[Federal Register Volume 81, Number 58 (Friday, March 25, 2016)][Rules and Regulations]
[Pages 16285-16890]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-04800]
Vol. 81
Friday,
No. 58
March 25, 2016
Part II
Book 2 of 3 Books
Pages 16285-16890
Department of Labor
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Occupational Safety and Health Administration
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29 CFR Parts 1910, 1915, and 1926
Occupational Exposure to Respirable Crystalline Silica; Final Rule
Federal Register / Vol. 81 , No. 58 / Friday, March 25, 2016 / Rules
and Regulations
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DEPARTMENT OF LABOR
Occupational Safety and Health Administration
29 CFR Parts 1910, 1915, and 1926
[Docket No. OSHA-2010-0034]
RIN 1218-AB70
Occupational Exposure to Respirable Crystalline Silica
AGENCY: Occupational Safety and Health Administration (OSHA),
Department of Labor.
ACTION: Final rule.
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SUMMARY: The Occupational Safety and Health Administration (OSHA) is
amending its existing standards for occupational exposure to respirable
crystalline silica. OSHA has determined that employees exposed to
respirable crystalline silica at the previous permissible exposure
limits face a significant risk of material impairment to their health.
The evidence in the record for this rulemaking indicates that workers
exposed to respirable crystalline silica are at increased risk of
developing silicosis and other non-malignant respiratory diseases, lung
cancer, and kidney disease. This final rule establishes a new
permissible exposure limit of 50 micrograms of respirable crystalline
silica per cubic meter of air (50 [mu]g/m\3\) as an 8-hour time-
weighted average in all industries covered by the rule. It also
includes other provisions to protect employees, such as requirements
for exposure assessment, methods for controlling exposure, respiratory
protection, medical surveillance, hazard communication, and
recordkeeping.
OSHA is issuing two separate standards--one for general industry
and maritime, and the other for construction--in order to tailor
requirements to the circumstances found in these sectors.
DATES: The final rule is effective on June 23, 2016. Start-up dates for
specific provisions are set in Sec. 1910.1053(l) for general industry
and maritime and in Sec. 1926.1153(k) for construction.
Collections of Information
There are a number of collections of information contained in this
final rule (see Section VIII, Paperwork Reduction Act). Notwithstanding
the general date of applicability that applies to all other
requirements contained in the final rule, affected parties do not have
to comply with the collections of information until the Department of
Labor publishes a separate notice in the Federal Register announcing
the Office of Management and Budget has approved them under the
Paperwork Reduction Act.
ADDRESSES: In accordance with 28 U.S.C. 2112(a), the Agency designates
Ann Rosenthal, Associate Solicitor of Labor for Occupational Safety and
Health, Office of the Solicitor of Labor, Room S-4004, U.S. Department
of Labor, 200 Constitution Avenue NW., Washington, DC 20210, to receive
petitions for review of the final rule.
FOR FURTHER INFORMATION CONTACT: For general information and press
inquiries, contact Frank Meilinger, Director, Office of Communications,
Room N-3647, OSHA, U.S. Department of Labor, 200 Constitution Avenue
NW., Washington, DC 20210; telephone (202) 693-1999; email
meilinger.francis2@dol.gov.
For technical inquiries, contact William Perry or David O'Connor,
Directorate of Standards and Guidance, Room N-3718, OSHA, U.S.
Department of Labor, 200 Constitution Avenue NW., Washington, DC 20210;
telephone (202) 693-1950.
SUPPLEMENTARY INFORMATION: The preamble to the rule on occupational
exposure to respirable crystalline silica follows this outline:
I. Executive Summary
II. Pertinent Legal Authority
III. Events Leading to the Final Standards
IV. Chemical Properties and Industrial Uses
V. Health Effects
VI. Final Quantitative Risk Assessment and Significance of Risk
VII. Summary of the Final Economic Analysis and Final Regulatory
Flexibility Analysis
VIII. Paperwork Reduction Act
IX. Federalism
X. State-Plan States
XI. Unfunded Mandates
XII. Protecting Children From Environmental Health and Safety Risks
XIII. Consultation and Coordination With Indian Tribal Governments
XIV. Environmental Impacts
XV. Summary and Explanation of the Standards
Scope
Definitions
Specified Exposure Control Methods
Alternative Exposure Control Methods
Permissible Exposure Limit
Exposure Assessment
Regulated Areas
Methods of Compliance
Respiratory Protection
Housekeeping
Written Exposure Control Plan
Medical Surveillance
Communication of Respirable Crystalline Silica Hazards to
Employees
Recordkeeping
Dates
Authority and Signature
Citation Method
In the docket for the respirable crystalline silica rulemaking,
found at http://www.regulations.gov, every submission was assigned a
document identification (ID) number that consists of the docket number
(OSHA-2010-0034) followed by an additional four-digit number. For
example, the document ID number for OSHA's Preliminary Economic
Analysis and Initial Regulatory Flexibility Analysis is OSHA-2010-0034-
1720. Some document ID numbers include one or more attachments, such as
the National Institute for Occupational Safety and Health (NIOSH)
prehearing submission (see Document ID OSHA 2010-0034-2177).
When citing exhibits in the docket, OSHA includes the term
"Document ID" followed by the last four digits of the document ID
number, the attachment number or other attachment identifier, if
applicable, page numbers (designated "p." or "Tr." for pages from a
hearing transcript), and in a limited number of cases a footnote number
(designated "Fn"). In a citation that contains two or more document
ID numbers, the document ID numbers are separated by semi-colons. For
example, a citation referring to the NIOSH prehearing comments and
NIOSH testimony obtained from the hearing transcript would be indicated
as follows: (Document ID 2177, Attachment B, pp. 2-3; 3579, Tr. 132).
In some sections, such as Section V, Health Effects, author names and
year of study publication are included before the document ID number in
a citation, for example: (Hughes et al., 2001, Document ID 1060;
McDonald et al., 2001, 1091; McDonald et al., 2005, 1092; Rando et al.,
2001, 0415).
I. Executive Summary
This final rule establishes a permissible exposure limit (PEL) for
respirable crystalline silica of 50 [mu]g/m\3\ as an 8-hour time-
weighted average (TWA) in all industries covered by the rule. In
addition to the PEL, the rule includes provisions to protect employees
such as requirements for exposure assessment, methods for controlling
exposure, respiratory protection, medical surveillance, hazard
communication, and recordkeeping. OSHA is issuing two separate
standards--one for general industry and maritime, and the other for
construction--in order to tailor requirements to the circumstances
found in these sectors. There are, however, numerous common elements in
the two standards.
The final rule is based on the requirements of the Occupational
Safety and Health Act (OSH Act) and court interpretations of the Act.
For health standards issued under section 6(b)(5) of the OSH Act, OSHA
is required to promulgate a standard that reduces significant risk to
the extent that it is technologically and economically feasible to do
so. See Section II, Pertinent Legal Authority, for a full discussion of
OSH Act legal requirements.
OSHA has conducted an extensive review of the literature on adverse
health effects associated with exposure to respirable crystalline
silica. OSHA has also developed estimates of the risk of silica-related
diseases, assuming exposure over a working lifetime, at the preceding
PELs as well as at the revised PEL and action level. Comments received
on OSHA's preliminary analysis, and the Agency's final findings, are
discussed in Section V, Health Effects, and Section VI, Final
Quantitative Risk Assessment and Significance of Risk. OSHA finds that
employees exposed to respirable crystalline silica at the preceding
PELs are at an increased risk of lung cancer mortality and silicosis
mortality and morbidity. Occupational exposures to respirable
crystalline silica also result in increased risk of death from other
nonmalignant respiratory diseases including chronic obstructive
pulmonary disease (COPD), and from kidney disease. OSHA further
concludes that exposure to respirable crystalline silica constitutes a
significant risk of material impairment to health and that the final
rule will substantially lower that risk. The Agency considers the level
of risk remaining at the new PEL to be significant. However, based on
the evidence evaluated during the rulemaking process, OSHA has
determined a PEL of 50 [mu]g/m\3\ is appropriate because it is the
lowest level feasible for all affected industries.
OSHA's examination of the technological and economic feasibility of
the rule is presented in the Final Economic Analysis and Final
Regulatory Flexibility Analysis (FEA), and is summarized in Section VII
of this preamble. OSHA concludes that the PEL of 50 [mu]g/m\3\ is
technologically feasible for most operations in all affected
industries, although it will be a technological challenge for several
affected sectors and will require the use of respirators for a limited
number of job categories and tasks.
OSHA developed quantitative estimates of the compliance costs of
the rule for each of the affected industry sectors. The estimated
compliance costs were compared with industry revenues and profits to
provide a screening analysis of the economic feasibility of complying
with the rule and an evaluation of the economic impacts. Industries
with unusually high costs as a percentage of revenues or profits were
further analyzed for possible economic feasibility issues. After
performing these analyses, OSHA finds that compliance with the
requirements of the rule is economically feasible in every affected
industry sector.
The final rule includes several major changes from the proposed
rule as a result of OSHA's analysis of comments and evidence received
during the comment periods and public hearings. The major changes are
summarized below and are fully discussed in Section XV, Summary and
Explanation of the Standards.
Scope. As proposed, the standards covered all occupational
exposures to respirable crystalline silica with the exception of
agricultural operations covered under 29 CFR part 1928. OSHA has made a
final determination to exclude exposures in general industry and
maritime where the employer has objective data demonstrating that
employee exposure to respirable crystalline silica will remain below 25
[mu]g/m\3\ as an 8-hour TWA under any foreseeable conditions. OSHA is
also excluding exposures in construction where employee exposure to
respirable crystalline silica will remain below 25 [mu]g/m\3\ as an 8-
hour TWA under any foreseeable conditions. In addition, OSHA is
excluding exposures that result from the processing of sorptive clays
from the scope of the rule. The standard for general industry and
maritime also allows employers to comply with the standard for
construction in certain circumstances.
Specified Exposure Control Methods. OSHA has revised the structure
of the standard for construction to emphasize the specified exposure
control methods for construction tasks that are presented in Table 1 of
the standard. Unlike in the proposed rule, employers who fully and
properly implement the controls listed on Table 1 are not separately
required to comply with the PEL, and are not subject to provisions for
exposure assessment and methods of compliance. The entries on Table 1
have also been revised extensively.
Protective Clothing. The proposed rule would have required use of
protective clothing in certain limited situations. The final rule does
not include requirements for use of protective clothing to address
exposure to respirable crystalline silica.
Housekeeping. The proposed rule would have prohibited use of
compressed air, dry sweeping, and dry brushing to clean clothing or
surfaces contaminated with crystalline silica where such activities
could contribute to employee exposure to respirable crystalline silica
that exceeds the PEL. The final rule allows for use of compressed air,
dry sweeping, and dry brushing in certain limited situations.
Written Exposure Control Plan. OSHA did not propose a requirement
for employers to develop a written exposure control plan. The final
rule includes a requirement for employers covered by the rule to
develop a written exposure control plan, and the standard for
construction includes a provision for a competent person (i.e., a
designated individual who is capable of identifying crystalline silica
hazards in the workplace and who possesses the authority to take
corrective measures to address them) to implement the written exposure
control plan.
Regulated Areas. OSHA proposed to provide employers covered by the
rule with the alternative of either establishing a regulated area or an
access control plan to limit access to areas where exposure to
respirable crystalline silica exceeds the PEL. The final standard for
general industry and maritime requires employers to establish a
regulated area in such circumstances. The final standard for
construction does not include a provision for regulated areas, but
includes a requirement that the written exposure control plan include
procedures used to restrict access to work areas, when necessary, to
minimize the numbers of employees exposed to respirable crystalline
silica and their level of exposure. The access control plan alternative
is not included in the final rule.
Medical Surveillance. The proposed rule would have required
employers to make medical surveillance available to employees exposed
to respirable crystalline silica above the PEL for 30 or more days per
year. The final standard for general industry and maritime requires
that medical surveillance be made available to employees exposed to
respirable crystalline silica at or above the action level of 25 [mu]g/
m\3\ as an 8-hour TWA for 30 or more days per year. The final standard
for construction requires that medical surveillance be made available
to employees who are required by the standard to use respirators for 30
or more days per year.
The rule requires the employer to obtain a written medical opinion
from physicians or other licensed health care professionals (PLHCPs)
for medical examinations provided under the rule but limits the information
provided to the employer to the date of the examination, a statement
that the examination has met the requirements of the standard, and any
recommended limitations on the employee's use of respirators. The
proposed rule would have required that such opinions contain additional
information, without requiring employee authorization, such as any
recommended limitations upon the employee's exposure to respirable
crystalline silica, and any referral to a specialist. In the final
rule, the written opinion provided to the employer will only include
recommended limitations on the employee's exposure to respirable
crystalline silica and referral to a specialist if the employee
provides written authorization. The final rule requires a separate
written medical report provided to the employee to include this
additional information, as well as detailed information related to the
employee's health.
Dates. OSHA proposed identical requirements for both standards: an
effective date 60 days after publication of the rule; a date for
compliance with all provisions except engineering controls and
laboratory requirements of 180 days after the effective date; a date
for compliance with engineering controls requirements, which was one
year after the effective date; and a date for compliance with
laboratory requirements of two years after the effective date.
OSHA has revised the proposed compliance dates in both standards.
The final rule is effective 90 days after publication. For general
industry and maritime, all obligations for compliance commence two
years after the effective date, with two exceptions: The obligation for
engineering controls commences five years after the effective date for
hydraulic fracturing operations in the oil and gas industry; and the
obligation for employers in general industry and maritime to offer
medical surveillance commences two years after the effective date for
employees exposed above the PEL, and four years after the effective
date for employees exposed at or above the action level. For
construction, all obligations for compliance commence one year after
the effective date, with the exception that certain requirements for
laboratory analysis commence two years after the effective date.
Under the OSH Act's legal standard directing OSHA to set health
standards based on findings of significant risk of material impairment
and technological and economic feasibility, OSHA does not use cost-
benefit analysis to determine the PEL or other aspects of the rule. It
does, however, determine and analyze costs and benefits for its own
informational purposes and to meet certain Executive Order
requirements, as discussed in Section VII. Summary of the Final
Economic Analysis and Final Regulatory Flexibility Analysis and in the
FEA. Table I-1--which is derived from material presented in Section VII
of this preamble--provides a summary of OSHA's best estimate of the
costs and benefits of the rule using a discount rate of 3 percent. As
shown, the rule is estimated to prevent 642 fatalities and 918
moderate-to-severe silicosis cases annually once it is fully effective,
and the estimated cost of the rule is $1,030 million annually. Also as
shown in Table I-1, the discounted monetized benefits of the rule are
estimated to be $8.7 billion annually, and the rule is estimated to
generate net benefits of approximately $7.7 billion annually.
II. Pertinent Legal Authority
The purpose of the Occupational Safety and Health Act (29 U.S.C.
651 et seq.) ("the Act" or "the OSH Act"), is "to assure so far as
possible every working man and woman in the Nation safe and healthful
working conditions and to preserve our human resources" (29 U.S.C.
651(b)). To achieve this goal Congress authorized the Secretary of
Labor ("the Secretary") "to set mandatory occupational safety and
health standards applicable to businesses affecting interstate
commerce" (29 U.S.C. 651(b)(3); see 29 U.S.C. 654(a) (requiring
employers to comply with OSHA standards), 655(a) (authorizing summary
adoption of existing consensus and federal standards within two years
of the Act's enactment), and 655(b) (authorizing promulgation,
modification or revocation of standards pursuant to notice and
comment)). The primary statutory provision relied upon by the Agency in
promulgating health standards is section 6(b)(5) of the Act; other
sections of the OSH Act, however, authorize the Occupational Safety and
Health Administration (OSHA) to require labeling and other appropriate
forms of warning, exposure assessment, medical examinations, and
recordkeeping in its standards (29 U.S.C. 655(b)(5), 655(b)(7),
657(c)).
The Act provides that in promulgating standards dealing with toxic
materials or harmful physical agents, such as respirable crystalline
silica, the Secretary shall set the standard which "most adequately
assures, to the extent feasible, on the basis of the best available
evidence, that no employee will suffer material impairment of health .
. . even if such employee has regular exposure to the hazard dealt with
by such standard for the period of his working life" (29 U.S.C.
655(b)(5)). Thus, "[w]hen Congress passed the Occupational Safety and
Health Act in 1970, it chose to place pre-eminent value on assuring
employees a safe and healthful working environment, limited only by the
feasibility of achieving such an environment" (American Textile Mfrs.
Institute, Inc. v. Donovan, 452 US 490, 541 (1981) ("Cotton Dust")).
OSHA proposed this new standard for respirable crystalline silica
and conducted its rulemaking pursuant to section 6(b)(5) of the Act
((29 U.S.C. 655(b)(5)). The preceding silica standard, however,
was adopted under the Secretary's authority in section 6(a) of the
OSH Act (29 U.S.C. 655(a)), to adopt national consensus
and established Federal standards within two years of the
Act's enactment (see 29 CFR 1910.1000 Table Z-1). Any rule that
"differs substantially from an existing national consensus standard"
must "better effectuate the purposes of this Act than the national
consensus standard" (29 U.S.C. 655(b)(8)). Several additional legal
requirements arise from the statutory language in sections 3(8) and
6(b)(5) of the Act (29 U.S.C. 652(8), 655(b)(5)). The remainder of this
section discusses these requirements, which OSHA must consider and meet
before it may promulgate this occupational health standard regulating
exposure to respirable crystalline silica.
Material Impairment of Health
Subject to the limitations discussed below, when setting standards
regulating exposure to toxic materials or harmful physical agents, the
Secretary is required to set health standards that ensure that "no
employee will suffer material impairment of health or functional
capacity..." (29 U.S.C. 655(b)(5)). OSHA has, under this section,
considered medical conditions such as irritation of the skin, eyes, and
respiratory system, asthma, and cancer to be material impairments of
health. What constitutes material impairment in any given case is a
policy determination on which OSHA is given substantial leeway. "OSHA
is not required to state with scientific certainty or precision the
exact point at which each type of [harm] becomes a material
impairment" (AFL-CIO v. OSHA, 965 F.2d 962, 975 (11th Cir. 1992)).
Courts have also noted that OSHA should consider all forms and degrees
of material impairment--not just death or serious physical harm (AFL-
CIO, 965 F.2d at 975). Thus the Agency has taken the position that
"subclinical" health effects, which may be precursors to more serious
disease, can be material impairments of health that OSHA should address
when feasible (43 FR 52952, 52954 (11/14/78) (Preamble to the Lead
Standard)).
Significant Risk
Section 3(8) of the Act requires that workplace safety and health
standards be "reasonably necessary or appropriate to provide safe or
healthful employment" (29 U.S.C. 652(8)). The Supreme Court, in its
decision on OSHA's benzene standard, interpreted section 3(8) to mean
that "before promulgating any standard, the Secretary must make a
finding that the workplaces in question are not safe" (Indus. Union
Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607, 642 (1980)
(plurality opinion) ("Benzene")). The Court further described OSHA's
obligation as requiring it to evaluate "whether significant risks are
present and can be eliminated or lessened by a change in practices"
(Benzene, 448 U.S. at 642). The Court's holding is consistent with
evidence in the legislative record, with regard to section 6(b)(5) of
the Act (29 U.S.C. 655(b)(5)), that Congress intended the Agency to
regulate unacceptably severe occupational hazards, and not "to
establish a utopia free from any hazards" or to address risks
comparable to those that exist in virtually any occupation or workplace
(116 Cong. Rec. 37614 (1970), Leg. Hist. 480-82). It is also consistent
with Section 6(g) of the OSH Act, which states that, in determining
regulatory priorities, "the Secretary shall give due regard to the
urgency of the need for mandatory safety and health standards for
particular industries, trades, crafts, occupations, businesses,
workplaces or work environments" (29 U.S.C. 655(g)).
The Supreme Court in Benzene clarified that OSHA has considerable
latitude in defining significant risk and in determining the
significance of any particular risk. The Court did not specify a means
to distinguish significant from insignificant risks, but rather
instructed OSHA to develop a reasonable approach to making its
significant risk determination. The Court stated that "[i]t is the
Agency's responsibility to determine, in the first instance, what it
considers to be a `significant' risk" (Benzene, 448 U.S. at 655), and
it did not "express any opinion on the... difficult question of
what factual determinations would warrant a conclusion that significant
risks are present which make promulgation of a new standard reasonably
necessary or appropriate" (Benzene, 448 U.S. at 659). The Court
stated, however, that the section 6(f) (29 U.S.C. 655(b)(f))
substantial evidence standard applicable to OSHA's significant risk
determination does not require the Agency "to support its finding that
a significant risk exists with anything approaching scientific
certainty" (Benzene, 448 U.S. at 656). Rather, OSHA may rely on "a
body of reputable scientific thought" to which "conservative
assumptions in interpreting the data..." may be applied, "risking
error on the side of overprotection" (Benzene, 448 U.S. at 656; see
also United Steelworkers of Am., AFL-CIO-CLC v. Marshall, 647 F.2d
1189, 1248 (D.C. Cir. 1980) ("Lead I") (noting the Benzene Court's
application of this principle to carcinogens and applying it to the
lead standard, which was not based on carcinogenic effects)). OSHA may
thus act with a "pronounced bias towards worker safety" in making its
risk determinations (Bldg & Constr. Trades Dep't v. Brock, 838 F.2d
1258, 1266 (D.C. Cir. 1988) ("Asbestos II").
The Supreme Court further recognized that what constitutes
"significant risk" is "not a mathematical straitjacket" (Benzene,
448 U.S. at 655) and will be "based largely on policy considerations"
(Benzene, 448 U.S. at 655 n.62). The Court gave the following example:
If...the odds are one in a billion that a person will die
from cancer by taking a drink of chlorinated water, the risk clearly
could not be considered significant. On the other hand, if the odds
are one in a thousand that regular inhalation of gasoline vapors
that are 2% benzene will be fatal, a reasonable person might well
consider the risk significant...(Benzene, 448 U.S. at 655).
Following Benzene, OSHA has, in many of its health standards,
considered the one-in-a-thousand metric when determining whether a
significant risk exists. Moreover, as "a prerequisite to more
stringent regulation" in all subsequent health standards, OSHA has,
consistent with the Benzene plurality decision, based each standard on
a finding of significant risk at the "then prevailing standard" of
exposure to the relevant hazardous substance (Asbestos II, 838 F.2d at
1263). Once a significant risk of material impairment of health is
demonstrated, it is of no import that the incidence of the illness may
be declining (see Nat'l Min. Assoc. v. Sec'y, U.S. Dep't of Labor, Nos.
14-11942, 14-12163, slip op. at 80 (11th Cir. Jan. 25, 2016)
(interpreting the Mine Act, 30 U.S.C. 811(a)(6)(A), which contains the
same language as section 6(b)(5) of the OSH Act requiring the Secretary
to set standards that assure no employee will suffer material
impairment of health)).
The Agency's final risk assessment is derived from existing
scientific and enforcement data and its final conclusions are made only
after considering all evidence in the rulemaking record. Courts
reviewing the validity of these standards have uniformly held the
Secretary to the significant risk standard first articulated by the
Benzene plurality and have generally upheld the Secretary's significant
risk determinations as supported by substantial evidence and "a
reasoned explanation for his policy assumptions and conclusions"
(Asbestos II, 838 F.2d at 1266).
Once OSHA makes its significant risk finding, the "more stringent
regulation" (Asbestos II, 838 F.2d at 1263) it promulgates must be
"reasonably necessary or appropriate" to reduce or eliminate that
risk, within the meaning of section 3(8) of the Act (29 U.S.C. 652(8))
and Benzene (448 U.S. at 642) (see Asbestos II, 838 F.2d at 1269). The
courts have interpreted section 6(b)(5) of the OSH Act as requiring
OSHA to set the standard that eliminates or reduces risk to the lowest
feasible level; as discussed below, the limits of technological and
economic feasibility usually determine where the new standard is set
(see UAW v. Pendergrass, 878 F.2d 389, 390 (D.C. Cir. 1989)). In
choosing among regulatory alternatives, however, "[t]he determination
that [one standard] is appropriate, as opposed to a marginally [more or
less protective] standard, is a technical decision entrusted to the
expertise of the agency..." (Nat'l Mining Ass'n v. Mine Safety and
Health Admin., 116 F.3d 520, 528 (D.C. Cir. 1997)) (analyzing a Mine
Safety and Health Administration ("MSHA") standard under the Benzene
significant risk standard). In making its choice, OSHA may incorporate
a margin of safety even if it theoretically regulates below the lower
limit of significant risk (Nat'l Mining Ass'n, 116 F.3d at 528 (citing
American Petroleum Inst. v. Costle, 665 F.2d 1176, 1186 (D.C. Cir.
1982))).
Working Life Assumption
The OSH Act requires OSHA to set the standard that most adequately
protects employees against harmful workplace exposures for the period
of their "working life" (29 U.S.C. 655(b)(5)). OSHA's longstanding
policy is to define "working life" as constituting 45 years; thus, it
assumes 45 years of exposure when evaluating the risk of material
impairment to health caused by a toxic or hazardous substance. This
policy is not based on empirical data that most employees are exposed
to a particular hazard for 45 years. Instead, OSHA has adopted the
practice to be consistent with the statutory directive that "no
employee" suffer material impairment of health "even if" such
employee is exposed to the hazard for the period of his or her working
life (see 74 FR 44796 (8/31/09)). OSHA's policy was given judicial
approval in a challenge to an OSHA standard that lowered the
permissible exposure limit (PEL) for asbestos (Asbestos II, 838 F.2d at
1264-1265). In that case, the petitioners claimed that the median
duration of employment in the affected industry sectors was only five
years. Therefore, according to petitioners, OSHA erred in assuming a
45-year working life in calculating the risk of health effects caused
by asbestos exposure. The D.C. Circuit disagreed, stating,
Even if it is only the rare worker who stays with asbestos-
related tasks for 45 years, that worker would face a 64/1000 excess
risk of contracting cancer; Congress clearly authorized OSHA to
protect such a worker (Asbestos II, 838 F.2d at 1264-1265).
OSHA might calculate the health risks of exposure, and the related
benefits of lowering the exposure limit, based on an assumption of a
shorter working life, such as 25 years, but such estimates are for
informational purposes only.
Best Available Evidence
Section 6(b)(5) of the Act requires OSHA to set standards "on the
basis of the best available evidence" and to consider the "latest
available scientific data in the field" (29 U.S.C. 655(b)(5)). As
noted above, the Supreme Court, in its Benzene decision, explained that
OSHA must look to "a body of reputable scientific thought" in making
its material harm and significant risk determinations, while noting
that a reviewing court must "give OSHA some leeway where its findings
must be made on the frontiers of scientific knowledge" (Benzene, 448
U.S. at 656). The courts of appeals have afforded OSHA similar latitude
to issue health standards in the face of scientific uncertainty. The
Second Circuit, in upholding the vinyl chloride standard, stated:
...the ultimate facts here in dispute are `on the frontiers
of scientific knowledge', and, though the factual finger points, it
does not conclude. Under the command of OSHA, it remains the duty of
the Secretary to act to protect the workingman, and to act even in
circumstances where existing methodology or research is deficient
(Society of the Plastics Industry, Inc. v. OSHA, 509 F.2d 1301, 1308
(2d Cir. 1975) (quoting Indus. Union Dep't, AFL-CIO v. Hodgson, 499
F.2d 467, 474 (D.C. Cir. 1974) ("Asbestos I"))).
The D.C. Circuit, in upholding the cotton dust standard, stated:
"OSHA's mandate necessarily requires it to act even if information is
incomplete when the best available evidence indicates a serious threat
to the health of workers" (Am. Fed'n of Labor & Cong. of Indus. Orgs.
v. Marshall, 617 F.2d 636, 651 (D.C. Cir. 1979), aff'd in part and
vacated in part on other grounds, American Textile Mfrs. Inst., Inc. v.
Donovan, 452 U.S. 490 (1981)).
When there is disputed scientific evidence, OSHA must review the
evidence on both sides and "reasonably resolve" the dispute (Pub.
Citizen Health Research Grp. v. Tyson, 796 F.2d 1479, 1500 (D.C. Cir.
1986)). In Public Citizen, there was disputed scientific evidence
regarding whether there was a threshold exposure level for the health
effects of ethylene oxide. The Court noted that, where "OSHA has the
expertise we lack and it has exercised that expertise by carefully
reviewing the scientific data," a dispute within the scientific
community is not occasion for it to take sides about which view is
correct (Pub. Citizen Health Research Grp., 796 F.2d at 1500).
"Indeed, Congress did `not [intend] that the Secretary be paralyzed by
debate surrounding diverse medical opinions' " (Pub. Citizen Health
Research Grp., 796 F.2d at 1497 (quoting H.R.Rep. No. 91-1291, 91st
Cong., 2d Sess. 18 (1970), reprinted in Legislative History of the
Occupational Safety and Health Act of 1970 at 848 (1971))).
A recent decision by the Eleventh Circuit Court of Appeals
upholding a coal dust standard promulgated by MSHA emphasized that
courts should give "an extreme degree of deference to the agency when
it is evaluating scientific data within its technical expertise"
(Nat'l Min. Assoc. v. Sec'y, U.S. Dep't of Labor, Nos. 14-11942, 14-
12163, slip op. at 43 (11th Cir. Jan. 25, 2016) (quoting Kennecott
Greens Creek Min. Co. v. MSHA, 476 F.3d 946, 954-955 (D.C. Cir. 2007)
(internal quotation marks omitted)). The Court emphasized that because
the Mine Act, like the OSH Act, "evinces a clear bias in favor of [ ]
health and safety," the agency's responsibility to use the best
evidence and consider feasibility should not be used as a counterweight
to the agency's duty to protect the lives and health of workers (Nat'l
Min. Assoc., Nos. 14-11942, 14-12163, slip op. at 43 (11th Cir. Jan.
25, 2016)).
Feasibility
The OSH Act requires that, in setting a standard, OSHA must
eliminate the risk of material health impairment "to the extent
feasible" (29 U.S.C. 655(b)(5)). The statutory mandate to consider the
feasibility of the standard encompasses both technological and economic
feasibility; these analyses have been done primarily on an industry-by-
industry basis (Lead I, 647 F.2d at 1264, 1301) in general industry.
The Agency has also used application groups, defined by common tasks,
as the structure for its feasibility analyses in construction (Pub.
Citizen Health Research Grp. v. OSHA, 557 F.3d 165, 177-179 (3d Cir.
2009) ("Chromium (VI)"). The Supreme Court has broadly defined
feasible as "capable of being done" (Cotton Dust, 452 U.S. at 509-510).
Although OSHA must set the most protective PEL that the Agency
finds to be technologically and economically feasible, it retains
discretion to set a uniform PEL even when the evidence demonstrates
that certain industries or operations could reasonably be expected to
meet a lower PEL. OSHA health standards generally set a single PEL for
all affected employers; OSHA exercised this discretion most recently in
its final rule on occupational exposure to chromium (VI) (71 FR 10100,
10337-10338 (2/28/2006); see also 62 FR 1494, 1575 (1/10/97) (methylene
chloride)). In its decision upholding the chromium (VI) standard,
including the uniform PEL, the Court of Appeals for the Third Circuit
addressed this issue as one of deference, stating "OSHA's decision to
select a uniform exposure limit is a legislative policy decision that
we will uphold as long as it was reasonably drawn from the record"
(Chromium (VI), 557 F.3d at 183 (3d Cir. 2009)); see also Am. Iron &
Steel Inst. v. OSHA, 577 F.2d 825, 833 (3d Cir. 1978)). OSHA's reasons
for choosing one chromium (VI) PEL, rather than imposing different PELs
on different application groups or industries, included: Multiple PELs
would create enforcement and compliance problems because many
workplaces, and even workers, were affected by multiple categories of
chromium (VI) exposure; discerning individual PELs for different groups
of establishments would impose a huge evidentiary burden on the Agency
and unnecessarily delay implementation of the standard; and a uniform
PEL would, by eliminating confusion and simplifying compliance, enhance
worker protection (Chromium (VI), 557 F.3d at 173, 183-184). The Court
held that OSHA's rationale for choosing a uniform PEL, despite evidence
that some application groups or industries could meet a lower PEL, was
reasonably drawn from the record and that the Agency's decision was
within its discretion and supported by past practice (Chromium (VI),
557 F.3d at 183-184).
Technological Feasibility
A standard is technologically feasible if the protective measures
it requires already exist, can be brought into existence with available
technology, or can be created with technology that can reasonably be
expected to be developed (Lead I, 647 F.2d at 1272; Amer. Iron & Steel
Inst. v. OSHA, 939 F.2d 975, 980 (D.C. Cir. 1991) ("Lead II")). While
the test for technological feasibility is normally articulated in terms
of the ability of employers to decrease exposures to the PEL,
provisions such as exposure measurement requirements must also be
technologically feasible (Forging Indus. Ass'n v. Sec'y of Labor, 773
F.2d 1436, 1453 (4th Cir. 1985)).
OSHA's standards may be "technology forcing," i.e., where the
Agency gives an industry a reasonable amount of time to develop new
technologies, OSHA is not bound by the "technological status quo"
(Lead I, 647 F.2d at 1264); see also Kennecott Greens Creek Min. Co. v.
MSHA, 476 F.3d 946, 957 (D.C. Cir. 2007) (MSHA standards, like OSHA
standards, may be technology-forcing); Nat'l Petrochemical & Refiners
Ass'n v. EPA, 287 F.3d 1130, 1136 (D.C. Cir. 2002) (agency is "not
obliged to provide detailed solutions to every engineering problem,"
but only to "identify the major steps for improvement and give
plausible reasons for its belief that the industry will be able to
solve those problems in the time remaining.").
In its Lead decisions, the D.C. Circuit described OSHA's obligation
to demonstrate the technological feasibility of reducing occupational
exposure to a hazardous substance.
[W]ithin the limits of the best available evidence...OSHA
must prove a reasonable possibility that the typical firm will be
able to develop and install engineering and work practice controls
that can meet the PEL in most of its operations...The effect of
such proof is to establish a presumption that industry can meet the
PEL without relying on respirators...Insufficient proof of
technological feasibility for a few isolated operations within an
industry, or even OSHA's concession that respirators will be
necessary in a few such operations, will not undermine this general
presumption in favor of feasibility. Rather, in such operations
firms will remain responsible for installing engineering and work
practice controls to the extent feasible, and for using them to
reduce...exposure as far as these controls can do so (Lead I,
647 F.2d at 1272).
Additionally, the D.C. Circuit explained that "[f]easibility of
compliance turns on whether exposure levels at or below [the PEL] can
be met in most operations most of the time..." (Lead II, 939 F.2d
at 990).
Courts have given OSHA significant deference in reviewing its
technological feasibility findings.
So long as we require OSHA to show that any required means of
compliance, even if it carries no guarantee of meeting the PEL, will
substantially lower...exposure, we can uphold OSHA's
determination that every firm must exploit all possible means to
meet the standard (Lead I, 647 F.2d at 1273).
Even in the face of significant uncertainty about technological
feasibility in a given industry, OSHA has been granted broad discretion
in making its findings (Lead I, 647 F.2d at 1285).
OSHA cannot let workers suffer while it awaits...scientific
certainty. It can and must make reasonable [technological
feasibility] predictions on the basis of `credible sources of
information,' whether data from existing plants or expert testimony
(Lead I, 647 F.2d at 1266 (quoting Am. Fed'n of Labor & Cong. of
Indus. Orgs., 617 F.2d at 658)).
For example, in Lead I, the D.C. Circuit allowed OSHA to use, as
best available evidence, information about new and expensive industrial
smelting processes that had not yet been adopted in the U.S. and would
require the rebuilding of plants (Lead I, 647 F.2d at 1283-1284). Even
under circumstances where OSHA's feasibility findings were less certain
and the Agency was relying on its "legitimate policy of technology
forcing," the D.C. Circuit approved of OSHA's feasibility findings
when the Agency granted lengthy phase-in periods to allow particular
industries time to comply (Lead I, 647 F.2d at 1279-1281, 1285).
OSHA is permitted to adopt a standard that some employers will not
be able to meet some of the time, with employers limited to challenging
feasibility at the enforcement stage (Lead I, 647 F.2d at 1273 & n.
125; Asbestos II, 838 F.2d at 1268). Even when the Agency recognized
that it might have to balance its general feasibility findings with
flexible enforcement of the standard in individual cases, the courts of
appeals have generally upheld OSHA's technological feasibility findings
(Lead II, 939 F.2d at 980; see Lead I, 647 F.2d at 1266-1273; Asbestos
II, 838 F.2d at 1268). Flexible enforcement policies have been approved
where there is variability in measurement of the regulated hazardous
substance or where exposures can fluctuate uncontrollably (Asbestos II,
838 F.2d at 1267-1268; Lead II, 939 F.2d at 991). A common means of
dealing with the measurement variability inherent in sampling and
analysis is for the Agency to add the standard sampling error to its
exposure measurements before determining whether to issue a citation
(e.g., 51 FR 22612, 22654 (06/20/86) (Preamble to the Asbestos
Standard)).
Economic Feasibility
In addition to technological feasibility, OSHA is required to
demonstrate that its standards are economically feasible. A reviewing
court will examine the cost of compliance with an OSHA standard "in
relation to the financial health and profitability of the industry
and the likely effect of such costs on unit consumer prices..."
(Lead I, 647 F.2d at 1265 (omitting citation)). As articulated by
the D.C. Circuit in Lead I,
OSHA must construct a reasonable estimate of compliance costs
and demonstrate a reasonable likelihood that these costs will not
threaten the existence or competitive structure of an industry, even
if it does portend disaster for some marginal firms (Lead I, 647
F.2d at 1272).
A reasonable estimate entails assessing "the likely range of costs
and the likely effects of those costs on the industry" (Lead I, 647
F.2d at 1266). As with OSHA's consideration of scientific data and
control technology, however, the estimates need not be precise (Cotton
Dust, 452 U.S. at 528-29 & n.54) as long as they are adequately
explained. Thus, as the D.C. Circuit further explained:
Standards may be economically feasible even though, from the
standpoint of employers, they are financially burdensome and affect
profit margins adversely. Nor does the concept of economic
feasibility necessarily guarantee the continued existence of
individual employers. It would appear to be consistent with the
purposes of the Act to envisage the economic demise of an employer
who has lagged behind the rest of the industry in protecting the
health and safety of employees and is consequently financially
unable to comply with new standards as quickly as other employers.
As the effect becomes more widespread within an industry, the
problem of economic feasibility becomes more pressing (Asbestos I,
499 F.2d. at 478).
OSHA standards therefore satisfy the economic feasibility criterion
even if they impose significant costs on regulated industries so long
as they do not cause massive economic dislocations within a particular
industry or imperil the very existence of the industry (Lead II, 939
F.2d at 980; Lead I, 647 F.2d at 1272; Asbestos I, 499 F.2d. at 478).
As with its other legal findings, OSHA "is not required to prove
economic feasibility with certainty, but is required to use the best
available evidence and to support its conclusions with substantial
evidence" (Lead II, 939 F.2d at 980-981) (citing Lead I, 647 F.2d at
1267)). Granting industries additional time to comply with new PELs may
enhance the economic, as well as technological, feasibility of a
standard (Lead I, 647 F.2d at 1265).
Because section 6(b)(5) of the Act explicitly imposes the "to the
extent feasible" limitation on the setting of health standards, OSHA
is not permitted to use cost-benefit analysis to make its standards-
setting decisions (29 U.S.C. 655(b)(5)).
Congress itself defined the basic relationship between costs and
benefits, by placing the "benefit" of worker health above all
other considerations save those making attainment of this
"benefit" unachievable. Any standard based on a balancing of costs
and benefits by the Secretary that strikes a different balance than
that struck by Congress would be inconsistent with the command set
forth in Sec. 6(b)(5) (Cotton Dust, 452 U.S. at 509).
Thus, while OSHA estimates the costs and benefits of its proposed
and final rules, these calculations do not form the basis for the
Agency's regulatory decisions; rather, they are performed in
acknowledgement of requirements such as those in Executive Orders 12866
and 13563.
Structure of OSHA Health Standards
OSHA's health standards traditionally incorporate a comprehensive
approach to reducing occupational disease. OSHA substance-specific
health standards generally include the "hierarchy of controls,"
which, as a matter of OSHA's preferred policy, mandates that employers
install and implement all feasible engineering and work practice
controls before respirators may be used. The Agency's adherence to the
hierarchy of controls has been upheld by the courts (ASARCO, Inc. v.
OSHA, 746 F.2d 483, 496-498 (9th Cir. 1984); Am. Iron & Steel Inst. v.
OSHA, 182 F.3d 1261, 1271 (11th Cir. 1999)). In fact, courts view the
legal standard for proving technological feasibility as incorporating
the hierarchy:
OSHA must prove a reasonable possibility that the typical firm
will be able to develop and install engineering and work practice
controls that can meet the PEL in most of its operations....The
effect of such proof is to establish a presumption that industry can
meet the PEL without relying on respirators (Lead I, 647 F.2d at
1272).
The hierarchy of controls focuses on removing harmful materials at
their source. OSHA allows employers to rely on respiratory protection
to protect their employees only when engineering and work practice
controls are insufficient or infeasible. In fact, in the control of
"those occupational diseases caused by breathing air contaminated with
harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors,"
the employers' primary objective "shall be to prevent atmospheric
contamination. This shall be accomplished as far as feasible by
accepted engineering control measures (for example, enclosure or
confinement of the operation, general and local ventilation, and
substitution of less toxic materials). When effective engineering
controls are not feasible, or while they are being instituted,
appropriate respirators shall be used pursuant to this section" (29
CFR 1910.134).
The reasons supporting OSHA's continued reliance on the hierarchy
of controls, as well as its reasons for limiting the use of
respirators, are numerous and grounded in good industrial hygiene
principles (see Section XV, Summary and Explanation of the Standards,
Methods of Compliance). Courts have upheld OSHA's emphasis on
engineering and work practice controls over personal protective
equipment in challenges to previous health standards, such as chromium
(VI): "Nothing in...any case reviewing an airborne toxin standard,
can be read to support a technological feasibility rule that would
effectively encourage the routine and widespread use of respirators to
comply with a PEL" (Chromium (VI), 557 F.3d at 179; see Am. Fed'n of
Labor & Cong. of Indus. Orgs. v. Marshall, 617 F.2d 636, 653 (D.C. Cir.
1979) cert. granted, judgment vacated sub nom. Cotton Warehouse Ass'n
v. Marshall, 449 U.S. 809 (1980) and aff'd in part, vacated in part sub
nom. Am. Textile Mfrs. Inst., Inc. v. Donovan, 452 U.S. 490 (1981)
(finding "uncontradicted testimony in the record that respirators can
cause severe physical discomfort and create safety problems of their
own")).
In health standards such as this one, the hierarchy of controls is
augmented by ancillary provisions. These provisions work with the
hierarchy of controls and personal protective equipment requirements to
provide comprehensive protection to employees in affected workplaces.
Such provisions typically include exposure assessment, medical
surveillance, hazard communication, and recordkeeping. This approach is
recognized as effective in dealing with air contaminants such as
respirable crystalline silica; for example, the industry standards for
respirable crystalline silica, ASTM E 1132-06, Standard Practice for
Health Requirements Relating to Occupational Exposure to Respirable
Crystalline Silica, and ASTM E 2626-09, Standard Practice for
Controlling Occupational Exposure to Respirable Crystalline Silica for
Construction and Demolition Activities, take a similar comprehensive
approach (Document ID 1466; 1504).
The OSH Act compels OSHA to require all feasible measures for
reducing significant health risks (29 U.S.C. 655(b)(5); Pub. Citizen
Health Research Grp., 796 F.2d at 1505 ("if in fact a STEL [short-term
exposure limit] would further reduce a significant health risk and is
feasible to implement, then the OSH Act compels the agency to adopt it
(barring alternative avenues to the same result)"). When there is
significant risk below the PEL, as is the case with respirable
crystalline silica, the DC Circuit indicated that OSHA should
use its regulatory authority to impose additional requirements
on employers when those requirements will result in a greater than de
minimis incremental benefit to workers' health (Asbestos II, 838 F.2d
at 1274). The Supreme Court alluded to a similar issue in Benzene,
pointing out that "in setting a permissible exposure level in reliance
on less-than-perfect methods, OSHA would have the benefit of a backstop
in the form of monitoring and medical testing" (Benzene, 448 U.S. at
657). OSHA believes that the ancillary provisions in this final
standard provide significant benefits to worker health by providing
additional layers and types of protection to employees exposed to
respirable crystalline silica.
Finally, while OSHA is bound by evidence in the rulemaking record,
and generally looks to its prior standards for guidance on how to
structure and specify requirements in a new standard, it is not limited
to past approaches to regulation. In promulgating health standards,
"[w]henever practicable, the standard promulgated shall be expressed
in terms of objective criteria and of the performance desired" (29
U.S.C. 655(b)(5)). In cases of industries or tasks presenting unique
challenges in terms of assessing and controlling exposures, it may be
more practicable and provide greater certainty to require specific
controls with a demonstrated track record of efficacy in reducing
exposures and, therefore, risk (especially when supplemented by
appropriate respirator usage). Such an approach could more effectively
protect workers than the traditional exposure assessment-and-control
approach when exposures may vary because of factors such as changing
environmental conditions or materials, and an assessment may not
reflect typical exposures associated with a task or operation. As
discussed at length in Section XV, Summary and Explanation of the
Standards, the specified exposure control measures option in the
construction standard (i.e., Table 1, in paragraph (c)(1)) for
respirable crystalline silica represents the type of innovative,
objective approach available to the Secretary when fashioning a rule
under these circumstances.
III. Events Leading to the Final Standards
The Occupational Safety and Health Administration's (OSHA's)
previous standards for workplace exposure to respirable crystalline
silica were adopted in 1971, pursuant to section 6(a) of the
Occupational Safety and Health Act (29 U.S.C. 651 et seq.) ("the Act"
or "the OSH Act") (36 FR 10466 (5/29/71)). Section 6(a) (29 U.S.C.
655(a)) authorized OSHA, in the first two years after the effective
date of the Act, to promulgate "start-up" standards, on an expedited
basis and without public hearing or comment, based on national
consensus or established Federal standards that improved employee
safety or health. Pursuant to that authority, OSHA in 1971 promulgated
approximately 425 permissible exposure limits (PELs) for air
contaminants, including crystalline silica, which were derived
principally from Federal standards applicable to government contractors
under the Walsh-Healey Public Contracts Act, 41 U.S.C. 35, and the
Contract Work Hours and Safety Standards Act (commonly known as the
Construction Safety Act), 40 U.S.C. 333. The Walsh-Healey Act and
Construction Safety Act standards had been adopted primarily from
recommendations of the American Conference of Governmental Industrial
Hygienists (ACGIH).
For general industry (see 29 CFR 1910.1000, Table Z-3), the PEL for
crystalline silica in the form of respirable quartz was based on two
alternative formulas: (1) A particle-count formula,
PELmppcf=250/(% quartz + 5) as respirable dust; and (2) a
mass formula proposed by ACGIH in 1968, PEL=(10 mg/m3)/(%
quartz + 2) as respirable dust. The general industry PELs for
crystalline silica in the form of cristobalite and tridymite were one-
half of the value calculated from either of the above two formulas for
quartz. For construction (see 29 CFR 1926.55, Appendix A) and shipyards
(see 29 CFR 1915.1000, Table Z), the formula for the PEL for
crystalline silica in the form of quartz (PELmppcf=250/(%
quartz + 5) as respirable dust), which requires particle counting, was
derived from the 1970 ACGIH threshold limit value (TLV).\1\ Based on
the formulas, the PELs for quartz, expressed as time-weighted averages
(TWAs), were approximately equivalent to 100 [mu]g/m3 for
general industry and 250 [mu]g/m3 for construction and
shipyards. The PELs were not supplemented by additional protective
provisions--such as medical surveillance requirements--as are included
in other OSHA standards. OSHA believes that the formula based on
particle-counting technology used in the general industry,
construction, and shipyard PELs has been rendered obsolete by
respirable mass (gravimetric) sampling.
---------------------------------------------------------------------------
\1\ The Mineral Dusts tables that contain the silica PELs for
construction and shipyards do not clearly express PELs for
cristobalite and tridymite. 29 CFR 1926.55; 29 CFR 1915.1000. This
lack of textual clarity likely results from a transcription error in
the Code of Federal Regulations. OSHA's final rule provides the same
PEL for quartz, cristobalite, and tridymite in general industry,
maritime, and construction.
---------------------------------------------------------------------------
In 1974, the National Institute for Occupational Safety and Health
(NIOSH), an agency within the Department of Health and Human Services
created by the OSH Act and designed to carry out research and recommend
standards for occupational safety and health hazards, evaluated
crystalline silica as a workplace hazard and issued criteria for a
recommended standard (29 U.S.C. 669, 671; Document ID 0388). NIOSH
recommended that occupational exposure to crystalline silica be
controlled so that no worker is exposed to a TWA of free (respirable
crystalline) silica greater than 50 [mu]g/m3 as determined
by a full-shift sample for up to a 10-hour workday over a 40-hour
workweek. The document also recommended a number of ancillary
provisions for a standard, such as exposure monitoring and medical
surveillance.
In December 1974, OSHA published an Advance Notice of Proposed
Rulemaking (ANPRM) based on the recommendations in the NIOSH criteria
document (39 FR 44771 (12/27/74)). In the ANPRM, OSHA solicited
"public participation on the issues of whether a new standard for
crystalline silica should be issued on the basis of the [NIOSH]
criteria or any other information, and, if so, what should be the
contents of a proposed standard for crystalline silica" (39 FR at
44771). OSHA also set forth the particular issues of concern on which
comments were requested. The Agency did not issue a proposed rule or
pursue a final rule for crystalline silica at that time.
As information on the health effects of silica exposure developed
during the 1980s and 1990s, national and international classification
organizations came to recognize crystalline silica as a human
carcinogen. In June 1986, the International Agency for Research on
Cancer (IARC), which is the specialized cancer agency within the World
Health Organization, evaluated the available evidence regarding
crystalline silica carcinogenicity and concluded, in 1987, that
crystalline silica is probably carcinogenic to humans
(http://monographs.iarc.fr/ENG/Monographs/suppl7/Suppl7.pdf). An
IARC working group met again in October 1996 to evaluate the complete
body of research, including research that had been conducted since the
initial 1986 evaluation. IARC concluded, more decisively this time,
that "crystalline silica inhaled in the form of quartz or cristobalite
from occupational sources is carcinogenic to humans" (Document ID
2258, Attachment 8, p. 211). In 2012, IARC reaffirmed that
"Crystalline silica in the form of quartz or cristobalite dust is
carcinogenic to humans" (Document ID 1473, p. 396).
In 1991, in the Sixth Annual Report on Carcinogens, the U.S.
National Toxicology Program (NTP), within the U.S. Department of Health
and Human Services, concluded that respirable crystalline silica was
"reasonably anticipated to be a human carcinogen" (as referenced in
Document ID 1417, p. 1). NTP reevaluated the available evidence and
concluded, in the Ninth Report on Carcinogens, that "respirable
crystalline silica (RCS), primarily quartz dust occurring in industrial
and occupational settings, is known to be a human carcinogen, based on
sufficient evidence of carcinogenicity from studies in humans
indicating a causal relationship between exposure to RCS and increased
lung cancer rates in workers exposed to crystalline silica dust"
(Document ID 1417, p. 1). ACGIH listed respirable crystalline silica
(in the form of quartz) as a suspected human carcinogen in 2000, while
lowering the TLV to 0.05 mg/m3 (50 [mu]g/m3)
(Document ID 1503, p. 15). ACGIH subsequently lowered the TLV for
crystalline silica to 0.025 mg/m3 (25 [mu]g/m3)
in 2006, which is ACGIH's current recommended exposure limit (Document
ID 1503, pp. 1, 15).
In 1989, OSHA established 8-hour TWA PELs of 0.1 mg/m3
(100 [mu]g/m3) for quartz and 0.05 mg/m3 (50
[mu]g/m3) for cristobalite and tridymite, as part of the Air
Contaminants final rule for general industry (54 FR 2332 (1/19/89)).
OSHA stated that these limits presented no substantial change from the
Agency's former formula limits, but would simplify sampling procedures.
In providing comments on the proposed rule, NIOSH recommended that
crystalline silica be considered a potential carcinogen.
In 1992, OSHA, as part of the Air Contaminants proposed rule for
maritime, construction, and agriculture, proposed the same PELs as for
general industry, to make the PELs consistent across all the OSHA-
regulated sectors (57 FR 26002 (6/12/92)). However, the U.S. Court of
Appeals for the Eleventh Circuit vacated the 1989 Air Contaminants
final rule for general industry (Am. Fed'n of Labor and Cong. of Indus.
Orgs. v. OSHA, 965 F.2d 962 (1992)), and also mooted the proposed rule
for maritime, construction, and agriculture. The Court's decision to
vacate the rule forced the Agency to return to the original 1971 PELs
for all compounds, including silica, adopted as section 6(a) standards.
In 1994, OSHA initiated a process to determine which safety and
health hazards in the U.S. needed the most attention. A priority
planning committee included safety and health experts from OSHA, NIOSH,
and the Mine Safety and Health Administration (MSHA). The committee
reviewed available information on occupational deaths, injuries, and
illnesses and communicated extensively with representatives of labor,
industry, professional and academic organizations, the States,
voluntary standards organizations, and the public. The OSHA National
Advisory Committee on Occupational Safety and Health and the Advisory
Committee on Construction Safety and Health (ACCSH) also made
recommendations. Rulemaking for crystalline silica exposure was one of
the priorities designated by this process. OSHA indicated that
crystalline silica would be added to the Agency's regulatory agenda as
other standards were completed and resources became available.
In 1996, OSHA instituted a Special Emphasis Program (SEP) to step
up enforcement of the crystalline silica standards. The SEP was
intended to reduce worker silica dust exposures that can cause
silicosis and lung cancer. It included extensive outreach designed to
educate and train employers and employees about the hazards of silica
and how to control them, as well as inspections to enforce the
standards. Among the outreach materials available were slides
presenting information on hazard recognition and crystalline silica
control technology, a video on crystalline silica and silicosis, and
informational cards for workers explaining crystalline silica, health
effects related to exposure, and methods of control. The SEP provided
guidance for targeting inspections of worksites that had employees at
risk of developing silicosis. The inspections resulted in the
collection of exposure data from the various worksites visited by
OSHA's compliance officers.
As a follow-up to the SEP, OSHA undertook numerous non-regulatory
actions to address silica exposures. For example, in October of 1996,
OSHA launched a joint silicosis prevention effort with MSHA, NIOSH, and
the American Lung Association (see https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=14110). This public
education campaign involved distribution of materials on how to prevent
silicosis, including a guide for working safely with silica and
stickers for hard hats to remind workers of crystalline silica hazards.
Spanish language versions of these materials were also made available.
OSHA and MSHA inspectors distributed materials at mines, construction
sites, and other affected workplaces. The joint silicosis prevention
effort included a National Conference to Eliminate Silicosis in
Washington, DC, in March of 1997, which brought together approximately
650 participants from labor, business, government, and the health and
safety professions to exchange ideas and share solutions regarding the
goal of eliminating silicosis (see https://industrydocuments.library.ucsf.edu/documentstore/s/h/d/p//shdp0052/shdp0052.pdf).
In 1997, OSHA announced in its Unified Agenda under Long-Term
Actions that it planned to publish a proposed rule on crystalline
silica
...because the agency has concluded that there will be no
significant progress in the prevention of silica-related diseases
without the adoption of a full and comprehensive silica standard,
including provisions for product substitution, engineering controls,
training and education, respiratory protection and medical screening
and surveillance. A full standard will improve worker protection,
ensure adequate prevention programs, and further reduce silica-
related diseases (62 FR 57755, 57758 (10/29/97)).
In November 1998, OSHA moved "Occupational Exposure to Crystalline
Silica" to the pre-rule stage in the Regulatory Plan (63 FR 61284,
61303-61304 (11/9/98)). OSHA held a series of stakeholder meetings in
1999 and 2000 to get input on the rulemaking. Stakeholder meetings for
all industry sectors were held in Washington, Chicago, and San
Francisco. A separate stakeholder meeting for the construction sector
was held in Atlanta.
OSHA initiated Small Business Regulatory Enforcement Fairness Act
(SBREFA) proceedings in 2003, seeking the advice of small business
representatives on the proposed rule (68 FR 30583, 30584 (5/27/03)).
The SBREFA panel, including representatives from OSHA, the Small
Business Administration's Office of Advocacy, and the Office of
Management and Budget (OMB), was convened on October 20, 2003.
The panel conferred with small entity representatives (SERs)
from general industry, maritime, and construction on
November 10 and 12, 2003, and delivered its final report,
which included comments from the SERs and recommendations to
OSHA for the proposed rule, to OSHA's Assistant Secretary on December
19, 2003 (Document ID 0937).
In 2003, OSHA examined enforcement data for the years 1997 to 2002
and identified high rates of noncompliance with the OSHA respirable
crystalline silica PELs, particularly in construction. This period
covers the first five years of the SEP. These enforcement data,
presented in Table III-1, indicate that 24 percent of silica samples
from the construction industry and 13 percent from general industry
were at least three times the then-existing OSHA PELs. The data
indicate that 66 percent of the silica samples obtained during
inspections in general industry were in compliance with the PEL, while
only 58 percent of the samples collected in construction were in
compliance.
In an effort to expand the 1996 SEP, on January 24, 2008, OSHA
implemented a National Emphasis Program (NEP) to identify and reduce or
eliminate the health hazards associated with occupational exposure to
crystalline silica (CPL-03-007 (1/24/08)). The NEP targeted worksites
with elevated exposures to crystalline silica and included new program
evaluation procedures designed to ensure that the goals of the NEP were
measured as accurately as possible, detailed procedures for conducting
inspections, updated information for selecting sites for inspection,
development of outreach programs by each Regional and Area Office
emphasizing the formation of voluntary partnerships to share
information, and guidance on calculating PELs in construction and
shipyards. In each OSHA Region, at least two percent of inspections
every year are silica-related inspections. Additionally, the silica-
related inspections are conducted at a range of facilities reasonably
representing the distribution of general industry and construction work
sites in that region.
A more recent analysis of OSHA enforcement data from January 2003
to December 2009 (covering the period of continued implementation of
the SEP and the first two years of the NEP) shows that considerable
noncompliance with the then-existing PELs continued to occur. These
enforcement data, presented in Table III-2, indicate that 14 percent of
silica samples from the construction industry and 19 percent for
general industry were at least three times the OSHA PEL during this
period. The data indicate that 70 percent of the silica samples
obtained during inspections in general industry were in compliance with
the PEL, and 75 percent of the samples collected in construction were
in compliance.
Both industry and worker groups have recognized that a
comprehensive standard is needed to protect workers exposed to
respirable crystalline silica. For example, ASTM International
(originally known as the American Society for Testing and Materials)
has published voluntary consensus standards for addressing the hazards
of crystalline silica, and the Building and Construction Trades
Department, AFL-CIO also has recommended a comprehensive program
standard. These recommended standards include provisions for methods of
compliance, exposure monitoring, training, and medical surveillance.
The National Industrial Sand Association has also developed an
occupational exposure program for crystalline silica that addresses
exposure assessment and medical surveillance.
Throughout the crystalline silica rulemaking process, OSHA has
presented information to, and consulted with, ACCSH and the Maritime
Advisory Committee on Occupational Safety and Health. In December of
2009, OSHA representatives met with ACCSH to discuss the rulemaking and
receive their comments and recommendations. On December 11, 2009, ACCSH
passed motions supporting the concept of Table 1 in the draft proposed
construction rule, recognizing that the controls listed in Table 1 are
effective. As discussed with regard to paragraph (f) of the proposed
standard for construction (paragraph (c) of the final standard for
construction), Table 1 presents specified control measures for selected
construction tasks. ACCSH also recommended that OSHA maintain the
protective clothing provision found in the SBREFA panel draft
regulatory text and restore the "competent person" requirement and
responsibilities to the proposed rule. Additionally, the group
recommended that OSHA move forward expeditiously with the rulemaking
process.
In January 2010, OSHA completed a peer review of the draft Health
Effects Analysis and Preliminary Quantitative Risk Assessment following
procedures set forth by OMB in the Final Information Quality Bulletin
for Peer Review, published on the OMB Web site on December 16, 2004
(see 70 FR 2664 (1/14/05)). Each peer reviewer submitted a written
report to OSHA. The Agency revised its draft documents as appropriate
and made the revised documents available to the public as part of its
Notice of Proposed Rulemaking (NPRM). OSHA also made the written charge
to the peer reviewers, the peer reviewers' names, the peer reviewers'
reports, and the Agency's response to the peer reviewers' reports
publicly available with publication of the proposed rule (Document ID
1711; 1716). Five of the seven original peer reviewers submitted post-
hearing reports, commenting on OSHA's disposition of their original
peer review comments in the proposed rule, as well as commenting on
written and oral testimony presented at the silica hearing (Document ID
3574).
On August 23, 2013, OSHA posted its NPRM for respirable crystalline
silica on its Web site and requested comments on the proposed rule. On
September 12, 2013, OSHA published the NPRM in the Federal Register (78
FR 56273 (9/12/13)). In the NPRM, the Agency made a preliminary
determination that employees exposed to respirable crystalline silica
at the current PELs face a significant risk to their health and that
promulgating the proposed standards would substantially reduce that
risk. The NPRM required commenters to submit their comments by December
11, 2013. In response to stakeholder requests, OSHA extended the
comment period until January 27, 2014 (78 FR 65242 (10/31/13)). On
January 14, 2014, OSHA held a web chat to provide small businesses and
other stakeholders an additional opportunity to obtain information from
the Agency about the proposed rule. Subsequently, OSHA further extended
the comment period to February 11, 2014 (79 FR 4641 (1/29/14)).
As part of the instructions for submitting comments, OSHA requested
(but did not require) that parties submitting technical or scientific
studies or research results and those submitting comments or testimony
on the Agency's analyses disclose the nature of financial relationships
with (e.g., consulting agreement), and extent of review by, parties
interested in or affected by the rulemaking (78 FR 56274).
Parties submitting studies or research results were also asked
to disclose sources of funding and sponsorship for their research.
OSHA intended for the disclosure of such information to promote
the transparency and scientific integrity of evidence submitted
to the record and stated that the request was consistent with
Executive Order 13563.
The Agency received several comments related to this request. For
example, an industrial hygiene engineer supported the disclosure of
potential conflict of interest information (Document ID 2278, p. 5).
Other commenters, such as congressional representatives and industry
associations, opposed the request, asserting that it could lead to
prejudgment or questioning of integrity, in addition to dissuading
participation in the rulemaking; some also questioned the legality of
such a request or OSHA's interpretation of Executive Order 13563 (e.g.,
Document ID 1811, p. 2; 2101, pp. 2-3). A number of stakeholders from
academia and industry submitted information related to the request for
funding, sponsorships, and review by interested parties (e.g., Document
ID 1766, p. 1; 2004, p. 2; 2211, p. 2; 2195, p. 17). OSHA emphasizes
that it reviewed and considered all evidence submitted to the record.
An informal public hearing on the proposed standards was held in
Washington, DC from March 18 through April 4, 2014. Administrative Law
Judges Daniel F. Solomon and Stephen L. Purcell presided over the
hearing. The Agency heard testimony from over 200 stakeholders
representing more than 70 organizations, such as public health groups,
trade associations, and labor unions. Chief Administrative Law Judge
Stephen L. Purcell closed the public hearing on April 4, 2014, allowing
45 days--until May 19, 2014--for participants who filed a notice of
intention to appear at the hearings to submit additional evidence and
data, and an additional 45 days--until July 3, 2014--to submit final
briefs, arguments, and summations (Document ID 3589, Tr. 4415-4416).
After the hearing concluded, OSHA extended the deadline to give those
participants who filed a notice of intention to appear at the hearings
until June 3, 2014 to submit additional information and data to the
record, and until July 18, 2014 to submit final briefs and arguments
(Document ID 3569). Based upon requests from stakeholders, the second
deadline was extended, and parties who filed a notice of intention to
appear at the hearing were given until August 18, 2014, to submit their
final briefs and arguments (Document ID 4192).
OSHA provided the public with multiple opportunities to participate
in the rulemaking process, including stakeholder meetings, the SBREFA
panel, two comment periods (pre- and post-hearing), and a 14-day public
hearing. Commenters were provided more than five months to comment on
the rule before the hearing, and nearly as long to submit additional
information, final briefs, and arguments after the hearing. OSHA
received more than 2,000 comments on the silica NPRM during the entire
pre-and post-hearing public participation period. In OSHA's view,
therefore, the public was given sufficient opportunities and ample time
to fully participate in this rulemaking.
The final rule on occupational exposure to respirable crystalline
silica is based on consideration of the entire record of this
rulemaking proceeding, including materials discussed or relied upon in
the proposal, the record of the hearing, and all written comments and
exhibits timely received. Thus, in promulgating this final rule, OSHA
considered all comments in the record, including those that suggested
that OSHA withdraw its proposal and merely enforce the existing silica
standards, as well as those that argued the proposed rule was not
protective enough. Based on this comprehensive record, OSHA concludes
that employees exposed to respirable crystalline silica are at
significant risk of developing silicosis and other non-malignant
respiratory disease, lung cancer, kidney effects, and immune system
effects. The Agency concludes that the PEL of 50 [mu]g/m\3\ reduces the
significant risks of material impairments of health posed to workers by
occupational exposure to respirable crystalline silica to the maximum
extent that is technologically and economically feasible. OSHA's
substantive determinations with regard to the comments, testimony, and
other information in the record, the legal standards governing the
decision-making process, and the Agency's analysis of the data
resulting in its assessments of risks, benefits, technological and
economic feasibility, and compliance costs are discussed elsewhere in
this preamble.
IV. Chemical Properties and Industrial Uses
Silica is a compound composed of the elements silicon and oxygen
(chemical formula SiO2). Silica has a molecular weight of
60.08, and exists in crystalline and amorphous states, both in the
natural environment and as produced during manufacturing or other
processes. These substances are odorless solids, have no vapor
pressure, and create non-explosive dusts when particles are suspended
in air (Document ID 3637, pp. 1-3).
Silica is classified as part of the "silicate" class of minerals,
which includes compounds that are composed of silicon and oxygen and
which may also be bonded to metal ions or their oxides. The basic
structural units of silicates are silicon tetrahedrons
(SiO4), pyramidal structures with four triangular sides
where a silicon atom is located in the center of the structure and an
oxygen atom is located at each of the four corners. When silica
tetrahedrons bond exclusively with other silica tetrahedrons, each
oxygen atom is bonded to the silicon atom of its original ion, as well
as to the silicon atom from another silica ion. This results in a ratio
of one atom of silicon to two atoms of oxygen, expressed as
SiO2. The silicon-oxygen bonds within the tetrahedrons use
only one-half of each oxygen's total bonding energy. This leaves
negatively charged oxygen ions available to bond with available
positively charged ions. When they bond with metal and metal oxides,
commonly of iron, magnesium, aluminum, sodium, potassium, and calcium,
they form the silicate minerals commonly found in nature (Document ID
1334, p. 7).
In crystalline silica, the silicon and oxygen atoms are arranged in
a three-dimensional repeating pattern. Silica is said to be
polymorphic, as different forms are created when the silica
tetrahedrons combine in different crystalline structures. The primary
forms of crystalline silica are quartz, cristobalite, and tridymite. In
an amorphous state, silicon and oxygen atoms are present in the same
proportions but are not organized in a repeating pattern. Amorphous
silica includes natural and manufactured glasses (vitreous and fused
silica, quartz glass), biogenic silica, and opals, which are amorphous
silica hydrates (Document ID 2258, Attachment 8, pp. 45-50).
Quartz is the most common form of crystalline silica and accounts
for almost 12% by volume of the earth's crust. Alpha quartz, the quartz
form that is stable below 573 [deg]C, is the most prevalent form of
crystalline silica found in the workplace. It accounts for the
overwhelming majority of naturally found silica and is present in
varying amounts in almost every type of mineral. Alpha quartz is found
in igneous, sedimentary, and metamorphic rock, and all soils contain at
least a trace amount of quartz (Document ID 1334, p. 9).
Alpha quartz is used in many products throughout various industries
and is a common component of building materials (Document ID 1334, pp.
11-15). Common trade names for commercially available quartz include:
CSQZ, DQ 12, Min-U-Sil, Sil-Co-Sil, Snowit, Sykron F300, and Sykron
F600 (Document ID 2258, Attachment 8, p. 43).
Cristobalite is a form of crystalline silica that is formed at high
temperatures (>1470 [deg]C). Although naturally occurring cristobalite
is relatively rare, volcanic eruptions, such as Mount St. Helens, can
release cristobalite dust into the air. Cristobalite can also be
created during some processes conducted in the workplace. For example,
flux-calcined diatomaceous earth is a material used as a filtering aid
and as a filler in other products (Document ID 2258, Attachment 8, p.
44). It is produced when diatomaceous earth (diatomite), a geological
product of decayed unicellular organisms called diatoms, is heated with
flux. The finished product can contain between 40 and 60 percent
cristobalite. Also, high temperature furnaces are often lined with
bricks that contain quartz. When subjected to prolonged high
temperatures, this quartz can convert to cristobalite.
Tridymite is another material formed at high temperatures (>870
[deg]C) that is associated with volcanic activity. The creation of
tridymite requires the presence of a flux such as sodium oxide.
Tridymite is rarely found in nature and rarely reported in the
workplace (Document ID 1424 pp. 5, 14).
When heated or cooled sufficiently, crystalline silica can
transition between the polymorphic forms, with specific transitions
occurring at different temperatures. At higher temperatures the
linkages between the silica tetrahedrons break and reform, resulting in
new crystalline structures. Quartz converts to cristobalite at 1470
[deg]C, and at 1723 [deg]C cristobalite loses its crystalline structure
and becomes amorphous fused silica. These high temperature transitions
reverse themselves at extremely slow rates, with different forms co-
existing for a long time after the crystal cools (Document ID 2258,
Attachment 8, p. 47).
Other types of transitions occur at lower temperatures when the
silica-oxygen bonds in the silica tetrahedron rotate or stretch,
resulting in a new crystalline structure. These low-temperature, or
alpha to beta, transitions are readily and rapidly reversed as the
crystal cools. At temperatures encountered by workers, only the alpha
form of crystalline silica exists (Document ID 2258, Attachment 8, pp.
46-48).
Crystalline silica minerals produce distinct X-ray diffraction
patterns, specific to their crystalline structure. The patterns can be
used to distinguish the crystalline polymorphs from each other and from
amorphous silica (Document ID 2258, Attachment 8, p. 45).
The specific gravity and melting point of silica vary between
polymorphs. Silica is insoluble in water at 20 [deg]C and in most
acids, but its solubility increases with higher temperatures and pH,
and it dissolves readily in hydrofluoric acid. Solubility is also
affected by the presence of trace metals and by particle size. Under
humid conditions water vapor in the air reacts with the surface of
silica particles to form an external layer of silinols (SiOH). When
these silinols are present the crystalline silica becomes more
hydrophilic. Heating or acid washing reduces the amount of silinols on
the surface area of crystalline silica particles. There is an external
amorphous layer found in aged quartz, called the Beilby layer, which is
not found on freshly cut quartz. This amorphous layer is more water
soluble than the underlying crystalline core. Etching with hydrofluoric
acid removes the Beilby layer as well as the principal metal impurities
on quartz (Document ID 2258, Attachment 8, pp. 44-49).
Crystalline silica has limited chemical reactivity. It reacts with
alkaline aqueous solutions, but does not readily react with most acids,
with the exception of hydrofluoric acid. In contrast, amorphous silica
and most silicates react with most mineral acids and alkaline
solutions. Analytical chemists relied on this difference in acid
reactivity to develop the silica point count analytical method that was
widely used prior to the current X-ray diffraction and infrared methods
(Document ID 2258, Attachment 8, pp. 48-51; 1355, p. 994).
Crystalline silica is used in industry in a wide variety of
applications. Sand and gravel are used in road building and concrete
construction. Sand with greater than 98% silica is used in the
manufacture of glass and ceramics. Silica sand is used to form molds
for metal castings in foundries, and in abrasive blasting operations.
Silica is also used as a filler in plastics, rubber, and paint, and as
an abrasive in soaps and scouring cleansers. Silica sand is used to
filter impurities from municipal water and sewage treatment plants, and
in hydraulic fracturing for oil and gas recovery (Document ID 1334, p.
11). Silica is also used to manufacture artificial stone products used
as bathroom and kitchen countertops, and the silica content in those
products can exceed 85 percent (Document ID 1477, pp. 3 and 11; 2178,
Attachment 5, p. 420).
There are over 30 major industries and operations where exposures
to crystalline silica can occur. They include such diverse workplaces
as foundries, dental laboratories, concrete products and paint and
coating manufacture, as well as construction activities including
masonry cutting, drilling, grinding and tuckpointing, and use of heavy
equipment during demolition activities involving silica-containing
materials. A more detailed discussion of the industries affected by the
proposed standard is presented in Section VII, Summary of the Final
Economic Analysis and Final Regulatory Flexibility Analysis.
Crystalline silica exposures can also occur in mining (which is under
the jurisdiction of the Mine Safety and Health Administration), and in
agriculture during plowing and harvesting.
V. Health Effects
A. Introduction
As discussed more thoroughly in Section II of this preamble,
Pertinent Legal Authority, section 6(b)(5) of the Occupational Safety
and Health Act (OSH Act or Act) requires the Secretary of Labor, in
promulgating standards dealing with toxic materials or harmful physical
agents, to "set the standard which most adequately assures, to the
extent feasible, on the basis of the best available evidence, that no
employee will suffer material impairment of health or functional
capacity even if such employee has regular exposure to the hazard dealt
with by such standard for the period of his working life" (29 U.S.C.
655). Thus, in order to set a new health standard, the Secretary must
determine that there is a significant risk of material impairment of
health at the existing PEL and that issuance of a new standard will
significantly reduce or eliminate that risk.
The Secretary's significant risk and material impairment
determinations must be made "on the basis of the best available
evidence" (29 U.S.C. 655(b)(5)). Although the Supreme Court, in its
decision on OSHA's Benzene standard, explained that OSHA must look to
"a body of reputable scientific thought" in making its material harm
and significant risk determinations, the Court added that a reviewing
court must "give OSHA some leeway where its findings must be made on
the frontiers of scientific knowledge" (Indus. Union Dep't,
AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607, 656 (1980) (plurality opinion)
("Benzene")). Thus, while OSHA's significant risk determination must be
supported by substantial evidence, the Agency "is not required to support
the finding that a significant risk exists with anything approaching
scientific certainty" (Benzene, 448 U.S. at 656).
This section provides an overview of OSHA's material harm and
significant risk determinations: (1) Summarizing OSHA's preliminary
methods and findings from the proposal; (2) addressing public comments
dealing with OSHA's evaluation of the scientific literature and methods
used to estimate quantitative risk; and (3) presenting OSHA's final
conclusions, with consideration of the rulemaking record, on the health
effects and quantitative risk estimates associated with worker exposure
to respirable crystalline silica. The quantitative risk estimates and
significance of those risks are then discussed in detail in Section VI,
Final Quantitative Risk Assessment and Significance of Risk.
B. Summary of Health and Risk Findings
As discussed in detail throughout this section and in Section VI,
Final Quantitative Risk Assessment and Significance of Risk, OSHA
finds, based upon the best available evidence in the published, peer-
reviewed scientific literature, that exposure to respirable crystalline
silica increases the risk of silicosis, lung cancer, other non-
malignant respiratory disease (NMRD), and renal and autoimmune effects.
In its Preliminary Quantitative Risk Assessment (QRA), OSHA used the
best available exposure-response data from epidemiological studies to
estimate quantitative risks. After carefully reviewing stakeholder
comments on the Preliminary QRA and new information provided to the
rulemaking record, OSHA finds there to be a clearly significant risk at
the previous PELs for respirable crystalline silica (equivalent to
approximately 100 [mu]g/m\3\ for general industry and between 250 and
500 [mu]g/m\3\ for construction/shipyards), with excess lifetime risk
estimates for lung cancer mortality, silicosis mortality, and NMRD
mortality each being much greater than 1 death per 1,000 workers
exposed for a working life of 45 years. Cumulative risk estimates for
silicosis morbidity are also well above 1 case per 1,000 workers
exposed at the previous PELs. At the revised PEL of 50 [mu]g/m\3\
respirable crystalline silica, these estimated risks are substantially
reduced. Thus, OSHA concludes that the new PEL of 50 [mu]g/m\3\
provides a large reduction in the lifetime and cumulative risk posed to
workers exposed to respirable crystalline silica.
These findings and conclusions are consistent with those of the
World Health Organization's International Agency for Research on Cancer
(IARC), the U.S. Department of Health and Human Services' (HHS)
National Toxicology Program (NTP), the National Institute for
Occupational Safety and Health (NIOSH), and many other organizations
and individuals, as evidenced in the rulemaking record and further
discussed below. Many other scientific organizations and governments
have recognized the strong body of scientific evidence pointing to the
health risks of respirable crystalline silica and have deemed it
necessary to take action to reduce those risks. As far back as 1974,
NIOSH recommended that the exposure limit for crystalline silica be
reduced to 50 [mu]g/m\3\ (Document ID 2177b, p. 2). In 2000, the
American Conference of Governmental Industrial Hygienists (ACGIH), a
professional society that has recommended workplace exposure limits for
six decades, revised their Threshold Limit Value (TLV) for respirable
crystalline silica to 50 [mu]g/m\3\ and has since further lowered its
TLV for respirable crystalline silica to 25 [mu]g/m\3\. OSHA is setting
its revised PEL at 50 [mu]g/m\3\ based on consideration of the body of
evidence describing the health risks of crystalline silica as well as
on technological feasibility considerations, as discussed in Section
VII of this preamble and Chapter IV of the Final Economic Analysis and
Final Regulatory Flexibility Analysis (FEA).
To reach these conclusions, OSHA performed an extensive search and
review of the peer-reviewed scientific literature on the health effects
of inhalation exposure to crystalline silica, particularly silicosis,
lung cancer, other NMRD, and renal and autoimmune effects (Document ID
1711, pp. 7-265). Based upon this review, OSHA preliminarily determined
that there was substantial evidence that exposure to respirable
crystalline silica increases the risk of silicosis, lung cancer, NMRD,
and renal and autoimmune effects (Document ID 1711, pp. 164, 181-208,
229). OSHA also found there to be suitable exposure-response data from
many well-conducted epidemiological studies that permitted the Agency
to estimate quantitative risks for lung cancer mortality, silicosis and
NMRD mortality, renal disease mortality, and silicosis morbidity
(Document ID 1711, p. 266).
As part of the preliminary quantitative risk assessment, OSHA
calculated estimates of the risk of silica-related diseases assuming
exposure over a working life (45 years) to 25, 50, 100, 250, and 500
[mu]g/m\3\ respirable crystalline silica (corresponding to cumulative
exposures over 45 years to 1.125, 2.25, 4.5, 11.25, and 22.5 mg/m\3\-
yrs) (see Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1264-65
(D.C. Cir. 1988) approving OSHA's policy of using 45 years for the
working life of an employee in setting a toxic substance standard). To
estimate lifetime excess mortality risks at these exposure levels, OSHA
used, for each key study, the exposure-response risk model(s) and
regression coefficient from the model(s) in a life table analysis that
accounted for competing causes of death due to background causes and
cumulated risk through age 85 (Document ID 1711, pp. 360-378). For
these analyses, OSHA used lung cancer, NMRD, or renal disease mortality
and all-cause mortality rates to account for background risks and
competing risks (U.S. 2006 data for lung cancer and NMRD mortality in
all males, 1998 data for renal disease mortality, obtained from cause-
specific death rate tables published by the National Center for Health
Statistics (2009, Document ID 1104)). The mortality risk estimates were
presented in terms of lifetime excess risk per 1,000 workers for
exposure over an 8-hour working day, 250 days per year, and a 45-year
working lifetime. For silicosis morbidity, OSHA based its risk
estimates on the cumulative risk model(s) used in each study to develop
quantitative exposure-response relationships. These models
characterized the risk of developing silicosis, as detected by chest
radiography, up to the time that cohort members, including both active
and retired workers, were last examined (78 FR 56273, 56312 (9/12/13)).
OSHA then combined its review of the health effects literature and
preliminary quantitative risk assessment into a draft document,
entitled "Occupational Exposure to Respirable Crystalline Silica--
Review of Health Effects Literature and Preliminary Quantitative Risk
Assessment," and submitted it to a panel of scientific experts \2\ for
independent peer review, in accordance with the Office of Management and
Budget's (OMB) "Final Information Quality Bulletin for Peer Review"
(Document ID 1336). The peer reviewers reviewed OSHA's draft Review of
Health Effects Literature and Preliminary QRA. The peer-review panel
responded to nearly 20 charge questions from OSHA and commented on
various aspects of OSHA's analysis (Document ID 1716).
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\2\ OSHA's contractor, Eastern Research Group, Inc. (ERG),
conducted a search for nationally recognized experts in occupational
epidemiology, biostatistics and risk assessment, animal and cellular
toxicology, and occupational medicine who had no actual or apparent
conflict of interest. ERG chose seven of the applicants to be peer
reviewers based on their qualifications and the necessity of
ensuring a broad and diverse panel in terms of scientific and
technical expertise (see Document ID 1711, pp. 379-381). The seven
peer reviewers were: Bruce Allen, Bruce Allen Consulting; Kenneth
Crump, Ph.D., Louisiana Tech University Foundation; Murray
Finkelstein, MD, Ph.D., McMaster University, Ontario; Gary Ginsberg,
Ph.D., Connecticut Department of Public Health; Brian Miller, Ph.D.,
Institute of Occupational Medicine (IOM) Consulting Ltd., Scotland;
Andrew Salmon, Ph.D., private consultant; and Noah Seixas, Ph.D.,
University of Washington, Seattle (Document ID 1711, p. 380).
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Overall, the peer reviewers found that OSHA was very thorough in
its review of the literature and was reasonable in its interpretation
of the studies with regards to the various endpoints examined, such
that the Agency's conclusions on health effects were generally well
founded (Document ID 1711, p. 381). The reviewers had various comments
on OSHA's draft Preliminary QRA (Document ID 1716, pp. 107-218). OSHA
provided a response to each comment in the Review of Health Effects
Literature and Preliminary QRA and, where appropriate, made revisions
(Document ID 1711, pp. 381-399). The Agency then placed the Review of
Health Effects Literature and Preliminary QRA into the rulemaking
docket as a background document (Document ID 1711). With the
publication of the Notice of Proposed Rulemaking (78 FR 56723 on 9/12/
13), all aspects of the Review of Health Effects Literature and
Preliminary QRA were open for public comment.
Following the publication of the proposed rule (78 FR 56273 (9/12/
13)) and accompanying revised Review of Health Effects Literature and
Preliminary QRA (Document ID 1711), the peer reviewers were invited to
review the revised analysis, examine the written comments in the
docket, and attend the public hearing to listen to oral testimony as it
applied to the health effects and quantitative risk assessment. Five
peer reviewers were available and attended. In their final comments,
provided to OSHA following the hearings, all five peer reviewers
indicated that OSHA had adequately addressed their original comments
(Document ID 3574). The peer reviewers also offered additional comments
on concerns raised during the hearing. Many of the reviewers commented
on the difficulty of evaluating exposure-response thresholds, and
responded to public comments regarding causation and other specific
issues (Document ID 3574). OSHA has incorporated many of the peer
reviewers' additional comments into its risk assessment discussion in
the preamble. Thus, OSHA believes that the external, independent peer-
review process supports and lends legitimacy to its risk assessment
methods and findings.
OSHA also received substantial public comment and testimony from a
wide variety of stakeholders supporting its Review of Health Effects
Literature and Preliminary QRA. In general, supportive comments and
testimony were received from NIOSH (Document ID 2177; 3998; 4233), the
public health and medical community, labor unions, affected workers,
private citizens, and others.
Regarding health effects, NIOSH commented that the adverse health
effects of exposure to respirable crystalline silica are "well-known,
long lasting, and preventable" (Document ID 2177b, p. 2). Darius
Sivin, Ph.D., of the UAW, commented, "[o]ccupational exposure to
silica has been recognized for centuries as a serious workplace
hazard" (Document ID 2282, Attachment 3, p. 4). Similarly, David
Goldsmith, Ph.D., testified:
There have been literally thousands of research studies on
exposure to crystalline silica in the past 30 years. Almost every
study tells the occupational research community that workers need
better protection to prevent severe chronic respiratory diseases,
including lung cancer and other diseases in the future. What OSHA is
proposing to do in revising the workplace standard for silica seems
to be a rational response to the accumulation of published evidence
(Document ID 3577, Tr. 865-866).
Franklin Mirer, Ph.D., CIH, Professor of Environmental and
Occupational Health at CUNY School of Public Health, on behalf of the
American Federation of Labor and Congress of Industrial Organizations
(AFL-CIO), reiterated that silica "is a clear and present danger to
workers health at exposure levels prevailing now in a large number of
industries. Workers are at significant risk for mortality and illnesses
including lung cancer and non-malignant respiratory disease including
COPD, and silicosis" (Document ID 2256, Attachment 3, p. 3). The AFL-
CIO also noted that there is "overwhelming evidence in the record that
exposure to respirable crystalline silica poses a significant health
risk to workers" (Document ID 4204, p. 11). The Building and
Construction Trades Department, AFL-CIO, further commented that the
rulemaking record "clearly supports OSHA's risk determination"
(Document ID 4223, p. 2). Likewise, the Sorptive Minerals Institute, a
national trade association, commented, "It is beyond dispute that OSHA
has correctly determined that industrial exposure to certain types of
silica can cause extremely serious, sometimes even fatal disease. In
the massive rulemaking docket being compiled by the Agency, credible
claims to the contrary are sparse to non-existent" (Document ID 4230,
p. 8). OSHA also received numerous comments supportive of the revised
standard from affected workers and citizens (e.g., Document ID 1724,
1726, 1731, 1752, 1756, 1759, 1762, 1764, 1787, 1798, 1800, 1802).
Regarding OSHA's literature review for its quantitative risk
assessment, the American Public Health Association (APHA) and the
National Consumers League (NCL) commented, "OSHA has thoroughly
reviewed and evaluated the peer-reviewed literature on the health
effects associated with exposure to respirable crystalline silica.
OSHA's quantitative risk assessment is sound. The agency has relied on
the best available evidence and acted appropriately in giving greater
weight to those studies with the most robust designs and statistical
analyses" (Document ID 2178, Attachment 1, p. 1; 2373, p. 1).
Dr. Mirer, who has served on several National Academy of Sciences
committees setting risk assessment guidelines, further commented that
OSHA's risk analysis is "scientifically correct, and consistent with
the latest thinking on risk assessment," (Document ID 2256, Attachment
3, p. 3), citing the National Academies' National Research Council's
Science and Decisions: Advancing Risk Assessment (Document ID 4052),
which makes technical recommendations on risk assessment and risk-based
decision making (Document ID 3578, Tr. 935-936). In post-hearing
comments expanding on this testimony, the AFL-CIO also noted that
OSHA's risk assessment methodologies are transparent and consistent
with practices recommended by the National Research Council in its
publication, Risk Assessment in the Federal Government: Managing the
Process, and with the Environmental Protection Agency's Guidelines for
Carcinogenic Risk Assessment (Document ID 4204, p. 20). Similarly, Kyle
Steenland, Ph.D., Professor in the Department of Environmental Health
at Rollins School of Public Health, Emory University, one of the
researchers on whose studies OSHA relied, testified that "OSHA has
done a very capable job in conducting the summary of the literature and
doing its own risk assessment" (Document ID 3580, Tr. 1235).
Collectively, these comments and testimony support OSHA's use of the
best available evidence and methods to estimate quantitative risks of
lung cancer mortality, silicosis and NMRD mortality, renal disease
mortality, and silicosis morbidity from exposure to respirable
crystalline silica.
Based on OSHA's Preliminary QRA, many commenters recognized that
reducing the permissible exposure limit is necessary to reduce
significant risks presented by exposure to respirable crystalline
silica (Document ID 4204, pp. 11-12; 2080, p. 1; 2339, p. 2). For
example, the AFL-CIO stated that "OSHA based its proposal on more than
adequate evidence, but more recent publications have described further
the risk posed by silica exposure, and further justify the need for new
silica standards" (Document ID 4204, pp. 11-12). Similarly, the
American Society of Safety Engineers (ASSE) remarked that "[w]hile
some may debate the science underlying the findings set forth in the
proposed rule, overexposure to crystalline silica has been linked to
occupational illness since the time of the ancient Greeks, and
reduction of the current permissible exposure limit (PEL) to that
recommended for years by the National Institute for Occupational Safety
and Health (NIOSH) is long overdue" (Document ID 2339, p. 2).
Not every commenter agreed, however, as OSHA also received critical
comments and testimony from various employers and their
representatives, as well as some organizations representing affected
industries. In general, these comments were critical of the underlying
studies on which OSHA relied for its quantitative risk assessment, or
with the methods used by OSHA to estimate quantitative risks. Some
commenters also presented additional studies for OSHA to consider. OSHA
thoroughly reviewed these and did not find them adequate to alter
OSHA's overall conclusions of health risk, as discussed in great detail
in the sections that follow.
After considering the evidence and testimony in the record, as
discussed below, OSHA affirms its approach to quantify health risks
related to exposure to respirable crystalline silica and the Agency's
preliminary conclusions. In the final risk assessment that is now
presented as part of this final rule in Section VI, Final Quantitative
Risk Assessment and Significance of Risk, OSHA concludes that there is
a clearly significant risk at the previous PELs for respirable
crystalline silica, with excess lifetime risk estimates for lung cancer
mortality, silicosis mortality, and NMRD mortality each being much
greater than 1 death per 1,000 workers as a result of exposure for 45
working years (see Section VI, Final Quantitative Risk Assessment and
Significance of Risk). At the revised PEL of 50 [micro]g/m\3\
respirable crystalline silica, OSHA finds the estimated risks to be
substantially reduced. Cumulative risk estimates for silicosis
morbidity are also well above 1 case per 1,000 workers at the previous
PELs, with a substantial reduction at the revised PEL (see Section VI,
Final Quantitative Risk Assessment and Significance of Risk, Table VI-
1).
The health effects associated with silica exposure are well-
established and supported by the record. Based on the record evidence,
OSHA concludes that exposure to respirable crystalline silica causes
silicosis and is the only known cause of silicosis. This causal
relationship has long been accepted in the scientific and medical
communities. In fact, the Department of Labor produced a video in 1938
featuring then Secretary of Labor Frances Perkins discussing the
occurrence of silicosis among workers exposed to silica
(see https://www.osha.gov/silica/index.html). Silicosis is a progressive disease
induced by the inflammatory effects of respirable crystalline silica in
the lung, which leads to lung damage and scarring and, in some cases,
progresses to complications resulting in disability and death (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk). OSHA used a weight-of-evidence approach to evaluate the
scientific studies in the literature to determine their overall quality
and whether there is substantial evidence that exposure to respirable
crystalline silica increases the risk of a particular health effect.
For lung cancer, OSHA reviewed the published, peer-reviewed
scientific literature, including 60 epidemiological studies covering
more than 30 occupational groups in over a dozen industrial sectors
(see Document ID 1711, pp. 77-170). Based on this comprehensive review,
and after considering the rulemaking record as a whole, OSHA concludes
that the data provide ample evidence that exposure to respirable
crystalline silica increases the risk of lung cancer among workers (see
Document ID 1711, p. 164). OSHA's conclusion is consistent with that of
IARC, which is the specialized cancer agency that is part of the World
Health Organization and utilizes interdisciplinary (e.g.,
biostatistics, epidemiology, and laboratory sciences) experts to
comprehensively identify the causes of cancer. In 1997, IARC classified
respirable crystalline silica dust, in the form of quartz or
cristobalite, as Group 1, i.e., "carcinogenic to humans," following a
thorough expert committee review of the peer-reviewed scientific
literature (Document ID 2258, Attachment 8, p. 211). OSHA notes that
IARC classifications and accompanying monographs are well recognized in
the scientific community, having been described as "the most
comprehensive and respected collection of systematically evaluated
agents in the field of cancer epidemiology" (Demetriou et al., 2012,
Document ID 4131, p. 1273). For silica, IARC's overall finding was
based on studies of nine occupational cohorts that it considered to be
the least influenced by confounding factors (see Document ID 1711, p.
76). OSHA included these studies in its review, in addition to several
other studies (Document ID 1711, pp. 77-170).
Since IARC's 1997 determination that respirable crystalline silica
is a Group 1 carcinogen, the scientific community has reaffirmed the
soundness of this finding. In March of 2009, 27 scientists from eight
countries participated in an additional IARC review of the scientific
literature and reaffirmed that respirable crystalline silica dust is a
Group 1 human carcinogen (Document ID 1473, p. 396). Additionally, in
2000, the NTP, which is a widely-respected interagency program under
HHS that evaluates chemicals for possible toxic effects on public
health, also concluded that respirable crystalline silica is a known
human carcinogen (Document ID 1164, p. 1).
For NMRD other than silicosis, based on its review of several
studies and all subsequent record evidence, OSHA concludes that
exposure to respirable crystalline silica increases the risk of
emphysema, chronic bronchitis, and pulmonary function impairment (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, pp. 181-208). For renal disease, OSHA reviewed
the epidemiological literature and finds that a number of
epidemiological studies reported statistically significant associations
between occupational exposure to silica dust and chronic renal disease,
subclinical renal changes, end-stage renal disease morbidity, chronic
renal disease mortality, and granulomatosis with polyangitis (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, p. 228). For autoimmune effects, OSHA reviewed
epidemiological information in the record suggesting an association
between respirable crystalline silica exposure and increased risk of
systemic autoimmune diseases, including scleroderma, rheumatoid
arthritis, and systemic lupus erythematosus (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk; Document ID
1711, p. 229). Therefore, OSHA concludes that there is substantial
evidence that silica exposure increases the risks of renal and of
autoimmune disease (see Section VI, Final Quantitative Risk Assessment
and Significance of Risk; Document ID 1711, p. 229).
OSHA also finds there to be suitable exposure-response data from
many well-conducted studies that permit the Agency to estimate
quantitative risks for lung cancer mortality, silicosis and NMRD
mortality, renal disease mortality, and silicosis morbidity (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, p. 266). OSHA believes the exposure-response
data in these studies collectively represent the best available
evidence for use in estimating the quantitative risks related to silica
exposure. For lung cancer mortality, OSHA relies upon a number of
published studies that analyzed exposure-response relationships between
respirable crystalline silica and lung cancer. These included studies
of cohorts from several industry sectors: Diatomaceous earth workers
(Rice et al., 2001, Document ID 1118), Vermont granite workers
(Attfield and Costello, 2004, Document ID 0285), North American
industrial sand workers (Hughes et al., 2001, Document ID 1060), and
British coal miners (Miller and MacCalman, 2009, Document ID 1306).
These studies are scientifically sound due to their sufficient size and
adequate years of follow-up, sufficient quantitative exposure data,
lack of serious confounding by exposure to other occupational
carcinogens, consideration (for the most part) of potential confounding
by smoking, and absence of any apparent selection bias (see Section VI,
Final Quantitative Risk Assessment and Significance of Risk; Document
ID 1711, p. 165). They all demonstrated positive, statistically
significant exposure-response relationships between exposure to
crystalline silica and lung cancer mortality. Also compelling was a
pooled analysis (Steenland et al., 2001a, Document ID 0452) of 10
occupational cohorts (with a total of 65,980 workers and 1,072 lung
cancer deaths), which was also used as a basis for IARC's 2009
reaffirmation of respirable crystalline silica as a human carcinogen.
This analysis by Steenland et al. found an overall positive exposure-
response relationship between cumulative exposure to crystalline silica
and lung cancer mortality (see Section VI, Final Quantitative Risk
Assessment and Significance of Risk; Document ID 1711, pp. 269-292).
Based on these studies, OSHA estimates that the lifetime lung cancer
mortality excess risk associated with 45 years of exposure to
respirable crystalline silica ranges from 11 to 54 deaths per 1,000
workers at the previous general industry PEL of 100 [micro]g/m\3\
respirable crystalline silica, and 5 to 23 deaths per 1,000 workers at
the revised PEL of 50 [micro]g/m\3\ respirable crystalline silica (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk, Table VI-1). These estimates exceed by a substantial margin the
one in a thousand benchmark that OSHA has generally applied to its
health standards following the Supreme Court's Benzene decision (448
U.S. 607, 655 (1980)).
For silicosis and NMRD mortality, OSHA relies upon two published,
peer-reviewed studies: A pooled analysis of silicosis mortality data
from six epidemiological studies (Mannetje et al., 2002b, Document ID
1089), and an exposure-response analysis of NMRD mortality among
diatomaceous earth workers (Park et al, 2002, Document ID 0405) (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, p. 292). The pooled analysis had a total of
18,634 subjects, 150 silicosis deaths, and 20 deaths from unspecified
pneumoconiosis, and demonstrated an increasing mortality rate with
silica exposure (Mannetje et al., 2002b, Document ID 1089; see also
1711, pp. 292-295). To estimate the risks of silicosis mortality, OSHA
used the model described by Mannetje et al. but used rate ratios that
were estimated from a sensitivity analysis conducted by ToxaChemica,
Inc. that was expected to better control for age and exposure
measurement uncertainty (2004, Document ID 0469; 1711, p. 295). OSHA's
estimate of lifetime silicosis mortality risk is 11 deaths per 1,000
workers at the previous general industry PEL, and 7 deaths per 1,000
workers at the revised PEL (see Section VI, Final Quantitative Risk
Assessment and Significance of Risk, Table VI-1).
The NMRD analysis by Park et al. (2002, Document 0405) included
pneumoconiosis (including silicosis), chronic bronchitis, and
emphysema, since silicosis is a cause of death that is often
misclassified as emphysema or chronic bronchitis (see Document ID 1711,
p. 295). Positive exposure-response relationships were found between
exposure to crystalline silica and excess risk for NMRD mortality (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, pp. 204-206, 295-297). OSHA's estimate of
excess lifetime NMRD mortality risk, calculated using the results from
Park et al., is 85 deaths per 1,000 workers at the previous general
industry PEL of 100 [micro]g/m\3\ respirable crystalline silica, and 44
deaths per 1,000 workers at the revised PEL (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk, Table VI-1).\3\
---------------------------------------------------------------------------
\3\ The risk estimates for silicosis and NMRD are not directly
comparable, as the endpoint for the NMRD analysis (Park et al.,
2002, Document ID 0405) was death from all non-cancer lung diseases,
including silicosis, pneumoconiosis, emphysema, and chronic
bronchitis, whereas the endpoint for the silicosis analysis
(Mannetje et al., 2002b, Document ID 1089) was deaths coded as
silicosis or other pneumoconiosis only (Document ID 1711, pp. 297-
298).
---------------------------------------------------------------------------
For renal disease mortality, Steenland et al. (2002a, Document ID
0448) conducted a pooled analysis of three cohorts (with a total of
13,382 workers) that found a positive exposure-response relationship
for both multiple-cause mortality (i.e., any mention of renal disease
on the death certificate) and underlying cause mortality. OSHA used the
Steenland et al. (2002a, Document ID 0448) pooled analysis to estimate
risks, given its large number of workers from cohorts with sufficient
exposure data (see Section VI, Final Quantitative Risk Assessment and
Significance of Risk; Document ID 1711, pp. 314-315). OSHA's analysis
for renal disease mortality shows estimated lifetime excess risk of 39
deaths per 1,000 workers at the previous general industry PEL of 100
[micro]g/m\3\ respirable crystalline silica, and 32 deaths per 1,000
workers exposed at the revised PEL of 50 [micro]g/m\3\ (see Section VI,
Final Quantitative Risk Assessment and Significance of Risk, Table VI-
1). OSHA acknowledges, however, that there are considerably less data
for renal disease mortality, and thus the findings based on them are
less robust than those for silicosis, lung cancer, and NMRD mortality
(see Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, p. 229). For autoimmune disease, there were no
quantitative exposure-response data available for a quantitative risk
assessment (see Section VI, Final Quantitative Risk Assessment and
Significance of Risk; Document ID 1711, p. 229).
For silicosis morbidity, OSHA reviewed the principal studies
available in the scientific literature that have characterized the risk
to exposed workers of acquiring silicosis, as detected by the
appearance of opacities on chest radiographs (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk; Document ID
1711, p. 357). The most reliable estimates of silicosis morbidity came
from five studies that evaluated radiographs over time, including after
workers left employment: The U.S. gold miner cohort studied by
Steenland and Brown (1995b, Document ID 0451); the Scottish coal miner
cohort studied by Buchanan et al. (2003, Document ID 0306); the Chinese
tin mining cohort studied by Chen et al. (2001, Document ID 0332); the
Chinese tin, tungsten, and pottery worker cohorts studied by Chen et
al. (2005, Document ID 0985); and the South African gold miner cohort
studied by Hnizdo and Sluis-Cremer (1993, Document ID 1052) (see
Section VI, Final Quantitative Risk Assessment and Significance of
Risk; Document ID 1711, pp. 316-343). These studies demonstrated
positive exposure-response relationships between exposure to
crystalline silica and silicosis risk. Based on the results of these
studies, OSHA estimates a cumulative risk for silicosis morbidity of
between 60 and 773 cases per 1,000 workers for a 45-year exposure to
the previous general industry PEL of 100 [micro]g/m\3\ respirable
crystalline silica depending upon the study used, and between 20 and
170 cases per 1,000 workers exposed at the new PEL of 50 [micro]g/m\3\
depending upon the study used (see Section VI, Final Quantitative Risk
Assessment and Significance of Risk, Table VI-1). Thus, like OSHA's
risk estimates for other health endpoints, the risk is substantially
lower, though still significant, at the revised PEL.
In conclusion, OSHA finds, based on the best available evidence and
methods to estimate quantitative risks of disease resulting from
exposure to respirable crystalline silica, that there are significant
risks of material health impairment at the former PELs for respirable
crystalline silica, which would be substantially reduced (but not
entirely eliminated) at the new PEL of 50 [mu]g/m\3\. In meeting its
legal burden to estimate the health risks posed by respirable
crystalline silica, OSHA has used the best available evidence and
methods to estimate quantitative risks of disease resulting from
exposure to respirable crystalline silica. As a result, the Agency
finds that the lifetime excess mortality risks (for lung cancer, NMRD
and silicosis, and renal disease) and cumulative risk (silicosis
morbidity) posed to workers exposed to respirable crystalline silica
over a working life represent significant risks that warrant
mitigation, and that these risks will be substantially reduced at the
revised PEL of 50 [mu]g/m\3\ respirable crystalline silica.
C. Summary of the Review of Health Effects Literature and Preliminary
QRA
As noted above, a wide variety of stakeholders offered comments and
testimony in this rulemaking on issues related to health and risk. Many
of these comments were submitted in response to OSHA's preliminary risk
and material impairment determinations, which were presented in two
background documents, entitled "Occupational Exposure to Respirable
Crystalline Silica--Review of Health Effects Literature and Preliminary
Quantitative Risk Assessment" (Document ID 1711) and "Supplemental
Literature Review of Epidemiological Studies on Lung Cancer Associated
with Exposure to Respirable Crystalline Silica" (Document ID 1711,
Attachment 1), and summarized in the proposal in Section V, Health
Effects Summary, and Section VI, Summary of OSHA's Preliminary
Quantitative Risk Assessment.
In this subsection, OSHA summarizes the major findings of the two
background documents. The Agency intends for this subsection to provide
the detailed background necessary to fully understand stakeholders'
comments and OSHA's responses.
1. Background
As noted above, OSHA's Review and Supplemental Review of Health
Effects Literature and Preliminary Quantitative Risk Assessment
(Document ID 1711; 1711, Attachment 1) were the result of the Agency's
extensive search and review of the peer-reviewed scientific literature
on the health effects of inhalation exposure to crystalline silica,
particularly silicosis, lung cancer and cancer at other sites, non-
malignant respiratory diseases (NMRD) other than silicosis, and renal
and autoimmune effects. The purposes of this detailed search and
scientific review were to determine the nature of the hazards presented
by exposure to respirable crystalline silica, and to evaluate whether
there was an adequate basis, with suitable data availability, for
quantitative risk assessment.
Much of the scientific evidence that describes the health effects
and risks associated with exposure to crystalline silica consisted of
epidemiological studies of worker populations; OSHA also reviewed
animal and in vitro studies. OSHA used a weight-of-evidence approach in
evaluating this evidence. Under this approach, OSHA evaluated the
relevant studies to determine their overall quality. Factors considered
in assessing the quality of studies included: (1) The size of the
cohort studied and the power of the study to detect a sufficiently low
level of disease risk; (2) the duration of follow-up of the study
population; (3) the potential for study bias (e.g., selection bias in
case-control studies or survivor effects in cross-sectional studies);
and (4) the adequacy of underlying exposure information for examining
exposure-response relationships. Studies were deemed suitable for
inclusion in OSHA's Preliminary Quantitative Risk Assessment (QRA)
where there was adequate quantitative information on exposure and
disease risks and the study was judged to be sufficiently high quality
according to these criteria.
Based upon this weight-of-evidence approach, OSHA preliminarily
determined that there is substantial evidence in the peer-reviewed
scientific literature that exposure to respirable crystalline silica
increases the risk of silicosis, lung cancer, other NMRD, and renal and
autoimmune effects. The Preliminary QRA indicated that, for silicosis
and NMRD mortality, lung cancer mortality, and renal disease mortality,
there is a significant risk at the previous PELs for respirable
crystalline silica, with excess lifetime risk estimates substantially
greater than 1 death per 1,000 workers as a result of exposure over a
working life (45 years, from age 20 to age 65). At the revised PEL of
50 [mu]g/m\3\ respirable crystalline silica, OSHA estimated that these
risks would be substantially reduced. Cumulative risk estimates for
silicosis morbidity were also well above 1 case per 1,000 workers at
the previous PELs, with a substantial reduction at the revised PEL.
2. Summary of the Review of Health Effects Literature
In its Review of Health Effects Literature, OSHA identified the
adverse health effects associated with the inhalation of respirable
crystalline silica (Document ID 1711). OSHA covered the following
topics: Silicosis (including relevant data from U.S. disease
surveillance efforts), lung cancer and cancer at other sites, non-
malignant respiratory diseases (NMRD) other than silicosis, renal and
autoimmune effects, and physical factors affecting the toxicity of
crystalline silica. Most of the evidence that described the health
risks associated with exposure to silica consisted of epidemiological
studies of worker populations; animal and in vitro studies on mode of
action and molecular toxicology were also described. OSHA focused
solely on those studies associated with airborne exposure to respirable
crystalline silica due to the lack of evidence of health hazards from
dermal or oral exposure. The review was further confined to issues
related to the inhalation of respirable dust, which is generally
defined as particles that are capable of reaching the pulmonary region
of the lung (i.e., particles less than 10 microns ([mu]m) in aerodynamic
diameter), in the form of either quartz or cristobalite, the two forms
of crystalline silica most often encountered in the workplace.
a. Silicosis
i. Types
Silicosis is an irreversible, progressive disease induced by the
inflammatory effects of respirable crystalline silica in the lung,
leading to lung damage and scarring and, in some cases, progressing to
complications resulting in disability and death. Exposure to respirable
crystalline silica is the only known cause of silicosis. Three types of
silicosis have been described: An acute form following intense exposure
to respirable dust of high crystalline silica content for a relatively
short period (i.e., a few months or years); an accelerated form,
resulting from about 5 to 15 years of heavy exposure to respirable
dusts of high crystalline silica content; and, most commonly, a chronic
form that typically follows less intense exposure of more than 20 years
(Becklake, 1994, Document ID 0294; Balaan and Banks, 1992, 0289). In
both the accelerated and chronic forms of the disease, lung
inflammation leads to the formation of excess connective tissue, or
fibrosis, in the lung. The hallmark of the chronic form of silicosis is
the silicotic islet or nodule, one of the few agent-specific lesions in
pathology (Balaan and Banks, 1992, Document ID 0289). As the disease
progresses, these nodules, or fibrotic lesions, increase in density and
can develop into large fibrotic masses, resulting in progressive
massive fibrosis (PMF). Once established, the fibrotic process of
chronic silicosis is thought to be irreversible (Becklake, 1994,
Document ID 0294). There is no specific treatment for silicosis (Davis,
1996, Document ID 0998; Banks, 2005, 0291).
Chronic silicosis is the most frequently observed type of silicosis
in the U.S. today. Affected workers may have a dry chronic cough,
sputum production, shortness of breath, and reduced pulmonary function.
These symptoms result from airway restriction and/or obstruction caused
by the development of fibrotic scarring in the alveolar sacs and lower
region of the lung. Prospective studies that follow the exposed cohort
over a long period of time with periodic examinations can provide the
best information on factors affecting the development and progression
of silicosis, which has a latency period (the interval between
beginning of exposure to silica and the onset of disease) from 10 to 30
years after first exposure (Weissman and Wagner, 2005; Document ID
0481).
ii. Diagnosis
The scarring caused by silicosis can be detected by chest x-ray or
computerized tomography (CT) when the lesions become large enough to
appear as visible opacities. The clinical diagnosis of silicosis has
three requirements: Recognition by the physician that exposure to
crystalline silica has occurred; the presence of chest radiographic
abnormalities consistent with silicosis; the absence of other illnesses
that could resemble silicosis on a chest radiograph (e.g., pulmonary
fungal infection or tuberculosis) (Balaan and Banks, 1992, Document ID
0289; Banks, 2005, 0291). A standardized system to classify opacities
seen in chest radiographs was developed by the International Labour
Organization (ILO) to describe the presence and severity of silicosis
on the basis of size, shape, and density of opacities, which together
indicate the severity and extent of lung involvement (ILO, 1980,
Document ID 1063; ILO, 2002, 1064; ILO, 2011, 1475; Merchant and
Schwartz, 1998, 1096; NIOSH, 2011, 1513). The density of opacities seen
on chest radiographs is classified on a 4-point category scale (0, 1,
2, or 3), with each category divided into three, giving a 12-
subcategory scale between 0/0 and 3/+. For each subcategory, the top
number indicates the major category that the profusion most closely
resembles, and the bottom number indicates the major category that was
given secondary consideration. Category 0 indicates the absence of
visible opacities and categories 1 to 3 reflect increasing profusion of
opacities and a concomitant increase in severity of disease. The bottom
number can deviate from the top number by 1. At the extremes of the
scale, a designation of 0/- or 3/+ may be used. Subcategory 0/-
represents a radiograph that is obviously absent of small opacities.
Subcategory 3/+ represents a radiograph that shows much greater
profusion than depicted on a standard 3/3 radiograph.
To address the low sensitivity of chest x-rays for detecting
silicosis, Hnizdo et al. (1993, Document ID 1050) recommended that
radiographs consistent with an ILO category of 0/1 or greater be
considered indicative of silicosis among workers exposed to a high
concentration of silica-containing dust. In like manner, to maintain
high specificity, chest x-rays classified as category 1/0 or 1/1 should
be considered as a positive diagnosis of silicosis. A biopsy is not
necessary to make a diagnosis and a diagnosis does not require that
chest x-ray films or digital radiographic images be rated using the ILO
system (NIOSH, 2002, Document ID 1110).
iii. Review of Occupation-Based Epidemiological Studies
The causal relationship between exposure to crystalline silica and
silicosis has long been accepted in the scientific and medical
communities. OSHA reviewed a large number of cross-sectional and
retrospective studies conducted to estimate the quantitative
relationship between exposure to crystalline silica and the development
of silicosis (e.g., Kreiss and Zhen, 1996, Document ID 1080; Love et
al., 1999, 0369; Ng and Chan, 1994, 0382; Rosenman et al., 1996, 0423;
Churchyard et al., 2003, 1295; Churchyard et al., 2004, 0986; Hughes et
al., 1998, 1059; Muir et al., 1989a, 1102; Muir et al., 1989b, 1101;
Park et al., 2002, 0405; Chen et al., 2001, 0332; Chen et al., 2005,
0985; Hnizdo and Sluis-Cremer, 1993, 1052; Miller et al., 1998, 0374;
Buchanan et al., 2003, 0306; Steenland and Brown, 1995b, 0451). In
general, these studies, particularly those that included retirees,
found a risk of radiological silicosis (usually defined as x-ray films
classified as ILO major category 1 or greater) among workers exposed
near the range of cumulative exposures permitted by current exposure
limits. The studies' methods and findings are presented in detail in
the Preliminary QRA (Document ID 1711, pp. 316-340); those studies on
which OSHA relied for its risk estimates are also discussed in the
Summary of the Preliminary QRA, below.
OSHA's review of the silicosis literature also focused on specific
issues associated with the factors that affect the progression of the
disease and the relationship between the appearance of radiological
abnormalities indicative of silicosis and pulmonary function decline.
From its review of the health literature, OSHA made a number of
preliminary findings. First, the size of opacities apparent on initial
x-ray films is a determinant of future disease progression, with subjects
exhibiting large opacities more likely to experience progression than
those having smaller opacities (Hughes et al., 1982, Document
ID 0362; Lee et al., 2001, 1086; Ogawa et al., 2003, 0398).
Second, continued exposure to respirable crystalline silica
following diagnosis of radiological silicosis increases the
probability of disease progression compared to those who are not
further exposed (Hessel et al., 1988, Document ID 1042), although there
remains a likelihood of progression even absent continued exposure
(Hessel et al., 1988, Document ID 1042; Miller et al., 1998, 0374;
Ogawa et al., 2003, 0398; Yang et al., 2006, 1134).
With respect to the relationship between radiological silicosis and
pulmonary function declines, literature findings are mixed. A number of
studies have reported pulmonary function declines among workers
exhibiting a degree of small-opacity profusion consistent with ILO
categories 2 and 3 (e.g., Ng and Chan, 1992, Document ID 1107).
However, although some studies have not found pulmonary function
declines associated with silicosis scored as ILO category 1, a number
of other studies have documented declines in pulmonary function in
persons exposed to silica and whose radiograph readings are in the
major ILO category 1 (i.e., 1/0, 1/1, 1/2), or even before changes were
seen on chest x-ray (Cowie, 1998, 0993; Cowie and Mabena, 1991, 0342;
Ng et al., 1987(a), 1108; Wang et al., 1997, 0478). Thus, OSHA
preliminarily concluded that at least some individuals will develop
pulmonary function declines absent radiological changes indicative of
silicosis. The Agency posited that this may reflect the relatively poor
sensitivity of x-ray films in detecting silicosis or may be due to
pulmonary function declines related to silica-induced chronic
obstructive pulmonary disease (see Document ID 1711, pp. 49-75).
iv. Surveillance
Unlike most occupational diseases, surveillance statistics are
available on silicosis mortality and morbidity in the U.S. The most
comprehensive and current source of surveillance data in the U.S.
related to occupational lung diseases, including silicosis, is the
National Institute for Occupational Safety and Health (NIOSH) Work-
Related Lung Disease (WoRLD) Surveillance System (NIOSH, 2008c,
Document ID 1308). Other sources are detailed in the Review of Health
Effects Literature (Document ID 1711). Mortality data are compiled from
death certificates reported to state vital statistics offices, which
are collected by the National Center for Health Statistics (NCHS), an
agency within the Centers for Disease Control and Prevention (e.g.,
CDC, 2005, Document ID 0319).
Silicosis-related mortality has declined in the U.S. over the time
period for which these data have been collected. From 1968 to 2005, the
annual number of silicosis deaths decreased from 1,157 to 161 (NIOSH,
2008c, Document ID 1308; http://wwwn.cdc.gov/eworld). The CDC cited two
main factors that were likely responsible for the declining trend in
silicosis mortality since 1968 (CDC, 2005, Document ID 0319). First,
many deaths during the early part of the study period were among
workers whose main exposure to respirable crystalline silica probably
occurred before introduction of national silica standards established
by OSHA and the Mine Safety and Health Administration (MSHA) (i.e.,
permissible exposure limits (PELs)); these standards likely led to
reduced silica dust exposure beginning in the 1970s. Second, employment
has declined in heavy industries (e.g., foundries) where silica
exposure was prevalent (CDC, 2005, Document ID 0319).
Despite this decline, silicosis deaths among workers of all ages
result in significant premature mortality; between 1996 and 2005, a
total of 1,746 deaths resulted in a total of 20,234 years of life lost
from life expectancy, with an average of 11.6 years of life lost. For
the same period, among 307 decedents who died before age 65 (the end of
a working life), there were 3,045 years of life lost up to age 65, with
an average of 9.9 years of life lost from a working life (NIOSH, 2008c,
Document ID 1308).
Surveillance data on silicosis morbidity, primarily from hospital
discharge records, are available only from the few states that have
administered disease surveillance programs for silicosis. For the
reporting period 1993-2002, these states recorded 879 cases of
silicosis (NIOSH 2008c, Document ID 1308). Nationwide hospital
discharge data compiled by NIOSH (2008c, Document ID 1308) and the
Council of State and Territorial Epidemiologists (CSTE, 2005, Document
ID 0996) indicate that, for the years 1970 to 2004, there were at least
1,000 hospitalizations that were coded for silicosis each year, except
one.
Relying exclusively on such passive case-based disease surveillance
systems that depend on the health care community to generate records is
likely to understate the prevalence of diseases associated with
respirable crystalline silica (Froines et al., 1989, Document ID 0385).
In order to diagnose occupational diseases, health care professionals
must have information about occupational histories and must be able to
recognize occupational diseases (Goldman and Peters, 1981, Document ID
1027; Rutstein et al., 1983, 0425). The first criterion to be met in
diagnosing silicosis is knowing a patient's history of exposure to
crystalline silica. In addition to the lack of information about
exposure histories, difficulty in recognizing occupational illnesses
like silicosis, that manifest themselves long after initial exposure,
contributes to under-recognition and underreporting by health care
providers. Based on an analysis of data from Michigan's silicosis
surveillance activities, Rosenman et al. (2003, Document ID 0420)
estimated that silicosis mortality and morbidity were understated by a
factor of between 2.5 and 5, and estimated that between 3,600 and 7,300
new cases of silicosis likely occurred in the U.S. annually between
1987 and 1996.
b. Lung Cancer
i. International Agency for Research on Cancer (IARC)
Classification
In 1997, the IARC determined that there was sufficient evidence to
regard crystalline silica as a human carcinogen (IARC, 1997, Document
ID 1062). This finding was based largely on nine studies of cohorts in
four industry sectors that IARC considered to be the least influenced
by confounding factors (sectors included quarries and granite works,
gold mining, ceramic/pottery/refractory brick industries, and the
diatomaceous earth industry). NIOSH also determined that crystalline
silica is a human carcinogen after evaluating updated literature (2002,
Document ID 1110).
ii. Review of Occupation-Based Epidemiological Studies
OSHA conducted an independent review of the epidemiological
literature on exposure to respirable crystalline silica and lung
cancer, covering more than 30 occupational groups in over a dozen
industrial sectors. OSHA's review included approximately 60 primary
epidemiological studies. Based on this review, OSHA preliminarily
concluded that the human data provides ample evidence that exposure to
respirable crystalline silica increases the risk of lung cancer among
workers.
The strongest evidence for carcinogenicity came from studies in
five industry sectors:
Diatomaceous Earth Workers (Checkoway et al., 1993,
Document ID 0324; Checkoway et al., 1996, 0325; Checkoway et al., 1997,
0326;
Checkoway et al., 1999, 0327; Seixas et al., 1997, 0431);
British Pottery Workers (Cherry et al., 1998, Document ID
0335; McDonald et al., 1995, 0371);
Vermont Granite Workers (Attfield and Costello, 2004,
Document ID 0285; Graham et al., 2004, 1031; Costello and Graham, 1988,
0991; Davis et al., 1983, 0999);
North American Industrial Sand Workers (Hughes et al.,
2001, Document ID 1060; McDonald et al., 2001, 1091; McDonald et al.,
2005, 1092; Rando et al., 2001, 0415; Sanderson et al., 2000, 0429;
Steenland and Sanderson, 2001, 0455); and
British Coal Miners (Miller et al., 2007, Document ID
1305; Miller and MacCalman, 2009, 1306).
OSHA considered these studies as providing the strongest evidence
for several reasons. They were all retrospective cohort or case-control
studies that demonstrated positive, statistically significant exposure-
response relationships between exposure to crystalline silica and lung
cancer mortality. Except for the British pottery studies, where
exposure-response trends were noted for average exposure only, lung
cancer risk was found to be related to cumulative exposure. In general,
these studies were of sufficient size and had adequate years of follow
up, and had sufficient quantitative exposure data to reliably estimate
exposures of cohort members. As part of their analyses, the authors of
these studies also found positive exposure-response relationships for
silicosis, indicating that underlying estimates of worker exposures
were not likely to be substantially misclassified. Furthermore, the
authors of these studies addressed potential confounding due to other
carcinogenic exposures through study design or data analysis.
In the diatomaceous earth industry, Checkoway et al. developed a
"semi-quantitative" cumulative exposure estimate that demonstrated a
statistically significant positive exposure-response trend between
duration of employment or cumulative exposure and lung cancer mortality
(1993, Document ID 0324). The quartile analysis with a 15-year lag
showed an increasing trend in relative risks (RR) of lung cancer
mortality, with the highest exposure quartile having a RR of 2.74 for
lung cancer mortality. Checkoway et al. conducted a re-analysis to
address criticisms of potential confounding due to asbestos and again
demonstrated a positive exposure-response risk gradient when
controlling for asbestos exposure and other variables (1996, Document
ID 0325). Rice et al. (2001, Document ID 1118) conducted a re-analysis
and quantitative risk assessment of the Checkoway et al. (1997,
Document ID 0326) study, finding that exposure to crystalline silica
was a significant predictor of lung cancer mortality. OSHA included
this re-analysis in its Preliminary QRA (Document ID 1711).
In the British pottery industry, excess lung cancer risk was found
to be associated with crystalline silica exposure among workers in a
proportionate mortality ratio (PMR) study \4\ (McDonald et al., 1995,
Document ID 0371) and in a cohort and nested case-control study \5\
(Cherry et al., 1998, Document ID 0335). In the former, elevated PMRs
for lung cancer were found after adjusting for potential confounding by
asbestos exposure. In the study by Cherry et al., odds ratios for lung
cancer mortality were statistically significantly elevated after
adjusting for smoking. Odds ratios were related to average, but not
cumulative, exposure to crystalline silica.
---------------------------------------------------------------------------
\4\ A PMR is the number of deaths within a population due to a
specific disease (e.g., lung cancer) divided by the total number of
deaths in the population during some time period.
\5\ A cohort study is a study in which the occurrence of disease
(e.g., lung cancer) is measured in a cohort of workers with
potential for a common exposure (e.g., silica). A nested case-
control study is a study in which workers with disease are
identified in an occupational cohort, and a control group consisting
of workers without disease is selected (independently of exposure
status) from the same cohort to determine whether there is a
difference in exposure between cases and controls. A number of
controls are matched to each case to control for potentially
confounding factors, such as age, gender, etc.
---------------------------------------------------------------------------
In the Vermont granite cohort, Costello and Graham (1988, Document
ID 0991) and Graham et al. (2004, Document ID 1031) in a follow-up
study found that workers employed prior to 1930 had an excess risk of
lung cancer. Lung cancer mortality among granite workers hired after
1940 (post-implementation of controls), however, was not elevated in
the Costello and Graham study and was only somewhat elevated (not
statistically significant) in the Graham et al. study. Graham et al.
(2004, Document ID 1031) concluded that their results did not support a
causal relationship between granite dust exposure and lung cancer
mortality.
Looking at the same population, Attfield and Costello (2004,
Document ID 0285) developed a quantitative estimate of cumulative
exposure (8 exposure categories) adapted from a job exposure matrix
developed by Davis et al. (1983, Document ID 0999). They found a
statistically significant trend between lung cancer mortality and log-
transformed cumulative exposure to crystalline silica. Lung cancer
mortality rose reasonably consistently through the first seven
increasing exposure groups, but fell in the highest cumulative exposure
group. With the highest exposure group omitted, a strong positive dose-
response trend was found for both untransformed and log-transformed
cumulative exposures. The authors explained that the highest exposure
group would have included the most unreliable exposure estimates being
reconstructed from exposures 20 years prior to study initiation when
exposure estimation was less precise. OSHA expressed its belief that
the study by Attfield and Costello (2004, Document ID 0285) was of
superior design in that it used quantitative estimates of exposure and
evaluated lung cancer mortality rates by exposure group. In contrast,
the findings by Graham et al. (2004, Document ID 1031) were based on a
dichotomous comparison of risk among high- versus low-exposure groups,
where date-of-hire before and after implementation of ventilation
controls was used as a surrogate for exposure. Consequently, OSHA used
the Attfield and Costello study in its Preliminary QRA (Document ID
1711). In its Supplemental Literature Review of Epidemiological Studies
on Lung Cancer Associated with Exposure to Respirable Crystalline
Silica, OSHA also discussed a more recent study of Vermont granite
workers by Vacek et al. (2011, Document ID 1486) that did not find an
association between silica exposure and lung cancer mortality (Document
ID 1711, Attachment 1, pp. 2-5). (OSHA examines this study in great
length in Section V.F, Comments and Responses Concerning Lung Cancer
Mortality.)
In the North American industrial sand industry, studies of two
overlapping cohorts found a statistically significant increased risk of
lung cancer mortality with increased cumulative exposure in both
categorical and continuous analyses (Hughes et al., 2001, Document ID
1060; McDonald et al., 2001, 1091; McDonald et al., 2005, 1092; Rando
et al., 2001, 0415; Sanderson et al., 2000, 0429; Steenland and
Sanderson, 2001, 0455). McDonald et al. (2001, Document ID 1091)
examined a cohort that entered the workforce, on average, a decade
earlier than the cohorts that Steenland and Sanderson (2001, Document
ID 0455) examined. The McDonald cohort, drawn from eight plants, had
more years of exposure in the industry (19 versus 8.8 years). The
Steenland and Sanderson (2001, Document ID 0455) cohort worked in 16
plants, 7 of which overlapped with the McDonald, et al.
(2001, Document ID 1091) cohort. McDonald et al. (2001, Document ID
1091), Hughes et al. (2001, Document ID 1060), and Rando et al. (2001,
Document ID 0415) had access to smoking histories, plant records, and
exposure measurements that allowed for historical reconstruction and
the development of a job exposure matrix. The McDonald et al. (2005,
Document ID 1092) study was a later update, with follow-up through
2000, of both the cohort and nested case-control studies. Steenland and
Sanderson (2001, Document ID 0455) had limited access to plant
facilities, less detailed historic exposure data, and used MSHA
enforcement records for estimates of recent exposure. These studies
(Hughes et al., 2001, Document ID 1060; McDonald et al., 2005, 1092;
Steenland and Sanderson, 2001, 0455) showed very similar exposure-
response patterns of increased lung cancer mortality with increased
exposure. OSHA included the quantitative exposure-response analysis
from the Hughes et al. (2001, Document ID 1060) study in its
Preliminary QRA, as it allowed for individual job, exposure, and
smoking histories to be taken into account.
OSHA noted that Brown and Rushton (2005a, Document ID 0303; 2005b,
0304) found no association between risk of lung cancer mortality and
exposure to respirable crystalline silica among British industrial sand
workers. However, a large portion of the cohort had relatively short
service times in the industry, with over one-half the cohort deaths and
almost three-fourths of the lung cancer mortalities having had less
than 10 years of service. Considering the apparent high turnover in
this industry and the absence of prior occupational histories,
exposures from work experience other than in the industrial sand
industry could be a significant confounder (Document ID 1711, p. 131).
Additionally, as Steenland noted in a letter review (2005a, Document ID
1313), the cumulative exposures of workers in the Brown and Ruston
(2005b, Document ID 0304) study were over 10 times lower than the
cumulative exposures experienced by the cohorts in the pooled analysis
that Steenland et al. (2001a, Document ID 0452) performed. The low
exposures experienced by this cohort would have made detecting a
positive association with lung cancer mortality even more difficult.
In British coal miners, excess lung cancer mortality was reported
in a large cohort study, which examined the mortality experience of
17,800 miners through the end of 2005 (Miller et al., 2007, Document ID
1305; Miller and MacCalman, 2009, 1306). By that time, the cohort had
accumulated 516,431 person years of observation (an average of 29 years
per miner), with 10,698 deaths from all causes. Overall lung cancer
mortality was elevated (SMR = 115.7, 95% C.I. 104.8-127.7), and a
positive exposure-response relationship with crystalline silica
exposure was determined from Cox regression after adjusting for smoking
history. Three of the strengths of this study were the detailed time-
exposure measurements of both quartz and total mine dust, detailed
individual work histories, and individual smoking histories. For lung
cancer, analyses based on Cox regression provided strong evidence that,
for these coal miners, although quartz exposures were associated with
increased lung cancer risk, simultaneous exposures to coal dust did not
cause increased lung cancer risk. Because of these strengths, OSHA
included this study in its Preliminary QRA (Document ID 1711).
In addition to the studies in these cohorts, OSHA also reviewed
studies of lung cancer mortality in metal ore mining populations. Many
of these mining studies, which showed mixed results, were subject to
confounding due to exposure to other potential carcinogens such as
radon and arsenic. IARC noted that only a few ore mining studies
accounted for confounding from other occupational carcinogens and that,
when confounding was absent or accounted for, an association between
silica exposure and lung cancer was absent (1997, Document ID 1062).
Many of the studies conducted since IARC's review, however, more
strongly implicate crystalline silica as a human carcinogen (1997,
Document ID 1062). Pelucchi et al. (2006, Document ID 0408), in a meta-
analysis of studies conducted since IARC's (1997, Document ID 1062)
review, reported statistically significantly elevated relative risks of
lung cancer mortality in underground and surface miners in three cohort
and four case-control studies. Cassidy et al., in a pooled case-control
analysis, showed a statistically significant increased risk of lung
cancer mortality among miners (OR = 1.48), and demonstrated a linear
trend of increasing odds ratios with increasing exposures (2007,
Document ID 0313).
OSHA also preliminarily determined that the results of the studies
conducted in three industry sectors (foundry, silicon carbide, and
construction sectors) were confounded by the presence of exposures to
other carcinogens. Exposure data from these studies were not sufficient
to distinguish between exposure to silica dust and exposure to other
occupational carcinogens. IARC previously made a similar determination
in reference to the foundry industry. However, with respect to the
construction industry, Cassidy et al. (2007, Document ID 0313), in a
large European community-based case-control study, reported finding a
clear linear trend of increasing odds ratios with increasing cumulative
exposure to crystalline silica (estimated semi-quantitatively) after
adjusting for smoking and exposure to insulation and wood dusts.
In addition, an analysis of 4.8 million death certificates from 27
states within the U.S. for the years 1982 to 1995 showed statistically
significant excesses in lung cancer mortality, silicosis mortality,
tuberculosis, and NMRD among persons with occupations involving medium
and high exposure to respirable crystalline silica (Calvert et al.,
2003, Document ID 0309). A national records and death certificate study
was also conducted in Finland by Pukkala et al., who found a
statistically significant excess of lung cancer incidence among men and
women with estimated medium and heavy exposures (2005, Document ID
0412).
One of the more compelling studies OSHA evaluated and used in the
Preliminary QRA (Document ID 1711) was Steenland et al.'s (2001a,
Document ID 0452) pooled analysis of 10 occupational cohorts (5 mines
and 5 industrial facilities), which demonstrated an overall positive
exposure-response relationship between cumulative exposure to
crystalline silica and lung cancer mortality. These 10 cohorts included
65,980 workers and 1,072 lung cancer deaths, and were selected because
of the availability of raw data on exposure to crystalline silica and
health outcomes. The investigators found lung cancer risk increased
with increasing cumulative exposure, log cumulative exposure, and
average exposure. Exposure-response trends were similar between mining
and non-mining cohorts.
iii. Confounding
Smoking is known to be a major risk factor for lung cancer.
However, OSHA maintained in the Preliminary QRA that it is unlikely
that smoking explained the observed exposure-response trends in the
studies described above (Document ID 1711). Studies by Hnizdo et al.
(1997, Document ID 1049), McLaughlin et al. (1992, Document ID 0372),
Hughes et al. (2001, Document ID 1060), McDonald et al. (2001, Document
ID 1091; 2005, 1092), Miller and MacCalman (2009, Document ID 1306),
and Cassidy et al. (2007, Document ID 0313) had detailed smoking
histories with sufficiently large populations and a sufficient
number of years of follow-up time to quantify the interaction
between crystalline silica exposure and cigarette smoking.
In a cohort of white South African gold miners (Hnizdo and
Sluis-Cremer, 1991, Document ID 1051) and in the follow-up nested
case-control study (Hnizdo et al., 1997, Document ID 1049), the
combined effect of exposure to respirable crystalline silica and
smoking was greater than additive, suggesting a multiplicative effect.
This effect appeared to be greatest for miners with greater than 35
pack-years of smoking and higher cumulative exposure to silica. In the
Chinese nested case-control studies (McLaughlin et al., 1992, Document
ID 0372), cigarette smoking was associated with lung cancer, but
control for smoking did not influence the association between silica
and lung cancer in the mining and pottery cohorts studied. The studies
of industrial sand workers (Hughes et al., 2001, Document ID 1060) and
British coal workers (Miller and MacCalman, 2009, Document ID 1306)
found positive exposure-response trends after adjusting for smoking
histories, as did Cassidy et al. (2007, Document ID 0313) in their
community-based case-control study of exposed European workers.
Given these findings of investigators who have accounted for the
impact of smoking, OSHA preliminarily determined that the weight of the
evidence reviewed identified respirable crystalline silica as an
independent risk factor for lung cancer mortality. OSHA also determined
that its finding was further supported by animal studies demonstrating
that exposure to silica alone can cause lung cancer (e.g., Muhle et
al., 1995, Document ID 0378).
iv. Lung Cancer and Silicosis
Animal and in vitro studies have demonstrated that the early steps
in the proposed mechanistic pathways that lead to silicosis and lung
cancer seem to share some common features (see Document ID 1711, pp.
171-172). This has led some researchers to suggest that silicosis is a
prerequisite to lung cancer. Some have suggested that any increased
lung cancer risk associated with silica may be a consequence of
inflammation (and concomitant oxidative stress) and increased
epithelial cell proliferation associated with the development of
silicosis. However, other researchers have noted additional genotoxic
and non-genotoxic mechanisms that may also be involved in
carcinogenesis induced by silica (see Section V.H, Mechanisms of
Silica-Induced Adverse Health Effects, and Document ID 1711, pp. 230-
239). IARC also noted that a direct genotoxic mechanism from silica to
induce a carcinogenic effect cannot be ruled out (2012, Document ID
1473). Thus, OSHA preliminarily concluded that available animal and in
vitro studies do not support the hypothesis that development of
silicosis is necessary for silica exposure to cause lung cancer.
In general, studies of workers with silicosis, as well as meta-
analyses that include these studies, have shown that workers with
radiologic evidence of silicosis have higher lung cancer risk than
those without radiologic abnormalities or mixed cohorts. Three meta-
analyses attempted to look at the association of increasing ILO
radiographic categories of silicosis with increasing lung cancer
mortality. Two of these analyses (Kurihara and Wada, 2004, Document ID
1084; Tsuda et al., 1997, 1127) showed no association with increasing
lung cancer mortality, while Lacasse et al. (2005, Document ID 0365)
demonstrated a positive dose-response for lung cancer with increasing
ILO radiographic category. A number of other studies found increased
lung cancer risk among exposed workers absent radiological evidence of
silicosis (Cassidy et al., 2007, Document ID 0313; Checkoway et al.,
1999, 0327; Cherry et al., 1998, 0335; Hnizdo et al., 1997, 1049;
McLaughlin et al., 1992, 0372). For example, the diatomaceous earth
study by Checkoway et al. showed a statistically significant exposure-
response relationship for lung cancer among persons without silicosis
(1999, Document ID 0327). Checkoway and Franzblau, reviewing the
international literature, found that all epidemiological studies
conducted to that date were insufficient to conclusively determine the
role of silicosis in the etiology of lung cancer (2000, Document ID
0323). OSHA preliminarily concluded that the more recent pooled and
meta-analyses do not provide compelling evidence that silicosis is a
necessary precursor to lung cancer.
c. Non-Malignant Respiratory Diseases (Other Than Silicosis)
In addition to causing silicosis, exposure to crystalline silica
has been associated with increased risks of other non-malignant
respiratory diseases (NMRD), primarily chronic obstructive pulmonary
disease (COPD), chronic bronchitis, and emphysema. COPD is a disease
state characterized by airflow limitation that is usually progressive
and not fully reversible. In patients with COPD, either chronic
bronchitis or emphysema may be present or both conditions may be
present together.
As detailed in the Review of Health Effects Literature, OSHA
reviewed several studies of NMRD morbidity and preliminarily concluded
that exposure to respirable crystalline silica may increase the risk of
emphysema, chronic bronchitis, and pulmonary function impairment,
regardless of whether signs of silicosis are present (Document ID
1711). Smokers may be at an increased risk relative to nonsmokers.
OSHA also reviewed studies of NMRD mortality that focused on causes
of death other than silicosis. Wyndham et al. found a significant
excess mortality for chronic respiratory diseases in a cohort of white
South African gold miners (1986, Document ID 0490). A case-referent
analysis found that, although the major risk factor for chronic
respiratory disease was smoking, there was a statistically significant
additional effect of cumulative exposure to silica-containing dust. A
multiplicative effect of smoking and cumulative dust exposure on
mortality from COPD was found in another study of white South African
gold miners (Hnizdo, 1990, Document ID 1045). Analysis of various
combinations of dust exposure and smoking found a trend in odds ratios
that indicated this synergism. There was a statistically significant
increasing trend for dust particle-years and for cigarette-years of
smoking.
Park et al. (2002, Document ID 0405) analyzed the California
diatomaceous earth cohort data originally studied by Checkoway et al.
(1997, Document ID 0326), consisting of 2,570 diatomaceous earth
workers employed for 12 months or more from 1942 to 1994, to quantify
the relationship between exposure to cristobalite and mortality from
chronic lung disease other than cancer (LDOC). Diseases in this
category included pneumoconiosis (which included silicosis), chronic
bronchitis, and emphysema, but excluded pneumonia and other infectious
diseases. Smoking information was available for about 50 percent of the
cohort and for 22 of the 67 LDOC deaths available for analysis,
permitting at least partial adjustment for smoking. Using the exposure
estimates developed for the cohort by Rice et al. (2001, Document ID
1118) in their exposure-response study of lung cancer risks, Park et
al. (2002, Document 0405) evaluated the quantitative exposure-response
relationship for LDOC mortality and found a strong positive
relationship with exposure to respirable crystalline silica. OSHA found
this study particularly compelling because of the strengths of the
study design and availability of smoking history data on part of the
cohort, as well as the high-quality exposure and job history data.
The study authors noted:
Data on smoking, collected since the 1960s in the company's
radiographic screening programme, were available for 1171 of the
subjects (50%). However, smoking habits were unknown for 45 of the
67 workers that died from LDOC (67%). Our Poisson regression
analyses for LDOC, stratified on smoking, have partially rectified
the confounding by smoking issue. Furthermore, analyses performed
without control for smoking produced slightly smaller and less
precise estimates of the effects of silica, suggesting that smoking
is a negative confounder. In their analysis of this cohort,
Checkoway et al. applied the method of Axelson concluding that it
was very unlikely that cigarette smoking could account for the
association found between mortality from LDOC and cumulative
exposure to silica (Document ID 0405, p. 41).
Consequently, OSHA used this study in its Preliminary QRA (Document
ID 1711, pp. 295-298).
Based on this evidence, and the other studies discussed in the
Review of Health Effects Literature, OSHA preliminarily concluded that
respirable crystalline silica increases the risk for mortality from
non-malignant respiratory disease (not including silicosis) in an
exposure-related manner. The Agency also preliminarily concluded that
the risk is strongly influenced by smoking, and opined that the effects
of smoking and silica exposure may be synergistic.
d. Renal Disease and Autoimmune Diseases
In its Review of Health Effects Literature, OSHA described the
available experimental and epidemiological data evaluating respirable
crystalline silica exposure and renal and/or autoimmune effects
(Document ID 1711). In addition to a number of case reports,
epidemiological studies have found statistically significant
associations between occupational exposure to silica dust and chronic
renal disease (Calvert et al., 1997, Document ID 0976), subclinical
renal changes (Ng et al., 1992c, Document ID 0386), end-stage renal
disease morbidity (Steenland et al., 1990, Document ID 1125), chronic
renal disease mortality (Steenland et al., 2001b, Document ID 0456;
2002a, 0448), and granulomatosis with polyangitis, a condition that can
affect the kidneys (Nuyts et al., 1995, Document ID 0397). In other
findings, silica-exposed individuals, both with and without silicosis,
had an increased prevalence of abnormal renal function (Hotz et al.,
1995, Document ID 0361), and renal effects have been reported to
persist after cessation of silica exposure (Ng et al., 1992c, Document
ID 0386). Possible mechanisms suggested for silica-induced renal
disease include a direct toxic effect on the kidney, deposition of
immune complexes (IgA) in the kidney following silica related pulmonary
inflammation, and an autoimmune mechanism (Calvert et al., 1997,
Document ID 0976; Gregorini et al., 1993, 1032).
In a pooled cohort analysis, Steenland et al. (2002a, Document ID
0448) combined the industrial sand cohort from Steenland et al. (2001b,
Document ID 0456), the gold mining cohort from Steenland and Brown
(1995a, Document ID 0450), and the Vermont granite cohort studies by
Costello and Graham (1988, Document ID 0991). In all, the combined
cohort consisted of 13,382 workers with exposure information available
for 12,783. The analysis demonstrated statistically significant
exposure-response trends for acute and chronic renal disease mortality
with quartiles of cumulative exposure to respirable crystalline silica.
In a nested case-control study design, a positive exposure-response
relationship was found across the three cohorts for both multiple-cause
mortality (i.e., any mention of renal disease on the death certificate)
and underlying cause mortality. Renal disease risk was most prevalent
among workers with cumulative exposures of 500 [micro]g/m\3\ or more
(Steenland et al., 2002a, Document ID 0448).
OSHA noted that other studies failed to find an excess renal
disease risk among silica-exposed workers. Davis et al. (1983, Document
ID 0999) found elevated, but not statistically significant, mortality
from diseases of the genitourinary system among Vermont granite shed
workers. There was no observed relationship between mortality from this
cause and cumulative exposure. A similar finding was reported by
Koskela et al. (1987, Document ID 0363) among Finnish granite workers,
where there were 4 deaths due to urinary tract disease compared to 1.8
expected. Both Carta et al. (1994, Document ID 0312) and Cocco et al.
(1994, Document ID 0988) reported finding no increased mortality from
urinary tract disease among workers in an Italian lead mine and zinc
mine. However, Cocco et al. (1994, Document ID 0988) commented that
exposures to respirable crystalline silica were low, averaging 7 and 90
[micro]g/m\3\ in the two mines, respectively, and that their study in
particular had low statistical power to detect excess mortality.
OSHA expressed its belief that there is substantial evidence,
particularly the 3-cohort pooled analysis conducted by Steenland et al.
(2002a, Document ID 0448), on which to base a finding that exposure to
respirable crystalline silica increases the risk of renal disease
mortality and morbidity. The pooled analysis by Steenland et al.
involved a large number of workers from three cohorts with well-
documented, validated job-exposure matrices; it found a positive,
monotonic increase in renal disease risk with increasing exposure for
both underlying and multiple cause data (2002a, Document ID 0448).
However, there are considerably less data available for renal disease
than there are for silicosis mortality and lung cancer mortality. The
findings based on these data are, therefore, less robust. Nevertheless,
OSHA preliminarily concluded that the underlying data are sufficient to
provide useful estimates of risk and included the Steenland et al.
(2002a, Document ID 0448) analysis in its Preliminary QRA.
For autoimmune effects, OSHA reviewed epidemiological information
suggesting an association between respirable silica exposure and
autoimmune diseases, including scleroderma (Sluis-Cremer et al., 1985,
Document ID 0439), rheumatoid arthritis (Klockars et al., 1987,
Document ID 1075; Rosenman and Zhu, 1995, 0424), and systemic lupus
erythematosus (Brown et al., 1997, Document ID 0974). However, there
were no quantitative exposure-response data available on which to base
a quantitative risk assessment for autoimmune diseases.
e. Physical Factors Affecting Toxicity of Crystalline Silica
OSHA also examined evidence on the comparative toxicity of the
silica polymorphs (quartz, cristobalite, and tridymite). A number of
animal studies appear to suggest that cristobalite and tridymite are
more toxic to the lung than quartz and more tumorigenic (e.g., King et
al., 1953, Document ID 1072; Wagner et al., 1980, 0476). However, in
contrast to these findings, several authors have reviewed the studies
done in this area and concluded that cristobalite and tridymite are not
more toxic than quartz (e.g., Bolsaitis and Wallace, 1996, Document ID
0298; Guthrie and Heaney, 1995, 1035). Furthermore, a difference in
toxicity between cristobalite and quartz has not been observed in
epidemiological studies (tridymite has not been studied) (NIOSH, 2002,
Document ID 1110). In an analysis of exposure-response for lung cancer,
Steenland et al. found similar exposure-response trends between
cristobalite-exposed workers and other cohorts exposed to quartz
(2001a, Document ID 0452).
OSHA also discussed other physical factors that may influence the
toxicologic potency of crystalline silica. A number of animal studies
compared the toxicity of freshly fractured silica to that of aged
silica (Porter et al., 2002, Document ID 1114; Shoemaker et al., 1995,
0437; Vallyathan et al., 1995, 1128). These studies have demonstrated
that although freshly fractured silica is more toxic than aged silica,
aged silica still retains significant toxicity. There have been no
studies comparing workers exposed to freshly fractured silica to those
exposed to aged silica. However, similarities between the results of
animal and human studies involving freshly fractured silica suggest
that the animal studies involving aged silica may also apply to humans.
For example, studies of workers exposed to freshly fractured silica
have demonstrated that these workers exhibit the same cellular effects
as seen in animals exposed to freshly fractured silica (Castranova et
al., 1998, Document ID 1294; Goodman et al., 1992, 1029). Animal
studies also suggest that pulmonary reactions of rats to short-duration
exposure to freshly fractured silica mimic those seen in acute
silicosis in humans (Vallyathan et al., 1995, Document ID 1128).
Surface impurities, particularly metals, have been shown to alter
silica toxicity. Iron, depending on its state and quantity, has been
shown to either increase or decrease toxicity (see Document ID 1711,
pp. 247-258). Aluminum has been shown to decrease toxicity (Castranova
et al., 1997, Document ID 0978; Donaldson and Borm, 1998, 1004; Fubini,
1998, 1016). Silica coated with aluminosilicate clay exhibits lower
toxicity, possibly as a result of reduced bioavailability of the silica
particle surface (Donaldson and Borm, 1998, Document ID 1004; Fubini,
1998, 1016). Aluminum as well as other metal ions are thought to modify
silanol groups on the silica surface, thus decreasing the membranolytic
and cytotoxic potency and resulting in enhanced particle clearance from
the lung before damage can take place (Fubini, 1998, Document ID 1016).
An epidemiological study found that the risk of silicosis was less in
pottery workers than in tin and tungsten miners (Chen et al., 2005,
Document ID 0985; Harrison et al., 2005, 1036), possibly reflecting
that pottery workers were exposed to silica particles having less
biologically-available, non-clay-occluded surface area than was the
case for miners.
Although it is evident that a number of factors can act to mediate
the toxicological potency of crystalline silica, it is not clear how
such considerations should be taken into account to evaluate lung
cancer and silicosis risks to exposed workers. After evaluating many in
vitro studies that investigated the surface characteristics of
crystalline silica particles and their influence on fibrogenic
activity, NIOSH concluded that further research is needed to associate
specific surface characteristics that can affect toxicity with specific
occupational exposure situations and consequent health risks to workers
(2002, Document ID 1110). Thus, OSHA preliminarily concluded that while
there was considerable evidence that several environmental influences
can modify surface activity to either enhance or diminish the toxicity
of silica, the available information was insufficient to determine in
any quantitative way how these influences may affect disease risk to
workers in any particular workplace setting.
3. Summary of the Preliminary QRA
OSHA presented in the Preliminary QRA estimates of the risk of
silica-related diseases assuming exposure over a working life (45
years, from age 20 to age 65) to the revised 8-hour time-weighted
average (TWA) PEL of 50 [micro]g/m\3\ respirable crystalline silica,
the new action level of 25 [micro]g/m\3\, and the previous PELs. OSHA's
previous general industry PEL for respirable quartz was expressed both
in terms of a particle count formula and a gravimetric concentration
formula; the previous construction and shipyard employment PELs for
respirable quartz were only expressed in terms of a particle count
formula. For general industry, as the quartz content increases, the
gravimetric PEL approached a limit of 100 [micro]g/m\3\ respirable
quartz. For construction and shipyard employment, OSHA's previous PELs
used a formula that limits exposure to respirable dust, depending upon
the quartz content, expressed as a respirable particle count
concentration. There was no single mass concentration equivalent for
the construction and shipyard employment PELs; OSHA reviewed several
studies that suggest that the previous construction/shipyard PEL likely
was between 250 and 500 [micro]g/m\3\ respirable quartz. In general
industry, for both the gravimetric and particle count PELs, OSHA's
previous PELs for cristobalite and tridymite were half the value for
quartz. Based upon these previous PELs and the new action level, OSHA
presented risk estimates associated with exposure over a working life
to 25, 50, 100, 250, and 500 [micro]g/m\3\ respirable silica
(corresponding to cumulative exposures over 45 years to 1.125, 2.25,
4.5, 11.25, and 22.5 mg/m\3\-yrs).
To estimate lifetime excess mortality risks at these exposure
levels, OSHA implemented each of the risk models in a life table
analysis that accounted for competing causes of death due to background
causes and cumulated risk through age 85. For these analyses, OSHA used
lung cancer, NMRD, or renal disease mortality and all-cause mortality
rates to account for background risks and competing risks (U.S. 2006
data for lung cancer and NMRD mortality in all males, 1998 data for
renal disease mortality, obtained from cause-specific death rate tables
published by the National Center for Health Statistics (2009, Document
ID 1104)). OSHA calculated these risk estimates assuming occupational
exposure from age 20 to age 65. The mortality risk estimates were
presented in terms of lifetime excess risk per 1,000 workers for
exposure over an 8-hour working day, 250 days per year, and a 45-year
working life.
For silicosis morbidity, OSHA based its risk estimates on
cumulative risk models used by various investigators to develop
quantitative exposure-response relationships. These models
characterized the risk of developing silicosis (as detected by chest
radiography) up to the time that cohort members (including both active
and retired workers) were last examined. Thus, risk estimates derived
from these studies represented less-than-lifetime risks of developing
radiographic silicosis. OSHA did not attempt to estimate lifetime risk
(i.e., up to age 85) for silicosis morbidity because the relationships
between age, time, and disease onset post-exposure have not been well
characterized.
a. Silicosis and NMRD Mortality
i. Exposure-Response Studies
In the Preliminary QRA, OSHA relied upon two published quantitative
risk studies of silicosis and NMRD mortality (Document ID 1711). The
first, Mannetje et al. (2002b, Document ID 1089) conducted a pooled
analysis of silicosis mortality in which there were 18,634 subjects,
150 silicosis deaths, and 20 deaths from unspecified pneumoconiosis.
Rates for silicosis adjusted for age, calendar time, and study were
estimated by Poisson regression and increased nearly monotonically with
deciles of cumulative exposure, from a mortality rate of 5/100,000
person-years in the lowest exposure category (0-0.99 mg/m\3\-yrs) to
299/100,000 person-years in the highest category (>28.10 mg/m\3\-yrs).
As previously discussed, the second, Park et al. (2002, Document ID
0405) analyzed the California diatomaceous earth cohort data from
Checkoway et al. (1997, Document ID 0326), and examined mortality from
chronic lung disease other than cancer (LDOC; also known as non-
malignant respiratory disease (NMRD)). Smoking information was
available for about 50 percent of the cohort and for 22 of the 67 LDOC
deaths available for analysis, permitting Park et al. (2002, Document
ID 0405) to partially adjust for smoking. Estimates of LDOC mortality
risks were derived via Poisson and Cox proportional hazards models; a
variety of relative rate model forms were fit to the data, with a
linear relative rate model selected for estimating risks.
ii. Risk Estimates
As silicosis is only caused by exposure to respirable crystalline
silica (i.e., there is no background rate of silicosis in the unexposed
population), absolute risks of silicosis mortality rather than excess
risks were calculated for the Mannetje et al. pooled analysis (2002b,
Document ID 1089). These risk estimates were derived from the rate
ratios incorporating simulated measurement error reported by
ToxaChemica (Document ID 0469). OSHA's estimate of lifetime risk of
silicosis mortality, for 45 years of exposure to the previous general
industry PEL, was 11 deaths per 1,000 workers for the pooled analysis
(Document ID 1711). At the revised PEL, the risk estimate was 7 deaths
per 1,000.
OSHA also calculated preliminary risk estimates for NMRD mortality.
These estimates were derived from Park et al. (2002, Document ID 0405).
For 45 years of exposure to the previous general industry PEL, OSHA
preliminarily estimated lifetime excess risk at 83 deaths per 1,000
workers. At the revised PEL, OSHA estimated 43 deaths per 1,000
workers.
OSHA noted that, for exposures up to 250 [micro]g/m\3\, the
mortality risk estimates based on Park et al. (2002, Document ID 0405)
are about 5 to 11 times as great as those calculated for the pooled
analysis of silicosis mortality (Mannetje et al., 2002b, Document ID
1089). These two sets of risk estimates, however, are not directly
comparable, as the endpoint for the Park et al. (2002, Document ID
0405) analysis was death from all non-cancer lung diseases, including
pneumoconiosis, emphysema, and chronic bronchitis, whereas the pooled
analysis by Mannetje et al. (2002b, Document ID 1089) included only
deaths coded as silicosis or other pneumoconiosis. Less than 25 percent
of the LDOC deaths in the Park et al. analysis were coded as silicosis
or other pneumoconiosis (15 of 67), suggesting that silicosis as a
cause of death may be misclassified as emphysema or chronic bronchitis.
Thus, Mannetje et al.'s (2002b, Document ID 1089) selection of deaths
may tend to underestimate the true risk of silicosis mortality, and
Park et al.'s (2002, Document ID 0405) analysis may more completely
capture the total respiratory mortality risk from all non-malignant
causes.
Since the time of OSHA's analysis, NCHS has released updated all-
cause mortality and NMRD mortality background rates from 2011
(http://wonder.cdc.gov/ucd-icd10.html); OSHA's final risk estimates for NMRD
mortality, which incorporate these updated rates (ICD10 codes J40-J47,
chronic lower respiratory diseases; J60-J66, J68, pneumoconiosis and
chemical effects), are available in Section VI, Final Quantitative Risk
Assessment and Significance of Risk.
b. Lung Cancer Mortality
i. Exposure-Response Studies
In 1997, when IARC determined that there was sufficient evidence to
regard crystalline silica as a human carcinogen, it also noted that
some epidemiological studies did not demonstrate an excess risk of lung
cancer and that exposure-response trends were not always consistent
among studies that were able to describe such trends (Document ID
1062). These findings led Steenland et al. (2001a, Document ID 0452) to
conduct a comprehensive exposure-response analysis--the IARC multi-
center study--of the risk of lung cancer associated with exposure to
crystalline silica. This study relied on all available cohort data from
previously-published epidemiological studies for which there were
adequate quantitative data on worker silica exposures to derive pooled
estimates of disease risk. In addition, as discussed previously, OSHA
identified four more recent studies suitable for quantitative risk
assessment: (1) An exposure-response analysis by Rice et al. (2001,
Document ID 1118) of a cohort of diatomaceous earth workers primarily
exposed to cristobalite; (2) an analysis by Attfield and Costello
(2004, Document ID 0285) of U.S. granite workers; (3) an exposure-
response analysis by Hughes et al. (2001, Document ID 1060) of U.S.
industrial sand workers; and (4) a risk analysis by Miller et al.
(2007, Document ID 1305) and Miller and MacCalman (2009, Document ID
1306) of British coal miners. OSHA thoroughly described each of these
studies in its Preliminary QRA (Document ID 1711); a brief summary of
the exposure-response models used in each study is provided here.
The Steenland et al. pooled exposure-response analysis was based on
data obtained from ten cohorts of silica-exposed workers (65,980
workers, 1,072 lung cancer deaths) (2001a, Document ID 0452). The
pooled analysis cohorts included U.S. gold miners (Steenland and Brown,
1995a, Document ID 0450), U.S. diatomaceous earth workers (Checkoway et
al., 1997, Document ID 0326), Australian gold miners (de Klerk and
Musk, 1998, Document ID 0345), Finnish granite workers (Koskela et al.,
1994, Document ID 1078), U.S. industrial sand employees (Steenland and
Sanderson, 2001, Document ID 0455), Vermont granite workers (Costello
and Graham, 1988, Document ID 0991), South African gold miners (Hnizdo
and Sluis-Cremer, 1991, Document ID 1051; Hnizdo et al.,1997, 1049),
and Chinese pottery workers, tin miners, and tungsten miners (Chen et
al., 1992, Document ID 0329).
Steenland et al. (2001a, Document ID 0452) performed a nested case-
control analysis via Cox regression. There were 100 controls chosen for
each case randomly from among cohort members who survived past the age
at which the case died; controls were matched on age (the time variable
in Cox regression), study, race/ethnicity, sex, and date of birth
within 5 years. Steenland et al. found that the use of any of the
following continuous exposure variables in a log linear relative risk
model resulted in positive statistically significant (p <= 0.05)
exposure-response coefficients: (1) Cumulative exposure with a 15-year
lag; (2) the log of cumulative exposure with a 15-year lag; and (3)
average exposure (2001a, Document ID 0452). The models that provided
the best fit to the data used cumulative exposure and log-transformed
cumulative exposure. Models that used log-transformed cumulative
exposure also showed no statistically significant heterogeneity among
cohorts (p = 0.36), possibly because they are less influenced by very
high exposures. At OSHA's request, Steenland (2010, Document ID 1312)
also conducted a categorical analysis of the pooled data set and
additional analyses using linear relative risk models (with and without
the log transformation of cumulative exposure) as well as a two-piece
spline model (see Document ID 1711, pp. 276-278).
Rice et al. (2001, Document ID 1118) applied a variety of exposure-
response models to the California diatomaceous earth cohort data
originally studied by Checkoway et al. (1993, Document ID 0324; 1996,
0325; 1997, 0326) and included in the Steenland et al. (2001a, Document
ID 0452) pooled analysis. The cohort consisted of 2,342 white males
employed for at least one year between 1942 and 1987 in a California
diatomaceous earth mining and processing plant. The cohort was followed
until 1994, and included 77 lung cancer deaths. Rice et al. reported
that exposure to crystalline silica was a significant predictor of lung
cancer mortality for nearly all of the models employed, with the linear
relative risk model providing the best fit to the data in the Poisson
regression analysis (2001, Document ID 1118).
Attfield and Costello (2004, Document ID 0285) analyzed the U.S.
granite cohort originally studied by Costello and Graham (1988,
Document ID 0991) and Davis et al. (1983, Document ID 0999) and
included in the Steenland et al. (2001a, Document ID 0452) pooled
analysis. The cohort consisted of 5,414 male granite workers who were
employed in the Vermont granite industry between 1950 and 1982 and who
had received at least one chest x-ray from the surveillance program of
the Vermont Department of Industrial Hygiene. The 2004 report by
Attfield and Costello extended follow-up from 1982 to 1994, and found
201 deaths (Document ID 0285). Using Poisson regression models, the
results of a categorical analysis showed a generally increasing trend
of lung cancer rate ratios with increasing cumulative exposure.
As mentioned previously, however, the rate ratio for the highest
exposure group in the Attfield and Costello analysis (cumulative
exposures of 6.0 mg/m\3\-yrs or higher) was substantially lower than
that for other exposure groups (2004, Document ID 0285). The authors
reported that the best-fitting model had a 15-year lag, untransformed
cumulative exposure, and the omission of this highest exposure group.
The authors argued that it was appropriate to omit the highest exposure
group for several reasons, including that the exposure estimates for
the highest exposure group were less reliable, and there was a greater
likelihood of cohort selection effects, competing causes of death, and
misdiagnosis (Document ID 0285, p. 136).
McDonald et al. (2001, Document ID 1091), Hughes et al. (2001,
Document ID 1060) and McDonald et al. (2005, Document ID 1092) followed
up on a cohort study of North American industrial sand workers included
in the Steenland et al. (2001a, Document ID 0452) pooled analysis. The
McDonald et al. cohort included 2,670 men employed before 1980 for
three years or more in one of nine North American (8 U.S. and 1
Canadian) sand-producing plants, including 1 large associated office
complex (2001, Document ID 1091). A nested case-control study based on
90 lung cancer deaths (through 1994) from this cohort was conducted by
Hughes et al. (2001, Document ID 1060). A subsequent update (through
2000, 105 lung cancer deaths) eliminated the Canadian plant, following
2,452 men from the eight U.S. plants (McDonald et al., 2005, Document
ID 1092). These nested case-control studies, Hughes et al. (2001,
Document ID 1060) and McDonald et al. (2005, Document ID 1092), allowed
for individual job, exposure, and smoking histories to be taken into
account in the exposure-response analysis. Hughes et al. (2001,
Document ID 1060) found statistically significant positive exposure-
response trends for lung cancer for both cumulative exposure (lagged 15
years) and average exposure concentration, but not for duration of
employment. With exposure lagged 15 years and after adjusting for
smoking, increasing quartiles of cumulative silica exposure were also
associated with lung cancer mortality (p-value for trend = 0.04).
McDonald et al. (2005, Document ID 1092) found very similar results,
with increasing quartiles of cumulative silica exposure (lagged 15
years) associated with lung cancer mortality (p-value for trend =
0.006). Because McDonald et al. (2005, Document ID 1092) did not report
the medians of the exposure categories, and given the similar results
of both case-control studies, OSHA chose to base its risk estimates on
the Hughes et al. (2001, Document ID 1060) study.
Miller et al. (2007, Document ID 1305) and Miller and MacCalman
(2009, Document ID 1306) continued a follow-up mortality study, begun
in 1970, of coal miners from 10 British coal mines initially followed
through the end of 1992 (Miller et al., 1997, Document ID 1304) and
extended it to 2005. In the analysis using internal controls and Cox
regression methods, the relative risk of lung cancer mortality,
adjusted for concurrent dust exposure and smoking status, at a
cumulative quartz exposure (lagged 15 years) equivalent of
approximately 55 [mu]g/m\3\ for 45 years was 1.14 (95% C.I., 1.04 to
1.25).
ii. Risk Estimates
In the Preliminary QRA, OSHA presented estimates of excess lung
cancer mortality risk from occupational exposure to crystalline silica,
based on data from the five epidemiology studies discussed above
(Document ID 1711). In its preliminary analysis, OSHA used background
all-cause mortality and lung cancer mortality rates from 2006, as
reported by the National Center for Health Statistics (NCHS) (Document
ID 1104). These rates were used in life table analyses to estimate
lifetime risks at the exposure levels of interest, ranging from 25 to
500 [mu]g/m\3\ respirable crystalline silica.
OSHA's preliminary estimates of lifetime excess lung cancer risk
associated with 45 years of exposure to crystalline silica at 100
[mu]g/m\3\ (approximately the previous general industry PEL) ranged
between 13 and 60 deaths per 1,000 workers, depending upon the study
used. For exposure to the revised PEL of 50 [mu]g/m\3\, the lifetime
risk estimates were in the range of between 6 and 26 deaths per 1,000
workers, depending upon the study used. For a 45 year exposure at the
new action level of 25 [mu]g/m\3\, OSHA estimated the risk to range
between 3 and 23 deaths per 1,000 workers. The Agency found that the
results from these preliminary assessments were reasonably consistent
despite the use of data from different cohorts and the reliance on
different analytical techniques for evaluating dose-response
relationships.
OSHA also estimated the lung cancer risk associated with 45 years
of exposure to the previous construction/shipyard PEL (in the range of
250 [mu]g/m\3\ to 500 [mu]g/m\3\) to range between 37 and 653 deaths
per 1,000 workers, depending upon the study used. OSHA acknowledges
that the 653 deaths is the upper limit for 45 years of exposure to 500
[mu]g/m\3\, and recognizes that actual risk, to the extent that workers
are exposed for less than 45 years or intermittently, is likely to be
lower. In addition, exposure to 250 or 500 [mu]g/m\3\ over 45 years
represents cumulative exposures of 11.25 and 22.5 mg/m\3\-yrs,
respectively. This range of cumulative exposure is well above the
median cumulative exposure for most of the cohorts used in the
preliminary risk assessment. Thus, OSHA explained that estimating lung
cancer excess risks over this higher range of cumulative exposures of
interest to OSHA required some degree of upward extrapolation of the
exposure-response function to model these high exposures, thus adding
uncertainty to the estimates.
Since the time of that original analysis, NCHS has released updated
all-cause mortality and lung cancer mortality background rates from
2011. OSHA's final risk estimates, which incorporate these updated
rates, are available in this preamble at Section VI, Final Quantitative
Risk Assessment and Significance of Risk.
c. Uncertainty Analysis of Pooled Studies of Lung Cancer Mortality and
Silicosis Mortality
In the Preliminary QRA, OSHA recognized that risk estimates can be
inherently uncertain and can be affected by confounding, selection
bias, and measurement error (Document ID 1711). OSHA presented several
reasons as to why it does not believe that confounding or selection
bias had a substantial impact on the risk estimates for lung cancer or
silicosis mortality (Document ID 1711, pp. 299-302). However, because
it was more difficult to assess the importance of exposure measurement
error, OSHA's contractor, ToxaChemica, Inc., commissioned Drs. Kyle
Steenland and Scott Bartell to perform an uncertainty analysis to
examine the effect of uncertainty due to measurement error in the
pooled studies (Steenland et al., 2001a, Document ID 0452; Mannetje
2002b, 1089) on the lung cancer and silicosis mortality risk estimates
(ToxaChemica, Inc., 2004, Document ID 0469).
There are two main sources of error in the silica exposure
measurements. The first arises from the assignment of individual
workers' exposures based on either exposure measurements for a sample
of workers in the same job or estimated exposure levels for specific
jobs in the past when no measurements were available, via a job-
exposure matrix (JEM) (Mannetje et al., 2002a, Document ID 1090). The
second arises from the conversion of historically-available dust
measurements, typically particle count concentrations, to gravimetric
respirable silica concentrations. ToxaChemica, Inc. conducted an
uncertainty analysis using the raw data from the IARC multi-centric
study to address these sources of error (2004, Document ID 0469).
i. Lung Cancer Mortality
To examine the effect of error in the assignment of individual
exposure values in the cohorts studied by Steenland et al. (2001a,
Document ID 0452), ToxaChemica, Inc. used a Monte Carlo analysis (a
type of simulation analysis that varies the values of an uncertain
input to an analysis--in this case, exposure estimates--to explore the
effects of different values on the outcome of the analysis) to randomly
sample new values for each worker's job-specific exposure levels from a
distribution that they believed characterized the variability in
exposures of individual workers in each job (see Document ID 1711, pp.
303-305). That is, ToxaChemica created a distribution of values for
each member of each cohort where the mean exposure for each member was
equal to the original exposure value and the distribution of exposure
values was based on a log-normal distribution having a standard
deviation that was based on the exposure variation observed in
industrial sand plants observed by Steenland and Sanderson (2001,
Document ID 0455). From this distribution, new sets of exposure values
from each cohort member were randomly drawn for 50 trials. This
simulation was designed to test whether sets of exposure values that
were plausibly different from the original estimates would lead to
substantially different results of the exposure-response analysis.
Except for the simulated exposure values and the correction of a few
minor errors in the original data sets, the simulation analysis used
the same data as the original analyses conducted by Steenland et al.
(2001a, Document ID 0452).
When an entire set of cumulative exposure values was assembled for
all workers based on these randomly sampled values, the set was used in
a conditional logistic regression to fit a new exposure-response model.
The extent to which altering the exposure values led to changes in the
results indicated how sensitive the previously presented risk estimates
may have been to error in the exposure estimates. Among the individual
cohorts, most of the mean regression coefficients resulting from the
simulation analysis were consistent with the coefficients from the
exposure-response analyses reported in Steenland et al. (2001, Document
ID 0455) and ToxaChemica, Inc. (2004, Document ID 0469) (following
correction for minor data entry and rounding errors). An exception was
the mean of the simulation coefficients based on the South Africa gold
cohort (0.26), which was lower than the previously calculated exposure
coefficient (0.582). ToxaChemica, Inc. (2004, Document ID 0469)
concluded that this error source probably did not appreciably change
the estimated exposure-response coefficient for the pooled data set.
To examine the effect of error in estimating gravimetric respirable
crystalline silica exposures from historical dust concentration data
(i.e., particle count data), ToxaChemica, Inc. (2004, Document ID 0469)
used a procedure similar to that used to assess uncertainties in
individual exposure value assignments. ToxaChemica, Inc. assumed that,
for each job in the dataset, a specific conversion factor existed that
related workers' exposures measured as particle concentrations to
gravimetric respirable silica exposures, and that this conversion
factor came from a normal distribution with a standard deviation
[sigma] = \1/2\ its mean [mu]. The use of a normal distribution was a
reasonable choice in that it allowed the sampled conversion factors to
fall above or below the original values with equal probability, as the
authors had no information to suggest that error in either direction
was more likely. The normal distribution also assigned higher
probability to conversion values closer to the original values. The
choice of the normal distribution therefore reflected the study
authors' judgment that their original conversion factors were more
likely to be approximately correct than not, while allowing for the
possibility of significant error in the original values.
A new conversion factor was then sampled for each job from the
appropriate distribution, and the complete set of sampled conversion
factors was then used to re-run the risk analysis used by Steenland et
al. (2001a, Document ID 0452). The results were similar to the
coefficients originally derived from each cohort; the only coefficient
substantially affected by the procedure was that for the South African
cohort, with an average value of 0.350 across ten runs compared to the
original value of 0.582 (see Table II-5, Document ID 1711, p. 307).
This suggests that the results of exposure-response analyses conducted
using the South African cohort are sensitive to error in exposure
estimates; therefore, there is greater uncertainty due to potential
exposure estimation error in an exposure-response model based on this
cohort than is the case for the other nine cohorts in Steenland et al's
analysis.
To explore the potential effects of both kinds of random
uncertainty described above, ToxaChemica, Inc. (2004, Document ID 0469)
used the distributions representing the error in job-specific exposure
assignment and the error in converting exposure metrics to generate 50
new exposure simulations for each cohort. A study-specific coefficient
and a pooled coefficient were fit for each new simulation, with the
assumption that the two sources of uncertainty were independent. The
results indicated that the only cohort for which the mean of the
exposure coefficients derived from the 50 simulations differed
substantially from the previously calculated exposure coefficient was
the South African gold cohort (simulation mean of 0.181 vs. original
coefficient of 0.582). For the pooled analysis, the mean coefficient
estimate from the simulations was 0.057, just slightly lower than the
previous estimate of 0.060. Based on these results, OSHA concludes
that random error in the underlying exposure estimates in the Steenland
et al. (2001a, Document ID 0452) pooled cohort study of lung cancer
is not likely to have substantially influenced the original risk
estimates derived from the pooled data set, although the model
coefficient for one of the ten cohorts (the South African gold miner
cohort) appeared to be sensitive to measurement errors (see Table II-5,
Document ID 1711, p. 307).
Drs. Steenland and Bartell also examined the effects of systematic
bias in conversion factors, considering the possibility that these may
have been consistently under-estimated or over-estimated for any given
cohort. They addressed possible biases in either direction, conducting
simulations where the true silica content was assumed to be either half
or double the estimated silica content of measured exposures. For the
conditional logistic regression model using log cumulative exposure
with a 15-year lag, doubling or halving the exposure for a specific
study resulted in virtually no change in the exposure-response
coefficient for that study or for the pooled analysis overall. This is
due to the use of log-transformed exposure metrics, which ensured that
any multiplicative bias in exposure would have virtually no effect on
conditional logistic regression coefficients (Document ID 0469, p. 17).
That is, for this model, a systematic error in exposure estimation for
any study had little effect on the lung cancer response rate for either
the specific study or the pooled analysis overall.
ii. Silicosis Mortality
Following the procedures described above for the lung cancer
analysis, Toxachemica, Inc. (2004, Document ID 0469) combined both
sources of random measurement error in a Monte Carlo analysis of the
silicosis mortality data from Mannetje et al. (2002b, Document ID
1089). Categorical analyses were performed with a nested case control
model, in contrast to the Poisson model used previously by Mannetje et
al. (2002b, Document ID 1089). The nested case control model was
expected to control more effectively for age. This model yielded
categorical rate ratio results using the original data (prior to
simulation of measurement error) which were approximately 20-25 percent
lower than those reported by Mannetje et al. (2002b, Document ID 1089).
The silicosis mortality dataset thus appeared to be more sensitive to
possible error in exposure measurement than the lung cancer dataset,
for which the mean of the simulation coefficients was virtually
identical to the original. OSHA notes that its risk estimates derived
from the pooled analysis (Mannetje et al., 2002b, Document ID 1089),
incorporated ToxaChemica, Inc.'s simulated measurement error (2004,
Document ID 0469). More information is provided in the Preliminary QRA
(Document ID 1711, pp. 310-314).
d. Renal Disease Mortality
i. Exposure-Response Studies
Steenland et al. (2002a, Document ID 0448) examined renal disease
mortality in a pooled analysis of three cohorts, as discussed
previously. These cohorts were chosen because data were available for
both underlying cause mortality and multiple cause mortality. The
combined cohort for the pooled analysis (Steenland et al., 2002a,
Document ID 0448) consisted of 13,382 workers with exposure information
available for 12,783 (95 percent). SMRs (compared to the U.S.
population) for renal disease (acute and chronic glomerulonephritis,
nephrotic syndrome, acute and chronic renal failure, renal sclerosis,
and nephritis/nephropathy) were statistically significantly elevated
using multiple cause data (SMR 1.29, 95% CI 1.10-1.47, 193 deaths) and
underlying cause data (SMR 1.41, 95% CI 1.05-1.85, 51 observed deaths).
ii. Risk Estimates
As detailed in the Preliminary QRA, OSHA estimated that exposure to
the previous (100 [mu]g/m\3\) and revised (50 [mu]g/m\3\) general
industry PELs, over a 45-year working life, would result in a lifetime
excess renal disease mortality risk of 39 and 32 deaths per 1,000
workers, respectively. For exposure to the previous construction/
shipyard PELs, OSHA estimated the lifetime excess risk to range from 52
to 63 deaths per 1,000 workers at exposures of 250 and 500 [mu]g/m\3\,
respectively. These risks reflect the 1998 background all-cause
mortality and renal mortality rates for U.S. males. Background rates
were not adjusted for the renal disease risk estimates because the CDC
significantly changed the classification of renal diseases after 1998;
they are now inconsistent with those used by Steenland et al. (2002a,
Document ID 0448) to ascertain the cause of death of workers in their
study.
e. Silicosis Morbidity
i. Exposure-Response Studies
OSHA summarized, in its Preliminary QRA, the principal cross-
sectional and cohort studies that quantitatively characterized
relationships between exposure to crystalline silica and the
development of radiographic evidence of silicosis (Document ID 1711).
Each of these studies relied on estimates of cumulative exposure to
evaluate the relationship between exposure and silicosis prevalence.
The health endpoint of interest in these studies was the appearance of
opacities on chest radiographs indicative of pulmonary fibrosis. Most
of the studies reviewed by OSHA considered a finding consistent with an
ILO classification of 1/1 to be a positive diagnosis of silicosis,
although some also considered an x-ray classification of 1/0 or 0/1 to
be positive. OSHA noted its belief, in the Preliminary QRA, that the
most reliable estimates of silicosis morbidity, as detected by chest
radiographs, come from the studies that evaluated radiographs over
time, included radiographic evaluation of workers after they left
employment, and derived cumulative or lifetime estimates of silicosis
disease risk. OSHA also pointed out that the low sensitivity of chest
radiography in detecting silicosis suggests that risk estimates derived
from radiographic evidence likely underestimate the true risk.
Hnizdo and Sluis-Cremer (1993, Document ID 1052) described the
results of a retrospective cohort study of 2,235 white gold miners in
South Africa. A total of 313 miners had developed silicosis (x-ray with
ILO 1/1 or greater) and had been exposed for an average of 27 years at
the time of diagnosis. The average latency for the cohort was 35 years
(range of 18-50 years) from the start of exposure to diagnosis. The
average respirable dust exposure for the cohort overall was 290 [mu]g/
m\3\ (range 110-470), corresponding to an estimated average respirable
silica concentration of 90 [mu]g/m\3\ (range 33-140). The average
cumulative dust exposure for the overall cohort was 6.6 mg/m\3\-yrs
(range 1.2-18.7). Silicosis risk increased exponentially with
cumulative exposure to respirable dust in models using log-logistic
regression. Using the exposure-response relationship developed by
Hnizdo and Sluis-Cremer (1993, Document ID 1052), and assuming a quartz
content of 30 percent in respirable dust, Rice and Stayner (1995,
Document ID 0418) estimated the risk of silicosis to be 13 percent for
a 45-year exposure to 50 [mu]g/m\3\ respirable crystalline silica.
Steenland and Brown (1995b, Document ID 0451) studied 3,330 South
Dakota gold miners who had worked at least a year underground between
1940 and 1965. Chest x-rays were obtained in cross-sectional surveys in
1960 and 1976 and used along with death certificates to ascertain cases
of silicosis; 128 cases were found via death certificate, 29 were found
by x-ray (defined as ILO 1/1 or greater), and 13 were found by both.
OSHA notes that the inclusion of death certificate diagnoses
complicates interpretation of the risk estimate from this study since,
as noted by Finkelstein (2000, Document ID 1015), it is not known how
well such diagnoses correlate with ILO radiographic interpretations; as
such, the risk estimates derived from this study may not be directly
comparable to others that rely exclusively on radiographic findings to
evaluate silicosis morbidity risk. The mean exposure concentration was
50 [mu]g/m\3\ for the overall cohort, with those hired before 1930
exposed to an average of 150 [mu]g/m\3\. The average duration of
exposure for workers with silicosis was 20 years (s.d. = 8.7) compared
to 8.2 years (s.d. = 7.9) for the rest of the cohort. This study found
that cumulative exposure was the best disease predictor, followed by
duration of exposure and average exposure. Lifetime risks were
estimated from Poisson regression models using standard life table
techniques; the results indicated an estimated risk of 47 percent
associated with 45 years of exposure to 90 [mu]g/m\3\ respirable
crystalline silica, which reduced to 35 percent after adjustment for
age and calendar time.
OSHA used the same life table approach as described for estimating
lung cancer and NMRD mortality risks to estimate lifetime silicosis
risk based on the silicosis rates, adjusted for age and calendar time,
calculated by Steenland and Brown (1995b, Table 2, Document ID 0451).
Silicosis risk was estimated through age 85, assuming exposure from age
20 through 65, and assuming that the silicosis rate remains constant
after age 65. All-cause mortality rates to all males for calendar year
2006 were used to account for background competing risk. From this
analysis, OSHA estimated the risk from exposure to the previous general
industry PEL of 100 [mu]g/m\3\ to be 43 percent; this is somewhat
higher than estimated by Steenland and Brown (1995b) because of the use
by OSHA of more recent mortality data and calculation of risk through
age 85 rather than 75. For exposure to the revised PEL of 50 [mu]g/
m\3\, OSHA estimated the lifetime risk to be 7 percent. Since the time
of the original analysis, NCHS has released updated all-cause mortality
background rates from 2011; OSHA's final risk estimates, which
incorporate these updated rates, are available in Section VI, Final
Quantitative Risk Assessment and Significance of Risk.
Miller et al. (1995, Document ID 1097; 1998, 0374) and Buchanan et
al. (2003, Document ID 0306) reported on a follow-up study conducted in
1990 and 1991 of 547 survivors of a 1,416 member cohort of Scottish
coal workers from a single mine. These men all worked in the mine
during a period between early 1971 and mid-1976, during which they had
experienced "unusually high concentrations of freshly cut quartz in
mixed coalmine dust" (Document ID 0374, p.52). Thus, this cohort
allowed for the study of exposure-rate effects on the development of
silicosis. The men all had radiographs dating from before, during, or
just after this high concentration period, and the 547 participating
survivors received follow-up chest x-rays between November 1990 and
April 1991.
Buchanan et al. (2003, Document ID 0306) presented logistic
regression models in stages. In the first stage they compared the
effect of pre- vs. post-1964 cumulative quartz exposures on odds
ratios; this yielded a statistically significant odds ratio estimate
for post-1964 exposures. In the second stage they added total dust
levels both pre- and post-1964, age, smoking status, and the number of
hours worked pre-1954; only post-1964 cumulative exposures remained
significant. Finally, in the third stage, they started with only the
statistically significant post-1964 cumulative exposures, and separated
these exposures into two quartz bands, one for exposure to
concentrations less than 2,000 [mu]g/m\3\ respirable quartz and the
other for concentrations greater than or equal to 2,000 [mu]g/m\3\.
Both concentration bands were highly statistically significant in the
presence of the other, with the coefficient for exposure concentrations
greater than or equal to 2000 [mu]g/m\3\ being three times that of the
coefficient for concentrations less than 2000 [mu]g/m\3\. From this,
the authors concluded that their analysis showed that "the risks of
silicosis over a working lifetime can rise dramatically with exposure
to such high concentrations over a timescale of merely a few months"
(Buchanan et al. 2003, Document ID 0306, p. 163). The authors then used
the model to estimate the risk of acquiring a chest x-ray classified as
ILO category 2/1+, 15 years after exposure, as a function of both low
(<2000 [mu]g/m\3\) and high (>2000 [mu]g/m\3\) quartz concentrations.
OSHA chose to use this model to estimate the risk of radiological
silicosis consistent with an ILO category 2/1+ chest x-ray for several
exposure scenarios; in each, it assumed 45 years of exposure, 2000
hours/year of exposure, and no exposure above a concentration of 2000
[mu]g/m\3\. The results showed that occupational exposures to the
revised PEL of 50 [mu]g/m\3\ led to an estimated risk of 55 cases per
1,000 workers. Exposure at the previous general industry PEL of 100
[mu]g/m\3\ increased the estimate to 301 cases per 1,000 workers. At
higher exposure levels the risk estimates rose quickly to near
certainty.
Chen et al. (2001, Document ID 0332) reported the results of a
retrospective study of a Chinese cohort of 3,010 underground miners who
had worked in tin mines at least one year between 1960 and 1965. They
were followed through 1994, by which time 2,426 (80.6 percent) workers
had either retired or died, and only 400 (13.3 percent) remained
employed at the mines. Annual radiographs were taken beginning in 1963
and cohort members continued to have chest x-rays taken every 2 or 3
years after leaving work. Silicosis was diagnosed when at least 2 of 3
radiologists classified a radiograph as being a suspected case or at
Stage I, II, or III under the 1986 Chinese pneumoconiosis roentgen
diagnostic criteria, which the authors reported agreed closely with ILO
categories 0/1, Category 1, Category 2, and Category 3, respectively.
Silicosis was observed in 33.7 percent of the group; 67.4 percent of
the cases developed after exposure ended.
Chen et al. (2001, Document ID 0332) found that a Weibull model
provided the best fit to relate cumulative silicosis risk to eight
categories of cumulative total dust exposure. The risk of silicosis was
strongly related to cumulative silica exposure. The investigators
predicted a 55-percent risk of silicosis associated with 45 years of
exposure to 100 [mu]g/m\3\. The paper did not report the risk
associated with a 45-year exposure to 50 [mu]g/m\3\, but OSHA estimated
the risk to be about 17 percent (based on the parameters of the Weibull
model).
In a later study, Chen et al. (2005, Document ID 0985) investigated
silicosis morbidity risks among three cohorts to determine if the risk
varied among workers exposed to silica dust having different
characteristics. The cohorts consisted of 4,547 pottery workers, 4,028
tin miners, and 14,427 tungsten miners, all employed after January 1,
1950 and selected from a total of 20 workplaces. The approximate
mean cumulative exposures to respirable silica for pottery, tin, and
tungsten workers were 6.4 mg/m\3\-yrs, 2.4 mg/m\3\-yrs, and 3.2 mg/
m\3\-yrs, respectively. Measurement of particle surface occlusion
(presence of a mineral coating that may affect the biological
availability of the quartz component) indicated that, on average, 45
percent of the surface area of respirable particles collected from
pottery factory samples was occluded, compared to 18 percent of the
particle surface area for tin mine samples and 13 percent of particle
surface area for tungsten mines. When cumulative silica exposure was
adjusted to reflect exposure to surface-active quartz particles (i.e.,
not occluded), the estimated cumulative risk among pottery workers more
closely approximated those of the tin and tungsten miners, suggesting
to the authors that alumino silicate occlusion of the crystalline
particles in pottery factories at least partially explained the lower
risk seen among pottery workers, despite their having been more heavily
exposed. Based on Chen et al. (2005, Document ID 0985), OSHA estimated
the cumulative silicosis risk associated with 45 years of exposure to
100 [mu]g/m\3\ respirable crystalline silica to be 6 percent for
pottery workers, 12 percent for tungsten miners, and 40 percent for tin
miners. For 45 years of exposure to 50 [mu]g/m\3\, cumulative silicosis
morbidity risks were estimated to be 2 percent for pottery workers, 2
percent for tungsten miners, and 10 percent for tin miners.
ii. Risk Estimates
OSHA's risk estimates for silicosis morbidity ranged between 60 and
773 per 1,000 workers for a 45-year exposure to the previous general
industry PEL of 100 [mu]g/m\3\, and between 20 and 170 per 1,000
workers for a 45-year exposure to the revised PEL of 50 [mu]g/m\3\,
depending upon the study used. OSHA recognizes that actual risk, to the
extent that workers are exposed for less than 45 years or
intermittently, is likely to be lower, but also recognizes that
silicosis can progress for years after exposure ends. Also, given the
consistent finding of a monotonic exposure-response relationship for
silicosis morbidity with cumulative exposure in the studies reviewed,
OSHA continues to find that cumulative exposure is a reasonable
exposure metric upon which to base risk estimates in the exposure range
of interest.
D. Comments and Responses Concerning Silicosis and Non-Malignant
Respiratory Disease Mortality and Morbidity
In this section, OSHA focuses on comments pertaining to the
literature used by the Agency to assess risk for silicosis and non-
malignant respiratory disease (NMRD) mortality and morbidity. As
discussed in the Review of Health Effects Literature and Preliminary
QRA (Document ID 1711) and in Section V.C, Summary of the Review of
Health Effects Literature and Preliminary QRA, of this preamble, OSHA
used two studies (ToxaChemica, 2004, Document ID 0469; Park et al.,
2002, 0405) to determine lifetime risk for silicosis and NMRD mortality
and five studies (Buchanan et al., 2003, Document ID 0306; Chen et al.,
2001, 0332; Chen et al., 2005, 0985; Hnizdo and Sluis-Cremer, 1993,
1052; and Steenland and Brown, 1995b, 0451) to determine cumulative
risk for silicosis morbidity. OSHA discussed the reasons for selecting
these scientific studies for quantitative risk assessment in its Review
of Health Effects Literature and Preliminary QRA (Document ID 1711, pp.
340-342). Briefly, OSHA concluded that the aforementioned studies used
scientifically accepted techniques to measure silica exposures and
health effects in order to determine exposure-response relationships.
The Agency believed, and continues to believe, that these studies, as a
group, provide the best available evidence of the exposure-response
relationships between silica exposure and silicosis morbidity,
silicosis mortality, and NMRD mortality and that they constitute a
solid and reliable foundation for OSHA's final risk assessment.
OSHA received both supportive and critical comments and testimony
regarding these studies. Comments largely focused on how the authors of
these studies analyzed their data, and concerns expressed by commenters
generally focused on exposure levels and measurement, potential biases,
confounding, statistical significance of study results, and model
forms. This section does not include extensive discussion on exposure
measurement error, potential biases, thresholds, confounding factors,
and the use of the cumulative exposure metric, which are discussed in
depth in other sections of this preamble, including V.J Comments and
Responses Concerning Biases in Key Studies and V.K Comments and
Responses Concerning Exposure Estimation Error and ToxaChemica's
Uncertainty Analysis. OSHA addresses comments on general model form and
various other issues here and concludes that these comments do not
meaningfully affect OSHA's reliance on the studies discussed herein or
the results of the Agency's final risk assessment.
1. Silicosis and NMRD Mortality
There are two published studies that report quantitative risk
assessments of silicosis and NMRD mortality (see Document ID 1711, pp.
292-298). The first is an exposure-response analysis of diatomaceous
earth (DE) workers (Park et al., 2002, Document ID 0405). Park et al.
quantified the relationship between cristobalite exposure and mortality
caused by NMRD, which includes silicosis, pneumoconiosis, emphysema,
and chronic bronchitis (Park et al. refers to these conditions as
"lung disease other than cancer (LDOC)," while OSHA uses the term
"NMRD"). Because NMRD captures much of the silicosis
misclassification that results in underestimation of the disease and
includes risks from other lung diseases associated with crystalline
silica exposures, OSHA believes the risk estimates derived from the
Park et al. study reasonably reflect the risk of death from silica-
related respiratory diseases, including silicosis (Document ID 1711,
pp. 297-298). The second study (Mannetje et al. 2002b, Document ID
1089) is a pooled analysis of six epidemiological studies that were
part of an IARC effort. OSHA's contractor ToxaChemica later conducted a
reanalysis and uncertainty analysis using these data (ToxaChemica,
2004, Document ID 0469). OSHA believes that the estimates from the
pooled study represent credible estimates of mortality risk from
silicosis across a range of industrial workplaces, but are likely to
understate the actual risk because silicosis is under-reported as a
cause of death.
a. Park et al. (2002)
The American Chemistry Council (ACC) submitted several comments
pertaining to the Park et al. (2002, Document ID 0405) study, including
comments on the cohort's exposure concentrations. In its post-hearing
brief, the ACC noted that the mean crystalline silica exposure in
Park's DE cohort was estimated to be more than three times the former
general industry PEL of 100 [mu]g/m\3\ and the mean estimated exposure
of the workers with silicosis could have been close to 10 times that
level. According to the ACC, extrapolating risks from the high exposure
levels in this cohort to the much lower levels relevant to OSHA's risk
assessment (the previous general industry PEL of 100 [mu]g/m\3\ and
the revised PEL of 50 [mu]g/m\3\) is "fraught with uncertainty"
(Document ID 4209, pp. 84-85).
OSHA acknowledges that there is some uncertainty in using models
heavily influenced by exposures above the previous PEL due to potential
deviance at areas of the relationship with fewer data points. However,
OSHA believes that the ACC's characterization of exposures in the Park
et al. (2002) study as vastly higher than the final and former PELs is
incorrect. The ACC focused on mean exposure concentrations, reported by
Park et al. as 290 [mu]g/m\3\, to make this argument (Document ID 0405,
p. 37). However, in the Park et al. study, the mean cumulative exposure
of the cohort was 2.16 mg/m\3\-yrs, lower than what the final rule
would permit over 45 years of exposure (2.25 mg/m\3\-yrs) (Document ID
0405, p. 37). Thus, whereas some participants in the Park et al. study
had higher average-8-hour exposures than were typical under the
previous PEL, they were quite comparable to the exposures workers might
accumulate over their working lives under the final PEL of 50 [mu]g/
m\3\. In addition, as discussed in Section V.M, Comments and Responses
Concerning Working Life, Life Tables, and Dose Metric, OSHA believes
that the evidence in the rulemaking record, including comments and
testimony from NIOSH (Document ID 3579, Tr. 127), Kyle Steenland, Ph.D.
(Document ID 3580, Tr. 1227), and OSHA peer reviewer Kenneth Crump,
Ph.D. (Document ID 1716, p. 166), points to cumulative exposure as a
reasonable and appropriate dose metric for deriving exposure-response
relationships. In sum, OSHA does not agree that the Park study should
be discounted based on the ACC's concerns about the estimated exposure
concentrations in the diatomaceous earth cohort.
The ACC also criticized the Park study for its treatment of
possible confounding by smoking and exposure to asbestos. The ACC
commented in its pre-hearing brief that data on smoking was available
for only half of the cohort (Document ID 2307, Attachment A, p. 108).
The Panel also wrote that, "while Park et al. dismissed asbestos as a
potential confounder and omitted asbestos exposure in their final
models, the situation is not as clear-cut as they would have one
believe" (Document ID 2307, Attachment A, p. 109). The Panel
highlighted that Checkoway et al. (1997), the study upon which Park
relied to dismiss asbestos as a potential confounder, noted that
"misclassification of asbestos exposure may have hindered our ability
to control for asbestos as a potential confounder" (Document ID 0326,
p. 685; 2307, Attachment A, p. 109).
OSHA has reviewed the ACC's concerns, and maintains that Park et
al. adequately addressed the issues of possible confounding by smoking
and exposure to asbestos in this data set. Smoking habits of a third of
the individuals who died from NMRD were known in the Park et al. (2002)
study. Based on that partial knowledge of smoking habits, Park et al.
presented analyses indicating that confounding by smoking was unlikely
to significantly impact the observed relationship between cumulative
exposure to crystalline silica and NMRD mortality (Document ID 0405, p.
41). Specifically, Park et al. (2002) performed internally standardized
analyses, which tend to be less susceptible to confounding by smoking
since they compare the mortality experience of groups of workers within
the cohort rather than comparing the mortality experience of the cohort
with an external population (such as by using national mortality
rates); the authors found that the internally standardized models
yielded only slightly lower exposure-response coefficients than
externally adjusted models (Document ID 0405; 1711, p. 302). These
results suggested that estimates of NMRD mortality risks based on this
cohort are not likely to be exaggerated due to cohort members' smoking
habits. Park et al. also stated that the authors' findings regarding
possible confounding by smoking were consistent with those of Checkoway
et al., who also concluded there it was "very unlikely" that smoking
could explain the association between mortality from NMRD and silica
exposure in this cohort (Document ID 0405, p. 41; 0326, p. 687). NIOSH
noted that "[r]esidual confounding from poorly characterized smoking
could have an effect," but that effect could be either positive or
negative (Document ID 4233, pp. 32-33). While OSHA agrees that
comprehensive smoking data would be ideal, the Agency believes that the
approach taken by Park et al. to address this issue was reasonable.
Asbestos exposure was estimated for all workers in Park et al.,
which enabled the researchers to directly test confounding. They
"found no confounding by asbestos" and, accordingly, omitted asbestos
exposure in their final modeling (Document ID 0405, p. 41). As
discussed in the Review of Health Effects Literature and Preliminary
QRA (Document ID 1711, pp. 301-302), exposure to asbestos was
particularly prevalent among workers employed prior to 1930; after
1930, asbestos was presumably no longer used in the process (Gibbs,
1998, Document ID 1024, p. 307; Checkoway et al., 1998, 0984, p. 309).
Checkoway et al. (1998), who evaluated the issue of asbestos
confounding for the same cohort used by Park et al., found that the
risk ratio for the highest silica exposure group after excluding the
workers employed before 1930 from the cohort (Relative Risk (RR) =
1.73) was almost identical to the risk ratio of the high-exposure group
before excluding those same workers (RR = 1.74) (Document ID 0984, p.
309). In addition, Checkoway's reanalysis of the original cohort study
(Checkoway et al., 1993) examined those members of the cohort for whom
there was quantitative information on asbestos exposure, based on a
mixture of historical exposure monitoring data, production records, and
recorded quantities of asbestos included in mixed products of the plant
(Checkoway et al., 1996, Document ID 0325). The authors found an
increasing trend in lung cancer mortality with exposure to crystalline
silica after controlling for asbestos exposure and found only minor
changes in relative risk estimates after adjusting for asbestos
exposure (1996, Document ID 0325). Finally, Checkoway et al. (1998)
reported that the prevalence of pleural abnormalities (indicators of
asbestos exposure) among workers hired before 1930 (4.2 percent) was
similar to that of workers hired after 1930 who presumably had no
asbestos exposure (4.9 percent), suggesting that asbestos exposure was
not a confounder for lung abnormalities in this group of workers
(Document ID 0984, p. 309). Therefore, Checkoway et al. (1998)
concluded that asbestos was not likely to significantly confound the
exposure-response relationship observed between lung cancer mortality
and exposure to crystalline silica in diatomaceous earth workers.
Rice et al. also utilized Checkoway's (1997, Document ID 0326) data
to test for confounding by asbestos in their Poisson and Cox
proportional hazards models. Finding no evidence of confounding, Rice
et al. did not include asbestos exposure as a variable in the final
models presented in their 2001 paper (Document ID 1118, p. 41). Based
on these numerous assessments of the effects of exposure to asbestos in
the diatomaceous earth workers cohort used by Park et al. (2002), OSHA
concludes that concerns about asbestos confounding in this cohort have
been adequately addressed and that the additional analyses performed by
Park et al. on this issue confirmed the findings of prior researchers
that confounding by asbestos exposure was not likely to have a large effect
on exposure-response relationships.
The ACC also expressed concern about model selection. Louis Anthony
Cox, Jr., Ph.D., of Cox Associates, on behalf of the ACC, was concerned
that the linear relative rate model was not appropriate because it is
not designed to test for exposure-response thresholds and, similarly,
the ACC has argued that threshold models are appropriate for
crystalline silica-related diseases (Document ID 2307, Attachment 4,
pp. 91). The ACC claimed that the Park et al. (2002) study is "fully
consistent" with a threshold above the 100 [mu]g/m\3\ concentration
for NMRD, including silicosis, mortality (Document ID 2307, Attachment
A, p. 107).
In its post-hearing comments, NIOSH explained that categorical
analysis for NMRD indicated no threshold existed with cumulative
exposure corresponding to 25 [mu]g/m\3\ over 40 years of exposure,
which is below the cumulative exposure equivalent to the new PEL over
45 years (Document ID 4233, p. 27). Park et al. did not estimate a
threshold below that level because the data lacked the power needed to
discern a threshold (Document ID 4233, p. 27). OSHA agrees with NIOSH's
assessment. In addition, as discussed extensively in Section V.I,
Comments and Responses Concerning Thresholds for Silica-Related
Diseases, OSHA has carefully reviewed the issue of thresholds and has
concluded, based on the best available evidence, that workers with
cumulative and average exposure levels permitted under the previous PEL
of 100 [mu]g/m\3\ are at risk of silica-related disease (that is, there
is unlikely to be an exposure-response threshold at or near 100 [mu]g/
m\3\). For these reasons, OSHA disagrees with Dr. Cox's criticism of
Park et al.'s reliance on the linear relative rate model.
The ACC then questioned the use of unlagged cumulative exposures as
the metric in Park et al. (2002). Dr. Cox noted that "[u]nlagged
models are not very biologically plausible for dust-related NMRD deaths
(if any) caused by exposure concentrations in the range of interest.
Unresolved chronic inflammation and degradation of lung defenses takes
years to decades to manifest" (Document ID 2307, Attachment 4, p. 92).
OSHA considers this criticism overstated. Park et al. considered a
range of lag periods, from two years to 15. They found that
"[u]nlagged models seemed to provide the best fit to the data in
Poisson analyses although lagged models performed almost as well"
(Document ID 0405, p. 37). Based on those findings, as well as
acknowledgments that NMRD effects other than silicosis (e.g., chronic
bronchitis) may be observable without a relatively long lag time
(unlike cancer) and that the majority of deaths observed in the cohort
were indeed NMRD other than silicosis, the researchers decided to use
an unlagged model. Because Park found the differences between the
lagged and unlagged models for this cohort and the NMRD endpoint to be
insignificant, OSHA finds that Park's final choice to use an unlagged
model does not detract from OSHA's decision to utilize lagged models in
its risk assessment.
The ACC was also concerned about the truncation of cumulative
exposures in the Park et al. (2002) paper. Peter Morfeld, Dr. rer.
medic, stated that Park et al.:
suffers from a methodological drawback....The authors truncated
the cumulative RCS dust exposures before doing the final analyses
based on their observation of where the cases were found. The
maximum in the study was 62.5 mg/m\3\-years but exposures were only
used up to 32 mg/m\3\-years because no LDOC deaths occurred at
exposures higher than that level. Such a selection distorts the
estimated exposure-response relationship because it is based on the
outcome of the study and on the exposure variable. Because high
exposures with no effects were deliberately ignored, the exposure-
response effect estimates are biased upward (Document ID 2307,
Attachment 2, p. 27).
OSHA acknowledges this concern about the truncation of data in the
study, and asked Mr. Park about it at the public hearing. Mr. Park
testified that there were good reasons to truncate the part of the
exposed workforce at the high end of cumulative exposure. He noted
several plausible reasons for the drop-off in the number of cases at
high exposures (attenuation), including random variance in
susceptibility to disease among different people and the healthy worker
survivor effect \6\ (Document ID 3579, Tr. 242-243). He also stated
that this attenuation is a common occurrence in studies of workers
(Document ID 3579, Tr. 242). Mr. Park then emphasized that how one
describes the higher end of the exposure-response relationship is
inconsequential for the risk assessment process because the
relationship at the lower end of the spectrum, where the PEL was
determined, is more important for rulemaking (Document ID 3579, Tr.
242-243). He also stated, in a post-hearing comment, that "[f]or the
purpose of low exposure extrapolation, adding a quadratic term [to
better describe the entirety of the exposure-response relationship]
would result in loss of precision with no advantage [gained] over
truncation of high cumulative exposure observation time" (Document ID
4233, p. 26). To summarize, Mr. Park stated that there are good
scientific reasons to expect attenuation of exposure-response at the
high end of the cumulative exposure range and that use of higher-
exposure data affected by healthy worker survivor effect or other
issues could reduce precision of the exposure-response model at the
lower exposures that are more relevant to the final silica standard.
OSHA finds that Mr. Park's approach in his study, along with his
explanations in the rulemaking record, are reasonable and that he has
fully responded to the concerns of the ACC.
---------------------------------------------------------------------------
\6\ Briefly, if individuals cease working due to illness, then
those individuals will not be represented in cohort subgroups having
the highest cumulative exposures. That exclusion may enable
individuals with greater physiological resilience to silica
exposures to be overrepresented in cohorts exposed to greater
amounts of silica. Further discussion on the healthy worker survivor
effect can be found in Section V.F, Comments and Responses on Lung
Cancer Mortality.
---------------------------------------------------------------------------
Dr. Morfeld also noted that alternative techniques that do not
require truncation are available to account for a healthy worker
survivor effect (Document ID 2307, Attachment 2, pp. 27-28). OSHA
believes such techniques, such as g-estimation, to be relatively new or
not yet in standard use in occupational epidemiology. As discussed
above, OSHA finds Mr. Park's approach in his study to be reasonable.
Finally, Dr. Cox stated in his comments that:
key studies relied on by OSHA, such as Park et al. (2002), do not
correct for biases in reported ER [exposure-response] relations due
to residual confounding by age (within age categories), i.e., the
fact that older workers may tend to have both higher lung cancer
risks and higher values of occupational exposure metrics, even if
one does not cause the other. This can induce a non-causal
association between the occupational exposure metrics and the risk
of cancer (Document ID 2307, Attachment 4, p. 29).
Confounding occurs in an epidemiological study when the
contribution of a causal factor cannot be separated from the effect of
another variable (e.g., age) not accounted for in the analysis.
Residual confounding occurs when attempts to control for confounding
are not precise enough (e.g., controlling for age by using groups with
age spans that are too wide), or subjects are misclassified with
respect to confounders (Document ID 3607, p. 1). However, the Park et
al. (2002) study of non-malignant respiratory disease mortality, which
Dr. Cox cited as not considering residual confounding by age, actually
addressed this issue by using 13 five-year age groups
(<25, 25-29, 30-34, etc.) in the models (Document ID 0405, p. 37).
Further discussion on residual confounding bias is found in Section V.J,
Comments and Responses Concerning Biases in Key Studies.
The inclusion of Park et al. (2002) (Document ID 0405) in OSHA's
risk assessment has additional support in the record. OSHA's expert
peer-review panel supported including the Park et al. study in the risk
assessment, with Gary Ginsberg, Ph.D., stating that it "represents a
reasonable estimate of silica-induced total respiratory mortality"
(Document ID 3574, p. 29). In addition, as OSHA noted in its Review of
Health Effects Literature and Preliminary QRA (Document ID 1711, pp.
355-356), the Park et al. study is complemented by the Mannetje et al.
multi-cohort silicosis mortality pooled study, which included several
cohorts that had exposure concentrations in the range of interest for
this rulemaking and also showed clear evidence of significant risk of
silicosis and other NMRD at the previous general industry and
construction PELs (2002b, Document ID 1089).
b. Mannetje et al. (2002b) and ToxaChemica (2004)
The ACC also submitted several comments on the Mannetje et al.
(2002b) study of silicosis mortality; the data from Mannetje et al.
were used in the ToxaChemica (2004) re-analysis. As noted above, the
Mannetje et al. (2002b) study was a pooled analysis of silicosis
mortality data from six epidemiological cohorts. This study showed a
statistically significant association between silicosis mortality and
workers' cumulative exposure, as well as with average exposure and
exposure duration. The ACC's pre-hearing brief stated that the study
"provided no justification for the relative rate model forms [Mannetje
et al.] used to evaluate exposure-response" (Document ID 2307,
Attachment A, p. 113). The concern expressed was that the study may not
have considered all potential exposure-response relationships and was
unable to discern differences between monotonic and non-monotonic
characteristics (Document ID 2307, Attachment A, p. 113-114).
Mannetje et al. (2002b, Document ID 1089) did not discuss whether
models other than relative rate models were tested. However, Mannetje's
data was reexamined by ToxaChemica, Inc. on request from OSHA and the
reexamined data was used by OSHA to help estimate lifetime risk for
silicosis mortality (2004, Document ID 0469; 1711, pp. 310-314). The
ToxaChemica reanalysis of the data included a categorical analysis and
a five-knot restricted spline analysis, in addition to a logistic
model, using the log of cumulative exposure (Document ID 0469, p. 50).
ToxaChemica also corrected some errors found in the original data set
and used a nested case-control approach, which they stated would
control more precisely for age than the Poisson regression approach
used by Mannetje et al. (Document ID 0469, p. 18). As shown in Figure 5
of ToxaChemica's report, the restricted spline model (which has
considerable flexibility to represent non-monotonic features of
exposure-response data) appeared to be monotonic, while the categorical
analysis appeared largely monotonic but for one exposure group
(Document ID 0469, p. 40, 50). When not adjusted for measurement error,
the second highest exposure group deviated from the monotonic
relationship existing between the other groups. However, the deviation
was resolved when two sources of measurement error were accounted for
(Document ID 0469, p. 40). The categorical analysis, restricted spline
model, and logistic model yielded roughly similar exposure-response
curves (Document ID 0469, p. 50). OSHA concludes that the ToxaChemica
reanalysis addresses the concerns raised by the ACC by finding similar
exposure-response relationships regardless of the model as well as
providing greater validation of a monotonic curve.
The ACC next questioned the odds ratios generated in the Mannetje
et al. (2002b) study (Document ID 2307, p. 114; 4209, p. 88). The Panel
noted that "the exposure-response relationship is not even fully
monotonic" and that the silica odds ratios in the pooled analysis have
overlapping confidence intervals, suggesting no statistically
significant difference (Document ID 2307, p. 114). The Panel concluded
that "the data indicate that there is no clear effect of exposure on
odds ratios over the entire range considered by the authors; hence, the
study provides no basis for concluding that reducing exposures will
reduce the odds ratio for silicosis mortality" (Document ID 4209, p.
88). Essentially, the ACC argued that the data do not appear to fit a
monotonic relationship and that the confidence intervals for each
exposure level overlap too much to discern any differences in risk
ratios between those exposures.
OSHA believes that the ACC overstated its contention about
confidence interval overlap between groups in the Mannetje et al.
(2002b) paper. Although the original data set reported in the study
lacks a monotonic relationship on the upper end of the exposure
spectrum (>9.58 mg/m\3\-yrs) (possibly due to a healthy worker survivor
effect, as explained above), OSHA notes that the 95 percent confidence
intervals reported do not contradict the presence of a monotonic
relationship (Document ID 1089). First, the confidence intervals of the
lower exposed groups did not overlap with those of the higher exposed
groups in that study (Document ID 1089). Second, even if they did,
overlap in confidence intervals does not mean that there is not a
significant difference between those groups. While it is true that, if
95 percent confidence intervals do not overlap, the represented
populations are statistically significantly different, the converse--
that, if confidence intervals do overlap, there is no statistically
significant difference--is not always true (Nathaniel Schenker and Jane
F. Gentleman. "On Judging the Significance of Differences by Examining
the Overlap Between Confidence Intervals." The American Statistician.
55(3): 2001. 182-186. (http://www.tandfonline.com/doi/abs/10.1198/000313001317097960).
Finally, as discussed above and in detail in Section V.K, Comments
and Responses Concerning Exposure Estimation Error and ToxaChemica's
Uncertainty Analysis, the ToxaChemica et al. (2004) re-analysis of the
corrected Mannetje et al. (2002b) data adjusting for two sources of
measurement error resulted in a monotonic relationship for the risk
ratios (Document ID 0469).
2. Silicosis Morbidity
OSHA relied on five studies for determining risk for silicosis
morbidity: Buchanan et al., 2003 (Document ID 0306), Chen et al., 2001
(Document ID 0332), Chen et al., 2005 (Document ID 0985), Hnizdo and
Sluis-Cremer, 1993 (Document ID 1052), and Steenland and Brown, 1995b
(Document ID 0451). OSHA finds that the most reliable estimates of
silicosis morbidity, as detected by chest radiographs, come from these
five studies because they evaluated radiographs over time, included
post-employment radiographic evaluations, and derived cumulative or
lifetime estimates of silicosis disease risk. OSHA received several
comments about these studies.
a. Buchanan et al. (2003)
Buchanan et al. (2003) reported on a cohort of Scottish coal
workers (Document ID 0306). The authors found a statistically
significant relationship between silicosis and cumulative
exposure acquired after 1964 (Document ID 0306). They also
found that the risks of silicosis over a working lifetime can
rise dramatically with exposure to high concentrations over
a timescale of merely a few months (Document ID 0306). In the
Preliminary QRA, OSHA considered this study to be of the highest
overall quality of the studies relied upon to assess silicosis
morbidity risks, in large measure because the underlying exposure data
was based on modern exposure measurement methods and avoided the need
to estimate historical exposures. The risk estimates derived from this
study were lower than those derived from any of the other studies
criticized by the ACC. One reason for this is because Buchanan et al.
only included cases with chest x-ray findings having an ILO score of 2/
1 or higher, whereas the other studies included cases with less damage,
having a lower degree of perfusion on x-ray (ILO 1/0 or 1/1) (Document
ID 0306). Thus, OSHA considered the risk estimates derived from the
Buchanan et al. study to be more likely to understate risks.
Dr. Cox commented that age needed to be included for modeling in
Dr. Miller's 1998 paper, the data from which were used in the Buchanan
et al. (2003) paper (Document ID 2307, Attachment 4, p. 97). However,
the Miller et al. (1998) study explicitly states that age was one of
several variables that were tried in the model but did not improve the
model's fit, as was time spent working in the poorly characterized
conditions before 1954 (Document ID 0374, p. 57). OSHA concludes that
the original paper did assess these variables and how they related to
the exposure-response relationship. Buchanan et al. (2003) also noted
their own finding that differences in age and exposure both failed to
improve fit, in agreement with Miller et al.'s conclusion (Document ID
0306, p. 161). OSHA therefore finds no credible reason that age should
have been included as a variable in Miller et al. (1998).
Dr. Cox also questioned the modeling methods in the Buchanan paper,
which presented logistic regression in progressive stages to search for
significance (Document ID 2307, Attachment 4, pp. 97-98; 0306, pp. 161-
163). Dr. Cox claimed that this is an example of uncorrected multiple
testing bias where the post hoc selection of data, variables, and
models can make independent variables appear to be statistically
significant in the prediction model. He suggested that corrections for
bias are needed to determine if the reported significance is causal or
statistical (Document ID 2307, Attachment 4, pp. 97-98). OSHA peer
reviewer Brian Miller, Ph.D., stated that Dr. Cox's claim that the
model was affected by multiple testing bias is unfounded (Document ID
3574, pp. 31-32). He noted that the model was based on a detailed
knowledge of the history of exposures at that colliery, and represented
the researchers' attempt to build "a reality-driven and `best-fitting'
model," (Document ID 3574, p. 31, quoting 2307, Attachment 4, p. 4).
Furthermore, none of OSHA's peer reviewers raised any concerns about
the approach taken by Buchanan et al. to develop their exposure-
response model and none suggested that corrections needed to be made
for multiple testing bias; all of them supported the study's inclusion
in OSHA's risk assessment (Document ID 3574). Finally, the cumulative
risk for silicosis morbidity derived from this study is similar to
values from other papers reported in the QRA (see OSHA's Final
Quantitative Risk Assessment in Section VI). Therefore, for the reasons
discussed above, OSHA is not convinced by Dr. Cox's arguments and finds
no credible reason to remove Buchanan et al. (2003) from consideration.
b. Chen et al. (2001, 2005), Steenland and Brown (1995), and Hnizdo and
Sluis-Cremer (1993)
The ACC also commented on several other studies used by OSHA to
estimate silicosis morbidity risks; these were the studies by Chen et
al. (2001, Document ID 0332; 2005, 0985), Steenland and Brown (1995b,
Document ID 0451), and Hnizdo and Sluis-Cremer (1993, Document ID
1052). The ACC's comments focus on uncertainties in estimating the
historical exposures of cohort members (Document ID 2307, Attachment A,
pp. 117-122, 124-130, 132-136). Section V.K, Comments and Responses
Concerning Exposure Estimation Error and ToxaChemica's Uncertainty
Analysis, discusses the record in detail with respect to the general
issue of uncertainties in estimating historical exposures to respirable
crystalline silica in epidemiological studies. The issues specific to
the studies relied upon by OSHA in its risk estimates for silicosis
morbidity will be discussed below.
In the Chen et al. studies, which focused on mining (i.e., tin,
tungsten) and pottery cohorts, high volume area samplers collected dust
and the respirable crystalline silica concentration was determined from
those samples (2001, Document ID 0332; 2005, 0985). However, according
to the ACC, the rest of the collected dust was not assessed for
chemicals that potentially could also cause radiographic opacities
(Document ID 2307, Attachment A, pp. 132-135). Neither study expressed
reason to be concerned about the non-silica portion of the dust
samples. OSHA recognizes that uncertainty about potential unknown
exposures exists in retrospective studies, which describes most
epidemiological research. However, OSHA emphasizes that the risk values
derived from the Chen et al. studies do not differ remarkably from
other silicosis morbidity studies used in the risk assessment (Document
ID 0306, 1052, 0451). Therefore, OSHA concludes that it is unlikely
that an unknown compound significantly impacted the exposure-response
relationships reported in both Chen studies.
The study on gold miners (Steenland and Brown, 1995b, Document ID
0451), which found that cumulative exposure was the best disease
predictor, followed by duration of exposure and average exposure, was
also criticized by the ACC, which alleged that the exposure assessment
suffered from "enormous uncertainty" (Document ID 2307, Attachment A,
pp. 146-147). The ACC noted that exposure measurements were not
available for the years prior to 1937 or after 1975 and that this
limitation of the exposure information may have resulted in an
underestimation of exposures (Document ID 2307, Attachment A, pp. 124-
126). OSHA agrees that these are potential sources of uncertainty in
the exposure estimates, but recognizes exposure uncertainty to be a
common occurrence in occupational epidemiology studies. OSHA believes
that the authors used the best measurement data available to them in
their study.
The ACC also took issue with Steenland and Brown's conversion
factor for converting particle count to respirable silica mass (10
mppcf = 100 [mu]g/m\3\), which was somewhat higher than that used in
the Vermont granite worker studies (10 mppcf = 75 [mu]g/m\3\) (Document
ID 2307, Attachment A, p. 126). OSHA notes that the study's reasoning
for adopting that specific particle count conversion factor was to
address the higher percentage of silica found in the gold mine samples
applicable to their cohort in comparison to the Vermont granite study
(Document ID 0451, p. 1373). OSHA finds this decision, which was based
on the specific known exposure conditions of this cohort, to be
reasonable.
With respect to the Hnizdo and Sluis-Cremer (1993, Document ID
1052) study, which found that silicosis risk increased exponentially with
cumulative exposure to respirable dust (Document ID 1052, p. 447), the
ACC questioned three assumptions the study made about exposures. First,
exposures were assumed to be static from the 1930s to the 1960s, based
on measurements from the late 1950s to mid-1960s, an assumption that,
according to the ACC, might underestimate exposure for workers employed
before the late 1950s (Document ID 2307, Attachment A, pp. 117-119).
Second, although respirable dust, by definition, includes particles up
to 10 [mu]m, the study only considered particles sized between 0.5 and
5 [mu]m in diameter (Document ID 1052, p. 449). The ACC contends this
exclusion may have resulted in underestimated exposure and
overestimated risk (Document ID 2307, Attachment A, p. 119). OSHA
agrees that uncertainty in exposure estimates is an important issue in
the silica risk assessment, and generally discusses the issue of
exposure measurement uncertainty in depth in a quantitative uncertainty
analysis described in Section V.K, Comments and Responses Concerning
Exposure Estimation Error and ToxaChemica's Uncertainty Analysis. As
discussed there, after accounting for the likely effects of exposure
measurement uncertainty in the risk assessment, OSHA affirms the
conclusion of the risk assessment that there is significant risk of
silicosis to workers exposed at the previous PELs.
Thirdly, the ACC challenged the authors' estimate of the quartz
content of the dust as 30 percent when it should have been 54 percent
(Document ID 1052, p. 450; 2307, Attachment A, p. 120). According to
the ACC, the 30 percent estimate was based on an incorrect assumption
that the samples had been acid-washed (resulting in a reduction in
silica content) before the quartz content was measured (Document ID
2307, Attachment A, pp. 120-122). This assumption would greatly
underestimate the exposures of the cohort and the exposures needed to
cause adverse effects, thus overestimating actual risk (Document ID
2307, Attachment A, pp. 121-122). The ACC recommended that the quartz
content in the Hnizdo and Sluis-Cremer study be increased from 30 to 54
percent, based on the Gibbs and Du Toit study (2002, Document ID 1025,
p. 602).
OSHA considered this issue in the Preliminary QRA (Document ID
1711, p. 332). OSHA noted that the California Environmental Protection
Agency's Office of Environmental Health Hazard Assessment reviewed the
source data for Hnizdo and Sluis-Cremer, located in the Page-Shipp and
Harris (1972, Document ID 0583) study, and compared them to the quartz
exposures calculated by Hnizdo and Sluis-Cremer (OEHHA, 2005, Document
ID 1322, p. 29). OEHHA concluded after analyzing the data that the
samples likely were not acid-washed and that the Hnizdo and Sluis-
Cremer paper erred in describing that aspect of the samples.
Additionally, OEHHA reported data that suggests that the 30 percent
quartz concentration may actually overestimate the exposure. It noted
that recent investigations found the quartz content of respirable dust
in South African gold mines to be less than 30 percent (Document ID
1322). In summary, OSHA concludes that no meaningful evidence was
submitted to the rulemaking record that changes OSHA's original
decision to include the Hnizdo and Sluis-Cremer study in its risk
assessment.
Despite the uncertainties inherent in estimating the exposures of
occupational cohorts in silicosis morbidity studies, the resulting
estimates of risk for the previous general industry PEL of 100 [mu]g/
m\3\ are in reasonable agreement and indicate that lifetime risks of
silicosis morbidity at this level, and, by extension, risks at the
higher previous PELs for maritime and construction (see section VI,
Final Quantitative Risk Assessment and Significance of Risk) are in the
range of hundreds of cases per 1,000 workers. Even in the unlikely
event that exposure estimates underlying all of these studies were
systematically understated by several fold, the magnitude of resulting
risks would likely still be such that OSHA would determine them to be
significant.
3. Conclusion
After carefully considering all of the comments on the studies
relied on by OSHA to estimate silicosis and NMRD mortality and
silicosis morbidity risks, OSHA concludes that the scientific evidence
used in its quantitative risk assessment substantially supports the
Agency's finding of significant risk for silicosis and non-malignant
respiratory disease. In its risk estimates in the Preliminary QRA, OSHA
acknowledged the uncertainties raised by the ACC and other commenters,
but the Agency nevertheless concluded that the assessment was
sufficient for evaluating the significance of the risk. After
evaluating the evidence in the record on this topic, OSHA continues to
conclude that its risk assessment (see Final Quantitative Risk
Assessment in Section VI.C of this preamble) provides a reasonable and
well-supported estimate of the risk faced by workers who are exposed to
respirable crystalline silica.
E. Comments and Responses Concerning Surveillance Data on Silicosis
Morbidity and Mortality
As discussed above in this preamble, OSHA has relied on
epidemiological studies to assess the risk of silicosis, a debilitating
and potentially fatal occupationally-related lung disease caused by
exposure to respirable crystalline silica. In the proposed rule (78 FR
56273, 56298; also Document ID 1711, pp. 31-49), OSHA also discussed
data from silicosis surveillance programs that provide some information
about the number of silicosis-associated deaths or the extent of
silicosis morbidity in the U.S. (78 FR at 56298). However, as OSHA
explained, the surveillance data are not sufficient for estimating the
risks of health effects associated with exposure to silica, nor are
they sufficient for estimating the benefits of any potential regulatory
action. This is because silicosis-related surveillance data are only
available from a few states and do not provide exposure data that can
be matched to surveillance data. Consequently, there is no way of
knowing how much silica a person was exposed to before developing fatal
silicosis (78 FR at 56298).
In addition, the available data likely understate the resulting
death and disease rates in U.S. workers exposed to crystalline silica
(78 FR 56298). This understatement is due in large part to: (1) The
passive nature of these surveillance systems, which rely on healthcare
providers' awareness of a reporting requirement and submission of the
appropriate information on standardized forms to health departments;
(2) the long latency period of silicosis; (3) incomplete occupational
exposure histories, and (4) other factors that result in a lack of
recognition of silicosis by healthcare providers, including the low
sensitivity, or ability of chest x-rays to identify cases of silicosis
(78 FR 56298). Specific to death certificate data, information on usual
industry and occupation are available from only 26 states for the
period 1985 to 1999, and those codes are not verifiable (Document ID
1711). Added to these limitations is the "lagging" nature of
surveillance data; it often takes years for cases to be reported,
confirmed, and recorded. Furthermore, in many cases, the available
surveillance systems lack information about actual exposures or even
information about the usual occupation or industry of the deceased
individual, which could provide some information about occupational
exposure (see 78 FR at 56298). Therefore, the Agency did not use these
surveillance data to estimate the risk of silicosis for the purpose of
meeting its legal requirements to prove a significant risk of material
impairment of health (see 29 U.S.C. 655(b)(5); Benzene, 448 U.S. 607,
642 (1980)).
Comments and testimony focusing on the silicosis surveillance data
alleged that OSHA should have used the surveillance data in its risk
estimates. Stakeholders argued that the declining numbers of reported
silicosis deaths prove the lack of necessity for a new silica standard.
Commenters also claimed that the surveillance data prove that OSHA
overestimated both the risks at the former permissible exposure limits
(PELs) and the benefits of the new rule.
After reviewing the rulemaking record, OSHA maintains its view that
these silicosis surveillance data, although useful for providing
context and an illustration of a significant general trend in the
reduction of deaths associated with silicosis over the past 4-5
decades, are not sufficient for estimating the magnitude of the risk or
the expected benefits. In the case of silicosis, surveillance data are
useful for describing general trends nationally and a few states have
the ability to use the data at the local or state level to identify
"sentinel events" that would justify initiating an inspection of a
workplace, for example. The overall data, however, are inadequate and
inappropriate for estimating risks or benefits associated with various
exposure levels, as is required of OSHA's regulatory process, in part
because they significantly understate the extent of silicosis in
workers in the United States and because they lack information about
exposure levels, exposure sources (e.g., type of job), controls, and
health effects that is necessary to examine the effects of lowering the
PEL. Thus, for these reasons and the ones discussed below, OSHA has
continued to rely on epidemiological data to meet its burden of
demonstrating that workers exposed to respirable crystalline silica at
the previous PELs face a significant risk of developing silicosis and
that risk will be reduced when the new limit is fully implemented.
Another related concern identified by stakeholders is the apparent
inconsistency between surveillance data and risk and benefits estimates
derived from modeling epidemiological data (Document ID 4194, pp. 7-10;
4209, pp. 3-4). However, this difference is not an inconsistency, but
the result of comparing two distinctly different items. Surveillance
data, primarily death certificate data, are known to be under-reported
and lack associated exposure data necessary to model relationships
between various exposure levels and observance of health effects. For
these reasons, OSHA relied on epidemiologic studies with detailed
exposure-response relationships to evaluate the significance of risk at
the preceding and new PELs. Thus, the silicosis mortality data derived
from death certificates and estimates of silica-related mortality risks
derived from well-conducted epidemiologic studies cannot be directly
compared in any meaningful way. With respect to silicosis morbidity,
OSHA notes that the estimates by Rosenman et al. (2003, Document ID
0420) of the number of cases of silicosis estimated to occur in the
U.S. (between 2,700 and 5,475 estimated to be in OSHA's jurisdiction
(i.e., excluding miners)) each year is in reasonable agreement with the
estimates derived from epidemiologic studies, assuming either a 13-year
or 45-year working life (see Chapter VII, Table VII-2 of the FEA).
1. Surveillance Data on Silicosis Mortality
The principal source of data on annual silicosis mortality in the
U.S. is the National Institute for Occupational Safety and Health
(NIOSH) Work-Related Lung Disease (WoRLD) Surveillance System (e.g.,
NIOSH, 2008c, Document ID 1308), which compiles cause-of-death data
from death certificates reported to state vital statistics offices and
collected by the National Center for Health Statistics (NCHS). Paper
copies were published in 2003 and 2008 (Document ID 1307; 1308) and
data are updated periodically in the electronic version on the CDC Web
site (http://www.cdc.gov/eworld). NIOSH also developed and manages the
National Occupational Respiratory Mortality System (NORMS), a data-
storage and interactive data retrieval system that reflects death
certificate data compiled by NCHS (http://webappa.cdc.gov/ords/norms.html).
From 1968 to 2002, silicosis was recorded as an underlying or
contributing cause of death on 16,305 death certificates; of these, a
total of 15,944 (98 percent) deaths occurred in males (CDC, 2005,
Document ID 0319). Over time, silicosis-related mortality has declined
in the U.S., but has not been eliminated. Based on the death
certificate data, the number of recognized and coded deaths for which
silicosis was an underlying or contributing cause decreased from 1,157
in 1968 to 161 in 2005, corresponding to an 86-percent decline
(Document ID 1711, p. 33; 1308, p. 55) (http://wwwn.cdc.gov/eworld).
The crude mortality rate, expressed as the number of silicosis deaths
per 1,000,000 general population (age 15 and higher) fell from about
8.9 per million to about 0.5 per million over that same time frame, a
decline of 94 percent (Document ID 1711, p. 33; 1308, p. 55) (http://wwwn.cdc.gov/eworld).
OSHA's Review of Health Effects Literature and Preliminary QRA
included death certificate statistics for silicosis up to and including
2005 (Document ID 1711, p. 33). OSHA has since reviewed the more recent
NORMS and NCHS data, up to and including 2013, which appear to show a
general downward trend in mortality, as presented in Table V-1.
However, more detailed examination of the most recent data
collected through NCHS (Table V-2) indicates that the decline in the
number of deaths with silicosis as an underlying or contributing cause
has leveled off in more recent years, suggesting that the number of
silicosis deaths being recorded and captured by death certificates may
be stabilizing after 30 or more years of decline.
Robert Cohen, M.D., representing the American Thoracic Society,
noted this apparent plateau effect, testifying that "[t]he data from
the NIOSH work-related lung disease surveillance report and others show
a plateau in silicosis mortality since the 1990s, and we are concerned
that that has been the same without any further reduction for more than
20 years. So we think that we still have work to do" (Document ID 3577, p. 775).
Some commenters raised the question about whether decedents who
died more recently were exposed to high levels of silica (pre-1970s)
and therefore wouldn't necessarily reflect mortalities relevant to the
current OSHA standard (Document ID 4194, p. 9; 4209, pp. 7-8). OSHA has
no information on the age of these decedents, or the timing of their
exposure to silica. If we assume that workers born in 1940-1950 would
have started working around 1960, at the earliest, and into the 1970's,
and life expectancy in general of 70 years, or 60-70 years to account
for years of life lost due to silicosis, most of these workers' working
life would have been spent after the 1971 PEL went into effect. It is
likely that some of the more recent decedents were exposed to silica
prior to 1971; however, it is less likely that all were exposed prior
to 1971. At the end of the day, there is no actual exposure information
on these decedents, and this generalization does not account for
overexposures, which have persisted over time.
2. Surveillance Data on Silicosis Morbidity
There is no nation-wide system for collecting silicosis morbidity
case data. The data available are from three sources: (1) The National
Hospital Discharge Survey (Document ID 1711, p. 40-43); (2) the Agency
for Healthcare Research and Quality's (AHRQ) Nationwide Inpatient
Survey (Document ID 3425, p. 2; https://www.hcup-us.ahrq.gov/nisoverview.jsp); and (3) states that administer silicosis and/or
pneumoconiosis disease surveillance (see Document ID 1711, p. 40-43;
http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance/stateprograms.html).
Both of the first two sources of data on silicosis morbidity cases
are surveys that provide estimates of hospital discharges. The first is
the National Hospital Discharge Survey (NHDS), which was conducted
annually from 1965-2010. The NHDS was a national probability survey
designed to meet the need for information on characteristics of
inpatients discharged from non-Federal short-stay hospitals in the
United States (see http://www.cdc.gov/nchs/nhds.htm). Estimates of
silicosis listed as a diagnosis on hospital discharge records are
available from the NHDS for the years 1985 to 2010 (see http://www.cdc.gov/nchs/nhds.htm). National estimates were rounded to the
nearest 1,000, and the NHDS has consistently reported approximately
1,000 discharges/hospitalizations annually since 1980 (e.g., Document
ID 1307; 1308). The second survey, the National (Nationwide) Inpatient
Sample (NIS), is conducted annually by the AHRQ. Dr. Kenneth Rosenman,
Division Chief and Professor of Medicine at Michigan State University
and who oversees one of the few occupational disease surveillance
systems in the U.S., testified that data from the NIS indicated that
the nationwide number of hospitalizations where silicosis was one of
the discharge diagnoses has remained constant, with 2,028
hospitalizations reported in 1993 and 2,082 in 2011 (Document ID 3425,
p. 2).
Morbidity data are also available from the states that administer
silicosis and/or pneumoconiosis disease surveillance. These programs
rely primarily on hospital discharge records and also may get some
reports of cases from the medical community and workers' compensation
programs. Currently, NIOSH funds the State-Based Occupational Safety
and Health Surveillance cooperative agreements (Document ID 1711, p.
40-41; http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance.html). All states funded under a cooperative
agreement conduct population-based surveillance for pneumoconiosis
(hospitalizations and mortality), and a few states (currently Michigan
and New Jersey) have expanded surveillance specifically for silicosis
(Document ID 1711, p. 40-42; http://www.cdc.gov/niosh/topics/surveillance/ords/StateBasedSurveillance/stateprograms.html).
State-based hospital discharge data are a useful population-based
surveillance data source for quantifying pneumoconiosis (including
silicosis), even though only a small number of individuals with
pneumoconiosis are hospitalized for that condition (Document ID 0996),
and the data refer to hospitalizations with a diagnosis of silicosis,
and not specific people. In addition to mortality data, NIOSH has
updated its WoRLD Surveillance System with some state-based morbidity
case data (http://wwwn.cdc.gov/eworld/Grouping/Silicosis/94). State-
based surveillance systems can provide more detailed information on a
few cases of silicosis.
NIOSH has published aggregated state case data in its WoRLD Reports
(Document ID 1308; 1307) for two ten-year periods that overlap, 1989 to
1998 and 1993 to 2002. State morbidity case data are compiled and
evaluated by variables such as ascertainment source, primary industry,
and occupations. For the time period 1989 to 1998, Michigan reported
589 cases of silicosis, New Jersey 191 cases, and Ohio 400 cases
(Document ID 1307, p. 69). In its last published report, for the later
and partially overlapping time period 1993 to 2002, Michigan reported
465 cases, New Jersey 135, and Ohio 279 (Document ID 1308, p. 72). Data
for the years 2003 to 2011, from the CDC/NIOSH electronic report,
eWoRld, show a modest decline in the number of cases of silicosis in
these three states; however, decreases are not nearly as substantial as
are those seen in the mortality rates (see Table V-3). Annual averages
for the two ten-year periods and the nine-year time period were
calculated by OSHA solely for the purpose of comparing cases of
silicosis reported over time.
3. Critical Comments Received on Surveillance Data
Industry representatives, including ACC's Crystalline Silica Panel
and Dr. Jonathan Borak, representing the Chamber of Commerce (Chamber),
contended that the steep decline seen in the number and rate of
silicosis deaths since 1968 proves that OSHA cannot meet its burden of
demonstrating that a more protective standard is necessary (e.g.,
Document ID 4209, p. 10; 2376, p. 8; 4016, p. 9). Similarly, other
commenters, such as the American Petroleum Institute, the Independent
Petroleum Association of America, the National Mining Association, the
American Foundry Society (AFS), the National Utility & Excavating
Contractors Association, Acme Brick, the National Ready Mixed Concrete
Association, and the Small Business Administration's Office of Advocacy
stated that surveillance data demonstrate that the previous OSHA PEL
was sufficiently effective in reducing the number of deaths from
silicosis (Document ID 3589, Tr. 4041; 4122; 2301, pp. 3, 7-9; 2211, p.
2; 2379, pp. 23-25; 2171, p. 1; 3730, p. 5; 3586, Tr. 3358-3360; 3589,
Tr. 4311; 2349, pp. 3-4). Industry commenters also argued that the
number of recorded silicosis-related deaths in recent years, as
reflected in the surveillance data, is far lower than the number of
lives that OSHA projected would be saved by a more stringent rule,
indicating that OSHA's risk assessment is flawed (e.g., Document ID
3578, Tr. 1074-1075; 4209, p. 3-4).
The Chamber, along with others, declared that OSHA ignored steep
declines in silicosis mortality, which in its view indicates that there
is no further need to reduce the PEL (Document ID 4194, pp. 7-8). OSHA
has not ignored the fact that the available surveillance data indicate
a decline in silicosis mortality. As discussed above and in the
proposal, the Agency has acknowledged that the available surveillance
data do show a decline in the silicosis mortality since 1968.
Furthermore, OSHA has no information on whether underreporting has
increased or decreased over time, and does not believe that differing
rates of reporting and underreporting of silicosis on death
certificates explains the observed decline in silicosis mortality. OSHA
believes that the reductions in deaths attributable to silicosis are
real, and not a statistical artifact. However, OSHA disagrees with
commenters' argument that this trend shows the lack of a need for this
new rule. First, as explained above, there is strong evidence that the
death certificate data do not capture the entirety of silicosis
mortality that actually exists, due to underreporting of silicosis as a
cause of death. Second, the stakeholders' argument assumes that
mortality will continue to decline, even in the absence of a stronger
silica standard, and that OSHA and workers should wait for this decline
to hit bottom (e.g., Document ID 4209, p. 7). However, testimony in the
record suggests that the decline in the number of deaths has leveled
off since 2000, probably because of the deaths of those historically
exposed to higher levels of silica occurred before then (e.g., Document
ID 3577, p. 775).
Third, the decline in silicosis deaths recorded over the past
several decades cannot be solely explained by improved working
conditions, but also reflects the decline in employment in industries
that historically were associated with high workplace exposures to
crystalline silica. One of OSHA's peer reviewers for the Review of
Health Effects Literature and Preliminary QRA, Bruce Allen, commented
that the observed decline in mortality "...in no way adjusts for
the declining employment in jobs with silica exposure," making "its
interpretation problematic. To emphasize the contribution of historic
declines in exposure as the underlying cause is spurious; no
information is given to allow one to account for declining employment"
(Document ID 3574, p. 7). The CDC/NIOSH also identified declining
employment in heavy industries where silica exposure was prevalent as a
"major factor" in the reduction over time in silicosis mortality
(Document ID 0319, p. 2). As discussed below, however, some silica-
generating operations or industries are new or becoming more prevalent.
In his written testimony, Dr. Rosenman pointed out that there are
"two aspects to the frequency of occurrence of disease (1)...the
risk of disease based on the level of exposure and (2) the number of
individuals at risk" (Document ID 3425, pp. 3-4). Dr. Rosenman
estimated the decline in the number of workers in Michigan foundries
(75 percent) and the number of abrasive blasting companies in Michigan
(71 percent), and then compared these percentages to the percentage
decline in the number of recorded silicosis deaths (80 percent) over a
similar time period. The similarities in these values led him to
attribute "almost all" of the decrease in silicosis deaths to a
decrease in the population at risk (Document ID 3425, pp. 3-4).
Finally, OSHA's reliance on epidemiological data for its risk
assessment purposes does not suggest that the Agency ignored the
available surveillance data. As discussed above, the data are
inadequate and inappropriate for estimating risks or benefits
associated with various exposure levels, as is required of OSHA's
regulatory process. Even in the limited cases where surveillance data
are available, OSHA generally relies on epidemiological data, to the
extent they include sufficiently detailed information on exposures,
exposure sources (e.g., type of job), and health effects, to satisfy
its statutory requirement to use the best available evidence to
evaluate the significance of risk associated with exposure to hazardous
substances.
Some stakeholders provided comments to the rulemaking record
consistent with OSHA's assessment. For example, Dr. Borak stated that
the surveillance data "provide little or no basis" (Document ID 2376,
p. 8) for OSHA to evaluate the protectiveness of the previous PELs.
Similarly, NIOSH asserted that relying on the surveillance data to show
that there is no need for a lower PEL or that there is no significant
risk at 100 [mu]g/m\3\ would be "a misuse of surveillance data"
(Document ID 3579, Tr. 167). NIOSH also added that, because the
surveillance data do not include information about exposures, it is not
the kind of data that could be used for a quantitative risk assessment.
NIOSH concluded that surveillance data are, in fact, "really not
germane to the risk assessment" (Document ID 3579, Tr. 248). OSHA
agrees with both Dr. Borak and NIOSH that the surveillance data cannot
and do not inform the Agency on the need for a lower PEL, nor is there
a role for surveillance data in making its significant risk findings.
Therefore, for its findings of significant risk at the current PEL, the
Agency relied on evidence derived from detailed exposure-response
relationships from well-conducted epidemiologic studies, and not
surveillance data, which have no associated exposure information. In
this case, epidemiologic data provided the best available evidence.
In its testimony, the AFL-CIO pointed out that a recent U.S.
Government Accountability Office (GAO) report on the Mine Safety and
Health Administration's (MSHA) proposed coal dust standard references
the National Academy of Sciences (NAS) conclusion that risk assessments
based on epidemiological data, not surveillance data, were an
appropriate means to assess risk for coal-dust exposures (Document ID
4204, p. 21; 4072, Attachment 48, pp. 7-8). The NAS emphasized that the
surveillance data available to MSHA did not include individual miners'
levels of exposure to coal mine dust and, therefore, could not be used
for the purpose of estimating disease risk for miners.
"Based on principles of epidemiology and statistical modeling, measures
of past exposures to coal mine dust are critical to assessing the
relationship between miners' cumulative coal mine dust exposure and
their risk of developing [pneumoconiosis]" (Document ID 4072,
Attachment 48, p. 8). The same rationale applies here. Thus, OSHA's
decision to rely on epidemiological data is well supported by the
record.
Commenters from companies and industry groups also argued that they
had no knowledge of workers acquiring silicosis in their companies or
industry (e.g., Document ID 2384, p. 2; 2338, p. 3; 2365, p. 2; 2185,
p. 3; 2426, p. 1). OSHA received similar comments as part of a letter
campaign in which over 100 letters from brick industry representatives
claimed there to be little or no silicosis observed in the industry
despite historical exposures above the PEL (e.g., Document ID 2009).
OSHA considered these comments and believes that many companies,
including companies in the brick industry, may not have active medical
surveillance programs for silicosis. Silicosis may not develop until
after retirement as a result of its long latency period. In addition,
silica exposures in some workplaces may be well below the final PEL as
a result of the environment in which workers operate, including
existing controls. Thus, OSHA believes that it is difficult to draw
conclusions about the rate of silicosis morbidity in specific
workplaces without having detailed information on medical surveillance,
silica exposures, and follow-up. This is why OSHA relies heavily on
epidemiological studies with detailed exposure data and extended
follow-up, and uses these data to evaluate exposure-response
relationships to assess health risks at the preceding and new PELs.
Commenters also argued that, due to the long latency of the
disease, silicosis cases diagnosed today are the result of exposures
that occurred before the former PELs were adopted, and thus reflect
exposures considerably higher than the previous PELs (e.g., Document ID
2376, p. 3; 2307, p. 12; 4194, p. 9; 3582, Tr. 1935). OSHA notes that
the evidence shows that the declining trend in silicosis mortality does
not provide a complete picture with regard to silicosis trends in the
United States. Although many silicosis deaths reported today are likely
the result of higher exposures (both magnitude and duration), some of
which may have occurred before OSHA adopted the previous PELs,
silicosis cases continue to occur today--some in occupations and
industries where exposures are new and/or increasing. For example, five
states reported cases of silicosis in dental technicians for the years
1994 to 2000 (CDC, MMWR Weekly, 2004, 53(09), pp. 195-197), for the
first time. For the patients described in this report, the only
identified source of crystalline silica exposure was their work as
dental technicians. Exposure to respirable crystalline silica in dental
laboratories can occur during procedures that generate airborne dust
(e.g., mixing powders, removing castings from molds, grinding and
polishing castings and porcelain, and using silica sand for abrasive
blasting). In 2015, the CDC reported the first case of silicosis
(progressive massive fibrosis) associated with exposure to quartz
surfacing materials (countertop fabrication and installation) in the
U.S. The patient was exposed to dust for 10 years from working with
conglomerate or quartz surfacing materials containing 70%-90%
crystalline silica. Cases had previously been reported in Israel, Italy
and Spain (MMWR, 2015, 64(05); 129-130). Recently, hazardous silica
exposures have been newly documented during hydraulic fracturing of gas
and oil wells (Bang et al., MMWR, 2015, 64(05); 117-120).
Dr. Rosenman's testimony provides support for this point. He
testified that newer industries with high silica exposures may also be
under-recognized because workers in those industries have not yet begun
to be diagnosed with silicosis due to the latency period (Document ID
3577, p. 858). Dr. Rosenman submitted to the record a study by Valiante
et al. (2004, Document ID 3926) that identified newly exposed
construction workers in the growing industry of roadway repair, which
began using current methods for repair in the 1980s. These methods use
quick-setting concrete that generates dust containing silica above the
OSHA PEL when workers perform jackhammering, and sawing and milling
concrete operations. State surveillance systems identified 576
confirmed silicosis cases in New Jersey, Michigan, and Ohio that were
reported to NIOSH for the years 1993 through 1997. Of these, 45 (8
percent) cases were in construction workers, three of which had been
engaged in highway repair.
Sample results for this study indicated a significant risk of
overexposure to crystalline silica for workers who performed the five
highway repair tasks involving concrete. Sample results in excess of
the OSHA PEL were found for operating a jackhammer (88 percent of
samples), sawing concrete and milling concrete tasks (100 percent of
samples); cleaning up concrete tasks (67 percent of samples); and
drilling dowels (100 percent of samples). No measured exposures in
excess of the PEL were found for milling asphalt and cleaning up
asphalt; however, of the eight samples collected for milling asphalt,
six (55 percent) results approached the OSHA PEL, and one was at 92
percent of the PEL. No dust-control measures were in place during the
sampling of these highway repair operations.
The authors pointed out that surveillance systems such as those
implemented by these states are limited in their ability to detect
diseases with long latencies in highway repair working populations
because of the relatively short period of time that modern repair
methods had been in use when the study was conducted. Nevertheless, a
few cases were identified, although the authors explain that the work
histories of these cases were incomplete, and the authors recommended
ongoing research to evaluate the silicosis disease potential among this
growing worker population (Document ID 3926, pp. 876-880). In
construction, use of equipment such as blades used on handheld saws to
dry-cut masonry materials have increased both efficiency and silica
exposures for workers over the past few decades (Document ID 4223, p.
11-13). Exposure data collected by OSHA as part of its technological
feasibility analysis demonstrates that exposures frequently exceed
previous exposure limits for these operations when no dust controls are
used (see Chapter IV of the FEA). Another operation seeing new and
increasing exposures to respirable crystalline silica is hydraulic
fracturing in the oil and gas industry (Document ID 3588, p. 3773).
Information in the record from medical professionals noted that lung
diseases caused by silica exposures are "not relics of the past," and
that they continue to see cases of silicosis and other related
diseases, even among younger workers who entered the workforce after
the former PEL was enacted (see Document ID 3577, Tr. 773).
Furthermore, the general declining trend seen in the death
certificate data is considerably more modest in silicosis morbidity
data. In his written testimony, Dr. Rosenman stated that the nationwide
number of hospitalizations where silicosis was one of the discharge
diagnoses has remained constant, with 2,028 hospitalizations reported
in 1993 and 2,082 in 2011 (Document ID 3425, p. 2). It is the opinion of
medical professionals including the American Thoracic Society and the
American College of Chest Physicians that these hospitalizations likely
represent "the tip of the iceberg" (of silicosis cases) since milder
cases are not likely to be admitted to the hospital (Document ID 2175,
p. 3). Again, this evidence shows that the declining trend observed in
silicosis mortality statistics does not provide a complete picture with
regard to silicosis trends in the United States. While silicosis
mortality has decreased substantially since records were first
available in 1968, the number of silicosis related deaths appears to
have leveled off (see Table V-2; Document ID 3577, Tr. 775). Workers
are still dying from silicosis today, and new cases are being
identified by surveillance systems, where they exist.
Based on the testimony and evidence described above, OSHA finds
that the surveillance data describing trends in silicosis mortality and
morbidity provide useful evidence of a continuing problem, but are not
suitable for evaluating either the adequacy of the previous PELs or
whether a more protective standard is needed. In fact, it would not be
possible to derive estimates of risk at various exposure levels from
the available surveillance data for silica. OSHA therefore
appropriately continues to rely on epidemiological data and its
quantitative risk assessment to support the need to reduce the previous
PELs in its final rule.
Commenters also argued that OSHA has failed to prove that a new
standard is necessary because silica-associated deaths are due to
existing exposures in excess of the previous PELs; therefore, the
Agency should focus on better enforcing the previous PELs, rather than
enacting a new standard (e.g., Document ID 2376, p. 8; 2307, p. 12;
4016, pp. 9-10; 3582, Tr. 1936). OSHA does not find this argument
persuasive. First, many of the commenters used OSHA's targeted
enforcement data to make this point. These data were obtained during
inspections where OSHA suspected that exposures would be above the
previous PELs. Consequently, the data by their very nature are skewed
in the direction of exceeding the previous PELs, and such enforcement
serves a deterrence function, encouraging future compliance with the
PEL.
Second, not all commenters agreed that overexposures were
"widespread." A few other commenters (e.g., AFS) thought that OSHA
substantially overstated the number of workers occupationally exposed
above 100 [mu]g/m\3\ in its PEA (Document ID 2379, p. 25). However
OSHA's risk analyses evaluated various exposure levels in determining
risks to workers, and did not rely on surveillance data, which rarely
have associated exposure data. Although OSHA relied on exposure data
from inspections to assess technological feasibility, it did not rely
on inspection data for its risk assessment because these exposure data
are not tied to specific health outcomes. Instead, the exposure data
used for risk assessment purposes is found in the scientific studies
discussed throughout this preamble section.
The surveillance data are also not comparable to OSHA's estimate of
deaths avoided by the final rule because, as is broadly acknowledged,
silicosis is underreported as a cause of death on death certificates.
Thus, the surveillance data capture only a portion of the actual
silicosis mortality. This point was raised by several rulemaking
participants, including Dr. Rosenman; Dr. James Cone, MD, MPH,
Occupational Medicine Physician at the New York City Department of
Health, the AFL-CIO; and the American Thoracic Society (ATS) (Document
ID 3425, p. 2; 3577, Tr. 855, 867; 4204, p. 17; 2175, p. 3; 3577, Tr.
772).
The rulemaking record includes one study that evaluated
underreporting of silicosis mortality. Goodwin et al. (2003, Document
ID 1030) estimated, through radiological confirmation, the prevalence
of unrecognized silicosis in a group of decedents presumed to be
occupationally exposed to silica, but whose causes of death were
identified as respiratory diseases other than silicosis. In order to
assess whether silicosis had been overlooked and under-diagnosed by
physicians, the authors looked at x-rays of decedents whose underlying
cause of death was listed as tuberculosis, cor pulmonale, chronic
bronchitis, emphysema, or chronic airway obstruction, and whose usual
industry was listed as mining, construction, plastics, soaps, glass,
cement, concrete, structural clay, pottery, miscellaneous mineral/
stone, blast furnaces, foundries, primary metals, or shipbuilding and
repair.
Any decedent found to have evidence of silicosis on chest x-ray
with a profusion score of 1/0 was considered to be a missed diagnosis.
Of the 177 individuals who met study criteria, radiographic evidence of
silicosis was found in 15 (8.5 percent). The authors concluded that
silicosis goes undetected even when the state administers a case-based
surveillance system. Goodwin et al. (2003, Document ID 1030) also cites
mortality studies of Davis et al. (1983, Document ID 0999) and Hughes
(1982, Document ID 0362) who reported finding decedents with past chest
x-ray records showing evidence of silicosis but no mention of silicosis
on the death certificate.
The Goodwin et al. (2003) study illustrates the importance of
information about the decedent's usual occupation and usual industry on
death certificates. Yet for the years 1985 to 1999, only 26 states
coded this information for inclusion on death certificates. If no
occupational information is available, recognizing exposure to silica,
which is necessary to diagnose silicosis, becomes even more difficult,
further contributing to possible underreporting.
Dr. Rosenman, a physician, epidemiologist and B-reader, testified
that in his research he found silicosis recorded on only 14 percent of
the death certificates of individuals with confirmed silicosis
(Document ID 3425, p. 2; 3577, Tr. 854; see also 3756, Attachment 11).
This means that as much as 86 percent of deaths related to silicosis
are missing from the NIOSH WoRLD database, substantially compromising
the accuracy of the surveillance information. Dr. Rosenman also found
that silicosis is listed as the cause of death in a small percentage of
individuals who have an advanced stage of silicosis; 18 percent in
those with progressive massive fibrosis (PMF) and 10 percent in those
with category 3 profusion.
As noted above, factors that contribute to underreporting by health
care providers include lack of information about exposure histories and
difficulty recognizing occupational illnesses that have long latency
periods, like silicosis (e.g., Document ID 4214, p. 13; 3584, Tr.
2557). Dr. Rosenman's testimony indicated that many physicians are
unfamiliar with silicosis and this lack of recognition is one factor
that contributes to the low recording rate for silicosis on death
certificates (Document ID 3577, Tr. 855). In order to identify cases of
silicosis, a health care provider must be informed of the patient's
history of occupational exposure to dust containing respirable silica,
a critical piece of information in identifying and reporting cases of
silicosis. However, information on a decedent's usual occupation and/or
industry is often not available at the time of death or is too general
to be useful. If the physician completing the death certificate is
unaware of the decedent's occupational exposure history to crystalline
silica, and does not have that information available to her/him on a
medical record, a diagnosis of silicosis on the death certificate is
unlikely. According to a study submitted by the Laborers' Health and
Safety Fund of North America, (Wexelman et al., 2010), a sample of
physician residents surveyed in New York City did not believe that
cause of death reporting is accurate; this was a general finding, and
not specific to silicosis (Document ID 3756, Attachment 7).
The ATS and the American College of Chest Physicians commented that
physicians often fail to recognize or misdiagnose silicosis as another
lung disease on the death certificate, leading to under-reporting on
death certificates (3577, Tr. 821, 826-827) and under-recognize and
underreport cases of silicosis (Document ID 2175, p. 3). As Dr.
Weissman from NIOSH responded:
...it's well known that death certificates don't capture all
of the people that have a condition when they pass away, and so
there would be many that probably would not be captured if the
silicosis didn't directly contribute to the death and depending on
who filled out the death certificate, and the conditions of the
death and all those kinds of things. So it's an under-representation
of people who die with the condition.... (Document ID 3579, pp.
166-167).
Although there is little empirical evidence describing the extent
to which silicosis is underreported as a cause of death, OSHA finds,
based on this evidence as well as on testimony in the record, that the
available silicosis surveillance data are likely to significantly
understate the number of deaths that occur in the U.S. where silicosis
is an underlying or contributing cause. This is in large part due to
physicians and medical residents who record causes of death not being
familiar or having access to the patient's work or medical history (see
Wexelman et al., 2010, Document ID 3756, Attachment 7; Al-Samarri et
al., Prev. Chronic Dis. 10:120210,2013). According to Goodwin et al.
(2003, Document ID 1030, p. 310), most primary care physicians do not
take occupational histories, nor do they receive formal training in
occupational disease. They further stated that, since it is likely that
a person would not retain the same health care provider over many
years, even if the presence of silicosis in a patient might have been
known by a physician who cared for them, it would not necessarily be
known by another physician or resident who recorded cause of death
years or decades later and who did not have access to the patient's
medical or work history. OSHA finds the testimony of Dr. Rosenman
compelling, who found that silicosis was not recorded as an underlying
or contributing cause of death even where there was chest x-ray
evidence of progressive massive fibrosis related to exposure to
crystalline silica.
Some commenters stated that the decline in silicosis mortality
demonstrates that there is a threshold for silicosis above the prior
PEL of 100 [mu]g/m\3\ (Document ID 4224, p. 2-5; 3582, Tr. 1951-1963).
OSHA finds this argument irrelevant as the threshold concept does not
apply to historical surveillance data. As noted above and discussed in
Section V.I, Comments and Responses Concerning Threshold for Silica-
Related Diseases, OSHA believes that surveillance data should not be
used for quantitative risk analysis (including determination of
threshold effects) because it lacks an exposure characterization based
on sampling. Thus, the surveillance data cannot demonstrate the
existence of a population threshold.
There is also evidence in the record that silicosis morbidity
statistics reviewed earlier in this section are underreported. This can
be due, in part, to the relative insensitivity of chest roentgenograms
for detecting lung fibrosis. Hnizdo et al. (1993) evaluated the
sensitivity, specificity and predictive value of radiography by
correlating radiological and pathological (autopsy) findings of
silicosis. "Sensitivity" and "specificity" refer to the ability of
a test to correctly identify those with the disease (true positive
rate), and those without the disease (true negative). Because
pathological findings are the most definitive for silicosis, findings
on biopsy and autopsy provide the best comparison for determining
sensitivity and specificity of chest imaging.
The study used three readers and defined a profusion score of 1/1
as positive for silicosis. Sensitivity was defined as the probability
of a positive radiological reading (ILO category >1/1) given that
silicotic nodules were found in the lungs at autopsy. Specificity was
defined as the probability of a negative radiological reading (ILO
category < 1/1) given that no, or only an insignificant number of
silicotic nodules were found at autopsy. The average sensitivity values
were low for each of the three readers (0.39, 0.37, and 0.24), whereas
the average specificity values were high (0.99, 0.97, and 0.98). For
all readers, the proportion of true positive readings (i.e., the
sensitivity) increased with the extent of silicosis found at autopsy
(Document ID 1050).
In the only published study that quantified the extent of
underreporting of silicosis mortality and morbidity, Rosenman et al.
estimated the number of new cases of silicosis occurring annually in
the U.S. at between 3,600 and 7,300 based on the ratio of living to
deceased persons identified and confirmed as silicotics in the Michigan
surveillance data and extrapolating that ratio using the number of
deaths due to silicosis for the U.S. as a whole (2003, Document ID
0420). OSHA reviewed the study in its Review of the Health Effects
Literature (Document ID 1711, p. 48). Patrick Hessel, Ph.D., criticized
the methods used by Dr. Rosenman, and deemed the resulting estimates
unreliable, stating that the actual number of new silicosis cases
arising each year is likely to be lower than the authors estimated
(Document ID 2332, p. 2; 3576, Tr. 323-331).
OSHA disagrees with the criticisms that Dr. Hessel, commenting on
behalf of the Chamber, offered on the study by Rosenman et al. (2003,
Document ID 0420). Specifically, Dr. Hessel argued: (1) That the
silicosis-related deaths used by Rosenman et al. occurred during the
period 1987 through 1996, and do not reflect the declining numbers
after that time period; (2) that the Michigan surveillance system
relied on a single B-reader who was biased toward finding silicosis in
patients who were brought to his attention for suspected silicosis; and
(3) that the Michigan population was not representative of the rest of
the country, since about 80 percent of the workers diagnosed with
silicosis worked in foundries, which are not prevalent in most other
states. Finally, in his hearing testimony, Dr. Hessel criticized the
capture-recapture analysis used by Rosenman et al. to estimate the
extent of underreporting of cases, stating that a number of underlying
assumptions used in the analysis were not met (Document ID 3576, Tr.
323-332).
Dr. Rosenman addressed many of these criticisms in the study and at
the rulemaking hearing. Regarding the fact that the number of
silicosis-related deaths does not reflect the decline in deaths after
1996, Dr. Rosenman testified that, although the number of recorded
silicosis deaths have declined since then, the ratio of cases to deaths
has increased because the number of cases has not declined. "The
living to dead ratio that we reported in our published study in 2003
was 6.44. This ratio has actually increased in recent years to 15.2. A
similar ratio...[was] found in the New Jersey surveillance data,
which went from 5.97 to 11.5 times" (Document ID 3577, Tr. 854). If
one were to apply the more recent ratio from Michigan (more than double
the ratio used by Rosenman et al.) to the more recent number of deaths
in the country (about half that recorded in the mid-1990s; see Table V-
1) to extrapolate the number of silicosis cases for the U.S. overall,
the result would be even greater than the estimate in Rosenman et al. (2003).
At the hearing, Dr. Rosenman testified that he was the sole B-
reader of lung x-rays for the study, and that he received the x-ray
films from other radiologists who suspected but did not confirm the
presence of silicosis (Document ID 3577, Tr. 877-878). Dr. Rosenman,
while acknowledging that there could be differences between readers in
scoring x-ray films, argued that such differences in scoring--for
example, whether a film is scored a 3/3, 3/2, or 2/3--did not affect
this study since the study design only required that a case be
identified and confirmed (diagnosis requires a chest radiograph
interpretation showing rounded opacities of 1/0 or greater profusion)
(Document ID 3577, Tr. 877-878; 0420, p. 142).
Dr. Rosenman also addressed the criticism that Michigan's worker
population with silica exposure is significantly different from the
rest of the country. In the study, Rosenman et al. reported that the
ratio of cases to deaths was about the same for Ohio as for Michigan
and, during the public hearing, Dr. Rosenman testified that the ratio
of cases to deaths for New Jersey was also similar to Michigan's (11.5
vs. 15.2) (Document ID 0420, p. 146; 3577, Tr. 854). This similarity
was despite the fact that New Jersey had a different industrial mix,
with fewer foundries (Document ID 3577, Tr. 878). Furthermore, the
estimates made by Rosenman et al. depended on the ratio of cases to
deaths in Michigan, rather than just the number of cases in that state.
The authors believed that the ratio would be unaffected by the level of
industrialization in Michigan (Document ID 0420, p. 146).
Finally, regarding the capture-recapture analysis, OSHA notes that
Dr. Hessel acknowledged that this technique has been used in
epidemiology to estimate sizes of populations identified from multiple
overlapping sources (Document ID 2332, p. 2), which is the purpose for
which Rosenman et al. used the approach. In addition, the Rosenman et
al. study noted that the assumptions used in capture-recapture analysis
could not be fully met in most epidemiological study designs, but that
the effect of violating these assumptions was either negligible or was
evaluated using interaction terms in the regression models employed.
The investigators also reported that the capture-recapture analysis
used on Ohio state surveillance data found that the total number of
cases estimated for the state was between 3.03 and 3.18 times the
number of cases identified, a result that is comparable to that for
Michigan (Document ID 0420, pp. 146-147). After considering Dr.
Hessel's written testimony, Dr. Rosenman testified that "...overall
I don't think his comments make a difference in my data" (Document ID
3577, Tr. 877).
OSHA finds all of Dr. Rosenman's responses to Dr. Hessel's
criticisms to be reasonable. And based on Dr. Rosenman's comments and
testimony, OSHA continues to believe that the Rosenman et al. (2003)
analysis and resulting estimates of the number of new silicosis cases
that arise each year are reasonable. Additionally, Dr. Rosenman, in
updating his data for his testimony for this rulemaking, found that the
ratio had increased from 6.44 in the published study to 15.2 times in
more recent years (Document ID 3577, Tr. 854). The study supports
OSHA's hypothesis that silicosis is a much more widespread problem than
the surveillance data suggest and that OSHA's estimates of the non-
fatal illnesses that will be avoided as a result of this new silica
standard are not unreasonable. Regardless, even assuming commenters'
criticisms have merit, they do not significantly affect OSHA's own
estimates from the epidemiological evidence of the risks of silicosis.
Accordingly, after careful consideration of the available
surveillance data, stakeholders' comments and testimony, and the
remainder of the record as a whole, OSHA has determined that the
available silicosis surveillance data are useful for providing context
and an illustration of a significant general trend in the reduction of
deaths associated with silicosis over the past four to five decades. As
discussed above, and in large part because the data themselves are
limited and incomplete, OSHA believes reliance upon them for the
purpose of estimating the magnitude of the risk would be inappropriate.
The Agency has chosen instead to follow its well-established practice
of relying on epidemiological data to meet its burden of demonstrating
that workers exposed to respirable crystalline silica at the previous
PELs face a significant risk of developing silicosis and that such risk
will be reduced when the new limit is fully implemented.
F. Comments and Responses Concerning Lung Cancer Mortality
OSHA received numerous comments regarding the carcinogenic
potential of crystalline silica as well as the studies of lung cancer
mortality that the Agency relied upon in the Preliminary Quantitative
Risk Assessment (QRA). Many of these comments, particularly from the
ACC, asserted that (1) OSHA should have relied upon additional
epidemiological studies, and (2) the studies that the Agency did rely
upon (Steenland et al., 2001a, as re-analyzed in ToxaChemica, 2004;
Rice et al., 2001; Attfield and Costello, 2004; Hughes et al., 2001;
and Miller and MacCalman, 2009) were flawed or biased. In this section,
OSHA presents these comments and its responses to them.
1. Carcinogenicity of Crystalline Silica
As discussed in the Review of Health Effects Literature and
Preliminary QRA (Document ID 1711, pp. 76-77), in 1997, the World
Health Organization's International Agency for Research on Cancer
(IARC) conducted a thorough expert committee review of the peer-
reviewed scientific literature and classified crystalline silica dust,
in the form of quartz or cristobalite, as Group 1, "carcinogenic to
humans" (Document ID 2258, Attachment 8, p. 211). IARC's overall
finding for silica was based on studies of nine occupational cohorts
that it considered to be the least influenced by confounding factors
(Document ID 1711, p. 76). In March of 2009, 27 scientists from eight
countries participated in an additional IARC review of the scientific
literature and subsequently, in 2012, IARC reaffirmed that respirable
crystalline silica dust is a Group 1 human carcinogen that causes lung
cancer (Document ID 1473, p. 396). Additionally, in 2000, the National
Toxicology Program (NTP) of HHS concluded that respirable crystalline
silica is a known human carcinogen (Document ID 1164, p. 1).
The ACC, in its pre-hearing comments, questioned the carcinogenic
potential of crystalline silica, asserting that IARC's 1996
recommendation that crystalline silica be classified as a Group 1
carcinogen was controversial (Document ID 2307, Attachment A, p. 29).
The ACC cited Dr. Patrick Hessel's 2005 review of epidemiological
studies, published after the initial IARC determination, in which he
concluded that "the silica-lung cancer hypothesis remained
questionable" (Document ID 2307, Attachment A, p. 31). The ACC
reasserted this position in its post-hearing brief, contending that
"epidemiological studies have been negative as often as they have been
positive" (Document ID 4209, pp. 33-34).
After the publication of Dr. Hessel's 2005 review article, IARC
reaffirmed in 2012 its earlier Group 1 classification for crystalline
silica dust (Document ID 1473). As pointed out by Steenland and
Ward, IARC is one of "2 agencies that are usually considered to be
authoritative regarding whether a substance causes cancer in humans,"
the other being the NTP, which has also determined crystalline silica
to be carcinogenic on two separate occasions (2013, article included in
Document ID 2340, p. 5). David Goldsmith, Ph.D., who coauthored one of
the first published articles linking silica exposure to lung cancer,
echoed Steenland and Ward:
It is important to recognize that evidence for silica's
carcinogenicity has been reviewed three times by the International
Agency for Research on Cancer, once in 1987, 1997, and 2012. It has
been evaluated by California's Proposition 65 in 1988, by the
National Toxicology Program in 2000 and reaffirmed in 2011, and by
the National Institute for Occupational Safety and Health in 2002
(Document ID 3577, Tr. 861-862).
Multiple organizations with great expertise in this area, including
the American Cancer Society, submitted comments supporting the thorough
and authoritative nature of IARC's findings regarding silica's
carcinogenicity (e.g., Document ID 1171; 1878). OSHA likewise places
great weight on the IARC and NTP classifications and, based on their
findings, concludes that the carcinogenic nature of crystalline silica
dust has been well established. Further support for this finding is
discussed in Section V.L, Comments and Responses Concerning Causation.
2. Silicosis and Lung Cancer
In addition to debating the conclusions of IARC, Peter Morfeld, Dr.
rer. medic, testifying on behalf of the ACC Crystalline Silica Panel,
concluded that OSHA's risk estimates for lung cancer are "unreliable"
because they "ignore threshold effects and the apparent mediating role
of silicosis" (Document ID 2307, Attachment 2, p. 16). Dr. Morfeld
argued that silicosis is a necessary prerequisite for silica-related
lung cancer. Commenters' arguments about silicosis being a prerequisite
for lung cancer and silicosis having a threshold are linked; if it were
shown both that silicosis requires a certain threshold of exposure and
that only persons with silicosis get lung cancer, then silica-related
lung cancer would also have an exposure threshold. As discussed in
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases, commenters claimed that there is a threshold for
silicosis above the previous PEL for general industry, which would make
any threshold for lung cancer above that level as well. OSHA discusses
these comments in detail in that section, and has determined that even
if lung cancer does not occur in the absence of silicosis, the record
strongly supports the conclusion that workers exposed to respirable
crystalline silica would still be at risk of developing lung cancer as
a result of their exposure because silicosis can develop among workers
whose average and cumulative exposures are below the levels permitted
by the previous PELs.
OSHA received comments from other stakeholders, including Robert
Glenn, representing the Brick Industry Association, and the AFS on the
possible mediating role of silicosis in the development of lung cancer
(Document ID 2307, pp. 29-35; 2343, Attachment 1, pp. 42-45; 2379,
Attachment 2, pp. 24-25). The ACC cited several review articles in
support of its claim that "silica exposures have not been shown to
increase the risk of lung cancer in the absence of silicosis"
(Document ID 2307, Attachment A, pp. 29, 32, 35). These articles
included: A 2004 review of studies by Kurihara and Wada that found that
while silicosis is a risk factor for lung cancer, exposure to silica
itself may not be a risk factor (Document ID 1084); a 2006 review by
Pelucchi et al. that determined that the issue of whether silica itself
increases lung cancer risk in the absence of silicosis has not been
resolved (Document ID 0408); and a 2011 review by Erren et al. that
concluded it is unclear whether silica causes lung cancer in persons
who do not already have silicosis (Document ID 3873). Similarly, the
AFS cited a review by the Health and Safety Executive (2003) that
concluded that increased risks of lung cancer are restricted to those
groups with the highest cumulative exposures, with evidence tending to
show that excess lung cancer mortality is restricted to those with
silicosis (Document ID 2379, Attachment 2, pp. 24-25). Having reviewed
the studies cited by commenters, OSHA has come to the conclusion that
none of the cited studies demonstrates that silicosis is a necessary
precursor to lung cancer, but acknowledges that uncertainty remains
about what percentage of lung cancers in silica-exposed workers are
independent of silicosis.
Similarly, the ACC stated that none of the studies of lung cancer
mortality that OSHA relied upon in the Preliminary QRA demonstrates
that silica exposure causes lung cancer in the absence of silicosis
(Document ID 2307, Attachment A, p. 66). During the rulemaking hearing,
NIOSH scientists addressed the issue of whether silicosis is a
necessary precursor to the development of lung cancer. They stated that
it is a difficult issue to resolve because the two diseases may have a
similar pathway, such that they can develop independently but still
appear correlated. Mr. Robert Park also added that:
[S]ilicosis isn't detectable until there's splotches on the lung
that are visible in x-rays. So prior to that point, somebody could
have [been] developing lung disease and you just can't see it. So,
of course, people that have silicosis are going to have higher lung
cancer, and it's going to look like a threshold because you didn't
see the silicosis in other people that have lower lung cancer risk.
To really separate those two, you'd have to do a really big study.
You'd have to have some measures, independent measures of lung
physiological pathology, and see what's going on with silicosis as a
necessary condition for development of lung cancer (Document ID
3579, Tr. 245-247).
Similarly, David Weissman, MD, concurred that "there's quite a bit
of reason as Bob [Park] said to think that the two processes
[development of silicosis and development of lung cancer] don't require
each other, and it would be extraordinarily difficult to sort things
out in human data" (Document ID 3579, Tr. 247). Indeed, Checkoway and
Franzblau (2000) reviewed the epidemiological literature addressing
this topic, and found that the "limitations of existing epidemiologic
literature that bears on the question at hand suggest that prospects
for a conclusive answer are bleak" (Document ID 0323, p. 257). The
authors concluded that silicosis and lung cancer should be treated in
risk assessments as "separate entities whose cause/effect relations
are not necessarily linked" (Document ID 0323, p. 257). Brian Miller,
Ph.D., a peer reviewer of OSHA's Review of Health Effects Literature
and Preliminary QRA, likewise wrote in his post-hearing comments, "I
consider this issue unanswerable, given that we cannot investigate for
early fibrotic lesions in the living, but must rely on radiographs"
(Document ID 3574, p. 31).
During the public rulemaking hearing, several stakeholders pointed
to a recent study of Chinese pottery workers and miners by Liu et al.
(2013, article included in Document ID 2340) as evidence that exposure
to crystalline silica is associated with lung cancer even in the
absence of silicosis (Document ID 3580, Tr. 1232-1235; 3577, Tr. 803-
804, 862-863). In this study, the authors excluded 15 percent of the
cohort (including 119 lung cancer deaths) with radiographic evidence of
silicosis and found that the risk of lung cancer mortality still
increased with cumulative exposure to crystalline silica, suggesting
that clinically-apparent silicosis is not a prerequisite for
silica-related lung cancer
(article included in Document ID 2340, pp. 3, 7).
The ACC argued that it is "premature to draw that conclusion,"
stating that the Liu study's conclusions are not supported by the data
and raising questions about uncertainty in the exposure estimates,
modeling and statistics, confounding, and the silicosis status of
cohort members (Document ID 2307, Attachment A, p. 48; 4027, pp. 35-36;
4209, pp. 40-51). With regard to exposure estimates, the ACC had a
number of concerns, including that conversion factors determined by
side-by-side sampling in 1988-1989 were used to convert Chinese total
dust concentrations to respirable crystalline silica exposures
(Document ID 4209, pp. 40-41). Dr. Cox expressed concern that these
conversion factors from 1988-1989 might not have been applicable to
other time periods, as particle size distributions could change over
time (Document ID 4027, p. 32). OSHA acknowledges this concern, but
given the "insufficient historical particle size data...to analyze
whether there were changes in particle size distributions from the
1950s to the 1990s," believes that the authors were justified in
making their exposure assumptions (Document ID 4027, p. 32). Dr. Cox's
concerns involving modeling and statistics (see Document ID 4027, pp.
33-36) in the study, including the absence of model diagnostics, the
use of inappropriate or misspecified models, the lack of a discussion
of residual confounding and model uncertainty, and the use of
inappropriate data adjustments and transformations, are discussed in
detail in Section V.J, Comments and Responses Concerning Biases in Key
Studies.
On the issue of confounding, the ACC noted that Liu et al. (2013)
used a subcohort of 34,018 participants from 6 tungsten mines, 1 iron
mine, and 4 potteries derived from a total cohort of 74,040
participants from 29 mines and pottery factories studied previously by
Chen et al. (2007, Document ID 1469; 2307, Attachment A, pp. 48-50).
Liu et al. (2013) excluded participants in the original cohort if
detailed information on work history or smoking was not available, or
if they worked in copper mines or tin mines where the analysis could be
confounded by other exposures, namely radon and carcinogenic polycyclic
aromatic hydrocarbons (PAHs) in the former and arsenic in the latter
(article included in Document ID 2340, p. 2). The ACC's main concern
was that Liu et al. (2013) did not adjust for these confounders in
their analyses, but rather claimed that there were no confounding
exposures in their smaller cohort on the basis of the exclusion
criteria (Document ID 2307, Attachment A, p. 49).
The ACC also noted that Chen et al. (2007) stated that the Chinese
pottery workers were exposed to PAHs, and some of the iron-copper
miners were exposed to PAHs and radon progeny (Document ID 2307,
Attachment A, p. 49). Chen et al. (2007) initially found an association
between respirable silica and lung cancer mortality in the pottery
workers and iron-copper miners, but it disappeared after adjusting for
PAH exposures (Document ID 1469). In the tungsten miners, Chen et al.
(2007) found no significant association for lung cancer mortality,
while Liu et al. (2013) did. Similarly, the ACC pointed out that a
subsequent study by Chen et al. (2012, article included in Document ID
2340) also failed to find a statistically significant increase in the
hazard ratio for lung cancer, meaning that there was no significant
positive exposure-response relationship between cumulative silica
exposure and lung cancer mortality (Document ID 4209, p. 45). Dr.
Morfeld concluded, "Unless and until these issues are resolved, Liu et
al. (2013) should not be used to draw conclusions regarding exposure-
response relationships between RCS [respirable crystalline silica],
silicosis and lung cancer risk" (Document ID 2307, Attachment 2, pp.
15-16).
During the public hearing, counsel to the ACC asked Dr. Steenland,
a co-author on the Liu et al. (2013) study, if he would provide
measurement data on the PAH exposures in the potteries, as well as
present the data from the Liu et al. (2013) study separately for
pottery factories and tungsten mines, as they were in Chen et al.
(2007, Document ID 1469) (Document ID 3580, Tr. 1237-1240). Dr.
Steenland subsequently provided the requested data for inclusion in the
rulemaking record (Document ID 3954).
With respect to the PAH data for the potteries, Dr. Weihong Chen,
the study's first author, reported that, in measurements in 1987-1988
in the four potteries that were excluded from the Liu et al. (2013)
analysis, the mean total PAHs was 38.9 [micro]g/m\3\ and the mean
carcinogenic PAHs was 4.7 [micro]g/m\3\. In the four potteries that
were included in the Liu et al. (2013) analysis, the mean total and
carcinogenic PAHs, as measured in 1987-1988, were substantially lower
at 11.6 and 2.5 [micro]g/m\3\, respectively. When the measurements were
repeated in 2006, the mean total and carcinogenic PAHs in the four
potteries included in the analysis were still lower, at 2.2 and 0.08
[micro]g/m\3\, levels that were "not much higher than environmental
PAH in many [Chinese] cities" (Document ID 3954, p. 2). Dr. Chen also
reported that, when comparing levels within six job titles, there was
no significant correlation between total or carcinogenic PAHs (based on
the 2006 measurements) and respirable silica dust. When the results
were presented separately for the mines and potteries, in analyses
using continuous cumulative exposure, the relationship between silica
exposure and lung cancer mortality remained significant for the pottery
factories, but not the metal mines. In the categorical analyses using
quartiles of cumulative exposure, the results were mixed: The
association between silica exposure and lung cancer mortality was
statistically significant in some exposure quartiles for both metal
mines and pottery factories (Document ID 3954, p. 2).
Based upon these subsequent data, the ACC concluded that PAHs were
likely present in the potteries but not in the mines (Document ID 4209,
p. 45). OSHA believes this conclusion, although plausible, to be
speculative. What is known is that the potteries that were excluded had
a higher average level of PAHs, and that a significant association
between cumulative silica exposure and lung cancer mortality remained
in the included potteries even after the analysis was separated by
potteries and mines. However, the association was less clear in the
metal mines.
The ACC also raised concerns about the silicosis status of lung
cancer cases in the Liu cohort, asserting that some workers may not
have had post-employment radiography given that social health insurance
only recently began to pay for it. As such, the ACC asserted that some
workers who developed lung cancer post-employment may have also had
undiagnosed silicosis (Document ID 4209, pp. 49-50). OSHA acknowledges
the limitations of the study, as with any retrospective study, but also
notes that no evidence was put forth to indicate that workers with
silicosis were misclassified in the study as workers without silicosis.
Further, Dr. Goldsmith testified that the method used by Liu et al. for
excluding workers with silicosis (x-ray findings) was "very eminently
reasonable," given that the only foolproof means of proving the
absence of silicosis--autopsy--was not available for this particular
cohort (Document ID 3577, Tr. 874-875).
Thus, OSHA concludes that the Liu et al. (2013) study preliminarily
suggests that silicosis is not required for the development of lung cancer;
however, no one study will settle the question of the role of silicosis
in the carcinogenicity of crystalline silica. As acknowledged by Dr.
Cox, the Agency did not rely upon the Liu et al. (2013) study in its
preliminary or final QRA (Document ID 2307, Attachment 4, p. 37).
Overall, after giving lengthy consideration to all evidence in the
record regarding whether silicosis is a necessary precursor to the
development of lung cancer, including the Liu study, the NIOSH
testimony, and the mechanistic evidence for the carcinogenicity of
crystalline silica discussed in Section V.H, Mechanisms of Silica-
Induced Adverse Health Effects, OSHA concludes that the mediating role
of silicosis in the development of lung cancer is not "apparent," as
suggested by Dr. Morfeld and the ACC (Document ID 2307, Attachment 2,
p. 16). As such, OSHA continues to believe that substantial evidence
supports the Agency's decision to consider lung cancer as a separate,
independent health endpoint in its risk analysis. The Agency also notes
that even if lung cancer does not occur in the absence of silicosis,
the record strongly supports the conclusion that workers exposed to
respirable crystalline silica would still be at risk of developing lung
cancer as a result of their exposure because silicosis can develop from
average and cumulative exposures below the levels allowed at the
previous PEL (see Section V.I, Comments and Responses Concerning
Thresholds for Silica-Related Diseases.)
3. Additional Studies
Stakeholders also suggested several additional studies that they
believe OSHA should include in its QRA on lung cancer. The AFS
commented that OSHA's Preliminary QRA overlooked a 2003 report by the
Health and Safety Executive (HSE, Document ID 1057), asserting that
over 40 percent of the references cited by HSE were omitted in OSHA's
review (Document ID 4035, p. 2). OSHA disagrees with this assessment of
overlooking the report, noting that the Agency reviewed and referenced
the HSE report in its Review of Health Effects Literature and
Preliminary QRA (Document ID 1711, p. 77). As discussed in Section V.C,
Summary of the Review of Health Effects Literature and Preliminary QRA,
OSHA used a weight-of-evidence approach to evaluate the scientific
studies in the literature to determine their overall quality. In so
doing, OSHA thoroughly reviewed approximately 60 published, peer-
reviewed primary epidemiological studies covering more than 30
occupational cohorts in over a dozen industrial sectors, as well as the
IARC pooled study and several meta-analyses (Document ID 1711, pp. 75-
172).
The AFS also submitted a 2011 review of 30 foundry epidemiology
studies by the Industrial Industries Advisory Council (IIAC) and noted
that only 7 of those 30 studies were included in OSHA's Review of
Health Effects Literature and Preliminary QRA (Document ID 2379, p.
24). AFS wrote:
The PQRA largely dismisses the foundry epidemiology studies,
based on assertions of positive confounding. However, a study
showing that there is no adverse effect despite a positive
confounder is not only still relevant to the question, but should be
more persuasive than a study without positive confounders because
the data then show that even with an additive risk, there is no
increase in effect at the reported exposure levels (Document ID
2379, p. 24).
In response to this comment, OSHA gathered the remaining 23 foundry
studies cited in the submitted report and placed them in the rulemaking
docket during the post-hearing comment period. OSHA notes, in the first
instance, that most of these studies were not designed to study the
effects of silica exposure on foundry workers, and did not even attempt
to do so; rather, their purpose was to examine lung cancer mortality
and/or morbidity in foundry work, which involves many toxic and
otherwise harmful substances besides silica. Therefore, OSHA would
likely be unable to suitably use these studies as a basis for a
quantitative risk assessment regarding respirable crystalline silica by
itself.
With respect to AFS's assertions of studies showing "no adverse
effect," OSHA notes that the summary section of the IIAC review
report, submitted as evidence by AFS, stated that, "The cohort
mortality studies and two morbidity studies suggest an increased risk
of lung cancer in foundry workers when considered overall, but do not
support a doubling of risk....Findings in the case-control studies,
the majority of which adjust for the effects of smoking...tend to
support those of the cohort studies" (Document ID 3991, p. 5). As
such, this review of 30 foundry epidemiology studies showed an
increased excess risk of lung cancer from foundry work; the fact that
the excess risk was not increased by a factor of two is irrelevant to
the current proceedings. The factor of two appears to be used by the
IIAC in determining whether monetary benefits should be paid to foundry
workers in Great Britain and is completely unrelated to OSHA's
statutory requirements for determining whether workers exposed to
silica are at a significant risk of material impairment of health.
Given that excess lung cancer was observed in many of these studies,
OSHA rejects the AFS's assertion that, even with positive confounding,
there was no increase in adverse effect (i.e., lung cancer).
OSHA also notes that the IIAC's finding of an elevated risk of lung
cancer in foundries is not surprising. As Dr. Mirer stated during his
testimony, IARC categorized foundry work as Group 1, carcinogenic to
humans, in 1987 based on observed lung cancer (Document ID 2257,
Attachment 3, p. 5). IARC reaffirmed its Group 1 classification for
foundry work in 2012 (Document ID 4130). However, as noted by OSHA in
its Review of Health Effects Literature, the foundry epidemiology
studies were profoundly confounded by the presence of exposures to
other carcinogens, including PAHs, aromatic amines, and metals
(Document ID 1711, p. 264). Because of this confounding, as well as the
fact that most of these studies did not specifically study the effects
of silica exposure on foundry workers, OSHA has decided not to include
them in its QRA.
The ACC likewise cited several individual studies that it believed
found no relationship between silica exposure and lung cancer risk
(Document ID 2307, Attachment A, pp. 33-35). These included studies by:
(1) Yu et al. (2007), which found no consistent exposure-response
relationship between silica exposure and lung cancer death in workers
with silicosis in Hong Kong (Document ID 3872); (2) Chen et al. (2007),
which found, as mentioned in relation to the Liu et al. (2013) study,
no relationship between silica exposure and lung cancer after adjusting
for confounders in a study of Chinese tungsten miners, tin miners,
iron-copper miners, and pottery workers (Document ID 1469); (3) Birk et
al. (2009), which found the standardized mortality ratio (SMR) for lung
cancer was not elevated in a subgroup of men who worked in areas of
German porcelain plants with the highest likely silica exposures
(Document ID 1468); (4) Mundt et al. (2011), which found, in a
subsequent analysis of the German porcelain industry, that cumulative
silica exposure was not associated with lung cancer mortality,
mortality from kidney cancer, or any other cause of death other than
silicosis (Document ID 1478); and (5) Westberg et al. (2013), which
found that cumulative silica exposure was not associated with lung
cancer morbidity (Document ID 4054).
Briefly, Chen et al. (2007) examined a cohort of male workers in 29
Chinese mines and factories, and initially found a significant trend
between cumulative silica exposure and lung cancer mortality in pottery
workers and tin miners; this trend was no longer significant after
adjustment for occupational confounders (carcinogenic PAHs in
potteries, arsenic in tin mines) (Document ID 1469, pp. 320, 323-324).
On the contrary, Liu et al. (2013) demonstrated a statistically
significant association between cumulative silica exposure and lung
cancer mortality after excluding mines and factories with confounding
exposures (article included in Document ID 2340). As noted previously,
there are questions of how confounding exposures to radon, PAHs, and
arsenic were handled in both the Chen et al. (2007) and Liu et al.
(2013) studies. One important difference between the two studies,
however, was the follow-up time. While Chen et al. (2007) had follow-up
to 1994 and identified 511 lung cancer deaths in a cohort of 47,108
workers (Document ID 1469, pp. 321-322), Liu et al. (2013) had follow-
up to 2003 and identified 546 lung cancer deaths in a cohort of 34,018
workers (article included in Document ID 2340, pp. 2-4).
OSHA discussed the Birk et al. (2009, Document ID 1468) and Mundt
et al. (2011, Document ID 1478) studies of the German porcelain
industry in its Supplemental Literature Review, noting several
limitations that are applicable to both studies and might preclude the
conclusion that there was no association between silica exposure and
lung cancer (Document ID 1711, Attachment 1, pp. 6-12). One such
limitation was the mean age of subjects--35 years--at the start of
follow-up, making this a relatively young cohort in which to observe
lung cancer. The mean follow-up period of 19 years per subject was also
a limitation, given the long latency for lung cancer and the young age
of the cohort at the start of follow-up; only 9.2 percent of the cohort
was deceased by the end of the follow-up period. OSHA noted that Mundt
et al. (2011) acknowledged that additional follow-up of the cohort may
be valuable (Document ID 1711, Attachment 1, pp. 10-11; 1478, p. 288).
In addition, Mundt et al. (2011) had only 74 male lung cancer deaths,
some of whom had possible or probable prior silica exposure that could
have resulted in cumulative exposure misclassification (Document ID
1478, pp. 285, 288). The authors also reported statistically
significantly elevated lung cancer hazard ratios for some categories of
average silica exposure, but did not present any trend analysis data
(Document ID 1478, p. 285). It also does not appear that Mundt et al.
performed any lagged analyses for lung cancer to account for the
latency period of lung cancer.
Following the ACC's citation of the Yu et al. (2007) and Westberg
et al. (2013) studies in its pre-hearing comments, OSHA obtained and
reviewed these studies, and added them to the rulemaking docket
(Document ID 3872; 4054). Yu et al. (2007) followed a cohort of 2,789
workers in Hong Kong diagnosed with silicosis between 1981 and 1998.
The average follow-up time was 9 years, with 30.6 percent of the cohort
deceased when the study ended in 1999. The SMR for lung cancer was not
statistically significantly elevated following indirect adjustment for
cigarette smoking; similarly, the authors did not find a significant
exposure-response relationship between cumulative silica exposure and
lung cancer mortality (Document ID 3872). Westberg et al. (2013)
studied a group of 3,045 male Swedish foundry workers to determine lung
cancer incidence and morbidity. Although the lung cancer incidence was
statistically significantly elevated, the authors did not find a
significant exposure-response relationship with cumulative quartz
exposure (Document ID 4054, p. 499).
Regarding these studies, OSHA notes that the Westberg et al. (2013)
study, like other foundry studies, is confounded by other carcinogenic
substances present in foundries, including, as the authors pointed out,
phenol, formaldehyde, furfuryl alcohols, PAHs, carbon black,
isocyanates, and asbestos (Document ID 4054, p. 499). The Yu et al.
(2007) study had an average follow-up period of only 9 years (Document
ID 3872, p. 1058, Table 1), which is a short follow-up period when
considering the latency period for the development of cancer. In
addition, the Yu et al. study (2007), as described in the earlier Tse
et al. (2007) study, used a job exposure matrix developed from expert
opinion to assign estimated past levels of silica exposure to
individuals based on self-reported work history; changes in exposure
intensity with calendar year were not considered because of limited
data (Document ID 3841, p. 88; 3872, p. 1057). OSHA notes that this
exposure estimation may have included considerable misclassification
due to inaccuracies in self-reported work history, the use of expert
opinion to estimate past exposure levels rather than actual
measurements for the subjects under study, and the failure to
incorporate any changes in exposure levels over calendar time into the
exposure estimates. Although these exposure estimates were used in an
analysis that found a significant exposure-response for NMRD mortality
among workers with silicosis (Tse et al., 2007, Document ID 3841), an
exposure-response for lung cancer mortality may not be as strong and
may be harder to detect, requiring more accurate exposure information.
OSHA also notes that NMRD mortality is likely to be a competing cause
of death with lung cancer, such that some workers may have died from
NMRD before developing lung cancer. The workers with silicosis in this
study also had high exposures (mean cumulative exposure of 10.89 mg/
m\3\-yrs) (Document ID 3872, p. 1058), possibly making it difficult to
detect an exposure-response for lung cancer when exposures are
relatively homogenous and high. Selection effects would have been
extreme in these highly-exposed workers, whose all-cause mortality was
double what would be expected (853 deaths observed, 406 expected) in
the general population of males in Hong Kong and whose respiratory
disease mortality was an astounding six times the expected level (445
deaths observed, 75 expected) (Document ID 3872, p. 1059).
OSHA acknowledges that not every study reaches the same results and
conclusions. This is typically true in epidemiology, as there are
different cohorts, measurements, study designs, and analytical methods,
among other factors. As a result, scientists critically examine the
studies, both individually and overall, in the body of literature to
draw weight-of-evidence conclusions. IARC noted, with respect to its
1997 carcinogenicity determination:
[N]ot all studies reviewed demonstrated an excess of cancer of
the lung and, given the wide range of populations and exposure
circumstances studied, some non-uniformity of results had been
expected. However, overall, the epidemiological findings at the time
supported an association between cancer of the lung and inhaled
crystalline silica ([alpha]-quartz and cristobalite) resulting from
occupational exposure (Document ID 1473, p. 370).
Given IARC's re-affirmation of this finding in 2012, OSHA does not
believe that the individual studies mentioned above fundamentally
change the weight of evidence in the body of literature supporting the
carcinogenicity of crystalline silica. The best available evidence in
the rulemaking record continues to indicate that exposure to respirable
crystalline silica causes lung cancer. OSHA acknowledges, however, that
there is some uncertainty with respect to the exact magnitude of the
lung cancer risk, as each of the key studies relied upon provides
slightly different risk estimates, as indicated in Table VI-1.
Further, the ACC focused extensively on and advocated for a study
by Vacek et al. (2011) that found no significant association between
respirable silica exposure and lung cancer mortality in a cohort of
Vermont granite workers (Document ID 1486, pp. 75-81). Included in the
rulemaking docket are the peer-reviewed published version of the study
(Document ID 1486) and the earlier Final Report to the ACC, whose
Crystalline Silica Panel funded the study (Document ID 2307, Attachment
6), as well as comments from two of the authors of Vacek et al. (2011)
responding to OSHA's treatment of the study in its Supplemental
Literature Review (Document ID 1804). The ACC stated:
Perhaps of most interest and relevance for present purposes--
because the cohort has been studied so extensively in the past and
because the present PEL is based indirectly on experience in the
Vermont granite industry--is the mortality study of Vermont granite
workers published in 2011. While the Vermont granite workers cohort
has been studied on a number of previous occasions, this is the most
comprehensive mortality study of Vermont granite workers to date
(Document ID 2307, Attachment A, p. 36).
The ACC criticized OSHA for rejecting the Vacek et al. (2011) study
in its Supplemental Literature Review and instead relying upon the
Attfield and Costello (2004, Document ID 0284) study of Vermont granite
workers (Document ID 2307, Attachment A, pp. 36-47; 4209, pp. 34-36).
The ACC asserted several differences between the studies. First, while
Attfield and Costello had 5,414 workers (201 lung cancer deaths) in the
cohort, Vacek et al. had 7,052 workers (356 lung cancer deaths) as they
extended the follow-up period by 10 years to 2004. Vacek et al. also
claimed to have more complete mortality data, finding that "162
workers, whom Attfield assumed were alive in 1994, had died before that
time and some decades earlier" (Document ID 2307, Attachment A, p.
38). In addition, Vacek et al. used exposure measurements and raw data
not used by Attfield and Costello; for example, Vacek et al. used
pension records and interviews from other studies to account for gaps
in employment and changes in jobs, while Attfield and Costello assumed
that a person remained in the same job between chest x-rays at the
Vermont Department of Industrial Health surveillance program. Different
conversion factors to estimate gravimetric concentrations from particle
count data were also used: Attfield and Costello used a factor of 10
mppcf = 75 [micro]g/m\3\ while Vacek et al. used a factor of 10 mppcf =
100 [micro]g/m\3\ (Document ID 2307, Attachment A, pp. 36-39; 1804, p.
3). OSHA notes that this discrepancy in gravimetric conversion factors
should not affect the detection of an exposure-response relationship,
as all exposures would differ by a constant factor.
The ACC also pointed out that Attfield and Costello's exposure
estimate for sandblasters was 60 [micro]g/m\3\ prior to 1940, 50
[micro]g/m\3\ from 1940-1950, and 40 [micro]g/m\3\ after 1950,
maintaining these numbers were too low compared to Vacek et al.'s
estimates of 240, 160, and 70 [micro]g/m\3\, respectively (Document ID
2307, Attachment A, p. 39; 1486, p. 313). Attfield and Costello took
these estimates for sand blasters from the Davis et al. (1983, Document
ID 0999) study, discussed in detail below; the estimates were based on
six published industrial hygiene measurement studies.
Lastly, the ACC posited that Attfield and Costello inappropriately
excluded the highest exposure group, stating:
Vacek et al. used all their data in evaluating potential E-R
[exposure-response] trends with increasing exposure. Attfield and
Costello did not. Instead, on a post hoc basis, they excluded the
highest exposure category from their analysis when they discovered
that the E-R trend for lung cancer was not significant if that group
was included (even though the trends for non-malignant respiratory
diseases were significant when all the data were used). This is an
example of both data selection bias and confirmation bias (Document
ID 2307, Attachment A, p. 40).
Based upon these assertions, the ACC concluded, "In sum, when
judged without a result-oriented confirmation bias, the larger, more
recent, more comprehensive, and more detailed study by Vacek et al.
(2011) must be deemed to supersede Attfield and Costello (2004) as the
basis for evaluating potential silica-related lung cancer risks in the
Vermont granite industry" (Document ID 2307, Attachment A, p. 41).
OSHA initially discussed some issues surrounding the Vacek et al.
(2011) study in its Supplemental Literature Review (Document ID 1711,
Attachment 1, pp. 2-5). Specifically, OSHA noted that (1) the
cumulative exposure quintiles used in the Vacek et al. (2011) analysis
were higher than the values used in the Attfield and Costello (2004)
analysis; (2) the regression models used in the Vacek et al. (2011)
study exhibited signs of uncontrolled confounding, as workers in the
second lowest cumulative exposure stratum in the models (except for
silicosis) exhibited a lower risk than those in the lowest stratum,
while all outcomes (except NMRD) in the highest exposure stratum showed
a decline in the odds ratio (a measure of the association between
silica exposure and health outcome) compared to the next lower stratum;
and (3) Vacek et al. (2011) found a statistically significant excess of
lung cancer (SMR = 1.37, with almost 100 excess lung cancer deaths) in
the cohort when compared to U.S. white males (Document ID 1486, p.
315). Regarding the excess lung cancer deaths, although they were
unable to obtain information on smoking for many of the cohort members,
Vacek et al. suggested that the elevated SMR for lung cancer was due,
at least in part, to the differences between the smoking habits of the
cohort and reference populations (Document ID 1486, p. 317). OSHA noted
that although the SMR for other NMRD was elevated, there was no
significant SMR elevation for other smoking-associated diseases,
including cancers of the digestive organs, larynx, and bladder, as well
as bronchitis, emphysema, and asthma (Document ID 1711, Attachment 1,
p. 5). Elevated SMRs for these diseases would be expected if workers in
the study population smoked more than those in the reference
population; in fact, for all heart disease, the mortality in the study
population (SMR = 0.89) was statistically significantly lower than the
reference population (Document ID 1486, p. 315). These data do not
support Vacek et al.'s assertion that smoking was responsible for the
increased lung cancer SMR in the cohort. In addition, Davis et al.
(1983) noted that granite shed workers employed during the 1970's
smoked only slightly more than U.S. white males (Document ID 0999, p.
717). OSHA also pointed out that the SMR may have been understated, as
Vacek et al. did not account for a healthy worker effect (HWE).
The ACC did not agree with OSHA's review of the Vacek et al. study,
noting that OSHA "rejects Vacek et al. (2011) on grounds that are
confusing and unfounded" (Document ID 2307, Attachment A, p. 41). The
ACC argued that the quintiles of cumulative exposure used by Vacek et
al. were not higher than typical values for lung cancer, and that OSHA,
in its Supplemental Literature Review, compared the Vacek et al.
quintiles of cumulative exposure for silicosis with the Attfield and
Costello groups used for both silicosis and lung cancer (Document ID
2307, Attachment A, pp. 41-42). OSHA acknowledges this discrepancy and,
given that Vacek et al. used quintiles of cumulative exposure that
differed for each health endpoint, agrees that the quintiles for lung
cancer used by Vacek et al. were not appreciably higher than the
exposure groups used by Attfield and Costello, though the Agency recognizes
that there may be alternative explanations for the patterns observed in
the Vacek et al. data. Regarding uncontrolled confounding, the ACC
stated that "The Vermont granite worker cohort, after all, supposedly is
free of confounding exposures," (Document ID 2307, Attachment A, p. 43
(citing Attfield and Costello, 2004, 0284)). Vacek et al. also pointed out
that although the odds ratios for the second lowest exposure stratums were
lower than those for the lowest categories for each of the diseases,
they were not statistically significantly lower (Document ID 1804, pp.
1-2).
Although OSHA notes that this latter phenomenon, in which the odds
ratio for the second lowest exposure stratum is lower than that for the
lowest stratum, is commonly observed and often attributable to some
form of selection confounding, the Agency recognizes that there may be
alternative explanations for the patterns observed in the Vacek et al.
data. One such explanation for the decreased odds ratios in the highest
exposure group is potential attenuation resulting from a HWE.
The HWE, as defined by Stayner et al. (2003), has two components:
(1) A healthy initial hire effect, in which bias is "introduced by the
initial selection of workers healthy enough to work...and the use
of general population rates for the comparison group, which includes
people who are not healthy enough to work," and (2) a healthy worker
survivor effect, referring "to the tendency of workers with ill health
to drop from the workforce and the effect this dropout may have on
exposure-response relationships in which cumulative exposure is the
measure of interest" (Document ID 1484, p. 318). Thus, the healthy
initial hire effect occurs in the scenario in which the death rate in a
worker group is compared to that in the general population; because the
general population has many people who are sick, the death rate for
workers may be lower, such that a direct comparison of the two death
rates results in a bias. The healthy worker survivor effect occurs in
the scenario in which less healthy workers transfer out of certain jobs
into less labor-intensive jobs due to decreased physical fitness or
illness, or leave the workforce early due to exposure-related illness
prior to the start of follow-up in the study. As a result, the
healthier workers accumulate the highest exposures such that the risk
of disease at higher exposures may appear to be constant or decrease.
OSHA disagrees with the ACC's statement that "the possibility of a
potential HWE in this cohort could not have affected the E-R analyses"
in Vacek et al. (2011) (Document ID 2307, Attachment A, p. 46), and
with the similar statement by study authors Pamela Vacek, Ph.D. and
Peter Callas, Ph.D., both of the University of Vermont, who asserted
that the HWE could not have impacted their exposure-response analyses
"because they were not based on an external reference population"
(Document ID 1804, p. 2). This explanation only considers one component
of the HWE, the healthy initial hire effect. An internal control
analysis, such as that performed by Vacek et al., will generally
minimize the healthy initial hire effect but does not address the
healthy worker survivor effect (see Document ID 1484, p. 318 (Stayner
et al. (2003)). Thus, the statement by the ACC that there could be no
HWE in the internal case control analysis of Vacek et al. (2011) is
incorrect, as it considered only the healthy initial hire effect and
not the healthy worker survivor bias.
In contrast, Attfield and Costello's stated rationale for excluding
the highest exposure group is related to the healthy worker survivor
effect:
We do know that this group is distinctive in entering the cohort
with substantial exposures--83% had worked for 20 years or more in
the high dust levels prevalent prior to controls. They were,
therefore, a highly selected healthy worker group. A further reason
may be that in the days when tuberculosis and silicosis were the
main health concerns in these workers, lung cancer may have been
obscured in this group as a cause of death in some cases" (Document
ID 0284, p. 136).
Support for Attfield and Costello's reasoning is provided by a
study by Applebaum et al. (2007), which re-analyzed the data from the
Attfield and Costello (2004) paper and concluded that there was a
healthy worker survivor effect present (study cited by Vacek et al.,
2009, Document ID 2307, Attachment 6, p. 3). Applebaum et al. (2007)
split the cohort of Vermont granite workers into two groups: (1) Those
that began working before the start of the study follow-up, i.e.,
prevalent hires; and (2) those that began working after the start of
the study follow-up, i.e., incident hires. The rationale for splitting
the cohort into these two groups was to examine if a healthy worker
survivor effect was more likely in the prevalent hire group, as this
group would be affected by workers that were more susceptible to health
effects and left the industry workforce prior to the start of the study
follow-up (Applebaum et al., 2007, pp. 681-682). Using spline models to
examine exposure-response relationships without forcing a particular
form (e.g., linear, linear-quadratic) on the observed data, the authors
found that the inclusion of prevalent hires in the analysis weakened
the association between cumulative silica exposure and lung cancer
because of bias from the healthy worker survivor effect. The bias can
be reduced by including only incident hires, or keeping the date of
hire close to the start of follow-up (Applebaum et al., 2007, pp. 685-
686). An alternative explanation for this trend offered by Applebaum et
al. may be that, assuming that there was more measurement error in the
older data, the prevalent hires had more exposure misclassification
(2007, p. 686); in such a case, however, the inclusion of prevalent
hires would still bias the results towards the null. Given the findings
of the Applebaum et al. (2007) study, OSHA believes that Attfield and
Costello (2004) had good reasons for removing the highest exposure
group, which was composed mostly of prevalent workers (83 percent of
workers in the highest exposure group had worked at least 20 years
prior to the start of the follow-up period) (Document ID 0284, p. 136).
Vacek et al. (2011), on the other hand, excluded 609 workers in the
design of their study cohort due to insufficient information. However,
the majority of the workers excluded from the cohort were incident
hires who began work after 1950 (Document ID 2307, Attachment 6, p. 12;
1486, p. 314). The final Vacek et al. (2011) cohort included 2,851
prevalent hires (began employment before 1950) compared to 4,201
incident hires (began employment in or after 1950) (Document ID 2307,
Attachment 6, p. 12; 1486, p. 314). By composing about 40 percent of
their cohort with prevalent hires and excluding many incident hires,
Vacek et al. (2011) may have introduced additional healthy worker
survivor effect bias into their study. Interestingly, Vacek et al.
described the Applebaum et al. (2007) results in their 2009 report,
stating, "They [Applebaum et al.] found that decreasing the relative
proportion of prevalent to incident hires [in the data used by Attfield
and Costello] resulted in a stronger association between cumulative
silica exposure and lung cancer mortality" (Document ID
2307, Attachment 6, p. 3). Despite their acknowledgement of the
Applebaum et al. (2007) findings, Vacek et al. (2011) did not conduct
any analysis of only the incident hires, or use statistical methods to
better determine the presence and effect of a healthy worker survivor
effect in their study.
The ACC also commented on Vacek et al.'s suggestion that the
elevated SMR observed for lung cancer in the cohort (when compared to a
reference population of U.S. white males) was due to differences in the
smoking habits of the cohort and reference population, which OSHA
criticized in its Supplemental Literature Review (Document ID 1486, p.
317; 1711, Attachment 1, p. 5). The ACC stated, "OSHA suggests that
the lack of complete smoking data for the cohort is a problem and
contends that smoking could not explain the elevated SMR for lung
cancer. This criticism, as Dr. Vacek explains, is overstated, and, in
any event, does not detract from the study's findings regarding the
absence of an association between silica exposure and lung cancer"
(Document ID 2307, Attachment A, pp. 46-47; 1804, p. 2).
Vacek et al. (2011) estimated the relative smoking prevalence in
the cohort to be 1.35 times that in the reference population; using
this estimated relative smoking prevalence, the authors estimated that
"the expected number of lung cancer deaths in the cohort after
adjusting the reference rates for smoking would be 353, yielding a
[non-significant] SMR of 1.02" (Document ID 1486, p. 317). OSHA notes
that this method used by Vacek et al. to adjust the SMR for smoking
neglects the healthy worker survivor effect (i.e., smokers may leave
the workforce sooner than nonsmokers because smoking is a risk factor
for poor health). Absent control for the healthy worker survivor
effect, smoking would (and perhaps did) become a negative confounder
because long duration--high cumulative exposure--workers would tend
toward lower smoking attributes. The method used by Vacek et al. is
also inconsistent with the frequently cited Axelson (1978) method,
which is used to adjust the SMR when the exposed population has a
higher percentage of smokers than the reference population (Checkoway
et al. 1997, Document ID 0326; Chan et al. 2000, 0983). As a result,
Vacek et al. (2011) likely overestimated the confounding effect of
smoking in this cohort.
In addition, as previously noted by OSHA, the SMRs for cancers
largely attributable to smoking, such as those of the buccal cavity and
pharynx (SMR = 1.01), larynx (SMR = 0.99), and esophagus (SMR = 1.15)
were not significant in the Vacek et al. study (Document ID 1486, p.
315; 2307, Attachment 6, p. 14). The SMR of 0.94 for bronchitis,
emphysema, and asthma also was not significant. If smoking were truly
responsible for the highly statistically significant SMR (1.37)
observed for lung cancer, the SMRs for these other diseases should be
significant as well. OSHA likewise notes that other studies have found
that smoking does not have a substantial impact on the association
between crystalline silica exposure and lung cancer mortality (e.g.,
Checkoway et al., 1997, Document ID 0326; Steenland et al., 2001a,
0452, p. 781) and that crystalline silica is a risk factor for lung
cancer independent of smoking (Kachuri et al., 2014, Document ID 3907,
p. 138; Preller et al., 2010, 4055, p. 657).
OSHA is also concerned about some features of the study design and
exposure assessment in Vacek et al. (2011). Regarding the study design,
in their nested case-control analyses, Vacek et al. sorted cases into
risk sets based on year of birth and year of death, and then matched
three controls to each risk set; from the data presented in Table 5 of
the study, the actual number of controls per lung cancer case can be
calculated as 2.64 (Document ID 1486, p. 316). Vacek et al.'s decision
to use such a small number of controls per case was unnecessarily
restrictive, as there were additional cohort members who could have
been used as controls for the lung cancer deaths. Typically, if the
relevant information is available, four or more (or all eligible)
controls are used per case to increase study power to detect an
association. OSHA notes that Steenland et al. (2001a), in their nested
case-control pooled analysis, used 100 controls per case (Document ID
0452, p. 777).
In addition, Vacek et al. stated that for the categorical analysis,
cut points on cumulative exposure were based on quintiles of the
combined distribution for cases and controls (Document ID 1486, p.
314). Therefore, there should be an approximately equal total number of
subjects (cases plus controls) in each group (or quintile). OSHA's
examination of Table 5 in the Vacek et al. (2011) study shows that
there is an approximately equal distribution of subjects for all
endpoints except lung cancer; for example, the silicosis groups each
had 43-44 subjects, the NMRD groups each had 125-130 subjects, the
kidney cancer groups each had 22-23 subjects, and the kidney disease
groups each had 25 subjects. However, the lung cancer groups, ranging
from the lowest to the highest exposure, had 325, 232, 297, 241, and
202 subjects (Document ID 1486, p. 316). OSHA could find no explanation
for this discrepancy in the text of the Vacek et al. (2011) study, and
questions how the lung cancer groups were composed.
With respect to the different job exposure matrices, OSHA has
reason to believe that the exposure data reported in the Attfield and
Costello study are more accurate than the data Vacek et al. used. OSHA
is particularly concerned that Vacek et al.'s pre-1940 exposure
estimate of 150 [micro]g/m\3\ for one job (channel bar operator) was
much lower than Attfield and Costello's estimate, from the Davis et al.
(1983) matrix, of 1070 [micro]g/m\3\ (Document ID 1486, p. 313; 0284,
p. 131). As NIOSH observed in its post-hearing comments, changing the
exposure estimate for channel bar operators could have "major
consequences" on the exposure-response analysis, as the job occurred
frequently (Document ID 4233, p. 22). NIOSH then pointed out that the
Attfield and Costello (2004) exposure estimate for channel bar
operators was based on multiple exposure measurements conducted by
Davis et al. (1983), whereas Vacek et al. based their exposure estimate
"on only three dust measurements" in which "only wet drilling was
used. Thus, their study used not only very limited sampling data but
also values that were biased towards low levels, since the samples were
taken when water was being used to control dust," a practice that was
not typically used for this occupation at the time (Document ID 4233,
p. 22). In fact, photographs from Hosey et al. (1957) showed channel
bar drilling in 1936 and 1937 with and without dust control; the
caption for the photo without dust control states that the "operator
in background is barely visible through dust cloud" (Document ID 4233,
p. 24, citing 3998, Attachment 14b). As NIOSH explained,
If there is a true [linear] relationship between exposure to
silica dust and lung cancer mortality, classifying highly exposed
workers incorrectly as low-exposed shifts the elevated risks to the
low exposure range. The impact is to spuriously elevate risks at low
exposures and lower them at high exposures, resulting in the
exposure-response trend being flattened or even obscured.
Ultimately, the true relationship may not be evident, or if it is,
may be attenuated (Document ID 4233, p. 22, n. 1).
Vacek et al. reported in their study that they conducted a
sensitivity analysis that did not change the exposure-response
relationship between silica exposure and lung cancer risk,
even when Attfield and Costello's pre-1940 exposure estimates were used
for channel bar operators (Document ID 2340, pp. 317-318; 2307,
Attachment 6, p. 31). Part of the problem may be the way that channel
bar operators were defined by Vacek et al. As noted by NIOSH, "Leyner
driller and channel bar operator or driller are synonyms" (Document ID
4233, p. 22, n. 3). Attfield and Costello defined channel bar operators
in that way, with a pre-1940 exposure estimate of 1070 [micro]g/m\3\
(Document ID 0284, p. 131). Vacek et al., on the contrary, assigned
channel bar operators to a category called "channel bar (wet)" and
assigned a pre-1940 exposure estimate of 150 [micro]g/m\3\ (Document ID
2307, Attachment 6, Appendix B, pp. 7, 15). They included Leyner
drillers under a general category called "driller" with a pre-1940
exposure estimate of 1070 [micro]g/m\3\ (Document ID 2307, Attachment
6, Appendix B, pp. 7, 15). Included in the Vacek et al. (2009) category
of "drillers" were plug drillers (Document ID 2307, Attachment 6,
Appendix B, p. 15); OSHA notes that Attfield and Costello used a lower
pre-1940 exposure estimate of 650 [micro]g/m\3\ for plug drillers, as
defined by Davis et al. (1983). OSHA believes that Vacek et al.
underestimated the exposures of some channel bar operators, and
overestimated the exposures of plug drillers, which may have
contributed to the lack of association, and that the categorization
used by Attfield and Costello, with the synonymous channel bar
operators and Leyner drillers in one category, and plug drillers in a
separate category, was more appropriate. Thus, even in Vacek et al's
sensitivity analysis, in which they used Attfield and Costello's
exposure estimate of 1070 [micro]g/m\3\ for channel bar operators and
drillers, the plug drillers would still have had a higher exposure
estimate (1070 [micro]g/m\3\ versus Attfield and Costello's 650
[micro]g/m\3\), making the analysis different from that of Attfield and
Costello.
For the reasons discussed herein, OSHA has decided not to reject
the Attfield and Costello (2004) study in favor of the Vacek et al.
(2011) study as a basis for risk assessment. OSHA maintains that it has
performed an objective analysis of the Attfield and Costello (2004) and
Vacek et al. (2011) studies. OSHA agrees with some of the ACC's
criticisms regarding the Agency's initial evaluation of the exposure
groupings and confounding in the Vacek et al. (2011) study. OSHA is
concerned, however, as discussed above, about several aspects of Vacek
et al. (2011), including a potential bias from the healthy worker
survivor effect, which was shown to exist in this cohort (see Applebaum
et al., 2007, cited in Document ID 2307, Attachment 6, p. 3), as well
as about job categorization that may have resulted in exposure
misclassification for certain job categories (e.g., the synonymous
channel bar operators and Leyner drillers). Despite its concerns with
the Vacek et al. study, OSHA acknowledges that comprehensive studies,
such as Attfield and Costello (2004) and Vacek et al. (2011), in the
Vermont granite industry have shown conflicting results with respect to
lung cancer mortality (Document ID 0284; 1486). As discussed earlier,
conflicting results are often observed in epidemiological studies due
to differences in study designs, analytical methods, exposure
assessments, populations, and other factors. In addition, the exposure-
response relationship between silica and lung cancer may be easily
obscured by bias, as crystalline silica is a comparably weaker
carcinogen (i.e., the increase in risk per unit exposure is smaller)
than other well-studied, more potent carcinogens such as hexavalent
chromium (Steenland et al., 2001, Document ID 0452, p. 781). Although
OSHA believes that the Attfield and Costello (2004) study is the most
appropriate Vermont granite study to use in its QRA, the Agency notes
that, even in the absence of the Attfield and Costello (2004) study,
the risk estimates for lung cancer mortality based on other studies
still provide substantial evidence that respirable crystalline silica
poses a significant risk of serious health conditions to exposed
workers.
4. Comments on Specific Studies Relied Upon by OSHA in Its QRA
a. Attfield and Costello (2004)
As stated above, OSHA disagrees with the ACC's contention that
Vacek et al. provides a more reliable scientific basis for estimating
risk than Attfield and Costello. While it is true that the final risk
estimate (54 deaths per 1,000 workers) derived from the Attfield and
Costello study for an exposure level of 100 [micro]g/m\3\ is the
highest when compared to the other studies, it is not true that the
final risk estimate (22 deaths per 1,000 workers) derived from the
Attfield and Costello study is the highest for the final rule's PEL of
50 [micro]g/m\3\. In fact, it is within the range of risk estimates
derived from the ToxaChemica (2004) pooled analysis of 16 to 23 deaths
per 1,000 workers at the final PEL. Thus OSHA has decided to retain its
reliance on the Attfield and Costello (2004) study and, again, notes
that, even without the Attfield and Costello (2004) study, all of the
other studies in the Final QRA demonstrate a clearly significant risk
of lung cancer mortality (11 to 54 deaths per 1,000 workers) at an
exposure level of 100 [micro]g/m\3\, with a reduced, albeit still
significant, risk (5 to 23 deaths per 1,000 workers) at an exposure
level of 50 [micro]g/m\3\ (see Table VI-1 in Section VI, Final
Quantitative Risk Assessment and Significance of Risk). Excluding
Attfield and Costello (2004), in other words, would not change OSHA's
final conclusion regarding the risk of death from lung cancer.
b. Miller and MacCalman (2009)
According to the ACC, OSHA's risk estimates based on the Miller and
MacCalman (2009, Document ID 1306) study are "more credible than the
others--because [the study] involved a very large cohort and was of
higher quality in terms of design, conduct, and detail of exposure
measurements," and also adjusted for smoking histories (Document ID
2307, Attachment A, p. 73). Although the risk estimates generated from
the Miller and MacCalman data were the lowest of the lung cancer
mortality estimates, the ACC next asserted that they were biased
upwards for several reasons. First, the ACC stated that exposure
information was lacking for cohort members after the mines closed in
the mid-1980's, and quoted OSHA as stating, "Not accounting for this
exposure, if there were any, would bias the risk estimates upwards"
(Document ID 2307, Attachment A, p. 74 (quoting 1711, p. 289)). OSHA,
however, does not believe there to have been additional substantial
quartz exposures. As the study authors wrote, "Because of the steep
decline of the British coal industry, the opportunities for further
extensive coal mine exposure were vanishingly small" (Document ID
1306, p. 11). Thus OSHA believes it to be unlikely that the risk
estimates are biased upwards to any meaningful degree based on lack of
exposure information at the end of the study period.
The ACC also stated that the unrestricted smoking of cohort members
after the closure of the mines would have resulted in risk estimates
that were biased upwards (Document ID 2307, Attachment A, p. 74). OSHA
has no reason to believe, nor did the ACC submit any evidence in
support of its contention, that unrestricted smoking occurred, however,
and notes that the authors stated that the period after the mines
closed was one of "greater anti-smoking health promotion campaigns"
(Document ID 1306, p. 11).
Finally, the ACC noted that Miller and MacCalman did not adjust
significance levels for the multiple comparisons bias with respect to
lag selection that Dr. Cox alleged affected their study (Document ID
2307, Attachment A, p. 74). Dr. Cox claimed that trying multiple
comparisons of alternative approaches, such as different lag periods,
and then selecting a final choice based on the results of these
multiple comparisons, leads to a multiple comparisons bias that could
result in false-positive associations (Document ID 2307, Attachment 4,
p. 28; see Section V.J, Comments and Responses Concerning Biases in Key
Studies). He argued that the authors should have reduced the
significance level (typically p = 0.05) at which a result is considered
to be significant. "Lag" refers to the exclusion of the more recent
years of exposure (e.g., 10-year lag, 15-year lag) to account for the
fact that diseases like cancer often have a long latency period (i.e.,
that the cancer may not be detected until years after the initiating
exposure, and exposures experienced shortly before detection probably
did not contribute to the development of disease). "Lag selection,"
therefore, refers to the choice of an appropriate lag period. As
addressed later in the Section V.J, Comments and Responses Concerning
Biases in Key Studies, OSHA does not necessarily believe such an
adjustment of significance levels to be appropriate, based upon the
testimony of Mr. Park of NIOSH, nor is it typically performed in the
occupational epidemiology literature (Document ID 3579, Tr. 151-152).
Similarly, the ACC stated that the confidence intervals are overly
narrow because they ignore model uncertainty, and that multiple
imputation of uncertain exposure values should have been performed
(Document ID 2307, Attachment A, p. 75). OSHA rejects this assertion on
the grounds that the authors used detailed exposure estimates that the
ACC recognized raised the credibility of the study; the ACC wrote,
regarding the study, "it involved a very large cohort and was of
higher quality in terms of design, conduct, and detail of exposure
measurements" (Document ID 2307, Attachment A, p. 73). Lastly, the ACC
argued that an exposure threshold should have been examined (Document
ID 2307, Attachment A, p. 75). OSHA discusses at length this issue of
thresholds, and the difficulty in ruling them in or out at low
exposures, in Section V.I, Comments and Responses Concerning Thresholds
for Silica-Related Diseases.
In summary, OSHA notes that the ACC has not provided any non-
speculative evidence to support its claims that the risk estimates
derived from the Miller and MacCalman (2009) study are biased upwards.
As stated in the Review of Health Effects Literature and Preliminary
QRA, and acknowledged by the ACC (Document ID 2307, p. 73), OSHA
believes these risk estimates to be very credible, as the study was
based on well-defined union membership rolls with good reporting, had
over 17,000 participants with nearly 30 years of follow-up, and had
detailed exposure measurements of both dust and quartz, as well as
smoking histories (Document ID 1711, pp. 288-289).
c. Steenland (2001a) and ToxaChemica (2004)
OSHA also received several comments on the ToxaChemica (2004,
Document ID 0469) analysis, which was based on the Steenland et al.
(2001a, Document ID 0452) pooled analysis. First, the ACC claimed that
there is significant heterogeneity in the exposure-response
coefficients, derived from the individual studies. Because the risk
estimates based on these coefficients differ by almost two orders of
magnitude, the ACC suggested that these models are misspecified for the
data (Document ID 2307, Attachment A, pp. 75-76). Essentially, the ACC
claimed that the exposure-response coefficients differ too much among
the individual studies, and asserted that it is therefore inappropriate
to use the pooled models. Dr. Cox wrote: "Steenland et al. did not
address the heterogeneity, but artificially suppressed it by
unjustifiably applying a log transformation. This is not a valid
statistical approach for exposure estimates with substantial estimation
errors" (Document ID 2307, Attachment 4, p. 75). During the public
hearing, however, Dr. Steenland explained to OSHA's satisfaction how
the data in his study was transformed, using accepted statistical
methods. Specifically, referring to his use of a log transformation to
address the heterogeneity, Dr. Steenland testified:
[I]t reduces the effect of the very highest exposures being able
to drive an exposure-response curve because those exposures are
often [skewed] way out--skewed to the right, because occupational
exposure data is often log normal. With some very high exposures,
they are sort of extreme, and that can drive your exposure-response
curve. And you take the log, it pulls them in, and so therefore
gives less influence to those high data points. And I think those
high data points are often measured with more error (Document ID
3580, Tr. 1265-1266).
OSHA finds this testimony to be persuasive and, therefore, believes
that Dr. Steenland's use of a log transformation to address the
heterogeneity was appropriate. The log transformation also permits a
better model fit when attenuation of the response is observed at high
cumulative exposures.
Dr. Morfeld commented that Steenland et al. did not take into
account smoking, which could explain the observed excess lung cancer of
20 percent (SMR = 1.2). Dr. Morfeld stated, "Thus, lung cancer excess
risks were demonstrated only under rather high occupational exposures
to RCS dust, and, even then, an upward bias due to smoking and a
necessary intermediate role for silicosis could not be ruled out"
(Document ID 2307, Attachment 2, p. 10). Dr. Steenland addressed the
concern about a potential smoking bias during his testimony:
We concluded that this positive exposure response was not likely
due to different smoking habits between high exposed and low exposed
workers. And the reason we did that was twofold. First, workers tend
to smoke similar amounts regardless of their exposure level in
general. We often worry about comparing workers to the general
population because workers tend to smoke more than the general
population. But, in internal analyses, we don't have this problem
very often. When we have smoking data, we see that it is not related
to exposure, so a priori we don't think it is likely to be a strong
confounder in internal analyses. Secondly, a number of the studies
we used in our pool[ed] cohort had smoking data, either for the
whole cohort or partially. And when they took that into account,
their results did not change. In fact, they also found that smoking
was not related to exposure in their studies, which means that it
won't affect the exposure-disease relationship because if it is
going to do that, it has to differ between the high exposed and the
low exposed, and it generally did not (Document ID 3580, Tr. 1227-
1228).
In addition, Brown and Rushton (2009), in their review article
submitted to the rulemaking record by Dr. Morfeld, appeared to agree
with Dr. Steenland, stating, "This [Steenland et al.] internal
analysis removed the possibility of confounding by smoking" (Document
ID 3573, Attachment 5, p. 150). Thus, OSHA rejects Dr. Morfeld's
assessment that the risk estimates may be biased upwards due to
smoking.
The ACC also commented that exposure misclassification due to
uncertain exposure estimates in Steenland's pooled cohort could have
created the appearance of a monotonic relationship, in which the
response increases with the exposure, even if the true response was not
monotonic (Document ID 2307, Attachment A, p. 76). The ACC, along with
Dr. Borak (representing the U.S. Chamber of Commerce) and others,
likewise cited OSHA's statement from the Review of Health Effects
Literature and Preliminary QRA, in which the Agency acknowledged that
uncertainty in the exposure estimates that underlie each of the 10
studies in the pooled analysis was likely to represent one of the most
important sources of uncertainty in the risk estimates (Document ID
1711, p. 292; 2376, p. 16). Dr. Borak also quoted Mannetje et al.
(2002), who developed quantitative exposure data for the pooled
analysis, as stating, "While some measurement error certainly occurred
in our estimates, a categorical analysis based on broad exposure groups
should not be much affected by the resulting level of
misclassification" (Document ID 2376, p. 17, quoting 1090, p. 84).
From this statement, Dr. Borak concluded that the researchers
themselves believed the data were only adequate for "categorical
analyses which might lead to qualitative conclusions" (Document ID
2376, p. 17).
OSHA disagrees with Dr. Borak's interpretation of the Mannetje et
al. statement, as categorical analyses are typically quantitative in
nature, with the data being used to draw quantitative conclusions.
However, OSHA recognized the possibility for uncertainty in the
exposure estimates, and it is for this reason that OSHA commissioned a
quantitative analysis of uncertainty in Steenland's pooled study
(ToxaChemica, 2004, Document ID 0469). This analysis suggested that
exposure misclassification had little effect on the pooled exposure
coefficient (and the variance around that estimate) for the lung cancer
risk model (Document ID 1711, pp. 313-314). Given this analysis, OSHA
also disagrees with the ACC's statement that "it is virtually certain
that substantial exposure estimation error infused the pooled analysis,
resulting in exposure misclassification that would create a false
appearance of a monotonically increasing exposure-response even where
none exists" (Document ID 2307, Attachment A, p. 78). OSHA notes that
this statement is not supported with any evidence from the Steenland et
al. (2001) study. In addition, as discussed at length in Section V.K,
Comments and Responses Concerning Exposure Estimation Error and
ToxaChemica's Uncertainty Analysis, exposure estimation error can also
bias results towards the null (weaken or obscure the exposure-response
relationship) (Document ID 3580, Tr. 1266-67; 3576, Tr. 358-359; 3574,
p. 21). Other criticisms from the ACC concerning alleged modeling
errors and biases in the Steenland study and the alleged threshold for
the health effects of silica exposure are discussed generally in
Section V.J, Comments and Responses Concerning Biases in Key Studies,
and Section V.I, Comments and Responses Concerning Thresholds for
Silica-Related Diseases. Dr. Cox's and Dr. Morfeld's criticisms of the
uncertainty analysis performed by Toxachemica are addressed in Section
V.K, Comments and Responses Concerning Exposure Estimation Error and
ToxaChemica's Uncertainty Analysis. For the reasons stated in those
sections, OSHA is unpersuaded by these criticisms.
The ACC concluded:
For all these reasons, the pooled analysis by Steenland et al.
(2001) does not yield credible or reliable estimates of silica-
related lung cancer risk. But, even if risk estimates based on
Steenland et al. (2001) were not so problematic, that study would
not demonstrate that reducing the PEL from 0.1 mg/m\3\ [100
[micro]g/m\3\] to 0.05 mg/m\3\ [50 [micro]g/m\3\] will result in a
substantial reduction in the risk of lung cancer (Document ID 2307,
Attachment A, p. 81).
The ACC then discussed the ToxaChemica report (2004), which the ACC
claimed shows that "under the spline model (which the authors prefer
over the log cumulative model because of biological plausibility)"
reducing the PEL from 100 [micro]g/m\3\ to 50 [micro]g/m\3\ would
negligibly reduce the excess risk of lung cancer mortality from 0.017
(17/1,000) to 0.016 (16/1,000), "risk values that are
indistinguishable given the overlapping confidence limits of the two
estimates" (Document ID 2307, Attachment A, p. 81). In addition, the
ACC noted that the excess risk at 150 [micro]g/m\3\ and 250 [micro]g/
m\3\ in the spline model is the same as the excess risk at 50 [micro]g/
m\3\, while that at 200 [micro]g/m\3\ is lower. "Estimates of lung
cancer risk in the neighborhood of the current general industry PEL are
hugely uncertain--with the data suggesting that a greater reduction in
lung cancer risk could be achieved by doubling the PEL to 200 [micro]g/
m\3\ than by cutting it in half to a level of 50 [micro]g/m\3\"
(Document ID 2307, Attachment A, pp. 81-82).
OSHA notes that these risk estimates cited by the ACC were the
original estimates for the spline model provided to OSHA by ToxaChemica
in its 2004 report (Document ID 0469). These are not the risk estimates
used by OSHA. Instead, to estimate the risks published in this final
rule, the Agency used the exposure-response coefficients from the study
in an updated life table analysis using background all-cause mortality
and lung cancer mortality rates from 2006 and 2011, respectively. The
risk estimates using the 2011 background data are the most updated
numbers with which to make the comparisons ACC has suggested. With the
2011 background data, the estimated excess risk is 20 deaths per 1,000
workers at 100 [micro]g/m\3\, and 16 deaths per 1,000 workers at 50
[micro]g/m\3\, a reduction of 4 deaths. OSHA's estimated excess risk at
250 [micro]g/m\3\ is 24 deaths per 1,000 workers, an increase in 8
deaths when compared to 50 [micro]g/m\3\. Thus it is not the case, as
ACC suggested, that increasing the PEL would cause a reduction in lung
cancer mortality risk.
In addition, the linear spline model employed by Steenland et al.
(2001) was only one of three models used by OSHA to estimate
quantitative risks from the pooled analysis. OSHA also used the log-
linear model with log cumulative exposure as well as the linear model
with log cumulative exposure (see Section VI, Final Quantitative Risk
Assessment and Significance of Risk). OSHA notes that all three models
indicated a reduction in risk when comparing an exposure level of 100
[micro]g/m\3\ to 50 [micro]g/m\3\.
In summary, OSHA disagrees with the ACC's assertion that the
Steenland et al. pooled analysis does not yield credible risk estimates
for lung cancer mortality. Dr. Morfeld's assertion that the risk
estimates were biased upwards due to smoking is quite unlikely to be
true, given that the study was an internal (worker to worker) analysis.
The ACC's claim that exposure estimation error resulted in false
exposure-response relationships was not supported by any actual data;
as discussed in Section V.K, Comments and Responses Concerning Exposure
Estimation Error and ToxaChemica's Uncertainty Analysis, exposure
estimation error can also bias results towards the null (weaken or
obscure the exposure-response relationship) (Document ID 3580, Tr.
1266-67; 3576, Tr. 358-359; 3574, p. 21). For these reasons, OSHA
rejects the ACC's claims that the Steenland study of lung cancer
mortality does not yield credible risk estimates. Rather, based upon
its review, OSHA believes this pooled analysis to be of high quality.
As Dr. Steenland testified during the informal public hearings, this
pooled analysis, with its more than 60,000 workers and 1,000 lung
cancer deaths, involved "a rich dataset with high statistical power to
see anything, if there was anything to see" (Document ID 3580, Tr.
1227). In fact, OSHA believes the Steenland et al. (2001a) study to be
among the best available studies in the peer-reviewed literature on the
topic of silica exposure and its relationship to lung cancer mortality.
d. Rice et al. (2001)
The ACC also commented on the Rice et al. (2001, Document ID 1118)
study of diatomaceous earth workers, which found a significant risk of
lung cancer mortality that increased with cumulative silica exposure in
a cohort of diatomaceous earth workers. The ACC claimed that it had a
high likelihood of exposure misclassification. Dr. Cox contended that
the practice of "[a]ssigning each worker a single estimated cumulative
exposure based on estimated mean values produces biased results and
artificially narrow confidence intervals (and hence excess false-
positive associations)" (Document ID 2307, Attachment 4, p. 76). OSHA
notes that Rice et al. (2001) described the exposure estimation
procedure in their paper. There were more than 6,000 measurements of
dust exposure taken from 1948-1988; particle count data were converted
to gravimetric data using linear regression modeling. Cumulative
exposures to respirable crystalline silica were then estimated for each
worker using detailed employment records (Document ID 1118, p. 39).
OSHA concludes it is highly unlikely that the exposure estimates are
biased to such an extent, as Dr. Cox suggests, that they would produce
false-positive associations.
The ACC also noted that the mean crystalline silica exposure in the
diatomaceous earth worker cohort was 290 [mu]g/m\3\, approximately
three times the former PEL for general industry (Document ID 2307,
Attachment A, p. 83). OSHA, however, believes that the cumulative
respirable crystalline silica dust concentration is the metric of
concern here, as that is what was used in the regression models. The
mean cumulative respirable crystalline silica dust concentration in the
study was 2.16 mg/m\3\-yrs, which is a very realistic cumulative
exposure for many workers (Document ID 1118, p. 39).
The ACC also stated that the results of the Rice study were
confounded by smoking and possibly asbestos exposure (Document ID 2307,
Attachment A, p. 83). OSHA previously addressed the possible
confounding in this cohort in its Review of Health Effects Literature
and Preliminary QRA (Document ID 1711, pp. 139-143). Rice et al. (2001)
used the same cohort originally reported on by Checkoway et al. (1993,
Document ID 0324; 1996, 0325; 1997, 0326). The Rice study discussed the
smoking confounding analysis performed by Checkoway et al. (1997), in
which the Axelson method (1978) was used to make a worst case estimate
(assuming 20 times greater lung cancer risk in smokers compared to non-
smokers) and indirectly adjust the relative risk (RR) estimates for
lung cancer for differences in smoking rates (Document ID 1118, pp. 40-
41). With exposures in the Checkoway study lagged 15 years to account
for the latency period, the worst case effect was to reduce the RR for
lung cancer in the highest exposure group from 2.15 to 1.67. Checkoway
et al. concluded that the association between respirable silica
exposure and lung cancer was unlikely to be confounded by cigarette
exposure (Document ID 0326, pp. 684, 687). Regarding confounding by
asbestos exposure, Rice et al. (2001) stated:
Checkoway et al. found no evidence that exposure to asbestos
accounted for the observed association between mortality from lung
cancer and cumulative exposure to silica. Our analyses of their data
also found no evidence of confounding by asbestos in the Poisson
regression or Cox's proportional hazards models regardless of lag
period; therefore, exposure to asbestos was not included in the
models presented in this paper (Document ID 1118, p. 41).
Based upon these analyses, OSHA rejects the ACC's unsupported
assertion that the results of Rice et al. (2001) were confounded by
smoking and asbestos exposure.
Lastly, Dr. Cox asserted that there were several biases in Rice et
al. (2001), including multiple-testing bias from testing multiple lag
periods, exposure groupings, and model forms; model specification bias;
and a lack of model diagnostics (Document ID 2307, Attachment 4, pp.
63-64, 77). OSHA addressed these issues generally in Section V.J,
Comments and Responses Concerning Biases in Key Studies, and rejects
these assertions for the same reasons. OSHA also discussed regression
diagnostics at length in the same section. In summary, despite the
criticisms directed at the Rice et al. study by the ACC, OSHA continues
to believe that the quantitative exposure-response analysis by Rice et
al. (2001) is of high quality and appropriate for inclusion in the QRA
(Document ID 1711, p. 143).
e. Hughes et al. (2001)
The ACC, through the comments of Dr. Cox, presented a similar
critique of the study of North American industrial sand workers by
Hughes et al. (2001, Document ID 1060). This study found a
statistically significant association (increased odds ratios) between
lung cancer mortality and cumulative silica exposure as well as average
silica concentration (Document ID 1060). In this study, according to
Dr. Cox, "The selected model form guarantees a monotonic exposure-
response relation, independent of the data. Model uncertainty and
errors in exposure estimates have both been ignored, so the slope
estimate from Hughes et al. (2001), as well as the resulting excess
risk estimates, are likely to be biased and erroneous" (Document ID
2307, Attachment 4, p. 85). The ACC also noted that this cohort had
incomplete smoking information, with the proportion of "ever smokers"
significantly higher in cases than in controls. In addition, the ACC
asserted that asbestos exposure may have also occurred, as three death
certificates listed mesothelioma as the cause of death (Document ID
2307, Attachment A, pp. 85-86).
OSHA discussed the Hughes et al. (2001, Document ID 1060) study in
its Review of Health Effects Literature and Preliminary QRA,
highlighting as strengths the individual job, exposure, and smoking
histories that were available (Document ID 1711, p. 285). Exposure
levels over time were estimated via a job exposure matrix constructed
by Rando et al. (2001, Document ID 0415) utilizing substantial exposure
data, including 14,249 respirable dust and silica samples taken from
1974 to 1998 in nine plants (Document ID 1711, pp. 88, 124-128; 1060,
202). Smoking data were collected from medical records supplemented by
information from next of kin or living subjects for 91 percent of cases
and controls (Document ID 1060, p. 202). OSHA believes these smoking
histories allowed the authors to adequately control for confounding by
smoking in their analyses. Regarding the three death certificates
listing mesothelioma, McDonald et al. (2001) explained that two were
for workers not included in the case/control study because they were
hired at or after age 40 with less than 10 years of work time; the
third was for a worker hired at age 19 who then accumulated 32 years of
experience in maintenance jobs (Document ID 1091, p. 195). As such,
OSHA does not believe it likely that asbestos exposure was a large
source of confounding in typical industrial sand operations in this
study. OSHA also notes that the positive findings of this study were
consistent with those of other studies of workers in this cohort,
including Steenland and Sanderson (2001, Document ID 0455) and McDonald
et al. (2005, Document ID 1092).
The ACC also noted that there was no consistent correlation in
Hughes et al. (2001) between employment duration and lung cancer risk
(Document ID 2307, Attachment A, p. 86), with Dr. Cox suggesting that
model specification error was to blame (Document ID 2307, Attachment 4, p. 86).
OSHA believes that cumulative exposure is a more appropriate metric
for determining risk than is duration of exposure because the
cumulative exposure metric considers both the duration and intensity
of exposure. For example, some workers may have been employed for a
very long duration with low exposures, whereas others may have
been employed for a short duration but with high exposures;
both groups could have similar cumulative exposures.
In summary, OSHA considers the Hughes et al. (2001) study to be of
high enough quality to provide risk estimates for excess lung cancer
from silica exposure, as the study is unlikely to be substantially
confounded. For these reasons, the Agency finds the assertion that the
risk estimates based on this study are erroneous to be unconvincing.
Overall, regarding all of the studies upon which OSHA relied in its
Preliminary QRA, the ACC concluded, "In sum, none of the studies on
which OSHA relies is inconsistent with a concentration threshold above
100 [mu]g/m\3\ for any risk of silica-related lung cancer; none
demonstrates an increased lung cancer risk in the absence of silicosis;
and none provides a sound basis for estimating lung cancer risks at RCS
[respirable crystalline silica] exposure levels of 100 [mu]g/m\3\ and
below" (Document ID 2307, Attachment A, p. 87).
OSHA is not persuaded that the evidence presented by the ACC
supports these conclusions. On the contrary, as OSHA discussed in the
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases, demonstrating the absence of a threshold is not a
feasible scientific pursuit, and some models produce threshold
estimates well below the PELs. Similarly, the ACC has not put forward
any study that has proven that silicosis must be a precursor for lung
cancer and, as discussed in Section V.H, Mechanisms of Silica-Induced
Adverse Health Effects, some studies have shown genotoxic mechanisms by
which exposure to crystalline silica may lead to lung cancer. The
strong epidemiological evidence for carcinogenicity, supported by
evidence from experimental animal and mechanistic studies, allowed IARC
to conclude on multiple occasions that respirable crystalline silica is
a Group I carcinogen. OSHA places great weight on this conclusion given
IARC's authority and standing in the international scientific
community. In addition, all of the lung cancer studies relied upon by
OSHA used models that allow for the estimation of lung cancer risks at
crystalline silica exposure levels of 100 [mu]g/m\3\ and below. OSHA
believes these studies (Steenland et al., 2001a, Document ID 0452, as
re-analyzed in ToxaChemica, 2004, 0469; Rice et al., 2001, 1118;
Attfield and Costello, 2004, 0284; Hughes et al., 2001, 1060; and
Miller and MacCalman, 2009, 1306) are of high quality and contain well-
supported findings. Thus, OSHA continues to rely upon these studies for
deriving quantitative risk estimates in its QRA and continues to
believe that workers exposed to respirable crystalline silica at levels
at or near the previous and new PELs are faced with a significant risk
of dying from lung cancer. As such, the Agency believes it would be
irresponsible as a scientific matter, and inconsistent with its
statutory obligations to issue standards based on the best available
evidence after conducting an extensive rulemaking, to retain the
regulatory status quo.
G. Comments and Responses Concerning Renal Disease Mortality
OSHA estimated quantitative risks for renal disease mortality
(Document ID 1711, pp. 314-316) using data from a pooled analysis of
renal disease, conducted by Steenland et al. (2002a, Document ID 0448).
As illustrated in Table VI-1, the lifetime renal disease mortality risk
estimate for 45 years of exposure to the previous general industry PEL
(100 [mu]g/m\3\ respirable crystalline silica) is 39 deaths per 1,000
workers. However, for the final PEL (50 [mu]g/m\3\), it is 32 deaths
per 1,000 workers. Although OSHA acknowledges that there are
considerably less data for renal disease mortality, and thus the risk
findings based on them are less robust than those for silicosis, lung
cancer, and non-malignant respiratory disease (NMRD) mortality, the
Agency believes the renal disease risk findings are based on credible
data. Indeed, the Steenland et al. pooled analysis had a large number
of workers from three cohorts with sufficient exposure data, and
exposure matrices for the three cohorts had been used in previous
studies that showed positive exposure-response trends for silicosis
morbidity or mortality, thus tending to validate the underlying
exposure and work history data (see Document ID 1711, pp. 215-216).
Nevertheless, OSHA received comments that were critical of its risk
estimates for renal disease mortality. Based upon its review of the
best available evidence, OSHA finds that these comments do not alter
its overall conclusions on renal disease mortality. In addition, OSHA
notes that even if the risk of renal disease mortality is discounted,
there would remain clearly significant risks of lung cancer mortality,
silicosis and NMRD mortality, and silicosis morbidity, with more robust
risk estimates based upon a larger amount of data from numerous studies
(see Table VI-1).
OSHA received several comments from the ACC regarding the Agency's
quantitative risk estimates for renal disease mortality. Specifically,
the ACC argued that: (1) The pooled study (Steenland et al., 2002a,
Document ID 0448) that OSHA relied upon did not provide sufficient data
to estimate quantitative risks; (2) the individual studies included in
the pooled study had several limitations; and (3) most epidemiological
studies have not demonstrated a statistically significant association
between silica exposure and renal disease mortality (Document ID 2307,
Attachment A, pp. 139-157; 4209, pp. 92-96). As explained below, and as
stated above, although the Agency acknowledges there is greater
uncertainty in the risk estimates related to renal disease than other
silica-related diseases, the best available evidence is of sufficient
quality to quantify the risk of renal disease in the final risk
assessment.
1. Pooled Study
Some commenters expressed concern about the Steenland et al.
(2002a, Document ID 0448) pooled study of renal disease mortality,
which OSHA and its contractor, ToxaChemica, used to calculate
quantitative risk estimates. Specifically, the ACC questioned why the
analysis only used three studies (Homestake, North Dakota gold miners,
Steenland and Brown, 1995a, Document ID 0450; U.S. industrial sand
workers, Steenland et al., 2001b, Document ID 0456; Vermont granite
workers, Costello and Graham, 1988, Document ID 0991) out of the ten
originally used in the pooled study of lung cancer mortality (Steenland
et al., 2001a, Document ID 0452). Peter Morfeld, Dr. rer. medic.,
representing the ACC, wrote in his written testimony that although
Steenland et al. (2002a, Document ID 0448) indicated that the three
studies were selected because they were the only ones to have
information on multiple cause mortality, all 10 studies had information
on renal disease as an underlying cause of death (Document ID 2308,
Attachment 4, pp. 24-25). Since ToxaChemica focused on underlying cause
results in their discussion, Dr. Morfeld argued that not having used
all 10 studies in the pooled analysis "raises a suspicion of study
selection bias" (Document ID 2308, Attachment 4, pp. 24-25).
OSHA finds this assertion of study selection bias by the ACC and
Dr. Morfeld to be unpersuasive because Steenland et al.'s explanation
(2002a) for including only three studies in the pooled analysis was
sound. The authors reported in their pooled study that both underlying
cause and multiple cause mortality were available for only three
cohorts of silica-exposed workers, and "multiple cause (any mention on
the death certificate) was of particular interest because renal disease
is often listed on death certificates without being the underlying
cause" (Document ID 0448, p. 5). The authors likewise cited a study
(Steenland et al., 1992), indicating that the ratio of chronic renal
disease mortality shown anywhere on a U.S. death certificate versus
being shown as an underlying cause is 4.75 (Document ID 0453, Table 2,
pp. 860-861). Indeed, in their pooled analysis of renal disease
mortality, Steenland et al. noted that there were 51 renal disease
deaths when using underlying cause, but 204 when using multiple cause
mortality (Document ID 0448, p. 5). As renal disease is a serious
disabling disease, the use of multiple cause mortality gives a much
better sense of the burden of excess disease than does the use of
underlying cause of death as an endpoint. As such, Steenland et al.
calculated odds ratios by quartile of cumulative silica exposure for
renal disease in a nested case-control analysis that considered any
mention of renal disease on the death certificate as well as underlying
cause. For multiple-cause mortality, the exposure-response trend was
statistically significant for both cumulative exposure (p = 0.004) and
log cumulative exposure (p = 0.0002); whereas for underlying cause
mortality, the trend was statistically significant only for log
cumulative exposure (p = 0.03) (Document ID 1711, p. 315). Thus, OSHA
believes that Steenland et al. (2002a, Document ID 0448) were justified
in including only the three cohorts with all-cause mortality in their
pooled analysis.
Concern was also expressed about the model selection in the pooled
analysis. Dr. Morfeld noted that a statistically significant
association between exposure to crystalline silica and renal disease
mortality was only found in the underlying cause analysis in which the
model was logged (p = 0.03) (Document ID 2308, Attachment 4, p. 25).
Dr. Morfeld commented, "The authors stated that the log-model fit
better, but evidence was not given (e.g., information criteria), and it
is unclear whether the results are robust to other transformations"
(Document ID 2308, Attachment 4, p. 25).
OSHA disagrees with this criticism because a log transformation of
the cumulative exposure metric is reasonable, given that exposure
variables are often lognormally distributed in epidemiological studies,
as discussed in Section V.J, Comments and Responses Concerning Biases
in Key Studies. Also, while it is true that Steenland et al. (2002a)
only found a statistically significant association in the continuous
underlying cause analysis when the cumulative exposure metric was
logged (p = 0.03), OSHA notes that the authors also found a
statistically significant association in the highest quartile of
unlogged cumulative silica exposure (1.67 + mg/m\3\-yr) in the
categorical underlying cause analysis (95% confidence interval: 1.31-
11.76) (Document ID 0448, Table 2, p. 7). Thus, for the highest
cumulative exposures, there was a significant association with renal
disease mortality even without a log transformation of the exposure
metric. Dr. Morfeld also failed to mention that Steenland et al.
(2002a) found statistically significant associations in the continuous
analyses (for both untransformed and log-transformed cumulative
exposure) using any mention of renal disease on the death certificate,
which adds weight to the study's findings that exposure to respirable
crystalline silica is associated with renal disease mortality (Document
ID 0448, Table 2, p. 7). In light of this, OSHA concludes that Dr.
Morfeld's criticism of the pooled analysis is without merit.
The ACC also noted that the authors of this study, Drs. Kyle
Steenland and Scott Bartell, acknowledged the limitations of the data
in their 2004 ToxaChemica report to OSHA. Specifically, in reference to
the 51 renal deaths (underlying cause) and 23 renal cases in the pooled
study, Drs. Steenland and Bartell wrote, "This amount of data is
insufficient to provide robust estimates of risk" (Document ID 2307,
Attachment A, p. 139, citing 0469, p. 27). Given this acknowledgement,
the ACC concluded that OSHA's inclusion of the renal disease mortality
risk estimates in the significant risk determination and calculation of
expected benefits was speculative (Document ID 2307, Attachment A, pp.
139-140). During the hearing, Dr. Steenland further explained, "I
think there is pretty good evidence that silica causes renal disease. I
just think that there is not as big a database as there is for lung
cancer and silicosis. And so there is more uncertainty" (Document ID
3580, Tr. 1245). OSHA agrees with Dr. Steenland and acknowledges, as it
did in its Review of Health Effects Literature and Preliminary QRA
(Document ID 1711, p. 357), that its quantitative risk estimates for
renal disease mortality have more uncertainty and are less robust than
those for the other health effects examined (i.e., lung cancer
mortality, silicosis and NMRD mortality, and silicosis morbidity).
However, OSHA disagrees with the ACC's suggestion that the Agency's
renal disease risk estimates are "rank speculation" (Document ID
4209, pp. 95-96), as these estimates are based on the best available
evidence in the form of a published, peer-reviewed pooled analysis
(Steenland et al. 2002a, Document ID 0448) that uses sound
epidemiological and statistical methods. Thus, OSHA believes that it is
appropriate to present the risk estimates along with the associated
uncertainty estimate (e.g., 95% confidence intervals) (see Document ID
1711, p. 316).
2. Individual Studies in the Pooled Study
The ACC also identified limitations in each of the three
epidemiological studies included in the Steenland et al. (2002a,
Document ID 0448) pooled study. First, with respect to the Steenland
and Brown (1995a, Document ID 0450) study of North Dakota gold miners,
the ACC noted there was a significantly elevated standardized mortality
ratio (SMR) for chronic renal disease only in the men hired prior to
1930. It noted that there were no silica exposure measurement data
available for this early time period, such that Steenland and Brown
(1995a, Document ID 0450) instead estimated a median exposure (150
[mu]g/m\3\) that was seven times higher for men hired prior to 1930,
versus men hired after 1950 (20 [mu]g/m\3\) (Document ID 2307,
Attachment A, p. 147). The ACC maintained that these exposure estimates
were likely to be understated and not credible, while also suggesting
"the existence of an average exposure threshold >=150 [mu]g/m\3\ for
any risk of silica-related renal disease mortality" (Document ID 2307,
Attachment A, p. 147).
OSHA finds the ACC's suggestion of a threshold to be unpersuasive,
as the ACC provided no analysis to indicate a threshold in this study.
OSHA addresses the Steenland and Brown (1995a, Document ID 0450)
exposure assessment in Section V.D, Comments and Responses Concerning
Silicosis and Non-Malignant Respiratory Disease Mortality and
Morbidity. The ACC also ignored the alternative explanation, that
elevated chronic renal disease mortality may have only been seen in
the workers hired prior to 1930 because they had a higher cumulative
exposure than workers hired later, not because there was necessarily a
threshold.
The ACC had a similar criticism of the Steenland et al. (2001b,
Document ID 0456) study of North American industrial sand workers. The
ACC posited that the exposure estimates were highly uncertain and
likely to be understated (Document ID 2307, Attachment A, p. 149). The
ACC noted that these exposure estimates, developed by Sanderson et al.
(2000, Document ID 0429), were considerably lower than those developed
by Rando et al. (2001, Document ID 0415) for another study of North
American industrial sand workers (Document ID 2307, Attachment A, p.
149). After discussing several differences between these two exposure
assessments, the ACC pointed to OSHA's discussion in the lung cancer
section of the preamble to the Proposed Rule (78 FR at 56302) in which
the Agency acknowledged that McDonald et al. (2001, Document ID 1091),
Hughes et al. (2001, Document ID 1060) and Rando et al. (2001, Document
ID 0415) had access to smoking histories, plant records, and exposure
measurements that allowed for the development of a job exposure matrix,
while Steenland and Sanderson (2001, Document ID 0455) had limited
access to plant facilities, less detailed historic exposure data, and
used MSHA enforcement records for estimates of recent exposure
(Document ID 2307, Attachment A, pp. 149-151). The ACC then noted that
the McDonald et al. study (2005, Document ID 1092), using the Rando et
al. (2001, Document ID 0415) exposure assessment, found no association
between end-stage renal disease or renal cancer and cumulative silica
exposure (Document ID 2307, Attachment A, pp. 149, 152).
The ACC also noted that, based on underlying cause of death, the
SMR for acute renal death in the Steenland et al. (2001b, Document ID
0456) study was not significant (95% confidence interval: 0.70-9.86),
and the SMR for chronic renal disease was barely significant (95%
confidence interval: 1.06-4.08) (Document ID 2307, Attachment A, p.
151). In light of this, the ACC maintained that Steenland et al. based
their exposure-response analyses on multiple-cause mortality data,
using all deaths with any mention of renal disease on the death
certificate even if it was not listed as the underlying cause. The ACC
asserted that "only the underlying cause data involve actual deaths
from renal disease" (Document ID 2307, Attachment A, p. 152).
OSHA does not find this criticism persuasive. For regulatory
purposes, multiple-cause mortality data is, if anything, more relevant
because renal disease constitutes the type of material impairment of
health that the Agency is authorized to protect against through
regulation regardless of whether it is determined to be the underlying
cause of a worker's death. Moreover, the discrepancy in the renal
disease mortality findings is a moot point, as only the model in the
pooled study with renal disease as an underlying cause was used to
estimate risks in the Preliminary QRA (Document ID 1711, p. 316). In
any event, OSHA notes an important difference between the Steenland et
al. study (2001b, Document ID 0456) and the McDonald study (2005,
Document ID 1092): They did not look at the same cohort of North
American industrial sand workers. Steenland et al. (2001b) examined a
cohort of 4,626 workers from 18 plants; the average year of first
employment was 1967, with follow-up through 1996 (Document ID 0456, pp.
406-408). McDonald et al. (2005) examined a cohort of 2,452 workers
employed between 1940 and 1979 at eight plants, with follow-up through
2000 (Document ID 1092, p. 368). Although there was overlap of about
six plants in the studies (Document ID 1711, p. 127), these were
clearly two fairly different cohorts of industrial sand workers. These
differences in the cohorts might explain the discrepancy in the
studies' results. In addition, OSHA notes that McDonald et al. (2005,
Document ID 1092) observed statistically significant excess mortality
from nephritis/nephrosis in their study that was not explained by the
findings of their silica exposure-response analyses (Document ID 1092,
p. 369).
The ACC further argued that the Steenland et al. (2002a, Document
ID 0448) pooled study is inferior to the Vacek et al. (2011, Document
ID 2340) study of Vermont granite workers, which found no association
between cumulative silica exposure and mortality from either kidney
cancer or non-malignant kidney disease and which it contended has
better mortality and exposure data (Document ID 2307, Attachment A, p.
154) (citing Vacek et al. (2011, Document ID 2340). In particular, it
argued that the Vacek et al. study is more reliable for this purpose
than the unpublished Attfield and Costello data (2004, Document ID
0285) on Vermont granite workers, which Steenland et al. relied on in
finding an association between silica exposure and renal disease.
OSHA notes that Steenland et al. acknowledged in their pooled study
that that unpublished data had not undergone peer review (Document ID
0448, p. 5). Despite this limitation, OSHA is also unpersuaded that the
Vacek et al. study, although it observed no increased kidney disease
mortality (Document ID 2340, Table 3, p. 315), negates Steenland et
al.'s overall conclusions. OSHA discussed several substantial
differences between these two studies in Section V.F, Comments and
Responses Concerning Lung Cancer Mortality.
3. Additional Studies
The ACC also submitted to the record several additional studies
that did not show a statistically significant association between
exposure to crystalline silica and renal disease mortality. These
included the aforementioned studies by McDonald et al. (2005, Document
ID 1092) and Vacek et al. (2011, Document ID 2340), as well as studies
by Davis et al. (1983, Document ID 0999), Koskela et al. (1987,
Document ID 0363), Cherry et al. (2012, article included in Document ID
2340), Birk et al. (2009, Document ID 1468), Mundt et al. (2011,
Document ID 1478), Steenland et al. (2002b, Document ID 0454), Rosenman
et al. (2000, Document ID 1120), and Calvert et al. (2003, Document ID
0309) (Document ID 2307, Attachment A, pp. 140-145). In light of its
assertions on the limitations of the three studies in the pooled
analysis, and because the three studies "run counter to a larger
number of studies in which a causal association between silica exposure
and renal disease was not found," the ACC concluded that "the three
studies relied on by OSHA do not provide a reliable or supportable
basis for projecting any risk of renal disease mortality from silica
exposure" (Document ID 4209, p. 94). Similarly, the AFS argued that
renal disease was only "found in a couple of selected studies and not
observed in most others," including no foundry studies (Document ID
2379, Attachment 1, pp. 1-3).
In light of the analysis contained in the Review of Health Effects
Literature and Preliminary QRA, and OSHA's confirmation of its
preliminary findings through examination of the record, OSHA finds
these claims to be lacking in merit (Document ID 1711, pp. 211-229). In
the Review of Health Effects Literature and Preliminary QRA, OSHA
presented a comprehensive analysis of several studies that showed an
association between crystalline silica and renal disease, as well
as discussing other studies that did not (Document ID 1711, pp. 211-229).
Based upon its overall analysis of the literature, including
the negative studies, OSHA concluded that there was substantial
evidence suggesting an association between exposure to crystalline
silica and increased risks of renal disease. This conclusion
was supported by a number of case reports and epidemiological
studies that found statistically significant associations
between occupational exposure to silica dust and chronic renal
disease (Calvert et al., 1997, Document ID 0976), subclinical
renal changes (Ng et al., 1992c, Document ID 0386), end-stage renal
disease morbidity (Steenland et al., 1990, Document ID 1125), end-stage
renal disease incidence (Steenland et al. 2001b, Document ID 0456),
chronic renal disease mortality (Steenland et al., 2002a, 0448), and
granulomatosis with polyangitis (Nuyts et al., 1995, Document ID 0397).
In other findings, silica-exposed individuals, both with and without
silicosis, had an increased prevalence of abnormal renal function (Hotz
et al., 1995, Document ID 0361), and renal effects were reported to
persist after cessation of silica exposure (Ng et al., 1992c, Document
ID 0386). While the mechanism of causation is presently unknown,
possible mechanisms suggested for silica-induced renal disease included
a direct toxic effect on the kidney, deposition in the kidney of immune
complexes (IgA) following silica-related pulmonary inflammation, or an
autoimmune mechanism (Calvert et al., 1997, Document ID 0976; Gregorini
et al., 1993, 1032).
From this review of the studies on renal disease, OSHA concluded
that there were considerably less data, and thus the findings based on
them were less robust, than the data available for silicosis and NMRD
mortality, lung cancer mortality, or silicosis morbidity. Nevertheless,
OSHA concluded that the Steenland et al. (2002a, Document ID 0448)
pooled study had a large number of workers and validated exposure
information, such that it was sufficient to provide useful estimates of
risk of renal disease mortality. With regard to the additional negative
studies presented by the ACC, OSHA notes that it discussed the Birk et
al. (2009, Document ID 1468) and Mundt et al. (2011, Document ID 1478)
studies in the Supplemental Literature Review of the Review of Health
Effects Literature and Preliminary QRA, noting the short follow-up
period as a limitation, which makes it unlikely to observe the presence
of renal disease (Document ID 1711, Supplement, pp. 6-12). OSHA
likewise discussed the Vacek et al. (2011, Document ID 2340) study
earlier in this section, and notes that Cherry et al. reported a
statistically significant excess of non-malignant renal disease
mortality in the cohort for the period 1985-2008, with an unexplained
cause (2012, p. 151, article included in Document ID 2340). Although
these latter two studies did not find a significant association between
silica exposure and renal disease mortality, OSHA does not believe that
they substantially change its conclusions on renal disease mortality
from the Preliminary QRA, given the number of positive studies
presented and the limitations of those two studies.
Thus, OSHA recognizes that the renal risk estimates are less robust
and have more uncertainty than those for the other health endpoints for
which there is a stronger case for causality (i.e., lung cancer
mortality, silicosis and NMRD mortality, and silicosis morbidity). But,
for the reasons stated above, OSHA believes that the evidence
supporting causality regarding renal risk outweighs the evidence
casting doubt on that conclusion. Scientific certainty is not the legal
standard under which OSHA acts. OSHA is setting the standard based upon
the clearly significant risks of lung cancer mortality, silicosis and
NMRD mortality, silicosis morbidity, and renal disease mortality at the
previous PELs; even if the risk of renal disease mortality is
discounted, the conclusion would not change that regulation is needed
to reduce the significant risk of material impairment of health (see
Society of the Plastics Industry, Inc. v. OSHA, 509 F.2d 1301, 1308 (2d
Cir. 1975)).
H. Mechanisms of Silica-Induced Adverse Health Effects
In this section, OSHA describes the mechanisms by which silica
exposure may cause silica-related health effects, and responds to
comments criticizing the Agency's analysis on this topic. In the
proposal as well as this final rule, OSHA relied principally on
epidemiological studies to establish the adverse health effects of
silica exposure. The Agency also, however, reviewed animal studies (in
vivo and in vitro) as well as in vitro human studies that provide
information about the mechanisms by which respirable crystalline silica
causes such effects, particularly silicosis and lung cancer. OSHA's
review of this material can be found in the Review of Health Effects
Literature and Preliminary Quantitative Risk Assessment (QRA), which
provided background and support for the proposed rule (Document ID
1711, pp. 229-261).
As described in the Review of Health Effects Literature, OSHA
performed an extensive evaluation of the scientific literature
pertaining to inhalation of respirable crystalline silica (Document ID
1711, pp. 7-265). Due to the lack of evidence of health hazards from
dermal or oral exposure, the Agency focused solely on the studies
addressing the inhalation hazards of respirable crystalline silica.
OSHA determined, based on the best available scientific information,
that several cellular events, such as cytotoxicity (i.e., cellular
damage), oxidative stress, genotoxicity (i.e., damage to cellular DNA),
cellular proliferation, and inflammation can contribute to a range of
neoplastic (i.e., tumor-forming) and non-neoplastic health effects in
the lung. While the exact mechanisms have yet to be fully elucidated,
they are likely initiated by damage to lung cells from interaction
directly with the silica particle itself or through silica particle
activation of alveolar macrophages following phagocytosis (i.e.,
engulfing particulate matter in the lung for the purpose of removing or
destroying foreign particles). The crystalline structure and unusually
reactive surface properties of the silica particle appear to cause the
early cellular effects. Silicosis and lung cancer share common features
that arise from these early cellular interactions but OSHA, in its
Review of Health Effects Literature and Preliminary QRA,
"preliminarily conclude[d] that available animal and in vitro studies
have not conclusively demonstrated that silicosis is a prerequisite for
lung cancer in silica-exposed individuals" (Document ID 1711, p. 259).
Although the health effects associated with inhalation of respirable
crystalline silica are seen primarily in the lung, other observed
health effects include kidney and immune dysfunctions.
Below, OSHA reviews the record evidence and responds to comments it
received on the mechanisms underlying respirable crystalline silica-
induced lung cancer and silicosis. The Agency also addresses comments
regarding the use of animal studies to characterize adverse health
effects in humans caused by exposure to respirable crystalline silica.
1. Mechanisms for Silica-Related Health Effects
In 2012, IARC reevaluated the available scientific information
regarding respirable crystalline silica and lung cancer and reaffirmed
that crystalline silica is carcinogenic to humans,
i.e., a Group 1 carcinogen (Document ID 1473, p. 396). OSHA's
review of all the evidence now in the rulemaking record, including the
results of IARC's reevaluation, indicates that silica may lead to
increased risk of lung cancer in humans by a multistage process that
involves a combination of genotoxic (i.e., causing damage to cellular
DNA) and non-genotoxic (i.e., not involving damage to DNA) mechanisms.
Respirable crystalline silica may cause genotoxicity as a result of
reactive oxygen species (ROS) produced by activated alveolar
macrophages and other lung cells exposed to crystalline silica
particles during phagocytosis. ROS have been shown to damage DNA in
human lung cells in vitro (see Document ID 1711, pp. 236-239). This
genotoxic mechanism is believed to contribute to neoplastic
transformation and silica-induced carcinogenesis. ROS is not only
produced during the early cellular interaction with crystalline silica
but also produced by PMNs (polymorphonuclear leukocytes) and
lymphocytes recruited during the inflammatory response to crystalline
silica. In addition to genotoxicity contributed by ROS, it is also
plausible that reactive molecules on the surface of crystalline silica
itself may bind directly to DNA and result in genotoxicity (Document ID
1711, p. 236). It should be noted that the mechanistic evidence
summarized above suggests that crystalline silica may cause early
genotoxic events that are independent of the advanced chronic
inflammatory response and silicosis (Document ID 1473, pp. 391-392).
Non-genotoxic mechanisms are also believed to contribute to the
lung cancer caused by respirable crystalline silica. Phagocytic
activation as well as silica-induced cytotoxicity trigger release of
the aforementioned ROS, cytokines (e.g., TNF[alpha]), and growth
factors (see Document ID 1711, pp. 233-235). These agents are able to
cause cellular proliferation, loss of cell cycle regulation, activation
of oncogenes (genes that have the potential to cause cancer), and
inhibition of tumor suppressor genes, all of which are non-genotoxic
mechanisms known to promote the carcinogenic process. It is plausible
that these mechanisms may be involved in silica-induced tumorigenesis.
The biopersistence and cytotoxic nature of crystalline silica leads to
a cycle of cell death (i.e., cytotoxicity), activation of alveolar
macrophages, recruitment of inflammatory cells (e.g., PMNs,
leukocytes), and continual release of the non-genotoxic mediators
(i.e., ROS, cytokines) able to promote carcinogenesis. The non-
genotoxic mechanisms caused by early cellular responses (e.g.,
phagocytic activation, cytotoxicity) are regarded, along with
genotoxicity, as important potential pathways that lead to the
development of tumors (Document ID 1711, pp. 232-239; 1473, pp. 394-
396).
The same non-genotoxic processes that may cause lung cancer from
respirable crystalline silica exposure are also believed to lead to
chronic inflammation, lung scarring, fibrotic lesions, and eventually
silicosis. This would occur when inflammatory cells move from the
alveolar space through the interstitium of the lung as part of the
clearance process. In the interstitium, respirable crystalline silica-
laden cells--macrophages and neutrophils--release ROS and TNF-[alpha],
as well as other cytokines, stimulating the proliferation of
fibroblasts (i.e., the major lung cell type in silicosis).
Proliferating fibroblasts deposit collagen and connective tissue,
inducing the typical scarring that is observed with silicosis.
Alternatively, alveolar epithelial cells containing respirable
crystalline silica die and may be replaced by fibroblasts due to
necrosis of the epithelium. This allows for uninhibited growth of
fibroblasts and formation of connective tissue where scarring
proliferates (i.e., silicosis). As scarring increases, there is a
reduction in lung elasticity concomitant with a reduction of the lung
surface area capable of gas exchange, thus reducing pulmonary function
and making breathing more difficult (Document ID 0314; 0315). It should
be noted that silicosis involves many of the same mechanisms that occur
during the early cellular interaction with crystalline silica.
Therefore, it is plausible that development of silicosis may also
potentially contribute to silica-induced lung cancer. However, the
relative contributions of silicosis-dependent and silicosis-independent
pathways are not known.
Although it is clear that exposure to respirable crystalline silica
increases the risk of lung cancer in exposed workers (see Section VI,
Final Quantitative Risk Assessment and Significance of Risk), some
commenters claimed that such exposure cannot cause lung cancer
independently of silicosis (i.e., only those workers who already have
silicosis can get lung cancer) (Document ID 2307, Attachment A, p. 53).
This claim is inconsistent with the credible scientific evidence
presented above that genotoxic and non-genotoxic mechanisms triggered
by early cellular responses to crystalline silica prior to development
of silicosis may contribute to crystalline silica-induced
carcinogenesis. OSHA finds, based on its review of all the evidence in
the rulemaking record, that workers without silicosis, as well as those
with silicosis, are at risk of lung cancer if regularly exposed to
respirable crystalline silica at levels permitted under the previous
and new PELs. The Agency also emphasizes that, regardless of the
mechanism by which respirable crystalline silica exposure increases
lung cancer risk, the fact remains that workers exposed to respirable
crystalline silica continue to be diagnosed with lung cancer at a
higher rate than the general population. Therefore, as discussed in
section VI, Final Quantitative Risk Assessment and Significance of
Risk, OSHA has met its burden of proving that workers exposed to
previously allowed levels of respirable crystalline silica are at
significant risk, by one or more of these mechanisms, of serious and
life-threatening health effects, including both silicosis and lung
cancer.
2. Relevance of Animal Models to Humans
Animal data has been used for decades to evaluate hazards and make
inferences regarding causal relationships between human health effects
and exposure to toxic substances. The National Academies of Science has
endorsed the use of well-conducted animal studies to support hazard
evaluation in the risk assessment process (Document ID 4052, p. 81) and
OSHA's policy has been to rely on such studies when regulating
carcinogens. In the case of respirable crystalline silica, OSHA has
used evidence from animal studies, along with human epidemiology and
other relevant information, to establish that occupational exposure is
associated with silicosis, lung cancer, and other non-malignant
respiratory diseases, as well as renal and autoimmune effects (Document
ID 1711, pp. 261-266). Exposure to various forms of respirable
crystalline silica by inhalation and intratracheal instillation has
consistently caused lung cancer in rats (IARC, 1997, Document ID 1062,
pp. 150-163). These results led IARC and NTP to conclude that there is
sufficient evidence in experimental animals to demonstrate the
carcinogenicity of crystalline silica in the form of quartz dust. IARC
also concluded that there is sufficient evidence in human studies for
the carcinogenicity of crystalline silica in the form of quartz or
cristobalite.
In its pre-hearing comments and post-hearing brief, the ACC noted
that increased lung cancer risks from exposure to respirable
crystalline silica have not been found in animal species other than
rats, and questioned the relevance of the rat model for evaluating
potential lung carcinogenicity in humans (Document ID 2307, Attachment
A, p. 30; 4209, p. 32). Specifically, the ACC highlighted studies by
Holland (1995) and Saffiotti et al. (1996) indicating that bioassays in
respirable crystalline silica-exposed mice, guinea pigs, and Syrian
hamsters have not found increased lung cancer (Document ID 2307,
Attachment A, p. 30, f. 51).
The ACC proposed that the increased lung cancer risk in respirable
crystalline silica-exposed rats is due to a particle overload
phenomenon, in which lung clearance of nonfibrous durable particles
initiates a non-specific response that results in intrapulmonary lung
tumors (Document ID 2307, Attachment A, p. 30, n. 51). Dr. Cox, on
behalf of the ACC, citing Mauderly (1997, included in Document ID
3600), Oberdorster (1996, Document ID 3969), and Nikula et al. (1997,
included in Document ID 3600), likewise commented that rats are
"uniquely sensitive to particulate pollution, for species-specific
reasons that do not generalize to other rodents or mammals, including
humans" (Document ID 2307, Attachment 4, p. 83). OSHA reviewed the
three studies referenced by Dr. Cox and notes that two actually appear
to support the use of the rat model and the third does not reject it.
Mauderly (1997) noted that the rat model was the only one to correctly
predict carcinogenicity after inhalation exposure to several types of
asbestos, and highlighted the shortcomings of other models, such as
those using hamsters, which are highly insensitive to particle-induced
lung cancers (article included in Document ID 3600, pp. 1339-1343).
While Mauderly (1997) advised caution when using the rat because it is
the most sensitive rodent species for lung cancer, he concluded that
"there is evidence supporting continued use of rats in exploration of
carcinogenic hazards of inhaled particles," and that the other test
species are problematic because they provide too many false negatives
to be predictive (article included in Document ID 3600, p. 1343).
Similarly, Oberdorster (1996), in discussing particle parameters used
in the evaluation of exposure-dose-relationships of inhaled particles,
stated that "the rat model should not be dismissed prematurely"
(Document ID 3969, p. 73). Oberdorster (1996) postulated that humans
and rats have very similar responses to particle-induced effects when
analyzing the exposure-response relationship using particle surface
area, rather than particle mass, as the exposure metric. Oberdorster
concluded that there simply was not enough known regarding exact
mechanisms to reject the model outright (Document ID 3969, pp. 85-87).
The remaining paper cited by Dr. Cox, Nikula et al. (1997), evaluated
the anatomical differences between primate and rodent responses to
inhaled particulate matter and the role of clearance patterns and
physiological responses to inhaled toxicants. The study noted that the
differences between primate clearance patterns and rat clearance
patterns may play a role in the pathogenesis from inhaled poorly
soluble particles but did not dismiss the rat model as irrelevant to
humans (Nikula, 1997, included in Document ID 3600, pp. 83, 93, 97).
Thus, OSHA finds that the Mauderly (1997) and Oberdorster (1996)
articles generally support the rat as an appropriate model for
qualitatively assessing the hazards associated with particle
inhalation. OSHA likewise notes that the rat model is a common and
well-accepted toxicological model used to assess human health effects
from toxicant inhalation (ILSI, 2000, Document ID 3906, pp. 2-9). OSHA
evaluated the available studies in the record, both positive and non-
positive, and believes that it is appropriate to regard positive
findings in experimental studies using rats as supportive evidence for
the carcinogenicity of crystalline silica. This determination is
consistent with that of IARC (Document ID 1473, p. 388) and NTP
(Document ID 1164, p. 1), which also regarded the significant increases
in incidence of malignant lung tumors in rats from multiple studies by
both inhalation and intratracheal instillation of crystalline silica to
be sufficient evidence of carcinogenicity in experimental animals and,
therefore, to contribute to the evidence for carcinogenicity in humans.
3. Hypothesis That Lung Cancer Is Dependent on Silicosis
The ACC asserted in its comments that "if it exists at all,
silica-related carcinogenicity most likely arises through a silicosis
pathway or some other inflammation-mediated mechanism, rather than by
means of a direct genotoxic effect" (Document ID 2307, Attachment A,
p. 52; 4209, p. 51; 2343, Attachment 1, pp. 40-44). It explained that
the "silicosis pathway" means that lung cancer stems from chronic
inflammatory lung damage, which in turn, "implies that there is a
threshold for any causal association between silica exposure and risk
of lung cancer" (Document ID 2307, Attachment A, pp. 52-53). The ACC
went on to state that a mechanism that involves ROS, growth factors,
and inflammatory cytokines from alveolar macrophages is "most
consistent" with development of advanced chronic inflammation (e.g.,
epithelial hyperplasia, lung tissue damage, fibrosis, and silicosis).
According to this hypothesis, silica-related lung cancer is restricted
to people who have silicosis (Document ID 2307, Attachment 2, p. 7).
Regarding this hypothesis, the ACC concluded, "[t]his view of the
likely mechanism for silica-related lung cancer is widely accepted in
the scientific community, including by OSHA's primary source of silica-
related health risk estimates, Dr. Kyle Steenland. OSHA appears to
share this view as well" (Document ID 2307, Attachment A, p. 54).
The ACC statement regarding acceptance by OSHA and the scientific
community is inaccurate. It implies scientific consensus, as well as
OSHA's concurrence, that the chronic inflammation from silicosis is the
only mechanism by which crystalline silica exposure results in lung
cancer. The ACC has over-simplified and neglected the findings of the
mechanistic studies that show activation of phagocytic and epithelial
cells to be an early cellular response to crystalline silica prior to
chronic inflammation (see Document ID 1711, pp. 234-238). As discussed
previously, alveolar macrophage activation leads to initial production
of ROS and release of cytokine growth factors that could contribute to
silica-induced carcinogenicity through both genotoxic and non-genotoxic
mechanisms. The early cellular response does not require chronic
inflammation and silicosis to be present, as postulated by the ACC. It
is possible that the early mechanistic influences that increase cancer
risk may be amplified by a later severe chronic inflammation or
silicosis, if such a condition develops. However, as Brian Miller,
Ph.D., stated "this issue of silicosis being a precursor for lung
cancer is unanswerable, given that we cannot investigate for early
fibrotic lesions in the living, but must rely on radiographs."
(Document ID 3574, Tr. 31).
In pre-hearing comments the ACC commented, as proof of silicosis
being linked to lung cancer, that fibrosis was linked to
adenocarcinomas (Document ID 2307, Attachment A, p. 61). This statement
is misleading. As explained earlier, silicosis results from stimulation
of fibroblast cells that cause lung fibrosis. Adenocarcinomas,
a hallmark tumor type in respirable crystalline silica-induced lung cancer,
are tumors that arise not from fibroblasts, but exclusively from lung
epithelial cells (IARC, 2012, Document ID 1473, pp. 381-389, 392).
These tumors may be linked to the genotoxic and non-genotoxic mechanisms
that occur prior to fibrosis, not secondary to the fibrotic process itself.
OSHA also received some comments that questioned the existence of a
direct genotoxic mechanism. Jonathan Borak, M.D., on behalf of the U.S.
Chamber of Commerce, commented, "there is no direct evidence that
silica causes cancer by means of a directly DNA-reactive mechanism"
(Document ID 2376, p. 21). Dr. Peter Morfeld, on behalf of the ACC, as
well as Peter Valberg, Ph.D., and Christopher M. Long, Sc.D., of
Gradient Corporation, on behalf of the U.S. Chamber of Commerce, cited
a scientific article by Borm et al. (2011, included in Document ID
3573) which reported finding evidence against a genotoxic mechanism and
in favor of a mechanism secondary to chronic inflammation (Document ID
3458, pp. 5-7; 4016, pp. 5-6; 4209, p. 51). Borm et al. (2011, included
in Document ID 3573) analyzed 245 published studies from 1996 to 2008
identified using the search terms "quartz" and `toxicity" in
conjunction with "surface," "inflammation," "fibrosis," and
"genotoxicity." The authors then estimated the lowest dose (in units
of micrograms per cell surface area) to consistently induce DNA damage
or induce markers of inflammation (e.g., IL-8 upregulation) in in vitro
studies. They adjusted the in vitro doses for the lung surface area
encountered in vivo and found the crystalline silica dose that produced
primary genotoxicity was 60-120 times higher than the dose that
produced inflammatory cytokines (Borm et al., 2011, included in
Document ID 3573, p. 762). Drs. Valberg and Long concluded that Borm et
al. demonstrated that genotoxicity was a secondary response to chronic
inflammation, except at very high exposures at which genotoxicity
independent of inflammation might occur. They also maintained that lung
cancer as a secondary response to chronic inflammation is considered to
have a threshold (Document ID 4016, p. 6).
OSHA reviewed the Borm et al. study (2011, Document ID 3889), and
notes several limitations. The authors examined the findings from
various genotoxic assays (comet assay, 8-OH-dG, micronucleus test)
(Borm et al., 2011, 3889, p. 758). They reported that 40 [mu]g/cm\2\
was the lowest dose in vitro to produce significant direct DNA damage
from crystalline silica. This genotoxic dose appears to be principally
obtained from a study of a specific quartz sample (i.e., DQ12) in a
single human alveolar epithelial cell line (i.e., A549 cells), even
though Appendix Table 3 cited in vitro studies using other cells (e.g.,
fibroblasts) and other types of quartz (e.g., MinUsil) that produced
direct genotoxic effects at lower doses (Borm et al., 2011, Document ID
3889, pp. 760, 769-770). This is especially pertinent since Borm et al.
state that in vitro systems utilizing single-cell cultures are
generally much less sensitive than in vivo systems, especially if
attempting to determine oxidative stress-induced effects, since many
cell culture systems use reagents that can scavenge ROS (Borm et al.
2011, Document ID 3889, p. 760). There was no indication that the
authors accounted for this deficiency. They go on to conclude that
their work shows a large-scale variation in hazard across different
forms of quartz with regard to effects such as DNA breakage (e.g.,
genotoxicity) and inflammation (Borm et al. 2011, Document ID 3889, p.
762).
The extreme variation in response along with reliance on an
insensitive genotoxicity test system could overestimate the appropriate
genotoxic dose in human lung cells in vivo. In addition, Borm et al.
used the dose sufficient to initiate production of an inflammatory
cytokine (i.e., IL-8) in the A549 cell-line as the threshold for
inflammation. It is not clear that an early cellular response, such as
IL-8 production necessarily reflects a sustained inflammatory response.
In summary, OSHA finds inconsistencies in this analysis, leaving some
questions regarding the study's conclusion that silica induces
genotoxicity only as a secondary response to an inflammation-driven
mechanism. While the in vitro dose comparisons in this study fail to
demonstrate that genotoxicity is secondary to the inflammatory
response, the study findings do indicate that cellular responses to
crystalline silica that drive inflammation may also lead to
tumorigenesis through both genotoxic and non-genotoxic mechanisms.
Dr. Morfeld, in his hearing testimony on behalf of the ACC,
referred to the paper by Borm et al. (2011) as reaching the conclusion
that the mechanism of silica-related lung cancer is secondary
inflammation-driven genotoxicity. As summarized by the ACC in post-
hearing comments, he observed that "there are no crystalline silica
particles found in the nucleus of the cells. There is nothing going on
with particles in the epithelial cells inside the lung" (Document ID
4209, p. 52). In hearing testimony, however, Dr. Morfeld acknowledged
that the Borm paper had limitations on extrapolating from in vitro to
in vivo and cited a study by Donaldson et al. (2009), which discussed
some of the limitations and the need for caution in extrapolating from
in vitro to in vivo (Document ID 3582, Tr. 2076-2077; 3894, pp. 1-2).
In considering this testimony, OSHA notes that the Donaldson et al.
(2009) study, which includes the same authors as the Borm et al. (2011)
study, acknowledged that direct interaction between respirable
crystalline silica and epithelial cellular membranes induces
intracellular oxidative stress which is capable of being genotoxic
(Document ID 3894, p. 3). This is consistent with the OSHA position as
well as the most recent IARC reevaluation of the cancer hazard from
crystalline silica dust. As IARC stated in its most recent evaluation
of the carcinogenicity of respirable crystalline silica under a section
on direct genotoxicity and cell transformation (Document ID 1473,
section 4.2.2, pp. 391-393):
Reactive oxygen species are generated not only at the particle
surface of crystalline silica, but also by phagocytic and epithelial
cells exposed to quartz particles....Oxidants generated by
silica particles and by the respiratory burst of silica-activated
phagocytic cells may cause cellular and lung injury, including DNA
damage (Document ID 1473, p. 391).
Given the IARC determination as well as the animal and in vitro
studies reviewed herein, OSHA finds that there is no conclusive
evidence that silica-related lung cancer only occurs as a secondary
response to chronic inflammation, or that silicosis is a necessary
prerequisite for lung cancer. Instead, OSHA finds support in the
scientific literature for a conclusion that tumors may form through
genotoxic as well as non-genotoxic mechanisms that result from
respirable crystalline silica interaction with alveolar macrophages and
other lung cells prior to onset of silicosis.
4. Hypothesis That Crystalline Silica-Induced Lung Disease Exhibits a
Threshold
It is well established that silicosis arises from an advanced
chronic inflammation of the lung. As noted above, a common hypothesis
is that pathological conditions that depend on chronic inflammation may
have a threshold. The exposure level at which silica-induced health
effects might begin to appear, however, is poorly characterized in the
literature (see Section V.I, Comments and Responses Concerning Thresholds for
Silica-Related Diseases). The threshold exposure level required for a
sustained inflammatory response is dependent upon multiple pro- and
anti-inflammatory factors that can be quite variable from individual to
individual and from species to species (Document ID 3896).
Discounting or overlooking the evidence that respirable crystalline
silica may be genotoxic in the absence of chronic inflammation, Drs.
Valberg and Long commented that crystalline silica follows a threshold
paradigm for poorly soluble particles (PSPs). PSPs are defined
generally as nonfibrous particles of low acute toxicity, which are not
directly genotoxic (ILSI, 2000, Document ID 3906, p. 1). Specifically,
Drs. Valberg and Long stated:
Mechanisms whereby lung cells respond to retention of a wide
variety of PSPs, including crystalline silica, follow a generally
accepted threshold paradigm, where the initiation of a chronic
inflammatory response is a necessary step in the disease process,
and the inflammatory response does not become persistent until
particle retention loads become sufficient to overwhelm lung defense
mechanisms. This overall progression from increased but controlled
pulmonary inflammation across a threshold exposure that leads to
lung damage has been described by a number of investigators
(Mauderly and McCunney, 1995; ILSI, 2000; Boobis et al., 2009;
Porter et al. 2004) (Document ID 2330, p. 19).
Similarly, Dr. Cox, in his post-hearing comments, discussed his
2011 article describing a quantifiable exposure-response threshold for
lung diseases induced by inhalation of respirable crystalline silica
(Document ID 4027, p. 29). Dr. Cox hypothesized the existence of an
exposure threshold such that exposures to PSPs, which he described as
including titanium dioxide, carbon black, and crystalline silica, must
be intense enough and last long enough to disrupt normal homeostasis
(i.e., normal cellular functions) and overwhelm normal repair
processes. Under the scenario he described, a persistent state of
chronic, unresolved inflammation results in a disruption of macrophage
and neutrophil ability to clear silica and other foreign particles from
the lung (Document ID 1470, pp. 1548-1551, 1555-1556).
OSHA disagrees with these characterizations about exposure
thresholds because, among other reasons, respirable crystalline silica
is not generally considered to be in the class of substances defined as
PSPs.\7\ Specifically, regarding the comments of Drs. Valberg and Long,
OSHA notes that the two cited documents (Mauderly and McCunney, 1995,
and ILSI, 2000) summarizing workshops on PSPs did not include
crystalline silica in the definition of PSP and the lung "overload"
concept, instead highlighting silica's cytotoxic and genotoxic
mechanisms. Mauderly and McCunney (1995) stated, "[i]t is generally
accepted that the term `overload' should be used in reference to
particles having low cytotoxicity, which overload clearance
[mechanisms] by virtue of the mass, volume, or surface area of the
deposited material (Morrow, 1992)" (p. 3, article cited in Document ID
2330, p. 19). Mauderly specifically cited quartz as a cytotoxic
particle that may fall outside this definition (p. 24, article cited in
Document ID 2330, p. 19). The International Life Science Institute's
(ILSI) Workshop Report (2000) intended only to address particles of
"low acute toxicity," such as carbon black, coal dust, soot, and
titanium dioxide (Document ID 3906, p. 1). OSHA believes that the
cytotoxic nature of crystalline silica would exclude it from the class
of rather nonreactive, non-toxic particles mentioned above. Therefore,
the Agency concludes that most scientific experts would not include
crystalline silica in the class of substances known as PSPs, nor intend
for findings regarding PSPs to be extrapolated to crystalline silica.
---------------------------------------------------------------------------
\7\ OSHA notes that crystalline silica has many mechanistic
features in common with asbestos. They are both durable,
biopersistent mineral forms where there is sufficient evidence of an
association with lung cancer (i.e., IARC Group 1 carcinogens),
chronic lung inflammation, and severe pulmonary fibrosis (i.e.,
silicosis and asbestosis) in humans. Like crystalline silica,
asbestos has reactive surfaces or other physiochemical properties
able to hinder phagocytosis and activate macrophages to release
reactive oxygen species, cytokines, and growth factors that lead to
DNA damage, cytotoxicity, cell proliferation and an inflammatory
response responsible for the disease outcomes mentioned above (see
IARC 2012, Document ID 1473, pp. 283-290). Crystalline silica and
asbestos can trigger phagocytic activation well below the high mass
burdens required to "overload" the lung and impair pulmonary
clearance that is typical of carbon black and other low acute-
toxicity PSPs.
---------------------------------------------------------------------------
During the public hearing, OSHA questioned Dr. Morfeld about the
relevance of the rat overload response and whether he considered
crystalline silica to be like other PSPs such as carbon black. Dr.
Morfeld replied that he was well aware of the literature and indicated
that crystalline silica was not considered one of the PSPs
(specifically not like carbon black) that these reports reviewed
(Document ID 3582, Tr. 2072-2074). OSHA also notes a report of the
European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC),
which was cited by the ACC (Document ID 4209, p. 32) and stated that
"particles exhibiting significant surface related (cyto)toxicity like
crystalline silica (quartz) and/or other specific toxic properties do
not fall under this definition [of PSPs]" (Document ID 3897, p. 5).
Respirable crystalline silica differs from PSPs because it does not
require particle overload to induce the same response typical of PSPs.
"Overload" refers to the consequence of exposure that results in a
retained lung burden of particles that is greater than the steady-state
burden predicted from deposition rates and clearance kinetics (Document
ID 4174, p. 20). This is a result of a volumetric over-exposure of dust
in the lung, which overwhelms macrophage function. Respirable
crystalline silica does not operate on this mechanism since macrophage
function is inhibited by the cytotoxic nature of respirable crystalline
silica rather than a volumetric overload (Oberdorster, 1996, Document
ID 3969). Therefore, respirable crystalline silica does not require
particle overload to induce the same response. Studies have found that
the respirable crystalline silica exposure levels required to induce
tumor formation in some animal studies are similar to those observed in
human studies, whereas studies involving PSPs tend to show responses at
much higher levels of exposure (Muhle et al., 1991, Document ID 1284;
Muhle et al., 1995, 0378; Saffiotti and Ahmed, 1995, 1121).
A study by Porter et al. (2004) demonstrated that pulmonary
fibrosis induction does not require silica particle overload (Document
ID 0410, p. 377). The ACC cited this study in its post-hearing brief,
stating, "Porter...noted that the response of the rat lung to
inhaled crystalline silica particles is biphasic, with a below-
threshold phase characterized by increased but controlled pulmonary
inflammation" (Document ID 4209, p. 52). OSHA notes that this biphasic
response is due in part to the cytotoxic nature of crystalline silica,
which disrupts macrophage clearance of silica particles leading to a
chronic inflammatory response at less than overload conditions. While
there are some mechanistic similarities, OSHA believes that the
argument that crystalline silica operates on the basis of lung overload
is erroneous and based on false assumptions that ignore toxicological
properties unique to crystalline silica, such as cytotoxicity and the
generation of intracellular ROS (Porter et al., 2002, Document ID 1114;
Porter et al., 2004, 0410). As previously discussed, the generation of
ROS could potentially damage cellular DNA by a genotoxic mechanism that
may not exhibit a threshold.
OSHA thoroughly reviewed Dr. Cox's 2011 article (Document ID 1470),
in which he proposed a threshold for crystalline silica, in its
Supplemental Literature Review (Document ID 1711, Attachment 1, pp. 37-
39). OSHA concluded that the evidence used to support Cox's assertion
that the OSHA PEL was below a threshold for lung disease in humans was
not supported by the evidence presented (Document ID 1470, p. 1543;
1711, Attachment 1). Specifically, Cox (2011) modelled a threshold
level for respirable crystalline silica using animal studies of PSPs.
This approach, according to the ILSI report (2000) and ECETOC report
(2013), is clearly not appropriate since the cytotoxic nature of
crystalline silica is not consistent with the low-toxicity PSPs
(Document ID 3906, p. 1; 3897, p. 5). Dr. Cox (2011) categorized
crystalline silica incorrectly as a PSP and ignored the evidence for
cytotoxicity and genotoxicity associated with crystalline silica. He
further failed to consider or include studies indicating a tumor
response at exposure levels below that leading to an excessive chronic
inflammatory response, such as Porter et al. (2002) and Muhle et al.
(1995) (Document ID 1114; 0378). Thus, OSHA considers the threshold
model designed by Dr. Cox (2011, Document ID 1470) and referenced by
Drs. Valberg and Long (Document ID 2330) to be contradicted by the best
available evidence regarding the toxicological properties of respirable
crystalline silica. Although OSHA acknowledges the possible existence
of a threshold for an inflammatory response, the Agency believes that
the threshold is likely much lower than that advocated by industry
representatives such as the ACC and the Chamber of Commerce (see
Section V.I, Comments and Responses Concerning Thresholds for Silica-
Related Diseases).
OSHA concludes that a better estimate of a threshold effect for
inflammation and carcinogenesis was done by Kuempel et al. (2001,
Document ID 1082). These researchers studied the minimum human
exposures necessary to achieve adverse functional and pathological
evidence of inflammation. They employed a physiologically-based lung
dosimetry model, included more relevant studies, and considered a
genotoxic effect for lung cancer (Kuempel et al., 2001, Document ID
1082; see 1711, pp. 231-232). Briefly, Kuempel et al. evaluated both
linear and nonlinear (threshold) models and determined that the average
minimum critical quartz lung burden (Mcrit) in rats
associated with reduced pulmonary clearance and increased neutrophil
inflammation was 0.39 mg quartz/g lung tissue. Mcrit is
based on the lowest observed adverse effect level in a study in rats
(Kuempel, 2001, Document ID 1082, pp. 17-23). A human lung dosimetry
model, developed from respirable coal mine dust and quartz exposure and
lung burden data in UK coal miners (Tran and Buchanan, 2001, Document
ID 1126), was then used to estimate the human-equivalent working
lifetime exposure concentrations associated with lung doses. An 8-hour
time-weighted average (TWA) concentration of 0.036 mg/m\3\ (36 [mu]g/
m\3\) over a 45-year working lifetime was estimated to result in a
human-equivalent lung burden to the average Mcrit in rats
(Document ID 1082, pp. 24-26). OSHA peer reviewer Gary Ginsburg, Ph.D.,
summarized, "the Kuempel et al. (2001, 2001b) rat analysis of lung
threshold loading and extrapolation to human dosimetry leads to the
conclusion that in the median case this threshold is approximately 3
times below the current [now former] OSHA PEL" (Document ID 3574, pp.
23). This estimated threshold would be significantly below the final
PEL of 50 [mu]g/m\3\.
In pre-hearing comments, ACC stated that some health organizations
suggested a silicosis-dependent threshold exists for lung cancer (ACC,
Document ID 2307, Attachment A, pp. 60-62). Specifically, ACC cited
Environment and Health Canada as stating:
Although the mechanism of induction for the lung tumours has not
been fully elucidated, there is sufficient supportive mode of action
evidence from the data presented to demonstrate that a threshold
approach to risk assessment is appropriate based on an understanding
of the key events in the pathogenesis of crystalline silica induced
lung tumours (pp. 49-51 as cited by ACC, Document ID 2307, p. 62).
In addition to the statement submitted by ACC, Environment and
Health Canada also stated that:
While there is sufficient evidence to support key events in a
threshold mode of action approach for lung tumours, the molecular
mechanism is still not fully elucidated. Also, despite the fact that
the effects seen in rats parallel the effects observed in human
studies, additional mechanistic studies could further clarify why
lung tumours are not seen in all experimental animals...Thus,
the question of whether silica exposure, in the absence of silicotic
response, results in lung tumours remains unanswered." (pp. 51-52
as cited by ACC, Document ID 2307, pp. 59-61).
It should be noted that the Environment and Health Canada report
was to determine general population risk of exposure to respirable
crystalline silica as a fraction of PM10. Environment and
Health Canada found that levels 0.1-2.1 [mu]g/m\3\ respirable
crystalline silica were sufficiently protective for the general
population because they represented a margin of exposure (MOE) 23-500
times lower than the 50 [mu]g/m\3\ quartz concentration associated with
silicosis in humans (pp. 50-51 as cited by ACC, Document ID 2307, pp.
59-61).
A report by Mossman and Glenn (2013) reviewed the findings from
several international OEL setting panels (Document ID 4070). The report
cites findings from the European Commission's Scientific Committee on
Occupational Exposure Limits for respirable crystalline silica. The
findings "acknowledged a No Observed Adverse Exposure Level (NOAEL)
for respirable crystalline silica in the range below 0.020 mg/m\3\, but
stated that a clear threshold for silicosis could not be identified"
(Mossman and Glen, 2013; Document ID 4070, p. 655). The report went on
to state that SCOEL (2002) recommended that an OEL should lie below 50
[mu]g/m\3\ (Document ID 4070, p. 655). Therefore, even if silica-
induced lung cancer were limited only to a mechanism that involved an
inflammation-dependent threshold, OSHA concludes that exposure
threshold would likely be lower than the final PEL.
5. Renal Disease and Autoimmunity
While mechanistic data is limited, other observed health effects
from inhalation of respirable crystalline silica include kidney and
autoimmune effects. Translocation of particles through the lymphatic
system and filtration through the kidneys may induce effects in the
immune and renal systems similar to the types of changes observed in
the lung (Miller, 2000, Document ID 4174, pp. 40-45). A review of the
available literature indicates that respirable crystalline silica most
likely induces an oxidative stress response in the renal and immune
cells similar to that described above (Donaldson et al., 2009, Document
ID 3894).
6. Conclusion
OSHA has reviewed and responded to the comments received on the
mechanistic studies of respirable crystalline silica-induced lung
cancer and silicosis, as well as comments that the mechanistic data
imply the existence of an exposure threshold. OSHA concludes that: (1)
Lung cancer likely results from both genotoxic and non-genotoxic
mechanisms that arise during early cellular responses as well
as during chronic inflammation from exposure to crystalline silica; (2)
there is not convincing data to demonstrate that silicosis is a
prerequisite for lung cancer; (3) experimental studies in rats are
relevant to humans and provide supporting evidence for carcinogenicity;
(4) crystalline silica does not behave like PSPs such as titanium
dioxide; and (5) any threshold for an inflammatory response to
respirable crystalline silica is likely several times below the final
PEL of 50 [mu]g/m\3\. Thus, the best available evidence on this issue
supports OSHA's findings that respirable crystalline silica increases
the risk of lung cancer in humans, even in the absence of silicosis,
and that lung cancer risk can be increased by exposure to crystalline
silica at or below the new OSHA PEL of 50 [mu]g/m\3\.
I. Comments and Responses Concerning Thresholds for Silica-Related
Diseases
In this section, OSHA discusses comments focused on the issue of
exposure-response thresholds for silica exposure. In the comments
received by OSHA on this topic, an exposure-response "threshold" for
silica exposure typically refers to a level of exposure such that no
individual whose exposure is below that level would be expected to
develop an adverse health effect. Commenters referred to thresholds
both in terms of concentration and cumulative exposure (i.e., a level
of cumulative exposure below which an individual would not be expected
to develop adverse health effects). In addition to individual
thresholds, some commenters referred to a "population average
threshold," that is, the mean or median value of individual thresholds
across a population of workers. There is significant scientific
controversy over whether any such thresholds exist for silicosis and
lung cancer, as well as the cumulative exposure level or concentration
at which a threshold effect may occur and whether certain statistical
modeling approaches can be used to identify threshold effects.
OSHA has reviewed the evidence in the record pertaining to
thresholds, and has determined that the best available evidence
supports the Agency's use of non-threshold exposure-response models in
its risk assessments for silicosis and lung cancer. The voluminous
scientific record accrued by OSHA in this rulemaking supports lowering
the existing PEL to 50 [mu]g/m\3\. Rather than indicating a threshold
of risk that starts above the previous general industry PEL, the weight
of this evidence, including OSHA's own risk assessment models, supports
a conclusion that there continues to be significant, albeit reduced,
risk at the 50 [mu]g/m\3\ exposure limit. OSHA's evaluation of the best
available evidence on thresholds indicates that there is considerable
uncertainty about whether there is any threshold below which silica
exposure causes no adverse health effects; but, in any event, the
weight of evidence supports the view that, if there is a threshold of
exposure for the health effects caused by respirable crystalline
silica, it is likely lower than the new PEL of 50 [mu]g/m\3\.
Commenters have not provided convincing evidence of a population
threshold (e.g., an exposure level safe for all workers) above the
revised PEL. In addition, OSHA's final risk assessment demonstrates
that achieving this limit--which OSHA separately concludes is overall
the lowest feasible level for silica-generating operations--will result
in significant reductions in mortality and morbidity from occupational
exposure to respirable crystalline silica.
1. Thresholds--General
In the Preliminary Quantitative Risk Assessment (QRA) (Document ID
1711, pp. 275, 282-285), OSHA reviewed evidence on thresholds from a
lung dosimetry model developed by Kuempel et al. (2001, Document ID
1082) and from epidemiological analyses conducted by Steenland and
Deddens (2002, Document ID 1124). As discussed in the Preliminary QRA,
Kuempel et al. (2001) used kinetic lung models for both rats and humans
to relate lung burden of crystalline silica and estimate a minimum
critical lung burden (Mcrit) of quartz above which particle
clearance begins to decline and lung inflammation begins to increase
(early steps in the process of developing silica-related disease). The
Mcrit would be achieved by a human equivalent airborne
exposure to 36 [mu]g/m\3\ for 45 years, based on the authors' rat-to-
human lung model conversion. Exposures below this level would not lead
to an excess lung cancer risk in the average individual, if it were
assumed that cancer is strictly a secondary response to persistent
inflammation. OSHA notes, however, that if some of the silica-related
lung cancer risk occurs as a result of direct genotoxicity from early
cellular interaction with respirable silica particles, then this
threshold value may not be applicable. Since silicosis is caused by
persistent lung inflammation, this exposure level could be viewed as a
possible average threshold level for that disease as well (Document ID
1711, p. 284). As 36 [mu]g/m\3\ is well below the previous general
industry PEL of 100 [mu]g/m\3\ and below the final PEL of 50 [mu]g/
m\3\, the Kuempel et al. study showed no evidence of an exposure-
response threshold high enough to impact OSHA's choice of PEL.
Steenland and Deddens (2002, Document ID 1124) examined a pooled
lung cancer study originally conducted by Steenland et al. (2001a).
They found that a threshold model based on the log of cumulative dose
(15-year lag) fit better than a no-threshold model, with the best
threshold at 4.8 log mg/m\3\-days (representing an average exposure of
10 [mu]g/m\3\ over a 45-year working lifetime). OSHA preliminarily
concluded that, in the Kuempel et al. (2001) study and among the
studies evaluated by Steenland et al. (2001a) in the pooled analysis,
there was no empirical evidence of a threshold for lung cancer in the
exposure range represented by the previous and final PELs (i.e., at 50
[mu]g/m\3\ or higher) (Document ID 1711, pp. 275, 284). Thus, based on
these two studies, workers exposed at or below the new PEL of 50 [mu]g/
m\3\ over a working lifetime still face a risk of developing silicosis
and lung cancer because their exposure would be above the supposed
exposure threshold.
In its prehearing comments, the ACC argued that OSHA's examination
of the epidemiological evidence, along with animal studies and
mechanistic considerations, "has not shown that reducing exposures
below currently permitted exposure levels would create any additional
health benefits for workers. OSHA's analysis and the studies on which
it relies have not demonstrated the absence of an exposure threshold
above 100 [mu]g/m\3\ for the various adverse health effects considered
in the QRA" (Document ID 2307, Attachment A, p. 26; also 2348,
Attachment 1, p. 33). According to the ACC, an exposure threshold above
OSHA's previous general industry PEL of 100 [mu]g/m\3\ means that
workers exposed below that level will not get sick, negating the need
to lower the PEL (Document ID 2307, Attachment A, p. 91).
Members of OSHA's peer review panel for the Review of Health
Effects Literature and Preliminary Quantitative Risk Assessment
(Document ID 1711) rejected the ACC's comments as unsupportable. Peer
reviewer Mr. Bruce Allen stated: "it is essentially impossible to
distinguish between dose-response patterns that represent a threshold
and those that do not" in epidemiological data (Document ID 3574, p.
8). Peer reviewer Dr. Kenneth Crump similarly commented:
OSHA is on very solid ground in the [Preliminary QRA's]
statement that "available information cannot firmly establish a
threshold exposure for silica-related effects"...the hypothesis
that a particular dose response does not have a threshold is not
falsifiable. Similarly, the hypothesis that a particular dose response
does have a threshold is not falsifiable (Document ID 3574, p. 17).
Dr. Cox, representing the ACC, agreed with Dr. Crump that "it's
impossible to prove a negative, empirically...you could never rule
out that possibility" of a threshold at a low level of exposure
(Document ID 3576, Tr. 402). However, he contended that it is possible
to rule out a threshold in the higher-level range of observed exposures
based on observed illness: "I think that there are plenty of chemicals
for which the hypothesis of a threshold exist[ing] at or above current
standards could be ruled out because you see people getting sick at
current levels" (Document ID 3576, Tr. 403). Other commenters stated
their belief that workers recently diagnosed with silicosis must have
had exposures above the previous general industry PEL and, based on
this supposition, concluded that OSHA has not definitively proven risk
to workers exposed below the previous general industry PEL (Document ID
4224, pp. 2-5; Tr. 3582, pp. 1951-1963).
OSHA agrees with Dr. Cox that observation of workers "getting sick
at current levels" can rule out a threshold effect at those levels. As
is discussed below, there is evidence that workers exposed to silica at
cumulative or average exposure levels permitted under the previous PELs
have become ill and died as a result of their exposure. OSHA thus
strongly disagrees with any implication from commenters that the Agency
should postpone reducing a PEL until it has extensive documentation of
sick and dying workers to demonstrate that the current PEL is not
sufficiently protective (see Section II, Pertinent Legal Authority, and
Section VI, Final Quantitative Risk Assessment and Significance of
Risk).
The ACC's and Chamber's comments on this issue essentially argue
that the model OSHA used to assess risk was inadequate to assess
whether a threshold of risk exists and, if one does exist, at what
level (Document ID 2307, Attachment A, pp. 52-65; 2376, pp. 20-22;
2330, pp. 17-21). According to OSHA peer reviewer Dr. Crump, however,
the analytical approach taken by OSHA in the Preliminary QRA was
appropriate. Considering the inherent limitations of epidemiological
data:
an attempt to distinguish between threshold and non-threshold dose
responses is not even a scientific exercise...The best that can
be done is to attempt to place bounds on the amount of risk at
particular exposures consistent with the available data, which is
what OSHA had done in their risk assessment (Document ID 3574, p.
17).
A further source of uncertainty in investigating thresholds was
highlighted by Dr. Mirer, on behalf of the AFL-CIO (Document ID 3578,
Tr. 988-989) and by peer reviewer Dr. Andrew Salmon, who stated:
[m]any of the so-called thresholds seen in epidemiological studies
represent thresholds of observability rather than thresholds of
disease incidence...studies (and anecdotal observations) with
less statistical power and shorter post-exposure followup (or none)
will necessarily fail to see the less frequent and later-appearing
responses at lower doses. This creates an apparent threshold which
is higher in these studies than the apparent threshold implied by
studies with greater statistical power and longer follow-up
(Document ID 3574, p. 37).
Peer reviewer Dr. Gary Ginsberg suggested that, recognizing these
inherent limitations, OSHA should characterize the body of evidence and
argument surrounding thresholds by discussing the following factors
related to whether a threshold for silica-related health effects exists
at exposure levels above the previous general industry PEL:
the choices relative to the threshold concept for the silica dose
response...[including] specific dose response datasets that are
consistent with a linear or a threshold-type model, if a threshold
seems likely, where was it seen relative to the current and proposed
PEL, and a general discussion of mechanism of action, measurement
error and population variability as concepts that can help us
understand silica dose response for cancer and non-cancer endpoints
(Document ID 3574, p. 24).
Following Dr. Ginsberg's suggestion, OSHA has, in its final health
and risk analysis, considered the epidemiological evidence relevant to
possible threshold effects for silicosis and lung cancer. As discussed
below, first in "Thresholds--Silicosis and NMRD" and then in
"Thresholds--Lung Cancer," OSHA has carefully considered comments
about statistical methods, exposure measurement uncertainty, and
variability as they pertain to threshold effects. The discussion
addresses the epidemiological evidence with respect to both cumulative
and concentration thresholds. For reference, a working lifetime (45
years) of exposure to silica at the previous general industry PEL (100
[mu]g/m\3\) and the final PEL (50 [mu]g/m\3\) yield cumulative
exposures of 4.5 mg/m\3\-yrs and 2.25 mg/m\3\-yrs, respectively. Other
sections with detailed discussions pertinent to threshold issues
include Section V.H, Mechanisms of Silica-Induced Adverse Health
Effects, and Section V.K, Comments and Responses Concerning Exposure
Estimation Error and ToxaChemica's Uncertainty Analysis.
2. Thresholds--Silicosis and NMRD
OSHA has determined that the studies most relevant to the threshold
issue in this rulemaking are those of workers who have cumulative
exposures or average exposure concentrations below the levels
associated with the previous general industry PEL (100 [mu]g/m\3\, or
cumulative exposure of 4.5 mg/m\3\-yrs). Contrary to comments that OSHA
only relied on studies involving exposures far above the levels of
interest to OSHA in this rulemaking, and then extrapolated exposure-
response relationships down to relevant levels (e.g., Document ID 2307,
Attachment A, pp. 94-95; 4226, p. 2), a number of silicosis studies
included workers who were exposed at levels close to or below the
previous OSHA PEL for general industry. For example, four of the six
cohorts of workers in the pooled silicosis mortality risk analysis
conducted by Mannetje et al. (2002) had median cumulative exposures
below 2.25 mg/m\3\-yrs., and three had median silica concentrations
below 100 [mu]g/m\3\ (Mannetje et al., 2002, Document ID 1089, p. 724).
Other silicosis studies with significant numbers of relatively low-
exposed workers include analyses of German pottery workers (Birk et
al., 2009, Document ID 4002, Attachment 2; Mundt et al., 2011, 1478;
Morfeld et al., 2013, 3843), Vermont granite workers (Attfield and
Costello, 2004, Document ID 0285; Vacek et al., 2011, 1486), and
industrial sand workers (McDonald et al., 2001, Document ID 1091;
Hughes et al., 2001, 1060; McDonald et al., 2005, 1092). In this
section, OSHA will discuss each of them in relationship to whether they
suggest the existence of a threshold above 100 [mu]g/m\3\, the previous
PEL for general industry.
a. Mannetje et al. Pooled Study and Related Analyses
Mannetje et al. (2002b, Document ID 1089) estimated excess lifetime
risk of silicosis based on six of the ten cohorts that were part of the
IARC multi-center exposure-response study (Steenland et al., 2001a,
Document ID 0452). The six cohorts were U.S. diatomaceous earth (DE)
workers, Finnish granite workers, U.S. granite workers, U.S. industrial
sand workers, U.S. gold miners, and Australian gold miners. Together,
the cohorts included 18,634 subjects and 170 silicosis deaths. All
cohorts except the Finnish granite workers and Australian gold miners
had significant numbers of workers with median cumulative and/or
average exposures below the levels associated with OSHA's previous
general industry PEL. Checking for nonlinearities in their
exposure-response model, Mannetje et al. found that a five-knot
cubic spline model (which allows for deviations, such as thresholds,
from a linear relationship) did not fit the data better than the linear
model used in their main analysis. The result of this attempt to check
for nonlinearities suggests that there is no threshold effect in the
relationship between cumulative silica exposure and silicosis risk in
the study. Significantly, NIOSH stated that the results of Mannetje et
al.'s analysis "suggest the absence of threshold at the lowest
[cumulative] exposure analyzed...in fact, the trend for silicosis
mortality risk extends down almost linearly to the lowest cumulative
exposure stratum", in which "the average cumulative exposure is the
equivalent of 45 years of exposure at 11.1 [mu]g/m\3\ silica"
(Document ID 4233, pp. 34-35). This level is significantly below the
new OSHA PEL of 50 [mu]g/m\3\.
As discussed in Section V.K, Comments and Responses Concerning
Exposure Estimation Error and ToxaChemica's Uncertainty Analysis, OSHA
commissioned Drs. Kyle Steenland and Scott Bartell to examine the
potential effects of exposure measurement error on the mortality risk
estimates derived from the pooled studies of lung cancer (Steenland et
al., 2001, Document ID 0452) and silicosis (Mannetje et al., 2002b,
Document ID 1089). Their analysis of the pooled data, using a variety
of standard statistical techniques (e.g., regression analysis), also
found the data either consistent with the absence of a threshold or
inconsistent with the existence of a threshold \8\ (Document ID 0469).
Thus, neither Mannetje et al. nor Steenland and Bartell's analyses of
the pooled cohorts suggested the existence of a cumulative exposure
threshold effect; in fact, they suggested the absence of a threshold.
Given the predominance in these studies of cohorts where at least half
of the workers had cumulative exposures below 4.5 mg/m\3\-yrs, OSHA
believes these results constitute strong evidence against an exposure
threshold above the level of cumulative exposure resulting from long-
term exposure at the previous PEL of 100 [mu]g/m\3\.
---------------------------------------------------------------------------
\8\ This analysis included a log-cumulative logistic regression
model, as well as a categorical analysis and five-knot restricted
cubic spline analysis using log-cumulative exposure. Had the spline
analysis shown a better-fitting model with a flat exposure-response
at low cumulative exposure levels, it might have suggested a
threshold effect for cumulative exposure. However, no significant
difference was observed between the parametric model and the two
other models, which had greater flexibility in the shape of the
exposure-response (Document ID 0469, p. 50, Figure 5).
---------------------------------------------------------------------------
b. Vermont Granite Workers
As discussed in the Supplemental Literature Review of
Epidemiological Studies, Vacek et al. (2011, Document ID 1486) examined
exposures from 1950 to 1999 for a group of 7,052 workers in the Vermont
granite industry (Document ID 1711, Attachment 1, pp. 2-5). The
exposure samples show relatively low exposures for the worker
population. For the period 1950 to 2004, Verma et al. (2012), who
developed the job exposure matrix used by Vacek et al., estimated that
average exposure concentrations in 21 of 22 jobs were below 100 [mu]g/
m\3\, and 11 of the 22 job classes were at 50 [mu]g/m\3\ or below. The
remaining job category, laborer, had an estimated average exposure
concentration of exactly 100 [mu]g/m\3\ (Verma et al., 2011, Document
ID 1487, p. 75).
Six of the 5,338 cohort members hired in or after 1940, when
Vermont's dust control program was in effect, were identified as having
died of silicosis by the end of the follow-up period (Vacek et al.,
Document ID 1486, p. 314). The frequency of observed silicosis
mortality in the population is significant by OSHA standards (1.1 per
1,000 workers), and may be underestimated due to under-reporting of
silicosis as a cause of death (see Section V.E, Comments and Responses
Concerning Surveillance Data on Silicosis Morbidity and Mortality).
This observed silicosis mortality shows that deaths from silicosis
occurred among workers hired after silica concentrations were reduced
below OSHA's previous general industry PEL. It therefore demonstrates
that a threshold for silicosis above 100 [mu]g/m\3\ is unlikely.
In terms of morbidity, Graham et al.'s study of radiographic
evidence of silicosis among retired Vermont granite workers found
silicosis in 5.7 percent of workers hired after 1940 (equivalent to 57/
1,000 workers) (Graham et al., 2004, Document ID 1031, p. 465). OSHA
concludes that these studies of low-exposed workers in the Vermont
granite industry show significant risk of silicosis--both mortality and
morbidity--at concentrations below the previous PELs. These studies
also indicate that a threshold at an exposure concentration
significantly above the previous PEL for general industry, as posited
by industry representatives, is unlikely.
c. U.S. Industrial Sand Workers
In an exposure-response study of 4,027 workers in 18 U.S.
industrial sand plants, Steenland and Sanderson (2001) reported that
approximately three-quarters of the workers with complete work
histories had cumulative exposures below 1.28 mg/m\3\-yrs, well below
the cumulative exposure of 2.25 mg/m\3\-yrs associated with a working
lifetime of exposure at the final PEL of 50 [mu]g/m\3\ (Document ID
0455, p. 700). The study identified fourteen deaths from silicosis and
unspecified pneumoconiosis (~3.5 per 1,000 workers) (Document ID 0455,
p. 700), of which seven occurred among workers with cumulative
exposures below 1.28 mg/m\3\-yrs. As with other reports of silicosis
mortality, this figure may underestimate the true rate of silicosis
mortality in this worker population.
Hughes et al. (2001) reported 32 cases of silicosis mortality in a
cohort of 2,670 workers at nine North American industrial sand plants
(~12 per 1,000) (Document ID 1060, p. 203). The authors developed a
job-exposure matrix based on exposure samples collected by the
companies and by MSHA between 1973 and 1994, along with the 1946
exposure survey used by Steenland and Sanderson (2001, Document ID
0455; 2307, Attachment 7, p. 6). Job histories were available for 29
workers who died of silicosis. Of these, fourteen had estimated
cumulative exposure less than or equal to 5 mg/m\3\-yrs, and seven had
cumulative exposures less than or equal to 1.5 mg/m\3\-yrs (Document ID
1060, p. 204). Both studies clearly showed silicosis risk among workers
whose cumulative exposures were comparable to those that workers could
experience under the final PEL (Document ID 0455, p. 700; 1060, p.
204), indicating that a threshold above this level of cumulative
exposure is unlikely.
d. German Porcelain Workers
A series of papers by Birk et al. (2009, Document ID 4002,
Attachment 2; 2010, Document ID 1467), Mundt et al. (2011, Document ID
1478), and Morfeld et al. (2013, Document ID 3843) examined silicosis
mortality and morbidity in a population of over 17,000 workers in the
German porcelain industry. Cohort members' annual average
concentrations of respirable quartz dust were reconstructed from
detailed work histories and dust measurements collected in the industry
from 1951 onward (Birk et al., 2009, Document ID 4002, Attachment 2,
pp. 374-375). Morfeld et al. observed 40 silicosis morbidity cases (ILO
profusion category 1/1 or greater), and noted that additional
follow-up of the cohort might be necessary due to the long latency
period of silicosis (2013, Document ID 3843, p. 1032).
Follow-up time is a critical factor for detection of silicosis,
which has a typical latency of 20-30 years (see Morfeld et al., 2013,
Document ID 3843, p. 1028). As stated in Section V.C, Summary of the
Review of Health Effects Literature and Preliminary QRA, the disease
latency for silicosis can extend to around 30 years. Follow-up was
extremely limited in the German porcelain workers silicosis morbidity
analysis, with a mean of 7.5 years of follow up for the study
population (Document ID 3843). Despite the limited follow-up time, the
cohort showed evidence of silicosis morbidity among low-exposed
workers: 17.5 percent of cases occurred among workers whose highest
average silica exposure in any year ("highest annual") was estimated
by the authors to be less than 250 [mu]g/m\3\, and 12.5 percent of
cases occurred among workers whose highest annual silica exposure was
estimated at less than 100 [mu]g/m\3\ (Document ID 3843).
The lead author of the study, Dr. Peter Morfeld, testified at the
public hearings on behalf of the ACC Crystalline Silica Panel. In his
post-hearing comments, Dr. Morfeld stated that "[m]echanistic
considerations imply that we should not expect to see a threshold for
cumulative exposure" in silicosis, but that the question of whether a
threshold concentration level may exist remains (Document ID 4003, p.
3). The study by Morfeld et al. "focused on the statistical estimation
of a concentration threshold...[and] simultaneously took into
account the cumulative exposure to respirable crystalline silica dust
as a driving force of the disease" (Document ID 4003, p. 3). Morfeld
et al. applied a technique developed by Ulm et al. (1989, 1991) to
estimate a concentration threshold. In this method a series of
candidate exposure concentration values are subtracted from the
estimated annual mean concentration data. Using the recalculated
exposure estimates for the study population, regression analyses for
each candidate are run to identify the best fitting model, using the
Akaike Information Criterion (AIC) to evaluate model fit (Document ID
3843, p. 1029). According to Morfeld, the best fitting model in their
study estimated a threshold concentration of 250 [mu]g/m\3\ (AIC =
488.3) with a 95 percent confidence interval of 160 to 300 [mu]g/m\3\.
A second model with very similar fit (AIC = 488.8) estimated a
threshold concentration of 200 [mu]g/m\3\ with a 95 percent confidence
interval of 57 [mu]g/m\3\ to 270 [mu]g/m\3\. A third model with a
poorer fit (AIC=490.6) estimated a threshold concentration of 80 [mu]g/
m\3\ with a 95 percent confidence interval of 0.2 [mu]g/m\3\ to 210
[mu]g/m\3\ (Document ID 3843, Table 3, p. 1031).
In the Final Peer Review Report, Dr. Crump stated that Morfeld et
al.'s modeling approach, like "all such attempts statistically to
estimate a threshold," is "not reliable because the threshold
estimates so obtained are highly unstable" (Document ID 3574, p. 17).
Dr. Morfeld's co-author, Dr. Mundt, stated in the public hearings:
I'll be the first one to tell you there is a lot of imprecision
and, therefore, say confidence intervals or uncertainty should be
respected, and that the--I'm hesitant to just focus on a single
point number like the .25 [250 [mu]g/m\3\], and prefer that you
encompass the broader range that was reported in the Morfeld, on
which I was an author and consistently brought this point to the
table (Document ID 3577, Tr. 645).
NIOSH submitted post-hearing comments on the analysis in Morfeld et
al. (2013). NIOSH pointed out that the exposure measurements in the
analysis were based on German dust samplers, which for pottery have
been shown to collect approximately twice as much dust as U.S.
samplers. Therefore, "when Dr. Morfeld cited 0.15 mg/m\3\ (150 [mu]g/
m\3\) as the lower 95% confidence limit for the threshold, that would
convert to 0.075 mg/m\3\ (75 [mu]g/m\3\) in terms of equivalent
measurements made with a U.S. sampler" (Document ID 4233, p. 21).
Similarly, the U.S. equivalent of each of the other threshold estimates
and confidence limits presented in Morfeld et al.'s analysis would be
about half the reported exposure levels. NIOSH also commented that
Morfeld et al.'s analysis appears to be consistent with both threshold
and non-threshold models (Document ID 4233, p. 55). Furthermore, NIOSH
observed that Morfeld et al. did not account for uncertainty in the
values of one of their model parameters ([egr]); therefore their
reported threshold confidence limits of 0.16-0.30 are too narrow
(Document ID 4233, p. 56). More generally, NIOSH noted that Morfeld et
al. did not quantitatively evaluate how uncertainty in exposure
estimates may have impacted the results of the analysis; Morfeld agreed
that he had not performed a "formal uncertainty analysis" (Document
ID 4233, p. 58; 3582, Tr. 2078-2079). NIOSH concluded, "it is our firm
recommendation to discount results based on the model specified in
[Morfeld et al. Eq. 3]...including all results related to a
threshold" (Document ID 4233, p. 58). OSHA has evaluated NIOSH's
comments on the analysis and agrees that the issues raised by NIOSH
raise serious questions about Morfeld et al.'s conclusions regarding a
silica threshold.
OSHA's greater concern with Dr. Morfeld's estimate of 250 [mu]g/
m\3\ as a threshold concentration for silicosis is the fact that a
substantial proportion of workers with silicosis in Dr. Morfeld's study
had no estimated exposure above the threshold suggested by the authors;
this threshold was characterized by commenters, including the Chamber
of Commerce (Chamber), as a concentration "below which the lung
responses did not progress to silicosis" (Document ID 4224, Attachment
1, p. 3). This point was emphasized by Dr. Brian Miller in the Final
Peer Review Report (Document ID 3574, p. 57) and by NIOSH (Document ID
4233, p. 57). In the study, 17.5 percent of workers with silicosis were
classified as having no exposure above Morfeld et al.'s estimated
threshold of 250 [mu]g/m\3\, (Document ID 3843, p. 1031) and 12.5
percent of these workers were classified as having no exposure above
100 [mu]g/m\3\. OSHA believes the presence of these low-exposed workers
with silicosis clearly contradicts the authors' estimate of 250 [mu]g/
m\3\ as a level of exposure below which no worker will develop
silicosis (see Document ID 4233, p. 57).
In a post-hearing comment, Dr. Morfeld offered a different
interpretation of his results, describing his threshold estimate as a
"population average" which would not be expected to characterize risk
for all individuals in a population. Rather, according to Dr. Morfeld
"we expect to see differences in response thresholds among subjects"
(Document ID 4003, p. 5). OSHA agrees with this interpretation, which
was similarly expressed in several comments from OSHA's peer reviewers
on the subject of thresholds (e.g., Document ID 3574, pp. 13, 21-22).
Consistent with its peer reviewers' opinions, OSHA draws the conclusion
from the data and discussion concerning population averages that these
"differences in response thresholds among subjects" support setting
the PEL at 50 [mu]g/m\3\ in order to protect the majority of workers in
the population of employees exposed to respirable crystalline silica.
OSHA's review of the Morfeld et al. data on German porcelain workers
thus reinforces its view that reducing exposures to this level will
benefit the many workers who would develop silicosis at exposure levels
below that of the "average" worker.
Dr. Morfeld's discussion of his estimate as a "population
average" among workers with different individual responses to silica
exposure echoes several comments from OSHA's peer reviewers on the subject of
thresholds. In the Final Peer Review Report, Dr. Ginsberg observed that
a linear exposure-response model may reflect a distribution of
individual "thresholds," such that "the population can be
characterized as having a distribution of vulnerability. This
distribution may be due to differences in levels of host defenses that
come with differences in age, co-exposure to other chemicals, the
presence of interacting background disease processes, non-chemical
stressors, and a variety of other host factors" (Document ID 3574, p.
21). Given the number of factors that may influence vulnerability to
certain diseases in a population of workers, Dr. Ginsberg continued:
it is logical for OSHA to strongly consider inter-subject
variability...as the reason for linearly-appearing regression
slopes in silica-related non-cancer and cancer studies. This
explanation does not imply an artifact [that is, a false appearance
of linear exposure-response] but that the linear (or log linear)
regression coefficient extending down to low dose reflects the
inherent variability in susceptibility such that the effect of
concern...may occur in some individuals at doses well below what
might be a threshold in others (Document ID 3574, pp. 21-22).
Peer reviewer Mr. Bruce Allen agreed that "[i]t makes no sense to
discuss a single threshold value...Given, then, that thresholds
must be envisioned as a distribution in the population, then there is
substantial population-level risk even at the mean threshold value, and
unacceptably high risk levels at exposures far below the mean
threshold." He further stated:
It is NOT, therefore, inappropriate to model the population-
level observations using a non-threshold model...In fact, I
would claim that it is inappropriate to include ANY threshold models
(i.e., those that assume a single threshold value) when modeling
epidemiological data. A non-threshold model for characterizing the
population dose-response behavior is theoretically and practically
the optimal approach (Document ID 3574, p. 13).
OSHA concludes that this German porcelain workers cohort shows
evidence of silicosis among workers exposed at levels below the
previous PELs, and that continued follow-up of this cohort would be
likely to show greater silicosis risk among low-exposed workers due to
the short follow-up time. Furthermore, the Chamber's characterization
of Dr. Morfeld's result as "a threshold concentration of 250 [mu]g/
m\3\ below which the lung responses did not progress to silicosis"
(Document ID 4224, p. 3) is plainly inaccurate, as the estimated
exposures of a substantial proportion of the workers with silicosis in
the data set did not exceed this level.
e. Park et al. (2002)
The ACC submitted comments on the Park et al. (2002, Document ID
0405) study which examined silicosis and lung disease other than cancer
(i.e., NMRD) in a cohort of diatomaceous earth workers. The ACC's
comments on this study are discussed in detail in Section V.D, Comments
and Responses Concerning Silicosis and Non-Malignant Respiratory
Disease Mortality and Morbidity, including comments relating to
exposure-response thresholds in this study. Briefly, the ACC claimed
that the Park et al. (2002) study is "fully consistent" with
Morfeld's estimate of a threshold above the 100 [mu]g/m\3\
concentration for NMRD, including silicosis, mortality (Document ID
2307, Attachment A, p. 107). However, NIOSH explained in its post-
hearing brief that categorical analysis for NMRD indicated no threshold
existed at or above a cumulative exposure corresponding to 25 [mu]g/
m\3\ over 40 years of exposure, which is below the cumulative exposure
equivalent to the new PEL over 45 years (Document ID 4233, p. 27). Park
et al. did not attempt to estimate a threshold below that level because
the data lacked the power needed to discern a threshold (Document ID
4233, p. 27). OSHA agrees with NIOSH's assessment, which indicates
that, if there is a cumulative exposure threshold for NMRD, including
silicosis, it is significantly below the final PEL of 50 [mu]g/m\3\.
f. Conclusion--Silicosis and NMRD
OSHA concludes that the body of epidemiological literature clearly
demonstrates risk of silicosis and NMRD morbidity and mortality among
workers who have been exposed to cumulative exposures or average
exposure concentrations at or below the levels associated with the
previous general industry PEL (100 [mu]g/m\3\, or cumulative exposure
of 4.5 mg/m\3\-yrs). Thus, OSHA does not agree with commenters who have
stated that the previous general industry PEL is fully protective and
that reducing it will yield no health benefits to silica-exposed
workers (e.g., Document ID 4224, p. 2-5; Tr. 3582, pp. 1951-1963).
Instead, the Agency finds that the evidence is at least as consistent
with a finding that no threshold is discernible as it is with a finding
that a threshold exists at some minimal level of exposure. The best
available evidence also demonstrates silicosis morbidity and mortality
below the previous PEL of 100 [mu]g/m\3\, indicating that any threshold
for silicosis (understood as an exposure level below which no one would
develop disease), if one exists, is below that level. Even if the
conclusion reached by Dr. Morfeld that a population average threshold
exists above the level of the previous PEL is accurate, there will
still be a substantial portion of the population who will develop
silicosis from exposures below the identified "threshold." These
findings support OSHA's action in lowering the PEL to 50 [mu]g/m\3\.
3. Thresholds--Lung Cancer
OSHA's Preliminary QRA and supplemental literature review included
several studies that provide information on possible threshold effects
for lung cancer. OSHA has determined that the epidemiological studies
most relevant to the threshold issue are those with workers who have
cumulative exposures or average exposure concentrations below the
levels associated with the previous general industry PEL (100 [mu]g/
m\3\, or cumulative exposure of 4.5 mg/m\3\-yrs). As with the silicosis
studies previously discussed, contrary to comments that OSHA only
relied on studies involving exposures far above the levels of interest
to OSHA in this rulemaking (e.g., Document ID 2307, Attachment A, pp.
94-95; 4226, p. 2), a number of lung cancer studies included workers
who were exposed at levels close to or below the previous general
industry PEL. Five of the 10 cohorts of workers in the pooled lung
cancer risk analysis conducted by Steenland et al. (2001a) had median
cumulative exposures below 4.5 mg/m\3\-yrs (the cumulative level
associated with a working lifetime of exposure at the previous general
industry PEL); four were also below 2.25 mg/m\3\-yrs (the cumulative
level associated with a working lifetime of exposure at the revised
PEL) and three had median silica concentrations below 100 [mu]g/m\3\
(Document ID 0452, p. 775). Other lung cancer studies with significant
numbers of relatively low-exposed workers include analyses of the
Vermont granite workers (Attfield and Costello, 2004, Document ID 0285;
Vacek et al., 2011, 1486) and industrial sand workers (McDonald et al.,
2001, Document ID 1091; Hughes et al., 2001, 1060; McDonald et al.,
2005, 1092) described in the previous discussion on silicosis. In
addition to the epidemiological studies discussed here, in Section V.H,
Mechanisms of Silica-Induced Adverse Health Effects, OSHA discussed
studies that have shown direct genotoxic mechanisms by which exposure
to crystalline silica at any level, with no threshold effect, may lead
to lung cancer.
a. Steenland et al. Pooled Lung Cancer Study and Related Analyse
Steenland et al. (2001a) estimated excess lifetime risk of lung
cancer based on a 10-cohort pooled study, which included several
cohorts with significant numbers of workers with median cumulative and
average exposures below those allowed by the previous general industry
PEL (Document ID 0452). Results indicated that 45 years of exposure at
0.1 mg/m\3\ (100 [mu]g/m\3\) would result in a lifetime risk of 28
excess lung cancer deaths per 1,000 workers (95% confidence interval
(CI) 13-46 per 1,000). An alternative (non-linear) model yielded a
lower risk estimate of 17 per 1,000 (95% CI 2-36 per 1,000).
A follow-up letter by Steenland and Deddens (2002, Document ID
1124) addressed the possibility of an exposure threshold effect in the
pooled lung cancer analysis conducted by Steenland et al. in 2001.
According to Dr. Steenland, "We further investigated whether there was
a level below which there was no increase in risk, the so-called
threshold. So we fit models that had a threshold versus those that
didn't, and we explored various thresholds that might apply" (Document
ID 3580, Tr. 1229). Threshold models using average exposure and
cumulative exposure failed to show a statistically significant
improvement in fit over models without a threshold. However, the
authors found that when they used the log of cumulative exposure (a
transformation commonly used to reduce the influence of high exposure
points on a model), a threshold model with a 15-year lag fit better
than a no-threshold model. The authors reported the best threshold
estimate at 4.8 log mg/m\3\-days (Document ID 1124, p. 781), or an
average exposure of approximately 10 [mu]g/m\3\ over a 45-year working
lifetime, one-fifth of the final PEL. Dr. Steenland explained what his
analysis indicated regarding a cumulative exposure threshold for lung
cancer: "we found, in fact, that there was a threshold model that fit
better than a no-threshold model, not enormously better but better
statistically, but that threshold was extremely low...far below the
...silica standard proposed by OSHA" (Document ID 3580, Tr. 1229).
In response to comments from ACC Panel members Dr. Valberg and Dr.
Long that the analysis presented by Steenland et al. showed a clear
threshold at a level of cumulative exposure high enough to bear on
OSHA's choice of PEL (Document ID 2330, p. 20), Dr. Steenland explained
that their conclusion was based on a misreading of an illustration in
his study:
[I]f you look at the figure, you see that the curve of the
spline [a flexible, nonlinear exposure-response model] starts to go
up around four on the log scale of microgram per meter cubed days.
And if you transform that from the log to the regular scale, that is
quite consistent with the threshold we got when we did a formal
analysis using the log transform model [discussed above] (Document
ID 3580, Tr. 1255).
The ACC representatives' comments do appear to be based on a
misunderstanding of the figure in question, due to an error in Dr.
Steenland's 2001 publication in which the axis of the figure under
discussion was incorrectly labeled. This error was later corrected in
an erratum (Document ID 3580, Tr. 1257; Steenland et al., 2002,
Erratum. Cancer Causes Control, 13:777).
In addition, at OSHA's request, Drs. Steenland and Bartell
(ToxaChemica, 2004, Document ID 0469) conducted a quantitative
uncertainty analysis to examine the effects of possible exposure
measurement error on the pooled lung cancer study results (see Section
V.K, Comments and Responses Concerning Exposure Estimation Error and
ToxaChemica's Uncertainty Analysis). These analyses showed no evidence
of a threshold effect for lung cancer at the final or previous PELs.
Based on Dr. Steenland's work, therefore, OSHA believes that no-
threshold models are appropriate for evaluating the exposure-response
relationship between silica exposure and lung cancer. Even if
commenters are correct that threshold models are preferable, the
threshold is likely at a level of cumulative exposure significantly
below what a worker would accumulate in 45 years of exposure at the
final PEL, and is therefore immaterial to this rulemaking (see Document
ID 1124, p. 781).
b. Vermont Granite Workers
In the Preliminary QRA and supplemental literature review, OSHA
reviewed several studies on lung cancer among silica-exposed workers in
the Vermont granite industry, whose exposures were reduced to
relatively low levels due to a program for dust control initiated in
1938-1940 by the Vermont Division of Industrial Hygiene (Document ID
1711, pp. 97-102; 1711, Attachment 1, pp. 2-5; 1487, p. 73). As
discussed above, Verma et al. (2012) reported that all jobs in the
industry had average exposure concentrations at or below 100 [mu]g/
m\3\--most of them well below this level--in the time period 1950-2004
after implementation of exposure controls (Document ID 1487, Table IV,
p. 75).
Attfield and Costello (2004) examined a cohort of 5,414 Vermont
granite workers, including 201 workers who died of lung cancer
(Document ID 0285, pp. 130, 134). In this study, cancer risk was
elevated at cumulative exposure levels below 4.5 mg/m\3\-yrs, the
amount of exposure that would result from a 45-year working lifetime of
exposure at the previous PEL. The authors reported elevated lung cancer
in all exposure groups, observing statistically significant elevation
among workers with cumulative exposures between 0.5 and 1 mg/m\3\-yrs
(p < 0.05), cumulative exposures between 2 and 3 mg/m\3\-yrs (p <
0.01), and cumulative exposures between 3 and 6 mg/m\3\-yrs (p < 0.05)
(Document ID 0285, p. 135). These findings indicate that a threshold in
exposure-response for lung cancer is unlikely at cumulative exposure
levels associated with 45 years of exposure at the previous PEL and
below.
Vacek et al. (2011) examined a group of 7,052 men, overlapping with
the Attfield and Costello cohort, who worked in the Vermont granite
industry at any time between January 1, 1947 and December 31, 1998
(Document ID 1486). Like Attfield and Costello, Vacek et al. reported
significantly elevated lung cancer (p < 0.01) (Document ID 1486, p.
315). Most of the lung cancer cases in Vacek et al. (305/356) had
cumulative exposures less than or equal to 4.1 mg/m\3\-yrs (Document ID
1486, p. 316), below the cumulative exposure level of 4.5 mg/m\3\-yrs
associated with 45 years of exposure at the previous PEL and below.
However, unlike Attfield and Costello, Vacek et al. did not find a
statistically significant relationship of increasing lung cancer risk
with increasing silica exposure, leading Vacek et al. to conclude that
increased lung cancer mortality in the cohort may not have been due to
silica exposure (Document ID 1486, p. 312).
The strengths and weaknesses of both studies and the differences
between them that could account for their conflicting conclusions were
discussed in great detail in Section V.F, Comments and Responses
Concerning Lung Cancer Mortality. For the purpose of evaluating the
effects of low concentrations of silica exposure, as well as whether a
threshold exposure exists, OSHA believes the Attfield and Costello
study may merit greater weight than Vacek et al. As discussed in
Section V.F, Comments and Responses Concerning Lung Cancer Mortality,
OSHA believes Attfield and Costello's choice to exclude the highest
exposure group from their analysis likely improved their study's
estimate of the exposure-response relationship at lower exposures; by
making this choice, they limited the influence of highly uncertain
exposure estimates at higher levels and helped to reduce the impact of
the healthy worker survivor effect. The Agency acknowledges the
strengths of the Vacek et al. analysis as well, including longer
follow-up of workers.
In conclusion, OSHA does not find compelling evidence in these
studies of Vermont granite workers of a cumulative exposure threshold
for lung cancer in the exposure range below the previous general
industry PEL. This conclusion is based on the statistically significant
elevations in lung cancer reported in both cohorts described above,
which were composed primarily of workers whose cumulative exposures
were below the level associated with a working lifetime of exposure.
However, OSHA acknowledges that a strong conclusion regarding a
threshold is difficult to draw from these studies, due to the
disagreement between Attfield and Costello and Vacek et al. regarding
the likelihood that excess lung cancer among Vermont granite workers
was due to their silica exposures.
c. Industrial Sand Workers
OSHA's Preliminary QRA (Document ID 1711, pp. 285-287) evaluated a
2001 case-control analysis of industrial sand workers including 2,640
men employed before 1980 for at least three years in one of nine North
American sand-producing plants. One of the sites was a large associated
office complex where workers' exposures were lower than those typically
experienced by production workers (Hughes et al., 2001, Document ID
1060). A later update by McDonald et al. (2005, Document ID 1091)
eliminated one plant, following 2,452 men from the 8 remaining U.S.
plants. Both cohorts overlapped with an earlier industrial sand cohort,
including 4,626 workers at 18 plants, which was included in Steenland
et al.'s pooled analysis (2001a, Document ID 0452). OSHA noted that
these studies (Hughes et al., 2001, Document ID 1060; McDonald et al.,
2005, 1092; Steenland and Sanderson, 2001, 0455) showed similar
exposure-response patterns of increased lung cancer mortality with
increased exposure.
In the Final Peer Review Report, Dr. Ginsberg commented on the
relevance of the industrial sand cohort studies, which included low-
exposed workers with exceptionally well-characterized exposures, for
threshold issues:
With respect to the body of silica epidemiology literature,
perhaps the case with the least amount of measurement error is of US
industrial sand workers wherein many measurements were made with
filter samples and SRD determination of crystalline silica and in
which there was very careful estimation of historical exposure for
both silica and smoking (MacDonald et al. 2005; Steenland and
Sanderson 2001; Hughes et al. 2001) (Document ID 3574, pp. 22-23).
OSHA agrees with Dr. Ginsberg's assessment of these studies and has
found them to be particularly high quality. Thus, the Agency was
especially interested in the studies' findings, which showed that
cancer risk was elevated at cumulative exposure levels below 4.5 mg/
m\3\-yrs, the amount of exposure that would result from a 45-year
working lifetime of exposure at the previous PEL. OSHA believes these
results provide strong evidence against a threshold in cumulative
exposure at any level high enough to impact OSHA's choice of PEL. Dr.
Ginsberg agrees with OSHA's conclusion (Document ID 3574, p. 23).
d. Other Studies
Comments submitted by the ACC briefly mentioned several
epidemiological studies that, they claim, "suggest the existence of a
threshold for any increased risk of silica-related lung cancer,"
including studies by Sogl et al. (2012), Mundt et al. (2011), Pukkala
et al. (2005), Calvert et al. (2003), Checkoway et al. (1997), and
Steenland et al. (2001a). OSHA previously reviewed several of these
studies in the Review of Health Effects Literature and Preliminary
Quantitative Risk Assessment, and the Supplemental Literature Review,
though not with specific attention to their implications for exposure-
response thresholds (Document ID 1711, pp. 139-155; 1711, Attachment 1,
pp. 6-12). The studies cited by ACC are discussed below, with the
exception of Steenland et al. (2001a), which was previously reviewed in
this section.
e. German Porcelain Workers
OSHA reviewed Mundt et al. (2011, Document ID 1478) in its
Supplemental Literature Review (Document ID 1711, Attachment 1, pp. 6-
12). As discussed there, Mundt et al. examined the risks of silicosis
morbidity and lung cancer mortality in a cohort of 17,644 German
porcelain manufacturing workers who had participated in medical
surveillance programs for silicosis between 1985 and 1987. This cohort
was also examined in a previous paper by Birk et al. (2009, Document ID
4002, Attachment 2).
Quantitative exposure estimates for this cohort showed an average
annual exposure of 110 [mu]g/m\3\ for workers hired prior to 1960 and
an average of 30 [mu]g/m\3\ for workers hired after 1960. More than 40
percent of the cohort had cumulative exposures less than 0.5 mg/m\3\-
yrs at the end of follow-up, and nearly 70 percent of the cohort had
average annual exposures less than 50 [mu]g/m\3\ (Mundt et al., 2011,
Document ID 1478, pp. 283-284).
The lung cancer mortality hazard ratios (HRs) associated with
average annual exposure were statistically significant in two of the
four average annual exposure groups: 2.1 (95% CI 1.1-4.0) for average
annual exposure group >50-100 [mu]g/m\3\ and 2.4 (95% CI 1.1-5.2) for
average annual exposure group >150-200 [mu]g/m\3\, controlling for age,
smoking, and duration of employment. In contrast, the HRs for lung
cancer mortality associated with cumulative exposure were not
statistically elevated after controlling for age and smoking.
The authors suggested the possibility of a threshold for lung
cancer mortality. However, no formal threshold analysis for lung cancer
was conducted in this study or in the follow-up threshold analysis
conducted on this population by Morfeld et al. for silicosis (2013,
Document ID 4175). Having reviewed this study carefully, OSHA believes
it is inconclusive on the issue of thresholds due to the elevated risk
of lung cancer seen among low-exposed workers (for example, those with
average exposures of 50-100 [mu]g/m\3\), which is inconsistent with the
ACC's claim that a threshold exists at or above the previous PEL of 100
[mu]g/m\3\, and due to several limitations which may preclude detection
of a relationship between cumulative exposure and lung cancer in this
cohort. As discussed in the Preliminary QRA, these include: (1) A
strong healthy worker effect observed for lung cancer; (2) Mundt et al.
did not follow the typical convention of considering lagged exposures
to account for disease latency; and (3) the relatively young age of
this cohort (median age 56 years old at time of silicosis
determination) (Document ID 1478, p. 288) and limited follow-up period
(average of 19 years per subject) (Birk et al. 2009, Document ID 4002,
Attachment 2, p. 377). Only 9.2 percent of the cohort was deceased by
the end of the follow up period. Mundt et al. (2011) acknowledged this
limitation, stating that the lack of increased risk of lung cancer was
a preliminary finding (Document ID 1478, p. 288).
f. German Uranium Miners
In pre-hearing comments, Dr. Morfeld described a study of 58,677
German uranium miners by Sogl et al. (2012, Document ID 3842; 2307, Attachment 2, p. 11).
Dr. Morfeld noted that the study was based on a detailed exposure
assessment of respirable crystalline silica (RCS) dust. According to
Dr. Morfeld, Sogl et al. "showed that no lung cancer excess risk was
observed at RCS dust exposure levels below 10 mg/m\3\-years"
(Document ID 2307, Attachment 2, p. 11). OSHA's review of this publication
confirmed that the authors reported a spline function with a single
knot at 10 mg/m\3\-yrs, which Morfeld interprets to suggest a threshold
for lung cancer of approximately 250 [mu]g/m\3\ average exposure concentration
for workers exposed over the course of 40 years. However, the authors also noted
that an increase in risk below this level could not be ruled out due to
strong confounding with radon, resulting in possible over-adjustment
(Sogl et al., Document ID 3842, p. 9). That is, because workers with
high exposures to silica would also have had high exposures to the lung
carcinogen radon, the models used by Sogl et al. may have been unable
to detect a relationship between silica and lung cancer in the presence
of radon. As described previously, excess lung cancer has been observed
among workers with lower cumulative exposures than the Sogl et al.
"threshold" in other studies which do not suffer from confounding
from potent lung carcinogens other than silica (for example, industrial
sand workers), and which are, therefore, likely to provide more
reliable evidence on the issue of thresholds. OSHA concludes that the
Sogl et al. study does not provide convincing evidence of a cumulative
exposure threshold for lung cancer.
g. U.S. Diatomaceous Earth Workers
Checkoway et al. (1997) investigated the risk of lung cancer among
diatomaceous earth (DE) workers exposed to respirable cristobalite (a
type of silica found in DE) (Document ID 0326; 1711, pp. 139-143).
Exposure samples were collected primarily at one of the two plants in
the study by plant industrial hygienists over a 40-year timeframe from
1948 to 1988 and used to estimate exposure for each individual in the
cohort (Seixas et al., 1997, Document ID 0431, p. 593). Based on 77
deaths from cancer of the trachea, lung, and bronchus, the standardized
mortality ratios (SMR) were 129 (95% CI 101-161) and 144 (95% CI 114-
180) based on rates for U.S. and local county males, respectively
(Document ID 0326, pp. 683-684). The authors found a positive, but not
monotonic, exposure-response trend for lung cancer. The risk ratios for
lung cancer with increasing quintiles of respirable crystalline silica
exposure were 1.00, 0.96, 0.77, 1.26 and 2.15 with a 15-year exposure
lag. Lung cancer mortality was thus elevated for workers with
cumulative exposures greater than 2.1 mg/m\3\-yrs, but was only
statistically significantly elevated for the highest exposure category
(RR = 2.15; 95% CI 1.08-4.28) (Document ID 0326, p. 686). OSHA notes
that this highest exposure category includes cumulative exposures only
slightly higher than 4.5 mg/m\3\-yrs, the level of cumulative exposure
resulting from a 45-year working lifetime at the previous PEL of 100
[mu]g/m\3\. OSHA does not believe that the appearance of a
statistically significantly elevated lung cancer risk in the highest
category should be interpreted as evidence of an exposure-response
threshold, especially in light of the somewhat elevated risk seen at
lower exposure levels. OSHA believes it is more likely to reflect
limited power to detect excess risk at lower exposure levels, a common
issue in epidemiological studies which was emphasized by peer reviewer
Dr. Andrew Salmon in relation to purported thresholds (Document ID
3574, p. 37).
h. Finnish Nationwide Job Exposure Matrix
OSHA reviewed Pukkala et al. (2005, Document ID 0412) in the Review
of Health Effects Literature and Preliminary Quantitative Risk
Assessment (Document ID 1711, pp. 153-154). As discussed there, Pukkala
et al. (2005) evaluated the occupational silica exposure among all
Finns born between 1906 and 1945 who participated in a national
population census on December 31, 1970. Follow-up of the cohort was
through 1995. Between 1970 and 1995, there were 30,137 cases of
incident lung cancer among men and 3,527 among women. Exposure data
from 1972 to 2000 was collected by the Finnish Institute of
Occupational Health (FIOH). Cumulative exposure categories for
respirable quartz were defined as: <1.0 mg/m\3\-yrs (low), 1.0-9.9 mg/
m\3\-yrs (medium) and >10 mg/m\3\-yrs (high). For men, over 18 percent
of the 30,137 lung cancer cases worked in occupations with potential
exposure to silica dust. The cohort showed statistically significantly
increased lung cancer among men in the lowest occupationally exposed
group (those with less than 1.0 mg/m\3\-yrs cumulative silica
exposure), as well as for men with exposures in the two higher groups
(1.0-9.9 mg/m\3\-yrs and >10 mg/m\3\-yrs). For women, the cohort showed
statistically significantly increased lung cancer among women with at
least 1.0 mg/m\3\-yrs cumulative silica exposure. Given these results,
it is unclear why ACC stated that Pukkula's results suggest that
"excess risk of lung cancer is mainly attributable to...cumulative
exposure exceeding 10 mg/m\3\-years" (Document ID 4209, p. 54).
Indeed, Pukkula's analysis appears to show excess risk of lung cancer
among men with any level of occupational exposure and among women whose
cumulative exposures were quite low (at least equivalent to about 25
[mu]g/m\3\ over 45 years). It does not support the ACC's contention
that lung cancer is seen primarily in workers with exposures greater
than 200 [mu]g/m\3\ (Document ID 4209, p. 54), but rather suggests that
any threshold for lung cancer risk would likely be well below 100
[mu]g/m\3\.
i. U.S. National (27 states) Case-Control Study
As discussed in the Review of Health Effects Literature and
Preliminary Quantitative Risk Assessment (Document ID 1711, pp. 152-
153), Calvert et al. (2003, Document ID 3890) conducted a case-control
study using 4.8 million death certificates from the National
Occupational Mortality Surveillance data set. Death certificates were
collected from 27 states covering the period from 1982 to 1995. Cases
were persons who had died from any of several diseases of interest:
Silicosis, tuberculosis, lung cancer, chronic obstructive pulmonary
disease (COPD), gastrointestinal cancers, autoimmune-related diseases,
or renal disease. Worker exposure to crystalline silica was categorized
as no/low, medium, high, or super-high based on their industry and
occupation. The authors acknowledged the potential for confounding by
higher smoking rates for cases compared to controls, and partially
controlled for this by eliminating white-collar workers from the
control group in the analysis. Following this adjustment, the authors
reported weak, but statistically significantly elevated, lung cancer
mortality odds ratios (OR) of 1.07 (95% CI 1.06-1.09) and 1.08 (95% CI
1.01-1.15) for the high- and super-high exposure groups, respectively
(Calvert et al., 2003, Document ID 3890, p. 126). Upon careful review
of this study, OSHA maintains its position that it should not be used
for quantitative risk analysis (including determination of threshold
effects) because it lacks an exposure characterization based on
sampling. Any determination regarding the existence or location of a
threshold based on Calvert et al. (2003) must, therefore, be considered
highly speculative.
j. Conclusion--Lung Cancer
In conclusion, OSHA has determined that the best available evidence
on the issue of a threshold for silica-related lung cancer does not
support the ACC's contention that an exposure-response threshold, below
which respirable crystalline silica exposure is not expected to cause
cancer, exists at or above the previous general industry PEL of 100
[mu]g/m3. While there are some studies that claim to point
to thresholds above the previous general industry PEL, multiple studies
contradict this evidence, most convincingly through evidence that
cohort members with low cumulative silica exposures suffered from lung
cancer as a result of their exposure. These studies indicate that there
is either no threshold for silica-related lung cancer, or that this
threshold is at such a low level that workers cumulatively exposed at
or below the level allowed by the new PEL of 50 [mu]g/m3
will still be at risk of developing lung cancer. Thus, OSHA does not
agree with commenters who have stated that the previous general
industry PEL is fully protective and that reducing it will yield no
health benefits to silica-exposed workers (e.g., Document ID 4224, p.
2-5; Tr. 3582, pp. 1951-1963).
4. Exposure Uncertainty and Thresholds
In his pre-hearing comments, Dr. Cox stated that the observation of
a positive and monotonic exposure-response relationship in
epidemiological studies "does not constitute valid evidence against
the hypothesis of a threshold," and that OSHA's findings of risk at
exposures below the previous PEL for general industry "could be due
simply to exposure misclassification" in studies of silica-related
health effects in exposed workers (Document ID 2307, Attachment 4, pp.
41-42). His statements closely followed his analyses from a 2011 paper,
in which Cox presented a series of simulation analyses designed to show
that common concerns in epidemiological analyses, such as uncontrolled
confounding, errors in exposure estimates, and model specification
errors, can obscure evidence of an exposure-response threshold, if such
a threshold exists (Document ID 3600, Attachment 7). Dr. Cox concluded
that the currently available epidemiological studies "do not provide
trustworthy information about the presence or absence of thresholds in
exposure-response relations" with respect to an exposure concentration
threshold for lung cancer (Document ID 3600, Attachment 7, p. 1548).
OSHA has reviewed Dr. Cox's comments and testimony, and concludes
that uncertainty about risk due to exposure estimation and confounding
cannot be resolved through the application of the statistical
procedures recommended by Dr. Cox. (Similar comments from Dr. Cox about
alleged biases in the studies relied upon are addressed in the next
section, where OSHA reaches similar conclusions). A reviewer on the
independent peer review panel, Dr. Ginsberg, commented that:
epidemiology studies will always have issues of exposure
misclassification or other types of error that may create
uncertainty when it comes to model specification. However, these
types of error will also bias correlations to the null such that if
they were sufficiently influential to obscure a threshold they may
also substantially weaken regression results and underestimate the
true risk (Document ID 3574, p. 23).
OSHA agrees with Dr. Ginsberg. As discussed in Section V.K,
Comments and Responses Concerning Exposure Estimation Error and
ToxaChemica's Uncertainty Analysis, a "gold standard" exposure sample
is not available for the epidemiological studies in the silica
literature, so it is not possible to determine the direction or
magnitude of the effects of exposure misclassification on OSHA's risk
estimates. The silica literature is not unique in this sense. As stated
by Mr. Robert Park of NIOSH, "modeling exposure uncertainty as
described by Dr. Cox...is infeasible in the vast majority of
retrospective observational studies. Nevertheless, mainstream
scientific thought holds that valid conclusions regarding disease
causality can still be drawn from such studies" (Document ID 4233, p.
32).
For the reasons discussed throughout this analysis of the
scientific literature, OSHA concludes that, even acknowledging a
variety of uncertainties in the studies relied upon, these
uncertainties are, for the most part, typical or inherent in these
types of studies. OSHA therefore finds that the weight of evidence in
these studies, representing the best available evidence on the health
effects of silica exposure, strongly supports the findings of
significant risk from silicosis, NMRD, lung cancer, and renal disease
discussed in this section and in the quantitative risk assessment that
follows in the next section (see Benzene, 448 U.S. at 656 ("OSHA is
not required to support its finding that a significant risk exists with
anything approaching scientific certainty. Although the Agency's
findings must be supported by substantial evidence, 29 U.S.C. 655(f),
6(b)(5) specifically allows the Secretary to regulate on the basis of
the `best available evidence.' ")).
5. Conclusion
In summary, OSHA acknowledges that common issues with
epidemiological studies limit the Agency's ability to determine whether
and where a threshold effect exists for silicosis and lung cancer.
However, as shown in the foregoing discussion, there is evidence in the
epidemiological literature that workers exposed to silica at
concentrations and cumulative levels allowable under the previous
general industry PEL not only develop silicosis, but face a risk of
silicosis high enough to be significant ( >1 per 1,000 exposed
workers). Although the evidence is less clear for lung cancer, studies
nevertheless show excess cases of lung cancer among workers with
cumulative exposures in the range of interest to OSHA. Furthermore, the
statistical model-based approaches proposed in public comments do not
demonstrate the existence or location of a "threshold" level of
silica exposure below which silica exposure is harmless to workers. The
above considerations lead the Agency to conclude that any possible
exposure threshold is likely to be at a low level, such that some
workers will continue to suffer the health effects of silica exposure
even at the new PEL of 50 [mu]g/m3.
There is a great deal of argument and analysis directed at the
question of thresholds in silica exposure-response relationships, but
nothing like a scientific consensus about the appropriate approach to
the question has emerged. If OSHA were to accept the ACC's claim that
exposure to 100 [mu]g/m3 silica is safe for all workers (due
to a threshold at or above an exposure concentration of 100 [mu]g/
m3) and set a PEL at 100 [mu]g/m3 for all
industry sectors, and if that claim is in fact erroneous, the
consequences of that error to silica-exposed workers would be grave. A
large population of workers would remain at significant risk of serious
occupational disease despite feasible options for exposure reduction.
J. Comments and Responses Concerning Biases in Key Studies
OSHA received numerous comments and testimony, particularly from
representatives of the ACC, regarding biases in the data that the
Agency relied upon to conduct its Preliminary Quantitative Risk
Assessment (Preliminary QRA). In this section, OSHA focuses on these
comments regarding biases, particularly with respect to how such biases
may have affected the data and findings from the key peer-reviewed,
published studies that OSHA relied upon in its Preliminary QRA.
The data utilized by OSHA to conduct its Preliminary QRA came from
published studies in the peer-reviewed scientific literature. When
developing health standards, OSHA is not required or expected to
conduct original research or wait for better data or new studies (see
29 U.S.C. 655(b)(5); e.g., United Steelworkers v. Marshall, 647 F.2d
1189, 1266 (D.C. Cir. 1980), cert. denied, 453 U.S. 913 (1981)).
Generally, OSHA bases its determinations of significant risk of
material impairment of health on the cumulative evidence found in a
number of studies, no one of which may be conclusive by itself (see
Public Citizen Health Research Group v. Tyson, 796 F.2d 1479, 1495
(D.C. Cir. 1986) (reviewing courts do not "seek a single dispositive
study that fully supports the Administrator's determination...
Rather, [OSHA's] decision may be fully supportable if it is based...
on the inconclusive but suggestive results of numerous studies.").
OSHA's critical reading and interpretation of scientific studies is
thus appropriately guided by the instructions of the Supreme Court's
Benzene decision that "so long as they are supported by a body of
reputable scientific thought, OSHA is free to use conservative
assumptions in interpreting the data with respect to carcinogens,
risking error on the side of overprotection rather than
underprotection" (Industrial Union Dep't v. American Petroleum Inst.,
448 U.S. 607, 656 (1980)).
Since OSHA is not a research agency, it draws from the best
available existing data in the scientific literature to conduct its
quantitative risk assessments. In most cases, with the exception of
certain risk and uncertainty analyses prepared for OSHA by its
contractor ToxaChemica, OSHA had no involvement in the data generation
or analyses reported in those studies. Thus, in calculating its risk
estimates, OSHA used published regression coefficients or equations
from key peer-reviewed, published studies, but had no control over the
actual published data; nor did the Agency have access to the raw data
from such studies.
As discussed throughout Section V of this preamble, the weight of
scientific opinion indicates that respirable crystalline silica is a
human carcinogen that causes serious, life-threatening disease at the
previously-permitted exposure levels. Under its statutory mandate, the
Agency can and does take into account the potential for statistical and
other biases to skew study results in either direction. However, the
potential biases of concern to the commenters are well known among
epidemiologists. OSHA therefore believes that the scientists who
conduct the studies and subject them to peer review before publication
have taken the potential for biases into account in evaluating the
quality of the data and analysis. As discussed further below, OSHA
heard testimony from David Goldsmith, Ph.D., describing how scientists
use "absolutely the best evidence they can lay their hands on" and
place higher value on studies that are the least confounded by other
factors that, if unaccounted for, could contribute to the effect (e.g.,
lung cancer mortality). (Document ID 3577, Tr. 894-895). Dr. Goldsmith
also testified that many of the assertions of biases put forth in the
rulemaking docket are speculative in nature, with no actual evidence
presented (Document ID 3577, Tr. 901). Thus, while taking seriously the
critiques of the "body of reputable scientific thought" OSHA has used
to support this final silica standard, the Agency finds no reason, as
discussed below, to consider discredited in any material way its key
conclusions regarding causation or significant risk of harm.
In his pre-hearing comments, Dr. Cox, on behalf of the ACC, claimed
that the Preliminary QRA did not address a number of sources of
potential bias:
The Preliminary QRA and the published articles that it relies on
do not correct for well-known biases in modeling statistical
associations between exposures and response. (These include study,
data, and model selection biases; model form specification and model
over-fitting biases; biases due to residual confounding, e.g.,
because age is positively correlated with both cumulative exposure
and risk of lung diseases within each age category (typically 5 or
more years long); and biases due to the effects of errors in
exposure estimates on shifting apparent thresholds to lower
concentrations). As a result, OSHA has not demonstrated that there
is any non-random association between crystalline silica exposure
and adverse health responses (e.g., lung cancer, non-malignant
respiratory disease, renal disease) at exposure levels at or below
100 [[micro]g/m\3\]. The reported findings of such an association,
e.g., based on significantly elevated relative risks or
statistically significant positive regression coefficients for
exposed compared to unexposed workers, are based on unverified
modeling assumptions and on ignoring uncertainty about those
assumptions (Document ID 2307, Attachment 4, pp. 1-2).
These biases, according to Dr. Cox, nearly always result in false
positives, i.e., finding that an exposure-response relationship exists
when there really is no such relationship (Document ID 3576, Tr. 380).
Although his comments appear to be directed to all published, peer-
reviewed studies relied upon by OSHA in estimating risks, Dr. Cox
admitted at the hearing that his statements about false positives were
based on his review of the Preliminary QRA with relation to lung cancer
only, and that he "[didn't] really know" whether the same allegations
of bias he directed at the lung cancer studies are relevant to the
studies of silica's other health risks (Document ID 3576, Tr. 426). In
his comments, Dr. Cox discussed each source of bias in detail; OSHA
will address them in turn. The concerns expressed by commenters,
including Dr. Cox, about exposure uncertainty--another potential source
of bias--are addressed in Section V.K, Comments and Responses
Concerning Exposure Estimation Error and ToxaChemica's Uncertainty
Analysis.
1. Model Specification Bias
Dr. Cox stated that model specification error occurs when the model
form, such as the linear absolute risk model, does not correctly
describe the data (Document ID 2307, Attachment 4, p. 21). Using a
simple linear regression example from Wikipedia, Dr. Cox asserted that
common indicators of goodness-of-fit, including sum of square residuals
and correlation coefficients, can be weak in identifying
"nonlinearities, outliers, influential single observations, and other
violations of modeling assumptions" (Document ID 2307, Attachment 4,
pp. 52-53). He advocated for the use of diagnostic tests to check that
a model is a valid and robust choice, stating, "[u]nfortunately,
OSHA's Preliminary QRA and the underlying papers and reports on which
it relies are not meticulous in reporting the results of such model
diagnostics, as good statistical and epidemiological practice
requires" (Document ID 2307, Attachment 4, p. 21). In his post-hearing
brief, Dr. Cox further described these diagnostic tests to include
plots of residuals, quantification of the effects of removing outliers
and influential observations, and comparisons of alternative model
forms using model cross-validation (Document ID 4027, p. 2). He also
suggested using Bayesian Model Averaging (BMA) or other model ensemble
methods to quantify the effects of model uncertainty (Document ID 4027,
p. 3).
OSHA believes that guidelines for which diagnostic procedures
should be performed, and whether and how they are reported in published
papers, are best determined by the scientific community through the
pre-publication peer review process. Many studies in the silica literature
did not report the results of diagnostic tests. For example, the Vacek et al.
(2009) study of lung cancer and silicosis mortality, which was
submitted to the rulemaking record by the ACC to support its position,
made no mention of the results of model diagnostic tests; rather, the
authors simply stated that models were fitted by maximum likelihood,
with the deviance used to examine model fitting
(Document ID 2307, Attachment 6, pp. 11-12). As illustrated by
this example, authors of epidemiological studies do not normally report
the results of diagnostic tests; nor do such authors publish their raw
data. Therefore, there is no data readily available to OSHA with which
it could perform the diagnostic analysis that Dr. Cox states is
necessary. If the suggestion is that no well-conducted epidemiological
study that failed to report a battery of diagnostic tests or disclose
what they showed should be relied upon for regulatory purposes, there
would be virtually no body of scientific study left for OSHA to
consider, raising the legal standard for issuing toxic substance
standards far above what the Benzene decision requires. Despite this,
OSHA maintains that, given the large number of peer-reviewed studies in
the published scientific literature on crystalline silica, subjecting
each model in each study to diagnostic testing along the lines
advocated by Dr. Cox would not fundamentally change the collective
conclusions when examining the literature base as a whole. Despite Dr.
Cox's criticisms, the scientific literature that OSHA reviewed to draw
its conclusions regarding material impairment of health and used in its
quantitative risk assessment, constitutes the best available evidence
upon which to base this toxic substance standard, in accordance with 29
U.S.C. 655(b) and the Benzene decision and subsequent case law.
Dr. Cox's other suggested approach to addressing model uncertainty,
BMA, can be used to construct a risk estimate based on multiple
exposure-response models. Unlike BMA, standard statistical practice in
the epidemiological literature is to evaluate multiple possible models,
identify the model that best represents the observations in the data
set, and use this model to estimate risk. In some cases, analysts may
report the results of two or more models, along with their respective
fit statistics and other information to aid model selection for risk
assessment and show the sensitivity of the results to modeling choices
(e.g., Rice et al., 2001, Document ID 1118). These standard approaches
were used in each of the studies relied on by OSHA in its Preliminary
QRA.
In contrast, BMA is a probabilistic approach designed to account
for uncertainty inherent in the model selection process. The analyst
begins with a set of possible models (Mi) and assigns each a
prior probability (Pr[Mi]) that reflects the analyst's
initial belief that model Mi represents the true exposure-
response relationship. Next, a data set is used to update the
probabilities assigned to the models, generating the posterior
probability for each model. Finally, the models are used in combination
to derive a risk estimate that is a composite of the risk estimates
from each model, weighted by each model's posterior probability (see
Viallefont et al., 2001, Document ID 3600, Attachment 34, pp. 3216-
3217). Thus, BMA combines multiple models, and uses quantitative
weights accounting for the analyst's belief about the plausibility of
each model, to generate a single weighted-average risk estimate. These
aspects of BMA are regarded by some analysts as improvements to the
standard approaches to exposure-response modeling.
However, Kyle Steenland, Ph.D., Professor, Department of
Environmental Health, Rollins School of Public Health, Emory
University, the principal author of a pooled study that OSHA heavily
relied upon, noted that BMA is not a standard method for risk
assessment. "[Bayesian] model averaging, to my knowledge, has not been
used in risk assessment ever. And so, sure, you could try that. You
could try a million things. But I think OSHA has correctly used
standard methods to do their risk assessment and [BMA] is not one of
those standard methods" (Document ID 3580, Tr. 1259).
Indeed, BMA is a relatively new method in risk analysis. Because of
its novelty, best practices for important steps in BMA, such as
defining the class of models to include in the analysis, and choosing
prior probabilities, have not been developed. Until best practices for
BMA are established, it would be difficult for OSHA to conduct and
properly evaluate the quality of BMA analyses. Evaluation of the
quality of available analyses is a key step in the Agency's
identification of the best available evidence on which to base its
significant risk determination and benefits analysis.
OSHA also emphasizes that, as noted by Dr. Steenland,
scientifically accepted and standard practices were used to estimate
risk from occupational exposure to crystalline silica (Document ID
3580, Tr. 1259). Thus OSHA has decided that it is not necessary to use
BMA in its QRA, and that the standard statistical methods used in the
studies it relies upon to estimate risk are appropriate as a basis for
risk estimation. OSHA notes that it is possible to incorporate risk
estimates based on more than one model in its risk assessment by
presenting ranges of risk, a strategy often used by OSHA when the best
available evidence includes more than one model, analytical approach,
or data set. In its Preliminary QRA, OSHA presented ranges of risks for
silica-related lung cancer and silicosis based on different data sets
and models, thus further lessening the utility of using more complex
techniques such as BMA. OSHA continued this practice in its final risk
assessment, presented in Section VI, Final Quantitative Risk Assessment
and Significance of Risk.
2. Study Selection Bias
Another bias described by Dr. Cox is study selection bias, which he
stated occurs when only studies that support a positive exposure-
response relationship are included in the risk assessment, and when
criteria for the inclusion and exclusion of studies are not clearly
specified in advance (Document ID 2307, Attachment 4, pp. 22-23). Dr.
Cox noted the criteria used by OSHA to select studies, as described in
the Supplemental Literature Review of Epidemiological Studies on Lung
Cancer Associated with Exposure to Respirable Crystalline Silica
(Supplemental Literature Review) (Document ID 1711, Attachment 1, p.
29). Dr. Cox, however, claimed that OSHA did not apply these criteria
consistently, in that there may still be exposure misclassification or
confounding present in the studies OSHA relied upon to estimate the
risk of the health effects evaluated by the Agency (Document ID 2307,
Attachment 4, pp. 24-25). Similarly, the American Foundry Society
(AFS), in its post-hearing brief, asserted that, "No formal process is
described for search criteria or study selection" and that OSHA's
approach of identifying studies based upon the IARC (1997) and NIOSH
(2002) evaluations of the literature "is a haphazard approach that is
not reproducible and is subject to bias. Moreover it appears to rely
primarily on information that is more than 10 years old" (Document ID
4229, p. 4).
OSHA disagrees with the arguments presented by Dr. Cox and the AFS,
as did some commenters. The American Public Health Association (APHA),
in its post-hearing brief, expressed strong support for OSHA's study
selection methods. Dr. Georges Benjamin, Executive Director, wrote,
"APHA recognizes that OSHA has thoroughly reviewed and evaluated the
peer-reviewed literature on the health effects associated with exposure
to respirable crystalline silica. OSHA's quantitative risk assessment is sound.
The agency has relied on the best available evidence and acted appropriately
in giving greater weight to those studies with the most robust designs and
statistical analyses" (Document ID 2178, Attachment 1, p. 1). Similarly,
Dr. Steenland testified that "OSHA has done a very capable job in
conducting the summary of the literature" (Document ID 3580, Tr.
1235).
In response to the criticisms by Dr. Cox and the AFS, OSHA notes
that the silica literature was exhaustively reviewed by IARC in 1997
and NIOSH in 2002 (Document ID 1062; 1110). As a result, there was no
need for OSHA to initiate a new review of the historical literature.
Instead, OSHA used the IARC and NIOSH reviews as a starting point for
its own review. As recognized by the APHA, OSHA evaluated and
summarized many of the studies referenced in the IARC and NIOSH
reviews, and then performed literature searches to identify new studies
published since the time of the IARC and NIOSH reviews. OSHA clearly
described this process in its Review of Health Effects Literature:
"OSHA has included in its review all published studies that the Agency
deems relevant to assessing the hazards associated with exposure to
respirable crystalline silica. These studies were identified from
numerous scientific reviews that have been published previously such as
the IARC (1997) and NIOSH (2002) evaluations of the scientific
literature as well as from literature searches and contact with experts
and stakeholders" (Document ID 1711, p. 8). For its Preliminary QRA,
OSHA relied heavily on the IARC pooled exposure-response analyses and
risk assessment for lung cancer in 10 cohorts of silica-exposed workers
(Steenland et al., 2001a, Document ID 0452) and multi-center study of
silicosis mortality (Mannetje et al., 2002b, Document ID 1089). As
stated in the Review of Health Effects Literature, these two studies
"relied on all available cohort data from previously published
epidemiological studies for which there were adequate quantitative data
on worker exposures to crystalline silica to derive pooled estimates of
disease risk" (Document ID 1711, p. 267).
In addition to relying on these two pooled IARC multi-center
studies, OSHA also identified single cohort studies with sufficient
quantitative information on exposures and disease incidence and
mortality rates. As pointed out by Dr. Cox, OSHA described the criteria
used for selection of the single cohort studies of lung cancer
mortality:
OSHA gave studies greater weight and consideration if they (1)
included a robust number of workers; (2) had adequate length of
follow-up; (3) had sufficient power to detect modest increases in
lung cancer incidence and mortality; (4) used quantitative exposure
data of sufficient quality to avoid exposure misclassification; (5)
evaluated exposure-response relationships between exposure to silica
and lung cancer; and (6) considered confounding factors including
smoking and exposure to other carcinogens (Document ID 1711,
Attachment 1, p. 29).
Using these criteria, OSHA identified four single-cohort studies of
lung cancer mortality that were suitable for quantitative risk
assessment; two of these cohorts (Attfield and Costello, 2004, Document
ID 0285; Rice et al., 2001, 1118) were included among the 10 used in
the IARC multi-center study and two appeared later (Hughes et al.,
2001, Document ID 1060; Miller and MacCalman, 2009, 1306) (Document ID
1711, p. 267). For NMRD mortality, in addition to the IARC multi-center
study (Mannetje et al., 2002b, Document ID 1089), OSHA relied on Park
et al. (2002) (Document ID 0405), who presented an exposure-response
analysis of NMRD mortality (including silicosis and other chronic
obstructive pulmonary diseases) among diatomaceous earth workers
(Document ID 1711, p. 267). For silicosis morbidity, several single-
cohort studies with exposure-response analyses were selected (Chen et
al., 2005, Document ID 0985; Hnizdo and Sluis-Cremer, 1993, 1052;
Steenland and Brown, 1995b, 0451; Miller et al., 1998, 0374; Buchanan
et al., 2003, 0306) (Document ID 1711, p. 267).
With respect to Dr. Cox's claim that OSHA did not apply its
criteria consistently, on the basis that there may still be exposure
misclassification or confounding present, OSHA notes that it selected
studies that best addressed the criteria; OSHA did not state that it
only selected studies that addressed all of the criteria. Given the
fact that some of the epidemiological studies concern exposures of
worker populations dating back to the 1930's, there is always some
potential for exposure misclassification or the absence of information
on smoking. When this was the case, OSHA discussed these limitations in
its Review of Health Effects Literature and Preliminary QRA (Document
ID 1711). For example, OSHA discussed the lack of smoking information
for cases and controls in the Steenland et al. (2001a, Document ID
0452) pooled lung cancer analysis (Document ID 1711, pp. 150-151).
With respect to the AFS's claim that OSHA relied on studies that
were more than 10 years old, OSHA again notes that it reviewed, in its
Review of Health Effects Literature and its Supplemental Literature
Review, the studies in the silica literature and selected the ones that
best met the criteria described above (Document ID 1711; 1711,
Attachment 1). It would be improper to only select the most recent
studies, particularly if the older studies are of higher quality based
on the criteria. Furthermore, the studies OSHA relied upon in its
Preliminary QRA were published between 1993 and 2009; the claim that
OSHA primarily relied on older studies is thus misleading, when the
studies were of relatively recent vintage and determined to be of high
quality based on the criteria described above. The AFS also suggested
that OSHA examine several additional foundry studies of lung cancer
(Document ID 2379, Attachment 2, p. 24); OSHA retrieved all of these
suggested studies, added them to the rulemaking docket following the
informal public hearings, and discusses them in Section V.F, Comments
and Responses Concerning Lung Cancer Mortality.
3. Data Selection Bias
A related bias presented by Dr. Cox is data selection bias, which
he stated occurs when only a subset of the data is used in the analysis
"to guarantee a finding of a positive" exposure-response relationship
(Document ID 2307, Attachment 4, p. 26). He provided an example, the
Attfield and Costello (2004, Document ID 0285) study of lung cancer
mortality, which excluded data as a result of attenuation observed in
the highest exposure group (Document ID 2307, Attachment 4, pp. 26-27).
Attenuation of response means the exposure-response relationship
leveled off or decreased in the highest exposure group. Referring to
another study of the same cohort, Vacek et al. (2009, Document ID 2307,
Attachment 6; 2011, 1486), Dr. Cox stated, "OSHA endorses the Attfield
and Costello findings, based on dropping cases that do not support the
hypothesis of an ER [exposure-response] relation for lung cancer, while
rejecting the Vacek et al. study that included more complete data (that
was not subjected to post hoc subset selection) but that did not find a
significant ER [exposure-response] relation"
(Document ID 2307, Attachment 4, pp. 26-27).
OSHA believes there are very valid reasons for the observance of
attenuation of response in the highest exposure group that would
justify the exclusion of data in Attfield and Costello (2004, Document
ID 0285) and other studies. This issue was discussed by Gary Ginsberg,
Ph.D., an OSHA peer reviewer from the Connecticut Department of Public
Health, in his post-hearing comments. Dr. Ginsberg noted that several
epidemiological studies have found an attenuation of response at higher
doses, with possible explanations including: (1) Measurement error,
which arises from the fact that the highest doses are associated with
the oldest datasets, which are most prone to measurement error; (2)
"intercurrent causes of mortality" from high dose exposures that
result in death to the subject prior to the completion of the long
latency period for cancer; and (3) the healthy worker survivor effect,
which occurs when workers with ill health leave the workforce early
(Document ID 3574, p. 24). As discussed in Section V.F, Comments and
Responses Concerning Lung Cancer Mortality, OSHA disagrees strongly
with Dr. Cox's assertion that data were excluded to ensure a positive
exposure-response relationship (Document ID 2307, Attachment 4, p. 26).
In addition, as detailed in Section VI, Final Quantitative Risk
Assessment and Significance of Risk, OSHA calculated quantitative risk
estimates for lung cancer mortality from several other studies that did
not rely on a subset of the data (Rice et al., 2001, Document ID 1118;
Hughes et al., 2001, 1060; Miller and MacCalman, 2009, 1306;
ToxaChemica, 2004, 0469; 1711, p. 351). These studies also demonstrated
positive exposure-response relationships.
4. Model Selection Bias
Another selection bias presented by Dr. Cox is model selection
bias, which he said occurs when many different combinations of models,
including alternative exposure metrics, different lags, alternative
model forms, and different subsets of data, are tried with respect to
their "ability to produce `significant'-looking regression
coefficients" (Document ID 2307, Attachment 4, p. 27). This is another
aspect of model specification error, as discussed above under model
averaging. Dr. Cox wrote:
This type of multiple testing of hypotheses and multiple
comparisons of alternative approaches, followed by selection of a
final choice based [on] the outcomes of these multiple attempts,
completely invalidates the claimed significance levels and
confidence intervals reported for the final ER [exposure-response]
associations. Trying in multiple ways to find a positive
association, and then selecting a combination that succeeds in doing
so and reporting it as `significant,' while leaving the nominal
(reported) statistical significance level of the final selection
unchanged (typically at p=0.05), is a well-known recipe for
producing false-positive associations (Document ID 2307, Attachment
4, p. 28).
Dr. Cox further stated that unless methods of significance level
reduction (i.e., reducing the nominal statistical significance level of
the final selection) are used, the study is biased towards false-
positive results (Document ID 2307, Attachment 4, p. 28).
During the informal public hearings, counsel for the ACC asked Mr.
Park of NIOSH's Risk Evaluation Branch about this issue, i.e., trying a
number of modeling choices, including exposure metrics, log-
transformations, lag periods, and model subsets (Document ID 3579, Tr.
149-150). Mr. Park's reply supports the use of multiple modeling
choices in the risk assessment as a form of sensitivity analysis:
Investigations like this look at a number of options. They come
into the study not totally na[iuml]ve. They, in fact, have some very
strong preference even before looking at the data based on prior
knowledge. So cumulative exposure, for example, is a generally very
high confidence choice in a metric. Trying different lags is
interesting. It helps validate the study because you know what it
ought to look like sort of. And in many cases, the choice does not
make a lot of difference. So it's kind of a robust test, and
similarly, the choice of the final model is not just coming in
na[iuml]ve. A linear exposure response has a lot of biological
support in many different contexts, but it could be not the best
choice (Document ID 3579, Tr. 150-151).
ACC counsel further asked, "And does one at the end of this
process, though, make any adjustment in what you consider to be the
statistically significant relationship in light of the fact that you've
looked at so many different models and arrangements?" (Document ID
3579, Tr. 151-152). Mr. Park replied, "No, I don't think that's a
legitimate application of a multiple comparison question" (Document ID
3579, Tr. 152). OSHA agrees with Mr. Park that significance level
reduction is not appropriate in the context of testing model forms for
risk estimation, and notes that, in the Agency's experience,
significance level reduction is not typically performed in the
occupational epidemiology literature. In addition, OSHA notes that, in
many of the key studies relied upon by the Agency to estimate
quantitative risks, the authors presented the results of multiple
models that showed statistically significant exposure-response
relationships. For example, Rice et al. (2001) presented the results of
six model forms, with all except one being significant (Table 1,
Document ID 1118, p. 41). Attfield and Costello (2004) presented the
results of their model with and without a 15-year lag and log
transformation, with many results being significant (Table VII,
Document ID 0285, p. 135). Thus, OSHA concludes that model selection
bias is not a problem in its quantitative risk assessment.
Furthermore, OSHA disagrees with Dr. Cox's assertion that modeling
choices are used to "produce `significant'-looking regression
coefficients" (Document ID 2307, Attachment 4, p. 27). OSHA believes
that the investigators of the studies it relied upon in its
Preliminary, and now final, QRA made knowledgeable modeling choices
based upon the exposure distribution and health outcome being examined.
For example, in long-term cohort studies, such as those of lung cancer
mortality relied upon by OSHA, most authors relied upon cumulative
exposure (mg/m\3\-yrs or mg/m\3\-days), i.e., the concentration of
crystalline silica exposure (mg/m\3\) multiplied by the duration of
exposure (years or days), as an exposure metric. Consistent with
standard statistical techniques used in epidemiology, the cumulative
exposure metric may then be log-transformed to account for an
asymmetric distribution with a long right tail, or attenuation, and the
metric may be lagged by several years to account for the long latency
period between the exposure and the development of lung cancer. When
investigators use subsets of the data, they typically explain the
rationale and the effect of using the subset in the analysis. These
choices all have important justifications and are not used purely to
produce the authors' desired results, as Dr. Cox suggested (Document ID
2307, Attachment 4, p. 27).
5. Model Uncertainty Bias
Related to model selection bias is Dr. Cox's assertion of model
uncertainty bias, which he said occurs when many different models are
examined and then one is selected on which to base risk calculations;
this approach "treats the finally selected model as if it were known
to be correct, for purposes of calculating confidence intervals and
significance levels. But, in reality, there remains great uncertainty
about what the true causal relation between exposure and response looks
like (if there is one)" (Document ID 2307, Attachment 4, pp. 28-29).
He further stated that ignoring this bias leads to artificially narrow
confidence intervals, which bias conclusions towards false-positive findings.
He then cited a paper (Piegorsch, 2013, included in Document ID 3600)
describing statistical methods for overcoming this bias by "including
multiple possible models in the calculation of results"
(Document ID 2307, Attachment 4, p. 29). OSHA concludes this bias is
really an extension of model specification error and model selection bias,
previously discussed, and maintains that best practices for model averaging
have not yet been established, making it difficult for the Agency to
conduct and properly evaluate the quality of BMA analyses.
6. Model Over-Fitting Bias
Next, Dr. Cox discussed model over-fitting bias, which he said
occurs when the same data set is used both to fit a model and to assess
the fit; this "leads to biased results: Estimated confidence intervals
are too narrow (and hence lower confidence limits on estimated ER
[exposure-response] slopes are too high); estimated significance levels
are too small (i.e., significance is exaggerated); and estimated
measures of goodness-of-fit overstate how well the model fits the
data" (Document ID 2307, Attachment 4, p. 39). He suggested using
appropriate statistical methods, such as "k-fold cross-validation,"
to overcome the bias (Document ID 2307, Attachment 4, p. 39).
OSHA does not agree that using the same data set to fit and assess
a model necessarily results in an over-fitting bias. The Agency
understands over-fitting to occur when a model is excessively complex
relative to the amount of data available such that there are a large
number of predictors relative to the total number of observations
available. For survival models, it is the number of events, i.e.,
deaths, that is relevant, rather than the size of the entire sample
(Babyak, 2004, included in Document ID 3600, p. 415). If the number of
predictors (e.g., exposure, age, gender) is small relative to the
number of events, then there should be no bias from over-fitting. In an
article cited and submitted to the rulemaking docket by Dr. Cox, Babyak
(2004) discussed a simulation study that found, for survival models, an
unacceptable bias when there were fewer than 10 to 15 events per
independent predictor (included in Document ID 3600, p. 415). In the
studies that OSHA relied on in its Preliminary QRA, there were
generally a large number of events relative to the small number of
predictors. For example, in the Miller and MacCalman (2009) study of
British coal miners, in the lung cancer model using both quartz and
coal dust exposures, there was a large number of events (973 lung
cancer deaths) relative to the few predictors in the model (quartz
exposure, coal dust exposure, cohort entry date, smoking habits at
entry, cohort effects, and differences in regional background cause-
specific rates) (Document ID 1306, pp. 6, 9). Thus, OSHA does not agree
the studies it relied upon were substantially influenced by over-
fitting bias. OSHA also notes that k-fold cross-validation, as
recommended by Dr. Cox, is not typically reported in published
occupational epidemiology studies, and that the studies the Agency
relied upon in the Preliminary QRA were published in peer-reviewed
journals and used statistical techniques typically used in the field of
occupational epidemiology and epidemiology generally.
7. Residual Confounding Bias
Dr. Cox also asserted a bias due to residual confounding by age.
Bias due to confounding occurs in an epidemiological study, in very
general terms, when the effect of an exposure is mixed together with
the effect of another variable (e.g., age) not accounted for in the
analysis. Residual confounding occurs when additional confounding
factors are not considered, control of confounding is not precise
enough (e.g., controlling for age by using groups with age spans that
are too wide), or subjects are misclassified with respect to
confounders (Document ID 3607, p. 1). Dr. Cox stated in his comments
that:
key studies relied on by OSHA, such as Park et al. (2002), do not
correct for biases in reported ER [exposure-response] relations due
to residual confounding by age (within age categories), i.e., the
fact that older workers may tend to have both higher lung cancer
risks and higher values of occupational exposure metrics, even if
one does not cause the other. This can induce a non-causal
association between the occupational exposure metrics and the risk
of cancer (Document ID 2307, Attachment 4, p. 29).
The Park et al. (2002) study of non-malignant respiratory disease
mortality, which Dr. Cox cited as not considering residual confounding
by age, used 13 five-year age groups (< 25, 25-29, 30-34, etc.) in the
models (Document ID 0405, p. 37). Regarding this issue in the Park et
al. (2002) study, in its post-hearing comments, NIOSH stated:
This is a non-issue. The five-year categorization was used only
for deriving the expected numbers of cases as an offset in the
Poisson analysis using national rates which typically are classified
in five-year intervals (on age and chronological time). The
cumulative exposures were calculated with a 10-day resolution over
follow-up and then averaged across observation time within 50
cumulative exposure levels cross-classified with the five-year age-
chronological time cells of the classification table. There would be
virtually no confounding between age and exposure [using this
approach] (Document ID 4233, p. 33).
OSHA agrees with this assessment, noting that it appears that age
groups were adequately constructed to prevent residual confounding.
OSHA thus rejects this assertion of residual confounding by age in the
Park et al. (2002) study.
8. Summary of Biases
In summary, OSHA received comments and heard testimony on potential
biases in the studies upon which it relied for its QRA. The ACC's Dr.
Cox, in particular, posited a long list of biases, including model form
specification bias, study selection bias, data selection bias, model
selection bias, model over-fitting bias, model uncertainty bias,
residual confounding bias, and bias as a result of exposure measurement
error. OSHA, in this section, has specifically addressed each of these
types of bias (except for bias due to exposure estimation error, which
is addressed in Section V.K, Comments and Responses Concerning Exposure
Estimation Error and ToxaChemica's Uncertainty Analysis).
In addition, OSHA heard testimony that countered the claims of
biases and their potential to cause false positive results. When asked
about the biases alleged by Dr. Cox and Dr. Long, Dr. Goldsmith
testified, "All of these other things, it seems to me, are smoke
screens for an inability to want to try and see what the body of
evidence really shows" (Document ID 3577, Tr. 895-896). Later in his
testimony, when asked about exposure misclassification, Dr. Goldsmith
similarly noted, "[a]nd for a lot of the arguments that are being put
forward by industry, they are speculating that there is the potential
for these biases, but they haven't gotten, [from] my perspective, the
actual evidence that this is the case" (Document ID 3577, Tr. 901).
Similarly, OSHA has reviewed the record evidence extensively and is not
aware of any specific, non-speculative evidence of biases in the
studies that it relied upon.
There also is a question of the extent to which Dr. Cox actually
reviewed all of the studies that he asserted to be biased. Upon
questioning from Anne Ryder, Attorney in the Office of the Solicitor,
Department of Labor, Dr. Cox admitted that he had not examined the
issue of silica and silicosis, and that his statements about false
positives were based on his review of the Preliminary QRA with relation
to lung cancer only:
MS. RYDER:...You talked a little bit earlier about the false
positives that are...present with a lot of the studies on lung
cancer. And, but I believe, in your comment you didn't say that
there are any of those same false positives with studies dealing
with silicosis and silica exposure. Is that correct?
DR. COX: I don't think I opined on that. So--and I really
haven't looked carefully at the question. I do take it as given that
silica at sufficiently high and prolonged exposures causes
silicosis. I've not really examined that literature.
MS. RYDER: So you don't think that those studies have the same
issues that some of the lung cancer studies have?
DR. COX: I don't really know (Document ID 3576, Tr. 426).
Dr. Cox further testified, regarding the likelihood that the
conclusions of the Preliminary QRA for silicosis are correct, "I
expect that the evidence is much stronger for silica and silicosis. But
I haven't reviewed it, so I can't testify to it" (Document ID 3576,
Tr. 427).
OSHA believes this testimony to be inconsistent with some of the
broad conclusions in Dr. Cox's pre-hearing written submission to the
rulemaking record, in which he claimed that all adverse outcomes in the
Preliminary QRA may have been affected by false positives. Dr. Cox
concluded in this submission that:
These multiple uncontrolled sources of false-positive bias can
generate findings of statistically "significant" positive ER
[exposure-response] associations even in random data, or in data for
which there is no true causal relation between exposure and risk of
adverse health responses. Because OSHA's Preliminary QRA and the
studies on which it relies did not apply appropriate technical
methods (which are readily available, as discussed in the
references) to diagnose, avoid, or correct for these sources of
false-positive conclusions, the reported findings of
"significantly" positive ER [exposure-response] associations
between crystalline silica exposures at and below the current PEL
and adverse outcomes (lung cancer, non-malignant lung disease, renal
disease) are not different from what might be expected in the
absence of any true ER [exposure-response] relations. They therefore
provide no evidence for (or against) the hypothesis that a true ER
[exposure-response] relation exists. Thus, OSHA has not established
that a non-random association exists between crystalline silica
exposures at or below the current PEL and the adverse health effects
on which it bases its determination of significant risk and
calculates supposed health effect benefits (Document ID 2307,
Attachment 4, pp. 29-30).
OSHA notes that "non-malignant lung disease" includes silicosis,
studies of which Dr. Cox subsequently testified that he did not
examine.
In conclusion, the studies relied upon by OSHA for its risk
assessment were peer-reviewed and used methods for epidemiology and
risk assessment that are commonly used. Dr. Cox provided no study-
specific evidence (e.g., data re-analysis) to support his comments that
the studies OSHA relied upon were adversely affected by numerous
different types of bias. As described above, OSHA recognizes that there
are uncertainties associated with the results of the studies relied on
for its risk assessment, as is typically the case for epidemiological
studies such as these. Nevertheless, as previously stated, OSHA
maintains that it has used a body of peer-reviewed scientific
literature that, as a whole, constitutes the best available evidence of
the relationship between respirable crystalline silica exposure and
silicosis, lung cancer, and the other health effects studied by the
Agency in promulgating this final rule.
K. Comments and Responses Concerning Exposure Estimation Error and
ToxaChemica's Uncertainty Analysis
Exposure estimation error, a typical feature of epidemiological
studies, occurs when the authors of an exposure-response study
construct estimates of the study subjects' exposures using uncertain or
incomplete exposure data. Prior to the publication of its Preliminary
Quantitative Risk Assessment (Preliminary QRA), the Agency commissioned
an uncertainty analysis conducted by Drs. Kyle Steenland and Scott
Bartell, through its contractor, ToxaChemica, Inc., to address exposure
estimation error in OSHA's risk assessment, and incorporated the
results into the Preliminary QRA. After reviewing comments submitted to
the record on the topic of exposure estimation error, OSHA maintains
that it has relied upon the best available evidence by: (1) Using high-
quality exposure-response studies and modeling approaches; (2)
performing an uncertainty analysis of the effect of exposure estimation
error on the risk assessment results; and (3) further submitting that
analysis to peer review. OSHA concludes from its uncertainty analysis
that exposure estimation error did not substantially affect the results
in the majority of studies examined (Document ID 1711, pp. 299-314).
Furthermore, having carefully considered the public comments
criticizing ToxaChemica's uncertainty analysis, OSHA has concluded that
it was not necessary to conduct additional analyses to modify the
approach adopted by Drs. Steenland and Bartell in the uncertainty
analysis. Nor was it necessary to incorporate additional sources of
uncertainty in the analysis. Also, given the evidence in the rulemaking
record that these estimation errors bias results towards
underestimating rather than overestimating the risks from exposure in
many circumstances, it is very unlikely that regression coefficients
and risk estimates from all of the different studies relied on in the
Preliminary QRA were biased upward. Accordingly, OSHA remains convinced
that the conclusions of the Agency's risk assessment are correct and
largely unaffected by potential error in exposure measurement.
OSHA received significant comments on the topic of exposure
estimation error in the studies it relied on in its Review of Health
Effects Literature and Preliminary QRA (Document ID 1711). A number of
commenters discussed the importance of accounting for exposure
estimation error. Dr. Cox, representing the ACC, described exposure
estimation error as perhaps the "most quantitatively important" issue
in the studies OSHA relied upon (Document ID 2307, Attachment 4, p.
40). Similarly, Christopher M. Long, Sc.D., Principal Scientist at
Gradient, representing the U.S. Chamber of Commerce (Chamber),
testified that exposure measurement error is a "common source of
uncertainty in most occupational and environmental epidemiologic
studies" (Document ID 3576, Tr. 298). According to Dr. Long, this type
of error can lead to inaccurate risk estimates by creating error in the
exposure-response curve derived from a data set and obscuring the
presence of a threshold (Document ID 3576, Tr. 300; see Section V.I,
Comments and Responses Concerning Thresholds for Silica-Related
Diseases, for further discussion on thresholds). Dr. Long further
stated that exposure measurement error can lead to over- or under-
estimation of risk: "the impact of exposure measurement error...
can bias either high or low. It can bias towards the null. It can be a
source of positive bias." (Document ID 3576, Tr. 358-359). A bias to
the null in an exposure-response model used in a quantitative risk
assessment is an underestimation of the relationship between exposure
level and the rate of the disease or health effect of interest, and
results in underestimation of risk.
OSHA agrees with the assessments of the ACC and the Chamber with
respect to the importance of exposure measurement error. Indeed, OSHA
peer reviewer, Dr. Gary Ginsberg, in his peer review comments
(Document ID 3574, p. 21), and OSHA's risk assessment contractor,
Dr. Steenland, in his hearing testimony (Document ID 3580, Tr. 1266-1267),
noted the potential for exposure measurement error to bias exposure-response
coefficients towards the null. Dr. Steenland explained: "misclassification
I would say in general tends to bias things to the null. It's harder to see
positive exposure-response trends in the face of misclassification. It depends
partly on the type of error....But, on the whole, I would say that
exposure measurement tends to bias things down rather than up"
(Document ID 3580, Tr. 1266-1267). Fewell et al., the authors of a
paper on residual confounding submitted by the ACC, wrote, "It is well
recognized that under certain conditions, nondifferential measurement
error in the exposure variable produces bias towards the null" (2007,
Document ID 3606, p. 646).
Several commenters representing the ACC challenged the methods used
in ToxaChemica's uncertainty analysis on the grounds that the analysis
failed to adequately address exposure estimation error. In spite of
their criticisms, critics were unable to supply better studies than
those OSHA used. Indeed, when asked during the hearing, Dr. Long was
unable to identify any studies that the Agency could use that
acceptably account for the impact of exposure measurement error on
exposure-response associations for crystalline silica (Document ID
3576, Tr. 356-357), and none was supplied following the hearings.
Taking into account the record evidence discussed above, OSHA
concludes that it is possible for exposure measurement error to lead to
either over- or under-estimation of risk and that this issue of
exposure measurement error is not specific to the silica literature. It
further concludes that industry representatives could not identify, and
failed to submit, any published epidemiological studies of occupational
disease that corrected for such bias to their satisfaction (Document ID
3576, Tr. 356-357).
Nevertheless, because OSHA agreed that an analysis of exposure
estimation error as a source of uncertainty is important, it
commissioned the uncertainty analysis discussed above to explore the
potential effects of exposure measurement error on the conclusions of
OSHA's risk assessment (Document ID 0469). The analysis examined the
potential effects of exposure measurement error on the mortality risk
estimates derived from the pooled studies of lung cancer (Steenland et
al. 2001a, Document ID 0452) and silicosis (Mannetje 2002b, Document ID
1089). This included the effects of estimation error on the detection
and location of a possible threshold effect in exposure-response
models.
The uncertainty analysis OSHA commissioned from Drs. Steenland and
Bartell (2004, Document ID 0469) addressed possible error in silica
exposure estimates from: (1) Random error in individual workers'
exposure estimates and (2) error in the conversion of dust measurements
(typically particle count concentrations) to gravimetric respirable
silica concentrations, which could have affected estimates of average
exposure for job categories in the job-exposure matrices used to
estimate workers' silica exposure. To address possible error in
individual workers' exposure estimates, the analysts performed a Monte
Carlo analysis, a type of simulation analysis which varies the values
of an uncertain input to an analysis (in this case, exposure estimates)
to explore the effects of different values on the outcome of the
analysis. The Monte Carlo analysis sampled new values for workers' job-
specific exposure levels from distributions they believed characterized
the exposures of individual workers in each job. In each run of the
Monte Carlo analysis, the sampled exposure values were used to
calculate new estimates of each worker's cumulative exposures, and the
resulting set was used to fit a new exposure-response model.
Similarly, the analysts performed a Monte Carlo analysis to address
the issue of uncertainty in conversion from dust to respirable silica
exposure, sampling new conversion factors from a normal distribution
with means equal to the original conversion factor, calculating new
estimates of workers' cumulative exposures, and re-fitting the
exposure-response model for each Monte Carlo run. To examine the
sensitivity of the model to the joint effects of both error types, the
analysts ran 50 Monte Carlo simulations using the sampling procedure
for both individual exposures and job-specific conversion factors. They
also examined the effects of systematic bias in conversion factors,
considering that these may have been consistently under-estimated or
over-estimated for any given cohort. They addressed possible biases in
either direction, conducting 20 simulations where the true silica
content was assumed to be either half or double the estimated silica
content of measured exposures.
The results of their analysis indicated that the conclusions of the
pooled lung cancer study conducted previously by Steenland et al.
(Document ID 0452) and included in OSHA's Preliminary QRA were unlikely
to be affected by the types of exposure estimation error examined by
Drs. Steenland and Bartell, whose analysis of the underlying data was
itself reviewed by OSHA's peer review panel. As explained below, after
reviewing comments critical of the uncertainty analysis, OSHA reaffirms
its conclusion that workers exposed to silica at the previous PELs are
at significant risk of disease from their exposure.
Drs. Long and Valberg, representing the Chamber, commented that
Drs. Steenland and Bartell's uncertainty analysis did not address all
potential sources of error and variability in exposure measurement,
such as possible instrument error; possible sampling error; random
variability in exposure levels; variability in exposure levels
resulting from changes in worker job functions during work shifts,
production process changes, or control system changes; variability in
sampler type used; variability in laboratory methods for determining
sampling results and laboratory errors; variability in duration of
exposure sampling; variability in sampling locations; variability in
reasons for sample data collection (e.g., compliance sampling, periodic
sampling, random survey sampling); variability in type of samples
collected (e.g., bulk samples, respirable dust samples); variation
among workers and over time in the size distribution, surface area,
recency of fracture, and other characteristics of the particles
inhaled; and extrapolation of exposure sampling data to time periods
for which sampling data are not available (Document ID 2330, pp. 4-5).
OSHA notes that these sources of potential error and variability are
common in occupational exposure estimation, and are sources of
uncertainty in most epidemiological studies, a point with which Drs.
Valberg and Long agree (Document ID 2330, p. 14).
OSHA has determined that its reliance on the best available
evidence provided it with a solid, scientifically sound foundation from
which to conclude that exposure to crystalline silica poses a
significant risk of harm, notwithstanding the various uncertainties
inherent in epidemiology generally or potentially affecting any given
study and that no studies exist entirely free from the types of data
limitations or error and variability Drs. Valberg and Long identified.
During the public hearing Dr. Long acknowledged that OSHA had not
overlooked studies that he believed adequately addressed the sources
of error cited in his comments. He was also unable to provide examples
of such analyses in the silica literature, or in any other area of
occupational epidemiology (Document ID 3576, Tr. 355-358; see also
Document ID 3577, Tr. 641, 648 (testimony of Dr. Kenneth Mundt)).
Additionally, Drs. Valberg and Long's critique of Drs.
Steenland and Bartell's uncertainty analysis ignores constraints on the
available data and reasonable limits on the analysts' ability to
investigate the full variety of possible errors and their potential
effects on OSHA's risk assessment.
OSHA additionally notes that Dr. Kenneth Crump, an OSHA peer
reviewer, in his examination of ToxaChemica's (Document ID 0469) study
of exposure uncertainty in the Steenland et al. pooled study, opined
that it was sound. He further observed that the "analysis of error
conducted by [ToxaChemica] is a very strong effort. The assumptions are
clearly described and the data upon [which] they are based appear to be
appropriate and appropriately applied." Dr. Crump was careful to note,
however, that "there are questions, as there will always be with such
an analysis...A major source of error that apparently was not
accounted for is in assuming that the average measure of exposure
assigned to a job is the true average" (Document ID 3574, pp. 161-
162). Dr. Cox referenced Dr. Crump's comment in his own pre-hearing
comments, in the context of a discussion on the importance of exposure
uncertainty in OSHA's risk analysis (Document ID 2307, p. 40). OSHA
addressed this particular criticism in the Review of Health Effects
Literature and Preliminary QRA. There, it stated that it is possible
that some job exposure estimates were above or below the true average
for a job; however, there was no "gold standard" measurement
available to appropriately test or adjust for this potential source of
error (Document ID 1711, p. xv). The Agency further stated that the
uncertainty, or sensitivity, analysis included potential error in job
averages, and found that most cohorts in the lung cancer and silicosis
mortality pooled studies were not highly sensitive to random or
systematic error in job-average exposure estimates (Document ID 1711,
pp. 303-314). In his final evaluation of OSHA's response to his
comments of 2009, Dr. Crump stated, "I believe that my comments have
been fairly taken into account in the current draft and I have no
further comments to make" (Document ID 3574, p. 17).
Similarly, Dr. Morfeld, representing the ACC, criticized Drs.
Steenland and Bartell for performing only 50 simulations of workplace
exposures as part of the uncertainty analysis (Document ID 2307,
Attachment 2, p. 10). Peer reviewer Mr. Bruce Allen also remarked that
this type of uncertainty analysis typically requires more than 50
simulations (Document ID 3574, p. 114). However, as stated by OSHA in
the response to peer review section of the Review of Health Effects
Literature and Preliminary QRA (Document ID 1711, pp. 379-400), the
results did not appear to change much with an increased number of
simulations. Thus, OSHA has concluded that the sensitivity findings
would not have changed substantially by running more simulations.
Indeed, in the final peer review report conveying his evaluation of
OSHA's response to his comments of 2009, Mr. Allen stated that OSHA
adequately addressed his comments in the updated risk assessment
(Document ID 3574, p. 5).
The overall salient conclusion that OSHA draws from this peer-
reviewed analysis is that even in those cohorts where exposure error
had some impact on exposure-response models for lung cancer or
silicosis, the resulting risk estimates at the previous and new PELs
remain clearly significant. Therefore, OSHA continues to rely on, and
have confidence in, the risk analysis it had performed. In particular,
OSHA concludes that Drs. Steenland and Bartell's modeling choices were
based on the best available data from a variety of industrial sources
and, through their uncertainty analysis, reached conclusions that
survive the ACC and Chamber criticisms of the study methodology. OSHA
further concludes that it is not necessary to conduct additional
analysis to modify the approach adopted by Drs. Steenland and Bartell
or to incorporate additional sources of exposure estimation uncertainty
in the analysis.
OSHA also disagrees with other specific criticisms that Drs. Long
and Valberg made concerning the uncertainty analysis. Dr. Long
testified that "there are no formal analyses conducted to determine
the error structures of the three sources of exposure measurement error
included in the sensitivity analyses; for example, without any formal
analysis, the OSHA assessment simply assumed a purely Berkson type
error structure from the assignment of job-specific average exposure
levels for individual exposures" (Document ID 3576, 304-305).\9\ Dr.
Cox expressed a similar concern that
---------------------------------------------------------------------------
\9\ The first component of ToxaChemica's analysis takes the
exposure level for each job in the job-exposure matrix as the mean
exposure level for workers in that job, with error (that results
from using the mean to estimate each individual worker's exposure)
varying randomly around the mean (Document ID 0469, P. 10). The
second type of error examined by ToxaChemica, resulting from the
assignment of a single conversion factor to represent quartz
percentage in dust samples for multiple jobs, similarly might be
expected to vary randomly around a mean equal to the recorded
conversion factor. Errors resulting from the assignment of job-
specific mean exposures (or conversion factors) to individual
workers or jobs results in a type of error known as Berkson error,
in which the true exposure level is assumed to vary randomly around
the assigned or "observed" exposure level for the job (Snedecor
and Cochran, 1989).
OSHA has not developed an appropriate error model specifically
for the exposure estimates in the crystalline silica studies and has
not validated (e.g., using a validation subset) that any of the ad
hoc error models that they discuss describes the real exposure
estimate errors of concern. They have also provided no justification
for ToxaChemica's assumption of a log-normal distribution without
outliers or mixtures of different distributions...and have
provided no rationale for the assumption that a=0.8*p (Document ID
---------------------------------------------------------------------------
2307, Attachment 4, p. 45).
OSHA disagrees with Dr. Long's and Dr. Cox's characterizations,
which implies that Drs. Steenland and Bartell did not adequately
investigate the patterns of error in the data available to them. As
noted in their 2004 report and by Dr. Steenland during the public
hearings, ToxaChemica did not have the internal validation data (true
exposures for a subset of the data set) that would be required to
conduct formal analyses or validation of the error structure within
each cohort of the pooled analysis (Document ID 0469, p. 16; 3580, pp.
1229-1231). Such data are not often available to analysts. However,
Drs. Steenland and Bartell researched and reviewed worker exposure and
dust composition data from several worksites to inform the error
structures used in their analyses. For example, their analysis of
individual workers' exposure data from the pooled analyses' industrial
sand cohort formed the basis of the equation used for the exposure
error simulation, which Dr. Cox represented as an assumption lacking
any rationale. Drs. Steenland and Bartell also reviewed a number of
studies characterizing the distribution of conversion factors across
and within jobs at different worksites. OSHA concludes that Drs.
Steenland and Bartell made a strong effort to collect data to inform
their modeling choices, and that their choices were based on the
best available information on error structure.
Dr. Long stated that "another limitation of the [ToxaChemica
uncertainty] assessment was its assumption of log-linear...types of
models, including log linear models with log-transformed exposure
variables, and it focused on cumulative measures of silica exposure
that obscure both within-person and between-person variability in
exposure rates" (Document ID 3576 pp. 305-306). Dr. Long's assertion
regarding the choice of exposure models is incorrect, as the
sensitivity analysis was not limited to log-linear models. It included
models with flexibility to capture nonlinearities in exposure-response,
including spline analyses and categorical analyses, and log-
transformation of the exposure variable was used only in the lung
cancer analysis where it was shown in the original pooled analysis to
better fit the data and address issues of heterogeneity between cohorts
(Document ID 0469). Drs. Steenland and Bartell found only slight
differences between the adjusted exposure-response estimates for each
type of model.
Drs. Long and Valberg also contended that the cumulative exposure
metric used in the Steenland and Bartell pooled study did not
sufficiently allow for examination of the effects of exposure
measurement uncertainty on the results of OSHA's risk assessment,
because other exposure metrics could be more relevant. OSHA disagrees.
As discussed in Section V.M, Comments and Responses Concerning Working
Life, Life Tables, and Dose Metric, cumulative exposure is widely
acknowledged by health experts as a driver of chronic diseases such as
silicosis and lung cancer, has been found to fit the exposure-response
data well in many studies of silicosis and lung cancer in the silica
literature, and best fit the exposure-response data in the underlying
pooled data sets to which Drs. Steenland and Bartell applied their
subsequent uncertainty analyses. Thus, OSHA believes it was appropriate
for this investigation of exposure estimation error to focus on the
cumulative exposure metric, for reasons including data fit and general
scientific understanding of this disease.
Furthermore, Dr. Long's concern that the choice of cumulative
silica exposure might "obscure within-person variability in exposure
rates" is not well supported in the context of lung cancer and
silicosis mortality. Because death from these diseases typically occurs
many years after the exposure that caused it, and complete records of
past exposures do not typically exist, it is very difficult, using any
metric, to trace within-person exposure variability (that is, changes
in a person's exposure over time); these factors, not the choice of
cumulative exposure metric, make it difficult to address variability in
individuals' exposures over time and their effects on risk. OSHA notes
that some analysts have explored the use of other exposure metrics in
threshold analyses, submitting studies to the record which the Agency
has reviewed and discussed in Section V.I, Comments and Responses
Concerning Thresholds for Silica-Related Diseases.
Dr. Long also testified that "[t]here's very little discussion in
the OSHA report regarding the potential impacts of exposure measurement
error on identification of thresholds...[ToxaChemica's 2004 report]
noted that exposure-response threshold estimates are imprecise and
appear to be highly sensitive to measurement errors" (Document ID 3576
p. 306). Dr. Cox further noted that exposure misclassification can
"create the appearance of a smooth, monotonically increasing estimated
ER [exposure-response] relation" and shift thresholds to the left
(Document ID 2307, Attachment 4, pp. 41-42); that is, create the
appearance that a threshold effect occurs at a lower exposure level
than would be seen in a data set without exposure misclassification.
In their uncertainty analysis, Drs. Steenland and Bartell estimated
an exposure-response threshold for the pooled cohorts in each of the 50
runs conducted for their lung cancer analysis. They defined the
"threshold" as the highest cumulative exposure for which the
estimated odds ratio was less than or equal to 1.0, reporting a mean
value of 3.04 mg/m\3\-days and median of 33.5 mg/m\3\-days across the
50 runs (Document ID 0469, p. 15). The authors observed that "[t]hese
estimates are somewhat lower than the original estimate (Steenland and
Deddens 2002) of a threshold at 121 mg/m\3\-days (4.8 on the log
scale), which translates to about 0.01 mg/m\3\ [10 [micro]g/m\3\] over
a working 30-year lifetime (considering a 15-year lag), or 0.007
[7[micro]g/m\3\] over a 45-year lifetime without considering a 15-year
lag" (Document ID 0469, p. 15). These exposure levels are about one-
fifth the PEL of 50 [mu]g/m\3\ included in the final standard.
As noted by Dr. Long, the threshold estimates were highly variable
across the 50 iterations (SD of 1.64 on the log scale), in keeping with
other comments received by OSHA that estimates of exposure-response
thresholds based on epidemiological data tend to be highly sensitive to
sources of measurement error and other issues common to epidemiological
investigations (see Section V.I, Comments and Responses Concerning
Thresholds for Silica-Related Diseases). However, the Agency notes that
the results of the uncertainty analysis, suggesting a possible
cumulative exposure threshold at approximately one-fifth the final 50
[mu]g/m3 PEL, provide no cause to doubt OSHA's determination
that significant risk exists at both the previous and the revised PEL.
An additional concern raised by Dr. Cox was based on his
misunderstanding that the equation used to characterize the
relationship between true and observed exposure in Drs. Steenland and
Bartell's simulation, "Exposuretrue = Exposureobserved + E",
concerned cumulative exposure. Dr. Cox stated that the equation is
"inappropriate for cumulative exposures [because] both the mean and
the variance of actual cumulative exposure received typically increase
in direct proportion to duration" (Document ID 2307, Attachment 4, p.
45). That is, the longer period of time over which a cumulative
exposure is acquired, the higher variance is likely to be, because
cumulative exposure is the sum of the randomly varying exposures
received on different days. However, the exposures referred to in the
equation are the mean job-specific concentrations recorded in the job-
exposure matrix (Exposureobserved) and individuals' actual exposure
concentrations from each job worked (Exposuretrue), not their
cumulative exposures (Document ID 0469, p. 11). Therefore, Dr. Cox's
criticism is unfounded.
Dr. Cox additionally criticized the simulation analysis on the
basis that "[t]he usual starting point for inhalation exposures [is]
with the random number of particles inhaled per breath modeled as a
time-varying (non-homogenous) Poisson process...It is unclear why
ToxaChemica decided to assume (and why OSHA accepted the assumption) of
an underdispersed distribution...rather than assuming a Poisson
distribution" (Document ID 2307, Attachment 4, pp. 45-46). OSHA
believes this criticism also reflects a misunderstanding of Drs.
Steenland and Bartell's analysis. While it could be pertinent to an
analysis of workers' silica dose (the amount of silica that enters the
body), the analysis addresses the concentration of silica in the air
near a worker's breathing zone, not internal dose. The worker's
airborne concentration is the regulated exposure endpoint and the
exposure of interest for OSHA's risk assessment. Thus, the uncertainty
analysis does not need to account for the number of particles inhaled
per breath.
More broadly, Dr. Cox asserted that the Monte Carlo analysis "is
an inappropriate tool for analyzing the effects of exposure measurement
error on estimated exposure-response data," citing a paper by Gryparis
et al. (2009) (Document ID 2307, Attachment 4, p. 44). This paper
indicates that by randomly simulating exposure measurement error, the
Monte Carlo approach can introduce classical error (Document ID 3870,
p. 262). Peer reviewer Dr. Noah Seixas similarly commented that "[t]he
typical Monte Carlo simulation, which is what appears to have been
done, would introduce classical error," that is, error which is
independent of the unobserved variable (in this case, the true exposure
value). He explained that, as a result, "the estimated risks [from the
simulation analyses] are most likely to be underestimates, or
conservatively estimating risk. This is an important aspect of
measurement error with significant implications for risk assessment and
should not be overlooked." (Document ID 3574, pp. 116-117). Addressing
Dr. Cox's broader point, Dr. Seixas in his peer review stated that the
"simulation of exposure measurement error in assessing the degree of
bias that may have been present is a reasonable approach to assessing
this source of uncertainty" (Document ID 3574, pp. 116). Dr. Crump
similarly characterized the uncertainty analysis used in the Steenland
and Bartell study as "a strong effort" that "appropriately applied"
this method (Document ID 3574, pp. 161-162). In this regard, OSHA
generally notes that the advantages and limitations of various methods
to address exposure measurement error in exposure-response models is an
area of ongoing investigation in risk assessment. As shown by the
comments of OSHA's peer reviewers above, there is no scientific
consensus to support Dr. Cox's opinion that the Monte Carlo analysis is
an inappropriate approach to analyze the effects of exposure
measurement error.
In conclusion, through use of high quality studies and modeling,
performance of an uncertainty analysis, and submission of the results
of that analysis to peer review, OSHA maintains that it has relied upon
the best available evidence. In addition, OSHA has carefully considered
the public comments criticizing ToxaChemica's uncertainty analysis and
has concluded that exposure estimation error did not substantially
affect the results in the majority of studies examined (Document ID
1711, pp. 299-314). As a result, it was not necessary to conduct
additional analyses modifying the approach adopted by Drs. Steenland
and Bartell. Accordingly, OSHA reaffirms its determination that the
conclusions of the Agency's risk assessment are correct and largely
unaffected by potential error in exposure measurement.
L. Comments and Responses Concerning Causation
As discussed in Section V.C, Summary of the Review of Health
Effects Literature and Preliminary QRA, OSHA finds, based upon the best
available evidence in the published, peer-reviewed scientific
literature, that exposure to respirable crystalline silica increases
the risk of silicosis, lung cancer, other non-malignant respiratory
disease (NMRD), and renal and autoimmune effects. Exposure to
respirable crystalline silica causes silicosis and is the only known
cause of silicosis. For other health endpoints like lung cancer that
have both occupational and non-occupational sources of exposure, OSHA
used a comprehensive weight-of-evidence approach to evaluate the
published, peer-reviewed scientific studies in the literature to
determine their overall quality and whether there is substantial
evidence that exposure to respirable crystalline silica increases the
risk of a particular health effect. For example, with respect to lung
cancer, OSHA reviewed 60 epidemiological studies covering more than 30
occupational groups in over a dozen industrial sectors and concluded
that exposure to respirable crystalline silica increases the risk of
lung cancer (Document ID 1711, pp. 77-170). This conclusion is
consistent with that of the World Health Organization's International
Agency for Research on Cancer (IARC), HHS' National Toxicology Program
(NTP), the National Institute for Occupational Safety and Health
(NIOSH), and many other organizations and individuals, as evidenced in
the rulemaking record and discussed throughout this section.
In spite of this, and in addition to asserting that OSHA's
Preliminary QRA was affected by many biases, Dr. Cox, on behalf of the
ACC, argued that OSHA failed to conduct statistical analyses of
causation, which led to inaccurate conclusions about causation. He
specifically challenged OSHA's reliance upon the IARC determination of
carcinogenicity, as discussed in Section V.F, Comments and Responses
Concerning Lung Cancer Mortality, and its use of the criteria for
evaluating causality developed by the noted epidemiologist Bradford
Hill (Document ID 2307, Attachment 4, pp. 13-14; 4027, p. 28). The Hill
criteria are nine aspects of an association that should be considered
when examining causation: (1) The strength of the association; (2) the
consistency of the association; (3) the specificity of the association;
(4) the temporal relationship of the association; (5) the biological
gradient (i.e., dose-response curve); (6) the biological plausibility
of the association; (7) coherency; (8) experimentation; and (9) analogy
(Document ID 3948, pp. 295-299).
Instead, Dr. Cox suggested that OSHA use the methods listed in
Table 1 of his 2013 paper, "Improving causal inferences in risk
analysis," which he described as "the most useful study designs and
methods for valid causal analysis and modeling of causal exposure-
response (CER) relations" (Document ID 2307, Attachment 4, p. 11).
Because OSHA did not use these methods, Dr. Cox maintained that the
Agency's Preliminary QRA "asserts causal conclusions based on non-
causal studies, data, and analyses" (Document ID 2307, Attachment 4,
p. 3). He also contended that OSHA "ha[d] conflated association and
causation, ignoring the fact that modeling choices can create findings
of statistical associations that do not predict correctly the changes
in health effects (if any) that would be caused by changes in
exposures" (Document ID 2307, Attachment 4, p. 3). He claimed that
"[t]his lapse all by itself invalidates the Preliminary QRA's
predictions and conclusions" (Document ID 2307, Attachment 4, p. 3).
As discussed below, since OSHA's methodology and conclusions regarding
causation are based on the best available evidence, they are sound.
Consequently, Dr. Cox's contrary position is unpersuasive.
1. IARC Determination
Dr. Cox asserted that OSHA erred in its reliance on the IARC
determination of carcinogenicity for crystalline silica inhaled in the
forms of quartz or cristobalite. He believed OSHA only relied on the
IARC findings because they aligned with the Agency's opinion, noting
that the "IARC analysis involved some of the same researchers, same
methodological flaws, and same gaps in explicit, well-documented
derivations of benefits and conclusions as OSHA's own preliminary QRA"
(Document ID 2307, Attachment 4, pp. 13-14). OSHA, however, relied on
IARC's determination to include lung cancer in its quantitative risk
assessment because it constitutes the best available evidence. For this
reason, Dr. Cox's position is without merit and OSHA's findings are supported
by substantial evidence in the record and reasonable.
As discussed in Section V.F, Comments and Responses Concerning Lung
Cancer Mortality, the IARC classifications and accompanying monographs
are well recognized in the scientific community, and have been
described by scientists as "the most comprehensive and respected
collection of systematically evaluated agents in the field of cancer
epidemiology" (Demetriou et al., 2012, Document ID 4131, p. 1273).
IARC's conclusions resulted from a thorough expert committee review of
the peer-reviewed scientific literature, in which crystalline silica
dust, in the form of quartz or cristobalite, was classified as Group 1,
"carcinogenic to humans," in 1997 (Document ID 2258, Attachment 8, p.
210). Since the publication of these conclusions, the scientific
community has reaffirmed their soundness. In March of 2009, 27
scientists from eight countries participated in an additional IARC
review of the scientific literature and reaffirmed that crystalline
silica dust is a Group 1 carcinogen, i.e., "carcinogenic to humans"
(Document ID 1473, p. 396). Additionally, the HHS' U.S. National
Toxicology Program also concluded that respirable crystalline silica is
a known human carcinogen (Document ID 1164, p. 1).
Further supporting OSHA's reliance on IARC's determination of
carcinogenicity for its quantitative risk assessment is testimony
offered by scientists during the informal public hearings. This
testimony highlighted IARC's carcinogenicity determinations as very
thorough examinations of the scientific literature that demonstrate
that exposure to respirable crystalline silica causes lung cancer. For
example, when asked about Dr. Cox's causation claims during the
informal public hearings, David Goldsmith, Ph.D., noted that causation
was very carefully examined by IARC. He believed that IARC, in its 1997
evaluation of evidence for cancer and silica, "...chose...the
best six studies that were the least confounded for inability to
control for smoking or other kinds of hazardous exposures like
radiation and asbestos and arsenic..." (Document ID 3577, Tr. 894-
896). He also believed it "...crucial...that we pay attention
to those kinds of studies, that we pay attention to the kinds of
studies that were looked at by the IARC cohort that Steenland did from
2001. That's where they had the best evidence" (Document ID 3577, Tr.
894-896).
Regarding IARC's evaluation of possible biases and confounders in
epidemiological studies, as well as its overall determination, Frank
Mirer, Ph.D., of CUNY School of Public Health, representing the AFL-
CIO, testified:
IARC has active practicing scientists review--I've been on two
IARC monographs, but not these monographs, monograph working groups.
It's been dealt with. It's been dealt with over a week of intense
discussion between the scientists who are on these committees, as to
whether there's chance bias in confounding which might have led to
these results, and by 1987 for foundries and 1997 for silica, and
it's been decided and reaffirmed.
So people who don't believe it are deniers, pure and simple.
This is the scientific consensus. I was on the NTP Board of
Scientific Counselors when we reviewed the same data. Known to be a
human carcinogen. Once you know it's a human carcinogen from studies
in humans, you can calculate risk rates (Document ID 3578, Tr. 937).
That OSHA relied on the best available evidence to draw its
conclusions was also affirmed by Dr. Cox's inability to provide
additional studies that would have cast doubt on the Agency's causal
analysis. Indeed, during the informal public hearings, Kenneth Crump,
Ph.D., an OSHA peer reviewer from the Louisiana Tech University
Foundation, asked Dr. Cox if he could identify "any causal studies of
silica that they [OSHA] should have used but did not use?" Dr. Cox
responded: "I think OSHA could look at a paper from around 2007 of
Brown's, on some of the issues and causal analysis, but I think the
crystalline silica area has been behind other particulate matter areas
...in not using causal analysis methods. So no, I can't point to a
good study that they should have included but didn't" (Document ID
3576, Tr. 401-402). In light of the above, OSHA maintains that in
relying on IARC's determination of carcinogenicity, its conclusions on
causation are rooted in the best available evidence.
2. Bradford Hill Criteria and Causality
Dr. Cox also challenged OSHA's use of Hill's criteria for
causation. He claimed that the Bradford Hill considerations were
neither necessary nor sufficient for establishing causation, which was
his reason for failing to include them in the statistical methods
listed in Table 1 of his written comments for objectively establishing
evidence about causation (Document ID 4027, p. 28). As explained below,
based on its review of the record, OSHA finds this position meritless,
as it is unsupported by the best available evidence.
As a preliminary matter, Hill's criteria for causation (Document ID
3948) are generally accepted as a gold standard for causation in the
scientific community. Indeed, OSHA heard testimony during the informal
public hearings and received post-hearing comments indicating that Dr.
Cox's assertion that statistical methods should be used to establish
causality is not consistent with common scientific practice. For
example, Andrew Salmon, Ph.D., an OSHA peer reviewer, wrote:
The identification of causality as opposed to statistical
association is, as described by Bradford Hill in his well-known
criteria, based mainly on non-statistical considerations such as
consistence, temporality and mechanistic plausibility: the role of
statistics is mostly limited to establishing that there is in fact a
quantitatively credible association to which causality may (or may
not) be ascribed. OSHA correctly cites the substantial body of
evidence supporting the association and causality for silicosis and
lung cancer following silica exposure, and also quotes previous
expert reviews (such as IARC). The causal nature of these
associations has already been established beyond any reasonable
doubt, and OSHA's analysis sufficiently reflects this (Document ID
3574, p. 38).
Similarly, Kyle Steenland, Ph.D., Professor, Department of
Environmental Health, Rollins School of Public Health, Emory
University, in response to a question about Dr. Cox's testimony on
causation from Darius Sivin, Ph.D., of the UAW Health and Safety
Department, stated that the Bradford Hill criteria are met for lung
cancer and silicosis:
[M]ost of the Bradford Hill criteria apply here. You know you
can never prove causality. But when the evidence builds up to such
an extent and you have 100 studies and they tend to be fairly
consistent, that's when we draw a causal conclusion. And that was
the case for cigarette smoke in lung cancer. That was the case for
asbestos in lung cancer. And when the evidence builds up to a
certain point, you say, yeah, it's a reasonable assumption that this
thing causes, X causes Y (Document ID 3580, pp. 1243-1244).
As a follow-up, OSHA asked if Dr. Steenland felt that the Bradford
Hill criteria were met for silica health endpoints. Dr. Steenland
replied, "For silicosis or for lung cancer. I had said they're met for
both" (Document ID 3580, p. 1262).
Gary Ginsberg, Ph.D., an OSHA peer reviewer, agreed with Dr.
Steenland, remarking to Dr. Cox during questioning, "I'm a little
dumbfounded about the concern over causality, given all the animal
evidence" (Document ID 3576, Tr. 406). Mr. Park from NIOSH's Risk
Evaluation Branch, in his question to Dr. Cox, echoed the sentiments of
Dr. Ginsberg, stating:
It's ludicrous to hear someone question causality. There's 100
years of research in occupational medicine, in exposure assessment.
People here even in industry would agree that silica they say causes
silicosis, which causes lung cancer. There's some debate about
whether the middle step is required. There's no question that
there's excess lung cancer in silica-exposed populations. We look at
literature, and we identify what we call good studies. Good studies
are ones that look at confounding, asbestos, whatever. We make
judgments. If there's data that allows one to control for
confounding, that's part of the analysis. If there is confounding
that we can't control for, we evaluate it. We ask how bad could it
be? There's a lot of empirical judgment from people who know these
populations, know these exposures, know these industries, who can
make very good judgments about that. We aren't stupid. So I don't
know where you're coming from (Document ID 3576, Tr. 410-411).
Indeed, Kenneth Mundt, Ph.D., testifying on behalf of the
International Diatomite Producers Association (part of the ACC
Crystalline Silica Panel, which included Dr. Cox), and whose research
study was the basis for the Morfeld et al. (2013, Document ID 3843)
paper that reportedly identified a high exposure threshold for
silicosis, also appeared to disagree with Dr. Cox's view of causation.
Dr. Mundt testified that while he thought he could appreciate Dr. Cox's
testimony, at some point there is sufficiently accumulated evidence of
a causal association; he concluded, "I think here, over time, we've
had the advantage with the reduction of exposure to see reduction in
disease, which I think just makes it a home run that the diseases are
caused by, therefore can be prevented by appropriate intervention"
(Document ID 3577, Tr. 639-640).
OSHA notes that Dr. Cox, upon further questioning by Mr. Park,
appeared to concede that exposure to respirable crystalline silica
causes silicosis; Dr. Cox stated, "I do not question that at
sufficiently high exposures, there are real effects" (Document ID
3576, Tr. 412). Later, when questioned by Anne Ryder, an attorney in
the Solicitor of Labor's office, he made a similar statement: "I do
take it as given that silica at sufficiently high and prolonged
exposures causes silicosis" (Document ID 3576, Tr. 426). Based upon
this testimony of Dr. Cox acknowledging that silica exposure causes
silicosis, OSHA interprets his concern with respect to silicosis to be
not one of causation, but rather a concern with whether there is a
silicosis threshold (i.e., that exposure to crystalline silica must
generally be above some level in order for silicosis to occur). Indeed,
OSHA peer reviewer Brian Miller, Ph.D., noted in his post-hearing
comments that Dr. Cox, when challenged, accepted that silica was causal
for silicosis, "but questioned whether there was evidence for
increased risks at low concentrations; i.e. whether there was a
threshold" (Document ID 3574, p. 31). Thresholds for silicosis are
addressed in great detail in Section V.I, Comments and Responses
Concerning Thresholds for Silica-Related Diseases.
Based on the testimony and written comments of numerous scientists
representing both public health and industry--all of whom agree that
causation is established by applying the Bradford Hill criteria and
examining the totality of the evidence--OSHA strongly disagrees with
Dr. Cox's claims that the Bradford Hill criteria are inadequate to
evaluate causation in epidemiology and that additional statistical
techniques are needed to establish causation. OSHA defends its reliance
on the IARC determination of 1997 and re-determination of 2012 that
crystalline silica is a causal agent for lung cancer. OSHA's own Review
of Health Effects Literature further demonstrates the totality of the
evidence supporting the causality determination (Document ID 1711).
Indeed, other than Dr. Cox representing the ACC, no other individual or
entity questioned causation with respect to silicosis. Even Dr. Cox's
questioning of causation for silicosis appears to be more of a question
about thresholds, which is discussed in Section V.I, Comments and
Responses Concerning Thresholds for Silica-Related Diseases.
3. Dr. Cox's Proposed Statistical Methods
OSHA reviewed the statistical methods provided by Dr. Cox in Table
1 of his 2013 paper, "Improving causal inferences in risk analysis,"
(Document ID 2307, Attachment 4, p. 11), and explains below why the
Agency did not adopt them. For example, Intervention Time Series
Analysis (ITSA), as proposed by Dr. Cox in his Table 1, is a method for
assessing the impact of an intervention or shock on the trend of
outcomes of interest (Gilmour et al., 2006, cited in Document ID 2307,
Attachment 4, p. 11). Implementing ITSA requires time series data
before and after the intervention for both the dependent variable
(e.g., disease outcome) and independent variables (e.g., silica
exposure and other predictors), as well as the point of occurrence of
the intervention. Although time-series data are frequently available in
epidemiological studies, for silica we do not have a specific
"intervention point" comparable to the implementation of a new OSHA
standard that can be identified and analyzed. Rather, changes in
exposure controls tend to be iterative and piecemeal, gradually
bringing workers' exposures down over the course of a facility's
history and affecting job-specific exposures differently at different
points in time. Furthermore, individual workers' exposures change
continually with new job assignments and employment. In addition, in a
situation where the intervention really reduces the adverse outcome to
a low level, such as 1/1000 lifetime excess risk, ITSA would require an
enormous observational database in order to be able to estimate the
actual post-intervention level of risk. OSHA believes the standard risk
analysis approach of estimating an exposure-response relationship based
on workers' exposures over time and using this model to predict the
effects of a new standard on risk appropriately reflects the typical
pattern of multiple and gradual changes in the workers' exposures over
time found in most industrial facilities.
Another method listed in Dr. Cox's Table 1, marginal structural
models (MSM), was introduced in the late 1990s (Robins, 1998, cited in
Document ID 2307, Attachment 4, p. 11) to address issues that can arise
in standard modeling approaches when time-varying exposure and/or time-
dependent confounders are present.\10\ These methods are actively being
explored in the epidemiological literature, but have not yet become a
standard method in occupational epidemiology. As such, OSHA faces some
of the same issues with MSM as were previously noted with BMA:
Published, peer-reviewed studies using this approach are not available
for the silica literature, and best practices are not yet well
established. Thus, the incorporation of MSM in the silica risk
assessment is not possible using the currently available literature and
would be premature for OSHA's risk assessment generally.
---------------------------------------------------------------------------
\10\ A time-dependent confounder is a covariate whose post-
baseline value is a risk factor for both the subsequent exposure and
the outcome.
---------------------------------------------------------------------------
In addition, in his post-hearing brief, Dr. Cox contended that
"[a] well-done QRA should explicitly address the causal fraction (and
explain the value used), rather than tacitly assuming that it is 1"
(Document ID 4027, p. 4). However, this claim is without grounds. OSHA
understands Dr. Cox's reference to the "causal fraction" to mean
that, when estimating risk from an exposure-response model, only a fraction
of the total estimated risk should be attributed to disease caused by
the occupational exposure of interest. The Agency notes that the
"causal fraction" of risk is typically addressed through the use of
life table analyses, which incorporate background rates for the disease
in question. Such analyses, which OSHA used in its Preliminary QRA,
calculate the excess risk, over and above background risk, that is
solely attributable to the exposure in question. Thus, there is no need
to estimate a causal fraction due to exposure. These approaches are
further discussed in Section V.M, Comments and Responses Concerning
Working Life, Life Tables, and Dose Metric. Furthermore, nowhere in the
silica epidemiological literature has the use of an alternative
"causal fraction" approach to ascribing the causal relationship
between silica exposure and silicosis and lung cancer been deemed
necessary to reliably estimate risk.
4. The Assertion That the Silica Scientific Literature May Be False
Dr. Cox also asserted that the same biases and issues with
causation in OSHA's Quantitative Risk Assessment (QRA) were likewise
present in the silica literature. He wrote, "In general, the
statistical methods and causal inferences described in this literature
are no more credible or sound than those in OSHA's Preliminary QRA, and
for the same reasons" (Document ID 2307, Attachment 4, p. 30).
The rulemaking record contains evidence that contradicts Dr. Cox's
claims with respect to the scientific foundation of the QRA. Such
evidence includes scientific testimony and the findings of many expert
bodies, including IARC, the HHS National Toxicology Program, and NIOSH,
concluding that exposure to respirable crystalline silica causes lung
cancer. At the public hearing, Dr. Steenland, Professor at Emory
University, testified that the body of evidence pertaining to silica
was of equal quality to that of other occupational health hazards
(Document ID 3580, pp. 1245-1246). Dr. Goldsmith similarly testified:
Silica dust...is like asbestos and cigarette smoking in that
exposure clearly increases the risk of many diseases. There have
been literally thousands of research studies on exposure to
crystalline silica in the past 30 years. Almost every study tells
the occupational research community that workers need better
protection to prevent severe chronic respiratory diseases, including
lung cancer and other diseases in the future. What OSHA is proposing
to do in revising the workplace standard for silica seems to be a
rational response to the accumulation of published evidence
(Document ID 3577, Tr. 865-866).
OSHA agrees with these experts, whose positive view of the science
supporting the need for better protection from silica exposures stands
in contrast to Dr. Cox's claim regarding what he believes to be the
problematic nature of the silica literature. Dr. Cox asserted in his
written statement:
Scientists with subject matter expertise in areas such as
crystalline silica health effects epidemiology are not necessarily
or usually also experts in causal analysis and valid causal
interpretation of data, and their causal conclusions are often
mistaken, with a pronounced bias toward declaring and publishing
findings of `significant' effects where none actually exists (false
positives). This has led some commentators to worry that `science is
failing us,' due largely to widely publicized but false beliefs
about causation (Lehrer, 2012); and that, in recent times, `Most
published research findings are wrong' (Ioannadis, 2005), with the
most sensational and publicized claims being most likely to be
wrong. (Document ID 2307, Attachment 4, pp. 15-16).
Moreover, during the public hearing, Dr. Cox stated that, with
respect to lung cancer in the context of crystalline silica, the
literature base may be false:
MR. PERRY [OSHA Director of the Directorate of Standards and
Guidance]: So as I understand it, you basically think there's a good
possibility that the entire literature base, with respect to lung
cancer now, I'm talking about, is wrong?
DR. COX: You mean with respect to lung cancer in the context of
crystalline silica?
MR. PERRY: Yes, sir.
DR. COX: I think that consistent with the findings of Lauer
[Lehrer] and Ioannidis and others, I think that it's very possible
and plausible that there is a consistent pattern of false positives
in the literature base, yes. And that implies, yes, they are wrong.
False positives are false (Document ID 3576, Tr. 423).
The Ioannidis paper (Document ID 3851) used mathematical constructs
to purportedly demonstrate that most claimed research findings are
false, and then provided suggestions for improvement (Document ID 3851,
p. 0696). Two of his suggestions appear particularly relevant to the
silica literature: "Better powered evidence, e.g., large studies or
low-bias meta-analyses, may help, as it comes closer to the unknown
`gold' standard. However, large studies may still have biases and these
should be acknowledged and avoided"; and "second, most research
questions are addressed by many teams, and it is misleading to
emphasize the statistically significant findings of any single team.
What matters is the totality of the evidence" (Document ID 3851, pp.
0700-0701). OSHA finds no merit in the claim that most claimed research
findings are false. Instead, it finds that the silica literature for
lung cancer is overall trustworthy, particularly because the "totality
of the evidence" characterized by large studies demonstrates a causal
relationship between crystalline silica exposure and lung cancer, as
IARC determined in 1997 and 2012 (Document ID 2258, Attachment 8, p.
210; 1473, p. 396).
OSHA likewise notes that there was disagreement on Ioannidis'
methods and conclusions. Jonathan D. Wren of the University of
Oklahoma, in a correspondence to the journal that published the paper,
noted that Ioannidis, "after all, relies heavily on other studies to
support his premise, so if most (i.e., greater than 50%) of his cited
studies are themselves false (including the eight of 37 that pertain to
his own work), then his argument is automatically on shaky ground"
(Document ID 4087, p. 1193). In addition, Steven Goodman of Johns
Hopkins School of Medicine and Sander Greenland of the University of
California, Los Angeles, performed a substantive mathematical review
(Document ID 4081) of the Ioannidis models and concluded in their
correspondence to the same journal that "the claims that the model
employed in this paper constitutes `proof' that most published medical
research claims are false, and that research in `hot' areas is most
likely to be false, are unfounded" (Document ID 4095, p. 0773).
Christiana A. Demetriou, Imperial College London, et al. (2012),
analyzed this issue of potential false positive associations in the
field of cancer epidemiology (Document ID 4131). They examined the
scientific literature for 509 agents classified by IARC as Group 3,
"not classifiable as to its carcinogenicity to humans" (Document ID
4131). Of the 509 agents, 37 had potential false positive associations
in the studies reviewed by IARC; this represented an overall frequency
of potential false positive associations between 0.03 and 0.10
(Document ID 4131). Regarding this overall false positive frequency of
about 10 percent, the authors concluded, "In terms of public health
care decisions, given that the production of evidence is historical,
public health care professionals are not expected to react immediately
to a single positive association. Instead, they are likely to wait for
further support or enough evidence to reach a consensus, and if a
hypothesis is repeatedly tested, then any initial false-positive
results will be quickly undermined" (Document ID 4131, p. 1277). The
authors also cautioned that "Reasons for criticisms that are most
common in studies with false-positive findings can also underestimate
an association and in terms of public health care, false-negative
results may be a more important problem than false-positives"
(Document ID 4131, pp. 1278-1279). Thus, this study suggested that the
false positive frequency in published literature is actually rather
low, and stressed the importance of considering the totality of the
literature, rather than a single study.
Given these responses to Ioannidis, OSHA fundamentally rejects the
claim that most published research findings are false. The Agency
concludes that, most likely, where, as here, there are multiple,
statistically significant positive findings of an association between
silica and lung cancer made by different researchers in independent
studies looking at distinct cohorts, the chances that there is a
consistent pattern of false positives are small; OSHA's mandate is met
when the weight of the evidence in the body of science constituting the
best available evidence supports such a conclusion.
M. Comments and Responses Concerning Working Life, Life Tables, and
Dose Metric
As discussed in Section V.C, Summary of the Review of Health
Effects Literature and Preliminary QRA, OSHA presented risk estimates
associated with exposure over a working lifetime to 25, 50, 100, 250,
and 500 [mu]g/m\3\ respirable crystalline silica (corresponding to
cumulative exposures over 45 years to 1.125, 2.25, 4.5, 11.25, and 22.5
mg/m\3\-yrs). For mortality from silica-related disease (i.e., lung
cancer, silicosis and non-malignant respiratory disease (NMRD), and
renal disease), OSHA estimated lifetime risks using a life table
analysis that accounted for background and competing causes of death.
The mortality risk estimates were presented as excess risk per 1,000
workers for exposures over an 8-hour working day, 250 days per year,
and a 45-year working lifetime. This is a legal standard that OSHA
typically uses in health standards to satisfy the statutory mandate to
"set the standard which most adequately assures, to the extent
feasible, that no employee will suffer material impairment of health or
functional capacity even if such employee has regular exposure to the
hazard dealt with by such standard for the period of his working
life." 29 U.S.C. 655(b)(5). For silicosis morbidity, OSHA based its
risk estimates on cumulative risk models used by various investigators
to develop quantitative exposure-response relationships. These models
characterized the risk of developing silicosis (as detected by chest
radiography) up to the time that cohort members (including both active
and retired workers) were last examined. Thus, risk estimates derived
from these studies represent less-than-lifetime risks of developing
radiographic silicosis. OSHA did not attempt to estimate lifetime risk
(i.e., up to age 85) for silicosis morbidity because the relationships
between age, time, and disease onset post-exposure have not been well
characterized.
OSHA received critical comments from representatives of the ACC and
the Chamber. These commenters expressed concern that (1) the working
lifetime exposure of 45 years was not realistic for workers, (2) the
use of life tables was improper and alternative methods should be used,
and (3) the cumulative exposure metric does not consider the exposure
intensity and possible resulting dose-rate effects. OSHA examines these
comments in detail in this section, and shows why they do not alter its
conclusion that the best available evidence in the rulemaking record
fully supports the Agency's use of a 45-year working life in a life
table analysis with cumulative exposure as the exposure metric of
concern.
1. Working Life
The Chamber commented that 45-year career silica exposures do not
exist in today's working world, particularly in "short term work-site
industries" such as construction and energy production (Document ID
4194, p. 11; 2288, p. 11). The Chamber stated that careers in these
jobs are closer to 6 years, pointing out that OSHA's contractor, ERG,
estimated a 64 percent annual turnover rate in the construction
industry. Referring to Section 6(b)(5) of the Occupational Safety and
Health (OSH) Act of 1970, the Chamber concluded, "OSHA improperly
inflates risk estimates with its false 45-year policy, contradicting
the Act, which requires standards based on actual, `working life'
exposures--not dated hypotheticals" (Document ID 4194, pp. 11-12;
2288, pp. 11-12).
As stated previously, OSHA believes that the 45-year exposure
estimate satisfies its statutory obligation to evaluate risks from
exposure over a working life, and notes that the Agency has
historically based its significance-of-risk determinations on a 45-year
working life from age 20 to age 65 in each of its substance-specific
rulemakings conducted since 1980. The Agency's use of a 45-year working
life in risk assessment has also been upheld by the DC Circuit (Bldg &
Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1264-65 (D.C. Cir. 1988))
(also see Section II, Pertinent Legal Authority). Even if most workers
are not exposed for such a long period, some will be, and OSHA is
legally obligated to set a standard that protects those workers to the
extent such standard is feasible. For reasons explained throughout this
preamble, OSHA has set the PEL for this standard at 50 [micro]g/m\3\
TWA. In setting the PEL, the Agency reasoned that while this level does
not eliminate all risk from 45 years of exposures for each employee, it
is the lowest level feasible for most operations.
In addition, OSHA heard testimony and received several comments
with accompanying data that support a 45-year working life in affected
industries. For example, six worker representatives of the
International Union of Bricklayers and Allied Craftworkers (BAC), which
represents a portion of the unionized masonry construction industry
(Document ID 4053, p. 2), raised their hands in the affirmative when
asked if they had colleagues who worked for longer than 40 years in
their trade (Document ID 3585, Tr. 3053). Following the hearings, BAC
reviewed its International Pension Fund and counted 116 members who had
worked in the industry for 40 years or longer. It noted that this
figure was likely an understatement, as many workers had previous
experience in the industry prior to being represented by BAC, and many
BAC affiliates did not begin participation in the Fund until
approximately a decade after its establishment in 1972 (Document ID
4053, p. 2).
OSHA heard similar testimony from representatives of other labor
groups and unions. Appearing with the Laborers' Health and Safety Fund
of North America (LHSFNA), Eddie Mallon, a long-time member of the New
York City tunnel workers' local union, testified that he had worked in
the tunnel business for 50 years, mainly on underground construction
projects (Document ID 3589, Tr. 4209). Appearing with the United
Steelworkers, Allen Harville, of the Newport News Shipbuilding Facility
and Drydock, testified that there are workers at his shipyard with more
than 50 years of experience. He also believed that 15 to 20 percent of
workers had 20 to 40 years of experience (Document ID 3584, Tr. 2571).
In addition, several union representatives appearing with the
Building and Construction Trades Department (BCTD) of the American
Federation of Labor and Congress of Industrial Organizations (AFL-CIO)
also commented on the working life exposure estimate. Deven Johnson, of the
Operative Plasterers' and Cement Masons' International Association,
testified that he thought 45 years was relevant, as many members of his
union had received gold cards for 50 and 60 years of membership; he
also noted that there was a 75-year member in his own local union
(Document ID 3581, Tr. 1625-1626). Similarly, Sarah Coyne, representing
the International Union of Painters and Allied Trades, testified that
45 years was adequate, as "we have many, many members who continue to
work out in the field with the 45 years" (Document ID 3581, Tr. 1626).
Charles Austin, of the International Association of Sheet Metal, Air,
Rail and Transportation Workers, added that thousands of workers in the
union's dust screening program have been in the field for 20 to 30
years (Document ID 3581, Tr. 1628-1629).
In its post-hearing comment, the BCTD submitted evidence on behalf
of the United Association of Plumbers, Fitters, Welders and HVAC
Service Techs, which represents a portion of the workers in the
construction industry. A review of membership records for this
association revealed 35,649 active members with 45 years or more of
service as a member of the union. Laurie Shadrick, Safety and Health
National Coordinator for the United Association, indicated that this
membership figure is considered an underestimate, as many members had
previous work experience in the construction industry prior to joining
the union, or were not tracked by the union after transitioning to
other construction trades (Document ID 4073, Attachment 1b). The post-
hearing comment of the BCTD also indicated a trend of an aging
workforce in the construction industry, with workers 65 years of age
and older predicted to increase from 5 percent in 2012 to 8.3 percent
in 2022 (Document ID 4073, Attachment 1a, p. 1). This age increase is
likely due to the fact that few construction workers have a defined
benefit pension plan, and the age for collecting Social Security
retirement benefits has been increasing; as a result, many construction
workers are staying employed for longer in the industry (Document ID
4073, Attachment 1a, p. 1). Thus, the BCTD expressed its support for
using a 45-year working life in the construction industry for risk
assessment purposes (Document ID 4073, Attachment 1a, p. 1).
In addition to BAC and BCTD, OSHA received post-hearing comments on
the 45-year working life from the International Union of Operating
Engineers (IUOE) and the American Federation of State, County and
Municipal Employees (AFSCME). The IUOE reviewed records of the Central
Pension Fund, in which IUOE construction and stationary local unions
participate, and determined that the average years of service amongst
all retirees (75,877 participants) was 21.34 years, with a maximum of
49.93 years of active service. Of these retirees, 15,836 participants
recorded over 30 years of service, and 1,957 participants recorded over
40 years of service (Document ID 4025, pp. 6-7). The IUOE also pointed
to the testimony of Anthony Bodway, Special Projects Manager at Payne &
Dolan, Inc. and appearing with the National Asphalt Pavement
Association (NAPA), who indicated that some workers in his company's
milling division had been with the company anywhere from 35 to 40 years
(Document ID 3583, Tr. 2227, 2228). Similarly, the AFSCME reported
that, according to its 2011 poll, 49 percent of its membership had over
10 years of experience, and 21 percent had over 20 years (Document ID
3760, p. 2).
The rulemaking record on this topic of the working life thus
factually refutes the Chamber's assertion that "no such 45-year career
silica exposures exist in today's working world, particularly in
construction, energy production, and other short term work-site
industries" (Document ID 4194, p. 11; 2288, p. 11). Instead, OSHA
concludes that the rulemaking record demonstrates that the Agency's use
of a 45-year working life as a basis for estimating risk is legally
justified and factually appropriate.
2. Life Tables
Dr. Cox, on behalf of the ACC, commented that OSHA should use
"modern methods," such as Bayesian competing-risks analyses,
expectation-maximization (EM) methods, and copula-based approaches that
account for subdistributions and interdependencies among competing
risks (Document ID 2307, Attachment 4, p. 61). Such methods, according
to Dr. Cox, are needed "[t]o obtain risk estimates...that have
some resemblance to reality, and that overcome known biases in the
na[iuml]ve life table method used by OSHA" (Document ID 2307,
Attachment 4, p. 61). Dr. Cox then asserted that the life table method
used in the following studies to estimate mortality risks is also
incorrect: Steenland et al. (2001a, Document ID 0452), Rice et al.
(2001, Document ID 1118), and Attfield and Costello (2004, Document ID
0285) (Document ID 2307, Attachment 4, pp. 61-63).
OSHA does not agree that the life table method it used to estimate
mortality risks is incorrect or inappropriate. Indeed, the Agency's
life table approach is a standard method commonly used to estimate the
quantitative risks of mortality. As pointed out by Rice et al. (2001),
the life table method was developed by the National Research Council's
BEIR IV Committee on the Biological Effects of Ionizing Radiations
(BEIR), Board of Radiation Effects Research, in its 1988 publication on
radon (Document ID 1118, p. 40). OSHA notes that the National Research
Council is the operating arm of the National Academy of Sciences and
the National Academy of Engineering, and is highly respected in the
scientific community. As further described by Rice et al., an
"advantage of this [actuarial] method is that it accounts for
competing causes of death which act to remove a fraction of the
population each year from the risk of death from lung cancer so that it
is not necessary to assume that all workers would survive these
competing causes to a given age" (Document ID 1118, p. 40). Because
this life table method is generally accepted in the scientific
community and has been used in a variety of peer-reviewed, published
journal articles, including some of the key studies relied upon by the
Agency in its Preliminary QRA (e.g., Rice et al., 2001, Document ID
1118, p. 40; Park et al., 2002, 0405, p. 38), OSHA believes it is
appropriate here.
Regarding the alternative methods proposed by Dr. Cox, OSHA
believes that these methods are not widely used in the occupational
epidemiology community. In addition, OSHA notes that Dr. Cox did not
provide any alternate risk estimates to support the use of his proposed
alternative methods, despite the fact that the Agency made its life
table data available in the Review of Health Effects Literature and
Preliminary QRA (Document ID 1711, pp. 360-378). Thus, for these
reasons, OSHA disagrees with Dr. Cox's claim that the life table method
used by the Agency to estimate quantitative risks was inappropriate.
3. Exposure Metric
In its risk assessment, OSHA uses cumulative exposure, i.e.,
average exposure concentration multiplied by duration of exposure, as
the exposure metric to quantify exposure-response relationships. It
uses this metric because each of the key epidemiological studies on
which the Agency relied to estimate risks used cumulative exposure as
the exposure metric to quantify exposure-response relationships,
although some also reported significant relationships based on exposure
intensity (Document ID 1711, p. 342). As noted in the Review of Health
Effects Literature, the majority of studies for lung cancer and silicosis
morbidity and mortality have consistently found significant positive
relationships between risk and cumulative exposure (Document ID 1711,
p. 343). For example, nine of the ten epidemiological studies included
in the pooled analysis by Steenland et al. (2001a, Document ID 0452)
showed positive exposure coefficients when exposure was expressed as
cumulative exposure (Document ID 1711, p. 343).
Commenting on this exposure metric, the ACC argued that cumulative
exposure undervalues the role of exposure intensity, as some studies of
silicosis have indicated a dose-rate effect, i.e., short-term exposure
to high concentrations results in greater risk than longer-term
exposure to lower concentrations at an equivalent cumulative exposure
level (Document ID 4209, p. 58; 2307, Attachment A, pp. 93-94). The ACC
added that, given that silica-related lung cancer and silicosis may
both involve an inflammation-mediated mechanism, a dose-rate effect
would also be expected for lung cancer (Document ID 4209, p. 58). It
concluded that "assessments of risk based solely on cumulative
exposure do not account adequately for the role played by intensity of
exposure and, accordingly, do not yield reliable estimates of risk"
(Document ID 4209, p. 68). Patrick Hessel, Ph.D., representing the
Chamber, pointed to the initial comments of OSHA peer reviewer Kenneth
Crump, Ph.D., who stated that "[n]ot accounting for a dose-rate
effect, if one exists, could overestimate risk at lower
concentrations" (Document ID 4016, p. 2, citing 1716, pp. 165-167).
OSHA acknowledges these concerns regarding the exposure metric and
finds them to have some merit. However, it notes that the best
available studies use cumulative exposure as the exposure metric, as in
common in occupational epidemiological studies. As discussed below,
there is also substantial good evidence in the record supporting the
use of cumulative exposure as the exposure metric for crystalline
silica risk assessment.
Paul Schulte, Ph.D., of NIOSH testified that "cumulative exposure
is a standard and appropriate metric for irreversible effects that
occur soon after actual exposure is experienced. For lung cancer and
nonmalignant respiratory disease, NMRD mortality, cumulative exposure
lagged for cancer is fully justified...For silicosis risk
assessment purposes, cumulative exposure is a reasonable and practical
choice" (Document ID 3579, Tr. 127). NIOSH also conducted a simulated
dose rate analysis for silicosis incidence with data from a Chinese tin
miners cohort and, in comparing exposure metrics, concluded that the
best fit to the data was cumulative exposure with no dose-rate effect
(Document ID 4233, pp. 36-39). This finding is consistent with the
testimony of Dr. Steenland, who stated, "Cumulative exposure, I might
say, is often the best predictor of chronic disease in general, in
epidemiology" (Document ID 3580, Tr. 1227). OSHA also notes that using
a cumulative exposure metric (e.g., mg/m\3\-yrs) factors in both
exposure intensity and duration, while using only an exposure intensity
metric (e.g., [mu]g/m\3\) ignores the influence of exposure duration.
Dr. Crump's comment that "[e]stimating risk based on an `incomplete'
exposure metric like average exposure is not recommended....
[E]xposure to a particular air concentration for one week is unlikely
to carry the same risk as exposure to that concentration for 20 years,
although the average exposures are the same" also supports the use of
a cumulative exposure metric (Document ID 1716, p. 166).
With regard to a possible dose-rate effect, OSHA agrees with Dr.
Crump that if one exists and is unaccounted for, the result could be an
overestimation of risks at lower concentrations (Document ID 1716, pp.
165-167). OSHA is aware of two studies discussed in its Review of
Health Effects Literature and Preliminary QRA that examined dose-rate
effects on silicosis exposure-response (Document ID 1711, pp. 342-344).
Neither study found a dose-rate effect relative to cumulative exposure
at silica concentrations near the previous OSHA PEL (Document ID 1711,
pp. 342-344). However, they did observe a dose-rate effect in instances
where workers were exposed to crystalline silica concentrations far
above the previous PEL (i.e., several-fold to orders of magnitude above
100 [mu]g/m\3\) (Buchanan et al., 2003, Document ID 0306; Hughes et
al., 1998, 1059). For example, the Hughes et al. (1998) study of
diatomaceous earth workers found that the relationship between
cumulative silica exposure and risk of silicosis was steeper for
workers hired prior to 1950 and exposed to average concentrations above
500 [micro]g/m\3\ compared to workers hired after 1950 and exposed to
lower average concentrations (Document ID 1059). Similarly, the
Buchanan et al. (2003) study of Scottish coal miners adjusted the
cumulative exposure metric in the risk model to account for the effects
of exposures to high concentrations where the investigators found that,
at concentrations above 2000 [micro]g/m\3\, the risk of silicosis was
about three times higher than the risk associated with exposure to
lower concentrations but at the same cumulative exposure (Document ID
0306, p. 162). OSHA concluded that there is little evidence that a
dose-rate effect exists at concentrations in the range of the previous
PEL (100 [micro]g/m\3\) (Document ID 1711, p. 344). However, at the
suggestion of Dr. Crump, OSHA used the model from the Buchanan et al.
study in its silicosis morbidity risk assessment to account for
possible dose-rate effects at high average concentrations (Document ID
1711, pp. 335-342). OSHA notes that the risk estimates in the exposure
range of interest (25-500 [mu]g/m\3\) derived from the Buchanan et al.
(2003) study were not appreciably different from those derived from the
other studies of silicosis morbidity (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk, Table VI-1.).
In its post-hearing brief, NIOSH also added that a "detailed
examination of dose rate would require extensive and real time exposure
history which does not exist for silica (or almost any other agent)"
(Document ID 4233, p. 36). Similarly, Dr. Crump wrote, "Having noted
that there is evidence for a dose-rate effect for silicosis, it may be
difficult to account for it quantitatively. The data are likely to be
limited by uncertainty in exposures at earlier times, which were likely
to be higher" (Document ID 1716, p. 167). OSHA agrees with Dr. Crump,
and believes that it has used the best available evidence to estimate
risks of silicosis morbidity and sufficiently accounted for any dose-
rate effect at high silica average concentrations by using the Buchanan
et al. (2003) study.
For silicosis/NMRD mortality, the ACC noted that Vacek et al.
(2009, Document ID 2307, Attachment 6) reported that, in their
categorical analysis of the years worked at various levels of exposure
intensity, only years worked at >200 [micro]g/m\3\ for silicosis and
>300 [micro]g/m\3\ for NMRD were associated with increased mortality
(Document ID 2307, Attachment A, p. 93, citing 2307, Attachment 6, pp.
21, 23). However, OSHA believes it to be inappropriate to consider
these results in isolation from the other study findings, and notes
that Vacek et al. (2009) also reported statistically significant
associations of silicosis mortality with cumulative exposure, exposure
duration, and average exposure intensity in their continuous analyses
with univariate models; for NMRD mortality, there were statistically
significant associations with cumulative exposure and average exposure
intensity (Document ID 2307, Attachment 6, pp. 21, 23).
In addition, OSHA notes that Vacek et al. (2009) did not include
both an exposure intensity term and a cumulative exposure term in the
multivariate model, after testing for correlation between cumulative
exposure and years at particular exposure intensity; such a model would
indicate how exposure intensity affects any relationship with
cumulative exposure. As Dr. Crump stated in his comments:
To demonstrate evidence for a dose-rate effect that is not
captured by cumulative exposure, it would be most convincing to show
some effect of dose rate that is in addition to the effect of
cumulative exposure. To demonstrate such an effect one would need to
model both cumulative exposure and some effect of dose rate, and
show that adding the effect of dose rate makes a statistically
significant improvement to the model over that predicted by
cumulative exposure alone (Document ID 1716, p. 166).
Indeed, both Buchanan et al. (2003, Document ID 0306) and Hughes et
al. (1998, Document ID 1059), when examining possible dose-rate effects
for silicosis morbidity, specifically included both cumulative exposure
and exposure intensity in their multivariate models. Additionally, as
described in the lung cancer section of this preamble, the Vacek et al.
study may be affected by both exposure misclassification and the
healthy worker survivor effect. Both of these biases may flatten an
exposure-response relationship, obscuring the relationship at lower
exposure levels, which could be the reason why a significant effect was
not found at the lower exposure levels in the Vacek et al. (2009,
Document ID 2307, Attachment 6) multivariate analysis.
Regarding lung cancer mortality, the ACC pointed out that Steenland
et al. (2001a, Document ID 0452) acknowledged that duration of exposure
did not fit the data well in their pooled lung cancer study. The ACC
indicated that exposure intensity should be considered (Document ID
2307, Attachment A, p. 93; 4209, p. 58, citing 0452, p. 779). OSHA
interpreted the results of the Steenland et al. (2001, Document ID
0452) study to simply mean that duration of exposure alone was not a
good predictor for lung cancer mortality, where a lag period may be
important between the exposure and the development of disease. Indeed,
Steenland et al. found the model with logged cumulative exposure, with
a 15-year lag, to be a strong predictor of lung cancer (Document ID
0452, p. 779). Additionally, no new evidence of a dose-rate effect in
lung cancer studies was submitted to the record.
For these reasons, OSHA does not believe there to be any persuasive
data in the record that supports a dose-rate effect at exposure
concentrations near the revised or previous PELs. OSHA concludes that
cumulative exposure is a reasonable exposure metric on which to base
estimates of risk to workers exposed to crystalline silica in the
exposure range of interest (25 to 500 [mu]g/m\3\).
N. Comments and Responses Concerning Physico-Chemical and Toxicological
Properties of Respirable Crystalline Silica
As discussed in the Review of Health Effects Literature and
Preliminary Quantitative Risk Assessment (Document ID 1711, pp. 344-
350), the toxicological potency of crystalline silica is influenced by
a number of physical and chemical factors that affect the biological
activity of the silica particles inhaled in the lung. The toxicological
potency of crystalline silica is largely influenced by the presence of
oxygen free radicals on the surfaces of respirable particles; these
chemically-reactive oxygen species interact with cellular components in
the lung to promote and sustain the inflammatory reaction responsible
for the lung damage associated with exposure to crystalline silica. The
reactivity of particle surfaces is greatest when crystalline silica has
been freshly fractured by high-energy work processes such as abrasive
blasting, rock drilling, or sawing concrete materials. As particles age
in the air, the surface reactivity decreases and exhibits lower
toxicologic potency (Porter et al., 2002, Document ID 1114; Shoemaker
et al., 1995, 0437; Vallyathan et al., 1995, 1128). In addition,
surface impurities have been shown to alter silica toxicity. For
example, aluminum and aluminosilicate clay on silica particles has been
shown to decrease toxicity (Castranova et al., 1997, Document ID 0978;
Donaldson and Borm, 1998, 1004; Fubini, 1998, 1016; Donaldson and Borm,
1998, Document ID 1004; Fubini, 1998, 1016).
In the preamble to the proposed standard, OSHA preliminarily
concluded that although there is evidence that several environmental
influences can modify surface activity to either enhance or diminish
the toxicity of silica, the available information was insufficient to
determine to what extent these influences may affect risk to workers in
any particular workplace setting (Document 1711, p. 350). NIOSH
affirmed OSHA's preliminary conclusion regarding the silica-related
risks of exposure to clay-occluded quartz particles, which was based on
what OSHA believed to be the best available evidence. NIOSH stated:
NIOSH concurs with this assessment by OSHA. Currently available
information is not adequate to inform differential quantitative risk
management approaches for crystalline silica that are based on
surface property measurements. Thus, NIOSH recommends a single PEL
for respirable crystalline silica without consideration of surface
properties (Document ID 4233, p. 44).
Two rulemaking participants, the Brick Industry Association (BIA),
which represents distributors and manufacturers of clay brick, and the
Sorptive Minerals Institute (SMI), which represents many industries
that process and mine sorptive clays for consumer products and
commercial and industrial applications, provided comment and supporting
evidence that the crystalline silica encountered in their workplace
environments presents a substantially lower risk of silica-related
disease than that reflected in the Agency's Preliminary QRA.
BIA argued that the quartz particles found in clays and shales used
in clay brick are occluded in aluminum-rich clay coatings. BIA
submitted to the record several studies indicating reduced toxicity and
fibrogenicity from exposure to quartz in aluminum-rich clays (Document
ID 2343, Attachment 2, p. 2). It purported that "OSHA lacks the
statutory authority to impose the proposed rule upon the brick and
structural clay manufacturing industry because employees in that
industry do not face a significant risk of material impairment of
health or functional capacity" (Document ID 2242, pp. 2-3). BIA
concluded that its industry should be exempted from the rule, stating:
"OSHA should exercise its discretion to exempt the brickmaking
industry from compliance with the proposed rule unless and until it
determines how best to take into account the industry's low incidence
of adverse health effects from silica toxicity" (Document ID 2242, p.
11).
SMI argued that silica in sorptive clays exists as either amorphous
silica or as geologically ancient, occluded quartz, "neither of which
pose the health risk identified and studied in OSHA's risk assessment"
(Document ID 4230, p. 2). SMI further contended that OSHA's discussion
of aged silica "does not accurately reflect the risk of geologically
ancient, (occluded) silica formed millions of years ago found in
sorptive clays" (Document ID 4230, p. 2). Additionally, SMI noted that
clay products produced by the sorptive minerals industry are not heated
to high temperatures or fractured, making them different from brick and
pottery clays (Document ID 2377, p. 7). In support of its position, SMI
submitted to the record several toxicity studies of silica in sorptive
clays. It stated that the evidence does not provide the basis for a
finding of a significant risk of material impairment of health from
exposure to silica in sorptive clays (Document ID 4230, p. 2).
Consequently, SMI concluded that the application of a reduced PEL and
comprehensive standard is not warranted.
Having considered the evidence SMI submitted to the record, OSHA
finds that although quartz originating from bentonite deposits exhibits
some biological activity, it is clear that it is considerably less
toxic than unoccluded quartz. Moreover, evidence does not exist that
would permit the Agency to evaluate the magnitude of the lifetime risk
resulting from exposure to quartz in bentonite-containing materials and
similar sorptive clays. This finding does not extend to the brick
industry, where workers are exposed to silica through occluded quartz
in aluminum rich clays. The Love et al. study (1999, Document ID 0369),
which BIA claimed would be of useful quality for OSHA's risk
assessment, shows sufficient cases of silicosis to demonstrate
significant risk within the meaning used by OSHA for regulatory
purposes. In addition, OSHA found a reduced, although still
significant, risk of silicosis morbidity in the study of pottery
workers (Chen et al., 2005, Document ID 0985) that BIA put forth as
being representative of mortality in the brick industry (Document ID
3577, Tr. 674). These findings are discussed in detail below.
1. The Clay Brick Industry
BIA did not support a reduction in the PEL because although brick
industry employees are exposed to crystalline silica-bearing materials,
BIA believes silicosis is virtually non-existent in that industry. It
contended that silica exposure in the brick industry does not cause
similar rates of disease as in other industries because brick industry
workers are exposed to quartz occluded in aluminum-rich layers,
reducing the silica's toxicity. BIA concluded that "no significant
workplace risk for brick workers from crystalline silica exposure
exists at the current exposure limit" (Document ID 3577, Tr. 654) and
that reducing the PEL would have no benefit to workers in the brick
industry (Document ID 2300, p. 2). These concerns were also echoed by
individual companies in the brick industry, such as Acme Brick
(Document ID 2085, Attachment 1), Belden Brick Company (Document ID
2378), and Riverside Brick & Supply Company, Inc. (Document ID 2346,
Attachment 1). In addition, OSHA received over 50 letters as part of a
letter campaign from brick industry representatives referring to BIA's
comments on the lack of silicosis in the brick industry (e.g., Document
ID 2004).
The Tile Council of North America, Inc., also noted that "[c]lay
raw materials used in tile manufacturing are similar to those used in
brick and sanitary ware manufacturing" and also suggested that
aluminosilicates decrease toxicity (Document ID 3528, p. 1). OSHA
agrees with the Tile Council of North America, Inc., that their
concerns mirror those of the BIA and, therefore, the Agency's
consideration and response to BIA also applies to the tile industry.
a. Evidence on the Toxicity of Silica in Clay Brick.
On behalf of BIA, Mr. Robert Glenn presented a series of published
and unpublished studies (Document ID 3418), also summarized by BIA
(Document ID 2300, Attachment 1) as evidence that "no significant
workplace risk for brick workers from crystalline silica exposure
exists at the current exposure limit" (Document ID 3577, Tr. 654).
Most of these studies, including an unpublished report on West Virginia
brick workers (West Virginia State Health Department, 1939), a study of
North Carolina brick workers (Trice, 1941), a study of brick workers in
England (Keatinge and Potter, 1949), a study of Canadian brick workers
(Ontario Health Department, 1972), two studies of North Carolina brick
workers (NIOSH, 1978 and NIOSH, 1980), a study of English and Scottish
brick workers (Love et al., 1999, Document ID 0369), and an unpublished
study commissioned by BIA of workers at 13 of its member companies
(BIA, 2006), reported little or no silicosis among the workers examined
(Document ID 3418; 3577, Tr. 655-669).
Based on its review of the record evidence, OSHA finds that there
are many silica-containing materials (e.g., other clays, sand, etc.) in
brick and concludes that BIA's position is not supported by the best
available evidence. The analysis contained in the studies Mr. Glenn
presents does not meet the rigorous standards used in the studies on
which OSHA's risk assessment relies. Indeed the studies cited by Mr.
Glenn and BIA do not adequately support their contention that silicosis
is "essentially non-existent." Several studies were poorly designed
and applied inappropriate procedures for evaluating chest X-rays
(Document ID 3577, Tr. 682-685). Dr. David Weissman of NIOSH
underscored the significance of such issues, stating: "It's very
important, for example, to use multiple [B] readers [to evaluate chest
X-rays] and medians of readings, and it is very important for people to
be blinded to how readings are done" (Document ID 3577, Tr. 682). Also
problematic was Mr. Glenn's failure to provide key information on the
length of exposure or time since the first exposure in any of the
studies he presented, which examined only currently employed workers.
Information on duration of exposure or time since first exposure is
essential to evaluating risk of silicosis because silicosis typically
develops slowly and becomes detectable between 10 years and several
decades following a worker's first exposure. In the hearing, Dr. Ken
Rosenman also noted inadequacies related to silicosis latency,
testifying that "we know that silicosis occurs 20, 30 years after . .
. first exposure...if people have high exposure but short duration,
short latency, you are not going to see positive x-rays [even if
silicosis is developing] and so it's not going to be useful" (Document
ID 3577, Tr. 688-689).
Mr. Glenn acknowledged shortcomings in the studies he submitted for
OSHA's consideration, agreeing with Dr. Weissman's points about quality
assurance for X-ray interpretation and study design (e.g., Document ID
3577, Tr. 683). In response to Dr. Rosenman's concerns about silicosis
latency, he reported that no information on worker tenure or time since
first exposure was presented in Trice (1941), Keatings and Potter
(1949), Rajhans and Buldovsky (1972), the NIOSH studies (1978, 1980),
or Love et al. (1999), and that more than half of the West Virginia
brick workers studied by NIOSH (1939) had a tenure of less than 10
years (Document ID 4021, pp. 5-6), a time period that OSHA believes is
too short to see development of most forms of silicosis. He suggested
that high exposures in two areas of the West Virginia facilities could
trigger accelerated or acute silicosis, which could be observed in less
than 10 years, if the toxicity of the silica in clay brick was
comparable to silica found in other industries (post-hearing comments,
p. 5). However, OSHA notes that a cross-sectional report on actively
employed workers would not necessarily capture cases of accelerated or
acute silicosis, which are associated with severe symptoms that compromise
individuals' ability to continue work, and therefore would result in a
survivor effect where only unaffected workers remain at the time of study.
Mr. Glenn further argued that the Agency should assess risk to
brick workers based on studies from that industry because the incidence
of silicosis among brick workers appears to be lower than among workers
in other industries (Document ID 3577, Tr. 670). For the reasons
discussed above, OSHA does not believe the studies submitted by Mr.
Glenn provide an adequate basis for risk assessment. In addition,
studies presented did not: (1) Include retired workers; (2) report the
duration of workers' exposure to silica; (3) employ, in most cases,
quality-assurance practices for interpreting workers' medical exams; or
(4) include estimates of workers' silica exposures. Furthermore, Mr.
Glenn acknowledged in the informal public hearing that the Love et al.
(1999, Document ID 0369) study of 1,925 workers employed at brick
plants in England and Scotland in 1990-1991 is the only available study
of brick workers that presented exposure-response information (Document
ID 3577, Tr. 692). He characterized the results of that study as
contradictory to OSHA's risk assessment for silicosis morbidity because
the authors concluded that frequency of pneumoconiosis is low in
comparison to other quartz-exposed workers (Document ID 4021, p. 2). He
also cited an analysis by Miller and Soutar (Document ID 1098) (Dr.
Soutar is a co-author of the Love et al. study) that compared silicosis
risk estimates derived from Love et al. and those from Buchanan et
al.'s study of Scottish coal workers exposed to silica, and concluded
that silicosis risk among the coal workers far exceeded that among
brick workers (Document ID 3577, Tr. 671). He furthermore concluded
that the Love et al. study is "the only sensible study to be used for
setting an exposure limit for quartz in brick manufacturing."
(Document ID 3577, Tr. 679).
Based on review of the Love et al. study (Document ID 0369), OSHA
agrees with Mr. Glenn's claim that the silicosis risk among workers in
clay brick industries appears to be somewhat lower than might be
expected in other industries. However, OSHA is unconvinced by Mr.
Glenn's argument that risk to workers exposed at the previous PEL is
not significant because the cases of silicosis reported in this study
are sufficient to show significant risk within the meaning used by OSHA
for regulatory purposes (1 in 1,000 workers exposed for a working
lifetime).
Love et al. reported that 3.7 percent of workers with radiographs
were classified as ILO Category 0/1 (any signs of small opacities) and
1.4 percent of workers were classified as ILO Category 1/0 (small
radiographic opacities) or greater. Furthermore, among workers aged 55
and older, the age category most likely to have had sufficient time
since first exposure to develop detectable lung abnormalities from
silicosis exposure, Love et al. reported prevalences of abnormal
radiographs ranging from 2.9 percent (cumulative exposure below 0.5 mg/
yr-m\3\) to 16.4 percent (exposure at least 4 mg/yr-m\3\) (Love et al.
1999, Document ID 0369, Table 4, p. 129). According to the study
authors, these abnormalities "are the most likely dust related
pathology--namely, silicosis" (Document ID 0369, p. 132). Given that
OSHA considers a lifetime risk of 0.1 percent (1 in 1,000) to clearly
represent a significant risk, OSHA considers the Love et al. study to
have demonstrated a significant risk to brick workers even if only a
tiny fraction of the abnormalities observed in the study population
represent developing silicosis (see Benzene, 448 U.S. 607, 655 n. 2).
According to the study authors, "the estimated exposure-response
relation for quartz suggests considerable risks of radiological
abnormality even at concentrations of 0.1 mg/m\3\ [100 [mu]g/m\3\] of
quartz" (Document ID 0369, p. 132).
OSHA concludes that, despite the possibly lower toxicity of silica
in the clay brick industry compared to other forms, and despite the
Love et al. study's likely underestimation of risk due to exclusion of
retired workers, the study demonstrates significant risk among brick
workers exposed at the previous general industry PEL. It also suggests
that the silicosis risk among brick workers would remain significant
even at the new PEL. Furthermore, OSHA is unconvinced by Mr. Glenn's
argument that the Agency should develop a quantitative risk assessment
based on the Love et al. study, because that study excluded retired
workers and had inadequate worker follow-up. As explained earlier in
this section, adequate follow-up time and inclusion of retired workers
is extremely important to allow for latency in the development of
silicosis. Therefore, OSHA relied on studies including retired workers
in its QRA for silicosis morbidity.
Mr. Glenn additionally argued that the risk of lung cancer from
silica exposure among brick workers is likely to be lower than among
workers exposed to silica in other work settings. Mr. Glenn
acknowledged that "there are no published mortality studies of brick
workers that look at cause of death or lung cancer death" (Document ID
3577, Tr. 674). However, he stated that "pottery clays are similar to
the structural clays used in brickmaking in that the quartz is occluded
in aluminum-rich layers of bentonite, kaolinite, and illite," and that
OSHA should consider studies of mortality among pottery workers as
representative of the brick industry (Tr. 674). Mr. Glenn cited the
Chen et al. (2005) study of Chinese pottery workers, which reported a
weak exposure-response relationship between silica exposure and lung
cancer mortality, and which appeared to be affected by PAH-related
confounding. He concluded that the Chen et al. study "provides strong
evidence for aluminum-rich clays suppressing any potential
carcinogenesis from quartz" (Document ID 3577, Tr. 675).
OSHA acknowledges that occlusion may weaken the carcinogenicity of
silica in the brick clay industry, but does not believe that the Chen
et al. study provides conclusive evidence of such an effect. This is
because of the relatively low carcinogenic potential of silica and the
difficulty involved in interpreting one cohort with known issues of
confounding (see Section V.F, Comments and Responses Concerning Lung
Cancer Mortality). OSHA also notes, however, that it estimated risks of
silicosis morbidity from the cited Chen et al. (2005, Document ID 0985)
study, and found the risk among pottery workers to be significant, with
60 deaths per 1,000 workers at the previous PEL of 100 [mu]g/
m3 and 20 deaths per 1,000 workers at the revised PEL of 50
[mu]g/m3 (as indicated in Section VI, Final Quantitative
Risk Assessment and Significance of Risk, Table VI-1). Thus, given Mr.
Glenn's assertion that pottery clays are similar to the clays used in
brickmaking, OSHA believes that while the risk of silicosis morbidity
may be lower than that seen in other industry sectors, it is likely to
still be significant in the brickmaking industry.
Thus, OSHA concludes that the BIA's position is not supported by
the best available evidence. The studies cited by Mr. Glenn to support
his contention that brick workers are not at significant risk of
silica-related disease do not have the same standards as those studies
used by OSHA in its quantitative risk assessment. Furthermore, in the
highest-quality study brought forward by Mr. Glenn (Love et al. 1999,
Document ID 0369), there are sufficient cases of silicosis to
demonstrate significant risk within the meaning used by OSHA for
regulatory purposes. Even if the commenters' arguments that silica in
clay brick is less toxic were, to some extent, legitimate, this would
not significantly affect OSHA's own estimates from the epidemiological
evidence of the risks of silicosis.
2. Sorptive Minerals (Bentonite Clay) Processing
SMI asserted that the physico-chemical form of respirable
crystalline silica in sorptive clays reduces the toxicologic potency of
crystalline silica relative to the forms of silica common to most
studies relied on in OSHA's Preliminary QRA. In other words, the risk
associated with exposure to silica in sorptive clays is assertedly
lower than the risk associated with exposure to silica in other
materials. SMI based this view on what it deemed the "best available
scientific literature," epidemiological, in vitro, and animal evidence
OSHA had not previously considered. It believed the evidence showed
reduced risk from exposure to occluded quartz found in the sorptive
clays and that occluded quartz does not create a risk similar to that
posed by freshly fractured quartz (Document ID 2377, p. 7). Based on
this, SMI contended that the results of OSHA's Preliminary QRA were not
applicable to the sorptive minerals industry, and a more stringent
standard for crystalline silica is "neither warranted nor legally
permissible" (Document ID 4230, p. 1). As discussed below, OSHA
reviewed the evidence submitted by SMI and finds that although the
studies provide evidence of some biological activity in quartz
originating from bentonite deposits, there is not quantitative evidence
that would permit the Agency to evaluate the magnitude of the lifetime
risk resulting from exposure to quartz in bentonite-containing
materials and similar sorptive clays.
a. Evidence on the Toxicity of Silica in Sorptive Minerals
SMI submitted a number of studies to the rulemaking record. First,
it summarized a retrospective study by Waxweiler et al. (Document ID
3998, Attachment 18e) of attapulgite clay workers in Georgia in which
the authors concluded that there was a significant deficit of non-
malignant respiratory disease mortality and no clear excess of lung
cancer mortality among these workers. It used the study as the basis
for its recommendation to OSHA that the study "be cited and that
exposures in the industry be recognized in the final rule as not posing
the same hazard as those in industries with reactive crystalline
silica" (Document ID 2377, p. 10).
Based on its review of the rulemaking record, OSHA concludes that
the Waxweiler et al. study is of limited value for assessing the hazard
potential of quartz in bentonite clay because of the low airborne
levels of silica to which the workers were exposed. The Agency's
conclusion is supported by NIOSH's summary of the time-weighted average
(TWA) exposures calculated for each job category in Waxweiler et al.
(1988, Document ID 3998, Attachment 18e), which were found to be
"within the acceptable limits as recommended by NIOSH (i.e., < 0.05 mg/
m3 [50 [mu]g/m3])...and most were
substantially lower" (Document ID 4233, p. 41). It cannot be known to
what extent the low toxicity of the dust or the low exposures
experienced by the workers each contributed to the lack of observed
disease.
SMI also presented a World Health Organization (WHO) document
(2005, Document ID 3929), which recognized that "studies of workers
exposed to sorptive clays have not identified significant silicosis
risk" (Document ID 2377, p. 10). However, although WHO did find that
there were no reported cases of fibrotic reaction in humans exposed to
montmorillonite minerals in the absence of crystalline silica (Document
ID 3929, p. 130), the WHO report does discuss the long-term effects
from exposure to crystalline silica, including silicosis and lung
cancer. In fact, with respect to evaluating the hazards associated with
exposure to bentonite clay, WHO regarded silica as a potential
confounder (Document ID 3929, p. 136). Thus, WHO did not specifically
make any findings with respect to the hazard potential of quartz in the
bentonite clay mineral matrix but instead recognized the hazard
presented by exposure to crystalline silica generally.
Additionally, the WHO (Document ID 3929, pp. 114, 118) cited two
case/case series reports of bentonite-exposed workers, one
demonstrating increasing prevalence of silicosis with increasing
exposure to bentonite dust (Rombola and Guardascione, 1955, Document ID
3998, Attachment 18) and another describing cases of silicosis among
workers exposed to bentonite dust (Phibbs et al. 1971, Document ID
3998, Attachment 18b). Rombola and Guardascione (1955) found silicosis
prevalences of 35.5 and 12.8 percent in two bentonite processing
factories, and 6 percent in a bentonite mine. In the factory where the
highest exposures occurred, 10 of the 26 cases found were severe and
all cases developed with seven or fewer years of exposure, indicating
that exposure levels were extremely high (Document ID 4233, p. 42,
citing 3998, Attachment 18). Phibbs et al. (1971) reviewed chest x-rays
of 32 workers in two bentonite plants, of which x-ray films for 14
indicated silicosis ranging from minimal to advanced. Although the
exposure of affected workers to respirable dust or quartz is not known,
industrial hygiene surveys conducted in four bentonite plants showed
some areas having particle counts in excess of 3 to 11 times the ACGIH
particle count limit (Document ID 3998, Attachment 18b, p. 4). This is
roughly equivalent to exposure levels between 8 and 28 times OSHA's
former general industry PEL of 100 [mu]g/m3 (given that the
particle count limit is about 2.5 or more times higher than the
gravimetric limit for respirable quartz (see Section V.C, Summary of
the Review of Health Effects Literature and Preliminary QRA). Exposures
of this magnitude are considerably higher than those experienced by
worker cohorts of the studies relied on by OSHA in its Final Risk
Assessment and discussed in Section V.C, Summary of the Review of
Health Effects Literature and Preliminary QRA. For example, the median
of average exposures reported in the ten cohort studies used by
Steenland et al. (2001, Document ID 0684, p. 775) ranged from about
one-half to six times the former general industry PEL.
The lack of specific exposure information on bentonite workers
found with silicosis, combined with the extraordinary exposures
experienced by workers in the bentonite plants studied by Phibbs et al.
(1971), make this study, while concerning, unsuitable for evaluating
risks in the range of the former and final rule PELs. OSHA notes that
the WHO report also concluded that available data were inadequate to
conclusively establish a dose-response relationship or even a cause-
and-effect relationship for bentonite dust, and that its role in
inducing pneumoconiosis remains uncertain.
SMI also presented evidence from animal and in vitro studies that
it believes shows that respirable crystalline quartz present in
sorptive clays exists in a distinct occluded form, which significantly
mitigates adverse health effects due to the physico-chemical
characteristics of the occluded quartz. As discussed below, based on
careful review of the studies SMI cited, OSHA believes these studies
indicate that silica in bentonite clay is of lower toxicologic potency
than that found in other industry sectors.
SMI submitted two studies: an animal study (Creutzenberg et al.
2008, Document ID 3891) and a study of the characteristics of quartz samples
isolated from bentonite (Miles et al. 2008, Document ID 4173). SMI
contended that these studies demonstrate the low toxicity potential of
geologically ancient occluded quartz found in sorptive clays (Document
ID 2377, pp. 8-9).
Creutzenberg et al. (2008) summarized the findings from a rat study
aimed at "characterizing the differences in biological activity
between crystalline ground reference quartz (DQ12) and a quartz with
occluded surfaces (quartz isolate) obtained from a clay deposit formed
110-112 million years ago" (Document ID 3891, p. 995). Based on
histopathological assessment of the lungs in each treatment group,
Creutzenberg et al. (2008, Document ID 3891) found that the DQ12
reference quartz group exhibited a significantly stronger inflammatory
reaction than the quartz isolate, which showed a slight but still
statistically significant inflammatory response compared to the control
group. The increased inflammatory response was observed at day 3 but
not at 28 or 90 days. Thus, reaction elicited by the quartz isolate,
thought to have similar properties to bentonite, was considered by the
investigators to represent a moderate effect that did not progress. In
light of this, the implications of this study for development of
silicosis are unclear.
SMI also cited Miles et al. (2008, Document ID 4173), who studied
the mineralogical and chemical characteristics of quartz samples
isolated from bentonite, including the quartz isolate used by
Creutzenberg et al. (2008) in their animal study. Their evaluation
identified several differences in the chemical and physical properties
of the quartz isolates and unoccluded quartz that could help explain
the observed differences in toxicity (Document ID 4173); these included
differences in crystal structure, electrical potential of particle
surfaces, and, possibly, differences in the reactivity of surface-free
radicals owing to the presence of iron ions in the residual clay
material associated with the quartz isolates.
With respect to the two studies just discussed, animal evidence
cited by SMI demonstrates that quartz in bentonite induces a modest
inflammatory reaction in the lung that does not persist (Creutzenberg
et al., 2008, Document ID 3891). Such a reaction is notably different
from the persistent and stronger response seen with standard
experimental quartz material without surface occlusion (Creutzenberg et
al., 2008, Document ID 3891). Physical and chemical characteristics of
quartz from bentonite deposits have been shown to differ from standard
experimental quartz in ways that can explain its reduced toxicity
(Miles et al., 2008, Document ID 4173). However, the animal studies
cited by SMI are not suitable for risk assessment since they were
short-term (90 days), single-dose experiments.
In sum, human evidence on the toxicity of quartz in bentonite clay
includes one study cited by SMI that did not find an excess risk of
respiratory disease (Waxweiller et al., Document ID 3998, Attachment
18e). However, because exposures experienced by the workers were low
with most less than that of the final rule PEL, the lack of an observed
effect cannot be solely attributed to the nature of the quartz
particles. Two studies of bentonite workers found a high prevalence of
silicosis based on x-ray findings (Rombola and Guardascione, 1955,
Document ID 3998, Attachment 18; Phibbs et al., 1971, Document ID 3998,
Attachment 18b). Limited exposure data provided in the studies as well
as the relatively short latencies seen among cases of severe silicosis
make it clear that the bentonite workers were exposed to extremely high
dust levels. Neither of these studies can be relied on to evaluate
disease risk in the exposure range of the former and revised respirable
crystalline silica PELs.
OSHA finds that the evidence for quartz originating from bentonite
deposits indicates some biological activity, but also indicates lower
toxicity than standard experimental quartz (which has similar
characteristics to quartz encountered in most workplaces where
exposures occur). For regulatory purposes, however, OSHA finds that the
evidence does not exist that would permit the Agency to evaluate the
magnitude of the lifetime risk resulting from exposure to quartz in
sorptive clays at the 100 [mu]g/m\3\ PEL. Instead, OSHA finds that the
record provides no sound basis for determining the significance of risk
for exposure to sorptive clays containing respirable quartz. Thus, OSHA
is excluding sorptive clays (as described specifically in the Scope
part of Section XV, Summary and Explanation) from the scope of the
rule, until such time that sufficient science has been developed to
permit evaluation of the significance of the risk. However, in
excluding sorptive clays from the rule, the general industry PEL, as
described in 29 CFR 1910.1000 Table Z-3, will continue to apply.
VI. Final Quantitative Risk Assessment and Significance of Risk
A. Introduction
To promulgate a standard that regulates workplace exposure to toxic
materials or harmful physical agents, OSHA must first determine that
the standard reduces a "significant risk" of "material impairment."
Section 6(b)(5) of the OSH Act, 29 U.S.C. 655(b). The first part of
this requirement, "significant risk," refers to the likelihood of
harm, whereas the second part, "material impairment," refers to the
severity of the consequences of exposure. Section II, Pertinent Legal
Authority, of this preamble addresses the statutory bases for these
requirements and how they have been construed by the Supreme Court and
federal courts of appeals.
It is the Agency's practice to estimate risk to workers by using
quantitative risk assessment and determining the significance of that
risk based on the best available evidence. Using that evidence, OSHA
identifies material health impairments associated with potentially
hazardous occupational exposures, and, when possible, provides a
quantitative assessment of exposed workers' risk of these impairments.
The Agency then evaluates whether these risks are severe enough to
warrant regulatory action and determines whether a new or revised rule
will substantially reduce these risks. For single-substance standards
governed by section 6(b)(5) of the OSH Act, 29 U.S.C. 655(b)(5), OSHA
sets a permissible exposure limit (PEL) based on that risk assessment
as well as feasibility considerations. These health and risk
determinations are made in the context of a rulemaking record in which
the body of evidence used to establish material impairment, assess
risks, and identify affected worker population, as well as the Agency's
preliminary risk assessment, are placed in a public rulemaking record
and subject to public comment. Final determinations regarding the
standard, including final determinations of material impairment and
risk, are thus based on consideration of the entire rulemaking record.
In this case, OSHA reviewed extensive toxicological,
epidemiological, and experimental research pertaining to the adverse
health effects of occupational exposure to respirable crystalline
silica, including silicosis, other non-malignant respiratory disease
(NMRD), lung cancer, and autoimmune and renal diseases. Using the
information collected during this review, the Agency
developed quantitative estimates of the excess risk of mortality and
morbidity attributable to the previously allowed and revised respirable
crystalline silica PELs; these estimates were published with the
proposed rule. The Agency subsequently reexamined these estimates in
light of the rulemaking record as a whole, including comments,
testimony, data, and other information, and has determined that long-
term exposure at and above the previous PELs would pose a significant
risk to workers' health, and that adoption of the new PEL and other
provisions of the final rule will substantially reduce this risk. Based
on these findings, the Agency is adopting a new PEL of 50 [mu]g/m\3\.
Even though OSHA's risk assessment indicates that a significant
risk also exists at the revised action level of 25 [mu]g/m\3\, the
Agency is not adopting a PEL below the revised 50 [mu]g/m\3\ limit
because OSHA must also consider the technological and economic
feasibility of the standard in determining exposure limits. As
explained in the Summary and Explanation for paragraph (c), Permissible
Exposure Limit (PEL), of the general industry/maritime standard
(paragraph (d) for construction), OSHA has determined that, with the
adoption of additional engineering and work practice controls, the
revised PEL of 50 [mu]g/m\3\ is technologically and economically
feasible in most operations in the affected general industrial and
maritime sectors and in the construction industry, but that a lower PEL
of 25 [mu]g/m\3\ is not technologically feasible for most of these
operations (see Section VII, Summary of the Final Economic Analysis and
Final Regulatory Flexibility Analysis (FEA) and Chapter IV,
Technological Feasibility, of the FEA). Therefore, OSHA concludes that
by establishing the 50 [mu]g/m\3\ PEL, the Agency has reduced
significant risk to the extent feasible.
B. OSHA's Findings of Material Impairments of Health
As discussed below and in OSHA's Review of Health Effects
Literature and Preliminary QRA (Document ID 1711, pp. 7-229), there is
convincing evidence that inhalation exposure to respirable crystalline
silica increases the risk of a variety of adverse health effects,
including silicosis, NMRD (such as chronic bronchitis and emphysema),
lung cancer, kidney disease, immunological effects, and infectious
tuberculosis (TB). OSHA considers each of these conditions to be a
material impairment of health. These diseases make it difficult or
impossible to work and result in significant and permanent functional
limitations, reduced quality of life, and sometimes death. When these
diseases coexist, as is common, the effects are particularly
debilitating (Rice and Stayner, 1995, Document ID 0418; Rosenman et
al., 1999, 0421). Based on these findings and on the scientific
evidence that respirable crystalline silica substantially increases the
risk of each of these conditions, OSHA has determined that exposure to
respirable crystalline silica increases the risk of "material
impairment of health or functional capacity" within the meaning of the
Occupational Safety and Health Act.
1. Silicosis
OSHA considers silicosis, an irreversible and potentially fatal
disease, to be a clear material impairment of health. The term
"silicosis" refers to a spectrum of lung diseases attributable to the
inhalation of respirable crystalline silica. As described more fully in
the Review of Health Effects Literature (Document ID 1711, pp. 16-71),
the three types of silicosis are acute, accelerated, and chronic. Acute
silicosis can occur within a few weeks to months after inhalation
exposure to extremely high levels of respirable crystalline silica.
Death from acute silicosis can occur within months to a few years of
disease onset, with the affected person drowning in his or her own lung
fluid (NIOSH, 1996, Document ID 0840). Accelerated silicosis results
from exposure to high levels of airborne respirable crystalline silica,
and disease usually occurs within 5 to 10 years of initial exposure
(NIOSH, 1996, Document ID 0840). Both acute and accelerated silicosis
are associated with exposures that are substantially above the previous
general industry PEL, although no precise information on the
relationships between exposure and occurrence of disease exists.
Chronic silicosis is the most common form of silicosis seen today,
and is a progressive and irreversible condition characterized as a
diffuse nodular pulmonary fibrosis (NIOSH, 1996, Document ID 0840).
Chronic silicosis generally occurs after 10 years or more of inhalation
exposure to respirable crystalline silica at levels below those
associated with acute and accelerated silicosis. Affected workers may
have a dry chronic cough, sputum production, shortness of breath, and
reduced pulmonary function. These symptoms result from airway
restriction caused by the development of fibrotic scarring in the lower
regions of the lungs. The scarring can be detected in chest x-ray films
when the lesions become large enough to appear as visible opacities.
The result is a restriction of lung volumes and decreased pulmonary
compliance with concomitant reduced gas transfer. Chronic silicosis is
characterized by small, rounded opacities that are symmetrically
distributed in the upper lung zones on chest radiograph (Balaan and
Banks, 1992, Document ID 0289, pp. 347, 350-351).
The diagnosis of silicosis is based on a history of exposure to
respirable crystalline silica, chest radiograph findings, and the
exclusion of other conditions that appear similar. Because workers
affected by early stages of chronic silicosis are often asymptomatic,
the finding of opacities in the lung is key to detecting silicosis and
characterizing its severity. The International Labour Organization
(ILO) International Classification of Radiographs of Pneumoconioses
(ILO, 1980, Document ID 1063; 2002, 1064) is the currently accepted
standard against which chest radiographs are evaluated for use in
epidemiological studies, medical surveillance, and clinical evaluation.
The ILO system standardizes the description of chest x-rays, and is
based on a 12-step scale of severity and extent of silicosis as
evidenced by the size, shape, and density of opacities seen on the x-
ray film. Profusion (frequency) of small opacities is classified on a
4-point major category scale (0-3), with each major category divided
into three, giving a 12-point scale between 0/- and 3/+. Large
opacities are defined as any opacity greater than 1 cm that is present
in a film (ILO, 1980, Document ID 1063; 2002, 1064, p. 6).
The small rounded opacities seen in early stage chronic silicosis
(ILO major category 1 profusion) may progress (through ILO major
categories 2 and/or 3) and develop into large fibrotic masses that
destroy the lung architecture, resulting in progressive massive
fibrosis (PMF). This stage of advanced silicosis is usually
characterized by impaired pulmonary function, permanent disability, and
premature death. In cases involving PMF, death is commonly attributable
to progressive respiratory insufficiency (Balaan and Banks, 1992,
Document ID 0289).
Patients with ILO category 2 or 3 background profusion of small
opacities are at increased risk, compared to those with category 1
profusion, of developing the large opacities characteristic of PMF. In
one study of silicosis patients in Hong Kong, Ng and Chan (1991,
Document ID 1106, p. 231) found the risk of PMF increased by 42 and 64
percent among patients whose chest x-ray films were classified as
ILO major category 2 or 3, respectively. Research has shown that
people with silicosis advanced beyond ILO major category 1 have
reduced life expectancy compared to the general population
(Infante-Rivard et al., 1991, Document ID 1065; Ng et al., 1992a,
0383; Westerholm, 1980, 0484).
Silicosis is the oldest known occupational lung disease and is
still today the cause of significant premature mortality. As discussed
further in Section V.E, Comments and Responses Concerning Surveillance
Data on Silicosis Morbidity and Mortality, in 2013, there were 111
deaths in the U.S. where silicosis was recorded as an underlying or
contributing cause of death on a death certificate (NCHS data). Between
1996 and 2005, deaths attributed to silicosis resulted in an average of
11.6 years of life lost by affected workers (NIOSH, 2007, Document ID
1362). In addition, exposure to respirable crystalline silica remains
an important cause of morbidity and hospitalizations. National
inpatient hospitalization data show that in the year 2011, 2,082
silicosis-related hospitalizations occurred, indicating that silicosis
continues to be a significant health issue in the U.S. (Document ID
3577, Tr. 854-855). Although there is no national silicosis disease
surveillance system in the U.S., a published analysis of state-based
surveillance data from the time period 1987-1996 estimated that between
3,600-7,000 new cases of silicosis occurred in the U.S. each year
(Rosenman et al., 2003, Document ID 1166).
It has been widely reported that available statistics on silicosis-
related mortality and morbidity are likely to be understated due to
misclassification of causes of death (for example, as tuberculosis,
chronic bronchitis, emphysema, or cor pulmonale), lack of occupational
information on death certificates, or misdiagnosis of disease by health
care providers (Goodwin et al., 2003, Document ID 1030; Windau et al.,
1991, 0487; Rosenman et al., 2003, 1166). Furthermore, reliance on
chest x-ray findings may miss cases of silicosis because fibrotic
changes in the lung may not be visible on chest radiograph; thus,
silicosis may be present absent x-ray signs or may be more severe than
indicated by x-ray (Hnizdo et al., 1993, Document ID 1050; Craighhead
and Vallyahan, 1980, 0995; Rosenman et al., 1997, 4181).
Although most workers with early-stage silicosis (ILO categories 0/
1 or 1/0) typically do not experience respiratory symptoms, the primary
risk to the affected worker is progression of disease with progressive
decline of lung function. Several studies of workers exposed to
crystalline silica have shown that, once silicosis is detected by x-
ray, a substantial proportion of affected workers can progress beyond
ILO category 1 silicosis, even after exposure has ceased (e.g., Hughes,
1982, Document ID 0362; Hessel et al., 1988, 1042; Miller et al., 1998,
0374; Ng et al., 1987a, 1108; Yang et al., 2006, 1134). In a population
of coal miners whose last chest x-ray while employed was classified as
major category 0, and who were examined again 10 years after the mine
had closed, 20 percent had developed opacities consistent with a
classification of at least 1/0, and 4 percent progressed further to at
least 2/1 (Miller et al., 1998, Document ID 0374). Although there were
periods of extremely high exposure to respirable quartz in the mine
(greater than 2,000 [mu]g/m\3\ in some jobs between 1972 and 1976, and
more than 10 percent of exposures between 1969 and 1977 were greater
than 1,000 [mu]g/m\3\), the mean cumulative exposure for the cohort
over the period 1964-1978 was 1.8 mg/m\3\-yrs, corresponding to an
average silica concentration of 120 [mu]g/m\3\. In a population of
granite quarry workers exposed to an average respirable silica
concentration of 480 [mu]g/m\3\ (mean length of employment was 23.4
years), 45 percent of those diagnosed with simple silicosis (i.e.,
presence of small opacities only on chest x-ray films) showed
radiological progression of disease after 2 to 10 years of follow up
(Ng et al., 1987a, Document ID 1108). Among a population of gold
miners, 92 percent progressed in 14 years; exposures of high-, medium-,
and low-exposure groups were 970, 450, and 240 [mu]g/m\3\, respectively
(Hessel et al., 1988, Document ID 1042). Chinese mine and factory
workers categorized under the Chinese system of x-ray classification as
"suspected" silicosis cases (analogous to ILO 0/1) had a progression
rate to stage I (analogous to ILO major category 1) of 48.7 percent,
and the average interval was about 5.1 years (Yang et al., 2006,
Document ID 1134).
The risk of silicosis carries with it an increased risk of reduced
lung function as the disease irreversibly progresses. There is strong
evidence in the literature for the finding that lung function
deteriorates more rapidly in workers exposed to silica, especially
those with silicosis, than what is expected from a normal aging process
(Cowie, 1988, Document ID 0993; Hughes et al., 1982, 0362; Malmberg et
al., 1993, 0370; Ng and Chan, 1992, 1107). The rates of decline in lung
function are greater in those whose disease showed evidence of
radiologic progression (Begin et al., 1987, Document ID 0295; Cowie,
1988, 0993; Ng and Chan, 1992, 1107; Ng et al., 1987a, 1108).
Additionally, the average deterioration of lung function exceeds that
in smokers (Hughes et al., 1982, Document ID 0362).
Several studies have reported no decrease in pulmonary function
with an ILO category 1 level of profusion of small opacities but found
declines in pulmonary function with categories 2 and 3 (Ng et al.,
1987a, Document ID 1108; Begin et al., 1988, 0296; Moore et al., 1988,
1099). However, one study found a statistically significantly greater
annual loss in forced vital capacity (FVC) and forced expiratory volume
in one second (FEV1) among those with category 1 profusion
compared to category 0 (Cowie, 1988, Document ID 0993). In another
study, the degree of profusion of opacities was associated with
reductions in several pulmonary function metrics (Cowie and Mabena,
1991, Document ID 0342). Some studies have reported no associations
between radiographic silicosis and decreases in pulmonary function (Ng
et al., 1987a, Document ID 1108; Wiles et al., 1972, 0485; Hnizdo,
1992, 1046), while other studies (Ng et al., 1987a, Document ID 1108;
Wang et al., 1997, 0478) have found that measurable changes in
pulmonary function are evident well before the changes seen on chest x-
ray. Findings of pulmonary function decrements absent radiologic signs
of silicosis may reflect the general insensitivity of chest radiography
in detecting lung fibrosis, or may also reflect that exposure to
respirable silica has been shown to increase the risk of non-malignant
respiratory disease (NMRD) and its attendant pulmonary function losses
(see Section V.C, Summary of the Review of Health Effects Literature
and Preliminary QRA).
Moreover, exposure to respirable crystalline silica in and of
itself, with or without silicosis, increases the risk that latent
tuberculosis infection can convert to active disease. Early
descriptions of dust diseases of the lung did not distinguish between
TB and silicosis, and most fatal cases described in the first half of
this century were a combination of silicosis and TB (Castranova et al.,
1996, Document ID 0314). More recent findings demonstrate that exposure
to silica, even without silicosis, increases the risk of infectious
(i.e., active) pulmonary TB (Sherson and Lander, 1990, Document ID
0434; Cowie, 1994, 0992; Hnizdo and Murray, 1998, 0360; teWaterNaude et
al., 2006, 0465). Both conditions together can hasten the development
of respiratory impairment and increase mortality risk even beyond that
experienced by persons with active TB who have not been exposed to
respirable crystalline silica (Banks, 2005, Document ID 0291).
Based on the information presented above and in its review of the
health literature, OSHA concludes that silicosis remains a significant
cause of early death and of serious illness, despite the existence of
an enforceable exposure limit over the past 40 years. Silicosis in its
later stages of progression (i.e., with chest x-ray findings of ILO
category 2 or 3 profusion of small opacities, or the presence of large
opacities) is characterized by the likely appearance of respiratory
symptoms and decreased pulmonary function, as well as increased risk of
progression to PMF, disability, and early mortality. Early-stage
silicosis, although without symptoms among many who are affected,
nevertheless reflects the formation of fibrotic lesions in the lung and
increases the risk of progression to later stages, even after exposure
to respirable crystalline silica ceases. In addition, the presence of
silicosis increases the risk of pulmonary infections, including
conversion of latent TB infection to active TB. Silicosis is not a
reversible condition, and there is no specific treatment for the
disease, other than administration of drugs to alleviate inflammation
and maintain open airways, or administration of oxygen therapy in
severe cases. Based on these considerations, OSHA finds that silicosis
of any form, and at any stage of progression, is a material impairment
of health and that fibrotic scarring of the lungs represents loss of
functional respiratory capacity.
2. Lung Cancer
OSHA considers lung cancer, an irreversible and frequently fatal
disease, to be a clear material impairment of health (see Homer et al.,
2009, Document ID 1343). According to the National Cancer Institute
(SEER Cancer Statistics Review, 2006, Document ID 1343), the five-year
survival rate for all forms of lung cancer is only 15.6 percent, a rate
that has not improved in nearly two decades. After reviewing the record
as a whole, OSHA finds that respirable crystalline silica exposure
substantially increases the risk of lung cancer. This finding is based
on the best available toxicological and epidemiological data, reflects
substantial supportive evidence from animal and mechanistic research,
and is consistent with the conclusions of other government and public
health organizations, including the International Agency for Research
on Cancer (1997, Document ID 1062; 2012, Document ID 1473), the HHS
National Toxicology Program (2000, Document ID 1417), the CDC's
National Institute for Occupational Safety and Health (2002, Document
ID 1110), the American Thoracic Society (1997, Document ID 0283), and
the American Conference of Governmental Industrial Hygienists (2010,
Document ID 0515).
The Agency's primary evidence comes from evaluation of more than 50
studies of occupational cohorts from many different industry sectors in
which exposure to respirable crystalline silica occurs, including:
Granite and stone quarrying; the refractory brick industry; gold, tin,
and tungsten mining; the diatomaceous earth industry; the industrial
sand industry; and construction. In addition, the association between
exposure to respirable crystalline silica and lung cancer risk was
reported in a national mortality surveillance study (Calvert et al.,
2003, Document ID 0309) and in two community-based studies (Pukkala et
al., 2005, Document ID 0412; Cassidy et al., 2007, 0313), as well as in
a pooled analysis of 10 occupational cohort studies (Steenland et al.,
2001a, Document ID 0452). Toxicity studies provide supportive evidence
of the carcinogenicity of crystalline silica, in that they demonstrate
biologically plausible mechanisms by which crystalline silica in the
deep lung can give rise to biochemical and cellular events leading to
tumor development (see Section V.H, Mechanisms of Silica-Induced
Adverse Health Effects).
3. Non-Malignant Respiratory Disease (NMRD) (Other Than Silicosis)
Although many of the stakeholders in this rule have focused their
attention on the evidence related to silicosis and lung cancer, the
available evidence shows that exposure to respirable crystalline silica
also increases the risk of developing NMRD, in particular chronic
bronchitis and emphysema. OSHA has determined that NMRD, which results
in loss of pulmonary function that restricts normal activity in
individuals afflicted with these conditions (see American Thoracic
Society, 2003, Document ID 1332), constitutes a material impairment of
health. Both chronic bronchitis and emphysema can occur in conjunction
with the development of silicosis. Several studies have documented
increased prevalence of chronic bronchitis and emphysema among silica-
exposed workers even absent evidence of silicosis (see Document ID
1711, pp. 182-192; NIOSH, 2002, 1110; American Thoracic Society, 2003,
1332). There is also evidence that smoking may have an additive or
synergistic effect on silica-related NMRD morbidity or mortality
(Hnizdo, 1990, Document ID 1045; Hnizdo et al., 1990, 1047; Wyndham et
al., 1986, 0490; NIOSH, 2002, 1110). In a study of diatomaceous earth
workers, Park et al. (2002, Document ID 0405) found a positive
exposure-response relationship between exposure to respirable
cristobalite (a form of silica) and increased mortality from NMRD.
Decrements in pulmonary function have often been found among
workers exposed to respirable crystalline silica absent radiologic
evidence of silicosis. Several cross-sectional studies have reported
such findings among granite workers (Theriault et al., 1974a, Document
ID 0466; Wallsh, 1997, 0477; Ng et al., 1992b, 0387; Montes II et al.,
2004b, 0377), gold miners (Irwig and Rocks, 1978, Document ID 1067;
Hnizdo et al., 1990, 1047; Cowie and Mabena, 1991, 0342), gemstone
cutters (Ng et al., 1987b, Document ID 1113), concrete workers (Meijer
et al., 2001, Document ID 1243), refractory brick workers (Wang et al.,
1997, Document ID 0478), hard rock miners (Manfreda et al., 1982,
Document ID 1094; Kreiss et al., 1989, 1079), pottery workers (Neukirk
et al., 1994, Document ID 0381), slate workers (Surh, 2003, Document ID
0462), and potato sorters exposed to silica in diatomaceous earth
(Jorna et al, 1994, Document ID 1071).
OSHA also evaluated several longitudinal studies where exposed
workers were examined over a period of time to track changes in
pulmonary function. Among both active and retired granite workers
exposed to an average of 60 [mu]g/m \3\, Graham et al. did not find
exposure-related decrements in pulmonary function (1981, Document ID
1280; 1984, 0354). However, Eisen et al. (1995, Document ID 1010) did
find significant pulmonary decrements among a subset of granite workers
(termed "dropouts") who left work and consequently did not
voluntarily participate in the last of a series of annual pulmonary
function tests. This group of workers experienced steeper declines in
FEV1 compared to the subset of workers who remained at work and
participated in all tests (termed "survivors"), and these declines
were significantly related to dust exposure. Thus, in this study,
workers who had left work had exposure-related declines in pulmonary
function to a greater extent than did workers who remained on the job,
clearly demonstrating a survivor effect among the active workers.
Exposure-related changes in lung function were also reported in a
12-year study of granite workers (Malmberg, 1993, Document ID 0370),
in two 5-year studies of South African miners (Hnizdo, 1992,
Document ID 1046; Cowie, 1988, 0993), and in a study of foundry workers
whose lung function was assessed between 1978 and 1992 (Hertzberg et
al., 2002, Document ID 0358).
Each of these studies reported their findings in terms of rates of
decline in any of several pulmonary function measures, such as FVC,
FEV1, and FEV1/FVC. To put these declines in
perspective, Eisen et al. (1995, Document ID 1010) reported that the
rate of decline in FEV1 seen among the dropout subgroup of
Vermont granite workers was 4 ml per mg/m\3\-yrs of exposure to
respirable granite dust; by comparison, FEV1 declines at a
rate of 10 ml/year from smoking one pack of cigarettes daily. From
their study of foundry workers, Hertzberg et al., reported finding a
1.1 ml/year decline in FEV1 and a 1.6 ml/year decline in FVC
for each mg/m\3\-yrs of respirable silica exposure after controlling
for ethnicity and smoking (2002, Document ID 0358, p. 725). From these
rates of decline, they estimated that exposure to the previous OSHA
general industry quartz standard of 100 [micro]g/m\3\ for 40 years
would result in a total loss of FEV1 and FVC that is less
than but still comparable to smoking a pack of cigarettes daily for 40
years. Hertzberg et al. also estimated that exposure to the current
standard for 40 years would increase the risk of developing abnormal
FEV1 or FVC by factors of 1.68 and 1.42, respectively (2002, Document
ID 0358, pp. 725-726). OSHA believes that this magnitude of reduced
pulmonary function, as well as the increased morbidity and mortality
from non-malignant respiratory disease (NMRD) that has been documented
in the studies summarized above, constitute material impairments of
health and loss of functional respiratory capacity.
4. Renal and Autoimmune Effects
Finally, OSHA's review of the literature reflects substantial
evidence that exposure to crystalline silica increases the risk of
renal and autoimmune diseases, both of which OSHA considers to be
material impairments of health (see Section V.C, Summary of the Review
of Health Effects Literature and Preliminary QRA). Epidemiological
studies have found statistically significant associations between
occupational exposure to silica dust and chronic renal disease (e.g.,
Calvert et al., 1997, Document ID 0976), subclinical renal changes
including proteinurea and elevated serum creatinine (e.g., Ng et al.,
1992c, Document ID 0386; Rosenman et al., 2000, 1120; Hotz, et al.,
1995, 0361), end-stage renal disease morbidity (e.g., Steenland et al.,
1990, Document ID 1125), chronic renal disease mortality (Steenland et
al., 2001b, Document ID 0456; 2002a, 0448), and granulomatosis with
polyangitis (Nuyts et al., 1995, Document ID 0397). Granulomatosis with
polyangitis is characterized by inflammation of blood vessels, leading
to damaging granulomatous formation in the lung and damage to the
glomeruli of the kidneys, a network of capillaries responsible for the
first stage of blood filtration. If untreated, this condition often
leads to renal failure (Nuyts et al., 1995, Document ID 0397, p. 1162).
Possible mechanisms for silica-induced renal disease include a direct
toxic effect on the kidney and an autoimmune mechanism (see Section
V.H, Mechanisms of Silica-Induced Adverse Health Effects; Calvert et
al., 1997, Document ID 0976; Gregorini et al., 1993, 1032). Steenland
et al. (2002a, Document ID 0448) demonstrated a positive exposure-
response relationship between exposure to respirable crystalline silica
and end-stage renal disease mortality.
In addition, there are a number of studies that show exposure to be
related to increased risks of autoimmune disease, including scleroderma
(e.g., Sluis-Cremer et al., 1985, Document ID 0439), rheumatoid
arthritis (e.g., Klockars et al., 1987, Document ID 1075; Rosenman and
Zhu, 1995, 0424), and systemic lupus erythematosus (e.g., Brown et al.,
1997, Document ID 0974). Scleroderma is a degenerative disorder that
leads to over-production of collagen in connective tissue that can
cause a wide variety of symptoms including skin discoloration and
ulceration, joint pain, swelling and discomfort in the extremities,
breathing problems, and digestive problems. Rheumatoid arthritis is
characterized by joint pain and tenderness, fatigue, fever, and weight
loss. Systemic lupus erythematosus is a chronic disease of connective
tissue that can present a wide range of symptoms including skin rash,
fever, malaise, joint pain, and, in many cases, anemia and iron
deficiency. OSHA considers chronic renal disease, end-stage renal
disease mortality, granulomatosis with polyangitis, scleroderma,
rheumatoid arthritis, and systemic lupus erythematosus clearly to be
material impairments of health.
C. OSHA's Final Quantitative Risk Estimates
To evaluate the significance of the health risks that result from
exposure to hazardous chemical agents, OSHA relies on epidemiological
and experimental data, as well as statistical methods. The Agency uses
these data and methods to characterize the risk of disease resulting
from workers' exposure to a given hazard over a working lifetime at
levels of exposure reflecting both compliance with previous standards
and compliance with the new standard. In the case of respirable
crystalline silica, the previous general industry, construction, and
shipyard PELs were formulas that limit 8-hour TWA exposures to
respirable dust; the limit on exposure decreased with increasing
crystalline silica content of the dust. OSHA's previous general
industry PEL for respirable quartz was expressed both in terms of a
particle count and a gravimetric concentration, while the previous
construction and shipyard employment PELs for respirable quartz were
only expressed in terms of a particle count formula. For general
industry, the gravimetric formula PEL for quartz approaches 100
[micro]g/m\3\ of respirable crystalline silica when the quartz content
of the dust is about 10 percent or greater. The previous PEL's particle
count formula for the construction and shipyard industries is equal to
a range of about 250 [mu]g/m\3\ to 500 [mu]g/m\3\ expressed as
respirable quartz. In general industry, the previous PELs for
cristobalite and tridymite, which are forms (polymorphs) of silica,
were one-half the PEL for quartz.
In this final rule, OSHA has established a uniform PEL for
respirable crystalline silica by revising the PELs applicable to
general industry, construction, and maritime to 50 [mu]g/m\3\ TWA of
respirable crystalline silica. OSHA has also established an action
level of 25 [micro]g/m\3\ TWA. In this section of the preamble, OSHA
presents its final estimates of health risks associated with a working
lifetime (45 years) of exposure to 25, 50, and 100 [micro]g/m\3\
respirable crystalline silica. These levels represent the risks
associated with exposure over a working lifetime to the new action
level, new PEL, and previous general industry PEL, respectively. OSHA
also presents estimates associated with exposure to 250 and 500
[micro]g/m\3\ to represent a range of risks likely to be associated
with exposure to the former construction and shipyard PELs. Risk
estimates are presented for mortality due to lung cancer, silicosis and
other non-malignant respiratory disease (NMRD), and end-stage renal
disease, as well as silicosis morbidity. These estimates are the
product of OSHA's risk assessment, following the Agency's
consideration of new data introduced into the rulemaking record and
of the numerous comments in the record that raised questions about
OSHA's preliminary findings and analysis.
After reviewing the evidence and testimony in the record, OSHA has
determined that it is appropriate to base its final risk estimates on
the same studies and models as were used in the NPRM (see Section V.C,
Summary of the Review of Health Effects Literature and Preliminary
QRA). For mortality risk estimates, OSHA used the models developed by
various investigators and employed a life table analysis to implement
the models using the same background all-cause mortality data and
consistent assumption for length of lifetime (85 years). The life table
is a technique that allows estimation of excess risk of disease
mortality factoring in the probability of surviving to a particular age
assuming no exposure to the agent in question and given the background
probability of dying from any cause at or before that age (see Section
V.M, Comments and Responses Concerning Working Life, Life Tables, and
Dose Metric). Since the time of OSHA's preliminary analysis, the
National Center for Health Statistics (NCHS) released updated all-cause
mortality background rates from 2011; these rates are available in an
internet web-based query by year and 2010 International Classification
of Diseases (ICD) code through the Centers of Disease Control and
Prevention (CDC) Wonder database (http://wonder.cdc.gov/udc-icd10.html).
Using these updated statistics, OSHA revised its life table analyses
to estimate lifetime risks of mortality that result from 45 years
of exposure to respirable crystalline silica. OSHA's final quantitative
mortality risk estimates are presented in Table VI-1 below.
For silicosis morbidity risk estimates, OSHA relied on the
cumulative risk models developed by investigators of five studies who
conducted studies relating cumulative disease risk to cumulative
exposure to respirable crystalline silica (see footnotes to Table VI-
1). Of these, only one, the study by Steenland and Brown (1995) of U.S.
gold miners, employed a life-table analysis. Table VI-1 also presents
OSHA's final quantitative estimates of silicosis morbidity risks.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
OSHA notes that the updated risk estimates are not substantially
different from those presented in the Preliminary QRA; for example, for
exposure at the previous general industry PEL approaching 100 [mu]g/
m\3\, the excess lung cancer mortality risk ranged from 13 to 60 deaths
per 1,000 workers using the original 2006 background data, and from 11
to 54 deaths per 1,000 workers using the updated 2011 background data.
For exposure at the revised PEL of 50 [mu]g/m\3\, the risk estimates
ranged from 6 to 26 deaths per 1,000 workers using the 2006 background
data, and 5 to 23 deaths per 1,000 workers using the 2011 background
data. Similarly, the updated risk estimates for NMRD are not
substantially different; for example, for exposure for 45 working years
at the previous general industry PEL approaching 100 [mu]g/m\3\, the
excess NMRD mortality risk, using the Park et al. (2002, Document 0405)
model was 83 deaths per 1,000 workers using the original 2006
background data, and 85 deaths per 1,000 workers using the updated 2011
background data. For exposure at the revised PEL of 50 [mu]g/m\3\, the
risk estimate was 43 deaths per 1,000 workers using the 2006 background
data, and 44 deaths per 1,000 workers using the 2011 background data.
OSHA also presents in the table the excess lung cancer mortality
risk associated with 45 years of exposure to the previous construction/
shipyard PEL (in the range of 250 to 500 [micro]g/m\3\). It should be
noted, however, that exposure to 250 or 500 [micro]g/m\3\ over 45 years
represents cumulative exposures of 11.25 and 22.5 mg/m\3\-yrs,
respectively, which are well above the median cumulative exposure for
most of the cohorts used in the risk assessment. Estimating excess
risks over this higher range of cumulative exposures required some
degree of extrapolation, which adds uncertainty. In addition, at
cumulative exposures as high as permitted by the previous construction
and maritime PELs, silica-related causes of mortality will compete with
each other and it is difficult to determine the risk of any single
cause of mortality in the face of such competing risks.
OSHA's final risk estimates for renal disease reflect the 1998
background all-cause mortality and renal mortality rates for U.S.
males, rather than the 2011 rates used for lung cancer and NMRD, as
updated in the previous sections. Background rates were not adjusted
for the renal disease risk estimates because the CDC significantly
changed the classification of renal diseases after 1998; they are now
inconsistent with those used by Steenland et al. (2002a, Document ID
0448), the study relied on by OSHA, to ascertain the cause of death of
workers in their study. OSHA notes that the change in classification
system, from ICD-9 to ICD-10, did not materially affect background
rates for diseases grouped as lung cancer or NMRD. The findings from
OSHA's final risk assessment are summarized below.
OSHA notes that the key studies in its final risk assessment were
composed of cohorts with cumulative exposures relevant to those permitted
by the preceding General Industry PEL (45 years of exposure at 100 [mu]g/m\3\
equals 4.5 mg/m\3\-yrs). Table VI-2 provides the reported cumulative
exposure information for each of the cohorts of the key studies. Most
of these cohorts had mean or median cumulative exposures below 4.5 mg/
m\3\-yrs. Based on this data, OSHA concludes that the cumulative
exposures experienced by the cohorts are relevant and reasonable for
use in the Agency's final risk assessment.
1. Summary of Excess Risk Estimates for Lung Cancer Mortality
For estimates of lung cancer risk from crystalline silica exposure,
OSHA has relied upon studies of exposure-response relationships
presented in a pooled analysis of 10 cohort studies (Steenland et al.,
2001a, Document ID 0452; ToxaChemica, Inc., 2004, 0469) as well as on
individual studies of granite (Attfield and Costello, 2004, Document ID
0543), diatomaceous earth (Rice et al., 2001, Document ID 1118), and
industrial sand (Hughes et al., 2001, Document ID 1060) worker cohorts,
and a study of coal miners exposed to respirable crystalline silica
(Miller et al., 2007, Document ID 1305; Miller and MacCalman, 2009,
1306). OSHA found these studies to have been suitable for use to
quantitatively characterize health risks to exposed workers because:
(1) Study populations were of sufficient size to provide adequate
statistical power to detect low levels of risk; (2) sufficient
quantitative exposure data were available over a sufficient span of
time to characterize cumulative exposures of cohort members to
respirable crystalline silica; (3) the studies either adjusted for or
otherwise adequately addressed confounding factors such as smoking and
exposure to other carcinogens; and (4) investigators developed
quantitative assessments of exposure-response relationships using
appropriate statistical models or otherwise provided sufficient
information that permits OSHA to do so. OSHA implemented all risk
models in its own life table analysis so that the use of background
lung cancer rates and assumptions regarding length of exposure and
lifetime were consistent across each of the models, and so OSHA could
estimate lung cancer risks associated with exposure to specific levels
of silica of interest to the Agency.
The Steenland et al. (2001a, Document ID 0452) study consisted of a
pooled exposure-response analysis and risk assessment based on raw data
obtained for ten cohorts of silica-exposed workers (65,980 workers,
1,072 lung cancer deaths). The cohorts in this pooled analysis include
U.S. gold miners (Steenland and Brown, 1995a, Document ID 0450), U.S.
diatomaceous earth workers (Checkoway et al., 1997, Document ID 0326),
Australian gold miners (de Klerk and Musk, 1998, Document ID 0345),
Finnish granite workers (Koskela et al., 1994, Document ID 1078), South
African gold miners (Hnizdo et al., 1997, Document ID 1049), U.S.
industrial sand workers (Steenland et al., 2001b, Document ID 0456),
Vermont granite workers (Costello and Graham, 1988, Document ID 0991),
and Chinese pottery workers, tin miners, and tungsten miners (Chen et
al., 1992, Document ID 0329). To determine the exposure-response
relationship between silica exposures and lung cancer, the
investigators used a nested case-control design with cases and controls
matched for race, sex, age (within five years), and study; 100 controls
were matched for each case. An extensive exposure assessment for this
pooled analysis was developed and published by Mannetje et al. (2002a,
Document ID 1090).
Using ToxaChemica's study (2004, Document ID 0469) of this pooled
data, the estimated excess lifetime lung cancer risk associated with 45
years of exposure to 100 [mu]g/m\3\ (about equal to the previous
general industry PEL) is between 20 and 26 deaths per 1,000 workers.
The estimated excess lifetime risk associated with 45 years of exposure
to silica concentrations in the range of 250 and 500 [mu]g/m\3\ (about
equal to the previous construction and shipyard PELs) is between 24 and
33 deaths per 1,000. At the final PEL of 50 [mu]g/m\3\, the estimated
excess lifetime risk ranges from 16 to 23 deaths per 1,000, and, at the
action level of 25 [mu]g/m\3\, from 10 to 21 deaths per 1,000.
In addition to the pooled cohort study, OSHA's Final Quantitative
Risk Assessment presents risk estimates in Table VI-1 derived from four
individual studies where investigators presented either lung cancer
risk estimates or exposure-response coefficients. Two of these studies,
one on diatomaceous earth workers (Rice et al., 2001, Document ID 1118)
and one on Vermont granite workers (Attfield and Costello, 2004,
Document ID 0543), were included in the 10-cohort pooled study
(Steenland et al., 2001a, Document ID 0452; ToxaChemica Inc., 2004,
0469). The other two were of British coal miners (Miller et al., 2007,
Document ID 1305; Miller and MacCalman, 2009,1306) and North American
industrial sand workers (Hughes et al., 2001, Document ID 1060).
Rice et al. (2001, Document ID 1118) presented an exposure-response
analysis of the diatomaceous worker cohort studied by Checkoway et al.
(1993, Document ID 0324; 1996, 0325; 1997, 0326), who found a
significant relationship between exposure to respirable cristobalite
and increased lung cancer mortality. From this cohort the estimates of
the excess risk of lung cancer mortality are 30, 15, and 8 deaths per
1,000 workers for 45 years of exposure to 100, 50, and 25 [mu]g/m\3\,
respectively. For exposures in the range of the current construction
and shipyard PELs over 45 years, estimated risks lie in a range between
72 and 137 excess deaths per 1,000 workers.
Somewhat higher risk estimates are derived from the analysis
presented by Attfield and Costello (2004, Document ID 0543) of Vermont
granite workers. OSHA's use of this analysis yielded a risk estimate of
54 excess deaths per 1,000 workers for 45 years of exposure to the
previous general industry PEL of 100 [mu]g/m\3\, 22 excess deaths per
1,000 for 45 years of exposure to the final PEL of 50 [mu]g/m\3\, and
10 excess deaths per 1,000 for 45 years of exposure at the action level
of 25 [mu]g/m\3\. Estimated excess risks associated with 45 years of
exposure at the current construction PEL range from 231 to 657 deaths
per 1,000.
Hughes et al. (2001, Document ID 1060) conducted a study of
industrial sand workers in the U.S. and Canada. Using this study, OSHA
estimated cancer risks of 33, 14, and 7 deaths per 1,000 for 45 years
exposure to the previous general industry PEL of 100 [mu]g/m\3\, the
final PEL of 50 [mu]g/m\3\, and the final action level of 25 [mu]g/m\3\
respirable crystalline silica, respectively. For 45 years of exposure
to the previous construction PEL, estimated risks range from 120 to 407
deaths per 1,000 workers.
Miller and MacCalman (2010, Document ID 1306; also reported in
Miller et al., 2007, Document ID 1305) presented a study of miners from
10 coal mines in the U.K. Based on this study, OSHA estimated the
lifetime lung cancer mortality risk to be 11 per 1,000 workers for 45
years of exposure to 100 [mu]g/m\3\ respirable crystalline silica. For
the final PEL of 50 [mu]g/m\3\ and action level of 25 [mu]g/m\3\, the
lifetime risks are estimated to be 5 and 3 deaths per 1,000,
respectively. The range of risks estimated to result from 45 years of
exposure to the previous construction and shipyard PELs is from 33 to
86 deaths per 1,000 workers.
2. Summary of Risk Estimates for Silicosis and Other Chronic Lung
Disease Mortality
OSHA based its quantitative assessment of silicosis mortality risks
on a pooled analysis conducted by Mannetje et al. (2002b, Document ID
1089) of data from six of the ten epidemiological studies in the
Steenland et al. (2001a, Document ID 0452) pooled analysis of lung
cancer mortality that also included extensive data on silicosis.
Cohorts included in the silicosis study were: U.S. diatomaceous earth
workers (Checkoway et al., 1997, Document ID 0326); Finnish granite
workers (Koskela et al., 1994, Document ID 1078); U.S. granite workers
(Costello and Graham, 1988, Document ID 0991); U.S. industrial sand workers
(Silicosis and Silicate Disease Committee, 1988, Document ID 0455);
U.S. gold miners (Steenland and Brown, 1995b, Document ID 0451); and
Australian gold miners (de Klerk and Musk, 1998, Document ID 0345).
These six cohorts contained 18,634 workers and 170 silicosis deaths,
where silicosis mortality was defined as death from silicosis (ICD-9
502, n = 150) or from unspecified pneumoconiosis (ICD-9 505, n = 20).
Although Mannetje et al, (2002b, Document ID 1089) estimated silicosis
risks from a Poisson regression, a subsequent analysis was conducted by
Steenland and Bartell (ToxaChemica, 2004, Document ID 0469) based on a
case control design. Based on the Steenland and Bartell analysis, OSHA
estimated that the lifetime risk of silicosis mortality associated with
45 years of exposure to the previous general industry PEL of 100 [mu]g/
m\3\ is 11 deaths per 1,000 workers. Exposure for 45 years to the final
PEL of 50 [mu]g/m\3\ results in an estimated 7 silicosis deaths per
1,000, and exposure for 45 years to the final action level of 25 [mu]g/
m\3\ results in an estimated 4 silicosis deaths per 1,000. Lifetime
risks associated with exposure at the previous construction and
shipyard PELs range from 17 to 22 deaths per 1,000 workers.
To study non-malignant respiratory diseases (NMRD), of which
silicosis is one, Park et al. (2002, Document ID 0405) analyzed the
California diatomaceous earth cohort data originally studied by
Checkoway et al. (1997, Document ID 0326). The authors quantified the
relationship between exposure to cristobalite and mortality from NMRD.
Diseases in this category included pneumoconiosis (which includes
silicosis), chronic bronchitis, and emphysema, but excluded pneumonia
and other infectious diseases. Because of the broader range of silica-
related diseases examined by Park et al., OSHA's estimates of the
lifetime chronic lung disease mortality risk based on this study are
substantially higher than those that OSHA derived from the Mannetje et
al. (2002b, Document ID 1089) silicosis analysis. For the previous
general industry PEL of 100 [mu]g/m\3\, exposure for 45 years is
estimated to result in 85 excess deaths per 1,000 workers. At the final
PEL of 50 [mu]g/m\3\ and action level of 25 [mu]g/m\3\, OSHA estimates
the lifetime risk from 45 years of exposure to be 44 and 22 excess
deaths per 1,000, respectively. The range of risks associated with
exposure at the former construction and shipyard PELs over a working
lifetime is from 192 to 329 excess deaths per 1,000 workers.
3. Summary of Risk Estimates for Renal Disease Mortality
OSHA's analysis of the health effects literature included several
studies that have demonstrated that exposure to respirable crystalline
silica increases the risk of renal and autoimmune disease (see Document
ID 1711, Review of Health Effects Literature and Preliminary QRA, pp.
208-229). For autoimmune disease, there was insufficient data on which
to base a quantitative risk assessment. OSHA's assessment of the renal
disease risks that result from exposure to respirable crystalline
silica is based on an analysis of pooled data from three cohort studies
(Steenland et al., 2002a, Document ID 0448). The combined cohort for
the pooled analysis (Steenland et al., 2002a, Document ID 0448)
consisted of 13,382 workers and included industrial sand workers
(Steenland et al., 2001b, Document ID 0456), U.S. gold miners
(Steenland and Brown, 1995a, Document ID 0450), and Vermont granite
workers (Costello and Graham, 1988, Document ID 0991). Exposure data
were available for 12,783 workers and analyses conducted by the
original investigators demonstrated monotonically increasing exposure-
response trends for silicosis, indicating that exposure estimates were
not likely subject to significant random misclassification. The mean
duration of exposure, cumulative exposure, and concentration of
respirable silica for the combined cohort were 13.6 years, 1.2 mg/m\3\-
years, and 70 [mu]g/m\3\, respectively. There were highly statistically
significant trends for increasing renal disease mortality with
increasing cumulative exposure for both multiple cause analysis of
mortality (p < 0.000001) and underlying cause analysis (p = 0.0007).
OSHA's estimates of renal disease mortality risk based on this study
are 39 deaths per 1,000 for 45 years of exposure at the previous
general industry PEL of 100 [mu]g/m\3\, 32 deaths per 1,000 for
exposure at the final PEL of 50 [mu]g/m\3\, and 25 deaths per 1,000 at
the action level of 25 [mu]g/m\3\. OSHA also estimates that 45 years of
exposure at the previous construction and shipyard PELs would result in
a renal disease excess mortality risk ranging from 52 to 63 deaths per
1,000 workers. OSHA acknowledges that the risk estimates for end-stage
renal disease mortality are less robust than those for silicosis, lung
cancer, and NMRD, and are thus more uncertain.
4. Summary of Risk Estimates for Silicosis Morbidity
OSHA's Final Quantitative Risk Assessment is based on several
cross-sectional studies designed to characterize relationships between
exposure to respirable crystalline silica and development of silicosis
as determined by chest radiography. Due to the long latency periods
associated with silicosis, OSHA relied on those studies that were able
to contact and evaluate many of the workers who had retired. OSHA
believes that relying on studies that included retired workers comes
closest to characterizing lifetime risk of silicosis morbidity. OSHA
identified studies of six cohorts for which the inclusion of retirees
was deemed sufficient to adequately characterize silicosis morbidity
risks well past employment (Hnizdo and Sluis-Cremer, 1991, Document ID
1051; Steenland and Brown, 1995b, 0451; Miller et al., 1998, 0374;
Buchanan et al., 2003, 0306; Chen et al., 2001, 0332; Chen et al.,
2005, 0985). Study populations included five mining cohorts and a
Chinese pottery worker cohort. With the exception of a coal miner study
(Buchanan et al., 2003, Document ID 0306), risk estimates reflected the
risk that a worker will acquire an abnormal chest x-ray classified as
ILO major category 1 or greater; the coal miner study evaluated the
risk of acquiring an abnormal chest x-ray classified as major category
2 or higher.
For miners exposed to freshly cut respirable crystalline silica,
OSHA estimates the risk of developing lesions consistent with an ILO
classification of category 1 or greater to range from 120 to 773 cases
per 1,000 workers exposed at the previous general industry PEL of 100
[mu]g/m\3\ for 45 years; from 20 to 170 cases per 1,000 workers exposed
at the final PEL of 50 [mu]g/m\3\; and from 5 to 40 cases per 1,000
workers exposed at the new action level of 25 [mu]g/m\3\. From the coal
miner study of Buchanan et al., (2003, Document ID 0306), OSHA
estimates the risks of acquiring an abnormal chest x-ray classified as
ILO category 2 or higher to be 301, 55, and 21 cases per 1,000 workers
exposed for 45 years to 100, 50, and 25 [mu]g/m\3\, respectively. These
estimates are within the range of risks obtained by OSHA from the other
mining studies. At exposures at or above 250 [mu]g/m\3\ (equivalent to
the previous construction and shipyard PELs) for 45 years, the risk of
acquiring an abnormal chest x-ray approaches 100 percent. OSHA's risk
estimates based on the pottery cohort are 60, 20, and 5 cases per 1,000
workers exposed for 45 years to 100, 50, and 25 [mu]g/m\3\,
respectively, which is generally below the range of risks estimated
from the other studies and may reflect a lower toxicity of quartz
particles in that work environment due to the presence of
aluminosilicates on the particle surfaces (see Section V.N, Comments
and Responses Concerning Physico-chemical and Toxicological Properties
of Respirable Crystalline Silica); they are still well over OSHA's 1 in
a 1,000 workers benchmark for setting standards, however. According to
Chen et al. (2005, Document ID 0985), adjustment of the exposure metric
to reflect the unoccluded surface area of silica particles resulted in
an exposure-response of pottery workers that was similar to the mining
cohorts, indicating that the occluded surface reduced the toxic potency
of the quartz particles. The finding of a reduced silicosis risk among
pottery workers is consistent with other studies of clay and brick
industries that have reported finding a lower prevalence of silicosis
compared to that experienced in other industry sectors (Love et al.,
1999, Document ID 0369; Hessel, 2006, 1299; Miller and Soutar, 2007,
1098) as well as a lower silicosis risk per unit of cumulative exposure
(Love et al., 1999, Document ID 0369; Miller and Soutar, 2007, 1098).
D. Significance of Risk and Risk Reduction
In this section, OSHA presents its final findings with respect to
the significance of the risks summarized above and the potential of the
proposed standard to reduce those risks. Findings related to mortality
risk will be presented first, followed by silicosis morbidity risks.
1. Mortality Risks
OSHA's Final Quantitative Risk Assessment described above presents
risk estimates for four causes of excess mortality: Lung cancer,
silicosis, non-malignant respiratory disease (including silicosis), and
renal disease. Table VI-1 above presents OSHA's estimated excess
lifetime risks (i.e., to age 85, following 45 years of occupational
exposure) of these fatal diseases associated with various levels of
respirable crystalline silica exposure allowed under the former PELs
and the final PEL and action level promulgated herein. OSHA's mortality
risk estimates represent "excess" risks in the sense that they
reflect the risk of dying from disease over and above that of persons
who are not occupationally exposed to respirable crystalline silica.
Assuming a 45-year working life, as OSHA has done in significant
risk determinations for previous standards, the Agency finds that the
excess risk of disease mortality related to exposure to respirable
crystalline silica at levels permitted by the previous OSHA standards
is clearly significant. The Agency's estimate of such risk falls well
above the level of risk the Supreme Court indicated a reasonable person
would consider unacceptable (Benzene, 448 U.S. 607, 655). For lung
cancer, OSHA estimates the range of risk at the previous general
industry PEL to be between 11 and 54 deaths per 1,000 workers. The
estimated risk for silicosis mortality is 11 deaths per 1,000 workers;
however, the estimated lifetime risk for non-malignant respiratory
disease (NMRD) mortality, including silicosis, is about 8-fold higher
than that for silicosis alone, at 85 deaths per 1,000. This higher
estimate for NMRD is better than the estimate for silicosis mortality
at capturing the total respiratory disease burden associated with
exposure to crystalline silica dust. The former captures deaths related
to other non-malignant diseases, including chronic bronchitis and
emphysema, for which there is strong evidence of a causal relationship
with exposure to silica, and is also more likely to capture those
deaths where silicosis was a contributing factor but where the cause of
death was misclassified. Finally, there is an estimated lifetime risk
of renal disease mortality of 39 deaths per 1,000. Exposure for 45
years at levels of respirable crystalline silica in the range of the
previous limits for construction and shipyards results in even higher
risk estimates, as presented in Table VI-1. It should be noted that
these risk estimates are not additive because some individuals may
suffer from multiple diseases caused by exposure to silica.
To further demonstrate significant risk, OSHA compares the risks at
the former PELs and the revised PEL for respirable crystalline silica
to risks found across a broad variety of occupations. OSHA also
compares the lung cancer risk associated with the former PELs and
revised PEL to the risks for other carcinogens OSHA regulates. The
Agency has used similar occupational risk comparisons in the
significant risk determinations for other substance-specific standards.
Fatal injury rates for most U.S. industries and occupations may be
obtained from data collected by the Department of Labor's Bureau of
Labor Statistics (BLS). Table VI-3 shows annual fatality rates per
1,000 employees for several industries for 2013, as well as projected
fatalities per 1,000 employees assuming exposure to workplace hazards
for 45 years based on these annual rates. While it is difficult to
meaningfully compare aggregate industry fatality rates to the risks
estimated in the quantitative risk assessment for respirable
crystalline silica, which address one specific hazard (inhalation
exposure to respirable crystalline silica) and several health outcomes
(lung cancer, silicosis, NMRD, renal disease mortality), these rates
provide a useful frame of reference for considering risk from
inhalation exposure to crystalline silica. For example, OSHA's
estimated range of 5-54 excess lung cancer deaths per 1,000 workers
from regular occupational exposure to respirable crystalline silica in
the range of 50-100 [mu]g/m\3\ is roughly comparable to, or higher
than, the expected risk of fatal injuries over a working life in high-
risk occupations such as mining and construction (see Table VI-3).
Regular exposures at higher levels, including the previous construction
and shipyard PELs for respirable crystalline silica, are expected to
cause substantially more deaths per 1,000 workers from lung cancer
alone (ranging from 24 to 657 per 1,000) than result from occupational
injuries in most private industry. At the final PEL of 50 [mu]g/
m3 respirable crystalline silica, the Agency's estimate of
excess lung cancer mortality, from 5 to 23 deaths per 1,000 workers, is
still 3- to 15-fold higher than private industry's average fatal injury
rate, given the same employment time, and substantially exceeds those
rates found in lower-risk industries such as finance and educational
and health services. Adding in the mortality from silicosis, NMRD, and
renal disease would make these comparisons even more stark.
Because there is little available information on the incidence of
occupational cancer across all industries, risk from crystalline silica
exposure cannot be compared with overall risk from other workplace
carcinogens. However, OSHA's previous risk assessments provide
estimates of risk from exposure to certain carcinogens. These risk
assessments, as with the current assessment for respirable crystalline
silica, were based on animal or human data of reasonable or high
quality and used the best information then available. Table VI-4 shows
the Agency's best estimates of cancer risk from 45 years of
occupational exposure to several carcinogens, as published in the
preambles to final rules promulgated since the Benzene decision in
1980.
The estimated excess lung cancer mortality risks associated with
respirable crystalline silica at the previous general industry PEL, 11-
54 deaths per 1,000 workers, are comparable to, and in some cases
higher than, the estimated excess cancer risks for many other workplace
carcinogens for which OSHA made a determination of significant risk
(see Table VI-4, "Selected OSHA Risk Estimates for Prior and Current
PELs"). The estimated excess lung cancer risks associated with
exposure to the previous construction and shipyard PELs are even
higher. The estimated risk from lifetime occupational exposure to
respirable crystalline silica at the final PEL of 50 [mu]g/m\3\ is 5-23
excess lung cancer deaths per 1,000 workers, a range still higher than
the risks from exposure to many other carcinogens regulated by OSHA.
OSHA's risk assessment also shows that reduction of the PELs for
respirable crystalline silica to the final level of 50 [mu]g/m\3\ will
result in substantial reduction in risk, although quantitative
estimates of that reduction vary depending on the statistical models
used. Risk models that reflect attenuation of the risk with increasing
exposure, such as those relating risk to a log transformation of
cumulative exposure, will result in lower estimates of risk reduction
compared to linear risk models. Thus, for lung cancer risks, the
assessment based on the 10-cohort pooled analysis by Steenland et al.
(2001, Document ID 0455; also 0469; 1312) suggests risk will be reduced
by about 14 percent from the previous general industry PEL and by 28-41
percent from the previous construction/shipyard PEL (based on the
midpoint of the ranges of estimated risk derived from the three models
used for the pooled cohort data). These risk reduction estimates,
however, are much lower than those derived from the single cohort
studies (Rice et al., 2001, Document ID 1118; Attfield and Costello,
2004, 0543; Hughes et al., 2001, 1060; Miller and MacCalman 2009,
1306). These single cohort studies suggest that reducing the previous
PELs to the final PEL will reduce lung cancer risk by more than 50
percent in general industry and by more than 80 percent in construction
and shipyards.
For silicosis mortality, OSHA's assessment indicates that risk will
be reduced by 36 percent and by 58-68 percent as a result of reducing
the previous general industry and construction/shipyard PELs,
respectively. NMRD mortality risks will be reduced by 48 percent and by
77-87 percent as a result of reducing the general industry and
construction/shipyard PELs, respectively, to the new PEL. There is also
a substantial reduction in renal disease mortality risks; an 18-percent
reduction associated with reducing the previous general industry PEL
and a 38-49 percent reduction associated with reducing the previous
construction/shipyard PEL.
Thus, OSHA believes that the final PEL of 50 [mu]g/m\3\ respirable
crystalline silica will substantially reduce the risk of material
health impairments associated with exposure to silica. However, even at
this final PEL, as well as the action level of 25 [mu]g/m\3\, the risk
posed to workers with 45 years of regular exposure to respirable
crystalline silica is greater than 1 per 1,000 workers and is still
clearly significant.
2. Silicosis Morbidity Risks
OSHA's Final Quantitative Risk Assessment also characterizes the
risk of developing silicosis, defined as developing lung fibrosis
detected by chest x-ray. For 45 years of exposure at the previous
general industry PEL of 100 [mu]g/m\3\, OSHA estimates that the risk of
developing lung fibrosis consistent with an ILO category 1+ degree of
small opacity profusion ranges from 60 to 773 cases per 1,000. For
exposure at the previous construction and shipyard PELs, the risk
approaches 100 percent. The wide range of risk estimates derived from
the underlying studies relied on for the risk assessment may reflect
differences in the relative toxicity of quartz particles in different
workplaces; nevertheless, OSHA finds that each of these risk estimates
clearly represents a significant risk of developing fibrotic lesions in
the lung. Exposure to the final PEL of 50 [mu]g/m\3\ respirable
crystalline silica for 45 years yields an estimated risk of between 20
and 170 cases per 1,000 for developing fibrotic lesions consistent with
an ILO category of 1+. These risk estimates indicate that the final PEL
will result in a reduction in risk by about two-thirds or more, which
the Agency finds is a substantial reduction of the risk of developing
abnormal chest x-ray findings consistent with silicosis.
One study of coal miners also permitted the agency to evaluate the
risk of developing lung fibrosis consistent with an ILO category 2+
degree of profusion of small opacities (Buchanan et al., 2003, Document
ID 0306). This level of profusion has been shown to be associated with
a higher prevalence of lung function decrement and an increased rate of
early mortality (Ng et al., 1987a, Document ID 1108; Begin et al.,
1988, 0296; Moore et al., 1988, 1099; Ng et al., 1992a, 0383; Infante-
Rivard, 1991, 1065). From this study, OSHA estimates that the risk
associated with 45 years of exposure to the previous general industry
100 [mu]g/m\3\ PEL is 301 cases per 1,000 workers, again a clearly
significant risk. Exposure to the final PEL of 50 [mu]g/m\3\ respirable
crystalline silica for 45 years yields an estimated risk of 55 cases
per 1,000 for developing lesions consistent with an ILO category 2+
degree of small opacity profusion. This represents a reduction in risk
of over 80 percent, again a clearly substantial reduction of the risk
of developing radiologic silicosis consistent with ILO category 2+.
3. Sources of Uncertainty and Variability in OSHA's Risk Assessment
Throughout the development of OSHA's risk assessment for silica-
related health effects, sources of uncertainty and variability have
been identified by the Agency, peer reviewers, interagency reviewers,
stakeholders, scientific experts, and the general public. This
subsection reviews and summarizes several general areas of uncertainty
and variability in OSHA's risk assessment. As used in this section,
"uncertainty" refers to lack of knowledge about factors affecting
exposure or risk, and "variability" refers to heterogeneity, for
example, across people, places, or time. For more detailed discussion
and evaluation of sources of uncertainty in the risk assessment and a
comprehensive review of comments received by OSHA on the risk
assessment, (see discussions provided throughout the previous section,
Section V, Health Effects).
As shown in Table VI-1, OSHA's risk estimates for lung cancer are a
range derived from a pooled analysis of 10 cohort studies (Steenland et
al., 2001a, Document ID 0452; ToxaChemica, Inc., 2004, 0469), a study
of granite workers (Attfield and Costello, 2004, Document ID 0543), a
study of diatomaceous earth workers (Rice et al., 2001, Document ID
1118), a multi-cohort study of industrial sand workers (Hughes et al.,
2001, Document ID 1060), and a study of coal miners exposed to
respirable crystalline silica (Miller et al., 2007, Document ID 1305;
Miller and MacCalman, 2009, 1306). Similarly, a variety of studies in
several different working populations was used to derive risk estimates
of silicosis mortality, silicosis morbidity, and renal disease
mortality. The ranges of risks presented in Table VI-1 for silica
mortality and the other health endpoints thus reflect silica exposure-
response across a variety of industries and worker populations, which
may differ for reasons such as the processes in which silica exposure
occurs and the various kinds of minerals that co-exist with crystalline
silica in the dust particles (see discussion on variability in
toxicological potency of crystalline silica later in this section). The
ranges presented in Table VI-1 do not reflect statistical uncertainty
(e.g., 95% confidence intervals) or model uncertainty (e.g., the slope
of the exposure-response curve at exposures higher or lower than the
exposures of the study population) but do reflect variability in the
sources of data for the different studies.
The risks presented in Table VI-1, however, do not reflect
variability in the consistency, duration or frequency of workers'
exposures. As discussed previously in this section, OSHA's final
estimates of health risks represent risk associated with exposure to an
8-hour time weighted average of 25, 50, 100, 250 and 500 [mu]g/m\3\
respirable crystalline silica. These levels represent the risks
associated with continuous occupational exposure over a working
lifetime of 45 years to the new action level, new PEL, previous general
industry PEL, and the range in exposure (250-500 [mu]g/m\3\) that
approximates the previous construction and shipyard PELs, respectively.
OSHA estimates risks assuming exposure over a working life so that it
can evaluate the significance of the risk associated with exposure at
the previous PELs in a manner consistent with Section 6(b)(5) of the
Act, which requires OSHA to set standards that substantially reduce
these risks to the extent feasible even if workers are exposed over a
full working lifetime. However, while the risk assessment is based on
the assumed working life of 45 years, OSHA recognizes that risks
associated with shorter-term or intermittent exposures at a given
airborne concentration of silica will be less than the risk associated
with continuous occupational exposure at the same concentration over a
working lifetime. OSHA thus also uses alternatives to the 45-year full-
time exposure metric in its projections of the benefits of the final
rule (Section VII of this preamble and the FEA) that reflect the
reduction in silica-related disease that the Agency expects will result
from implementation of the revised standard, using the various
estimates of workers' typical exposure levels and patterns.
The remainder of this discussion reviews several general areas of
uncertainty and variability in OSHA's risk assessment that are not
quantitatively reflected in the risk estimates shown in Table VI-1, but
that provide important context for understanding these estimates,
including differences in the degree of uncertainty among the estimates.
These areas include exposure estimation error, dose-rate effects, model
form uncertainty, variability in toxicological potency of crystalline
silica, and additional sources of uncertainty specific to particular
endpoints, (e.g., the small number of cases in the renal disease
analysis), differing conclusions in the literature on silica as a
causative factor in renal disease and lung cancer, and reporting error
in silicosis mortality and morbidity. These different sources of
uncertainty have varying effects that can lead either to under- or
over-estimation of risks. OSHA has taken these sources of uncertainty into
account in concluding that the body of scientific literature supports
the finding that there is significant risk at existing levels of
exposure. The Agency is not required to support the finding that a
"significant risk exists with anything approaching scientific
certainty" (Benzene, 448 U.S. at 656).
a. Exposure Estimation Error
As discussed in Section V, OSHA identified exposure estimation
error as a key source of uncertainty in most of the studies and thus
the Agency's risk assessment. OSHA's contractor, ToxaChemica, Inc.,
commissioned Drs. Kyle Steenland and Scott Bartell to perform an
uncertainty analysis to examine the effect of uncertainty due to
exposure estimation error in the pooled studies (Steenland et al.,
2001a, Document ID 0452; Mannetje 2002b, 1089) on the lung cancer and
silicosis mortality risk estimates (ToxaChemica, Inc., 2004, Document
ID 0469). Drs. Steenland and Bartell addressed two main sources of
error in the silica exposure estimates. The first arises from the
assignment of individual workers' exposures based either on exposure
measurements for a sample of workers in the same job or estimated
exposure levels for specific jobs in the past when no measurements were
available, via a job-exposure matrix (JEM) (Mannetje et al., 2002a,
Document ID 1090). The second arises from the conversion of
historically-available dust measurements, typically particle count
concentrations, to gravimetric respirable silica concentrations.
ToxaChemica, Inc. conducted an uncertainty analysis using the raw data
from the IARC multi-centric study to address these sources of error
(2004, Document ID 0469).
To explore the potential effects of both kinds of uncertainty
described above, ToxaChemica, Inc. (2004, Document ID 0469) used the
distributions representing the error in job-specific exposure
assignment and the error in converting exposure metrics to generate 50
exposure simulations for each cohort. A study-specific coefficient and
a pooled coefficient were fit for each new simulation. The results
indicated that the only lung cancer cohort for which the mean of the
exposure coefficients derived from the simulations differed
substantially from the previously calculated exposure coefficient was
the South African gold cohort (simulation mean of 0.181 vs. original
coefficient of 0.582). This suggests that the results of exposure-
response analyses conducted using the South African cohort are
sensitive to error in exposure estimates; therefore, there is greater
uncertainty due to potential exposure estimation error in an exposure-
response model based on this cohort than is the case for the other nine
cohorts in Steenland et al's analysis (or, put another way, the
exposure estimation for the other nine cohorts was less sensitive to
the effects of exposure measurement uncertainty).
For the pooled analysis, the mean coefficient estimate from the
simulations was 0.057, just slightly lower than the previous estimate
of 0.060. Based on these results, OSHA concluded that random error in
the underlying exposure estimates in the Steenland et al. (2001a,
Document ID 0452) pooled cohort study of lung cancer is not likely to
have substantially influenced the original findings.
Following the same procedures described above for the lung cancer
analysis, ToxaChemica, Inc. (2004, Document ID 0469) combined both
sources of random measurement error in a Monte Carlo analysis of the
silicosis mortality data from Mannetje et al. (2002b, Document ID
1089). The silicosis mortality dataset appeared to be more sensitive to
possible error in exposure measurement than the lung cancer dataset,
for which the mean of the simulation coefficients was virtually
identical to the original. To reflect this exposure measurement
uncertainty, OSHA's final risk estimates derived from the pooled
analysis (Mannetje et al., 2002b, Document ID 1089), incorporated
ToxaChemica, Inc.'s simulated measurement error (2004, Document ID
0469).
b. Uncertainty Related to Dose-Rate Effects
OSHA received comments citing uncertainty in its risk assessment
related to possible dose-rate effects in the silica exposure-response
relationships, particularly for silicosis. For example, the ACC
commented that extrapolating risks from the high mean exposure levels
in the Park et al. 2002 cohort (Document ID 0405) to the much lower
mean exposure levels relevant to OSHA's risk assessment contributes
uncertainty to the analysis (Document ID 4209, pp. 84-85), because of
the possibility that risk accrues differently at different exposure
concentrations. The ACC thus argued that the risk associated with any
particular level of cumulative exposure may be higher for exposure to a
high concentration of respirable crystalline silica over a short period
of time than for an equivalent cumulative exposure resulting from
exposure to a low concentration of respirable crystalline silica over a
long period of time (Document ID 4209, p. 58; 2307, Attachment A, pp.
93-94). These and similar comments on dose-rate effects questioned
OSHA's use of workers' cumulative exposure levels to estimate risk, as
the cumulative exposure metric does not capture dose-rate effects.
Thus, according to the ACC, if there are significant dose-rate effects
in the exposure-response relationship for a disease or other health
endpoint, use of the cumulative exposure metric could lead to error in
risk estimates.
The rationale for OSHA's reliance on a cumulative exposure metric
to assess the risks of respirable crystalline silica is discussed in
Section V. With respect to this issue of uncertainty related to dose-
response effects, OSHA finds limited evidence in the record to either
support or refute the effects hypothesized by the ACC. As such, OSHA
acknowledges some uncertainty. Furthermore, use of an alternative
metric such as concentration would not provide assurance that
uncertainties would be mitigated or reduced.
Two studies discussed in OSHA's Review of Health Effects Literature
and Preliminary QRA examined dose-rate effects on silicosis exposure-
response (Document ID 1711, pp. 342-344). Neither study found a dose-
rate effect relative to cumulative exposure at silica concentrations
near the previous OSHA PEL (Document ID 1711, pp. 342-344). However,
they did observe a dose-rate effect in instances where workers were
exposed to crystalline silica concentrations far above the previous PEL
(i.e., several-fold to orders of magnitude above 100 [mu]g/m\3\)
(Buchanan et al., 2003, Document ID 0306; Hughes et al., 1998, 1059).
The Hughes et al. (1998) study of diatomaceous earth workers found that
the relationship between cumulative silica exposure and risk of
silicosis was steeper for workers hired prior to 1950 and exposed to
average concentrations above 500 [micro]g/m\3\ compared to workers
hired after 1950 and exposed to lower average concentrations (Document
ID 1059). Hughes et al. reported that subdivisions for workers with
exposure to concentrations below 500 [mu]g/m\3\ were examined, but that
no differences were observed across these groups (Document ID 1059, p.
809). It is unclear whether sparse data at the low end of the
concentration range contributed to this finding, as the authors did not
provide detailed information on the distribution of exposures in the
study population.
The Buchanan et al. (2003) study of Scottish coal miners adjusted
the cumulative exposure metric in the risk model to account for the
effects of exposures to high concentrations where the investigators
found that, at concentrations above 2000 [mu]g/m\3\, the risk of
silicosis was about three times higher than the risk associated with
exposure to lower concentrations but at the same cumulative exposure
(Document ID 0306, p. 162). Buchanan et al. noted that only 16 percent
of exposure hours among the workers in the study occurred at levels
below 10 [mu]g/m\3\ (Document ID 0306, p. 161), and cautioned that
insufficient data are available to predict effects at very low
concentrations where data are sparse (Document ID 0306, p. 163).
However, 56 percent of hours occurred at levels between 10 and
100 [mu]g/m\3\. Detailed information on the hours worked at
concentrations within this range was not provided.
Based on its review of these studies, OSHA concluded that there is
little evidence that a dose-rate effect exists at concentrations in the
range of the previous PEL (100 [mu]g/m\3\) (Document ID 1711, p. 344).
However, there remains some uncertainty related to dose-rate effects in
the Agency's silicosis risk assessment. Even if a dose-rate effect
exists only at concentrations far higher than the previous PEL, it is
possible for the dose-rate effect to impact model form if not properly
accounted for in study populations with high-concentration exposures.
This is one reason that OSHA presents a range of risk estimates based
on a variety of study populations exposed under different working
conditions. For example, as OSHA noted in its Review of Health Effects
Literature and Preliminary QRA (Document ID 1711, pp. 355-356), the
Park et al. study is complemented by the Mannetje et al. multi-cohort
silicosis mortality pooled study. Mannetje et al.'s study included
several cohorts that had exposure concentrations in the range of
interest for this rulemaking and also showed clear evidence of
significant risk of silicosis mortality at the previous general
industry and construction PELs (2002b, Document ID 1089). In addition,
OSHA used the model from the Buchanan et al. study in its silicosis
morbidity risk assessment to account for possible dose-rate effects at
high average concentrations (Document ID 1711, pp. 335-342). OSHA notes
that the risk estimates in the exposure range of interest (25-500
[mu]g/m\3\) derived from the Buchanan et al. (2003) study were not
appreciably different from those derived from the other studies of
silicosis morbidity (see Table VI-1).
c. Model Form Uncertainty
Another source of uncertainty in OSHA's risk analysis is
uncertainty with respect to the form of the statistical models used to
characterize the relationship between exposure level and risk of
adverse health outcomes. As discussed in Section V, some commenters
expressed concern that studies relied on by OSHA may not have
considered all potential exposure-response relationships and might be
unable to discern differences between monotonic and non-monotonic
characteristics (e.g., Document ID 2307, Attachment A, p. 113-114).
OSHA acknowledges that the possibility of error in selection of
exposure-response model forms is a source of uncertainty in the silica
risk assessment. To address this uncertainty, the Agency included
studies in the risk assessment that explored a variety of model forms.
For example, as discussed in Section V, the ToxaChemica reanalyses of
the Mannetje et al. silicosis mortality dataset and the Steenland et
al. lung cancer mortality data set examined several model forms
including a five-knot restricted spline analysis, which is a highly
flexible model form able to capture a variety of exposure-response
shapes (Document ID 0469, p. 50). The ToxaChemica reanalysis addresses
the issue of model form uncertainty by finding similar exposure-
response relationships regardless of the type of model used.
d. Uncertainty Related to Silica Exposure as a Risk Factor for Lung
Cancer
As discussed in Section V, OSHA has reviewed the best available
evidence on the relationship between silica exposure and lung cancer
mortality, and has concluded that the weight of evidence supports the
finding that exposure to silica at the preceding and new PELs increases
the risk of lung cancer. However, OSHA acknowledges that not every
study in the literature on silica-related lung cancer reached the same
conclusions. This variability is to be expected in epidemiology, as
there are different cohorts, measurements, study designs, and
analytical methods, among other factors. OSHA further acknowledges that
there is uncertainty with respect to the magnitude of the risk of lung
cancer from silica exposure. In the case of silica, the exposure-
response relationship with lung cancer may be easily obscured, as
crystalline silica is a comparably weaker carcinogen (i.e., the
increase in risk per unit exposure is smaller) than other well-studied,
more potent carcinogens such as hexavalent chromium (Steenland et al.,
2001, Document ID 0452, p. 781) and tobacco smoke, a common co-exposure
in silica-exposed populations.
A study by Vacek et al. (2011) illustrates the uncertainties
involved in evaluating risk of lung cancer from silica exposure. This
study found no significant association between respirable silica
exposure and lung cancer mortality in a cohort of Vermont granite
workers (Document ID 1486, pp. 75-81). Some commenters criticized
OSHA's preliminary risk assessment for rejecting the Vacek et al.
(2011) study and instead relying upon the Attfield and Costello (2004,
Document ID 0284) study of Vermont granite workers (Document ID 2307,
Attachment A, pp. 36-47; 4209, pp. 34-36). As discussed in detail in
Section V, OSHA reviewed the Vacek et al. study and all comments
received by the Agency on this issue, and has decided not to reject the
Attfield and Costello (2004) study in favor of the Vacek et al. (2011)
study as a basis for risk assessment. OSHA acknowledges that
comprehensive studies, such as those of Attfield and Costello (2004)
and Vacek et al. (2011), in the Vermont granite industry have shown
conflicting results with respect to lung cancer mortality (Document ID
0284; 1486). Although OSHA believes that the Attfield and Costello
(2004) study is the most appropriate Vermont granite study to use in
its QRA, it also relied upon other studies, and that the risk estimates
for lung cancer mortality based on those studies (i.e., Document ID
0543, 1060, 1118, 1306) still provide substantial evidence that
respirable crystalline silica poses a significant risk of lung cancer
to exposed workers.
e. Uncertainty Related to Renal Disease
As discussed in Section V, OSHA acknowledges that there are
considerably less data for renal disease mortality than those for
silicosis, lung cancer, and non-malignant respiratory disease (NMRD)
mortality. Although the Agency believes the renal disease risk findings
are based on credible data, the risk findings based on them are less
robust than the findings for silicosis, lung cancer, and NMRD.
Based upon its overall analysis of the literature, including the
negative studies, OSHA has concluded that there is substantial evidence
suggesting an association between exposure to crystalline silica and
increased risks of renal disease. This conclusion is supported by a
number of case reports and epidemiological studies that found
statistically significant associations between occupational exposure to
silica dust and chronic renal disease (Calvert et al., 1997, Document
ID 0976), subclinical renal changes (Ng et al., 1992c, Document ID
0386), end-stage renal disease morbidity (Steenland et al., 1990,
Document ID 1125), end-stage renal disease incidence (Steenland et al.,
2001b, Document ID 0456), chronic renal disease mortality
(Steenland et al., 2002a, 0448), and granulomatosis with
polyangitis (Nuyts et al., 1995, Document ID 0397). However, as
discussed in the Review of Health Effects Literature and Preliminary
QRA, the studies reviewed by OSHA included a number of studies that did
not show an association between crystalline silica and renal disease
(Document ID 1711, pp. 211-229). Additional negative studies by Birk et
al. (2009, Document ID 1468), and Mundt et al. (2011, Document ID 1478)
were reviewed in the Supplemental Literature Review of the Review of
Health Effects Literature and Preliminary QRA, which noted the short
follow-up period as a limitation, which reduces the likelihood that an
increased incidence of renal mortality would have been detected
(Document ID 1711, Supplement, pp. 6-12). Comments submitted to OSHA by
the ACC additionally cited several studies that did not show a
statistically significant association between exposure to crystalline
silica and renal disease mortality, including McDonald et al. (2005,
Document ID 1092), Vacek et al. (2011, Document ID 2340), Davis et al.
(1983, Document ID 0999), Koskela et al. (1987, Document ID 0363),
Cherry et al. (2012, article included in Document ID 2340), Steenland
et al. (2002b, Document ID 0454), Rosenman et al. (2000, Document ID
1120), and Calvert et al. (2003, Document ID 0309) (Document ID 2307,
Attachment A, pp. 140-145).
As discussed in detail in Section V, OSHA concludes that the
evidence supporting causality regarding renal risk outweighs the
evidence casting doubt on that conclusion, but acknowledges this
divergence in the renal disease literature as a source of uncertainty.
OSHA estimated quantitative risks for renal disease mortality
(Document ID 1711, pp. 314-316) using data from a pooled analysis of
renal disease, conducted by Steenland et al. (2002a, Document ID 0448).
The data set included 51 deaths from renal disease as an underlying
cause, which the authors of the pooled study, Drs. Kyle Steenland and
Scott Bartell, acknowledged to be insufficient to provide robust
estimates of risk (Document ID 2307, Attachment A, p. 139, citing 0469,
p. 27). OSHA agrees with Dr. Steenland and acknowledges, as it did in
its Review of Health Effects Literature and Preliminary QRA (Document
ID 1711, p. 357), that its quantitative risk estimates for renal
disease mortality are less robust than those for the other health
effects examined (i.e., lung cancer mortality, silicosis and NMRD
mortality, and silicosis morbidity).
f. Uncertainty in Reporting and Diagnosis of Silicosis Mortality and
Silicosis Morbidity
OSHA's final quantitative risk assessment includes risk estimates
for silicosis mortality and morbidity. Silicosis mortality is
ascertained by analysis of death certificates for cause of death, and
morbidity is ascertained by the presence of chest radiographic
abnormalities consistent with silicosis among silica-exposed workers.
Each of these kinds of studies are associated with uncertainties in
case ascertainment and use of chest roentgenograms to detect lung
scarring due to silicosis.
For silicosis mortality, OSHA's analysis includes a pooled analysis
of six epidemiological studies first published by Mannetje et al.
(2002b, Document ID 1089) and re-analyzed by OSHA's contractor
ToxaChemica (2004, Document ID 0469). OSHA finds that the estimates
from Mannetje et al. and ToxaChemica's analyses are likely to
understate the actual risk because silicosis is under-reported as a
cause of death, as discussed in Sections VC.2.iv and V.E in the context
of silicosis disease surveillance systems. To help address this
uncertainty, OSHA's risk analysis also included an exposure-response
analysis of diatomaceous earth (DE) workers (Park et al., 2002,
Document ID 0405), which better captures the totality of silica-related
respiratory disease than do the datasets analyzed by Mannetje et al.
and ToxaChemica. Park et al.. quantified the relationship between
cristobalite exposure and mortality caused by NMRD, which includes
silicosis, pneumoconiosis, emphysema, and chronic bronchitis. Because
NMRD captures much of the silicosis misclassification that results in
underestimation of the disease and includes risks from other lung
diseases associated with crystalline silica exposures, OSHA finds the
risk estimates derived from the Park et al. study are important to
include as part of OSHA's range of estimates of the risk of death from
silica-related respiratory diseases, including silicosis. (Document ID
1711, pp. 297-298). OSHA concludes that the range of silicosis and NMRD
risks presented in the final risk assessment, based on both the
ToxaChemica reanalysis of Mannetje et al.'s silicosis mortality data
and Park et al.'s study of NMRD mortality, provide a credible range of
estimates of mortality risk from silicosis and NMRD across a range of
industrial workplaces. The upper end of this range, based on the Park
et al. study, is less likely to underestimate risk as a result of
under-reporting of silicosis mortality, but cannot be directly compared
to risk estimates from studies that focused on cohorts of workers from
different industries.
OSHA's estimates of silicosis morbidity risks are based on studies
of active and retired workers for which exposure histories could be
constructed and chest x-ray films could be evaluated for signs of
silicosis. There is evidence in the record that chest x-ray films are
relatively insensitive to detecting lung fibrosis. Hnizdo et al. (1993,
Document ID 1050) found chest x-ray films to have low sensitivity for
detecting lung fibrosis related to silicosis, compared to pathological
examination at autopsy. To address the low sensitivity of chest x-rays
for detecting silicosis, Hnizdo et al. (1993, Document ID 1050)
recommended that radiographs consistent with an ILO category of 0/1 or
greater be considered indicative of silicosis among workers exposed to
a high concentration of silica-containing dust. In like manner, to
maintain high specificity, chest x-rays classified as category 1/0 or
1/1 should be considered as a positive diagnosis of silicosis. Studies
relied on in OSHA's risk assessment typically used an ILO category of
1/0 or greater to identify cases of silicosis. According to Hnizdo et
al., they are unlikely to include many false positives (diagnoses of
silicosis where there is none), but may include false negatives
(failure to identify cases of silicosis). Thus, the use of chest
roentgenograms to ascertain silicosis cases in the morbidity studies
relied on by OSHA in its risk assessment could lead to an
underestimation of risk given the low sensitivity of chest
roentgenograms for detecting silicosis.
g. Variability in Toxicological Potency of Crystalline Silica
As discussed in Section V, the toxicological potency of crystalline
silica is influenced by a number of physical and chemical factors that
affect the biological activity of inhaled silica particles. The
toxicological potency of crystalline silica is largely influenced by
the presence of oxygen free radicals on the surfaces of respirable
particles. These chemically-reactive oxygen species interact with
cellular components in the lung to promote and sustain the inflammatory
reaction responsible for the lung damage associated with exposure to
crystalline silica. The reactivity of particle surfaces is greatest
when crystalline silica has been freshly fractured by high-energy
work processes such as abrasive blasting, rock drilling, or sawing
concrete materials. As particles age in the air, the surface reactivity
decreases and exhibits lower toxicologic potency (Porter et al., 2002,
Document ID 1114; Shoemaker et al., 1995, 0437; Vallyathan et al.,
1995, 1128). In addition, surface impurities have been shown to alter
silica toxicity. For example, aluminum and aluminosilicate clay on
silica particles has been shown to decrease toxicity (Castranova et
al., 1997, Document ID 0978; Donaldson and Borm, 1998, 1004; Fubini,
1998, 1016; Donaldson and Borm, 1998, Document ID 1004; Fubini, 1998,
1016).
In the preamble to the proposed standard, OSHA preliminarily
concluded that although there is evidence that several environmental
influences can modify surface activity to either enhance or diminish
the toxicity of silica, the available information was insufficient to
determine to what extent these influences may affect risk to workers in
any particular workplace setting (Document 1711, p. 350). OSHA
acknowledges that health risks are probably in the low end of the range
for workers in the brick manufacturing industry, although the evidence
still indicates that there is a significant risk at the previous
general industry PEL for those workers. OSHA also acknowledges that
there was a lack of evidence for a significant risk in the sorbent
minerals industry due to the nature of crystalline silica present in
those operations; as a result, it decided to exclude sorptive clay
processing from this rule. Furthermore, Dudley and Morriss (2015) raise
concerns about the whether the exposures reflected in the historical
cohorts used in the risk assessment are sufficiently reflective of
rapidly changing working conditions over the last 45 years.\11\
However, the risk estimates presented in Table VI-1 are based on
studies from a variety of industries, such that the risk ranges
presented are likely to include estimates appropriate to most working
populations. Thus, in OSHA's view, its significant risk finding is well
supported by the weight of best available evidence, notwithstanding
uncertainties that may be present to varying degrees in the numerous
studies relied upon and the even greater number of studies that the
Agency considered.
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\11\ Dudley, S. E. and Morriss, A. P. (2015), Will the
Occupational Safety and Health Administration's Proposed Standards
for Occupational Exposure to Respirable Crystalline Silica Reduce
Workplace Risk?. Rish Analysis, 35: 1191-1196. doi:10.1111/
risa.12341
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4. OSHA's Response to Comments on Significant Risk of Material
Impairment
OSHA received several comments pertaining to the Agency's
determination of a significant risk of material impairment of health
posed to workers exposed for a working life to the previous PELs.
Although many of these comments were supportive of OSHA's conclusions
regarding the significance of risk, others were critical or suggested
that OSHA has an obligation to further reduce the risk below that
estimated to remain at the revised PEL.
Referring to the previous PELs for respirable crystalline silica,
the AFL-CIO commented that "[w]orkers face a significant risk of harm
from silica exposure at the current permissible exposure limits," and
that "[t]here is overwhelming evidence in the record that exposure to
respirable crystalline silica poses a significant health risk to
workers" (Document ID 4204, pp. 10-11). The AFL-CIO noted that OSHA's
mortality risk estimates well exceeded the benchmark of 1/1,000 excess
risk over a working lifetime of exposure to the previous PELs, and also
highlighted the risks of silicosis morbidity (Document ID 4204, p. 13).
The AFL-CIO further pointed out that there is no cure for silicosis,
and quoted oral testimony from workers at the informal public hearings
demonstrating that "[s]ilica-related diseases are still destroying
workers' lives and livelihoods" (Document ID 4204, p. 19).
Both the UAW and the Building and Construction Trades Department
(BCTD) concurred with the AFL-CIO that the previous PEL needs to be
lowered to adequately protect workers. Referring to the previous PEL,
the BCTD stated that "[t]he record supports OSHA's determination that
exposures at the current PEL present a significant risk" (Document ID
4223, p. 6). Although supportive of OSHA's proposed standard, the UAW
also suggested the adoption of a PEL of 25 [micro]g/m\3\ or lower where
feasible (Document ID 2282, Attachment 3, p.1), noting that a PEL set
at this level "will significantly reduce workers' exposure to deadly
silica dust and prevent thousands of illnesses and deaths every year"
(Document ID 2282, Attachment 3, p. 25). Similarly, Charles Gordon, a
retired occupational safety and health attorney, commented that the
revised PEL "leaves a remaining risk of 97 deaths per 1,000 workers
from silicosis, lung cancer, and renal disease combined" (Document ID
4236, p. 2). Again, it should be noted that these risk estimates are
not additive because some individuals may suffer from multiple diseases
caused by exposure to silica. Instead, OSHA presents risk estimates for
each health endpoint.
As discussed above, OSHA acknowledges that there remains a
significant risk of material impairment of health at the revised PEL; a
further reduction in the PEL, however, is not currently technologically
feasible (see Section VII, Summary of the Final Economic Analysis and
Final Regulatory Flexibility Analysis, in which OSHA summarizes its
assessment of the technological feasibility of the revised PEL).
Despite this, the final PEL will provide a very substantial reduction
in the risk of material impairment of health to silica-exposed workers,
as described in the Benzene decision (Benzene, 448 U.S. at 642).
In contrast to the foregoing comments from labor groups contending
that OSHA would be setting the PEL too high if it made a final
determination to lower the preceding PELs to 50 [micro]g/m\3\, critical
comments came from industry groups including the American Chemistry
Council (ACC), which disagreed with OSHA's determination of a
significant risk of material impairment of health at the previous PELs.
The ACC stated, "OSHA's assessment of these risks is flawed, and its
conclusions that the risks are significant at a PEL of 100 [micro]g/
m\3\ and would be substantially reduced by lowering the PEL to 50
[micro]g/m\3\ are unsupported" (Document ID 4209, p. 12). The ACC then
asserted several "fundamental shortcomings" in OSHA's QRA on which
OSHA based its significant risk determination (Document ID 4209, pp.
16-17), including a variety of purported biases in the key studies on
which OSHA relied. OSHA addresses the ACC's concerns in detail in
Section V of this preamble dealing with the key studies relied upon by
the Agency for each health endpoint, as well as separate sections
addressing the issues of biases, causation, thresholds, the uncertainty
analysis, and the life table and exposure assumptions used in the QRA.
As more fully discussed in those sections, OSHA finds these concerns to
be unpersuasive. As discussed in Section V, the scientific community
and regulators in other advanced industrial societies agree on the need
for a PEL of at most 50 [micro]g/m\3\ based on demonstrated health
risks, and OSHA has used the best available evidence in the scientific
literature to estimate quantitative risks of silica-related illnesses
and thereby reach the same conclusion. OSHA's preliminary review of the
health effects literature and OSHA's preliminary QRA were, further,
examined by an independent, external peer review panel of
accomplished scientists, which lent credibility to the Agency's methods
and findings and led to some adjustments in the analysis that
strengthened OSHA's final risk assessment. There is, additionally,
widespread support for the Agency's methods and conclusions in the
rulemaking record. As such, OSHA is confident in its conclusion that
there is a significant risk of material impairment of health to workers
exposed to respirable crystalline silica at the levels of exposure
permitted under the previous PELs and under this final standard, and
finds no merit in broad assertions purporting to debunk this
conclusion.
In summary, as discussed throughout Section V and this final rule,
OSHA concludes, based on the best available evidence in the scientific
literature, that workers' exposure to respirable crystalline silica at
the previous PELs results in a clearly significant risk of material
impairment of health. The serious, and potentially fatal, health
effects suffered by exposed workers include silicosis, lung cancer,
NMRD, renal disease, and autoimmune effects. OSHA finds that the risk
is substantially decreased, though still significant, at the new PEL of
50 [micro]g/m\3\ and below, including at the new action level of 25
[micro]g/m\3\. The Agency is constrained, however, from lowering the
PEL further by its finding that a lower PEL would be infeasible in many
operations across several industries. Given the significant risks faced
by workers exposed to respirable crystalline silica under the
previously-existing exposure limits, OSHA believes that it is
imperative that it issue this final standard pursuant to its statutory
mandate under the OSH Act.
VII. Summary of the Final Economic Analysis and Final Regulatory
Flexibility Analysis
A. Introduction
OSHA's Final Economic Analysis and Final Regulatory Flexibility
Analysis (FEA) addresses issues related to the costs, benefits,
technological and economic feasibility, and the economic impacts
(including impacts on small entities) of this final respirable
crystalline silica rule and evaluates regulatory alternatives to the
final rule. Executive Orders 13563 and 12866 direct agencies to assess
all costs and benefits of available regulatory alternatives and, if
regulation is necessary, to select regulatory approaches that maximize
net benefits (including potential economic, environmental, and public
health and safety effects; distributive impacts; and equity). Executive
Order 13563 emphasized the importance of quantifying both costs and
benefits, of reducing costs, of harmonizing rules, and of promoting
flexibility. The full FEA has been placed in OSHA rulemaking docket
OSHA-2010-0034. This rule is an economically significant regulatory
action under Sec. 3(f)(1) of Executive Order 12866 and has been
reviewed by the Office of Information and Regulatory Affairs in the
Office of Management and Budget, as required by executive order.
The purpose of the FEA is to:
Identify the establishments and industries potentially
affected by the final rule;
Estimate current exposures and the technologically
feasible methods of controlling these exposures;
Estimate the benefits resulting from employers coming into
compliance with the final rule in terms of reductions in cases of
silicosis, lung cancer, other forms of chronic obstructive pulmonary
disease, and renal failure;
Evaluate the costs and economic impacts that
establishments in the regulated community will incur to achieve
compliance with the final rule;
Assess the economic feasibility of the final rule for
affected industries; and
Assess the impact of the final rule on small entities
through a Final Regulatory Flexibility Analysis (FRFA), to include an
evaluation of significant regulatory alternatives to the final rule
that OSHA has considered.
Significant Changes to the FEA Between the Proposed Standards and the
Final Standards
OSHA changed the FEA for several reasons:
Changes to the rule, summarized in Section I of this
preamble and discussed in detail in the Summary and Explanation;
Comments on the Preliminary Economic Analysis (PEA);
Updates of economic data; and
Recognition of errors in the PEA.
OSHA revised its technological and economic analysis in response to
these changes and to comments received on the NPRM. The FEA contains
some costs that were not included in the PEA and updates data to use
more recent data sources and, in some cases, revised methodologies.
Detailed discussions of these changes are included in the relevant
sections throughout the FEA.
The FEA contains the following chapters:
Chapter I. Introduction
Chapter II. Market Failure and the Need for Regulation
Chapter III. Profile of Affected Industries
Chapter IV. Technological Feasibility
Chapter V. Costs of Compliance
Chapter VI. Economic Feasibility Analysis and Regulatory Flexibility
Determination
Chapter VII. Benefits and Net Benefits
Chapter VIII. Regulatory Alternatives
Chapter IX. Final Regulatory Flexibility Analysis
Chapter X. Environmental Impacts
Table VII-1 provides a summary of OSHA's best estimate of the costs
and estimated benefits of the final rule using a discount rate of 3
percent. As shown, the final rule is estimated to prevent 642
fatalities and 918 silica-related illnesses annually once it is fully
effective, and the estimated cost of the rule is $1,030 million
annually. Also as shown in Table VII-1, the discounted monetized
benefits of the final rule are estimated to be $8.7 billion annually,
and the final rule is estimated to generate net benefits of $7.7
billion annually. Table VII-1 also presents the estimated costs and
estimated benefits of the final rule using a discount rate of 7
percent.
The remainder of this section (Section VII) of the preamble is
organized as follows:
B. Market Failure and the Need for Regulation
C. Profile of Affected Industries
D. Technological Feasibility
E. Costs of Compliance
F. Economic Feasibility Analysis and Regulatory Flexibility
Determination
G. Benefits and Net Benefits
H. Regulatory Alternatives
I. Final Regulatory Flexibility Analysis.
B. Market Failure and the Need for Regulation
Employees in work environments addressed by the final silica rule
are exposed to a variety of significant hazards that can and do cause
serious injury and death. As described in Chapter II of the FEA in
support of the final rule, OSHA concludes there is a failure of private
markets to protect workers from exposure to unnecessarily high levels
of respirable crystalline silica and that private markets, as well as
information dissemination programs, workers' compensation systems, and
tort liability options, each may fail to protect workers from silica
exposure, resulting in the need for a more protective OSHA silica rule.
After carefully weighing the various potential advantages and
disadvantages of using a regulatory approach to improve upon the
current situation, OSHA concludes that, in the case of silica exposure,
the final mandatory standards represent the best choice for reducing
the risks to employees. In addition, rulemaking is necessary in this
case in order to replace older existing standards with updated, clear,
and consistent health standards.
C. Profile of Affected Industries
Introduction
Chapter III of the FEA presents profile data for industries
potentially affected by the final silica rule. The discussion below
summarizes the findings in that chapter. As a first step, OSHA
identifies the North American Industrial Classification System (NAICS)
industries, both in general industry and maritime and in the
construction sector, with potential worker exposure to silica. Next,
OSHA provides summary statistics for the affected industries, including
the number of affected entities and establishments, the number of
workers whose exposure to silica could result in disease or death
("at-risk workers"), and the average revenue for affected entities
and establishments.\12\ Finally, OSHA presents silica exposure profiles
for at-risk workers. These data are presented by sector and job
category. Summary data are also provided for the number of workers in
each affected industry who are currently exposed above the final silica
PEL of 50 [mu]g/m\3\, as well as above an alternative PEL of 100 [mu]g/
m\3\ for economic analysis purposes.
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\12\ The Census Bureau defines an establishment as a single
physical location at which business is conducted or services or
industrial operations are performed. The Census Bureau defines a
business firm or entity as a business organization consisting of one
or more domestic establishments in the same state and industry that
were specified under common ownership or control. The firm and the
establishment are the same for single-establishment firms. For each
multi-establishment firm, establishments in the same industry within
a state will be counted as one firm; the firm employment and annual
payroll are summed from the associated establishments. (US Census
Bureau, Statistics of US Businesses, Definitions. 2015,
http://www.census.gov/econ/susb/definitions.html?cssp=SERP).
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The methodological basis for the industry and at-risk worker data
presented in this chapter comes from the PEA, the Eastern Research
Group (ERG) analysis supporting the PEA (2007a, 2007b, 2008a, and
2008b),\13\ and ERG's analytic support in preparing the FEA. The data
used in this chapter come from the rulemaking record (Docket OSHA-2010-
0034), the technological feasibility analyses presented in Chapter IV
of the FEA, and from OSHA (2016), which updated its earlier
spreadsheets to reflect the most recent industry data available. To do
so, ERG first matched the BLS Occupational Employment Statistics (OES)
survey occupational titles with the at-risk job categories, by NAICS
industry. ERG then calculated the percentages of production employment
represented by each at-risk job title within industry (see OSHA, 2016
for details on the calculation of employment percentages and the
mapping of at-risk job categorizations into OES occupations).\14\ ERG's
expertise for identifying the appropriate OES occupations and
calculating the employment percentages enabled OSHA to estimate the
number of employees in the at-risk job categories by NAICS industry
(Id.).
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\13\ Document ID, 1709, 1608, 1431, and 1365, respectively.
\14\ Production employment includes workers in building and
grounds maintenance; forestry, fishing, and farming; installation
and maintenance; construction; production; and material handling
occupations.
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In the NPRM and PEA, OSHA invited the public to submit additional
information and data that might help improve the accuracy and
usefulness of the preliminary industry profile; the profile presented
here and in Chapter III of the FEA reflects public comment.
Selection of NAICS Industries for Analysis
The technological feasibility analyses presented in Chapter IV of
the FEA identify the general industry and maritime sectors and the
construction activities potentially affected by the final silica
standard.
General Industry and Maritime
Employees engaged in various activities in general industry and
maritime routinely encounter crystalline silica as a molding material,
as an inert mineral additive, as a component of fluids used to
stimulate well production of oil or natural gas, as a refractory
material, as a sandblasting abrasive, or as a natural component of the
base materials with which they work. Some industries use various forms
of silica for multiple purposes. As a result, employers are faced with
the challenge of limiting worker exposure to silica in dozens of job
categories throughout the general industry and maritime sectors.
Job categories in general industry and maritime were selected for
analysis based on data from the technical industrial hygiene
literature, evidence from OSHA Special Emphasis Program (SEP) results,
and, in several cases, information from ERG site visit reports and
public comment submitted into the record. These data sources provided
evidence of silica exposures in numerous sectors. While the available
data are not entirely comprehensive, OSHA believes that silica
exposures in other sectors are quite limited.
The industry subsectors in the overall general industry and
maritime application groups that OSHA identified as being potentially
affected by the final silica standard are as follows:
Asphalt Paving Products
Asphalt Roofing Materials
Hydraulic Fracturing
Industries with Captive Foundries
Concrete Products
Cut Stone
Dental Equipment and Supplies
Dental Laboratories
Flat Glass
Iron Foundries
Jewelry
Mineral Processing
Mineral Wool
Nonferrous Sand Casting Foundries
Non-Sand Casting Foundries
Other Ferrous Sand Casting Foundries
Other Glass Products
Paint and Coatings
Porcelain Enameling
Pottery
Railroads
Ready-Mix Concrete
Refractories
Refractory Repair
Shipyards
Structural Clay
In some cases, affected industries presented in the technological
feasibility analysis have been disaggregated to facilitate the cost and
economic impact analysis. In particular, flat glass, mineral wool, and
other glass products are subsectors of the glass industry described in
Chapter IV, Section IV-9, of the FEA, and captive foundries,\15\ iron
foundries, nonferrous sand casting foundries, non-sand cast foundries,
and other ferrous sand casting foundries are subsectors of the
overall foundries industry presented in Chapter IV, Section IV-8, of
the FEA.
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\15\ Captive foundries include establishments in other
industries with foundry processes incidental to the primary products
manufactured. ERG (2008b, Document ID 1365) provides a discussion of
the methodological issues involved in estimating the number of
captive foundries and in identifying the industries in which they
are found. Since the 2008 ERG report, through comment in the public
record and the public hearings, OSHA has gained additional
information on the presence of captive foundries throughout general
industry.
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As described in ERG (2008b, Document ID 1365) and updated in OSHA
(2016), OSHA identified the six-digit NAICS codes for these subsectors
to develop a list of industries potentially affected by the final
silica standard. Table VII-2 presents the sectors listed above with
their corresponding six-digit NAICS industries. The NAICS codes and
associated industry definitions in the FEA are consistent with the 2012
NAICS edition.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
Construction
The construction sector is an integral part of the nation's
economy, accounting for approximately 4.5 percent of total private
sector employment. Establishments in this industry are involved in a
wide variety of activities, including land development and subdivision,
homebuilding, construction of nonresidential buildings and other
structures, heavy construction work (including roadways and bridges),
and a myriad of special trades such as plumbing, roofing, electrical,
excavation, and demolition work.
Construction activities were selected for analysis based on
historical data of recorded samples of construction worker exposures
from the OSHA Integrated Management Information System (IMIS) and the
National Institute for Occupational Safety and Health (NIOSH). In
addition, OSHA reviewed the industrial hygiene literature across the
full range of construction activities and focused on dusty operations
where silica sand was most likely to be fractured or abraded by work
operations. These physical processes have been found to cause the
silica exposures that pose the greatest risk of silicosis for workers.
The construction activities, by equipment or task, that OSHA
identified as being potentially affected by the final silica standard
are as follows:
Earth drilling
Heavy Equipment Operators and Ground Crew Laborers--I
(Abrading or fracturing silica containing materials or demolishing
concrete or masonry structures)
Heavy Equipment Operators and Ground Crew Laborers--II
(Grading and Excavating)
Hole Drillers Using Handheld or Stand-Mounted Drills
Jackhammers and Other Powered Handheld Chipping Tools
Masonry and Concrete Cutters Using Portable Saws--I (Handheld
power saws)
Masonry and Concrete Cutters Using Portable Saws--II (Handheld
power saws for cutting fiber-cement board)
Masonry and Concrete Cutters Using Portable Saws--III (Walk-
behind saws)
Masonry and Concrete Cutters Using Portable Saws--IV (Drivable
or ride-on concrete saws)
Masonry and Concrete Cutters Using Portable Saws--V (Rig-
mounted core saws or drills)
Masonry Cutters Using Stationary Saws
Millers Using Portable or Mobile Machines--I (Walk-behind
milling machines and floor grinders)
Millers Using Portable or Mobile Machines--II (Small drivable
milling machine (less than half-lane))
Millers Using Portable or Mobile Machines--III (Milling
machines (half-lane and larger with cuts of any depth on asphalt only
and for cuts of four inches in depth or less on any other substrate))
Rock and Concrete Drillers--I (Vehicle-mounted drilling rigs
for rock and concrete)
Rock and Concrete Drillers--II (Dowel drilling rigs for
concrete)
Mobile Crushing Machine Operators and Tenders
Tuckpointers and Grinders--I (Handheld grinders for mortar
removal (e.g., tuckpointing))
Tuckpointers and Grinders--II (Handheld grinders for uses
other than mortar removal)
As shown in OSHA (2016) and in Chapter IV of the FEA, these
construction activities occur in the following industries and
governmental bodies, accompanied by their four-digit NAICS codes: \16\
\17\
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\16\ ERG and OSHA used the four-digit NAICS codes for the
construction sector both because the BLS's Occupational Employment
Statistics survey only provides data at this level of detail ad
because, unlike the case in general industry and maritime, job
categories in the construction sector are task-specific, not
industry-specific. Furthermore, as far as economic impacts are
concerned, IRS data on profitability are reported only at the four-
digit NAICS code level of detail.
\17\ Some public employees in state and local governments are
exposed to elevated levels of respirable crystalline silica. These
exposures are included in the construction sector because they are
the result of construction activities.
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2361 Residential Building Construction
2362 Nonresidential Building Construction
2371 Utility System Construction
2372 Land Subdivision
2373 Highway, Street, and Bridge Construction
2379 Other Heavy and Civil Engineering Construction
2381 Foundation, Structure, and Building Exterior Contractors
2382 Building Equipment Contractors
2383 Building Finishing Contractors
2389 Other Specialty Trade Contractors
2211 Electric Utilities
9992 State Government
9993 Local Government
Characteristics of Affected Industries
Table VII-3 provides an overview of the industries and estimated
number of workers affected by the final rule. Included in Table VII-3
are summary statistics for each of the affected industries, subtotals
for construction and for general industry and maritime, and grand
totals for all affected industries combined.
The first five columns in Table VII-3 identify the NAICS code for
each industry in which workers are routinely exposed to respirable
crystalline silica and the name or title of the industry, followed by
the total number of entities, establishments, and employees for that
industry. Note that, while the industries are characterized by such
exposure, not every entity, establishment, and employee in these
affected industries engage in activities involving silica exposure.
The next three columns in Table VII-3 show, for each affected
industry, the number of entities and establishments in which workers
are actually exposed to silica and the total number of workers exposed
to silica. The number of affected establishments was set equal to the
total number of establishments in an industry (based on Census data)
unless the number of affected establishments would exceed the number of
affected employees in the industry. In that case, the number of
affected establishments in the industry was set equal to the number of
affected employees, and the number of affected entities in the industry
was reduced so as to maintain the same ratio of entities to
establishments in the industry.\18\
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\18\ OSHA determined that removing this assumption would have a
negligible impact on total costs and would reduce the cost and
economic impact on the average affected establishment or entity.
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BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
As shown in Table VII-3, OSHA estimates that a total of 652,600
entities (586,800 in construction; 65,900 in general industry and
maritime), 675,800 establishments (600,700 in construction; 75,100 in
general industry and maritime), and 2.3 million workers (2.0 million in
construction; 0.3 million in general industry and maritime) would be
affected by the final silica rule. Note that only 67 percent of the
entities and establishments, and about 21 percent of the workers in
affected industries, actually engage in activities involving silica
exposure.\19\
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\19\ It should be emphasized that these percentages vary
significantly depending on the industry sector and, within an
industry sector, depending on the NAICS industry. For example, about
35 percent of the workers in construction, but only 6 percent of
workers in general industry, actually engage in activities involving
silica exposure. As an example within construction, about 35 percent
of workers in highway, street, and bridge construction, but only 3
percent of workers in state and local governments, actually engage
in activities involving silica exposure.
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The ninth column in Table VII-3, with data only for construction,
shows for each affected NAICS construction industry the number of full-
time-equivalent (FTE) affected workers that corresponds to the total
number of affected construction workers in the previous column.\20\
This distinction is necessary because affected construction workers may
spend large amounts of time working on tasks with no risk of silica
exposure. As shown in Table VII-3, the 2.0 million affected workers in
construction converts to approximately 387,700 FTE affected workers. In
contrast, OSHA based its analysis of the affected workers in general
industry and maritime on the assumption that they were engaged full
time in activities with some silica exposure.
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\20\ FTE affected workers becomes a relevant variable in the
estimation of control costs in the construction industry. The reason
is that, consistent with the costing methodology, control costs
depend only on how many worker-days there are in which exposures are
above the PEL. These are the worker-days in which controls are
required. For the derivation of FTEs, see Tables IV-8 and IV-22 and
the associated text in ERG (2007a, Document ID 1709).
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The last three columns in Table VII-3 show combined total revenues
for all entities (not just affected entities) in each affected
industry, and the average revenue per entity and per establishment in
each affected industry. Because OSHA did not have data to distinguish
revenues for affected entities and establishments in any industry,
average revenue per entity and average revenue per affected entity (as
well as average revenue per establishment and average revenue per
affected establishment) are estimated to be equal in value.
Silica Exposure Profile of At-Risk Workers
The technological feasibility analyses presented in Chapter IV of
the FEA contain data and discussion of worker exposures to silica
throughout industry. Exposure profiles, by job category, were developed
from individual exposure measurements that were judged to be
substantive and to contain sufficient accompanying description to allow
interpretation of the circumstance of each measurement. The resulting
exposure profiles show the job categories with current overexposures to
silica and, thus, the workers for whom silica controls would be
implemented under the final rule.
Chapter IV of the FEA includes a section with a detailed
description of the methods used to develop the exposure profile and to
assess the technological feasibility of the final standard. The final
exposure profiles take the exposure data that were used for the same
purpose in OSHA's PEA and build upon them, using new data in the
rulemaking record. The sampling data that were used to identify the
affected industries and to develop the exposure profiles presented in
the PEA were obtained from a comprehensive review of the following
sources of information: OSHA compliance inspections conducted before
2011, OSHA contractor (ERG) site visits performed for this rulemaking,
NIOSH site visits, NIOSH Health Hazard Evaluation reports (HHEs),
published literature, submissions by individual companies or
associations and, in a few cases, data from analogous operations
(Document ID 1720, pp. IV-2-IV-3). The exposure profiles presented in
the PEA were updated for the FEA using exposure measurements from the
OSHA Information System (OIS) that were taken during compliance
inspections conducted between 2011 and 2014 (Document ID 3958). In
addition, exposure data submitted to the record by rulemaking
participants were used to update the exposure profiles. The criteria
used for determining whether to include exposure data in the exposure
profiles are described in Section IV-2--Methodology in Chapter IV of
the FEA. As explained there, some of the original data are no longer
used in the exposure profiles based on those selection or screening
criteria. OSHA considers the exposure data relied upon for its analysis
to be the best available evidence of baseline silica exposure
conditions.
Table VII-4 summarizes, from the exposure profiles, the total
number of workers at risk from silica exposure at any level, and the
distribution of 8-hour TWA respirable crystalline silica exposures by
job category for general industry and maritime sectors and for
construction activities. Exposures are grouped into the following
ranges: Less than 25 [mu]g/m\3\; >= 25 [mu]g/m\3\ and <= 50 [mu]g/m\3\;
> 50 [mu]g/m\3\ and <= 100 [mu]g/m\3\; > 100 [mu]g/m\3\ and <= 250
[mu]g/m\3\; and greater than 250 [mu]g/m\3\. These frequencies
represent the percentages of production employees in each job category
and sector currently exposed at levels within the indicated range.
Table VII-5 presents data by NAICS code--for each affected general,
maritime, and construction industry--on the estimated number of workers
currently at risk from silica exposure, as well as the estimated number
of workers at risk of silica exposure at or above 25 [mu]g/m\3\, above
50 [mu]g/m\3\, and above 100 [mu]g/m\3\. As shown, an estimated
1,249,250 workers (1,097,000 in construction; 152,300 in general
industry and maritime) currently have silica exposures at or above the
new action level of 25 [mu]g/m\3\; an estimated 948,100 workers
(847,700 in construction; 100,400 in general industry and maritime)
currently have silica exposures above the new PEL of 50 [mu]g/m\3\; and
an estimated 578,000 workers (519,200 in construction; 58,800 in
general industry and maritime) currently have silica exposures above
100 [mu]g/m\3\--an alternative PEL investigated by OSHA for economic
analysis purposes.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
D. Technological Feasibility
In Chapter IV of OSHA's FEA, OSHA assesses the technological
feasibility of the standard in all affected industry sectors and
application groups. The analysis presented in this chapter is organized
by industry sectors in general industry and maritime and by application
groups in the construction industry. Employee exposures were analyzed
at the operation, job category or task/activity level to the extent
that the necessary data were available.
OSHA collected exposure data to characterize current (baseline)
exposures and to identify the tasks, operations, and job categories for
which employers will need to either improve their process controls or
implement additional controls to reduce respirable crystalline silica
exposures to 50 [micro]g/m\3\ or below. In the few instances where
there were insufficient exposure data, OSHA used analogous operations
to characterize these operations.
The technological feasibility analysis informed OSHA's selection of
the rule's permissible exposure limit (PEL) of 50 [micro]g/m\3\
respirable crystalline silica, consistent with the requirements of the
Occupational Safety and Health Act ("OSH Act"), 29 U.S.C. 651 et seq.
Section 6(b)(5) of the OSH Act requires that OSHA "set the standard
which most adequately assures, to the extent feasible, on the basis of
the best available evidence, that no employee will suffer material
impairment of health or functional capacity" (29 U.S.C. 655(b)(5)). In
fulfilling this statutory directive, OSHA is guided by the legal
standard expressed by the Court of Appeals for the D.C. Circuit for
demonstrating the technological feasibility of reducing occupational
exposure to a hazardous substance:
OSHA must prove a reasonable possibility that the typical firm
will be able to develop and install engineering and work practice
controls that can meet the PEL in most of its operations....The
effect of such proof is to establish a presumption that industry can
meet the PEL without relying on respirators....Insufficient
proof of technological feasibility for a few isolated operations
within an industry, or even OSHA's concession that respirators will
be necessary in a few such operations, will not undermine this
general presumption in favor of feasibility. Rather, in such
operations firms will remain responsible for installing engineering
and work practice controls to the extent feasible, and for using
them to reduce...exposure as far as these controls can do so
(United Steelworkers of Am, AFL-CIO-CLC v. Marshall, 647 F.2d 1189,
1272 (D.C. Cir. 1980)).
Additionally, the D.C. Circuit explained that "[f]easibility of
compliance turns on whether exposure levels at or below [the PEL] can
be met in most operations most of the time..." (Am. Iron & Steel
Inst. v. OSHA, 939 F.2d 975, 990 (D.C. Cir. 1991)); (see Section II,
Pertinent Legal Authority).
Consistent with the legal standard described above, Chapter IV of
the FEA, which can be found at www.regulations.gov (docket OSHA-2010-
0034), describes OSHA's examination of the technological feasibility of
this rule on occupational exposure to respirable crystalline silica.
The chapter provides a description of the methodology and data used by
OSHA to analyze the technological feasibility of the standard, as well
as a discussion of the accuracy and reliability of current methods used
for the sampling and analysis of respirable crystalline silica. Chapter
IV contains OSHA's analyses, for 21 general industry sectors, 1
maritime sector, and 12 construction industry application groups, of
the technological feasibility of meeting the rule's requirements for
reducing exposures to silica. For each sector and application group,
OSHA addresses the extent to which the evidence in the record indicates
that engineering and work practice controls can reduce respirable
crystalline silica exposures to the PEL or below and maintain them at
that level. These individual technological feasibility analyses form
the basis for OSHA's overall finding that employees' exposures can be
reduced to the rule's PEL or below in most of the affected sectors'
operations. Throughout Chapter IV, OSHA describes and responds to
issues raised in the comments and testimony it received from interested
parties during the comment periods and public hearing OSHA held on the
proposed rule. The material below summarizes the detailed discussion
and presentation of OSHA's findings contained in Chapter IV of the FEA.
1. Methodology
As noted above, OSHA's technological feasibility analysis for this
rule largely involved describing engineering and work practice controls
that OSHA concludes can be expected to control respirable crystalline
silica exposures to the PEL or below. For this portion of the analysis,
OSHA relied on information and exposure measurements from many
different sources, including OSHA's inspection database (OSHA
Information System (OIS)), OSHA inspection reports, National Institute
of Occupational Safety and Health (NIOSH) reports, site visits by NIOSH
and OSHA's contractor, Eastern Research Group, Inc. (ERG), and
materials from other federal agencies, state agencies, labor
organizations, industry associations, and other groups. In addition,
OSHA reviewed studies from the published literature that evaluated the
effectiveness of engineering controls and work practices in order to
estimate the reductions from current, baseline exposures to silica that
can be achieved through wider or improved implementation of such
controls. Finally, OSHA considered the extensive testimony and numerous
comments regarding the feasibility of implementing engineering and work
practice controls, including circumstances that preclude the use of
controls in certain situations. In total, OSHA's feasibility analysis
is based on hundreds of sources of information in the record,
constituting one of the largest databases of information OSHA has used
to evaluate the feasibility of a health standard.
The technological feasibility chapter of the FEA describes the
industry sectors and application groups affected by the rule, and
identifies the sources of exposure to respirable crystalline silica for
each affected job category or task. The technological feasibility
analysis subdivides the general industry and maritime workplaces into
24 industry sectors.\21\ General industry sectors are identified
primarily based on the type of product manufactured (e.g., concrete
products, pottery, glass) or type of process used (e.g., foundries,
mineral processing, refractory repair). Where sufficiently detailed
information was available, the Agency further divided general industry
sectors into specific job categories on the basis of common factors
such as materials, work processes, equipment, and available exposure
control methods. OSHA notes that these job categories are intended to
represent job functions; actual job titles and responsibilities might
differ depending on the facility or industry practice.
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\21\ OSHA's technological feasibility analysis in the FEA is
divided into 22 sections, one for each of the general industry and
maritime sectors. However, separate technological feasibility
findings are made for three different foundry sectors (ferrous,
nonferrous, and non-sand casting foundries), making a total of 24
sectors for which separate analyses and findings are made (see Table
VII-8).
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For the construction industry, OSHA identified application groups
based on construction activities, tasks, or equipment that are commonly
recognized to create silica exposures; these tasks involve the use of
power tools (e.g., saws, drills, jackhammers) or larger equipment that
generates silica-containing dust (e.g., milling machines, rock and
concrete crushers, heavy equipment used in demolition or earthmoving).
The technological feasibility analysis for the construction industry
addresses 12 different application groups, defined by common
construction tasks or activities. OSHA organized construction workers
by application groups, rather than by industry sector or job titles,
because construction workers often perform multiple activities and job
titles do not always coincide with the sources of exposure; likewise,
the same equipment, tool or task may be called by different names throughout
construction and its various subspecialties. By organizing construction
activities this way, OSHA was able to create exposure profiles for employees
who perform the same activities in any segment of the construction
industry.
OSHA developed exposure profiles for each sector and application
group in order to characterize the baseline exposures and conditions
for each operation or task (see sections 4 and 5 of Chapter IV of the
FEA). The sample results included in the exposure profiles presented in
the Preliminary Economic Analysis (PEA) were obtained primarily from
OSHA compliance inspection reports and from NIOSH Health Hazard
Evaluation and control technology assessments. Samples were also
obtained from state plan case files, contractor site visits, published
literature and other sources. To ensure the exposure profiles were
based on the best available data, the exposure profiles were updated by
removing samples collected prior to 1990 (n = 290), leaving 2,512
samples from exposure profiles presented in the PEA from 1990 through
2007. More recent samples submitted by commenters during the rulemaking
(n = 153), primarily from 2009 through 2014, and samples obtained from
the OIS database (n = 699) from OSHA compliance inspections from 2011
to 2014 were added to exposure profiles, resulting in a total of 3,364
samples (2,483 for general industry and 881 for construction) in the
final exposure profiles. In total, these were obtained from 683 source
documents (see Table VII-6).
The exposure profiles characterize what OSHA considers to be the
baseline, or current, exposures for each job category or application
group. Where sufficient information on control measures was available,
the exposure profiles were subdivided into sample results with and
without controls and the controls were discussed in the baseline
conditions section. OSHA also discusses the sampling results associated
with specific controls in the baseline conditions section. In these
cases, the exposure profiles include exposures associated with a range
of controlled and uncontrolled exposure scenarios.
The exposure profiles include silica exposure data only for
employees in the United States. Information on international exposure
levels is occasionally referenced for perspective or in discussions of
control options. The rule covers three major polymorphs of crystalline
silica (i.e., quartz, cristobalite, and tridymite). However, the vast
majority of crystalline silica encountered by employees in the United
States is in the quartz form, and the terms crystalline silica and
quartz are often used interchangeably. Unless specifically indicated
otherwise, all silica exposure data, samples, and results discussed in
the technological feasibility analysis refer to personal breathing zone
(PBZ) measurements of respirable crystalline silica.
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\22\ OSHA silica Special Emphasis Program (SEP) inspection
reports are from inspections conducted by OSHA compliance safety and
health officers (CSHOs) under the silica National Emphasis Program
between 1993 and 2000.
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In general industry and maritime, the exposure profiles in the
technological feasibility analysis consist mainly of full-shift
samples, collected over periods of 360 minutes or more (see
Table IV-02-G in the FEA). By using this criterion, OSHA ensured that
the samples included in the exposure profiles were collected for at
least three-quarters of a typical 8-hour shift and therefore captured
most activities involving exposure to silica at which the employee
spends a substantial amount of time (Document ID 0845, pp. 38-40; see
Table IV-02-G in the FEA). Due to the routine nature of most job
activities in general industry, OSHA assumed that, for the partial
shift samples of less than 480 minutes, the same level of exposure as
measured during the sampled portion of the shift continued during the
smaller, unsampled portion. OSHA considers the 6-hour (360-minute)
sampling duration to be a reasonable criterion for including a sample
because it limits the extent of uncertainty about general industry/
maritime employees' true exposures, as no more than 25 percent of an 8-
hour shift would be unsampled. The sample result is therefore assumed
to be representative of an 8-hour time-weighted average (TWA).
Moreover, by relying primarily on sampling results 360 minutes or
greater, OSHA minimized the number of results included in the profiles
reported as below the limit of detection (LOD). The LOD for an
analytical method refers to the smallest mass of silica that can be
detected on the filter used to collect the air sample. Many
laboratories currently report an LOD of 10 [mu]g or lower for quartz
samples (Document ID 0666). As discussed in the Methodology section of
Chapter IV of the FEA, relying primarily on samples with a duration of
360 minutes or greater allows OSHA to draw the conclusion that any
sample results reported as non-detect for silica are at most 16 [mu]g/
m\3\, and well below the action level of 25 [mu]g/m\3\.
In the construction industry, approximately 43 percent of the
sampling data used in the exposure profiles also consisted of samples
collected over periods of 360 minutes or more. Most of the samples
(approximately 70%, or an additional 27%) in the construction industry
exposure profiles were collected over periods of 240 minutes or more
(see Table IV-02-G in the FEA). This allows OSHA to draw the conclusion
that any sample results reported as non-detect are below the action
level of 25 [mu]g/m\3\ (see Table IV-2-F in the FEA). Construction
workers typically spend their shifts working at multiple discrete tasks
and do not normally engage in any one task for the entire duration of a
shift; these varied tasks can include tasks that generate exposure to
respirable crystalline silica (Document ID 0677). Consequently, for
construction, OSHA assumed zero exposure during the unsampled portion
of the employee's shift unless there was evidence that silica exposures
continued for the entire shift. For example, if a sample measured an
average of 100 [mu]g/m\3\ over 240 minutes (4 hours), the result would
be recorded as 50 [mu]g/m\3\ TWA for a full 8-hour shift (480 minutes).
The Construction Industry Safety Coalition (CISC), comprised of 25
trade associations, was critical of several aspects of OSHA's
feasibility analysis. CISC objected to the assumption of zero exposure
for the unsampled portion of the work shift when calculating 8-hour
TWAs for the construction exposure profiles. It claimed that assuming
zero exposure underestimated TWA exposure levels when compared with the
alternative assumption used for general industry that the exposure
level measured during the sampled time period remained at the same
level during the unsampled period (Document ID 2319, pp. 21-25). While
there would be some uncertainty whichever assumption OSHA used, OSHA
concludes that the no-exposure assumption for unsampled portions of a
shift produces a more accurate result than the assumption of continued
exposure at the same level because of the widely-recognized differences
in work patterns between general industry and construction operations.
In general industry, most operations are at a fixed location and
involve manufacturing processes that remain relatively constant over a
work shift. Also, most of the sample durations in general industry were
360 minutes or longer, and therefore were more likely to be
representative of 8-hour TWA exposures. In contrast, construction work
is much more variable with respect to the location of the work site,
the number of different tasks performed, and the duration of tasks
performed. As stated above, tasks that generate exposure to respirable
crystalline silica in construction are often performed on an
intermittent basis (e.g., Document ID 0677).
OSHA's conclusion that the variability in sample durations for the
samples taken by OSHA in the construction industry more accurately
reflects the variability in exposure duration for these activities thus
comports with empirical experience. An assumption that exposure levels
during short-term tasks continued for the entire work shift would
substantially overestimate the actual 8-hour TWA exposures. The
Building and Construction Trades Department, AFL-CIO (BCTD) supported
OSHA's assumptions on work patterns, stating "OSHA correctly treated
the unsampled time as having `zero exposure' in its technological
feasibility assessment" (Document ID 4223, pp. 16-17). Its conclusion
was based on research performed by The Center to Protect Workers'
Rights, which developed a task-based exposure assessment model for the
construction industry that combines air sampling with task observations
and task durations in order to assess construction workers' exposure to
workplace hazards (Susi, et al., 2000, Document ID 4073, Attachment
8c). This model, when applied to masonry job sites, found that
employees spent much of their shifts performing non-silica-generating
tasks, both before and after the task involving silica exposure
(Document ID 4223, p. 16; 4073, Attachment 3a, pp. 1-2). BCTD indicated
that it was reasonable to assume these types of work patterns would be
similar for other construction tasks (Document ID 4223, pp. 16-17).
CISC also commented that OSHA did not account for the varying
amounts of crystalline silica that could exist in materials being
disturbed by employees, and that OSHA did not account for differences
in exposure results "due solely to what part of the country the
activity took place in" (Document ID 2319, pp. 26-27). OSHA has
determined that the sampling data relied on to establish baseline
silica exposures are representative of the range of silica content in
materials worked on by construction workers. Information on the percent
silica content of the respirable dust sampled was available for 588 of
the 881 samples used in the exposure profiles for construction tasks.
The silica content in these samples ranged from less than 1 percent
(non-detect) to 50 percent, with an average silica content of 9.1
percent. Thus, the sample results in the exposure profiles reflect the
range in the silica content of the respirable dust sampled by OSHA at
construction work sites. Similarly, the exposure profiles contain
exposure results from many different construction tasks taken in a
variety of locations around the country under different weather
conditions. Therefore, OSHA concludes that the exposure data used in
the exposure profiles are the best available evidence of actual
exposures in construction representing nationwide weather patterns, and
that these data reflect the broad range of silica exposures experienced
by employees in the construction industry.
Each section in the technical feasibility analysis presented in
Chapter IV of the FEA begins with descriptions of the manufacturing or
industrial process or construction activity that has potential exposure
to respirable crystalline silica, each job category or construction
task with exposure, and the major activities and sources of exposure.
Exposure profiles based on the available sampling information are then
presented and used to characterize the baseline exposures and
conditions for each operation or task (including exposure controls
currently in use). Based on the profile of baseline exposures, each
section next includes a description of additional engineering and work
practice controls that can be implemented to reduce employee exposures
to at least the rule's PEL. In addition, comments and other evidence in
the record relating to the description of the industry sector or
application group, the exposure profile and baseline conditions, and
the need for additional controls are discussed in each section.
Finally, based on the exposure profile and assessment of available
controls and other pertinent evidence in the record, each section
includes a feasibility determination for each operation, task, or
activity, including an overall feasibility determination where more
than one operation, task, or activity is addressed in the section.
In particular, OSHA evaluated information and testimony from the
record on the effectiveness of engineering and work practice controls
and either: (1) Identified controls that have been demonstrated to
reduce exposures to 50 [mu]g/m\3\ or below; or (2) evaluated the extent
to which baseline exposures would be reduced to 50 [mu]g/m\3\ or below
after applying the percent reduction in respirable silica or dust
exposure that has been demonstrated for a given control in the
operation or task under consideration or, in some cases, in analogous
circumstances. In some cases, the evidence demonstrates that most
exposures are already below the PEL. OSHA considers the evidence relied
on in making its feasibility determinations to be the best available
evidence on these issues.
For general industry and maritime, the additional engineering
controls and work practices identified by OSHA consist of equipment and
approaches that are widely available and are already used in many
applications. In some cases, the same technology can be transferred or
adapted to similar operations in other industry sectors covered under
the scope of this rule. Such controls and work practices include
implementing and maintaining local exhaust ventilation (LEV) systems
with dust collection systems (such as integrated material transfer
stations); enclosing a conveyor of silica-containing material or other
containment systems; worker isolation; process modifications; dust
suppression, systems such as water sprays; and housekeeping. In many
cases, a combination of controls is necessary to control exposures to
silica. In general industry, enclosed and ventilated equipment is often
already in use. For example, most paint and coating production
operations have switched from manual transfer of raw materials
containing crystalline silica to integrated bag dumping stations
equipped with well-ventilated enclosures and bag compactors (e.g.,
Document ID 0199, pp. 9-10; 0943, p. 87; 1607 p. 10-19; 1720, p. IV-
237). Where the evidence shows that a type of control like the material
transfer system is already being used in a sector covered by the rule,
OSHA is able to conclude that it can be used more widely in that sector
as an additional control or can be adapted to other industry sectors
for use during similar operations (see sections IV-15 Paint and
Coatings, IV-16 Porcelain Enameling, IV-11 Glass, and IV-05 Concrete
Products, of the FEA for additional information).
For construction, the exposure controls contained in Table 1 of the
rule consist primarily of water-based dust suppression systems, and LEV
systems that are integrated into hand tools and heavier equipment. As
shown in Chapter IV of the FEA, such systems are commercially available
from several vendors. In addition, equipment such as filtered,
ventilated booths or cabs and water-based systems for suppressing
fugitive dust generated by crushers and heavy equipment are available
to control exposures of construction workers to respirable crystalline
silica.
OSHA received numerous comments that disputed OSHA's preliminary
conclusion in the Notice of Proposed Rulemaking (NPRM) that a PEL of 50
[mu]g/m\3\ TWA was technologically feasible. These comments addressed
two general areas of concern: (1) Whether sampling and analytical
methods are sufficiently accurate to reliably measure respirable
crystalline silica concentrations at levels around the PEL and action
level; and (2) whether engineering and work practice controls can
reduce exposures from current levels to the lower levels required to
comply with the new standards. These issues and OSHA's technological
feasibility findings are discussed in the sections that follow. Much
more detail can be found in Chapter IV of the FEA.
2. Feasibility Determination for Sampling and Analytical Methods
As explained in Pertinent Legal Authority (Section II of this
preamble to the final rule), a finding that a standard is
technologically feasible requires that "provisions such as exposure
measurement requirements must also be technologically feasible" (see
Forging Indust. Ass'n v. Sec'y of Labor, 773 F.2d 1436, 1453 (4th Cir.
1985)). Thus, part of OSHA's technological feasibility assessment of a
new or revised health standard includes examining whether available
methods for measuring worker exposures have sufficient sensitivity and
precision to ensure that employers can evaluate compliance with the
standard and that workers have accurate information regarding their
exposure to hazardous substances. Consistent with the Supreme Court's
definition of "feasibility", OSHA finds that it is feasible to
measure worker exposures to a hazardous substance if achieving a
reasonable degree of sensitivity and precision with sampling and
analytical methods is "capable of being done" (Am. Textile Mfrs.
Inst., Inc. v. Donovan, 452 U.S. 490, 509-510 (1981)). OSHA also notes
that its analysis of the technological feasibility of the sampling and
analysis of respirable crystalline silica must be performed in
recognition of the fact that, as recognized by federal courts of
appeals, measurement error is inherent to sampling (Nat'l Min. Assoc.
v. Sec'y, U.S. Dep't of Labor, Nos. 14-11942, 14-12163, slip op. at 55
(11th Cir. Jan. 25, 2016); Am. Mining Cong. v. Marshall, 671 F.2d 1251,
1256 (10th Cir. 1982)). "Since there is no perfect sampling method,
the Secretary has discretion to adopt any sampling method that
approximates exposure with reasonable accuracy." Am. Mining Cong. v.
Marshall, 671 F.2d at 1256.
Since the late 1960s, exposures to respirable crystalline silica
(hereinafter referred to as "silica") have typically been measured
using personal respirable dust samplers coupled with laboratory
analysis of the crystalline silica content of the collected airborne
dust. The laboratory analysis is usually performed using X-ray
diffraction (XRD) or infrared spectroscopy (IR). A colorimetric method
of analysis that was used by a few laboratories has now been phased out
(Harper et al., 2014, Document ID 3998, Attachment 8, p. 1). OSHA has
successfully used XRD analysis since the early 1970s to enforce its
previous PELs for crystalline silica, which, for general industry, were
approximately equivalent to 100 micrograms per cubic meter ([mu]g/m\3\)
for quartz and 50 [mu]g/m\3\ for cristobalite and tridymite
(and within the range of about 250 [mu]g/m\3\ to 500 [mu]g/m\3\ for quartz in construction).
There are no other generally accepted methods for measuring
worker exposure to respirable crystalline silica.
The ability of current sampling and analytical methods to
accurately measure worker exposures to respirable crystalline silica
was a subject of much comment in the rulemaking record. In particular,
the Chamber of Commerce (Chamber) and American Chemistry Council (ACC)
submitted comments and testimony maintaining that existing methods do
not measure respirable crystalline silica exposures with sufficient
accuracy to support OSHA's proposal in the Notice of Proposed
Rulemaking to reduce the PEL to 50 [mu]g/m\3\ and establish the 25
[mu]g/m\3\ action level (Document ID 2285; 2288, pp. 17-21; 2307,
Attachment A, pp. 198-227; 4209, pp. 129-155; 3436, p. 8; 3456, pp. 18-
19; 3460; 3461; 3462; 4194, pp. 17-21). Similar views were expressed by
several other rulemaking participants (e.g., Document ID 2056, p. 1;
2085, p. 3; 2174; 2185, pp. 5-6; 2195, Attachment 1, p. 37; 2276, pp.
4-5; 2317, p. 2; 2379, Comments, pp. 28-30; 4224, pp. 11-14; 4232,
Attachment 1, pp. 3-24). Specifically, these commenters argue that, due
to several asserted sources of error, current sampling and analytical
methods do not meet the NIOSH accuracy criterion of 25
percent (NIOSH Manual of Analytical Methods, http://www.cdc.gov/niosh/docs/95-117/). Their arguments include: (1) That there is sampling
error attributed to bias against the particle-size selection criteria
that defines the performance of the samplers and variation in
performance between sampling devices; (2) that the accuracy and
precision of the analytical method at the low levels of silica that
would be collected at the revised PEL and action level is less than
that in the range of the previous PELs for silica, particularly in the
presence of interfering substances; and (3) variation between
laboratories analyzing comparable samples adds an unacceptable degree
of uncertainty. After considering all of the testimony and evidence in
the record, OSHA rejects these arguments and, as discussed below,
concludes that it is feasible to obtain measurements of respirable
crystalline silica at the final rule's PEL and action level with
reasonable accuracy.
OSHA is basing its conclusions on the following findings, which are
described in detail in this section. First, although there is variation
in the performance of respirable dust samplers, studies have
demonstrated that, for the majority of work settings, samplers will
perform with an acceptable level of bias (as defined by international
standards) as measured against internationally recognized particle-size
selection criteria that define respirable dust samplers. This means
that the respirable dust mass collected by the sampler will be
reasonably close to the mass that would be collected by an ideal
sampler that exactly matches the particle-size selection criteria. In
addition, OSHA finds that the measure of precision of the analytical
methods for samples collected at crystalline silica concentrations
equal to the revised PEL and action level is only somewhat higher
(i.e., somewhat less precise) than that for samples collected at
concentrations equal to the previous, higher PELs. Further, the
analytical methods can account for interferences such that, with few
exceptions, the sensitivity and precision of the method are not
significantly compromised. Studies of measurement variability between
laboratories, as determined by proficiency testing, have demonstrated a
significant decline in inter-laboratory variability in recent years.
Improvements in inter-laboratory variability have been attributed to
changes in proficiency test procedures as well as greater
standardization of analytical procedures among laboratories. Finally,
although measurement variability increases at low sample loads compared
to sample loads in the range of the former PELs, OSHA finds, based on
these studies, that the magnitude of this increase has also declined in
recent years.
Several rulemaking participants commented that OSHA's analysis of
the feasibility of sampling and analytical methods for crystalline
silica was well supported and sound (Document ID 2080, pp. 3-4; 2244,
p. 3; 2371, Attachment 1, p. 5; 3578, Tr. 941; 3586, Tr. 3284; 3577,
Tr. 851-852; 4214, pp. 12-13; 4223, pp. 30-33). Gregory Siwinski, CIH,
and Dr. Michael Lax, Medical Director of Upstate Medical University, an
occupational health clinical center, commented that current laboratory
methods can measure respirable crystalline silica at the 50 [mu]g/m\3\
PEL and 25 [mu]g/m\3\ action level, and that they have measured
exposures below the action level (Document ID 2244, p. 3). Dr. Celeste
Montforton of the George Washington School of Public Health testified
that "[i]ndustrial hygienists, company safety personnel, consultants,
and government inspectors have been conducting for decades workplace
sampling for respirable silica..." and that some governments, such
as Manitoba and British Columbia, are successfully collecting and
analyzing samples to determine compliance with their occupational
exposure limits of 25 [mu]g/m\3\ (Document ID 3577, Tr. 851-852). Dr.
Frank Mirer of the CUNY School of Public Health, formerly with the UAW
and on behalf of the AFL-CIO, stated that "[a]ir sampling is feasible
at 25 [mu]g/m\3\ and below for [a] full shift and even for part shift.
It was dealt with adequately in the OSHA proposal" (Document ID 3578,
Tr. 941).
The ACC, Chamber, and others base their argument that sampling and
analytical methods for respirable crystalline silica are insufficiently
precise on strict adherence to NIOSH's accuracy criterion of 25 percent at a 95-percent confidence level for chemical sampling
and analysis methods (http://www.cdc.gov/niosh/docs/95-117/). The ACC
pointed out that "OSHA standards typically reflect the NIOSH Accuracy
Criterion by requiring employers to use a method of monitoring and
analysis that has an accuracy of plus or minus 25 percent...," and
cited a number of OSHA standards where the Agency has included such
requirements (benzene, 29 CFR 1910.1028; lead (which requires a method
accuracy of 20%), 29 CFR 1910.1025; cadmium, 29 CFR
1910.1027; chromium (VI), 29 CFR 1910.1026) (Document ID 4209, p. 129).
However, the NIOSH accuracy criterion is not a hard, bright-line rule
in the sense that a sampling and analytical method must be rejected if
it fails to meet this level of accuracy, but is rather a goal or target
to be used in methods development. Where evidence has shown that a
method does not meet the accuracy criterion at the PEL or action level,
OSHA has stipulated a less rigorous level of accuracy to be achieved.
For example, OSHA's acrylonitrile standard requires use of a method
that is accurate to 35 percent at the PEL and 50 percent at the action level (29 CFR 1910.1045), and several
OSHA standards require that 35 percent accuracy be obtained
at the action level (arsenic, 29 CFR 1910.1018; ethylene oxide, 29 CFR
1910.1047; formaldehyde, 29 CFR 1910.1048; 1,3-butadiene, 29 CFR
1910.1051; methylene chloride, 29 CFR 1910.1052). As discussed below,
the precision of the sampling and analytical method for crystalline
silica, as currently implemented using OSHA Method ID-142 for X-ray
diffraction, is about 21 percent for quartz and
cristobalite.
In the remainder of this section, OSHA first describes available
respirable dust sampling methods and addresses comments and testimony
related to the performance and accuracy of respirable dust samplers.
Following that discussion, OSHA summarizes available analytical methods
for measuring crystalline silica in respirable dust samples and addresses
comments and evidence regarding analytical method precision, the presence
of interfering materials, and reported variability between laboratories
analyzing comparable samples.
a. Respirable Dust Sampling Devices
Respirable dust comprises particles small enough that, when
inhaled, they are capable of reaching the pulmonary region of the lung
where gas exchange takes place. Measurement of respirable dusts
requires the separation of particles by size to assess exposures to the
respirable fraction of airborne dusts. A variety of different
industrial hygiene sampling devices, such as cyclones and elutriators,
have been developed to separate the respirable fraction of airborne
dust from the non-respirable fraction. Cyclones are the most commonly
used size-selective sampling devices, or "samplers," for assessing
personal exposures to respirable dusts such as crystalline silica. The
current OSHA (ID-142, revised December 1996, Document ID 0946) and
NIOSH (Method 7500, Document ID 0901; Method 7602, 0903; Method 7603,
http://www.cdc.gov/niosh/docs/2003-154/pdfs/7603.pdf) methods for
sampling and analysis of crystalline silica specify the use of
cyclones.
Although respirable dust commonly refers to dust particles having
an aerodynamic diameter of 10 [mu]m (micrometer) or less, it is more
precisely defined by the collection efficiency of the respiratory
system as described by a particle collection efficiency model. These
models are often depicted by particle collection efficiency curves that
describe, for each particle size range, the mass fraction of particles
deposited in various parts of the respiratory system. These curves
serve as the "yardsticks" against which the performance of cyclone
samplers should be compared (Vincent, 2007, Document ID 1456). Figure
VII-1 below shows particle collection efficiency curves for two
particle size selection criteria: The criteria specified in the 1968
American Conference of Governmental Industrial Hygienists (ACGIH)
Threshold Limit Value (TLV) for respirable dust, which was the basis
for the prior OSHA general industry silica PEL, and an international
specification by the International Organization for Standardization
(ISO) and the Comit[eacute] Europ[eacute]en de Normalisation (CEN)
known as the ISO/CEN convention, which was adopted by ACGIH in 1994 and
is the basis for the definition of respirable crystalline silica in the
final rule. In addition to the curves, which cover the full range of
particle sizes that comprise respirable dust, particle size collection
criteria are also often described by their 50-percent respirable "cut
size" or "cut point." This is the aerodynamic diameter at which 50
percent of the particle mass is collected, i.e., the particle size that
the sampler can collect with 50-percent efficiency. Particles with a
diameter smaller than the 50-percent cut point are collected with an
efficiency greater than 50 percent, while larger-diameter particles are
collected with an efficiency less than 50 percent. The cut point for
the 1968 ACGIH specification is 3.5 [mu]m and for the ISO/CEN
convention is 4.0 [mu]m (Lippman, 2001, Document ID 1446, pp. 107,
113).
For most workplace conditions, the change in the criteria for
respirable dust in the final rule would theoretically increase the mass
of respirable dust collected over that measured under the previous
criteria by an amount that depends on the size distribution of airborne
particles in the workplace. Soderholm (1991, Document ID 1661) examined
these differences based on 31 aerosol size distributions measured in
various industrial workplaces (e.g., coal mine, lead smelter, brass
foundry, bakery, shielded metal arc [SMA] welding, spray painting,
pistol range) and determined the percentage increase in the mass of
respirable dust that would be collected under the ISO/CEN convention
over that which would be collected under the 1968 ACGIH criteria.
Soderholm concluded that, for all but three of the 31 size
distributions that were evaluated, the increased respirable dust mass
that would be collected using the ISO/CEN convention for respirable
dust instead of the 1968 ACGIH criteria would be less than 30 percent,
with most size distributions (25 out of the 31 examined, or 80 percent)
resulting in a difference of between 0 and 20 percent (Document ID
1661, pp. 248-249, Figure 1). In the PEA, OSHA stated its belief that
the magnitude of this effect does not outweigh the advantages of
adopting the ISO/CEN convention. In particular, most respirable dust
samplers on the market today are designed and calibrated to perform in
a manner that closely conforms to the international ISO/CEN convention.
Incorporating the ISO/CEN convention in the definition of
respirable crystalline silica will permit employers to use any sampling
device that conforms to the ISO/CEN convention. There are a variety of
these cyclone samplers on the market, such as the Dorr-Oliver, Higgins-
Dewell (HD), GK2.69, SIMPEDS, and SKC aluminum. In the PEA, OSHA
reviewed several studies demonstrating that these samplers collect
respirable particles with efficiencies that closely match the ISO/CEN
convention (Document ID 1720, pp. IV-21--IV-24). In addition to cyclone
samplers, there are also personal impactors available for use at flow
rates from 2 to 8 L/min that have been shown to conform closely with
the ISO/CEN convention (Document ID 1834, Attachment 1). Cyclones and
impactors both separate particles by size based on inertia. When an
airstream containing particles changes direction, smaller particles
remain suspended in the airstream and larger ones impact a surface and
are removed from the airstream. Cyclones employ a vortex to separate
particles centrifugally, while impactors use a laminar airflow around a
flat surface such that particles in the desired size range impact onto
the surface.
The current OSHA sampling method for crystalline silica, ID-142, is
the method used by OSHA to enforce the silica PELs and is used by some
employers as well. It specifies that a respirable sample be collected
by drawing air at 1.7 0.2 liters/minute (L/min) through a
Dorr-Oliver 10 millimeter (mm) nylon cyclone attached to a cassette
containing a 5-[mu]m pore-size, 37-mm diameter polyvinyl chloride (PVC)
filter (Document ID 0946). NIOSH sampling and analysis methods for
crystalline silica (Method 7500, Method 7602, Method 7603) have also
adopted the ISO/CEN convention with flow rate specifications of 1.7 L/
min for the Dorr-Oliver 10-mm nylon cyclone and 2.2 L/min for the HD
cyclone (Document ID 0901; 0903). Method 7500 also allows for the use
of an aluminum cyclone at 2.5 L/min. NIOSH is revising its respirable
dust method to include any sampler designed to meet the ISO/CEN
criteria (Document ID 3579, Tr. 218).
The devices discussed above, when used at the appropriate flow
rates, are capable of collecting a quantity of respirable crystalline
silica that exceeds the quantitative detection limit for quartz (the
principle form of crystalline silica) of 10 [mu]g for OSHA's XRD method
(Document ID 0946). For several scenarios based on using various
devices and sampling times (8-hour, 4-hour, and 1-hour samples), OSHA
calculated the amount of respirable quartz that would be collected at
quartz concentrations equal to the existing general industry PEL, the
proposed (and now final) rule's PEL, and the proposed (and now final)
rule's action level. As seen in Table IV.3-A, computations show that
the 10-mm nylon Dorr-Oliver operated at an optimized flow rate of 1.7
L/min, the aluminum cyclone operated at 2.5 L/min, the HD cyclone
operated at 2.2 L/min, and the GK2.69 operated at 4.2 L/min will all
collect enough quartz during an 8-hour or 4-hour sampling period to
meet or exceed the 10 [micro]g quartz limit of quantification for OSHA
Method ID-142. Therefore, each of the commercially available cyclones
is capable of collecting a sufficient quantity of quartz to exceed the
limit of quantification when airborne concentrations are at or below
the action level, provided that at least 4-hour air samples are taken.
Table VII-7 also shows that the samplers can collect enough silica to
meet the limit of quantification when the airborne respirable silica
concentration is below the action level of 25 [mu]g/m\3\, in one case
as low as 5 [mu]g/m\3\.
A comment from the National Rural Electric Cooperative Association
(NRECA) stated that the current OSHA and NIOSH analytical methods
require sampling to collect a minimum of 400 liters of air, and that at
the flow rates specified for current samplers, sampling would have to
be performed for approximately 2.5 to 4 hours; however, this is
considerably longer than most construction tasks performed in
electrical transmission and distribution work, which tend to last 2
hours or less (Document ID 2365, pp. 2, 6-7). OSHA does not view this
discrepancy to be a problem. The minimum sampling times indicated in
the OSHA and NIOSH methods contemplate that exposure occurs over most
of the work shift. Construction operations frequently involve shorter-
term tasks after which there is no further exposure to respirable
crystalline silica. In those situations, OSHA often does not itself
continue sampling during inspections and does not expect employers to
continue sampling when there is no exposure to silica, and considers
the sampling result that is obtained from shorter-term task sampling to
be sufficient to represent a worker's 8-hour time-weighted-average
(TWA) exposure, which can be calculated assuming no exposure for the
period of the shift that is not sampled. If the airborne concentration
of silica for the task is low, the sampling result would likely be
below the limit of quantification. In that case, it would be safe for
the employer to assume that the exposure is below the action level.
Transition to ISO-CEN Criteria for Samplers
In the final rule, OSHA is adopting the ISO/CEN particle size-
selective criteria for respirable dust samplers used to measure
exposures to respirable crystalline silica. Under the ISO/CEN
convention, samplers should collect 50 percent of the mass of particles
that are 4 [mu]m in diameter (referred to as the cut point), with
smaller particles being collected at higher efficiency and larger
particles being collected at lower efficiency. Particles greater than
10 [mu]m in diameter, which are not considered to be respirable, are to
be excluded from the sample based on the ISO/CEN convention (Document
ID 1446, pp. 112-113).
Several rulemaking participants supported OSHA's proposed adoption
of the ISO/CEN criteria for respirable dust samplers (Document ID 1730;
1969; 3576, Tr. 290; 3579, Tr. 218-219; 4233, p. 4). For example, a
representative of SKC, Inc., which manufactures samplers used to
collect respirable crystalline silica, stated that:
Adoption of the ISO/CEN performance standard for respirable dust
samplers by OSHA will bring the U.S. regulatory standards in line
with standards/guidelines established by other occupational health
and safety agencies, regulatory bodies, and scientific consensus
organizations around the world. It will also align OSHA performance
criteria for respirable dust samplers to that of NIOSH (Document ID
1730, pp. 1-2).
As discussed above, OSHA's previous (and currently enforceable)
general industry PEL for crystalline silica was based on a 1968 ACGIH
definition, which specified a model with a cut point of 3.5 [mu]m.
Based on available studies conducted over 40 years ago, the Dorr-Oliver
10-mm cyclone was thought to perform closely to this specification. As
such, it is the sampling device specified in OSHA's respirable dust
sampling and analytical methods, including Method ID-142 for respirable
crystalline silica (Document ID 0946). For most sizes of respirable
particles, the ISO/CEN convention specifies a greater efficiency in
particle collection than does the 1968 ACGIH model; consequently,
samplers designed to meet the ISO/CEN convention will capture somewhat
greater mass of airborne particle than would a sampler designed to the
1968 ACGIH model, with the magnitude of the increased mass dependent on
the distribution of particle sizes in the air. For most particle size
distributions encountered in workplaces, the increase in dust mass
theoretically collected under the ISO/CEN convention compared to the
ACGIH model would be 25 percent or less (Soderholm, 1991, Document ID
1661).
Several rulemaking participants commented that moving from the 1968
ACGIH model to the ISO/CEN convention effectively decreased the PEL and
action level below the levels intended, since more dust would be
collected by samplers that conform to the ISO/CEN convention than by
those that conform to the 1968 ACGIH model
(Document ID 2174; 2195, p. 30; 2285, pp. 3-4; 2307, Attachments
10, p. 19, and 12, p. 3; 2317, p. 2; 3456, p. 10; 4194, pp. 15-16). For
example, the Chamber commented that adopting the ISO/CEN specification
"can result in citations for over exposure to quartz dust where none
would have been issued prior to the adoption of this convention"
(Document ID 2288, p. 16). OSHA disagrees with this assessment because,
based on more recent evaluations (Bartley et al., 1994, Document ID
1438, Attachment 2; Lee et al., 2010, 3616; 2012, 3615), the Dorr-
Oliver 10-mm cyclone that has been used by the Agency for enforcement
of respirable dust standards for decades has been found to perform
reasonably closely (i.e., with an acceptable level of bias) to the ISO/
CEN specification when operated at the 1.7 L/min flow rate specified by
OSHA's existing method. Consequently, OSHA and employers can continue
to use the Dorr-Oliver cyclone to evaluate compliance against the final
PEL of 50 [mu]g/m\3\ without having to change equipment or procedures,
and thus would not be collecting a greater quantity of dust than
before. Furthermore, OSHA notes that other ISO/CEN-compliant samplers,
such as the SKC 10-mm aluminum cyclone and the HD cyclone specified in
the NIOSH Method 7500, are already widely used by investigators and
employers to evaluate exposures to respirable crystalline silica
against benchmark standards. Therefore, the change from the ACGIH
convention to the ISO/CEN convention is more a continuation of the
status quo than a drastic change from prior practice.
Other rulemaking participants argued that moving to the ISO/CEN
convention effectively invalidates OSHA's risk and feasibility analyses
since the exposure data that underlie these analyses were obtained
using devices conforming to the 1968 ACGIH specification. For example,
Thomas Hall, testifying for the Chamber, stated that moving to the ISO/
CEN convention "would produce a difference in [current] exposure
results from...historical measurements that have been used in the
risk assessments" (Document ID 3576, Tr. 435). Similarly, in its pre-
hearing comments, the ACC argued that:
When OSHA conducted technological feasibility studies for
attaining the proposed 50 [mu]g/m\3\ PEL, the Agency based its
decisions on samples collected using the current ACGIH method, not
the proposed ISO/CEN method. Thus, the switch to the ISO/CEN
definition will have two impacts on feasibility. First, it will add
uncertainty regarding OSHA's technological feasibility determination
because greater reductions in exposure will be required to achieve a
50 [mu]g/m\3\ PEL measured by the ISO/CEN definition than by the
ACGIH definition that OSHA applied. Second, OSHA's use of the ACGIH
definition to estimate compliance costs causes the Agency to
underestimate the costs of achieving the 50 [mu]g/m\3\ PEL because
OSHA did not account for the additional workers whose exposures
would exceed the proposed PEL under the ISO/CEN definition but who
would be exposed below the proposed PEL if measured under the ACGIH
definition (Document ID 2307, Attachment 8, p. 9).
OSHA rejects these arguments for the following reasons. First, with
respect to the risk information relied on by the Agency, exposure data
used in the various studies were collected from employer records
reflecting use of several different methods. Some studies estimated
worker exposures to silica from particle counts, for which the sampling
method using impingers does not strictly conform to either the ACGIH or
ISO/CEN conventions (e.g., Rice et al., Document ID 1118; Park et al.,
Document ID 0405; Attfield and Costello, Document ID 0285; Hughes et
al., Document ID 1060). Other studies used measurements taken using
cyclone samplers and modern gravimetric methods of silica analysis
(e.g., Rice et al. and Park et al., data obtained from cyclone pre-
separator up through 1988, Document ID 1118, 0405; Hughes et al., data
from 10-mm nylon cyclone through 1998, Document ID 1060). OSHA believes
it likely that exposure data collected using cyclones in these studies
likely conformed to the ISO/CEN specification since flow rates
recommended in the OSHA and NIOSH methods were most likely used. The
studies by Miller and MacCalman (Document ID 1097) and by Buchanan et
al. (Document ID 0306) used exposure measurements made with the MRE
113A dust sampler, which does conform reasonably well with the ISO/CEN
specification (Gorner et al., Document ID 1457, p. 47). The studies by
Chen et al. (2001, Document ID 0332; 2005, Document ID 0985) estimated
worker exposures to silica from total dust measurements that were
converted to respirable silica measurements from side-by-side
comparisons of the total dust sampling method with samples taken using
a Dorr-Oliver cyclone operated at 1.7 L/min, which is consistent with
the ISO/CEN convention (see Section V, Health Effects, of this preamble
and OSHA's Preliminary Review of Health Effects Literature and
Preliminary Quantitative Risk Assessment, Document ID 1711). Thus, it
is simply not the case that the exposure assessments conducted for
these studies necessarily reflect results from dust samples collected
with a device conforming to the 1968 ACGIH particle size-selective
criteria, and OSHA finds that no adjustment of OSHA's risk estimates to
reflect exposure measurements consistent with the ISO/CEN convention is
warranted.
Second, with respect to the feasibility analysis, OSHA relied on
exposure data and constructed exposure profiles based principally on
measurements made by compliance officers using the Dorr-Oliver cyclone
operated at 1.7 L/min, as the Agency has done since Method ID-142 was
developed in 1981, well before the 1990 cut-off date for data used to
construct the exposure profiles. As explained earlier in the section,
recent research shows that the Dorr-Oliver cyclone operated at this
flow rate performs in a manner consistent with the ISO/CEN
specification. Other data relied on by OSHA comes from investigations
and studies conducted by NIOSH and others who used various cyclones
that conform to the ISO/CEN specification. Thus, OSHA finds that the
exposure profiles being relied on to evaluate feasibility and costs of
compliance do not reflect sample results obtained using the 1968 ACGIH
model. Instead, the vast majority of sample results relied upon were
collected in a manner consistent with the requirements of the final
rule. NIOSH supported this assessment, stating that, given the Dorr-
Oliver sampler operated at a flow rate of 1.7 L/min conforms closely to
the ISO/CEN convention, "there is continuation with historic exposure
data" (Document ID 4233, p. 4). For these reasons, OSHA finds that it
is appropriate to rely on the feasibility and cost analyses and
underlying exposure data without adjustment to account for the final
rule's adoption of the ISO/CEN specification for respirable dust
samplers.
Sampling Error
Several commenters raised issues concerning the accuracy of
respirable dust samplers in relation to the ISO/CEN criteria, asserting
that sampling respirable dust is uncertain and inaccurate, and that
there are numerous sources of error. Chief among these were Dr. Thomas
Hall of Industrial Hygiene Specialty Resources, LLC, testifying for the
Chamber, and Paul K. Scott of ChemRisk, testifying for the ACC.
The Chamber's witnesses and others referenced studies showing that
all samplers were biased against the ISO/CEN particle-size selection
convention. This means that the sampler would collect more or less mass
of respirable particulate than would an ideal sampler that exactly
conforms to the ISO/CEN convention. OSHA discussed this issue in the PEA,
noting that most samplers tend to over-sample smaller particles and
under-sample larger particles, compared to the ISO/CEN convention,
at their optimized flow rates. This means that, for particle size
distributions dominated by smaller particles, the sampler will collect
more mass than would be predicted from an ideal sampler that exactly
conforms to the ISO/CEN convention. For particle size distributions
dominated by larger particles in the respirable range, less
mass would be collected than predicted. In the PEA, OSHA evaluated
several studies that showed that several cyclone samplers exhibited a
bias of 10 percent or less for most particle size distributions
encountered in the workplace. Some of these studies found biases as
high as 20 percent but only for particle size distributions
having a large mass median aerodynamic diameter (MMAD) (i.e., 20
[micro]m or larger) and narrow distribution of particle sizes (i.e., a
geometric standard deviation (GSD) of 2 or less) (Document ID 1720, pp.
IV-21--IV-24). Such particle size distributions are infrequently seen
in the workplace; for well-controlled environments, Frank Hearl of
NIOSH testified that the GSD for typical particle size distributions
would be about 2 (Document ID 3579, Tr. 187). Dr. Hall (Document ID
3576, Tr. 502) testified, similarly, that it would be around 1.8 to 3
for well-controlled environments and higher for uncontrolled
environments (see also Liden and Kenny, 1993, Document ID 1450, p. 390,
Figure 5; Soderholm, 1991,1661, p. 249, Figure 1). Furthermore, a
particle size distribution with a large MMAD and small GSD would
contain only a very small percentage (< 10%) of respirable dust that
would be collected by a sampler optimized to the ISO/CEN criteria
(Soderholm, 1991, Document ID 1661, p. 249, Figure 2). According to
Liden and Kenny (1993), "samplers will perform reasonably well
providing the absolute bias in sampling is kept to within 10 percent .
. . this aim can be achieved...over the majority of size
distributions likely to be found in field sampling" (Document ID 1450,
p. 390).
Dr. Hall commented that "sampling results differ depending on the
choice of sampler used" and that published evaluations have shown that
they "have different collection efficiencies, specifically with
respect to particle collection in aerosol clouds with large [MMADs
greater than] 10 [mu]m" (Document ID 2285, p. 16). He cited the work
of Gorner et al. (2001, Document ID 1457), who noted that the cut
points achieved by different samplers varied considerably and that flow
rates were optimized to bring their respective cut points closer to the
ISO/CEN convention, as evidence that commercial samplers do not provide
consistently similar results. However, OSHA interprets the findings of
Gorner et al. as actually providing evidence of samplers' consistency
with the ISO/CEN convention for most particle size distributions
encountered in the workplace. This study, which was reviewed in OSHA's
PEA, evaluated 15 respirable dust samplers, most of them cyclones,
against 175 different aerosol size distributions and evaluated the bias
and accuracy of sampler performance against the ISO/CEN convention.\23\
Gorner et al. found that most of the samplers they tested met the
international criteria for acceptable bias and accuracy (described by
Bartley et al., 1994, Document ID 1438, Attachment 2 and Gorner et al.,
2001, 1457); under those criteria, bias is not to exceed 10 percent and
inaccuracy is not to exceed 30 percent for most of the size
distributions tested (Document ID 1457, pp. 49, 52; Document ID 1438,
Attachment 2, p. 254). Gorner et al. concluded that the samplers "are
therefore suitable for sampling aerosols within a wide range of
particle size distributions" (Document ID 1457, p. 52). Gorner et al.
also stated that sampler performance should be evaluated by examining
bias and accuracy rather than simply comparing cut points and slopes
against the ISO/CEN convention (Document ID 1457, p. 50), as Dr. Hall
did in his comments.
---------------------------------------------------------------------------
\23\ Bias means the difference in particle mass collected by a
sampler as compared to the mass that would be collected by a
hypothetical ideal sampler that exactly matched the ISO/CEN
convention. Accuracy includes bias and other sources of error
related to the testing procedure (e.g., errors in flow rate and
particle mass analysis)(Document ID 1457, p. 49).
---------------------------------------------------------------------------
The ACC's witness, Mr. Scott, noted several potential sources of
sampling error in addition to the conventional 5-percent pump flow rate
error that is included in OSHA's estimate of sampling and analytical
error (SAE, discussed further in Section IV-3.2.4--Precision of
Measurement). These included variation in performance of the same
cyclone tested multiple times (estimated at 6 percent) and variation
between different cyclones tested in the same environment (estimated at
5 percent) (Document ID 2308, Attachment 6, pp. 7-8). Based on
published estimates of the magnitude of these kinds of errors, Mr.
Scott estimated a total sampling error of 9.3 percent after factoring
in pump flow rate error, inter-sampler error, and intra-sampler error;
this would increase the SAE by 4 percent, for example, from 15 to 19
percent at 50 [mu]g/m\3\ (Document ID 2308, pp. 8-9). This means that,
if all sampler error were factored into the SAE, an employer would be
considered out of compliance with the PEL for an exposure exceeding
59.5 [micro]g/m\3\, rather than at 57.5 [micro]g/m\3\ if only pump
error were considered, a difference of only 2 [micro]g/m\3\ in silica
concentration. OSHA therefore concludes that intra- and inter-sampler
error of the types described by Mr. Scott do not materially change how
OSHA would enforce, or how employers should evaluate, compliance with
the final rule PEL.
As described above, many different respirable dust samplers have
been evaluated against the ISO/CEN convention for different particle
size distributions and, in general, these biases are small for the vast
majority of particle size distributions encountered in the workplace.
OSHA concludes that Mr. Scott's estimate likely overstates the true
total sampling error somewhat because the measurements of sampler bias
against the ISO/CEN criteria involve accurately measuring and
maintaining consistent pump flow rates during the testing of the
samplers; therefore, adding pump flow rate error to estimates of inter-
and intra-sampler measurement error is redundant. Furthermore, if an
employer relies on a single type of cyclone sampler, as is OSHA's
practice, there would be no inter-sampler variability between different
field samples. If an employer is concerned about this magnitude of
uncertainty, he or she can choose simply to use the same sampling
device as OSHA (i.e., the Dorr-Oliver cyclone operated at a flow rate
of 1.7 L/min, as specified in Method ID-142) and avoid any potential
measurement uncertainties associated with use of different sampling
devices.
The American Foundry Society (AFS) commented that the ASTM Standard
D4532 for respirable dust sampling includes errors for sampling,
weighing, and bias, none of which is included in OSHA's pump flow rate
error (Document ID 2379, p. 29). This ASTM standard describes
procedures for sampling respirable dust using a 10-mm cyclone, HD
cyclone, or aluminum cyclone in a manner identical to that prescribed
in the OSHA and NIOSH methods for sampling and analysis of silica.
Thus, the kinds of errors identified by AFS are the same as those
reflected in Mr. Scott's testimony described above, which, as OSHA has
shown, do not result in substantial uncertainties in exposure
measurement.
OSHA further observes that the kinds of sampling errors described
by rulemaking participants are independent of where the PEL is
established and are not unique to silica; these biases have existed
since OSHA began using the Dorr-Oliver cyclone to enforce the previous
PELs for crystalline silica, as well as many other respirable dust
standards, over 40 years ago. OSHA also believes that sampling error
within the range quantified by Mr. Scott would be unlikely to change
how an employer makes risk management decisions based on monitoring
results. One Chamber witness, Gerhard Knutson, President of Knutson
Ventilation, testified that the type of cyclone used to obtain exposure
measurements for crystalline silica was not typically a consideration
in designing industrial ventilation systems (Document ID 3576, Tr. 521-
522). Dr. Hall, another Chamber witness, also testified that he has
used all three sampling devices listed in the NIOSH Method 7500 and has
not historically made a distinction between them, though he might make
different decisions today based on the aerosol size distribution
encountered in a particular workplace (Document ID 3576, Tr. 522-523).
In his pre-hearing submission, Dr. Hall cited the Gorner et al. (2001,
Document ID 1457) study as recommending that "rough knowledge of the
aerosol size distribution can guide the choice of an appropriate
sampling technique" (Document ID 2285, p. 8). OSHA concludes it
unlikely that, in most instances, it is necessary to obtain such data
to minimize sampling bias for risk management purposes, given the
overall magnitude of the bias as estimated by Mr. Scott (i.e., an error
of less than 10 percent).
High Flow Samplers
OSHA's PEA also described high-flow samplers, in particular the
GK2.69 from BGI, Inc., which is run at a flow rate of 4.2 L/min in
contrast to 1.7 L/min for the Dorr-Oliver and 2.5 L/min for the
aluminum cyclone. High-flow devices such as this permit a greater
amount of dust to be collected in low-dust environments, thus improving
sensitivity and making it more likely that the amount of silica
collected will fall within the range validated by current analytical
methods. For example, a Dorr-Oliver run at 1.7 L/min where the silica
concentration is 50 [mu]g/m\3\ would collect 41 [mu]g of silica over 8
hours, compared to the GK2.69 run at 4.2 L/min, which would collect 101
[mu]g of silica (see Table IV.3-A), well within the validation range of
the OSHA method (i.e., the range over which precision is determined, 50
to 160 [mu]g) (Document ID 0946, p. 1). Several rulemaking participants
supported OSHA's proposal to permit use of high-flow samplers that
conform to the ISO/CEN convention (Document ID 2256, Attachment 3, p.
12; 3578, Tr. 941; 3586, Tr. 3286-3287; 4233, p. 4). For example,
William Walsh, representing the American Industrial Hygiene Association
(AIHA) Laboratory Accreditation Programs, stated that he could measure
concentrations of silica at the 25 [mu]g action level with sufficient
precision by using a high-flow device (Document ID 3586, Tr. 3287).
The performance of high-flow samplers has been extensively studied,
particularly by Lee et al. (2010, Document ID 3616; 2012, 3615), Stacey
et al. (2013, Document ID 3618), and Kenny and Gussman (1997, Document
ID 1444). The Kenny and Gussman study, which was reviewed in OSHA's
PEA, found the GK2.69 had good agreement with the ISO/CEN convention at
the 4.2 L/min flow rate, with a cut point of 4.2 [mu]m and a collection
efficiency curve that was steeper than the ISO/CEN (i.e., it was more
efficient for smaller particles and less so for larger particles). For
particle size distributions up to an MMAD of 25 [mu]m and GSD of 1.5 to
3.5, bias against the ISO/CEN convention was generally between +5 and -
10 percent. Bias was greater (-20 percent) for particle size
distributions having an MMAD above 10 [mu]m and a low GSD which,
according to the authors, are not likely to be encountered (Document ID
1444, p. 687, Figure 7).
The Lee et al. (2010, Document ID 3616; 2012, 3615) and Stacey
(2013, Document ID 3618) studies of high-flow sampler performance are
the product of a collaborative effort between NIOSH and the United
Kingdom's Health and Safety Executive (HSE) that examined the
performance of three high-flow samplers; these were the GK2.69, the
CIP10-R (Arelco ARC, France), and the FSP10 (GSA, Germany). The FSP10
runs at a flow rate of 10 L/min and the combination of large cyclone
and heavy-duty pump may be burdensome for workers to wear. The CIP-10
also runs at 10 L/min and is much smaller and lighter, but uses a
collection technology different from cyclones, which may be unfamiliar
to users. According to NIOSH, cyclones operating around 4 L/min "offer
a current compromise" for obtaining higher flow rates without the need
to use larger personal samplers that may be difficult for workers to
wear (Document ID 2177, Attachment B, p. 13; 3579, Tr. 163)." For this
reason, OSHA's review of these studies focuses on the performance of
the GK2.69 cyclone.
Lee et al. (2010, Document ID 3616) tested the GK2.69 against 11
sizes of monodisperse aerosol and found that, at the 4.2 L/min flow
rate, the estimated bias against the ISO/CEN convention was positive
for all particle size distributions (i.e., the sampler collected
greater mass of particulate than would be predicted from an ideal
sampler that exactly conformed to ISO/CEN), with a 10-percent
efficiency for collecting 10 [mu]m particles, compared to 1 percent for
the ISO/CEN convention. The authors estimated a bias of +40 percent for
a particle size distribution having a MMAD of 27.5 [mu]m. However,
adjustment of the flow rate to 4.4 L/min resulted in biases of less
than 20 percent for most particle size distributions and the collection
efficiency for 10 [mu]m particles was much closer to the ISO/CEN
convention (2.5 percent compared to 1 percent). The authors concluded
that, at the higher flow rate, the GK2.69 cyclone met the international
standard for sampler conformity to relevant particle collection
conventions (European Committee for Standardization, EN 13205, cited in
Lee et al., 2010, Document ID 3616), and would provide relatively
unbiased measurements of respirable crystalline silica (Document ID
3616, pp. 706, 708, Figure 5(a)).
Lee et al. (2012, Document ID 3615) performed a similar evaluation
of the same samplers using coal dust but included analysis of
crystalline silica by both XRD and IR. The GK2.69 runs at a flow rate
of 4.4 L/min collected somewhat more respirable dust and crystalline
silica than would be predicted from differences in flow rates, compared
to the 10-mm nylon cyclone, but nearly the same as the Higgins-Dewell
cyclone. The authors found that the GK2.69 "showed non-significant
difference in performance compared to the low-flow rate samplers"
(Document ID 3615, p. 422), and that "the increased mass of quartz
collected with high-flow rate samplers would provide precise analytical
results (i.e., significantly above the limit of detection and/or the
limit of quantification) compared to the mass collected with low-flow
rate samplers, especially in environments with low concentrations of
quartz..." (Document ID 3615, p. 413). Lee et al. concluded that
"[a]ll samplers met the [EN 13205] requirements for accuracy for
sampling the ISO respirable convention" (Document ID 3615, p. 424).
Stacey et al. (2013, Document ID 3618) used Arizona road dust
aerosols to evaluate the performance of high-flow samplers against the Safety In
Mines Personal Dust Sampler (SIMPEDS), which is the low-flow sampler
used to measure respirable crystalline silica in the U.K. For the
GK2.69, use of a flow rate of 4.2 L/min or 4.4 L/min made little
difference in the respirable mass collected, and there was closer
agreement between the GK2.69 and SIMPEDS sampler when comparing
respirable crystalline silica concentration than respirable dust
concentration, and the difference was not statistically significant
(Document ID 3618, p. 10). According to NIOSH, the findings by Stacey
et al. (2013) corroborate those of Lee et al. (2010 and 2012) that the
GK2.69 meets the ISO/CEN requirements for cyclone performance and that
either the 4.2 L/min or 4.4 L/min flow rate "can be used to meet the
ISO convention within acceptable limits" (Document ID 2177, p. 13).
Mr. Scott testified that the high-flow samplers (including the
GK2.69) studied by Lee et al., (2010 and 2012), "tended to have a
substantial bias towards collecting more respirable particulates than
the low-flow samplers, collecting between 12 percent and 31 percent
more mass" because high-flow samplers tend to collect a higher
proportion of larger particles (Document ID 3582, Tr. 1984). In his
written testimony, he noted that Lee et al. (2010) reported a nearly
10-fold higher collection efficiency for 10 [mu]m particles compared to
the ISO/CEN standard. However, Mr. Scott's testimony ignores Lee et
al.'s findings that the oversampling of larger particles seen at a flow
rate of 4.2 L/min was not apparent at the higher 4.4 L/min flow rate
and that Lee et al. (2010) concluded that agreement with the ISO/CEN
convention was achieved at the higher flow rate (Document ID 3616, pp.
706, 708). In addition, oversampling of larger particles at the 4.2 L/
min flow rate was not reported by Lee et al. (2012, Document 3615) or
Stacey et al. (2013, Document ID 3618).
Dr. Hall expressed a similar concern as Mr. Scott. He cited Lee et
al. (2010) as stating that the GK2.69 would collect significantly more
aerosol mass for particle size distributions having an MMAD of more
than 6 [mu]m. He also cited Lee et al. (2010 and 2012) for the finding
that the GK2.69 collects from 1.8 to 3.84 times as much aerosol mass as
the Dorr-Oliver or Higgins-Dewell cyclones (Document ID 2285, p. 12).
In his pre-hearing comment, Dr. Hall stated that "[f]or aerosol clouds
with a [MMAD] greater than 10 [mu]m, the expected absolute bias can
range be (sic) between 20 and 60%" and "the total variability for the
method SAE can be as large as 85-90%" (Document ID 2285, pp. 15-16).
OSHA notes that both Dr. Hall and Mr. Scott focus their comments
regarding the performance of high-flow samplers on environments where
the particle size distribution is characterized by larger particles and
small variance (GSD). The findings by Lee et al. (2010) show that, at a
flow rate of 4.2 L/min, under this experimental system, there were
large positive biases (>20 percent) against the ISO/CEN convention for
nearly all particle size distributions having MMAD of 5 to 10 [mu]m
(Document ID 3616, pp. 704-706, Figure 3(b)). However, when the flow
rate was adjusted to 4.4 L/min, bias exceeding 20 percent was found to
occur primarily with particle size distributions having GSDs under 2.0
and MMAD greater than 10 [mu]m (Document ID 3616, p. 707, Figure 5(a)).
As discussed above, it is rare to encounter particle size distributions
having relatively large MMADs and small GSDs, so the high variability
attributed to high-flow samplers by Dr. Hall and Mr. Scott should not
be of concern for most workplace settings. Further, sampler performance
is considered acceptable if the bias and accuracy over at least 80
percent of the remaining portion of the bias map are within acceptable
limits, which are no more than 10 and 30 percent, respectively
(Document ID 1457, pp. 49, 52). The Lee et al. studies (2010 and 2012)
concluded that the high-flow samplers tested met these international
requirements for accuracy for sampling the ISO/CEN convention, and the
Stacey et al. (2013) study found that their results compared favorably
with those of Lee et al. (2012). Therefore, OSHA finds that the
uncertainties characterized by Dr. Hall and Mr. Scott are exaggerated
for most workplace situations, and that there is substantial evidence
that high-flow samplers, in particular the GK2.69 cyclone, can be used
to collect respirable crystalline silica air samples in most workplace
settings without introducing undue bias.
Mr. Scott, testifying for the ACC, was of the opinion that,
although high-flow samplers have been evaluated by Gorner et al. (2001,
Document ID 1457) and Lee et al. (2010, Document ID 3616; 2012, 3615)
with respect to their sampling efficiencies as compared to the ISO/CEN
convention and their performance compared to low-flow samplers, none of
the studies evaluated the accuracy and precision using methods
recommended in NIOSH's Guidelines for Air Sampling and Analytical
Method Development and Evaluation (1995, http://www.cdc.gov/niosh/docs/95-117/)
(Document ID 2308, Attachment 6, p. 18). OSHA understands Mr.
Scott to contend that the sampler must be tested against a generated
atmosphere of respirable crystalline silica and that the precision of
the sampling and analytical method must be determined overall from
these generated samples.
OSHA does not agree with the implication that, until high-flow
samplers have been evaluated according to the NIOSH (1995) protocol,
the findings from the studies described above are not sufficient to
permit an assessment of sampler performance. The NIOSH Guidelines cited
by Mr. Scott state that "[a]n experimental design for the evaluation
of sampling and analytical methods has been suggested. If these
experiments are not applicable to the method under study, then a
revised experimental design should be prepared which is appropriate to
fully evaluate the method" (http://www.cdc.gov/niosh/docs/95-117/, p.
1). These guidelines contemplate the development of entirely new
sampling and analytical methods. Because the analytical portion of the
sampling and analytical method for respirable crystalline silica was
already fully evaluated before the GK2.69 was developed (Kenny and
Gussman, 1997, Document ID 1444), it was only necessary to evaluate the
performance of the GK2.69 high-flow sampler. As described above, the
studies by Lee et al. (2010, Document ID 3616; 2012, 3615) and Stacey
et al. (2013, Document ID 3618) reflect a collaborative effort between
NIOSH in the U.S. and HSE in the U.K. to evaluate the performance of
high-flow respirable dust samplers. The Lee et al. (2010, 2012) studies
were conducted by NIOSH laboratories in Morgantown, West Virginia with
peer review by HSE scientists, and the Stacey et al. (2013) study was
conducted by HSE at the Health and Safety Laboratory at Buxton in the
U.K. Both Lee et al. (2012) and Stacey et al. (2013) concluded that
high-flow samplers studied, including the GK2.69, met the EN 13205
requirements for accuracy for sampling against the ISO/CEN convention,
demonstrating that results from these two national laboratories
compared favorably. OSHA concludes these peer-reviewed studies,
performed by NIOSH and HSE scientists, meet the highest standards for
effective methods evaluation and therefore does not agree with the
suggestion that additional work following NIOSH's protocol is
necessary. Comments submitted by NIOSH indicate that the Lee et al.
(2010, 2012) and Stacy et al. (2013) studies are sufficient to
establish the GK2.69 high-flow sampler as acceptable for
sampling respirable crystalline silica under the ISO/CEN convention
(Document ID 2177, Attachment B; 4233, p. 4).
URS Corporation, on behalf of the ACC, commented that precision
will not be improved by the use of high-flow samplers because filter
loadings of interferences will increase along with the amount of
crystalline silica; this would, in URS's opinion, necessitate
additional sample handling procedures, such as acid washing, that erode
precision. URS also argued that such samples may require analysis of
multiple peaks and that overall X-ray intensity may be diminished due
to increased filter load (Document ID 2307, Attachment 12, p. 3). In
its post-hearing brief, the ACC stated that the use of high-volume
samplers "in addition to traditional Dorr-Oliver sampler" would
reduce inter-laboratory precision (i.e., the extent to which different
laboratories achieve similar results for the same sample) due to the
use of multiple sampler types (Document ID 4209, p. 154).
OSHA finds that these arguments are unsupported. Although the high-
flow sampler will collect more dust than lower-flow samplers in the
same environment, the relative proportion of any interfering materials
collected to the amount of crystalline silica collected would remain
unchanged. Thus, there should be no increased effect from the
interfering materials relative to the silica. OSHA recognizes that, to
prevent undue interference or diminished X-ray intensity, it is
important to keep the dust load on the filter within reasonable limits.
Both OSHA and NIOSH methods stipulate a maximum sample weight to be
collected (3 mg for OSHA and 2 mg for NIOSH) (Document ID 0946, p. 5;
0901, p. 3), and in the event that excess sample is collected, the
sample can be split into portions and each portion analyzed separately
(Document ID 0946, p. 5). In environments where using a high-flow
sampler is likely to collect more than the maximum sample size, use of
a lower-flow sampler is advised. In response to the concern that
permitting use of high-flow samplers will affect inter-laboratory
variability, OSHA observes that employers are already using a variety
of commercially available samplers, such as those listed in the NIOSH
Method 7500, to obtain exposure samples; not everyone uses the Dorr-
Oliver sampler. Thus, for the final rule, OSHA is permitting employers
to use any sampling device that has been designed and calibrated to
conform to the ISO/CEN convention, including higher-flow samplers such
as the GK2.69. In effect, this is a continuation of well-studied
current practice, not an untested departure from it.
b. Laboratory Analysis of Crystalline Silica
Crystalline silica is analyzed in the laboratory using either X-ray
diffraction (XRD) or infrared spectroscopy (IR). A third method,
colorimetric spectrophotometry, is no longer used (Document ID 3579,
Tr. 211; Harper et al., 2014, 3998, Attachment 8, p. 1). This section
describes crystalline silica analysis by XRD and IR and responds to
comments and testimony on the precision and accuracy of these methods
for measuring crystalline silica concentrations in the range of the
final rule's PEL and action level. As discussed below, both XRD and IR
methods can detect and quantify crystalline silica in amounts collected
below the final rule's 25 [micro]g action level.
X-Ray Diffraction
For XRD, a dust sample that has been collected by a sampler is
deposited on a silver-membrane filter and scanned by the X-ray beam,
where X-rays diffract at specific angles. A sensor detects these
diffracted X-ray beams and records each diffracted beam as a
diffraction peak. Unique X-ray diffraction patterns are created when
the diffraction peaks are plotted against the angles at which they
occur. The intensity of the diffracted X-ray beams depends on the
amount of crystalline silica present in the sample, which can be
quantified by comparing the areas of the diffraction peaks obtained
with those obtained from scanning a series of calibration standards
prepared with known quantities of an appropriate reference material.
Comparing multiple diffraction peaks obtained from the sample with
those obtained from the calibration standards permits both quantitative
and qualitative confirmation of the amount and type of crystalline
silica present in the sample (i.e., quartz or cristobalite). A major
advantage of XRD compared with the other techniques used to measure
crystalline silica is that X-ray diffraction is specific for
crystalline materials. Neither non-crystalline silica nor the amorphous
silica layer that forms on crystalline silica particles affects the
analysis. The ability of this technique to quantitatively discriminate
between different forms of crystalline silica and other crystalline or
non-crystalline materials present in the sample makes this method least
prone to interferences. Sample analysis by XRD is also non-destructive,
meaning that samples can be reanalyzed if necessary (Document ID 1720,
pp. IV-26--IV-27).
The OSHA Technical Manual lists the following substances as
potential interferences for the analysis of crystalline silica using
XRD: Aluminum phosphate, feldspars (microcline, orthoclase,
plagioclase), graphite, iron carbide, lead sulfate, micas (biotite,
muscovite), montmorillonite, potash, sillimanite, silver chloride,
talc, and zircon (https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html, Chapter 1, III.K). The interference from other minerals
usually can be recognized by scanning multiple diffraction peaks
quantitatively. Diffraction peak-profiling techniques can resolve and
discriminate closely spaced peaks that might interfere with each other.
Sometimes interferences cannot be directly resolved using these
techniques. However, many interfering materials can be chemically
washed away in acids that do not dissolve the crystalline silica in the
sample. Properly performed, these acid washes can dissolve and remove
these interferences without appreciable loss of crystalline silica
(Document ID 1720, p. IV-27).
The nationally recognized analytical methods using XRD include OSHA
ID-142, NIOSH 7500, and MSHA P-2 (Document ID 0946; 0901; 1458). All
are based on the XRD of a redeposited thin-layered sample with
comparison to standards of known concentrations (Document ID 0946, p.
1; 0901, p. 1; 1458, p. 1). These methods, however, differ on
diffraction peak confirmation strategies. The OSHA and MSHA methods
require at least three diffraction peaks to be scanned (Document ID
0946, p. 5; 1458, p. 13). The NIOSH method only requires that multiple
peaks be qualitatively scanned on representative bulk samples to
determine the presence of crystalline silica and possible
interferences, and quantitative analysis of air samples is based on a
single diffraction peak for each crystalline silica polymorph analyzed
(Document ID 0901, pp. 3, 5).
Infrared Spectroscopy
Infrared spectroscopy is based on the principle that molecules of a
material will absorb specific wavelengths of infrared electromagnetic
energy that match the resonance frequencies of the vibrations and
rotations of the electron bonds between the atoms making up the
material. The absorption of IR radiation by the sample is compared with
the IR absorption of calibration standards of known concentration to
determine the amount of crystalline silica in the sample. Using IR can
be efficient for routine analysis of samples that are well
characterized with respect to mineral content, and the technique, like
XRD, is non-destructive, allowing samples to be reanalyzed if
necessary. The three principle IR analytical methods for crystalline
silica analyses are NIOSH 7602 (Document ID 0903), NIOSH 7603 (http://www.cdc.gov/niosh/docs/2003-54/pdfs/7603.pdf), and MSHA P-7 (Document
ID 1462); NIOSH Method 7603 and MSHA P-7 were both specifically
developed for the analysis of quartz in respirable coal dust. OSHA does
not use IR for analysis of respirable crystalline silica.
Interferences from silicates and other minerals can affect the
accuracy of IR results. The electromagnetic radiation absorbed by
silica in the infrared wavelengths consists of broad bands. In theory,
no two compounds have the same absorption bands; however, in actuality,
the IR spectra of silicate minerals contain silica tetrahedra and have
absorption bands that will overlap. If interferences enhance the
baseline measurement and are not taken into account, they can have a
negative effect that might underestimate the amount of silica in the
sample. Compared with XRD, the ability to compensate for these
interferences is limited (Document ID 1720, pp. IV-29--IV-30).
c. Sensitivity of Sampling and Analytical Methods
The sensitivity of an analytical method or instrument refers to the
smallest quantity of a substance that can be measured with a specified
level of accuracy, and is expressed as either the LOD or the "Limit of
Quantification" (LOQ). These two terms have different meanings. The
LOD is the smallest amount of an analyte that can be detected with
acceptable confidence that the instrument response is due to the
presence of the analyte. The LOQ is the lowest amount of analyte that
can be reliably quantified in a sample and is higher than the LOD.
These values can vary from laboratory to laboratory as well as within a
given laboratory between batches of samples because of variation in
instrumentation, sample preparation techniques, and the sample matrix,
and must be confirmed periodically by laboratories.
At a concentration of 50 [micro]g/m\3\, the final rule's PEL, the
mass of crystalline silica collected on a full-shift (480 minute) air
sample at a flow rate of 1.7 L/min, for a total of 816 L of air, is
approximately 41 [micro]g (see Table VII-7). At a concentration of 25
[micro]g/m\3\, the final rule's action level, the mass collected is
about 20 [micro]g. The LOQ for quartz for OSHA's XRD method is 10
[micro]g (Document ID 0946; 3764, p. 4), which is below the amount of
quartz that would be collected from full-shift samples at the PEL and
action level. Similarly, the reported LODs for quartz for the NIOSH and
MSHA XRD and IR methods are lower than that which would be collected
from full-shift samples taken at the PEL and action level (NIOSH Method
7500, Document ID 0901, p. 1; MSHA Method P-2, 1458, p. 2; NIOSH Method
7602, 0903, p. 1; NIOSH Method 7603, http://www.cdc.gov/niosh/docs/2003-154/pdfs/7603.pdf, p. 1; MSHA Method P-7, 1462, p. 1).
The rule's 50 [micro]g/m\3\ PEL for crystalline silica includes
quartz, cristobalite, and tridymite in any combination. For
cristobalite and tridymite, the previous general industry formula PEL
was approximately 50 [micro]g/m\3\, so the change in the PEL for
crystalline silica does not represent a substantive change in the PEL
for cristobalite or tridymite when quartz is not present. OSHA Method
ID-142 (Document ID 0946) lists a 30-[micro]g LOQ for cristobalite;
however, because of technological improvements in the equipment, the
current LOQ for cristobalite for OSHA's XRD method as implemented by
the OSHA Salt Lake Technical Center (SLTC) is about 20 [micro]g
(Document ID 3764, p. 10).
That XRD analysis of quartz from samples prepared from reference
materials can achieve LODs and LOQs between 5 and 10 [micro]g was not
disputed in the record. Of greater concern to several rulemaking
participants was the effect of interfering materials potentially
present in a field sample on detection limits and on the accuracy of
analytical methods at low filter loads when interferences are present.
Although the Chamber's witness, Robert Lieckfield of Bureau Veritas
Laboratories, did not dispute that laboratories could achieve this
level of sensitivity (Document ID 3576, Tr. 485-486), the ACC took
issue with this characterization of method sensitivity stating that
"the LOQ for real world samples containing interferences is likely to
be higher than the stated LOQ's for analytical methods, which are
determined using pure NIST samples with no interferences" (Document ID
4209, p. 132). Both Mr. Lieckfield and Mr. Scott testified that the
presence of interferences in samples can increase the LOQ and potential
error of measurement at the LOQ (Document ID 2259, p. 7; 3460, p. 5).
Mr. Scott (Document ID 2308, Attachment 6, p. 5) cited a laboratory
performance study by Eller et al. (1999a, Document ID 1687), in which
laboratories analyzing samples with and without interfering materials
present reported a range of LOD's from 5 [mu]g to 50 [mu]g. Mr. Scott
believed that this study provided evidence that interfering materials
present in crystalline silica samples adversely affected laboratories'
reported LODs. OSHA disagrees with this interpretation. The Agency
reviewed this study in the PEA (Document ID 1720, p. IV-33) and
believes that the variability in reported LODs reflected differences in
laboratory practices with respect to instrument calibration and quality
control procedures. These factors led Eller et al. (1999b, Document ID
1688, p. 24; 1720, p. IV-42) to recommend changes in such practices to
improve laboratory performance. Thus, OSHA finds that the variation in
reported LODs referred to by Mr. Scott cannot be attributed primarily
to the presence of interfering materials on the samples.
The presence of interferences can adversely affect the sensitivity
and precision of the analysis, but typically only when the interference
is so severe that quantification of crystalline silica must be made
from secondary and tertiary diffraction peaks (Document ID 0946, p. 6).
However, OSHA finds no evidence that interferences usually present
serious quantification problems. First, there are standard protocols in
the OSHA, NIOSH, and MSHA methods that deal with interferences.
According to OSHA Method ID-142,
Because of these broad selection criteria and the high specificity
of the method for quartz, some of the listed interferences may only
present a problem when a large amount of interferent is present...
. Interference effects are minimized by analyzing each sample for
confirmation using at least three different diffraction peaks so as
to include peaks where the quartz and cristobalite results are in
good agreement and where the interferent thus causes no problem.
Bulk samples or a description of the process being sampled are
useful in customizing a chemical cleanup procedure for any
interference found difficult to resolve by software. Even so, the
presence of an interference rarely jeopardizes the analysis
(Document ID 0946, p. 5).
Software developed by instrument manufacturers and techniques such
as acid washing of the sample when interferences are suspected to be
present are also useful in resolving interferences. The Chamber's
expert witness, Mr. Lieckfield, acknowledged that it was also their
practice at his lab to chemically treat samples from the start to
remove interfering materials and to analyze multiple diffraction peaks
to resolve interferences (Document ID 3576, Tr. 533, 542). According to
OSHA's representative from the SLTC, it is "nearly always possible"
to eliminate interferences and is it no more difficult to obtain
precise measurements when interferences are present than when they are
not (Document ID 3579, Tr. 48).
ACC also cites the results of a round-robin performance study that
it commissioned, in which five laboratories were provided with
crystalline silica samples with and without interfering materials
(Document ID 4209, p. 132). These laboratories reported non-detectable
levels of silica for 34 percent of the filters having silica loadings
of 20 [mu]g or more. However, as discussed below in the section on
inter-laboratory variability (Section IV-3.2.5--Measurement Error
Between Laboratories), OSHA has determined that this study is seriously
flawed and, in particular, that there was systematic bias in the
results, possibly due to sample loss. This could explain the high
prevalence of reported non-detectable samples by the laboratories,
rather than the presence of interferences per se.
Furthermore, OSHA's review of the several hundred inspection
reports relied on to evaluate the technological feasibility of the
final rule's PEL in many industry sectors does not show that
investigators have particular difficulty in measuring respirable
crystalline silica concentrations below the PEL. Sections IV-4 and IV-5
of this chapter contain hundreds of exposure measurement results in a
wide variety of workplace settings that were detected and reported by a
laboratory as being above detectable limits but below the PEL or action
level. If, as ACC suggests, interferences have a profound effect on the
ability to measure concentrations in this range, many of these samples
might have been reported as "less than the LOD," with the reported
LOD in the range of 25 [mu]g to 50 [mu]g. Examination of the exposure
data described in Sections IV-4 and IV-5 of this chapter shows clearly
that this is not the case (see exposure profiles for Concrete Products,
Section IV-4.3; Cut Stone, Section IV-4.4; Foundries (Metal Casting),
Section IV-4.8; Mineral Processing, Section IV-4.12; Porcelain
Enameling, Section IV-4.14; Ready Mix Concrete, Section IV-4.17;
Refractories, Section IV-4.18). In addition, the United Steelworkers
reported receiving exposure data from 17 employers with samples in this
same range, indicating that sampling of exposures below the final PEL
and action level is feasible and already being utilized by employers
(Document ID 4214, pp. 12-13; Document ID 4032, Attachment 3).
Therefore, OSHA finds that the presence of interfering substances
on field samples will not, most of the time, preclude being able to
detect concentrations of respirable crystalline silica in the range of
the PEL and action level, and that such instances where this might
occur are rare. Accordingly, even when the presence of interfering
substances is taken into account, worker exposure is capable of being
measured with a reasonable degree of sensitivity and precision.
d. Precision of Measurement
All analytical methods have some random measurement error. The
statistics that describe analytical error refer to the amount of random
variation in measurements of replicate sets of samples containing the
same quantity of silica. This variation is expressed as a standard
deviation about the mean of the measurements. The relative standard
deviation (RSD), a key statistic used to describe analytical error, is
calculated by dividing the standard deviation by the mean for a data
set. The RSD is also known as the coefficient of variation (CV).
When random errors are normally distributed, a 95-percent
confidence interval can be calculated as X (1.96 x CV),
where X is the mean. This statistic is termed the "precision" of the
analytical method and represents a 2-sided confidence interval in that,
for a particular measurement, there is a 95-percent chance that the
"true" value, which could be higher or lower than the measurement,
lies within the confidence interval. The measure of analytical
precision typically also includes a term to represent error in sampler
pump flow, which is conventionally taken to be 5 percent. The better
the precision of an analytical method, the lower its value (i.e., a
method having a precision of 17 percent has better precision than one
with a precision of 20 percent).
OSHA also uses a statistic called the Sampling and Analytical Error
(SAE) to assist compliance safety and health officers (CSHOs) in
determining compliance with an exposure limit. The estimate of the SAE
is unique for each analyte and analytical method, and must be
determined by each laboratory based on its own quality control
practices. At OSHA's Salt Lake Technical Center (SLTC), where
analytical methods are developed and air samples taken for enforcement
purposes are analyzed, the SAE is based on statistical analysis of
results of internally prepared quality control samples. Sampling and
analytical components are assessed separately, where CV1
reflects analytical error that is estimated from the analysis of
quality control samples, and CV2 is the sampling error,
assumed to be 5 percent due to variability in sampling pump flow rates
that can affect sample air volume. Analytical error is combined with
sampling pump error, and the SAE is calculated as a one-sided 95-
percent confidence limit with the following formula:
The current SLTC SAE for crystalline silica is approximately 0.17,
according to testimony from a representative of SLTC (Document ID 3579,
Tr. 95). OSHA uses the SAE in its enforcement of PELs, where the PEL
times the SAE is added to the PEL for a substance and compared to a
sample result (see Section II, Chapter 1 of the OSHA Technical Manual,
https://www.osha.gov/dts/osta/otm/otm_toc.html). A sample result is considered to have definitively exceeded the PEL if the result is
greater than the sum of the PEL and the PEL times the SAE. For example,
with the PEL at 50 [mu]g/m\3\ and an SAE of 17 percent, an air sample
result would have to be greater than 58.5 [mu]g/m\3\ (i.e., 50 + (50 x
0.17)) to be considered to have definitively exceeded the PEL. This
policy gives employers the benefit of the doubt, as it assumes that the
actual exposure was below the PEL even when the result is above the PEL
but below the PEL plus the SAE; the effect is that OSHA does not cite
an employer for an exposure above the PEL unless the Agency has
obtained a sample measurement definitively above the PEL after
accounting for sampling and analytical error.
OSHA's quality control samples, which were prepared and analyzed at
SLTC, demonstrate that the XRD method has acceptable precision, even at
the low range of filter loads (50 [mu]g). For the period April 2012
through April 2014, SLTC's analysis of 348 quality control samples,
with a range of filter loads of about 50 to 250 [mu]g crystalline
silica, showed average recovery (i.e., the measurement result as
compared to the reference mean value for the sample) of 0.98 with an
RSD of 0.093 and precision of 20.8 percent (Document ID 3764,
Attachment 1). Among those samples, there were 114 with a target filter
load of 50 [mu]g (range of actual filter load was 50 to 51.6 [mu]g);
these samples showed an average recovery of 1.00 with an RSD of 0.093
and precision of 20.7 percent (Document ID 3764, Attachment 1). Thus,
OSHA's experience with quality control standards shows that the XRD
method for quartz is as precise in the low range of method validation
as it is over the full range.
The ACC raised several questions regarding OSHA's Method ID-142 and
its validation. First, a paper they submitted by Sandra Wroblewski,
CIH, of Computer Analytical Solutions notes that OSHA's stated Overall
Analytical Error is 26 percent, higher than the 25-percent level "OSHA
states is necessary to ensure that a PEL can be feasibly measured,"
and that the method had not been validated for cristobalite (Document
ID 2307, Attachment 10, pp. 13-14). In addition, the ACC stated that
OSHA's method specifies a precision and accuracy validation range of
50-160 [micro]g quartz per sample, above the quantity that would be
collected at the PEL and action level (assuming use of a Dorr-Oliver
sampler at 1.7 L/min) and that the method has not been tested for
validation at a range corresponding to the PEL and action level
(Document ID 2307, Attachment 10, p. 14). ACC also argued that OSHA's
method does not comply with the Agency's Inorganic Methods Protocol,
which requires the CV1 to be 0.07 or less and the detection
limit to be less than 0.1 times the PEL (Document ID 2307, Attachment
A, p. 202). The Edison Electric Institute (Document ID 2357, pp. 20-21)
and Ameren Corporation (Document ID 2315, p. 2) expressed similar
concerns about the detection limit.
While OSHA's published Method ID-142 reports an Overall Analytical
Error of 26 percent, OSHA no longer uses this statistic (it is in the
process of revising Method ID-142); the Agency provides measures of
precision and SAE instead. The Overall Analytical Error, which is
described in Method ID-142, published in 1996, included a bias term
that is now corrected for in the data used to determine method
precision, so there is no longer a need to include a bias term in the
estimation of analytical error. As described above, the precision of
Method ID-142 is about 21 percent based on recent quality control
samples.\24\ OSHA's Inorganic Methods Protocol, to which the ACC
referred, has been replaced by evaluation guidelines for air sampling
methods using spectroscopic or chromatographic analysis, published in
2005 (https://www.osha.gov/dts/sltc/methods/spectroguide/spectroguide.html)
and 2010 (https://www.osha.gov/dts/sltc/methods/chromguide/chromguide.html), respectively. These more recent
publications no longer reflect the guidance contained in the Inorganic
Methods Protocol, and OSHA's Method ID-142 is consistent with these
more recent guidelines. Finally, although the published method did not
include validation data for filter loads below 50 [mu]g or data for
cristobalite, OSHA has conducted studies to characterize the precision
that is achieved at low filter loads for quartz and cristobalite; these
studies are in the rulemaking record (Document ID 1670, Attachment 1;
1847, Attachment 1; 3764, pp. 15-16) and are discussed further below.
---------------------------------------------------------------------------
\24\ OSHA also wishes to point out that the guideline for
achieving a method precision of 25 percent was never an OSHA
requirement for determining method feasibility, but is drawn from
the NIOSH Accuracy Criterion (http://www.cdc.gov/niosh/docs/95-117/
), which was used for the purpose of developing and evaluating
analytical methods. Nevertheless, OSHA's Method ID-142 now meets
that guideline.
---------------------------------------------------------------------------
In comments submitted on behalf of the Chamber, Mr. Lieckfield
cited the NIOSH Manual of Analytical Methods, Chapter R, as stating
that "current analysis methods do not have sufficient accuracy to
monitor below current exposure standards" (Document ID 2259, p. 1).
However, this is contradicted by NIOSH's own post-hearing submission,
which stated that, although method variability was assessed based on
the exposure limits at that time (i.e., 1983, see Document ID 0901, pp.
1, 7), "it was known from an intra-laboratory study that an acceptable
variability would likely be at least 20 [mu]g on-filter, and so 20
[mu]g was given as the lower range of the analytical method" (Document
ID 4233, p. 3). Furthermore, in Chapter R of NIOSH's Manual, NIOSH goes
on to say that the GK2.69 high-flow sampler "has promise for
potentially lowering the levels of silica that can be measured and
still meet the required accuracy" (http://www.cdc.gov/niosh/docs/2003-154/pdfs/chapter-r.pdf, p. 265). This chapter was published in 2003,
well before the studies by Lee et al. (2010, 2012) and Stacey et al.
(2013), discussed above, which demonstrate that the GK2.69 sampler has
acceptable performance. NIOSH concluded in its post-hearing comment
that "current methods of sampling and analysis for respirable
crystalline silica have variability that is acceptable to demonstrate
compliance with the proposed PEL and action level" (Document ID 4233,
p. 4).
At the time of the proposal, there was little data characterizing
the precision of analytical methods for crystalline silica at filter
loads in the range of the PEL and action level (i.e., with prepared
samples of 40 [mu]g and 20 [mu]g crystalline silica, which are the
amounts of silica that would be collected from full-shift sampling at
the PEL and action level, respectively, assuming samples are collected
with a Dorr-Oliver cyclone at a flow rate of 1.7 L/min). To
characterize the precision of OSHA's Method ID-142 at low filter loads,
SLTC conducted studies in 2010 and again in 2013 (the latter of which
was presented in the PEA; see Document ID 1720, p. IV-35). For these
studies, the lab prepared 10 replicate samples each of quartz and
cristobalite from NIST standard reference material and determined the
precision of the analytical method; a term representing pump flow rate
error was included in the precision estimate. In the 2010 test
(Document ID 1670, Attachment 1), the precision for quartz loads
equating to the PEL and action level was 27 and 33 percent,
respectively. For cristobalite loads equating to the PEL and action
level, the precision was 23 and 27 percent, respectively. The results
from the 2013 test (Document ID 1847, Attachment 1; 3764, pp. 15-16;
Document ID 1720, p. IV-35) showed improvement in the precision; for
quartz, precision at loads equating to the PEL and action level was 17
and 19 percent, respectively, and for cristobalite, precision at loads
equating to the PEL and action level was 19 and 19 percent,
respectively. Both the 2010 and 2013 tests were conducted using the
same NIST standards, same instrumentation, and same sample preparation
method (OSHA Method ID-142) with the exception that the 2013 test used
automatic pipetting rather than manual pipetting to prepare the samples
(Document ID 1847). OSHA believes it likely that this change in sample
preparation reduced variation in the amount of silica loaded onto the
filters, which would account for at least some of the increased
precision seen between 2010 and 2013 (i.e., imprecision in preparing
the samples would make the analytical precision for 2010 appear worse
than it actually was). Based on these studies, particularly the 2013
study, OSHA preliminarily determined that the XRD method was capable of
accurately measuring crystalline silica concentrations at the PEL and
action level.
The ACC believed that OSHA's reliance on the 2013 study was
"misplaced" because the results were not representative of "real
world" samples that contain interfering minerals that could increase
analytical error, and because the studies did not account for inter-
laboratory variability (Document ID 4209, pp. 135-137; 2308, Attachment
6, p. 10). The ACC also believed that variability would have been
depressed in this study because the samples were analyzed in close
temporal proximity by the same analyst and using the same instrument
calibration, and the study involved only 10 samples at each filter load
(Document ID 4209, pp. 137-138; 2308, Attachment 6, p. 10).
The ACC's witness, Mr. Scott, also commented that the study
failed to take into account the effect of particle sizes on the
analysis of crystalline silica and believed that SLTC's evaluation
could not reflect differences in precision between the XRD and IR
methods (Document ID 2308, Attachment 6, p. 10).
Despite the criticism that OSHA's investigation involved a small
number of samples analyzed at the same time, the results obtained were
comparable to OSHA's analysis of quality control samples at somewhat
higher filter loads (between 50 and 51.6 [mu]g) analyzed over a two-
year period (Document ID 3764, Attachment 1). These results, described
above, showed a precision of 20.7 percent, compared to 17 and 19
percent for quartz filter loads of 40 and 20 [mu]g, respectively
(Document ID 1847, Attachment 1; Document ID 3764). From these results,
OSHA concludes that any effect on analytical error from performing a
single study using the same analyst and instrument calibration is
modest.
OSHA also concludes that Mr. Scott's argument that particle size
effects were not taken into account is without merit. The samples
prepared and analyzed in OSHA's study, like any laboratory's quality
control samples, use standard materials that have a narrow range in
particle size. Although large (non-respirable) size particles can
result in an overestimate of crystalline silica content, in practice
this is not typically a serious problem with air samples and is more of
a concern with analyzing bulk samples. First, as discussed above,
respirable dust samplers calibrated to conform to the ISO/CEN
convention are collecting respirable particulate and excluding larger
particles (Document ID 3579, Tr. 219). In analyzing field samples, OSHA
uses microscopy to identify whether larger particles are present and,
if they are, the results are reported as a bulk sample result so as not
to be interpreted as an airborne exposure (Document ID 3579, Tr. 213).
Additionally, OSHA's Method ID-142 calls for grinding and sieving bulk
samples to minimize particle size effects in the analysis (Document ID
0946, p. 13). OSHA also notes that the Chamber's witness, Mr.
Lieckfield, testified that his laboratory does not check for oversized
particles (Document ID 3576, p. 483).
With regard to interferences, as discussed above, there are
procedures that have been in place for many years to reduce the effect
of interfering materials in the analysis. The presence of interferences
does not typically prevent an analyst from quantifying crystalline
silica in a sample with reasonable precision. As to the claim regarding
XRD versus IR, a recent study of proficiency test data, in which
multiple laboratories are provided comparable silica samples, both with
and without interfering materials added, did not find a meaningful
difference in precision between laboratories using XRD and those using
IR (Harper et al., 2014, Document ID 3998, Attachment 8). In addition,
as discussed above, NIOSH's and OSHA's measures of precision of the XRD
method at low filter loads were comparable, despite differences in
equipment and sample preparation procedures. Therefore, OSHA finds that
the studies it carried out to evaluate the precision of OSHA Method ID-
142 at low filter loads provide a reasonable characterization of the
precision of the method for analyzing air samples taken at
concentrations equal to the final PEL and action level under the
respirable crystalline silica rule.
With respect to the ACC's and Mr. Scott's reference to inter-
laboratory variation in silica sample results, OSHA discusses data and
studies that have evaluated inter-laboratory variance in analytical
results in the next section.
e. Measurement Error Between Laboratories
The sources of random and systematic error described above reflect
the variation in sample measurement experienced by a single laboratory;
this is termed intra-laboratory variability. Another source of error
that affects the reliability of results obtained from sampling and
analytical methods is inter-laboratory variability, which describes the
extent to which different laboratories may obtain disparate results
from analyzing the same sample. Inter-laboratory variability can be
characterized by using data from proficiency testing, where
laboratories analyze similarly-prepared samples and their results are
compared. In practice, however, it is difficult to separate intra- and
inter-laboratory variability because each laboratory participating in a
proficiency test provides analytical results that reflect their own
degree of intra-laboratory variability. Thus, use of proficiency test
data to compare performance of laboratories in implementing an
analytical method is really a measure of total laboratory variability.
The best available source of data for characterizing total
variability (which includes an inter-laboratory variability component)
of crystalline silica analytical methods is the AIHA Industrial Hygiene
Proficiency Analytical Testing (PAT) Program. The AIHA PAT Program is a
comprehensive testing program that provides an opportunity for
laboratories to demonstrate competence in their ability to accurately
analyze air samples through comparisons with other labs. The PAT
program is designed to help consumers identify laboratories that are
deemed proficient in crystalline silica analysis.
Crystalline silica (using quartz only) is one of the analytes
included in the proficiency testing program. The AIHA PAT program
evaluates the total variability among participating laboratories based
on proficiency testing of specially prepared silica samples. The AIHA
contracts the preparation of its crystalline silica PAT samples to an
independent laboratory that prepares four PAT samples in the range of
about 50 to 225 [mu]g (Document ID 3586, Tr. 3279-3280) and one blank
sample for each participating laboratory per round. Each set of PAT
samples with the same sample number is prepared with as close to the
same mass of crystalline silica deposited on the filter as possible.
However, some variability occurs within each numbered PAT sample set
because of small amounts of random error during sample preparation.
Before the contract laboratory distributes the round, it analyzes a
representative lot of each numbered set of samples to ensure that
prepared samples are within 10 percent (Document ID 3586,
Tr. 3276). The samples are distributed to the participating
laboratories on a quarterly basis (Document ID 1720, p. IV-36). The PAT
program does not specify the particular analytical method to be used.
However, the laboratory is expected to analyze the PAT samples using
the methods and procedures it would use for normal operations.
The results of the PAT sample analysis are reported to the AIHA by
the participating laboratories. For each PAT round, AIHA compiles the
results and establishes upper and lower performance limits for each of
the four sample results based on the mean and RSD of the sample
results. For each of the four samples, a reference value is defined as
the mean value from a selected set of reference laboratories. The RSD
for each of the four samples is determined from the results reported by
the reference labs after correcting for outliers (generally clear
mistakes in analysis or reporting, particularly those that are order-
of-magnitude errors) (Document ID 4188, p. 2). A participating
laboratory receives a passing score if at least three out of the four
sample results reported are within 20 percent of the reference mean for
the sample (Document ID 3586, Tr. 3291). Two or more results reported
by a lab in a given round that are outside the limits results
in the lab receiving an unsatisfactory rating. An unsatisfactory
rating in 2 of the last 3 rounds results in revocation of the
lab's AIHA accreditation for the analysis of crystalline silica.
Participation in the PAT program is a prerequisite for accreditation
through the AIHA Industrial Hygiene Laboratory Accreditation Program
(IHLAP).
In the PEA, OSHA presented PAT results from its SLTC for the period
June 2005 through February 2010 (PAT Rounds 160-180) (Document ID 1720,
pp. IV-40-41). The mean recovery was 99 percent, with a range of 55 to
165 percent. Eighty-one percent of the samples analyzed over this
period were within 25 percent of the reference mean and the
RSD for this set of samples was 19 percent, showing reasonable
agreement with the reference mean. OSHA also evaluated PAT data from
all participating laboratories for the period April 2004 through June
2006 (PAT Rounds 156-165) (Document ID 1720, pp. IV-37--IV-40).
Overall, the mean lab RSD was 19.5 percent for the sample range of 49
to 165 [mu]g. Beginning with Round 161, PAT samples were prepared by
liquid deposition rather than by sampling a generated silica aerosol,
in order to improve consistency and reduce errors in sample
preparation. The improvement was reflected in the results, with the
mean lab RSD declining from 21.5 percent to 17.2 percent after the
change to liquid deposition, demonstrating the improved consistency
between PAT samples.
In the time since OSHA analyzed the PAT data, Harper et al. (2014,
Document ID 3998, Attachment 8) evaluated more recent data.
Specifically, Harper et al. (2014, Document ID 3998, Attachment 8, p.
3) evaluated PAT test results for the period 2003-2014 (Rounds 152
through 194) and found that variation in respirable crystalline silica
analysis has improved substantially since the earlier data from 1990 to
1998 was studied by Eller et al. (1999a, Document ID 1687). A total of
9,449 sample results were analyzed after removing re-test results,
results where the method of analysis was not identified, and results
that were more than three standard deviations from the reference mean.
There was a clear improvement in overall variation in the newer data
set compared with that of Eller et al. (1999a, Document ID 1687), with
the mean laboratory RSD declining from about 28.7 percent to 20.9
percent (Document ID 3998, Attachment 8, Figure 1). Both the older and
newer data sets showed that analytical variation increased with lower
filter loadings, but the more recent data set showed a much smaller
increase than did the older. At a filter load of 50 [mu]g, the mean lab
RSD of the more recent data was less than 25 percent, whereas it was
almost 35 percent with the older data set (Document ID 3998, Attachment
8, Figure 1). It was also clear that the change in sample preparation
procedure (i.e., from aerosol deposition to liquid deposition starting
in Round 161) explained at least some of the improvement seen in the
more recent PAT results, with the mean lab RSD declining from 23.6
percent for all rounds combined to 19.9 percent for Rounds 162-194.
Despite the improvement seen with the change in deposition method,
it is important to understand that the observed variation in PAT
results between labs still reflects some sample preparation error
(limited to 10 percent as explained above), a source of
error not reflected in the analysis of field samples. Other factors
identified by the investigators that account for the improved
performance include the phasing out of the colorimetric method among
participating labs, use of more appropriate calibration materials
(i.e., NIST standard reference material), calibration to lower mass
loadings, stricter adherence to published method procedures, and
possible improvements in analytical equipment. There was also only a
small difference (2 percent) in mean lab RSD between labs using XRD and
those using IR (Document ID 3998, Attachment 8, p. 9). The increase in
variance seen with lower filter loads was not affected either by
analytical method (XRD vs. IR) or by the composition of interfering
minerals added to the matrix (Document ID 3998, Attachment 8, p. 4).
OSHA finds that this study provides substantial evidence that
employers will obtain reliable results from analysis of respirable
crystalline silica most of the time for the purpose of evaluating
compliance with the PEL. From Round 162 through 194 (after the
deposition method was changed), and over the full range of PAT data,
only about 7 out of the 128 (5 percent) lab RSD values reported were
above 25 percent (Document ID 3404, Figure 2). For filter loads of 75
[mu]g or less, only 3 lab RSD values out of about 30 reported, were
above 25 percent. As stated above, the mean RSD at a filter load of 50
[mu]g was less than 25 percent and agreement between labs improved
substantially compared to earlier PAT data.
Summary data for PAT samples having a target load of less than 62.5
[mu]g were provided by AIHA in a post-hearing comment (Document ID
4188) and compared with the findings reported by Harper et al. (2014,
Document ID 3998, Attachment 8). For PAT rounds 155-193 (from 1999 to
2013), there were 15 sets of samples in the range of 41.4 to 61.8 [mu]g
distributed to participating laboratories. Lab RSDs from results
reported for these samples ranged from 11.2 to 26.4 percent, with an
average RSD of 17.1 percent, just slightly above the average RSD of
15.9 percent for all samples across the entire range of filter loads
from those rounds. Taken together, the results of the analysis
performed by Harper et al. (2014, Document ID 3998, Attachment 8) and
the summary data provided by AIHA (Document ID 4188) suggest that
sample results from participating labs will be within 25 percent of the
crystalline silica filter load most of the time.
In its post hearing comments, the National Stone, Sand & Gravel
Association (NSSGA) contended that analytical laboratories cannot
provide adequately precise and accurate results of silica samples
(Document ID 4232). NSSGA provided a detailed analysis of low-load
samples from the same 15 PAT rounds as examined by AIHA (Document ID
4188) and concluded that "employers and employees cannot rely on
today's silica sampling and analytical industry for consistently
accurate sample results necessary to achieve or surpass compliance
requirements" (Document ID 4232, p. 26). The NSSGA compared individual
labs' sample results to the reference mean for each sample and found,
from the AIHA PAT data, that 76-84 percent of the results were within
25 percent of the reference mean, and the range of results reported by
laboratories included clear outliers, ranging from zero to several-fold
above the target filter load (Document ID 4232, p. 8, Table 1, rows 1-
6). NSSGA concluded from this that "[i]t is of little value to
employers that a given lab's results meet the NIOSH Accuracy Criterion
while other labs' results cannot, particularly since employers almost
certainly won't know which labs fall into which category" (Document ID
4232, p. 10). NSSGA's point appears to be that the outliers in the PAT
data erode an employer's ability to determine if they are receiving
accurate analytical results, without which they have little ability to
determine their compliance status with respect to the PEL or action
level. Further, NSSGA suggests that OSHA's analysis of the PAT data,
discussed above, is not adequate to demonstrate the performance of an
individual laboratory that may be chosen by an employer.
In response to NSSGA's criticism, OSHA points out that its analysis
of the PAT data was part of its analysis of technological feasibility
in which the Agency's legal burden is to show that employers can
achieve compliance in most operations most of the time. It may be an
unavoidable fact that lab results may be inaccurate some of the time,
but that does not render the standard infeasible or unenforceable. OSHA
contends that its analysis has satisfied that burden and nothing in the
NSSGA's comments suggests otherwise.
NSSGA further suggests that employers have no means of determining,
based on a laboratory's PAT proficiency rating alone, whether that
individual laboratory is likely to produce erroneously high or low
results. OSHA concurs that selecting a laboratory based on
accreditation, price, and turnaround time, as NSSGA suggests (Document
ID 4232, p. 5), is common but may be inadequate to determine whether an
individual laboratory is capable of producing results of consistently
high quality. Employers and their industrial hygiene consultants can,
and should, ask additional questions and request additional assurances
of quality from the laboratories they consider using. For example,
employers can ask to review the laboratory's individual PAT results
over time, focusing on and questioning any significant outliers in the
laboratory's results. While NSSGA suggests that the PAT results are
treated as confidential by the AIHA-PAT program (Document ID 4232, p.
6), there is nothing stopping a laboratory from sharing its PAT data or
any other information related to its accreditation with their clients
or prospective clients.
Further, laboratories routinely perform statistical analyses of
their performance in the context of analyzing known samples they use
for equipment calibration, and often perform statistical comparisons
among the various technicians they employ. Review of these statistics
can shed light on the laboratory's ability to provide consistent
analysis. Finally, as employers conduct exposure monitoring over time,
and come to understand what results are typically seen in their
workplaces, clear outliers should become more identifiable; for
example, if employee exposures are usually between the action level and
PEL, and a sample result shows an exposure significantly above the PEL
without any clear change in workplace conditions or operations,
employers should question the result and ask for a reanalysis of the
sample. Employers could also request gravimetric analysis for
respirable dust against which to compare the silica result to confirm
that the silica content of the dust is consistent with past experience.
For example, if, over time, an employer's consistent results are that
the silica content of respirable dust generated in its workplace is 20
percent silica, and subsequently receives a sample result that
indicates a significantly higher or lower silica content, it would be
appropriate for the employer to question the result and request
reanalysis. Therefore, OSHA rejects the idea that employers are at the
mercy of random chance and have to simply accept a high degree of
uncertainty in exposure measurements; rather, there are positive steps
they can take to reduce that uncertainty.
Results from the AIHA PAT program were discussed at considerable
length during the rulemaking proceeding. After considering all of the
analyses of PAT data presented by Eller et al. (1999a, Document ID
1687), OSHA in its PEA, and Harper et al. (2014, Document ID 3404), the
ACC concluded that "PAT program results indicate that analytical
variability as measured by precision is unacceptably high for silica
loadings in the range of 50-250 [mu]g" and that the PAT data "provide
strong evidence that commercial laboratories will not be able to
provide reliable measurements of...[respirable crystalline silica]
exposures at the levels of the proposed PEL and action level"
(Document ID 4209, p. 144). OSHA disagrees with this assessment. First,
OSHA's experience over the last 40 years in enforcing the preceding PEL
that this standard supersedes is that analytical variability has not
been an impediment to successful enforcement of the superseded PEL, and
there have been few, if any, challenges to such enforcement actions
based on variability. Nor has OSHA been made aware of concerns from
employers that they have been unable to evaluate their own compliance
with the former PEL or make reasonable risk management decisions to
protect workers. In fact, the Chamber's expert, Mr. Lieckfield,
admitted that analytical variability for asbestos, another substance
that has been regulated by OSHA over the Agency's entire history, "is
worse" than that for crystalline silica (Document ID 3576, Tr. 531).
To support its contention that reliably measuring silica at the
final rule's PEL and action level is not possible, the ACC cited Harper
et al. (2014, Document ID 3998, Attachment 8) as stating that further
increases in laboratory variance below the 40-50 [mu]g range would have
"implications for the [working] range of the analytical methods," and
that excessive variance might "make it difficult to address for either
method" (Document ID 4209, p. 144). However, it is clear from Harper
et al. (2014) that this is the basis for the authors' recommendation
that the PAT program consider producing samples with filter loads as
low as 20 [mu]g to "support the analysis of lower target concentration
levels" (Document ID 3404, p. 5). They also identify use of currently
available higher-flow-rate sampling devices (discussed above) to
increase the collected mass of silica, which would generate field
samples in the filter load range currently used in the PAT program.
Finally, the ACC sponsored a performance testing study to assess
inter-laboratory variability at crystalline silica filter loads at 40
and 20 [mu]g (i.e., the amount of silica collected at final rule's PEL
and action level, respectively, assuming use of a Dorr-Oliver cyclone
operated at a flow rate of 1.7 L/min) as well as at 80 [mu]g (i.e., the
amount collected at the preceding PEL) (Document ID 2307, Attachment
14; 3461; 3462). The study was blinded in that participating
laboratories were not aware that they were receiving prepared samples,
nor were they aware that they were involved in a performance study. For
this study, each of five laboratories was sent three replicate rounds
of samples; each round consisted of three filters prepared with
respirable crystalline silica (Min-U-Sil 5) alone, three of silica
mixed with kaolin, three of silica mixed with soda-feldspar, and one
blank filter. The samples were prepared by RJ Lee Group and sent by a
third party to the laboratories as if they were field samples. All
laboratories were accredited by AIHA and analyzed the samples by XRD.
The samples were initially prepared on 5 [mu]m PVC filters;
however, due to sample loss during preparation, RJ Lee changed to 0.8
[mu]m PVC filters. It should be noted that the 2-propanol used to
suspend the Min-U Sil sample for deposition onto the 0.8 [mu]m filter
dissolved between 50 and 100 [mu]g of filter material, such that the
amount of minerals deposited on the filter could not be verified from
the post-deposition filter weights. In addition, two of the labs had
difficulty dissolving these filters in tetrahydrofuran, a standard
method used to dissolve PVC filters in order to redeposit the sample
onto silver membrane filters for XRD analysis. These labs were replaced
by two laboratories that used muffle furnaces to ash the filters before
redeposition, as did the other three labs originally selected.
Results reported from the labs showed a high degree of both intra-
and inter-laboratory variability as well as a systematic negative bias
in measured vs. applied silica levels, with mean reported silica values
more than 30 percent lower than the deposited amount. Across all
laboratories, mean results reported for filter loads of 20, 40, and 80
[mu]g were 13.36, 22.93, and 46.91 [mu]g, respectively (Document ID
2307, Attachment 14, pp. 5-6). In addition, laboratories reported non-
detectable results for about one-third of the silica samples (Document
ID 2307, Attachment 14, p. 7) and two blank filters sent to the labs
were reported to have silica present, in one case an amount of 52 [mu]g
(Document ID 2307, Attachment 14, pp. 9-10; 3582, Tr. 1995). Individual
CVs for the labs ranged from 20 to 66 percent, up to more than 3 times
higher than the CVs reported by OSHA or NIOSH for their respective
methods. After examining variability in reported results, the
investigators concluded that two-fold differences in filter load could
not be reliably distinguished in the concentration range of 25 to 100
[mu]g/m\3\ (Document ID 2307, Attachment 14, p. 14).
OSHA identifies several deficiencies in this study; these
deficiencies are sufficient to discredit the finding that high
variability in silica results can be attributed to the inability of the
analytical method to accurately measure crystalline silica at filter
loads representative of concentrations at the action level and PEL set
by this rule. Principally, the loss of filter material during
deposition of the samples, combined with the lack of any verification
of the actual amount of silica loaded onto the filters, makes it
impossible to use the laboratory results to assess lab performance
since the amount of silica on the filters analyzed by the labs cannot
be known. The large negative bias in lab results compared to the target
filter load implies that there was significant sample loss. In
addition, the quality control employed by RJ Lee to ensure that filter
loads were accurately known consisted only of an analysis of six
separately prepared samples to evaluate the recovery from the 0.8 [mu]m
PVC filter and two sets of filters to evaluate recovery and test for
shipping loss (Document ID 3461, Slides 8, 15, 16; 3582, Tr. 2090-
2091). This is in stark contrast to the procedures used by the AIHA PAT
program, which verifies its sample preparation by analyzing a
statistically adequate number of samples prepared each quarter to
ensure that sample variation does not exceed 10 percent
(Document ID 3586, Tr. 3276-3277). RJ Lee's use of the 0.8 [mu]m PVC
copolymer filter (Document ID 4001, Attachment 1) is also contrary to
the NIOSH Method 7500 (Document ID 0901), which specifies use of the 5
[mu]m PVC filter, and may have introduced bias. As stated at the
hearing by Mary Ann Latko of the AIHA Proficiency Analytical Testing
Programs, "[a]ny variance from the NIOSH method should not be
considered valid unless there's a sufficient quality control data
provided to demonstrate the reliability of the modified method"
(Document ID 3586, Tr. 3278).
OSHA finds that the AIHA PAT data are a far more credible measure
of inter-laboratory variation in crystalline silica measurement than
the ACC-sponsored RJ Lee study. Strict procedures are used to prepare
and validate sample preparation in accordance with ISO requirements for
conformity assessment and competence of testing in calibration
laboratories (Document ID 3586, Tr. 3275) and the database includes 200
rounds of silica testing since 2004, with 55 laboratories participating
in each round (Document ID 3586, Tr. 3264-3265). By comparison, the RJ
Lee study consisted of three rounds of testing among five laboratories.
One of the goals of the RJ Lee study was to conduct a double-blind
test so that laboratories would not know they were analyzing prepared
samples for proficiency testing; according to Mr. Bailey, a
laboratory's knowledge that they are participating in a performance
study, such as is the case with the AIHA PAT program, "can introduce
bias into the evaluation from the very beginning" (Document ID 3582,
Tr. 1989; Document ID 4209, p. 147). However, OSHA doubts that such
knowledge has a profound effect on laboratory performance. Accredited
laboratories participating in the PAT program undergo audits to ensure
that analytical procedures are applied consistently whether samples are
received from the field or from the PAT program. According to testimony
from Mr. Walsh:
[S]ite assessors [for the AIHA accreditation program] are very
sensitive to how PAT samples are processed in the lab. It's a
specific area that's examined, and if the samples are processed in
any way other than a normal sample, the laboratory is cited as a
deficiency (Document ID 3586, Tr. 3299-3300).
Therefore, after considering the evidence and testimony on the RJ
Lee study and AIHA PAT Program data, OSHA concludes that the AIHA PAT
data are the best available data on which to evaluate inter-laboratory
variability in measuring respirable crystalline silica. The data
evaluated by Harper et al. (2014) showed that laboratory performance
has improved in recent years resulting in greater agreement between
labs; mean RSD for the period 2003-2013 was 20.9 percent (Document ID
3998, Attachment 8, Figure 1). In addition, across the range of PAT
filter loadings, only about 5 percent of the samples resulted in lab
RSDs above 25 percent. At lower filter loads, 75 [mu]g or less, about
10 percent of samples resulted in RSDs above 25 percent Document ID
3998, Attachment 8, Figure 2). OSHA concludes that these findings
indicate general agreement between laboratories analyzing PAT samples.
Although laboratory performance has not been broadly evaluated at
filter loads below 40 [mu]g, particularly when interferences are
present, OSHA's investigations show that the XRD method is capable of
measuring crystalline silica at filter loads of 40 [mu]g or less
without appreciable loss of precision. The analysis of recent PAT data
by Harper et al. (2014, Document ID 3998, Attachment 8) shows that the
increase seen in inter-laboratory variation with lower filter loads
(e.g., about 50 and 70 [mu]g) is modest compared to the increase in
variation seen in the past from earlier PAT data, and the summary data
provided by AIHA (Document ID 4188) show that the average lab RSD for
samples with low filter loads is only a few percentage points above
average lab RSD across the full range of filter loads used in the PAT
program since 1999. OSHA finds that the studies of recent PAT data
demonstrate that laboratories have improved their performance in recent
years, most likely as a result of improving quality control procedures
such as were first proposed by Eller et al. (1999b, Document ID 1688,
pp. 23-24). Such procedures, including procedures concerning equipment
calibration, use of NIST standard reference material for calibration,
and strict adherence to published analytical methods, are required by
Appendix A of the final standards (29 CFR 1910.1053 and 29 CFR
1926.1153). According to Dr. Rosa Key-Schwartz, NIOSH's expert in
crystalline silica analysis, NIOSH worked closely with the AIHA
laboratory accreditation program to implement a silica emphasis program
for site visitors who audit accredited laboratories to ensure that
these quality control procedures are being followed (Document ID 3579,
Tr. 153). With such renewed emphasis being placed on tighter procedures
for crystalline silica analysis, OSHA finds that exposure monitoring
results being received from laboratories are more reliable than was
the case in years past and thus are deserving of greater confidence
from employers and workers.
f. Conclusion
Based on the record evidence reviewed in this section, OSHA finds
that current methods to sample respirable dust and analyze samples for
respirable crystalline silica by XRD and IR methods are capable of
reliably measuring silica concentrations in the range of the final
rule's PEL and action level. This finding is based on the following
considerations: (1) Several sampling devices are available that conform
to the ISO/CEN specification for particle-size selective samplers with
a level of bias and accuracy deemed acceptable by international
convention, and moving to the ISO/CEN convention will maintain
continuity with past practice, (2) both the XRD and IR methods can
measure respirable crystalline silica with acceptable precision at
amounts that would be collected by samplers when airborne
concentrations are at or around the PEL and action level, and (3)
laboratory proficiency data demonstrate that there is reasonable
agreement between laboratories analyzing comparable samples most of the
time.
There are several sampling devices that can collect respirable
crystalline silica in sufficient quantity to be measured by laboratory
analysis; some of these include the Dorr-Oliver nylon cyclone operated
at 1.7 L/min air flow rate, the Higgins-Dewell cyclones (2.2 L/min),
the SKC aluminum cyclone (2.5 L/min), and the GK2.69, which is a high-
flow sampler (4.2 L/min). Each of these cyclones can collect the
minimum amount of silica necessary, at the PEL and action level, for
laboratories to measure when operated at their respective flow rates
for at least four hours. In addition, each of these devices (as well as
a number of others) has been shown to conform to the ISO/CEN convention
with an acceptable bias and accuracy for a wide range of particle-size
distributions encountered in the workplace. OSHA used the Dorr-Oliver
at a flow rate of 1.7 L/min to enforce the previous PELs for respirable
crystalline silica, so specifying the use of sampling devices
conforming to the ISO/CEN convention does not reflect a change in
enforcement practice. The modest error that is associated with using
respirable dust samplers is independent of where the PEL is set, and
these samplers have been used for decades both by OSHA, to enforce the
preceding silica PEL (and other respirable dust PELs), and by employers
in managing silica-related risks. Therefore, OSHA finds that these
samplers are capable of and remain suitable for collecting respirable
dust samples for crystalline silica analysis.
Both XRD and IR analytical methods are capable of quantifying
crystalline silica with acceptable precision when air samples are taken
in environments where silica concentrations are around the PEL and
action level. OSHA's quality control samples analyzed by XRD over the
past few years show the precision to be about 20 percent over the range
of filter loads tested (about one-half to twice the former PEL). OSHA
conducted studies to characterize the precision of its Method ID-142 at
low filter loads representing the amounts that would be captured using
the Dorr-Oliver cyclone at the action level and PEL (i.e., 20 and 40
[mu]g, respectively), and found the precision, for quartz and
cristobalite, at both 20 and 40 [mu]g to be comparable to the precision
at the higher range of filter loads.
Evaluation of data from AIHA's Proficiency Analytical Testing
Program shows that results from participating laboratories are in
agreement (i.e., within 25%) most of the time. Performance between
laboratories has improved significantly in recent years, most likely
due to adoption of many of the quality control practices specified by
Appendix A of the final standards. Although precision declines as the
amount of crystalline silica in samples declines, the rate of decline
in precision with declining mass is less today than for prior years.
OSHA expects that increasing emphasis on improved quality control
procedures by the AIHA laboratory accreditation program (Document ID
3579, Tr. 153), the requirement in the final rule for employers to use
laboratories that use XRD or IR analysis (not colorimetric) and that
are accredited and conform to the quality control procedures of
Appendix A of the final standards, and increased market pressure for
laboratories to provide reliable results are likely to improve
agreement in results obtained by laboratories in the future.
Inter-laboratory variability has not been well characterized at
filter loads below 50 [mu]g, which is slightly more than would be
collected by a Dorr-Oliver cyclone sampling a silica concentration at
the PEL over a full shift. However, OSHA concludes that the studies
conducted by SLTC show that acceptable precision can be achieved by the
XRD method for filter loads obtained by collecting samples with the
Dorr-Oliver and similar devices at the action level and PEL. If
employers are concerned about the accuracy that their laboratory would
achieve at filter loads this low, samplers with higher flow rates could
be used to collect an amount of silica that falls within the working
range of the OSHA method and within the range of filter loads currently
used by the PAT program (i.e., 50 [mu]g or more). For example, either
the aluminum cyclone or HD will collect at least 50 [micro]g or more of
silica where concentrations are around the PEL, and the GK2.69 will
collect a sufficient quantity of crystalline silica where
concentrations are at least at the action level.
Based on the information and evidence presented in this section,
OSHA is confident that current sampling and analytical methods for
respirable crystalline silica provide reasonable estimates of measured
exposures. Employers should be able to rely on sampling results from
laboratories meeting the specifications in Appendix A of the final
standards to analyze their compliance with the PEL and action level
under the new silica rule; employers can obtain assurances from
laboratories or their industrial hygiene service providers that such
requirements are met. Similarly, employees should be confident that
those exposure results provide them with reasonable estimates of their
exposures to respirable crystalline silica. Thus, OSHA finds that the
sampling and analysis requirements under the final rule are
technologically feasible.
3. Feasibility Findings for the Final Permissible Exposure Limit of 50
[mu]g/m\3\
In order to demonstrate the technological feasibility of the final
PEL, OSHA must show that engineering and work practices are capable of
reducing exposures to the PEL or below for most operations most of the
time. Substantial information was submitted to the record on control
measures that can reduce employee exposures to respirable crystalline
silica, including but not limited to LEV systems, which could include
an upgrade of the existing LEV or installation of additional LEV;
process enclosures that isolate the employee from the exposure; dust
suppression such as wet methods; improved housekeeping; and improved
work practices. Substantial information was also submitted to the
record on the use of respiratory protection; while OSHA does not, as a
rule, consider the use of respirators when deciding whether an
operation is technologically feasible, it does, when it finds a
particular operation or task cannot achieve the PEL without respiratory
protection, require appropriate respirator use as a supplementary
control to engineering and work practice controls, when those controls
are not sufficient alone to meet the PEL.
OSHA finds that many engineering control options are currently
commercially available to control respirable dust (e.g., Document ID
0199, pp. 9-10; 0943, p. 87; 1607, p. 10-19; 1720, p. IV-237; 3791, p.
iii; 3585, p. 3073; 3585, p. 3072). These controls will reduce
employees' exposures to respirable crystalline silica when the
employees are performing the majority of tasks that create high
exposures. OSHA's finding is based on numerous studies, conducted both
in experimental settings in which the tools, materials and duration of
the task are controlled by the investigator, and in observational field
studies of employees performing their normal duties in the field. As
detailed in Chapter IV of the FEA, more than 30 studies were submitted
to the docket that report substantial reductions in exposure when using
controls compared with uncontrolled situations. The specific reports
that OSHA relied upon to estimate the range of reductions that can be
achieved through the implementation of engineering controls are
discussed in greater detail in the relevant sections of the
technological feasibility analyses.
Table VII-8 lists the general industry sectors included in the
technological feasibility analysis and indicates the numbers of job
categories in each sector for which OSHA has concluded that the final
PEL of 50 [mu]g/m\3\ is technologically feasible (see Chapter IV of the
FEA). As this table shows, OSHA has determined that the final rule's
PEL is feasible for all general industry sectors for the vast majority
of operations in these affected industry sectors (87 out of 90). For
only three general industry job categories, OSHA has concluded that
exposures to silica will likely exceed the final rule's PEL even when
all feasible controls are fully implemented; therefore, supplemental
respiratory protection will be needed in addition to those controls to
ensure that employees are not exposed in excess of the PEL for those
three categories. Specifically, supplemental use of respiratory
protection may be necessary for abrasive blasting operations in the
concrete products industry sector, cleaning cement trucks in the ready
mix concrete industry sector, and during abrasive blasting operations
in shipyards. In addition, in foundries, while finding that compliance
with the standard is overall feasible for all job categories, OSHA
recognizes that supplemental use of respiratory protection may be
necessary for the subset of employees who infrequently perform
refractory lining repair; for the small percentage of shakeout
operators, knockout operators, and abrasive blasters who work on large
castings in circumstances where substitution to non-silica granular
media is not feasible; and for maintenance operators performing
refractory patching where reduced silica refractory patching products
cannot be used.
OSHA has determined that some engineering controls are already
commercially available for the hydraulic fracturing industry, and other
controls that have demonstrated promise are currently being developed.
OSHA recognizes, however, that engineering controls have not been
widely implemented at hydraulic fracturing sites, and no individual PBZ
results associated with controls have been submitted to the record.
The available information indicates that controls for dust
emissions occurring from the sand mover, conveyor, and blender hopper
have been effective in reducing exposures. KSW Environmental reported
that a commercially-available control technology reduced exposures in
one test with all 12 samples below the NIOSH recommended exposure limit
(REL) of 50 [mu]g/m\3\ (Document ID 4204, p. 35, Fn. 21). KSW
Environmental also stated that four additional customer tests resulted
in 76 PBZ samples, all below 100 [mu]g/m\3\ (Document ID 4204, p. 35,
Fn. 21). Another manufacturer of a similar ventilation system (J&J
Bodies) reported that there was significantly less airborne dust
during the loading of proppant onto the sand mover when its dust
control system was used. This dust control system was used at
10 different hydraulic fracturing sites with reportedly good results
(Document ID 1530, p. 5).
These findings indicate that, with good control of the major dust
emission sources at the sand mover and along the conveyor to the
blender hopper, exposures can be reduced to at least 100 [mu]g/m\3\.
Use of other dust controls, including controlling road dust (reducing
dust emissions by 40 to 95 percent), applying water misting systems to
knock down dust released from partially-enclosed conveyors and blender
hoppers (reducing dust emissions by more than half), providing filtered
booths for sand operators (reducing exposure to respirable dust by
about half), reducing drop height at transfer points and hoppers, and
establishing regulated areas, will further reduce exposures to 50
[mu]g/m\3\ or below. Additional opportunities for exposure reduction
include use of substitute proppant, where appropriate, and development
and testing of dust suppression agents for proppant, such as that
developed by ARG (Document ID 4072, Attachment 35, pp. 9-10). OSHA
anticipates that once employers come into compliance with the preceding
PEL, the additional controls to be used in conjunction with those
methodologies to achieve compliance with the PEL of 50 [mu]g/m\3\ will
be more conventional and readily available.
Therefore, OSHA finds that the PEL of 50 [mu]g/m\3\ can be achieved
for most operations in the hydraulic fracturing industry most of the
time. As shown in Table IV.4.22-B of the FEA, this level has already
been achieved for almost one-third of all sampled workers (and nearly 1
in 5 sand fracturing workers, the highest exposed job category). OSHA
expects that the growing availability of the controls needed to achieve
the preceding PEL, along with further development of emerging
technologies and better use and maintenance of existing controls, will
reduce exposures to at or below the PEL for the remaining operations.
The American Petroleum Institute (API), the Marcellus Shale
Coalition (MSC), and Halliburton questioned whether the analysis of
engineering controls presented in the PEA was sufficient to demonstrate
the technological feasibility of reducing exposures to silica at
hydraulic fracturing sites to levels at or below 50 [mu]g/m\3\, in part
because the analysis did not include industry-specific studies on the
effectiveness of dust controls but largely relied instead on research
from other industries (Document ID 2301, Attachment 1, pp. 29, 60-61;
2302, pp. 4-7; 2311, pp. 2-3). These stakeholders argued that OSHA
needed to do significantly more data collection and analysis to show
that the PEL of 50 [mu]g/m\3\ is feasible for hydraulic fracturing
operations.
OSHA sought additional information on current exposures and dust
control practices. Throughout the NPRM and hearings, OSHA, as well as
other stakeholders, requested additional information on exposures and
engineering controls (Document ID 3589, Tr. 4068-4070, 4074-4078, 4123-
4124; 3576, Tr. 500, 534). Submissions to the record indicate that
significant efforts are currently being made to develop more effective
dust controls specifically designed for hydraulic fracturing (Document
ID 1530; 1532; 1537; 1538; 1570; 4072, Attachments 34, 35, 36; 4204, p.
35, Fn. 21). However, industry representatives provided no additional
sampling data to evaluate the effectiveness of current efforts to
control exposures. Thus, NIOSH and OSHA provided the only detailed air
sampling information for this industry, and summary data were provided
by a few rulemaking participants (Document ID 4204, Attachment 1, p.
35, Fn. 21; 4020, Attachment 1, p. 4).
When evaluating technological feasibility, OSHA can consider
engineering controls that are under development. Under section 6(b)(5)
of the OSH Act, 29 U.S.C. 655(b), OSHA is not bound to the
technological status quo and can impose a standard where only the most
technologically advanced companies can achieve the PEL even if it is
only some of the operations some of the time. Lead I (United
Steelworkers of Am., AFL-CIO-CLC v. Marshall, 647 F.2d 1189 (D.C. Cir.
1980)); Am. Iron & Steel Inst. v. OSHA, 577 F.2d 825 (3d Cir. 1978).
Relying on these precedents, the D.C. Circuit reaffirmed that MSHA and
OSHA standards may be "technology-forcing" in Kennecott Greens Creek
Min. Co. v. MSHA, 476 F.3d 946, 957, 960 (D.C. Cir. 2007), and that
"the agency is `not obliged to provide detailed solutions to every
engineering problem,' but only to `identify the major steps for
improvement and give plausible reasons for its belief that the industry
will be able to solve those problems in the time remaining.' " Id.
(finding that MSHA provided "more than enough evidence," including
"identif[ying] several types of control technologies that are
effective at reducing...exposure," to conclude that the industry
could comply with the two-year implementation date of a technology-
forcing standard) (citing Nat'l Petrochemical & Refiners Ass'n v. EPA,
287 F.3d 1130, 1136 (D.C. Cir. 2002)).
OSHA concluded that these technologies will enable the industry to
comply within five years. OSHA has described technologies that have
been developed and tested, and that have demonstrated that the PEL is
obtainable. These technologies have been developed to reduce exposures
to the preceding PEL, but some of them appear also to have the
capability to reduce some exposures to the PEL of 50 [micro]g/m\3\. KSW
Environmental has provided data that indicate exposures can be achieved
at or below the PEL (Document ID 1570, p. 22; 4204, Attachment 1, p.
35, Fn. 21; 4222, Attachment 2, p. 6), and NIOSH has presented concepts
of "mini-bag houses" that can be retrofitted on existing equipment
(Document ID 1537, p. 5; 1546, p. 10). SandBox Logistics, LLC, has
developed a shipping container for bulk transport of sand specifically
designed for hydraulic fracturing operations that eliminates the need
for sand movers, a major source of exposure to silica at fracturing
sites (Document ID 3589, Tr. 4148). OSHA views these and other advanced
controls discussed above as on the "horizon," but not currently
widely available for operational use (Am. Fed'n of Labor & Cong. of
Indus. Organizations v. Brennan, 530 F.2d 109, 121 (3d Cir. 1975)).
Once they are deployed, as explained fully in Chapter IV of the FEA,
more conventional adjustments and additional controls can be used with
them to lower exposures to the new PEL or below.
Evidence in the record shows widespread recognition of silica
exposure hazards on hydraulic fracturing sites and industry's efforts
to address them primarily through the efforts of the National Service,
Transmission, Exploration & Production Safety (STEPS) network's
Respirable Silica Focus Group. The STEPS network initiated action to
address exposure to silica at hydraulic fracturing sites in 2010, when
NIOSH first conducted air sampling and then publicized the severity of
hazardous silica exposures as part of its Field Effort to Assess
Chemical Exposures in Gas and Oil Workers (Document ID 1541).
Recognition of silica exposures in the industry well above the
preceding PEL of 100 [micro]g/m\3\ prompted the development of
engineering controls to reduce exposures to silica. While some
companies in the hydraulic fracturing industry are able to obtain and
implement controls to comply with the preceding PEL (e.g., Document ID
4204, Attachment 1, p. 35, Fn. 21), the technology is not currently widely
available. Given the progress that has been made since 2010, OSHA
concluded that these technologies will become more widely available and
enable the industry to comply with the final PEL within five years. As
noted by Kenny Jordan, the Executive Director of the Association of
Energy Service Companies (AESC), his organization's participation on
the National Occupational Research Agenda (NORA) NIOSH Oil and Gas
Extraction Council enabled members to be "at the forefront of building
awareness of the silica at the well site issue, particularly among
those working in fracking operations" (Document ID 3589, Tr. 4059). In
the five years since that time, the substantial progress in controlling
silica exposures at fracking sites described above has occurred.
In June 2012, the STEPS network, in which AESC and many other
industry, educational and regulatory entities participate, launched a
respirable silica focus group to spread awareness, better characterize
on-site silica exposures, and facilitate and evaluate the development
of engineering controls (Document ID 3589, Tr. 4059; 1537). This
enabled several manufacturers of engineering controls, such as KSW
Environmental (formerly Frac Sand Dust Control and Dupre) who had
developed a working model in 2009 (Document ID 1520), to collaborate
and share information on various engineering controls. As a
consequence, the silica control field has grown significantly during
this period, including the development, testing and, in some cases,
deployment of new technologies, including those from KSW Environmental,
J&J Truck Bodies, SandBox Logistics, and NIOSH's baghouse. For example,
John Oren, the co-inventor of the SandBox Logistics technology, said it
had taken his company only three years to develop the product and make
it commercially available (Document ID 3589, Tr. 4148). OSHA concludes
that an additional five years will be more than enough time for these
and other firms to complete development and increase manufacturing and
sales capacity, and, simultaneously, for hydraulic fracturing employers
to test, adopt and adapt these emerging technologies to their
workplaces. Indeed, in light of the progress that has already been
made, it may be more accurate to call the standard "market-
accelerating" than "technology-forcing."
During the rulemaking, API touted the efforts of this industry to
develop technology to protect workers against the hazards of silica
(Document ID 4222, Attachment 2, p. 9). OSHA agrees with API that these
efforts have been noteworthy and that more time is warranted to allow
for continued development, commercialization, and implementation of
these innovative technologies. OSHA is confident that with the
innovation displayed by this industry to date, the hydraulic fracturing
industry can further reduce worker exposures to the PEL if sufficient
time is provided. Therefore, OSHA is providing an extra three years
from the effective date of the standard--for a total of five years--to
implement engineering controls for the hydraulic fracturing industry.
OSHA concludes that this is ample time for this highly technical and
innovative industry to come into compliance with the final PEL. This is
consistent with, but longer than, the time frame OSHA granted for
implementation of engineering controls for hexavalent chromium, where
OSHA provided four years to allow sufficient time for some industries
to coordinate efforts with other regulatory compliance obligations as
well as gain experience with new technology and learn more effective
ways to control exposures (71 FR 10100, 10372, Feb. 28, 2006). Thus,
with the extra time provided for this industry to come into compliance,
OSHA finds that the final PEL of 50 [micro]g/m\3\ is feasible for the
hydraulic fracturing industry.
In the two years leading up to the effective date, the hydraulic
fracturing industry will continue to be subject to the preceding PEL in
29 CFR 1910.1000 (Table Z). In order to meet the preceding PEL of 100
[micro]g/m\3\ during this interim period, such compliance will include
adoption of the new engineering controls discussed above as they become
widely available for field use.\25\ As a result, OSHA expects many
exposures in hydraulic fracturing to be at or near the 50 [micro]g/m\3\
level ahead of the five-year compliance date due to the expected
efficacy of this new technology. Thus, with the extra time provided for
this industry to come into compliance, OSHA finds that the standard is
feasible for most workers in the Hydraulic Fracturing industry most of
the time.
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\25\ Compliance with Table Z requires implementing all feasible
engineering and administrative controls to achieve the PEL before
using protective equipment such as respirators. 29 CFR 1910.1000(e).
OSHA acknowledges that the technologies to meet the PEL in Table Z
are not currently widely available in the quantities needed for the
entire industry to achieve compliance. Accordingly, as employers
work toward implementing controls during the interim period,
supplemental respiratory protection may be necessary to comply with
the PEL of 100 [micro]g/m\3\. Likewise, during the additional three-
year phase-in period, OSHA anticipates that many employers may need
to use supplemental respiratory protection to comply with the PEL of
50 [micro]g/m\3\.
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OSHA has determined that a PEL of 50 [micro]g/m\3\ is
technologically feasible for the maritime industry. Although it is not
feasible to reduce painters' exposures to 50 [micro]g/m\3\ when
conducting abrasive blasting operations most of the time without the
use of respirators, evidence in the record demonstrates that it is
feasible to reduce painters' helpers' exposure to 50 [micro]g/m\3\ most
of the time with HEPA-filtered vacuums. As noted in Chapter IV of the
FEA, workers in the maritime industry may also be exposed during
foundry activities; as explained in FEA Chapter IV. Section 4.8.4--
Captive Foundries, OSHA has determined that it is feasible to reduce
exposures during most operations in captive foundries to 50 [micro]g/
m\3\, most of the time. The record evidence indicates that shipyard
foundries face similar issues controlling silica as other typical small
foundries (e.g., cleaning the cast metal) and that shipyard foundries
cast items in a range of sizes, from small items like a ship's plaque
to large items like the bow structure for an aircraft carrier (Document
ID 1145; 3584, Tr. 2607). OSHA did not receive comments indicating that
foundries in shipyards would require any unique controls to reduce
exposures, and therefore believes that exposures in shipyard foundries
can also be reduced to 50 [micro]g/m\3\ in most operations, most of the
time. Accordingly, OSHA has determined that 50 [micro]g/m\3\ is
feasible for most silica-related activities performed in the maritime
industry.
Even if captive foundries are excluded from consideration, OSHA
considers the standard to be feasible for shipyards with the use of
respirators by painters doing abrasive blasting. OSHA recognizes that,
consistent with its hierarchy of controls policy for setting methods of
compliance, respirator use is not ordinarily taken into account when
determining industry-wide feasibility. Neither this policy nor the
"most operations most of the time" formulation for technological
feasibility is meant to place OSHA in a "mathematical straitjacket"
(Indus. Union Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607, 655
(1980) ("Benzene") (stated with respect to the "significant risk"
finding, which the Supreme Court recognized is "based largely on
policy considerations" (Benzene, 448 U.S. at 655 n.62)). No court has
been confronted with a situation where an industry has two operations
(or any even number), of which one can achieve the PEL through
engineering controls and the other (or exactly half) can achieve it
most of the time only with the use of respirators. However, the same
court that formulated the "most operations most of the time" standard
"also noted that `[i]nsufficient proof of technological feasibility
for a few isolated operations within an industry, or even OSHA's
concession that respirators will be necessary in a few such operations,
will not undermine' a showing that the standard is generally feasible"
(Amer. Iron & Steel Inst. v. OSHA, 939 F.2d 975, 980 (D.C. Cir. 1991)
(Lead II), (quoting United Steelworkers of Am. AFL-CIO-CLC v. Marshall,
647 F.2d 1189, 1272 (D.C. Cir. 1980) ("Lead I")). It further
recognized the intended pragmatic flexibility of this standard by
stating that "[f]or example, if `only the most technologically
advanced plants in an industry have been able to achieve [the
standard]--even if only in some of their operations some of the time,'
then the standard is considered feasible for the entire industry"
(Lead II, 939 F. 2d at 980 (quoting Lead I, 647 F.2d at 1264)). In this
instance, OSHA has determined that it makes sense to treat painters
performing abrasive blasting in shipyards as an outlier for which the
PEL established for all other covered industries is feasible, even
conceding that respirators will be necessary. If abrasive blasting were
the predominant activity that occurs in shipyards, there might be
justification to set a separate, higher PEL for shipyards. But as in
construction (for which supplemental respirator use is also
contemplated for abrasive blasting operations), abrasive blasting is
one of many activities that occurs; substitution of non-silica blasting
materials is an option in many cases; few, if any, painters spend
entire days or weeks doing blasting operations and thus needing
respirators for the duration; and lowering the standard from 250
[micro]g/m\3\ to 50 [micro]g/m\3\ does not threaten the economic
viability of the industry. Under these circumstances, OSHA concludes
that it may find the standard feasible for shipyards rather than raise
the PEL for this single industry because it can only achieve the
uniform PEL with respirators or, alternatively, not be able to revise
the previous PEL of 250 [micro]g/m\3\ at all.
Table VII-9 lists the construction application groups included in
the technological feasibility analysis and indicates the numbers of
tasks in each application group. As this table shows, OSHA has
determined that the rule's PEL is feasible for the vast majority of
tasks (19 out of 23) in the construction industry. For those
construction tasks listed in Table 1 of paragraph (c) of the
construction standard, OSHA has determined that the controls listed on
Table 1 are either commercially available from tool and equipment
manufacturers or, in the case of jackhammers, can be fabricated from
readily available parts. Therefore, OSHA has determined that these
control requirements are technologically feasible and will, with few
exceptions, achieve exposures of 50 [mu]g/m\3\ or less most of the
time. Furthermore, Table 1 in paragraph (c) of the standard for
construction acts as a "safe harbor" in the sense that full and
proper implementation of the specified controls satisfies the
employer's duty to achieve the PEL, and the employer is under no
further obligation to do an exposure assessment or install additional,
non-specified controls. Thus, OSHA finds the operations listed in Table
1 to be technologically feasible for the vast majority of employers who
will be following the table.
Where available evidence indicates that exposures will remain above
this level after implementation of dust controls (see Chapter IV of the
FEA), Table 1 requires that respiratory protection be used. OSHA has
determined that available engineering and work practice controls cannot
achieve exposure levels of 50 [mu]g/m\3\ or less for only two
activities: Handheld grinders used to remove mortar (i.e.,
tuckpointing) and dowel drilling in concrete. For a few other
activities, OSHA concludes that respiratory protection will not
generally be needed unless the task is performed indoors or in enclosed
areas, or the task is performed for more than four hours in a shift.
Table 1 requires use of respiratory protection when using handheld
power saws indoors or outdoors more than four hours per shift; walk-
behind saws indoors; dowel drills in concrete; jackhammers or handheld
powered chipping tools indoors or outdoors more than four hours per
shift; handheld grinders for mortar removal; and handheld grinders for
uses other than mortar removal when used indoors for more than four
hours per shift.
OSHA has also evaluated the feasibility of three application groups
that do not appear on Table 1: Underground construction, drywall
finishing work, and abrasive blasting. For these operations, employers
will be subject to the paragraph (d) requirements for alternative
exposure control methods. Due in part to the complexity of excavating
machines, dust controls, and the ventilation systems required to
control dust for underground operations, OSHA decided not to include
underground construction and tunneling operations in Table 1 of
paragraph (c) of the construction standard. Nonetheless, OSHA has
determined that the PEL is technologically feasible in underground
construction because exposures can be reduced to 50 [micro]g/m\3\ or
less most of the time. Drywall finishing work was not included on Table
1 because silica-free drywall compounds are commercially available and
can be used to eliminate exposure to silica when finishing drywall. In
contrast to underground construction and drywall finishing, OSHA
decided that abrasive blasting was not suited to the Table 1 approach
because employers have several options in the control measures they can
implement when abrasive blasting based on their particular application.
For example, substitution to low-silica agent, use of wet blasting and
process enclosures are all possible control options for abrasive
blasting operations. Therefore, OSHA does not specify a specific
control for abrasive blasting suitable for all applications, unlike the
entries on Table 1 for tuckpointing and dowel drilling, where LEV is
the only option accompanied by required supplemental respirator use.
Furthermore, OSHA has existing requirements for abrasive blasting under
the ventilation standard for construction (29 CFR 1926.57). In certain
situations, that standard requires abrasive blasting operators to use
abrasive blasting respirators approved by NIOSH for protection from
dusts produced during abrasive blasting operations (29 CFR
1926.57(f)(5)(i) through (iii)). That standard also includes
specifications for blast-cleaning enclosures (29 CFR 1926.57(f)(3)),
exhaust ventilation systems (29 CFR 1926.57(f)(4)), air supply and air
compressors (29 CFR 1926.57(f)(6)), and operational procedures (29 CFR
1926.57(f)(7)). OSHA also has similar requirements for abrasive
blasting under the general industry standard (29 CFR 1910.94).
Therefore, OSHA expects that respiratory protection will be required to
be used during blasting operations under the paragraph (d) approach
that employers must follow when employees are doing this task.
The American Chemistry Council's (ACC's) Crystalline Silica Panel
contended that OSHA did not demonstrate that the proposed standard
would be technologically feasible in all affected industry sectors
because OSHA had failed to account for day-to-day environmental
variability in exposures (Document ID 4209, Attachment 1, p. 97). ACC
noted that OSHA enforces PELs as never-to-be-exceeded values and that
an employer can be cited based on a single measurement even if
most exposures on most days are below the PEL. Therefore, they
stated that to be "reasonably confident of complying with OSHA's
proposed PEL of 50 [mu]g/m\3\, the long-term average exposure in
most workplaces likely would have to be maintained at a level
below 25 [mu]g/m\3\ (or even below 20 [mu]g/m\3\)"
(Document ID 4209, p. 97; 2307, Attachment A, pp. 23-24, 160).
Representatives from the American Foundry Society (AFS) and the Asphalt
Roofing Materials Association (ARMA) made similar arguments (Document
ID 2291, p. 5; 3584, Tr. 2654-2655; 3580, Tr. 1282-1284, 1289).
OSHA recognizes the existence of exposure variability due to
environmental factors that can affect employee exposures, especially in
the construction industry where work sites and weather conditions can
change on a daily basis. OSHA has acknowledged this in past rulemakings
where the same issue was raised (e.g., benzene, 52 FR 34534; asbestos,
53 FR 35609; lead in construction, 58 FR 26590; formaldehyde, 57 FR
22290; cadmium, 57 FR 42102; and chromium (VI), 71 FR 10099). However,
not all exposure variation is due to random environmental factors;
rather, many high exposures are the result of predictable causes that
the employer can readily identify and address in efforts to improve
exposure control. Several studies were submitted to the docket that
used multivariate statistical models to identify factors associated
with increased exposure to silica during various construction
activities (Document ID 3608, 3803, 3956, 3998 Attachment 5h). These
studies reported that as much as 80 percent of the variability in
respirable quartz exposures could be attributed to various exposure
determinants included in the models, clearly indicating that not all
variability in exposure is uncontrollable. This was also attested to at
the hearing by Dr. Frank Mirer:
Exposures go up and down not by magic but by particular
conditions, differences in work methods, differences in control
efficiency, differences in adjacent operations (Document ID 3578,
Tr. 971).
OSHA concludes from the evidence in the record that the consistent
use of engineering controls will reduce exposure variability. By
improving or adding effective controls and work practices to reduce
employee exposures to the PEL or below, employers will reduce exposure
variability, and this reduction will provide employers with greater
confidence that they are in compliance with the revised PEL. OSHA does,
however, acknowledge that exposure controls cannot entirely eliminate
variability. Some day-to-day variability in silica exposure
measurements may remain, despite an employer's conscientious
application and maintenance of all feasible engineering and work
practice controls. Nonetheless, the legal standard for finding that a
PEL is technologically feasible for an industry sector is whether most
employers can implement engineering and work practice controls that
reduce exposures to the PEL or below most of the time. As explained in
Section XV, Summary and Explanation, in situations where exposure
measurements made by OSHA indicate that exposures are above the PEL,
and that result is clearly inconsistent with an employer's own exposure
assessment, OSHA will use its enforcement discretion to determine an
appropriate response. Moreover, for the vast majority of construction
employers (and some general industry or maritime employers doing tasks
that are "indistinguishable" from Table 1 tasks and choose to comply
with the construction standard), full compliance with Table 1 will
eliminate the risk that an employer will be subject to citation for
exposures above the PEL, even when the employer has instituted all
feasible controls that normally or typically maintain exposures below
the PEL.
OSHA also received a number of general comments on the feasibility
of wet methods and LEV, as well as comments on challenges faced when
employing these dust control strategies in specific work settings. In
general industry, several commenters indicated for specific industries
that there was no one control that could obtain the PEL of 50 [mu]g/
m\3\ (Document ID 2264, p. 36). CISC was also critical of several
aspects of OSHA's feasibility analysis. CISC commented that OSHA failed
to consider exposures from secondary or adjacent sources and that OSHA
should factor this into its analysis (Document ID 2319, p. 30; 4217, p.
13). Dr. Mirer also stated that many employees' silica exposures are
due to dust released from adjacent operations, but indicated that if
these dust releases are controlled, the exposures of workers in
adjacent areas will be substantially reduced (Document ID 4204, p.
104). In many industries, OSHA has shown that all sources of respirable
crystalline silica should be controlled and that often a combination of
controls may be needed to address potential sources of silica.
Additionally, addressing each source of exposure also reduces exposures
in adjacent areas, thus mitigating the concern about secondary
exposures expressed by both industry and union stakeholders.
Other commenters addressed the use of water on construction sites;
several commenters asserted that it is not always possible for
employers to use water for dust suppression. For example, in its post-
hearing submission, CISC discussed what it believed to be "significant
obstacles" to using wet dust suppression technologies on construction
sites. Such obstacles include freezing weather, which contraindicates
water use, and a lack of running water onsite, which requires employers
to deliver water, a practice which, according to CISC, is both "costly
and time consuming" (Document ID 4217, pp. 18-19). However, many other
participants commented that these barriers can be overcome. For
example, Phillip Rice, of Fann Contracting, Inc., uses water trucks to
haul water to sites and includes the cost of doing so in his bids. He
added that "when someone says they can't get water on their project
there is something wrong" (Document ID 2116, Attachment 1, p. 33).
Representatives of the International Union of Bricklayers and Allied
Craftworkers pointed out that water is essential for work in the
masonry trades and without it, no mortar can be mixed to set materials
(Document ID 3585, Tr. 3059-3060). They testified that, in their
experience, it was rare to work on sites that did not have water or
electricity available, but when they do, they bring in water trucks and
gas-powered generators to run saws (Document ID 3585, Tr. 3061-3063).
With respect to weather conditions, heated water or heated shelters can
be used if construction work is being performed in sub-freezing
temperatures (Document ID 3585, Tr. 3095-3096).
These comments and testimony indicate that the vast majority of the
barriers to wet dust suppression raised by CISC have already been
overcome in various construction settings. However, OSHA recognizes
that there will be limited instances where the use of wet dust
suppression is not feasible, particularly where its use can create a
greater hazard. For example, water cannot be used for dust control in
work settings where hot processes are present due to the potential for
steam explosions (Document ID 2291, p. 13; 2298, p. 3), nor can it be
used safely where it can increase fall hazards, such as on a roof
(Document ID 2214, p. 2). Nevertheless, OSHA finds that many employers
currently use wet dust suppression, that there are many commercially
available products with integrated water systems for dust suppression,
and that these products can be used in most work settings to control
exposures to respirable crystalline silica. In the limited cases where
dust suppression is not feasible, OSHA discusses the use of alternative
controls such as local exhaust ventilation and the supplemental
use of respiratory protection, as needed.
Some commenters questioned whether OSHA had adequately considered
the difficulties in complying with the PEL for maintenance activities.
The National Association of Manufacturers, for example, quoted one of
its members, who stated:
[t]here are occasional conditions where maintenance cleaning is
performed inside conveyor enclosures where the enclosure is
ordinarily a part of the dust control systems. This is just one
example of where a control would have to be breached in order to
properly maintain it as well as the operating equipment. It is
simply not technically feasible to establish engineering controls
for all possible maintenance activities (Document ID 2380,
Attachment 2, p. 1).
OSHA has addressed maintenance activities in each sector's
technological feasibility analysis, but the standard itself
acknowledges the difficulties of some maintenance activities. Paragraph
(g)(1)(ii) of the standard for general industry and maritime (paragraph
(e)(1)(ii)(B) in construction) requires respiratory protection "where
exposures exceed the PEL during tasks, such as certain maintenance and
repair tasks, for which engineering and work practice controls are not
feasible" (see the Summary and Explanation section on Respiratory
Protection for more information).
CISC submitted comments suggesting that the technological
feasibility analysis was incomplete because it did not cover every
construction-related task for which there is the potential for exposure
to silica dust. It listed more than 20 operations, including cement
mixing, cutting concrete pavers, demolishing drywall or plaster walls/
ceilings, overhead drilling, demolition of concrete and masonry
structures, and grouting floor and wall tiles, that it stated OSHA must
examine in order to establish feasibility, in addition to the
application groups already covered by OSHA's analysis (Document ID
2319, pp. 19-21). CISC asserted that, because of the many types of
silica-containing materials used in the construction industry, as well
as the presence of naturally occurring silica in soil, additional data
collection and analysis by OSHA should be conducted before promulgating
a final rule (Document ID 2319, pp. 25-26; 4217, p. 3).
As explained in the NPRM, OSHA's analysis for construction focuses
on tasks for which the available evidence indicates that significant
levels of respirable crystalline silica may be created, due primarily
to the use of powered tools or large equipment that generates visible
dust. OSHA notes that many of the examples of tasks for which CISC
requested additional analysis are tasks involving the tools and
equipment already covered in this feasibility analysis. For example,
overhead drilling is addressed in section IV-5.4 Hole Drillers Using
Handheld or Stand-Mounted Drills, and the demolition of concrete and
masonry structures is addressed in section IV-5.3 Heavy Equipment
Operators. In other cases, such as for concrete mixing, there are no
sampling data in the record to indicate that the task is likely to
result in 8-hour TWA exposures above the action level. Exposure can
occur when cleaning dried cement, and the feasibility of control
measures to reduce exposures when cleaning out the inside of cement
mixers is discussed in section IV-4.17 Ready Mix Concrete. Other tasks
listed by CISC involve working with wet or intact concrete, which is
unlikely to result in 8-hour TWA exposures above the action level.
Further, CISC did not submit to the record any air monitoring data to
support its assertion that these activities result in significant
exposures. Therefore, OSHA has not added these additional activities to
the feasibility analysis.
4. Feasibility Findings for an Alternative Permissible Exposure Limit
of 25 [mu]g/m\3\
In the NPRM, OSHA invited comment on whether it should consider a
lower PEL because it determined there was still significant risk at the
proposed PEL of 50 [mu]g/m\3\ (78 FR 56288, September 12, 2013). OSHA
has determined that the rule's PEL of 50 [mu]g/m\3\ is the lowest
exposure limit that can be found to be technologically feasible based
on the rulemaking record. Specifically, OSHA has determined that the
information in the rulemaking record either demonstrates that the
proposed alternative PEL of 25 [mu]g/m\3\ would not be achievable for
most of the affected industry sectors and application groups or the
information is insufficient to conclude that engineering and work
practice controls can consistently reduce exposures to or below 25
[mu]g/m\3\. Therefore, OSHA cannot find that the proposed alternative
PEL of 25 [mu]g/m\3\ is achievable for most operations in the affected
industries, most of the time.
The UAW submitted comments and data to the record, maintaining that
a PEL of 25 [mu]g/m\3\ is technologically feasible. As evidence, it
submitted exposure data from a dental equipment manufacturing plant and
two foundries (Document ID 2282, Attachment 3, pp. 7-8; 4031, pp. 3-8)
showing that exposures to silica in these establishments were
consistently below 25 [mu]g/m\3\ TWA. However, OSHA cannot conclude
that exposure data from three facilities is representative of the wide
array of facilities affected by the rule or sufficient to constitute
substantial record evidence that a PEL of 25 [mu]g/m\3\ is
technologically feasible in most operations most of the time.
Although available exposure data indicate that exposures below 25
[mu]g/m\3\ have already been achieved for most employees in some
general industry sectors and construction application groups (e.g.,
dental laboratories, jewelry, and paint and coatings in general
industry, and drywall finishers and heavy equipment operators
performing excavation in construction), the relatively low exposures
can be attributed to the effective control of the relatively small
amounts of dust containing silica generated by employees in these
industries and application groups. Further extrapolation to other
sectors or groups with higher baseline exposures or more challenging
control situations is not warranted, however.
For most of the industries and application groups included in this
analysis, a review of the sampling data indicates that an alternative
PEL of 25 [mu]g/m\3\ cannot be achieved with engineering and work
practice controls. OSHA finds that engineering and work practice
controls will not be able to consistently reduce and maintain exposures
to an alternative PEL of 25 [mu]g/m\3\ in the sectors that use large
quantities of silica containing material, including foundries (ferrous,
nonferrous, and non-sandcasting), concrete products, and hydraulic
fracturing, or have high energy operations, such as jackhammering and
crushing machines.
For instance, in the ferrous foundry industry, the baseline median
exposure in the profiles exceeds 50 [mu]g/m\3\ for 6 of the 12 job
categories analyzed: Sand system operators, shakeout operators,
abrasive blasting operator, cleaning/finishing operators, maintenance
operators, and housekeeping employees. OSHA concluded that engineering
and work practice controls can reduce TWA exposures to 50 [mu]g/m\3\ or
less for most of these operations most of the time. However, because
large amounts of silica-containing sand is transported, used, and
recycled to create castings, OSHA cannot conclude that available
controls can reduce exposures to or below 25 [mu]g/m\3\ in any step of
the production process. Additionally, high energy operations in foundries
can create concentrations of respirable silica above 25 [mu]g/m\3\. For
example, the shakeout process is a high energy operation using
equipment that separates castings from mold materials by mechanically
vibrating or tumbling the casting. The dust generated from this process
causes elevated silica exposures for shakeout operators and often
contributes to exposures for other employees in a foundry. The
effectiveness of dust controls on shakeout operations was demonstrated
at three foundries that implemented various dust controls in the
shakeout area (e.g., shakeout enclosure added, ventilation system
improved, conveyors enclosed and ventilated); full-shift samples taken
by or for OSHA measured exposures for shakeout operators ranging from
less than or equal to 13 [mu]g/m\3\ to 41 [mu]g/m\3\ (Document ID 1365,
pp. 2-51; 1407, p. 20; 0511, p. 2). These readings were obtained in
foundries that had made a systematic effort to identify and abate all
sources of dust emission with the establishment of an abatement team
consisting of an engineer, maintenance and production supervisors, and
employees. TWA exposures for the shakeout operators were reduced to
less than 50 [mu]g/m\3\, but two of the four measurements in this well-
controlled facility exceeded 25 [mu]g/m\3\ (see Chapter IV 4.8.1 of the
FEA). Other industry sectors that use substantial quantities of
crystalline silica as a raw material include refractories, glass
products, mineral processing, structural clay and cement products. OSHA
finds that the available evidence on exposures at facilities in these
industries in which controls have been implemented indicates most
exposures are typically between 25 [mu]g/m\3\ and 50 [mu]g/m\3\.
For other general industry sectors, OSHA has insufficient data to
demonstrate that engineering and work practice controls will reduce
exposures to or below 25 [mu]g/m\3\ most of the time (see Chapter IV of
the FEA). For example, it is not evident that exposures can be reduced
to 25 [mu]g/m\3\ for four out of five jobs analyzed in the pottery
sector, for two out of three job categories in the structural clay
sector, and for two jobs in the porcelain enameling sector.
OSHA has also determined that application groups in construction
that use large quantities of silica containing material or involve high
energy operations will not be able to consistently achieve 25 [mu]g/
m\3\ (e.g. tuck pointing/grinding and rock and concrete drilling).
These operations cause employees to have elevated exposures even when
available engineering and work practice controls are used. Examples
include using jackhammers during demolition of concrete and masonry
structures, grinding concrete surfaces, using walk-behind milling
machines, operating rock and concrete crushers, and using portable saws
to cut concrete block. For instance, jackhammering is a high energy
operation and OSHA finds that when employees perform this operation for
four hours or less in a shift, most employees using jackhammers
outdoors experience levels at or below 50 [mu]g/m\3\ TWA but not
reliably at or below 25 [mu]g/m\3\. The use of portable cut-off saws (a
type of handheld power saw) is also a high energy operation that can
lead to exposures over 25 [mu]g/m\3\. Due to energy applied to the
material being cut from the rapid rotation of the circular blade, the
dust generated can be difficult to control; available data indicate
that exposures will often exceed 25 [mu]g/m\3\ TWA, even when the
portable cut-off saw is used with water for dust suppression. Evidence
in the record indicates that, for most of the other construction
operations examined, use of feasible engineering and work practice
controls will still result in frequent exposures above 25 [mu]g/m\3\.
For other tasks in construction application groups, OSHA has
insufficient data to demonstrate that engineering and work practice
controls will reduce exposures to or below 25 [mu]g/m\3\ most of the
time (see Chapter IV of the FEA).
Therefore, OSHA concludes that 50 [mu]g/m\3\ as an 8-hour TWA is
the lowest feasible exposure limit that the record demonstrates can be
applied to most general industry, maritime, and construction operations
without the excessive use of respirators. OSHA also concludes that it
would hugely complicate both compliance and enforcement of the rule if
it were to set a PEL of 25 [mu]g/m\3\ for a minority of industries or
operations where it would be technologically feasible and a PEL of 50
[mu]g/m\3\ for the remaining industries and operations where
technological feasibility at the lower PEL is either demonstrably
unattainable, doubtful or unknown. OSHA is not under a legal obligation
to issue different PELs for different industries or application groups,
but may exercise discretion to issue a uniform PEL if it determines
that the PEL is technologically feasible for all affected industries
(if not for all affected operations) and that a uniform PEL would
constitute better public policy (see Section II, Pertinent Legal
Authority (discussing the chromium (VI) decision)). In declining to
lower the PEL to 25 [mu]g/m\3\ for any segment of the affected
industries, OSHA has made that determination here.
E. Costs of Compliance
Overview
This section assesses the costs to establishments in all affected
industry sectors of reducing worker exposures to silica to an 8-hour
time-weighted average (TWA) permissible exposure limit (PEL) of 50
[mu]g/m\3\--or, alternatively, for employers in construction to meet
the Table 1 requirements--and of complying with the standard's
ancillary requirements. This cost assessment is based on OSHA's
technological feasibility analysis presented in Chapter IV of the FEA;
analyses of the costs of the standard conducted by OSHA's contractor,
Eastern Research Group; testimony during the hearings; and the comments
submitted to the docket as part of the rulemaking process.
OSHA estimates that the standard will have a total cost of $1,029.8
million per year in 2012 dollars. Of that total, $370.8 million will be
borne by the general industry and maritime sectors, and $659.0 million
will be borne by the construction sector. Costs originally estimated
for earlier years in the PEA were adjusted to 2012 dollars using the
appropriate price indices. In general, all employee and supervisor
wages (loaded) were from the 2012 BLS OES (Document ID 1560); medical
costs were inflated to 2012 dollars using the medical services
component of the Consumer Price Index; and, unless otherwise specified,
all other costs were inflated using the GDP Implicit Price Deflator
(Document ID 1666).
All costs were annualized using a discount rate of 3 percent,
which--along with 7 percent \26\--is one of the discount rates
recommended by OMB. Annualization periods for expenditures on equipment
are based on equipment life, while there is a 10-year annualization
period for one-time costs. Note that the benefits of the standard,
discussed in Section VII.G of this preamble and in Chapter VII of the
FEA, were annualized over a 60-year period to reflect the time needed
for benefits to reach steady-state values. Therefore, the time horizon
of OSHA's complete analysis of this rule is 60 years. Employment and
production in affected industries are being held constant over this time
horizon for purposes of the analysis. All non-annual costs are estimated
to repeat every ten years over the 60-year time horizon, including one-time
costs that recur because of changes in operations over time or because of
new entrants that must comply with the standard.\27\ Table VII-10 shows, by
affected industry in the sectors of general industry and maritime,
annualized compliance costs for all establishments, all small entities
(as defined by the Small Business Act and the Small Business
Administration's (SBA's) implementing regulations; see 15 U.S.C. 632
and 13 CFR 121.201), and for all very small entities (those with fewer
than 20 employees). Table VII-11 similarly shows, by affected industry
in construction, annualized compliance costs for all entities, all
small entities, and all very small entities. Note that the totals in
these tables and all other tables in this chapter, as well as totals
summarized in the text, may not precisely sum from underlying elements
due to rounding.
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\26\ Appendix V-D of the FEA presents costs by NAICS industry
and establishment size category using, as alternatives, both a 7
percent discount rate and a 0 percent discount rate. In the
sensitivity analysis presented in Chapter VII of the FEA, OSHA
compares the estimated cost of the rule using the 3 percent discount
rate to the estimated cost using these alternative discount rates.
\27\ To the extent one-time costs do not recur, OSHA's cost
estimates, when expressed as an annualization over a 10-year period,
will overstate the cost of the standard.
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OSHA's exposure profile, presented in Chapter III of the FEA,
represents the Agency's best estimate of current exposures (i.e.,
baseline exposures). Except for compliance with Table 1 in
construction, OSHA did not attempt to determine the extent to which
current exposures in compliance with the new silica PEL are the result
of baseline engineering controls or the result of other circumstances
leading to low exposures. This information is not needed to estimate
the costs of (additional) engineering controls needed to comply with
the new PEL, but it is relevant to estimate the costs of complying with
Table 1 in construction.
For both construction and general industry/maritime, the estimated
costs for the silica rule represent the additional costs necessary for
employers to achieve full compliance with the new standard, assuming
that all firms are compliant with the previous standard. Thus, the
estimated costs do not include any costs necessary to achieve
compliance with previous silica requirements, to the extent that some
employers may not be fully complying with previously-applicable
regulatory requirements. OSHA almost never assigns costs for reaching
compliance with an already existing standard to a new standard
addressing the same health issues. Nor are any costs associated with
previously-achieved compliance with the new requirements included.
Because of the severe health hazards involved, as well as current
OSHA regulation, the Agency expects that the estimated 11,640 abrasive
blasters in the construction sector and the estimated 3,038 abrasive
blasters in the maritime sector are currently wearing respirators as
required by OSHA's abrasive blasting provisions (29 CFR 1915.154
(referencing 29 CFR 1910.134)). Furthermore, an estimated 264,761
workers, including abrasive blasters, will need to use respirators at
least once during a year to achieve compliance with the new silica rule
in construction, and, based on the NIOSH/BLS respirator use survey
(NIOSH/BLS, 2003, Document ID 1492), an estimated 56 percent of
construction employees whose exposures are high enough that they will
need respirators under the new rule currently use such respirators.
OSHA therefore estimates that 56 percent of affected construction
employees already use respirators in compliance with the respirator
requirements of the final silica rule.
Other than respiratory protection, OSHA did not assume baseline
compliance with any other ancillary provision, even though some
employers have reported that they currently monitor silica exposure,
provide silica training, and conduct medical surveillance.
The remainder of this chapter is organized as follows. First, unit
and total costs by provision are presented for general industry and
maritime and for construction. Following that, the chapter concludes
with a summary of the estimated costs of the rule for all affected
industries.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
1. Engineering Controls
a. General Industry and Maritime
The engineering control section in Chapter V of the FEA covers
OSHA's estimates of engineering control costs for general industry and
maritime sectors. Oil and natural gas fracturing operations are
addressed separately because OSHA used a different methodology to
estimate engineering control costs for this application group. This
section will address OSHA's overall methodology, the methodology for
each category of costs (such as ventilation, housekeeping, conveyors),
issues specific to small entities, and issues specific to the hydraulic
fracturing industry. Within each of these discussions, this section
summarizes the methodology used in the PEA to estimate engineering
control costs, summarizes and responds to the comments on the PEA, and
summarizes the changes made to the methodology used in the PEA for the
FEA. Finally, the chapter presents OSHA's final estimates of
engineering control costs.
Introduction
The PEA's technological feasibility analysis identified the types
of engineering controls that affected industries or sectors would need
in order to control worker exposures to at or below the proposed PEL of 50
[mu]g/m\3\. Through its contractor, Eastern Research Group (ERG),
OSHA generated cost estimates for those controls using product
and technical literature, equipment vendors, industrial engineers,
industrial hygienists, and other sources, as relevant to each item.
Wherever possible, objective cost estimates from recognized technical
sources were used. Specific sources for each estimate were presented
with the cost estimates.
Table V-4 of the PEA provided a list of possible controls on an
industry-by-industry basis and included details on control
specifications and costs. The basic information for the types of
controls needed was taken from the PEA's technological feasibility
analysis. The following discussion explains how OSHA developed and used
these estimates to prepare the aggregate costs of engineering controls
presented in the PEA.
In developing engineering control cost estimates for the PEA, OSHA
made a variety of estimates about the size or scope of the engineering
or work practice changes necessary to reduce silica exposures in
accordance with the proposed rule. In some cases, OSHA estimated that
employers would need to install all new engineering controls. In other
cases, though, employers were expected to only need to add additional
ventilation capacity or improve maintenance for existing equipment. In
these cases, the costs were based on judgments of the amount of
incremental change (either additional capacity or additional
maintenance work) required per year. These estimates of the size or
scope of the necessary engineering or work practice changes reflected
representative conditions for the affected workers based on technical
literature (including National Institute for Occupational Safety and
Health (NIOSH) Health Hazard Evaluations), judgments of knowledgeable
consultants and industry observers, and site visits. A detailed list of
the specific costing assumptions and information sources for each
control, grouped by job category or industry sector, was shown in PEA
Appendix V-A, Table V-A-1.
In order to estimate costs in a consistent manner, OSHA, in the
PEA, estimated all costs on an annualized basis. For capital costs,
OSHA calculated the annualized capital cost, using a three percent
discount rate over the expected lifetime of the capital item. The
capital costs for long-lasting capital items (such as ventilation
system improvements) were annualized over ten years. OSHA estimated
that, in the general industry and maritime sectors, any capital
expenditure would also entail maintenance costs equal to ten percent of
the value of the capital investment annually.
General Methodology
General Methodology: Per-Worker Basis and Treatment of Overexposures
for Cost Calculations
PEA Estimates
OSHA, in the PEA, estimated control costs on a per-worker basis.
Costs were related directly to the estimates of the number of workers
needing controls (i.e., workers exposed over 50 [mu]g/m\3\). OSHA
divided engineering control costs into two categories: (1) Those only
needed by establishments with employees exposed to levels of silica
that exceeded the preceding general industry PEL of 100 [mu]g/m\3\; and
(2) those applicable to all establishments where workers were exposed
to levels of silica above the proposed PEL (whether just above 50
[mu]g/m\3\ or also above 100 [mu]g/m\3\). It should be noted that the
maritime sector has been subject to a different preceding PEL of 250
[mu]g/m\3\. The PEA estimates were presented in the PEA cost analysis
tables. The overwhelming majority of the costs (90 percent of all
engineering control costs and 85 percent of costs associated with
meeting the preceding PEL of 100 [mu]g/m\3\) were associated with the
second category (controls applicable to all establishments with
exposures above the proposed or preceding PEL). Because OSHA is not
accounting for the costs of controls necessary to reach the preceding
PEL, the PEA focused on controls that may be needed to meet the new
PEL. OSHA derived per-worker costs by examining the controls needed for
each job category in each industry and dividing the cost of that
control by the number of workers whose exposures would be reduced by
that control. OSHA then multiplied the estimated per-worker control
cost by the number of workers exposed between the proposed (new) PEL of
50 [mu]g/m\3\ and the preceding PEL of 100 [mu]g/m\3\. The numbers of
workers in this category were based on the exposure profiles for at-
risk occupations developed in the technological feasibility analysis in
Chapter IV of the PEA and the estimates of the number of workers
employed in these occupations were developed in the industry profile in
Chapter III of the PEA. The exposure profile information was determined
to be the best available data for estimating the need for incremental
controls on a per-worker basis.
In general, in the PEA, OSHA inferred the extent to which exposure
controls were already in place from the distribution of overexposures
among the affected workers. Thus, if most exposures in a facility were
above the preceding PEL, OSHA broadly interpreted this as a sign of
limited or no controls, and if most exposures were below the proposed
(new) PEL of 50 [mu]g/m\3\, this would be indicative of having adequate
controls in place. OSHA calculated the costs of controls per exposed
worker in each job category and assigned this cost to the total number
of employees exposed between the proposed (new) PEL and the preceding
PEL. For example, if a control cost $1,000 per year and covered 4
employees, the cost per employee would be $250 per year. If 100
employees in the job category were exposed between the preceding and
proposed (new) PEL, then the total costs would be $250 times 100
employees or $25,000. No costs were estimated for employees currently
exposed above the preceding PEL or below the proposed (new) PEL.
OSHA determined that multiple controls would be needed for almost
all jobs in general industry in order reduce exposures from baseline
conditions to meeting the proposed (new) PEL of 50 [mu]g/m\3\. Some of
these controls cover a group of workers, while others might be
individualized (such as daily housekeeping by each individual worker).
Comments on the Per-Worker Basis and Proportionality of Costs
URS, speaking for the American Chemistry Council (ACC), argued that
OSHA's approach underestimated the costs of controls because it based
costs on controls per worker instead of controls per facility (Document
ID 2307, Attachment 8, p. 4). Since OSHA did not provide a distribution
of exposures by facility or provide facility-specific information, URS
used data in the record to create its own models to account for
facility size. URS described its approach as follows:
URS created three statistical binomial distributions of
overexposed workers, one for each of the three facility sizes, using
OSHA's estimate of the percentage of over-exposed workers for that
job. The result was a binomial distribution curve indicating the
percentage of overexposed workers for each job category for each
size-specific "model facility."
For each binomial distribution, the peak of the distribution
curve centers on the average number of overexposed workers per
facility for that job description according to OSHA's estimate
(Document ID 2307, Attachment 8, p. 7).
In taking this approach, URS erroneously assumed that the
distribution of overexposed workers per facility was random, as
evidenced by its use of a binomial distribution to approximate
overexposures per facility within each of three facility sizes
(Document ID 2307, Attachment 8, p. 7). Examination of the spreadsheet
URS provided shows that this approach approximately doubles the number
of controls needed and, and for this reason, doubles the total cost of
engineering controls (Document ID 2307, Attachment 26, Table 2A, URS
Summary Worksheet).
OSHA disagrees with URS's implicit conclusion that overexposures
are random across facilities. It is not reasonable to assume that
controls have no relation to exposure level as this approach assumes.
As will be discussed later in the context of OSHA's treatment of the
preceding PEL, the data underlying the exposure profile show that
establishments with low exposures are much more likely to have controls
in place than those with very high exposures.
URS then assumed that if one worker in a job category is
overexposed, then all controls listed by OSHA will be needed (Document
ID 2307, Attachment 25, Engineering Costs). URS did not dispute that
multiple controls would be needed for almost all jobs in general
industry in order reduce exposures from baseline conditions to meeting
the proposed (new) PEL of 50 [mu]g/m\3\. The existence of multiple
controls weakens the theory suggested by URS--that all controls are
needed if even one worker is exposed at levels above the PEL--because
as explained above, some controls are individualized while some protect
groups of workers.
The best possible approach to what engineering controls are needed
might differ based on whether: (1) There are no controls for a job
category in place at all and most workers are overexposed by a large
margin; or (2) only some workers in a job category are overexposed by a
small margin (i.e., a set of controls is already in place).
In the first case, the most common approach would be to apply a
relatively full set of controls, as explained in OSHA's technological
feasibility analysis. This might start with enclosures and local
exhaust ventilation (LEV), but, if exposures are high and the
establishment is very dusty, it might also include initial cleaning or
the introduction of ongoing routine housekeeping. In these situations,
in which most employees are overexposed, OSHA estimated that the full
set of controls listed in the technological feasibility analysis would
be applied and, in these cases, there would be little difference in the
results obtained using OSHA's approach and the results obtained using
the approach suggested by URS.
However, the approach to controlling silica exposures that OSHA
believes to be typical when establishments are faced with the second
situation would be quite different, and therefore different from what
URS expected. Commenters from both labor (Document ID 4204, p. 40) and
industry (Document ID 1992, p. 6) pointed out that when there are
controls in place or only some workers are overexposed, the first step
is to examine work practices. The AFL-CIO noted that exposures can be
controlled through work practices, repositioning ventilation systems,
and controlling fugitive emissions (carryover from adjacent silica
emitting processes) (Document ID 4204, p. 40). Implementing these types
of changes can be inexpensive. The principal cost of improving work
practices may only be training or retraining workers in appropriate
work practices. OSHA's proportional cost approach in the PEA may
therefore overestimate costs for situations in which overexposures can
be corrected with work practice changes because the Agency will have
included costs for engineering controls when, in fact, none will be
needed. The URS approach will always include the costs of all controls
for a job category in any facility where anyone in a job category is
overexposed, and will thus yield even higher estimates.
As described in Chapter IV, Technological Feasibility, of the FEA,
and summarized below, in situations in which there are LEV systems in
place but the PEL is still not being met, employers would typically try
many things short of removing the entire system and replacing it with a
system with greater air flow velocities (and thus greater capacity and
cost). The incremental solutions to controlling silica exposures
include minor design modification of existing controls, better repair
and maintenance of existing controls, adding additional LEV capacity to
existing systems, improving housekeeping, modifying tools or machinery
causing high levels of emissions, and reducing cross contamination.
Some worksites might require a slightly different and readily
modified design. For example, an OSHA special emphasis program
inspection of a facility in the Concrete Products industry discovered
that installing a more powerful fan motor, installing a new filter bag
for the bag-filling machine LEV, and moving hoods closer to the packing
operator's position reduced respirable dust exposure by 92 percent, to
11 [mu]g/m\3\ (Document ID 0126, pp. 7-8). In an assessment of the
Asphalt Roofing industry, NIOSH recommended repair and servicing of
existing process enclosures and ventilation systems to eliminate leaks
and poor hood capture but did not indicate that entirely new systems
would need to be installed (Document ID 0889, pp. 12-13; 0891, pp. 3
and 11; 0890, p.14; 0893, p. 12).
In other cases, better equipment repair and maintenance procedures
can be the key to meeting the PEL when there are already controls in
place. For example, as described in Chapter IV of the FEA, in the
Concrete Products industry, OSHA obtained a sample of 116 [mu]g/m\3\
for a material handler who operated a forklift to transport product
between stations. The inspector noted that there were leaks in the silo
bin chute and that some controls were not fully utilized. The report
indicated that dust generated by various other processes in the
facility was a contributing factor to the forklift operator's high
level of exposure. In this case, the first course of action for the
employer would be to correct the deficiencies in the existing systems.
Similarly, at a site visit in the Paint and Coating industry, ERG
monitored mixer operators' exposures and obtained results below the
limit of detection while workers emptied 50-pound bags of powder into
hoppers when dust control systems were working properly. These values
are 95 percent lower than the 263 [mu]g/m\3\ obtained during another
shift, at the same plant, when the dust control systems malfunctioned
(Document ID 0199, p. 9).
In other cases, as pointed out by a foundry commenter, adding LEV
capacity to existing systems for silica emissions not yet subject to
any LEV control can be a good strategy for lowering exposures (Document
ID 1992, p. 6). In one foundry, NIOSH investigators recommended
installation of LEV over the coater and press areas, enclosure of the
coating process, and/or repair and servicing of existing process
enclosures and ventilation systems to eliminate leaks and poor hood
capture (Document ID 0889, pp. 12-13; 0891, pp. 3 and 11; 0890, p. 14;
0893, p. 12).
Various combinations of improved housekeeping, initial cleaning,
and switching to High-Efficiency Particulate Air (HEPA) vacuums can
also help employers meet the PEL. In the Structural Clay industry,
professional cleaning in a brick manufacturing facility removed
"several inches" of dust from floors, structural surfaces and
equipment (Document ID 1365, pp. 3-19-3-20; 0571). These changes alone
led to a dramatic decrease in exposures, by as much as 90 percent, to below
50 [mu]g/m\3\, for materials handlers. Similar results were observed
for grinding operators (Document ID 0571). In one NIOSH evaluation,
operators in a grinding area where good housekeeping practices were
being implemented had substantially lower exposures than operators in a
grinding room where the housekeeping practices were poor. The grinding
room referred to as the "C plant" had 2 to 3 inches of settled dust
on the floor and had an exposure result of 144 [mu]g/m\3\. Grinding
operators at the grinding room referred to as the "B plant," where
dust had been cleaned up, had substantially lower exposures (24 [mu]g/
m\3\) (Document ID 0235, pp. 6-7).
Good housekeeping also increases the useful life of equipment. As
discussed in Chapter IV of the FEA, dust clogs machines and reduces
their useful life. As an example, regulating cotton dust was
acknowledged to increase productivity by reducing down time. It also
increased the useful life of looms (Document ID 2256, Attachment 4, p.
11). The Agency predicts that this is likely to be the case with silica
controls as well. Dust being properly captured at the source can also
result in cost savings in housekeeping activities because less dust
needs to be cleaned up when it is captured at the source and not
allowed to spread (Document ID 2256, Attachment 4, p. 11).
In specific situations, there are a variety of other controls that
may be useful. As discussed in the Technological Feasibility chapter of
the FEA, Simcox et al. (1999) (Document ID 1146) found that Fabricators
in the Cut Stone industry had a mean exposure of 490 [mu]g/m\3\, which
was reduced 88 percent to 60 [mu]g/m\3\ when dry grinding tools used on
granite were replaced or modified to be water-fed. Similar reductions
were found at other facilities when wet grinding, polishing, and
cutting methods were adopted (Document ID 1365, p. 11-20; 1146, p.
579). In the technological feasibility chapter, OSHA examined the work
practices of cut stone splitters and chippers and found that a
combination of wetting the floor at appropriate times, modifying
ventilation directly from the top of the saws, and retrofitting
splitting stations with LEV reduced exposures from a mean of 117 [mu]g/
m\3\ to a mean of 18 [mu]g/m\3\, an 85 percent reduction (Document ID
1365, p. 11-22; 0180).
Finally, in situations where there is cross contamination,
employers may achieve the PEL for some workers without implementing any
controls specific to that job category. As pointed out by the AFL-CIO,
when this occurs, OSHA's costs may be overestimated (Document ID 4204,
Attachment 1, p. 105).
These examples show that in many situations, where there are
already controls in place, or where exposures are only slightly above
the PEL, the PEL can be met by a variety of mechanisms short of
installing an entirely new set of controls. Since the record shows
that, frequently, exposures can be controlled without installing new
engineering controls, OSHA's approach of estimating costs based on the
proportion of the workers exposed above the PEL is much more likely to
be accurate than estimates based on URS's suggestion that all controls
are needed whenever one worker is exposed above the PEL.
The URS facility-based approach would require taking the costs of
newly installing a full set of controls even if only one worker is
exposed above the PEL. This approach assumes that (1) the existing
exposure levels in a given facility have been achieved without the use
of any controls; and (2) existing controls cannot be improved upon for
less than the cost of installing an entirely new system of controls.
These assumptions are unsupported by the URS comments and the nature of
exposure control, as discussed above.
OSHA, therefore, rejects URS's approach and is maintaining its per-
worker basis for calculating costs for the FEA. Based on the evidence
presented in this section, the Agency concludes that OSHA's
proportional approach of assigning control costs to each worker based
on the cost per worker of a complete set of controls is a better
approach to commonly encountered exposure situations than to assume
that any reading above the PEL triggers the need for a complete set of
controls.
The AFL-CIO argued that OSHA's proportional approach resulted in an
over-estimation of costs because it involved adding costs for the
exposed occupation wherever there was an overexposure, even when the
overexposure was primarily or solely the result of cross contamination.
The AFL-CIO recommended that OSHA "identify operations which are
unlikely to [generate] silica emissions, or background and bystander
exposure measurements, and subtract those measured exposure levels from
those operations which do emit silica" (Document ID 4204, Attachment
1, pp. 31-32). OSHA has routinely included the elimination of cross
contamination as a component of the controls needed for some job
categories. As discussed in Chapter IV of the FEA, OSHA also believes
that other controls will still be needed for many job categories in
which cross contamination is common and as long as these additional
controls are needed, overall costs will not decline as a result of
controlling cross contamination. However, OSHA agrees that there may be
situations in which correcting cross contamination alone would be
sufficient. In this case, the commenter is right that OSHA may
sometimes overestimate costs.
General Methodological Issues--Comments on Costs Associated With
Exposures Over the Preceding PEL
Many commenters argued that OSHA should have attributed the costs
of reaching the preceding PEL of 100 [mu]g/m\3\ to this standard
(Document ID 2307, Attachment 8b, p. 16; 2195, p. 33; 1819, p. 2; 2375,
Attachment 2, p. 65; 2307, Attachment 1, p. 2; 2379, Attachment 2, p.
9). For example, Stuart Sessions of Environomics, commenting on behalf
of the ACC, stated that of the workers currently exposed over 50 [mu]g/
m\3\, two-thirds are exposed over 100 [mu]g/m\3\, and that OSHA erred
in excluding the costs of reducing those exposures to 100 [mu]g/m\3\
(Document ID 2307, Attachment C, pp. 2-3).
OSHA's preliminary initial regulatory flexibility analysis (PIRFA)
for the 2003 Small Business Advocacy Review (SBAR) panel included
benefits and costs associated with future compliance with existing
silica requirements on the basis that the rule would help improve
compliance with the existing silica rules (OSHA, 2003a and 2003b)
(Document ID 1685 and 0938, respectively). Upon further consideration,
OSHA determined that a more fair and accurate measure of the benefits
and costs of the proposed rule was to begin the analysis with a
baseline of full compliance with existing requirements; OSHA has
retained this approach for the final rule. The Agency offers three
reasons in support of this approach. First, the obligation to comply
with the preceding silica PEL is independent of OSHA's actions in this
rulemaking. The benefits and costs associated with achieving compliance
with the preceding silica rules are a function of those rules and do
not affect the choice of PEL. The question before the Agency was
whether to adopt new rules, and its analysis focused on the benefits
and costs of those new rules. Second, the Agency's longstanding policy
is to assume 100 percent compliance for purposes of estimating the
costs and benefits of new rules, and to assume less than full
compliance with the existing OSHA rules would be inconsistent with that
policy. Finally, assuming full compliance with the existing rules is in
keeping with standard OSHA practice in measuring the incremental
effects of a new rule against pre-existing legal obligations.
Reliance on costs that assume full compliance with both the
preceding and proposed (new) OSHA rules makes it easier to compare
the two regulatory schemes.
Some commenters also disagreed with the way OSHA attributed costs
to employers whose workers were being exposed to silica at levels
greater than the preceding PEL of 100 [mu]g/m\3\ (Document ID 3251, p.
2; 3296, p. 2; 3333, p. 2; 3373, p.2; 2503, p.2; 2291, p. 16; 4209, p.
111). These commenters argued that OSHA did not attribute any costs to
reaching 50 [mu]g/m\3\ to employers whose employees were exposed above
100 [mu]g/m\3\. They argued that OSHA instead assumed that the costs
and controls necessary to reach 100 [mu]g/m\3\ would also be sufficient
to reach a level of 50 [mu]g/m\3\, and as discussed above, that OSHA
did not account for those costs because reducing exposures to the
preceding PEL of 100 [mu]g/m\3\ was already required before this
rulemaking. The American Foundry Society (AFS) argued that OSHA reduced
costs by two-thirds "under the logic that employers must comply with
the current PEL and the proposal does not add any existing obligation"
(Document ID 2379, Appendix 1, p. 10). AFS added that OSHA's
underestimation of costs in this manner was particularly severe because
OSHA used outdated data that showed more employees with exposures over
100 [mu]g/m\3\, whereas more recent data would show fewer employees
with exposures above 100 [mu]g/m\3\ and more with exposures between 50
and 100 [mu]g/m\3\. Had OSHA used this updated data, in AFS's
estimation, the Agency would have identified more employers needing to
install additional engineering controls and thus there would be
additional costs that were not accounted for in the PEA (Document ID
2379, Attachment 3, pp. 9-10). ACC made a similar point, saying that as
a result of OSHA's methodology, "the exposure reduction costs for the
estimated 81,000 workers now exposed above 100 [mu]g/m\3\ are not taken
into account by OSHA on either a full cost basis or an incremental cost
basis" (Document ID 2308, Attachment 9, pp. 2-3).
In addition URS, among others, argued that "OSHA fails to account
for the non-linear costs associated with each incremental reduction in
silica concentrations," meaning that URS believed that it is more
costly to achieve additional reductions in exposure as exposures are
lowered. For example, according to URS's contention, it would be more
costly to reduce exposures from 75 [mu]g/m\3\ to 50 [mu]g/m\3\ than
from 125 [mu]g/m\3\ to 100 [mu]g/m\3\ (Document ID 2308--Attachment 8,
p. 11; 2291, p. 16; 4209, p. 11; 2307, Attachment 2, pp. 181-182; 2379,
Attachment 2, p. 9; 3487, p. 13).
OSHA has several responses to these criticisms. In response to the
criticism that OSHA overestimated the number of workers with exposure
levels above 100 [mu]g/m\3\ as a result of using outdated data, the
Agency has updated the exposure profile used to develop the final
analysis of costs. This update is described previously in Chapters III
and IV of the FEA. As a result of this update, OSHA found that, in the
aggregate, the percentage of workers in general industry and maritime
exposed to silica levels between 50 [mu]g/m\3\ and 100 [mu]g/m\3\ rose
from 33 percent as estimated in the PEA to 42 percent. And, as the
commenters noted would be the case, the percentage exposed at levels
above 100 [mu]g/m\3\ fell from 67 percent to 58 percent. OSHA has
updated this analysis to incorporate these data and has estimated costs
for these additional workers whose exposures fall between 50 [mu]g/m\3\
and 100 [mu]g/m\3\. The revised distribution also shows that of those
workers with exposures above the new PEL, 41 percent are exposed
between the new PEL and the preceding general industry PEL with an
average exposure level of 70 [mu]g/m\3\, 29 percent are exposed between
the preceding PEL and 250 [mu]g/m\3\ with an average exposure level of
156 [mu]g/m\3\, and 30 percent are exposed above 250 [mu]g/m\3\ with an
average exposure level of 485 [mu]g/m\3\. Where an industry submitted
more recent exposure data or information about exposure distributions
within their industry, OSHA was able to show that its final exposure
distribution was roughly equivalent (see Chapter IV of the FEA).
The technological feasibility analysis (presented in Chapter IV of
the FEA) describes the controls necessary for reducing exposures from
the highest levels observed in an industry's exposure profile to the
new PEL. In all application groups except two (asphalt paving products
and dental laboratories), the highest observed exposures were above the
preceding PEL. With the exception of hydraulic fracturing,\28\ the
technological feasibility analysis did not distinguish between the
controls necessary to meet the preceding general industry PEL of 100
[mu]g/m\3\ and those necessary to meet the new general industry PEL of
50 [mu]g/m\3\. Instead, the technological feasibility analysis simply
listed the controls necessary for those employers whose employees had
the highest baseline exposures to significantly reduce exposures and,
in most operations, meet the new PEL.
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\28\ Due to an unusually rich data set, and the great similarity
of different fracturing operations, both with respect to the
equipment used and the current levels of control, OSHA was able to
estimate which controls are necessary to go from an uncontrolled
situation to the preceding PEL and which are necessary to get from
the preceding PEL to the new PEL in the hydraulic fracturing
industry.
---------------------------------------------------------------------------
It was not necessary for OSHA to distinguish between controls
necessary to achieve the preceding PEL and those necessary to achieve
the new PEL in order to demonstrate the technological feasibility of
achieving a PEL of 50 [mu]g/m\3\. Such a distinction would have been
difficult because, from a baseline of uncontrolled exposures, the
controls necessary to meet the preceding and new PELs are difficult to
distinguish. For example, if there are two different controls necessary
to fully meet the new PEL, then it is logically possible that two
different establishments may achieve an exposure level at or below the
preceding PEL in different ways. One establishment may have excellent
housekeeping but poorly maintained LEV. Another may have well
maintained LEV but poor housekeeping. For individual cases, there is
not a simple demarcation of which controls of the total set of controls
are necessary to achieve the new PEL when only the exposure level and
not the controls already in place are known. Nor, as discussed above,
is it the case that a control, once installed, will always provide
identical protection. Two otherwise equal facilities may have the same
installed controls but different exposure levels because of the quality
of the maintenance of the system.
For the purposes of costing engineering controls for general
industry and maritime in the PEA, OSHA assigned all of the costs for
meeting a PEL of 50 [mu]g/m\3\--including the costs of controls
necessary to meet the preceding PEL of 100 [mu]g/m\3\--to all workers
with exposure levels between 50 [mu]g/m\3\ and 100 [mu]g/m\3\. However,
OSHA assigned no costs in the PEA to employees whose exposures exceeded
the preceding PEL. This approach would be accurate for both those above
and below the preceding PEL only if the exact same controls would be
needed to control exposures in both situations and these controls would
always yield an exposure level below the preceding PEL. However, as
discussed in the previous section on proportionality of costs, OSHA has
determined that this is not typically the case. There exist multiple
kinds of controls and the actual application and operation of the
control can differ. The approach applied in the PEA applied more
controls than will typically be needed where exposures are below the
preceding PEL and thus overestimates costs in these situations, but
then assigns no costs for achieving the new PEL where exposures are
above the preceding PEL. In the latter situation, it can reasonably
be expected that, in most cases, some costs would be incurred to
meet the new PEL even after the preceding PEL is met and therefore
the PEA methodology underestimated costs in those situations.
Although these over- and under-estimates are partially offsetting,
OSHA acknowledges that any over-estimates of cost do not necessarily
offset the potential under-estimates of costs.
OSHA has therefore decided to adopt an approach to the estimation
of costs different from that adopted in the PEA. In the FEA, OSHA
relied on data available in the rulemaking record to both correct the
overestimate of costs for those below the preceding PEL and, as many
industry commenters urged, estimate the costs necessary to meet the
preceding PEL as well as the new PEL for those above the preceding PEL.
To be clear, these data still do not enable OSHA to distinguish
between the exact controls needed to get from uncontrolled exposures to
the preceding PEL and those needed to get from the preceding PEL to the
new PEL on an industry-by-industry and occupation-by-occupation basis.
However, the data do enable OSHA to show that the majority of the costs
of controlling silica exposures are incurred in order to reduce
exposures from uncontrolled levels to the preceding PEL. OSHA will then
assume that 50 percent of the costs incurred will be to implement the
controls necessary to get from the uncontrolled situation to the
preceding PEL and 50 percent to implement the controls necessary to go
from the preceding PEL to meeting the new PEL. If, in fact, a majority
of the costs are incurred in order to reduce exposures to the preceding
PEL, the assumption that attributes 50 percent of costs to going from
the preceding PEL to the new PEL will overestimate the true costs for
establishments with exposures at the preceding PEL or between the
preceding PEL and the new PEL.
In order to assess whether the majority of the costs are necessary
to meet the preceding PEL, OSHA first examined what kinds of exposures
are associated with the uncontrolled situations that served as the
starting point for the estimates of needed controls in the
technological feasibility analysis. The average level of exposure
across all of general industry for employees with exposure exceeding
the preceding PEL is over 300 [mu]g/m\3\. Thus, on average, across all
industries the uncontrolled situation involves high levels of exposure,
commonly more than 3 times the preceding PEL.\29\
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\29\ To check that this was not the result of a very high
exposures for a small number of employees or industries, OSHA
examined the exposure profile presented in Table III-9 and found
that in only 4 industries (with 1.1 percent of all employees exposed
above the preceding PEL) were there no exposures above 250 [mu]g/
m\3\.
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In general, to reduce exposures from over 2.5 times the preceding
PEL to the preceding PEL, employers would have to implement some
measure or measures, and those measures would be the ones that provide
the greatest reduction in silica exposures and therefore control most
of the silica exposures in the facility. In most cases this will be a
working LEV system or some form of worker isolation. Measures like
improved housekeeping cannot reduce exposures from the levels observed
in uncontrolled exposure situations to the preceding PEL. OSHA reviewed
industry-by-industry and occupation-by-occupation cost estimates for
engineering controls and found that, on average 63 percent of the costs
were for LEV, 23 percent were for housekeeping, and 16 percent were for
other controls, most commonly wet methods (based on OSHA, 2016). In
many cases, where wet methods were applicable, wet methods represented
the majority of the costs and there were not significant LEV costs. As
a result, 79 percent of the costs of controls, on average, are
attributable to either wet methods or LEV. The combination of LEV or
wet methods with some improvement in housekeeping (though not the
improvements necessary to meet the new PEL) will constitute the
majority of costs for virtually all occupational categories. Some
improvement in housekeeping will typically also be required to meet
even the preceding PEL.\30\ While employers can probably meet the
preceding PEL with less than ideally maintained LEV systems,
improvements in maintenance will not reverse the conclusion that the
majority of the costs are incurred to meet the preceding PEL. This is
the case because on average 63 percent of engineering control costs are
necessary to reach the preceding PEL and some housekeeping costs will
also be necessary, leaving a significant percentage of expenditures
above 50 percent of the costs available for improved maintenance.
---------------------------------------------------------------------------
\30\ For example, in several industry sectors where workers are
currently manually dumping silica-containing materials, the use of
automated and ventilated dumping stations is needed to reduce
exposures from over 250 [mu]g/m\3\ to below the preceding PEL.
However, once these controls are installed and in use, final
exposures are often below the limit of detection or less than 12
[mu]g/m\3\--well below the new PEL (see technological feasibility
chapter for paint and coatings). However, to maintain these
exposures below the new PEL, these industry sectors will need to
ensure that ventilation systems are properly maintained and will
need sufficient housekeeping to ensure against build-ups of dust.
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To confirm the findings of this cost-spreadsheet-based analysis of
where the majority of the costs are incurred, OSHA reviewed industries
where good data are available on controls in both uncontrolled
situations and situations with exposures between the new and the
preceding PEL. OSHA examined the exposures and controls in eight
ferrous sand casting foundry facilities. In these eight facilities,
four had relatively few workers exposed above 50 [mu]g/m\3\, and the
other 4 had many exposures over 100 [mu]g/m\3\. OSHA found that those
facilities with most exposures over 100 [mu]g/m\3\ generally had little
or no LEV (relying instead on general ventilation), poor housekeeping,
no enclosures for workers, and poor maintenance. The foundries where
silica dust was better controlled generally had working LEV systems,
good housekeeping that kept surfaces free of silica dust, and good
maintenance practices. This indicates that LEV and some housekeeping
are essential to meeting the preceding PEL. OSHA also examined data on
all exposures with control descriptions. These data showed that
exposures above 250 [mu]g/m\3\ occurred in uncontrolled situations or
situations in which controls, though installed, were not in use. In
situations where exposures were between the preceding and new PELs,
most exposures showed some controls in place, normally LEV, but not all
controls recommended. In some cases there were no controls in place.
These generally represented situations in which exposures were much
lower than the typical uncontrolled situations and such facilities
would not normally need the full controls necessary to go from very
high levels of exposure to the new PEL (See Exhibit: Descriptions of
Control, available in Docket OSHA-2010-0034 at www.regulations.gov).
Based on these findings, OSHA determined that the majority of costs
are incurred in order to implement controls necessary to get from an
uncontrolled situation to the preceding PEL. However, OSHA developed
cost estimates for engineering controls based on the conservative
assumption that 50 percent of the total costs of going from an
uncontrolled situation to the new PEL is incurred in order to reach the
preceding PEL and the remaining 50 percent are incurred to reach the
new PEL.\31\ For example, in the cut stone industry 63 percent of those
exposed above the new PEL are also above the preceding PEL and 37
percent are below the preceding PEL but above the new PEL. The total
cost to the cut stone industry of going from uncontrolled exposure to
the new PEL is $17.7 million. With OSHA's assumption that half of the
costs of going from an uncontrolled situation to the new PEL is
incurred in order to reach the preceding PEL, then the cost for those
employers with employees exposed above the preceding PEL would be 63
percent of $17.5 million times 0.5, which equals $5.5 million. The cost
for those below the preceding PEL would be 37 percent of $17.7 million
times 0.5, which equal $3.3 million. The total cost of going from the
preceding PEL to the new PEL in the cut stone industry is therefore the
sum of these two calculations: $8.8 million. This will overestimate the
costs of reaching the new PEL, given the majority of the costs are
incurred to implement controls necessary to reach the preceding
PEL.\32\
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\31\ This approach was not applied to the two industries, dental
laboratories and asphalt paving materials, where the exposure
profile showed that there were no exposures above the preceding PEL.
\32\ OSHA also notes that this approach shows rising incremental
costs of control, which is consistent with some comments. This is
because 50 percent of the costs are estimated to be incurred to go
from levels of over 250 [mu]g/m\3\ to 100 [mu]g/m\3\ and equal costs
are estimated to be incurred to go from 100 [mu]g/m\3\ to 50 [mu]g/
m\3\.
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As presented in more detail below, this approach results in a total
annualized cost estimate for general industry and maritime engineering
controls of $225 million. Fortunately, this cost estimate is not highly
sensitive to the allocation percentage chosen. Each decrement of 5
percentage points changes the engineering control costs by
approximately 5.5 percent. Thus, for example, if 65 percent of the
costs are necessary to go from the preceding PEL to the new PEL, then
the annualized cost estimate for engineering controls would rise to
$261 million per year.\33\
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\33\ A value of 100 percent would be totally implausible as it
would imply that all establishments currently far above the
preceding PEL could achieve that PEL without cost. Put another way,
this would be equivalent to saying that, if OSHA had decided to
adopt the alternative PEL of 100 [mu]g/m\3\ (i.e., the same as the
preceding general industry PEL), as some employer groups
recommended, any employers currently above that PEL--regardless of
how far above the PEL they were--would be able to meet a PEL of 100
[mu]g/m\3\ without implementing any new engineering controls.
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Accounting for Costs of Downtime
Some commenters suggested that OSHA failed to account for the
downtime that installing engineering controls or performing an initial
through cleaning would require (e.g., Document ID 2368, p. 13 for
engineering controls; Document ID 2379, Attachment 2, p. 16 for initial
thorough cleaning).
Almost all firms need downtime occasionally in order to perform
general maintenance, inventory, or other tasks. In the final rule, OSHA
has extended the compliance date for general industry from one year to
two years. This will allow almost all employers to schedule work that
might require downtime to install, improve, or maintain controls that
they determine are necessary to meet the new PEL or to perform the
initial thorough cleaning at times when they would already need
scheduled downtime for other purposes. Therefore, OSHA has determined
that there will be no additional costs incurred for downtime in order
for employers to install engineering controls or to perform the initial
thorough cleaning.
Technological Change
One commenter, Dr. Ruth Ruttenberg, testifying for the AFL-CIO,
argued that OSHA had overestimated costs by failing to consider
technological change:
Technological improvements--both engineering and scientific--are
constantly occurring, especially when the pressure of a pending or
existing regulation provide a strong incentive to find a way to
comply at a lower cost... These improvements are well-documented
following the promulgation of rules for vinyl chloride, coke ovens,
lead, asbestos, lock-out/tag-out, ethylene oxide, and a host of
others (Document ID 2256, Attachment 4, p. 2).
Dr. Ruttenberg recognized that OSHA, in the PEA, already predicted
some "technological and cost-saving advances with silica," such as
expanding the use of automated processes and developing more effective
bag seals, but criticized OSHA for not accounting for those cost
savings in its analysis:
Technological improvements are as sure a reality--based on past
experience and academic research--as overestimation of cost and
underestimate of benefits are in an OSHA regulatory analysis. More
than 40 years of OSHA history bear this out (Document ID 2256,
Attachment 4, p. 3).
When promulgating health standards, OSHA generally takes an
approach in which cost estimates and economic feasibility analyses are
based on the technologies specified in the technological feasibility
analysis. This is a conservative approach to satisfying OSHA's legal
obligations to show economic and technological feasibility. As a
result, the Agency does not account for some factors that may reduce
costs, such as technological changes that reduce the costs of controls
over time and improvements in production that reduce the number of
employees exposed. As pointed out in the PEA, and from the examples
described in the "Total Cost Summary" at the end of this chapter,
some past experience suggests that these factors tend to result in
OSHA's costs being overestimated.\34\ OSHA considers the primary
purpose of the cost estimate to be to provide a basis for evaluating
the economic feasibility of the rule, and OSHA has determined that for
this rulemaking, feasibility is most accurately demonstrated by using
an approach that does not account for the potential impacts of future
technological changes.
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\34\ On the other hand, there is supplemental evidence from
Harrington et al. (2000) [Harrington, Winston, Richard D.
Morgenstern and Peter Nelson. "On the Accuracy of Regulatory Cost
Estimates." Journal of Policy Analysis and Management, 19(2), 297-
322, 2000] that OSHA does not systematically overestimate costs on a
per-unit basis, and that the reason for overestimation of costs at
the aggregate level has been a combination of difficulty with
establishing baseline conditions and noncompliance. Nevertheless,
several examples of OSHA's overestimation of costs reported in the
article are due to technological improvements.
---------------------------------------------------------------------------
General Methodological Issues: Number of Workers Covered by a Control
PEA Estimates
The cost calculations in the PEA included estimates of the number
of workers whose exposures are controlled by each engineering control.
Because working arrangements vary within occupations and across
facilities of different sizes, there are no definitive data on how many
workers are likely to be covered by a given set of controls. In many
small facilities, especially those that might operate only one shift
per day, some controls will limit exposures for only a single worker.
Also, small facilities might have only one worker in certain affected
job categories. More commonly, however, and especially in the principal
production operations, several workers are likely to derive exposure
reductions from each engineering control.
The PEA relied on case-specific judgments of the number of workers
whose exposures are controlled by each engineering control (see Table
3-3 in ERG, 2007b, Document ID 1608). The majority of controls were
estimated to benefit four workers, based on the judgment that there is
often multi-shift work and that many work stations are shared by at
least two workers per shift. The costs of some types of equipment that
protect multiple employees, such as HEPA vacuums, were spread over
larger groups of employees (e.g., six to eight workers). In the PEA,
the average number of workers affected represented an average across
all establishments, large and small.
Comments and Responses
Some commenters questioned OSHA's estimate of the number of workers
whose exposures could be controlled per newly added or enhanced
control. OSHA's PEA most commonly estimated that four workers would
have their exposures reduced for each new or enhanced engineering
control. Dr. Ronald Bird, testifying for the Chamber of Commerce,
argued that OSHA's estimates were simply arbitrary assumptions
(Document ID 2368, p. 14). Stuart Sessions, testifying for the ACC,
argued that the use of a single standard crew size of four led OSHA to
underestimate costs and economic impacts for smaller establishments, at
which, he argued, "there are virtually never as many as four
overexposed workers in any job category, and it is simply impossible
that one application of a package of controls in this situation could
protect as many as 4 overexposed workers on average" (Document ID
4231, Attachment 1, p. 6).
The approach OSHA used was intended to represent the average number
of employees affected by a given set of controls. Larger establishments
may have more than four workers whose exposures are reduced by a single
control, and smaller establishments may have fewer than four. However,
OSHA agrees that this approach may result in an underestimate of costs
for the smallest establishments. Because it is particularly important
to consider the costs to the smallest establishments, OSHA has reduced
the number of employees whose exposures are reduced per control by half
for establishments with fewer than twenty employees, so that in those
small establishments a given control is assumed to reduce exposures for
two workers instead of four as assumed in the PEA. Because larger
establishments may have greater numbers of employees whose exposures
are reduced per control, this change may result in an overall
overestimation of costs. (In the PEA, the overestimation of costs for
larger facilities was partially offset by the underestimation of costs
for smaller establishments. This is no longer the case in the FEA.)
OSHA nevertheless believes the revised approach used in the FEA is
better than the approach used in the PEA for purposes of capturing
economic impacts on smaller establishments, even though it may result
in aggregate costs being overestimated.
Variability
Some commenters argued that both OSHA's technological feasibility
and cost analyses were flawed because OSHA neglected to address the
day-to-day variability of exposure measurements. By failing to address
the issue of variability, these commenters argued, OSHA grossly
underestimated the costs of engineering controls. These commenters
reported that silica exposures would have to be controlled to levels
considerably lower than the proposed (new) PEL in order to account for
the variation in exposures across jobs and from day to day (e.g.,
Document ID 2307, Attachment 2, p. 202; 2308, Attachment 7, p. 2; 2308,
Attachment 8, p. 6; 2379, Attachment 4, p. 1; 2291, p. 11; 2195, pp.
26-27; 2503, p. 2; 2222, Attachment 1, p. 1). For example, in response
to a written question about the activities in which employers were able
to achieve the proposed (new) PEL "most of the time," AFS objected to
the premise of the question, noting that "[s]everal foundries have
received citations for exposures above the current PEL on operations or
tasks for which the proposed PEL is achieved most of the time"
(Document ID 2379, Appendix 1, p. 18). AFS argued that OSHA's non-
compliance model of enforcement requires employers to reduce average
exposures to half the PEL in order to have confidence that exposures
will never exceed the PEL (Document ID 2379, Appendix 2, p. 29). The
Asphalt Roofing Manufacturing Association (ARMA) made a similar point
and said that the majority of asphalt roofing plants operated by its
members have some exposures over the PEL of 50 [mu]g/m\3\, even if it's
a "relatively small incidence" (Document ID 2291, p. 11).
Both AFS and ARMA offered estimates of the magnitude of this
variability by measuring the statistical variance of exposures. AFS
stated that to assure 84 percent confidence in compliance with the
preceding PEL, the mean exposures in some specific jobs in specific
foundries would need to be below half that PEL, and that the "mean
level necessary to achieve the 95 percent confidence of compliance
could not be determined but is significantly below one half the PEL"
(Document ID 2379, Appendix 1, p. 23).
ARMA examined the distribution of silica exposures in over 1,300
samples from 57 asphalt roofing facilities. These data showed that even
though the median exposures for all jobs were below the new action
level of 25 [mu]g/m\3\, a total of 9 percent of all samples were above
the new PEL of 50 [mu]g/m\3\ (Document ID 2291, p. 5, Table 1). ARMA
also provided an estimate of the "lowest strictly achievable level"
(meaning a level not to be exceeded more than 5 percent of the time)
which varied by job classification from 67 to 310 [mu]g/m\3\ (Document
ID 2291, p. 9, Table 2).
One serious problem with the ARMA analysis is that the discussions
of variability and the estimates of mathematical variance are based on
results either from different facilities with potentially different
levels of controls or from all job categories within one facility. The
key issue for assessing the importance of variability is the variance
within a given job category in a specific establishment with specific
controls. The methodology employed is such that even if individual job
categories or individual facilities had no variance, pooling data
across facilities would create variance.
ARMA estimated that sufficiently controlling variation would
require investment in capture vents, duct work, and dust collection
systems costing up to $2.1 million each in initial costs per
manufacturing line (Document ID 2291, p. 12). AFS did not provide a
cost estimate solely for sufficiently controlling variation.
The AFL-CIO disagreed with industry's arguments and instead argued
that the best way to reduce variability was not simply to add
additional engineering controls because, as explained earlier in the
discussion of URS's comments on the per-worker cost basis,
overexposures are not random:
The worker-to-worker variation is explainable and controllable:
Workers use different methods, they may take different positions
relative to ventilation systems, they may use different work
practices, and they may be subject to fugitive emissions (carryover
from adjacent silica emitting processes). These differences in
conditions can be observed by the industrial hygienist collecting
the air sample, compared to exposure levels, and changed. Day-to-day
variation for the same worker is caused by variation in materials,
ventilation systems, production rate, and adjacent sources showing
such variation. Sometimes these variations can be large, based on
breakdowns of ventilation, process upsets and blowouts (Document ID
4204, p. 40).
OSHA's enforcement policies are discussed in Chapter IV of the FEA
and in this preamble. Variability of exposures is potentially a cost
issue when there are technologically feasible controls that have costs
not otherwise accounted for that could further reduce environmental
variability. If it is not technologically feasible to reduce
variability then there will be no further costs. For example, if an
employer has installed all feasible controls, there are no additional
costs for engineering controls because there are no additional controls
to purchase, regardless of variability. On the other hand, an employer
who has a median exposure level of 80 percent of the PEL with frequent
excursions above and who could feasibly reduce variability would be
required to do so.
As noted above, those (AFS, ARMA) who argued that OSHA had
underestimated costs by failing to account for exposure variability, in
general, assumed that the best approach to reducing variability would
be to increase the levels of LEV to reduce the average exposure level
to half of the PEL or less, without examining the origin of the
variability.
OSHA agrees with the AFL-CIO that variability in exposure is likely
controllable by examining the origins of the variability. One origin is
poor work practices. To improve work practices, employers could observe
work practices when monitoring takes place; determine which work
practices are associated with high exposures; and modify those work
practices found to lead to high exposures. Variability can also be the
result of a failure of controls not functioning properly, either
resulting from sudden failures or from gradual deterioration of
performance over time. The latter can be prevented by good maintenance.
Both in its cost assessment for the proposal and in the
modifications made for this final rule, OSHA has taken account of the
costs necessary to reduce unusual and exceptionally high exposure
levels and thus reduce some sources of variation. As discussed in the
cost of ancillary provisions, OSHA has estimated costs for exposure
monitoring that include the time for observation of the worker. OSHA
has also estimated costs for training to assure good work practices,
and has increased the estimated length of training in general industry
to ensure that the time is sufficient for training on work practices.
In this section, OSHA has costed LEV, LEV maintenance, and the need for
replacement LEV to assure that the LEV will function properly. OSHA has
therefore already accounted for a variety of costs associated with
steps that can be taken to reduce variability in exposures.
Substitution of Low- or Non-Silica Inputs
PEA Estimate
For several industries, employers might lower silica exposures by
substituting low- or non-silica inputs for existing inputs. While this
option can be an extremely effective method for controlling silica
exposures in many industries, OSHA did not cost this option in the PEA.
OSHA determined that there were often complicating factors that
restricted the potential for broad substitution of non-silica-
containing inputs for silica-containing inputs throughout the affected
industries. It is possible that the same product quality cannot be
maintained without using silica. Some products made with substitute
ingredients were judged to be inferior in quality and potentially not
viable in the market. In addition, a substitute silica ingredient might
introduce adverse health risks of its own. Further, in several
instances, the availability of reasonably inexpensive alternative non-
silica ingredients was well known but the alternative was not selected
as a control option by most firms. In light of these concerns, OSHA
decided not to include the option of non-silica substitutes in
estimating the cost of the proposed rule.
Comments and Responses on Substitution
Some commenters complained that OSHA's analysis did not account for
the costs of substitution (Document ID 2264, Attachment 1, p. 27; 2379,
Attachment 2, p. 6; 3485, p. 25; 3487, p. 17).
OSHA considered the comments on the issue but has decided to adhere
to the approach taken in the PEA. OSHA did not take account of the
costs of substituting other substances for silica, because, while such
substitution might have substantial benefits and avoid the need for
engineering controls, OSHA determined that, in most situations,
substitution is not the least costly method of achieving the proposed
or new PEL (Document ID 2379, Attachment 2, p. 6). As a result, OSHA's
final cost analyses do not account for the possibility that firms would
choose to substitute for substances other than silica. To the extent
that substitutes are the least costly solution in some situations, OSHA
has overestimated the costs.
Cost of Air Quality Permit Notification
The Agency received comments suggesting that foundries and other
manufacturing plants would be required by the Environmental Protection
Agency (EPA), or other federal or state environmental authorities, to
incur an administrative cost to ensure their systems are compliant with
relevant EPA regulations. Commenters expressed concern that the
permitting process itself could be a major undertaking, made worse by
difficult compliance deadlines. Given that the final rule provides
extra time for planning and permitting, OSHA has examined the potential
impacts of the new rule and finds that the commenters are overstating
the potential for such costs. The argument for significant permitting
costs was typically combined (e.g., Document ID 2379, Appendix 3) with
an argument that the Agency underestimated the amount of ventilation
required to comply with the final rule; comments on ventilation
requirements are dealt with in great detail elsewhere in this chapter.
Upon investigation, while OSHA agrees that it would be appropriate
to recognize an administrative burden with respect to the interfacing
environmental regulations, the Agency believes that many of the
commenters' concerns were overstated. First, many control methods
needed to comply with the final rule will not require alterations to
existing ventilation systems. As discussed earlier in Chapter V of the
FEA, work practices, housekeeping and maintenance are important
components in controlling exposures; in many cases existing
ventilation, as designed and permitted with the environmental
authority, is adequate, but needs to be maintained better. In addition,
most establishments, particularly smaller ones, will continue to have
particulate emissions levels that fall below the level of EPA permit
requirements. In the case of large facilities that do not, the changes
will be on a sufficiently small scale that they will not require
elaborate repermitting, but will only require minor incremental costs
for notifying the environmental authorities, or in some cases,
submitting a "minor" permit
(see http://www2.epa.gov/nsr and http://www2.epa.gov/title-v-operating-permits).
Taking into account the preceding silica PEL and the estimate that
baghouses will capture 99 percent of silica emissions
(Document ID 3641, p. VII-19), OSHA concludes that it is unlikely that
facilities will encounter a need for significant air permit modifications.
The Agency recognizes, however, that there will be minor
incremental costs for notifying environmental authorities. While many
establishments in the United States may have no requirement to do so,
the Agency has conservatively assumed that all establishments with
twenty or more employees in most industries will need to dedicate a
certain amount of time to preparing a one-time notification to
environmental authorities to ensure that their air permits accurately
reflect current operating conditions. OSHA has determined that small
establishments would generally lack the large scale industrial facilities
requiring permits, and that the few that might require such permits would
be balanced out by the likely inclusion of medium establishments that do
not actually require permits for their emissions. The industries
excluded were those that generally lack large scale industrial
facilities, or that do not produce a concentrated, as opposed to
diverse or unconsolidated, emission source. The excluded industries
were hydraulic fracturing, shipyards, dental equipment and labs,
jewelry, railroads, and landscaping.
To allow for adequate administrative time for creating and
submitting the notification, at those facilities that could potentially
incur costs, OSHA allocated 20 hours to establishments with 20 to 499
employees and 40 hours to establishments with 500 or more employees. A
manager's loaded hourly wage rate of $74.97 was applied to estimate the
cost to employers (BLS, OES, 2012, Document ID 1560). The costs per
establishment were estimated at approximately $1,500 per medium
establishment and $3,000 per large establishment. Because both new
permit applications and permit modifications are minor administrative
chores, OSHA's cost estimates are sufficient to cover either case.
Costs for Specific Engineering Controls
Ventilation Costs
PEA Estimates
In the PEA, OSHA determined that at many workstations, employers
needed to improve ventilation to reduce silica exposures. The cost of
ventilation enhancements estimated in the PEA generally reflected the
expense of ductwork and other equipment for the immediate workstation
or individual location and, potentially, the cost of incremental
capacity system-wide enhancements and increased operating costs for the
heating, ventilation, and air conditioning (HVAC) system for the
facility.
In considering the specific ventilation enhancements for given job
categories the PEA estimated the type of LEV and the approximate
quantity in cubic feet per minute (cfm) of air flow required to reduce
worker exposures.
To develop generally applicable ventilation cost estimates for the
PEA, a set of workstation-specific and facility-wide ventilation
estimates were defined using suggested ventilation approaches described
in the American Conference of Governmental Industrial Hygienists
(ACGIH) Industrial Ventilation Manual, 24th edition (Document ID 1607).
With the assistance of industrial hygienists and plant ventilation
engineering specialists, workstation estimates of cfm were derived from
the ACGIH Ventilation Manual, and where not covered in that source,
from expert judgements for the purpose of costing LEV enhancements
(Document ID 1608, p. 29).
Over a wide range of circumstances, ventilation enhancement costs,
which included a cost factor for HEPA filters and baghouses, where
needed, varied from roughly $9 per cfm to approximately $18 per cfm
(Document ID 1608, p. 29). Because of a lack of detailed data to
estimate the specific ventilation installation costs for a given
facility, an estimate of the likely average capital cost per cfm was
used and applied to all ventilation enhancements. Based on discussions
with ventilation specialists, $12.83 per cfm was judged to be a
reasonable overall estimate of the likely capital costs of ventilation
enhancements (Document ID 3983, p. 1).
OSHA applied the per-cfm capital cost estimate to estimated cfm
requirements for each workstation. By using the unit value of $12.83
per cfm, the cost estimates for each ventilation enhancement included
both the cost of the LEV enhancement at the workstation and the
contribution of the enhancement to the overall facility ventilation
system requirements. That is, each ventilation enhancement at a
workstation was expected to generate costs to the building's general
ventilation system either by requiring increased capacity to make up
for the air removed by the LEV system or to filter the air before
returning it to the workplace.
For operating costs, engineering consultants analyzed the costs of
heating and cooling system operation for 12 geographically (and
therefore, climatologically) diverse U.S. cities. The analysis,
presented in Table 3-2 in the ERG report (Document ID 1608, p. 30),
showed the heating and cooling British Thermal Unit (BTU) requirements
for 60-hours-a-week operation (12 hours a day, Monday through Friday)
or for a continuous 24-hour-a-day, year-round operation, with and
without recirculation of plant air. Facilities that recirculate air
have much lower ventilation system operating costs because they do not
need to heat or cool outside air to comfortable inside temperatures.
In the PEA, ventilation operating costs were based on a weighted
average of the costs of four operating scenarios: (1) No recirculated
air, continuous operation; (2) no recirculated air, operating 60 hours
per week; (3) recirculated HEPA filtered air, continuous operation; and
(4) recirculated HEPA filtered air, operating 60 hours per week. These
scenarios were chosen to reflect the various types of operating system
characteristics likely to be found among affected facilities. The
weights (representing the share of total facilities falling into each
category) and operating costs per cfm for each of these scenarios are
shown below in Table VII-11-1:
The national average annual operating cost per cfm was estimated to
be $2.22. This estimate was a weighted average of the operating costs
for facilities that recirculate air and those that require make-up air.
The operating costs for HEPA-filter recirculated air were estimated at
$0.50 per cfm for facilities operating 60 hours per week and $1.40 per
cfm for those continuously operating 24 hours per day. The operating
costs for facilities that do not recirculate air were $5.78 per cfm for
those operating 60 hours per week and $15.55 per cfm for those
operating continuously. In generating these estimates, it was judged
that 80 percent of facilities would recirculate airflow and 20 percent
would not, and that 75 percent within each group operate for 12 hours
per day on weekdays, with the remainder operating continuously, year-
round, for 24 hours a day.
OSHA also added a maintenance factor to the operating cost
estimates, which was 10 percent of the capital cost investments of
$12.83 per cfm for ventilation systems. As a result, the total annual
costs per cfm, excluding annualized capital costs, were estimated to be
$3.50 (weighted average operating costs of $2.22 plus annual
maintenance costs of 10 percent of $12.83).
Underlying the cost results was the assumption that, over the
course of the proposed one-year compliance period for engineering
controls, employers would schedule installation of ventilation to
minimize disruption of production, just as they would with any
modification to their plants.
Comments and Responses on Local Exhaust Ventilation Issues: Need for a
Complete New System
Local exhaust ventilation represents one of the major costs
associated with engineering controls in both the PEA and in the FEA.
Commenters raised issues both about OSHA's PEA estimates of the unit
costs of LEV and about the adequacy of OSHA's estimates of the volume
of LEV that would be needed to adequately control silica exposures.
URS, testifying on behalf of ACC, argued that any firm that would
be utilizing LEV to meet a PEL of 50 [mu]g/m\3\ would need to remove
any existing LEV and install an entirely new LEV system. Thus, in URS's
estimation, there would be no incremental addition of LEV. In a
discussion of the URS approach during OSHA's informal public hearings,
OSHA asked the URS representative to confirm that his organization
commented that when a majority of workers are exposed over the PEL, the
existing controls must be replaced instead of enhanced:
MR. BURT: I want to be sure I understand what that's saying.
Let's say you encountered a situation in which there were four
workers. Two were exposed at 35, two at 60. You would scrap all of
the controls and start over again. That's what it seems to be
saying.
[...]
MR. WAGGENER: [Y]es, that they would need to be replaced with a
more adequate system (Document ID 3582, Tr. 2109-2110).
OSHA's examination of the spreadsheets URS provided documenting its
independently developed cost estimates shows that, in all cases where
any employee in an establishment was exposed above 50 [mu]g/m\3\, URS
assumed that the employer would need to install a complete new LEV
system and included the costs for installing and operating this
entirely new system (Document ID 2308, Attachment 8, pp. 13-14).
John Burke from OSCO Industries took a different approach to the
question that better illustrates the options that OSHA believed to be
available when it developed the PEA estimates:
A single large dust collector is probably already handling the
exhausting of the entire sand conditioning system. Most likely all
the pick-up points referenced in the economic analysis already have
suction being applied and yet there is still an overexposure. What
do you do and how much is that going to cost? If the sand system
operator is overexposed then you could first evaluate work practices
controls. If work practice controls are unsuccessful and additional
suction is needed, that suction is going to be very expensive! If
your environmental operating permit allows it you may be able to
tweak the performance of the dust collector. There may be some
things you can do to tweak the capacity of your existing dust
collector to bring it up to exactly its permitted air volume or
you might have to enlarge your dust collector
(Document ID 1992, p. 6).
OSHA agrees with Mr. Burke. As discussed above, there are usually a
wide variety of ways to improve existing controls before removing and
reinstalling an LEV system. As a result, OSHA finds the URS approach
unrealistic and likely to significantly overestimate costs.
Comments and Responses on the Volume of Controls Needed
One commenter, URS, questioned OSHA's estimates of the volume of
additional LEV that would be needed to comply with the standard. URS,
testifying for ACC, reported that OSHA's estimates in the PEA were too
low as compared to the recommendations in Table 6-2 of the ACGIH
Ventilation Manual (28th Edition). They criticized OSHA's estimates
saying that OSHA routinely underestimated required capture velocities
by at least a factor of two for particles with high (conveyor loading,
crushing) or very high (grinding, abrasive blasting, tumbling) energies
of dispersion (Document ID 2308, Attachment 8, pp. 12 and 14). URS said
that "the capture velocities for LEV systems in OSHA's models were
often based on the minimum recommended velocity," that OSHA's
estimated additional LEV was too low because "the ACGIH capture
velocity values used by OSHA were first developed and published many
years ago" and were not sufficient to control dust to the levels OSHA
is now proposing, and that "the velocity values used in OSHA's cost
model are most likely undersized by a factor of 2 or more" (Document
ID 2308, pp. 11-12). Other than its own supposition, URS did not
identify an alternative source for OSHA to use as the basis for
estimates of ventilation capacity necessary to control silica
exposures.
In response to these comments, and in order to determine whether
ACGIH recommendations had changed between the 24th edition (which OSHA
used to develop estimates in the PEA) and the more recent 28th edition,
OSHA checked its estimated volumes against those in the more recent
ACGIH Ventilation Manual (Chapter 13 in the 28th edition (Document ID
3883)). In the 24th edition of the Manual, ACGIH provided a single
recommendation for ventilation capacity rather than a range. In the
PEA, OSHA adopted this recommendation and did not choose a value from
within a range of values. The 28th edition of the Manual provides more
flexibility in system design and specification and incorporates a
recommended range. However, OSHA determined that the ventilation
capacity estimates did not change between the 24th edition of the
Manual and the 28th edition. In most cases, OSHA's estimated volumes
were identical to those recommended by ACGIH. The exceptions were
situations in which ACGIH provided no recommendation (in which case
OSHA relied on recommendations of industrial hygienists), and
situations in which the technological feasibility analysis recommended
additional volumes of LEV capacity above what employers were typically
using. In the latter situations, OSHA estimated that an additional 25
percent of the ACGIH specification would be necessary to adequately
control silica exposures (See Exhibit: Comparison of OSHA CFM Volumes
to ACGIH Values, available in Docket OSHA-2010-0034 at
www.regulations.gov).
URS argued that silica was different from other substances LEV
might be applied to in ways that would call for higher volumes of
ventilation (Document ID 2308, Attachment 8, p. 14). However, in all
cases involving silica (such as shake-out stations), the ACGIH Manual
recommended the volumes used by OSHA and criticized by URS.
OSHA's estimates of the ventilation capacity necessary to control
silica exposures relied on a detailed set of recommendations provided
by ACGIH while URS simply asserted that these values are "most likely
undersized by a factor of 2 or more" without providing additional
evidence to support this (Document ID 2308, Attachment 8, p. 12). Based
on these findings, OSHA has determined that the ACGIH recommendations
constitute the best available evidence and has maintained the estimates
of ventilation capacity from the PEA for the FEA.
Comments Providing Alternative Ventilation System Cost Estimates
Other commenters provided much higher costs than OSHA's estimates
but without providing any background to allow OSHA to put those costs
in context. It is difficult for OSHA to evaluate a cost estimate
without information on the size of the facility, the estimated volume
of air, and the exposure levels before and after the LEV was installed.
The Interlocking Concrete Pavement Institute (ICPI) commented that
OSHA underestimated compliance costs because "[o]ne ICP manufacturer
reported that it could cost $150,000 to acquire and install highly
efficient vacuum and water dust-control systems" and other
manufacturers reported similarly high costs (Document ID 2246, p. 11).
At the public hearings, OSHA sought clarification on the assumptions
underlying the ICPI cost estimate, and the ICPI representative stated
that $150,000 was a mid-range estimate. The representative also
confirmed that this was the cost of an entirely new system:
MR. BLICKSILVER: [D]oes this actually represent the incremental
cost associated with complying with OSHA's proposed rule?...Or
is this an overall cost for dust control in these manufacturing
plants?
MR. SMITH: The latter (Document ID 3589, Tr. 4407-4409).
In a follow-up verbal exchange, OSHA requested that ICPI analyze
its survey data to produce median values for the range of cost
estimates and submit their analysis as a post-hearing comment (Document
ID 3589, Tr. 4409). However, no ICPI comments appeared in the record
following the Institute's testimony at the hearings.
Similarly, OSHA asked Mr. Tom Slavin, testifying for AFS, for
additional information from AFS on the many cost estimates for
individual foundries that it had included in its comments:
MR. BURT: You provide many examples of cost to specific
foundries of specific activities. I would like to suggest that those
can be most useful if we have data on the size of the firm in
question, the type of foundry if that's appropriate, and what they
were trying to accomplish with this effort.
Were they at 400 and trying to get to 100, at 100 trying to get
lower? Something that puts it in context would again make these
many, many helpful quotes much more useful.
Size is just critical, just because of the fact that when we
don't know whether we're talking about 20 or 200 people in a foundry
really affects what you want to do with those cost estimates. And
that one's relatively simple, size of firm, type of foundry if you
have it, what they were trying to do with that effort (Document ID
3584, Tr. 2773-2774).
Later in the exchange, OSHA requested information on "the
components of [AFS's estimated cost per cfm of additional ventilation]
that would be capital cost, installation cost, and then any other
operating costs you have" (Document ID 3584, Tr. 2784). OSHA received
no response to this request.
Unfortunately, it is almost impossible for OSHA to make use of
commenters' estimates of costs or volume of LEV systems without
information on the size of the facility and on what the resulting
system accomplished in terms of reducing exposure levels. OSHA
consistently requested this kind of information, but did not receive it.
As shown in the discussion of alternative estimates of costs by small
entity representatives during the SBAR Panel (discussed below), even
estimates that appear higher
than OSHA's average costs can be consistent with those costs when the
full context for the estimates is examined.
Comments and Responses on Unit Cost per CFM
Many commenters thought that OSHA's unit costs for ventilation were
too low. With respect to the annualized value of the capital costs plus
operating and maintenance costs of $5.33 that OSHA used in the PEA, AFS
stated:
The PEA uses an annual cost factor of $5.33 for ventilation,
including ducting and bag house operation [...] is far below foundry
experience. A group of foundry ventilation managers and ventilation
experts estimated the annual cost per CFM at $20 for exhaust alone
and another $6-10 for makeup air critical to achieving the lower
PEL. The cost to meet the new U.S. Environmental Protection Agency
(EPA) dust loading criteria increases the exhaust annual cost to $25
per CFM. Any new installation would be expected to design to the new
criteria even if not yet required to do so for that specific
jurisdiction (Document ID 2379, Appendix 3, p. 9).
URS, commenting on behalf of ACC, estimated the annualized cost of
LEV to be $27 per cfm, and increased OSHA's original estimate of
capital costs from $12.83 to $22 per cfm for the purpose of URS's cost
estimate (Document ID 2308, Attachment 8, pp. 13-14).
Many other commenters from industry suggested unit costs for
additional LEV. For example, AFS provided independent estimates of
annualized costs of $20 to $25 per cfm and URS estimated $22 to $27
capital costs per cfm (Document ID 2379, Appendix 1, p. 45; 2308,
Attachment 8, p. 14; 2379, Appendix 2, p. 13; 2503, p. 2; 2119,
Attachment 3, p. 4; 2248, p. 8; 3490, p. 3; 3584, Tr. 2779).
OSHA agrees that there can be a wide range of both capital and
operating costs associated with LEV. Capital costs will vary according
to such factors as the exact nature of the ventilation (including the
design of the slot, hood, or bagging station), the volume of materials
to be handled by the ventilation, and the length of the ductwork
necessary. OSHA also would like to clarify that, as shown in OSHA's
spreadsheets (OSHA, 2016), where there are major structural changes
associated with a control, such as automation, a new bagging station,
or conveyor closure, these costs are estimated over and above the basic
capital costs of LEV. Annual operating costs vary according to climate,
hours of operation, and the extent to which air is recirculated. To
examine these possible costs, OSHA reviewed the thoroughly documented
LEV costs presented in its Final Economic Analysis for the Occupational
Exposure to Hexavalent Chromium Standard (Document ID 3641). In that
FEA, OSHA's estimates of the capital costs for LEV (updated to 2012
dollars) averaged more than $20 per cfm when major work station
changes, such as automated bag slitting stations, were included in the
cost of LEV. Ordinary additional LEV without major workstation changes
was estimated to have an average capital cost of $9 per cfm in 2012
dollars. Operating costs in that rulemaking were estimated to be
somewhat higher than estimated here, but combined annualized costs
(capital plus operating costs) were approximately the same (See
Exhibit: Analysis of LEV Costs from Hex Chrome, available in Docket
OSHA-2010-0034 at www.regulations.gov).
OSHA agrees that the capital costs of some kinds of LEV that
involve significant workstation modifications or even automation can
exceed $20 per cfm, but finds an average of $13.34 (in 2012 dollars)
per cfm in capital costs to be reasonable given that some kinds of LEV
installation can cost as little as $3 to $5 per cfm. OSHA also finds
the operating cost estimates used in the FEA to be a reasonable average
across a very wide variety of circumstances.
Housekeeping and Dust Suppression Costs
PEA Costs
For a number of occupations, the technological feasibility analysis
in the PEA indicated that improved housekeeping practices were needed
to reduce silica exposures. The degree of incremental housekeeping
depended upon how dusty the operations were and the appropriate
equipment for addressing the dust problem. The incremental costs for
most such occupations reflected labor associated with additional
housekeeping efforts. Because incremental housekeeping labor was
required on virtually every work shift by most of the affected
occupations, the costs of housekeeping in the PEA were significant. The
PEA also estimated that employers would need to purchase HEPA vacuums
and to incur the ongoing costs of HEPA vacuum filters. The time needed
for such housekeeping varied from five to twenty minutes per affected
worker per day. Appendix V-A in the PEA provided detailed
specifications on the application of housekeeping and other dust-
suppression controls in each occupational category and the sources of
OSHA's unit cost data for such controls.
For some indoor dust suppression tasks, it was assumed that dust
suppression mixes--often sawdust-based with oil or other material that
adheres to dust and allows it to be swept up without becoming
airborne--were spread over the areas to be swept. For these products,
estimates were made of usage rates and the incremental times necessary
to employ them in housekeeping tasks.
For outdoor dust suppression, the PEA determined that workers must
often spray water over storage piles and raw material receiving areas.
The methods by which water is provided for these tasks can vary widely,
from water trucks to available hoses. It was judged that most
facilities would make hoses available for spraying and that spraying
requires a materials-handling worker to devote part of the workday to
lightly spray the area for dust control.
The PEA did not include any costs for thorough cleaning designed to
remove accumulated dust, either as a one-time cost or as an annual
cost.
Comments and Responses on Costs of Routine Housekeeping and Initial
Cleaning
Commenters had a number of issues with respect to how OSHA treated
the costs of housekeeping, including the time and equipment needed for
vacuuming, the need for professional floor to ceiling cleaning, and the
costs of the ban on dry sweeping.
Comments and Responses on Costs of Routine Housekeeping
With respect to the use of HEPA vacuums, AFS commented that due to
the volume of sand involved, foundries often use vacuum systems that
cost $45,000 instead of the $3,500 estimated by OSHA in the PEA
(Document ID 4229, Attachment 1, p. 23). Several commenters reported
that HEPA semi-mobile central vacuum systems cost more than $40,000 to
purchase and cost approximately $4,000 per year to maintain, and that
sweeping compound costs approximately $4,000 per year (Document ID
2384, p. 7; 2114, Attachment 1, p. 4). Several others noted that
acquiring HEPA vacuums and employee time for vacuuming would be
expensive (Document ID 2301, Attachment 1, p. 74; 3300, pp. 4-5; 2114,
Attachment 1, p. 4).
OSHA's costs are for improved housekeeping, beyond the necessary
tasks related to dealing with the large volumes of sand used in
foundries. For this final rule, OSHA estimates the costs of additional
housekeeping as those necessary for overexposed workers to spend
10 minutes vacuuming their immediate work areas with a 15-gallon HEPA
vacuum. It is possible that a large firm may find a dust handling
system or a semi-mobile central vacuum system less expensive
than having individual workers equipped with smaller capacity HEPA
vacuums spend additional time performing housekeeping on each shift.
With respect to the shipbuilding sector, OSHA found that it had not
accounted for the costs of HEPA vacuums for abrasive blasting helpers.
OSHA has added costs for the vacuums, but not for the time spent
performing housekeeping as the vacuums replace dry sweeping.
As to the possible costs of the ban on dry sweeping, OSHA has
modified this prohibition in ways that should avoid significant costs
in situations where dry sweeping is the only effective method of
housekeeping.
Comments and Responses on Costs of Initial Cleaning
URS, testifying for ACC, questioned OSHA's omission of
"professional cleaning" from its cost models for some industries,
noting that professional cleaning was identified in the PEA as
necessary for some industries to achieve the PEL (Document ID 2308,
Attachment 8, p. 12). URS also provided estimates of the cost of
professional cleaning:
Based on communications with several industries, URS estimates
that a thorough annual professional cleaning will cost about $1.00
per square foot of the facility process operations area.
...A professional cleaning can take several days to
accomplish [...] For square footage, URS assumed 20,000 square
feet for very small facilities, 50,000 square feet for small
facilities, and 200,000 square feet for large facilities (Document
ID 2308, Attachment 8, p. 24).
Initial thorough facility cleaning and rigorous housekeeping are
supplemental controls and work practices addressed in the technological
feasibility analysis for the following application groups: Concrete
Products, Pottery, Structural Clay, Mineral Processing, Iron Foundries,
Nonferrous Sand Foundries, and Captive Foundries. OSHA failed to
include the costs of a thorough initial cleaning in the PEA, but has
developed estimates of these costs for the FEA in response to the URS
comment. The final standard sets the performance objective of achieving
the PEL using engineering controls, work practices, and where
necessary, respiratory protection, and, with respect to facility
cleaning and housekeeping, the rule does not mandate that firms hire
outside specialists. To estimate the final costs for initial thorough
facility cleaning, OSHA first developed an analysis of average
production floor space in square feet for two plant sizes based on data
on plant floor space and employment for individual facilities reported
in various NIOSH control technology and exposure assessment field
studies (OSHA examined Document ID 215; 216; 268; 1373; 1383; 3786;
3996; and 4114. The analysis is in Exhibit: Analysis of Plant Floor
Space, available in Docket OSHA-2010-0034 at www.regulations.gov).
For the purpose of estimating cleaning costs, OSHA characterized
establishments with fewer than twenty employees as very small
establishments, and characterized establishments with twenty or more
employees as larger establishments.
OSHA determined, based on a review of the data in the NIOSH field
studies, that production floor space averages 725 square feet per
employee (See Exhibit: Analysis of Plant Floor Space).
For very small establishments with fewer than 20 employees, OSHA
used an average of 7 employees per establishment. For larger
establishments, OSHA used an average of 80 employees. (These estimates
of the number of employees are based on OSHA (2016), which shows that
the average number of employees for establishments with fewer than 20
employees is 7 employees and that the average number of employees for
establishments with more than 20 employees is 80 employees.) Based on
these parameters, OSHA's floor space model found that the typical floor
space for very small establishments is 5,075 square feet and for larger
establishments is 58,000 square feet.
ERG spoke with a representative of an upper-Midwestern firm
specializing in the industrial cleaning of foundries and related
facilities (Document ID 3817, p. 2). According to that representative,
cleaning costs depend on numerous factors, such as the distance to the
facility that needs to be cleaned, the size and number of machines and
pieces of equipment present, the types of required cleaning activities,
and the presence of confined spaces. The representative described one
of his company's clients as a sand-casting foundry that produces 42,000
tons of gray and ductile iron castings per year in a 210,000 square
foot facility. According to the representative, a crew of two
technicians cleans the facility every 2 to 3 weeks at a cost of $2,200
to $3,500 per cleaning, which requires one day, or roughly $0.01 to
$0.02 per square foot in 2014 dollars.
For the FEA, OSHA is estimating, based on data from the ERG field
interviews, that it will take 4 to 5 days to perform a one-time initial
cleaning (remove all visible silica dust) and that if the same facility
is cleaned every 2 to 3 weeks it will take 1 day to clean it. At a cost
of $0.02 per day per square foot, and using a cleaning duration of 5
days, OSHA calculated a cost of $0.15 per square foot in 2012 dollars
for an initial thorough cleaning. This value is derived from inflating
the 2003 estimate of $0.10 per square foot ($0.02 per day per square
foot over 5 days) to 2012 dollars, which raised the cost to $0.12 per
square foot. OSHA also allowed for an additional allotment of 25
percent of the estimated cost of $0.12 per square foot (in 2012
dollars) to ensure that the cleaning was sufficiently thorough to
achieve compliance, increasing the total from $0.12 to $0.15. OSHA
judges that this is a reasonable average for the range of facilities to
be covered, especially given that some annual cleaning is probably
already occurring at most facilities and therefore the full cost of
cleaning would not be attributable to this rule. The costs here are
applied to represent an incremental cleaning beyond that employed for
normal business purposes.
As discussed earlier in this chapter, URS, an engineering
consultant to ACC, estimated that a thorough annual professional
cleaning will cost about $1.00 per square foot of a facility's process
operations area. URS provided no specific reference for that unit
estimate other than that it communicated with industry representatives
(Document ID 2308, Attachment 8, p. 24). The data OSHA used to develop
its cost estimates are based on interviews with a company that provides
housekeeping services rather than companies that may or may not have
purchased such services. OSHA's estimated costs for a thorough initial
cleaning are over five times the costs of a thorough cleaning where
there is just few weeks' worth of accumulated dust. Greater
accumulations during an initial cleaning do not mean that the initial
cleaning will cost 50 times the cost of a more basic/regular cleaning,
as much of the cost of the initial cleaning will be due to the time
spent going over the entire facility with the appropriate cleaning
devices--a cost that is fixed by area and not by accumulation. OSHA
therefore rejects the URS unit estimate of $1.00 per square foot as not
representative of a typical cost for initial thorough facility
cleaning, particularly for firms that choose to use in-house resources.
Nonetheless, OSHA acknowledges that unique circumstances may create higher
unit costs than the value OSHA is using in the FEA. OSHA also acknowledges
that the cost of cleaning per square foot probably declines as facility
size increases (Document ID 4231, p. 4). The paucity of data on square
footage for the affected facilities, however, did not allow for further
modeling of cleaning costs.
For this final analysis of costs for initial thorough facility
cleaning, OSHA estimated that an upfront, one-time, extensive servicing
(using vacuum and wash equipment) to rid the production area of
respirable crystalline silica during plant turnaround or other downtime
would cost $0.15 per square foot (including the additional allowance to
ensure a sufficiently thorough cleaning) or $0.02 when annualized at 3
percent for 10 years, and OSHA applied that unit cost along with the
average production floor space discussed above in OSHA's cost model
(725 square feet per employee) to derive final costs for facility
cleaning by application group. For the seven affected application
groups, OSHA estimates that annualized initial thorough facility
cleaning costs will range from just under $45,000 for Nonferrous Sand
Foundries to $488,000 for Concrete Products. Across all seven affected
application groups, OSHA estimates that annualized costs for initial
thorough facility cleaning will total $2.8 million.
Conveyor Covers
The technological feasibility analysis in the PEA recommended
reducing silica exposures by enclosing process equipment, such as
conveyors, particularly where silica-containing materials were
transferred (and notable quantities of dust can become airborne), or
where dust is generated, such as in sawing or grinding operations. For
the PEA, OSHA estimated the capital costs of conveyor covers as $20.73
(updated to 21012 dollars) per linear foot, based on Landola (2003,
Document ID 0745) (as summarized in footnote a in Table V-3 of the
PEA). OSHA estimated that each work crew of four affected workers would
require 100 linear feet of conveyors. OSHA, based on ERG's estimates,
calculated maintenance costs as 10 percent of capital costs. Based on
the technological feasibility analysis, OSHA also included the cost of
LEV on the vents of the conveyors for the structural clay, foundry,
asphalt roofing, and mineral processing application groups, but not for
the glass and mineral wool application groups.
URS commented that OSHA underestimated the length of conveyors by
using 100 linear feet in its estimate, and suggested that the estimate
of 200 feet that it used as the basis for its estimates was still an
underestimation for some foundries (Document ID 2307, Attachment 26,
Control Basis and Control Changes tabs). URS maintained OSHA's estimate
of $20.73 per linear foot in its own calculations. However, it appears
that URS did not understand that OSHA estimated 100 linear feet of
conveyors for every 4 workers, not 100 linear feet of conveyors for an
entire affected establishment. Further, the URS comment indicated that
100 linear feet was an underestimate for "medium and large
foundries." But because OSHA's estimate of 100 linear feet is for
every four workers, OSHA actually estimated much longer conveyor
lengths for larger facilities with more workers. OSHA has determined
that its estimate of 100 linear feet for every four workers at a cost
of $20.73 per linear foot is a reasonable approach for estimating the
costs of conveyor covers.
Selected Control Options That Are Not Costed
Consistent with ERG's cost model, in the PEA OSHA chose not to
estimate costs for some control options mentioned in the accompanying
technological feasibility analysis in Chapter IV of the PEA. In these
cases, OSHA judged that other control options for a specific at-risk
occupation were sufficient to meet the PEL. AFS identified several
control options for which OSHA did not estimate costs:
Substitution of non-silica sand (V-A-51)
Pneumatic sand handling systems (V-A-51)
Didion drum to clean scrap for furnace operators (V-A-52)
Non-silica cores and core coatings (V-A-52)
Professional cleaning costs and associated downtime (V-A-52)
Physical isolation of pouring areas (V-A-52)
Modify ventilation system to reduce airflow from other areas
(V-A-52)
Automation of a knockout process (V-A-53)
Automated abrasive blast pre-cleaning of castings for
finishing operators (V-A-54)
Wet methods (V-A-54)
Low silica refractory (V-A-55) (Document ID 2379, p. 16)
Just because a control is mentioned in the technological
feasibility analysis does not mean that OSHA has determined that its
use is required--only that it represents a technologically feasible
method for controlling exposures. The Agency developed cost estimates
based on the lowest cost combination of controls that allows employers
to move from an uncontrolled situation to meeting the new PEL. OSHA did
not include the costs for possible controls that were either more
expensive or were not necessary to achieve the PEL. OSHA (2016)
describes in detail which controls were considered necessary to achieve
the PEL. OSHA continues in the FEA to exclude costs for these kinds of
more expensive possible controls.
Railroads
In its preliminary estimates, OSHA inadvertently applied the
preceding general industry PEL of 100 [mu]g/m\3\ in its analysis of the
railroad industry. Silica exposures among railroad employees, however,
result from ballast dumping, which is track work that is generally
subject to OSHA's construction standard and covered by the preceding
construction PEL of 250 [mu]g/m\3\ (see discussion of railroads in
Chapter III, Industry Profile). As a result, OSHA has changed its
conclusion that there would be no incremental costs for railroads to
meet the new PEL. OSHA has reassigned all costs previously assigned to
meeting the preceding PEL to being incremental costs of meeting the new
PEL. Although the railroad activities affected by the new silica rule
will typically constitute construction work, OSHA has categorized all
compliance costs for railroads with general industry costs under NAICS
482110 because the railroad industry is predominantly engaged in non-
construction work and its NAICS code is not typically classified as a
construction code.
Costs of Engineering Controls for Hydraulic Fracturing in the PEA
Both in the PEA and in the FEA, OSHA presented the methods of
estimating the costs of controlling silica exposures during hydraulic
fracturing separately from the engineering control costs for all other
portions of general industry because there are some fundamental
differences in the methodology OSHA used, and thus in the comments OSHA
received on that methodology. In the PEA, OSHA began its analysis of
hydraulic fracturing in the standard way of examining the set of
engineering controls available to control employee exposures to silica.
Unlike the way OSHA handled the rest of general industry, however, for
hydraulic fracturing OSHA identified precisely which controls were
necessary to go from current levels of exposure to the preceding
general industry PEL of 100 [mu]g/m\3\ and then what further
controls would be necessary to go from the preceding general industry
PEL of 100 [mu]g/m\3\ to the new PEL of 50 [mu]g/m\3\. OSHA took a
different approach for this sector because the data available for this
industry, as a result of an extensive set of site visits, were adequate
to make this type of determination. OSHA determined that a combination
of wet methods, partial enclosure, and LEV controls would be sufficient
to meet a PEL of 100 [mu]g/m\3\ for hydraulic fracturing. OSHA then
determined that LEV controls at thief hatches and operator enclosures
would be sufficient to reduce exposures during hydraulic fracturing
from 100 [mu]g/m\3\ to 50 [mu]g/m\3\. The costs of these additional
engineering controls were shown in Tables A-14, A-15, and A-16 for
large, medium, and small fleets, respectively, in the PEA (the full
derivation of the results in these tables can be found in ERG, 2013,
Document ID 1712).
As discussed in the Industry Profile section of the FEA (Chapter
III), the basic unit for analysis for this industry is the fleet rather
than the establishment. Rather than allocating costs according to the
proportion of workers above a given exposure level, as was done for the
rest of general industry, for hydraulic fracturing the controls applied
per fleet were judged to reduce the exposures of all workers associated
with the fleet.
Public Comments on OSHA's Preliminary Cost Estimates for Engineering
Controls in Hydraulic Fracturing
General Methodology
Though there were extensive comments on OSHA's estimates of
engineering control costs for hydraulic fracturing, no commenter
objected to the differences in methodology compared to OSHA's treatment
of the other general industry sectors (as outlined above). Halliburton
Energy Services, Inc. commented that OSHA's analysis "lacks data"
(Document ID 4211, p. 5). As discussed in Chapter IV Technological
Feasibility, OSHA agrees that there is limited experience with many
possible controls. For this reason, OSHA has allowed this industry an
extended compliance deadline of five years before they have to meet the
new PEL with engineering controls. However, OSHA does not agree that
this adds significant uncertainty to the costs analysis. The costs of
the controls OSHA has examined, and especially those needed to go from
the preceding general industry PEL to the new PEL can readily be
ascertained. It is possible that the cost of some controls that have
not yet been tested and that OSHA has not costed could be much lower
than the costs OSHA estimated in the PEA and in the FEA.
Compliance Rate
In the joint comments submitted by the American Petroleum Institute
and the Independent Petroleum Association of America (API/IPAA or "the
Associations"), the Associations disagreed with OSHA's estimated
current compliance rate for the use of engineering controls. In the
PEA, OSHA estimated a compliance rate of ten percent for engineering
controls in this industry. In their comments the Associations said that
"ERG assumed that 10% of all hydraulic fracturing firms already
utilize: (1) Baghouse controls; (2) caps on fill ports; (3) dust
curtains; (4) wetting methods; and (5) conveyor skirting systems"
(Document ID 2301, p. 40, fn. 148).
While OSHA used a compliance rate of ten percent for all of these
controls, it is not meant to represent that all prescribed controls are
used in ten percent of firms. OSHA's compliance rates take into account
that some well sites, as documented in Chapter IV of the FEA, were
observed to be using a variety of controls that reduce dust levels, and
as a result, those firms will not need to implement as many additional
controls in order to achieve the new PEL. Further, as noted in Chapter
IV of the FEA, the industry is constantly installing additional
controls to reduce silica exposures. Thus the Agency sees no reason to
change its estimate of current compliance. In any case, removing the
assumption would make only a ten percent difference to the cost
estimates, which would not be a change of large enough magnitude to
threaten OSHA's conclusion that compliance with the final rule is
economically feasible for the hydraulic fracturing industry.
Maintenance Costs
In the PEA, OSHA estimated that the life of most capital equipment
would be ten years, and that maintenance and operating costs would
range from ten to thirty percent of capital costs per year (ten percent
being most common).
API/IPAA argued that the hostile, sandy environment of the well
site shortens the useful life of equipment and increases maintenance
costs. The Associations estimated that the useful life of equipment
ranges from 5 years to 7.5 years and that annual operating and
maintenance costs range from 10 percent to 25 percent of capital costs.
While OSHA agrees that the oilfield environment is challenging and
dusty, there is no evidence in the record that these environments are
more challenging than other industrial settings where equipment lives
of 10 years and operating and maintenance costs of 10 to 30 percent
have been used as reasonable estimates.
Cost of Specific Controls
Dust Booths
In the PEA, OSHA estimated that there would need to be one dust
booth for each sand moving machine, and that this would result in one
dust booth for small fleets, three for medium fleets, and five for
large fleets. In critiquing OSHA's cost analysis for hydraulic
fracturing, API/IPAA disagreed with OSHA's estimates that only sand
mover operators would need to utilize dust control booths in order to
achieve the new PEL (Document ID 2301, p. 69). API/IPAA suggested that
instead there would need to be one booth per affected worker and that
only one worker could utilize a given booth. In the Associations'
estimate this would mean that there would need to be 3, 8 and 12 booths
for small, medium, and large fleets, respectively (Document ID 2301,
Attachment 4, Dust Booths, row 9).
As discussed in the technological feasibility chapter of the FEA,
OSHA agrees that workers other than sand mover operators will need to
use dust booths. However, OSHA does not agree that a booth can only
accommodate a single person. These booths are places of refuge and are
not assigned to specific individuals. The technological feasibility
chapter in the FEA determined that dust booths can accommodate more
than one person per booth. Because OSHA agrees that more employees than
sand mover operators will need booths, OSHA has raised its estimates of
booths needed by size class from 1, 4, and 5 booths to 3, 6, and 8
booths. While this estimate of the number of booths is lower than that
recommended by API/IPAA, OSHA finds that these booths can accommodate 2
persons per booth and thus can accommodate more workers than API/IPAA
suggested.
In the PEA, OSHA estimated the transportation costs for booths as
$37.25 per booth. API/IPAA disagreed. The Associations argued that a
cost of $513 for a small fleet, which would only have one booth, would
be more appropriate (Document ID 2301, p. 69). Most of the difference
between API/IPAA's cost estimate for deploying dust control booths and
OSHA's estimate is attributable to the fact that the Associations
presented their cost per fleet and OSHA presented its cost per
booth. API/IPAA applied their estimate of the number of booths
necessary at these worksites when deriving their estimate and they
estimated about six times as many booths being necessary as OSHA did.
However, after further examination of this cost, OSHA determined that
the standard per-mile shipping rate that it used to estimate
transportation costs in the PEA was applied incorrectly. This resulted
in an estimate of transportation costs for booths in the PEA that was
too low. OSHA has determined that the cost to transport dust booths
presented by the Associations more completely captured the costs
associated with transporting these booths. For the FEA, OSHA has
accepted the Associations' per-fleet transportation cost of $513 for
each booth and applied the cost to the Agency's estimate of the number
of booths necessary to control silica exposures on well sites.
Water Misting
In the PEA, OSHA estimated that water misting system would be
needed to control residual emissions from some releases from sand
moving systems. These water misting systems were estimated to cost
$60,000 per fleet to purchase and an additional 20 percent of the
purchase cost for installation. API/IPAA incorrectly assumed that these
water misting systems were intended to control all dust emission from
truck traffic and other sources (Document ID 2301, pp. 69-70). This was
not the case--dust suppression for truck and other traffic was costed
at a much higher rate separately from water misting.
OSHA's cost estimates for misting systems were based on
conversations with a mining dust control specialist who indicated the
price and efficacy of available water misting systems (Document ID
1571). While API/IPAA disagreed with OSHA's costs, they did not offer
any data to show an alternative cost, instead simply carrying OSHA's
estimate for water misting systems forward in their analysis to arrive
at their cost estimate (Document ID 2301, Attachment 3, Water Misting,
cells K:O6 and J8). OSHA has determined that the equipment that formed
the basis for its cost estimates in the PEA may not be durable enough
to stand up to the wear from frequent loading, unloading, and
transportation. Therefore, the Agency, based on its own judgement, has
increased the estimated cost of a water misting system by 33 percent in
order to account for the need for a more durable system. Based on this,
OSHA's final cost analysis for hydraulic fracturing includes costs of
$79,800 per fleet to purchase the equipment plus installation costs of
$15,960 for installation (20 percent of the purchase price) for water
misting equipment to control residual dust emissions from sand moving
systems.
Costs of Transportation
In developing the costs for hydraulic fracturing firms to comply
with this rule in the PEA, it was determined that the baghouse controls
that are commercially available are integrated into sandmover units and
therefore should not present any logistical difficulties for
transportation purposes. However, in examining the costs to transport,
assemble, and disassemble the control equipment, API/IPAA noted
potential difficulties in adding baghouse controls to sandmovers, which
are often nearly at weight limits for road movement (Document ID 2301,
p. 71).
OSHA's determination about integrated units has not changed since
the PEA. The existence of integrated units is further discussed in
Chapter IV of the FEA, Technological Feasibility. OSHA notes that
sandmover units are not the heaviest items transported by hydraulic
fracturing firms, so the additional weight associated with baghouse
controls would be insignificant in this context. These firms are highly
experienced in moving the heavy, bulky equipment needed on well sites
and including additional controls on this equipment is not expected to
create a situation that exceeds the capabilities of these firms.
Containerized Systems
Commenting on OSHA's analysis of the cost of controls for hydraulic
fracturing, API/IPAA expressed concern that OSHA was considering
requiring the use of containerized systems. The Associations stated
that these systems would be economically infeasible for small fleets
and raised questions about whether these systems would be sufficient to
allow fleets using them to achieve the PEL (Document ID 4222, p. 7).
Neither in the PEA nor the FEA has OSHA's cost analysis reflected the
use of containerized systems, nor does OSHA require their use. Instead,
containerized systems represent a possible technological change that
could potentially reduce the costs of silica control. OSHA has in no
way quantitatively tried to estimate the effects of this possible
reduction.
Conveyor Skirting
In the PEA, OSHA found that conveyor skirting systems with
appropriate LEV would be needed to meet the new PEL, and included the
cost of such controls in the incremental costs associated with the new
PEL. As discussed in Chapter IV, Technological Feasibility, in the FEA,
however, OSHA now finds that these conveyor skirting systems will be
needed to meet the preceding PEL, but not to further lower exposures to
the new PEL, so OSHA is not including costs for these controls as
incremental costs associated with achieving the new PEL. As a result,
the FEA does not include costs for conveyor skirting systems and LEV.
Dust Suppression--Control of Dust Generated From Traffic
On the other hand, dust suppression to control silica emissions
generated by truck traffic, estimated in the PEA as necessary only to
meet the preceding PEL, has now been determined to be necessary to meet
the new PEL (see Chapter IV, Technological Feasibility in the FEA). As
a result, in the FEA OSHA added the costs of dust suppression to
control silica dust generated by truck traffic to the estimated
incremental costs of meeting the new PEL. OSHA estimates that dust
suppression is more expensive in the aggregate than conveyor skirting
systems with appropriate LEV.
OSHA made two additional changes to the costs of dust suppression
from the PEA to the FEA. First, OSHA accepted the unit costs for dust
suppression application provided by API/IPAA (Document ID 2301,
Attachment 3, Dust Suppression). This unit cost is somewhat lower than
the original estimate that OSHA adopted in the PEA (Document ID 1712).
This seems reasonable to OSHA based on the costs of the most commonly
used dust suppression materials. Second, OSHA has determined that these
controls will be utilized to reduce exposures for ancillary support
workers and remote/intermittent workers, 50 percent of whom work in
situations that currently have exposures below the new PEL (as shown in
the exposure profile in the section on hydraulic fracturing in Chapter
IV, of the FEA, technological feasibility). As a result, instead of
assigning dust suppression costs for all wells (as in the PEA), OSHA
determined in the FEA that dust suppression costs would be incurred by
50 percent of wells. This aligns with a view that, in many cases,
natural conditions (silica content of soils, dustiness, wetness and/or
climate) are such that dust suppression is not needed.
Small Business Considerations
Small Business Regulatory Enforcement Fairness Act (SBREFA) Comments on
Compliance
Costs in General Industry and Maritime
Before publishing the NPRM, OSHA received comment on the accuracy
of its unit costs through the Small Business Advocacy Review (SBAR)
Panel process.
The Small Entity Representatives (SERs) who participated in the
2003 SBAR Panel process on OSHA's draft standards for silica provided
many comments on the estimated compliance costs OSHA presented in the
Preliminary Initial Regulatory Flexibility Analysis (PIRFA) for general
industry and maritime (Document ID 0938).
In response to the SERs' comments, OSHA carefully reviewed its cost
estimates and evaluated the alternative estimates and methodologies
suggested by the SERs. OSHA updated all unit costs presented in the
PIRFA to reflect the most recent cost data available and inflated all
costs to 2009 dollars prior to publication of the proposed rule.
However, the Agency generally determined that the control cost
estimates in the PIRFA were based on sound methods and reliable data
sources.
For the PEA, OSHA reviewed the SERs' cost estimates for small
entities in the foundry and structural clay industries. Given that
those SERs did not report their own sizes, the Agency could not compare
their estimates to the estimates in the PEA. OSHA concluded that the
compliance costs reported by the SERs in general industry that did
provide size data were not incompatible with OSHA's own estimates of
the costs of engineering controls to comply with the PEL. As discussed
above, for the FEA, OSHA has halved the number of workers assumed to be
covered by each control for most controls in establishments with fewer
than twenty employees, which results in a doubling of the engineering
control costs for these establishments.
Comments and Responses on Costs for Small Establishments
Stuart Sessions, testifying on behalf of ACC, argued that OSHA had
underestimated costs to small establishments for two reasons: (1) Small
establishments may have higher exposures and therefore many need to
spend more money installing controls to reduce those exposures; and (2)
costs to small establishments may involve diseconomies of scale--
whereby smaller facilities would have to pay more per unit to procure
and install systems--that OSHA had not accounted for (Document ID 4231,
Attachment 1, pp. 2-4).
With respect to the issue about small establishments having higher
exposures--the commenter simply asserted that this is the case without
providing any evidence to support the claim. Mr. Sessions speculated
that smaller businesses have a "lesser ability to afford compliance
expenditures and lesser ability to devote management attention to
compliance responsibilities" (Document ID 4231, Attachment 1, p. 2).
While it is possible that very small establishments may not have the
same controls already in place as large establishments, as asserted by
the commenter, this does not necessarily mean that very small
establishments will have higher exposures. Small and very small
establishments typically only have one shift per day, so fewer shifts
are being worked where there is a potential for exposure. They also may
spend more time on activities not involving silica exposures. For
example, a small art foundry that produces one or two castings a week
will simply spend proportionally less time on activities that lead to
silica exposure than a large production foundry.
With respect to the issue of diseconomies of scale, OSHA has taken
this phenomenon into account in its cost estimates in the FEA. First,
in order to provide a conservative estimate of costs for the purposes
of determining the impacts on very small employers, OSHA has revised
what Mr. Sessions called "the most inappropriate of OSHA's
assumptions" (Document ID 4231, Attachment 1, p. 6). In the PEA, OSHA
estimated that a single control would reduce the exposures of four
workers. For the FEA, OSHA has revised its estimates so that the number
of workers whose exposures are reduced by a control are half that used
in the PEA for establishments with fewer than 20 employees--reducing
the number of workers covered by a control from four to two. OSHA made
this adjustment even though there are ways in which small
establishments may have lower costs per cfm than larger establishments.
For capital costs, a major element of cost per cfm is the length of
ductwork. Within the same industry, the length of ductwork will be much
shorter in smaller establishments. For operating costs per cfm, length
of operating time is a key element of costs.
OSHA has continued to estimate that the exposures of four employees
whose exposures would be reduced per control for establishments with
more than twenty employees (even though it is likely that more than
four workers have their exposures reduced per control in the largest
establishments). This effectively means that very large establishments
with hundreds of employees have been modeled as if their costs were
equivalent to that of several 20-40 person establishments combined. Far
from neglecting diseconomies of scale, in an effort to be conservative
and adequately account for the challenges faced by smaller
establishments, OSHA has instead neglected to account for economies of
scale in larger establishments.
Mr. Sessions calculated some higher overall costs for smaller
establishments (Document ID 4231, Attachment 1, pp. 6-10). However,
these costs are critically dependent on the assumptions already
addressed and rejected by OSHA, such as that exposures are random and
that any exposures require that all possible controls be installed to
control those exposures.
Final Control Costs
Unit Control Costs
Methodology
For the FEA, OSHA used unit costs developed in the PEA for specific
respirable crystalline silica control measures from product and
technical literature, equipment vendors, industrial engineers,
industrial hygienists, and other sources, as relevant to each item.
Some PEA estimates were modified for the FEA based on comments in the
record, and all costs were updated to 2012 dollars. Specific sources
for each estimate are presented with the cost estimates. Wherever
possible, objective cost estimates from recognized technical sources
were used. Table V-4 in the FEA provides details on control
specifications and data sources underlying OSHA's unit cost estimates.
Summary of Control Costs for General Industry and Maritime
Table V-5 in the FEA summarizes the estimated number of at-risk
workers and the annualized silica control costs for each application
group. Control costs in general industry and maritime for firms to
achieve the PEL of 50 [mu]g/m\3\ level are expected to total $238.1
million annually. As shown, application group-level costs exceed $15.0
million annually for concrete products, hydraulic fracturing, iron
foundries, railroads, and structural clay.
Table V-6 in the FEA shows aggregate annual control costs in
general industry and maritime by NAICS industry. These costs reflect
the disaggregation of application group costs among the industries that
comprise each group (see Table III-1 in Chapter III of the FEA on the
profile of affected industries.)
b. Control Costs in Construction
In both the PEA and the FEA, OSHA determined that employers, in
order to minimize exposure monitoring costs, would select appropriate
controls from Table 1. The final estimate for control costs, however,
includes Table 1 control costs for a larger number of employees than in
the PEA. For the purpose of estimating control costs in the PEA, OSHA
examined all of the employers with employees engaged in Table 1 tasks
but judged that only a subset of those employers (those with workers
exposed above the proposed silica PEL) would require additional
engineering controls. For this final rule, OSHA has judged, for costing
purposes, that all of the construction employers with employees
performing any task covered in Table 1 will adopt the engineering
controls for that task as specified in Table 1. Thus, in the FEA, OSHA
took the more conservative approach--which may result in an
overestimate of costs--of identifying the cost of controls for all
employers with employees engaged in Table 1 tasks, not just the subset
of employers with employees exposed above the PEL. However, as
discussed in Chapter III of the FEA, OSHA did adjust control costs to
reflect the 44 percent of workers in construction currently exposed at
or below the PEL who are estimated to be in baseline compliance with
the Table 1 requirements.
OSHA is also likely overestimating the cost of controls for another
reason. If the employer is able to demonstrate by objective data, or
other appropriate means, that worker exposures would be below the
action level under any foreseeable conditions, the employer would be
excluded from the scope of the final rule. These employers would not
require additional controls. OSHA did not have sufficient data to
identify this group of employers and did not try to reduce the costs to
reflect this group, so OSHA's estimate of costs is therefore
overestimated by an amount equal to the costs for those employers
engaged in covered construction tasks but excluded from the scope of
the rule.
A few tasks involving potentially hazardous levels of silica
exposure are not covered in Table 1. Employers would have to engage in
exposure monitoring for these tasks pursuant to paragraph (d) and use
whatever feasible controls are necessary to meet the PEL specified in
paragraph (d)(1). For example, tunnel boring and abrasive blasting are
not covered by Table 1 and are therefore addressed separately in this
cost analysis. Although several commenters identified various other
activities that they believed were not covered by Table 1 that could
result in crystalline silica exposure over the PEL (Document ID 2319,
pp. 19-21; 2296, pp. 8-9), some of these activities were simply
detailed particularized descriptions of included activities. For
example, overhead drilling is addressed in the FEA, Chapter IV-5.4 Hole
Drillers Using Handheld or Stand-Mounted Drills, and the demolition of
concrete and masonry structures is addressed in the FEA, Chapter IV-5.3
Heavy Equipment Operators. For the remainder, the available exposure
data did not indicate that these activities resulted in a serious risk
of exposure to respirable crystalline silica (see FEA, Chapter III
Industry Profile, Construction, Public Comments on the Preliminary
Profile of Construction and Summary and Explanation, Scope and
Application); furthermore, these other activities could be addressed
using the controls identified in the FEA. Because OSHA did not have
sufficient data to identify a significant number of silica exposures
above the PEL of 50 [mu]g/m\3\ for these activities, the Agency did not
include costs for controlling silica exposures during these activities.
Nevertheless, to the extent that employers find it necessary to
implement controls for any activity that OSHA did not explicitly
include in this analysis, the FEA shows that those controls are clearly
economically feasible.
The control costs for the construction standard are therefore based
almost entirely on the tasks and controls specified in Table 1. Most of
the remainder of this section is devoted to explaining the manner in
which OSHA estimated the costs of applying appropriate engineering
controls to construction activities as required by Table 1 of the final
standard. These costs are generated by the application of known dust-
reducing technology, such as the application of wet methods or
ventilation systems, as detailed in the technological feasibility
analysis in Chapter IV of the FEA. These costs are discussed first,
and, following that, the control costs for tasks not specified in Table
1 are separately estimated.
OSHA revised Table 1 between the PEA and the FEA. The entries
included in the table have been modified with some tasks being added
and some being removed.\35 \In addition, the methods of controlling
exposures that Table 1 requires for certain tasks have changed in
response to comments and additional analysis. Excluding changes to
respirator requirements, which are addressed elsewhere in this
preamble, significant and substantive revisions to Table 1 that have
the potential to impact control costs include:
---------------------------------------------------------------------------
\35\ Additionally, the nomenclature changed from "Operation"
in the NPRM to "Equipment/Task" in the final rule.
---------------------------------------------------------------------------
New entries on Table 1--
[cir] Handheld power saws for cutting fiber-cement board (with
blade diameter of 8 inches or less)
[cir] Rig-mounted core saws and drills
[cir] Dowel drilling rigs for concrete
[cir] Small drivable milling machines (less than half-lane)
[cir] Large drivable milling machines (half-lane and larger for
cuts of any depth on asphalt only and for cuts of four inches in depth
or less on any other substrate)
[cir] Heavy equipment and utility vehicles used to abrade or
fracture silica-containing materials (e.g., hoe-ramming, rock ripping)
or used during demolition activities involving silica-containing
materials.
[cir] Heavy equipment and utility vehicles for tasks such as
grading and excavating but not including: Demolishing, abrading, or
fracturing silica-containing materials
Removed entry for drywall finishing from Table 1
Revised entries on Table 1--
[cir] Drivable saw entry revised to permit outdoor use only.
[cir] Portable walk-behind or drivable masonry saws divided into
two entries--walk-behind saws and drivable saws.
[cir] Handheld drills entry revised to include stand-mounted drills
and overhead drilling.
[cir] Combined entries for vehicle-mounted drilling rigs for rock
and vehicle-mounted drilling rigs for concrete.
[cir] Milling divided into three tasks--walk-behind milling
machines and floor grinders; small drivable milling machines (less than
half-lane); and large drivable milling machines (half-lane and larger
with cuts of any depth on asphalt only and for cuts of four inches in
depth or less on any other substrate).
[cir] Heavy equipment used during earthmoving divided into two
tasks--(1) heavy equipment and utility vehicles used to abrade or
fracture silica-containing materials (e.g., hoe-ramming, rock ripping)
or used during demolition activities involving silica-containing
materials, and (2) use of heavy equipment and utility vehicles for
tasks such as grading and excavating but not including: Demolishing,
abrading, or fracturing silica-containing materials.
[cir] Revised crushing machines entry to require equipment designed
to deliver water spray or mist for dust suppression and a ventilated
booth or remote control station.
In addition to the new and revised tasks in Table 1, some of the
controls and specifications required by Table 1 were revised for this
final rule, including removal of "Notes/Additional Specifications"
from individual Table 1 entries and addition of substantive paragraphs
after the table. Those revisions include:
Revised or newly required controls/specifications for
Table 1 tasks--
[cir] Revised requirement to operate and maintain tools/machine/
equipment in accordance with manufacturer's instructions to minimize
dust emissions.
[cir] Revised specifications for dust collectors to require they
provide at least 25 cubic feet per minute (cfm) of air flow per inch of
blade/wheel diameter (for some, but not all entries that include a dust
collection system as a control method).
[cir] Revised specification for dust collectors to require they
provide the air flow recommended by the tool manufacturer, or greater,
and have a filter with 99 percent or greater efficiency and a filter-
cleaning mechanism (for some, but not all entries that include a dust
collection system as a control method). The entries for handheld
grinders for mortar removal (i.e., tuckpointing) and handheld grinders
for uses other than mortar removal require a cyclonic pre-separator or
filter-cleaning mechanism.
[cir] Revised requirement for tasks indoors or in enclosed areas to
provide a means of exhaust as needed to minimize the accumulation of
visible airborne dust (paragraph (c)(2)(i)).
[cir] Added requirement for wet methods to apply water at flow
rates sufficient to minimize release of visible dust (paragraph
(c)(2)(ii)).
[cir] Revised specifications for enclosed cabs to require that
cabs: (1) Are maintained as free as practicable from settled dust; (2)
have door seals and closing mechanisms that work properly; (3) have
gaskets and seals that are in good condition and working properly; (4)
are under positive pressure maintained through continuous delivery of
fresh air; (4) have intake air that is filtered through a filter that
is 95% efficient in the 0.3-10.0 [mu]m range (e.g., MERV-16 or better);
and (5) have heating and cooling capabilities (paragraph (c)(2)(iii)).
[cir] Added requirement to operate handheld grinders outdoors only
for uses other than mortar removal, unless certain additional controls
are implemented.
[cir] Added wet methods option for use of heavy equipment and
utility vehicles for tasks such as grading and excavating but not
including: Demolishing, abrading, or fracturing silica-containing
materials.
[cir] Added requirement to use wet methods when employees outside
of the cab are engaged in tasks with heavy equipment used to abrade or
fracture silica-containing materials (e.g., hoe-ramming, rock ripping)
or used during demolition activities involving silica-containing
materials.
Removed controls/specifications for Table 1 tasks--
[cir] Removed requirements to change water frequently to avoid silt
build-up in water.
[cir] Removed requirements to prevent wet slurry from accumulating
and drying.
[cir] Removed requirements to operate equipment such that no
visible dust is emitted from the process.
[cir] Removed local exhaust dust collection system option and
requirement to ensure that saw blade is not excessively worn from the
entry for handheld power saws.
[cir] Removed requirement to eliminate blowing or dry sweeping
drilling debris from working surface from the entry for handheld and
stand-mounted drills (including impact and rotary hammer drills).
[cir] Removed additional specifications for dust collection systems
for vehicle-mounted drilling rigs for concrete (e.g., use smooth ducts
and maintain duct transport velocity at 4,000 feet per minute; provide
duct clean-out points; install pressure gauges across dust collection
filters; activate LEV before drilling begins and deactivate after drill
bit stops rotating).
[cir] Removed requirements to operate grinder for tuckpointing
flush against the working surface and to perform the work against the
natural rotation of the blade.
[cir] Removed dust collection system option and requirement to use
an enclosed cab from crushing machines.
These and other changes to Table 1 are discussed in detail in
Section XV: Summary and Explanation of this preamble. While Table 1 has
changed with regard to the tasks included and the control methods
required, OSHA's methodology used to estimate the costs of controls for
the construction industry has remained basically the same as that
explained in detail in the PEA, with steps added (and explained in the
following discussion) to address cost issues raised during the comment
period and the updates and revisions to Table 1. OSHA summarizes the
methodology in the following discussion, but the PEA includes
additional details about the methodology not repeated in the FEA.
OSHA adopted the control cost methodology developed by ERG (2007a,
Document ID 1709) for the PEA and subsequently for the FEA. In order to
provide some guidance on that cost methodology, OSHA itemizes below the
three major steps, with sub-tasks, used to estimate control costs in
construction, with two additional steps added for the FEA to estimate
the number of affected workers by industry and equipment category \36\
(numbered Step 3) and to estimate control costs for self-employed
persons (numbered Step 5)--tables referenced below are in Chapter V of
the FEA:
---------------------------------------------------------------------------
\36\ The term "equipment category" as used here matches the
broad headings used in the Technological Feasibility analysis. Later
on in this section, OSHA identifies which Table 1 tasks are included
in each equipment category.
---------------------------------------------------------------------------
Step 1: Baseline daily costs, relative costs of controls,
and labor share of value
[cir] Use RSMeans (2008, Document ID 1331) estimates to estimate
the baseline daily cost for every representative job associated with
each silica equipment category (Table V-30) and unit labor and
equipment costs (Table V-31).
[cir] Use vendors' equipment prices and RSMeans estimates to
estimate the unit cost of silica controls (Table V-32), and estimate
the productivity impact for every silica control and representative
job, to be added to the cost of the control applied to a particular job
(Table V-33).\37\
---------------------------------------------------------------------------
\37\ This latter sub-step was performed in the PEA, but it was
inadvertently omitted in the text summary.
---------------------------------------------------------------------------
[cir] Use the costs from Tables V-32 and V-33 to calculate the
incremental productivity impact, labor cost, and equipment cost for
each representative job when controls are in place (Table V-34).
[cir] Using Tables V-30 and V-34, calculate the percentage
incremental cost of implementing silica controls for each
representative job (Table V-35).
[cir] Calculate the weighted average incremental cost (in
percentage terms) and labor share of total costs for each silica job
category (outdoors and indoors estimated separately) using the assumed
distribution of associated representative jobs (Tables V-36a and V-
36b).
Step 2: Total value of activities performed in all Table 1
silica equipment categories
[cir] Match BLS Occupational Employment Statistics OES
occupational classifications for key and secondary workers with the
labor requirements for each equipment category (Table V-37) and
estimate the full-time-equivalent (FTE) number of employees by key and
secondary occupations working on each silica task (Tables V-38a and V-
38b).
[cir] Based on the distribution of occupational employment by
industry from OES, distribute the full-time-equivalent employment
totals for each equipment category by NAICS construction industry
(Table V-39).
Step 3: Total affected employment by industry and
equipment category
[cir] Disaggregate construction industries into four distinct
subsectors based on commonality of construction work (Table V-40a) and
then estimate the percentage of affected workers by occupation,
equipment category, and construction subsector (Table V-40b).
[cir] Use the percentage of affected workers by occupation,
equipment category, and construction subsector (Table V-40b) to obtain
total affected employment by occupation (Table V-41) and total affected
employment by industry and task (Table V-42).
Step 4: Aggregate silica control costs (not including
self-employed persons)
[cir] Using the FTE employment totals for each task by NAICS
construction industry (Table V-39) and the mean hourly wage data from
OES, adjusted for fringe benefits, calculate the annual labor value of
each Table 1 silica activity by NAICS construction industry (Table V-
43).
[cir] Using the labor share of value calculated for each activity
performed in a silica-related equipment category (Table V-43), estimate
the total value of each Table 1 equipment/task category by industry
(Table V-44).
[cir] Estimate the distribution of silica work by equipment type,
duration of activity, and location of activity (Table V-45).
[cir] Multiply the total value of Table 1 construction activities
requiring controls (Table V-44) by the percentage incremental cost
associated with the controls required for each activity that uses
equipment in each equipment category (Tables V-36a and V-36b) and
weighted by the percentage of tasks performed outdoors and indoors/
within an enclosed space (Table V-45), to calculate the total control
costs, adjusted for baseline compliance, by Table 1 equipment category
and industry (Table V-46).
[cir] Calculate engineering control costs for silica-generating
construction activities not covered in Table 1 (Tables V-47a and V-
47b).
[cir] Combine the control costs for Table 1 construction activities
(Table V-46) and the control costs for construction activities not
covered in Table 1 (Tables V-47a and V-47b) to calculate the total
control costs by equipment category and construction industry (Table V-
48).
Step 5: Adjust aggregate silica control costs to include
self-employed persons
[cir] Use data from the BLS Current Population Survey to estimate
the ratio of the number of self-employed persons to the number of
employees by occupation (Table V-49) and then redo the estimation after
restricting self-employed persons to just those occupations covered by
OSHA that potentially involve exposure to hazardous levels of
respirable crystalline silica (Table V-50).
[cir] Multiply the FTE rate for each occupation (from Tables V-38a
and V-38b) by the number of self-employed workers and employees in that
occupation (from Table V-50) to obtain the ratio of FTE self-employed
persons to FTE employees and then reduce that ratio to reflect only
self-employed persons working on a multi-employer worksite where the
work of the self-employed person cannot be isolated in time or space
(Table V-51).
[cir] Increase the earlier estimate of control costs by equipment
category and industry (Table V-48) by the adjusted FTE ratio of self-
employed workers (Table V-40) to calculate total control costs by
equipment category and industry with self-employed persons included
(Table V-52).
Baseline Costs of Representative Jobs
Baseline Job Safety Practices
OSHA's cost estimates address the extent to which current
construction practices incorporate silica dust control measures. Thus,
OSHA's baseline reflects such safety measures as are currently
employed. To the limited extent that silica dust control measures are
already being employed, OSHA has reduced the estimates of the
incremental costs of silica control measures to comply with the new
PEL. As discussed in Chapter III of the FEA and summarized in Tables
III-A-1 and III-A-2, OSHA estimates that 44 percent of workers with
exposures currently below the new PEL are using the controls required
in Table 1.
Representative Jobs
Unlike the situation with the general industry/maritime standard,
OSHA does not have extensive data identifying the number of employees
engaged in Table 1 tasks or the duration of their exposure to
respirable crystalline silica during those tasks. Therefore, ERG
developed a model based on "representative jobs" for the purposes of
identifying the control costs necessary to comply with Table 1. Using
RSMeans Heavy Construction Cost Data (RSMeans, 2008, Document ID 1331),
which is a data source frequently used in the construction industry to
develop construction bids, ERG (2007a, Document ID 1709) defined
representative jobs for each silica-generating activity described in
the feasibility analysis. These activities and jobs are directly
related to the silica-related construction activities described in the
technological feasibility chapter of the FEA. ERG (2007a, Document ID
1709) specified each job in terms of the type of work being performed
(e.g., concrete demolition), the makeup of the crew necessary to do the
work, and the requisite equipment. For example, for the impact drilling
activity, ERG defined three representative jobs for various types of
demolition work. For each job, ERG derived crew composition and
equipment requirement data from the RSMeans (2008,Document ID 1331)
guide and then calculated the per-day baseline cost from the labor
rates, equipment charges, material costs, and overhead and profit
markups presented in the cost estimating guide.
Table V-30 of the FEA shows the specifications for each
representative job and the associated daily labor, equipment, and
material costs. Table V-31 of the FEA provides a summary of the labor
rates and equipment charges used to estimate the daily cost of each
representative construction job in Table V-30 of the FEA. Note that the
data on hourly wages with overhead and profit in Table V-31 of the FEA,
obtained from RSMeans (2008, Document ID 1331), are employed here to be
consistent with other RSMeans cost parameters to estimate the baseline
costs of representative jobs. The RSMeans estimates are published for
the purpose of helping contractors formulate job bids, so ERG relied on
that data as an indicator of the amount of labor and time that would be
required for each of the representative jobs in the cost model
developed for this analysis. These RSMeans estimates are later used
only to determine two ratios: The labor share of the costs of
representative construction jobs and the percentage increase in the
cost of each representative job due to the addition of controls to
comply with the final rule. Everywhere else in the cost chapter, when
the actual wages were important to the calculations and are expressed
as fixed amounts and not just ratios, OSHA used 2012 BLS wage data, which
include fringe benefits but not overhead and profit.
SBREFA Panel Comments on Cost Methodology for Construction
Prior to the publication of the PEA, one SBREFA commenter
criticized the methodology for estimating engineering control costs on
the grounds that while RSMeans estimates were used to establish the
marginal costs of new controls (as a percentage of baseline costs),
average wage rates (including fringe benefits) from the BLS
Occupational Employment Statistics Survey, 2000, were used to calculate
the value of at-risk tasks without providing a justification for not
using RSMeans wage data (Document ID 0968, p. 13). Since BLS wage rates
are significantly lower than the RSMeans rates used by ERG in earlier
parts of the analysis, the commenter argued that this would
significantly lower the base to which the marginal cost factors are
applied to estimate compliance costs (Id.). This SBREFA commenter
further argued that the RSMeans estimates are likely to be on the high
end of estimated wages because they only cover unionized labor and are
therefore likely to lead to high estimates of impacts. The commenter
then recommended that more appropriate indexed labor wage costs be
computed and used consistently throughout the analysis (Document ID
0968, p. 14).
First, the commenter's concern is misplaced because the choice of
the RSMeans estimates source does not skew the results in the manner
suggested by the commenter; nor does it even have a significant impact
on the cost analysis. The RSMeans estimates were used only to develop
the ratio of costs for the representative jobs to the total labor cost
and then to determine the incremental compliance costs as a percentage
of the total and the share (percentage) of estimate value with controls
accounted for by labor. Because the RSMeans estimates are organized by
project cost to assist contractors in bid planning, that data set is
the logical choice for this purpose over BLS data, which provides wage
data but does not provide comparable costs for projects. Dividing
project labor value by the labor share of project value yields an
estimate of total project value.
The absolute level of the RSMeans wage and equipment cost levels do
not directly affect the resultant aggregate compliance costs. While
lower wage rates would lower the baseline costs of the representative
jobs, it does not follow that control costs as a percent of baseline
costs would also be lower. In fact, if lower wage rates are combined
with the same equipment costs, the equipment part of incremental
control costs would be a higher percentage of total baseline costs.
Only the labor share (percentage) of baseline costs, along with the
incremental compliance costs as a percent of baseline costs, are taken
from the analysis of representative costs and used in the subsequent
estimation of aggregate costs. The absolute levels of the wage rates
and equipment costs taken from RSMeans do not directly enter the
aggregate cost analysis.
Second, OSHA notes that the BLS wage data, on which the aggregate
compliance costs are based, are obtained from a statistically valid,
national survey of employment and compensation levels and are the best
available data characterizing national averages of wages by detailed
occupation. For some of the reasons the commenter noted, OSHA believes
that the BLS wage estimate provides a more accurate reflection of
average wages.
Another set of SBREFA commenters criticized OSHA's cost estimation
methodology, arguing that fundamental errors resulted in serious
underestimates of the costs of engineering controls. The commenters
asserted without any significant explanation that the task-by-task
incremental cost estimates (shown in Table V-23 of the PIRFA, Document
ID 1720, p. 749) should have been multiplied by two factors: (1) "The
ratio of the RSMeans labor rate to the BLS wage and benefits rate,"
and (2) the inverse of the "percentage in key occupations working on
task" from Table V-26 (also in the PIRFA, Document ID 1720, p. 766).
Under this approach, the commenters argued that "the cost of PEL
controls for brickmasons, blockmasons, cement masons and concrete
finishers performing grinding and tuckpointing would be approximately
seventy-two (72.0) times the ERG estimate, and...the cost of PEL
controls for drywall finishing (at the 50 [mu]g/m\3\ PEL) would be
approximately 7.2 times the ERG estimate" (Document ID 0004).
The rationalization for these calculations was not provided, and
OSHA found these conclusions without merit. The incremental control
costs shown in Table V-34 of the FEA were based on RSMeans estimates
for labor and equipment costs. As shown in Table V-34, these cost
estimates, after adjustments for productivity impacts, are used to
calculate the percentage increase in baseline costs associated with
each control. The RSMeans-based cost estimates shown in Table V-34 are
also used to estimate the share of total baseline task/project costs
accounted for by labor requirements. The averages of the percentage
increase due to incremental control costs and the labor share
(percentage) of total baseline costs are shown in Table V-37 of the
FEA. These two percentages are used to extrapolate the aggregate
control costs associated with each task. This extrapolation was based
on (1) the full-time-equivalent employment in key and secondary
occupations associated with each task, and (2) the value of the labor
time as measured by the BLS occupational wage statistics, adjusted for
fringe benefits.
OSHA provided similar responses in the PEA and requested comment on
its responses to the SBREFA comments, but received none (see PEA, p. V-
131).
The same set of SBREFA commenters further argued that OSHA's
analysis contained five more "fundamental errors" (Document ID 0004).
First, the commenters asserted that OSHA's calculations understate the
actual cost because they are based on old data (1999 or 2000 data from
RSMeans rather than RSMeans 2003 data). OSHA used the most recent
available data at the time the initial preliminary analysis was
completed and subsequently updated those data for the PEA (and the FEA)
using RSMeans estimates from 2008 (Document ID 1331). However, as noted
previously, the RSMeans estimates do not directly determine the
absolute level of aggregate compliance costs, but rather the labor
share (percentage) of project costs and incremental compliance costs as
a percentage of baseline costs. This aspect of the analysis received no
further comment and has been retained for the FEA.
Second, the commenters asserted that there is no information to
"suggest much less substantiate the premise that the exposure
monitoring data in Tables 3-1 and 3-2 [in the ERG (2007a) report,
Document ID 1709)] (even if they were properly collected and analyzed)
are in any way representative of current workplace exposures across the
country" (Document ID 0004). In response, OSHA points out that the
profiles used to estimate the numbers of workers exposed in excess of
each PEL option were, in fact, based on the extensively documented
technological feasibility analysis with many of the data points in the
exposure profiles being taken from the findings of OSHA inspections
(and based on ERG, 2007a, Document ID 1709). OSHA is tasked with using
the best available evidence to develop the analyses, and the data in
the exposure profile represent the best available evidence on current
workplace exposures to respirable crystalline silica. More importantly,
for estimating the cost of controls, Table 1 in the final rule is
intended to be the default option for protecting workers performing
covered tasks, regardless of actual exposure level. The FEA reflects
this, while recognizing that a sizable minority of workers with
exposures below the PEL have limited their exposures by using such
controls currently.
Third, the commenters claimed that there is "is no information to
suggest much less substantiate the premise that the exposure monitoring
data in Tables 3-1 and 3-2 (even if they were representative of current
workplace exposures) are in any way representative of the non-existent,
theoretical jobs artificially created by the FTE [full-time equivalent]
analysis so as to justify their use as the foundation for Table 4-12"
(Document ID 0004). However, OSHA notes that the representative jobs on
which the cost analysis is based were designed to correspond directly
to the tasks assessed in the technological feasibility analysis.
Furthermore, Table 4-12 in ERG (2007a, Document ID 1709) was derived
directly from Table 3-2 and is independent of the "FTE analysis."
Fourth, the commenters argued that a more logical and appropriate
methodology would assume that all FTEs were exposed above the PEL in
the absence of controls, and the commenter could find "no
justification, and substantial support to the contrary, for an approach
that artificially condenses actual exposures into far more highly
concentrated exposures (by condensing all at-risk task hours into FTEs)
and then [assumes] that, despite the impact of this change, the grab
bag of exposure monitoring described in ERG Tables 3-1, 3-2 and 4-12
represents these FTEs" (Document ID 0004). The commenters asserted
that the effect in ERG (2007a, Document ID 1709) of "first multiplying
total project costs by the FTE percentage (from Table 4-8) and then by
the `Percentage of Workers Requiring Controls' from Table 4-12 (and
then by the average `Total Incremental Costs as % of Baseline Costs' by
job category from Table 4-7) results in an unjustified double
discounting of exposed workers in the incremental cost calculation"
(Document ID 0004).
OSHA disagrees. The Agency notes that ERG (2007a, Document ID 1709)
used the exposure profiles from the industry profile to estimate the
number of full-time equivalent workers that are exposed above the PEL.
In other words, this exposure profile is applicable if all exposed
workers worked full time only at the specified silica-generating tasks.
The actual number exposed above the PEL is represented by the adjusted
FTE numbers (see Table 4-22 in ERG, 2007a, Document ID 1709). The
adjusted FTE estimate takes into account that most workers,
irrespective of occupation, spend some time working on jobs where no
silica contamination is present. The control costs (as opposed to some
program costs) are independent of the number of workers associated with
these worker-days. OSHA noted in the PEA that the thrust of the comment
about "double discounting" was unclear, but the commenters did not
respond with clarification. Nothing is "discounted" in the estimation
of aggregate control costs.
Finally, the SBREFA commenters argued that the "application of the
FTE analysis to the additional equipment costs is based on the wholly
unfounded assumption, contrary to actual experience, that this
additional equipment could be used with perfect efficiency (i.e., never
idle) so that it is only at a particular site during the time the at-
risk tasks are being performed" (Document ID 0004). In response, OSHA
notes that its analysis does in fact assume some efficiency with
respect to the use of additional equipment required for controls.
However, many of the equipment costs are based on monthly equipment
rental rates provided by RSMeans that already embody some degree of
idleness over the course of a year (see ERG, 2007a, Table 4-3, Document
ID 1709). In other cases, daily equipment costs were directly estimated
based on equipment purchase costs, annualization factors, and assumed
operating and maintenance costs.\38\ OSHA did receive further comment
on the issue following the publication of the PEA (Document ID 4217,
pp. 84-88), and, in response, the Agency developed prorated ownership
costs (equivalent to twice the rental rates) for control equipment for
tradespersons performing tasks involving short-term, intermittent
silica work.
---------------------------------------------------------------------------
\38\ These were originally translated to daily costs on the
assumption of full-time usage (240 days per year). However, in
response to this comment, this rate was adjusted downward, assuming
instead that equipment would be used 150 days per year (30 weeks),
on average; OSHA applied this downward adjustment to equipment usage
in the PEA and the effect of this change in equipment usage was to
increase the daily cost of control equipment.
---------------------------------------------------------------------------
Public Comment on Engineering Control Costs in Construction
Having already incorporated comments from small business in the
SBREFA panel process, the Agency produced revised estimates for the PEA
in support of the proposed silica rule. In the PEA, OSHA requested
comments from rulemaking participants on the Agency's preliminary
estimate of control costs in construction. Below are comments
representative of the prominent issues that raised concerns.
The most broad-based critique of the construction cost analysis
came from the Construction Industry Safety Coalition (CISC), and its
consultant Environomics (Document IDs 2319, 2320, and 4217). Several of
their arguments regarding underestimation of costs related to an
undercount of the affected construction population (for example, they
believed OSHA should have accounted for the cost to control silica
exposures for plumbers). OSHA agrees in part that there were some
occupations--plumbers, plumber helpers, electricians, electrician
helpers, roofers, roofer helpers, terrazzo workers and finishers, and
sheet metal workers--that likely have exposure and should be included
in this analysis, as they do perform some activities covered by Table
1. These are discussed in FEA Chapter III, Industry Profile.
Owning Versus Renting Engineering Controls in Construction
OSHA also received comments regarding the availability of control
equipment. In its post-hearing brief, CISC commented:
In the Agency's cost analysis, it has also made the entirely
impractical assumption that controls (e.g., wet methods, LEV) for
the tools that construction workers use in performing tasks that
generate respirable silica need to be available only during the
exact duration while a dusty task is performed. The CISC estimates
costs instead to provide control equipment on an "always
available" basis to workers who engage in dusty tasks. Control
equipment must be available whenever a worker may need to perform an
at-risk task, and not for only the very limited duration when the
at-risk task is actually being performed. Costs for the engineering
controls required to meet the reduced PEL in the proposed rule will
be far higher than OSHA estimates (Document ID 4217, p. 29).
While OSHA agrees that CISC's argument has merit, during hearing
testimony CISC's representative acknowledged that its estimates did not
initially take into account the economic life of a control. This is
reflected in the following conversation between CISC's Stuart Sessions
and OSHA's Robert Stone:
MR. STONE: So returning to the methodology for costing, you
pretty much used our numbers and you used our, presumably, like you
mentioned the dust shroud that has a one-year life and, therefore,
after one year, you take the cost again the second year, is that
right? And the third year, and so on? Okay. I think this is perhaps
a problem with the way you've done your analysis. We used basically
FTEs, full-time equivalents. You're using three percent of the time
let's say for plumbers, as an example, you're applying it to three
crews, all right? At the end of one year, you're having them buy
another dust shroud. And my view...they will have used nine
percent of the economic life of the dust shroud. Now, you can argue
I'd make an adjustment because we estimate 150-[day construction
work-year] use of it, for full-time use. This would suggest, though,
that after one year, you will have used one-sixth of the life of
that dust shroud and an employer is not going to throw it out. It's
still functional. He'll use it for the next five years. He'll use it
for six years. Any views on that?
* * *
MR. SESSIONS: Yes. That's a good point, and I hadn't thought
about that.
MR. STONE: Okay, thank you. A related point is actually the same
issue. It would be operating in maintenance costs. You're--it's
going to be one-sixth of our original estimate, but I don't think
you've made that adjustment.
MR. SESSIONS: Correct. (Document ID 3580, Tr. 1501-1502).
After the hearing discussion, CISC revised its methodology,
noting:
After additional thought and discussion about this issue with
several construction tradespeople, we...concluded that useful
life is a function of both how often the tool and controls are used,
but also how long they sit in the construction worker's truck and
get bounced around going from job site to job site (even when they
are not used), and how often they are taken out of the truck and
returned to the truck (even when they are only set up then taken
down at the job site but not actually used). Thus useful life will
increase if a tool sits idle for some percentage of the time when it
is available, but useful life will not increase to the same
proportional extent as the decrease in usage. We assumed in the
example in workbook Tab # X2B that using the tool and equipment 1/4
as often will double its useful life (Document ID 4217, p 89).
OSHA agrees with this updated methodology and has adopted CISC's
approach--essentially assuming one-half of the usage life over which to
amortize the purchased control equipment--for jobs that typically
involve intermittent short-term exposure. The jobs for which the Agency
assumed a half-life of the control equipment were: (1) Hole drillers
using hand-held or stand-mounted drills--for electricians, plumbers,
carpenters, and their helpers, and for sheet metal workers; and (2)
handheld power saws for carpenters and their helpers. Note that OSHA's
adoption of this updated approach resolves CISC's criticism that OSHA
had not accounted for productivity decreases from controls not being
available when the worker needs to use them for short-term or
intermittent silica jobs.
For all other construction jobs (i.e., those not itemized above
involving intermittent short-term exposure), OSHA did not adopt CISC's
approach but instead (as in the PEA) used the market-derived rental
rate for control equipment without either doubling the rental rate to
take into account "down-time" or requiring purchase of the control
equipment. There are several reasons OSHA retained its PEA approach for
these jobs in the final rule:
In most cases, an employer's own/rent decision for control
equipment will be determined by the own/rent decision for the
construction equipment (including construction tools) to which the
control equipment will be applied. If the employer rents/owns the
construction equipment, the employer will rent/own the control
equipment. The major exception would be if a particular piece of
control equipment could be applied to many types of construction
equipment. An example might be a dust collector. In that situation, the
employer might find it economic to rent the construction equipment and
own the control equipment. But, in that case, the purchased control
equipment will not be sitting idle.
Construction equipment is sufficiently expensive that
employers, as a general matter, will not find it economically efficient
to have it sitting idle. That is why employers so frequently rent
construction equipment. Of course, employers that do only one type of
construction job all year (or those that are sufficiently large that
they work on that particular type of construction job all year) will
find it economic to own the construction equipment--as well as the
control equipment--but then the control equipment will not be sitting
idle.
In light of permit requirements and other job-planning
requirements, in almost all cases, the employer will have advance
knowledge of the details of the construction job (as opposed to,
sometimes, repair work in general industry). This knowledge would
include the construction equipment--and controls--required to perform
the job. In fact, employers will often schedule construction jobs
precisely to avoid having construction equipment sitting idle. In other
words, the typical employer--and certainly the competent employer--
won't come to the job site unprepared, needing to leave the job site to
obtain rental equipment or controls.
The construction sector is a significant component of the
U.S. economy. There is a large, competitive construction equipment/
control rental market in place to serve it. In most places, employers
should be able to obtain needed construction equipment/controls in a
timely manner under terms similar to those estimated here.
For the aforementioned reasons, OSHA believes that the ownership-
versus-rental cost issue, except in the case of construction jobs that
involve intermittent short-term exposure, is somewhat of a red herring.
The difference in amortized cost should be negligible, given that
employers will choose to own or rent based on whichever is the lower-
cost alternative. In fact, because rental costs are typically somewhat
higher than amortized ownership costs, OSHA may have overestimated
compliance costs for those employers who purchase control equipment.
Self-Employed Persons
CISC, and its contractor Environomics, claimed in their comments
that OSHA had omitted the costs of compliance by sole proprietors
(typically self-employed persons) (Document ID 4217, p. 80). The
inclusion of such costs and the circumstances under which they would
arise are discussed in Chapter III of the FEA. In the FEA OSHA has
accounted for costs associated with controlling employee exposures from
sole proprietor activities. The actual self-employment data and the
estimated effect on employer costs are presented at the end of this
section on engineering control costs in construction.
Full Cost vs. Incremental Cost
Prior to the PEA, a participant in the SBREFA process noted that
while OSHA established the total incremental cost for each silica
control method (summarized for the final rule in Table V-35 of the
FEA), the cost estimates were based on the application of a single
control method. The commenter argued that there may be cases where two
or more control methods would have to be applied concurrently to meet
the exposure limits (Document ID 0968, p. 14). In response, OSHA noted
in the PEA that for each task, specified control options correspond to
the control methods described in the technological feasibility analysis
in Chapter IV (of the PEA). These methods reflected the choices laid
out in Table 1 of the proposed rule; they were also presented in Table
V-25 in the PEA along with OSHA's calculation of the weighted average
proportion of project costs attributable to labor and the incremental
control costs as a percentage of baseline project cost.
Throughout the comment period, CISC reiterated its pre-PEA
objections to OSHA's methodology of estimating incremental costs
instead of the "full" compliance costs, which CISC defined as
including the costs for employers to meet their existing duty to comply
with OSHA's old PEL (CISC claims employers of "nearly 60,000 workers"
were not in compliance with OSHA's preceding standard and would have
OSHA attribute the costs of compliance with the preceding standard to
the costs of this rule) (Document ID 4217, p. 33):
In our view, OSHA has made two errors in the approach it has taken:
First, the "full" compliance costs for reducing worker
exposures from their current levels to below the proposed new PEL are
the conceptually correct costs to estimate when assessing economic
feasibility, not the "incremental" costs for reducing exposures to
below the proposed new PEL from a starting point assuming compliance
with the current PEL. In practice, employers will face the full costs,
not the lesser incremental costs, and the economic feasibility
assessment should consider whether employers can afford these full
costs, not the hypothetical and lower incremental costs.
Second, OSHA has made a conceptual error in the Agency's
methodology for estimating compliance costs * * * Insofar as OSHA omits
all costs for [employees with exposures >250 [micro]g/m\3\]--failing to
estimate the costs to reduce their exposures all the way down below 50
[micro]g/m\3\ instead of only to below 250 [micro]g/m\3\--OSHA
estimates costs that fall short of the incremental costs of the
Proposed Standard that the Agency aims to estimate. (Document ID 4217,
pp. 96-97)
Both arguments are now largely moot because in the FEA almost all
of the construction engineering control costs are based on compliance
with Table 1 and encompass all employees engaged in the Table 1 tasks,
regardless of their current level of exposure. OSHA has included the
full incremental--and full total--costs for all employers in
construction who have workers who are performing tasks listed on Table
1, even those workers with exposures currently above 250 [micro]g/m\3\.
CISC's arguments for the construction sector are now only relevant
to the very few tasks not covered by Table 1, such as tunnel boring.
OSHA therefore addresses CISC's arguments in the context of those few
tasks.
The first argument is that employers who are not in compliance with
the preceding PEL of 250 [micro]g/m\3\ will have to incur costs to
achieve that PEL in addition to the costs they will incur to reach the
new PEL of 50 [micro]g/m\3\. As laid out in the PEA, OSHA rejects this
position, as this is inappropriate for estimating economic feasibility
among firms making a good faith effort to comply with the existing
silica rule. Employers who had a legal obligation to comply with OSHA's
preceding PEL but failed to do so are not excused from their previous
obligation by the new rule; nor can the fulfillment of a pre-existing
duty be fairly re-characterized as a new duty resulting from a new
rule. But this issue is not limited to construction, and a more
complete discussion is presented in the general industry engineering
control cost section in the FEA.
The second argument can be dismissed on similar grounds. CISC's
argument appears to assume that employers will incur different costs
for different controls necessary to reduce exposures from above 250
[micro]g/m\3\ down to 250 [micro]g/m\3\, and from 250 [micro]g/m\3\
down to 50 [micro]g/m\3\. In many cases, however, the same controls
needed to bring exposures below 250 [micro]g/m\3\ will also bring
exposures to 50 [micro]g/m\3\ or below, so there would be no cost
associated with the new rule. To the extent that separate controls are
required to reduce exposures down from 250 [micro]g/m\3\ to 50
[micro]g/m\3\, OSHA does account for the costs for those controls.
General Comments on Cost Methodology
James Hardie Building Products commissioned Peter Soyka of Soyka &
Company LLC to perform an evaluation of the PEA. While Mr. Soyka's
comments cover many aspects of the analysis and overlap with those of
other commenters, some were relatively unique.
In one place, Mr. Soyka questions the entire method of analyzing
jobs from the level of workers and their tasks. He expressed concern
about both what he termed the failure to capture the cost to the
establishment, as well as the need for workers to have controls
available (Document ID 2322, Attachment G, p. 165). OSHA did not,
however, ignore other costs for establishments. Elements of these costs
are dealt with at the establishment level for some ancillary provisions
of the standard, and are discussed later in this chapter. The second
element, regarding the availability of controls for certain
occupations, mirrors concerns raised by Environomics and CISC, and has
been dealt with above.
Elsewhere in his comments, Mr. Soyka states that "OSHA should
develop revised unit costs that consider the full array of elements
that affect what a business charges its customers for a unit of time
expended." Such unit costs," he submitted, "would include direct
labor, fringe benefits, overhead, SG&A, and a reasonable allowance for
profit (e.g., the typical cost of capital found in a specific industry
or overall)" (Document ID 2322, Attachment G, p. 182). The approach
put forward in the PEA and in the FEA incorporates fringe labor costs.
OSHA has provided a sensitivity analysis of the effects of including
other cost elements in the sensitivity analysis section of the FEA. As
noted elsewhere, for the FEA the Agency recognizes that the labor
productivity effect of adopting certain controls is accompanied by a
loss of productivity in equipment under certain circumstances; that
additional cost has been incorporated in the FEA. The National
Association of Home Builders (NAHB) faulted the costing of engineering
controls in the PEA on several grounds, including several very similar
to those raised by Mr. Soyka and addressed earlier. NAHB also stated
that OSHA has not considered the "unique nature of construction, in
that sites are not fixed in nature, and that equipment may need to be
moved between several sites in a single day" or the "compliance costs
for cleanup of the jobsites" (Document ID 2296, p. 38). Both are
addressed in the FEA as opportunity costs or housekeeping costs.
Other Aspects of Unit Costs
Following publication of the NPRM, a representative of
petrochemical employers, the American Fuel and Petrochemical
Manufacturers, raised concerns about retrofitting and clean-up costs
that it claimed were improperly omitted from OSHA's analysis of
engineering controls in construction:
OSHA claims "[t]he estimated costs for the proposed silica
standard rule include the additional costs necessary for employers
to achieve full compliance."[ ] Yet it fails to consider the
additional costs of retrofitting existing equipment to comply with
Table 1 in Section 1926.1053 (Table 1). In addition to acquiring new
engineering controls not previously implemented, many employers will
have to modify pre-existing equipment to come into compliance (e.g.,
outfitting the cab of a heavy equipment bulldozer with air
conditioning and positive pressure). Table V-3, found in OSHA's
complete PEA, begins to address these costs by enumerating the
capital and operating costs for the engineering controls required by
Table 1. But it does not account for the ancillary costs of retrofitting
those controls, including the cost of retrofitting the equipment
itself as well as the lost time the facility may absorb in doing so.
OSHA also fails to account for the clean-up costs associated
with the natural by-products from Table 1's required engineering
controls. For example, many of the engineering controls require the
use of wet methods or water delivery systems. [ ] Employers will
incur costs from removing (from the clean-up process itself and lost
time) excess water to prevent ice or mold from developing. Yet these
costs go unaccounted for in the PEA (Document ID 2350, pp. 6-7).
In the FEA, the Agency does not include any specific cost for
retrofitting equipment. The record indicates that almost universally
employers either already have equipment with the required controls
available for use (e.g., wet method for saw), or the equipment allows
for the easy addition of a control (e.g., shroud for HVAC).
Furthermore, most equipment is portable and/or handheld and is
relatively inexpensive with a useful life of two years or less. As a
result, it would simply not make economic sense to retrofit the
equipment when it would be less expensive to replace it. In addition,
most other types of relevant construction equipment--heavier and
drivable--generally have a useful life of ten years or less; control-
ready equipment of this type has been on the market for years and is
typically already in use. Thus, OSHA did not estimate any retrofitting
costs. While some employers might still retain pieces of earth-moving
equipment that do not have a cab that complies with Table 1, equipment
with a cab is the industry standard for both purchase and rental. As
discussed in this chapter in the context of productivity, the
implication is that the market has shifted to heavy equipment with cabs
even in the absence of a silica standard. In addition, in final Table 1
OSHA has reduced the number of tasks that require equipment with
enclosed cabs to just a single task: Heavy equipment and utility
vehicles used to abrade or fracture silica-containing materials or used
during demolition activities involving silica-containing materials. For
the odd piece of old, cab-less heavy equipment which does not conform
to the requirements of Table 1, individual employers have the choice of
renting the required equipment to perform that single task, or simply
using the cab-less equipment only on non-silica tasks (thereby ceding
the one silica-abrading construction task to employers that have more
up-to-date equipment). In short, the requirement to use a cab when
performing Table 1 tasks is not a requirement to retrofit all existing
equipment that might conceivably be used for a Table 1 task.
Regarding the question of clean-up costs, the commenter treats the
issue as if there were no clean-up costs associated with generating
silica currently. As discussed in the Environmental Impact Analysis
(Section XIV of this preamble) and in the discussion of productivity
impacts later in this section, there was substantial comment to the
record indicating that in many, if not most, situations, the controls
associated with reducing silica exposure will lead to a net decrease in
the amount of time required for cleanup after a job. While OSHA is not
attempting to quantify any potential cost savings, the record likewise
does not support attributing additional costs to cleanup.
Specific Industry/Equipment Category Cost Comments
Crushing Machines
William Turley, executive director of the Construction & Demolition
Recycling Association (CDRA), broadly described the impacts he
anticipated for his industry.
Recyclers who crush materials for reentry into the economic
mainstream as aggregate products would appear to have to do all of
the following:
Purchase and install climate-controlled enclosures or
cabs for all crusher operators;
Install crusher baghouses for particulate emission
reduction;
Enclose conveyor belts--a measure unprecedented in our
industry;
Install effectively designed and maintained water
spraying equipment;
Impose full-shift use of respirators for all quality
control hand pickers working on processing lines;
Establish and implement emission testing protocols and
procedures to ensure compliance with the PEL;
Implement medical surveillance programs for all
employees engaged in material crushing activities; and
Achieve a "no visible emissions" standard, which
frankly is both unattainable and utterly unreasonable.
To the best of our knowledge, no recycler in the United States
has a system even resembling the above. The cost of such systems
will unquestionably threaten the economic viability of construction
& demolition debris recyclers across the Country. It must also be
pointed out that the industry has an exceptionally diverse
composition of larger operators with higher economic margins and
small operations with limited capabilities to capitalize the type of
equipment called for in this rulemaking (Document ID 2220, pp. 2-3).
The final silica rule does not require all the above steps. OSHA
expects that crushing machines will be used for construction/demolition
activities, as discussed in detail in the Summary and Explanation of
the standard. As such, OSHA anticipates that employers engaged in the
recycling operation would follow Table 1 and would not need to conduct
exposure monitoring.
For crushing machines, OSHA removed the "no visible emissions"
requirement and the requirement for enclosed cabs, both of which had
been in the proposed Table 1. Employers are now required to use a spray
system and comply with manufacturer instructions. Also, there is no
requirement to enclose conveyor belts or install crusher baghouses.
Instead, employees must use a remote control station or ventilated
booth that provides fresh, climate-controlled air to the operator. For
the FEA, OSHA added the cost of a ventilated booth for the use of
crushing machines in construction/demolition activities. Most crushing
machines are already equipped with movable controls that will allow
operation of the machine from inside the booth, so no additional
equipment modifications will be required for most machines. Crushers
available for purchase or rental are also typically equipped with a
water spray system, so OSHA has not assessed any incremental cost for
sprayers.
Homebuilding--Roofing
The National Roofing Contractors Association (NRCA) objected to
OSHA's preliminary cost estimates for controls used to limit silica
exposure in roofing operations, claiming that OSHA's preliminary
estimate of an average of $550 per year for firms that employ 20
workers or fewer (covering the majority of roofing contractors) had
significantly underestimated the cost of specialized saws that would be
required for roofing equipment. In support of the argument that OSHA
had underestimated costs, NRCA identified costs for retrofitting
portable saws with integrated dust collection systems along with
specialized vacuums equipped with HEPA filters (Document ID 2214 p. 4).
The task of cutting most roofing materials would fall under
"Handheld power saws (any blade diameter)" in Table 1, and the final
version of Table 1 does not allow for the dust collection methods
described, so the majority of costs quoted by NAHB are not relevant.
Instead, the final version of Table 1 requires that the employer use
wet methods. Second, the estimate of $550 a year in costs to very small
employers was an estimated average across all affected establishments
with fewer than 20 employees, not just roofing operations in
homebuilding. Questions of small business impact or economic
feasibility for the roofing industry are dealt with Chapter VI of the
FEA.
The comments submitted by consultant Peter Soyka on behalf of James
Hardie Building Products ("Hardie") presented a table of typical
devices with engineering controls involved in fiber cement cutting and
an un-sourced range of costs for the retail prices of those types of
devices and their controls (Document ID 2322, p. 13).
Hardie's inclusion of a table of retail prices for the purchase of
equipment with controls suggests there may have been a misunderstanding
of the nature of OSHA's cost methodology--it is not based on purchasing
entirely new pieces of equipment, but making sure the equipment has the
controls necessary to comply with Table 1. To the extent commenters
submitted estimates addressing the latter question, OSHA has taken them
into consideration in its final estimates.
Asphalt Milling
Fann Contracting, Inc. acknowledged that the availability of
equipment with built-in controls is rising. However, the commenter
suggested that OSHA's preliminary assessment of the design
specifications and costs for the engineering controls identified in
Table 1 of the proposed rule had under-counted the amount of milling
machines and other paving-related equipment that the commenter believed
would still require additional retrofits to enclosed cabs (sealing
cracks, adding air conditioning, upgrading to HEPA filters, etc.) to
satisfy the requirements in Table 1 (Document ID 2116, pp. 6-7).
Table 1 in the final rule does not require a cab for milling
machines or any of the equipment identified by the commenter for paving
purposes, so the commenter's concerns are not relevant. Table 1 only
requires cabs for "(xvii) Heavy equipment and utility vehicles used to
abrade or fracture silica-containing materials (e.g., hoe-ramming, rock
ripping) or used during demolition activities involving silica-
containing materials," and specifies it as an option for "(ix)
Vehicle-mounted drilling rigs for rock and concrete." Table 1 requires
employers to use wet methods to control dust emissions from milling
machines. These costs have been accounted for in the cost analysis.
Drywall Finishing
A SBREFA commenter raised questions about the availability of
silica-free joint compound for drywall finishing (Document ID 0004). In
the PEA, OSHA relied on NIOSH studies showing that silica-free joint
compounds had become readily available in recent years (see ERG, 2007a,
Section 3.2) (Document ID 1709). The cost model for the PEA assumed
that 20 percent of drywall finishing jobs would continue to use
conventional joint compound. Based on additional information, OSHA has
determined that all commercially available joint compounds have no, or
very low amounts of, silica and do not pose a risk to workers from
respirable crystalline silica (Document ID 2296, pp. 32, 36; 1335, p.
iii) and has therefore not included drywall finishing in Table 1 or
taken any costs for this task (see Section XV. Summary and Explanation
of the Standards, Specified Exposure Control Methods for more
information).
Number of Days Controls Are Used Annually
Whether equipment, and the relevant controls, are rented or
purchased, the effective annual cost of the equipment is based on the
assumed number of days per year that it would be used. In the PEA, OSHA
had estimated rental of the equipment for 150 days during each 365-day
period. Based on comments received from industry representatives during
the 2003 SBAR Panel process (Docket ID 0968), this estimate had been
reduced from an average of 250 days in the Preliminary Initial
Regulatory Flexibility Analysis (PIRFA). This reduced workday estimate
presumably reflected winter weather slowdown in many parts of the
country, as well as general weather conditions (such as rain) that can
interfere with many construction processes, and resulted in \2/3\
higher daily rental rates for control equipment.
However, Environomics, in developing its own cost estimates,
assumed that control equipment would be used for 250 days a year,
without an articulated rationale for departing from the estimate
provided during the SBAR Panel process (Document ID 4023, Attachment 2,
X2B-Hole Drilling Unit Costs, Cell P:Q44). More importantly,
Environomics selectively and inconsistently applied 250 days only to
the frequency of usage but not to the daily rate (which OSHA had based
on 150 days of usage). To see why it is a problem to apply a different
number of days to the same daily rate, consider a piece of control
equipment, with a one-year life, known to cost $1,500. Using a 150-day
construction work-year, OSHA would estimate a daily rate for the
control equipment of $10 ($1,500/150 days in the construction work-
year). The annual cost for that control would be $1,500 ($10 multiplied
by 150 days). Using the same example, Environomics would keep OSHA's
daily rate of $10 (amortized over 150 days) but apply it to a 250-day
calendar to arrive at an annual cost of $2,500--where the one-year cost
of the equipment was known to be $1,500. In short, the selective 250-
day methodology Environomics used results in an overestimation of costs
by 67 percent.
Accordingly, OSHA has decided to retain the 150-day construction
work year based on the best available evidence, and the Agency has
consistently applied that work-year throughout the cost analysis
developed in the FEA for construction. (General industry and maritime
work is typically less affected by weather, so a separate work-year
number of days is used for those calculations).
Unit Control Costs
In developing the cost estimates in the FEA, OSHA defined silica
dust control measures for each representative job (see ERG (2007a,
Document ID 1709). Generally, these controls involve either a water-
spray approach (wet method) or a dust collection system to capture and
suppress the release of respirable silica dust. Wet-method controls
require a water source (e.g., tank) and hoses. The size of the tank
varies with the nature of the job and ranges from a portable water tank
(unspecified capacity) costing $15.50 a day to a 10,000 gallon water
tank with an engine-driven discharge, costing $168.38 a day.\39\
Depending on the type of tool being used, dust collection methods
entail vacuum equipment, including a vacuum unit and hoses, and either
a dust shroud or an extractor. The capacity of the vacuum depends on
the type and size of tool being used. Some equipment, such as concrete
floor grinders, comes equipped with a dust collection system and a port
for a vacuum hose. The estimates of control costs for those jobs using
dust collection methods also include the cost for HEPA filters.
---------------------------------------------------------------------------
\39\ See Chapter X in the FEA for a discussion on the
environmental impacts resulting from the use of wet methods for
controlling exposure to silica.
---------------------------------------------------------------------------
The unit costs for most control equipment are based on price
information collected from manufacturers and vendors. In some cases,
control equipment costs were based on data from RSMeans (2008) on
equipment rental charges (Document ID 1331). Table V-32 of the FEA
shows the general unit control equipment costs and the assumptions that
OSHA used to estimate the costs for specific types of jobs.
For each job identified as needing engineering controls, OSHA
estimated the annual cost of the appropriate controls and translated
this cost to a daily charge, based on an assumed use of 150 days per
year (30 weeks), as explained earlier. The only exceptions were
engineering controls expected to be used for short-term, intermittent
work. For these controls, consistent with the CISC methodology that OSHA
adopted, carpenters and other occupational groups were estimated to purchase
this control equipment, and for costing purposes, OSHA amortized the
equipment over its "half-life"--that is, over 75 days rather than 150
days (effectively doubling the daily capital costs of the equipment).
Accordingly, Table V-32 of the FEA shows separate daily cost estimates,
for regular and for infrequent use, for a dust extraction kit and for a
10-15 gallon vacuum with a HEPA filter.
Incremental Labor Costs and Productivity Impacts in Construction
In addition to incremental equipment costs, OSHA estimated in the
PEA the incremental labor costs generated by implementing silica dust
controls. These labor costs were generated by: (1) The extra time
needed for workers to set up the control equipment; (2) potential
reductions in productivity stemming from use of the controls; (3)
additional time to service vacuum dust control equipment; and (4)
additional housekeeping time associated with or generated by the need
to reduce exposures. All additional labor costs related to the use of
controls were subsumed into a single additional labor productivity
impact estimate for each of the representative job categories. Except
where otherwise noted, the productivity impact described is negative,
meaning that the addition of the control is expected to reduce
productivity. To develop estimates of the labor productivity impacts of
the dust control equipment that would be required as a result of the
proposed standard, ERG interviewed equipment dealers, construction
contractors, industry safety personnel, and researchers working on
construction health topics.
In part, because most silica dust controls are not yet the norm in
construction, knowledge about the impact of dust controls on
productivity was uneven and quite limited. More precisely, few
individuals that ERG interviewed were in any position to compare
productivity with and without controls and the literature on this topic
appears deficient in this regard. Overall, telephone contacts produced
a variety of opinions on labor productivity effects, but very few
quantitative estimates. Of all the sources contacted, equipment rental
agencies and construction firms estimated the largest (negative)
productivity impacts. Some equipment vendors suggested that there are
positive productivity effects from control equipment due to improved
worker comfort (from the reduction in dust levels). Others suggested
that the use of dust collection equipment reduces or eliminates the
need to clean up dust after job completion. Comments to the record,
discussed below, closely mirrored this preliminary information.
The estimation of labor productivity effects is also complicated by
the job- and site-specific factors that influence silica dust exposures
and requirements for silica dust control. Potential exposures vary
widely with hard-to-predict characteristics of some specific work tasks
(e.g., characteristics of materials being drilled), environmental
factors (e.g., wet or dry conditions, soil conditions, wind
conditions), work locations (e.g., varying dust control and dust
cleanup requirements for inside or outside jobs), and other factors.
Generalizations about productivity impacts, therefore, are hampered by
the range of silica dust control requirements and work circumstances.
After considering the existing evidence OSHA concluded that labor
productivity impacts are often likely to occur and accounted for them
in the PEA analysis. In the PEA, depending on the general likelihood of
productivity impacts for each activity, OSHA used a productivity impact
ranging from zero to negative five percent of output. After considering
the many comments advocating for both increasing and decreasing the
productivity impact estimates, OSHA has concluded that the estimates in
the PEA were approximately correct and has retained the PEA estimates
for the FEA. The comments and factors influencing each selection are
described in the following discussion.
SBREFA Panel Comments on Productivity Impacts
In response to the SBREFA Panel, the Reform OSHA Coalition
commented on the estimates of the impact of exposure control equipment
on productivity during construction operations. This SBREFA commenter
noted that the estimates of the productivity impact of using additional
control measures were based on interviews with dealers, contractors,
and researchers working on construction health topics and expressed its
opinion that it was not clear how this "purely qualitative analysis
[was translated] into productivity [impact] rates.... " (Document
ID 0968, p. 14). The commenter indicated that engineering control
compliance costs would be sensitive to the ultimate choice of
productivity impact measures (Id.).
OSHA responded to these comments in the PEA as part of the
discussion of the basis for OSHA's productivity estimates. OSHA
summarizes the responses to SBREFA comments here for the convenience of
the reader. As described in the PEA, ERG's research revealed little
substantive, quantitative evidence about the magnitude of the
productivity impacts of the controls, and in some cases, the direction
of the impacts (positive or negative) appeared to depend on the
specific nature of the job. OSHA's estimates in the preliminary
analysis reflected ERG's best professional judgment about the likely
magnitude of these impacts. Some of the estimates may be conservative
because under some scenarios for certain tasks the productivity impacts
could be significantly smaller than those shown in Table V-23 of the
PEA. In some scenarios the productivity impact may even be positive.
The same commenter also expressed a concern that even though
"silica is not now considered a hazardous waste," OSHA had not
analyzed the impact of the proposed rule on disposal of "[silica-
]contaminated" wastes such as "filters of dust control vacuums and
contaminated water discharge" (Document ID 0968, p. 28). The commenter
asserted that disposal issues are "acute on the construction site
where a means to readily dispose of such material or water is not
available" (Id.). The comment was somewhat puzzling because the
comment was premised on the fact that there is not currently any
"hazardous" classification for such waste that would trigger special
disposal duties, and the commenter did not explain why any additional
costs would be incurred beyond normal disposal practices. OSHA did not
identify any new areas of cost in its Environmental Impacts analysis
presented in the FEA, and finds no evidence that employers will be
required to incur additional environmental costs as a result of this
rule, other than some potential permit-modification notification costs
addressed in the discussion of engineering control costs for general
industry in the FEA. The incremental disposal costs resulting from dust
collected in vacuums, discarded filters, and other sources in
construction are therefore likely to be de minimis. An analysis of wet
methods for dust controls suggests that in most cases the amount of
slurry discharge is not sufficient to cause a runoff to storm drains
or surface water.\40\
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\40\ For a more detailed discussion of this issue, see Chapter X
of the FEA.
---------------------------------------------------------------------------
Public Comment on Productivity Impacts in Construction
OSHA invited comment on the productivity impacts--positive and
negative--resulting from the introduction of controls to limit exposure
to silica. In the discussion below, OSHA reviews comments supporting
both negative productivity impacts and positive productivity impacts.
The comments supporting negative productivity impacts include
assertions that OSHA underestimated the negative productivity impact of
complying with the silica rule, failed to include a productivity impact
on equipment, and failed to include a fixed productivity impact. OSHA
considered those comments before concluding that it will generally
retain the approach it used in the PEA, with the exception of
selectively adding additional costs for productivity impacts on
equipment in response to a point raised by CISC. OSHA will also explain
separately why it is not calculating any productivity impact for two
specific activities: (1) Use of cabs for earthmoving equipment, and (2)
drywall installation.
Public Comments Suggesting That OSHA Underestimated the Productivity
Impacts Associated With Engineering Controls
The Interlocking Concrete Pavement Institute reported that
"converting from in-place paver cutting to wet cutting and/or vacuum
systems could induce a 50 percent productivity penalty," but did not
otherwise substantiate that claim beyond noting that it was a survey
response from one of its members (Document ID 2246, Attachment 1, p.
3).
Mr. Soyka, in the comments prepared for Hardie, critiqued OSHA's
estimates of the productivity impact on construction operations as
"far too small" and urged OSHA to adjust productivity-loss estimates
based on empirical data "if available" (Document ID 2322, Appendix G,
pp. 14-15 and 21-22). However, the commenter did not clearly identify
any such empirical data in the comments. The only labor-based
engineering control cost alternative offered by the commenter that
resembled "empirical data" is the addition of a seven-hour penalty
per job that was "based on a JHI time-motion study" apparently
conducted exclusively in a single industry (new home construction) and
comprised of data from just the JHI study (Document ID 2322, Appendix
G, Attachment A, p. A-8). OSHA could not determine whether it would
actually supply new "empirical evidence" that would warrant a change
from the preliminary estimate because the study was not submitted into
the record. The commenter cites "James Hardie Building Products, Inc.,
undated, pg. 15," which appears to align with an entry in the list of
references to an undated "James Hardie Labor Efficiency Manual," but
that manual was not submitted into the record.
Mr. Soyka recommended that OSHA use time-motion studies to derive
the estimated productivity impacts.
[...F]ew [of the productivity penalties estimated by OSHA]
are supported by actual data (e.g., time-motion studies). OSHA
should apply a more conservative approach that considers how work
flow and task completion are likely to be affected by newly required
changes to existing practices as well as entirely new activities
(Document ID 2322, Appendix G).
In addition, Mr. Soyka developed an alternative cost model that
included additional productivity impacts that OSHA did not include. In
this model Mr. Soyka "assumed that wherever possible, company owners
in the residential construction industry will outsource their
compliance obligations to specific subcontractors...providing the
products and services that might generate significant amounts of silica
dust" (Document ID 2322, Appendix G, p. 26). In this scenario, Mr.
Soyka determined that the employer would require "the subcontractor to
relocate its work location outside the house(s) being constructed to a
distance sufficient to ensure that silica dust concentrations remained
minimal inside and around the house(s)" and that "relocating the
materials and work giving rise to silica dust generation [. . .] would
add substantially to the time required to complete the associated
tasks" (Document ID 2322, Appendix G, p. 30). He accounted for this
additional time by increasing the productivity impact on the specialty
subcontractors to seven hours per job, "based upon time-motion studies
conducted by James Hardie (James Hardie Building Products, Inc.,
undated, pg. 15)" (Document ID 2322, Appendix G, p. 31).
Mr. Soyka's model also included a productivity impact for "wearing
respirators to account for fatigue and adverse impacts on employee-to-
employee communication" (Document ID 2322, Appendix G, p. 32).
OSHA fundamentally disagrees with the Mr. Soyka's assumptions. Mr.
Soyka's assumption that all silica-generating tasks need to be removed
from the homebuilding site results from a misunderstanding of OSHA's
statement that "[i]n response to the proposed rule, many employers are
likely to assign work so that fewer construction workers perform tasks
involving silica exposure; correspondingly, construction work involving
silica exposure will tend to become a full-time job for some
construction workers" (FR, 2013, at 56357) (Document ID 2322, Appendix
G, p. 25). OSHA did not mean that silica-generating tasks will be
subcontracted out and that subcontractors will be forced to perform
these tasks off-site. Rather, the Agency was acknowledging that
construction employers would likely consolidate the responsibilities
for performing silica-generating tasks to as few workers as possible in
order to limit exposures to peripheral workers.
As mentioned previously, the "time-motion studies" performed by
James Hardie, compiled in an unpublished reference, were not provided
for public inspection. Moreover, the description of how those data were
used in developing the model suggests that Mr. Soyka's relevant
assumptions are not based on time-motion studies of how long it
actually takes to perform specific tasks with controls added. Rather,
it appears that Mr. Soyka assumed inflated times to perform the tasks,
based on a misunderstanding of what the proposed rule required; in any
case, it is not descriptive of the requirements for the final rule. Mr.
Soyka's suggested approach contrasts with the estimates provided by
CISC/Environomics, which accepted the limitations of the analytical
exercise and agreed with most of the estimates in the PEA regarding the
"variable" productivity effect.
Moreover, it should be noted that aside from weighing the possible
competing forces on productivity in the course of a shift (e.g., more
time for set up vs. less time required for clean-up), there is also a
short-run/long-run phenomenon over a longer period as the standard
comes into use. There may be a short learning curve until workers
determine the most efficient way to perform a job when controls are
introduced (Document ID 3581, p. 1700); in some cases the effect may be
relatively larger until the method of performing a job is
reconceptualized. Mr. Sokya criticizes OSHA for not recognizing "the
dynamic nature of construction" (Document ID 2322, Appendix G, p. 19),
but one obvious aspect of the dynamic nature of construction is that
employers will be constantly adapting to changing circumstances and
trying to find ways to perform the job in the most cost-effective manner.
In short, the Agency believes that a time-motion study of a particular
task is neither necessary to determine approximately what the effect
will be in the short-run, nor would it allow OSHA to determine what
the long-run cost of integrating the controls will be.
CISC and its consultant Environomics, as well as some other
commenters, questioned OSHA's productivity-loss estimates associated
with the required controls. CISC/Environomics claimed that overall OSHA
"underestimated productivity losses associated with performing tasks
using the prescribed controls by an amount roughly equal to the average
equipment intensity of about 42 percent" (Document ID 2320, p. 29).
CISC/Environomics reported that this underestimation came largely from
OSHA failing to account for what they termed "fixed productivity
impacts" and for productivity impacts to equipment. Both of these
concerns are discussed below.
In its post-hearing brief, CISC/Environomics presented the results
from a questionnaire and interviews conducted with employers and
knowledgeable tradespeople; the results included a finding that "the
variable penalty percentages [. . .] were the same as or slightly
larger than those that OSHA had estimated" (Document ID 4217, p. 92).
CISC/Environomics did not submit the questionnaire or the answers
received, nor the details of the interviews, to the record so OSHA
could not fully evaluate the findings or compare them to its own
findings. Based on the available summary information it appears that,
while CISC and OSHA's estimates for variable productivity costs were
nearly identical, it is not clear that CISC's estimates took current
compliance into account. CISC stated that its members felt that
"something greater than zero variable productivity penalty should be
estimated for masons using portable saws controlled with wet methods [.
. .] and for heavy equipment operations using enclosed cabs and HEPA
filters" (Document ID 4217, pp. 92-93). OSHA acknowledges that there
would be a productivity impact to comply with the requirements of the
silica rule relative to using no controls for those activities.
However, as shown in Chapter III of the FEA, Industry Profile, OSHA has
found high levels of baseline compliance with the provisions of the
rule for those activities. As is standard in OSHA's costing
methodology, only costs above and beyond those incurred under current
standards are attributable to the final rule.
In addition, CISC argued that OSHA should take higher productivity
impacts because "in some fraction of these instances [(where controls
would be required)], the controls are hellaciously difficult to use"
(Document ID 3580, Tr. 1321). The testimony goes on to give examples of
such difficulties such as when "building houses where the utilities
are not yet in and the water is not yet in," when working in places
where power is not readily available such as in parking garages or on
scaffolding, and when doing work that requires wet methods outdoors in
extremely cold temperatures (Document ID 3580, Tr. 1321-1322). A
different commenter, the National Utility Contractors Association,
similarly criticized OSHA's estimates for excluding additional water-
transportation costs: "there is not always a water supply available
which would require trucking large volumes of water to the job site
which adds additional costs." (Document ID 3729, p.3)
Given the fact that the majority of the silica-generating equipment
requiring controls under this standard--such as tuckpointing grinders
and concrete drilling equipment--require electricity, OSHA does not
find merit in applying any productivity impact simply because the
controls for those tools may also need electricity. If the employer can
find a way to power the equipment, it can also power the controls when
necessary. Similarly, employers must commonly transport water to
worksites without it for cleanup and sanitation purposes, and OSHA's
technological feasibility analysis explains why the amount of water
required to generate the spray mist is not typically very significant.
Although it seems plausible that wet methods would occasionally be used
outdoors by some employers in weather cold enough to freeze the water
mist used to control the silica dust, this is far from a common
construction occurrence. Moreover, it is not entirely clear from the
record that freezing mist would decrease productivity. OSHA's estimates
of productivity impacts is intended to represent an average across all
situations, and the tiny fraction of time wet methods will need to be
used outdoors in extremely cold weather should not skew the average
productivity impact.
CISC/Environomics stated that there should also be a productivity
impact on equipment rental or use as well as for the additional labor
to operate that equipment longer. Environomics reported that a complete
cost estimate of productivity loss would include not only the
additional labor time required, but also the cost of having to rent
equipment for a longer period of time.
...Simply put, a productivity penalty for labor will
translate to a productivity penalty for equipment. For example, if
due to a labor productivity loss, the labor time required to
complete a job increases from eight hours to eight hours and 15
minutes, the equipment time required for job completion will also
increase to eight hours and 15 minutes. Additional equipment rental
costs will be incurred for the additional 15 minutes, or equipment
owned by the employer will be delayed for use on another job by 15
minutes (Document ID 2320, p. 29).
This concern was reiterated both in its hearing testimony (Document
ID 3580, Tr.1323) and in its post-hearing brief where Environomics
stated that "OSHA's analysis should add an equipment component to the
costs associated with whatever productivity penalty is incurred in
performing a construction task using the Table 1 controls" (Document
ID 4217, p. 91). OSHA agrees, in part, and recognizes that there can be
a productivity impact for equipment (as well as for labor) for many
tasks when there is a cost created by having to extend the rental time
of the equipment.
In the PEA, OSHA had estimated the labor productivity impacts
associated with engineering controls to reduce silica exposure. For the
FEA, the Agency has added a parallel cost for the equipment portion of
the cost for a number of equipment categories. These are itemized in
Table V-34 of the FEA. For example, for Task 15 (Demolition of concrete
slabs, mesh-reinforcing, up to 3"deep), there is estimated to be a 2
percent labor increase related to maintaining wet methods for dust
suppression. In the original Means estimates, it was estimated that
approximately 70 percent of the costs of the task were labor-related,
divided between an operator and a laborer. This 2 percent additional
cost is estimated to amount to $9.39 in added labor cost for an
equipment operator and $7.84 for a laborer, or a total labor
productivity cost per job of $17.23. For the FEA, OSHA is adding an
additional cost item of $7.58 to reflect an opportunity cost, in the
form of a prospective extended equipment rental cost, raising the total
incremental estimated cost to $24.81 per task. As with the other
construction engineering control costs, this additional cost item is
task-specific.
While OSHA judged that equipment productivity can be impacted
negatively by the new rule for many tasks, there are two general
categories for which the Agency determined that there would be
no impact on equipment productivity. The first broad category is short-
term, intermittent work in which the equipment and control are often
idle. An example would be a plumber drilling holes in concrete. The
equipment and control are sufficiently inexpensive (relatively
speaking) that the construction employer or trade contractor (or
possibly even the tradesperson) would typically own rather than rent
the equipment and control. As discussed elsewhere in the FEA, OSHA
determined that certain tradespersons, such as plumbers, electricians,
and their helpers, are more likely to purchase their equipment, rather
than renting it. OSHA estimated the cost of purchasing control
equipment at twice the rental cost.
The second category of tasks for which the Agency did not assess
any equipment productivity impact is the group of tasks in which there
is not a fixed ratio of labor to capital (capital in this case
including rental costs). For example, as explained in the following
unit cost discussion, Task 10 (as detailed in Table V-34 of the FEA)
involves performing earthmoving as a heavy equipment operation task. In
this case, while extra time by a laborer would be required to tend to
the application of wet methods, such application would be done
simultaneously with actually performing the earth-moving task. Thus,
while wet methods for Task 10 would require an added labor cost
(itemized as a "productivity" cost), it would not actually slow down
the operation so as to require the longer period of use of the
equipment that would impose an equipment impact.
CISC/Environomics also argued that part of the productivity effect
was fixed and would therefore need to be accounted for separately. This
fixed component, CISC/Environomics reported, would be "typically
involving activities such as initial set-up and final take-down and
clean-up of the control equipment, [which] often occur at the beginning
and end of a job or work shift" (Document ID 4217, p. 90, see also
2320, p. 28; 3580, Tr. 1320). This would mean that shorter jobs would
have a relatively larger percentage loss in productivity.
Other commenters did not agree that there would be costs related to
set up. During the hearings, Deven Johnson, of the Operative
Plasterers' and Cement Masons' International Association, testified
that the concrete grinding "tools that are on the market today come
integral with the capture device[. . .] The hose is attached to the
grinder already. The electrical cord is attached to the motor already.
[. . .] You simply plug it in and start using it [. . .] there's no
setup time" and that for "a walk-behind concrete diamond-bladed saw
for cutting slabs, the setup time is, make sure there's gas in it and .
. . hook a water hose up to it and turn the water on" (Document ID
3581, Tr. p. 1699). During the hearing, Manafort Brothers described a
wheel-based machine used to suppress dust during demolition operations,
which was simply wheeled onto the worksite and hooked up to a water
supply and electrical source (Document ID 3583, Tr. 2430), and the
Building Trades Construction Department (BCTD) of the AFL-CIO submitted
an extensive list of available tools that included the controls
required by the rule that would require little or no set up (Document
ID 4073, Attachment 4a).
Based on the evidence in the record, OSHA determined that any time
needed to set up the engineering controls required by this rule is
adequately accounted for in the productivity impacts the Agency has
included, particularly in light of the fact that OSHA is not making any
adjustment to account for productivity improvements that are likely to
result from this rule (see the discussion of comments identifying
productivity improvements later in this section). Environomics'
inclusion of both a "fixed" productivity impact as well as a
"variable" productivity impact, without recognizing offsetting
productivity benefits identified by other commenters', results ins a
significant overestimate of the productivity impact.
Public Comments Suggesting That OSHA had Overestimated the Productivity
Impacts Associated With Engineering Controls
BCTD strongly disagreed with CISC's estimates about productivity
decreases resulting from the rule, stating in their post-hearing brief:
[a]ll that [CISC] offered to support these significant increases [in
the productivity impact] is an explanation of how its approach to
calculating productivity differs from OSHA's and a few examples,
such as:
So in the case of the carpenters with the dust extraction
equipment on the drill and the HEPA vacuum, the carpenter takes a
little bit longer to do his hole-drilling task because he's got to
attach the equipment to the drill. He's got to attach the hose to
the HEPA vacuum. He's got to walk over before he drills and he's got
to turn on the HEPA vacuum. Then after he drills, he's got to turn
off the HEPA vacuum. He's got to periodically empty the HEPA vacuum.
He's got to worry about the vacuum hose from the drill to the vacuum
getting kinked and all that sort of thing. So the job takes a little
bit longer. Tr:1317-18.
CISC offered no evidence that its analytical approach is more
accurate than OSHA's. Moreover, this description of how its
hypothetical carpenter would deploy control technology assumes the
employer would select the most cumbersome and inefficient technique
available, rather than taking advantage of the range of more
suitable and less costly tools that are readily available on the
market. See, e.g., Ex. 4073, Att.7a (ROI: hand-held drill with
integrated dust collection) (Document ID 4223, pp. 55-56).
BCTD also took exception to the fact that "CISC acknowledged that
`there may be a productivity net gain in terms of cleanup from using a
control,' Tr:1319 (Sessions), [but did] not appear to have taken
potential gains into consideration when estimating its lost
productivity cost" (Document ID 4223 pp. 55).
Dr. Ruth Ruttenberg highlighted the various areas where the PEA may
have overestimated the negative productivity effect of engineering
controls in construction. She stated that the assumption of a negative
impact on productivity
...is yet another example of OSHA erring on the side of being
conservative in cost estimates. Despite the fact that some who were
interviewed suggested there could be a positive impact on
productivity, OSHA's PEA assessed anywhere from 0 percent to a 5
percent penalty in productivity loss as a result of OSHA compliance
with the proposed silica rule. (PEA, p. V-123-124) The impact of an
assumption of lost productivity can be profound, and OSHA
acknowledges this: "...the magnitude of the productivity impacts
can substantially change the estimate of the overall cost increase
associated with controls" (PEA, p. V-131).
Despite the fact that OSHA leaves likely productivity increases
out of its calculations, it does point to opportunities to increase
productivity with dust control. [...]
Limiting dust increases visibility for workers. (PEA, p. V-126)
Vacuum systems speed up drilling because continuous removal of drill
cuttings from the hole, reduce the need for workers to periodically
stop and clean. (PEA, p. V-128) And the list goes on. OSHA's cost
estimates are conservative, and high, when it comes to productivity
impact (Document ID 2256-A4, p. 7).
Productivity Improvements
In addition to comment that the productivity loss due to this rule
would be minimal, OSHA also received considerable comment to the record
that the controls would improve productivity in a number of ways the
Agency had not factored in--for example by reducing clean-up time by
capturing dust at the source, improving worker comfort and morale, and
encouraging innovation.
Productivity Improvements--Reduced Clean-Up Time
Testimony at the public hearings by the International Union of
Bricklayers and Allied Craftworkers on the experience by union members
with engineering controls suggested that use of controls may boost
productivity by reducing the amount of dust that needs to be cleaned up
during a given shift. The following is a hearing dialogue between Chris
Trahan of BCTD, and Sean Barrett of the International Union of
Bricklayers and Allied Craftworkers:
MS. TRAHAN: [. . .] In your experience is there any productivity
gains or benefits that you can describe?
MR. BARRETT: I can. These machines, when running correctly, when
[. . .] the vacs are regulated, the filters are running good. You
can run that machine until 3 o'clock in the afternoon, shut it off,
and go home. [. . .] If [the machine is] not [running correctly],
you constantly got to keep going back and cleaning up what you
already did. You're losing productivity. And over the course of [. .
.] a month you're talking 40 man-hours. You're talking a--paying a
guy for a week. It's--that's not the case at all [if dust controls
are functioning]. You would actually increase productivity by having
the right equipment there and not have people have to keep coming
back or jimmy-rig little things to try to get by. Just do it the way
it was designed, and you'll get a lot farther....(Document ID
3585, Tr. 3055-3057).
Deven Johnson of the Operative Plasterers' and Cement Masons'
International Association elaborated on the potential time savings of
some of the new engineering controls:
One of the other things that collecting the dust from these operations
on the front end does, it saves time on cleanup. Some of the industry
people have said that it's prohibitive to do that because it takes more
time to collect the dust. That's also not true. If you're collecting
the dust as it's generated and it's going into a HEPA-filtered
container, it's not being blown all over the job site, you don't need
anybody else to clean it up (Document ID 3581, Tr. 1594).Walter
Jones of the Laborer's Health and Safety Fund testified that, for some
tasks, reducing or eliminating the need to clean up after a job can
dramatically increase productivity, in this case by one-third:
We had the Bricklayers here a few days ago and they were talking
about their ability to work till 3:00, because they did not have to
clean up. Instead, when they use non-dust controlling or capturing
devices, they would have to stop right after lunch in order to begin
cleaning up. So we're looking at adding a few more hours to the
workday. So to me, in my mind, they're way more productive (Document
ID 3589, Tr. 4246).
Joel Guth, President of iQ Power Tools and a mason contractor,
testified that he had been able to document the savings in clean-up
time.
In certain industries we've been able to measure the time
savings from cleaning up the silica dust [. . .] It saves them one
to two to three hours a day in cleanup time because they don't have
to wash down the house or wash the windows or wash the bushes where
they're inherently dry cutting (Document ID 3585, Tr. 2981).
Scott Schneider, CIH, Director of Occupational Safety and Health.
Laborer's Health and Safety Fund of North America, discussed how
engineering controls contribute to a more productive workplace:
When you control the dust and you don't have--you're not
breathing it into your lungs, but you're also not spraying it all
over the construction site, all over the sidewalk, and you have to
clean it up, there's a lot of other costs involved in not
controlling. So I think we're going to realize those benefits by
implementing the standard (Document ID 3589, Tr. 4277).
Productivity Improvements--Improved Worker Comfort
OSHA also heard a good deal of testimony suggesting that
productivity will be improved through the use of engineering controls
due to improving the working conditions for workers.
Mr. James Schultz of Wisconsin Coalition of Occupational Safety and
Health described the physiological and practical benefits of
introducing or enhancing engineering controls:
I think if you would work in the work environment that was less
dust or hopefully dust free, it would definitely increase the amount
of productivity just because so much of the time you're spending
wiping the dust off your brow because it's falling into your eyes or
something like that. Even if you have the respirator, it still
interferes with your vision and things like that. So a cleaner
environment would definitely be more productive just because [. .
.], you spend less time trying to think about how you can protect
yourself from this hazard, and I know myself, after working in the
place for many years, I've started to have breathing problems and so
if you can eliminate those breathing problems, if you can breathe
freely, you're also going to be much more productive because you're
not going to stop because you have [to] wheeze or go stand outside
to get some fresh air for awhile or those types of things (Document
ID 3586, Tr. 3253-3254).
Deven Johnson, mentioned previously, testified about the human
effect of controlling silica as well:
Another thing is, an individual who is working in an environment
where [. . .] he or she is constantly bombarded with concrete dust
all day long, your productivity drops as you get more and more
miserable as the day goes on. Commonsense would dictate, if you're
not blasting me in the face with dust and sand and silica for eight
hours a day, that I'm going to feel physically better and I'm not
going to be as tired and exhausted and pissed off as I normally
would be at the end of the day. Your productivity goes up[. . .].
(Document ID 3581, Tr. 1594-1595).
Mr. Javier Garcia Hernandez, from National Council for Occupational
Safety and Health/Equality State Policy Center/Laborsafe, testified on
the cognitive factors that affect productivity, and why engineering
controls should aid productivity:
...as a construction worker, I highly believe that we're more
productive when we are protected[....]. We spend less energy
focusing on how to protect ourselves. Just imagine you're working in
a roomful of dust and you're just trying to either close your eyes
or cover your mouth so the less you breathe. So you're constantly
thinking about how to breathe less dust but if you have the
respirator or the wet, the controlled area, whether it is water or
respiratory protection, you're much more productive because our mind
is less occupied in how to protect ourselves and we spend that time
that we would have spent protecting ourselves working (Document ID
3586, Tr. 3248-49).
Todd Ward, a bricklayer, testified that workers have some awareness
of the hazards of dry cutting blocks and that
...when [workers] on the job [are] dry cutting they know--it
affects morale as well when they know [. . .] they have some
safeguards and they're protecting their lungs. So there is an
increased productivity when you have a good morale then on the job
(Document ID 3585, Tr. 3057).
Productivity Improvements--Innovation
OSHA received comments on the fact that OSHA standards often lead
to innovation.
The Laborers' Health and Safety Fund of North America pointed out
that "[j]ust about every OSHA standard has had a look-back that has
shown [that] industry has innovated to meet the new standard" and
continued, saying that "[w]e believe a new OSHA standard with a lower
PEL will spur innovation in the construction industry to meet the
challenge" (Document ID 3589, pp. 4183-4184).
Charles Gordon observed that "reality is that the new technology
will increase productivity faster, so that the actual costs will be
much less than predicted" (Document ID 3855, Tr. 3815).
Conclusions Regarding Productivity Impacts
In summary, while some commenters have asserted that OSHA has
underestimated the productivity penalties of using engineering controls
in construction, other evidence in the record suggests that the
aggregate net productivity effect of implementing engineering controls
could either be neutral, or possibly positive. In the absence of detailed
quantitative data on these various potentially offsetting effects, OSHA
has conservatively chosen to retain its percentage estimates from the
PEA, while adding some additional productivity impacts that will
increase not only labor costs but also equipment costs.
There is one exception: OSHA has removed the productivity impact
that it had included in the PEA for drywall installers. As explained in
the unit cost discussion, the Agency has determined from the record
that there is no economic reason why drywall installers would now use
silica-based drywall installation--the U.S. market has shifted entirely
to a silica-free compound (Document ID 2287, p. 38; 2296, Attachment 1,
p. 30; 1335, pp. 3-4, 7, 10). Therefore, there is no longer a logical
basis for a assigning a productivity loss to workers performing this
task.
Table VII-12 summarizes the labor productivity estimates. As
discussed previously, while empirical quantitative data are quite
limited on productivity, it is possible to gauge the relative
productivity impacts across the principal control options. For example,
OSHA judged that there are no productivity impacts for certain
controls, such as mobile crushing machines. On the other hand, OSHA
found that the controls required for tuckpointers and grinders may
result in additional time being spent setting up and maintaining
controls over the course of a workday. In Table V-34 of the FEA,
productivity impacts, or "lost production time," are shown by task
and are factors in OSHA's estimate of incremental cost per day.
As discussed, OSHA has retained most of its original estimates of
the productivity effects from the PEA. In some cases, however, Table 1,
which forms the basis for the equipment categories listed in Table VII-
12, was changed from the PEA in response to comment. (see Methods of
Compliance in this preamble for further discussion on the changes to
Table 1). In other cases, OSHA received clarification on the manner of
exposure and added elements to Table VII-12, but did not adjust the
productivity impact. For example, OSHA received very specific comments
on tasks involving portable masonry saws used to cut fiber cement
materials (e.g., "Hardie board"), and this is reflected in specific
descriptions in Table 1 and in Table VII-12, but the estimated
productivity impact for "masonry cutting using portable saws" remains
the same. Similarly, the Table 1 task that included "heavy equipment
operations" in the proposed rule has been broken out into two groups:
(1) Heavy equipment operators and ground crew laborers used for
activities such as grading and excavating that will not involve
demolition or other uses that will abrade or fracture silica-containing
materials; and (2) heavy equipment operators and ground crew laborers
involved in demolition or the abrading or fracturing of silica-
containing materials. These two categories are now estimated to have
productivity impacts of two and three percent, respectively.
Productivity Impact Estimates, by Equipment Category
Rock and Concrete Drilling
This equipment category includes the following Table 1 tasks:
Dowel drilling rigs for concrete; and
Vehicle-mounted drilling rigs for rock and concrete
This equipment category covers a range of drilling activities using
truck-mounted and similar drilling equipment, such as quarry drills and
crawler-type drills. Dust control requires the use of either a dust
collection system or wet drilling methods. Studies of the effectiveness
of available dust collection systems have not addressed performance
issues, but ERG judged that their use does not affect drilling
productivity. While workers must service the dust control equipment
during the workday, this activity generally does not affect the rate of
drilling, except perhaps for short-duration jobs. The wet drilling
methods are integrated into drilling equipment and also should not
adversely affect the drilling rate. Thus, OSHA estimates that there
will be no lost production time for these tasks.
Tuckpointers and Grinders
This equipment category includes the following Table 1 tasks:
Handheld grinders for mortar removal (i.e., tuckpointing);
and
Handheld grinders for uses other than mortar removal
According to ERG's search of the literature, grinding tools can be
retrofitted with dust control shrouds that connect to a vacuum system
(Buser, 2001 & 2002, Document ID 0577). Studies on the use of these
controls indicate that extra time is required to install the shroud and
periodically clean, empty, or replace the vacuum drums, filters, or bags.
The estimated time to install the shroud may be as short as five minutes,
although some types of shrouds take longer to install. Once installed,
however, the shroud can be left in place for the work at that location,
so this activity need not take place at the initiation of each grinding
job.
For interior jobs and for exterior work that requires site cleanup
of grinding debris, the additional work time required to use a vacuum
system might be partially offset by savings in the time required to
seal work areas (to prevent dust migration) and to clean the work area
after task completion. Overall, clean-up times will vary depending on
the size of the job site, the quantity of grinding debris, and the
strength and capacity of the vacuum.
Grinding without a dust-control shroud can generate clouds of dust
that might impair a worker's views of the grinding area. Whereas metal
shrouds also block the view of the grinding area, plastic shrouds allow
workers a view of the work area. Some contractors have noted, however,
that use of shrouds does not allow for the precision required for
certain tasks, such as grinding an inside corner (Lattery, 2001,
Document ID 0777).
For exterior jobs where cleanup is not required and where the work
area is not sealed, the use of vacuum equipment is likely to decrease
productivity for the amount of time required for servicing the vacuum
collectors. If, for example, five minutes were required to empty the
vacuums every two hours, production time would decline about 4 percent,
due simply to dumping the accumulated dust.
At some construction sites, vacuums have been used during the
grinding process, but without shrouds. In these cases, one worker
typically holds the vacuum nozzle near the grinding tool, which another
worker operates. Switching to shrouds with a direct vacuum attachment
would eliminate the need for this assistant and is a more productive
operation.
Manufacturers and vendors cited other benefits from using the
shroud-vacuum systems. Because dust does not build up on and clog the
surface of the grinding wheel, the wheels last longer, resulting in an
approximate 40 percent savings on the grinding discs (Eurovac, 2001,
Document ID 0688). Another source contacted by ERG estimated that
shrouds can increase the abrasive life of a grinding wheel by more than
500 percent (Buser, 2001 & 2002, Document ID 0577). In this regard,
workers would spend slightly less time replacing wheels over the life
of the equipment.
OSHA concluded that while the productivity impacts of vacuum
systems can sometimes be partly offset by other factors, net
productivity impacts are likely to remain negative. For exterior work,
productivity is clearly lower when workers use a vacuum system.
Overall, based on ERG's research, OSHA's final cost estimates include a
5 percent impact for lost production time associated with grinding
operations in construction. This productivity impact is identical to
the impact estimated for this activity in the PEA.
For a tuckpointing project, NIOSH researchers examined the use of
vacuum system controls at a large college building complex (Gressel et
al., 1999, Document ID 0718). Workers used a shroud-vacuum system with
an integral impeller and a fabric dust collection bag. This system
required emptying the collection bags about once an hour. The authors
reported some problems caused by blocking and kinking of the hose and
occasional separations of the hose from the tool. Some of these
problems can be attributed to the design of the dust control system and
might be rectified by future design innovations. Overall, the vacuum
control systems appeared to reduce worker output.
Manufacturers and vendors contacted by ERG estimated that
polyurethane shroud-vacuum systems with tuckpointing equipment, similar
to those used with hand-held grinders, actually enhance productivity.
Among the reasons provided for productivity improvements were: (1)
Fewer workers were required; (2) cleanup times were reduced; (3)
workers had improved visibility of the work surface; and (4) blades
last longer (Buser, 2001 & 2002, Document ID 0577; Caperton, 2002,
Document ID 0580; Eurovac, 2001, Document ID 0688; Nash and Williams,
2000, Document ID 0829). These observations on productivity applied to
tuckpointers with 2- to 8-inch diameter wheels. In addition, positive
effects on worker productivity have also been reported for shrouds that
fit on 5-inch and 7- to 8-inch (18-lb) tuckpointers with integrated
dust-collection systems since equipment without integrated dust-
collection systems require that an additional worker be present to
continually vacuum dust away from the work area (Document ID 0577). On
the equipment that can be used with the tuckpointers with 5- to 8-inch
wheels, an impeller inside the tool housing pushes dust down a hose
into a reusable dust-collection bag (Document ID 0577). One vendor
estimated that the operational productivity of these tools is no
different from that of the same tool without dust control capability.
Workers would still be required to periodically empty dust bags,
although other clean-up time might be somewhat reduced (Document ID
0580). Because tuckpointing work is almost exclusively exterior work,
however, clean-up is often not required.
Based on the considerations for hand-held grinding tools discussed
above and the findings from the NIOSH tuckpointing study, OSHA judged
in the PEA that use of a vacuum system during tuckpointing operations
would impose, on average, a 5 percent negative productivity impact.
Based on these findings and because manufacturer optimism about any
positive productivity impacts has not been documented in controlled
studies, OSHA included the same 5 percent negative productivity impact
for tuckpointing tasks in the FEA.
Heavy Equipment Operators and Ground Crew Laborers
This activity includes the following Table 1 tasks:
Heavy equipment and utility vehicles used to abrade or
fracture silica-containing materials (e.g., hoe-ramming, rock ripping)
or used during demolition; and
Heavy equipment and utility vehicles for tasks such as
grading and excavating but not including: Demolishing or abrading or
fracturing silica-containing materials \41\
---------------------------------------------------------------------------
\41\ Heavy equipment operations (grading and excavating) was
referred to as earth moving in the PEA and in comments. The term has
been updated for this analysis and used throughout for the sake of
consistency and to avoid confusion.
---------------------------------------------------------------------------
The control method proscribed in the proposed silica standard was
to enclose and ventilate the operator's cab. The requirement for an
enclosed cab is only retained in the final standard with respect to the
use of heavy equipment used to abrade or fracture silica-containing
materials or used during demolition. Final Table 1 allows employers to
control dust from heavy equipment used for other purposes (e.g.,
grading or excavating) by using wet methods.
Using an enclosed cab on heavy construction equipment will not
require maintenance beyond the general maintenance necessary to
maintain the integrity of the cab enclosure. Therefore, OSHA estimated
in the PEA that no productivity loss will be incurred for this control.
In the case of heavy equipment operations, CISC/Environomics
estimated that there would be a one percent productivity penalty for
enclosed cabs, due to communication issues and the need to unclog HEPA
filters (Document ID 4217, p. 93). For several reasons OSHA is not
persuaded that the factors CISC cites would result in a net
productivity loss for enclosed cabs on heavy equipment.
First, it is not clear that communication issues are being created
by setting some minimal standards for enclosed cabs. Information
supplied in the record indicates that there are alternate means of
communication beyond shouting from the cab to the front-line workers
outside the cab, including hand signals (Document ID 3583, Tr. 2441)
and existing wireless communication systems (Document ID 0805, p. 4;
2262, p. 28). Many of these work environments are noisy, which seems to
make alternate means of communication desirable, if not required.
Second, it appears that it may be more economical and desirable for
workers to operate in a climate-controlled cab and that equipment with
enclosed cabs has become standard in the construction industry. In
fact, OSHA has determined that relevant heavy equipment currently comes
with an enclosed cab as standard equipment (Document ID 3813, 3814,
3815, 3816), and in pricing construction jobs, RS Means included a cab
as a standard equipment (meaning that it was already included in the
equipment cost, not an added engineering control). In any case, the
fact that cabs are standard suggests that potential buyers do not view
the presence of a cab to be undesirable. While Environomics
acknowledged this possibility at the hearings, their judgment remained
that there would be a net productivity loss (without providing
information on how these offsetting considerations were being
incorporated) (Document ID 3580, Tr. 1434-1435). While OSHA is not
persuaded that the evidence in the record supports Environomics
conclusions, their argument is largely moot. Any productivity impact
would result only from the addition of new controls, but enclosed cabs
appear to have become standard on the relevant equipment, meaning that
in most cases employers would not have the option of using open cabs
even if OSHA's new rule was not in effect. Thus, there can be no
productivity impact attributed to the requirement for a cab.
Although OSHA is not including any productivity impact to account
for enclosed cabs, final Table 1 requires water, or other dust
suppressants, during specified heavy equipment operations in order to
protect workers outside the cab and as an alternative method of
protecting operators for activities that do not involve silica abrading
or fracturing. OSHA has therefore, as indicated in Table VII-12, added
a 2 percent productivity impact for heavy equipment tasks involving
grading and excavating, and 3 percent during demolishing, abrading or
fracturing silica-containing materials. OSHA judged that the abrading,
fracturing, and demolition-related tasks tend to be relatively dustier,
and would therefore require relatively more labor to administer.
Hole Drilling Using Handheld or Stand-mounted Drills
This equipment category includes the Table 1 task "handheld and
stand-mounted drills (including impact and rotary hammer drills)."
This category includes workers in the construction industry who use
handheld drills to create clearly defined holes for attachments (e.g.,
anchors, bolts, hangers) or for small openings for utility pass-
throughs in concrete and other silica-containing construction
materials. Workers use common electric drills, pneumatic drills,
handheld core drills, stand-mounted drills, rotary drills, rotary
hammers, percussion hammer drills, or other impact drills to drill
holes. With regard to core drills, only small, handheld core drills
with bits up to a few inches in diameter are included in this category.
This discussion does not address the use of portable and mobile hole
saws used to produce large holes or openings. That equipment is covered
in the discussion of Masonry and Concrete Cutters Using Portable Saws.
Handheld and rig-mounted drills can be equipped with local exhaust
ventilation to effectively capture dust generated when drilling small
diameter holes. Larger core drills, also referred to as core saws, are
more frequently used with water as a coolant to extend the service life
of the drill bit, as well to suppress dust.
One rock-drill manufacturer asserts that use of vacuum systems
speeds drilling by continuously removing the drill cuttings from the
hole, making it unnecessary for workers to periodically stop drilling
to accomplish this task (Atlas-Copco, 2001, Document ID 0542). On the
other hand, the connection and servicing of the vacuum equipment
requires incremental work that could reduce productivity. If the
construction project at hand involves interior work, this impact might
be offset by reductions in the time necessary for cleanup (i.e.,
interior work would require cleanup, while exterior drilling probably
would not). In the PEA, OSHA applied a 2 percent productivity impact
where this task is performed and did not receive comment suggesting
that this estimate was too low, so OSHA retains the same 2%
productivity impact in estimating compliance costs in the FEA.
Jackhammers and Other Powered Handheld Chipping Tools
This equipment category includes the Table 1 task "Jackhammers and
handheld powered chipping tools."
Silica exposures generated during pavement breaking, concrete
demolition, and other concrete work using jack hammers and other
handheld powered chipping tools (including pavement breakers and other
similar tools) are controlled through the use of wet or dry methods.
Regarding wet methods, because the work area generally cannot be
presoaked effectively (i.e., dust is generated once impact drillers
break through the surface), OSHA judged that adequate dust control
requires a constant spray of water to the work area. Thus, dust control
requires that a water sprayer be mounted onto the jackhammer (or that a
mobile sprayer be set up that can move along with the work).
Alternatively, a crew member can use a water hose to spray and wet the
concrete and asphalt surfaces being broken, although the associated
productivity loss could be substantial, and, for that reason, OSHA
believes that construction firms would likely try to avoid that
approach.
However, OSHA judged that the incremental productivity impact from
the spraying activity is modest because various crew members could
occasionally be enlisted to keep the water spray directed in the
correct location. Further, because of the interactive nature of the
various crew member activities, the time to move the water sprayer is
unlikely to affect the overall crew output. In addition, incremental
cleanup costs generally would not be significant since most drilling
projects are performed outside. Nevertheless, to allow for some
incremental work related to supplying water and positioning the spray
when wet methods are used, as was the case in the PEA, for the FEA OSHA
estimated a 3 percent productivity impact for this equipment category
when wet methods are used.
A separate, higher, productivity impact was defined for use of dry
methods for activities where jackhammers and other handheld powered
chipping tools are used. Dry methods are somewhat less flexible and
require a shroud for the close capture of dust as it is generated
during operations. Workers also periodically have to empty
the vacuum bags in which the dust accumulates. Thus, as discussed above
with respect to the use of a shroud for grinding and tuckpointing,
these controls are judged to generally have a greater productivity
impact during operations and, consistent with the PEA, OSHA assigned a
5 percent productivity impact to use of this control method for this
equipment category.
Masonry and Concrete Cutters Using Portable Saws
This equipment category includes the following Table 1 tasks:
Handheld power saws (any blade diameter);
Handheld power saws for cutting fiber-cement board (with
blade diameter of 8 inches or less);
Rig-mounted core saws or drills;
Walk-behind saws; and
Drivable saws
Drivable saws and walk-behind saws have an integrated water tank,
and the sawing is almost always done wet (see FEA Chapter IV,
Technological Feasibility). Wet sawing keeps the blade from
overheating, with the water acting as coolant. Rig-mounted core saws
used to drill larger diameter holes in concrete are typically used with
water as a coolant to extend the service life of the bit, as well as to
suppress dust.
As has been noted, most portable hand-held concrete saws are
designed with wet-sawing capability (see Chapter IV, Technological
Feasibility of the FEA). These saws have a water hookup for a hose
attachment, but might also be used for dry cutting. (Dry-cut diamond
blades for dry cutting are available; these are made especially so that
the tips do not separate during dry cutting.)
A construction equipment distributor judged that there are no
operational productivity advantages for dry cutting, as opposed to wet
cutting (Healy, 2002, Document ID 0726). Wet cutting, however, requires
access to water (water line or pressurized tank), and some time is
needed to connect the equipment (although OSHA received a number of
comments saying that this hook up is very simple and not time
consuming--see "Public comments suggesting that OSHA underestimated
the productivity impacts associated with engineering controls" earlier
in this section for more detail). In addition, the water hose hookup
may be cumbersome and interfere with the work (Healy, 2002, Document ID
0726). For these reasons, as was estimated in the PEA, for the FEA,
OSHA assigned a cost of 2 percent in lost production time for equipment
in this category.
For the final rule, the Agency has clarified in Table 1 that hand-
held circular saws with a blade diameter of eight inches or less
specially designed for cutting fiber cement board can be used outdoors
without respiratory protection, when equipped with a local exhaust
ventilation. The productivity impact for this group is also estimated
at 2 percent because, although it does not have an impact on job
performance, it involves some set-up time and incremental maintenance.
Masonry Cutters Using Stationary Saws
This equipment category includes the Table 1 task "Stationary
masonry saws." Stationary saws for masonry, brick, and tile cutting
come equipped with water systems for wet cutting, which is the
conventional, baseline control method for this type of work. Some
modest incremental time is needed to provide for and connect the water
supply and to maintain the water nozzles and spray system. This
incremental time was the basis for OSHA to estimate a 2 percent cost in
lost production, both in the PEA and in the FEA.
Millers Using Portable or Mobile Machines
This equipment category includes the following Table 1 tasks:
Walk-behind milling machines and floor grinders;
Small drivable milling machine (less than half-lane);
Large drivable milling machines (half-lane and larger with
cuts of any depth on asphalt only and for cuts of four inches in depth
or less on any other substrate)
The activities performed using equipment in this category range
from cold planing and cleaning of asphalt to surface planing or
grinding of concrete. In large-scale projects, such as street
resurfacing, baseline practices are judged to control silica dust
exposures. No additional controls would be needed, and therefore no
negative productivity impacts are expected.
While some grinding machines designed for milling concrete surfaces
have built-in dust collection or wet-method systems, others must be
attached to external vacuum equipment. ERG reviewed the available
literature and found no evidence that the grinding operation is slowed
when such vacuum equipment is attached. Nevertheless, workers must
devote some time to setting up equipment, changing vacuum bags or
barrels, and cleaning filters. On the other hand, using an LEV system
to capture dust as it is generated reduces the time required for
cleaning up the settled dust from the surfaces following completion of
the grinding task. OSHA estimated in the PEA that there would be a 2
percent productivity impact for milling using wet methods and a 5
percent productivity impact when using LEV systems.\42\ These estimates
have been retained for the FEA.
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\42\ For the FEA, milling operations using LEV are accounted for
under grinding operations, as indicated in Table V-24.
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Mobile Crushing Machine Operators and Tenders
This equipment category comprises the Table 1 task "Crushing
machines."
OSHA projected in the PEA that there would be no productivity
impact for this equipment category. The Table 1 requirements for this
machinery have changed in the final rule, but OSHA's conclusion that
there will be no productivity impact remains the same. Final Table 1
requires employers to protect employees through a combination of
sprayers and requiring the operator to operate the machinery from
within a ventilated booth or at a remote control station. Once
installed, the sprayer systems will be part of the crushing machine
operation and will not impact production rates. For the purpose of the
economic analysis of this rule, OSHA has accounted for additional costs
for use of the ventilated booth. Because the booth can be located close
to the machinery, there would not be productivity loss from the
operator having to travel to a different location for operation. In
most cases the booth can be set up quickly once at each location, so in
most cases there will not be any significant productivity loss
associated with the use of the booth.
Baseline and Incremental Unit Control Costs
Table V-34 in the FEA, and presented as Table VII-13 in this
section, summarizes the control method and costs per day for each
representative construction job. These costs include incremental
equipment costs and indirect labor costs due to productivity impacts
(decreases in productivity associated with the use of the control
equipment).
Note that the only silica tasks in Table V-34 of the FEA considered
to have short-term infrequent work where the employee would own the
equipment are Task 11: Hole drilling using hand-held or stand-mounted
drills and Task 18: Masonry cutting using portable saws--II. Note also
that all the indoor tasks in Table V-34 of the FEA have an additional
daily control equipment cost of $1.67 for a fan.
Table V-35 of the FEA summarizes the baseline costs and incremental
control costs from Tables V-30 and V-34, of the FEA, respectively, for
each representative silica-related job in OSHA's silica construction
cost analysis. The control cost (defined as incremental control costs
per day) are shown in Table V-35 of the FEA as a percentage of the
baseline daily job costs. As the incremental control costs were
obtained from Table V-34, they are just the sum of additional labor and
equipment costs associated with the use of silica controls, including
the labor and equipment productivity impacts of the use of the silica
controls.
As is evident from Table V-35 of the FEA, these incremental control
costs can range from 0.3 percent to 7.8 percent of the baseline job
cost. The magnitude of the productivity impacts can substantially
change the estimate of the overall cost increase associated with the
silica dust controls.
Table V-36a of the FEA presents the weighted average of control
costs by task category for outdoor tasks. OSHA defined "weights" for
each job category (column "Relative Frequency Within Categories")
based on the projected relative applicability of the controls and/or
tasks within each category (as determined in the technological
feasibility analysis in Chapter IV of the FEA). These percentages did
not change from the PEA except for the two tasks that have each been
further partitioned into multiple tasks in the final rule: Heavy
construction operators and masonry cutters using portable saws. Heavy
equipment operators are subdivided into tasks that involve fracturing,
abrading, or demolishing silica-containing materials such as masonry or
concrete, that require use of wet methods whenever workers other than
the equipment operator are present, and tasks that involve use of heavy
equipment for earthmoving and excavation of soil, that require wet
methods only as necessary to minimize fugitive dust. Masonry cutters
using portable saws are subdivided into five categories: (1) Handheld
power saws such as cutoff saws; (2) handheld power saws for cutting
fiber-cement board with blade diameters of less than eight inches; (3)
walk-behind saws; (4) drivable saws; and (5) rig-mounted core saws. Wet
methods are specified as a control method for all use of portable saws
except for handheld power saws for cutting fiber-cement board, for
which LEV rather than use of water to suppress dust is required. The
labor cost as a percentage of project costs--which, as subsequently
shown, is a critical factor in calculating the total value of all
silica-generating construction activities--is derived from Table V-30
of the FEA.
Table V-36b of the FEA presents the weighted average of control
costs by task category for tasks indoors or in enclosed areas ("indoor
tasks"). The procedures are identical to those used in Table V-36a of
the FEA, and the only difference is that the total incremental costs as
a percentage of baseline costs are higher due to the addition of the
cost of a fan for indoor tasks.
Once the total value of all silica-generating construction activity
is calculated for each task, as shown in Table V-44 of the FEA, the
incremental costs associated with each task category as a percentage of
baseline costs (from Tables V-36a and V-36b of the FEA) will determine
the costs that the engineering control requirements in the final
construction standard add to the costs of construction activity--that
is, the incremental costs of the resulting reduction in silica
exposure.
Aggregate "Key" and "Secondary" Labor Costs for Representative
Projects
To estimate aggregate labor costs or value for each equipment
category, OSHA first matched OES occupational classifications with the
labor requirements for each equipment category (e.g., hole drillers
using hand-held or stand-mounted drills). These matching occupations
are shown in Table V-37 of the FEA. In order to estimate the percentage
of time during each work day that workers spend on activities using
equipment in the relevant categories, OSHA designated some occupations
as "key" and others as "secondary." The key field in Table V-37 is
set to "1", if a key occupation and to "0" if a secondary one. Even
those employees who are engaged in tasks on Table 1 typically spend
only a portion of their workdays engaged in silica-generating tasks, so
the distinction between "key" and "secondary" is needed in order to
estimate the amount of time workers participate in silica-generating
tasks. In the preliminary and final cost analyses, OSHA applied ERG's
occupation designation, as explained in greater detail below. OSHA
requested comment on the designations of "key" and "secondary"
designations in the PEA, but did not receive any comments challenging
those designations.
"Key" occupations refer to the worker or workers on each crew who
perform the principal silica-generating activity using the equipment in
each equipment category. For each equipment category, ERG estimated the
overall percentage of time that workers in key occupations devote to
the activity.
Other "secondary" crew members (e.g., first-line supervisors/
managers and construction laborers) were estimated in terms of their
ratio to the number of key workers required for given task areas. The
secondary crew ratios range from 0 percent (no one in a secondary
occupation engaged in silica-generating tasks) to 300 percent (three
times the number of secondary occupation workers, in relation to the
number of key workers, exposed to silica-generating tasks). As noted
above, OSHA used these percentages and ratios to estimate (on an annual
basis) the amount of time these employees are using relevant equipment
to engage in work that causes silica exposures. The estimate of the
percentage of time performing the silica-generating activity can be
viewed in terms of the full-time-equivalent (FTE) employees engaged in
work that utilizes equipment in each equipment category. These
estimates and the corresponding ratios for secondary workers are shown
in Table V-37 of the FEA.
For the key occupations, OSHA was able to obtain some data with
which to estimate the proportion of time workers perform activities
using silica-generating equipment. For the secondary occupations, such
estimates were generally not possible. Thus, the participation of
secondary occupations in silica-generating activities was defined based
on their relationship to the key occupations. This participation is
defined by their presence in the job crews, as shown in Table V-30 of
the FEA. To illustrate the need for this approach, consider the
difficulty in predicting how often construction foremen of all types
are present during activities where silica-generating equipment is
used. BLS data, for example, provide only a total number of foremen,
but no information about how they might spend their time. It is
reasonable to forecast, however, using the job-crew definitions, that
foremen will be present in some proportion to the number of workers in
key occupations using jackhammers and other powered handheld chipping
tools, rock and concrete drillers, and other silica-generating
equipment. OSHA presented these data in the PEA and requested comments,
but did not receive any on this aspect of the analysis. Therefore, OSHA
is retaining its estimates from the PEA, except as noted.
For some activities, the crew size and composition vary among the
jobs defined in the equipment category. In those cases, OSHA used ERG
determinations as to the most representative crew composition and used
that crew model to define the ratio of secondary to key occupations
(ERG, 2007a, Document ID 1709).
The estimates of the number of FTE employees engaged in activities
using silica-generating equipment are one of many factors that
influence the final cost estimates. There are few data, however, on the
breakdown of time spent by construction workers in various activities.
The following discussion presents the basis for the time-on-task
estimates for the key occupations as included in the PEA and the FEA
(except where noted). OSHA presented most of these estimates for public
comment in the PEA but did not receive any comments challenging them.
Rock and Concrete Drillers
A review of NIOSH reports covering rock and concrete drillers
showed that over 75 percent of driller time was spent on actual
drilling (NIOSH 1992a, Document ID 0911, NIOSH 1992b, Document ID 0910,
NIOSH 1995, Document ID 0907) and is supported by updated data in
NIOSH, 1999b (Document ID 0220). Therefore, for the PEA and FEA, OSHA
used 75 percent as the best indication of the time spent using dust-
generating equipment for workers in this category.
Tuckpointers and Grinders
Grinding and tuckpointing are only two of the numerous jobs
performed by brickmasons, cement masons, and their helpers. Workers in
those trades are much more frequently performing bricklaying, cement
work, and masonry construction. Where tuckpointers and grinders are
being used, a review of the OSHA Special Emphasis Program reports
revealed that the time spent using tuckpointers and grinders varied
widely (see the technological feasibility analysis for this activity in
Chapter IV of the FEA). In both the PEA and in the FEA, OSHA used ERG's
estimate that 2.5 percent of the time for workers in each of the
applicable occupations would be spent on using this equipment.
Heavy Equipment Operators and Ground Crew Laborers
For the final rule, heavy equipment operators and ground crew
laborers were split into two categories in Table 1 based on how the
heavy equipment and utility vehicles are being used, which reflects
distinctions added in the final rule. This equipment is considered to
either be used a) to abrade or fracture silica-containing materials
(e.g., hoe-ramming, rock ripping) or used during the demolition of
concrete or masonry structures; or b) for tasks such as grading and
excavating but not including: demolition of concrete or masonry
structures or abrading or fracturing silica-containing materials.
ERG estimated that workers using heavy equipment to abrade or
fracture silica-containing materials or for demolition devoted only 2.5
percent of their time, on an FTE-equivalent basis, to doing this work.
Key workers in the companion group using heavy equipment for
grading and excavating often spend the bulk of their work shift on the
equipment itself, engaged in construction work. OSHA Inspection Reports
and other documentation consistently show that heavy equipment
operators perform their tasks for more than 7 hours per shift (OSHA SEP
Inspection Reports 122212079, 116179359; Greenspan, et al., 1995; NIOSH
HETA 93-0696-2395, 1999; NIOSH, 1999b; NIOSH ECTB 233-120, 1999c.).\43\
Nevertheless, the heavy equipment operator occupational category also
includes operators of such equipment as pile drivers, cranes, and air
compressors that are not generally associated with silica dust
generation. For the PEA, OSHA used ERG's estimate of 75 percent for
operating engineers and 50 percent for excavating and loading machine
and dragline operators in this category to estimate the number of heavy
equipment operators performing silica-generating activities. OSHA did
not receive any comment on these estimates and therefore has retained
their substance for the FEA.
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\43\ Document ID 0133, 0192, 0716, 0220, and 0266, respectively.
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Hole Drilling Using Handheld or Stand-Mounted Drills
While many workers might occasionally be assigned to drill holes in
concrete, this equipment category represents a very small part of the
activities of the occupational groups performing this work. ERG judged
that carpenters, electricians, plumbers, sheet metal workers, and
helpers (construction laborers) spend one percent of their time
drilling holes in silica-containing materials in the affected
industries. OSHA presented this estimate in the PEA and did not receive
comment or alternate estimates and has therefore retained the estimate
for the FEA.
Jackhammers and Other Powered Handheld Chipping Tools
OSHA estimated in the PEA that in the key occupation of
construction laborers, relatively few use equipment in this category.
In developing the estimate of time spent using equipment in this
category for the PEA, ERG examined a snapshot of construction
activities from the BLS publication, Injuries to Construction Laborers
(BLS, 1986, Document ID 0559). That source presents a survey of injured
construction workers and includes questions about their activities at
the time they were injured. The survey indicated that 3 percent of
construction workers were using jackhammers at the time they were
injured. ERG judged that, while the survey was not intended to
characterize typical construction activities, and a survey of injured
workers introduces considerable potential bias into the observations,
this estimate was useful as an observation of representative
construction activities. ERG also judged that, because jackhammers are
heavier, more cumbersome, and more powerful than much construction
equipment, workers are probably injured more frequently while using
jackhammers, on average, than when using all other construction
equipment. Thus, the 3 percent figure is likely to be an upper bound of
the amount of time spent using jackhammers and other powered handheld
chipping tools. In the absence of other data, OSHA used ERG's estimate
that 3 percent of laborers are using this equipment for the PEA. The
Agency received no additional data or comment on this estimate and has
therefore retained this estimate for the FEA.
Masonry and Concrete Cutters Using Portable Saws--I
The key occupations using portable saws to cut masonry and
concrete, namely brickmasons, blockmasons, stonemasons, and their
helpers, spend, on average, a small share of their time cutting these
materials with portable saws. In Table 1, OSHA notes three types of
portable saws: (1) Hand-held saws, (2) walk-behind saws, and (3)
drivable saws. Each of those is encompassed in this analysis, although
small-diameter handheld saws are addressed separately. According to
OSHA and NIOSH reports, the workers in these occupations perform
multiple masonry activities and might engage in cutting for only a
small portion of their shift (OSHA SEP Inspection Report 300646510;
NIOSH, 1999a) (Document ID 0084). Another glimpse of this activity can
be gleaned from the BLS injury report for construction laborers, where
3 percent of workers were injured while breaking up or cutting
concrete, asphalt, brick, rocks, etc. For each of the applicable
occupations, OSHA estimated in the PEA that 10 percent of the workers'
time would be spent using the equipment in this category.
The Agency received no comment on this estimate and has therefore
retained this estimate for the FEA. Masonry and Concrete Cutters
Using Portable Saws--II--Small Diameter Saws for Cutting
Fiber-Cement Board
The task of using handheld power saws for cutting fiber-cement
board (with blade diameter of 8 inches or less) was separated out in
Table 1 in the final rule to recognize portable saws used for cutting
cement fiberboard or cement fibersiding as a potential source of
silica-containing dust. OSHA judged that portable saws would be used by
carpenters or their helpers to cut fiber-cement board and that, on
average, they would spend 2.5 percent of their time using equipment in
this category to cut the referenced materials.
Masonry Cutters Using Stationary Saws
As noted earlier, OSHA and NIOSH surveillance publications report
that saw operators perform multiple masonry cutting activities and
might engage in cutting silica-containing materials for only a small
portion of their shift (OSHA SEP Inspection Report 300646510; NIOSH,
1999a). For the PEA, OSHA used ERG's estimate that workers in mason
occupations spend 10 percent of their time cutting silica-containing
materials with stationary saws. The Agency received no comment on this
estimate and has therefore retained this estimate for the FEA.
Millers Using Portable or Mobile Machines
In the PEA, ERG identified two key occupation groups where millers
are using portable or mobile machines: (1) Cement masons and (2)
paving, surfacing, and tamping equipment operators. In response to
comments (see Document ID 3585, Tr. 3036; 4220, p. 9; 3756, Attachment
1), for the FEA, OSHA added a third key occupation group: Terrazzo
workers and finishers. Milling using this equipment represents a small
share of the overall job duties of these applicable key occupations: In
the PEA OSHA judged that 5 percent of all work for the first two
occupation groups is spent using this equipment, and OSHA is retaining
that estimate in the FEA because there were no comments challenging
that estimate. OSHA estimates that terrazzo workers use the equipment
about half as much as the other two occupation groups, so OSHA
estimates that 2.5 percent of all work time spent by terrazzo workers
and finishers will be spent using this equipment.
Rock Crushing Machine Operators and Tenders
According to information collected from ERG communication and OSHA
SEP inspection reports, rock crushing machine operators spend most, if
not all, of their shifts at and around the rock crushing process
(Polhemus, 2000, Document ID 0958; Haney, 2001, Document ID 0721; OSHA
SEP Inspection Report 2116507, Document ID 0186; OSHA SEP Inspection
Report 300441862, Document ID 0030). OSHA estimated in the PEA that
this occupational group spends 75 percent of its time using rock
crushing machines and did not receive any comment on the estimate. OSHA
has retained this estimate for the FEA.
Tunnel Boring
Underground workers perform both tunnel work and other types of
construction work. The majority of these underground tasks still fall
under Table 1 and have been accounted for elsewhere in the appropriate
construction task analysis. However, a small amount of silica-
generating underground construction work outside the scope of Table 1,
primarily in tunnel boring, is expected to occur. The cost of
engineering controls for this activity (to comply with the new PEL) is
presented after the total engineering control costs to comply with
Table 1 are presented.
SBREFA Panel Comments on Key and Secondary Occupations
As stated in the comments during the Silica SBREFA process, one
SBREFA commenter was "unable to reconcile ERG's statement that `the
amount of time...grinders and tuck-pointers perform grinding ranges
widely, from about 1 hour per shift up to a full 8-hour shift (or
longer)' [see the discussion on technological feasibility in Chapter IV
of the FEA] with the 2.5% estimate in Table 4-8 [in the ERG report
(2007a); Table V-26 in the PEA]" (Document ID 0004; 1709). The
commenter also asserted that masonry cutters use stationary saws
approximately 20 to 30 percent of their working time (rather than 10
percent), and that masonry cutters use portable saws approximately 5
percent of their working time (rather than 10 percent) (Document ID
0004).
In response, OSHA reiterated in the PEA that Table V-26 of the PEA
showed the estimates of the full-time-equivalent number of workers in
key and secondary occupations using equipment to perform silica-
generating tasks. These occupations are taken from the BLS Occupational
Employment Survey classification system and are much broader than the
"masonry cutter" category referred to by the commenter, implying a
lower percentage of time devoted to tasks involving masonry cutting.
OSHA did not receive further comment on this explanation.
Therefore, OSHA has not changed these estimates in the FEA. For each
occupation the estimates in Table V-37 of the FEA are meant to reflect
the typical or average amount of a worker's time (over a year) devoted
to the listed tasks.
FTE At-Risk Employment by Task Category
Tables V-38a and V-38b of the FEA provide estimates, by occupation,
of the full-time-equivalent (FTE) number of key and secondary workers,
respectively, for each task category, using the percentages and ratios
from Table V-37 of the FEA. These tables are relatively direct
compilations from previous tables with adjustments needed, in a few
cases, to assure that the industry-specific FTE occupational totals did
not exceed the total occupational employment for any industry.
Table V-39 of the FEA shows the corresponding estimates by NAICS
code for the construction industry.
OSHA distributed FTE at-risk workers across NAICS codes according
to the combination of task categories and occupational (key and
secondary) categories (from BLS, 2012, Document ID 1560) derived and
updated by ERG for each industry group (ERG, 2007a, Document ID 1709).
Overall, a full-time equivalent of 374,003 workers is estimated to
use equipment to perform work on silica-containing materials in
construction, ranging from 1,135 FTEs for rock crushing machine
operators and tenders to 198,585 FTEs for heavy equipment operators and
ground crew laborers (grading and excavating).
Total At-Risk Employment
In the PEA, OSHA used a relatively crude approach to convert the
estimated number of FTE affected construction workers to the number at-
risk construction workers. There, OSHA used a multiplier of 2 or 5,
depending on the industry, to convert the number of FTEs to the number
of at-risk workers (in Table V-37 of the PEA).
OSHA received several comments regarding the analysis used in the
PEA as being too simplistic. Joseph Liss challenged OSHA's methodology:
Even though OSHA estimates the number of workers needing
training for silica exposure under the proposed rule by
multiplying full-time equivalents by a factor of either 2 or 5,
depending upon the sub-industry, the multiplicative factor for
training purposes is likely to be much higher. For example, while
paving, surfacing, and tamping operators spend a total of only 5% of
their time on tasks exposed to silica, as estimated by ERG, it is
not unlikely that many of the 51,857 workers in that industry sub-
group will do silica-exposed work at some point, and, thus, require
training. There are 823,737 construction laborers, and ERG estimated
that 3% of their time is spent on silica-exposed work, but the
severe turnover in that industry means firms may need to train many
of those workers in silica safety procedures and health effects.
OSHA estimates the nation's 575,000 residential construction workers
spend 5% of their time on construction work and uses a
multiplicative factor of two, thus assuming that only 10% of those
workers require training and exposure monitoring. Costs may increase
if the number of workers exposed increases, since OSHA requires
training for all newly hired workers as well as all initial training
for all workers exposed to silica (citations omitted) (Document ID
1950, p. 9).
Additionally, the Construction Industry Safety Coalition (CISC)
submitted calculations to arrive at their own results of at-risk
workers. They note:
These percentages represent our quick judgement across both the
key occupations and the secondary occupations that OSHA identifies
as participating in the crew when the at-risk task is performed. If
we had more time, we would like to make this judgement more
carefully (Document ID 4032, Tab 6).
For the FEA, in response to comments, OSHA refined its process, as
described below, to allow for a more nuanced approach to estimating the
number of affected workers. As a result of this revised approach, the
ratio of the estimated number of at-risk construction workers to the
estimated number of FTE-affected construction workers increased from
approximately three to one in the PEA to over five to one in the FEA.
OSHA first assigned each of the affected NAICS construction industries
to one of four subsectors in order to account for likely differences
among specific industries with respect to the frequency with which
silica-generating equipment is used. These subsectors are shown in
Table V-40a of the FEA. Note that non-construction industries doing
construction work--state and local governments and electric utilities--
are included in Subsector 3.
Second, because at-risk workers do not necessarily specialize in
jobs that use equipment that generates silica-containing dust, ERG
independently estimated the number of "affected" workers based on
judgments of the share of workers in each occupation that would likely
ever perform these tasks. These judgments were also made on a
subsector-by-subsector basis. In most cases, costs for program
requirements (but not for engineering controls) are based on the
numbers of affected workers performing each task in a given industry.
The estimated share of affected workers for the key occupations, taking
into account the specific construction subsector and task, is shown in
Table V-40b of the FEA.
Using the FTE rates, secondary ratios, and affected rate parameters
displayed in Table V-37 of the FEA, OSHA calculated, in Table V-39 of
the FEA, that there are an estimated 374,003 FTEs affected by the rule.
Table V-41 of the FEA converts these FTEs to 2.02 million affected
construction workers disaggregated by occupation based on 2012 County
Business Pattern (CBP) total employment of 2.93 million in affected
occupations in construction industries. Thus, as shown in Table V-41 of
the FEA, about 68.9 percent of construction workers in affected
occupations will be affected by the final rule. Table V-42 of the FEA
shows the same estimated number of affected workers, but disaggregated
by NAICS industries and equipment category. There are an estimated
13.45 million workers total in the affected industries, meaning that
about 15 percent of the workers in these industries are affected by the
final rule. That percentage is misleading, however, because almost 7.7
million of total employment in affected industries (almost 60 percent)
are employed in state and local governments, of which only 2 percent
are affected by the final rule. When these public workers are removed,
approximately 32 percent of the construction workers in affected
private industries are affected by the final rule.
All of the above statistics do not include the estimated 11,640 at-
risk abrasive blasters working in construction industries. Also,
because some occupations are associated with the use of more than one
equipment category, the "affected" totals are constrained to be less
than or equal to the industry total for each at-risk occupation.
Labor Cost and Total Value of Work Performed Using Silica Exposure-
Generating Equipment
To derive labor costs and project value for construction work done
using the specified equipment where occupational exposure to silica is
found, OSHA multiplied the mean hourly wage, as reported by OES (BLS,
2012, Document ID 1560), for each affected occupation within each
affected industry, by 2,000 hours. Then, to derive the total value of
annual wages expended for work done using specified equipment to
perform silica exposure-generating activities, OSHA multiplied that
product by the number of affected full-time-equivalent employees. These
estimates were then inflated to adjust for fringe benefits. These
loaded-wage costs, totaled by industry and equipment category, are
summarized in Table V-43 of the FEA as the annual labor value (or labor
cost) of silica-generating projects. Overall, OSHA estimated the labor
value of all silica-generating construction work performed with the
specified equipment to be $21.8 billion annually.
OSHA then converted the labor values for each industry and task
category from Table V-43 of the FEA to the total project value by
dividing by the labor share of project costs. This conversion is
possible because the labor share for each task category equals the
labor value divided by project value, so dividing the labor value by
the labor share generates an estimate of project value. The
corresponding estimates of total project value for each industry and
equipment category are shown in Table V-44 of the FEA. Overall, OSHA
estimated the value of silica-generating construction work performed
with the specified equipment at $41.2 billion. The values for specific
equipment categories ranged from $136.2 million for rock crushing
machine operators and tenders to $28.0 billion for heavy construction
equipment operations-II.
The value of work performed using the specified equipment was then
summed by NAICS industry to derive the total value of at-risk projects,
a base from which OSHA calculated control costs associated with
compliance with Table 1 or the final PEL.
Aggregate Control Costs in Construction To Comply With Table 1 or the
New PEL
For the final rule, OSHA revised Table 1 to include separate
engineering control and respirator requirements for tasks indoors or in
enclosed areas ("indoor tasks") to provide a means of exhaust as
needed to minimize the accumulation of visible airborne dust. As a
result, indoor tasks will have an additional cost to reflect use of
control equipment (e.g., a fan or "blower") providing a means of
exhaust as needed to minimize the accumulation of visible airborne
dust. These additional indoor costs were included in Table V-34 of the
FEA. However, to properly reflect these costs in the aggregate control
costs in construction, OSHA had to add an additional methodological
step. OSHA's Office of Technological Feasibility helped to develop
estimates of the distribution of silica-related work disaggregated
by the type of control equipment used, the duration of the task, and
the location of the task (i.e., indoors or outdoors). The resulting
distribution of silica-related work, which is later used to weight
costs by the percentage of tasks performed indoors or outdoors, is
displayed in Table V-45 of the FEA.
To derive estimates in Table V-46 of the FEA of aggregate
incremental compliance costs to meet final Table 1, the total value of
construction work using the specified equipment and requiring controls
(in Table V-44 of the FEA) was multiplied by the percentage of
incremental cost associated with the controls required for each
equipment category (in Tables V-36a and V-36b of the FEA), weighted by
the percentage of work using each type of equipment performed outdoors
and indoors (in Table V-45 of the FEA), and reduced by the percentage
of baseline compliance.
As indicated in Table V-46 of the FEA, OSHA estimates that the
incremental compliance costs for engineering controls (excluding tunnel
boring and abrasive blasting) will total $386.4 million for
construction work performed using the specified equipment affected by
the final standard.
Control Costs for Construction Tasks Not Under Table 1
Abrasive Blasting
In the PEA, OSHA estimated that some abrasive blasting crews were
not currently using all feasible engineering controls and added costs
for wet methods for them to achieve the proposed PEL. OSHA did not
receive comments on the PEA estimates of engineering control costs for
abrasive blasting crews and has retained the same methodology to
estimate costs for the FEA.
Consistent with what was done in the PEA, Table V-47a of the FEA
presents the unit costs and analytical assumptions applied in OSHA's
cost analysis of controlling silica exposures during abrasive blasting
operations. As shown in the table, after accounting for the number of
affected workers, crew size, daily output, blasting cost per square
foot, number of blasting days per year, and the percentage of crews
using sand, OSHA estimates that baseline annual costs for sand blasting
total $126.7 million. As in the PEA, ERG estimated that the incremental
cost for wet blasting is 30 percent of baseline costs and that 50
percent of crews currently use wet methods. Therefore, the annual costs
to comply with the final standard by using wet methods during sand
blasting are expected to total $19.0 million, or $2,366 per worker for
the approximately 8,033 workers exposed to silica dust.
Distributing these annualized costs by industry, OSHA estimates
that employers in NAICS 238200, Building Finishing Contractors, will
incur compliance costs of $12.1 million annually, while firms in NAICS
238900, Other Specialty Trade Contractors, will incur compliance costs
of $6.9 million annually.
Tunnel Boring
Tunnel boring is not included on Table 1 of the final rule. An
employer engaged in tunnel boring must comply with the PEL of 50 [mu]g/
m\3\ specified in Sec. 1926.1153(d). Employers in tunnel boring must
already comply with the ventilation and dust suppressant requirements
in subpart S of Part 1926 (Underground construction), which would have
allowed those employers to meet the previous PEL of 250 [mu]g/m\3\.
Therefore, OSHA calculates the additional controls necessary to reduce
exposures from the preceding PEL to the new PEL of 50 [mu]g/m\3\.
In most cases, employers are able to reduce exposures to the
preceding PEL by providing suction at the drill head, removing the dust
as soon as it is generated. The technological feasibility chapter of
the FEA demonstrates that employers can do so by extending the existing
suction controls as the drill head progresses. There are limits on
these extensions, however, and the amount of worker exposure can
increase if the suction is not extended frequently enough to keep it at
the drill head. This extension does not require additional machinery,
but it is likely to require the employer to invest more labor time to
extend the suction device more frequently to meet the new PEL than
previously necessary to meet the preceding PEL. OSHA has estimated in
Table V-47 of the FEA the control costs for tunnel boring using the
same cost methodology applied in the PEA (see Tables V-21 and V-24 in
the PEA) to calculate the incremental cost as a percentage of baseline
control costs (0.013%). The rest of the calculations in Table V-47
reflect 2012 data on the number of affected FTE tunnel workers and 2012
hourly wage rates. The resulting estimate of annualized incremental
control costs for tunnel boring is about 0.02 million.
Table V-48 of the FEA adds the abrasive blasting and the tunnel
boring control costs in construction to the control costs for Table 1
tasks presented in Table V-46 of the FEA.
Adjustment for Self-Employed Workers on a Multi-Employer Worksite
The OSH Act provides authority for OSHA to regulate employers for
the protection of their employees. Because sole proprietors without
employees, referred to as "self-employed workers" for the purposes of
this discussion, are not "employers" under the Act, OSHA cannot
require them to comply with the silica standard. On a multi-employer
worksite, however, their silica activities could expose employees
protected by the Act to respirable crystalline silica.
Employers must still protect their employees from exposure to
silica in accordance with the standard, whether it is generated by work
performed by their own employees or by the work performed by a sole
proprietor not regulated by the Act (see the summary and explanation of
the written exposure control plan requirements in paragraph Sec.
1926.1153(g)(1)(iv)). Under OSHA's multi-employer citation policy (CPL
02-00-124), employers of workers who may be exposed to silica are
considered "exposing employers" who have a duty to protect their
employees, even from hazards they do not correct themselves. However,
the controlling employer, the employer in overall charge of the
worksite or project, also has a duty to exercise reasonable care to
prevent and detect violations of the silica standard on the multi-
employer worksite. The silica standard does not limit the means by
which either employer may fulfill this duty, and in many cases the
issue may be resolved if the work schedule does not place the self-
employed worker in the same area of the worksite at the same time as
employees, thereby avoiding the need for additional measures.
As discussed in Chapter III of the FEA, CISC requested that the
Agency account for the costs arising from self-employed workers
separately based on the theory that self-employed workers will use the
controls necessary to comply with Table 1 to reduce exposures to others
when working on a multi-employer worksite where employees are present
(Document ID 4217, p. 80). CISC identified several reasons why this
might happen, including self-interested recognition of "Table 1
specifications as the safe way to perform their work"; demands by
construction general contractors that anyone working on their site,
whether self-employed or not, conform to regulatory requirements; and
demands by nearby employers that their employees "not suffer increased
silica exposures from inappropriate practices by self-employed workers."
While these are not costs that OSHA typically includes in its
analysis, OSHA recognizes that Table 1 is unique among OSHA standards,
and that it is possible that controlling employers on a multi-employer
construction worksite may assume some costs of engineering controls--
either by providing the controls or by reimbursing the self-employed
persons for the costs of the controls through increased fees--when they
cannot resolve the issue through simple scheduling choices. Therefore,
OSHA is estimating the additional cost of the engineering controls in
that scenario.
In order to estimate the number of self-employed persons in
construction, CISC's contractor, Environomics, Inc., took the following
approach:
The U.S. Census Bureau, in Revised 2008 Nonemployer Statistics
Reflecting 2009 Methodology Changes, provides information on the
number of self-employed individuals ("nonemployers") working in
each of the 4-digit construction industries (total of 2.52 million
self-employed construction workers), but no further information on
the occupations of these self-employed workers. In order to estimate
the number of self-employed workers in each of the various at-risk
construction occupations that OSHA identified and that we added, we
simply assumed that these 2.52 million "nonemployers" are
distributed among occupations within each construction NAICS in the
same proportion as employed workers are distributed among
occupations within the NAICS (Document ID 4217, p. 80).
Note that the Census data that Environomics used provides detail on
self-employed persons by 4-digit NAICS construction industries but not
by occupation. Hence, in the absence of occupational data, Environomics
simply assumed that the number of self-employed persons by occupation
was proportional to the number of employees by occupation--which
implies that the ratio of the number of self-employed persons to
employees was the same for each occupation. Using this database and
approach, Environomics estimated that the ratio of self-employed
persons to employees for all occupations affected by the rule was 40.1
percent (1,811,009 self-employed relative to 4,519,889 employees).
Based on the full-time-equivalent (FTE) number of workers--which, in
OSHA's estimation methodology, determines the amount of engineering
control equipment used--Environomics calculated that the ratio of FTE
self-employed persons to FTE employees for all occupations affected by
the rule was 35.7 percent.
Having reviewed the Environomics self-employment analysis, OSHA has
concluded that the occupation of the self-employed persons is a much
more relevant factor for estimating costs than the 4-digit construction
industry in which self-employed persons work. Therefore, for its
analysis, OSHA has chosen to rely on data from the 2013 BLS Current
Population Survey, with the goal of estimating the ratio of the number
of self-employed persons to the number of employees by occupation.
Table V-49 of the FEA presents data from the 2013 BLS Current
Population Survey with the focus on the ratio of the self-employed to
the non-self-employed (i.e., employees).\44\ Note that this table
includes many occupations that do not involve silica exposure (e.g.,
boilermakers, paperhangers, glaziers) and others that are not covered
by OSHA (e.g., mining machine operators; roof bolters, mining--covered
by MSHA).
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\44\ The absolute number of self-employed and employed in
construction by occupation from this survey is not, itself, relevant
for this analysis. What matters is the ratio of self-employed to
non-self employed in construction where the estimates of both types
of workers are derived from a single source.
---------------------------------------------------------------------------
Table V-50 of the FEA presents the same data as shown in Table V-49
of the FEA, but restricted to just those occupations where OSHA
estimated that workers are potentially exposed to hazardous levels of
respirable crystalline silica. One thing that is immediately obvious in
this table is the very wide variation from occupation to occupation in
the ratio of the self-employed to the employed, with the ratio ranging
from 0 percent to 47.53 percent. This wide variation is clearly
incompatible with the assumption made by Environomics that the ratio of
the number of self-employed to employees is the same for all
occupations. Table V-50 of the FEA also shows that average ratio of
self-employed to employees over all construction occupations involving
silica exposure (when the ratio is allowed to vary by occupation) is
22.82 percent when weighted by the number of employees (as compared to
40.1 percent as estimated by Environomics).
As noted above, in OSHA's methodology, the amount of engineering
control equipment used is based on the FTE number of workers. In Table
V-51 of the FEA, OSHA multiplied the FTE rate for each occupation (from
Tables V-38a and V-38b of the FEA) by the number of self-employed
workers and employees in that occupation (from Table V-48 of the FEA).
As shown in Table V-51 of the FEA, there are an estimated 69,461 FTE
self-employed workers in at-risk occupations, relative to the total of
377,913 FTE employees in at-risk occupations. In other words, the
number of at-risk FTE self-employed workers is 18.38 percent of the
number of at-risk FTE employees (as compared to 35.7 percent as
estimated by Environomics).
The analysis of the number of self-employed persons conducted by
Environomics stopped at this point. However, as OSHA explained in
Chapter III of the FEA, self-employed workers are not required to
comply with the final rule and are only likely to do so in two
situations: (1) Where self-employed workers are generating silica dust
while working in a multi-employer construction worksite such that their
activities could expose the employees of others, and (2) where the host
employer (or competent person) is unable to schedule the self-employed
worker's activities or location so as to prevent the exposure or
overexposure of other, covered workers. OSHA does not have data on the
likelihood of either of these two conditions. OSHA judges that self-
employed workers work at multi-employer construction sites at the same
times as others a minority of their worktime, and work even less
frequently within the same area such that covered employees could be
exposed. Nevertheless, OSHA is conservatively estimating here that they
do so 50 percent of the time. OSHA also judges that the host contractor
(with the assistance of the competent person) would be able to schedule
the self-employed workers' activities or location so as to prevent the
exposure or overexposure of other, covered workers a majority of the
time. This makes sense because self-employed workers would often be
used on multi-employer sites when they possess special skills not
otherwise available onsite. Therefore, their work frequently could be
performed at a different time or location from the other work. In any
case, for costing purposes, OSHA is conservatively estimating that the
work of self-employed persons cannot be isolated in time or space so as
to prevent the exposure or overexposure of other, covered workers 50
percent of the time that those self-employed workers are on the multi-
employer worksite.
Based on these estimates, OSHA calculates that only 25 percent of
the at-risk work of self-employed workers would meet the conditions in
which a host or controlling employer would incur engineering control
costs to mitigate the exposures to employees on the site. At the bottom
of Table V-51 of the FEA, OSHA has accordingly reduced the number of
FTE self-employed workers using equipment to perform silica-dust-producing
work relative to the number of FTE at-risk employees to 25 percent of the
earlier estimate of 18.38 percent. OSHA therefore concludes that the
number of FTE at-risk self-employed workers imposing costs on host
employers is equal to 4.60 percent of the number of FTE at-risk
employees. This result is shown at the bottom of Table V-51 of the FEA.
Finally, in Table VII-13, OSHA increased the estimates of the
control costs for work performed using the specified equipment in
construction presented in Table V-48 of the FEA by 4.60 percent to
include the engineering control costs that would be incurred by host or
controlling employers to control the exposures caused by self-employed
workers. This increases the annualized cost of engineering controls
needed in construction to comply with the final rule from $405.5
million to $423.4 million.
2. Respiratory Protection
OSHA's cost estimates assume that implementation of the recommended
silica controls prevents workers in general industry and maritime from
being exposed over the PEL in most cases. Specifically, based on its
technological feasibility analysis, OSHA expects that the engineering
controls are adequate to keep silica exposures at or below the PEL for
an alternative PEL of 100 [mu]g/m\3\ (introduced for economic analysis
purposes).\45\ For the new 50 [mu]g/m\3\ PEL, OSHA's feasibility
analysis suggests that the controls that employers use, either because
of technical limitations or imperfect implementation, might not be
adequate in all cases to ensure that worker exposures in all affected
job categories are at or below 50 [mu]g/m\3\.
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\45\ As a result, OSHA expects that establishments in general
industry do not currently use respirators to comply with the current
OSHA PEL for quartz of approximately 100 [mu]g/m\3\.
---------------------------------------------------------------------------
For the FEA, OSHA estimates that respirators will be required: (1)
For all workers that the Agency's technological feasibility analysis
has determined will require respirator use; and (2) for ten percent of
the remaining workers currently exposed above 50 [mu]g/m\3\ at covered
workplaces.
This is a change in methodology from the PEA, where OSHA estimated
the percentage of workers requiring respirators in an industry as
either (1) or (2), whichever was larger. The Agency believes that the
FEA formula, which results in higher estimates of respirator usage, is
more accurate in that it reflects the combined effects of (1) and (2)
whereas the earlier methodology did not. The number of workers that the
FEA estimates will need respirators is presented in Table V-13 in the
FEA.
In the PEA, OSHA concluded that all maritime workers engaged in
abrasive blasting were already required to use respirators under
existing OSHA standards and, therefore, maritime establishments would
incur no additional costs for maritime workers to use respirators as a
result of this final rule. However, for the FEA, OSHA has determined
from its earlier technological feasibility analysis that only abrasive
blasting operators, but not abrasive blasting helpers, are already
required to use respirators under existing OSHA standards. The Agency,
therefore, has added respirator costs for abrasive blaster helpers in
maritime (half of all the abrasive blaster workers) as a result of this
final rule.
For construction, employers whose workers are exposed to respirable
silica above the proposed PEL were assumed to adopt the appropriate
task-specific engineering controls and, where required, respirators
prescribed in Table 1 and paragraph (g)(1) in the final standard.
Respirator costs in the construction industry have been adjusted to
take into account OSHA's estimate (consistent with the findings from
the NIOSH Respiratory Survey, 2003, Document ID 1492) that 56 percent
of establishments in the construction industry are already using
respirators that would be in compliance with the final silica rule.
OSHA used respirator cost information from a 2003 OSHA respirator
study to estimate the annual cost of $367 (general industry) or $286
(construction) for disposable filtering facepiece respirators, $520
(general industry) or $409 (construction) for a half-mask, non-powered,
air-purifying respirator and $644 (general industry) or $533
(construction) per year (in 2012 dollars) for a full-face non-powered
air-purifying respirator (ERG, 2003, Document ID 1612). These unit
costs reflect the annualized cost of respirator use, including
accessories (e.g., filters), training, fit testing, and cleaning where
relevant.
The PEA estimated that (with the exception of workers who are
entering regulated areas) all workers in general industry and
construction who need respirators with an assigned protection factor
(APF) of 10 would use non-disposable, half-face respirators. The FEA
estimates that in general industry half of the workers who need
respirators will use half-face elastomeric respirators and half will
use disposable N95 respirators. This is because, as clarified in the
final rule, both disposable and non-disposable respirators are
available with an APF of 10, and, with each type of respirator offering
certain advantages, OSHA accordingly estimates that about half of the
employees in general industry and maritime will prefer the ease of use
of disposable respirators while the other half will prefer the
durability of non-disposable respirators. For the construction sector,
the FEA estimates that 10 percent of workers needing respirators will
use elastomeric half-face respirators and 90 percent will use
disposable N95 respirators. This is because very few workers in
construction engage in tasks requiring respirator use full-time. Under
those circumstances, disposable respirators are both more convenient to
use and much less expensive than reusable respirators.
In addition to bearing the costs associated with the provision of
respirators, employers will incur a cost burden to establish respirator
programs. OSHA projects that this expense will involve an initial 8
hours for establishments with 500 or more employees and 4 hours for all
other firms. After the first year, OSHA estimates that 20 percent of
establishments would revise their respirator program every year, with
the largest establishments (500 or more employees) expending 4 hours
for program revision, and all other employers expending 2 hours for
program revision. Consistent with the findings from the NIOSH
Respiratory Survey (2003) (Document ID 1492), OSHA estimates that 56
percent of establishments in the construction industry that would
require respirators to achieve compliance with the final PEL already
have a respirator program.\46\ OSHA further estimates that 50 percent
of firms in general industry and all maritime firms that would require
respirators to achieve compliance already have a respirator program.
---------------------------------------------------------------------------
\46\ OSHA's derivation of the 56 percent current compliance rate
in construction, in the context of the final silica rule, is
described in Chapter V in the FEA.
---------------------------------------------------------------------------
3. Exposure Assessment
OSHA developed separate cost estimates for (1) initial monitoring
or any exposure monitoring at hydraulic fracturing sites and (2)
scheduled monitoring at fixed sites (which excludes hydraulic
fracturing). Costs under (2) were estimated to be lower because the
exposure monitoring is expected to be of shorter duration (possibly
obviating an overnight stay) and could be conducted by a lower-cost
Industrial Hygienist (IH) or IH technician rather than by a CIH. Based
on the comments received in the record, OSHA decided to significantly
increase its estimate from $500 (in the PEA) to $2,500 for an IH
consultant to perform initial exposure monitoring or to perform at
sites that have not previously been well characterized. In the
construction sector, the $2,500 cost estimate for IH services applies
to all exposure monitoring since the worksite is not fixed and has not
been previously characterized. OSHA estimates that the IH periodic
exposure monitoring costs would be approximately $1,250, or half of the
$2,500 estimate. These IH monitoring costs would cover 2, 6, and 8
personal breathing zone (PBZ) samples per day for small, medium, and
large establishments, respectively.
For initial monitoring or any exposure monitoring at hydraulic
fracturing sites, the total unit cost of an exposure sample is
estimated to range from $487 to $1,425 (depending on establishment
size). For periodic monitoring in general industry and maritime,
excluding hydraulic fracturing sites, the total unit cost of an
exposure sample is estimated to range from $328 to $796 (depending on
establishment size).
Tables V-14 and V-61 in the FEA shows the unit costs and associated
assumptions used to estimate exposure assessment costs. Unit costs for
exposure sampling include direct sampling costs, the costs of
productivity losses, and recordkeeping costs, and, depending on
establishment size, range from $328 to $1,421 per sample in general
industry and maritime and from $488 to $1,425 per sample in
construction.
For costing purposes, based on OSHA (2016), OSHA estimated that
there are four workers per work area. OSHA interpreted the initial
exposure assessment in general industry and maritime as requiring
first-year testing of at least one worker in each distinct job
classification and work area who is, or may reasonably be expected to
be, exposed to airborne concentrations of respirable crystalline silica
at or above the action level.
For periodic monitoring, the final standard provides employers an
option of assessing employee exposures either under a performance
option (paragraph (d)(2)) or a scheduled monitoring option (paragraph
(d)(3)). For the performance option, the employer must assess the 8-
hour TWA exposure for each employee on the basis of any combination of
air monitoring data or objective data sufficient to accurately
characterize employee exposures to respirable crystalline silica. For
the scheduled monitoring option (termed the "periodic" monitoring
option in the proposal), the employer must perform initial monitoring
to assess the 8-hour TWA exposure for each employee on the basis of one
or more (PBZ) air samples that reflect the exposures of employees on
each shift, for each job classification, in each work area. Where
several employees perform the same job tasks on the same shift and in
the same work area, the employer may sample a representative fraction
of these employees in order to meet this requirement. In representative
sampling, the employer must sample the employee(s) who are expected to
have the highest exposure to respirable crystalline silica. Under the
scheduled monitoring option, requirements for periodic monitoring
depend on the results of initial monitoring. If the initial monitoring
indicates that employee exposures are below the action level, no
further monitoring is required. If the most recent exposure monitoring
reveals employee exposures to be at or above the action level but at or
below the PEL, the employer must repeat monitoring within six months of
the most recent monitoring. If the most recent exposure monitoring
reveals employee exposures to be above the PEL, the employer must
repeat monitoring within three months of the most recent monitoring.
OSHA used the fixed schedule option under the frequency-of-monitoring
requirements to estimate, for costing purposes, that exposure
monitoring will be conducted (a) twice a year where initial or
subsequent exposure monitoring reveals that employee exposures are at
or above the action level but at or below the PEL, and (b) four times a
year where initial or subsequent exposure monitoring reveals that
employee exposures are above the PEL.
As required under paragraph (d)(4) of the final rule, employers
must reassess exposures whenever a change in the production, process,
control equipment, personnel, or work practices may reasonably be
expected to result in new or additional exposures at or above the
action level, or when the employer has any reason to believe that new
or additional exposures at or above the action level have occurred. In
response to comments, OSHA increased its estimate from 15 percent to 25
percent of the share of workers whose initial exposure or subsequent
monitoring was at or above the action level would undertake additional
monitoring.
Changes from the proposed to the final rule have resulted in a
significant reduction in OSHA's estimate of the annual number of
samples taken by construction employers. For the final rule, employers
following Table 1 are not required to engage in initial or subsequent
exposure monitoring for those construction workers engaged in tasks on
Table 1. Therefore, OSHA only estimated scheduled semi-annual exposure
monitoring (for expected exposures at or above the action level but at
or below the PEL) and scheduled quarterly exposure monitoring costs
(for expected exposures above the PEL) for those operations are not
listed on Table 1. In addition, OSHA estimated that some small fraction
of employers--1 percent--will choose to conduct initial sampling to
investigate the possibility that exposures are so low (below the action
level) that Table 1 need not be followed.
A more detailed description of unit costs, other unit parameters,
and methodological assumptions for exposure assessments is presented in
Chapter V of the FEA.
4. Medical Surveillance
Paragraph (i) of the final standard requires the employer to make
medical surveillance available for each employee occupationally exposed
to respirable crystalline silica at or above the action level of 25
[mu]g/m\3\ for 30 days or more per year. ERG (2013) assembled
information on representative unit costs for initial and periodic
medical surveillance (Document ID 1712). Separate costs were estimated
for current employees and for new hires as a function of the employment
size (i.e., 1-19, 20-499, or 500+ employees) of affected
establishments. Table V-16 in the FEA presents ERG's unit cost data and
modeling assumptions used by OSHA to estimate medical surveillance
costs.
In accordance with paragraph (i)(2) of the final standard, the
initial medical examination will consist of (1) a medical and work
history, (2) a physical examination with special emphasis on the
respiratory system, (3) a chest x-ray interpreted and classified
according to the International Labour Office (ILO) International
Classification of Radiographs of Pneumoconiosis by a NIOSH-certified B
Reader, (4) a pulmonary function test administered by a spirometry
technician with a current certificate from a NIOSH-approved course, (5)
testing for latent tuberculosis (TB) infection, and (6) any other tests
deemed appropriate by the PLHCP. In accordance with paragraph (i)(3) of
the final standard, the contents of the periodic medical examinations
are the same as those for the initial examination, with the exception
that testing for latent tuberculosis infection is not required.
As shown in Table V-16 in the FEA, the estimated unit cost of the
initial health screening for current employees in general industry and
maritime ranges from approximately $415 to $435 and includes direct
medical costs, the opportunity cost of worker time (i.e., lost work
time, evaluated at the worker's 2012 hourly wage, including fringe
benefits) for offsite travel and for the initial health screening
itself, and recordkeeping costs. The variation in the unit cost of the
initial health screening is due entirely to differences in the
percentage of workers expected to travel offsite for the health
screening. In OSHA's experience, the larger the establishment the more
likely it is that the selected PLHCP would provide the health screening
services at the establishment's worksite. OSHA estimates that 20
percent of establishments with fewer than 20 employees, 75 percent of
establishments with 20-499 employees, and 100 percent of establishments
with 500 or more employees would have the initial health screening for
current employees conducted onsite.
The unit cost components of the initial health screening for new
hires in general industry and maritime are identical to those for
existing employees with the exception that the percentage of workers
expected to travel offsite for the health screening would be somewhat
larger (due to fewer workers being screened annually, in the case of
new hires, and therefore yielding fewer economies of onsite screening).
OSHA estimates that 10 percent of establishments with fewer than 20
employees, 50 percent of establishments with 20-499 employees, and 90
percent of establishments with 500 or more employees would have the
initial health screening for new hires conducted onsite. As shown in
Table V-16 in the FEA, the estimated unit cost of the initial health
screening for new hires in general industry and maritime ranges from
approximately $417 to $437.
The unit costs of medical surveillance in construction were derived
using identical methods. As shown in Table V-63 of the FEA, the
estimated unit costs of the initial health screening for current
employees in construction range from approximately $429 to $467; the
estimated unit costs of the initial health screening for new hires in
construction range from $433 to $471.
In accordance with paragraph (h)(2) of the final standard, the
initial medical examination will consist of (1) a medical and work
history, (2) a physical examination with special emphasis on the
respiratory system, (3) a chest x-ray interpreted and classified
according to the International Labour Office (ILO) International
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B
Reader, (4) a pulmonary function test administered by a spirometry
technician with a current certificate from a NIOSH approved course, (5)
testing for latent tuberculosis (TB) infection, and (6) any other tests
deemed appropriate by the physician or licensed health care
professional (PLHCP). In accordance with paragraph (h)(3) of the final
standard, the contents of the periodic medical examinations are the
same as those for the initial examination, with the exception that
testing for latent tuberculosis infection is not required.
The estimated unit cost of periodic health screening also includes
direct medical costs, the opportunity cost of worker time, and
recordkeeping costs. As shown in Table V-16 in the FEA, these triennial
unit costs in general industry and maritime vary from $415 to $435. For
construction, as shown in Table V-63 in the FEA, the triennial unit
costs for periodic health screening vary from roughly $429 to $467. The
variation in the unit cost (with or without the chest x-ray and
pulmonary function test) is due entirely to differences in the
percentage of workers expected to travel offsite for the periodic
health screening. OSHA estimated that the share of workers traveling
offsite, as a function of establishment size, would be the same for the
periodic health screening as for the initial health screening for
existing employees.
OSHA estimated a turnover rate of 75 percent in general industry
and maritime and 40 percent in construction, based on estimates of the
separations rate (layoffs, quits, and retirements) provided by the
Bureau of Labor Statistics (BLS, 2012). However, not all new hires
would require initial medical testing. As specified in paragraph (h)(2)
of the final rule, employees who had received a medical examination
that meets the requirements of this section within the previous three
years would be exempt from undergoing a second "initial" medical
examination. OSHA estimates that 25 percent of new hires in general
industry and maritime and 60 percent of new hires in construction would
be exempt from the initial medical examination.
Although OSHA believes that some affected establishments in
construction currently provide some medical testing to their silica-
exposed employees, there was significant testimony in the record that
many employers would at least have to make changes to their existing
practices in order to comply with the new standard. Therefore, for
costing purposes, the Agency assumed no current compliance with the
health screening requirements of the rule.
OSHA requested information from interested parties on the current
levels and the comprehensiveness of health screening in general
industry, maritime, and construction. Although testimony in the record
indicated that current medical surveillance programs exist to a limited
extent among affected employers (see Chapter V, Costs of Compliance)
for costing purposes for the rule, OSHA has conservatively assumed no
current compliance with the health screening requirements.
Finally, OSHA estimated the unit cost of a medical examination by a
pulmonary specialist for those employees found to have signs or
symptoms of silica-related disease or are otherwise referred by the
PLHCP. OSHA estimates that a medical examination by a pulmonary
specialist costs approximately $335 for workers in general industry and
maritime and $364 for workers in construction. This cost includes
direct medical costs, the opportunity cost of worker time, and
recordkeeping costs. In all cases, OSHA anticipates that the worker
will travel offsite to receive the medical examination by a pulmonary
specialist (see Chapter V in the FEA for a full discussion of OSHA's
analysis of medical surveillance costs under the final standard).
5. Familiarization Costs and Costs of Communication of Silica Hazards
to Employees
OSHA did not estimate any employer familiarization costs in the PEA
in support of the proposed rule. OSHA's rationale for not including
familiarization costs in the PEA was that there was already an existing
silica standard in place and, therefore, the Agency expected that any
familiarization costs for a revised silica standard would be
negligible.
However, several commenters on the proposed rule argued that
employers will need to spend time to become familiar with the
requirements of the final rule; that the employer time spent is the
direct result of the final rule itself; and, therefore, that OSHA
should include employer familiarization costs as part of the costs of
the final rule.
OSHA found the comments in support of including some
familiarization costs persuasive and the Agency has now concluded that
employers will need to spend some time to understand the ancillary
provisions and the other new and revised components of the final rule
and to determine what actions they must take in order to comply. OSHA
estimated that 8 hours would be spent on familiarization in its 2012
update to the Hazard Communication Standard (see 77 FR 17637-17638
(March 26, 2012)) and believes that this is a reasonable estimate of
familiarization time for a typical firm for this final silica rule.
For the silica rule OSHA used the number of employees as a proxy
for the level of familiarization that would be needed. Accordingly,
OSHA has reduced the average of 8 hours of familiarization time for
establishments with fewer employees and increased it significantly for
establishments with a larger number of employees: 4 hours per covered
employer with fewer than 20 employees; 8 hours per covered employer
with 20 to 499 employees; and 40 hours per covered employer with 500 or
more employees. These estimates represent average familiarization
times; it is expected that some establishments will spend less time on
familiarization than estimated here (e.g.,, if worker exposure never
meets or exceeds the action level) and some will spend more time on
familiarization than estimated here. The annualized costs per
establishment range from $19 to $189 for establishments in general
industry and maritime and from $21 to $207 for establishments in
construction.
The final standard requires two forms of hazard communication to
employees: Paragraph (j)(1) notes that employers must include
respirable crystalline silica in their existing hazard communication
programs required by the hazard communication standard (HCS)
(29 CFR 1910.1200), and paragraph (j)(3) requires that employers
must provide employees with specific information and training. As
specified in paragraph (j)(3)(i) of the final rule and the HCS,
training is required for all employees in general industry and maritime
are covered by the standard. This requirement applies to newly hired
workers who would require training before starting work, workers who
change jobs within their current workplace or are assigned new tasks or
exposure protection, and any covered worker an employer believes needs
additional training. Thus OSHA has estimated a one-time training cost
for existing employees as well as recurring training costs to account
for new hires.
OSHA estimated separate costs for initial training of current
employees and for training new hires. Given that new-hire training
might need to be performed frequently during the year, OSHA estimated a
smaller class size for new hires. OSHA anticipates that training, in
accordance with the requirements of the final rule, will be conducted
by in-house safety or supervisory staff with the use of training
modules or videos and will last, on average, one hour. OSHA judged that
establishments could purchase sufficient training materials at an
average cost of $2.10 per worker, encompassing the cost of handouts,
video presentations, and training manuals and exercises. Included in
the cost estimates for training are the value of worker and trainer
time as measured by 2012 hourly wage rates (to include fringe
benefits). OSHA also developed estimates of average class sizes as a
function of establishment size. For initial training, OSHA estimated an
average class size of 5 workers for establishments with fewer than 20
employees, 10 workers for establishments with 20 to 499 employees, and
20 workers for establishments with 500 or more employees. For new hire
training, OSHA estimated an average class size of 2 workers for
establishments with fewer than 20 employees, 5 workers for
establishments with 20 to 499 employees, and 10 workers for
establishments with 500 or more employees.
The unit costs of training are presented in Tables V-22 (for
general industry/maritime) and V-69 (for construction) in the FEA.
Based on ERG's work, OSHA estimated the annualized cost (annualized
over 10 years) of initial training per current employee at between
$3.39 and $4.10 and the annual cost of new-hire training at between
$30.90 and $47.05 per employee in general industry and maritime,
depending on establishment size. For construction, OSHA estimated the
annualized cost of initial training per employee at between $4.21 and
$4.99 and the annual cost of new hire training at between $38.14 and
$55.76 per employee, depending on establishment size.
OSHA recognizes that many affected establishments currently provide
training on the hazards of respirable crystalline silica in the
workplace. In the PEA OSHA estimated that 50 percent of affected
establishments already provide such training. However, some of the
training specified in the final rule requires that workers be familiar
with the training and medical surveillance provisions in the rule.
The Agency reviewed its baseline training estimates in light of
comments in the record decided to take a more conservative approach to
estimating current compliance with the training provisions in the final
rule. Therefore, for the FEA, OSHA assumed no baseline respirable
crystalline silica training (other than that already required under the
HCS) and that a full hour of training, on average, will be required for
all covered workers. This removal of baseline respirable crystalline
silica training in estimating training costs has the effect, by itself,
of increasing the effective training costs in the FEA relative to the
PEA by 33 percent (from an average training time, per employee, of 45
minutes to 60 minutes). OSHA recognizes that this change may lead to an
overestimation of training costs for some employers.
6. Regulated Areas
Paragraph (e)(1) of the final standard requires employers in
general industry and maritime to establish a regulated area wherever an
employee's exposure to airborne concentrations of respirable
crystalline silica is, or can reasonably be expected to be, in excess
of the PEL. Paragraph (e)(2)(i) requires employers to demarcate
regulated areas from the rest of the workplace in a manner that
minimizes the number of employees exposed to respirable crystalline
silica within the regulated area. Paragraph (e)(2)(ii) requires
employers to post signs at all entrances to regulated areas bear the
legend specified in paragraph (j)(2) of the standard. Under paragraph
(e)(3), employers must limit access to regulated areas and under
paragraph (e)(4), employers must provide each employee and designated
employee representative entering a regulated area with an appropriate
respirator (in accordance with paragraph (g) of the standard) and
require each employee and designated employee representative to use the
respirator while in a regulated area.
Based on OSHA (2016), OSHA derived unit cost estimates for
establishing and maintaining regulated areas to comply with these
requirements and estimated that one area would be necessary for every
eight workers in general industry and maritime exposed above the PEL.
Planning time for a regulated area is estimated to be an initial seven
hours of supervisor time (initial cost of $282.67 in 2012 dollars), and
one hour for changes annually (at a cost of $40.38 in 2012 dollars);
material costs for signs and boundary markers (annualized at $66.93 in
2012 dollars); and costs of $526 annually for two disposable
respirators per day to be used by authorized persons (other than those
who regularly work in the regulated area) who might need to enter the
area in the course of their job duties. Tables V-25 in the FEA shows
the cost assumptions and unit costs applied in OSHA's cost model for
regulated areas in general industry and maritime. Overall, OSHA
estimates that each regulated area would, on average, cost employers
$666 annually in general industry and maritime.
7. Written Exposure Control Plans
A written exposure control plan provision was not included in the
silica proposal, and no costs for a written exposure control plan were
estimated in the PEA. Paragraph (f)(2) in the final standard for
general industry and paragraph (g) in the final standard for
construction specify the following requirements for a written exposure
control plan: (i) A description of the tasks in the workplace that
involve exposure to respirable crystalline silica; (ii) a description
of the engineering controls, work practices, and respiratory protection
used to limit employee exposure to respirable crystalline silica for
each task; (iii) a description of the housekeeping measures used to
limit employee exposure to respirable crystalline silica; and (iv) for
construction, a description of the procedures used to restrict access
to work areas, when necessary, to minimize the number of employees
exposed to respirable crystalline silica and their level of exposure,
including exposures generated by other employers or sole proprietors.
In the FEA, Table V-27 shows the unit costs and assumptions for
written exposure control plans in general industry and Tables V-72
and V-74 show, respectively the unit costs for developing and
implementing written exposure control plans in construction.
Unit costs for a written exposure control plan were calculated
based on establishment size, and the Agency assumed, for costing
purposes, that a supervisor will develop and update the written
exposure control plan for each establishment, spending 1 hour for
establishments with fewer than 20 employees, 4 hours for those
establishments with between 20 and 499 employees, and 16 hours for
those establishments with 500 or more employees. OSHA estimated that 1
hour would be sufficient for very small establishments because there
is, on average, barely more than 1 worker covered by the standard per
very small establishment in general industry and maritime.
OSHA further determined that the additional supervisory time needed
to review and evaluate the effectiveness of the plan, and to update it
as necessary, will also vary by establishment size. OSHA estimated 0.5
hours for establishments with fewer than 20 employees, 2 hours for
those with between 20 and 499 employees, and 8 hours for those with 500
or more employees to perform the annual review and update. The Agency
expects that no other labor or materials will be required to implement
the plan, so the sole cost for this provision is the time it will take
to develop, review, and update the plan.
In the context of general industry or maritime activities in
permanent facilities, the implementation of the written exposure
control plan will not typically involve significant time or effort
above existing operations. In construction, however, employers may be
faced with new costs to implement the written exposure plan as they
move from site to site. OSHA has therefore included costs for
implementation, in addition to the costs for development of the plan,
for construction activities. The plan must be implemented by a
"competent person," and OSHA has addressed the additional costs for
training the competent person after the discussion of the general
implementation costs.
Paragraph (g)(4) requires the employer to designate a competent
person to implement the exposure control plan, and restrict access to
work areas, when necessary, to minimize the number of employees exposed
to respirable crystalline silica and their level of exposure, including
exposures generated by other employers or sole proprietors. The
competent person has two broad options to restrict access to work areas
when necessary: (1) Notifying or briefing employees, or (2) direct
access control. The direct access control component is similar to the
written access control plan included in the PEA, which OSHA has
replaced with the written exposure control plan in the final rule.
While the requirements for the written exposure control plan are more
performance-oriented and thus should provide more flexibility for
employers and reduce the cost of compliance, OSHA has estimated the
costs of these options using, where appropriate, comparable components
of the regulated area and written access control plan costs estimated
in the PEA.
For the employee notification or briefing option, OSHA estimated
that, on average, it will take the competent person 15 minutes (0.25
hours) per job to revise the briefing plan, that each job will last 10
work-days, and that there are 150 construction working days in a year
(Document ID 1709, p. 4-6). OSHA further estimated that it will take
the competent person 6 minutes (0.1 hours) to brief each at-risk crew
member (where an at-risk crew member could be an employee, a
contractor, a subcontractor, or other worker under the control of the
competent person) and that each crew consists of 4 at-risk workers. As
shown in Table V-74 in the FEA, the annual cost of the job briefing
option is $105.25 per at-risk crew member.
For the direct access control option, OSHA estimated that, on
average, it will take the competent person 15 minutes (0.25 hours) per
job to revise the plan concerning direct access control and, again,
that each job will last 10 work-days and that there are 150
construction working days in a year. Thus, OSHA estimates that, on
average, each employer would implement a direct access control 15 times
per year over a total of 3.75 hours per year.
OSHA also added the cost of signage and tape for constructing
physical barriers: 100 feet of hazard tape (per job) and three warning
signs. These costs are all displayed in Table V-74 in the FEA. As also
shown there, the annualized cost of the direct access control option is
$71.40 per at-risk crew member.
As discussed in the Summary and Explanation section of this
preamble concerning the written exposure control plan, restricting
access is necessary where respirator use is required under Table 1 or
when an exposure assessment reveals that exposures are in excess of the
PEL, or in other situations identified by the competent person. On the
other hand, when exposure to respirable crystalline silica is being
successfully contained by engineering controls and work practices
specified in Table 1 and no respirator use is required by Table 1,
implementation of access control procedures is not required.
OSHA assumed that, in restricting access, half the time employers
would use the briefing option and the other half of the time they would
use direct access control. Consequently, as shown in Table V-74, the
annualized cost of restricting access to work areas is $88.33 per at-
risk crew member.
As specified in paragraph (g)(4) of the final standard, a competent
person must carry out the responsibilities of implementing the written
exposure control plan. As defined in the standard, "competent person"
means an individual who is capable of identifying existing and
foreseeable respirable crystalline silica hazards in the workplace and
who has authorization to take prompt corrective measures to eliminate
or minimize them, as well as has the knowledge and ability necessary to
fulfill the responsibilities set forth in paragraph (g) of the
standard. OSHA has utilized the competent person provision in other
construction standards, such as 1926.1127, Cadmium, and 1926.1101,
Asbestos, so the Agency expects that there is widespread familiarity
with both the concept and the responsibilities of competent person in
the construction sector. As in other OSHA construction rules, a major
purpose of the competent person provision in this final silica standard
is to identify who has the responsibility for inspections of the job
sites, materials, and equipment. Thus, OSHA expects that most employers
will have training programs in place to produce competent persons, and
the cost of training someone will only be a relatively small marginal
increase in the overall training cost. For that reason, the Agency
expects that many employees designated as competent persons will
undergo some training for the position. OSHA is estimating that each
competent person will, on average, undergo two hours of training--in
addition to the one hour of silica training estimated for all
construction employees. OSHA does not anticipate any additional costs
beyond training costs to be associated with the requirement that a
competent person implement the written exposure control plan.
While the competent person provision does not specify a training
requirement, the competent person is required to possess the knowledge
and skills to perform the functions required by the standard. For that
reason, the Agency expects that many employees designated as competent
persons will undergo some training for the position. OSHA estimates
that, on average, there will be 1 competent person for each establishment
with fewer than 20 employees, 5 competent persons for each
establishment with 20-499 employees, and 10 competent persons for each
establishment with 500 or more employees.
OSHA expects that competent persons will be trained by a
supervisor, presumably one who went through the process to become
familiar with the requirements of the respirable crystalline silica
standard, or by a combination of supervisory and/or technical staff
that are familiar with the operation of the engineering controls. While
the competent persons are not required to be supervisors and some of
the staff providing the training may not be supervisors, OSHA is using
a supervisor's wage to estimate the costs for time spent by both the
trainers and the trainees in order to provide the upper cost limit,
realizing that the cost for establishments who do not designate
supervisors as the competent person will be lower. OSHA estimated that
the total cost per establishment to train a competent person in
construction will range from $21 to $114 (see Chapter V in the FEA for
a full discussion of OSHA's analysis of costs for written exposure
control plans under the final standard).
8. Combined General Industry/Maritime Control, Respirator, and Program
Costs
Table VII-14 shows that the estimated combined costs for employers
in the general industry and maritime sectors to comply with the final
silica rule are approximately $370.8 million annually. These costs
include $238.1 million annually for engineering controls and $10.5
million annually for respirators to meet the final PEL of 50 [mu]g/
m\3\. The remaining $122.2 million annually are to meet the ancillary
provisions of the final rule. These ancillary annual costs consist of
$79.6 million for exposure monitoring; $29.7 million for medical
surveillance; $6.0 million for familiarization and training; $2.6
million for regulated areas; and $4.1 million for the written exposure
control plan.
Table V-B-1 in Appendix V-B in the FEA presents estimated
compliance costs by NAICS industry code and program element for small
business entities (as defined by the Small Business Act and the Small
Business Administration's implementing regulations; see 15 U.S.C. 632
and 13 CFR 121.201) in general industry and maritime, while Table V-B-2
in the FEA presents estimated compliance costs, by NAICS code and
program element, for very small entities (fewer than twenty employees)
in general industry and maritime.
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BILLING CODE 4510-26-C
9. Combined Construction Control, Respirator, and Program Costs
Table VII-15 summarizes the engineering control costs, respirator
costs, and program costs of the rule for the construction sector.
Annualized compliance costs in construction are expected to total
$659.0 million, of which $423.4 million are for engineering controls,
$22.4 million are for respirators, and $213.2 million are to meet the
ancillary provisions of the rule. These ancillary annual costs consist
of $16.5 million for exposure monitoring; $66.7 million for medical
surveillance; $89.9 million for familiarization and training; and
$40.1 million for the written exposure control plan.
Table V-B-1 in Appendix V-B in the FEA presents estimated
compliance costs by NAICS industry code and program element for small
entities (as defined by the Small Business Administration) in
construction, while Table V-B-2 in the FEA presents estimated
compliance costs, by NAICS code and program element, for very small
entities (fewer than twenty employees) in construction.
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BILLING CODE 4510-26-C
10. Total Cost Summary
As shown in Table VII-16, annualized compliance costs associated
with the rule are expected to total $1,030 million. Table VII-16 also
provides total annualized costs for general industry, maritime, and
construction separately, by major provision or program element included
in the rule. This table shows that engineering control costs represent
64 percent of the costs of the standard for all three affected industry
sectors: general industry, maritime, and construction. Considering
other leading cost categories, costs for exposure assessment and
medical surveillance represent, respectively, 30 percent and 15 percent
of the costs of the standard for general industry and maritime; costs
for training and familiarization and medical surveillance represent,
respectively, 14 percent and 10 percent of the costs of the standard
for construction.
While the costs presented here represent the Agency's best estimate
of the costs to industry of complying with the rule under static
conditions (that is, using existing technology and the current
deployment of workers), OSHA recognizes that actual costs could be
somewhat higher or lower, depending on the Agency's possible
overestimation or underestimation of various cost factors. In Chapter
VII of the FEA, OSHA provides a sensitivity analysis of its cost
estimates by modifying certain critical unit cost factors. Beyond this
sensitivity analysis, OSHA notes that its cost estimates do not reflect
the possibility that, in response to the rule, industry may find ways
to reduce compliance costs.
This could be achieved in three ways. First, in construction, 36
percent of the estimated costs of the rule (all costs except
engineering controls) vary directly with the number of workers exposed
to silica. However, as shown in Table III-5 in the FEA, more than five
times as many construction workers will be affected by the rule as will
the number of full-time-equivalent construction workers necessary to do
the work. This is because most construction workers currently doing
work involving silica exposure perform such tasks for only a portion of
their workday. In response to the rule, many employers are likely to
assign work so that fewer construction workers perform tasks involving
silica exposure; correspondingly, construction work involving silica
exposure will tend to become a full-time job for some construction
workers.\47\ Were this approach fully implemented in construction, the
actual cost of the rule would decline because employers would have to
comply with the ancillary provisions of the final rule for fewer
workers.\48\ However, these workers would be subject to the full
protections of the final rule.
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\47\ There are numerous instances of job reassignments and job
specialties arising in response to OSHA regulation. For example,
asbestos removal and confined space work in construction have become
activities performed by well-trained specialized employees, not
general laborers (whose only responsibility is to identify the
presence of asbestos or a confined space situation and then to
notify the appropriate specialist).
\48\ OSHA expects that such a structural change in construction
work assignments would not have a significant effect on the benefits
of the rule. As discussed in Chapter VII of this PEA, the estimated
benefits of the rule are relatively insensitive to changes in
average occupational tenure or how total silica exposure in an
industry is distributed among individual workers.
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Second, industry could demonstrate that certain construction
activities result in exposures below the action level under any
foreseeable conditions--in which case, workers engaged only in those
silica-generating activities would not be subject to the requirements
of the final rule. For example, an employer could make this
demonstration by using objective data developed for short-term,
intermittent tasks involving limited generation of silica dust. In
estimating the costs for this final rule, however, OSHA included all
costs, including ancillary costs as appropriate, associated with short-
term intermittent silica tasks.
Third, the costs presented here do not take into account the
possible development and dissemination of cost-reducing compliance
technology in response to the rule.\49\ One possible example is the
development of safe substitutes for silica sand in activities such as
abrasive blasting operations, repair and replacement of refractory
materials, foundry operations, and in the railroad transportation
industry. Another is expanded use of automated processes which would
allow workers to be isolated from the points of operation that involve
silica exposure (such as tasks between the furnace and the pouring
machine in foundries and at sand transfer stations in structural clay
production facilities). Yet another example is the further development
and use of bags with valves that seal effectively when filled, thereby
preventing product leakage and worker exposure (for example, in mineral
processing and concrete products industries). Probably the most
pervasive and significant technological advances, however, will likely
come from the integration of compliant control technology into standard
production equipment. Such advances would both increase the
effectiveness and reduce the costs of silica controls when compared to
retrofitted production equipment. Possible examples include local
exhaust ventilation (LEV) systems attached to portable tools used by
grinders and tuckpointers; enclosed operator cabs equipped with air
filtration and air conditioning in industries that mechanically
transfer silica or silica-containing materials; and machine-integrated
wet dust suppression systems used, for example, in road milling
operations.\50\
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\49\ Evidence of such technological responses to regulation
includes Ashford, Ayers, and Stone (1985)(Document ID 0536), OTA
(1995)(Document ID 0947), and OSHA's regulatory reviews of existing
standards under Sec. 610 of the Regulatory Flexibility Act ("610
lookback reviews"). On the other hand, supplemental evidence from
Harrington et al. (2000) [Harrington, Winston, Richard D.
Morgenstern and Peter Nelson. "On the Accuracy of Regulatory Cost
Estimates." Journal of Policy Analysis and Management, 19(2), 297-
322, 2000] finds that OSHA does not systematically overestimate
costs on a per-unit basis. Nevertheless, several examples of OSHA's
overestimation of costs reported in the article are due to
technological improvements.
\50\ A dramatic example from OSHA's 610 lookback review of its
1984 ethylene oxide (EtO) standard is the use of EtO as a sterilant.
OSHA estimated the costs of then existing add-on controls for EtO
sterilization, but in response to the standard, improved EtO
sterilizers with built-in controls were developed and widely
disseminated at about half the cost of the equipment with add-on
controls. (See OSHA, 2005.) Lower-cost EtO sterilizers with built-in
controls did not exist, and their development had not been predicted
by OSHA, at the time the final rule was published in 1984.
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OSHA has decided not to include in its analysis any possible cost-
reducing technological advances or worker specialization because the
technological and economic feasibility of the rule can easily be
demonstrated using existing technology and employment patterns.
However, OSHA believes that actual costs, which will incorporate any
future developments of this type, will likely be lower than those
estimated here.
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a. Costs Under Alternative PEL (100 [mu]g/m\3\) Scenario
Appendix V-C in the FEA presents, for analytical purposes, costs
for an alternative PEL of 100 [mu]g/m\3\. Total annualized compliance
costs under this alternative are $649.3 million. Table V-C-1 displays
costs for general industry, maritime, and construction by each program
element. Table V-C-2 shows total costs by NAICS industry code for all
affected general industry and maritime establishments, for business
entities in general industry and maritime defined as small by the Small
Business Administration, and for very small business entities in
general industry and maritime (those with fewer than twenty employees).
Table V-C-3 shows total costs by NAICS industry code for all affected
construction establishments, for business entities in construction
defined as small by the Small Business Administration, and for very
small business entities in construction (those with fewer than twenty
employees).
b. Costs Under Alternative Discount Rates
An appropriate discount rate \51\ is needed to reflect the timing
of costs after the rule takes effect and to allow conversion to an
equivalent steady stream of annualized costs.
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\51\ Here and elsewhere throughout the FEA, unless otherwise
noted, the term "discount rate" always refers to the real discount
rate--that is, the discount rate net of any inflationary effects.
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c. Alternative Discount Rates for Annualizing Costs
Following OMB (2003) guidelines (Document ID 1493), OSHA has
estimated the annualized costs of the rule using separate discount
rates of 3 percent and 7 percent. Consistent with the Agency's own
practices in recent proposed and final rules,\52\ OSHA has also
estimated, for benchmarking purposes, undiscounted costs--that is,
costs using a zero percent discount rate.
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\52\ See, for example, 71 FR 10099, the preamble for the final
hexavalent chromium rule.
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d. Summary of Annualized Costs Under Alternative Discount Rates
In addition to using a 3 percent discount rate in its main cost
analysis, OSHA estimated compliance costs, in Appendix V-D in the FEA,
using alternative discount rates of 7 percent and zero percent. Table
V-D-1 and V-D-2 in Appendix V-D present total costs at a 7 percent
discount rate for both (1) all employers by major industry category and
program element, and (2) affected employers by NAICS industry code and
employment size class (all establishments, small entities, and very
small entities). Tables V-D-3 and V-D-4 present the same breakdowns of
total costs estimated at a zero percent discount rate.
As shown in Appendix V-D, the choice of discount rate has only a
minor effect on total annualized compliance costs, with annualized
costs increasing from 1,030 million using a three percent discount rate
to $1,056 million using a seven percent discount rate, and decreasing
to $1,012 million using a zero percent discount rate.
e. Time Distribution of Costs
OSHA analyzed the stream of (unannualized) compliance costs, by
industry sector, for the first ten years after the rule takes effect
under the simplifying assumption that no provisions of the rule are
phased in. As shown in Table VII-16, total compliance costs are
expected to peak in Year 1 at more than $1.5 billion. After that, costs
are estimated to decline and remain relatively flat after the initial
set of capital and program start-up expenditures has been incurred.
Costs are projected to rise somewhat in Year 4 as a result of the
triennial medical examinations and in Year 6 because of a second cycle
of control equipment purchases in construction for short-term,
intermittent work. Thereafter there are fluctuations but no strong
trend. OSHA notes that the differences between costs for Year 1 and
costs for subsequent years are narrower than might otherwise be the
case due to (1) the expectation that, in the construction sector, a
large percentage of control equipment will be rented (leading to
constant annual expenses for the rented control equipment) rather than
purchased as capital in Year 1; and (2) the expectation that the only
engineering controls needed in the maritime sector will be wet methods,
which do not require capital expenditures. On the other hand, the
ancillary provisions are expected to have a relatively large number of
initial costs (mainly labor rather than capital) in Year 1.
F. Economic Feasibility Analysis and Regulatory Flexibility
Determination
Chapter VI of the FEA presents OSHA's analysis of the economic
impacts of its final silica rule on affected employers in general
industry, maritime, and construction. The discussion below summarizes
the findings in that chapter.
As a first step, the Agency explains its approach for achieving the
two major objectives of its economic impact analysis: (1) To establish
whether the final rule is economically feasible for all affected
industries, and (2) to determine if the Agency can certify that the
final rule will not have a significant economic impact on a substantial
number of small entities. Next, this approach is applied to industries
with affected employers in general industry and maritime and then to
industries with affected employers in construction. Finally, OSHA
examines the employment effects of the silica rule. This includes a
review of estimates of employment effects that commenters provided and
a summary of a report prepared for the Agency by Inforum--a not-for-
profit corporation (based at the University of Maryland) specializing
in the design and application of macroeconomic models of the United
States (and other countries)--to estimate the industry and aggregate
employment effects of the silica rule.
Many commenters questioned OSHA's preliminary conclusions
concerning economic feasibility, but did so for reasons that OSHA has
responded to in previous chapters.
A variety of commenters raised issues concerning industries with
possible silica exposure that were not covered in the Preliminary
Economic and Initial Regulatory Feasibility Analysis (PEA). A full
discussion of these comments and of industries added is provided in the
FEA.
Many commenters questioned why OSHA used no data after 2006 (see
comments by the Brick Industry Association (BIA) (Document ID 2300, p.
5), the American Fuel & Petrochemical Manufacturers (AFPM) (Document ID
2350, p. 6), the Belden Brick Company (Document ID 3260, p. 3),
Basalite Concrete Products, LLC (Document ID 2083, p. 1), SBG
Consulting (Document ID 2222, p. 1), Acme Brick (Document ID 2182, p.
4), Erie Bronze & Aluminum (Document ID 1780, p. 1), Calstone (Document
ID 3391, p. 2), the Chamber of Commerce (Document ID 1782, p. 1), the
Mason Contractors Association of America (MCAA) (Document ID 1767, p.
2), Scango Consulting LLC d.b.a. Capitol Hardscapes (Document ID 2241,
p. 3), the National Concrete Masonry Association (NCMA) (Document ID
3585, p. 2944), the American Road and Transportation Builders
Association (ARTBA) (Document ID 2245, p. 4), and the Construction
Industry Safety Coalition (CISC) (Document ID 4217, Attachment 1, pp. 4
and 49-52)). As discussed in Chapter III of the FEA, OSHA is using
revenue data from 2012 and profit data averaged across the years 2000
through 2012. The revenue data from 2012 represent a reasonable choice
because this year was neither a peak growth year nor a recession year
and was the most up-to-date data available at the time this analysis
was developed. The range of years for profits assures the use of profit
rates from throughout the business cycle--including two recessions and
two sustained growth periods.
One commenter questioned OSHA's sources and methodology for
estimating revenues (Document ID 2308, Attachment 9, pp. 7-8 and 14-
16). This commenter questioned the methodology used to update revenue
estimates between Economic Census years. This is no longer an issue as
OSHA is using 2012 Economic Census data and using 2012 as the base year
for the analysis. Therefore, there is no need for a methodology to
update Economic Census revenues.
OSHA also received criticism on the choice of the data source and
the methodology for estimating profits of the construction industry.
These include comments from the National Association of Home Builders
(NAHB) and the CISC (Document ID 2296, Attachment 1, pp. 20-22; 2308,
Attachment 9, pp. 7-12).
Stuart Sessions, submitting on behalf of the CISC, criticized OSHA
for using the Internal Revenue Service's (IRS) Corporation Source Book
(CSB) as the source for industry profits since those data are only
presented at the four-digit NAICS level instead of the five- or six-
digit NAICS level. Mr. Sessions recommended that OSHA use an
alternative data source for profit data and recommended Bizminer or RMA
(Document ID 4231, Attachment 1, pp.12-13). OSHA investigated these
sources and determined that these data were private data sources and
that their publishers would not allow the data to be made publicly
available. These other sources of profit data also suffered from the
disadvantage of not representing adequate and random samples of the
affected industries. A further discussion on this issue appears in
Chapter III of the FEA.
In the PEA, OSHA used IRS data to calculate profit rates as the
ratio of net income to total receipts (with the numerator including
only firms with positive net income and the denominator including firms
with and without net income) by NAICS industry. In response to comments
criticizing this ratio as an inappropriate method to calculate industry
profitability (Document ID 2308, Attachment 9, pp. 11-12; 4209, pp.
115-116), OSHA has revised the way that estimated profits are
calculated. In the FEA, OSHA calculates profit rates using the method
recommended by Mr. Sessions, which is discussed more fully in Chapter
III. This method includes unprofitable firms and divides the "net
income" from all firms (profitable and unprofitable) by total receipts
from all firms (profitable and unprofitable), resulting in somewhat
lower profit rates.
Similarly, Mr. Sessions criticized OSHA for using data that he
believed were at a level that was too aggregated to show economic
impacts of the costs of the rule accurately (Document ID 2319,
Attachment 1, p. 71). The Portland Cement Association likewise
disagreed with OSHA's presentation of costs as averages across
industries. It said that "a more focused explanation of individual
plant and facility costs is relevant to those industries with
significant compliance responsibilities" (Document ID 2284, p. 6).
OSHA's data sources for profile data are presented in Chapter III of
the FEA. In general, OSHA has disaggregated industries to the extent
that the source data will allow.
The most common criticism of OSHA's preliminary conclusions on
economic feasibility was that the conclusions were based on costs that
were underestimated or inaccurate (e.g., Document ID 2023, p. 1; 2299,
p. 15; 2379, Attachment 3, pp. 2 and 10; 2388, pp. 2 and 10; 2296,
Attachment 1, p. 17; 2116, Attachment 1, p. 22; and 3378, Attachment
2). For example, Wayne D'Angelo of the American Petroleum Institute
(API) and the Independent Petroleum Association of America (IPAA) (API/
IPAA or "the Associations") critiqued OSHA's feasibility analysis for
the hydraulic fracturing industry, stating that OSHA had not met its
obligations due to inaccurate cost data and an industry profile that,
they asserted, did not "reasonably represent the typical firms in the
various segments of the industry, given varying operations, exposure
levels, and processes" (Document ID 2301, Attachment 1, pp. 62-63).
OSHA responded to comments on its preliminary cost estimates in
Chapter V of the FEA. In the aggregate, OSHA increased its cost
estimate by approximately 46 percent, in part, as a result of changes
in cost estimates made in response to comments and, in part, as a
result of changes in the rule.
Some commenters argued that OSHA had not adequately considered the
possibility that smaller establishments might have higher costs or that
the costs have a greater impact on small businesses (Document ID 4231,
Attachment 1, p. 11; 2379, Attachment 2, p. 7; 3582, Tr. 2107-2109;
2203, p. 1; 2351, p. 8; 3433, p. 9; 3580, Tr. 1398). As discussed in
Chapter V, OSHA has made a number of changes to the costs analysis to
reflect higher costs for small establishments.
1. Analytic Approach
a. Economic Feasibility
The Court of Appeals for the D.C. Circuit has long held that OSHA
standards are economically feasible so long as their costs do not
threaten the existence of, or cause massive economic dislocations
within, a particular industry or alter the competitive structure of
that industry. American Iron and Steel Institute. v. OSHA, 939 F.2d
975, 980 (D.C. Cir. 1991); United Steelworkers of America, AFL-CIO-CLC
v. Marshall, 647 F.2d 1189, 1265 (D.C. Cir. 1980); Industrial Union
Department
v. Hodgson, 499 F.2d 467, 478 (D.C. Cir. 1974).
In practice, the economic burden of an OSHA standard on an
industry--and whether the standard is economically feasible for that
industry--depends on the magnitude of compliance costs incurred by
establishments in that industry and the extent to which they are able
to pass those costs on to their customers. That, in turn, depends, to a
significant degree, on the price elasticity of demand for the products
sold by establishments in that industry.
The price elasticity of demand refers to the relationship between
the price charged for a product and the demand for that product: The
more elastic the relationship, the less an establishment's compliance
costs can be passed through to customers in the form of a price
increase and the more it has to absorb compliance costs in the form of
reduced profits. When demand is inelastic, establishments can recover
most of the variable costs of compliance (i.e., costs that are highly
correlated with the amount of output) by raising the prices they
charge; under this scenario, if costs are variable rather than fixed,
profit rates are largely unchanged and the industry remains largely
unaffected. Any impacts are primarily on those customers using the
relevant product. On the other hand, when demand is elastic,
establishments cannot recover all compliance costs simply by passing
the cost increase through in the form of a price increase; instead,
they must absorb some of the increase from their profits. Commonly,
this will mean reductions both in the quantity of goods and services
produced and in total profits, though the profit rate may remain
unchanged. Other things being equal, higher fixed costs mean that the
optimal scale of the typical establishment will be larger than it would
be if fixed costs were lower. This in turn means that, where there are
higher fixed costs, there will be fewer plants for the same level of
production. Whether an increase in fixed costs results in closures of
existing plants depends on several factors. If demand regularly
increases (such as due to economic growth) or the industry regularly
experiences plant closures, the optimal scale may be arrived at by
reduced entry rather than premature closures. If plants are not part of
a simple homogeneous market, it may not be possible to shift the scale
of production. For example, if a plant provides foundry products to
others in the same city, it may not be able to readily expand its scale
of production. In general, "[w]hen an industry is subjected to a
higher cost, it does not simply swallow it; it raises its price and
reduces its output, and in this way shifts a part of the cost to its
consumers and a part to its suppliers," in the words of the court in
American Dental Association v. Secretary of Labor (984 F.2d 823, 829
(7th Cir. 1993)).
The court's summary is in accord with microeconomic theory. In the
long run, firms can remain in business only if their profits are
adequate to provide a return on investment that ensures that investment
in the industry will continue. As technology and costs change, however,
the long-run demand for some products naturally increases and the long-
run demand for other products naturally decreases. In the face of
additional compliance costs (or other external costs), firms that
otherwise have a profitable line of business may have to increase
prices to stay viable. Increases in prices typically result in reduced
quantity demanded, but rarely eliminate all demand for the product.
Whether this decrease in the total production of goods and services
results in smaller output for each establishment within the industry,
or the closure of some plants within the industry; a reduced number of
new establishments entering the industry; or a combination of the
three, is dependent on the cost and profit structure of individual
firms within the industry.
If demand is perfectly inelastic (i.e., the price elasticity of
demand is zero), then the impact of compliance costs that are 1 percent
of revenues for each firm in the industry would result in a 1 percent
increase in the price of the product, with the quantity demanded
constant. (This outcome would hold in the long run, regardless of type
of costs, but in the short run would hold with certainty only if
compliance costs are strictly variable.) Such a scenario represents an
extreme case, but might be observed in situations in which there were
few if any substitutes for the product in question, or if the products
of the affected sector account for only a very small portion of the
revenue or income of its customers. Under this scenario, both profits
and output of the industry would be unaffected, but customers would be
worse off.
If the demand is perfectly elastic (i.e., the price elasticity of
demand is infinitely large), then no increase in price is possible and
before-tax profits would be reduced by an amount equal to the costs of
compliance (net of any cost savings--such as reduced workers'
compensation insurance premiums--resulting from the final standard) if
the industry attempted to maintain production at the same level. Under
this scenario, if the costs of compliance are such a large percentage
of profits that some or all plants in the industry could no longer
operate with the hope of an adequate return on investment, then some or
all of the firms would close. Similarly, if compliance costs are fixed,
such costs may result in premature closures or reduced entry into the
market in some circumstances.
A commonly discussed intermediate case would be a price elasticity
of demand of one.\53\ In this scenario, if the costs of compliance
amount to 1 percent of revenues, then production would decline by 1
percent and prices would rise by 1 percent. (As before, this outcome
would hold in the long run, regardless of type of costs, but in the
short run would hold with certainty only if compliance costs are
variable.) Under this scenario, and if marginal costs of the regulation
fall proportionally with output, then industry revenues would remain
the same, with somewhat lower production, but with similar profit
rates. Customers would, however, receive less of the product for their
(same) expenditures, and firms would have lower total profits; this, as
the court described in Am. Dental Ass'n v. Sec'y of Labor, 984 F.2d 823
(7th Cir. 1993), is the more typical case.
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\53\ Here and throughout this section, the price elasticity of
demand is reported as an abosulte value.
---------------------------------------------------------------------------
A decline in output as a result of an increase in price may occur
in a variety of ways: Individual establishments could each reduce their
levels of production; some marginal plants could close; or, in the case
of an industry with high turnover of establishments, new entry may be
delayed until demand equals supply. In many cases a decrease in overall
output for an industry will be a combination of all three kinds of
reductions. Which possibility is most likely depends on the rate of
turnover in the industry and on the form that the costs of the
regulation take.
When turnover in an industry is high, or an industry is expanding
rapidly, then the key issue is the long run costs as determined by the
cost of entry into the industry. For example, if there is annual
turnover in an industry of ten percent per year, and a price elasticity
of one, then a single year without new entry would result in a price
rise of ten percent. Such a rise would be more than enough to
compensate existing employers for a cost increase of one percent of
revenues. If the costs are variable costs (i.e., costs that vary with
the level of production at a facility), then economic theory suggests
that any reductions in output will take the form of reductions in output
at each affected facility, with few, if any, plant closures. If the
costs of a regulation primarily take the form of fixed costs
(i.e., costs that do not vary with the level of production at a facility),
and assuming perfect competition, then reductions in overall output
are more likely to can only take the form of plant closures or delays
in new entry. Most of the costs of this regulation, as estimated in
Chapter V of the FEA, are variable costs. Almost all of the major costs
of program elements, such as medical surveillance and training, will
vary in proportion to the number of employees (which is a rough proxy
for the amount of production). Exposure monitoring costs will vary
with the number of employees, but do have some economies of scale
to the extent that a larger firm need only conduct representative
sampling rather than sample every employee. The costs of engineering
controls in construction also vary by level of production because
almost all necessary equipment can readily be rented and the
productivity costs of using some of these controls vary proportionally
to the level of production. Finally, the costs of operating engineering
controls in general industry (the majority of the annualized costs of
engineering controls are in general industry) vary by the number of
hours the establishment works, and thus vary by the level of production
and are not fixed costs in the strictest sense.
This leaves two kinds of costs that are, in some sense, fixed
costs--capital costs of engineering controls in general industry and
certain initial costs that new entrants to the industry will not have
to bear.
Fixed costs in the form of capital costs of engineering controls in
general industry and maritime due to this standard are relatively small
as compared to the total costs, representing less than 21 percent of
total annualized costs and approximately $1,019 per year per affected
establishment in general industry.
There are some initial fixed costs in the sense that they might
only be borne by firms in the industry today. For example, costs for
general training not currently required and initial costs of medical
surveillance may not be borne by establishments new to the industry to
the extent they can hire from a workforce that may have already had
this training and/or initial medical surveillance. An initial thorough
facility cleaning is not a cost a new establishment would need to bear.
These costs will disappear after the initial year of the standard and
thus would be difficult to pass on. These costs, however, represent
less than two percent of total costs and less than $58 per affected
establishment. These initial fixed costs that may be borne by firms in
the affected industries today, together with capital costs, give a
total fixed cost of approximately 22 percent of total annual costs.
Because the remaining three-fourths of the total annual costs are
variable, OSHA expects it is somewhat more likely that reductions in
industry output resulting from the increase in costs associated with
this rule will be met by reductions in output at each affected facility
rather than as a result of plant closures or reduced new entry.
However, closures of some marginal plants or poorly performing
facilities are always possible. To determine whether a rule is
economically feasible, OSHA begins with two screening tests to consider
minimum threshold effects of the rule under two extreme cases: (1) All
costs are passed through to customers in the form of higher prices
(consistent with a price elasticity of demand of zero), and (2) all
costs are absorbed by the firm in the form of reduced profits
(consistent with an infinite price elasticity of demand).
In the former case, the immediate impact of the rule would be
observed in increased industry revenues. While there is no hard and
fast rule, in the absence of evidence to the contrary, OSHA generally
considers a standard to be economically feasible for an industry when
the annualized costs of compliance are less than a threshold level of
one percent of annual revenues. Retrospective studies of previous OSHA
regulations have shown that potential impacts of such a small magnitude
are unlikely to eliminate an industry or significantly alter its
competitive structure,\54\ particularly since most industries have at
least some ability to raise prices to reflect increased costs and, as
shown in the FEA, normal price variations for products typically exceed
three percent a year.\55\ Of course, OSHA recognizes that even when
costs are within this range, there could be unusual circumstances
requiring further analysis.
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\54\ See OSHA's Web page, http://www.osha.gov/dea/lookback.html#Completed, for a link to all completed OSHA lookback
reviews.
\55\ See, for example, Table VI-3 and the accompanying text
presented in Chapter VI of the FEA.
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In the latter case, the immediate impact of the rule would be
observed in reduced industry profits. OSHA uses the ratio of annualized
costs to annual profits as a second check on economic feasibility.
Again, while there is no hard and fast rule, in the absence of evidence
to the contrary, OSHA generally considers a standard to be economically
feasible for an industry when the annualized costs of compliance are
less than a threshold level of ten percent of annual profits. In the
context of economic feasibility, the Agency believes this threshold
level to be fairly modest, given that normal year-to-year variations in
profit rates in an industry can exceed 40 percent or more.\56\ OSHA's
choice of a threshold level of ten percent of annual profits is low
enough that even if, in a hypothetical worst case, all compliance costs
were upfront costs, then upfront costs would still equal 88.5 percent
of profits using a three percent discount rate (see section Normal
Year-to-Year Variations in Prices and Profit Rates below) and thus
would be affordable from profits alone without the need for an employer
to resort to credit markets. If the threshold level were first-year
costs of ten percent of annual profits, firms could even more easily
expect to cover first-year costs at the threshold level out of current
profits without having to access capital (including credit markets)
markets and otherwise being threatened with short-term insolvency.
---------------------------------------------------------------------------
\56\ See, for example, Table VI-5 and the accompanying text
presented in Chapter VI of the FEA.
---------------------------------------------------------------------------
In general, it is usually the case that firms would be able to pass
on some or all of the costs of the rule to their customers in the form
of higher prices. OSHA therefore will tend to give much more weight to
the ratio of industry costs to industry revenues than to the ratio of
industry costs to industry profits. However, if costs exceed either the
threshold percentage of revenue or the threshold percentage of profits
for an industry, or if there is other evidence of a threat to the
viability of an industry because of the standard, OSHA will examine the
effect of the rule on that industry more closely. Such an examination
would include market factors specific to the industry, such as normal
variations in prices and profits, international trade and foreign
competition, and any special circumstances, such as close domestic
substitutes of equal cost, which might make the industry particularly
vulnerable to a regulatory cost increase.
The preceding discussion focused on the economic viability of the
affected industries in their entirety. However, even if OSHA found that
a final standard did not threaten the survival of affected industries,
there is still the question of whether the industries' competitive
structure would be significantly altered. For example, if the
annualized costs of an OSHA standard were equal to ten percent of an
industry's annual profits, and the price elasticity of demand for the
products in that industry were equal to one, then OSHA would not expect
the industry to go out of business. However, if the increase in costs
were such that most or all small firms in that industry would have to
close, it could reasonably be concluded that the competitive structure
of the industry had been altered. For this reason, OSHA also examines
the differential costs by size of establishment.
Public Comments on OSHA's Approach to Economic Feasibility
Some commenters were concerned that reductions of profits of less
than ten percent could still represent major losses to an employer. For
example, one commenter said:
The proposed rule states that in no cases will the amount of
revenue or profits exceed 8.8% noting that this number is easily
passed to consumers in the form of increased product and service
costs. For a rule as specific and slight as one affecting only
silica dust inhalation, a reduction in profits by 8.8% should give
the government pause (Document ID 2189, p. 1).
Another commenter expressed similar concerns about a reduction in
profits of 4.8 percent (Document ID 1882, Attachment 1, p. 2). OSHA is
not dismissive of losses in profits of less than ten percent. However,
such losses need to be weighed against the OSH Act's objectives of
occupational safety and health. For purposes of assessing economic
feasibility, OSHA needs to be concerned with major dislocating effects
on entire industries, which will not be the result of relatively small
changes in profits. Further, as will be discussed below, these costs
can likely be passed on to consumers.
API/IPAA, while disagreeing with OSHA's cost estimates,
acknowledged that OSHA's use of the rules of thumb of ten percent of
profits or one percent of revenues has been upheld in court (Document
ID 2301, Attachment 1, pp. 62-63).
Some commenters were also concerned that OSHA's screening analysis
methodology did not give adequate consideration to upfront costs
(Document ID 2379, Attachment 3, p. 39; 2119, Attachment 3, p. 22). As
will be discussed below, OSHA's choice of a threshold level of ten
percent of annual profits is low enough that even if, in a hypothetical
worst case, all compliance costs were upfront costs, then upfront costs
would still equal 88.5 percent of profits and thus would be affordable
from profits alone without needing to resort to credit markets. (If the
cost exceeds 100 percent of profits then the company would have to
borrow to pay the balance. Otherwise the firm will not have to borrow
but could finance the cost internally.)
While not specifically addressed to the issue of the screening
analysis, Mr. Sessions provided some estimates of how various
percentage cost increases might interact with demand and supply
elasticities to produce estimates of declines in total industry output.
His estimates show that the decline in total revenues (and, in this
situation, total production) associated with increased costs of one
percent of revenues ranges from zero to 0.83 percent of total
production (the range depending on the elasticities of supply and
demand, with the highest impact on total revenues associated with a
very unlikely price elasticity of ten) (Document ID 4231, Attachment 1,
p. 31). Even the largest decline in revenues would result in only a
0.83 percent decline in revenues, which would not represent a major
dislocation of any affected industry. While OSHA does not necessarily
endorse this particular approach to calculating changes in total
revenue for given percentage change in costs, the calculation confirms
OSHA's general view that increases of less than one percent of costs do
not render a standard economically infeasible.
After reviewing these comments, OSHA has decided to retain its
screening test of ten percent of profits and one percent of revenues as
levels below which significant dislocation of an industry is extremely
unlikely.
b. Regulatory Flexibility Screening Analysis
The Regulatory Flexibility Act (RFA), Public Law 96-354, 94 Stat.
1164 (codified at 5 U.S.C. 601), requires Federal agencies to consider
the economic impact that a final rulemaking will have on small
entities. The RFA states that whenever an agency "promulgates a final
rule under section 553 of this title, after being required by that
section or any other law to publish a general notice of proposed
rulemaking, the agency shall prepare a final regulatory flexibility
analysis" (FRFA). 5 U.S.C. 604(a). Pursuant to section 605(b), in lieu
of an FRFA, the head of an agency may certify that the final rule will
not have a significant economic impact on a substantial number of small
entities. A certification must be supported by a factual basis. If the
head of an agency makes a certification, the agency shall publish such
certification in the Federal Register at the time of publication of
general notice of final rulemaking or at the time of publication of the
final rule. 5 U.S.C. 605(b). Thus, if OSHA cannot issue the required
certification, it must prepare a FRFA.
OSHA makes its determination about whether it can issue the
required certification by applying screening tests to consider minimum
threshold effects of the rule on small entities. These screening tests
are similar in concept to those OSHA described above to identify
minimum threshold effects for the purposes of demonstrating economic
feasibility and are discussed below.
There are, however, two differences. First, for each affected
industry, the screening tests are applied, not to all establishments,
but to small entities (defined as "small business concerns" by the
Small Business Administration (SBA)) and also to very small entities
(as defined by OSHA as small businesses with fewer than 20 employees).
Second, although OSHA's regulatory flexibility screening test for
revenues also uses a minimum threshold level of annualized costs equal
to one percent of annual revenues, OSHA has established a minimum
threshold level of annualized costs equal to five percent of annual
profits for the average small entity or very small entity (rather than
the ten percent threshold applicable for general economic feasibility
screening). The Agency has chosen a lower minimum threshold level for
the profitability screening analysis and has applied its screening
tests to both small entities and very small entities in order to ensure
that certification will be made, and an FRFA will not be prepared, only
if OSHA can be highly confident that a final rule will not have a
significant economic impact on a substantial number of small entities
or very small entities in any affected industry.
OSHA has prepared separate regulatory flexibility screening tests
for general industry, maritime, and construction.
2. Impacts in General Industry and Maritime
In this section, OSHA will determine whether (1) the rule is
economically feasible for all affected industries in general industry
and maritime, and (2) the Agency can certify that the rule will not
have a significant economic impact on a substantial number of small
entities in general industry and maritime. OSHA concludes that the rule
is economically feasible, but the Agency is unable to certify that it
will not have a significant economic impact on a substantial number of
small entities.
a. Economic Feasibility Screening Analysis: All Establishments
Earlier chapters of the FEA identified the general industry and
maritime sectors potentially affected by the final rule; presented
summary profile data for affected industries, including the number of
affected entities and establishments, the number of at-risk workers,
and the average revenue for affected entities and establishments; and
developed estimates, by affected industry, of the costs of the rule.
The economic impacts of the final rule on general industry and maritime
are driven, in part, by the costs of additional dust control measures,
respirators, and silica program activities needed to comply with the
rule.
To determine whether the final rule's projected costs of compliance
would threaten the economic viability of affected industries; OSHA
first compared, for each affected industry, annualized compliance costs
to annual revenues and profits per (average) affected establishment.
The results for all affected establishments in all affected industries
in general industry and maritime are presented in Table VII-18, using
annualized costs per establishment for the PEL of 50 [mu]g/m\3\. Shown
in the table for each affected industry are total annualized costs, the
total number of affected establishments, annualized costs per affected
establishment, annual revenues per establishment, the profit rate,
annual profits per establishment, annualized compliance costs as a
percentage of annual revenues, and annualized compliance costs as a
percentage of annual profits.
The annualized costs per affected establishment for each affected
industry were calculated by distributing the industry-level
(incremental) annualized compliance costs among all affected
establishments in the industry, where annualized compliance costs
reflect a three percent discount rate. The annualized cost of the rule
for the average establishment in all of general industry and maritime
is estimated to be $4,939 in 2012 dollars. It is clear from Table VII-
18 that the estimates of the annualized costs per affected
establishment in general industry and maritime vary widely from
industry to industry. These estimates range from $220,558 for NAICS
213112 (Support Activities for Oil and Gas Operations) and $57,403 for
NAICS 331511 (Iron Foundries) to $304 for NAICS 621210 (Offices of
Dentists) and $377 for NAICS 324121 (Asphalt Paving Mixture and Block
Manufacturing).
Table VII-18 also shows that, within the general industry and
maritime sectors, there are no industries in which the annualized costs
of the final rule exceed 1 percent of annual revenues and there are
eight industries in which the annualized costs of the rule exceed ten
percent of annual profits and none where annualized costs exceed one
percent of annual revenues. NAICS 213112 (Support Activities for Oil
and Gas Operations), has the highest cost impact as a percentage of
revenues, of 0.56 percent. NAICS 327120 (Clay Building Material and
Refractories Manufacturing) has the highest cost impact as a percentage
of profits, of 31.08 percent. For all affected establishments in
general industry and maritime, the estimated annualized cost of the
rule is, on average, equal to 0.06 percent of annual revenue and 2.43
percent of annual profits.
The industries with costs that exceed ten percent of profits are:
NAICS 327110--Pottery, Ceramics, and Plumbing Fixture Manufacturing, 31
percent; NAICS 327120--Clay Building Material and Refractories
Manufacturing, 31 percent; NAICS 327991--Cut Stone and Stone Product
Manufacturing, 24 percent; NAICS 327390--Other Concrete Product
Manufacturing, 17 percent; NAICS 327999--All Other Miscellaneous
Nonmetallic Mineral Product Manufacturing, 16 percent; NAICS 327332--
Concrete Pipe Manufacturing, 13 percent; NAICS 327331 Concrete Block
and Brick Manufacturing, 13 percent; and NAICS 327320 Ready-Mix
Concrete Manufacturing, 10 percent.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
b. Normal Year-to-Year Variations in Prices and Profit Rates
The United States has a dynamic and constantly changing economy in
which an annual percentage changes in industry revenues or prices of
one percent or more is common. Examples of year-to-year changes in an
industry that could cause such variations in revenues or prices include
increases in fuel, material, real estate, or other costs; tax increases;
and shifts in demand.
Methodology
To demonstrate the normal year-to-year variation in prices for all
the manufacturers in general industry and maritime affected by the
rule, OSHA developed in the FEA year-to-year producer price indices and
year-to-year percentage changes in producer prices, by industry, for
the years 2004 through 2014. As shown in Table VI-3 in the FEA, for the
combined affected manufacturing industries in general industry and
maritime over the 12-year period, the average change in producer prices
was 2.7 percent a year. For the industries in general industry and
maritime with the largest estimated potential annual cost impact as a
percentage of revenue--NAICS 213112--Support Activities for Oil and Gas
Operations, 0.56 percent; and NAICS 327991--Cut Stone and Stone Product
Manufacturing, 0.42 percent--the average annual changes in producer
prices in these industries over the 12-year period were, respectively,
3.8 percent, and 0.5 percent.
Based on these data, it is clear that the potential cost impacts of
the final rule in general industry and maritime are all well within
normal year-to-year variations in prices in those industries. The
maximum cost impact of the rule as a percentage of revenue in any
affected industry is 0.56 percent, while the average annual change in
producer prices for affected industries was 2.7 percent for the period
2004 through 2014 (changed from 1998 to 2009 in the PEA). Furthermore,
even a casual examination of Table VI-3 of the FEA reveals that annual
changes in producer prices in excess of five or even ten percent are
possible without threatening an industry's economic viability. Thus,
OSHA concludes that the potential price impacts of the final rule would
not threaten the economic viability of any industries in general
industry and maritime.
Changes in profit rates are also subject to the dynamics of the
U.S. economy. A recession, a downturn in a particular industry, foreign
competition, or the increased competitiveness of producers of close
domestic substitutes are all easily capable of causing a decline in
profit rates in an industry of well in excess of ten percent in one
year or for several years in succession.
To demonstrate the normal year-to-year variation in profit rates
for all the manufacturers in general industry and maritime affected by
the rule, OSHA in the FEA developed Table VI-4 and Table VI-5, which
show, respectively, year-to-year profit rates and year-to-year
percentage changes in profit rates, by industry, for the years 2000
through 2012. For the combined affected manufacturing industries in
general industry and maritime over the thirteen-year period, OSHA
calculated an average change in profit rates of 138.5 percent a year
(average for all industries calculated from the per-NAICS averages
shown in Table VI-5 in the FEA). For the industries in general industry
and maritime with the largest estimated potential annual cost impacts
as a percentage of profit--NAICS 327120--Clay Building Material and
Refractories Manufacturing, 31 percent; NAICS 327110--Pottery,
Ceramics, and Plumbing Fixture Manufacturing, 31 percent; and NAICS
327991--Cut Stone and Stone Product Manufacturing, 24 percent--the
average annual percentage changes in profit rates in these industries
over the 13-year period were, respectively, 951 percent, 951 percent,
and 113 percent.
One complicating factor is that the annualized costs of the rule,
if absorbed in lost profits, would involve not just a temporary loss of
profits but a longer term negative effect on profits relative to the
baseline. To address this issue, the Agency compared the effect of a
longer term reduction in profits to much larger reductions in profits
but over shorter periods. Assuming a three-percent discount rate, the
Agency determined a ten percent decline in profit rates relative to the
original baseline, which remains constant at that lower level over a
ten-year period, would be equivalent to: \57\
---------------------------------------------------------------------------
\57\ Note that the reduction in profits rates over time, as a
result of the rule, is being measured here relative to the baseline.
If the reduction in profit rates were made relative to the previous
year, as is done in Table VI-5 in the FEA, then there would be only
a one-time reduction in the profit rate in year one as a result of
the rule, after which the profit rate would reach a new (lower)
level but would not change from year to year.
---------------------------------------------------------------------------
An 88.5 percent decline in profit rates for one year;
a 44.5 percent decline in profit rates that remains
constant at the lower level for two years; or
a 30 percent decline in profit rates that remains constant
at the lower level for three years.\58\
---------------------------------------------------------------------------
\58\ Assuming a seven-percent discount rate, a ten-percent
decline in profit rates over the ten-year annualization period would
be equivalent to: A 75-percent decline in profit rates for one year;
a 39-percent decline in profit rates that remains constant at the
lower level for two years; or a 27-percent decline in profit rates
that remains constant at the lower level for three years.
---------------------------------------------------------------------------
An examination of Table VI-5, for the thirteen year period from
2000 to 2012, clearly shows that short-run changes in average industry
profit rates of the above magnitudes have occurred on numerous
occasions in general industry and maritime, without threatening the
economic viability of the affected industries. For this reason, OSHA is
confident that potential profit rate impacts of ten percent or less as
a result of the rule would not threaten the economic viability of the
affected industries in general industry and maritime.
A longer-term loss of profits in excess of ten percent a year could
be more problematic for some affected industries and might conceivably,
under sufficiently adverse circumstances, threaten an industry's
economic viability. In OSHA's view, however, affected industries would
generally be able to pass on most or all of the costs of the final rule
in the form of higher prices rather than bear the costs of the final
rule in reduced profits. In other words, the demand for the goods and
services produced by affected industries in general industry and
maritime do not appear to be perfectly elastic or close to it. While
there are substitutes for these products, there are no perfect
substitutes that would lead the price elasticity to be extremely high.
As a result, the demand for quantities of brick and structural clay,
vitreous china, ceramic wall and floor tile, other structural clay
products (such as clay sewer pipe), and the various other products
manufactured by affected industries would not significantly contract in
response to a 0.48 percent (or lower) price increase for these
products. It is of course possible that such price changes will result
in some reduction in output, and the reduction in output might be met
through the closure of a small percentage of the plants in the
industry. However, the only realistic circumstance under which an
entire industry would be significantly affected by small price
increases would be the availability in the market of a very close or
perfect substitute product not subject to OSHA regulation. The classic
example, in theory, would be foreign competition. In the following
discussion OSHA examines the threat of foreign competition for affected
U.S. establishments in general industry and maritime and concludes that
it is unlikely to threaten the viability of any affected industry.
Public Comments on Year-to-Year Variations in Prices and Profit Rates
The American Chemistry Council (ACC) stated, with respect to a
similar analysis in the PEA, that short-term volatility within an
industry sector is of little value in projecting what will
happen when a new regulation resets the baseline for profits and
revenue because OSHA is comparing short-term changes to long-term
changes (Document ID 2307, Attachment 2, p. 196). Another commenter
made the similar point that year-to-year fluctuations cannot be
compared to long-term changes (Document ID 2308, Attachment 9, p. 7).
OSHA first examines the issue of changes in prices over time. Such
changes, on the whole, represent pass through of changes in costs,
since profits are not continually rising. These changes in costs are
not "fluctuations" with upward and downward shifts in prices. For
almost all industries these changes in costs are continuing upward
shifts that average each year much larger changes than the maximum
price change any industry will need to incur in order to comply with
the silica rule.
For variations in profits, these are indeed fluctuations and
profits do indeed both rise and fall. However, if, as the commenters
argue only long-term average profits matter, then we could reach the
very counterintuitive result that there should be no excess plant
closures during recessions. This is not the case because long-term
profits are, in fact, nothing more than a prediction and the present
value of long term profits will be different at the beginning than at
the end of a recession. Recognizing these timing effects is why OSHA
examined the annualized value of losses in profits associated with the
recession beginning 2008 and compared it to the annualized value of the
loss in profits as result of costs of this standard. While temporary
and permanent losses are different, the use of discounting enables us
to compare short- and long-term losses.
c. International Trade Effects
The magnitude and strength of foreign competition is an important
factor in determining the ability of firms in the U.S. to pass on (part
or all of) the costs of the rule in the form of higher prices for their
products. If firms are unable to do so, they must absorb the costs of
the rule out of profits, possibly resulting in the business failure of
individual firms or even, if the cost impacts are sufficiently large
and pervasive, causing significant dislocations within an affected
industry.
As in the PEA, OSHA in the final economic analysis examined how
likely such an outcome is. The analysis there included a review of
trade theory and empirical evidence and the estimation of impacts.
Throughout, the Agency drew on ERG (2007c) (Document ID 1710), which
was prepared specifically to help analyze the international trade
impacts of OSHA's final silica rule. A summary of the FEA results is
presented below.
OSHA focused its analysis on eight of the industries likely to be
most affected by the final silica rule and for which import and export
data were available. OSHA combined econometric estimates of the
elasticity of substitution between foreign and domestic products,
Annual Survey of Manufactures data, and assumptions concerning the
values for key parameters to estimate the effect of a range of
hypothetical price increases on total domestic production. In
particular, OSHA estimated the domestic production that would be
replaced by imported products and the decrease in exported products
that would result from a 1 percent increase in prices--under the
assumption that firms would attempt to pass on all of a 1 percent
increase in costs arising from the final rule. The sum of the increase
in imports and decrease in exports represents the total loss to
industry attributable to the rule. These projected losses are presented
as a percentage of baseline domestic production to provide some context
for evaluating the relative size of these impacts.
The effect of a 1 percent increase in the price of a domestic
product is derived from the baseline level of U.S. domestic production
and the baseline level of imports. The baseline ratio of import values
to domestic production for the eight affected industries ranges from
0.04 for iron foundries to 0.547 for ceramic wall and floor tile
manufacturing--that is, baseline import values range from 4 percent to
more than 50 percent of domestic production in these eight industries.
OSHA's estimates of the percentage reduction in U.S. production for the
eight affected industries due to increased domestic imports (arising
from a 1 percent increase in the price of domestic products) range from
0.013 percent for iron foundries to 0.237 percent for cut stone and
stone product manufacturing.
OSHA also estimated the baseline ratio of U.S. exports to
consumption in the rest of the world for the sample of eight affected
industries. The ratios range from 0.001 for other concrete
manufacturing to 0.035 percent for nonclay refractory manufacturing.
The estimated percentage reductions in U.S. production due to reduced
U.S. exports (arising from a 1 percent increase in the price of
domestic products) range from 0.014 percent for ceramic wall and floor
tile manufacturing to 0.201 percent for nonclay refractory
manufacturing.
The total percentage change in U.S. production for the eight
affected industries is the sum of the loss associated with increased
imports and the loss resulting from reduced exports. The total
percentage reduction in U.S. production arising from a 1 percent
increase in the price of domestic products range from a low of 0.085
percent for other concrete product manufacturing to a high of 0.299
percent for porcelain electrical supply manufacturing.
These estimates suggest that the final rule would have only modest
international trade effects. It was previously hypothesized that if
price increases resulted in a substantial loss of revenue to foreign
competition, then the increased costs of the final rule would have to
come out of profits. That possibility has been contradicted by the
results reported in this section. The maximum loss to foreign
competition in any affected industry due to a 1 percent price increase
was estimated at approximately 0.3 percent of industry revenue.
Because, as reported earlier in this section, the maximum cost impact
of the final rule for any affected industry would be 0.56 percent of
revenue, this means that the maximum loss to foreign competition in any
affected industry as a result of the final rule would be 0.2 percent of
industry revenue --which would hardly qualify as a substantial loss to
foreign competition. This analysis cannot tell us whether the resulting
change in revenues will lead to a small decline in the number of
establishments in the industry or slightly less revenue for each
establishment. However it can reasonably be concluded that revenue
changes of this magnitude will not lead to the elimination of
industries or significantly alter their competitive structure.
Based on the Agency's preceding analysis of economic impacts on
revenues, profits, and international trade, along with the discussion
of industry concerns below, OSHA concluded that the annualized costs of
the final rule are below the threshold level that could threaten the
economic viability of any industry in general industry or maritime.
OSHA further noted that while there would be additional costs (not
attributable to the final rule) for some employers in general industry
and maritime to come into compliance with the new silica standard,
these costs would not affect the Agency's determination of the economic
feasibility of the final rule.
Public Comment on International Trade Effects
Foundries
The following comments discuss the loss of business to foreign
competition in the foundry industry. The comments have been grouped
together by issue and are followed by OSHA's response. The first group
of commenters used impact numbers from an alternative cost model to
discuss the loss of business to foreign competition.
The United States Chamber of Commerce ("the Chamber") stated that
additional costs of the rule's ancillary provisions along with
engineering controls will result in reduced competitiveness relative to
foreign foundries (Document ID 2288, pp. 27-28). The Chamber also
critiqued OSHA's inability to determine feasibility because of a lack
of data to analyze economic impacts across facilities by age, design,
operations, condition and region (Document ID 2288, pp. 29-30).
In the comments above, the negative economic effect of losing
business to foreign competition is based on an alternative cost model
report prepared for the American Foundry Society (AFS) by Environomics.
This report is addressed in the Engineering Control Costs section in
Chapter V of the FEA, where OSHA concluded that the costs in that
report were inflated. Because these inflated costs also underpin the
Chamber's claim that the rule will reduce competitiveness with foreign
foundries, OSHA does not accept that claim. In response to the
Chamber's criticism of OSHA's data sources, the Agency notes that
Chapter III, the section on Survey Data and OSHA Economic Analyses,
discusses why it was infeasible to collect and compile a full-scale
national survey of the kinds of baseline conditions and practices that
the Chamber of Commerce urged OSHA to consider.
The following comments from foundry firms and associations address
foreign competition in metalcasting from China and India along with the
inability to pass the cost on to their customers.
AFS submitted comments that the metalcasting industry would lose
business to foreign competition as follows:
Many foundries have closed in recent years with foreign
competition assuming much of that business. Five of the eleven
identifiable foundries used in the PEA to support OSHA's assertion
of feasibility have closed. Because castings are the starting point
of many manufacturing processes, loss of foundry jobs also means
loss of other manufacturing jobs.
The U.S. metalcasting industry is made up of 1,978 facilities,
down from 2,170 five years ago. This reduction can be attributed to
the recession, technological advancements, foreign competition and
tightening regulations (Document ID 2379, Attachment 3, p. 42; 4035,
p. 5).
The Indiana Cast Metals Association concurred with these comments
and also suggested that other industries would also be negatively
impacted if U.S. foundries shut down (Document ID 2049, p. 1). The Ohio
Cast Metals Association submitted two comments stating that the rule
will increase costs and undermine the Ohio-based metalcasting
industry's ability to compete in the global marketplace:
[The silica rule] will significantly increase costs, slow down
or eliminate hiring, reduce the number of foundry jobs and undermine
our industry's ability to compete in the global marketplace. For
some foundries, the rulemaking could be the final straw that
destroys their business.
...Over the past two decades Ohio foundries along with other
manufacturers throughout the United States have faced tremendous
international competition from China, Brazil, and India and many
foundries have closed and thousands of employees have lost their
jobs during this period. To suggest that Ohio foundries can just
pass on the tremendous costs associated with compliance with the
proposed silica rule with "minimal loss of business to foreign
competition" indicates that the individuals performing this
analysis were driven by other agendas or misinformed (Document ID
2119, Attachment 3, pp. 1-2).
Grede Holdings L.L.C. submitted a comment expressing its view that
it would be difficult for foundries to pass the cost of compliance to
the customer because of international competition, and that the number
of foundries in the U.S. has dropped by more than half since 1980,
going from 4,200 foundries to 2,050 foundries (Document ID 2298, p. 3).
Sawbrook Steel submitted two comments voicing concern that the
implementation of the regulation will cause jobs to move overseas,
resulting in a shrinking of the domestic casting manufacturing
(Document ID 2227, p. 2; 1995, p. 1).
In the comments above, businesses and associations state that the
costs of the rule will be too high and they will lose business to
foreign competition. The chief advantage of foreign imports to
downstream users, as reported to the U.S. International Trade
Commission (ITC) during an investigation they conducted into the
competitive conditions in the U.S. foundry market, is their low
pricing. Respondents to the investigations said the cost of foreign
produced products ranged from ten percent to forty percent less than
the cost of U.S. products (Document ID 0753, table 5-60, p. 5-53 as
referenced in Document ID 1710, pp. 5-4). U.S. producers have responded
to competition with a broad array of initiatives, such as implementing
lean manufacturing, improving customer service, and increasing
automation (Document ID 0753, pp. 10-14 and 10-15). According to the
ITC study:
The use of technology may also be influenced by the type of
castings produced and relative wage rates. Low-value, low-quality
castings, for example, generally require a lower level of technology
and relatively more semi-skilled labor than foundries producing more
complex castings. To lower labor costs, foundries in developed
countries with higher wage rates may install more automation and
technological improvements, whereas foundries in developing
countries with relatively lower wage rates may substitute labor for
relatively high-cost capital investments (Document ID 0753, p. 2-
11).
Before addressing issues on international competition for
metalcasters, it should be noted that all foundry industries affected
by this rule are below the ten percent cost to profit threshold and one
percent cost to revenue threshold. This means that even if the argument
that costs cannot be passed on were to be correct, the loss in profits
would be less than ten percent and unlikely to effect the feasibility
of the industry. Further the costs to be passed on would require less
than one percent price increases. In general, metalcasters in the U.S.
have shortened lead times, improved productivity through computer
design and logistics management, provided expanded design and
development services to customers, and provided a higher quality
product than foundries in China and other nations where labor costs are
low (Document ID 0753, p. 3-12). All of these measures, particularly
the higher quality of many U.S. metalcasting products and the ability
of domestic foundries to fulfill orders quickly, are substantial
advantages for U.S. metalcasters that may outweigh the very modest
price increases projected in Tables VI-3 and VI-4 of the FEA (Document
ID 1710, p. 5-4). According to the ITC study, quality was the number
one purchasing decision factor for the majority of purchasers, with
price and lead times ranking lower, and U.S. metalcasters are able to
deliver that quality (Document ID 0753, p. 4-5). The ITC report noted:
Certain purchasers noted that when inventory management and
complex manufacturing skills are required, U.S. foundries excel.
U.S. foundries were also cited by responding U.S. purchasers as
manufacturing with a low defect (rejection) rate. (Id.)
Purchaser responses to the ITC's survey stated that some U.S.
foundries are also completely inoculated against foreign competition,
even if the prices of U.S. foundry products rise:
As noted in questionnaire responses, certain purchasers are
committed to buying solely U.S.-made castings. One U.S. foundry
official noted that if downstream customers require castings to be
made in the United States, then U.S. foundries are guaranteed that
business. This situation often occurs when foundries supply castings
for federally funded operations, such as construction projects
(Document ID 0753, p. 4-5).
Foundries in China and India, while expanding their capacities, are
also faced with rising domestic demand due to their own rapidly
expanding domestic industrial economies, which affect their ability to
fulfill export demand (Document ID 0753, p. 5-16). ERG's research noted
a growth in U.S. foundry exports, which could help to offset some of
the foreign imports entering the U.S. market. According to one report
cited by ERG, U.S. foundry exports were roughly equivalent to 53
percent of the imports (Document ID 1710, p. 5-5).
ERG's research also provided some evidence that the combination of
U.S. and foreign demand for metalcasting may outstrip the supply to
such a degree that, even if the U.S. foundries operated at full
capacity, their maximum output would fail to meet the demand from the
U.S. and foreign markets (Document ID 1710, p. 5-5). The U.S. foundry
industry is unlikely to face any significant economic impacts if there
is ample demand and a limited supply because such a condition makes it
easier to pass along any costs of the rule.
Tile Production
The following comments discuss the difficulties of competing with
foreign tile producers followed by OSHA's response.
Tile Council of North America (TCNA) noted the import price
sensitivity between domestic tile and imported tile as follows:
The low cost of imported tile places an enormous burden on U.S.
tile manufacturers to maintain current pricing to remain
competitive. According to the latest data collected by TCNA, the
average price per square foot of U.S. tile shipments is $1.43. The
average price per square foot of Chinese imports is $0.86. With
Chinese imports 60% less expensive than U.S. tile in what is an
extremely price-competitive market, OSHA's claim that "any price
increases would result in minimum loss of business to foreign
competition" strains credulity.
To illustrate the tremendous import/price sensitivity between
domestic tile and imports, we note the increase in imports from Peru
as a result of a bilateral free trade agreement between Peru and the
United States eliminating duty on tile from Peru. Although only
amounting to a price change of 4--5 cents per square foot, from
2008, the year before the bilateral agreement to the end of 2011,
tile imports from Peru into the United States grew by 59%. This
illustrates how even a small change in price due to modest increases
in operating costs and raw material costs pose an existential threat
to the tile manufacturing industry.
The import sensitivity of domestic tile manufacturing operations
is well known by the United States International Trade Commission
(USITC) and the office of the United States Trade Representative
(USTR). The assertion made by OSHA that cost increases will not
result in lost market share to foreign competition is in direct
conflict with information known by USITC and the USTR and contrary
to established public policy (as reflected in existing Free Trade
Agreements) and industry testimony.
Contrary to the assertion made by OSHA, the marginal price
increases anticipated by required conformance to the rule as
proposed would make the domestic tile manufacturing industry highly
uncompetitive threatening the very viability of this import-
sensitive industry (Document ID 2363, p. 9).
The National Tile Contractors Association also questioned OSHA's
preliminary determination that the tile industry could pass on most or
all costs through higher prices, calling the claim "wildly
erroneous":
Implementation of the proposed rule's requirements would
increase both production and installation costs, and would put
pressure on consumer prices. At a time when U.S. consumption of
ceramic tile is more than 25% below its peak level (2006), this is a
serious concern. The U.S. market is already flooded with lower
quality, lower priced imports from many countries that likely do not
respect the health, safety, and rights of workers. The low cost of
imported tile places an enormous burden on U.S. tile manufacturers
to maintain current pricing to remain competitive (Document ID 2267,
p. 8).
Dal-Tile echoed the TCNA comments regarding the inability to pass
costs onto the customer (Document ID 2147, p. 3).
OSHA does not dispute the commenters' information indicating that
Chinese and Peruvian tile are significantly cheaper than U.S. tile, but
that point actually undercuts their claim that a small change in the
price of U.S. tile would place an "enormous burden" on U.S. tile
manufacturers. The commenters note that Chinese tile is already
available in the U.S. at just over half the price of U.S. tile. If the
market was actually as sensitive as the commenters suggest, and the
Chinese tile was competing for the same market share as U.S. tile,
under the commenter's logic the U.S. tile industry would have already
gone out of business. But that has not happened, suggesting that U.S.
tile manufacturers have been able to identify customers for whom the
tile price is not the predominant factor. Likewise, the example of
Peruvian tile demonstrates only that the lower-priced imported tile is
sensitive to small price changes. The commenter provides no evidence
that the Peruvian tile is competing for the same customers as the U.S.
tile industry.
In summary, the TCNA's argument that cost increases will result in
lost market share to foreign competition is unconvincing because it is
not clear that there is a strong relationship between the price of the
foreign tile and the price of the U.S. tile. One likely cause for this
disconnect is that, as TCNA notes, the market is "already flooded with
lower quality, lower priced" imports (Document ID 2363, p. 8),
suggesting that tile from China, Peru, and the other lower-priced
foreign importers are of a lower quality that may be targeted at a
different customer base than the higher-quality U.S. tile. This
perception that tile from China and other low-cost tile producing
countries may be of lower quality produces an imperfect substitution
scenario and adds to the inelasticity of demand for domestic tiles,
enabling producers to pass some of the costs on to the consumer.
On the other end of the tile price range are the Italian tiles.
Italy and China are the top countries of origin for tiles imported into
the U.S., but tiles from these countries command very different prices.
In terms of general tile products, one source indicates that the
average prices of tiles imported by the U.S. in 2012 were $20.20 to
$20.90 per square meter for Italian tiles and between $8.30 and $8.70
per square meter for Chinese tiles imported by the U.S., a significant
price difference that could be explained by a difference in
quality.\59\ TCNA stated above that the average price of tile from
China is $0.86 per square foot or $9.25 (10.76 x 0.86) per square
meter. TCNA's average price of American tile is $1.43 per square foot
or $15.39 (10.76 x 1.43) per square meter (Document ID 2363, p. 9),
which shows the U.S. producers to be supplying a mid-priced product.
Although Italy is also a major source of tile imports in the U.S.
despite their higher price, the commenters did not suggest that an
increase in U.S. tile prices would cause the U.S. to lose market share
to the Italian tile; nor did the commenters suggest that lower-priced
U.S. tile could be exported to dominate the Italian market. The
implication is, again, that different customers are willing to pay
different prices for different quality tile.
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\59\ http://www.scirp.org/journal/PaperInformation.aspx?PaperID=43515.
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Using price as an indicator of quality, the tile market can be
segmented into three categories: Low quality, mid-grade, and high
quality. The U.S. tile industry has located a niche between the lowest
quality/lowest priced tile and the highest quality/highest priced tile.
While it is possible that a few tile firms that produce very low-
quality or very high-quality tile may be negatively impacted by an
increase in the price of their tile, OSHA concludes that the majority
of firms would not experience a significant negative economic impact.
This is along with the fact that the increase in price from this rule
is expected to be minimal. TCNA commented that the average price per
square foot of U.S. tile shipments is $1.43. The cost to revenue ratio
for NAICS 327122 Ceramic Wall and Floor Tiles is 0.35 percent, meaning
this final rule will increase the average cost of U.S. tile by five
hundredths of a cent (or $0.0005 per square foot). It is therefore fair
to say this extremely modest increase in the average price of U.S. tile
would not have a significant economic impact on the U.S. tile industry
as a whole.
Brick Industry
During the public hearing Belden Tri-State Building Materials
stated that the brick industry has foreign competition, mostly from
Canada, and some from Mexico (particularly in Texas, Oklahoma or
Arkansas), and Germany (Document ID 3586, Tr. 3457). They indicated
that their competition includes not only imported brick but also
"other cladding materials like vinyl siding and HardiePlank," but the
competition from imported brick is typically "more expensive brick"
because of "innovations in Europe that we just haven't caught up to,
different sizes, different colors, different processes" (Id.).
Acme Brick Company representatives indicated in testimony that
oversees competition was virtually nonexistent because it is "hard to
get that across the ocean economically" and noted that they generally
locate their production facilities strategically to be near their
markets because "[p]roduction costs really are about a third of the
cost of the brick when we have them close...[The] farther away [the
bricks come from]--there are some distinctions in the quality or the
makeup of a brick" (Document ID 3577, Tr. 736).
This testimony indicates to OSHA that international competitors
will not be able to take advantage of any potential price increases
made by U.S. producers in the U.S. domestic brick market. The brick
making industry will therefore be able to pass on most, if not all, of
the costs of complying with the rule.
Hydraulic Fracturing
To determine the economic impacts for most industries, OSHA used
the Census Bureau's Statistics of U.S. Businesses to estimate revenues
on a six-digit NAICS basis but these revenue data were not sufficiently
precise to isolate the hydraulic fracturing component from the larger
industry (NAICS 213112). As a result, instead of using data from the
Economic Census, revenues for hydraulic fracturing firms were based on
estimated utilization rates and per stage revenues. As discussed in
Chapter III of the FEA, Profile of Affected Industries, the data on
this industry have been updated to reflect the comments in the record
and the best data available in 2012. The cost to profit percentage for
the hydraulic fracturing industry estimated in the FEA is 7.67 percent
(below OSHA's ten percent threshold) for fleets of all sizes. The ratio
of costs to revenues for hydraulic fracturing firms in the FEA is
estimated to be 0.54 percent for all establishments in the industry,
0.17 percent for small entities and 0.24 percent for very small
entities. Although the costs as a percent of revenue increased for all
establishments, the impacts still remain well below the one percent
threshold.
However, these estimates are based on the state of the industry in
the base year of 2012 supplemented with data provided in comments to
the proposed rule in 2013 and early 2014. When the PEA was published in
2006, the price of oil fluctuated between $70 and $80 a barrel. During
the years following the publication of the PEA the price of oil has had
some large fluctuations. Before the recession of 2008 the price of oil
peaked at $146 per barrel but dropped to $44 dollars per barrel during
the economic downturn in 2008.\60\ As the price of oil steadily
increased during 2009, there was an influx of money invested in the
hydraulic fracturing industry. The FEA uses revenue data from 2012 when
the price per barrel fluctuated between $90 and $100. However, in the
fourth quarter of 2014, the price of oil dropped to $49 per barrel. The
price of oil in 2015 has oscillated between approximately $45 and $60
per barrel.\61\ Because of this major change in the industry since the
record closed in 2012, OSHA has supplemented its feasibility analysis
with more current data.
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\60\ http://www.macrotrends.net/1369/crude-oil-price-history-chart.
\61\ http://www.macrotrends.net/1369/crude-oil-price-history-chart.
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The Structure of the Hydraulic Fracturing Industry
Hydraulic fracturing nearly doubled U.S. oil production from 5.6
million barrels a day in 2010 to a rate of 9.3 million barrels a day in
2015. Up until the drop in oil prices during the fourth quarter of
2014, the expected annual increase in production was one million
barrels. The economics of hydraulic fracturing wells is much different
than conventional wells.\62\ The marginal cost of producing a barrel of
oil from a conventional well for large oil producing countries is
around $15 to $30.\63\ Therefore, the owners of conventional wells
continue to produce even as the price per barrel decreased from $100 to
$40, and would remain in business at costs down to $30. The traditional
oil drilling business is driven by marginal costs, not costs spent to
drill the well. This means that supply is inelastic relative to demand.
This has not been true for the hydraulic fracturing industry.
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\62\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
\63\ http://knoema.com/vyronoe/cost-of-oil-production-by-country.
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Hydraulic fracturing wells have a very short life compared to
conventional wells. For example, a well in the Bakken region straddling
Montana and North Dakota may start out producing 1,000 barrels a day
then decline to 280 barrels at the beginning of year two. By year
three, more than half of the reserves will be depleted. Therefore, to
generate revenue, producers need to constantly drill new wells. In this
sense, hydraulic fracturing wells are more like gold or silver mines
than conventional oil production.\64\ The recent drop in oil prices has
caused a series of bankruptcies and closures across the oil industries.
Although there was a reduction in the number of rigs from about 1,600
to 800,\65\ hydraulic fracturing still accounted for 4.6 million
barrels a day out of a total of 9.4 million barrels or 49 percent of
total oil produced in February 2015. Hydraulic fracturing also
accounted for 54 percent of natural gas output.
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\64\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
\65\ http://www.economist.com/node/21648622/print.
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The Energy Information Administration (EIA) projects the Brent
crude oil price will average $40 a barrel in 2016 and $50 a barrel in
2017. However, EIA expects crude oil prices to rise in future years,
rising to over $70 per barrel by 2020 and to $100 per barrel by 2028.
EIA's crude oil price forecast remains subject to significant uncertainties
as the oil market moves toward balance and could continue to experience
periods of heightened volatility.\66\ Thus, industry implementation of
OSHA's engineering control requirements, which are not required until five
years after the effective date of the rule, may come during a period of much
higher and rising energy prices. In any case, the price increase required
by this rule is a very small fraction of the fluctuation in energy prices
during the past several years.
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\66\ http://www.eia.gov/forecasts/steo/report/prices.cfm.
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However, the possibility that oil prices are not going to increase
in the near future has spurred a new wave of innovation in energy
exploration. Now that prices have dropped to around $50 a barrel,
companies are focusing on efficiency and getting the most petroleum for
the least amount of money. With the effective date of this rule on the
horizon, it is possible that some of this innovation will lead to
technologies that not only increase efficiency but reduce worker
exposures to silica at the same time.
Through the application of new technology OSHA believes that, even
in a lower price environment, hydraulic fracturing entrepreneurs will
be able to implement the controls required by this final rule without
imposing significant costs, causing massive economic dislocations to
the hydraulic fracturing industry, or imperiling the industry's
existence. Big oil-field-services like Haliburton Co. and Schlumberger
Ltd. report that they have witnessed customers concentrating on using
technology such as lasers and other high-tech equipment and data
analytics before they drill to make sure new wells deliver the most
crude for the investment cost. The application of this new technology
as well as fiber-optic tools that help monitor a well during hydraulic
fracturing to make sure that it's working as well as possible and new
techniques to stimulate microbes already present that attach themselves
to bits of oil, essentially breaking it up and making it easier for the
crude to flow through rock \67\ have had positive quantitative results.
Productivity at some "super-fracking" wells has increased 400-600
barrels a day per rig from just a few years ago. Drilling efficiency in
some areas has increased as much as 26 percent in a single year \68\
while the time to drill and fracture a well has come down from an
average of 32 days in 2008 to now only about half that time: 14-16 days
from start to finish and in some cases even less. These increased
efficiencies result in significant cost savings.\69\ Also, the lower
demand by hydraulic fracturing companies for equipment rental,
trucking, and labor has caused a decrease in their prices, reducing the
overall cost of hydraulic fracturing.\70\
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\67\ http://www.wsj.com/articles/oil-companies-tap-new-technologies-to-lower-production-costs-1442197712/.
\68\ http://www.forbes.com/sites/judeclemente/2015/05/07/u-s-oil-production-forecasts-continue-to-increase/.
\69\ http://www.aei.org/publications/top-10-things-i-learned-on-my-summer-trip-to-the-bakken-oil-fields-part-ii/.
\70\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
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Although the drop in the price of oil has caused an initial
reduction in hydraulic fracturing operations, the application of
recently developed technology to new wells has increased per well
production. One expert was quoted in Fortune magazine as saying
"[t]here tailing off in U.S. drilling activity, but I expect continued
development drilling in major new areas, particularly the Bakken, even
at $50 (a barrel)." \71\ In the Bakken region in 2015 the decrease in
oil production resulting from the reduction of rigs was substantially
offset by increases in new well oil production per rig. There are
reasons to believe in the continuance of tight oil growth. An analysis
by IHS shows that most of the potential U.S. tight oil capacity
additions in 2015 have a break-even price in the range of $50 to $69
per barrel. Continued productivity gains, such as improvements in well
completion and downspacing, also support the continuation of U.S.
production growth at lower prices.\72\ Based on these advances, it is
plausible that hydraulic fracturing shale operations may achieve break-
even costs of $5-$20 per barrel.\73\
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\71\ http://fortune.com/2015/01/09/oil-prices-shale-fracking/.
\72\ http://press.ihs.com/press-release/energy-power/tight-oil-test-us-production-growth-remains-resilient-amid-lower-crude-oi.
\73\ http://economics21.org/commentary/shale-2.0-big-data-revolution-america-oil-fields-05-20-2015.
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A sign of the ongoing effectiveness of upgrades in efficiency in
the hydraulic fracturing business is evident in the projections for
U.S. crude production. The EIA's Annual Energy Outlook for 2015 has
projected that the U.S. is on track to hit reach a record for crude
output at 10.6 million barrels a day in 2020.\74\
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\74\ http://www.forbes.com/sites/judeclemente/2015/05/07/u-s-oil-production-forecasts-continue-to-increase/.
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While the economic conditions faced by the hydraulic fracturing
industry have changed significantly since the publication of the
proposed rule, this discussion shows that there is significant reason
to believe that this rule will not have a significant impact on the
hydraulic fracturing industry. Advancements in technology and the
application of new efficient drilling methods continue to increase the
per-rig production capacity of new-well oil drilling rigs while
lowering the costs of operating these rigs. These technological changes
increase the energy recovered through hydraulic fracturing, and thus
the value of fracturing services, without increasing the costs per well
associated with controlling silica exposures. Further, the demand for
fracturing services will depend, in part, on energy prices. The costs
associated with complying with the silica rule are a minor issue by
comparison. Thus, OSHA's conclusion that this rule is economically
feasible for the hydraulic fracturing industry has not changed.
Railroads
In the PEA, OSHA did not include any estimates of costs as
percentage of revenues or as a percentage of profits for railroads.
This was due to the fact that the standard sources of economic
statistics that were used for data on revenues and employment for all
other affected industries do not include railroads. The Association of
American Railroads (AAR) expressed concern about the impact of the rule
on small railroads (although not on larger railroads), but did not
provide any estimates or analysis, or suggest that OSHA use any
specific sources to conduct such an analysis. For the FEA, OSHA did
examine costs as percentage of revenues and profits for the railroad
industry as a whole using supplemental information from sources
typically relied on by the industry.
For the FEA, OSHA estimated that 16,895 workers in the rail
transportation industry (NAICS 4821; "railroads") will be covered by
the final standard, including 7,239 workers employed as Ballast Dumpers
and 9,656 workers employed as Machine Operators (for the purposes of
this analysis, OSHA assumed that the machine operators would be
conducting at least some work outside of the cab of the equipment). The
Agency estimated that compliance costs for railroads will total $16.6
million, or $980 per affected worker.
Based on these estimates, OSHA judged that the final rule is
feasible for railroads because combining supplemental data from BLS
\75\ and the Association of American Railroads \76\ for the estimated
105 rail transportation establishments in NAICS 4821 with a reported
revenue of $72.9 billion, the cost-to-revenue impacts are an estimated
0.02 percent and cost-to-profit impacts are an estimated 0.4 percent.
In addition, the per-worker cost for railroads ($980) is lower than the
average per-worker cost ($1,231) across all affected NAICS industries
in general industry and for 2000-2012, the average profit rate for
rail transportation, 6.2 percent, was significantly higher than the
average profit rate for all affected NAICS industries throughout general
industry (3.4 percent).
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\75\ Bureau of Labor Statistics, Quarterly Census of Employment
and Wages, Series ID ENUUS0002054821, NAICS 4821, Rail
Transportation. Accessed November 6, 2015.
\76\ Railroad Statistics. Association of American Railroads. AAR
Policy and Economics Department. July 15, 2014. http://www.aar.org/StatisticsAndPublications/Documents/AAR-Stats.pdf
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The AAR noted that small railroads had not been covered in the
Initial Regulatory Flexibility Analysis (Document ID 2366, p. 4). The
commenter is correct that OSHA did not examine small entities in this
sector but has done so for the FEA using supplemental information on
railroads.
In 2012, 574 U.S. freight rail establishments, employing 181,264
workers, operated on roughly 169,000 miles of track.\77\ The Surface
Transportation Board in the U.S. Department of Transportation
classifies railroads into three groups based on annual revenues:
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\77\ Class I Railroad Statistics. Association of American
Railroads. AAR Policy and Economics Department. July 15, 2014.
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Class I for freight railroads defined as railroads with
annual operating revenues above $467.1 million ($2013)
Class II, includes some regional railroads, defined as
railroads each with operating revenues between $37.4 million and $467.1
million ($2013)
Class III for all other freight rail operations (including
smaller regional, short-line, switching, and terminal).\78\
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\78\ Federal Register, Volume 79, No. 111, June 10,2014, p.
33257, cited in Summary of Class II and Class III Railroad Capital
Needs and Funding Sources--A Report to Congress, Federal Railroad
Administration, October 2014, p. 2 http://www.fra.dot.gov/Elib/Document/14131.
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In 2013, in addition to the seven Class I freight railroad systems,
there were 21 regional railroads (line-haul railroads operating at
least 350 miles of road and/or earning revenue between roughly $40
million and the Class I threshold), and over 500 local railroads (line-
haul or short-line railroads smaller than regional railroads).\79\
Among the 567 railroads that fell below the Class I revenue threshold,
11 qualified as Class II and the remainder (556, including 10 regional
railroads) qualified as Class III (FRA, 2015). Class III railroads are
typically local short-line railroads serving a small number of towns
and industries or hauling cars for one or more larger railroads. Many
Class III railroads were once branch lines of larger railroads or
abandoned portions of main lines.
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\79\ Freight Railroads Background. (FR, 2015) Stephanie
Lawrence, Office of Policy, Office of Rail Policy and Development,
Federal Railroad Administration April 2015. http://www.fra.dot.gov/eLib/Details/L03011. These regional railroads are almost evenly
divided between Class II (11 railroads) and Class III (10
railroads).
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In 2012, employment within 546 local railroad companies totaled
12,293 workers and employment within 21 regional railroads totaled
5,507 workers. Line Haul Railroads are classified in NAICS 482111 and
entities within this industry with 1,500 or fewer workers are
classified as small by SBA size standards. Local/Short Line Railroads
are classified in NAICS 482112 and entities within this industry with
500 or fewer workers are classified as small by the SBA size standard.
For 2012, OSHA estimated that all 567 Class II and Class III railroads
(combined total of 17,800 workers) qualified as small entities
according to the SBA definitions.
In a recent study prepared for Congress,\80\ the Federal Railroad
Administration reported that in 2013, 546 Local/Short Line Railroads
employed 12,293 workers and earned $2.6 billion in revenue. OSHA
estimates that of the 16,895 affected employees throughout rail
transportation, 1,146 employees of Short-Line railroads are affected by
the final rule.\81\ According to the BLS Quarterly Census of Employment
and Wages, on average 32 establishments were identified within NAICS
482112, Short-Line Railroads (an establishment can operate more than
one railroad). Therefore, if all 546 Class III railroads are controlled
by 32 establishments, OSHA estimates that revenue per establishment is
approximately $81.3 million.
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\80\ Summary of Class II and Class III Railroad Capital Needs
and Funding Sources, Federal Railroad Administration, Report to
Congress, October 2014.http://www.fra.dot.gov/Elib/Document/14131.
\81\ (16,895 affected workers/181,264 total employees in NAICS
4821) * 12,293 total Short-Line employees = 1,146 affected Short-
Line employees.
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OSHA estimated that compliance costs for rail transportation will
total $16,562,059. Therefore, if costs per affected worker ($980 per
worker) are apportioned to the establishments operating Short-Line
Railroads, OSHA estimates that costs for these local railroads will
total $1.1 million, or roughly $35,100 per establishment. As noted
above, annual revenues among Short-Line rail operations total
approximately $2.6 billion, or $81.3 million per establishment.
Applying the industry-wide profit rate of 6.23 percent for NAICS 4821,
OSHA estimated that profits per establishment in NAICS 482112 are $5.1
million. Therefore, OSHA estimates that impacts measured as costs as a
percent of revenues will not exceed 0.04 percent, and that impacts
measured as costs as a percent of profits will not exceed 0.69 percent.
Thus, OSHA concludes that the silica standard will not impose a
significant impact on a substantial number of small entities in rail
transportation and therefore will not threaten the competitive
structure or viability of small entities in NAICS 482110.
d. Economic Feasibility Screening Analysis: Small and Very Small
Businesses
The preceding discussion focused on the economic viability of the
affected industries in their entirety. Even though OSHA found that the
final standard did not threaten the survival of these industries, there
is still the possibility that the competitive structure of these
industries could be significantly altered.
To address this possibility, OSHA followed its normal rulemaking
procedure for examining the annualized costs per affected small entity
and per very small entity for each affected industry in general
industry and maritime. Again, OSHA used its typical minimum threshold
level of annualized costs equal to one percent of annual revenues--and,
secondarily, annualized costs equal to ten percent of annual profits--
below which the Agency has concluded that the costs are unlikely to
threaten the survival of small entities or very small entities or,
consequently, to alter the competitive structure of the affected
industries.
Compliance costs for entities with fewer than 20 employees were
estimated, in many cases, using a derived compliance cost per employee.
Assuming costs to be equally distributed among all employees, OSHA
estimated the compliance cost per employee by dividing total costs for
each NAICS by the number of employees. OSHA then multiplied the
compliance cost per employee with the ratio of the average number of
employees per entity with fewer than 20 employees. Similarly,
compliance costs per small entity were estimated from the product of
compliance costs per employee and the average number of employees in
entities within the SBA classification for the given NAICS. However,
some compliance costs, such as some engineering control costs, were
modified to reflect diseconomies of scale for very small establishments.
As shown in Table VII-19 and Table VII-20, the annualized cost of
the final rule is estimated to be $2,967 for the average small entity
in general industry and maritime and $1,532 for the average very small
entity in general industry and maritime. These tables also show that
the only industry in which the annualized costs of the final rule for
small entities exceed one percent of annual revenues is NAICS 213112
(Support Activities for Oil and Gas Operations), which is estimated to
be 1.29 percent. There are two industries for very small entities
exceeding one percent of annual revenues--NAICS 213112 (Support
Activities for Oil and Gas Operations), 2.09 percent and NAICS 327110
(Pottery, Ceramics, and Plumbing Fixture Manufacturing), 1.21 percent.
Small entities in nine industries in general industry and maritime
are estimated to have annualized costs in excess of ten percent of
annual profits; NAICS 327110: Pottery, Ceramics, and Plumbing Fixture
Manufacturing (38.6 percent); NAICS 327120: Clay Building Material and
Refractories Manufacturing (33.6 per cent); NAICS 327991: Cut Stone and
Stone Product Manufacturing (24.7 percent); NAICS 327999: All Other
Miscellaneous Nonmetallic Mineral Product Manufacturing (20.9 percent);
NAICS 327390: Other Concrete Product Manufacturing (18.6 percent);
NAICS 213112: Support Activities for Oil and Gas Operations (18.2
percent); NAICS 327332: Concrete Pipe Manufacturing (14.5 percent);
NAICS 327331: Concrete Block and Brick Manufacturing (13.1 percent);
and NAICS 327320: Ready-Mix Concrete Manufacturing (11.5 percent).
Very small entities in sixteen industries are estimated to have
annualized costs in excess of ten percent of annual profit: NAICS
327110: Pottery, Ceramics, and Plumbing Fixture Manufacturing (90.6
percent); NAICS 327120 Clay Building Material and Refractories
Manufacturing (58.5 percent); NAICS 327999: All Other Miscellaneous
Nonmetallic Mineral Product Manufacturing (51.1 percent); NAICS 327991:
Cut Stone and Stone Product Manufacturing (30.8 percent); NAICS 213112:
Support Activities for Oil and Gas Operations (29.5 percent); NAICS
327390: Other Concrete Product Manufacturing (29.2 percent); NAICS
327212: Other Pressed and Blown Glass and Glassware Manufacturing (22.7
percent); NAICS 327332: Concrete Pipe Manufacturing (22.1 percent);
NAICS 327211: Flat Glass Manufacturing (20.4 percent); NAICS 327331:
Concrete Block and Brick Manufacturing (19.5 percent); NAICS 327993:
Mineral Wool Manufacturing (17.4 percent); NAICS 327992: Ground or
Treated Mineral and Earth Manufacturing (16.3 percent); NAICS 327320:
Ready-mix Concrete Manufacturing (15.9 percent); NAICS 331513: Steel
Foundries (except investment) (12.3 percent); NAICS 331524: Aluminum
Foundries (except die-casting) (11.3 percent); and NAICS 331511: Iron
Foundries (10.0 percent).
In general, cost impacts for affected small entities or very small
entities will tend to be somewhat higher, on average, than the cost
impacts for the average business in those affected industries. That is
to be expected. After all, smaller businesses typically suffer from
diseconomies of scale in many aspects of their business, leading to
lower revenue per dollar of cost and higher unit costs. Small
businesses are able to overcome these obstacles by providing
specialized products and services, offering local service and better
service, or otherwise creating a market niche for themselves. The
higher cost impacts for smaller businesses estimated for this rule
generally fall within the range observed in other OSHA regulations for
which there is no record of major industry failures.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
In allocating the share of costs to very small entities, OSHA did
not have direct information about how many very small entities were
engaged in silica-related activities. Instead, OSHA assumed that the
affected employees would be distributed among entities of different
size according to each entity size class's share of total employment.
In other words, if 15 percent of employees in an industry worked in
very small entities (those with fewer than 20 employees), then OSHA
assumed that 15 percent of affected employees in the industry
would work in very small entities. However, in reality, OSHA
anticipates that in industries with foundries, none of the entities
with fewer than 20 employees have foundries or, if they do, that the
impacts are much smaller than estimated here.
SBREFA Comments on Impacts on General Industry and Maritime
In this section, OSHA reviews comments addressing economic impacts
in general industry and maritime that were submitted during the SBREFA
process prior to the PEA. OSHA addressed these comments in the PEA that
was made available for public comment, but OSHA did not receive
comments specifically addressing its responses to the SBREFA
recommendations. OSHA is reprinting its responses here for the
convenience of the reader.
SERs from foundries stated that there had been a long-run decline
in the number of foundries in the United States, with the industry
under continued pressure from foreign competitors and the need to meet
new domestic regulations. The total expense of the draft standard and
inability to meet lower PELs would pressure more U.S. foundries out of
business, continuing an historical trend in this industry, SERs said.
The variability in the foundry products and small open-area production
plants would make meeting lower PELs difficult and costly. Many smaller
foundries would be put out of business, the SERs said, and many jobs
lost in the industry. "Twenty percent of profits is a great deal to
spend on engineering controls with questionable results.... [t]he
economics of the foundry industry today are not pretty," one SER said.
And another: "The cost of meeting the standard will be very difficult
....A PEL of 50 would put us out of business." OSHA found in this
FEA that costs as percentage of profits for even very small foundries
would not rise to a level of 20 percent.
SERs from the brick industry stated that meeting the provisions of
the draft proposed standard, particularly with a lower PEL, would be
very tough for their competitive, low margin industry. Similarly, a SER
from the pre-cast concrete industry said, "The problem is not putting
the company out of business, but that the price of products will
increase." OSHA found that because bricks face limited foreign
competition, a very small change in the price of bricks would not
affect the viability of the industry.
Other SERs (industrial sand, molding powders, refractory concrete)
noted that the impact of the standard on them, particularly if the PEL
is lowered, would entail substantial costs, but indirect effects could
be significant as well since their major customers (foundries) could be
negatively impacted, too. "Refractory companies are going out of
business with the foundries," one SER said. OSHA has concluded that
foundries will not, in general go out of business.
e. Regulatory Flexibility Screening Analysis
To determine if the Assistant Secretary of Labor for OSHA can
certify that the final silica standard for general industry and
maritime will not have a significant economic impact on a substantial
number of small entities, the Agency has developed screening tests to
consider minimum threshold effects of the final standard on small
entities. The minimum threshold effects for this purpose are annualized
costs equal to one percent of annual revenues and annualized costs
equal to five percent of annual profits applied to each affected
industry. (OSHA uses five percent as a threshold for significant
impacts on small entities rather than the ten percent used for
potentially serious impacts on industries in order to assure that small
entity impacts will always receive special attention.) OSHA has applied
these screening tests both to small entities and to very small
entities. For purposes of certification, the threshold level cannot be
exceeded for affected small entities or very small entities in any
affected industry. Table VII-19 and Table VII-20 show that, in general
industry and maritime, the annualized costs of the final rule exceed
one percent of annual revenues for small entities and very small
entities in one industry. These tables also show that the annualized
costs of the final rule exceed five percent of annual profits for small
entities in 15 industries and for very small entities in 25 industries.
OSHA is therefore unable to certify that the final rule will not have a
significant economic impact on a substantial number of small entities
in general industry and maritime and must prepare a Final Regulatory
Flexibility Analysis (FRFA). The FRFA is presented in Section VII.I of
this preamble.
3. Impacts in Construction
a. Economic Feasibility Screening Analysis: All Establishments
To determine whether the final rule's estimated costs of compliance
would threaten the economic viability of affected construction
industries, OSHA used the same data sources and methodological approach
that were used earlier in this section for general industry and
maritime. OSHA first compared, for each affected construction industry,
annualized compliance costs to annual revenues and profits per
(average) affected establishment. The results for all affected
establishments in all affected construction industries are presented in
Table VII-21, using annualized costs per establishment for the final
PEL of 50 [mu]g/m\3\.
The annualized cost of the rule for the average establishment in
construction, encompassing all construction industries, is estimated at
$1,097 in 2012 dollars. The estimates of the annualized costs per
affected establishment range from $4,811 for NAICS 237300 (Highway,
Street, and Bridge Construction) and $4,463 for NAICS 237100 (Utility
System Construction) to $364 for NAICS 236100 (Residential Building
Construction) and $360 for NAICS 221100 (Electric Utilities).
Table VII-21 shows that the annualized costs of the rule do not
exceed one percent of annual revenues or 10 percent of annual profits
for any affected construction industry. NAICS 238100 (Foundation,
Structure, and Building Exterior Contractors) has both the highest cost
impact as a percentage of revenues, of 0.12 percent, and the highest
cost impact as a percentage of profits, of 3.66 percent. For all
affected establishments in construction, the estimated annualized cost
of the final rule is, on average, equal to 0.05 percent of annual
revenue and 1.52 percent of annual profit. These are well below the
minimum threshold levels of 1 percent and 10 percent, respectively.
Therefore, even though the annualized costs of the final rule
incurred by the construction industry as a whole are roughly twice the
combined annualized costs incurred by general industry and maritime,
OSHA concludes, based on its screening analysis, that the annualized
costs as a percentage of annual revenues and as a percentage of annual
profits are below the threshold level that could threaten the economic
viability of any of the construction industries. OSHA therefore finds
that the final rule is economically feasible for each of the industries
engaged in construction activities. OSHA further notes that while there
would be additional costs (not attributable to the final rule) for some
employers in construction industries to come into compliance with the
preceding silica standard, these costs would not affect the Agency's
determination of the economic feasibility of the final rule.
Below, OSHA provides additional information to further support the
Agency's conclusion that the final rule would not threaten the economic
viability of any construction industry.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
b. Normal Year-to-Year Variations in Profit Rates
As previously noted, the United States has a dynamic and constantly
changing economy in which large year-to-year changes in industry profit
rates are commonplace. A recession, a downturn in a particular
industry, foreign competition, or the increased competitiveness of
producers of close domestic substitutes are all easily capable of
causing a decline in profit rates in an industry of well in excess of
10 percent in one year or for several years in succession.
To demonstrate the normal year-to-year variation in profit rates
for all the establishments in construction affected by the final rule,
OSHA presented data in the FEA on year-to-year profit rates and year-
to-year percentage changes in profit rates, by industry, for the years
2000-2012. For the combined affected industries in construction over
the 13-year period, the average change in profit rates was 63.09
percent a year. If the three worst years are excluded, there is still
substantial variation in profits, far larger than the change in profits
that would be necessary if the costs of this rule cannot be passed on.
These data indicate that even if the annualized costs of the final
rule for the most significantly affected construction industries were
completely absorbed in reduced annual profits, the magnitude of reduced
annual profit rates is well within normal year-to-year variations in
profit rates in those industries and does not threaten their economic
viability. Of course, a permanent loss of profits would present a
greater problem than a temporary loss, but it is unlikely that all
costs of the final rule would be absorbed in lost profits. Given that,
as discussed in Chapter VI of the FEA, the overall price elasticity of
demand for the outputs of the construction industry is fairly low and
that almost all of the costs estimated in Chapter V of the FEA are
variable costs, the data and economic theory suggest that most firms
will see small declines in output rather than that any but the most
extremely marginal firms would face any real risk of closure. Many
parts of the construction industry have already absorbed much more
drastic changes in profit without evidence of industry collapse or
major change.
Market Structure and Market Impacts in the Construction Industry
At a conceptual level, the market-determined output of the
construction industry depends on the intersection of demand and supply
curves. Incremental compliance costs of the rule (which are almost
entirely variable costs) shift the construction supply curve upward.
The net effect is an increase in the price for construction activities
and a reduction in the level of activity (with the magnitude of this
effect depending on the price elasticity of demand). Lower levels of
activity mean less construction work, a reduction in the number of
construction establishments, and a concomitant reduction in
construction employment. The greater the price elasticity of demand and
the greater the increase in marginal costs, the larger will be the
reduction in equilibrium output. In terms of prices, the greater the
price elasticity of demand, the smaller the increase in prices will be
for a given increment to marginal costs, and the larger the reduction
in output.
Increasing the cost of construction project activities that
generate silica exposures has two effects on the demand for these
activities. First, increasing the cost of silica-related jobs relative
to the costs of other construction inputs might result in substitution
away from this type of work. Architects, building designers, and
contractors might be more likely to choose building methods and
materials that eliminate or reduce the need to perform silica-related
jobs. For example, pre-cast concrete structures that require a
relatively high level of concrete finishing work would become more
expensive relative to other building technologies. Contractors and
others could reduce the cost impact of the standard by switching to
other building methods unaffected by the silica rule when the
alternative would result in lower cost than would compliance with the
rule. The magnitude of these impacts will depend on the feasibility,
characteristics, and relative expense of alternative technologies.
Second, some of the increase in the cost of silica-generating
activities will increase the marginal cost of construction output and
cause the construction supply curve to shift upward, resulting in a
higher price for each quantity produced. The magnitude of the impact of
the cost increases due to the silica rule on the supply relationship
will depend on the size of the cost increases and the importance of
silica-generating activities in the overall cost of construction
projects. If the silica-generating activities are a small portion of
the overall cost of construction then the supply curve shift will be
smaller when compared to a shift in the supply curve from silica-
generating activity that is a large portion of the overall cost of
construction. If, for example, there is a one percent increase in the
costs of a silica generating activity and the silica generating
activity constitutes only one percent of the costs of a building, then
the total increase in the cost of the building will be an almost
unobservable 0.01 percent. Magnitude of shifts in derived demand for a
service used in making another product are determined by the price
change for the final product, not the price change for the service
itself.
In practice, if one considers the costs of the final rule relative
to the size of construction activity in the United States, it is clear
that the price and profit impacts of the final rule on construction
industries must be quite limited. The annualized cost of the final rule
would be equal to approximately 0.1 percent of the value of annual
construction activity in the U.S. Moreover, construction activity in
the U.S. is not subject to any disadvantage from foreign competition--
any foreign firms performing construction activities in the United
States would be subject to OSHA regulations.
c. Impacts by Type of Construction Demand
The demand for construction services originates in three
independent sub-sectors: residential building construction,
nonresidential building construction, and nonbuilding construction.
Residential Building Construction: Residential building demand is
derived from the household demand for housing services. These services
are provided by the stock of single and multi-unit residential housing
units. Residential housing construction represents changes to the
housing stock and includes construction of new units and modifications,
renovations, and repairs to existing units. A number of studies have
examined the price sensitivity of the demand for housing services.
Depending on the data source and estimation methodologies, these
studies have estimated the demand for housing services at price
elasticity values ranging from -0.40 to -1.0, with the smaller (in
absolute value) less elastic values estimated for short-run periods
(Glennon, 1989, Document ID 0707; Mayo, 1981, Document ID 0794). In the
long run, it is reasonable to expect the demand for the stock of
housing to reflect similar levels of price sensitivity.
Many of the silica-generating construction activities affected by
the rule are not widely used in single-family construction or
renovation. This assessment is consistent with the cost estimates that
show relatively low impacts for residential building contractors. (See
Table VI-9 of the FEA--the costs as a percent of revenues
for Residential Building Construction are estimated to be 0.03 percent
and the costs as a percent of profits are estimated to be 1.29
percent). Multi-family residential construction might have more
substantial impacts, but, based on Census data, this type of
construction represents a relatively small share of net investment in
residential buildings.
Nonresidential Building Construction: Nonresidential building
construction consists of industrial, commercial, and other
nonresidential structures. As such, construction demand is derived from
the demand for the output of the industries that use the buildings. For
example, the demand for commercial office space is derived from the
demand for the output produced by the users of the office space. The
price elasticity of demand for this construction category will depend,
among other things, on the price elasticity of demand for the final
products produced, the importance of the costs of construction in the
total cost of the final product, and the elasticity of substitution of
other inputs that could substitute for nonresidential building
construction. ERG (2007c) found no studies that attempted to quantify
these relationships (Document ID 1710). But given the costs of the
final rule relative to the size of construction spending in the United
States, the resultant price or revenue effects are likely to be quite
small as well.
Nonbuilding Construction: Nonbuilding construction includes roads,
bridges, and other infrastructure projects. Utility construction (power
lines, sewers, water mains, etc.) and a variety of other construction
types are also included. A large share of this construction (63.8
percent) is publicly financed (ERG, 2007a, Document ID 1709). For this
reason, a large percentage of the decisions regarding the appropriate
level of such investments is not made in a private market setting. The
relationship between the costs and price of such investments and the
level of demand might depend more on political considerations than the
factors that determine the demand for privately produced goods and
services.
While a number of studies have examined the factors that determine
the demand for publicly financed construction projects, these studies
have focused on the ability to finance such projects (e.g., tax
receipts) and socio-demographic factors (e.g., population growth) to
the exclusion of cost or price factors. In the absence of budgetary
constraints, the price elasticity of demand for public investment is
therefore probably quite low. On the other hand, budget-imposed limits
might constrain public construction spending. If the dollar value of
public investments were fixed, a price elasticity of demand of 1 would
be implied and any percentage increase in construction costs would be
offset with an equal percentage reduction in investment (measured in
physical units), keeping public construction expenditures constant.
Public utility construction comprises the remainder of nonbuilding
construction. This type of construction is subject to the same derived-
demand considerations discussed for nonresidential building
construction, and for the same reasons, OSHA expects the price and
profit impacts to be quite small.
SBREFA Comments on Impacts on the Construction Industry
In this section OSHA reviews comments addressing economic impacts
in construction that were submitted during the SBREFA process prior to
the PEA. OSHA addressed these comments in the PEA that was made
available for public comment, but did not receive comments specifically
addressing its responses to the SBREFA recommendations. OSHA is
reprinting its responses here for the convenience of the reader.
One commenter believed that OSHA had ignored the range of
profitability among businesses, and thus did not adequately recognize
that the average percentage reduction in profits could mean bankruptcy
for those firms struggling to stay afloat. The Agency's approach to
economic feasibility is designed to address the overall health of
industries in compliance with legal precedent, which permits OSHA to
find a regulation economically feasible even though it may close some
marginal firm. In most years, ten percent or more of construction firms
exit the industry (See U.S. Census Bureau Business Dynamics Statistics,
available at http://www.census.gov/ces/dataproducts/bds/data_firm.html).
The slight acceleration of the closure of such firms is not the kind of
economic impact that would make a regulation economically infeasible.
The commenter also asserted that OSHA ignored the cost of credit
and that this also varies across businesses. OSHA believes that the
cost of credit is not an important issue in this case because OSHA's
analysis demonstrates that, in most cases, upfront costs can usually be
met from cash flow. Earlier in this chapter, OSHA noted that its choice
of a threshold level of ten percent of annual profits for economic
feasibility determinations is low enough that even if, in a
hypothetical worst case, all compliance costs were upfront costs, then
upfront costs would still equal 88.5 percent of profits and thus would
be affordable from profits alone without needing to resort to credit
markets. As shown in Table VI-12 of the FEA, all industries' costs are
a very small percentage of profits, assuring that even upfront costs
can be met from profits without resorting to credit markets. Further, a
firm that is having trouble meeting upfront costs can rent the
appropriate tools without incurring any upfront capital investment
costs.
A SER asserted that the impact of the rule would be
"catastrophic" for the concrete cutting industry. One SER maintained
that the rule would be both economically and technologically infeasible
for the specialty trade concrete cutting industry (Document ID 0937, p.
69). The Small Business Advocacy Review (SBAR) Panel recommended that
OSHA thoroughly review the economic impacts, and develop a more
detailed economic feasibility analysis for certain industries (Document
ID 0937, p. 69). OSHA believes that the analyses in this chapter and in
Chapter IX of the FEA address the SER's comments and the SBAR Panel
recommendations.
Concrete cutting is undertaken for such purposes as grooving for
projects such as highways, bridges, and sidewalks along with repairing
these structures when they become operationally unsound. These
contracts are bid on by firms who will all fall under the final silica
rule, so there is no economic disadvantage between firms caused by the
silica rule. Because the silica rule only applies in areas subject to
OSHA jurisdiction, there is no foreign competition that would not also
be subject to the silica standard. The cutting industry also works on
runways and parking lots along with homebuilders for smaller projects.
The demand for these products are relatively inelastic and not subject
to foreign competition, enabling these companies to pass most of the
costs of this final rule onto their consumers. Based on these analyses,
OSHA disagrees that the rule would be "catastrophic" or economically
infeasible for the concrete cutting industry.
d. Economic Feasibility Screening Analysis: Small and Very Small
Businesses
The preceding discussion focused on the economic viability of the
affected construction industries in their entirety. However, even
though OSHA found that the silica standard did not threaten the
survival of these construction industries, there is still the
possibility that the industries' competitive structures could be
significantly altered.
To address this possibility, OSHA examined the annualized costs per
affected small and very small entity for each affected construction
industry. Table VII-22 and Table VII-23 show that in no construction
industries do the annualized costs of the final rule exceed one percent
of annual revenues or 10 percent of annual profits either for small
entities or for very small entities. Therefore, OSHA concludes, based
on its screening analysis, that the annualized costs as a percentage of
annual revenues and as a percentage of annual profits are below the
threshold level that could threaten the competitive structure of any of
the construction industries.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
e. Differential Impacts on Small Entities and Very Small Entities
Below, OSHA provides some additional information about differential
compliance costs for small and very small entities that might influence
the magnitude of differential impacts for these smaller businesses.
The distribution of impacts by size of business is affected by the
characteristics of the compliance measures. For silica controls in
construction, the dust control measures consist primarily of equipment
modifications and additions made to individual tools, rather than
large, discrete investments, such as might be applied in a
manufacturing setting. As a result, compliance advantages for large
firms through economies of scale are limited. It is possible that some
large construction firms might derive purchasing power by buying dust
control measures in bulk. However, given the simplicity of many control
measures, such as the use of wet methods on machines already
manufactured to accommodate controls, such differential purchasing
power appears to be of limited consequence.
The greater capital resources of large firms will give them some
advantage in making the relatively large investments needed for some
control measures. For example, cab enclosures on heavy construction
equipment or foam-based dust control systems on rock crushers might be
particularly expensive for some small entities with an unusual number
of heavy equipment pieces. Nevertheless, where differential investment
capabilities exist, small construction firms may also have the
capability to achieve compliance with lower-cost measures, such as by
modifying work practices. In the case of rock crushing, for example,
simple water spray systems can be arranged without large-scale
investments in the best commercially available systems.
In the program area, large firms might have a slight advantage in
the delivery of training or in arranging for health screenings. This
phenomenon has been accounted for in the analysis that OSHA provides.
f. Regulatory Flexibility Screening Analysis
To determine if the Assistant Secretary of Labor for OSHA can
certify that the final silica standard for construction will not have a
significant economic impact on a substantial number of small entities,
OSHA applies the same screening analysis to construction as it does for
general industry, as discussed earlier in that section for the same
reasons: annualized costs equal to one percent of annual revenues and
annualized costs equal to five percent of annual profits applied to
each affected industry. OSHA has applied these screening tests both to
small entities and to very small entities. For purposes of
certification, the threshold levels cannot be exceeded for affected
small or very small entities in any affected industry.
Table VII-22 and Table VII-23 show that in no construction
industries do the annualized costs of the final rule exceed one percent
of annual revenues or five percent of annual profits either for small
entities or for very small entities. However, as previously noted in
this section, OSHA is unable to certify that the final rule will not
have a significant economic impact on a substantial number of small
entities in general industry and maritime and must prepare a Final
Regulatory Flexibility Analysis (FRFA). The FRFA is presented in
Section VII.I of this preamble.
4. Employment Impacts on the U.S. Economy
The discussion below on employment impacts of the silica rule on
the U.S. economy is divided into three parts: (1) a brief summary of
the employment impacts of the proposed silica rule (based on an
analysis performed for OSHA by its subcontractor, Inforum, in 2011,
Document ID 1701) that the Agency included in the PEA in support of the
silica proposal; (2) a review of estimates provided by commenters on
the employment effects of the silica proposal; and (3) a summary of a
recent analysis of the employment effects of the final silica rule that
Inforum performed for OSHA, followed by a critique of the commenters'
analysis of employment effects relative to Inforum's analysis.
a. Inforum Analysis of Employment Effects Prepared for Silica Proposal
In October 2011, OSHA directed Inforum \82\ to run its
macroeconomic model to estimate the employment impacts of the costs
\83\ of the proposed silica rule. Inforum ran the model for the ten-
year period 2014-2023 and reported its annual and cumulative employment
and other macroeconomic results. While employment effects varied from
year to year and from industry to industry, a key Inforum result was
that the proposed silica rule cumulatively would generate an additional
8,625 job-years over the period 2014--2023, or an additional 862.5 job-
years annually, on average, over the period.\84\ A fuller discussion of
Inforum's macroeconomic model and the results of its analysis can be
found in Chapter VI of the PEA in support of OSHA's silica proposal and
in the Inforum report itself (Inforum, 2011, Document ID 1701).
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\82\ Inforum, which stands for the INterindustry FORecasting at
the University of Maryland, is a not-for-profit Maryland
corporation. Inforum has over 45 years of experience designing and
using macroeconomic models of the United States (and other
countries). Details of Inforum's macroeconomic model are presented
later in this section.
\83\ The estimated cost at the time was approximately $650
million in 2009 dollars using a 3 percent discount rate.
\84\ A "job-year" is the term of art used to reflect the fact
that an additional person is employed for a year, not that a new job
has necessarily been permanently created.
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b. Estimates by Commenters on Employment Effects of the Silica Proposal
Three commenters on the silica proposal--the National Federation of
Independent Business (NFIB) with the NFIB Research Foundation; the
American Chemistry Council (ACC) with Stuart Sessions of Environomics,
Inc.; and the Construction Industry Safety Coalition (CISC) with
Environomics, Inc.--provided or reported estimates of the employment
effects of the proposed silica rule. These commenter estimates are
summarized below.
The NFIB Research Foundation performed a study (Document ID 2210,
Attachment 2) to estimate the employment and other macroeconomic
effects of OSHA's proposed rule, using the Agency's own estimates of
the annualized compliance costs of the proposed rule for affected
employers of approximately $637 million in 2009 dollars. The study
modeled (a) anticipated employer costs due to the proposed rule, (b)
changes to private sector demand, and (c) changes to state and local
government spending associated with the proposed rule, and then
forecast their effects using NFIB's Business Size Impact Module (BSIM)
to run a simulation. The BSIM is a dynamic, multi-region model based on
the Regional Economic Models, Inc. (REMI) structural economic
forecasting and policy analysis model, which integrates input-output,
computable general equilibrium, econometric, and economic geography
methodologies. Costs were estimated by five size classes of firms. It
was noted that the annualized compliance costs of the proposed rule:
...also represent new demand for private sector goods and
services for firms who assist businesses affected by the new PEL in
complying with the proposed rule. In the BSIM, this new demand for
goods and services provided by the private sector acts as a
countervailing force to any negative impact on employers the new
annualized compliance costs may have (Document ID 2210, Attachment
2, p. 8).
The summary findings of the NFIB Research Foundation study included
an overall loss of 27,000 jobs and lost output of over $72 billion in
the long run, with at least half the loss expected to occur in the
small business sector.
The American Chemistry Council (ACC) (Document ID 4209-A1) reported
on Mr. Sessions's post-hearing brief (Document ID 4231), which provided
estimates of the economic and employment impacts of the general
industry costs to comply with the proposed silica rule and, in
addition, criticized Inforum's estimates of the employment effects of
the proposed silica rule (Inforum, 2011, Document ID 1701).
Mr. Sessions estimated economic impacts based on the URS
Corporation estimates of $6.131 billion as the cost of the proposed
silica rule on 19 general industry sectors (Document ID 4209-1, pp.
102-103). (Note that the analysis does not include the construction
sector and is more than 50 times higher than OSHA's general industry
cost estimate in the proposal). The economic impacts were estimated in
two analytical steps: (1) estimate the impact of the proposed
regulation's compliance costs on the value of output of the affected
industries; and (2) estimate how the expected changes in output will
reverberate throughout the economy, using IMPLAN--a well-known input-
output model of the U.S. economy.
The first step was achieved by estimating the amount of cost pass-
through of the compliance costs, using a supply elasticity of 1.0, and
then estimating the demand response to this price increase assuming a
demand elasticity of -1.5. This results in a decline in industry
revenue equal to about 20 percent of annualized compliance costs,
which--given URS's estimates of compliance costs--is equal to $1.23
billion per year. Again using the IMPLAN model, the corresponding
estimated employment effect is 18,000 lost jobs annually (5,400 direct
effect; 5,000 indirect effect; and 7,500 induced effect) and a loss in
economic output/GDP of more than $1.6 billion per year.
Additionally, Mr. Sessions reviewed Inforum's analysis of the
employment impacts of the proposed rule. He asserted that OSHA had
supplied Inforum with year-by-year compliance costs that were only 53
percent of the annualized costs that OSHA had estimated in the PEA so
that Inforum's projections of employment effects would be seriously
underestimated:
OSHA estimates the cost of the Proposed Standard to be $658
million per year in 2009 dollars on an annualized basis, excluding
the hydraulic fracturing industry. Assuming a 7%/year discount rate,
this annual cost, continuing forever as OSHA estimates it will, is
equivalent to a present value cost of $9.4 billion dollars in the
initial year of compliance. For comparison with this figure, I
calculate (also assuming a 7% discount rate) that the present value
in the first year for the ten-year schedule of compliance costs
shown in Inforum's Table 1 is only $5.0 billion [italics added]
(Document ID 4231).
In reviewing the above procedures, OSHA concludes that Mr. Sessions
has misinterpreted his own calculations. The annualized value of an
infinite series of costs (i.e., continuing forever) discounted at 7
percent is equal to 0.07 (the annualization factor) x the present value
(PV). Hence, the annualized cost of Mr. Session's present value of $9.4
billion should equal $658 million. Now, OSHA provided a stream of costs
for 10 years, not forever. The annualization factor for annualized
costs incurred over ten years using a 7 percent discount rate is equal
to 0.1424. Therefore, the PV of OSHA's costs given to Inforum should be
$658 million/0.1424, or about $4.6 billion. Mr. Sessions only confused
issues by using first-year costs (which is irrelevant to his exercise)
rather than annualized costs. So, there is nothing in Mr. Sessions's
calculations that would suggest that OSHA had provided Inforum with
seriously incomplete costs. However, just to make sure, OSHA and ERG
also reviewed the year-by-year proposal cost data given to Inforum (for
Inforum, 2011, Document ID 1701) and found nothing amiss.
The Construction Industry Safety Coalition, submitted a late
comment on the silica proposal (CISC, 2015), which contains estimates
prepared by Environomics, Inc. (Environomics, 2015) of the employment
impacts of the proposed silica rule on the construction sector
(Document ID 4242). This late comment, including the contained
Environomics study, has been excluded from OSHA decision-making
consideration, but is presented here for informational purposes only.
The employment effects estimated by Environomics (2015) reflect
annual costs to construction industries of $4.9 billion, which includes
almost $3.9 billion of direct compliance costs to construction
employers and another $1.05 billion of costs passed through from
general industry (as a result of the silica rule for general industry)
to the construction industry (Document ID 4242). Environomics used the
IMPLAN model to translate the estimated $4.9 billion annual cost of the
silica rule into more than 52,700 lost jobs related to the construction
industry. These job losses would consist of about 20,800 in
construction; 12,180 additional jobs lost in industries that supply
materials, products, and services to the construction industry; and
nearly 20,000 further jobs lost when those who lose their jobs in
construction and supplier industries no longer have earnings to spend
(i.e., "induced" jobs). Furthermore, Environomics argued that
"(t)hese job figures are expressed on a full-time equivalent basis.
Given the number of part-time and seasonal jobs in construction, the
number of actual workers and actual jobs affected will be much more
than 52,700" (Environomics, 2015, Document ID 4242, p. 2).
c. Inforum Analysis of Employment Effects of the Final Silica Rule
In December 2015, OSHA directed Inforum to run its macroeconomic
model to estimate the industry and aggregate employment impacts on the
U.S. economy of the cost of OSHA's final silica rule.\85\ The Agency
believes that the specific model of the U.S. economy that Inforum
uses--called the LIFT (Long-term Interindustry Forecasting Tool)
model--is particularly suitable for this work because it combines the
industry detail of a pure input-output model (which shows, in matrix
form, how the output of each industry serves as inputs in other
industries) with macroeconomic modeling of demand, investment, and
other macroeconomic parameters.\86\ The Inforum model can thus both
trace changes in particular industries through their effect on other
industries and also examine the effects of these changes on aggregate
demand, imports, exports, and investment, and in turn determine net
changes to Gross Domestic Product (GDP), employment, prices, etc.
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\85\ The estimated cost of the final rule that OSHA provided
Inforum was about $962 in annualized terms in December 2015. The
final cost presented in the FEA is about $1,030 million in
annualized terms, or about 7 percent ($68 million) higher than the
costs used by Inforum to estimate the employment effects of the
final rule. OSHA believes that if the most recent cost estimates had
been used, they would have had a minor effect on Inforum's estimate
of the employment impact of the final rule.
\86\ The LIFT model combines a dynamic input-output (I-O) core
for 110 productive sectors with a full macroeconomic model with more
than 1,200 macroeconomic variables that are consistent with the
National Income and Product Accounts (NIPA) and other published
data. LIFT employs a "bottom-up" regression approach to
macroeconomic modeling (so that aggregate investment, employment,
and exports, for example, are the sum of investment and employment
by industry and exports by commodity). Unlike some simpler
forecasting models, price effects are embedded in the model and the
results are time-dependent (that is, they are not static or steady-
state, but present year-by-year estimates of impacts consistent with
economic conditions at the time).
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Using industry-by-industry compliance cost estimates provided by
OSHA,\87\ Inforum employed the LIFT model of the U.S. economy to
compute the industry-level and macroeconomic impacts expected to follow
implementation of the silica standard. The general methodology was to
embed the compliance costs into the industry price functions of the
LIFT model, solve the equations of the model with the additional costs
included in the calculations, and then compare the simulation to a
baseline scenario which did not include the additional costs.
Enforcement of the rule was assumed to start in 2017 in construction
and in 2018 in general industry and maritime (with enforcement of
engineering control requirements for hydraulic fracturing activities
beginning in 2021). The timing of the compliance costs reflected the
phased-in enforcement of the rule, and the LIFT model results were
calculated over a ten-year horizon, that is, through 2026.
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\87\ OSHA contractor ERG provided silica-rule compliance cost
data for 13 segments of the construction sector plus construction
activity by state and local governments, and for 102 industrial
sectors. The costs were specified in 2012 dollars and covered a 10
year horizon, beginning with the implementation of the rule. The
data covered eight cost types and were classified as intermediate,
capital, and direct labor costs. In order to integrate the
compliance costs within the LIFT model framework, Inforum
established a mapping between the OSHA NAICS-based industries and
the LIFT production sectors. See Inforum (2016) for a discussion of
these and other transformations of OSHA's cost estimates to conform
to the specifications of the LIFT model.
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The most significant Inforum result is that the final silica rule
cumulatively generates an additional 9,500 job-years over the period
2017-2026, or an additional 950 job-years annually, on average, over
the period (Inforum, 2016). It should be noted, however, that these
results vary significantly from year to year. For example, in 2017, the
first year in which the silica final rule would be in effect and when
most capital costs for control equipment would be incurred, an
additional 21,100 job-years would be generated as a result of the
silica rule. Then, through 2026, the change in job-years relative to
the baseline ranges from a high of 19,600 (in 2019) to a low of -17,300
(in 2020).\88\ Inforum emphasized that all of these estimated job-year
impacts of the silica rule, both positive and negative, should be
viewed as negligible--relative to total U.S. employment of between 157
and 168 million workers during the time period under consideration and
not statistically different from an estimate of 0 job-years (that is,
that the silica rule would have no job impact).
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\88\ The fluctuations in employment from year to year as a
result of the proposed rule reflect how the Inforum model works. The
model has large short-term multipliers (from the initial increase in
compliance expenditures) but long-term stabilizers to return to an
equilibrium output and employment level. Hence, the short-term
multipliers may cause output and employment to overshoot in one year
and adjust in the other direction in the next year or two as the
model (and the real-world economy) equilibrates.
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The employment impacts of the silica rule would also vary
significantly from industry to industry and from sector to sector. For
example, for the period 2017-2026, the construction industry would, on
average, gain 4,260 job-years annually while the rest of the U.S.
economy would, on average, lose 3,310 job-years annually. Again,
relative to total employment in the construction sector of about 10
million workers and employment in the rest of the U.S. economy of about
150 million workers over the 10-year period, these employment impacts
should be considered negligible. For a fuller discussion of OSHA's
estimate of the employment and other macroeconomic impacts of the
silica rule, see Inforum (2016).
One obvious question is why the employment impacts of the silica
rule would be positive in construction and negative elsewhere. There
seem to be two major reasons. One is that, as reflected in the Inforum
model, there is little foreign competition in U.S. construction and the
price elasticity of demand in construction is extremely low relative to
demand for products in most other industries. Hence, output and
employment would be expected to decline minimally in response to any
price increase if employers in construction pass on the costs of the
silica rule. Second, and probably more important, in OSHA's view,
compliance with many of the provisions in the silica rule is relatively
labor-intensive, often requiring the application of additional labor in
the regulated firms themselves. Examples would include time spent for
training, medical surveillance, and activities to meet the PEL (such as
setting up and using control equipment and performing housekeeping
tasks). The increased labor required to produce a unit of output in
regulated firms would tend to increase employment in those industries
(holding output constant). This is particularly true in construction,
where compliance with the PEL would be much more labor-intensive--both
because engineering controls in construction are typically mobile and
require more worker activity and because housekeeping and other worker
actions are expected to play a larger role in achieving compliance with
the PEL. By comparison, engineering control equipment in general
industry/maritime is usually in a fixed location (eliminating the need
for workers to move the equipment) and worker actions would play a
smaller role in achieving compliance with the PEL.
Finally, OSHA turns to a critique of the commenters' analysis of
employment effects of the proposed silica rule relative to Inforum's
analysis of employment effects of the final silica rule. This critique
reflects comments provided in the Inforum report (Inforum, 2016).
The NFIB Research Foundation Analysis: Although the NFIB Research
Foundation study (Document ID 2210, Attachment 2) reported that careful
attention was given to the analysis of costs and their attribution by
firm size, it doesn't offer much information on how the BSIM model
works or how the results were obtained. "From what is generally known
about the REMI model upon which it is based, the general mechanism is
probably the sequence of (1) increased costs leading to (2) increased
output price leading to (3) reduced demand and therefore jobs"
(Inforum, 2016, p. 8). The study does acknowledge that the costs also
represent new private sector demand for firms that assist affected
employers in complying with the new PEL, but the purported positive
impacts of this private sector demand are not visible in the study.
Presumably the reported impacts are net effects that combine the
negative effects from the increased prices and reduced demand of the
affected sectors with the stimulus from spending on the supplying
sectors; however, that is not clear, and the stimulus is not
quantified. In Inforum's analysis (Inforum, 2016), these effects are
explicitly considered, both for intermediate goods and services as well
as investment.
Another important difference from Inforum's analysis is that the
NFIB study did not attempt to quantify the additional jobs created in
the affected industries. In Inforum's LIFT model, these were captured
as changes in labor productivity. For several industries, especially
construction, although the industry does experience increased costs, it
must also hire more workers to comply with the silica rule. The
additional jobs required in the affected industries are not discussed
or apparently modeled in the NFIB study. In summary, it seems that the
counteracting influences due to intermediate and investment related
purchases from other industries, and the job-creating expenditures in
the affected industries were not, in fact, captured in the study.
The CISC and ACC Studies: These two studies are being critiqued
together because they both rely on costs many times higher than OSHA's
estimates and because they both made projections using the IMPLAN
model.
What accounts for the difference between LIFT simulations and the
CISC and ACC estimates? There are several factors at play:
Probably most importantly, CISC's estimate starts with annual
compliance costs for the construction industry that are nearly 7 times
larger than OSHA's estimates for the construction industry (only) ($4.1
billion vs. an average of over $600 million, both in 2012 dollars).
Meanwhile, the ACC study estimates costs for general industry that are
more than 16 times larger than OSHA's estimates for the final rule
($6.1 billion in 2009 dollars versus $359 million in 2012 dollars.
Moreover, the CISC and ACC studies assumes that the same annualized
cost estimates are imposed each year, whereas the OSHA cost estimates
vary over the 10 year time period, with peak costs occurring in the
first year.
Neither the CISC nor the ACC application of the IMPLAN model
accounted for the increase in demand for capital equipment and
intermediate goods and services needed to comply with the proposed
silica rule. Thus, the employment and income boosting impacts of these
expenditures are not captured in their analysis. In contrast, Inforum's
methodology uses an explicit price function where annual compliance
costs by industry change commodity prices in proportion to their share
of total annual gross costs. In turn, price changes affect production
and employment through a dynamic general equilibrium framework. Demand
and supply price elasticities in the LIFT model are composites of
several sets of empirically estimated functions for final demand,
exports, imports, and price mark-ups. Furthermore, the parameters of
these functions vary by type of product according to the econometric
estimation.
At OSHA's request, Inforum made a separate run using the LIFT model
in the absence of the final silica rule for the construction industry
but with the final silica rule for general industry and maritime. The
purpose of this run was to calculate the indirect effects (only) of the
final silica rule for general industry and maritime on prices and
employment in the construction industry (Inforum, 2016). This LIFT
simulation estimated that the final silica rule for general industry
and maritime indirectly increased prices in the construction industry
by an average of .005 percent. The direction, if not the magnitude of
this effect, is consistent with the CISC/Environomics results
(Environomics, 2015, Document ID 4242). This led to a modest decline in
construction output and construction jobs. As shown in Table 9 of the
Inforum report (Inforum, 2016), the decline in jobs varied from +290 to
-940 a year over the period 2017 to 2026, with a cumulative job impact
of -4.8 thousand jobs over the 10-year period. Again, it should be
emphasized that this separate run was made in the absence of the final
silica rule for the construction industry.\89\
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\89\ As shown in Table 6 of the Inforum report, the cumulative
effect of the final rule for general industry, maritime, and
construction is to increase construction employment by 42,600 job
years over the 10-year time period, or about 4,260 jobs a year, on
average. Hence, the cumulative effect of the final rule for
construction alone is to increase construction employment by about
47,400 (42,600 + 4,800) jobs, or about 4,740 jobs a year, to the
extent that the two components are additive.
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The IMPLAN model is static and cannot compute employment and output
impacts over time, and it cannot show how the economy evolves to cope
with changes in costs. In order to extrapolate over ten years, the
authors simply multiply the first year effects by 10. The results are
implausible for a dynamic economy as the full static one-year impact is
unlikely to be the average impact over the course of several years. At
least theoretically, the economy contains powerful forces pushing it
towards full employment equilibrium. Therefore, most changes to output
and employment due to cost or demand shocks tend to be neutralized
through time. That is, most impacts, negative or positive, will
approach zero over the long term. Indeed, Inforum's LIFT model produces
dynamic results that vary from year to year, which is consistent with
fluctuations in the state of the economy and with short and long term
expenditure effects. It shows how the employment is reallocated among
industries and how the economy eventually will return to the baseline,
or potential, level of employment.
While the IMPLAN study places the regulatory analysis within the
context of the overall economy, it does not take full advantage of the
framework. For instance, given data for gross output in the base year
it is possible to compute the industry price effect so that the revenue
shocks can be judged relative to a price elasticity of demand. Instead,
the study employs an unrealistically large construct of a 5 to 1
compliance cost to revenue loss. Finally, the IMPLAN model's inability
to model the long-term properties of the economy severely undermines
the study's conclusion of long term cost to the economy.
G. Benefits and Net Benefits
In this section, OSHA discusses the benefits and net benefits of
the final silica rule. To set out an approach to estimate the benefits,
the Agency will, in the following sections, estimate the number of
silica-related diseases prevented as a result of the rule, estimate the
timing of the potentially avoided diseases, monetize their economic
value, and discount them. Taking into account the estimated costs of
the final rule, presented in Chapter V of the FEA, OSHA will then
estimate the net benefits and incremental benefits of the rule.
Finally, the Agency will assess the sensitivity of the estimates to
changes in various cost and benefit parameters.
This section presents OSHA's quantitative estimates of what rule-
induced benefits would be under certain assumptions. OSHA acknowledges
that these estimates are heavily influenced by the underlying
assumptions, and also that the long time frame of this analysis (60
years) is a source of uncertainty. The assumptions underlying these
estimates of deaths and morbidity avoided will be discussed in detail
as they appear in the remainder of this chapter, but the major ones are
as follows:
The exposure profile and other industrial profile data
presented in Chapter III of the FEA reflect both current conditions and
future conditions (extending over the next sixty years);
To separate the effects of this new rule from the effects
of compliance with existing standards, it is assumed that any workers
currently exposed above the preceding PEL are exposed to levels of
silica that exactly meet the preceding PEL;
The rule will result in workers being exposed at the new
PEL but will never reduce exposures below the new PEL;
Workers have identical exposure tenures (45 years, except
where otherwise noted);
The effects of baseline respirator use on risk are
ignored; and
The assumptions inherent in developing the exposure-
response functions discussed in Section VI, presented in Table VI-1 of
this preamble, are reasonable throughout the exposure ranges relevant
to this benefits analysis. (The reasonableness of these assumptions is
discussed in Section VI.)
The first two assumptions are also the basis for the cost analysis
in Chapter V of the FEA. The basis for the last assumption is discussed
in greater detail in Section VI of this preamble and will be briefly
reviewed in this section. It bears emphasis, however, that the sources
of data for OSHA's benefits analysis are the same as those used in the
Quantitative Risk Assessment (Section VI of this preamble) and the
technological feasibility analysis in Chapter IV of the FEA.
While OSHA did not quantify the benefits of the ancillary
provisions, consistent with the statute (29 U.S.C. 655(b)(7), section
6(b)(7)), the Agency finds that these provisions are beneficial and
necessary in order for the standard to be fully and correctly
implemented and for the full benefits of the rule to be realized. On
the whole, OSHA intends the requirements for training on control
measures, housekeeping, and other ancillary provisions of the rule to
apply where those measures are used to limit exposures. Without
effective training on use of engineering controls, for example, it is
unreasonable to expect that such controls will be used properly and
consistently. The ancillary provisions found in the rule are generally
standard and common throughout OSHA regulations.
The provision requiring exposure assessment in general industry is
integral to determining the engineering controls and work practices
needed to control employee exposure to the new PEL, to evaluate the
effectiveness of the required engineering and work practice controls,
and to determine whether additional controls must be instituted. In
addition, monitoring is necessary to determine which respirator, if
any, must be used by the employee, and it is also necessary for
compliance purposes.
The requirement for regulated areas in general industry and
maritime serves several important purposes including alerting employees
to the presence of respirable crystalline silica at levels above the
PEL, restricting the number of people potentially exposed to respirable
crystalline silica at levels above the PEL, and ensuring that those who
must be exposed are properly protected. Similarly, the competent person
requirement in the construction standard will protect bystanders by
restricting access to work areas only when necessary, benefiting those
bystanders through reduced exposures.
Written exposure control plans provide a systematic approach for
ensuring proper function of engineering controls and effective work
practices that can prevent overexposures from occurring. OSHA expects a
written exposure control plan will be instrumental in ensuring that
employers comprehensively and consistently protect their employees.
The medical surveillance provisions have the potential to protect
workers through the early detection of silica-related illnesses and
will enable employees to take actions in response to information about
their health status gleaned from medical surveillance. Additionally, by
requiring medical surveillance to general industry and maritime workers
exposed at or above the action level, OSHA provides an incentive for
employers to further reduce exposures, where possible, to avoid
incurring the costs of medical surveillance.
1. Estimates of the Number of Avoided Cases of Silica-Related Disease
For reasons described in detail in this preamble, OSHA has adopted
a PEL of 50 [mu]g/m\3\ in its silica standards covering general
industry, maritime, and construction, along with an alternative method
of compliance (Table 1) in construction. Analogous to the estimates in
the PEA, OSHA has calculated estimates of the benefits associated with
the PEL of 50 [mu]g/m\3\ for respirable crystalline silica, and
corresponding Table 1 in construction, by applying the dose-response
relationships developed in OSHA's quantitative risk assessment (QRA) to
exposures at or below the preceding PELs.
a. Exposure Profiles
OSHA determined exposure levels at or below the preceding PELs by
first developing an exposure profile of current exposures for
industries with workers exposed to respirable crystalline silica, using
OSHA inspection and site-visit data, and then applying this exposure
profile to the total current worker population. The industry-by-
industry exposure profile is presented in Chapter III of the FEA.
Because OSHA relied solely on measurement of airborne exposures,
respirator use may result in lower baseline exposures inside the
respirator than would be indicated by the airborne exposures
measurements. The extent to which this affects OSHA's benefits
calculations depends on the extent to which there was baseline
respirator use in the risk assessment studies OSHA relied on and how
these studies accounted for respirator use, if they did so at all. OSHA
reviewed the risk assessment studies it is relying on as well as
earlier studies that described the source of exposure data for each
cohort and how exposures were estimated for cohort members to determine
whether respirator use was accounted for. OSHA found that the
overwhelming majority of studies did not mention either respirator use
or how they accounted for respirator use, even though many took place
in time periods and at exposures levels where some respirator use could
have been expected. Some studies accounted for use of "dust controls"
but did not state whether these "dust controls" included respirator
use. Two studies (Rando et al. 2001, Document ID 0415), whose exposure
estimates for North American industrial sand workers were used by
Hughes et al. (2001, Document ID 1060), and Dosemeci et al. (1993),
whose exposure estimates for Chinese mine and pottery workers were
modified and used by Chen et al. (2001, Document ID 0332; 2005,
Document ID 0985), mention adjusting exposure estimates to account for
respirator use, but did not discuss in detail how these adjustments
were calculated. Most studies OSHA relied on, directly or indirectly,
cover long periods of time, over which respirator use varied. Most
cover some time after OSHA set a general industry PEL of approximately
100 [mu]g/m\3\ and required the use of a respirator if that exposure
level was exceeded. In summary, OSHA does not know the extent of
respirator use in the risk assessment studies relied on for the
benefits analysis, nor how they might differ from current respirator
use. As a result, OSHA is unable to accurately adjust its estimates to
account for baseline respirator use.
OSHA also is not able to quantify the effectiveness of respirator
use. (OSHA regulations provide for assigned protection factors, but
these are based on ideal conditions rather than real world conditions.)
It is thus difficult to know how to correct for possible respirator
use. As will be discussed below, OSHA estimates benefits relative to a
baseline characterized by compliance with the preceding PEL. The
preceding PEL in construction and maritime is approximately 250 [mu]g/
m\3\. If respirators have a protection factor of five, then they would
be equivalent to the new PEL of 50 [mu]g/m\3\ if fully effective at 250
[mu]g/m\3\. In general industry there is a preceding PEL of
approximately 100 [mu]g/m\3\. If respirators have a protection factor
of two, then they would be equivalent to the new PEL of 50 [mu]g/m\3\,
if fully effective. Beyond this, OSHA does not have the data to
quantify the effects of respirator use because it is well known that in
actual practice in work settings, respirators are not always as
protective as the assigned protection factors would indicate. For the
purpose of estimating the health benefits of the final rule, exposures
above the relevant preceding PELs were set at the relevant preceding PEL;
for purposes of comparing the effects of the preceding and the new
standards, the analysis thus assumes full compliance with both, without
taking baseline respirator use into account.
By applying the dose-response relationships from the literature to
estimates of exposures at or below the preceding PELs across
industries, it is possible to estimate the number of cases of the
following diseases expected to occur in the worker population given
exposures at or below the preceding PELs (the "baseline"):
fatal cases of lung cancer,
fatal cases of non-malignant respiratory disease (NMRD)
(including silicosis),
fatal cases of end-stage renal disease, and
cases of silicosis morbidity.
Non-fatal cases of lung cancer, NMRD and end-stage renal disease
were not estimated. In that respect, the estimates of the benefits are
understated. However, OSHA's benefits calculations do not, for example,
factor in any impact on the rule's implementation of the following
aspect of the Agency's enforcement approach: As a general matter, where
compliance with a standard's requirement clearly creates a new hazard,
employers can raise a defense that compliance with the requirement is
not feasible, and OSHA would work with the employer to implement an
alternative means of protection that does not create a serious
hazard.\90\
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\90\ In FEA Chapter IV, OSHA responds to commenters who have
stated that safety hazards would increase in the presence of the
rule (due to, for instance, use of wet methods on roofs) by
suggesting technologically feasible alternatives, including using
wet methods or exhaust ventilation on the ground or on platforms or
scaffolds. Other commenters also described how fall protection on
roofs was already being used where wet methods are employed.
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In a comment suggesting that some reductions in exposures (and thus
some benefits) were not included in OSHA's analysis, Dr. Ruth
Ruttenberg noted that "OSHA/ERG did not consider stomach cancer,
autoimmune disease, and other cancer and non-cancer health effects of
silica exposure" (Document ID 2256, Attachment 4, p. 11). These
potential benefits were not quantified, for the PEA or FEA, because the
Agency does not, at this time, have sufficient exposure-response data
to perform a quantitative risk assessment for these illnesses. The
Health Effects and Significance of Risk section of this preamble
contain a more detailed discussion of these potential silica-related
health effects that were not quantified.
b. OSHA's Method for Using Risk Models and Exposure Profile To Estimate
Cases Avoided as a Result of the Rule
The core of OSHA's methodology for benefits analysis is to
calculate the number of estimated premature deaths and illness cases
avoided as a result of the new rule. To do this, OSHA estimates the
expected number of mortality and morbidity cases expected to occur
under the assumption that the preceding PEL is being met (i.e., those
workplaces where the preceding PEL is currently exceeded are set equal
to the preceding PEL), and then subtract the expected number of
mortality and morbidity cases estimated to occur with the new rule in
place. OSHA then estimates the numbers of disease cases and deaths that
would result after the new standard goes into effect (i.e., assuming
full compliance in that no worker will be exposed in excess of the new
PEL). For this purpose, OSHA assumes all exposures above the new PEL
are reduced to the new PEL of 50 [mu]g/m\3\. The difference between
these estimates represents the numbers of disease cases and deaths that
the Agency estimates would be avoided as a result of issuing the new
standard. That is, this approach focuses on calculating estimates
derived from eliminating those exposures between the preceding PEL and
the new PEL. As explained later, these estimated mortality and
morbidity cases avoided are then monetized to comprise the benefits (in
dollar terms) of the rule.
By focusing on exposures between the preceding PEL (even for
workers exposed above the preceding PEL) and the new PEL exclusively,
and ignoring the possibility that workers' exposures are reduced below
the new PEL, OSHA's calculations will have a tendency toward
underestimation. Some exposures may be reduced to below the new PEL of
50 [mu]g/m\3\ as a result of engineering controls that do more than
needed. Also, some exposures below the new PEL of 50 [mu]g/m\3\ may be
reduced further due to "bystander effects," by which those already
exposed below the new PEL but working near other exposed workers would
have their exposures reduced further.
In order to estimate the number of deaths prevented, OSHA uses a
lifetime risk model, which is a mathematical framework that explicitly
follows workers from the beginning of their work lives until
retirement. Workers are assumed to start work at age 20 and work
continuously until age 65, resulting in a 45-year work life, and then
assumed to live another 15 years post-retirement, or until age 80. This
estimate is useful because the OSH Act requires OSHA to examine
exposures for an entire working life. Shorter job tenures will be
discussed further below.
Using this model, OSHA calculates the workers' cumulative workplace
exposures to silica, and estimates the probability of their dying each
year from silica-related diseases. The model also establishes the
background probability of the workers' dying from non-silica-related
causes. The increase in the workers' probability of dying due to
cumulative silica exposure in the workplace is added to this background
probability. As will be explained in more detail later, the difference
in these probabilities is used to form the basis for estimating the
number of illnesses and deaths due to silica exposures as they
currently exist and the estimated number of illnesses and deaths that
would be avoided when the standard is fully in effect, assuming full
compliance.
The background, age-specific survival probabilities are based on
the current (2011) U.S. (male) population, the latest year for which
age-specific all-cause mortality statistics are available.\91\ The
exposure-response functions for different diseases, which relate
cumulative silica exposure and increased probabilities of respective
disease endpoints, are drawn from specific studies discussed in this
preamble, Section VI--Final Quantitative Risk Assessment and
Significance of Risk.\92\ Estimates of the number of cases of silicosis
prevented by the new standard were also based on cumulative risk models
taken from several morbidity studies, but were not used in life table
analyses as was done for mortality (see Section VI of this preamble,
Final Quantitative Risk Assessment and Significance of Risk). The
exposure levels used in the model cover the U.S. exposure profile as
presented in Table III-9 in Chapter III Industry Profile of the FEA.
OSHA's exposure profiles for general industry and maritime and for
construction contain the estimated numbers of employees exposed within
specific bands of exposure levels: below 25 [mu]g/m\3\, 25 to 50 [mu]g/
m\3\, and above 50 [mu]g/m\3\ (in bands of 50 [mu]g/m\3\ to 100 [mu]g/
m\3\, 100 [mu]g/m\3\ to 250 [mu]g/m\3\, and above 250 [mu]g/m\3\,
whenever any of these bands are above the preceding PEL, OSHA lowered
the estimate for the band to the preceding PEL).
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\91\ Overall, approximately 3 percent of all construction
workers are women. (BLS, 2014--Labor Force Statistics from the
Current Population Survey, available at http://www.bls.gov/cps/cpsaat11.pdf).
There is no comparable breakdown for manufacturing occupations
as a whole but, for selected occupations for which data are
available, women are always fewer than 15 percent of the
relevant manufacturing workforce. OSHA used background mortality
rates for the U.S. male population because the cohorts in the key
studies used in the Agency's quantitative risk assessment were
composed overwhelmingly of male workers. OSHA used the exposure-
response models from these studies in a life table analysis to
estimate excess risk of disease mortality from exposure to
respirable crystalline silica after accounting for competing causes
of death due to background causes. Because, in most key studies, the
exposure-response models were built using data from male workers
only, it is unknown how these models would change for female
workers, or for mixed-gender populations, as it is not clear that
females would react to the silica exposure in the same exact way as
males. There is no such model data available for these cohorts.
Furthermore, OSHA believes that use of all-cause mortality data for
the U.S. population as a whole is not appropriate since the working
populations studied in the cohort studies, as well as the present
population of workers covered by the rule, are overwhelmingly male
and do not reflect the nearly equal proportion of males and females
represented by the all-cause mortality data for the U.S. population
as a whole. If one were to assume that the exposure-response model
for female workers was the same as that for male workers, then the
resulting relative risk (RR, the ratio of the risk of disease
mortality occurring in the exposed to the risk of disease mortality
occurring in the unexposed) for a particular cumulative exposure
would be the same. Because the risk of disease mortality in the
exposed population is calculated by multiplying the RR by the
background risk in the unexposed population, the risk of mortality
in the exposed population would be different between females and
males and would depend upon the background gender-specific disease
risks. Because the background cause-specific (e.g., lung cancer or
NMRD) mortality for females is generally lower than that for males,
the Agency would expect that the predicted risk of mortality to
exposed females may be slightly lower than that for exposed males.
On the other hand, this effect may be offset by female workers'
greater likelihood of surviving to the advanced age groups in which
silica-related diseases most typically appear in severe forms and
become a cause of death. Given the absence of exposure-response
models for female workers, which are required to estimate a proper
RR of disease for females, it is impossible to make any sound
conclusion on how the risk estimates would change for female
workers.
\92\ Specifically the low estimate for lung cancer uses
estimates from ToxaChemica (2004, Document ID 0469), the high
estimate for lung cancer uses Attfield and Costello (2004, Document
ID 0543), the renal disease estimate uses Steenland, Attfield, and
Mannetje (2002) (Document ID 1089), the morbidity estimate for
silicosis uses Buchanan, Miller, and Soutar (2003, Document ID
0306), and the mortality estimate for silicosis uses Mannetje, et.
al. (2002, Document ID 1089). See Section VI--Final Quantitative
Risk Assessment and Significance of Risk in this preamble for more
discussion.
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The results in Table III-9 in the FEA represent average daily
exposures in the risk model for general industry and maritime. In
construction, occupational exposure is commonly intermittent (i.e., not
occurring every workday), necessitating an adjustment to accurately
estimate these workers' cumulative exposure and risk. Workers in the
construction sector perform a multitude of tasks, only some of which
involve silica exposure. OSHA's estimated exposure levels represent the
8-hour time-weighted average of exposure on days when workers perform
tasks involving silica exposures. However, to account for the fact
that, in most affected construction occupations, workers do not do such
tasks every day, the cumulative exposure estimate for these workers
needed to be adjusted. To account for this intermittent exposure, the
risk model uses an adjustment factor which estimates the percentage of
days in which a worker will typically perform tasks that generate
silica exposures. These adjustment factors are generally based on the
proportion of time workers perform silica-generating activities along
with associated work crew sizes.\93\ So, for example, if, on average, a
group of workers is estimated to spend 20 percent of its time
performing tasks involving silica exposure, the model multiplies the
base exposure level--the exposure that the group of workers is
estimated to have based on the exposure profile--by this 20 percent. In
the Agency's model, this adjustment factor is calculated as the total
number of full time equivalent days that affected employees spend on
silica-related tasks divided by total affected employment as shown in
Chapter III of the FEA. For all construction occupations other than
hole drillers using hand-held drills, OSHA calculated an FTE adjustment
factor of 28 percent that was derived from the exposure profile. Hole
drillers using hand-held drills have a large number of employees and an
extremely low adjustment factor as compared to all other occupations.
Because the risk models are nonlinear, averaging such disparate groups
together provides unrepresentative results and therefore, this
occupation has its risk calculated separately. For hole drillers using
hand-held drills, OSHA calculated an adjustment factor of 3.5 percent.
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\93\ Detailed methodology and estimates for each occupation are
discussed in the construction engineering control cost section in
Chapter V of the FEA, in the subsection entitled "Aggregate `Key'
and `Secondary' Labor Costs for Representative Projects."
---------------------------------------------------------------------------
In order to calculate the number of expected and avoided cases for
each health outcome, OSHA assumes that all workers whose exposures fall
within a band are exposed the same and assigns the average of all
individual exposure observations within the relevant band (i.e., the
mean exposure) as the single point estimate within each band.\94\ This
point estimate of exposure is then used with the associated risk
estimate for each health outcome, which is multiplied by the estimated
number of workers exposed within the exposure band to calculate the
number of workers who experience that health outcome in the absence of
the new rule. For workers currently exposed above the new PEL, OSHA
assumes that their post-rule exposures will be lowered to the new PEL
of 50 [micro]g/m\3\. This reflects the fact that the Agency is taking
no benefits for reducing exposure above the previous PELs to the
previous PELs. The analysis starts from a baseline of the previous
PELs. A similar calculation is then performed at these new exposure
levels for these currently overexposed workers: The numbers of workers
exposed within each exposure band of the post-rule exposure profile is
then multiplied by the associated risk estimates for each health
outcome to yield estimates of the numbers of disease cases and
fatalities that will occur after the standard is implemented. Finally,
subtracting this post-implementation number of deaths and disease cases
from those estimated under baseline (pre-rule) conditions yields an
estimate of the number of deaths and illness cases averted due to the
standard.
---------------------------------------------------------------------------
\94\ Individual exposure data are presented within various
sections of Chapter IV, Technological Feasibility, of the FEA. All
individual observations are presented in Technical and Analytical
Support for OSHA's Final Economic Analysis for the Final Respirable
Crystalline Silica Standard: Excel Spreadsheets Supporting the FEA,
available in Docket OSHA-2010-0034 at www.regulations.gov.
---------------------------------------------------------------------------
As an example, Table VII-23-1 presents the summary calculations for
a risk model that produces one estimate of the number of lung cancer
deaths avoided by the revised standard for workers in general industry
if they were all exposed to silica for 45 years (this uses the
ToxaChemica 2004 risk model of lung cancer deaths avoided).
In Table VII-23-1, the total General Industry population at risk
for excess lung cancer is 291,019. There are 142,071 workers in the
range of silica exposure of below 25 [micro]g/m\3\, 51,377 workers
exposed between 25 and 50 [micro]g/m\3\, etc. The "Model Exposure
Level-Baseline" row provides the mean exposure level within each
range, which is the point estimate of exposure for which the associated
lifetime risk estimate is used to estimate the number of lung cancer
deaths that occur among workers exposed within each exposure range. For
example, from the exposure profile, the mean exposure for workers in
General Industry who are exposed below 25 [micro]g/m\3\ is 14 [micro]g/
m\3\, and the risk of lung cancer for all workers in this exposure band
is calculated from this average exposure of 14 [micro]g/m\3\. Though
the exposure profile includes 28,297 workers exposed in the range of
100-250 [micro]g/m\3\ and 28,443 workers exposed above 250 [micro]g/
m\3\, to estimate the number of baseline lung cancer deaths, those
workers' exposure levels are set at the preceding PEL of 100 [micro]g/m\3\.
In this example, estimated benefits due to the new PEL do not include
any benefits to workers for their exposures being reduced to the
preceding PEL; only those benefits associated with the exposure levels
being reduced from the preceding PEL or lower to the new PEL are
included in the estimates. The row labeled "Model Exposure Level-50 PEL"
shows the expected exposures among workers that result after the standard
is promulgated. Exposures of workers exposed below 50 [micro]g/m\3\ are
expected to remain unchanged while the exposures of all workers who are
currently exposed above 50 [micro]g/m\3\ are expected to be reduced to
the new PEL of 50 [micro]g/m\3\.\95\
---------------------------------------------------------------------------
\95\ For the purposes of estimating costs and benefits, OSHA
assumes full compliance with all applicable OSHA standards.
---------------------------------------------------------------------------
Table VII-23-1 also presents the estimated excess risk of lung
cancer per 1,000 workers for each exposure band and the number of lung
cancer deaths that would occur among workers exposed within each
exposure band for 45 years. For example, among workers exposed within
the lowest exposure band, the lifetime risk model estimates an
increased risk of lung cancer above the background mortality risk of
14.7 deaths per 1,000 workers at a constant exposure to 14 [micro]g/
m\3\ silica for 45 years. Multiplying this risk estimate by the number
of workers at risk in that exposure band (142,071) yields an estimated
2,084 lung cancer deaths. Doing the same across the various baseline
exposure level bands results in an estimated baseline total of 5,021
lung cancer deaths due to exposure to silica for the population of
workers at risk. The table shows similar estimated lung cancer risks
and estimated numbers of deaths in the post-standard scenario. For all
workers whose baseline 45-year exposures are at or above 50 [micro]g/
m\3\, the estimated risk of lung cancer associated with exposure at the
new PEL of 50 [micro]g/m\3\ is 19.0 per 1,000 workers. Multiplying this
risk by the number of workers exposed to silica at levels between 50
and 100 [micro]g/m\3\ (41,596), for example, yields an estimated 776
deaths occurring in this group for the post-standard scenario. Doing
the same for each exposure band for the post-standard scenario and
summing across all exposure bands, the number of estimated excess lung
cancer deaths post-standard is 4,858. The next two rows show the
difference between the baseline and the post-standard scenarios, both
for lung cancer death risks ("differential lung cancer death rate")
and numbers of deaths ("lung cancer deaths averted"). The final total
number of lung cancer deaths averted is 163. Dividing by the analytic
time horizon of 45 years results in about 4 annual deaths averted.
The preceding example assumes a constant exposure level each year
for 45 years. Elsewhere in this chapter, OSHA examines what would
happen if the day-to-day exposure remains the same but job tenure is
shorter. In order to have a valid comparison, OSHA compares each
scenario to what is estimated to happen over 45 years. All job tasks,
and hence cumulative exposure, do not change with decreased job tenure;
they are just spread over more workers. Thus, if OSHA were to examine a
job tenure of 25 years, almost twice as many workers would be exposed
for almost half as long as for the 45-year assumption. With a strictly
proportional (linear) risk function the benefits of having half the
exposure for twice the number of workers would exactly offset each
other and final benefits would be the same. Hence the net effect of
such changes is directly related to non-linearities in the various
lifetime risk models.
c. Results for Cases Avoided
OSHA received a number of comments concerning the Agency's
preliminary risk assessment and discussion of the health effects of
silica in this preamble to the proposed rule. Those comments are
discussed in detail in Sections V (Health Effects) and VI (Final
Quantitative Risk Assessment and Significance of Risk) of this preamble
to the final rule.
OSHA examined the various lung cancer risk models presented in its
QRA to estimate the benefits of lowering the PEL. As can be inferred
from Table VI-1 of the Final QRA, the ToxaChemica, Inc. (2004, Document
ID 0469) log-linear model estimated the lowest estimate of lung cancer
cases avoided from lowering the PEL to 50 or 100 [mu]g/m\3\, whereas
the Attfield and Costello (2004, Document ID 0543) model estimated the
highest number of lung cancer cases avoided. The remainder of the
studies indicated an intermediate reduction in risk. OSHA used the
ToxaChemica 2004 (log-linear model) and Attfield and Costello studies
to characterize a range of estimated lung cancer reduction,
acknowledging that neither of these estimates captures the full range
of uncertainty associated with the models and data used.
Table VII-24 shows the range of modeled estimates for the number of
avoided fatal lung cancers for PELs of 50 [mu]g/m\3\ and 100 [mu]g/m\3\
for the scenario in which workers are uniformly exposed to silica for
45 years. At the final PEL of 50 [mu]g/m\3\, the modeling approach
yields estimates of 2,921 to 8,246 lung cancers prevented over the
lifetime of the worker population, with a midpoint estimate of 5,584
fatal lung cancers prevented. This is the equivalent of between 65 and
183 cases avoided annually, with a midpoint estimate of 124 cases
avoided annually, given a 45-year working life of exposure.
Following Park (2002, Document ID 0405), as discussed in the
Agency's QRA, OSHA's estimation model suggests that the final PEL of 50
[mu]g/m\3\ would, in the scenario in which workers are uniformly
exposed to silica for 45 years, prevent 14,606 fatalities over the
lifetime of the worker population from non-malignant respiratory
diseases arising from silica exposure.\96\ This is equivalent to 325
fatal cases prevented annually. Some of these fatalities would be
classified as silicosis, but most would be classified as other
pneumoconiosis and chronic obstructive pulmonary disease (COPD), which
includes chronic bronchitis and emphysema. That is one reason why we
would expect this estimate to exceed the count based solely on death
certificates (for instance, in 2013, CDC's count based on state-
provided vital records is 111 deaths annually from silicosis in the
United States).
---------------------------------------------------------------------------
\96\ Park et al. (2002, Document ID 0405) also found that silica
exposure was responsible for a significant number of deaths that had
been attributed to diseases other than silicosis.
---------------------------------------------------------------------------
Certain commenters argued that the recent CDC count of silicosis
mortality from death certificates is evidence that OSHA's benefits were
overestimated.
Some commenters, such as the American Chemistry Council and Faten
Sabry, Ph.D., representing the Chamber of Commerce, argued--based on
the numbers of silicosis-related deaths recorded in recent years
reported in mortality surveillance data--that OSHA overestimated the
estimated benefits of the standard (Document ID 2263, p. 57; 3729, p.
1; 2288, Appendix 6; 4209, pp. 3-4). Dr. Sabry stated that the 52
deaths reported by the CDC in 2010 where silicosis was identified as an
underlying cause of death were considerably fewer than the number of
silicosis-related deaths that OSHA claimed would be avoided once the
proposed standard becomes fully implemented. Dr. Sabry concluded,
"[s]o, by OSHA's calculation, reducing the PEL to 50 [micro]g/m\3\
will prevent more silicosis-related deaths than actually occur in the
United States today--which suggests that OSHA's risk assessment is
faulty" (Document ID 2288, Appendix 6). The National Utility
Contractors Association (NUCA) made the same argument when it asserted:
"OSHA predicts that this proposed rule will prevent approximately 600
silica related deaths per year, but the CDC is recording less than 100
deaths per year" (Document ID 3729, p. 1). The National Federation of
Independent Business also argued that OSHA estimated 375 prevented
cases of silicosis that would have led to deaths, but the CDC reported
only about 150 deaths per year where silicosis was the underlying cause
or a contributing factor, causing OSHA to overestimate lives saved due
to the standard by about 150 percent (Document 2210, Attachment 1, p. 3).
OSHA disagrees that the silicosis mortality surveillance data alone
provides evidence that OSHA has overstated the quantitative benefits of
the rule. OSHA derived its benefits estimates from exposure data
presented in the Industry Profile chapter of the FEA and from its
quantitative risk assessment, which is based on epidemiological data
that quantify relationships between exposure and disease risk. OSHA
relied on these estimates to estimate the number of silicosis-related
deaths and illnesses that would occur absent a revised standard and the
number of deaths that would be avoided by promulgation of such a
standard. From this analysis, OSHA estimated that 325 deaths from
silicosis and other non-malignant lung disease and 918 silicosis
morbidity cases are estimated to be avoided annually once the full
effects of the standards are realized. The 52 deaths cited by Dr. Sabry
appears to refer to only the number of deaths with silicosis coded as
the "underlying" cause of death on death certificates, and does not
include deaths coded with silicosis as a "contributing" cause.
Combined with the deaths where silicosis is coded as a "contributing"
cause, in this case 49, CDC/NIOSH reported a total of 101 deaths where
silicosis was either an underlying cause of death or a contributing
cause of death.
OSHA's model does not only count fatalities related to silicosis.
OSHA's estimate of the impact of exposure to respirable crystalline
silica includes deaths from other diseases (lung cancer, non-malignant
respiratory disease such as chronic bronchitis and emphysema, and end-
stage renal disease) that, according to scientific evidence, can be
caused by exposure to respirable crystalline silica (Document ID 1711;
2175, p. 2). OSHA also estimated, based on the Park study discussed
previously, that 325 cases of fatal non-malignant respiratory diseases
associated with exposure to silica, including, but not limited to
silicosis, that would be prevented annually due to the final standard.
Thus, OSHA's estimates of the numbers of deaths prevented that are due
to non-malignant respiratory disease are not comparable to surveillance
statistics that only capture silicosis as a cause of death.
Furthermore, Dr. Sabry's comments are primarily focused on the
hydraulic fracturing industry, which only recently became a major
source of silica exposure, where most of the effects of current
exposures will likely not be seen for a number of years, underlining
why this analysis of past trends is not instructive for epidemiological
estimates.
In response to NUCA's comparison of OSHA's estimate of 679 deaths
avoided to the estimate of fewer than 100 deaths from the surveillance
data, the Agency again points out that the model accounts for causes of
death other than those resulting from silicosis and therefore reported
to CDC/NIOSH in the surveillance data. Therefore, NUCA's comparison is
faulty because focusing exclusively on silicosis mortality fails to
capture silicosis morbidity, as well as mortality and morbidity
resulting from other diseases related to silica exposure, including
lung cancer, other non-malignant respiratory disease such as chronic
bronchitis and emphysema, and renal disease (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk, Table VI-1).
George Kennedy of the National Utilities Contractor's Association
makes a similar "apples and oranges" error in his comment:
OSHA predicts that this rule will prevent approximately 600
silica-related deaths per year. But how is this possible if the CDC
is reporting less than 100? (Document ID 3583, p. 2240)
Mr. Kennedy's comment is based on comparing CDC counts of
documented silicosis fatality cases, but this count is not a report on
all silica-related deaths. The Agency's articulated need for the
standard, however, is based on the finding that silica exposure results
in an array of adverse, mutually independent health endpoints. In
contrast, the CDC estimate deals with a small part of the overall
health risk from silica exposure.
As also discussed in the Agency's QRA, OSHA finds that workers with
higher cumulative exposures to silica are at elevated risk of lung
cancer, end-stage renal disease, and non-malignant respiratory
diseases. Based on the midpoint of the lower high-end estimate
(Attfield and Costello, 2004, Document ID 0543) and a higher low-end
estimate (ToxaChemica log-linear model, Document ID 0469), OSHA's
estimation model estimates that the new PEL of 50 [mu]g/m\3\ would, in
the scenario in which workers are uniformly exposed to silica for 45
years prevent 5,584 cases of lung cancer, or about 124 cases annually
upon reaching "steady state" (see later discussion of this concept)
in 60 years. Based on Steenland, Attfield, and Mannetje (2002, Document
ID 1089), OSHA's estimation model estimates that the final PEL would
prevent 8,689 cases of end-stage renal disease, or about 193 cases
annually in steady state. And based on Park (2002, Document ID 0405),
OSHA's estimation model estimates that the new PEL would prevent 14,606
cases of non-malignant respiratory diseases (including silicosis) over
the lifetime of 45 cohorts' worth of worker population, or about 325
cases annually in steady state, of which 2,970 (66 annually) are
attributable to diagnosed cases of silicosis, based on Mannetje (2002,
Document ID 1089).
Combining the three major fatal health endpoints--lung cancer, non-
malignant respiratory diseases, and end-stage renal disease--OSHA's
modeling approach yields estimates that the new PEL would prevent
between 26,216 and 31,541 premature fatalities over the lifetime of the
current worker population, with a midpoint estimate of 28,879
fatalities prevented. This is the equivalent of between 583 and 701
premature fatalities avoided annually, with a midpoint estimate of 642
premature fatalities avoided annually, given a 45-year working life of
exposure.
In addition, the final silica rule is estimated to prevent a large
number of cases of silicosis morbidity. Table VII-25 is designed to
compare available estimates of actual silicosis cases to the estimates
generated by OSHA exposure profile and models. The first set of rows
compares present estimates of 2/1 and the second set of rows estimates
of 1/0 cases of silicosis generated by various risk models using OSHA's
exposure profile. Going across, the first columns are for a tenure
length of 45 years, the second set for a tenure length of 13 years.
Then below in the second panel, the final set of rows is based on
Rosenman, et al. (2003, Document ID 1166) estimates of actual silicosis
cases, generated with an alternative modeling approach. To be
consistent with OSHA's jurisdiction, OSHA revised Rosenman's estimate
to remove workers not in OSHA's jurisdiction, such as miners. The lower
panel, based on Rosenman, et al. (Document ID 1166), shows, assuming 45
years of exposure, that between 2,700 and 5,475 new cases of silicosis,
at an ILO x-ray rating of 1/0 or higher, are estimated to occur
annually at current exposure levels as a result of silica exposure at
establishments within OSHA's jurisdiction (i.e., excluding miners).\97\
The various models OSHA used yield estimates of between 836 and 8,011
cases, assuming 45 years of exposure and between 393 and 10,107 cases
assuming 13 years of exposure at an ILO x-ray rating of 1/0 or higher.
OSHA's risk models for morbidity using OSHA's exposure profile are thus
somewhat consistent with epidemiologically based estimates of silicosis
cases though some are a bit over the epidemiological estimates. When a
job tenure of 13 years is assumed, the table shows that for most
models, as compared to the 45 year job tenure analysis, the results are
a lower numbers of cases, while other models yield estimates of cases
within the range estimated by Rosenman for U.S. workers other than
miners (who are outside OSHA's jurisdiction.) There are, however,
exceptions. The estimated number of cases for some models falls below
Rosenman's estimates. On the other hand, two models show an increased
number of cases which are above the range of Rosenman's estimates. This
is a result of very high rates of cases expected to occur in persons
exposed at levels above the preceding PELs. Since OSHA does not
estimate benefits to workers exposed at levels above the preceding
PELs, any estimated increase in cases among such workers will not
affect OSHA's benefits analysis.
---------------------------------------------------------------------------
\97\ Rosenman indicated that the underlying cases of silicosis
morbidity have changed little over time, testifying that data from
the National Intake Survey indicated that the nationwide number of
hospitalizations where silicosis was one of the discharge diagnoses
has remained constant, with 2,028 hospitalizations reported in 1993
and 2,082 in 2011 (Document ID 3425, p. 2).
---------------------------------------------------------------------------
A number of commenters took issue with the general idea that
silicosis is an occupational health problem for workers whose exposures
to silica did not exceed the preceding PELs. These commenters typically
pointed to the significant decline in the number of silicosis deaths
reported by the CDC in the last few decades.
OSHA does not find these comments persuasive. As explained in depth
in the Health Effects and Risk Assessment sections of this preamble,
while the Agency welcomes any apparent decline in silicosis cases, the
Agency has substantial evidence that significant risk remains at
preceding PELs. The commenters do not account for the undercounting of
silicosis deaths from death certificates, as demonstrated by Rosenman
(Document ID 1166] and others; nor do they address other health
endpoints beyond fatal silicosis. Although the decline in reported
cases may indicate the Agency's success up to this point in reducing
the incidence of silicosis, it cannot be taken as an absolute measure
of how many silica-related disease cases currently exist in the
population. Most silicosis cases are not fatal--given that the total
cases of silicosis have apparently remained largely constant, fewer
silicosis fatalities may mean that more individuals are living with
silicosis for longer periods while ultimately dying of other
causes.\98\
---------------------------------------------------------------------------
\98\ As indicated previously, Rosenman found that the underlying
cases of silicosis morbidity have changed little over time,
remaining constant, even while reported fatalities have declined
(Document ID 3425, p. 2).
---------------------------------------------------------------------------
While OSHA has estimated morbidity from silicosis, it has not
attempted to estimate the number of morbidity cases from these other
health endpoints. Including these other endpoints would increase
estimates of the number of overall cases avoided.
As summarized in Table VII-25, OSHA expects that, in the scenario
in which workers are uniformly exposed to silica for 45 years, the
silica rule will eliminate the majority of 1/0, 1/1, and 1/2 silicosis
cases. However, the Agency has not included the elimination of these
less severe silicosis cases in its estimates of the monetized benefits
and net benefits of the final rule. Instead, as shown above in Table
VII-24, OSHA focused its morbidity-only benefits and related net
benefits analysis exclusively on the number of silicosis cases reaching
the more severe levels of 2/1 and above (moderate-to-severe silicosis,
using the ILO method for assessing severity). As discussed in the
Agency's QRA, OSHA estimates that the new PEL of 50 [mu]g/m\3\ for the
current worker population would, in the scenario in which workers are
uniformly exposed to silica for 45 years, prevent 41,293 cases of
moderate-to-severe silicosis (2/1 or more) over a working life, or
about 918 cases prevented annually.\99\
---------------------------------------------------------------------------
\99\ The unfiltered count of morbidity cases is reported only in
Table VII-25. The Agency believes the actual number of morbidity-
only cases prevented by the standard in the scenario in which
workers are uniformly exposed for 45 years is somewhere between 918
and 984 cases annually, using Mannetje (2002) (Document ID 1089) to
estimate the number of prevented silicosis fatalities (66) and
excluding these fatalities from the estimated "morbidity-only"
cases. While the Agency received no comment on its methodology for
counting morbidity cases, in preparing the FEA OSHA discovered that
the simultaneous accounting for morbidity in Buchanan's study of
coal miners (2003, Document ID 0306) and pre-mortality morbidity in
Park (2002) (Document ID 0405) could result in a potential double-
counting of morbidity valuation (discussed later in this chapter),
as some of the Buchanan's cases diagnosed with 2/0+ silicosis at
retirement could ultimately proceed to death. A precise estimate of
the morbidity-only cases is not possible, as Buchanan also excluded
a number of cases where the workers had already died, possibly from
silicosis, so that Buchanan was, in turn, likely underestimating the
total lifetime morbidity risk from silicosis. By relying on
Mannetje, OSHA avoids any potential double counting of benefits.
---------------------------------------------------------------------------
As previously discussed, OSHA based its estimates of reductions in
the number of silica-related diseases using estimates that reflect a
working life of constant exposure for workers who are employed in a
respirable crystalline silica-exposed occupation for their entire
working lives, from ages 20 to 65.\100\ In other words, these estimates
reflect an assumption that workers do not enter or exit jobs with
silica exposure mid-career or switch to other exposure groups during
their working lives. While the Agency is legally obligated to examine
the effect of exposures from a 45-year working lifetime of
exposure,\101\ for purely informational purposes, the Agency also
alternatively examined the effect of assuming that workers are exposed
to silica for three other tenure lengths: 25, 13, and 6.6 working years
(see Table VII-26a through Table VII-26c for number of cases and Table
VII-28a through Table VII-28d for monetary benefits for all four tenure
levels).
---------------------------------------------------------------------------
\100\ In construction, the analysis assumes that while workers
gain additional exposure annually, they are not necessarily exposed
to silica constantly, depending upon the demands of the job.
\101\ Section 6(b)(5) of the OSH Act states: "The Secretary, in
promulgating standards dealing with toxic materials or harmful
physical agents under this subsection, shall set the standard which
most adequately assures, to the extent feasible, on the basis of the
best available evidence, that no employee will suffer material
impairment of health or functional capacity even if such employee
has regular exposure to the hazard dealt with by such standard for
the period of his working life." Given that OSHA must analyze
significant risk over a working life, the Agency estimated benefits
for the affected population over the same period.
---------------------------------------------------------------------------
Table VII-26a presents cases for a worker exposed for 25 years.
While each individual worker is estimated to have less cumulative
exposure under the 25-years-of-exposure assumption, in fact 56 percent
(25/45) as much, the effective exposed population over time is
proportionately increased (due to the turnover of workforce for a
constant number of jobs, and hence total exposure), over the same time
period. A comparison of Table VII-26a to Table VII-24, reflecting
exposures over 25 working years versus 45 working years, shows
variations in the number of estimated prevented cases by health
outcome. Estimated prevented cases of fatal end-stage renal disease are
higher in the 25-year model, whereas cases of fatal non-malignant
respiratory disease and silicosis morbidity are lower. In the case of
lung cancer, the effect varies by model, with a decrease in the
Attfield and Costello, 2004 higher estimate (Document ID 0543) and an
increase in the ToxaChemica, 2004 lower estimate (Document ID 0469).
Looking at overall totals, the midpoint estimate of the number of
avoided fatalities under the new PEL of 50 [mu]g/m\3\ is 642 for 45
years, increasing to 772 for 25 years. For total morbidity, there
instead is a decrease: from 918 cases avoided for 45 years down to 443
cases avoided for 25 years, Table VII-26b presents results for 13 years
of exposure. For a 13 year job tenure, the midpoint for the number of
fatalities avoided is 982 while the total number morbidity cases
avoided is 246. Finally, Table VII-26c presents the results for 6.6
years of exposure. In this scenario, the midpoint for the number of
fatalities avoided is 1,382 and the total number of morbidity cases
avoided is 194. Looking across the tenure results shows that midpoint
mortality significantly increases with lower tenure, while total
morbidity has a large decrease with lower tenure.
A commenter, Joseph Liss, objected to the Agency's approach of
simultaneously increasing the estimated exposed population--not because
it was technically incorrect, but because it makes it harder to see the
difference in risk to a particular exposed population (Document ID
1950, pp. 16-19).
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
OSHA reported in the PEA that in the construction industry, which
has an unusually high rate of job turnover compared to other
industries, BLS data show that the mean job tenure with one's current
employer is 6.6 years (BLS, 2010a, Document ID 1620), and the median
age of construction workers in the U.S. is 41.6 years
(BLS, 2010b, Document ID 1672). OSHA further noted that BLS does
not have data on occupational tenure within an industry, but that
the Agency would expect that job tenure in the construction occupations
as a whole would be substantially greater than the job tenure with a
worker's current employer. None of the commenters disagreed.
Furthermore, many workers may return to the construction industry
after unemployment or work in another industry. Job tenure with the
current employer, however, is longer in the other industries affected
by the silica rule (BLS, 2010a, Document ID 1620).
Dr. Ronald Bird, submitting a comment on behalf of the U.S. Chamber
of Commerce--as well as an unaffiliated commenter, Joseph Liss--
suggested that OSHA's estimates of disease cases prevented from 45
years of silica exposure is unrepresentative of the typical tenure of
workers affected by the standard, particularly in construction
(Document ID 2368, p. 18; Document ID 1950, pp. 15-19). Dr. Bird
suggested that workers will routinely change occupations in the course
of their lifetime. From a probabilistic standpoint, he calculated that
workers would, on average, likely work in an occupation for less than
six years. The comments directly from the Chamber of Commerce go
further, to say that "[n]o such 45-year career silica exposures exist
in today's working world..." (Document ID 2288, p. 11).
The article (Rytina, 1983, Document ID 2368) that Dr. Bird cited
for his data on occupational turnover provides data that refute the
assumptions of Dr. Bird's model. While Dr. Bird assumes that
occupational turnover is constant without regard to age or length of
occupational experience, the Rytina article states:
Not surprisingly, occupational mobility rates declined sharply
with age...The rate for workers age 35-44 was less than one
fourth as high as that for workers 18 and 19 years of age. * * *
[O]ccupational change among older workers occurs less frequently
because of attachments to a particular occupation or the risks of
losing income, job security, and pension rights, which might
accompany an occupational shift (Rytina, 1983, Document ID 2368, p.
5).
Furthermore, the Rytina article shows that among workers 45 to 54
years of age, 16.5 percent of workers have been in the same occupation
for 25 years or more, and among workers 55 and older, 32.9 percent have
been in the same occupation for 25 years or more. By comparison, Dr.
Bird's model suggests that, regardless of age, no more than 13 percent
of workers will remain in a given occupation for more than 20 years.
Two commenters also provided evidence of the average tenures of
their workers that is contrary to Dr. Bird's estimates. The National
Industrial Sand Association (NISA) noted, "many NISA member company
employees work at their workplaces for all or much of their worklives.
In 2004, a study calculated the mean tenure for NISA member company
employees fitting the definition of the study's cohort to be 19.7
years" (Document ID 2195, p. 19). Southern Company, an electric
utility, noted that it "has approximately 8000 employees in job titles
performing activities with potential exposures to silica-containing
materials. The average tenure for these employees is 17 years; 37% of
these employees have over 20 years work experience" (Document ID 2185,
p. 3).
Other commenters provided evidence to refute the Chamber of
Commerce claim that that 45-year career silica exposures no longer
exist in today's working world (Document ID 2288, p. 11). During the
public hearing, participants on a panel comprised of members of the
International Union of Bricklayers and Allied Craftworkers (BAC) were
asked if they had colleagues who had worked longer than forty years in
their trade. All six of the participants affirmed that they did
(Document ID 3585, Tr. 3053). Further, several labor groups submitted
evidence of lengthy worker tenure. The BAC noted that:
A review of our International Pension Fund records documented
116 individuals who have worked for 40 years or more. We consider
this figure to understate the work lives of Fund participants
because many of these individuals had previous work experience in
the construction industry before being represented by BAC. In
additional, we believe this figure understates the number of
participants with work lives of 45 years, because the Fund was
established in 1972 and it was not until roughly a decade later that
even half of BAC affiliates had commenced participation in the Fund
(Document ID 4053, Attachment 1, p. 2).
Similarly, The United Association of Plumbers, Fitters, Welders,
and HVAC Service Techs, submitted that "a review of membership records
documented 35,649 active members who have worked 45 years or more while
they have been a member of the union." They also concur with the BAC
statement that the number may be understated given previous work
experience (Document ID 4073, Attachment 3, p. 1). And the
International Union of Operating Engineers' Central Pension Fund found
the average operating engineer has over 20 years of service in the
trade with a range up to 49.93 years (Document ID 4025, Attachment 1,
pp. 6-7).
Dr. Bird also objected to OSHA's approach of using a single
representative exposure to measure lifetime exposure. He states: "If
exposures are variable over the course of a year, the lifetime exposure
pattern is contrary to OSHA's assumption and the benefits from the
proposed reduction in the PEL would be considerably less" (Document ID
2368, p. 19). Dr. Bird apparently faults the Agency for not considering
the possibility that future exposures may be lower than those observed
on a given day. However, it is equally plausible that a worker's future
exposures may be higher than on the day they were observed by OSHA. The
single-day exposure data is the best available data in the record for
those workers, and the Agency does not find any persuasive evidence in
this record to suggest an obvious bias to characterizing exposure from
a single day rather over the course of consecutive days.
Paragraph (i)(2)(v) of the general industry and maritime standard
and paragraph (h)(2)(v) of the construction standard also contain
specific provisions for diagnosing latent tuberculosis (TB) in the
silica-exposed population and thereby reducing the risk of TB being
spread to the population at large. OSHA currently lacks good methods
for quantifying these benefits. Nor has the Agency attempted to assess
benefits directly stemming from enhanced medical surveillance in terms
of reducing the severity of symptoms from the illnesses that do result
from present or future exposure to silica. Dr. Ruth Ruttenberg, an
economist representing the AFL-CIO, noted this as a source of the
underestimation of the benefits in her comments (Document ID 2256,
Attachment 4, pp. 9-12). However, no commenters suggested how to
quantify these effects.
OSHA's risk estimates are based on application of exposure-response
models derived from several individual epidemiological studies as well
as the pooled cohort studies of Steenland et al. (2001, Document ID
0492) and Mannetje et al. (2002, Document ID 1089). OSHA recognizes
that there is uncertainty around any of the point estimates of risk
derived from any single study. In its preliminary risk assessment
(summarized in Section VI of this preamble), OSHA has made efforts to
characterize some of the more important sources of uncertainty to the
extent that available data permit. This specifically includes
characterizing statistical uncertainty by reporting the confidence
intervals around each of the risk estimates (presented in the
Preliminary Quantitative Risk Assessment, Document ID 1711); by
quantitatively evaluating the impact of uncertainties in underlying
exposure data used in the cohort studies; and by exploring the use
of alternative exposure-response model forms. OSHA finds that these
efforts reflect much, but not necessarily all, of the uncertainties
associated with the approaches taken by investigators in their
respective risk analyses. However, for reasons explained in Section VI
of this preamble, OSHA concludes that characterizing the risks and
benefits as a range of estimates derived from the full set of
available studies, rather than relying on any single study as the
basis for its estimates, better reflects the uncertainties in the
estimates and more fairly captures the range of risks likely to
exist across a wide range of industries and exposure situations.
Section VI of this preamble provides a more complete discussion of
the source of uncertainty in the risk assessment functions used in this
benefits analysis. The sources of uncertainty include the degree to
which OSHA's risk estimates reflect the risk of disease among workers
with widely varying exposure patterns. Some workers are exposed to
fairly high concentrations of crystalline silica only intermittently,
while others experience more regular and constant exposure. Risk models
employed in the quantitative assessment are based on a cumulative
exposure metric, which is the product of average daily silica
concentration and duration of worker exposure for a specific task.
Consequently, these models assume the same risk for a given cumulative
exposure regardless of the pattern of exposure, reflecting a worker's
long-term average exposure without regard to intermittencies or other
variances in exposure. That is, the use of the cumulative exposure
metric in these models assumes that there are no significant dose-rate
effects in the relationship between silica exposure and risk.
Possible dose-rate effects in the silica exposure-response
relationships, particularly for silicosis. OSHA's reliance on a
cumulative exposure metric to assess the risks of respirable
crystalline silica is discussed in Section V of this preamble.
Uncertainty with respect to the form of the statistical models used to
characterize the relationship between exposure level and risk of
adverse health outcomes is discussed in Section VI.
In its quantitative risk assessment, OSHA used the exposure-
response models from the best available evidence (i.e., the key studies
discussed at length in Section V, Health Effects and Section VI, Final
Quantitative Risk Assessment and Significance of Risk) to estimate
risks for 45 years of exposure to the previous PELs, revised PEL, and
the action level. When examining the risk estimates specifically for
silicosis mortality and morbidity in Table VI, one interesting
observation is the apparent difference in the exposure-response
relationship for these two endpoints. For example, for 45 years of
exposure to the action level (25 [mu]g/m\3\), there would be an
estimated 4 deaths from silicosis and 21 cases of silicosis (with chest
X-ray ILO category of 2/1 or greater) per 1,000 workers; at the
previous PEL (100 [mu]g/m\3\), there would be an estimated 11 deaths
from silicosis and 301 cases of silicosis per 1,000 workers. In other
words, nearly 20 percent of silicosis cases are estimated to be fatal
at the relatively low exposure of 25 [mu]g/m\3\ but only about 4
percent are estimated to be fatal at the relatively high exposure of
100 [mu]g/m\3\.\102\ Moreover, as noted previously, morbidity and
mortality estimates change in opposite directions in response to
varying the assumption about workers' total length of exposure.
Although this issue was not explicitly raised in the rulemaking record,
OSHA notes and addresses it here.
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\102\ Even if one subtracts off the Table VI-1 estimates of
other silica-attributable diseases (e.g., lung cancer) from the 100
[mu]g/m\3\ denominator, on the assumption that those diseases cause
mortality before silicosis has a chance to do so, the ratio of fatal
silicosis cases to the remaining silicosis diagnoses is still no
more than 6.6 percent at 100 [mu]g/m\3\, as opposed to the ratio of
nearly 20 percent at 25 [mu]g/m\3\.
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OSHA attributes this apparent difference in the exposure-response
relationships for silicosis mortality and morbidity to several factors.
First, the silicosis mortality study (ToxaChemica, 2004, Document ID
0469) defined deaths using death certificate data, in which silicosis
or unspecified pneumoconiosis was recorded as the underlying cause of
death. In contrast, the silicosis morbidity study (Buchanan et al.,
2003, Document ID 0306) defined silicosis cases using data from chest
x-rays showing radiographic opacities. These radiographic signs of
silicosis represent an early endpoint that is very different from
silicosis death as the underlying cause of death. Such disparate
endpoints are alone one reason why OSHA does not believe that the
exposure-response curves should necessarily be proportional.
In addition, as discussed in Section V.E, Comments and Responses
Concerning Surveillance Data on Silicosis Morbidity and Mortality,
silicosis is well-known to be underreported on death certificates in
that deaths due to silicosis could have been reported as tuberculosis
or chronic obstructive pulmonary disease (Document ID 1089, pp. 724-
725; 1030; 3425, p. 2; 3577, Tr. 855, 867; 4204, p. 17; 2175, p. 3;
3577, Tr. 772). Also, silica-exposed workers are at risk for other
silica-related diseases, including lung cancer and renal disease, as
well as other non-exposure-related causes of death such that many
workers who contract silicosis will not ultimately die from silicosis.
Therefore the reported silicosis deaths at any level are the lowest
possible number of such deaths. Workers with higher cumulative
exposures are also likely to be older, and therefore may have a higher
rate of other conditions that could have been listed on death
certificates. Furthermore, as discussed in Section VI, OSHA's risk
assessment required some degree of extrapolation at high doses (e.g.,
45 years of exposure to 250 and 500 [mu]g/m\3\ respirable crystalline
silica) that result in cumulative exposures not experienced by many of
the cohort members studied. Thus, OSHA attributes the apparent non-
proportionality in the exposure-response curves for silicosis mortality
and morbidity to these factors. It is possible nonetheless, that future
research may shed additional light on this topic.
d. Estimating a Stream of Benefits Over Time
Risk assessments in the occupational environment are generally
designed to estimate the risk of an occupationally related illness over
the course of an individual worker's lifetime. As previously discussed,
the current occupational exposure profile for a particular substance
for the current cohort of workers can be matched up against the
expected profile after the final standard takes effect, creating a
"steady state" estimate of benefits. However, in order to annualize
the benefits for the period of time after the silica rule takes effect,
it is necessary to create a timeline of benefits for an entire active
workforce over that period.
There are various approaches for modeling the workforce. As
explained below, OSHA uses a model that considers the effect of
lowering exposures for the entire working population. At one extreme,
however, one could assume that all of the relevant silica exposures
will occur after the standard goes into effect and none of the benefits
occurs until after the worker retires, or at least 45 years in the
future. In the case of lung cancer, that period would effectively be
60 years, since the 45 years of exposure must be added to a 15-year
latency period during which it is assumed that lung cancer does not
develop.\103\ At the other extreme, one could assume that the benefits
occur immediately, or at least immediately after a designated lag.
Neither extreme reflects the reality that silica-related diseases that
this standard aims to reduce significantly occur at various times
during and after the working lives of these populations of workers,
with the majority of cases occurring sometime after the typical worker
is middle aged. Indeed, based on the various risk models (as detailed
in model life tables in Appendix A to the QRA), which reflect real-world
experience with development of disease over an extended period of time;
it appears that the actual pattern occurs at some point between these two
extremes.
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\103\ This assumption is consistent with the 15-year lag
incorporated in the lung cancer risk models used in OSHA's QRA.
---------------------------------------------------------------------------
The model OSHA uses, therefore, is one that considers the effect of
lowering exposures for the entire working population. This population-
based approach does not simply follow the pattern of the risk
assessments, which are based in part on life tables, and observe that
typically the risk of the illness grows gradually over the course of a
working life and into retirement. While this would be a good working
model for an individual exposed over a working life, it is not very
descriptive of the exposed population as a whole. In the latter case,
in order to estimate the benefits of the standard over time, OSHA
considers that workers currently being exposed to silica are going to
vary considerably in age. Since the health risks from crystalline
silica exposure depend on a worker's cumulative exposure over a working
lifetime, the overall benefits of the final standard will phase in over
several decades, as the cumulative exposure gradually falls for all age
groups, until those now entering the workforce reach retirement and the
annual stream of silica-related illnesses reaches a new, significantly
lowered "steady state." However, the beneficial effects of the rule
begin in the near term and increase over time until that "steady
state" is reached; and, for a given level of cumulative exposure, the
near-term impact of the final rule will be greater for workers who are
now middle-aged or older, compared to younger workers with similar
current levels of cumulative exposure. This conclusion follows from the
structure of the relative risk models used in this analysis and the
fact that the background mortality rates for diseases such as lung
cancer, chronic obstructive pulmonary disease and renal disease
increase with age.
In order to characterize the magnitude of benefits before the
steady state is reached, OSHA created a linear phase-in model to
reflect the potential timing of benefits. Specifically, OSHA estimated
that, for all non-cancer cases, while the number of cases of silica-
related disease would gradually decline as a result of the final rule,
they would not reach the steady-state level until 45 years had passed.
The reduction in cases in any given year in the future was estimated to
be equal to the steady-state reduction (the number of cases in the
baseline minus the number of cases in the new steady state) times the
ratio of the number of years since the standard was implemented and a
working life of 45 years; in other words, the number of non-malignant
silica-relates cases of disease avoided is assumed to increase in
direct proportion to the number of years the standard is in effect
until year 45, at which point the numbers hold steady. This formulation
also assumes that the number of workers is constant over the entire
time frame. Expressed mathematically:
Nt = (C-S) x (t/45),
where Nt is the number of non-malignant silica-related
diseases avoided in year t; C is the current annual number of non-
malignant silica-related diseases; S is the steady-state annual number
of non-malignant silica-related diseases; and t represents the number
of years after the final standard takes effect, with t<=45.
In the case of lung cancer, the function representing the decline
in the number of cases as a result of the final rule is similar, but
there would be a 15-year lag before any reduction in cancer cases would
be achieved. Expressed mathematically, for lung cancer:
Lt = (Cm-Sm) x ((t-15)/45),
where 15 <=t <=60 and Lt is the number of lung cancer cases
avoided in year t as a result of the final rule; Cm is the
current annual number of silica-related lung cancers; and Sm
is the steady-state annual number of silica-related lung cancers.
This model was extended to 60 years for all the health effects
previously discussed in order to incorporate the 15-year lag, in the
case of lung cancer, and a 45-year working life. OSHA also has
estimated the benefits using other job tenures. For this purpose, OSHA
examined scenarios for the same number of years--60 years--but with the
work force restarting exposure whenever the first job tenure cycle was
complete.
OSHA also has estimated the benefits using other job tenures. For
this purpose, OSHA examined scenarios for the same number of years--60
years--but with the work force restarting exposure whenever the first
job tenure cycle was complete.
In order to compare costs to benefits, OSHA assumes that economic
conditions remain constant and that annualized costs will continue for
the entire 60-year time horizon used for the benefits analysis (as
discussed in Chapter V of the FEA). OSHA invited comments on this
assumption in the PEA, for both the benefit and cost analysis. OSHA was
particularly interested in what assumptions and time horizon should be
used instead and why. The Agency did not receive any comments on this
point.
2. Monetizing the Benefits
OSHA also estimates the monetary value of health and longevity
improvements of the type associated with the final silica rule. These
estimates are for informational purposes only because OSHA cannot use
benefit-cost analysis as a basis for determining the PEL for a health
standard. The Agency's methodology for monetizing benefits is based on
both the relevant academic literature and on the approaches OSHA and
other regulatory agencies have taken in the past for similar regulatory
actions.
In explaining OSHA's methodology for monetizing health and
longevity improvements, OSHA relied on a 45 year occupational tenure.
Later, OSHA discusses monetization under alternative occupational
tenures of 25, 13 and 6.6 years.
a. Placing a Monetary Value on Individual Silica-Related Fatalities
Avoided
To estimate the monetary value of the reductions in the number of
silica-related fatalities, OSHA relied, as OMB recommends in its
Circular A-4, on estimates developed from the willingness of affected
individuals to pay to avoid a marginal increase in the risk of
fatality. While a willingness-to-pay (WTP) approach clearly has
theoretical merit, it should be noted that an individual's willingness
to pay to reduce the risk of fatality would tend to underestimate the
total willingness to pay, which would include the willingness of
others--particularly the immediate family--to pay to reduce that
individual's risk of fatality.\104\
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\104\ See, for example, Thaler and Rosen (1976), (Document ID
1520, pp. 265-266); Sunstein (2004) (Document ID 1523, p. 433); or
Viscusi, Magat and Forrest (1988), the last of whom write that
benefits from improvement in public health "consist of two
components, the private valuation consumers attach to their own
health, plus the altruistic valuation other members of society place
on their health." That paper uses contingent valuation methods to
suggest that the effect of altruism could significantly alter
willingness-to-pay estimates for some kinds of health improvement.
There are, however, many questions concerning how to measure the
altruistic component and the conditions under which it might matter.
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For estimates using the willingness-to-pay concept, OSHA relies on
existing studies of the imputed value of fatalities avoided based on
the theory of compensating wage differentials in the labor market.
These studies rely on certain critical assumptions for their estimates,
particularly that workers understand the risks to which they are
exposed and that workers have legitimate choices between high- and low-
risk jobs. Actual labor markets only imperfectly reflect these
assumptions. A number of academic studies, as summarized in Viscusi and
Aldy (2003, Document ID 1220), have shown a correlation between higher
job risk and higher wages, suggesting that employees demand monetary
compensation in return for a greater risk of injury or fatality. The
estimated trade-off between lower wages and marginal reductions in
fatal occupational risk--that is, workers' willingness to pay for
marginal reductions in such risk--yields an imputed value of an avoided
fatality: the willingness-to-pay amount for a reduction in risk divided
by the reduction in risk.
OSHA has used this approach in many recent proposed and final rules
(see 69 FR 59305 (Oct. 4, 2004) and 71 FR 10099 (Feb. 28, 2006), the
preambles for the proposed and final hexavalent chromium rule).
Limitations to this approach (see Hintermann, Alberini and Markandya,
(2010, Document ID 0739)), have been examined in a recent WTP analysis,
by Kniesner et al. (2012, Document ID 3819), using panel data to
examine the trade-off between fatal job risks and wages. This article
addressed many of the earlier econometric criticisms by controlling for
measurement error, endogeneity, and heterogeneity. Accordingly, OSHA
views this analysis as buttressing the estimates in Viscusi and Aldy
(2003, Document ID 1220), which the Agency is continuing to rely on for
the FEA.\105\
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\105\ For example, if workers are willing to pay $50 each for a
1/100,000 reduction in the probability of dying on the job, then the
imputed value of an avoided fatality would be $50 divided by 1/
100,000, or $5,000,000. Another way to consider this result would be
to assume that 100,000 workers made this trade-off. On average, one
life would be saved at a cost of $5,000,000.
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OSHA received several comments on the use of willingness-to-pay
measures and estimates based on compensating wage differentials. For
example, Peter Dorman, Professor of Economics, Evergreen State College,
Eric Frumin of Change to Win, and Dr. Ruth Ruttenberg, representing the
AFL-CIO, in addition to critiquing the academic studies used to develop
the willingness-to-pay measure, cited the absence of effective labor
markets for capturing a wage differential for hazardous work (Document
ID 2260, Attachment 1; 2372, Attachment 1, pp. 4-15; 2256, Attachment
4, p. 9). OSHA acknowledges that there has been an absence of a wage
premium for risk in certain labor markets, and cites this absence in
Chapter II of the FEA as an example of market failure. Nonetheless,
while the Agency agrees that the absence of a wage premium for risk
demonstrates the need for regulatory intervention in the labor market,
it does not, in itself, invalidate the use of the willingness-to-pay
approach for the informational purposes for which OSHA calculates
benefits, so long as there are some reasonably well-functioning parts
of the labor market that can be used to estimate the willingness to pay
for some subset of workers. OSHA finds that there are such sections of
the labor market.
Several studies indicate that there are enough functional parts of
the labor market to allow for some quantification of the risk,
typically expressed as the value of a statistical life (VSL), a
possible measure of willingness to pay. For example, Viscusi and Aldy
(2003) conducted a meta-analysis of studies in the economics literature
that use a willingness-to-pay methodology to estimate the imputed value
of life-saving programs and found that each fatality avoided was valued
at approximately $7 million in 2000 dollars. For the PEA, the Agency
used the GDP Deflator (U.S. BEA, 2010) to convert this estimate to $8.7
million in 2009 dollars for each fatality avoided. For the FEA, the
base year has been further updated to 2012 using the GDP Deflator (U.S.
BEA, 2013), yielding an estimate of $9.0 million per fatality
avoided.\106\
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\106\ An alternative approach to valuing an avoided fatality is
to monetize, for each year that a life is extended, an estimate from
the economics literature of the value of that statistical life-year
(VSLY). See, for instance, Aldy and Viscusi (2007) (Document ID
1522) for discussion of VSLY theory and FDA (2003, Document ID 1618,
pp. 41488-9), for an application of VSLY in rulemaking. OSHA has not
investigated this approach which was not recommended by any
commenter in the record. It acknowledges, however, that such an
approach would have the effect of lowering estimated benefits
because silica-related health outcomes largely affect older workers
and retirees as they approach actuarially expected life
expectancies.
---------------------------------------------------------------------------
There are a number of factors that could influence the value of a
statistical life (VSL) calculation in different labor markets, but for
the purpose of its analysis OSHA has identified methods for normalizing
the risk between markets. For example, in Kniesner, Viscusi, and Ziliak
(2010, Document ID 0767), the authors addressed the issue of the
heterogeneity of the VSL approach among various labor markets by
developing analytical tools (quantile regressions) for differentiating
by income. For the purpose of quantifying the effects of income growth
over time on the value of a statistical life, OSHA relies on their
data, which generally show that VSL increases with increased worker
income (as banded by quartile). Despite potential weaknesses in the VSL
approach, Executive Order 12866 recommends monetization of regulatory
benefits (including increases in longevity), and the Agency concludes
this constitutes the best available method for this purpose.
b. Placing a Monetary Value on Individual Non-Fatal Silica-Related
Diseases Avoided
In addition to the benefits that are based on the imputed value of
fatalities avoided, workers also place a value on occupational injuries
or illnesses avoided, which reflect their willingness to pay to avoid
monetary costs (for medical expenses and lost wages) and quality-of-
life losses as a result of occupational illness. Silicosis, lung
cancer, and renal disease can be totally disabling and adversely affect
individuals for years or even decades in non-fatal cases, or before
ultimately proving fatal. Because monetary measures of the willingness
to pay for avoiding these illnesses are rare and difficult to find OSHA
has included a range based on a variety of estimation methods.
Consistent with Buchanan et al. (2003), OSHA estimated the total
number of moderate to severe silicosis cases prevented by the final
rule, as measured by 2/1 or more severe x-rays (based on the ILO rating
system). However, while radiological evidence of moderate to severe
silicosis is evidence of significant material impairment of health,
placing a precise monetary value on this condition is difficult, in
part because the severity of symptoms may vary significantly among
individuals. For that reason, in the PEA, as well as in the FEA, the
Agency has employed a broad range of valuation, which should encompass
the range of severity these individuals may encounter. Using the
willingness-to-pay approach, discussed in the context of the imputed
value of fatalities avoided, OSHA has estimated a range in valuations
(updated and reported in 2012 dollars) that runs from approximately
$64,000 per case--which reflects estimates developed by Viscusi and
Aldy (2003, Document ID 1220), based on a series of studies primarily
describing simple accidents--to upwards of $5.2 million per case--which
reflects estimates developed by Magat, Viscusi, and Huber (1996, Document
ID 0791) for non-fatal cancer. The latter number is based on an approach
that applies a willingness-to-pay value to avoid serious illness that
is calibrated relative to the value of an avoided fatality. OSHA (2006,
Document ID 0941) previously used this approach in the FEA supporting
its hexavalent chromium final rule, and EPA (2003, Document ID 0657)
used this approach in its Stage 2 Disinfection and Disinfection
Byproducts Rule concerning regulation of primary drinking water. EPA
used the study by Magat, Viscusi & Huber (1996, Document ID 0791) on
the willingness to pay to avoid nonfatal lymphoma and chronic
bronchitis as a basis for valuing a case of nonfatal cancer at 58.3
percent of the value of a fatal cancer. OSHA's estimate of $5.2 million
in 2012 dollars for an avoided case of non-fatal cancer is based on
this 58.3 percent figure.
There are several benchmarks for valuation of health impairment due
to silica exposure, using a variety of techniques, which provide a
number of mid-range estimates between OSHA's high and low estimates of
$5.2 million and $64,000. For example, EPA (2008) recently estimated a
cost of approximately $460,000, in 2008 dollars, per case of chronic
bronchitis, which OSHA (2009) used as the basis for comparison with
less severe lung impairments from diacetyl exposure. Another approach
is to employ a cost-of-injury model. Combining estimates of
productivity losses (i.e., lost wages, fringe benefits, and household
production), medical costs (including hospitalizations), and loss of
quality-of-life components, Miller (2005), using an enhanced cost-of-
injury model, estimated the average silicosis disease cost the
equivalent of $335,000 in 2012 dollars).\107\
---------------------------------------------------------------------------
\107\ Miller (2005) estimated the cost of a silicosis case,
using an enhanced direct cost approach--including a quality-
adjusted-life-years component--to be $265,808 in 2002 dollars.
---------------------------------------------------------------------------
Miller (2005) also estimated the morbidity costs of several
different pneumoconioses other than silicosis and found the other cases
to be even more costly to society than silicosis. While the full costs
of renal disease are less well known, the medical costs alone of
dealing with end-stage renal disease run over $64,000 annually per
patient (Winkelmayer, 2002). This suggests that a more comprehensive
analysis of the direct costs of renal disease, as well as for the
various lung impairments, would produce an estimate well above the
$64,000 estimate of injuries in Viscusi and Aldy (2003). Moreover,
several studies (e.g., Alberini and Krupnick, 2000) have found that the
cost of injury approach tends to significantly underestimate the true
economic cost of an injury or illness, relative to the willingness to
pay approach, which includes quality of life impacts and psychic costs
as well as medical costs and lost income. In this way, looking only at
specific elements of this valuation, such as a workers compensation
payouts (to the extent they can be linked to a specific employer in a
timely manner), would dramatically underestimate the cost of the
illness to society.
Thus, the various studies presented in Chapter VII of the FEA
suggest that the imputed value of avoided morbidity associated with
silica exposure, both for cases preceding death and for non-fatal
cases, ranges between $64,000 and $5.2 million, depending in part on
the model used to compute the value and in part on the severity and
duration of the case. OSHA considers this wide range of estimates is
descriptive of the value of preventing morbidity associated with
moderate-to-severe silicosis, as well as the morbidity preceding
mortality due to other causes enumerated here--lung cancer, lung
diseases other than cancer, and renal disease. OSHA is therefore
applying these values to monetize cases of avoided silica-related
morbidity.\108\ OSHA has included these estimates of silicosis
morbidity throughout the analysis. For mortality, OSHA has included the
midpoints of $64,000 and $5.2 million ($2.63 million) for all mortality
cases. The high and low estimates in the remainder of this document for
mortality not only reflect different point estimates, but different
levels for the morbidity effect.
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\108\ For the purpose of simplifying the estimation of the
monetized benefits of avoided illness and death, OSHA simply added
the monetized benefits of morbidity preceding mortality to the
monetized benefits of mortality at the time of death, and both would
be discounted at that point. In theory, however, the monetized
benefits of morbidity should be recognized (and discounted) at the
onset of morbidity, as this is what a worker's willingness to pay is
presumed to measure--that is, the risk of immediate death or an
immediate period of illness that a worker is willing to pay to
avoid--a practice that would increase the present value of
discounted morbidity benefits. A parallel tendency toward
underestimation occurs with regard to morbidity not preceding
mortality, since it implicitly assumes that the benefits occur at
retirement, as per the Buchanan model, but many, if not most, of the
2/0 or higher silicosis cases will have begun years before (with
those classifications, in turn, preceded by a 1/0 classification).
As a practical matter, however, the Agency lacks sufficient data at
this time to refine the analysis in this way.
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Public Comment on Valuing Non-Fatal Cases of Silicosis
OSHA requested public input on the issue of valuing the cost to
society of non-fatal cases of moderate-to-severe silicosis, as well as
the morbidity associated with other related diseases of the lung, and
with renal disease. A number of commenters did not directly provide
quantitative estimates of the cost of silicosis or other silica-related
health effects, but provided qualitative descriptions of the heavy
burden to health, work, and family life incurred by having silicosis.
For example, Alan White, of the United Steelworkers Local Union
593, who developed silicosis after working in a foundry for 16 years as
a general helper, described the practical implications of developing
silicosis:
First of all, for me, there was the growing problem of being out
of breath sooner than I used to. That's a difficult situation for a
competitor, especially since I didn't know why. Then, I received a
big surprise during the conversation with the first doctor when I
found out that I have silicosis and that I will lose my job. He and
the other doctors all agreed that the diagnosis is silicosis.
Watching your wife and other loved ones cry as they figure out what
silicosis is was a big hit and then, shortly afterward, there was
the radical pay cut from a transfer out of the foundry to a
department where I knew nothing because I chose my health over money
...There are also difficulties outside of work and issues for me
to look forward to in the future. Walking while talking on a cell
phone is very exhaustive, as well as walking up the stairs from my
basement to my second floor apartment. I have increasing difficulty
on my current job. Certain irritants like air fresheners, potpourri
and cleaners make home life increasingly difficult and I was told
that it's downhill from here for both work and home life (Document
ID 3477, p. 2).
Mr. White also described how the foundry went to considerable
expense to hire people to do the job he previously had done, including
the costs to the foundry for mistakes made by the trainees replacing
him. Such personnel costs to the employer would not be captured by
either the willingness-to-pay approach or cost-of-injury approach.
In addition to questioning the underlying willingness to pay
approach, at least one commenter indicated various ways in which the
approach employed by OSHA would tend to underestimate the economic
benefits of the rulemaking. Dr. Ruttenberg argued that the WTP approach
does not include costs to third parties of silica-related illnesses and
injuries, starting with a number of government programs:
In its Preliminary Economic Analysis, OSHA says that it wants
public input on the issue of valuing the cost to society of non-
fatal cases of moderate-to severe silicosis, as well as the
morbidity associated with other related diseases of the lung, and
with renal disease. (PEA, p. VII-15) This is a key request because
adding such societal costs can double the benefits of preventing
these diseases. In an article by a lawyer and two economists looking
at the social cost of dangerous products, Shapiro, Ruttenberg, and
Leigh argue that a large economic burden is borne by private
insurance, government programs, the business community and the
victims and their families. Those affected by occupational
exposures, such as silica, may become eligible for a range of cash
or in-kind assistance. Such programs may include unemployment
compensation, food stamps, Medicaid, Medicare, State Children's
Health Insurance Program (SCHIP), Temporary Assistance for Needy
Families (TANF), Social Security Disability, and Old Age, Survivors
and Disability Insurance. There are also costs for use of military
hospitals and clinics (Document ID 2256, Attachment 4, pp. 9-10)
(citations omitted).
Part of the cost of the injury or fatality may be borne in
substantial part by the victim's family:
There is another group of costs that can easily double, or even
triple, the direct and indirect totals. These are social and
economic impacts that are also caused by an incident. They often
involve third-party payments, or stress on the victim or his/her
family members. The financial pressures on a family can include the
need for a caregiver, need for additional income from children or
spouse to fill the gap between previous earnings and workers
compensation, or psychotherapy for family members to cope with harsh
new realities. When children lose their chance at college and higher
future earnings, the impact can be hundreds of thousands of dollars
(Document ID 2256, Attachment 4).
Dr. Ruttenberg pointed to an existing Department of Transportation
study, which suggested that only a fraction of the economic cost of
motor vehicle accidents was actually borne by the victim, with the
remainder of the costs split between governmental bodies, insurers, and
other parties (Document ID 2256, Attachment 4, p. 11).\109\
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\109\ The Agency acknowledges this is a likely and potentially
substantial source of underestimation of morbidity costs and is
currently investigating ways to capture this currently unquantified
dimension of benefits for potential use in future rulemakings.
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The Center for Progressive Reform argued that there is value to
reducing economic inequities created by occupational illnesses related
to silica exposure:
The proposal's implications for fair treatment of workers also
deserve more attention. The proposed standards would benefit a
population comprising mostly construction workers (more than 85% of
the total affected population). This is an industry that is a
bastion for middle class workers and those striving to attain middle
class status. It is also an industry that employs a significant
number of foreign-born and non-union workers, groups who typically
have limited power to negotiate improved working conditions.
Ensuring that these workers' health is better protected against the
hazards of silica exposure is an important step toward reducing
socioeconomic inequality, given the linkages between individual
health and social mobility. Other federal agencies, including the
National Highway Traffic Safety Administration (NHTSA) and
Department of Justice (DOJ), have gone so far as to argue that
equity and other non-monetizable benefits are sufficient to justify
rules for which the monetized costs far outweigh the monetized
benefits. (As with the OSH Act, the authorizing statutes under which
NHTSA and DOJ were acting do not require cost-benefit analysis, much
less require the agencies to produce rules with monetized benefits
that outweigh monetized costs) (Document ID 2351, p. 7) (citations
omitted).
The Agency recognizes that, as with third party effects, there are
aspects of economic equity issues related to occupational injury,
illness, and mortality that merit attention for policy making. As noted
previously, however, the OSH Act requires that OSHA policy for toxic
substances be ultimately determined by issues of risk and feasibility,
as opposed to cost-benefit criteria.
The Agency requested public input on the issue of valuing the cost
to society of non-fatal cases of moderate to severe silicosis, as well
as the morbidity associated with other related diseases of the lung,
and with renal disease. The final benefits analysis summarized below
and discussed in greater detail in the FEA incorporates OSHA's response
to public comment.
c. Adjusting Monetized Benefits To Reflect Rising Future Value
In the PEA, OSHA suggested, provided estimates, and requested
comment on adjusting future values of illness and mortality prevention
to account for changes in real income over time. Ronald White of the
Center for Effective Government favored integrating this element into
the monetized benefits analysis (Document ID 2341, p. 3).\110\ No
commenters argued against it. For the reasons provided in the PEA and
described below, the Agency is adopting this approach and has used it
to develop its primary benefits estimates.
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\110\ The estimates of monetized benefits to reflect changes in
real income over time developed in the PEA contained an error in the
formulas (an inconsistent discount rate was used) that resulted in
underestimated benefits. That error has been corrected in the
estimates presented in the FEA.
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OSHA's estimates of the monetized benefits of the final rule are
based on the imputed value of each avoided fatality and each avoided
silica-related disease. As previously discussed, these, in turn, are
derived from a worker's willingness-to-pay to avoid a fatality (with an
imputed value per fatality avoided of $9.0 million in 2012 dollars) and
to avoid a silica-related disease (with an imputed value per disease
avoided of between $64,000 and $5.3 million in 2012 dollars). Two
related factors suggest that these values will tend to increase over
time and help to better identify the amount that a worker would be
willing to pay to avoid a fatality.
First, economic theory and empirical evidence from the relevant
studies indicate that the value of reducing life-threatening and
health-threatening risks--and correspondingly the willingness of
individuals to pay to reduce these risks--will increase as real per
capita income increases.\111\ With increased income, an individual's
health and life becomes more valuable relative to other goods because,
unlike other goods, they are without close substitutes. Expressed
differently, as income increases, consumption will increase but the
marginal utility of consumption will decrease. In contrast, added years
of life (in good health) are, in the model of Hall and Jones (2007,
Document ID 0720), not subject to the same type of diminishing returns
and, indeed, may be viewed as the ultimate good.
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\111\ Simple modeling can show this directly. For example, Rosen
(1988) (Document ID 1165) demonstrates that the value of life can be
expressed as the marginal rate of substitution between wealth and
the probability of survival. An increase in wealth or income will
therefore increase an individual's willingness to pay.
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Second, real per capita income has broadly been increasing
throughout U.S. history, including during recent periods.\112\ For example,
for the period 1950 through 2000, real per capita income grew at an average
rate of 2.31 percent a year (Hall and Jones, 2007, Document ID 0720),\113\
although real per capita income for the recent 25 year period 1983 through
2008 grew at an average rate of only 1.3 percent a year (U.S. Census Bureau,
2010, Document ID 1621). More important is the fact that real U.S. per capita
income is estimated to grow significantly in future years. The Annual Energy
Outlook (AEO) estimates, prepared by the Energy Information
Administration (EIA) in the Department of Energy (DOE), estimates an
average annual growth rate of per capita income in the United States of
2.7 percent for the period 2011-2035.\114\ The U.S. Environmental
Protection Agency prepared its economic analysis of the Clean Air Act
using the AEO estimates. OSHA concludes that it is reasonable to use
the same AEO estimates employed by DOE and EPA, and correspondingly
estimates that per capita income in the United States will increase by
2.7 percent per year over the 60-year period in the analysis for this
silica rule. OSHA, as discussed below, will not use this value combined
with the best estimate of income elasticity. Instead OSHA derives a
lower combined measure of the adjustment that combines income
elasticity and rate of economic growth. Further, OSHA analyzes the
sensitivity of the results to this assumption later in this chapter.
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\112\ In addition, as Costa (1998) and Costa and Kahn (2004)
(Document ID 0609) point out, elderly health, longevity, and well-
being in the United States have historically been improving, which
also has the effect of increasing the imputed value of life. Of
course, improvements in elderly health, longevity, and well-being
are not independent of increases in per capita income over the same
period.
\113\ The results are similar if the historical period includes
a major economic downturn (such as the United States has recently
experienced). From 1929 through 2003, a period in U.S. history that
includes the Great Depression, real per capita income still grew at
an average rate of 2.22 percent a year (Gomme and Rupert, 2004)
(Document ID 0710).
\114\ The EIA used DOE's National Energy Modeling System (NEMS)
to produce the Annual Energy Outlook (AEO) estimates (EIA, 2011)
(Document ID 1573). Future per capita GDP was calculated by dividing
the projected real gross domestic product each year by the estimates
U.S. population for that year.
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On the basis of the predicted increase in real per capita income in
the United States over time and the expected resulting increase in the
value of avoided fatalities and diseases, OSHA has adjusted its
estimates of the benefits of the final rule to reflect the anticipated
increase in their value over time. This type of adjustment has been
supported by EPA's Science Advisory Board (EPA, 2000b, Document ID
0652) \115\ and applied by EPA.\116\ OSHA accomplished this adjustment
by modifying benefits in year i from [Bi] to [Bi
* (1 + k)i], where "k" is the estimated annual increase in
the magnitude of the benefits of the final rule.\117\
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\115\ Supplementary evidence in support for this type of
adjustment comes from EPA (2010) (Document ID 1713) and U.S.
Department of Transportation (2014) guidelines.
\116\ See, for example, EPA (2003) (Document ID 0657) and EPA
(2008) (Document ID 0661).
\117\ This precise methodology was suggested in Ashford and
Caldart (1996) (Document ID 0538).
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What remains is to estimate a value for "k" with which to
increase benefits annually in response to annual increases in real per
capita income, where "k" is equal to (1 + g) * ([eta]), "g" is the
expected annual percentage increase in real per capita income, and
"[eta]" is the income elasticity of the value of a statistical life.
Probably the most direct evidence of the value of "k" comes from the
work of Costa and Kahn (2003, 2004). They estimate repeated labor
market compensating wage differentials from cross-sectional hedonic
regressions using census and fatality data from the Bureau of Labor
Statistics for 1940, 1950, 1960, 1970, and 1980. In addition, with the
imputed income elasticity of the value of life on per capita GNP of 1.7
derived from the 1940-1980 data, they then predict the value of an
avoided fatality in 1900, 1920, and 2000. Given the change in the value
of an avoided fatality over time, it is possible to estimate a value of
"k" of 3.4 percent a year from 1900-2000; of 4.3 percent a year from
1940-1980; and of 2.5 percent a year from 1980-2000.\118\
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\118\ These estimates for "k" were not reported in Costa and
Kahn (2003 Document ID 0610, 2004, Document ID 0609) but were
derived by OSHA from the data presented. The changes in the value of
"k" for the different time periods mainly reflect different growth
rates of per capita income during those periods.
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Other, more indirect evidence comes from estimates in the economics
literature on the income elasticity of the value of a statistical life.
Viscusi and Aldy (2003, Document ID 1220) performed a meta-analysis on
49 wage-risk studies and concluded that the confidence interval upper
bound on the income elasticity did not exceed 1.0 and that the point
estimates across a variety of model specifications ranged between 0.5
and 0.6.\119\ Applied to a long-term increase in per capita income of
about 2.7 percent a year, this would suggest a value of "k" of about
1.5 percent a year.
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\119\ These results conflict with the more recent work by Hall
and Jones (2007) (Document ID 0720), which concludes that the income
elasticity of the value of life should be larger than 1.
---------------------------------------------------------------------------
More recently, Kniesner, Viscusi, and Ziliak (2010, Document ID
0767), using panel data quintile regressions, developed an estimate of
the overall income elasticity of the value of a statistical life of
1.44. Applied to a long-term increase in per capita income of about 2.7
percent a year, this would suggest a value of "k" of about 3.9
percent a year.
Based on the preceding discussion of these three approaches for
estimating the annual increase in the value of the benefits of the
final rule and the fact that the estimated increase in real per capita
income in the United States has flattened in recent years and could
remain so, OSHA has selected a conservative value for "k" of
approximately 2 percent a year over the next 60 years.
Thus, based on the best current thinking and data on willingness to
pay and its relationship to income elasticity as income increases, OSHA
concludes that a 2 percent increase in benefits per year, as measured
by a corresponding anticipated increase in VSL, is a reasonable, mid-
range estimate. However, OSHA recognizes the uncertainties surrounding
these estimates and has subjected them to sensitivity analysis, as
discussed below.
Accordingly, OSHA concludes that the rising value, over time, of
health benefits is a real phenomenon that should be taken into account
in estimating the annualized benefits of the final rule. Table VII-4,
in the following section, and the monetized benefits estimates that
follow it, show estimates of the monetized benefits of the silica rule
with this adjustment integrated into the valuation. OSHA provides a
sensitivity analysis of the effects of this approach later in this
chapter.
d. The Monetized Benefits of the Final Rule
Table VII-27 presents the estimated annualized (over 60 years,
using a 0 percent discount rate) benefits from each of these components
of the valuation, and the range of estimates, based on risk model
uncertainty (notably in the case of lung cancer), and the range of
uncertainty regarding valuation of morbidity. As shown, the full range
of monetized benefits, undiscounted, for the final PEL of 50 [micro]g/
m\3\ runs from $7.3 billion annually, in the case of the lowest
estimate of lung cancer risk and the lowest valuation for morbidity, up
to $19.3 billion annually, for the highest of both. Note that the value
of total benefits is more sensitive to the valuation of morbidity
(ranging from $7.9 billion to $18.5 billion, given estimates at the
midpoint of the lung cancer models) than to the lung cancer model used
(ranging from $12.5 to $13.8 billion, given estimates at the midpoint
of the morbidity valuation).\120\
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\120\ As previously indicated, these valuations include all the
various estimated health endpoints. In the case of mortality this
includes lung cancer, non-malignant respiratory disease and end-
stage renal disease. The Agency highlighted lung cancers in this
discussion due to the model uncertainty. In calculating the
monetized benefits, the Agency is typically referring to the
midpoint of the high and low ends of potential valuation--in this
case, the undiscounted midpoint of $7.7 billion and $19.5 billion.
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This result comports with the very wide range of valuation for
morbidity. At the low end of the valuation range, the total value of
benefits is dominated by mortality ($7.7 billion out of $7.9 billion at
the case frequency midpoint), whereas at the high end the majority of
the benefits are related to morbidity ($11.2 billion out of $18.7
billion at the case frequency midpoint). Also, the analysis illustrates
that most of the morbidity benefits are related to silicosis cases that
are not ultimately fatal. At the valuation and case frequency midpoint
of $13.3 billion, $7.7 billion in benefits are related to mortality,
$2.0 billion are related to morbidity preceding mortality, and $3.5
billion are related to morbidity not preceding mortality.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
3. Discounting of Monetized Benefits
As previously noted, the estimated stream of benefits arising from
the final silica rule is not constant from year to year, both because
of the 45-year delay after the rule takes effect until all active
workers obtain reduced silica exposure over their entire working lives
and because of, in the case of lung cancer, a 15-year latency period
between reduced exposure and a reduction in the probability of disease.
An appropriate discount rate \121\ is needed to reflect the timing of
benefits over the 60-year period after the rule takes effect and to
allow conversion to an equivalent steady stream of annualized
benefits.\122\
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\121\ Here and elsewhere throughout this section, unless
otherwise noted, the term "discount rate" always refers to the
real discount rate--that is, the discount rate net of any
inflationary effects.
\122\ This essential point was missed in a comment by Dr.
Ruttenberg, which claimed that OSHA's estimates of the benefits of
an avoided fatality were forty percent below the VSL estimate of
$8.7 million (in 2009 dollars) that the Agency was using (Document
ID 2256, Attachment 4, p. 9). The difference is due to the fact that
the avoided fatalities occurred over a 60 year period and had to be
discounted.
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a. Alternative Discount Rates for Annualizing Benefits
Following OMB (2003) guidelines (Document ID 1493], OSHA has
estimated the annualized benefits of the final rule using separate
discount rates of 3 percent and 7 percent. Consistent with the Agency's
own practices in recent final and final rules, OSHA has also estimated,
for benchmarking purposes, undiscounted benefits--that is, benefits
using a zero percent discount rate.
The "appropriate" or "preferred" discount rate to use to
monetize health benefits is a controversial topic, which has been the
source of scholarly economic debate for several decades.\123\ However,
in simplest terms, the basic choices involve a social opportunity cost
of capital approach or social rate of time preference approach. OSHA
analyzes the benefits of this rule under both approaches.
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\123\ For a more detailed discussion of the major issues, see,
for example, Lind (1982a, 1982b, and 1990, Document ID1622); EPA
(2000a, Document ID 1327, Chapter 6); and OMB (2003, Document ID
1493, pp. 31-37).
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The social opportunity cost of capital approach reflects the fact
that private funds spent to comply with government regulations have an
opportunity cost in terms of foregone private investments that could
otherwise have been made. The relevant discount rate in this case is
the pre-tax rate of return on the foregone investments (Lind, 1982b,
pp. 24-32) (Document ID 1622).
The rate of time preference approach is intended to measure the
tradeoff between current consumption and future consumption, or in the
context of the final rule, between current benefits and future
benefits. The individual rate of time preference is influenced by
uncertainty about the availability of the benefits at a future date and
whether the individual will be alive to enjoy the delayed benefits. By
comparison, the social rate of time preference takes a broader view
over a longer time horizon--ignoring individual mortality and the
riskiness of individual investments (which can be accounted for
separately).\124\
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\124\ It is not always possible to explicitly model all forms of
uncertainty that are relevant to a regulatory cost-benefit analysis
(e.g., medical innovations that allow for more successful treatment
of illnesses or changes in industrial practices or locations that in
turn change the exposure profile of workers subject to a
regulation). Because these uncertainties tend to increase as the
time horizon being analyzed lengthens, application of a discount
rate provides a reduced-form approach to less heavily weighting the
least-certain estimated benefits and costs.
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A usual method for estimating the social rate of time preference is
to calculate the post-tax real rate of return on long-term, risk-free
assets, such as U.S. Treasury securities (OMB, 2003, Document ID 1493).
A variety of studies have estimated these rates of return over time and
reported them to be in the range of approximately 1-4 percent.
OMB Circular A-4 (2003) recommends using discount rates of 3
percent (representing the social rate of time preference) and 7 percent
(a rate estimated using the social cost of capital approach) to
estimate benefits and net benefits (Document ID 1493). Ronald White of
the Center for Effective Government endorsed the use of a 3 percent
discount rate--since it "appropriately reflects a social rate of time
preference approach consistent with recommendations for benefits
evaluation by the U.S. Environmental Protection Agency" (Document ID
2341, pp. 3-4). Charles Gordon argued for a 0 percent discount rate:
The economic literature indicates that the social discount rate
should be 2 percent or 3 percent. But I believe the social discount
rate should be zero, because if you were asked the question, do you
want yourself saved from crystalline silica exposure...or do you
want your son to be saved from crystalline silica death 20 years
from now, you could not answer that question. You could not give a
preference (Document ID 3588, Tr. 3789-90).
In acknowledgement of OMB Circular A-4 (2003, Document ID 1493),
OSHA presents benefits and net benefits estimates using discount rates
of 3 percent (representing the social rate of time preference) and 7
percent (a rate estimated using the social cost of capital approach).
The weight of the evidence favors using a discount rate of 3 percent or
less, and that 3 percent is one of the options permitted by OMB, the
Agency is using a 3 percent discount rate to display its primary
estimates of benefits under the social rate of time preference method.
b. Summary of Annualized Benefits Under Alternative Discount Rates
Table VII-28a through Table VII-28d presents OSHA's estimates of
the sum of the annualized benefits of the final rule, under various
occupational tenure assumptions, using alternative discount rates of 0,
3, and 7 percent, with a breakout between construction and general
industry/maritime, with each table presenting these results for a
different tenure level. All of these benefits calculations reflect
willingness-to-pay values that, as previously discussed, increase in
real value at 2 percent a year.
Given that the stream of benefits extends out 60 years, the value
of future benefits is highly sensitive to the choice of discount rate.
As previously established in Table VII-27, the undiscounted benefits
(i.e., using the 0 percent discount rate) for the scenario in which
workers are uniformly exposed to silica for 45 years range from $7.3
billion to $19.3 billion annually. In Table VII-28a, for 45 years
tenure, using a 3 percent discount rate, the annualized benefits range
from $4.8 billion to $12.6 billion. Using a 7 percent discount rate,
the annualized benefits range from $2.7 billion to $6.9 billion. As can
be seen, going from undiscounted benefits (with a midpoint of $13.3
billion) to benefits calculated at a 7 percent discount rate (with a
midpoint of $4.8 billion) has the effect of cutting the annualized
benefits of the final rule by 64 percent.
Comparing across tenure levels for representative benefits, Table
VII-28a for 45 years tenure has total benefits at the midpoint estimate
of $8.7 billion at a 3 percent discount rate and $4.8 billion at 7
percent discount rate. Table VII-28b for 25 years tenure has total
benefits at the midpoint estimate of $10.0 billion at a 3 percent
discount rate and $5.5 billion at 7 percent discount rate. Table VII-
28c for 13 years tenure has total benefits at the midpoint estimate of
$12.3 billion at a 3 percent discount rate and $6.8 billion at 7
percent discount rate. Finally, Table VII-28d for 6.6 years tenure has
total benefits at the midpoint estimate of $16.1 billion at a 3 percent
discount rate and $9.0 billion at 7 percent discount rate.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
4. Estimates of Net Benefits of the Final Rule
OSHA has estimated as shown in Table VII-29, the monetized and
annualized net benefits of the final rule (with a PEL of 50 [micro]g/
m\3\ in general industry/maritime and construction and Table 1
governing almost all controls in Construction), based on the benefits
model and costs previously presented in this chapter and in Chapter V
of the FEA. Net benefits are the difference between benefits and costs.
Table VII-29 shows net benefits using alternative discount rates of
0, 3, and 7 percent for benefits and costs, including the previously
discussed adjustment to monetized benefits to reflect increases in real
per capita income over time.
As previously noted, the OSH Act requires the Agency to set
standards based on eliminating significant risk to the extent feasible.
An alternative criterion of maximizing net (monetized) benefits may
result in very different regulatory outcomes. Thus, this analysis of
estimated net benefits has not been used by OSHA as the basis for its
decision concerning the choice of a PEL or of ancillary requirements
for the final silica rule. Instead, it is provided pursuant to
Executive Orders 12866 and 13563. OSHA has used the 45 year
occupational tenure in its main analysis. OSHA has also examined other
possible tenures and provided the results. The occupational tenure
results are such the benefits are higher the shorter the occupational
tenure. Examination of shorter tenure would actually increase the net
benefits because more workers are exposed to silica, albeit for a
shorter time each.
Table VII-29 also shows results of estimates of annualized net
benefits for an alternative PEL of 100 [micro]g/m\3\. Under this
regulatory alternative, the PEL would be changed from 50 [micro]g/m\3\
to 100 [micro]g/m\3\ for all industries covered by the final rule, and
the action level would be changed from 25 [micro]g/m\3\ to 50 [micro]g/
m\3\ (thereby keeping the action level at one-half of the PEL). The
ancillary provisions of the standard, such as the medical surveillance
provisions, would remain the same in this alternative as in this final
rule, but would be impacted by factors such as changes in respirator
use and effects on other provisions such as medical surveillance. For
example, in the construction sector where medical surveillance
requirements are triggered by respirator use, a reduction in respirator
use would result in a decrease in the costs associated with medical
surveillance. Under this alternative, OSHA determined in the PEA that
Table 1 requirements for respirator use would be eliminated and that
only abrasive blasters and some underground construction workers, which
are not included in Table 1, would be required to wear respirators.
However, the number of mortalities and morbidities would rise if
workers were exposed to higher levels of silica. OSHA did not receive
comment on its analysis of this alternative.
As previously noted in this summary, the choice of discount rate
for annualizing benefits has a significant effect on annualized
benefits. The same is true for net benefits. For example, the net
benefits using a 7 percent discount rate for benefits are considerably
smaller than the net benefits using a 0 percent discount rate,
declining by more than half to two-thirds under all scenarios.
(Conversely, as noted in Chapter V of the FEA, the choice of discount
rate for annualizing costs has only a very minor effect on annualized
costs.)
The estimates of net benefits in Table VII-29 show that:
While the net benefits of the final rule vary
considerably--depending on the choice of discount rate used to
annualize benefits and on whether the calculated benefits are in the
high, midpoint, or low range--benefits exceed costs for the 50 [mu]g/
m\3\ PEL in all scenarios that OSHA considered (i.e., the highest
estimate for costs is lower than the lowest estimate for benefits).
The Agency's best estimate of the net annualized benefits
of the final rule--using a uniform discount rate for both benefits and
costs of 3 percent--and cognizant of the uncertainties inherent in the
analysis, is between $3.8 billion and $11.6 billion, with a midpoint
value of $7.7 billion.
The alternative of a 100 [mu]g/m\3\ PEL has lower net
benefits under all assumptions, relative to the 50 [mu]g/m\3\ PEL.
However, for this alternative PEL, benefits were also found to exceed
costs in all scenarios that OSHA considered.
One commenter, the Mercatus Institute, argued that the benefits for
the proposed rule were overestimated due to OSHA's assumption of full
compliance, and that this simultaneously underestimated costs, since
the cost of complying with existing rules is assumed away. This
commenter stated that the Agency should not assume that firms will
necessarily comply with the Agency's rules and the benefits estimates
should therefore be lower (Document ID 1819, p. 9). OSHA makes three
points in response. First, the argument is logically inconsistent--if
the Agency did not assume full compliance with the previous PELs and
assumes compliance with the new PEL, as Mercatus advocates, it is true
that the estimated costs would increase, but so would the estimated
benefits. Second, the logic for the Mercatus Institute's argument seems
to be undercut by the Mercatus Institute's own observation that the
Agency has had success in reducing silicosis, which suggests that in
the long run, at least, firms actually do comply with OSHA rules
(Document ID 1819, pp. 4-5). Finally, as discussed in the engineering
controls section of Chapter V of the FEA, the Agency has determined
that the best way for it to calculate costs and benefits is to estimate
the incremental costs and benefits of the standard by assuming full
compliance. OSHA also emphasizes that the compliance assumption applies
to both costs and benefits so that the comparison of one to the other
is not necessarily unduly weighted in either direction (an exception
would be the counterfactual scenario in which extremely high non-
compliance by a few employers changed benefits estimates substantially
but cost estimates only slightly).\125\
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\125\ If this rulemaking has the potential to increase
compliance with existing regulations, it would be appropriate for
the analysis conducted under Executive Order 12866 and 13563 to
include both cost and benefits estimates that reflect the new
compliance. This is not, however, a legal requirement of the OSH
Act. OSHA knows of no way to make such estimates and lacks any
persuasive evidence in this rulemaking record that this rulemaking
would affect compliance with the preceding PEL.
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Estimates of Incremental Benefits of the Final Rule
Incremental costs and benefits are those that are associated with
increasing the stringency of the standard. A comparison of incremental
benefits and costs provides an indication of the relative efficiency of
the final PEL and the alternative PEL. Again, OSHA has conducted these
calculations for informational purposes only and has not used this
information as the basis for selecting the PEL for the final rule.
Tables VII-30A and VII-30B show result of estimates of the costs
and benefits of reducing exposure levels from the preceding PELs of
approximately 250 [micro]g/m\3\ (for construction and maritime) and 100
[micro]g/m\3\ (for general industry) to the final rule PEL of 50
[micro]g/m\3\ and to the alternative PEL of 100 [micro]g/m\3\, using
the alternative discount rates of 3 and 7 percent. These tables also
introduce a second alternative PEL. Under this second alternative
standard, addressed in Tables VII-30A and VII-30B, the PEL would be
lowered from 50 [micro]g/m\3\ to 25 [micro]g/m\3\ for all industries
covered by the final rule, while the action level would remain at 25
[micro]g/m\3\ (because of difficulties in accurately measuring exposure
levels below 25 [micro]g/m\3\). For the construction sector under this
second alternative, Table 1 requirements would also be modified to
include respiratory protection for all workers covered under Table 1
(because all exposures for Table 1 activities are assumed to be above
25 [micro]g/m\3\), and all these covered workers would be subject to
the medical surveillance provision.\126\
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\126\ As with general industry and maritime employees, the
limited number of construction workers not covered by Table 1 and
estimated to exceed 25 [micro]g/m\3\ currently, such as abrasive
blasters, are assumed to need respiratory protection under this
alternative.
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Table VII-30A breaks out costs by provision and benefits by type of
disease and by morbidity/mortality, while Table VII-30B breaks out
costs and benefits by major industry sector or construction task
sector. As Table VII-30A shows, at a discount rate of 3 percent, a PEL
of 50 [micro]g/m\3\, relative to a PEL of 100 [micro]g/m\3\, imposes
incremental costs of $381 million per year; incremental benefits of
$4.3 billion per year, and additional net benefits of $3.9 billion per
year. The final PEL of 50 [micro]g/m\3\ also has higher net benefits
than 100 [micro]g/m\3\ either at a 3 percent or 7 percent discount
rate.
Table VII-30B continues this incremental analysis but with
breakdowns between construction and general industry/maritime. As
shown, both sectors show strong positive net benefits, which are
greater for the final PEL of 50 [micro]g/m\3\ than the alternative of
100 [micro]g/m\3\.
The estimates in Tables VII-30A and VII-30B indicate that, across
all discount rates, there are net benefits to be achieved by lowering
exposures from the preceding PEL (250 [mu]g/m\3\ or 100 [mu]g/m\3\) to
100 [mu]g/m\3\ and then, in turn, lowering them further to 50 [mu]g/
m\3\ and then to 25 [mu]g/m\3\, and the lower the PEL, the greater the
net benefits.\127\ Net benefits decline across all incremental changes
in PELs as the discount rate for annualizing benefits increases. The
incremental net benefit of reducing the PEL from 100 [mu]g/m\3\ to 50
[mu]g/m\3\ is greater than the incremental net benefit of reducing the
PEL from 50 [mu]g/m\3\ to 25 [mu]g/m\3\ under both the 3 percent
discount rate and the 7 percent discount rate.
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\127\ The lowest PEL considered as an alternative was 25 [mu]g/
m\3\. In addition, the costs exceed the benefits using the 7 percent
discount rate for the 100 [mu]g/m\3\ alternative, since quantified
benefits for the FEA are based entirely on the various quantitative
risk assessments, and the PEL for general industry is already set at
100 [mu]g/m\3\. (There would, however, be net benefits for
construction.) As noted previously, the Agency is claiming no
quantified benefits for the various ancillary provisions, such as
medical surveillance.
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However, the majority of the benefits and costs that OSHA estimates
for the final rule (PEL of 50 [mu]g/m\3\) are from the initial effort
to lower exposures from the preceding PEL of 250 [mu]g/m\3\ in both
construction and maritime to 100 [mu]g/m\3\, as shown in the 100 [mu]g/
m\3\ column and the Incremental Costs/Benefits column between the 100
[mu]g/m\3\ column and the 50 [mu]g/m\3\ column in Table VII-30A. The
majority of the costs and benefits attributable to lowering exposures
to 100 [mu]g/m\3\ are in the construction industry. OSHA did not
estimate any costs or benefits for general industry employers lowering
exposures to an alternative of 100 [mu]g/m\3\ because the preceding PEL
was already 100 [mu]g/m\3\, but a relatively small amount of costs and
benefits would be attributed to maritime employers lowering exposures
to the alternative of 100 [mu]g/m\3\ from the preceding PEL of 250
[mu]g/m\3\. Because a single standard would cover both general industry
and maritime employers, those costs and benefits are grouped together
in Table VII-30A and VII-30B.
In addition to examining alternative PELs, OSHA also examined
alternatives to other provisions of the standard. These alternatives
are discussed in the following Chapter VIII of the FEA: Regulatory
Alternatives.
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5. Sensitivity Analysis
In this section, OSHA presents the results of two different types
of sensitivity analysis. In the first type of sensitivity analysis,
OSHA made a series of isolated changes to individual cost and benefit
input parameters in order to determine their effects on the Agency's
estimates of annualized costs, annualized benefits, and annualized net
benefits. In the second type of sensitivity analysis--a so-called
"break-even" analysis--OSHA also investigated isolated changes to
individual cost and benefit input parameters, but with the objective of
determining how much they would have to change for annualized costs to
equal annualized benefits.
Again, the Agency has conducted these calculations for
informational purposes only and has not used these results as the basis
for selecting the PEL for the final rule.
a. Analysis of Isolated Changes to Inputs
The methodology and calculations underlying the estimation of the
costs and benefits associated with this rulemaking are generally linear
and additive in nature. Thus, the sensitivity of the results and
conclusions of the analysis will generally be proportional to isolated
variations a particular input parameter. For example, if the estimated
time that employees need to travel to (and from) medical screenings is
doubled, the corresponding labor costs double as well.
OSHA evaluated a series of such changes in input parameters to test
whether and to what extent the general conclusions of the economic
analysis held up. OSHA first considered changes to input parameters
that affected only costs and then changes to input parameters that
affected only benefits. Each of the sensitivity tests on cost
parameters had only a very minor effect on total costs or net costs.
Much larger effects were observed when the benefits parameters were
modified; however, in all cases, net benefits remained significantly
positive. On the whole, OSHA found that the conclusions of the analysis
are reasonably robust, as changes in any of the cost or benefit input
parameters still show significant net benefits for the final rule. The
results of the individual sensitivity tests are summarized in Table
VII-31A and B and are described in more detail below.
OSHA has tailored the sensitivity analysis to examine issues raised
by commenters, particularly with respect to costs. (For more detail,
see Chapter V of the FEA.) For each alternative, the estimated cost
increase is equivalent to the estimated decrease in net benefits
(except for minor rounding discrepancies). For instance, in the first
example of sensitivity testing, when OSHA doubled the estimated portion
of the affected self-employed population from 25 to 50 percent, and
estimates of other input parameters remained unchanged, Table VII-31A
shows that the estimated total costs of the final rule increased by
$17.9 million annually, or by about 1.7 percent, while estimated net
benefits also declined by $17.9 million, from $7,657 million to $7,639
million annually.
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In the second example, OSHA doubled the estimated familiarization
time needed to understand the requirements of the new standard
relative to OSHA's best estimate, which ranged from 4 to 40 hours
depending on establishment size (see Chapter V for more detail). As
shown in Table VII-31A, if OSHA's estimates of other input parameters
remained unchanged, the total estimated costs of the final rule
increased by $16.0 million annually, or by about 1.5 percent, while net
benefits declined by the same amount annually, from approximately
$7,657 million to $7,641 million annually.
In the third example, OSHA doubled the estimated daily amount of
housekeeping per worker necessary to comply with the standard, from 10
minutes to 20 minutes. As shown in Table VII-31A, if OSHA's estimates
of other input parameters remained unchanged, the total estimated costs
of the final rule increased by $12.5 million annually, or by about 1.2
percent, while net benefits declined by the same amount annually, from
approximately $7,657 million to $7,645 million annually.
In the fourth example, OSHA examined the effect of increasing its
estimate of the frequency with which thorough cleaning of the workplace
would be performed in general industry. The Agency examined the effect
of increasing the frequency from only one initial thorough cleaning to
the initial cleaning plus an annual thorough cleaning, or alternately,
a thorough cleaning every 5 years. As shown in Table VII-31A, if
thorough cleaning were an annual cost, the total estimated costs of the
final rule increased by $17.2 million annually, or by about 1.7
percent, while net benefits declined by the same amount annually, from
$7,657 million to $7,640 million annually. In the second variation of
this test, for a thorough cleaning every 5 years, as shown in Table
VII-31A, the increase in annual costs is only 0.2 percent.
In the fifth example, OSHA increased its estimate of respirator
use. In Chapter V of the FEA, OSHA explained that it calculated the
costs of respirators for general industry and maritime workers who will
still be exposed above the PEL after all feasible controls are in
place. In addition, to be conservative, OSHA added costs to provide
respirators to 10 percent of the remaining population. For this
sensitivity test, OSHA doubled its estimate of the amount of additional
respirator use in general industry from 10 percent to 20 percent. As
shown in Table VII-31A, the total estimated costs of the final rule
increased by $20.0 million annually, or by about 1.9 percent, while net
benefits decreased by the same amount annually, from approximately
$7,657 million to $7,637 million annually.
In the sixth example, reflecting in part the range of comments the
Agency received on the issue (discussed in detail in Chapter V), OSHA
explored the effect of increasing, and alternately decreasing, by 50
percent the size of the productivity impact arising from the use of
engineering controls in construction. As shown in Table VII-31A, if
OSHA's estimates of other input parameters remained unchanged, under
the first variation, the total estimated costs of the final rule
increased by $99.6 million annually, or by about 9.7 percent, while net
benefits declined by the same amount annually, from $7,657 million to
$7,558 million annually. Under the second variation, the decrease in
costs and increase in net benefits would be of the same magnitude, with
final estimated net benefits rising to $7,757 million.
As shown in Table VII-31B, OSHA also performed sensitivity tests on
several input parameters used to predict the benefits of the final
rule. In the first two tests, in an extension of results previously
presented in Table VII-27, the Agency examined the effect on annualized
net benefits of employing the high-end estimate of the benefits, as
well as the low-end estimate. As discussed previously, the Agency
examined the sensitivity of the benefits to both the valuation of
individual silica-related disease cases prevented, as well as the
number of lung cancer deaths prevented. Table VII-31B presents the
effect on annualized net benefits of using the extreme values of these
ranges, the high count of cases prevented and the high valuation per
case prevented, and the low count and the low valuation per case
prevented. As indicated, using the high estimate of cases prevented and
their valuation, the benefits rise by 45 percent to $12.6 billion,
yielding net benefits of $11.5 billion. For the low estimate of both
cases prevented and their valuation, the benefits decline by 45
percent, to $4.8 billion, yielding net benefits of $3.8 billion.
In the third sensitivity test of benefits, OSHA examined the effect
of raising the discount rate for benefits to 7 percent. The fourth
sensitivity test of benefits examined the effect of removing the
adjustment to monetized benefits to reflect increases in real per
capita income over time. The results of the first of these sensitivity
tests for net benefits was previously shown in Table VII-29 and is
repeated in Table VII-31B. Raising the interest rate to 7 percent
lowers the estimated benefits by 45 percent, to $4.8 billion, yielding
annualized net benefits of $3.8 billion. Removing the two-percent
annual increase to monetized benefits to reflect increases in real per
capita income over time decreases the benefits by 50 percent, to $4.3
billion, yielding net benefits of $3.3 billion.
b. "Break-Even" Analysis
OSHA also performed sensitivity tests on several other parameters
used to estimate the net costs and benefits of the final rule. However,
for these, the Agency performed a "break-even" analysis, asking how
much the various cost and benefits inputs would have to vary in order
for the costs to equal, or break even with, the benefits. The results
are shown in Table VII-32.
OSHA also performed sensitivity tests on several other parameters
used to estimate the net costs and benefits of the final rule. However,
for these, the Agency performed a "break-even" analysis, examining
how much the various cost and benefits inputs would have to vary in
order for the costs to equal, or break even with, the benefits
estimated. The results are shown in Table VII-32.
In the first break-even test on cost estimates, OSHA examined how
much costs would have to increase in order for costs to equal estimates
benefits. As shown in Table VII-32, this point would be reached if
costs increased by $7.7 billion.
In a second test, looking specifically at the estimated engineering
control costs, the Agency found that these costs would also need to
increase by $7.7 billion for costs to equal estimates benefits.
In a third sensitivity test, on benefits, OSHA examined how much
its estimated monetary valuation of an avoided illness or an avoided
fatality would need to be reduced in order for the costs to equal the
benefits. Since the total valuation of prevented mortality and
morbidity are each estimated to exceed at least $2.6 billion, while the
estimated costs are $1.0 billion, an independent break-even point for
each is impossible. In other words, for example, if no value is
attached to an avoided illness associated with the rule, but the
estimated value of an avoided fatality is held constant, the rule still
has substantial net benefits. Only through a reduction in the estimated
net value of both components is a break-even point possible.
OSHA, therefore, examined how large an across-the-board reduction
in the monetized value of all avoided illnesses and fatalities would be
necessary for the benefits to equal the costs. As shown in Table VII-
32, for costs to equal estimated benefits, the estimated value per life
saved would have to decline to $1.10 million per life saved, and an
equivalent percentage reduction to about $0.3 million per illness
prevented.
In a break-even sensitivity test, OSHA estimated how many silica-
related fatalities and illnesses would be required for benefits to
equal costs. As shown in Table VII-32, a reduction of 88 percent,
relative to the morbidity and mortality estimates is required to reach
the break-even point--566 fewer fatalities prevented annually, and 809
fewer silica-related illnesses prevented annually.
H. Regulatory Alternatives
This section discusses several major regulatory alternatives to the
final OSHA silica standard, pursuant to Executive Orders 13653 and
12866. The presentation of regulatory alternatives in this chapter
serves two important functions. The first is to demonstrate that OSHA
explored less costly ways (compared to the final rule) to provide
workers an adequate level of protection from exposure to respirable
crystalline silica. The second is tied to the Agency's statutory
requirement, which underlies the final rule, to reduce significant risk
to the extent feasible. If OSHA had been unable to support its findings
of significant risk and feasibility based on evidence presented during
notice and comment, the Agency would then have had to consider
regulatory alternatives that do satisfy its statutory obligations.
Each regulatory alternative presented here is described and
analyzed relative to the final rule. Where relevant, the Agency notes
that some regulatory alternatives are not permissible based on the
required legal findings OSHA has made regarding significant risk and
feasibility. The regulatory alternatives have been organized into four
categories similar to those used in the PEA: (1) Alternative PELs to
the new PEL of 50 [mu]g/m\3\; (2) regulatory alternatives that affect
ancillary provisions; (3) a regulatory alternative that would modify
the methods of compliance; and (4) regulatory alternatives concerning
when different provisions of the final rule would take effect.
Alternative PELs
OSHA selected a new PEL for respirable crystalline silica of 50
[mu]g/m\3\ for all industries covered by the final rule and developed
and included Table 1 for many work activities within the construction
sector. The final rule is based on the requirements of the Occupational
Safety and Health Act (OSH Act) and court interpretations of the Act.
For health standards issued under section 6(b)(5) of the OSH Act (29
U.S.C. 655(b)(5)), OSHA is required to promulgate a standard that
reduces the risk of material impairment of health to the extent that it
is technologically and economically feasible to do so (see Section II,
Pertinent Legal Authority, for a full discussion of the legal
requirements for promulgating new health standards under the OSH Act).
OSHA has conducted an extensive review of the literature on adverse
health effects associated with exposure to respirable crystalline
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the final
PEL and action level, as well as at OSHA's preceding PELs. These
analyses are presented in a background document entitled "Respirable
Crystalline Silica--Health Effects Literature Review and Preliminary
Quantitative Risk Assessment" and its final findings are described in
this preamble in Section V, Health Effects, and Section VI, Final
Quantitative Risk Assessment and Significance of Risk. The available
evidence indicates that employees exposed to respirable crystalline
silica well below the previous PELs are at increased risk of lung
cancer mortality and silicosis mortality and morbidity. Occupational
exposures to respirable crystalline silica also can result in the
development of kidney and autoimmune diseases and in death from other
nonmalignant respiratory diseases. As discussed in Section VI
Significance of Risk, in this preamble, OSHA finds that worker exposure
to respirable crystalline silica at the previous and new PELs
constitutes a significant risk and that the final standard will
substantially reduce this risk.
Section 6(b) of the OSH Act (29 U.S.C. 655(b)) requires OSHA to
determine that its standards are technologically and economically
feasible. OSHA's examination of the technological and economic
feasibility of the final rule is presented in the FEA, and is
summarized in this section (Section VII) of this preamble. For general
industry and maritime, OSHA has concluded that the final PEL of 50
[mu]g/m\3\ is technologically feasible for all affected industries. In
other words, OSHA has found that engineering and work practice controls
will be sufficient to reduce and maintain silica exposures to the PEL
of 50 [mu]g/m\3\ or below in most operations most of the time in the
affected industries in general industry, and the rule is also feasible
in maritime (feasibility for maritime (shipyards) partly depends on it
being subject to other standards regulating abrasive blasting). For
those few operations where the PEL cannot be achieved even when
employers install all feasible engineering and work practice controls,
employers in general industry and maritime can supplement controls with
respirators to achieve exposure levels at or below the PEL.
For construction, determined that the engineering and work practice
controls specified in Table 1 are feasible for all affected activities
and in most cases will keep exposures at or below 50 [mu]g/m\3\ most of
the time. For those few activities where the engineering and work
practice controls specified in Table 1 are not sufficiently protective
of worker health, Table 1 specifies respirator use to supplement those
controls. A limited number of activities, such as tunneling and
abrasive blasting, are not dealt with under Table 1, but are governed
more directly by the PEL of 50 [mu]g/m\3\, as in general industry and
maritime. For construction, while a few tasks like abrasive blasting
and those specified on Table 1 as requiring respirators cannot
achieve the PEL most of the time with engineering and work practice
controls alone, OSHA has concluded that the PEL of 50 [mu]g/m\3\ is
technologically feasible for the construction industry overall because
most operations can meet the PEL using the specified controls in Table
1or under the traditional approach.
OSHA developed quantitative estimates of the compliance costs of
the final rule for each of the affected industry sectors. The estimated
compliance costs were compared with industry revenues and profits to
provide a screening analysis of the economic feasibility of complying
with the revised standard and an evaluation of the potential economic
impacts. Industries with unusually high costs as a percentage of
revenues or profits were further analyzed for possible economic
feasibility issues. After performing these analyses, OSHA has concluded
that compliance with the requirements of the final rule would be
economically feasible in every affected industry sector.
OSHA has examined two regulatory alternatives (named Regulatory
Alternatives #1 and #2) that would modify the PEL for the final rule.
Under Regulatory Alternative #1, the final PEL would be changed from 50
[micro]g/m\3\ to 100 [micro]g/m\3\ for all industry sectors covered by
the rule, and the action level would be changed from 25 [micro]g/m\3\
to 50 [micro]g/m\3\ (thereby keeping the action level at one-half of
the PEL). Under Regulatory Alternative #2, the new PEL would be lowered
from 50 [micro]g/m\3\ to 25 [micro]g/m\3\ for all industry sectors
covered by the rule, while the action level would remain at 25
[micro]g/m\3\ (because of difficulties in accurately measuring exposure
levels below 25 [micro]g/m\3\). For the construction sector under this
second alternative, Table 1 requirements would also be modified to
include respiratory protection for all workers covered under Table 1
(because none are expected to be mostly under 25 [micro]g/m\3\ for any
of the tasks), and all these covered workers would be subject to the
medical surveillance provision.
Tables VII-33 and VII-34 present, for informational purposes, the
estimated costs, estimated benefits, and estimated net benefits of the
final rule under the new PEL of 50 [mu]g/m\3\ and for the regulatory
alternatives of a PEL of 100 [mu]g/m\3\ and a PEL of 25 [mu]g/m\3\
(Regulatory Alternatives #1 and #2), using alternative discount rates
of 3 and 7 percent. These two tables also present the incremental
costs, the estimated incremental benefits, and the estimated
incremental net benefits of going from a PEL of 100 [mu]g/m\3\ to the
new PEL of 50 [mu]g/m\3\ and then of going from the new PEL of 50
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Table VII-33 breaks out costs by
provision and benefits by type of disease and by morbidity/mortality,
while Table VII-34 breaks out costs and benefits by major industry
sector.
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As previously noted, Tables VII-33 and VII-34 also show the costs
and estimated benefits of a PEL of 25 [mu]g/m\3\ (Regulatory
Alternative #2), as well as the incremental costs and benefits of going
from the final PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Because
OSHA determined that a PEL of 25 [mu]g/m\3\ would not be feasible
(that is, engineering and work practices would not be sufficient to
reduce and maintain silica exposures to a PEL of 25 [mu]g/m\3\ or below
in most operations most of the time in the affected industries), the Agency
did not attempt to identify engineering controls or their costs for
affected industries to meet this PEL. Instead, for purposes of estimating
the costs of going from a PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\,
OSHA assumed that all workers exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\
would have to wear respirators to achieve compliance with the 25 [mu]g/m\3\
PEL. OSHA then estimated the associated additional costs for
respirators, exposure assessments, medical surveillance, and regulated
areas (the latter three for ancillary requirements specified in the
final rule).
As Tables VII-33 and VII-34 show, going from the final rule to
Regulatory Alternative #2 (PEL of 25 [mu]g/m\3\) is estimated to
prevent, annually, an additional 295 silica-related fatalities and an
additional 122 cases of silicosis. These estimates support OSHA's
finding that there is significant risk remaining at the final PEL of 50
[mu]g/m\3\. However, the Agency has determined that a PEL of 25 [mu]g/
m\3\ is not technologically feasible for most sectors or operations,
and for that reason, has not selected it.
Regulatory Alternatives That Affect Ancillary Provisions
Section 6(b)(7) of the OSH Act, 29 U.S.C. 655(b)(7), requires
standards to prescribe, where appropriate, the monitoring or measuring
of employee exposure for the protections of employees. Section 6(b)(7)
also requires the standards to prescribe, where appropriate, the type
and frequency of medical exams to be provided by employers "in order
to most effectively determine whether the health of [exposed] employees
is adversely affected by such exposure." The final rule contains
several ancillary provisions (provisions other than the PEL), including
requirements for exposure assessment, medical surveillance,
familiarization and training, regulated areas (in general industry and
maritime), and a written exposure control plan.
OSHA's reasons for including each of the ancillary provisions are
detailed in Section XV of this preamble, Summary and Explanation of the
Standards. In particular, OSHA has determined that requirements for
exposure assessment (or alternately, using specified exposure control
methods for selected construction operations) provide a basis for
ensuring that appropriate measures are in place to limit worker
exposures. Medical surveillance is particularly important because
workers exposed at levels below the new PEL are still at significant
risk of death and illness (OSHA's decision not to lower the PEL further
was due to limitations on technological feasibility, rather than a
determination that significant risk was eliminated at the new PEL).
Medical surveillance will allow for identification of respirable
crystalline silica-related adverse health effects at an early stage so
that appropriate intervention measures can be taken. Regulated areas
and a written exposure control plan are important in part because they
help limit exposure to respirable crystalline silica to as few
employees as possible. Finally, worker training is necessary to inform
employees of the hazards to which they are exposed, along with
associated protective measures, so that employees understand how they
can minimize potential health hazards. Worker training on silica-
related work practices is particularly important in controlling silica
exposures because engineering controls frequently require action on the
part of workers to function effectively.
As shown in Table VII-33, these ancillary provisions represent
approximately $340 million (or about 35 percent) of the total
annualized costs of the final rule of $962 million (using a 3 percent
discount rate). The three most expensive of the ancillary provisions
are the requirements for medical surveillance, with annualized costs of
$96 million; the requirements for training and familiarization, with
annualized costs of $94 million; and exposure assessment, with
annualized costs of $71 million.
The requirements for exposure assessment in general industry and
maritime are triggered by the action level. The exposures of workers in
construction for whom all Table 1 requirements have been met do not
have to be assessed, but if Table 1 requirements are not met, the
requirements for exposure assessment in construction would also be
triggered by the action level. As described in this preamble, OSHA has
defined the action level for the standard as an airborne concentration
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an 8-
hour time-weighted average. In this final rule, as in other OSHA health
standards, the action level has been set at one-half of the PEL.
As explained in Chapter IV of the FEA, OSHA finds that proper
implementation of engineering and work practice controls, particularly
those specified in Table 1, will eliminate much of the variability in
silica exposure that characterizes baseline conditions in the general
industry, maritime, and construction sectors. OSHA recognizes, however,
that some variability is unavoidable and uncontrollable even with such
controls. Because of this variability of employee exposures to airborne
concentrations of respirable crystalline silica, maintaining exposures
below the action level should provide reasonable assurance that
employees will not be exposed to respirable crystalline silica at
levels above the PEL on days when no exposure measurements are made.
Even when all measurements on a given day fall between the PEL and the
action level, there is some chance that on another day, when exposures
are not measured, actual exposure may exceed the PEL. When exposure
measurements are below the PEL but above the action level, the employer
cannot be certain that employees have not been exposed to respirable
crystalline silica concentrations in excess of the PEL during at least
some part of the work week. Therefore, requiring periodic exposure
measurements when the action level is exceeded provides the employer
with a reasonable degree of confidence in the results of the exposure
monitoring.
As specified in the final rule, all workers in general industry and
maritime exposed to respirable crystalline silica at or above the
action level of 25 [mu]g/m\3\ are subject to the medical surveillance
requirements. In the construction sector, medical surveillance is
triggered by respirator use for 30 days or more per year (which
generally corresponds to a risk of exposure above 50 [mu]g/m\3\ that
prompted the Table 1 respirator requirement), For the final rule, the
medical surveillance requirements will apply to an estimated 141,594
workers in general industry and 270,581 workers in construction. OSHA
estimates that 989 possible ILO 2/0 silicosis cases will be referred to
specialists annually as a result of this medical surveillance.
OSHA's conclusion is that the requirements triggered by the action
level will result in a very real and necessary, but non-quantifiable,
reduction in risk beyond that provided by the PEL alone. OSHA has
determined that these ancillary provisions (periodic exposure
assessment, medical surveillance in general industry/maritime) will
reduce significant risk in at least three ways: (1) Providing economic
incentives to employers to reduce exposures to below 25 [mu]g/m\3\ to
avoid the costs of medical surveillance and exposure monitoring; (2)
helping to ensure the PEL is not exceeded; and (3) providing medical
exams to workers exposed at the action level, resulting in additional
specialist referrals for X-ray findings consistent with silicosis and
allowing employees who find out they have a silica-related disease to
take action, such as changing jobs or wearing a respirator for
additional protection. In sum, the ancillary provisions triggered by
the action level in the final rule provide significant benefits to worker
health by providing additional layers and types of protection to
employees exposed to respirable crystalline silica. Medical surveillance
is particularly important for this rule because those exposed at the
action level are still at significant risk of illness. OSHA did not
estimate, and the benefits analysis does not include, monetary benefits
resulting from early discovery of illness. OSHA's choice of using an
action level for exposure monitoring of one-half of the PEL is based
on the Agency's enforcement experience with other standards, including
those for inorganic arsenic (29 CFR 1910.1018), ethylene oxide (29 CFR
1910.1047), benzene (29 CFR 1910.1028), and methylene chloride (29 CFR
1910.1052).
In response to comments on the proposed rule and PEA, among other
changes discussed in Chapter V, OSHA added familiarization costs and
increased estimated training costs in the FEA, and increased the cost
of an industrial hygienist when conducting exposure monitoring. These
changes, however, were the result of OSHA revisions to its cost
estimates, not changes to the text of the regulation. Medical
surveillance and exposure assessments were the ancillary provisions
that were the focus of regulatory alternatives in the PEA. For these
reasons, the Agency has examined four regulatory alternatives
(Regulatory Alternatives #3, #4, #5, and #6) involving changes to one
or the other of these two ancillary provisions. These four regulatory
alternatives are defined below and the incremental cost impact of each
is summarized in Table VII-35. In addition, OSHA has qualitatively
considered a regulatory alternative (Regulatory Alternative #7) that
would remove all ancillary provisions.
Under Regulatory Alternative #3, the action level would be raised
from 25 [micro]g/m\3\ to 50 [micro]g/m\3\ in the standard for general
industry and maritime, while keeping the PEL at 50 [micro]g/m\3\. As a
result, exposure monitoring and medical surveillance requirements would
be triggered only if workers were exposed above 50 [micro]g/m\3\. No
changes would be made to the construction standard because the medical
surveillance trigger for that standard is respirator use, not an action
level. As shown in Table VII-35, Regulatory Alternative #3 would reduce
the annualized cost of the final rule by about $85 million, using a
discount rate of 3 percent, and about $86 million using a discount rate
of 7 percent.
Under Regulatory Alternative #4, the action level in general
industry and maritime would remain at 25 [micro]g/m\3\ but
medical surveillance would now be triggered by the PEL, not the action
level. As a result, medical surveillance requirements would be
triggered only if workers in general industry and maritime were exposed
above the PEL of 50 [micro]g/m\3\. No changes would be made to the
construction standard. This alternative is similar to Alternative #3,
but because the action level would remain lower, the amount of exposure
monitoring would not decrease in Alternative #4 (applicable to general
industry and maritime (and for construction employers following the
exposure monitoring method of compliance)), exposure monitoring is
required when levels exceed the action level). As shown in Table VII-
35, Regulatory Alternative #4 would reduce the annualized cost of the
final rule by about $28 million, using a discount rate of 3 percent and
about $29 million using a discount rate of 7 percent).
Under Regulatory Alternative #5, the only change to the final rule
would be to the medical surveillance frequency requirements. Instead of
requiring qualifying workers to be offered a medical check-up every
three years, an annual medical check-up would be required to be
offered. Assuming all workers will accept this offer, as shown in Table
VII-35, Regulatory Option #5 would increase the annualized cost of the
final rule by about $110 million, using a discount rate of 3 percent
(and by about $108 million, using a discount rate of 7 percent).
Under Regulatory Alternative #6, medical surveillance would be
triggered by the PEL (in general industry and maritime), not the action
level, and all workers (including in construction) subject to medical
surveillance would be required to have a medical check-up annually
rather than triennially. As shown in Table VII-35, Regulatory
Alternative #6 would cause a net increase of the annualized cost of the
final rule by about $42 million, using a discount rate of 3 percent
(and by about $40 million, using a discount rate of 7 percent).
While the Agency expects there will be substantial benefits related
to its ancillary provisions, it does not have the same quantitative
basis for estimating benefits, and therefore does not have quantitative
estimates for the benefits of the preceding four regulatory
alternatives.
The final regulatory alternative affecting ancillary provisions,
Regulatory Alternative #7, would eliminate all of the ancillary
provisions of the final rule, including exposure assessment, medical
surveillance, training, regulated areas, and the written exposure
control plan. This alternative would be difficult to justify legally in
light of 29 U.S.C. 655(b)(5) and (b)(7) along with case law requiring
OSHA to use ancillary provisions to reduce significant risk remaining
at the PEL when these provisions result in more than a de minimis
benefit to workers (see Section II, Pertinent Legal Authority). In any
event, it should be noted that elimination of the ancillary provisions
does not mean that all costs for ancillary provisions would disappear.
In order to meet the PEL, employers would still commonly need to
conduct exposure monitoring, train workers on the use of controls, and
set up some kind of regulated areas (in general industry and maritime)
to indicate where respirator use would be required. It is also likely
that some employers would follow the many recommendations to provide
medical surveillance for employees and establish a written exposure
control plan. OSHA has not attempted to estimate the extent to which
the costs of these activities would be reduced if they were not
formally required.
OSHA finds that the benefits estimated under the final rule will
not be fully achieved if employers do not implement the ancillary
provisions of the final rule. For example, OSHA believes that the
effectiveness of the final rule depends on regulated areas and the
written exposure control plan to further limit exposures and on medical
surveillance to identify disease cases when they do occur. For
construction work, the written exposure control plan is an integral
part of the overall scheme to protect workers engaged in activities
covered by Table 1. Without this provision, workers would risk
exposures from the activities of others and exposure monitoring would
need to be significantly increased to ensure protection for those
workers.
Both industry and worker groups have recognized that a
comprehensive standard, as opposed to a PEL alone, is needed to protect
workers exposed to respirable crystalline silica. For example, the
industry consensus standards for crystalline silica, ASTM E 1132--06,
Standard Practice for Health Requirements Relating to Occupational
Exposure to Respirable Crystalline Silica, and ASTM E 2626--09,
Standard Practice for Controlling Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities, as well
as the draft proposed silica standard for construction developed by the
Building and Construction Trades Department, AFL-CIO, have each
included comprehensive programs. These recommended standards include
provisions for methods of compliance, exposure monitoring, training,
and medical surveillance (Document ID 1466; 1504; 1509.
3. A Regulatory Alternative That Modifies the Methods of Compliance
The final standard in general industry and maritime requires
employers to implement engineering and work practice controls to reduce
employees' exposures to or below the PEL. Where engineering and/or work
practice controls are insufficient, employers are still required to
implement them to reduce exposure as much as possible, and to
supplement them with a respiratory protection program. Under the final
construction standard, employers are given two options for compliance.
The first option specifies, in Table 1 of the final rule, the exposure
control methods and respiratory protection required for compliance when
performing the specified task or operating the specified machines.
Employers choosing this option must fully and properly implement the
control methods and respiratory protection on the table to be
considered to be in compliance with Table 1. The second option largely
follows the requirements in the general industry and maritime standard:
employers must conduct exposure monitoring and provide sufficient
controls to ensure that their workers are not exposed above the PEL.
One regulatory alternative (Regulatory Alternative #8) involving
methods of compliance would be to eliminate Table 1 as a compliance
option in the construction sector. This was suggested by one commenter
(Document ID 1950), as a means of promoting innovation.
As discussed in the Summary and Explanation in detail, OSHA
fashioned the final rule as a sensible compromise between providing
clear direction for employers, in a manner that reduces compliance
burdens, and allowing for flexibility and innovation when desired.
Table 1 is an option in the final rule that promotes both goals. While
OSHA assumes that most establishments will choose to follow Table 1, in
part to avoid the cost of monitoring, it is not a requirement.
Employers are free to follow the other option (paragraph (d) of the
standard) and conduct the required monitoring and devise their own
means of complying with the PEL if they choose. To eliminate Table 1,
therefore, would actually provide less flexibility and impose
additional costs upon employers. OSHA therefore did not quantify costs
or benefits for eliminating Table 1. Nonetheless, the Agency
seriously doubts that there would be any additional benefits under
Alternative #8, and concludes that removing the Table 1 option would
significantly increase exposure monitoring costs by taking away a
carefully crafted "safe harbor" provision from employers.
Regulatory Alternatives That Affect the Timing of the Standard
The final rule will become effective 90 days following publication
of the final rule in the Federal Register. The provisions outlined in
the construction standard will become enforceable one year following
the effective date, except for those governing sample analysis (two
years). The provisions set forth in the general industry and maritime
standards will become enforceable two years following the effective
date, with the exception that the engineering and work practice control
requirements in the hydraulic fracturing industry will become
enforceable five years after the effective date.
There are many theoretical options that OSHA could explore with
regard to compliance dates. These include: Requiring the fracking
industry to follow the same compliance schedule as all other general
industry and maritime employers; going back to the dates originally
proposed (one year for engineering controls, two years for
laboratories, six months for all other provisions); allowing more time
for all employers to comply with the final rule; or allowing less time
for all employers to come into compliance. These options are explored
in detail in the Summary and Explanation for DATES. As indicated in
that discussion, there are technical issues, and there may be
additional costs, associated with advancing the compliance dates ahead
of those laid out in the final rule; in all cases, pushing back the
compliance deadlines will also push back the onset of benefits
generated by the final rule. OSHA has not quantified the costs or
benefits of either advancing or delaying any of the compliance dates
because the timing of the effective dates has the same percentage
effect on both benefits and costs.
I. Final Regulatory Flexibility Analysis
The Regulatory Flexibility Act, as amended in 1996, requires an
agency to prepare a Final Regulatory Flexibility Analysis (FRFA)
whenever it promulgates a final rule that is required to conform to the
notice-and-comment rulemaking requirements of section 553 of the
Administrative Procedure Act (APA) (see 5 U.S.C. 601-612). For OSHA
rulemakings, the FRFA analysis must contain:
1. A statement of the need for, and objectives of, the rule;
2. a statement of the significant issues raised by the public
comments in response to the initial regulatory flexibility analysis,
a statement of the assessment of the agency of such issues, and a
statement of any changes made in the proposed rule as a result of
such comments;
3. the response of the agency to any comments filed by the Chief
Counsel for Advocacy of the Small Business Administration (SBA) in
response to the proposed rule, and a detailed statement of any
change made to the proposed rule in the final rule as a result of
the comments;
4. a description of and an estimate of the number of small
entities to which the rule will apply or an explanation of why no
such estimate is available;
5. a description of the projected reporting, recordkeeping and
other compliance requirements of the rule, including an estimate of
the classes of small entities which will be subject to the
requirement and the type of professional skills necessary for
preparation of the report or record; and
6. a description of the steps the agency has taken to minimize
the significant economic impact on small entities consistent with
the stated objectives of applicable statutes, including a statement
of the factual, policy, and legal reasons for selecting the
alternative adopted in the final rule and why each one of the other
significant alternatives to the rule considered by the agency which
affect the impact on small entities was rejected; and for a covered
agency, as defined in section 609(d)(2), a description of the steps
the agency has taken to minimize any additional cost of credit for
small entities. 5 U.S.C. 604.
The Regulatory Flexibility Act further states that the required
elements of the FRFA may be performed in conjunction with or as part of
any other agenda or analysis required by any other law if such other
analysis satisfies the provisions of the FRFA. 5 U.S.C. 605.
In addition to these elements, OSHA also includes, in this section,
the recommendations from the Small Business Advocacy Review (SBAR)
Panel and OSHA's responses to those recommendations.
While a full understanding of OSHA's analysis and conclusions with
respect to costs and economic impacts on small entities requires a
reading of the complete FEA and its supporting materials, this FRFA
summarizes the key aspects of OSHA's analysis as they affect small
entities.
The Need for and Objectives of the Rule
Exposure to crystalline silica has been shown to increase the risk
of several serious diseases. Crystalline silica is the only known cause
of silicosis, which is a progressive respiratory disease in which
respirable crystalline silica particles cause an inflammatory reaction
in the lung, leading to lung damage and scarring, and, in some cases,
to complications resulting in disability and death. In addition, many
well-conducted investigations of exposed workers have shown that
exposure increases the risk of mortality from lung cancer, chronic
obstructive pulmonary disease (COPD), and renal disease. OSHA's
detailed analyses of the scientific literature and silica-related
health risks were presented in OSHA's Review of Health Effects
Literature and Preliminary QRA in the NPRM (Document ID 1711, pp. 7-
229), and are included in Section VI Significance of Risk in this
preamble.
OSHA reviewed numerous studies and found that they all demonstrated
positive, statistically significant exposure-response relationships
between exposure to crystalline silica and lung cancer mortality (see
the Health Risk section in this preamble for more detail). In addition,
OSHA noted that in 2009 the International Agency for Research on Cancer
(IARC) reaffirmed its finding that respirable crystalline silica is a
human carcinogen, identifying in its analysis an overall positive
exposure-response relationship between cumulative exposure to
crystalline silica and lung cancer mortality (see Section VI,
Significance of Risk; Document ID 1711, pp. 269-292). Based on studies,
OSHA estimates that the lifetime lung cancer mortality excess risk
associated with 45 years of exposure to respirable crystalline silica
ranges from 11 to 54 deaths per 1,000 workers at the preceding general
industry PEL of 100 [micro]g/m\3\ respirable crystalline silica, with
that risk reduced to 5 to 23 deaths per 1,000 workers at the new PEL of
50 [micro]g/m\3\ respirable crystalline silica.
OSHA has also quantitatively evaluated the mortality risk from non-
malignant respiratory disease, including silicosis and COPD. Risk
estimates for silicosis mortality are based on a study by Mannetje et
al. (2002b, Document ID 1089), as reanalyzed by ToxaChemica, Inc.
(2004, Document ID 0469), which pooled data from six worker cohort
studies to derive a quantitative relationship between silica exposure
and death rate for silicosis. For non-malignant respiratory disease
generally, risk estimates are based on an epidemiologic study of
diatomaceous earth workers, which included a quantitative exposure-
response analysis (Park et al., 2002, Document ID 0405). For 45 years
of exposure to the preceding general industry PEL, OSHA's estimates of
excess lifetime risk are 11 silicosis deaths per 1,000 workers for
the pooled analysis and 85 non-malignant respiratory disease deaths per
1,000 workers based on Park et al.'s (2002) estimates (Document ID
0405). At the new PEL, OSHA estimates silicosis and non-malignant
respiratory disease mortality at 7 and 44 deaths per 1,000,
respectively. As noted by Park et al. (2002) (Document ID 0405), it is
likely that silicosis as a cause of death is often misclassified as
emphysema or chronic bronchitis; thus, Mannetje et al.'s analysis of
deaths may tend to underestimate the true risk of silicosis mortality,
while Park et al.'s (2002) analysis would more fairly capture the total
respiratory mortality risk from all non-malignant causes, including
silicosis and COPD.
OSHA also identified five studies that quantitatively described
relationships between exposure to respirable crystalline silica and
silicosis morbidity, as diagnosed from chest radiography. Based on the
results of these studies, OSHA estimates a cumulative risk for
silicosis morbidity of 60 to 773 cases per 1,000 workers for a 45-year
exposure to the preceding general industry PEL of 100 [micro]g/m\3\
respirable crystalline silica, and 20 to 170 cases per 1,000 workers
exposed at the new PEL of 50 [micro]g/m\3\ (see Section VI,
Significance of Risk, Table VI-1).
OSHA's estimates of crystalline silica-related renal disease
mortality risk are derived from an analysis by Steenland et al. (2002,
Document ID 0448), in which data from three cohort studies were pooled
to derive a quantitative relationship between exposure to silica and
the relative risk of end-stage renal disease mortality. The cohorts
included workers in the U.S. gold mining, industrial sand, and granite
industries. OSHA's analysis for renal disease mortality shows estimated
lifetime excess risk of 39 deaths per 1,000 workers at the preceding
general industry PEL of 100 [micro]g/m\3\ respirable crystalline
silica, and 32 deaths per 1,000 workers exposed at the new PEL of 50
[micro]g/m\3\ (see Section VI, Significance of Risk, Table VI-1).
The objective of the final rule is to reduce the numbers of
fatalities and illnesses occurring among employees exposed to
respirable crystalline silica in general industry, maritime, and
construction sectors. This objective will be achieved by requiring
employers to install engineering controls where appropriate and to
provide employees with the equipment, respirators, training, exposure
monitoring, medical surveillance, and other protective measures
necessary for them to perform their jobs safely. The legal basis for
the rule is the responsibility given to the U.S. Department of Labor
through the Occupational Safety and Health Act of 1970 (OSH Act). The
OSH Act provides that, in promulgating health standards dealing with
toxic materials or harmful physical agents, the Secretary "shall set
the standard which most adequately assures, to the extent feasible, on
the basis of the best available evidence, that no employee will suffer
material impairment of health or functional capacity even if such
employee has regular exposure to the hazard dealt with by such standard
for the period of his working life." 29 U.S.C. 655(b)(5) (see Section
II, Pertinent Legal Authority for a more detailed discussion).
Summary of Significant Issues Raised by Comments on the Initial
Regulatory Flexibility Analysis (IRFA) and OSHA's Assessment of, and
Response to, Those Issues
Small business representatives commented on all aspects of this
rule, and their comments and OSHA's responses are covered throughout
this preamble and the FEA. This section of the FRFA focuses only on
comments that directly concern this FRFA or the screening analysis that
precedes it.
One commenter questioned the use of SBA definitions for small
businesses, arguing that some definitions include firms with 500
employees or more, which, according to the commenter, are too large to
constitute "small" businesses. The commenter commended OSHA for also
including an analysis of very small entities with fewer than 20
employees (Document ID 2351, Attachment 1, p. 8). OSHA determined that
both the analysis of the impacts on SBA-defined small entities and the
analysis of the impacts on very small entities (those with fewer than
twenty employees) are useful and important for examining small business
impacts.
Two commenters were concerned that their industries had not been
covered in the IRFA. The American Railroad Association noted that small
railroads had not been covered (Document ID 2366, Attachment 1, p. 4).
The commenter is correct that OSHA did not examine small entities in
this sector in the IRFA. For the FEA, OSHA has added a discussion of
small entities in the railroad industry to Chapter VI, Economic
Impacts. The Sorptive Minerals Institute also stated that their
industry was not covered in the IRFA (Document ID 4230, Attachment 1,
p. 16). As discussed in Chapter IV, the sorptive mineral industry was
covered as part of a larger industry. In any case, OSHA has excluded
exposures that result from the processing of sorptive clays from the
scope of the final rule.
Many commenters were concerned that OSHA had not used economic data
that included the effects of the recent "great recession". This issue
was addressed in the Chapter VI Introduction, but some commenters
specifically discussed this topic in reference to small entities
(Document ID 1822, Attachment 1, p. 1; 2187, Attachment 1, p. 2; 2322,
p. 13; 3433, p. 8; 4231, Attachment 1, pp. 15-17). Complete data of the
kind that OSHA needs for a thorough analysis of economic impacts were
not yet available at the time the PEA was developed. As discussed in
Chapter II, Industrial profile, the FEA, including this FRFA, uses
2012, the most recent year with complete data, as a base year and used
average profits from years including the recession and surrounding
years.
Some commenters were concerned with OSHA's estimates of small
business profits. One commenter pointed out that OSHA had relied
entirely on C corporation data, even though many affected firms might
be S corporations, partnerships or sole proprietorships (Document ID
2296, Attachment 1, p. 23). This is true, but there are no published
data on S corporation, partnership, or sole proprietorship profits, and
thus C corporation data is the best available data. As another
commenter pointed out, reported profits of small business are generally
lower than the total returns earned by owners who also act as
executives for their firms. The same commenter explained that smaller
firms have a great deal of flexibility in deciding what portions of
entity gains are reported as profits, what portions are reported as
management salaries, and what portions are reported as management
bonuses (Document ID 2163, Attachment 1, p. 7). As a result, it is
possible that OSHA has underestimated small firm profits and thus
overestimated potential impacts on profits.
Stuart Sessions argued that OSHA should have analyzed whether
smaller firms have higher or lower profits than larger firms (Document
ID 4231, Attachment 1, pp. 11-12). The limited data supplied by Mr.
Sessions, however, did not show that small firms either had larger or
smaller profits than bigger firms on an across-industry basis (Document
ID 4231, Attachment 1, p. 11). Mr. Sessions developed an economic model
that used a combination of multiple data sources to determine profit
rates of small firms (RMA and BizMiner). In Chapter III Industrial
Profile, Revenue and Profit, OSHA discusses why the Agency's analysis
does not use these alternate data sources suggested by Mr. Sessions.
Mr. Sessions, testifying on behalf of the Construction Industry Safety
Coalition, also testified that the use of data aggregated to the four-digit
NAICS code level in OSHA's analysis shields small businesses from being
captured properly in the analysis, and that "the analysis at the six-digit
level would show substantial impacts for masonry contractors who are small
business..., which the analysis currently doesn't show" (Document ID 3580,
Tr. 1402). Mr. Sessions further claimed that, even though OSHA analyzed
the costs to employers with 20 or fewer employees, the analysis still
"hid" a lot of small businesses (Document ID 3580, Tr. 1402). The use
of Internal Revenue Service's Corporation Source Book profit data at a
four-digit NAICS code level is explained in Chapter III along with a
discussion explaining why alternative data sources suggested by Mr.
Sessions are not applied in the FEA.
At least one commenter argued that OSHA might have inaccurately
estimated small firm revenues as a result of OSHA's method of
projecting revenues for years when Census data are not available
(Document ID 4231, Attachment 1, pp. 15-17). This argument is now moot,
as OSHA is using data from the 2012 Economic Census, and is not using
projected revenues in this analysis.
Some commenters argued that OSHA had not adequately accounted for
diseconomies of scale in small firms (Document ID 4231, Attachment 1,
pp. 2-5; 2307, Attachment 10, p. 25; 2322, Attachment 1, pp. 15-16).
During his testimony, Stuart Sessions testified that it was his "guess
...that small businesses are substantially more likely to be
noncompliant currently than large businesses," and requested that OSHA
conduct additional analysis to "handle the differential compliance
rates between small and large business" (Document ID 3580, Tr. 1399).
As discussed in Chapter V, OSHA has changed its approach to estimating
costs of small firms to account for diseconomies of scale in small
firms. However, there is no evidence, other than Mr. Sessions's
"guess," that small firms are less compliant than large firms.
Janet Kaboth, testifying on behalf of a small company in the brick
manufacturing industry, stated that small businesses are more impacted
by the rule because they have more difficulty accessing capital to
upgrade engineering controls:
[Engineering controls] must be purchased and paid for in the
first year of compliance....It is extremely unlikely that a
small entity such as Whitacre Greer would be able to obtain a bank
loan...for something that does not reduce costs or increase
revenue and additionally adds cost (Document ID 3589, Tr. 3397-
3399).
As discussed in Chapter VI, Economic Impacts, small firms will
typically be able to pay for the first year costs of engineering
controls from a single year's profits. Thus, there is no need to
account for possible difficulties in obtaining credit.
A different commenter requested that OSHA provide additional
guidance in Table 1 of the construction standard as a way to mitigate
the impact on small businesses (Document ID 2322, p. 6). OSHA has done
so, and agrees that it will likely ease compliance for small
construction businesses because it provides them with task-specific
guidance that will allow them to avoid more complicated exposure
monitoring processes.
Many companies, associations, and private individuals submitted
comments requesting a new SBAR Panel based a number of changes that
have occurred since the SBAR Panel for this rule was held in 2003. The
first and most common concern was that the economic data and
information gathered during the Panel have become outdated and do not
represent the dramatic changes in economic conditions that have
resulted from the boom and bust economic cycle that occurred in the
years following 2003 (Document ID 2224, p. 2; 2004, p. 1; 3580, Tr.
1274-1276; 1779, p. 2; 1767, p. 2; 1783, p. 1; 2140, p. 1; 3495, p. 2;
1798, p. 6; 1811, pp. 1-2; 2023, p. 1; 2222, p. 1; 2224, p. 2; 2230, p.
1; 2248, Attachment 1, p. 5; 2294, p. 2; 2300, p. 2; 2305, p. 13; 2279,
p. 11; 2289, p. 9; 2391, p. 2; 3275, pp. 2-3; 2075, p. 4; 2083, p. 1;
2114, Attachment 1, p. 2; 2150, p. 2; 2170, Attachment 1, p. 1; 2210,
Attachment 1, pp. 1-2; 4194, p. 5; 4210, Attachment 1, p. 2; 4217,
Attachment 1, p. 7). Some commenters claimed that their industries have
not recovered from the recession of 2008 and feel that their economic
circumstances as small entities have changed as a result (Document ID
1779, p. 2; 1767, p. 2; 1783, p. 1; 2140, p. 1; 3495, p. 2).
OSHA conducted the SBAR Panel early in the rulemaking process in
order to address small business concerns during the development of the
proposed rule. The Agency used information gathered during the SBAR
Panel to make significant changes to the proposed rule itself, as well
as to the cost, impact, and other analyses contained in the proposal.
OSHA's proposal contained six pages of tables that described every
recommendation from the SBAR Panel, along with the Agency's responses.
OSHA's extensive rulemaking process included small business
feedback not only from the original SBREFA review in 2003, but also
from the subsequent written comment period in 2013 and 2014, as well as
from the public hearings held in 2014. The rulemaking record shows the
major issues that arose with respect to technological feasibility,
costs, economic feasibility, and possible alternatives to the proposed
rule represented largely the same issues addressed by small entity
representatives (SERs) in 2003. To the extent there may be new issues
that have arisen since the SBAR Panel made its recommendations, OSHA is
confident that commenters, including small entities and the Small
Business Administration's Office of Advocacy, were able to raise those
issues and express whatever concerns they had about them later in the
rulemaking process. OSHA has addressed comments regarding recent and
current economic conditions under which small businesses are operating
by considering this information in developing the final rule and
supporting analyses.
A second concern raised by commenters who were advocating for OSHA
to hold a new SBAR Panel, related to the changes in technology and work
practices that have taken place over the last ten years. For example,
one commenter claimed that the comments of the SERs were not reflective
of the greater use of tools with dust collection capability, and other
devices currently being used that release water at the point of
cutting, to control silica dust (Document ID 2210, Attachment 1, p. 1).
However, the commenters who wanted OSHA to account for improved
technology and work practices did not generally provide information to
supplement or update the information OSHA received from the SERs,
despite opportunities to do so.
While there has been progress in the development and adoption of
technologies that reduce silica exposures, the record (including
comments from the commenters calling for a new Panel) brought out few,
if any, fundamentally new technologies for reducing silica exposure. In
any event, the advancement of technologies that would improve silica
control or reduce the cost impact of the final rule would not
necessitate a new SBAR panel.
There were also a number of construction firms that expressed
disappointment at not being able to comment on Table 1, as presented
in the proposed rule, prior to the proposed rule being issued
(Document ID 2187, p. 22; 4217, Attachment 1, p. 7; 3580, Tr. 1274-1276).
It is typical for OSHA to modify a rule as a result of the SBREFA process.
The SBREFA process is a one-time requirement, not a requirement to
conduct a new Panel every time a rule is altered in response to SBAR
Panel recommendations. The commenters, who did have the opportunity to
comment on Table 1 once it was proposed, did not present any compelling
argument regarding how the timing of their opportunity to comment impacted
their ability to communicate their recommendations about Table 1 to OSHA.
The Agency notes that it has made a number of significant changes to Table 1
since the proposal, most in response to post-proposal comments, so it is
clear that commenters had ample opportunities to recommend improvements
to Table 1.
No SERs from the hydraulic fracturing industry were included in the
2003 SBAR panel. OSHA did not determine that this industry would be
affected by this rule until the preparation of the NPRM and the PEA. As
a result, OSHA has received comments from associations and businesses
requesting a new SBAR Panel that would allow a more detailed analysis
of the potential impacts on small entities in this industry. Commenters
pointed out that the unique economic circumstances of the hydraulic
fracturing industry were not presented for public comment or analysis
on regulatory alternatives and small business impacts during the
Agency's 2003 SBAR Panel (Document ID 2301, Attachment 1, p. 63; 3589,
pp. 15-16; 2288, p. 5).
OSHA is not required to assure that every industry affected by a
rule is represented on the Panel by a SER. The hydraulic fracturing
industry had extensive opportunities to comment throughout this
rulemaking process. In fact, a number of commenters, including several
trade associations, submitted comments and testified at the hearing,
providing analysis of the hydraulic fracturing industry for the record.
OSHA sees no indication that the record would be better developed by
convening a different SBAR panel with a SER from the hydraulic
fracturing industry. OSHA has, however, extended the compliance
deadline for these firms to install the required engineering controls
required by this final rule to five years; three more years than for
establishments in general industry and four more years than for
construction firms.
Response to Comments by the Chief Counsel for Advocacy of the Small
Business Administration and OSHA's Response to Those Comments
The Chief Counsel for Advocacy of the Small Business Administration
("Advocacy") provided OSHA with comments on this rule on February 11,
2014 (Document ID 2349). Advocacy provided comment on OSHA's risk
assessment and benefits analysis; technological feasibility analysis;
cost analysis; current economic conditions; preferred alternatives; and
procedural issues.
Risk Assessment and Benefits Issues
With respect to the risk assessment, Advocacy was concerned that
OSHA was attributing benefits to reducing the PEL to 50 [mu]g/m\3\ that
perhaps would better be attributed to eliminating exposures above the
existing PEL of 100 [mu]g/m\3\ (Document ID 2349, pp. 3-4). OSHA does
not think this is the case. As discussed in the section on significant
risk, OSHA did not assess the risk of silica exposure by attributing
existing known cases of silicosis or any other disease to various PELs.
Rather, OSHA examined risk assessment studies that assessed the long
term consequences of various levels of exposure to silica. Such studies
focus on estimating the morbidity and mortality that result from
changing lifetime exposure levels from the preceding PELs of 100 [mu]g/
m\3\ in general industry and 250 [mu]g/m\3\ in construction to the new
PEL of 50 [mu]g/m\3\.
Advocacy also expressed concerns about the accuracy of older
exposure data (Document ID 2349, p. 4). OSHA's exposure profile, used
for examining feasibility and benefits, now shows only exposures
measured after 1990 and includes data from OSHA's OIS system for 2011
to 2014.
Advocacy was also concerned that OSHA might not have adequately
accounted for varying risk levels associated with different types of
silica (Document ID 2349, p. 4). OSHA carefully considered this issue
in the risk assessment section and found there were insufficient data
to demonstrate significant risk for silica exposures that result from
processing sorptive clays. As a result, OSHA excluded this processing
activity from the scope of the final standard. OSHA found that, while
the risk from other forms of silica may vary, there is evidence of
significant risk for all of the other forms of respirable crystalline
silica.
Advocacy also reported that small business representatives were
concerned that "OSHA's assumption that silica exposure occurs over a
working life of eight hours per day for 45 years does not reflect
modern working conditions" (Document ID 2349, p. 4). OSHA is required
by the OSH Act to consider the risk of a hazard over a worker's entire
working life (see 29 U.S.C. 655(b)(5)). In Chapter VII of the FEA, OSHA
also examined other possible average tenure assumptions.
Advocacy also reported that small business representatives "noted
the uncertainty of assessing silica-related risk because of confounding
factors, such as smoking or exposure to other chemicals, and the long
latency period for silica-related illness to appear" (Document ID
2349, p. 4). OSHA notes in Section VI, Significance of Risk, in this
preamble that study after study finds that incidence of the diseases
caused by exposure to silica rises with increasing exposures to silica.
In order to see this type of result, and for those results to be driven
by smoking as a confounding factor, it would be necessary not just that
the silica-using population smoke more than the comparable non-silica
using population, but also that smoking rates rise as silica exposures
increase. This seems very unlikely and there is no evidence in the
record that this is the case.
Technological Feasibility Issues
Advocacy noted that small business representatives had raised many
concerns about whether the controls OSHA indicated as appropriate to
achieve the PEL were feasible in all circumstances and could, in fact,
allow an employer to fully achieve the PEL (Document ID 2349, p. 4).
OSHA has thoroughly examined all comments on this kind of issue across
all affected industries in Chapter IV of the FEA, and OSHA notes that
employers may raise infeasibility as a defense in enforcement actions.
Advocacy also noted that small business representatives were concerned
about whether available methods of measuring exposure were sufficiently
accurate to correctly measure the action level and PEL (Document ID
2349, p. 4). OSHA has explained in Chapter IV of the FEA why existing
equipment is sufficiently accurate to correctly measure airborne
respirable silica at the levels established by the new PEL and action
level.
Advocacy said that one small business representative "noted that
increasing the volume of air needed for additional ventilation could
result in a violation of a facility's air permit" (Document ID 2349,
p. 5). While the Agency does not believe that most small employers
exhaust large enough volumes of air that the additional ventilation
required by this final standard will result in needing to alter air
permits, OSHA does acknowledge that this may be an issue for some
employers. In order to reduce the burden, should this be the case,
OSHA has given general industry employers an additional year to meet
the PEL, and has added costs for firms subject to air permitting
requirements to alter their permits to more fully assess the economic
feasibility of this rule.
Advocacy also said that one small business representative "noted
that creating regulated areas is not feasible in many open-design
facilities" (Document ID 2349, p. 5). Regulated area requirements have
been a part of OSHA health standards for many years and employers have
consistently found ways to make them work. The Agency does not expect
that establishing a regulated area for silica would be any more
difficult than establishing such an area for any of the other
substances for which OSHA has regulated area requirements. In addition,
OSHA does not have a regulated area requirement in construction where
workplaces (such as in road building or repair) are more mobile.
Cost Issues
Advocacy stated that small business representatives generally felt
that OSHA underestimated costs, and were particularly concerned about
OSHA's "cost per exposed worker" approach and OSHA's estimates of the
number of workers whose exposures are controlled per engineering
control (Document ID 2349, p. 5). The specific methodological issues
that Advocacy mentions are issues for OSHA's general industry and
maritime cost estimates, but not for construction cost estimates
because the cost estimation methodologies for the construction sector
are quite different and do not use the "cost per exposed worker"
approach. OSHA has provided detailed responses to comments on costs in
Chapter V. In general industry and maritime, OSHA continues to use the
cost per exposed worker approach and defends this approach in Chapter
V. OSHA has lowered its estimate of the number of workers whose
exposures are reduced per engineering control in response to comments
from small business representatives and others.
Advocacy also noted that small business representatives objected to
OSHA focusing on the incremental cost of moving from the preceding PELs
to the new PEL. Advocacy reported that small business representatives
believed OSHA should have included the costs of reaching the preceding
PEL in its analysis (Document ID 2349, p. 5). Contrary to Advocacy's
suggestion, OSHA did not conduct the analysis this way because it would
require an assumption that employers are not complying with OSHA's
existing requirements to meet the preceding PEL, but would now choose
to comply with a more stringent requirement. OSHA's exposure profiles
do indicate that many employers are failing to meet the preceding PELs,
but the question that the Agency has to address with this analysis for
this rulemaking is whether OSHA should require employers to meet a
lower PEL than the preceding PEL. The costs of meeting the preceding
PEL are not relevant to that decision.
Issues Concerning Current Economic Conditions
Advocacy reported that "small business representatives stated that
OSHA was using older economic data that does not reflect current
economic conditions, and [thus] that OSHA's cost pass-through
assumptions are unrealistic" (Document ID 2349, p. 5). For the FEA,
OSHA is using 2012 as the base year for economic data and includes data
from the recent recession in analyzing average industry profits and
historical changes in profits and prices. OSHA has updated its findings
on the ability of firms to pass costs on to buyers in light of the
updated data, resolving Advocacy's concern on this issue.
Regulatory Alternatives
Advocacy commended OSHA for following the advice of small business
representatives and adopting the Table 1 approach for the construction
sector, but urged OSHA to make the table clearer, more workable, and
more specific, and to relieve employers of any remaining duty to
conduct exposure monitoring when engaged in Table 1 tasks (Document ID
2349, p. 6). OSHA has revised Table 1, as Advocacy and small business
representatives suggested, to provide employers with a clear
alternative to exposure monitoring and to provide greater clarity and
specificity in the descriptions of controls.
Advocacy also urged OSHA to consider the option of leaving the PEL
unchanged and instead improving enforcement, noting that this was the
option most favored by small business representatives (Document ID
2349, p. 3). However, the OSH Act commands OSHA to protect workers from
harmful substances by setting
...the standard which most adequately assures, to the extent
feasible, on the basis of the best available evidence, that no
employee will suffer material impairment of health or functional
capacity even if such employee has regular exposure to the hazard
dealt with by such standard for the period of his working life." 29
U.S.C. 655(b)(5).
The record does not indicate that workers are currently protected in
accordance with the Act. There are currently two entirely different
PELs, 100 [mu]g/m\3\ in general industry and 250 [mu]g/m\3\ in
construction. The record does not suggest either that employers in
construction cannot feasibly reach a lower PEL or that there is no
significant risk below 250 [mu]g/m\3\. The record shows that most
employers in construction currently reach a PEL of 50 [mu]g/m\3\ most
of the time (see Chapter IV) and that it is economically feasible to do
so (see Chapter VI).
OSHA did consider the option of lowering the construction PEL to
100 [mu]g/m\3\ and leaving the general industry PEL unchanged. However,
this action would not be in accordance with the OSH Act given that
there is still significant risk at a PEL of 100 [mu]g/m\3\ and that a
lower PEL is both technologically and economically feasible. As shown
in OSHA's risk assessment, there is still significant risk of material
impairment of health at levels all the way down to a lower PEL of 25
[mu]g/m\3\, but OSHA found compliance with the lower PEL of 25 [mu]g/
m\3\ to be technologically infeasible for all industries.
Finally, Advocacy urged OSHA to consider the option of abandoning
the hierarchy of controls, which is OSHA's longstanding policy of
preferring engineering controls and administrative controls over
personal protective equipment such as respirators (Document ID 2349,
pp. 4-5). This issue is addressed in the summary and explanation
section discussion of the methods of compliance provision. It should
also be noted that OSHA defines technological feasibility in terms of
what can be accomplished with engineering controls, not in terms of
what can be accomplished with respirators.
Issues With Respect to Small Business Participation
Advocacy also expressed concern that small businesses did not have
adequate opportunity for participation in the rulemaking process and
that the SBAR panel was held over ten years before the proposed rule
was issued (Document ID 2349, p. 7). OSHA responded to these concerns
in section two of this FRFA. A Description and Estimate of the Number
of Small Entities To Which the Rule Will Apply
OSHA has analyzed the impacts associated with this final rule,
including the type and number of small entities to which the standard
will apply. In order to determine the number of small entities
potentially affected by this rulemaking, OSHA used the definitions of
small entities developed by the Small Business Administration (SBA) for
each industry.
OSHA estimates that approximately 646,000 small business or
government entities would be affected by the silica standard. Within
these small entities, roughly 1.4 million workers are exposed to
crystalline silica and would be protected by this final standard. A
breakdown, by industry, of the number of affected small entities is
provided in Table III-6 in Chapter III of the FEA.
OSHA estimates that approximately 579,000 very small entities would
be affected by the silica standard. Within these very small entities,
roughly 785,000 workers are exposed to crystalline silica and would be
protected by the standard. A breakdown, by industry, of the number of
affected very small entities is provided in Table III-7 in Chapter III
of the FEA.
A Description of the Projected Reporting, Recordkeeping, and Other
Compliance Requirements of the Rule
Tables VII-36 and VII-37 show the average costs of the silica
standard and the costs of compliance as a percentage of profits and
revenues by NAICS code for, respectively, small entities (classified as
small by SBA) and very small entities (those with fewer than 20
employees). The costs for SBA defined small entities ranges from a low
of $295 per entity for entities in NAICS 238200 Building Equipment
Contractors, to a high of about $161,651 for NAICS 213112 Support
Activities for Oil and Gas Operations.
The cost for very small entities ranges from a low of $223 for
entities in NAICS 238200 Building Equipment Contractors, to a high of
about $119,072 for entities in NAICS 213112 Support Activities for Oil
and Gas Operations.
Tables VII-38a and VII-38b show the unit costs which form the basis
for OSHA's cost estimates for the average small entity and very small
entity.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
Description of the Steps OSHA Has Taken To Minimize the Significant
Economic Impact on Small Entities Consistent With the Stated Objectives
of Applicable Statutes and Statement of the Reasons for Selecting the
Alternative Adopted in the Final Rule
OSHA has made a number of changes in the final silica rule that
will serve to minimize significant impacts on small entities consistent
with the objectives of the OSH Act.
First, OSHA has made two changes to the scope of the rule that will
minimize impacts for small business. OSHA has eliminated from the scope
of the rule exposures that result from the processing of sorptive
clays. OSHA's analysis did not determine whether any or all of the
processers of sorptive minerals are small businesses, but to the extent
they are, this change will reduce impacts on such entities. OSHA has
also rewritten the scope of the rule with respect to the coverage of
employers whose employees are exposed to silica at levels below the
action level. The final rule does not apply to employers in general
industry and maritime where the employer has objective data
demonstrating that employee exposure to respirable crystalline silica
will remain below 25 [mu]g/m\3\ as an 8-hour time-weighted average
under any foreseeable conditions, and does not apply in construction
where employee exposure will remain below 25 [mu]g/m\3\ as an 8-hour
time-weighted average under any foreseeable conditions (see Scope in
Section XV, Summary and Explanation of the Standards). OSHA expects
that these changes may remove all compliance duties for some small
businesses, possibly including carpenters, plumbers, and electricians,
whose employees' only exposures to respirable crystalline silica is in
small amounts for short-duration tasks that are performed infrequently.
OSHA also revised Table 1 for the construction industry in ways
that will minimize impacts on small businesses. OSHA requested comment
on the approach for construction in the NPRM. After carefully reviewing
the comments received on this issue, the Agency significantly revised
the structure of the construction rule to focus on the tasks known to
generate high exposures to respirable crystalline silica and to expand
Table 1 to cover almost all of them (tunnel boring and abrasive
blasting are the exceptions). Under this final rule, where employers
fully and properly implement the specified engineering controls, work
practices, and respiratory protection for each employee engaged in a
task identified on Table 1, the employer is not also required to
conduct exposure assessments to determine compliance with the PEL.
Specifying the kinds of dust controls for construction tasks that are
expected to reduce exposures to the 50 [micro]g/m\3\ target, as an
option in lieu of a performance-oriented approach involving a PEL and
regular exposure assessment, will make compliance easier for
construction employers. Some commenters indicated that this specific
guidance is particularly beneficial to small businesses that may not
have as many resources to develop their own compliance plans (e.g.,
Document ID 2322-A1, p. 16). The Agency also revised the notes and
specifications on Table 1 to clarify what is required for employers to
fully and properly implement the specified engineering controls, work
practices, and respiratory protection for tasks on Table 1 (see
Specified Exposure Control Methods in Section XV, Summary and
Explanation of the Standards).
After carefully reviewing the comments received on respiratory
protection requirements for the construction standard and the exposure
data in the record (described in Chapter IV of the FEA), OSHA
identified those situations where respiratory protection is necessary
and made significant revisions to the respiratory protection
requirements specified on Table 1 based on those findings. The result
is that respiratory protection is not required for most of the tasks
covered by Table 1 (see Specified Exposure Control Methods in Section
XV, Summary and Explanation of the Standards).
For this final rule, the Agency has significantly revised the
requirements for initial exposure assessment and periodic exposure
assessment in order to provide employers with greater flexibility. The
standard allows the employer to use either the performance option or
the scheduled monitoring option for initial and periodic exposure
assessments. OSHA also clarified that the performance option provides
employers with flexibility in the methods used to assess employee
exposures, and provided examples of how employers can accurately
characterize employee exposures using the performance option (see
Exposure Assessment discussion in Section XV, Summary and Explanation
of the Standards).
At the suggestion of many commenters, OSHA has eliminated regulated
area/access control plan requirements in construction. Employers in
construction now have more flexibility in determining the best way to
control exposures through a written exposure control plan.
In the final rule, OSHA has agreed with many commenters to
eliminate the requirements for protective clothing, and thus has
reduced costs to small businesses.
OSHA requested comment on the use of wet methods as a substitute
for dry sweeping in the NPRM. After carefully reviewing the comments
received on this issue, the Agency revised the provision to prohibit
dry sweeping only where such activity could contribute to employee
exposure to respirable crystalline silica. Moreover, the standard
contains an exception to the prohibition on dry sweeping in such
circumstances if wet sweeping, HEPA-filtered vacuuming, or other
methods that minimize the likelihood of exposure are not feasible (see
Housekeeping in Section XV, Summary and Explanation of the Standards).
In the NPRM, OSHA requested comment on the prohibition of employee
rotation to achieve compliance when exposure levels exceed the PEL.
After carefully reviewing the comments received on this issue, OSHA
removed the prohibition on employee rotation from the rule (see Methods
of Compliance in Section XV, Summary and Explanation of the Standards).
OSHA examined the issue of a 30-day exemption in the NPRM. After
carefully reviewing the comments received on this issue, the Agency
decided not to include a 30-day exemption from the requirement to
implement engineering and work practice controls. However, OSHA
clarified that where engineering controls are not feasible, such as for
certain maintenance and repair activities, the use of respirators is
permitted (see Methods of Compliance and Respiratory Protection in
Section XV, Summary and Explanation of the Standards).
OSHA adopted these alternatives to reduce costs and regulatory
burdens consistent with the requirements of the OSH Act and court
interpretations of the Act. For health standards issued under section
6(b)(5) of the OSH Act, OSHA is required to promulgate a standard that
reduces significant risk to the extent that it is technologically and
economically feasible to do so (see Section II, Pertinent Legal
Authority, for a full discussion of OSHA legal requirements).
OSHA has conducted an extensive review of the literature on adverse
health effects associated with exposure to respirable crystalline
silica. The Agency has also developed estimates of the risk of silica-
related diseases assuming exposure over a working lifetime at the
proposed PEL and action level, as well as at OSHA's preceding PELs.
These analyses are summarized in this preamble in Section V, Health
Effects and Quantitative Risk Analysis. The available evidence indicates
that employees exposed to respirable crystalline silica well below the
preceding PELs are still at increased risk of lung cancer mortality and
silicosis mortality and morbidity. Occupational exposures to respirable
crystalline silica also may result in the development of kidney and
autoimmune diseases and in death from other nonmalignant respiratory
diseases, including chronic obstructive pulmonary disease (COPD).
As discussed in Section VI, Significance of Risk, in this preamble,
OSHA determined that worker exposure to respirable crystalline silica
constitutes a significant risk and that the final standard will
substantially reduce this risk. Further, there is significant risk well
below the new PEL of 50 [mu]g/m\3\, but OSHA has determined that
achieving a PEL of 25 [mu]g/m\3\ is not technologically feasible.
Section 6(b) of the OSH Act requires OSHA to determine that its
standards are technologically and economically feasible. OSHA's
examination of the technological and economic feasibility of the final
rule is presented in the FEA and FRFA. OSHA has concluded that the new
PEL of 50 [mu]g/m\3\ is technologically feasible for all affected
sectors in general industry and maritime and that Table 1 is
technologically feasible for construction.
For those few operations where the new PEL is not technologically
feasible, even when workers use recommended engineering and work
practice controls, employers can supplement controls with respirators
to achieve exposure levels at or below the new PEL.
OSHA developed quantitative estimates of the compliance costs of
the final rule for each of the affected industry sectors in Chapter V
of the FEA. The estimated compliance costs were compared with industry
revenues and profits to provide a screening analysis of the economic
feasibility of complying with the revised standard and an evaluation of
the potential economic impacts in Chapter VI of the FEA. Industries
with unusually high costs as a percentage of revenues or profits were
further analyzed for possible economic feasibility issues. After
performing these analyses, OSHA has concluded that compliance with the
requirements of the final rule will be economically feasible in every
affected industry sector.
OSHA has also provided analyses of the costs and benefits of
alternative PELs, though it should be pointed out these are for
informational purposes only. Benefit cost analysis cannot be used as a
decision criteria for OSHA health standards under the OSH Act. OSHA has
examined two regulatory alternatives (named Regulatory Alternatives #1
and #2) that would have modified the PEL for the final rule. Under
Regulatory Alternative #1, the PEL would have been 100 [mu]g/m\3\ for
all affected industry sectors, and the action level would have been 50
[mu]g/m\3\ (thereby keeping the action level at one-half of the PEL).
For the construction sector under Regulatory Alternative #1, Table 1
requirements for respirator use would have been eliminated for all
workers performing Table 1 tasks. Under this alternative, only abrasive
blasters and underground construction workers would have been required
to wear respiratory protection, and only workers wearing respirators in
these operations would have been subject to the medical surveillance
provision. Under Regulatory Alternative #2, the PEL would have been 25
[mu]g/m\3\ for all affected industry sectors, while the action level
would have remained at 25 [mu]g/m\3\ (because of difficulties in
accurately measuring exposure levels below 25 [mu]g/m\3\). For the
construction sector under Regulatory Alternative #2, Table 1
requirements would have been modified to include respiratory protection
for all workers covered under Table 1, and all these covered workers
would have been subject to the medical surveillance provision.
Table VII-39 presents, for informational purposes, the estimated
costs, benefits, and net benefits of the final rule under Regulatory
Alternatives #1 and #2, using alternative discount rates of 3 and 7
percent. The tables also present the incremental costs, the incremental
benefits, and the incremental net benefits of going from a PEL of 100
[mu]g/m\3\ to the new PEL of 50 [mu]g/m\3\ and then of going from the
new PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ for general industry
and maritime, as well as the effects in construction of the
corresponding changes to Table 1 under Regulatory Alternatives #1 and
#2. Table VII-39 breaks out costs by provision and benefits by type of
disease and by morbidity/mortality.
Because OSHA determined that a PEL of 25 [mu]g/m\3\ would not be
feasible (that is, engineering and work practices would not be
sufficient to reduce and maintain silica exposures to a PEL of 25
[mu]g/m\3\ or below in most operations most of the time in the affected
industry sectors in general industry and maritime), the Agency did not
attempt to identify engineering controls or their costs for this
alternative PEL. Instead, for purposes of estimating the costs of going
from a PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\, OSHA assumed
that all workers exposed between 50 [mu]g/m\3\ and 25 [mu]g/m\3\ would
have to wear respirators to achieve compliance with a PEL of 25 [mu]g/
m\3\. OSHA then estimated the associated additional costs for
respirators, exposure assessments, medical surveillance, and regulated
areas (the latter three for ancillary requirements specified in the
final rule). For the construction sector under Regulatory Alternative
#2, as previously indicated, Table 1 requirements would be modified to
include respiratory protection for all covered workers, and all covered
workers would be subject to the medical surveillance provision.
As shown in Table VII-39, going from the final rule to Regulatory
Alternative #2 would prevent, annually, an additional 295 silica-
related fatalities and an additional 122 cases of silicosis. These
estimates support OSHA's finding that there is significant risk
remaining at the new PEL of 50 [mu]g/m\3\. However, the Agency has
determined that it cannot select Regulatory Alternative #2 because a
PEL of 25 [mu]g/m\3\ is not technologically feasible and this
alternative would require extensive use of respirators for those using
Table 1 under the construction standard (see the Technological
Feasibility Summary in this preamble for a further discussion of the
feasibility of a PEL of 25 [mu]g/m\3\).
Recommendations From the SBAR Panel and OSHA's Responses
Table VII-40 lists all of the SBAR Panel recommendations and OSHA's
responses to these recommendations.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
VIII. Paperwork Reduction Act
The final general industry/maritime ("the general industry
standard") and construction standards ("the standards") for
respirable crystalline silica contain collections of information (also
referred to as "paperwork" requirements) that are subject to review
by the Office of Management and Budget (OMB). In accordance with the
Paperwork Reduction Act (PRA) (44 U.S.C. 3506(c)(2)), OSHA solicited
public comments on the Respirable Crystalline Silica Standards for
General Industry, Shipyard Employment and Maritime Terminals (29 CFR
1910.1053) and Construction (29 CFR 1926.1053) Information Collection
Request (ICR) (paperwork burden hour and cost analysis) for the
proposed rule. The Department also submitted this ICR to OMB for review
in accordance with 44 U.S.C. 3507(d) on September 12, 2013. On January
23, 2014, OMB authorized the Department to use OMB Control Number 1218-
0266 in future paperwork submissions involving this rulemaking. OMB
commented, "This OMB action is not an approval to conduct or sponsor
an information collection under the Paperwork Reduction Act of 1995"
(see http://www.reginfo.gov/public/do/PRAViewICR?ref_nbr=201111-1218-004).
The proposed rule invited the public to submit comments to OMB, in
addition to OSHA, on the proposed collections of information with
regard to the following:
Whether the proposed collections of information are
necessary for the proper performance of the Agency's functions,
including whether the information is useful;
The accuracy of OSHA's estimate of the burden (time and
cost) of the collections of information, including the validity of the
methodology and assumptions used;
The quality, utility, and clarity of the information
collected; and
Ways to minimize the compliance burden on employers, for
example, by using automated or other technological techniques for
collecting and transmitting information (78 FR 56438).
No public comments were received specifically in response to the
proposed ICR and supporting documentation submitted to OMB for review.
However, public comments submitted in response to the Notice of
Proposed Rulemaking (NPRM), described earlier in this preamble,
substantively addressed collections of information and contained
information relevant to the burden hour and costs analysis. OSHA
considered these comments when it developed the revised ICR associated
with these final rules.
The Department of Labor submitted the final ICR on the date of
publication, containing a full analysis and description of the burden
hours and costs associated with the collections of information of the
final rule, to OMB for approval. A copy of the ICR is available to the
public at http://www.reginfo.gov/public/do/PRAViewICR?ref_nbr=201509-1218-004
(this link will only become active the day following publication of
this notice). OSHA will publish a separate notice in the Federal Register
that will announce the results of that review. That notice will also
include a summary of the collections of information and burdens imposed
by the new standard. A Federal agency cannot conduct or sponsor a
collection of information unless it is approved by OMB under the PRA,
and the collection of information notice displays a currently valid
OMB control number (44 U.S.C. 3507(a)(3)). Also, notwithstanding any
other provision of law, no employer shall be subject to penalty for
failing to comply with a collection of information if the collection
of information does not display a currently valid OMB control number
(44 U.S.C. 3512).
The major collections of information found in the standards are
listed below.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
The collections of information in the rule are needed to assist
employers in identifying and controlling exposures to respirable
crystalline silica in the workplace, and to address respirable
crystalline silica-related adverse health effects. OSHA will also use
records developed in response to these standards to determine
compliance.
The final rule imposes new collections of information for purposes
of the PRA. In response to comments on the proposed rule, OSHA has
revised provisions of the final rule that affect the collections of
information. These revisions include:
--An exception in paragraph (a)(2) of the general industry standard for
those circumstances where the employer has objective data demonstrating
that employee exposure to respirable crystalline silica will remain
below 25 micrograms per cubic meter of air (25 [mu]g/m\3\) as an 8-hour
time-weighted average (TWA) under any foreseeable conditions. The
construction standard also provides an exception where employee
exposure will remain below 25 [mu]g/m\3\ as an 8-hour TWA under any
foreseeable conditions (paragraph (a)). However, the exception in the
construction standard does not require the employer to have objective
data to support the exception.
--An additional exemption in the general industry standard for
occupational exposures that result from the processing of sorptive
clays (paragraph (a)(1)(iii)).
--Revisions to paragraph (d) of the general industry standard
(paragraph (d)(2) for construction), which sets forth requirements for
assessing employee exposures to respirable crystalline silica,
including revisions to:
[cir] General requirements for exposure assessment. Paragraph (d)(1) of
the general industry standard (paragraph (d)(2)(i) in construction) was
revised and restructured to allow employers to use either the
performance option or the scheduled monitoring option to meet their
initial and periodic exposure assessment obligations. More
specifically, these revisions include replacing the proposed (d)(1)(ii)
and (d)(1)(iii), all of (d)(2), and (d)(3) with a simplified general
requirement to assess exposures when exposures are expected to be at or
above the action level using either the performance option or the
scheduled monitoring option. Thus, the final rule does not contain an
initial assessment requirement like the proposed rule. Initial
monitoring is only required under the scheduled monitoring option and
has to be performed as soon as work begins. The proposed standard
included a requirement to assess the exposure of employees expected to
be exposed to respirable crystalline silica at or above the action
level, which consisted of an initial monitoring of employees, unless
monitoring had been performed in the previous 12 months, or the
employer had objective data to demonstrate that exposures would be
below the action level under any expected conditions, as well as
periodic exposure assessments, depending on the results of initial
monitoring, following either a scheduled monitoring option or a
performance option. These revisions from the proposed rule emphasize
the performance option in order to provide additional flexibility for
employers who are able to characterize employee exposures through
alternative methods. However, the content of the performance option
requirement remains the same as the content of the proposed
requirement.
[cir] OSHA has also not established time limitations for air
monitoring results used to characterize employee exposures under the
performance option. Although the proposed rule limited employers using
air monitoring data for initial exposure assessment purposes to data
obtained no more than twelve months prior to the rule's effective date,
there were no such time restrictions on monitoring data used to conduct
periodic exposure assessments under the performance option.
Nevertheless, many commenters found the 12-month limit on the use of
monitoring results for initial exposure assessments using existing data
to be too restrictive. OSHA has been persuaded by these commenters not
to establish time limitations for monitoring results used to assess
exposures under the performance option, as long as the employer can
demonstrate the data accurately characterize current employee exposures
to respirable crystalline silica.
[cir] Scheduled monitoring option. Paragraph (d)(3) of the general
industry standard (paragraph (d)(2)(iii) for construction) describes
the scheduled monitoring option, which provides employers with a
clearly defined, structured approach to assessing employee exposures.
OSHA made a number of minor changes to the requirements for periodic
monitoring under the scheduled monitoring option (paragraphs
(d)(3)(iii)-(d)(3)(v) of the general industry standard, paragraphs
(d)(2)(iii)(C)-(d)(2)(iii)(E) in construction) to clarify that the
"most recent" exposure monitoring sample determines how often an
employer must monitor.
[cir] Revisions to requirements to reassess exposures. Paragraph
(d)(4) of the general industry standard (paragraph (d)(2)(iv) in
construction) requires employers assessing exposures using either the
performance option or the scheduled monitoring option to reassess
employee exposures whenever there has been a change in the production,
process, control equipment, personnel, or work practices that may
reasonably be expected to result in new or additional exposures to
respirable crystalline silica at or above the action level, or when the
employer has any reason to believe that new or additional exposures at
or above the action level have occurred. OSHA added the phrase "or
when the employer has any reason to believe that new or additional
exposures at or above the action level have occurred" to the proposed
language to make clear that reassessment of exposures is required
whenever there is reason to believe that a change in circumstances
could result in new or additional exposures at or above the action
level.
--The addition of paragraph (f)(2)(i) of the general industry standard
(paragraph (g)(1) of the construction standard), which requires
employers to establish and implement a written exposure control plan
for all employees covered by the rule. Under paragraph (f)(2)(i)(A)-(C)
(paragraphs (g)(1)(i)-(iii) of the construction standard), the written
exposure control plan must contain a description of: The tasks in the
workplace that involve exposure to respirable crystalline silica; the
engineering controls, work practices, and respiratory protection used
to limit employee exposure to respirable crystalline silica for each
task; and a description of the housekeeping measures used to limit
employee exposure to respirable crystalline silica. Paragraph
(g)(1)(iv) of the construction standard requires the written exposure
control plan to contain a description of the procedures used to
restrict access to work areas, when necessary, to minimize the number
of employees exposed to respirable crystalline silica and their level
of exposure, including exposures generated by other employers or sole
proprietors. OSHA did not propose a requirement for a written exposure
control plan, but requested comment on whether to include one in the
final rule. The final rule does not include the proposed written access
control plan that the employer could prepare in lieu of establishing
regulated areas that would only apply to areas with PEL exceedances.
--Alterations to paragraph (i)(1)(i) of the general industry standard,
which requires employers to make medical surveillance available at no
cost to the employee, and at a reasonable time and place, for each
employee who will be occupationally exposed to respirable crystalline
silica at or above the action level for 30 or more days per year.
Paragraph (h)(1)(i) of the construction standard requires employers to
make medical surveillance available to employees who will be required
by the standard to use a respirator for 30 or more days per year. In
the proposed standards, OSHA specified that employers must make medical
surveillance available to those employees who would be occupationally
exposed to respirable crystalline silica above the PEL for 30 or more
days a year.
--Revisions to the medical surveillance exam requirements in paragraph
(i)(2)(iii) of the standard (paragraph (h)(2)(iii) of the standard for
construction), which allow digital X-rays, in addition to film X-rays,
and no longer allow for an equivalent diagnostic study. The paragraph
requires a chest X-ray (a single posteroanterior radiographic
projection or radiograph of the chest at full inspiration recorded on
film (no less than 14 x 17 inches and no more than 16 x 17 inches) or
digital radiography systems) interpreted and classified according to
International Labour Office (ILO) International Classification of
Radiographs of Pneumoconiosis by a NIOSH-certified B Reader. The only
substantive changes from the proposed provision are to (1) specifically
allow for the use of digital systems because OSHA concluded that they
are an equivalent diagnostic studies as film X-rays and (2) to no
longer allow for the use of an equivalent diagnostic study because OSHA
concluded there are currently no studies that are equivalent to film
and digital X-rays.
--Minor edits to paragraphs (i)(4)(i)-(iv) of the general industry
standard (paragraphs (h)(4)(i)-(iv) of the standard for construction),
which is entitled: "Information provided to the PLHCP." For example,
in paragraphs (i)(4)(i) and (iv) (paragraphs (h)(4)(i) and (iv) in the
standard for construction), "affected employee" was changed to
"employee". The word "affected" was removed because it is clear
that the paragraphs refer to employees who will be undergoing medical
examinations. In paragraph (i)(4)(iii) (paragraph (h)(4)(iii) in the
standard for construction), "has used the equipment" was changed to
"has used or will use the equipment" to make it consistent with the
earlier part of the paragraph that states "personal protective
equipment used or to be used". Changes to these paragraphs are made to
clarify OSHA's intent, which has not changed from the proposed rule.
--Revisions to the information required to be provided by the PLCHP to
the employer and the employee. In response to public comments about
employee privacy and potential discrimination or retaliation concerning
medical findings, the final rule requires a detailed written medical
report for the employee and a less detailed written medical opinion for
the employer. This is a change from the proposed rule, which required
the PLHCP to give the employer a written medical opinion that did not
include findings unrelated to respirable crystalline silica exposure,
and required the employer to give the employee a copy of the opinion.
[cir] The contents of the written medical report for the employee
are set forth in paragraphs (i)(5)(i)-(iv) of the general industry
standard (paragraphs (h)(5)(i)-(iv) of the construction standard). They
include: A statement indicating the results of the medical examination,
including any medical condition(s) that would place the employee at
increased risk of material impairment of health from exposure to
respirable crystalline silica and any medical conditions that require
further evaluation or treatment; any recommended limitations on the
employee's use of respirators; any recommended limitations on
respirable crystalline silica exposure; and a statement that the
employee should be examined by a specialist if the chest X-ray provided
in accordance with this section is classified as 1/0 or higher by the B
reader, or if referral to a specialist is deemed appropriate by the
PLHCP. The health-related contents of the PLHCP's report to the
employee are fairly consistent with the proposed PLHCP's opinion to the
employer, but two major exceptions are noted. Because only the employee
will be receiving the written medical report, (1) the written medical
report should include diagnoses and specific information on health
conditions, including those not related to respirable crystalline
silica and (2) medical conditions that require further evaluation or
follow-up are not limited to those related to respirable crystalline
silica exposure. Although the employer will not be responsible for
further evaluation of conditions not related to respirable crystalline
silica exposure, the PLHCP has an ethical obligation to inform the
employee about those conditions. In addition, a minor difference from
the proposed opinion is that the report specifies limitations of
respirator use rather than personal protective equipment (PPE), because
a respirator is the only type of PPE required under this rule.
[cir] The contents of the PLHCP's written medical opinion for the
employer are presented in paragraphs (i)(6)(i)(A)-(C) and
(i)(6)(ii)(A)-(B) of the general industry standard (paragraphs
(h)(6)(i)(A)-(C) and (h)(6)(ii)(A)-(B) of the construction standard).
The contents of the written opinion are to include only the following:
The date of the examination, a statement that the examination has met
the requirements of the standard, and any recommended limitations on
the employee's use of respirators. Paragraphs (i)(6)(ii)(A)-(B) of the
general industry standard (paragraphs (h)(6)(ii)(A)-(B) of the
construction standard) state that if the employee provides written
authorization, the written opinion provided to the employer must
also contain: Any recommended limitations on exposure to respirable
crystalline silica and a statement that the employee should be examined
by a specialist if the chest X-ray provided in accordance with the
standard is classified as 1/0 or higher by the B reader, or if referral
to a specialist is otherwise deemed appropriate by the PLHCP.
As noted above, OSHA proposed that the employer obtain a more detailed
written medical opinion from the PLHCP. In the final rule, the only
medically related information that is to be reported to the employer
without authorization from the employee is limitations on
respirator use.
[cir] Under paragraph (i)(5) of the general industry standard
(paragraph (h)(5) of the construction standard), the employer must
ensure that the PLHCP explains the results of the examination to the
employee and gives the employee a written report within 30 days of each
medical examination performed. Under paragraphs (i)(6)(i) and
(i)(6)(iii) of the general industry standard (paragraphs (h)(6)(i) and
(h)(6)(iii) of the construction standard), employers must ensure that
the PLHCP gives them and that the employee receives a copy of the
employer's written medical opinion within 30 days of each medical
examination. OSHA had proposed that the employer obtain the PLHCP's
medical opinion within 30 days of the medical examination and then
provide a copy to the employee within 2 weeks after receiving it.
[cir] The proposed opinion for the employer called for a statement
that the PLHCP had explained to the employee the results of the medical
examination, including findings of any medical conditions related to
respirable crystalline silica exposure that require further evaluation
or treatment, and any recommendations related to use of protective
clothing or equipment. As noted above, OSHA has retained the
requirement that the employer ensure that the PLHCP explains the
results to the employee in paragraph (i)(5) of the standard (paragraph
(h)(5) of the standard for construction), but no longer requires the
PLCHP to include a statement of this fact in the opinion for the
employer. OSHA is not mandating how the employer ensures that the
employee gets the required information because there are various ways
this could be done, such as in a contractual agreement between the
employer and PLHCP. PLHCPs could still include the verification in the
PLHCP's opinion for the employer if that is a convenient method for
them to do so.
--Changes to the provisions regarding referral to a specialist.
Paragraphs (i)(5)(iv) and (i)(6)(ii)(B) of the general industry
standard (paragraphs (h)(5)(iv) and (h)(6)(ii)(B) of the construction
standard) specifies that the PHLCP include a statement that the
employee should be examined by a specialist if the X-ray is classified
as 1/0 or higher by the B reader, or if referral to a specialist is
deemed appropriate by the PLHCP. Those paragraphs now indicate referral
to a "specialist." OSHA has added "specialist" to the definitions
in paragraph (b) of the standards, to allow referrals to specialists
who are American Board Certified in Pulmonary Disease or Occupational
Medicine. OSHA proposed examination by an American Board Certified
Specialist in Pulmonary Disease and concludes that expansion of the
specialist definition to include board certified occupational medicine
physicians will mean that more physicians will be available for
referrals, making appointments easier to get.
--Changes to the requirements regarding information given by the
specialist to the employer and employee. Under paragraph (i)(7)(iii) of
the general industry standard (paragraph (h)(7)(iii) of the standard
for construction), the employer must ensure that the specialist
explains medical findings to the employee and gives the employee a
written medical report (i.e., a report containing results of the
examination, including conditions that might increase the employee's
risk from exposure to respirable crystalline silica, conditions
requiring further follow-up, recommended limitations on respirator use,
and recommended limitations on respirable crystalline silica exposure,
as required by paragraph (i)(5) except (i)(5)(iv) of the general
industry standard ((h)(5) except (h)(5)(iv) of the construction
standard). The reasons why the specialist is to give the employee this
information and the changes from the proposed rule are discussed above,
under the requirements for the PLHCP's report. Likewise, for the same
reasons as addressed above, paragraph (i)(7)(iv) of the standard
(paragraph (h)(7)(iv) of the standard for construction) requires the
specialist to provide the employer with a medical opinion (i.e.,--an
opinion indicating the date of the examination, any recommended
limitations on the employee's use of respirators, and with the written
authorization of the employee, any recommended limitations on the
employee's exposure to respirable crystalline silica, as required by
paragraph (i)(6) (except (i)(6)(i)(B) and (i)(6)(ii)(B)) of the general
industry standard (paragraph (h)(6) (except (h)(6)(i)(B) and
(h)(6)(ii)(B)) of the construction standard)).
--Changes to the requirements regarding maintenance of monitoring data
records by employers. Paragraph (k)(1)(i) of the general industry
standard (paragraph (j)(1)(i) of the construction standard), the
substance of which remains unchanged from the proposed standards,
requires the employer to make and maintain accurate air monitoring data
records of all exposure measurements taken to assess employee exposure
to respirable crystalline silica, as prescribed in paragraph (d) of the
general industry standard (paragraph (d)(2) of the construction
standard). OSHA has added the words "make and" prior to "maintain"
in order to clarify that the employer's obligation is to create and
preserve such records. The language in this provision is consistent
with OSHA's standard on access to employee exposure and medical
records, which refers to employee exposure and medical records that are
made or maintained (29 CFR 1910.1020(b)(3)). This clarification has
also been made for other records required by the silica rule (29 CFR
1910.1053(k)(2)(i), 29 CFR 1910.1053(k)(3)(i), 29 CFR
1926.1153(j)(2)(i), and 29 CFR 1926.1153(j)(3)(i)). In addition, OSHA
now refers to "measurements taken to assess employee exposure" rather
than "measurement results used or relied on to characterize employee
exposure" in paragraph (k)(1)(i) of the general industry standard
(paragraph (j)(1)(i) of the construction standard). This change is non-
substantive, and is intended to clarify OSHA's intent that all
measurements of employee exposure to respirable crystalline silica be
maintained.
--Changes to the requirement for maintaining air monitoring data
records by employers. OSHA has made one modification in the rule to
describe the information required in the records that differs from the
proposed rule in paragraph (k)(1)(ii)(B) (paragraph (j)(1)(ii)(B) of
the construction standard) and that is to change "the operation
monitored" to "the task monitored." Both "task" and "operation" are
commonly used in describing work. However, OSHA uses the term "task"
throughout the rule, and the Agency is using "task" in the
recordkeeping provision for consistency and to avoid any potential
misunderstanding that could result from using a different term.
This change neither increases nor decreases an employer's obligations
as set forth in the proposed standards.--Changes to the requirements
regarding maintenance of objective data records by employers.
Paragraph (k)(2)(i) of the general industry standard (paragraph
(j)(2)(i) for construction), the substance of which remains unchanged
from the proposed rule, requires employers who rely on objective
data to keep accurate records of the objective data. Paragraph (k)(2)(ii)
of the general industry standard (paragraph (j)(2)(ii) of the
construction standard) requires the record to include: The
crystalline silica-containing material in question; the source
of the objective data; the testing protocol and results of testing;
a description of the process, task, or activity on which the
objective data were based; and other data relevant to the process,
task, activity, material, or exposures on which the objective data were
based. Paragraphs (k)(2)(ii)(D) and (E) of the general industry
standard (paragraphs (j)(2)(ii)(D) and (E) of the construction
standard) have been modified from the proposed rule to substitute the
word "task" for "operation", and to clarify the requirements for
records of objective data. These changes do not affect the employer's
obligations as set forth in the proposed standards.
--Changes to the requirements regarding the maintenance of medical
surveillance records by employers. In paragraph (k)(3)(ii)(B) and (C)
of the general industry standard (paragraph (j)(3)(ii)(B) and (C) of
the construction standard), which requires employers to make and
maintain medical surveillance records, OSHA has changed the "PLHCP's
and pulmonary specialist's written opinions" to the "PLHCPs' and
specialists' written medical opinions." The change, consistent with
paragraph (i) of the general industry standard (paragraph (h) of the
construction standard), is made to reflect the revised definition for
the term "specialist" included in the rule.
IX. Federalism
The Agency reviewed the respirable crystalline silica rule
according to the most recent Executive Order on Federalism, Executive
Order 13132, which requires that Federal agencies, to the extent
possible, refrain from limiting State policy options, consult with
States before taking actions that would restrict States' policy
options, and take such actions only when clear constitutional authority
exists and the problem is of national scope (64 FR 43255 (8/10/1999)).
The Executive Order allows Federal agencies to preempt State law only
with the express consent of Congress. In such cases, Federal agencies
must limit preemption of State law to the extent possible.
Under Section 18 of the Occupational Safety and Health Act (29
U.S.C. 667), Congress expressly provided that States may adopt, with
Federal approval, a plan for the development and enforcement of
occupational safety and health standards. OSHA refers to States that
obtain Federal approval for such plans as "State-Plan States."
Occupational safety and health standards developed by State-Plan States
must be at least as effective in providing safe and healthful
employment and places of employment as the Federal standards. Subject
to these requirements, State-Plan States are free to develop and
enforce their own occupational safety and health standards.
This rule complies with Executive Order 13132. The problems
addressed by this new respirable crystalline silica rule are national
in scope. As explained in Chapter VI, Final Quantitative Risk
Assessment and Significance of Risk, employees face a significant risk
of material health impairments from exposure to crystalline silica in
the workplace. These employees are exposed to respirable crystalline
silica in general industry, construction, and shipyard workplaces
across the country. Accordingly, the rule establishes requirements for
employers in every State to protect their employees from the risks of
exposure to respirable crystalline silica. In States without OSHA-
approved State plans, Congress expressly provides for OSHA standards to
preempt State occupational safety and health standards in areas
addressed by the Federal standards. In these States, this rule limits
State policy options in the same manner as every standard promulgated
by the Agency. In States with OSHA-approved State plans, this rule does
not significantly limit State policy options. Any special workplace
problems or conditions in a State with an OSHA-approved State plan may
be dealt with by its State standard, provided the standard is at least
as effective as this rule.
X. State-Plan States
When Federal OSHA promulgates a new standard or a more stringent
amendment to an existing standard, the 28 States and U.S. territories
with their own OSHA-approved occupational safety and health plans
("State-Plan States") must revise their standards to reflect the new
standard or amendment. The State standard must be at least as effective
as the Federal standard or amendment, and must be promulgated within
six months of the publication date of the final Federal rule (29 U.S.C.
667(c)(2); 29 CFR 1953.5(a)).
A State-Plan State may demonstrate that a standard change is
unnecessary because the State standard is already the same as or at
least as effective as the new or amended Federal standard. In order to
avoid delays in worker protection, the effective date of the State
standard and any of its delayed provisions must be the date of State
promulgation or the Federal effective date, whichever is later. The
Assistant Secretary may permit a longer time period if the State timely
demonstrates that good cause exists for extending the time limitation
(29 CFR 1953.5(a)). Of the 28 States and territories with OSHA-approved
State plans, 22 cover public and private-sector employees: Alaska,
Arizona, California, Hawaii, Indiana, Iowa, Kentucky, Maryland,
Michigan, Minnesota, Nevada, New Mexico, North Carolina, Oregon, Puerto
Rico, South Carolina, Tennessee, Utah, Vermont, Virginia, Washington,
and Wyoming. Six States and territories cover only public-sector
employees: Connecticut, Illinois, Maine, New Jersey, New York, and the
Virgin Islands.
This respirable crystalline silica rule applies to general
industry, construction, and maritime, and imposes additional or more
stringent requirements as compared to the existing permissible exposure
limits for respirable crystalline silica. This rule requires that all
State-Plan States revise their general industry and construction
standards appropriately within six months of the date of this notice.
In addition, State plans that cover private sector maritime employment
or have public employees working in the maritime industry covered by
this standard would be required to adopt comparable provisions to their
maritime standards within six months of publication of the final rule.
XI. Unfunded Mandates
OSHA reviewed this rule according to the Unfunded Mandates Reform
Act of 1995 (UMRA) (2 U.S.C. 1501 et seq.) and Executive Order 13132
(64 FR 43255 (8/10/1999)). Under Section 202 of the UMRA (2 U.S.C. 1532),
an agency must prepare a written "qualitative and quantitative assessment"
of any regulation creating a mandate that "may result in the expenditure
by the State, local, and tribal governments, in the aggregate, or by
the private sector, of $100,000,000 or more" in any one year before
promulgating a final rule. OSHA's rule does not place a mandate on
State or local governments, for purposes of the UMRA, because OSHA
cannot enforce its regulations or standards on State or local
governments (29 U.S.C. 652(5)). Under voluntary agreements with OSHA,
some States require public sector entities to comply with State
standards, and these agreements specify that these State standards must
be at least as protective as OSHA standards. The Occupational Safety
and Health Act (29 U.S.C. 651 et seq.) does not cover tribal
governments in the performance of traditional governmental functions,
though it does cover tribal governments when they engage in commercial
activity. However, the rule would not require tribal governments to
expend, in the aggregate, $100,000,000 or more in any one year for
their commercial activities. As noted below, OSHA also reviewed this
rule in accordance with Executive Order 13175 on Consultation and
Coordination with Indian Tribal Governments (65 FR 67249 (11/9/2000)),
and determined that it does not have "tribal implications" as defined
in that Executive Order.
OSHA concludes that the final rule would impose a Federal mandate
on the private sector in excess of $100,000,000 in expenditures in any
one year, as documented in the Final Economic Analysis (FEA) (see
Section VII, Summary of the Final Economic Analysis and Final
Regulatory Flexibility Analysis). However, the final rule does not
trigger the requirements of UMRA based on its impact on State, local,
or tribal governments. The FEA constitutes the written statement
containing a qualitative and quantitative assessment of these
anticipated costs and benefits required under Section 202(a) of the
UMRA (2 U.S.C. 1532(a)).
XII. Protecting Children From Environmental Health and Safety Risks
Executive Order 13045 requires that Federal agencies submitting
covered regulatory actions to the Office of Management and Budget's
Office of Information and Regulatory Affairs (OIRA) for review pursuant
to Executive Order 12866 must provide OIRA with (1) an evaluation of
the environmental health or safety effects that the planned regulation
may have on children, and (2) an explanation of why the planned
regulation is preferable to other potentially effective and reasonably
feasible alternatives considered by the agency (62 FR 19885 (4/23/
1997)). Executive Order 13045 defines "covered regulatory actions" as
rules that may (1) be economically significant under Executive Order
12866 (i.e., a rulemaking that has an annual effect on the economy of
$100 million or more, or would adversely effect in a material way the
economy, a sector of the economy, productivity, competition, jobs, the
environment, public health or safety, or State, local, or tribal
governments or communities), and (2) concern an environmental health
risk or safety risk that an agency has reason to believe may
disproportionately affect children. In this context, the term
"environmental health risks and safety risks" means risks to health
or safety that are attributable to products or substances that children
are likely to come in contact with or ingest (e.g., through air, food,
water, soil, product use).
The respirable crystalline silica rule is economically significant
under Executive Order 12866 (see Section VII, Summary of the Final
Economic Analysis and Final Regulatory Flexibility Analysis). However,
after reviewing the rule, OSHA has determined that the rule would not
impose environmental health or safety risks to children as set forth in
Executive Order 13045. The rule would require employers to limit
employee exposure to respirable crystalline silica and take other
precautions to protect employees from adverse health effects associated
with exposure to respirable crystalline silica. OSHA is not aware of
any studies showing that exposure to respirable crystalline silica
disproportionately affects children, that there are a significant
number of employees under 18 years of age who may be exposed to
respirable crystalline silica, or that employees of that age are
disproportionately affected by such exposure.
A few commenters expressed concerns about exposure of children to
respirable crystalline silica through their parents' contaminated work
clothing (e.g., Document ID 4204, pp. 73-74). The American Federation
of Labor and Congress of Industrial Organizations concluded that
maintaining OSHA's longstanding hierarchy of controls in the final rule
would prevent silica dust from being carried home on work clothing
better than would a rule that relies solely on respirators to protect
workers (Document ID 4204, pp. 64-65, 72-74). OSHA agrees, and finds
that the final rule's primary reliance on engineering and work practice
controls to protect workers will result in greater protection to
children than either the prior permissible exposure limit for
respirable crystalline silica or a rule that places primary reliance on
respiratory protection.
Because OSHA does not believe that the health risks of respirable
crystalline silica have a disproportionate impact on children, OSHA
concludes the respirable crystalline silica rule does not constitute a
covered regulatory action as defined by Executive Order 13045. To the
extent children are exposed to respirable crystalline silica either as
employees or at home as a result of family members' workplace
exposures, the final rule offers greater protection than did the
previous permissible exposure limits.
XIII. Consultation and Coordination With Indian Tribal Governments
OSHA reviewed this final rule in accordance with Executive Order
13175 on Consultation and Coordination with Indian Tribal Governments
(65 FR 67249 (11/9/2000)), and determined that it does not have
"tribal implications" as defined in that Executive Order. The
Occupational Safety and Health Act (29 U.S.C. 651 et seq.) does not
cover tribal governments in the performance of traditional governmental
functions, so the rule will not have substantial direct effects on one
or more Indian tribes in their sovereign capacity, on the relationship
between the Federal government and Indian tribes, or on the
distribution of power and responsibilities between the Federal
government and Indian tribes. On the other hand, employees in
commercial businesses owned by tribes or tribal members will receive
the same protections and benefits of the standard as all other covered
employees.
XIV. Environmental Impacts
Introduction
OSHA has reviewed the final rule according to the National
Environmental Policy Act (NEPA) of 1969 (42 U.S.C. 4321 et seq.), the
regulations of the Council on Environmental Quality (40 CFR part 1500
et seq.), and the Department of Labor's NEPA procedures (29 CFR part
11). The Agency has determined that the final rule will have no
significant impact on air, water, or soil quality; plant or animal
life; the use of land; or other aspects of the external environment.
Therefore, OSHA concludes that the final standard will have no significant
environmental impacts. This conclusion reaffirms the conclusions set forth
in the Preliminary Economic Analysis (PEA).
To reach this conclusion, OSHA examined comments received about the
potential environmental impacts posed by the final rule. Comments
addressed two main issues: (1) Potential water runoff from construction
tasks; and (2) costs associated with federal, state, and local
environmental permits employers could be required to obtain as a result
of the final rule. There were no specific comments regarding soil
quality, plant or animal life, or land use. This section first lays out
OSHA's preliminary conclusions regarding environmental impacts and then
shows why the best available evidence in the rulemaking record
reaffirms those conclusions. SBREFA and Conclusions Contained in the
PEA
Pursuant to the recommendations from the Small Business Advocacy
Review Panel, the Agency investigated potential environmental impacts
and articulated its findings in the PEA. As noted in the SBREFA report
(Document ID 0937, p. 77), the Panel requested that OSHA clarify how
its silica rulemaking was related to designating silica-containing
materials as hazardous wastes. In the PEA, OSHA explained that it did
not believe silica wastes are classified as hazardous wastes for
purposes of the Environmental Protection Agency (EPA) (Document ID
1720, p. IX-68). And the contents of OSHA's final rule on silica have
no direct bearing on whether silica waste is classified as hazardous
for EPA purposes.
In addition, some Small Entity Representatives (SERs) raised the
possibility that the use of wet methods to limit silica exposures in
some areas could violate EPA rules with respect to suspended solids in
runoff unless provisions are made for recycling or settling the
suspended solids out of the water. The SBAR Panel recommended that OSHA
investigate this issue, add appropriate costs if necessary, and solicit
comment. In response, the Agency identified six construction tasks
where wet methods were utilized and found negligible costs related to
controlling excess water because the amount of water used to control
silica dust was minimal and typically did not produce runoff. OSHA's
estimate of the potential environmental impact of each of these six
equipment types was summarized in the PEA as follows:
Stationary masonry saws: Most stationary saws come
equipped with a water basin that typically holds several gallons of
water and a pump for recycling water for wet cutting. The water is
recirculated and, thus, not continually discharged. When emptied, the
amount of water is not sufficient to produce a runoff.
Hand-held masonry saws: Large quantities of water
typically are not required in order to control dust. With these saws,
water is supplied from a small capacity water tank. Any slurry residue
after cutting could be dealt with by sweeping or vacuuming.
Walk-behind and other large concrete saws: Larger concrete
saws are equipped with a tank to supply water to the blade while
cutting. These saws leave a slurry residue, but do not require so much
water as to create a runoff.
Walk-behind concrete grinders and millers: Some tools are
equipped with a water-feed system. In these, a water line from a tank,
a garden hose, or other water supply leads to the grinding head and
delivers water to spray or flood the cutting tool and/or the work
surface. When an automatic water feed is not available, a helper can
apply water directly to the cutting surface. While such wet methods
might generate enough water to create a runoff, these grinding and
milling activities are typically done during the finishing stages of
structure construction (e.g., parking garages) and are often performed
inside the structure. Thus, direct discharges to storm drains or
surface waters are unlikely.
Asphalt millers for pavement resurfacing: A typical
asphalt milling machine has a built-in reservoir from which water is
applied to the cutting drum. The amount of water used, however, is
insufficient to produce a runoff.
Impact drillers/pavement breakers: Water for dust
suppression can be applied manually or by using a semi-automated water-
feed device. In the simplest method for suppressing dust, a dedicated
helper directs a constant spray of mist at the impact point while
another worker operates the jackhammer. The helper can use a hose with
a garden-style spray nozzle to maintain a steady and carefully directed
mist at the impact point where material is broken and crushed.
Jackhammers retrofitted with a focused water mist aimed at the tip of
the blade offer a dramatic decrease in silica exposure. Although water-
fed jackhammers are not commercially available, it is neither expensive
nor difficult to retrofit equipment. Studies suggest that a water flow
rate of 1/8 to 1/4 gallon per minute is best for silica dust control.
At this rate, about 7.5 to 15 gallons of water per hour would be
applied to (i.e., sprayed on) the work area. It is unclear whether this
quantity of water applied to a moveable work area at a constant rate
would produce a runoff. If the work were in sufficient proximity to a
storm drain or surface water, the contractor might need to use a simple
barrier to prevent the water from entering the drain, or otherwise
filter it. Because the volume of water is relatively small, the costs
for such barriers are likely insubstantial and would typically overlap
with the contractor's existing obligations for a site-control plan to
prevent unwanted runoff from other causes.
In the PEA, OSHA found that employers typically have pre-existing
obligations to limit runoff of solid waste, such as from rainfall, into
storm drains. The Agency preliminarily concluded that: (1) The use of
wet methods for certain construction tasks would not cause significant
environmental problems from water runoff; and (2) employers should be
able to comply with non-OSHA environmental regulations because runoff
from wet methods can be easily controlled. As explained below, in light
of the best available evidence contained in the record, OSHA reaffirms
its preliminary conclusions.
Potential Water Runoff From Construction Tasks
While the Agency did not receive any comments directly addressing
the PEA's discussion of environmental impacts, it did receive several
comments on the water runoff issue. Most of the concerns expressed
related to construction work, although a few comments came from
entities in general industry. The construction and general industry
commenters that addressed the issue of water runoff from the use of wet
methods to comply with the final PEL included James Hardie Building
Products, Inc.; the Unified Abrasives Manufacturers' Association;
American Road & Transportation Builders Association; the General
Contractors Association of New York; the Masonry & Concrete Saw
Manufacturers Institute; and the Fertilizer Institute. None of the
commenters to raise this issue provided any evidence to establish that
runoff created by wet methods would actually create a problem (Document
ID 2322, Attachment G, p. 14; 2243, p. 2; 2245, p. 4; 2314, p. 2; 2316,
Attachment 1, pp. 2-3; 2101, pp. 6-7, 11-12). For example, one
commenter, the Construction Industry Safety Coalition, advanced a
theoretical argument that wet methods would either: (a) Require
"tremendous" amounts of water; or (b) fail to effectively control
silica. It stated:
For employers using wet methods, even attempting to meet this
"no visible dust" standard will require a tremendous amount of
water--many studies discussed in the technological feasibility
analysis certainly support this notion. Such large amounts of water
run counter to OSHA's contractor's assessment that "minimal" water
should be used to avoid environmental contamination issues. The
Agency contends that construction employers can mitigate any
environmental concerns by utilizing as little water as possible to
prevent accumulations from occurring or potentially damaging
residential or commercial buildings. Even if utilizing only a little
water will effectively reduce exposures to below the proposed PEL,
the CISC has significant concerns that it will prevent all visible
dust from being emitted (Document ID 2320, Attachment 1, pp. 9-10).
In light of the discussion set forth in Chapter VI of the FEA,
Technological Feasibility, and evidence in the record, OSHA's
preliminary findings regarding water runoff are affirmed. The Agency
concludes that the comments it received expressing concerns about the
runoff issue are unsubstantiated and theoretical and do not provide a
sufficient justification for OSHA to alter its preliminary conclusions.
As discussed in the Technological Feasibility section, OSHA finds that
appropriate wet methods will typically require only limited application
of water, possibly as little as a mist. In such conditions, the water
will evaporate before collecting into a body of water. Where a greater
water flow is necessary to suppress airborne silica, the runoff, rather
than forming a free-flowing stream, will typically consolidate into
slurry. In addition, because employers want to keep nearby structures
and materials dry, they will typically use as little water as
necessary.
OSHA finds support for these findings in the hearing testimony
compilation assembled by the Building and Construction Trades
Department. That evidence demonstrates the practical reality that water
runoff from construction tasks is insignificant (Document ID 4223, pp.
28-30). Indeed, Deven Johnson, of the Operative Plasterers' and Cement
Masons' International Association, stated that in her years of
experience in using wet methods to control relatively dusty situations
involving demolition, she had never had a problem with runoff-related
issues. She indicated that runoff tends to create a slurry, which is
easily vacuumed up (Document ID 3581, pp. 1695-1696). Gary Fore, a
consultant and former Vice President for the American National Asphalt
Pavement Association, likewise said that runoff was never a problem. He
confirmed the PEA's preliminary conclusion for asphalt milling
operations. While there may be a substantial amount of water used in
the course of a day, it is applied as an aerosol. Further, although the
pavement surface may be temporarily moist, it does not produce runoff
from the construction site (Document ID 3583, p. 2209). Finally, Donald
Hulk, Safety Director for Manafort, a construction contractor,
testified that contrary to hypothetical assertions about potential
runoff issues, his company did not find managing potential runoff from
wet methods to be a problem. His reasoning confirmed the PEA's finding
that the amount of water required for typical silica-containing dust
suppression will not create substantial runoff. Moreover, he testified
that in the case of demolition related to roadway construction, excess
water is typically absorbed into demolition debris or evaporates--which
is aided by the fact that most construction activity occurs during the
warmer parts of the year (Document ID 3583, Tr. 2384-2385).
Certain industries voiced water runoff concerns specific to their
workplaces. For example, the fertilizer industry stated its
apprehension about OSHA's "preference" for wet methods to control
silica exposure and indicated that such methods would be potentially
problematic from an environmental standpoint at its facilities
(Document ID 2101, pp. 6-7, 11-12). OSHA finds the fertilizer
industry's concern misplaced because the final standard does not
require the use of wet methods in general industry. Additionally, as
discussed in Chapter III, the Agency estimates that exposures to
respirable crystalline silica in the fertilizer industry are
sufficiently low that most fertilizer-related manufacturing industries
will not be affected by the final standard; the mixing-only fertilizer
industry, NAICS 325314, was the only one judged to be affected.
The coal-fired electric industry also raised the issue of water
runoff in its industry. The Edison Electric Institute and Alabama Power
Company indicated a potential for conflict between an EPA rulemaking
regarding ash ponds at the site of coal-fired electric utilities and
this rulemaking (Document ID 2357, pp. 28-29; 2185, Attachment 1, p.
11). OSHA considered this concern, but has concluded that this will not
be a problem in practice. The commenters never explained how the wet
methods that might be required in Table 1 for construction activities
(e.g., cutting concrete for transmission and distribution) would result
in water flowing into fly ash ponds. In any event, the Agency has found
that the proper use of wet methods will not result in significant
runoff issues for any of the industries covered by the standard.\128\
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\128\ Alabama Power also referred to problems with environmental
permits, but did not specify to which environmental permits they
were referring. Permit issues are addressed later in this section.
---------------------------------------------------------------------------
Air Quality/Permit Concerns
Regulations that will reduce the atmospheric concentration of
respirable crystalline silica in the air within industrial and other
facilities and workplaces have the potential to affect, either
positively or negatively, the amount of respirable crystalline silica
emitted by these sources into the ambient (external) environment. In
most cases, the change will be small. As discussed in Chapter V of the
FEA, Costs of Compliance, most ventilation is needed to reach the
preceding PEL rather than the new PEL. The extent to which the
reduction in the PEL--and, hence, occupational exposures--under the
OSHA standard will impact air quality depends on how employers handle
the increased volume of respirable crystalline silica captured by the
relevant control technologies. Taking into account the measures
employers are already using to comply with the existing silica PEL, and
the fact that the baghouses employers are already using capture at
least 99 percent of silica emissions (Document ID 3641, p. VII-19),
OSHA concludes that the final rule will not have a significant impact
on air quality
A number of commenters raised concerns that the final rule would
create an onerous and cost-increasing administrative burden because it
would necessitate obtaining EPA environmental permits, notably with
regard to air quality regulations and related permits and process
approvals at the state and local level. The concern was not an adverse
environmental impact, per se, but rather the burden of complying with
existing environmental rules in the context of the new OSHA standard
(e.g., Document ID 2291, Attachment 1, p. 12; 2379, Appendix 1, p. 14;
2380, Attachment 2, p. 19; 2317, pp. 2-3). OSHA's response to these
cost concerns is addressed in Chapter V of the FEA in the section on
general industry engineering control costs.
A prime concern voiced by the commenters was having to comply with
OSHA compliance deadlines while simultaneously meeting deadlines under
applicable air quality permitting regulations.
For example, the Asphalt Roofing Manufacturers Association (ARMA)
raised the issue of EPA permits related to changes in ventilation
systems.
...the proposal appears to completely disregard environmental
permitting requirements, which will present a significant time
demand in almost every case because the standard will require
increased dust collection, and releases to outside air will trigger
air pollution limitations and permitting requirements for both State
and or Federal agencies. Recent experience of ARMA members relating
to implementation of the new National Ambient Air Quality Standards
(NAAQS) for particulate matter (PM2.5) reveals that, even
in the case of minor facility modifications which emit particulate
matter, authorization to construct or modify a control device can
take more than a year to obtain. Even longer permitting times will
be experienced in cases requiring complex modeling of nearby
sources, or State or Federal approval of modeling methods and
protocol inputs. These factors could further delay the issuance of
permits by an additional twelve months, assuming the facility is
able to develop a passing model. If the model does not pass, further
modeling and review by permitting agencies, or additional emissions
abatement, may be required to obtain the permits, extending still
further this step in the process (Document ID 2291, Attachment 1, p.
12).
As the Agency explains in the Summary & Explanation section of the
preamble dealing with paragraph (j), dates, the final rule's effective
and enforcement dates have been tailored to allow a sufficient period
of time for employers to meet requirements for approval by other
regulatory agencies. (A discussion of various state permitting times
can be found in "Examples of State Environmental Agency Permit
Turnaround Times," ERG, 2015.) The Agency believes providing longer
compliance deadlines should address the primary concerns expressed by
commenters regarding the time necessary to obtain any required
environmental permit approvals. Ultimately, as discussed in the Summary
and Explanation, cases that are unusually problematic can be addressed
through OSHA's enforcement discretion if the employer can show that it
has made good faith efforts to implement engineering controls, but has
been unable to implement such controls due to the time needed for
environmental permitting.
Some industries raised permit concerns unique to their operations.
The Association of American Railroads and American Short Line and
Regional Railroad Association stated that it foresaw a need for a
permit under the Clean Water Act if a ballast was sprayed with a
chemical, which, through run off or by another means, reached a body of
water (Document ID 2366, p. 7).
OSHA considers the railroad industry's concern about the threat of
significant water contamination from chemical dust suppressant
speculative because of the limited amount of water potentially used.
Consequently, the Agency does not foresee a significant environmental
impact. Additionally, no current OSHA standard governs the use of
chemical dust suppressants. While some state or local governments may
require a permit, it is not clear this would pose a new issue for the
railroads, as OSHA believes it is likely that they already have to deal
with such issues in the context of runoff from deicing chemicals, as
well as oil and metal particles from normal operations. OSHA notes,
however, that the analysis in the railroad section of Chapter IV of the
FEA, Technological Feasibility, discusses chemical suppressants merely
as a possibility for reducing exposures, but it is not ultimately
identified as necessary to enable employers in the industry to meet the
PEL of 50 [mu]g/m\3\. Accordingly, the FEA's cost analysis for the
railroad industry does not include chemical suppressants, but assumes
the industry will use wet methods to reduce exposures, and estimates
the costs accordingly. To the extent chemical dust suppressants are
more cost-effective than water, the FEA has overestimated the cost to
the industry. And to the extent suppressants pose an environmental air
quality permitting issue, OSHA notes that suppressants are not required
under the final rule and is not including relevant permitting costs in
its analysis.
The Shipbuilders Council of America (SCA) stated that if the final
silica rule altered blasting technologies and/or facility equipment,
the data currently used for shipyard permits in certain states (e.g.,
state air and water permits) would be invalid, necessitating permit and
plan updates and creating additional costs for the industry (Document
ID 2255, p. 2). The final rule does not specify engineering control
changes in this area; nor does the Agency believe the lower PEL will
require a change in engineering controls for abrasive blasting,
relative to current standards. As laid out in Chapter V in the FEA,
employers complying with the hierarchy of controls under the existing
silica PEL and ventilation standards will already be using engineering
controls to limit exposures. OSHA has found that the only additional
feasible engineering controls employers in shipyards can implement to
reduce exposures is the use of HEPA vacuums (in lieu of dry sweeping).
Implementation of this control will reduce potential environmental
problems because the use of HEPA vacuums raises less dust than dry
sweeping.
Positive Environmental Effects
Based on its review of the record, OSHA concludes that the final
rule will potentially have a positive environmental impact. At least
one industry commenter, in the context of the hydraulic fracturing
industry, suggested that its technology, the adoption of which would
presumably be hastened by the promulgation and enforcement of the final
rule, would reduce potential environmental impacts (Document ID 3589,
Tr. 4140). In a similar vein, as discussed in both Chapters IV and V of
the FEA, the final standard actually helps construction employers'
reduce fugitive and co-generated dust, aiding in their compliance with
environmental standards related to the dust. (The issue of controlling
fugitive dust overlaps with the issue of existing employer obligations
to minimize the runoff of solid waste into public water, discussed
previously in this chapter, as well as the general expectation that
employers clean up their work sites after their work is completed, as
discussed in Chapter V).
Conclusion
As a result of this review, OSHA has reaffirmed its conclusions in
the PEA, that the silica final rule will have no significant impact on
air, water, or soil quality; plant or animal life; the use of land; or
aspects of the external environment. It finds that the final standard
is in compliance with NEPA and will have no significant environmental
impact.
XV. Summary and Explanation of the Standards
OSHA proposed two standards for occupational exposure to respirable
crystalline silica--one for general industry and maritime and a second
for construction. Both proposed standards were structured according to
OSHA's traditional approach, including separate provisions for a
permissible exposure limit (PEL), exposure assessments, and methods of
compliance, which includes a requirement to follow the hierarchy of
controls. The methods of compliance provision in the proposed
construction standard included Table 1, which specified engineering
controls, work practices, and respiratory protection for common
construction operations (now referred to as tasks). Construction
employers who would have chosen to fully implement engineering
controls, work practices, and respirators for a task in proposed Table
1 would have been exempted from conducting exposure assessments for
employees conducting that task, but would have been required to
comply with the PEL.
The structure of the final standard for general industry and
maritime remains generally consistent with other OSHA health standards.
The most significant structural change from the proposed general
industry and maritime standard is that "cleaning methods," which was
under the Methods of Compliance paragraph, is now a separate paragraph
called Housekeeping. The same change regarding Housekeeping was made to
the standard for construction. In addition both standards include a
requirement for a written exposure control plan, which is included
under the Methods of Compliance paragraph in the standard for general
industry and maritime but as a separate paragraph in the standard for
construction. Most importantly, the structure for the construction
standard is significantly different from OSHA's traditional approach to
address stakeholder concerns about compliance in the construction
industry.
Many stakeholders thought that construction employers who fully and
properly implement the engineering controls, work practices, and
respiratory protection specified in Table 1 should be considered to be
in compliance with the PEL. As reflected in paragraph (c) of the
standard for construction (which includes Table 1), and as discussed in
more detail in the summary and explanation, OSHA agrees that
construction employers who fully and properly implement the engineering
controls, work practices, and respiratory protection for a task on
Table 1 do not have to demonstrate compliance with the PEL for that
task, because these controls provide a level of protection equivalent
to that provided by the alternative approach that includes the 50
[micro]g/m\3\ PEL.
OSHA also received many comments about the challenges of conducting
exposure assessments in the construction industry. OSHA expects that
because of these challenges most construction employers will follow
Table 1. Therefore, OSHA made major structural changes to the standard
for construction to emphasize Table 1 in paragraph (c) for employers
who choose to follow that approach. Paragraph (d) of the standard for
construction provides alternative exposure control methods for
construction employers who choose not to follow Table 1 or who perform
tasks that are not included in Table 1 (e.g., abrasive blasting and
underground construction (tunnel boring)). Paragraph (d) of the
standard for construction contains requirements, including the PEL,
exposure assessments, and methods of compliance, that follow OSHA's
traditional approach.
Construction employers who choose to follow Table 1 of paragraph
(c) are exempt from following paragraph (d) but must comply with
provisions in all other paragraphs of the standard for construction. On
the other hand, construction employers who follow the alternate
exposure control methods in paragraph (d) are exempt from following the
provisions in paragraph (c) but must comply with the provisions in all
other paragraphs of the standard for construction.
Although the structure of the standard for general industry and
maritime differs from the structure of the standard for construction,
many of the requirements are the same or similar in both standards.
Therefore the summary and explanation is organized according to the
main requirements of the standards. It includes paragraph references to
the standard for general industry and maritime, followed by paragraph
references for the standard for construction. The summary and
explanation uses the term "rule" when referring to both standards.
Generally, when the summary and explanation refers to the term
"rule," it is referring to the final rule. To avoid confusion, the
term "final rule" is sometimes used when making a comparison to or
clarifying a change from the proposed rule.
Scope and Application
Separate standards for general industry/maritime and construction.
OSHA proposed two separate standards addressing occupational exposure
to respirable crystalline silica: one for exposures in general industry
and maritime, and another for exposures in the construction industry.
The proposed standards were intended to provide equivalent protection
for workers while accounting for the different work activities,
anticipated exposures, and other conditions in these sectors.
Commenters representing construction employers, labor unions, and
governmental entities noted the intrinsic differences between
construction and other industries and were generally supportive of
OSHA's decision to propose one standard for general industry and
maritime and another for construction (e.g., Document ID 1955, p. 2;
2116, p. 40; 2166, p. 3; 2181, p. 4; 2262, p. 14; 2318, p. 13; 2371, p.
5; 3403, p. 3). However, some stakeholders expressed concerns about
differentiation among industries.
The Association of Occupational and Environmental Clinics opposed
applying occupational health protection measures differently (Document
ID 3399, p. 4). Edison Electric Institute (EEI) argued that differences
in the standards may create confusion, administrative burden, and
ambiguity, and could ultimately frustrate good-faith compliance
efforts. EEI suggested that the easiest solution would be for OSHA to
have "a single regulation applicable to the electric utility industry,
rather than separate General Industry and Construction requirements"
(Document ID 2357, p. 17).
Commenters representing utility providers, surface mineral mining,
rock crushing, railroad operations, and truck distribution expressed
concerns about separate standards creating uncertainty about which
requirements would apply to various activities (Document ID 2101, p. 3;
2185, pp. 4-5; 2318, p. 13; 2357, p. 4; 2366, p. 3; 3492, p. 2).
Southern Company cited the installation of new power delivery lines
versus the repair or maintenance of existing power delivery lines as an
example, indicating that once a concrete pole is in the ground the
process of mounting hardware is exactly the same, but the applicable
standard may be different (Document ID 2185, p. 4).
The International Brotherhood of Teamsters (IBT) also expressed
concerns about work activities where it may not be clear whether the
general industry or construction standard applies. IBT noted that
ready-mix concrete truck drivers frequently travel to more than one
work location and may work at many different construction sites on any
given day. These workers are typically covered by the general industry
standard; however, they may work at construction sites and perform
certain tasks that could be considered construction work (Document ID
2318, p. 13).
Several commenters requested that OSHA develop a table listing
specified exposure control methods for general industry, comparable to
proposed Table 1 for construction, or that OSHA add general industry
tasks to Table 1 (Document ID 2116, Attachment 1, p. 3; 2212, p. 2;
2244, p. 4; 2339, p. 8; 2357, p. 1). The American Society of Safety
Engineers requested that Table 1 "be considered for the general
industry/maritime standard for commonly performed tasks involving high
levels of silica exposure" (Document ID 2339, p. 8).
After considering the concerns raised by commenters, OSHA is
issuing one standard that addresses occupational exposure to respirable
crystalline silica in general industry and maritime work and another
for construction work. As reflected primarily in paragraph (c) and
Table 1 of the standard for construction, the Agency finds that certain
conditions inherent to the construction industry, such as the transient
nature of the work, warrant alternatives to protect employees that are
somewhat different than those that apply to general industry and
maritime work. OSHA has long recognized a distinction between the
construction and general industry sectors, and has issued standards
specifically applicable to construction work under 29 CFR part 1926.
The Agency has provided a definition of the term "construction work"
at 29 CFR 1910.12(b), has explained the terms used in that definition
at 29 CFR 1926.13, and has issued numerous interpretations over the
years explaining the classification of activities as either general
industry or construction work.
In issuing separate standards for general industry/maritime and
construction, OSHA's intent is to ensure that employees exposed to
respirable crystalline silica in construction are, to the extent
feasible, provided equivalent protection to that afforded employees in
general industry and maritime. Specifically, OSHA intends that Table 1
in paragraph (c) of the construction standard, while providing
employers with an alternative, flexible approach to addressing exposure
to respirable crystalline silica in construction, will provide the same
level of protection against exposures to silica for construction
employees as is provided to general industry and maritime employees;
the same is true for construction employees whose employers are
following the traditional exposure assessment and hierarchy of controls
approach under paragraph (d) of the construction standard.
OSHA recognizes that in some circumstances, general industry
activities and conditions in workplaces where general industry tasks
are performed may be indistinguishable from those found in construction
work. In some cases, employers whose primary business is classified as
general industry may have some employees who perform construction work,
and employers whose primary business is classified as construction may
have some employees who perform general industry work. Given the wide
variety of tasks performed in the workplace, it is inevitable that
questions will arise regarding the classification of certain
activities, and these questions have been and will continue to be
addressed in letters of interpretation and other guidance issued by
OSHA. However, the distinction between sectors is generally well
understood by both OSHA enforcement personnel and the regulated
community, and OSHA concludes that any attempt to create exceptions or
to provide different criteria in this final rule would not improve upon
the current criteria but would, rather, cause confusion.
In certain circumstances, tasks performed in a general industry
setting may be indistinguishable from the tasks listed on Table 1, and,
under these circumstances, OSHA intends to treat full compliance with
the construction standard as full compliance with the general industry/
maritime standard. Accordingly, OSHA has revised the scope provision
(i.e., paragraph (a)) in the general industry and maritime standard by
adding paragraph (a)(3) to permit employers to follow the construction
standard rather than the general industry and maritime standard when
the general industry/maritime task performed is indistinguishable from
a construction task listed on Table 1 in paragraph (c) of the
construction standard, and the task will not be performed regularly in
the same environment and conditions.
These indistinguishable tasks should not be merely parallel or
complementary to or occurring at the same time and place as the
construction tasks listed on Table 1, but rather should be of the same
nature and type as those construction tasks. OSHA anticipates that the
option in paragraph (a)(3) will apply primarily to maintenance and
repair tasks performed in general industry or maritime settings. For
example, an employee using a portable masonry saw to cut brick to patch
a section of an existing brick wall, which is typically maintenance,
would require tools and controls that are the same as those of an
employee cutting brick while building a new brick wall, which is
construction work. In performing this task, the employer could follow
the construction standard, including paragraph (c)(1)(ii) of Table 1,
rather than the general industry and maritime standard. Similarly, the
installation of new power delivery lines is considered a construction
activity, while the repair or maintenance of existing power delivery
lines is considered a general industry task, even though a handheld
drill may be used to drill a hole in concrete during both activities.
In this situation, if the employer complies with the entry on Table 1
for handheld and stand-mounted drills (paragraph (c)(1)(vii) of the
construction standard), in addition to all other applicable provisions
of the construction standard (e.g., paragraph (g), Written exposure
control plan), the employer would not be obligated under the general
industry and maritime standard to perform an exposure assessment for
the employee(s) engaged in the drilling task, or be subject to citation
for failure to meet the permissible exposure limit (PEL); instead, the
employer would have the same accommodation that Table 1 in paragraph
(c) of the construction standard affords a construction employer doing
that task and following paragraph (c). However, in the event that the
employer fails to fully comply with the construction standard by, for
example, failing to fully and properly implement the controls on Table
1 or to fully establish and implement a written exposure control plan
(e.g., by not designating a competent person to implement the plan),
the employer would be subject to the general industry and maritime
standard and could be cited for not having performed an exposure
assessment or not having achieved the PEL with respect to the
employee(s) engaged in that task.
Paragraph (a)(3)(ii) of the general industry and maritime standard
provides that, in order for the employer to be able to avail itself of
the option to follow the construction standard, the task must not be
performed regularly in the same environment and conditions. For
example, an employer that performs sanding or cutting of concrete
blocks in a concrete block manufacturing plant may not follow the
construction standard, because the task is performed regularly in the
same environment and conditions. Likewise, an employer whose business
includes chipping out concrete from inside the drums of ready-mixed
concrete trucks using pneumatic chipping tools may not follow the
construction standard, because that task will be regularly performed in
a relatively stable and predictable environment that would not require
the accommodation of Table 1, which is intended in part to accommodate
situations where the tasks will be performed in different environments
and conditions.
Regarding comments that exposure controls should be specified in
the general industry and maritime standard in a manner similar to that
of Table 1 for construction tasks, OSHA concludes that, for most
general industry operations, it is not possible to develop a
specification that would broadly apply to facilities that vary widely
in size, process design, and complexity while being specific enough to
provide reasonably objective criteria against which to judge compliance
with the standard. Unlike for construction tasks, the rulemaking record
does not provide sufficient information for OSHA to account for the
wide variety of potential tasks across the range of manufacturing and
other general industry work. In manufacturing industries such as
foundries and pottery production, local exhaust specifications must be
custom designed for each establishment considering its manufacturing
processes, equipment, and layout. Based on its over forty years of
experience in enforcing occupational safety and health standards, OSHA
concludes that in general industry and maritime, employee protection
is best provided through a performance-oriented standard that permits
employers to implement engineering controls and work practices that
best fit their situation. In contrast, the task-based operations
performed in construction are uniquely suited to a specification
approach since the same equipment and dust controls are generally
used regardless of the nature of the construction project, making
specification of an effective dust control approach possible.
Agriculture. The proposed rule did not cover agricultural employers
due to limited data on exposures and control measures in the
agriculture sector. OSHA's authority is also restricted in this area;
since 1976, an annual rider in the Agency's Congressional
appropriations bill has limited OSHA's use of funds with respect to
farming operations that employ fewer than ten employees (Consolidated
Appropriations Act, 1976, 94, 90 Stat. 1420, 1421 (1976) (and
subsequent appropriations acts)). The Agency requested information on
agricultural operations that involve respirable crystalline silica
exposures in the Notice of Proposed Rulemaking (NPRM), as well as
information related to the development of respirable crystalline
silica-related adverse health effects and diseases among employees in
the agricultural sector (78 FR 56274, 56288 (9/12/13). OSHA did not
receive information that would support coverage of agricultural
operations. Therefore, agriculture employers and operations are not
covered by the rule, as specified in paragraph (a)(1)(ii) of the
general industry and maritime standard.
Mine Safety and Health Administration (MSHA) jurisdictional
concerns. The Fertilizer Institute (TFI) and Fann Contracting, Inc.
requested that OSHA clarify the jurisdictional limits of the silica
rule in light of OSHA's memorandum of understanding (MOU) with MSHA
(Document ID 2101, p. 3; 2116, p. 31) (citing Interagency Agreement
Between the Mine Safety and Health Administration U.S. Department of
Labor and the Occupational Safety and Health Administration U.S.
Department of Labor). The MOU, which has been in effect since March 29,
1979 (Document ID 2101, p. 3), delineates certain areas of respective
authority, sets forth factors regarding determinations relating to
convenience of administration, provides a procedure for determining
general jurisdictional questions, and provides for coordination between
MSHA and OSHA in all areas of mutual interest. The respirable
crystalline silica rule in no way modifies the existing jurisdictional
boundaries set forth in the Interagency Agreement, and any issues
related to the rule that may arise between MSHA and OSHA are governed
by this agreement. Therefore, the final rule does not necessitate a
clarification of the jurisdictional limits.
Federal Railroad Administration (FRA) jurisdictional concerns. The
Association of American Railroads (AAR) and the American Short Line and
Regional Railroad Association (ASLRRA) raised jurisdictional issues
about railroad operations (Document ID 2366, pp. 3-4). The stated
concern is that railroad operations are also regulated by FRA. AAR and
ASLRRA questioned OSHA's jurisdiction over railroad activities that
OSHA considered and costed in its preliminary economic analysis,
notably those of "ballast dumper" and "machine operator." AAR and
ASLRRA disagreed with OSHA's inclusion of these job categories as being
"non-operational," which allowed them to be included within the scope
of the OSHA silica rule. AAR and ASLRRA asserted that the FRA has
developed a special expertise, making the FRA uniquely qualified to
play the primary role in the federal government's efforts to assure
safe employment and places of employment for railroad employees engaged
in activities related to railroad operations (Document ID 2366, pp. 3-
4).
Section 4(b)(1) of the OSH Act limits OSHA's authority; the Act
does not apply to working conditions of employees with respect to which
other Federal agencies exercise statutory authority to prescribe or
enforce standards or regulations affecting occupational safety or
health. Many of the regulatory boundaries between FRA and OSHA are
documented in an FRA policy statement that outlines the respective
areas of jurisdiction between FRA and OSHA with regard to the railroad
industry, but the FRA has also defined some boundaries through
rulemaking (Document ID 0692 (43 FR 10583-10590 (3/14/78))). In 2003,
FRA amended the Railroad Workplace Safety regulations, 49 CFR part 214,
to require that new and employer-designated existing on-track roadway
maintenance machines be equipped with, among other things, positive
pressurized ventilation systems, and be capable of protecting employees
in the cabs of the machines from exposure to air contaminants,
including silica, in accordance with OSHA's air contaminants standard,
29 CFR 1910.1000 (49 CFR 214.505). In that rulemaking, the FRA
articulated the overlap of its authority with OSHA's concerning
protection from air contaminants: "when working inside the cab,
workers receive protection from FRA; when working outside the cab,
workers receive protection from OSHA" (68 FR 44388, 44393-44394 (7/28/
03)). Consequently, this OSHA rule applies only to those railroad
activities outside the cab (e.g., ballast dumping outside cabs) over
which the FRA has not exercised jurisdiction, and only those activities
are included in the final economic analysis. Additional discussion of
this jurisdictional issue is included in the section on the
technological feasibility of railroads (see Chapter IV of the Final
Economic Analysis and Final Regulatory Flexibility Analysis (FEA)).
Forms of silica covered. OSHA received comments about which forms,
or polymorphs, of silica (e.g., quartz, cristobalite, tridymite) to
include within the scope of the rule. The Industrial Minerals
Association--North America and Ameren Corporation supported including
all forms within the scope of the rule (Document ID 1760, p. 2; 2200,
p. 2; 2315, p. 2). Other commenters made recommendations regarding
specific forms of silica. For example, the National Industrial Sand
Association (NISA) suggested including tridymite; however, the National
Institute for Occupational Safety and Health (NIOSH) and the North
American Insulation Manufacturers Association (NAIMA) did not support
inclusion of tridymite due largely to its rarity in the workplace
(Document ID 2195, p. 30; 2177, Attachment 2, p. 10; 4213, p. 4).
Similarly, Southern Company recommended that neither tridymite nor
cristobalite be included within the scope of the rule, due to their
rarity in the workplace (Document ID 2185, p. 2, 6). The American
Composites Manufacturers Association and Southern Company suggested
that OSHA focus exclusively on quartz (Document ID 1732, p. 6; 2185, p.
6). NAIMA suggested OSHA focus on both quartz and cristobalite
(Document 4213, p. 4).
As discussed in Section V of this preamble, Health Effects, OSHA
has concluded, based on the available scientific evidence, that quartz,
cristobalite, and tridymite have similar toxicity and carcinogenic
potency. Including all three forms of crystalline silica in the scope
of the rule is therefore protective of the health of employees.
Coverage of quartz, cristobalite, and tridymite in the scope of the
rule maintains the coverage from OSHA's previous PELs for respirable
crystalline silica; to eliminate one or more forms from the scope of
the rule would lessen protections, contrary to what the OSH Act
contemplates (see 29 U.S.C. 655(b)(8)). Therefore, the respirable
crystalline silica rule applies to occupational exposure to respirable
crystalline silica, as defined in paragraph (b) of each standard to
include quartz, cristobalite, and tridymite.
Some commenters contended that OSHA should differentiate between
crystalline silica and amorphous silica in the scope of the rule. The
Society for Protective Coatings stated that this differentiation would
avoid confusion and unnecessary burden, especially for small businesses
(Document ID 2120, p. 1; 3544, p. 16). NAIMA stated that NIOSH, IARC
(the International Agency for Research on Cancer), EPA (the
Environmental Protection Agency), and the California Office of
Environmental Health Hazard Assessment all recognize the distinction in
potential hazards to workers between amorphous and crystalline silica
(Document ID 3544, p. 16). However, OSHA never intended to, and did
not, include amorphous silica in the proposed rule. Nor do the final
standards apply to amorphous silica. In fact, each standard bears the
title, "Respirable crystalline silica"; only the respirable fraction
of crystalline silica, where it exists as quartz, cristobalite, and/or
tridymite, is covered.
Requests for exemptions. Commenters requested exemptions from the
rule for specific operations or industries, such as auto body
operations, cement distribution terminals, floor covering dealers,
rural electric distribution cooperatives, and painting operations,
arguing that these operations involve low levels of exposure to
respirable crystalline silica (e.g., Document ID 2300, p. 4; 2358, p.
15; 2359, pp. 3-7; 2365, p. 2; 3751, p. 2; 2239, pp. 4-5). For example,
the National Automobile Dealers Association (NADA) said that the
likelihood of worker exposure to significant respirable crystalline
silica in dealership auto body operations is de minimis, largely due to
product substitution, state-of-the-art work practices, and the use of
respiratory protection. NADA requested that OSHA confirm this
conclusion through a clear statement in the preamble of its final rule
(Document ID 2358, p. 3). Similarly, the World Floor Covering
Association requested that OSHA revise the rule to exempt retail
flooring dealers and installers from all requirements in the standard
based on the intermittent and de minimis exposure of its employees to
crystalline silica (Document ID 2359, p. 11). The Portland Cement
Association also requested an exemption from the silica rule, arguing
that its contemporary inhalation survey and historical data show that
there is no probability that respirable crystalline silica exposures
can be generated above the proposed action level among employees at
cement terminals.
OSHA addresses the concerns of commenters regarding situations
where they believe exposures are minimal and represent very little
threat to the health of workers by including in the standards' scope
and application sections an exception based on the level of exposure to
respirable crystalline silica. Therefore, paragraph (a)(2) of the
standard for general industry and maritime provides an exception for
circumstances where the employer has objective data demonstrating that
employee exposure to respirable crystalline silica will remain below 25
micrograms per cubic meter of air (25 [mu]g/m\3\) as an 8-hour time-
weighted average (TWA) under any foreseeable conditions.
OSHA concludes this approach is sensible policy because providing
an exception for situations where airborne exposures are less likely to
present significant risk allows employers to focus resources on the
exposures of greatest occupational health concern. The Agency has
included a definition for "objective data" in the rule (discussed
with regard to Definitions) to clarify what information and data can be
used to satisfy the obligation to demonstrate that respirable
crystalline silica exposures will be below 25 [mu]g/m\3\ as an 8-hour
TWA under any foreseeable conditions.
When using the phrase "any foreseeable conditions" OSHA is
referring to situations that can reasonably be anticipated. The Agency
considers failure of engineering controls to be a situation that is
generally foreseeable. Although engineering controls are usually a
reliable means for controlling employee exposures, equipment does
occasionally fail. Moreover, OSHA intends the requirements for training
on control measures, housekeeping, and other ancillary provisions of
the rule to apply where engineering controls are used to limit
exposures. Without effective training on use of engineering controls,
for example, it is unreasonable to expect that such controls will be
used properly and consistently. Thus, the exception does not apply
where exposures below 25 [mu]g/m\3\ as an 8-hour TWA are expected or
achieved, but only because engineering or other controls are being used
to limit exposures; in that circumstance, but for the controls,
exposures above 25 [mu]g/m\3\ as an 8-hour TWA would be foreseeable,
and are foreseeable in the event of control failure or misuse.
OSHA considers the exclusion from the application of the rule for
exposures below the 25 [mu]g/m\3\ action level to be a reasonable point
of demarcation. For workplaces or tasks for which exposures are
consistently below that threshold, it should be possible for employers
to develop or obtain objective data demonstrating that employee
exposure will remain below that level under any foreseeable conditions.
Other standards have included similar exceptions (e.g., acrylonitrile,
29 CFR 1019.1045; ethylene oxide, 29 CFR 1910.1047; 1,3-butadiene, 29
CFR 1910.1051; chromium (VI), 29 CFR 1910.1026). In order for an
employer to take advantage of this exclusion, the employer must have
objective data demonstrating that employee exposure to respirable
crystalline silica will remain below 25 [mu]g/m\3\ as an 8-hour TWA)
under any foreseeable conditions, and must provide this data to the
Assistant Secretary upon request.
NADA's submission provides an example of data that can be used to
meet the requirements of the standard (Document ID 4197; 4198). NADA
conducted air monitoring for employees performing a variety of tasks in
automobile body shops. NADA selected body shops from a random sample of
members, and worked to ensure that those selected were not the most
technologically advanced or cleanest in order to ensure that the
results of the study were representative of typical operations. The
sampling was conducted in accordance with procedures described in
OSHA's Technical Manual, and techniques for controlling dust generated
during sanding operations were recorded and monitored. NADA retained a
consultant to review testing methodology and final results and worked
with Maine's OSHA Consultation Program to gather samples. In the body
shops sampled, all but one of the samples taken for respirable
crystalline silica indicated that exposures were below the limit of
detection. For the one sample where the level of exposure was above the
limit of detection, the result was below 25 [mu]g/m\3\ as an 8-hour
TWA. A body shop performing tasks in a manner consistent with that
described in the NADA submission would be able to rely on these
objective data to demonstrate that exposures do not exceed 25 [mu]g/m\3\
as an 8-hour TWA under any foreseeable conditions.
The construction standard, paragraph (a), also provides an
exception where employee exposure will remain below 25 [mu]g/m\3\ as an
8-hour TWA under any foreseeable conditions, but it does not require
the employer to have objective data to support the exception. The data
presented in Chapter IV of the FEA indicate that construction tasks can
and often do involve exposures that exceed 25 [mu]g/m\3\ as an 8-hour
TWA. However, some construction tasks may involve only minimal exposure
to respirable crystalline silica. Some commenters indicated that they
believed these tasks were covered under the scope of the proposed
construction standard. For example, the Construction Industry Safety
Coalition (CISC) and the National Association of Home Builders
indicated that they believed that mixing mortar, pouring concrete
footers, slab foundation, and foundation walls, and the removal of
concrete formwork would be covered by the standard (Document ID 2319,
pp. 19-21; 2296, pp. 8-9). OSHA finds that these tasks, when performed
in isolation from activities that do generate significant exposures to
respirable crystalline silica (e.g., tasks listed on Table 1, abrasive
blasting), do not create respirable crystalline silica exposures that
exceed 25 [mu]g/m\3\ as an 8-hour TWA. OSHA's analysis of the
rulemaking record also indicates that a substantial number of employees
in the construction sector perform tasks involving occasional, brief
exposures to respirable crystalline silica that are incidental to their
primary work. These employees include carpenters, plumbers, and
electricians who occasionally drill holes in concrete or masonry or
perform other tasks that involve exposure to respirable crystalline
silica. CISC estimated that 1.5 million employees in the construction
industry perform such tasks (Document ID 2319, pp. 72-73). Where
employees perform tasks that involve exposure to respirable crystalline
silica for a very short period of time, OSHA finds that exposures for
many tasks will be below 25 [mu]g/m\3\ as an 8-hour TWA. Short-term
respirable crystalline silica exposures must be very high in order for
those exposures to exceed 25 [mu]g/m\3\ as an 8-hour TWA; for example,
if an employee is exposed for only 15 minutes, his or her exposure
would have to exceed 800 [micro]g/m\3\ for that 15 minute period before
the 8-hour TWA exposure would exceed 25 [mu]g/m\3\.
When performed without adequate controls, some tasks can generate
such high exposures. However, for some construction tasks that may be
performed occasionally, for brief periods of time, exposures would not
generally be expected to exceed 25 [mu]g/m\3\ as an 8-hour TWA. For
example, for hole drillers using hand-held drills, the highest result
identified in OSHA's exposure profile was for a worker performing dry
drilling on a wall on the lower level of a concrete parking garage
where air circulation was poor (see Chapter IV of the FEA). This result
showed an exposure of 300 [micro]g/m\3\ during the sampling period
(Document ID 1423, p. 833). If the duration of exposure was 15 minutes,
the 8-hour TWA exposure would be 19 [mu]g/m\3\, and therefore under the
25 [mu]g/m\3\ threshold (assuming no exposure for the remainder of the
shift).
Rather than require construction employers to develop objective
data to support an exception from the construction standard for
employees who are exposed to minimal levels of respirable crystalline
silica, or who are occasionally exposed to respirable crystalline
silica for brief periods, OSHA is structuring the scope paragraph
(i.e., paragraph (a)) for the construction standard so that the
standard applies to all occupational exposures to respirable
crystalline silica, except where employee exposure will remain below 25
[mu]g/m\3\ as an 8-hour TWA under any foreseeable conditions. This
approach relieves construction employers of the burden of developing
objective data for such situations.
In the NPRM, OSHA asked stakeholders whether the Agency should
limit the coverage of the rule to materials that contain a threshold
concentration (e.g., 1 percent, 0.1 percent) of crystalline silica (78
FR at 56288). Stakeholders representing industries including cement and
concrete, composites manufacturing, fertilizers, and sand and gravel
suggested a threshold, commonly presenting concerns regarding
requirements for labels and safety data sheets (SDSs) (e.g., Document
ID 1785, p. 4; 2116, Attachment 1, p. 45; 2179, pp. 3-4; 2101, pp. 8-9;
2284, p. 10; 2296, p. 44; 2312, p. 3; 2317, p. 3; 2319, p. 120; 2327,
Attachment 1, p. 14; 4208, pp. 19-20). For example, TFI supported a
percentage-based threshold for crystalline silica containing materials,
indicating that such an approach would be consistent with OSHA's past
standard-setting experience for asbestos-containing materials. TFI
stated that OSHA should not set a threshold at lower than 1 percent,
and recommended that OSHA consider a 5 percent threshold, noting
challenges in measuring crystalline silica content in bulk materials at
concentrations below 1 percent (Document ID 2101, pp. 5-9).
OSHA has not included a threshold concentration exception in these
standards. The Agency has concluded that it would not be appropriate to
establish a threshold crystalline silica concentration because the
evidence in the rulemaking record is not sufficient to lead OSHA to
determine that the suggested concentration thresholds would be
protective of employee health. The Agency's exposure assessment
findings show that exposures to respirable crystalline silica can
exceed the action level of 25 mg/m\3\ or PEL of 50 mg/m\3\ even at
threshold concentrations less than 1 or 0.1 percent, as demonstrated by
the abrasive blasting activities investigated in a NIOSH survey report
using Staurite XL in containment (Document ID 0212, p. 12). Issues with
regard to requirements for labels and SDSs are addressed in the summary
and explanation of requirements for Communication of Respirable
Crystalline Silica Hazards to Employees in this preamble.
The Brick Industry Association (BIA) argued that its members should
be exempt from compliance with the respirable crystalline silica rule,
indicating that the low toxicity of crystalline silica in the brick and
structural clay industry does not cause a material risk of health
impairment. BIA noted that OSHA has established specific requirements
for certain industries in the past, such as the pulp, paper and
paperboard mill industry in 29 CFR 1910.216, and the textile industry
in 29 CFR 1910.262. BIA requested that OSHA take a similar approach for
the brick industry because, BIA argued, silicosis is essentially non-
existent in the brick industry's workers (Document ID 2300, pp. 2-4).
OSHA also received comments and testimony from stakeholders in the
brick, tile, and fly ash industries who argued that in their
industries, crystalline silica was most commonly shrouded or occluded
within matrices of aluminosilicates, and therefore the silica was less
bioavailable and exhibited reduced toxicity (e.g., Document ID 2085, p.
2; 2123, p. 1; 2267, p. 8; 2343, Attachment 1, p. 30; 3587, Tr. 3628;
3587, Tr. 3704).
As discussed in Section V of this preamble, Health Effects, OSHA
has reviewed the evidence concerning potential effects on silica-
related toxicity of a variety of physical factors, including the age
of fractured surfaces of the crystal particle and clay occlusion of
the particle. OSHA recognizes that the risk to employees exposed to
a given level of respirable crystalline silica may not be equivalent
in different work environments due to differences in physical factors
that affect the potency of crystalline silica. OSHA also recognizes
that workers in these industries (e.g., brick manufacturing) may
experience lower rates of silicosis and other health effects associated
with exposure to respirable crystalline silica. However, OSHA finds
that these employees are still at significant risk of developing
adverse health effects from exposure to respirable crystalline silica.
The Agency is therefore is not excluding brick, tile, or fly ash from
the scope of the rule based on physical characteristics of
crystalline silica.
OSHA also received multiple studies, along with testimony and
comments from the Sorptive Minerals Institute (SMI) (Document ID 2377;
4230). SMI stated that sorptive clays are limited to a specific and
discreet subset of deposits in the U.S., including specifically: The
Monterey formation (California), the Porters Creek formation
(Mississippi Valley), the Twiggs and Meigs fullers earth (southeastern
U.S.), the Wyoming or Western-type sodium bentonite deposits, the
calcium bentonite deposits (north-central Florida), and the fullers
earth deposits of eastern Virginia (Document ID 4230, p. 3). As
discussed in Section V, Health Effects, SMI contended that silica in
sorptive clays exists as either amorphous silica or as geologically
ancient, occluded quartz, and that neither form poses the health risk
described in OSHA's risk assessment (Document ID 4230, p. 2). After
evaluation of the evidence SMI submitted to the record, OSHA finds that
quartz originating from bentonite and similar sorptive clays is
considerably less toxic than unoccluded quartz, and evidence does not
exist that would permit the Agency to evaluate the magnitude of the
lifetime risk resulting from exposure to silica in sorptive clay
deposits. OSHA is therefore excluding sorptive clays from the scope of
the rule, as described in paragraph (a)(1) of the general industry and
maritime standard. The PEL in 29 CFR 1910.1000 Table Z-3 (i.e., the
formula that is approximately equivalent to 100 [mu]g/m\3\) will
continue to apply to occupational exposure to respirable crystalline
silica from sorptive clays. The exemption covers exposures resulting
from the processing, packaging, and distribution of sorptive clays
originating from the geological deposits described above (and intended
for sorptive clay-specific use such as absorbents for oil, grease, and
animal waste, as a carrier for pesticides and fertilizers, or in
cosmetics, pharmaceuticals, and animal feeds).
Relationship to other OSHA standards. EEI and the American Iron and
Steel Institute (AISI) sought clarification from OSHA regarding how the
silica rule would affect the existing coke oven emissions standard or
the PEL for coal dust. EEI said that OSHA should expressly exempt coal
dust from the rule (Document ID 2357, p. 4). AISI similarly stated that
the rule potentially conflicts with the coal dust PEL and is
duplicative of existing steel industry standards. AISI stated that
OSHA's existing coke oven emissions standard protects employees working
in the regulated area around metallurgical coke ovens and metallurgical
coke oven batteries where exposures to emissions are of greatest
concern. AISI believes that workers covered by OSHA's coke oven
emissions standard are therefore already protected adequately from the
dangers of crystalline silica exposure and such operations should be
exempt from the rule (Document ID 3492, p. 2).
The respirable crystalline silica rule has no effect upon OSHA's
standard for coke oven emissions, the existing PEL for coal dust, or
any other substance-specific standard. None of these requirements
provide the full range of protections afforded by the respirable
crystalline silica rule. The PEL for coal dust is only a PEL; it does
not provide any additional protections, such as medical surveillance.
Other requirements therefore do not provide protection equivalent to
the respirable crystalline silica rule. Accordingly, the silica rule
applies to these situations to the extent there is silica exposure and
the conditions for excluding them from the rule's scope are not met.
Definitions
Paragraph (b) of the standard for general industry and maritime
(paragraph (b) of the standard for construction) provides definitions
of terms used in the standards.
"Action level" means a concentration of airborne respirable
crystalline silica of 25 micrograms of respirable crystalline silica
per meter cubed of air ([mu]g/m\3\), calculated as an 8-hour time-
weighted average. The action level triggers requirements for exposure
assessment and, in the standard for general industry and maritime,
medical surveillance. The definition is unchanged from the proposal.
Because of the variable nature of employee exposures to airborne
concentrations of respirable crystalline silica, maintaining exposures
below the action level provides reasonable assurance that employees
will not be exposed to respirable crystalline silica at levels above
the permissible exposure limit (PEL) on days when no exposure
measurements are made. Even when all measurements on a given day fall
below the PEL but are above the action level, there is a reasonable
chance that on another day, when exposures are not measured, the
employee's actual exposure may exceed the PEL (Document ID 1501). The
importance of the action level is explained in greater detail in the
summary and explanation of Exposure Assessment and summary and
explanation of Medical Surveillance.
The action level in this rule is set at one-half of the PEL. This
is the same ratio of action level to PEL that has been used and been
effective in other standards, including those for inorganic arsenic (29
CFR 1910.1018), ethylene oxide (29 CFR 1910.1047), benzene (29 CFR
1910.1028), methylene chloride (29 CFR 1910.1052), and chromium (VI)
(29 CFR 1910.1026).
Following the publication of the proposed rule, OSHA received a
number of comments pertaining to the definition of the action level.
Some commenters, such as National Council for Occupational Safety and
Health (NCOSH), American Federation of Labor and Congress of Industrial
Organizations (AFL-CIO), International Brotherhood of Teamsters, United
Steelworkers (USW), Center for Effective Government (CEG), American
Public Health Association (APHA), American Thoracic Society (ATS), and
Cara Evens, a private citizen, supported OSHA's proposal to include an
action level of 25 [mu]g/m\3\ (e.g., Document ID 1801, p. 2; 2173, pp.
2-3; 2175, p. 5; 2178, Attachment 1, p. 2; 2318, p. 10; 2336, p. 5;
2341, pp. 2-3; 4204, pp. 42-45, 51-52). For example, USW supported the
inclusion of an action level that is half the PEL (25 [micro]g/m\3\)
because:
This action level will further reduce exposure to respirable
crystalline silica by workers and will incentivize employers to
implement best-practice controls keeping exposures at a minimum as
well as reducing costs of monitoring and assessments. The USW
believes measuring airborne concentrations of silica at 25ug/m\3\
will prove feasible given current sampling techniques (Document ID
2336, p. 5).
AFL-CIO noted that action levels have long been incorporated into
OSHA standards in recognition of the variability of workplace exposures
and argued that the inclusion of an action level is particularly
important in this rulemaking because exposures at the PEL pose a
significant risk to employees (Document ID 2256, Attachment 2, p. 9).
NCOSH and CEG echoed AFL-CIO's concerns about significant risk remaining
at the PEL, and NCOSH, further noted that significant risk remains at
the action level (Document ID 2173, p. 2; 2341, p. 2).
As discussed in more detail in the summary and explanation of
Medical Surveillance, some stakeholders, such as APHA, supported an
action level trigger for medical surveillance in the standard for
general industry because of significant risk of disease remaining at
the action level and even below (Document ID 2178, Attachment 1, p. 2).
The National Institute for Occupational Safety and Health (NIOSH)
supported an action level that is lower than the PEL because it is
consistent with longstanding industrial hygiene practice, and an action
level is included in other OSHA standards. NIOSH did not recommend a
value for the action level but cited a 1975 study by NIOSH (Leidel et
al. 1975, Document ID 1501) as demonstrating that an action level
provides a high level of confidence that most daily exposures will be
below the PEL (Document ID 2177, Attachment B, p. 23).
Other commenters supported having an action level, but advocated a
higher level (e.g., Document ID 1963, pp. 1-2; 2196, Attachment 1, pp.
1-2; 2200, pp. 1-2; 2213, p. 3; 2232, p. 1; 2233, p. 1; 2301,
Attachment 1, p. 78; 2311, p. 3). For instance, the National Industrial
Sand Association (NISA) recommended an action level of 50 [mu]g/m\3\,
which is one half the value of the PEL they supported (100 [mu]g/m\3\).
NISA recommended a higher PEL because it disagreed with OSHA that
significant risk existed at the proposed PEL of 50 [mu]g/m\3\. NISA
also argued that a PEL of 50 [mu]g/m\3\ would not be technologically or
economically feasible. However, NISA's reasons for recommending an
action level set at half of its recommended PEL mirrored many of the
reasons offered by USW and AFL-CIO, including maintaining consistency
with other OSHA standards, accounting for exposure variability, and
providing employers with incentives to keep exposures low. In addition,
NISA commented that keeping exposures well below the PEL would provide
a margin of safety to protect against uncertainties in the toxicology
and epidemiology data supporting a PEL (Document ID 2195, pp. 30-35).
NISA also recommended that medical surveillance be triggered at the
action level (although, as noted above, NISA recommended an action
level of 50 [mu]g/m\3\); that recommendation is discussed in the
summary and explanation of Medical Surveillance.
Southern Company asserted that OSHA set the proposed action level
too low, because it believed it is difficult to measure based on
current laboratory detection limits (Document ID 2185, pp. 5-6). It
recommended that OSHA consider setting the action level at an
achievable analysis level (though a suggested level for OSHA to
consider was not provided) or conduct further cost analyses of
additional sampling and ancillary provisions this may trigger. As
stated further below, OSHA's conclusion that silica exposures can be
measured with reasonable accuracy at the action level is discussed in
the Sampling and Analysis discussion of technological feasibility in
Chapter IV of the Final Economic Analysis and Final Regulatory
Flexibility Analysis (FEA).
Other commenters supported an action level but argued that the
proposed action level was set too high. For example, the United
Automobile, Aerospace and Agricultural Implement Workers of America
(UAW) argued that the action level would need to be set at 12.5 [mu]g/
m\3\, one-fourth of a 50 [mu]g/m\3\ PEL, in order to ensure that fewer
than 5 percent of exposures would exceed a PEL of 50 [mu]g/m\3\
(Document ID 2282, Attachment 3, p. 14). In support of its recommended
action level, UAW cited a study by Rappaport et al. (1988), which
reported that no more than 12 percent of log-normally distributed
exposures are expected to exceed the PEL with an action level set at
one half the PEL (Document ID 2282, Attachment 2, pp. 310, 314).
Similarly, the BlueGreen Alliance (BGA) supported a lower action level,
indicating that the proposed action level was not protective enough.
BGA supported an action level of no higher than 25 percent of the PEL
"...in order to provide reasonable likelihood that 95% of exposures
are below the PEL" (Document ID 2176, p. 2).
Finally, some commenters opposed having any action level (Document
ID 2085, p. 3; 2296, p. 40; 2305, pp. 4, 10; 2312, p. 2; 2317, p. 2;
2327, Attachment 1, pp. 13, 15-17; 2305, pp. 4, 10; 2296, p. 40; 3577,
Tr. 707-708). Mercatus Center of George Mason University (Mercatus
Center) asserted that OSHA did not provide adequate justification for
the proposed action level, arguing that because OSHA found a PEL of 25
[mu]g/m\3\ to be infeasible, the Agency has not shown that employers
would have sufficient incentives to limit exposures to the action level
(Document ID 1819, p. 2). The Fertilizer Institute indicated that the
action level will create a de facto 25 [mu]g/m\3\ standard because the
initial and periodic monitoring requirements will be a time-consuming,
expensive endeavor (Document ID 2101, pp. 7-8). The National Concrete
Masonry Association and Blue Stone Block Supermarket argued that the
best approach would be to remove the action level and only "require
action when the PEL is exceeded" (Document ID 2279, p. 9; 2384, p. 9).
They believed requiring action only when their recommended PEL of 100
[micro]g/m\3\ is exceeded would be effective in reducing silica-related
illnesses and more cost-effective for industries.
OSHA considered these comments and has decided to retain an action
level of 25 [micro]g/m\3\. OSHA agrees with CEG and AFL-CIO that that
the inclusion of an action level of 25 [micro]g/m\3\ is particularly
important in this rulemaking because employees exposed at the action
level and revised PEL remain at significant risk of developing
respirable crystalline silica-related diseases (see Section VI, Final
Quantitative Risk Assessment and Significance of Risk). In addition, as
explained in Chapter IV of the FEA, OSHA has found that the revised PEL
is technologically and economically feasible. OSHA disagrees with
Mercatus Center that an action level of 25 [micro]g/m\3\ is not
appropriate because that level is not feasible as a PEL, and the Agency
does not agree with the Fertilizer Institute that a 25 [mu]g/m\3\
action level creates a de facto standard. The action level only
triggers certain requirements (i.e., a requirement for exposure
assessment in general industry/maritime and construction, and medical
surveillance in general industry/maritime only); employers that exceed
it but remain at the PEL or below will not be in violation of the rule,
so long as they comply with the requirements associated with the action
level. The requirements associated with exposures at or above the
action level create an incentive--but not a requirement--for employers
to reduce exposures below the action level where it is reasonably
possible to do so. Although OSHA could not find that engineering
controls and work practices are sufficient to reduce and maintain
respirable crystalline silica exposures to a level of 25 [mu]g/m\3\ or
below in most operations most of the time in affected industries, it is
likely possible for some employers to reduce exposures to below the
action level in some circumstances, without the use of respirators. The
Agency also concludes that it is feasible to measure respirable
crystalline silica levels at an action level of 25 [mu]g/m\3\ with
reasonable accuracy (see Chapter IV of the FEA). Because employers are
not required to reduce exposures below 25 [mu]g/m\3\, feasibility
concerns are not relevant. Consequently, OSHA does not agree with
NISA and Southern Company that feasibility concerns warrant revising
the proposed action level upward.
OSHA agrees, however, that maintaining exposures below an action
level that is half the PEL provides reasonable assurance that employees
will not be exposed to respirable crystalline silica at levels above
the PEL on days when no exposure measurements are made. OSHA's early
standards relied, in part, on a statistical basis for using an action
level of one-half the PEL (e.g., acrylonitrile, 29 CFR 1910.1045;
ethylene oxide, 29 CFR 1910.1047). OSHA previously determined (based in
part on research conducted by Leidel et al., 1975) that where exposure
measurements are above one-half the PEL, the employer cannot be
reasonably confident that the employee is not exposed above the PEL on
days when no measurements are taken (Document ID 1501, pp. 5-6, 29-30,
38). Similarly, Rappaport et al. (1988) used monitoring data and
applied a statistical method to estimate that no more than 12 percent
of lognormally-distributed exposures would be expected to exceed the
PEL if mean exposures remain below an action level set at one-half the
PEL (Document ID 2282, Attachment 2).
OSHA thus agrees with UAW and BGA that an action level lower than
one-half of the PEL would provide a higher degree of confidence that
exposures are not likely to exceed the PEL. However, OSHA's policy is
to set the action level at a value that effectively encourages
employers to reduce exposures below the action level while still
providing reasonable assurance that employee exposures are typically
below the PEL. The Agency's experience with previous standards also
indicates that an action level of one-half the PEL effectively
encourages employers, where feasible, to reduce exposures below the
action level to avoid the added costs of required compliance with
provisions triggered by the action level.
OSHA is convinced, therefore, that an action level is needed and
decided to set the action level at one-half of the PEL, based on
residual risk at the PEL of 50 [mu]g/m\3\, the feasibility of measuring
exposures at an action level of 25 [mu]g/m\3\, and the administrative
convenience of having the action level set at one-half the PEL, as it
is in other OSHA standards. OSHA's risk assessment indicates that
significant risk remains at the PEL of 50 [mu]g/m\3\. OSHA therefore
has a duty to impose additional requirements on employers to reduce
remaining significant risk when those requirements will afford benefits
to employees and are feasible (Building and Construction Trades
Department, AFL-CIO v. Brock, 838 F.2d 1258, 1269 (D.C. Cir 1988)).
With significant risk remaining at 50 [mu]g/m\3\, reducing that risk by
incorporating an action level is necessary and appropriate. OSHA
concludes that the action level will result in a real and necessary
further reduction in risk beyond that provided by the PEL alone.
"Competent person" means an individual who is capable of
identifying existing and foreseeable respirable crystalline silica
hazards in the workplace and who has authorization to take prompt
corrective measures to eliminate or minimize them. The competent person
must also have the knowledge and ability necessary to fulfill the
responsibilities set forth in paragraph (g) of the construction
standard. OSHA has not included requirements related to a competent
person in the general industry and maritime standard. This definition
therefore is included only in the construction standard.
In the proposal, OSHA defined competent person as one who is
capable of identifying existing and predictable respirable crystalline
silica hazards in the surroundings or working conditions and who has
authorization to take prompt corrective measures to eliminate them.
OSHA received a number of comments related to this definition. Many of
these commenters suggested that the definition should be expanded. For
example, Building and Construction Trades Department, AFL-CIO (BCTD)
recommended that OSHA revise the proposed definition to require that
the competent person be capable of identifying the proper methods to
control existing and predictable hazards in the surroundings or working
conditions. BCTD also asked that the definition specify that the
competent person be "designated by the employer to act on the
employer's behalf." It proposed specific language that incorporated
these suggestions (Document ID 4223, p. 112). International Union of
Operating Engineers (IUOE) endorsed the BCTD definition and
International Union of Bricklayers and Allied Craftworkers (BAC) agreed
with BCTD that OSHA's definition needed to be more fully developed
(Document ID 2262, p. 40; 2329, p. 5).
The American Society of Safety Engineers (ASSE) advocated for the
following definition, which it based on that of the asbestos standard:
Competent person means, in addition to the definition in 29 CFR
1926.32(f), one who is capable of identifying existing respirable
crystalline silica hazards in the workplace and selecting the
appropriate control strategy for such exposure and for developing
and overseeing written access control plans, who has the authority
to take prompt corrective measures to eliminate such hazards, as
specified in 29 CFR 1926.32(f), and who is trained in a manner
consistent with OSHA requirements for training (Document ID 4201,
pp. 3-4).
Finally, NIOSH noted the American National Standards Institute
(ANSI) AIO.38 definition of competent person:
One who, as a result of specific education, training, and/or
experience, is capable of identifying existing and predictable
hazards in the surroundings [or] working conditions that are
unsanitary, hazardous or dangerous to employees, and who has the
authorization and responsibility to take prompt corrective measures
to eliminate them [emphasis omitted] (as cited in Document ID 2177,
Attachment B, p. 9).
In determining if the proposed definition for competent person
needed to be revised, OSHA considered these comments and the definition
of competent person in the safety and health regulations for
construction (29 CFR 1926.32(f)). Under 29 CFR 1926.32(f), competent
person is defined as one capable of identifying existing and
predictable hazards in the surroundings or working conditions that are
unsanitary, hazardous, or dangerous to employees and who is authorized
to take prompt corrective measures to eliminate them. OSHA concludes
that its definition for competent person is consistent with 1926.32(f)
but tailored to respirable crystalline silica by specifying
"respirable crystalline silica hazards" instead of "unsanitary,
hazardous, or dangerous" conditions. OSHA did make a few minor
revisions to its proposed definition. The Agency replaced the word
"one" with "individual," which is merely an editorial change. The
Agency removed the phrase "in the surroundings or working conditions"
and changed it to "in the workplace" to make it specific to the
workplace. The Agency removed the phrase "to eliminate them" and
changed it to "to eliminate or minimize them" to denote there may be
cases where complete elimination would not be feasible. OSHA also
changed "predicted" to "foreseeable" to make the wording consistent
with the scope of the standard (paragraph (a)).
OSHA agrees with ASSE and the ANSI definition highlighted by NIOSH
that the definition for competent person must indicate that the
competent person has appropriate training, education, or experience.
Therefore, OSHA further revised the proposed definition for competent
person to indicate that the competent person must have the knowledge
and ability necessary to fulfill the responsibilities set forth in
paragraph (g). Comments regarding knowledge or training for a
competent person and OSHA's responses to those comments are discussed
in the summary and explanation of Written Exposure Control Plan.
The requirement that the competent person have the knowledge and
ability to fulfill the responsibilities set forth in paragraph (g)
addresses BCTD's and ASSE's requests to amend the definition to specify
that the competent person be capable of identifying or selecting the
proper methods to control hazards in the surroundings or working
conditions. It is clear from paragraph (g) that the competent person
must be familiar with and also capable of implementing the controls and
other protections specified in the written exposure control plan.
ASSE also requested that the definition indicate that the competent
person be capable of developing and overseeing the written access
control plan, which OSHA had proposed. However, the final rule does not
specify a written access control plan, and instead requires a written
exposure control plan. Regardless, OSHA does not agree with ASSE's
suggestion that the definition should be revised to indicate capability
to develop a written plan. OSHA assigns that responsibility to the
employer because under paragraph (g)(4), the competent person is
someone on the job site who makes frequent and regular inspections, and
thus may not be involved in developing the written exposure control
plan in an office environment. OSHA also disagrees with BCTD that the
definition should specify that the competent person is designated by
the employer to act on behalf of the employer. The employer's
obligation to designate a competent person is clearly specified in
paragraph (g)(4) and the definition clearly states that the competent
person has authority to promptly apply corrective measures.
The competent person concept has been broadly used in OSHA
construction standards (e.g., 29 CFR 1926.32(f) and 1926.20(b)(2)),
particularly in safety standards. This standard does not affect the
competent person provisions in these other standards.
"Employee exposure" means the exposure to airborne respirable
crystalline silica that would occur if the employee were not using a
respirator. This definition clarifies the requirement that employee
exposure must be measured as if no respiratory protection is being
worn. The definition, which is consistent with OSHA's previous use of
the term in other standards, did not generate any comment and is
unchanged from the proposal.
"High-efficiency particulate air (HEPA) filter" means a filter
that is at least 99.97 percent efficient in removing mono-dispersed
particles of 0.3 micrometers in diameter. The definition is unchanged
from the proposal. HEPA filters are more efficient than membrane
filters because they are designed to target much smaller particles. In
the housekeeping requirements of paragraph (h)(1) of the standard for
general industry and maritime (paragraph (f)(1) of the standard for
construction), OSHA refers to HEPA-filtered vacuuming as an example of
an appropriate cleaning method, and the Table 1 entry for handheld and
stand-mounted drills requires use of a HEPA-filtered vacuum (if a
commercially available hole-cleaning kit connected to a dust collector
is not being used). OSHA had also proposed HEPA-filtered dust
collectors as controls for some tasks listed on Table 1 of the proposed
standard for construction.
The Agency received one comment related to HEPA filters from the
Occupational and Environmental Health Consulting Services (OEHCS).
First, OEHCS recommended that the definition be expanded to indicate
that HEPA filters are effective at removing particles in the 0.3-
micrometer size range, as measured by a laser particle counter. Second,
it requested addition of the term "Portable High Efficiency Air
Filtration (PHEAF)" device, defined as a portable device equipped with
a certified HEPA filter that, when tested as a complete unit, is 99.97
percent effective in removing particles in the 0.3-micrometer size
range, as measured by a laser particle counter (Document ID 1953, pp.
4-6). OEHCS advocated for a requirement that portable filtration
devices (e.g., HEPA vacuums, dust collectors used on tools, and filter
systems for enclosed cabs) meet the definition of PHEAF. It argued that
HEPA vacuums or other portable filtration devices might not perform
effectively in the field due to inadequate, damaged, or deteriorating
sealing surfaces; replacement filters that do not fit correctly; filter
cabinets that are damaged; or filters that are punctured. Claiming that
damaged filters might not build up enough pressure differential to
signal that they should be changed, OEHCS recommended a requirement for
field testing the devices using a laser particle counter to ensure that
HEPA filters function as intended (Document ID 1953, Attachment 1, pp.
2-4).
OSHA encourages employers to ensure that HEPA filters function in
the field according to the specifications of this definition. However,
the Agency concludes that it is not appropriate to include requirements
for PHEAF devices, as defined by OEHCS, or laser particle counting
testing, in the rule due to the lack of documented effectiveness or
consistency with the definition and because of the lack of support in
the record. As a result, OSHA is retaining its proposed definition for
HEPA filter and is not adding PHEAF to the definitions section.
"Objective data" means information, such as air monitoring data
from industry-wide surveys or calculations based on the composition of
a substance, demonstrating employee exposure to respirable crystalline
silica associated with a particular product or material or a specific
process, task, or activity. The data must reflect workplace conditions
closely resembling or with a higher exposure potential than the
processes, types of material, control methods, work practices, and
environmental conditions in the employer's current operations.
The proposed definition of "objective data" also included
"calculations based on the...chemical and physical properties of a
substance" as an example of a type of objective data that might
demonstrate employee exposure to respirable crystalline silica. BCTD
objected to this example's inclusion in the definition (Document ID
2371, Attachment 1, pp. 11-12). Although BCTD agreed that the chemical
and physical properties of a substance are among the factors that may
be relevant in determining whether data from one set of circumstances
can be used to characterize the exposures in other circumstances, BCTD
stated that the proposed definition suggested that the chemical and
physical properties of the material could be determinative in every
instance. It also maintained that on construction sites the work
processes themselves are more consistently a significant predictor of
ambient silica exposures than percentage of silica in the material
itself. Finally, BCTD argued that it is very important to focus not
only on the overall operation, but also the specific silica dust-
generating task.
In including this item in the definition, OSHA did not intend to
imply that it would be relevant in all circumstances. Nonetheless, OSHA
has removed the phrase "chemical and physical properties" from the
final definition of "objective data" because it has concluded that a
substance's chemical and physical properties are not typically relevant
for demonstrating exposures to respirable crystalline silica. However,
in those instances where a substance's physical and chemical properties
demonstrate employee exposure to respirable crystalline silica
associated with a particular product or material or a specific process,
task, or activity, an employer may use that information as objective
data under this rule.
The proposed rule also stated that objective data is information
demonstrating employee exposure to respirable crystalline silica
associated with a particular product or material or a specific process,
operation, or activity. Throughout this rule, OSHA has often replaced
the word "operation" with the word "task" (see summary and
explanation of Specified Exposure Control Methods for further
discussion). OSHA has made the change to "task" (instead of
"operation") in this definition to remain consistent with that
change. This is also consistent with NIOSH's recommendation to add
specificity to the definition by including the term "task" (Document
ID 2177, Attachment B, p. 12).
In addition, the proposal indicated that "objective data" needed
to reflect workplace conditions closely resembling the processes, types
of material, control methods, work practices, and environmental
conditions in the employer's current operations. Dow Chemical Company
stated that this requirement is generally appropriate, but argued that
when data pertain to a more challenging work environment with higher
potential for exposure, those data should be considered objective data
(Document ID 2270, p. 2). It explained:
If data from a more challenging environment demonstrate
compliance with the Permissible Exposure Limit, then one may infer
with confidence that workers in a less challenging environment
(i.e., with less potential for exposure) are also not exposed above
the PEL. Even if the two work environments are not "closely
resembling," the data are still an objective, valid method of
screening workplaces that have a clearly lower risk of exposure
(Document ID 2270, p. 2).
OSHA agrees with Dow that data pertaining to an environment with
higher exposure potential can be used as objective data for other
environments with less potential for exposure. Therefore, OSHA added
"or with a higher exposure potential" to the definition.
Edison Electric Institute (EEI) requested that OSHA harmonize the
definition of "objective data" throughout its regulations (Document
ID 2357, p. 22). OSHA recognizes that the term has evolved over time
based on the Agency's experience implementing those standards.
"Objective data", as defined in this standard, is based on the record
in this rulemaking and reflects an appropriate definition in the
context of exposures to respirable crystalline silica. Additionally,
OSHA has established a process, the Standards Improvement Project, to
improve and streamline OSHA standards, including the revision of
individual requirements within rules that are inconsistent. OSHA will
consider reviewing the consistency of this definition in the next
iteration of this ongoing effort.
Many commenters suggested that OSHA add specificity with regards to
what is considered objective data and establish criteria for objective
data in the definition (e.g., Document ID 2177, Attachment B, p. 11;
2181, p. 5; 2253, p. 4; 2256, Attachment 2, p. 10; 2339, p. 7; 2371,
Attachment 1, p. 12; 2379, Appendix 1, pp. 54-55; 2380, Attachment 2,
p. 26; 4223, p. 70). As discussed in the summary and explanation of
Exposure Assessment, OSHA intends for the performance option to give
employers flexibility to accurately characterize exposures using
whatever processes or data are most appropriate for their
circumstances. The Agency concludes it would be inconsistent to include
specifications or criteria in the definition of objective data and thus
has not done so here.
Commenters also provided examples of alternative exposure
measurement and characterization strategies that could generate
objective data, such as: area sampling (Document ID 2195, pp. 36-37);
area exposure profile mapping (Document ID 2379, Appendix 1, pp. 48-
49); real-time monitoring (Document ID 2256, Attachment 3, p. 12; 2357,
pp. 37-38; 2379, Appendix 1, pp. 48-49, 55-56; 3578, Tr. 941-942; 3579,
Tr. 161-162; 3588, Tr. 3798-3800; 4204, p. 56); and geotechnical
profiling with testing for crystalline silica content (Document ID
2262, p. 13). Trolex LTD pointed to emerging methods and technologies,
such as new optical methods for particle counting and identification,
which might provide enhanced measurements of real-time employee
exposure to respirable crystalline silica in the future (Document ID
1969, p. 2).
In addition, commenters provided specific examples of types of
information and information sources that they felt should be considered
objective data. For example, the American Foundry Society (AFS)
commented that objective data should include data that permits reliable
estimation of exposure, such as: data from real-time monitors and area
exposure mapping; data from less than full-shift samples where
professional judgment can be used to determine exposure levels; and
exposure data where the percent of silica is calculated using a
historical average for the area or operation involved (Document ID
2379, Appendix 1, pp. 54-55). The National Association of Manufacturers
suggested the following as reliable sources of objective data:
published scientific reports in the open scientific literature; NIOSH
Health Hazard Evaluations; insurance carriers' loss prevention reports;
and information that the silica in a process cannot be released because
it is bound in a matrix preventing formation of respirable particles
(Document ID 2380, Attachment 2, p. 26). ASSE identified industry-wide
data, safety data sheets from product manufacturers, prior historical
sampling data under comparable conditions, and aggregated company-wide
sampling information as reliable sources of objective data (Document ID
3578, Tr. 1036). Commenters also pointed to data collected by a trade
association from its members (e.g., Document ID 2181, pp. 5-6, 7; 2371,
Attachment 1, Appendix A; 3544, pp. 12-13; 3583, Tr. 2394; 3585, Tr.
2905-2906; 3588, Tr. 3936-3938; 4197, pp. 1-6; 4198, pp. 1-181; 4223,
pp. 68-70).
The Agency, while including specific examples in the definition
(i.e., air monitoring data from industry-wide surveys and calculations
based on the composition of a substance), does not intend to limit the
information that can be considered objective data to the information
from those sources. OSHA agrees that data developed with alternative
exposure measurement and characterization strategies, both those
currently available and those that become available in the future, and
the types of information and information sources suggested by
commenters can be used as objective data where the conditions of the
definition are satisfied. Monitoring data obtained prior to the
effective date of the rule can also be considered objective data if it
demonstrates employee exposure to respirable crystalline silica
associated with a particular product or material or a specific process,
task, or activity and reflects workplace conditions closely resembling
or with a higher exposure potential than the processes, types of
material, control methods, work practices, and environmental conditions
in the employer's current operation.
Objective data is further discussed in the summary and explanation
of Scope and Application (paragraph (a)(2) for general industry and maritime)
and Exposure Assessment (paragraph (d) for general industry and
maritime standard and paragraph (d)(2) for the construction standard).
"Physician or other licensed health care professional [PLHCP]"
means an individual whose legally permitted scope of practice (i.e.,
license, registration, or certification) allows him or her to
independently provide or be delegated the responsibility to provide
some or all of the particular health care services required by
paragraph (i) of this section (paragraph (h) of the standard for
construction). This definition is unchanged from the proposal, and is
included because the standard requires that all medical examinations
and procedures be performed by or under the supervision of a PLHCP.
OSHA received two comments on the definition of PHLCP, both of
which addressed the scope of the PHLCP's qualifications, from APHA and
ATS (Document ID 2175, p. 5; 2178, Attachment 1, p. 5). ATS agreed with
OSHA's determination of who is qualified to be a PLHCP (Document ID
2175, p. 5). APHA advocated that the PLHCP:
...should be licensed for independent practice...and have
training and experience in clinical and in population/preventive
health, in managing and interpreting group surveillance information,
and in the care and management of respiratory illness (Document ID
2178, Attachment 1, p. 5).
APHA commented that:
...different members of the health team may provide different
required services through referral or other arrangements, but the
designated PLHCP should have responsibility for program oversight
and coordination (Document ID 2178, Attachment 1, p. 5).
As discussed further in the summary and explanation of Medical
Surveillance, OSHA agrees that different tasks may be performed by
various PLHCPs, according to their licenses, but has determined that
requiring a license for independent practice and the extra training and
responsibilities advocated by APHA are neither necessary nor
appropriate for the PLHCP in OSHA standards. Any PLHCP may perform the
medical examinations and procedures required under the standard when he
or she is licensed, registered, or certified by state law to do so. Who
qualifies to be a PLHCP is determined on a state-by-state basis by
state licensing bodies. OSHA's broad definition for PLHCP gives the
employer the flexibility to retain the services of a variety of
qualified licensed health care professionals. Moreover, since the term
PHLCP includes more than just physicians, it addresses concerns about
the limited availability of medical providers in rural areas (e.g.,
Document ID 2116, Attachment 1, p. 43; 2365, p. 10).
OSHA has included the same definition for PLHCP in other standards
and continues to find that it is appropriate to allow any individual to
perform medical examinations and procedures that must be made available
under the standard when he or she is appropriately licensed by state
law to do so and is therefore operating under his or her legal scope of
practice. PLHCP, as defined and used in this standard, is consistent
with other recent OSHA standards, such as chromium (VI) (29 CFR
1910.1026), methylene chloride (29 CFR 1910.1052), and respiratory
protection (29 CFR 1910.134). OSHA's experience with PLHCPs in these
other standards supports the Agency's determination.
"Regulated Area" means an area, demarcated by the employer, where
an employee's exposure to airborne concentrations of respirable
crystalline silica exceeds, or can reasonably be expected to exceed,
the PEL. The definition is unchanged from the proposed standard. This
definition is consistent with the use of the term in other OSHA
standards, including those for chromium (VI) (29 CFR 1910.1026), 1,3-
butadiene (29 CFR 1910.1051), and methylene chloride (29 CFR
1910.1052).
OSHA proposed the inclusion of regulated areas in the standards for
both construction and general industry/maritime, but has not included
this provision, or the associated definition, in the final standard for
construction. Construction industry stakeholders should instead refer
to paragraph (g)(1)(iv) for written exposure control plan requirements
to describe procedures for restricting access.
Several stakeholders, including the Construction Industry Safety
Coalition (CISC) and National Association of Home Builders, requested
that OSHA clarify what "reasonably expected" means (e.g., Document ID
2296, p. 25; 2319, p. 89). CISC argued that "[s]uch subjective
language is not enforceable and...will be fraught with compliance
problems..." (Document ID 2296, p. 25; 2319, p. 89).
As noted above, the language in the regulated areas definition has
been included in a number of previous OSHA standards. Based on OSHA's
experience with these standards, OSHA expects that employers will have
little difficulty understanding the meaning of the phrase "reasonably
be expected to exceed." One reason OSHA chooses to utilize language
that has been used in previous standards, where possible, is to avoid
the sort of confusion CISC describes. In addition, the basis for
establishing regulated areas in general industry and maritime and the
reason for omitting this requirement in the construction standard are
discussed in further detail in the summary and explanation of Regulated
Areas.
"Respirable crystalline silica" means quartz, cristobalite, and/
or tridymite contained in airborne particles that are determined to be
respirable by a sampling device designed to meet the characteristics
for respirable-particle-size-selective samplers specified in the
International Organization for Standardization (ISO) 7708:1995: Air
Quality--Particle Size Fraction Definitions for Health-Related
Sampling. The definition in the rule is very similar to the proposed
definition with one modification. OSHA changed the wording from "means
airborne particles that contain quartz, cristobalite, and/or tridymite
and whose measurement is determined by a sampling device..." to
"means quartz, cristobalite, and/or tridymite contained in airborne
particles that are determined to be respirable by a sampling device . .
." to make it clear that only that portion of the particles that is
composed of quartz, cristobalite, and/or tridymite is considered to be
respirable crystalline silica.
The definition for respirable crystalline silica encompasses the
forms of silica (i.e., quartz, cristobalite, and tridymite) covered
under current OSHA standards and harmonizes the Agency's practice with
current aerosol science and the international consensus that the ISO
convention represents. The American Conference of Governmental
Industrial Hygienists (ACGIH) and the European Committee for
Standardization (CEN) have adopted the ISO criteria for respirable
particulate collection efficiency, and the criteria are sometimes
referred to as the ISO/CEN definition. NIOSH has also adopted the ISO
definition in its Manual of Sampling and Analytical Methods (Document
ID 0903, p. 2). Adoption of this definition by OSHA allows for
workplace sampling for respirable crystalline silica exposures to be
conducted using any particulate sampling device that conforms to the
ISO criteria (i.e., a device that collects dust according to the
particle collection efficiency curve specified in the ISO standard).
The relationship between the ISO criteria for respirable particulate
collection efficiency and the ACGIH criteria is discussed in greater
detail in the Sampling and Analysis discussion in Chapter IV of the
FEA.
The U.S. Chamber of Commerce (the Chamber), Halliburton, and the
National Rural Electric Cooperative Association (NRECA) asserted that
OSHA's proposed definition of respirable crystalline silica would
encompass non-respirable particles (Document ID 2288, p. 15; 2302, p.
7; 2365, p. 12). NRECA stated:
...the proposed definition would include anything that gets
collected onto the sampling media from respirable-particle size-
selective samplers. Unfortunately, these samplers are not fool-proof
and often much larger sized particles do make their way into the
sampling media; that is, they collect total crystalline silica dusts
rather than just the respirable portions. This definition will
include all total dusts that make their way through the cyclone and
into the sampling media, thus suggesting a much larger exposure than
is otherwise the case...(Document ID 2365, p. 12).
As indicated in the discussion of the feasibility of measuring
respirable crystalline silica exposures in Chapter IV of the FEA, there
is currently no sampling device that precisely matches the ISO criteria
in capturing respirable dust. However, available research indicates
that many existing devices can achieve good agreement with the ISO
criteria. When operated correctly, the sampling devices do not collect
total dusts; they collect only the respirable fraction.
The Chamber and NRECA also argued that OSHA's proposed definition
of respirable crystalline silica would include substances other than
crystalline silica (Document ID 2288, p. 15; 2365, p. 12; 3578, Tr.
1138). NRECA stated:
An additional concern with the definition is that it states
"any particles that contain quartz, cristobalite, and/or tridymite
. . ." It is possible to interpret this portion of the definition
to mean that any other mineral/impurities that were able to be
collected into the sampling media will be counted/weighed as opposed
to just the silica portions...(Document ID 2365, p. 12).
In addition, American Industrial Hygiene Association (AIHA) indicated
that the proposed definition would include the entirety of a sample of
dust containing any miniscule but detectable quantity of quartz,
cristobalite or tridymite, and recommended revising the definition
(Document ID 2169, pp. 2-3).
OSHA recognizes that the proposed definition could have been
misunderstood to encompass components of respirable dust particles
other than quartz, cristobalite, and tridymite. This was not the
Agency's intent, and, in response to these comments, OSHA has revised
the definition to clarify that only the portion of the particles
composed of quartz, cristobalite, or tridymite is considered to be
included in the definition of respirable crystalline silica.
Ameren Corporation supported OSHA's inclusion of quartz and
cristobalite and allowing the use of a sampling device designed to meet
the characteristics for respirable particle size-selective samplers
specified in ISO 7708:1995 in the definition, but indicated that the
definition should be limited to a "percentage of 1% or greater"
(Document ID 2315, p. 3). However, it did not provide a rationale for
why OSHA should include this in the definition. Including such a
limitation in the definition of respirable crystalline silica would
have the effect of limiting coverage of the rule to situations where
crystalline silica concentrations in a mixture exceed the 1 percent
threshold. As discussed in the summary and explanation of Scope and
Application, OSHA concludes that it is not appropriate to limit
coverage of the rule to situations where concentrations of crystalline
silica in a mixture exceed a 1 percent threshold.
The Society for Protective Coatings (SSPC) and the National
Automobile Dealers Association recommended that OSHA distinguish
between amorphous silica and crystalline silica in the definition
(Document ID 2120, p. 2; 2358, p. 5). SSPC also provided a link to a
Web page (http://www.crystallinesilica.eu/content/what-respirable-crystalline-silica-rcs)
to guide the Agency on revising the definition. OSHA finds that the
term "crystalline" is sufficiently descriptive and does not merit
further explanation in the definition. However, the Agency affirms
here that fused quartz and other forms of amorphous silica are not
considered crystalline silica under the rule.
The SEFA Group (formerly the Southeastern Fly Ash Company)
suggested adding a definition for "free respirable crystalline
silica" to describe crystalline silica as an independent structure
with varying surface chemistry, as distinguished from crystalline
silica that is incorporated into a larger matrix of the parent mineral
(Document ID 2123, p. 2). OSHA has revised the definition to clarify
that respirable crystalline silica includes only the crystalline silica
contained in airborne particles, i.e., the component in dust that is
crystalline silica and not some other mineral. The Agency does not
agree that defining the term "free respirable crystalline silica"
will alter the meaning or enhance the clarity of the rule, and has not
added this term.
"Specialist" means an American Board Certified Specialist in
Pulmonary Disease or an American Board Certified Specialist in
Occupational Medicine. The term is used in paragraph (i) of the
standard for general industry and maritime, (paragraph (h) of the
standard for construction), which sets forth requirements for medical
surveillance. For example, paragraph (i)(7)(i) of the standard for
general industry and maritime, (paragraph (h)(7)(i) of the standard for
construction) requires that the employer make available a medical
examination when specialist referral is indicated in the PLHCP's
written medical opinion for the employer.
The proposed rule did not include this term in the Definitions
paragraph because it only allowed referral to an American Board
Certified Specialist in Pulmonary disease, which was clearly addressed
in the Medical Surveillance paragraph of the rule. However, several
commenters recommended that OSHA expand the types of specialists to
whom employees could be referred. For example, Dow Chemical requested
that OSHA not require the pulmonary specialist to be board certified to
expand availability of specialists and noted that several OSHA
standards, such as benzene and 1,3-butadiene, do not require the
specialist to be board certified (Document ID 2270, pp. 5-8). The Glass
Association of America, Asphalt Roofing Manufacturers Association,
North American Insulation Manufacturers Association, ATS, and BCTD
requested that OSHA also allow referral to an occupational medicine
specialist, with many of them specifying a board certified occupational
medicine specialist (Document ID 2215, p. 9; 2291, p. 26; 2348,
Attachment 1, p. 40; 3577, Tr. 778; 4223, p. 129).
OSHA is retaining the requirement for board certification to ensure
a high level of competency. However, OSHA is persuaded by comments and
testimony that individuals who are either American Board Certified in
Occupational Medicine or American Board Certified in Pulmonary Disease
are recognized specialists qualified to examine patients referred for
possible respirable crystalline silica-related diseases. OSHA concludes
that both pulmonary disease and occupational medicine specialists are
qualified to counsel employees regarding work practices and personal
habits that could affect their respiratory health, consistent with
recommendations in Section 4.7.2 in ASTM standards E 1132-06, Standard
Practice for Health Requirements Relating to Occupational Exposure to
Respirable Crystalline Silica and E 2626-09, Standard Practice for
Health Requirements Relating to Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities
(Document ID 1466, p. 5; 1504, p. 5). OSHA therefore added the
definition to allow referrals to providers who are American Board
certified in pulmonary disease or occupational medicine. The addition
of the term to definitions also allows OSHA to simply refer to
"specialist" when referring to American Board certified pulmonary
disease and occupational medicine specialists in the medical
surveillance paragraph of the rule.
"Assistant Secretary," "Director," and "This section" are
also defined terms. The definitions are consistent with OSHA's previous
use of these terms in other health standards and have not changed since
the proposal, which elicited no comments.
Finally, stakeholders suggested that OSHA define a number of new
terms, including: "affected employee" (American Iron and Steel
Institute (AISI) (Document ID 2261, p. 4)), "aged silica" (the
Sorptive Minerals Institute (Document ID 3587, Tr. 3698-3699)),
"asphalt milling" (IUOE (Document ID 2262, pp. 23-24)), "chest
radiograph" (NIOSH (Document ID 2177, Comment B, pp. 40-41)),
"controlling employer" (BAC and BCTD (Document ID 2329, p. 7; 2371,
pp. 38-40)), "each employee" or "each affected employee" (AISI
(Document ID 3492, p. 3)), "earth moving" (IUOE (Document ID 2262,
pp. 6-9, 15)), "earth moving equipment" (IUOE (Document ID 3583, Tr.
2356-2360; 2262, pp. 6-9, 15)), "estimating respirable dust,
excessive" (Industrial Hygiene Specialty Resources (Document ID 2285,
p. 7)), "gross contamination" or "grossly contaminated" (ORCHSE,
AFS, and NAHB (Document ID 2277, p. 4; 3584, Tr. 2669-2671; 3487, pp.
21-22; 2296, p. 29; 2379, Attachment B, p. 32)), "grossly" (Tile
Council of North America (Document ID 2363, p. 6)), "intermittent
work" (EEI (Document ID 2357, p. 14)), "respirable dust" (AFS
(Document ID 2379, Attachment B, pp. 16, 28)), "safety and health
professional technician" (Dr. Bird of the Chamber (Document ID 3578,
Tr. 1176-1177)), "short duration" (EEI (Document ID 2357, p. 14)),
and "silica exposure" (AIHA (Document ID 2169, p. 5)).
OSHA has concluded that these terms do not need to be defined in
the rule. Many of the terms were part of the proposal or were included
in stakeholder's comments on the proposal, but do not appear in the
rule. For example, the proposed rule contained a provision related to
protective work clothing in regulated areas that would have been
triggered where there is potential for employees' work clothing to
become grossly contaminated with finely divided material containing
crystalline silica. As discussed in summary and explanation of
Regulated Areas, OSHA has not included a requirement for employers to
provide protective work clothing or other means of removing silica dust
from clothing in the rule, and the rule does not otherwise use the
terms "grossly," "gross contamination," or "grossly
contaminated." Therefore, there is no reason to define these terms.
OSHA concludes that many of the other terms that stakeholders asked
the Agency to define are sufficiently explained in the preamble or
their meanings are clear. For example, OSHA explains the term
"affected employee" in the summary and explanation of Exposure
Assessment. Because the term only appears in paragraphs (d)(6) and (7)
of the standard for general industry and maritime (paragraphs
(d)(2)(vi) and (vii) for construction) and is thoroughly explained in
the summary and explanation, OSHA concludes that it need not be defined
in this section.
Specified Exposure Control Methods. OSHA's standard requires
employers engaged in construction to control their employees' exposure
to respirable crystalline silica. Paragraph (c) of the standard for
construction describes the specified exposure control methods approach.
This approach includes "Table 1: Specified Exposure Control Methods
When Working With Materials Containing Crystalline Silica," a table
identifying common construction tasks known to generate high exposures
to respirable crystalline silica and specifying appropriate and
effective engineering controls, work practices, and respiratory
protection for each identified task. For each employee engaged in a
task identified on Table 1, the employer is required to fully and
properly implement the engineering controls, work practices, and
respiratory protection specified for the task on Table 1, unless the
employer assesses and limits the exposure of the employee to respirable
crystalline silica in accordance with paragraph (d) of the standard for
construction. If the employer fully and properly implements the
engineering controls, work practices, and respiratory protection
specified for each employee engaged in a task identified on Table 1,
the employer is not required to conduct exposure assessments or
otherwise comply with a PEL for those employees. If the employer does
not follow Table 1 for employees engaged in identified tasks or if the
respirable crystalline silica-generating task is not identified on
Table 1, the employer must assess and limit the exposure of employees
in accordance with paragraph (d) of the standard for construction.
Paragraph (d) of the standard for construction imposes requirements
similar to OSHA's traditional approach of requiring employers to
demonstrate compliance with a PEL through required exposure assessments
and controlling employee exposures through the use of feasible
engineering controls and work practices (i.e., the hierarchy of
controls) (see the summary and explanation of Alternative Exposure
Control Methods for further discussion of this approach).
The concept for the specified exposure control methods approach was
included in the proposed rule. OSHA also included a version of Table 1
in the proposed rule for construction employers, identifying specific
engineering controls, work practices, and respiratory protection for
common construction tasks that employers could use to meet the
requirement to implement engineering and work practice controls.
Employers fully implementing the engineering controls, work practices,
and respiratory protection on Table 1 would not have been required to
conduct exposure assessments for employees performing a listed task,
but would have been required to comply with the 50 [micro]g/m\3\ PEL
for those employees. For tasks where respirator use was to be required,
employees were presumed to be exposed above the PEL, and thus the
proposed standard would have required the employer to comply with all
provisions that would be triggered by exposure above the PEL (e.g.,
regulated areas, medical surveillance), except for exposure monitoring.
Prior to the NPRM, OSHA included this alternative compliance
approach in the Preliminary Initial Regulatory Flexibility Analysis
(PIRFA) provided to small business representatives during the Small
Business Regulatory Enforcement Fairness Act (SBREFA) process (Document
ID 0938, pp. 16-17). Participants in the SBREFA process generally
supported the approach and their comments further informed the Agency
in developing the proposed rule (Document ID 0937, pp. 37-39). An
alternative compliance approach similar to that developed by OSHA for
the SBREFA process was also included in ASTM E 2625-09, Standard
Practice for Controlling Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities, a
consensus standard issued in May 2009 developed by a committee
consisting of both labor and industry representatives for crystalline
silica exposures in construction (Document ID 1504). Following this,
on December 10, 2009, the Advisory Committee on Construction Safety
and Health (ACCSH) recommended that OSHA include the specified
exposure control methods approach in its proposed rule
(Document ID 1500, p. 13).
The approach of specifying a list of tasks with a corresponding
list of controls to simplify compliance in the construction industry
received wide support from representatives in government, including the
National Institute for Occupational Safety and Health (NIOSH);
professional organizations, including the American Industrial Hygiene
Association (AIHA) and the American Society of Safety Engineers (ASSE);
labor, including the International Union of Operating Engineers (IUOE),
the Building and Construction Trades Department of the AFL-CIO (BCTD),
the Laborers' Health and Safety Fund of North America (LHSFNA), and the
International Union of Bricklayers and Allied Craftworkers (BAC); and
industry groups, including the Associated General Contractors of New
York State, the Edison Electric Institute (EEI), and the National
Asphalt Pavement Association (NAPA) (e.g., Document ID 2177, Attachment
B, p. 23; 3578, Tr. 1028; 2339, p. 8; 3583, Tr. 2337-2338; 2371,
Attachment 1, p. 22-23; 3589, Tr. 4192-4193; 2329, pp. 5-6; 2145, pp.
4-5; 3583, Tr. 2171; 2357, p. 26). Walter Jones, an industrial
hygienist representing LHSFNA, testified that the approach "not only
makes compliance...easier to determine, enforce, and teach, it also
assures acceptable levels of healthfulness" (Document ID 3589, Tr.
4193).
Industry trade associations, such as the Construction Industry
Safety Coalition (CISC), Leading Builders of America (LBA), the
Mechanical Contractors Association of America, and individual
construction employers, including Atlantic Concrete Cutting, Inc. and
Holes Incorporated, generally supported the overall approach while
being critical of the specifics of Table 1 (e.g., Document ID 4217, p.
20; 2367, p. 2; 2338, p. 3; 2269, pp. 21-22; 2143, pp. 2-3). CISC
stated that its group of employers "continues to be appreciative of
OSHA's efforts to try to make a simple compliance option...for
construction employers" (Document ID 4217, p. 20).
One commenter, Francisco Trujillo, safety director for Miller and
Long, Inc., suggested that the specified exposure control methods
approach to compliance in the construction industry is not a substitute
for safety professionals and industrial hygienists conducting exposure
assessments and selecting the appropriate engineering controls, work
practices, and respiratory protection for each task based on the
results. He commented that "[t]he implication that if Table 1 is
followed everything will be fine is unrealistic..." and recommended
that Table 1 be at most non-mandatory guidance (Document ID 2345, p.
4).
OSHA agrees that safety professionals and industrial hygienists
play a key role in ensuring the safety of employees exposed to silica
during certain activities, including those not listed on Table 1, and
can also help ensure that the engineering controls, work practices, and
respiratory protection specified on Table 1 are fully and properly
implemented. However, as discussed below, the Agency is not persuaded
that construction employees will always be better protected by the
traditional performance approach of establishing a PEL and requiring
periodic exposure assessments, particularly when the tasks and tools
that cause high exposures to respirable crystalline silica, and the
dust control technologies available to address such exposures, can be
readily identified.
Although there was general agreement among commenters that an
alternative approach was needed to simplify compliance for the
construction industry, commenters provided various opinions on how such
an alternative compliance approach should be structured to ensure that
it was workable in practice. Several commenters, including BCTD,
LHSFNA, EEI, LBA, Fann Contracting, Inc., CISC, ASSE, the National
Association of Home Builders (NAHB), the Associated Builders and
Contractors (ABC), and Holes Incorporated, urged OSHA to exempt
employers complying with Table 1 from also complying with the PEL
(e.g., Document ID 2371, Attachment 1, p. 26; 4223, p. 92-94; 4207, p.
3; 2357, p. 26; 2269, pp. 21-22; 2116, Attachment 1, p. 29; 2319, pp.
123-124; 2339, pp. 8-9; 2296, p. 41; 2289, p. 7; 3580, Tr. 1364). Holes
Incorporated and ABC suggested that employers would not use an approach
that required compliance with both the PEL and specified engineering
controls (Document ID 3580, Tr. 1364; 2289, p. 7). The National Utility
Contractors Association (NUCA) argued that not linking the actions on
Table 1 directly to compliance with the regulation was confusing and
would make it difficult for contactors to be certain they are in
compliance (Document ID 2171, p. 2). ASSE suggested that Table 1 should
constitute compliance with the PEL because the listed controls "can be
viewed as akin to implementing all technologically feasible controls"
(Document ID 2339, pp. 8-9). BCTD commented that the focus of OSHA's
enforcement efforts should be on ensuring that employers have fully and
properly implemented the controls listed on Table 1 (Document ID 2371,
Attachment 1, p. 26).
Similarly, commenters from both industry and labor, including the
American Federation of State, County, and Municipal Employees,
Mechanical Contractors Association of America, the American Federation
of Labor and Congress of Industrial Organizations, BAC, BCTD, and
LHSFNA, also argued that exposure assessments should not be required
where employers implement control measures specified on Table 1 for
construction tasks (e.g., Document ID 2106, p. 3; 2143, pp. 2-3; 2256,
Attachment 2, p. 10; 2329, pp. 5-6; 2371, Attachment 1, pp. 6-7; 4207,
p. 2). LHSFNA stated that:
...air monitoring is less practical in construction, where the
jobsite and work is constantly changing, than in general industry
where work exposures are more stable. In construction, air
monitoring results often come back from the lab after the task has
ended and thus are of little value...(Document ID 2253, p. 2).
On the other hand, other commenters, including NIOSH, argued that
fully implementing the controls described on Table 1 would not
automatically provide a sufficient level of confidence that exposures
are adequately controlled; employers would also need to ensure that the
exposures of employees performing Table 1 tasks would not exceed the
revised PEL (e.g., Document ID 2177, Attachment B, p. 17). Mr.
Trujillo's comment emphasizing the role of safety professionals and
recommending that Table 1 be at most non-mandatory guidance was to the
same effect (Document ID 2345, p. 4).
Several commenters, including Fann Contracting, IUOE, LBA, CISC,
Charles Gordon, a retired occupational safety and health attorney, Arch
Masonry, Inc., and NUCA argued that as proposed, the alternative
compliance option would not necessarily simplify compliance for some
employers, as they would still need to do exposure assessments for a
variety of reasons, such as monitoring employees working in the
vicinity of Table 1 tasks, complying with the PEL, providing monitoring
data to controlling employers on multi-employer worksites, and
complying with the rule for tasks that are not listed on Table 1
(Document ID 2116, Attachment 1, p. 3; 2262, pp. 44-45; 2269,
pp. 21-22; 2319, p. 6; 3538, p. 16; 3580, Tr. 1473-1474;
3587, Tr. 3677-3679; 3583, Tr. 2243).
Other commenters supported the inclusion of exposure assessment
requirements for employees performing tasks on Table 1 even where
employers implement the specified engineering controls, work practices,
and respiratory protection to best protect employees in the
construction industry. The Center for Progressive Reform commented
that:
[t]he same principles that weigh in favor of a requirement to
monitor silica exposure in other industries holds for the
construction industry--monitoring gives workers, employers, OSHA,
and researchers valuable information that can be used to reduce
workplace hazards (Document ID 2351, p. 11).
The International Safety Equipment Association (ISEA) opined that
the most protective approach for employees is for employers to take air
samples of respirable crystalline silica (Document ID 2212, p. 1). AIHA
argued that there remained a need for exposure monitoring to verify
that the controls in place for Table 1 tasks actually reduce exposures
(Document ID 2169, p. 3). NIOSH recommended periodic exposure
monitoring requirements for these tasks to provide a sufficient level
of confidence that exposures are adequately controlled and that the
employers' selection of equipment, maintenance practices, and employee
training were effective (Document ID 2177, Attachment B, pp. 17, 26).
Charles Gordon proposed that when performing a Table 1 task, employers
should be required to semi-annually monitor each task and keep records
of that monitoring to ensure that workers are not exposed to high
levels of respirable crystalline silica (Document ID 3539; 3588, Tr.
3801).
After reviewing the comments on this issue, OSHA concludes that the
best approach for protecting employees exposed to respirable
crystalline silica in the construction industry is to provide a set of
effective, easy to understand, and readily implemented controls for the
common equipment and tasks that are the predominant sources of exposure
to respirable crystalline silica. OSHA is persuaded by comments and
data in the record that requiring specific engineering controls, work
practices, and respiratory protection for construction tasks, in lieu
of a performance-oriented approach involving a PEL and exposure
assessment, is justified for several reasons so long as employers fully
and properly implement the engineering controls, work practices, and
respiratory protection specified on Table 1.
First, the controls listed on Table 1 represent the feasible
controls identified in the record for each listed task, and there is
substantial evidence that demonstrates that, for most of the Table 1
tasks, exposure to respirable crystalline silica can be consistently
controlled below 50 [micro]g/m\3\ using those controls (see Chapter IV
of the Final Economic and Regulatory Flexibility Analysis (FEA)). As
such, Table 1 provides a less burdensome means of achieving protection
at least equivalent to that provided by the alternative exposure
control methods that include the 50 [micro]g/m\3\ PEL, which OSHA has
determined to be the lowest feasible exposure level that could be
achieved most of the time for most of the tasks listed on Table 1. For
example, as discussed in Section 5.7 of Chapter IV of the FEA, exposure
data demonstrates that the engineering controls and work practices
specified on Table 1 for stationary masonry saws (wet cutting)
significantly reduce employees' exposures to respirable crystalline
silica from a mean of 329 [micro]g/m\3\, when cutting masonry dry, to a
mean of 41 [micro]g/m\3\. Additionally, the record developed during the
rulemaking process has contributed greatly to the Agency's
understanding of the effectiveness of the prescribed controls. Based on
the record, OSHA is confident that exposures will be adequately
controlled using the specified methods supplemented with appropriate
respiratory protection for those few tasks that are very difficult to
control using engineering controls and work practices alone.
Second, this approach recognizes and avoids the challenges of
characterizing employee exposures to crystalline silica accurately in
many construction tasks while also ensuring that employees are
protected. In manufacturing settings and other more stable environments
subject to the general industry standard, exposure assessment can
provide an accurate depiction of the silica exposure that could be
typically expected for employees in normal operating conditions. In
general, such assessments need not be repeated frequently, costs are
therefore minimized, and the results will be timely even if there is a
delay for lab processing. In contrast, the frequent changes in
workplace conditions that are common in construction work (e.g.,
environment, location), along with potential time-lags in the exposure
assessment process, provide a compelling argument for the specified
exposure control methods approach that emphasizes clear and timely
guidance capable of protecting the employees during their shifts
instead of relying on a minimum exposure assessment requirement to
characterize employee exposures.
Third, requiring employers to implement specified dust controls
absent an additional PEL requirement simplifies compliance for
employers who fully and properly implement the engineering controls,
work practices, and respiratory protection listed on Table 1.
Simplifying compliance will also encourage employers performing tasks
listed on Table 1 to use this approach, rather than the alternative of
performing exposure assessments and implementing dust controls, as
required by paragraph (d) of the standard for construction, and thus,
will also reduce regulatory burden on construction employers of all
sizes. For this reason, OSHA expects that the vast majority of
construction employers will choose to follow Table 1 for all Table 1
tasks.
Fourth, this approach will also create greater awareness of
appropriate controls, which may in turn facilitate better
implementation and compliance, by making it far easier for employees to
understand what controls are effective for a given task and what
controls the employer must provide. Employees can locate the task they
are performing on Table 1 and immediately see what controls are
required, along with any specifications for those controls. It will,
further, be clear if an employer is not providing the correct controls
or ensuring that they are being used appropriately.
"Fully and properly" implementing the specified exposure control
methods. In order for employers to comply with paragraph (c) of the
standard for construction, they must "fully and properly" implement
the engineering controls, work practices, and respiratory protection
for each employee engaged in a task identified on Table 1. While
several commenters, including BAC and BCTD, supported this requirement
(e.g., Document ID 2329, p. 6; 2371, Attachment 1, p. 24), BCTD also
urged OSHA to clarify the meaning of "fully and properly"
implementing the specified engineering controls and work practices on
Table 1 to ensure that employers know what is required of them and how
the standard will be enforced (Document ID 4223, p. 92; 2371,
Attachment 1, p. 27-29).
Other commenters provided suggestions for what they believed should
be considered "fully and properly implementing" the controls
specified on Table 1. NIOSH recommended that OSHA provide checklists
and require a daily evaluation of engineering controls to determine
if the controls are performing as designed and to ensure that
employees using the controls are trained and have the appropriate
materials to operate the controls properly (Document ID 2177,
Attachment B, pp. 21-22). IUOE recommended that regular inspections
of engineering controls in enclosed cabs should be required
(Document ID 2262, p. 29). Anthony Bodway, Special Projects Manager
at Payne & Dolan, Inc., representing NAPA, testified that his paving
company uses a daily maintenance checklist to ensure that the controls
are functioning properly and meeting the standards set by the equipment
manufacturers (Document ID 3583, Tr. 2194-2197). AIHA suggested that
OSHA require employers to follow the manufacturer's user instructions
for installation, use, and maintenance of engineering controls, unless
there is a written variance from the manufacturer (Document ID 2169, p. 5).
Charles Gordon argued that OSHA should require a competent person to
evaluate the use of the controls specified on Table 1 initially and
periodically in order to ensure that they are fully and properly implemented
(Document ID 4236, p. 4). In general disagreement with these comments,
the National Stone, Sand, and Gravel Association (NSSGA) argued that,
while employers should conduct routine maintenance of the controls, OSHA
should not require an employer to complete an evaluation or inspection
checklist of controls or work practices at a certain frequency
(Document ID 2327, Attachment 1, p. 21).
Although the specified exposure control methods approach affords
compliance flexibility for the employer, OSHA sees value in reminding
employers and employees that this option will only be protective if
they take steps to ensure that the engineering controls, work
practices, and respiratory protection are as effective as possible.
Thus, the Agency is requiring employers to fully and properly implement
the specified engineering controls, work practices, and respiratory
protection for each employee performing a task described on Table 1 in
order to be in compliance with paragraph (c)(1) of the standard for
construction. To do otherwise would undermine the entire basis for this
compliance approach.
Merely having the specified controls present is not sufficient to
constitute "fully and properly" implementing those controls.
Employees will not be protected from exposure to respirable crystalline
silica if the specified engineering controls, work practices, and
respiratory protection are not also implemented effectively. In order
to be in compliance with paragraph (c)(1) of the standard for
construction, employers are required to ensure that the controls are
present and maintained and that employees understand the proper use of
those controls and use them accordingly.
While OSHA has decided not to further define "fully and properly"
by providing specific checklists for employers or requiring employers
to conduct inspections at set intervals, there are several readily
identifiable indicators that dust controls are or are not being fully
and properly implemented, many of which are discussed with regard to
specific equipment and tasks in Chapter IV of the FEA and in the
discussions of specific controls that appear further below in the
section. For example, for dust collection systems, the shroud or
cowling must be intact and installed in accordance with the
manufacturer's instructions; the hose connecting the tool to the vacuum
must be intact and without kinks or tight bends that would prevent the
vacuum from providing the air flow recommended by the tool
manufacturer; the filter(s) on the vacuum must be cleaned or changed as
frequently as necessary in order to ensure they remain effective (it
may be necessary to activate a back-pulse filter cleaning mechanism
several times during the course of a shift); and dust collection bags
must be emptied as frequently as necessary to avoid overfilling, which
would inhibit the vacuum system from operating effectively. For water-
based dust suppression systems, an adequate supply of water for dust
suppression must be available on site. For worksites without access to
a water main, a portable water tank or water truck having enough water
for the task must be provided. The spray nozzles must be working
properly to produce a spray pattern that applies water at the point of
dust generation and inspected at regular intervals to ensure they are
not clogged or damaged. All hoses and connections must be inspected as
necessary for leaks that could signal that an inadequate flow rate is
being delivered.
Manufacturer's instructions can also provide information about how
to fully and properly implement and maintain controls. For example, the
operator's instruction manual for EDCO concrete/asphalt saws provides a
pre-start checklist that includes information about the proper
functioning of wet-cutting equipment (Document ID 1676, p. 5). In some
cases, industry associations and employers, in collaboration with
equipment manufacturers, have also developed best practices with regard
to the full and proper implementation of engineering controls, work
practices, and respiratory protection for their particular industry or
operation. For example, NAPA and the Association of Equipment
Manufacturers (AEM) provided operational guidance for water systems
during milling operations that includes pre-operation inspection
activities, preparations for safe operation, and other operation
considerations (Document ID 2181, p. 52).
In addition, paragraph (g) of the standard for construction
requires employers to establish and implement a written exposure
control plan, which includes provisions for a competent person to make
frequent and regular inspection of job sites, materials, and equipment
in order to implement the plan (see the summary and explanation of
Written Exposure Control Plan for discussion about this requirement).
Thus, the requirement for a written exposure control plan and the
competent person, which was added to the final standard for
construction, provides additional safeguards for ensuring that
employers fully and properly implement Table 1.
OSHA expects that in most instances it will be straightforward for
a designated competent person to identify whether the controls have
been fully and properly implemented. For example, a significant amount
of visible dust being frequently or continuously emitted from the
material being worked on can serve as an indication that controls are
not fully and properly implemented. A small amount of dust can be
expected even with new equipment that is operating as intended by the
manufacturer. The amount of visible dust associated with the new dust
controls should be noted when equipment is put into service and checked
periodically. A noticeable increase in dust emissions would indicate
that the dust control system is not operating as intended.
Employees engaged in Table 1 tasks. Commenters expressed concerns
about the lack of requirements in the proposed rule to protect
employees assisting with Table 1 tasks or working in the vicinity of
others engaged in Table 1 tasks (e.g., Document ID 2116, Attachment 1,
pp. 2-3). In response, OSHA has clarified the language in paragraph
(c)(1) of the standard for construction to encompass all employees
"engaged in a task identified on Table 1." This phrasing is intended
to include not only the equipment operator, but also laborers and other
employees who are assisting with the task or have some responsibility
for the completion of the task, even if they are not directly operating
the equipment. For example, where an employee is assisting another
employee operating a walk-behind saw indoors by guiding the saw and
making sure that the cutting is precise, that employee would be
considered to be engaged in the task and would need to wear a respirator.
Similarly, employees assisting a jackhammer task would be considered to
be engaged in the task and would also be required to wear a respirator
if they engaged in the task outdoors for more than four hours in a
work shift.
It is not OSHA's intent, however, for all employees who are in the
vicinity of a listed task to be considered "engaged in the task." To
protect the other employees in the vicinity of a listed task, the
employer must account for the potential exposures of these employees to
respirable crystalline silica as part of its written exposure control
plan. As discussed in the summary and explanation of Written Exposure
Control Plan, paragraph (g)(1)(iv) of the standard for construction
requires a description of the procedures used to restrict access to
work areas, when necessary, to limit the number of employees exposed
and their exposure levels. Employers must develop procedures to
restrict or limit access when employees in the vicinity of silica-
generating tasks are exposed to excessive respirable crystalline silica
levels. Such a situation might occur in a variety of circumstances,
including when an employee who is not engaged in the task, but is
working in the vicinity of another employee performing a Table 1 task
requiring respiratory protection, is exposed to clearly visible dust
emissions (e.g., an employee directing traffic around another employee
jackhammering for more than four hours in a shift). In that case, the
competent person, as required under paragraph (g)(4) of the standard
for construction, would assess the situation in accordance with the
employer's procedures to determine if it presents a recognized hazard,
and if it does, take immediate and effective steps to protect employees
by implementing the procedures described in the written exposure
control plan. For the above example, this could include positioning the
employee directing traffic at a safe distance upwind from the dust-
generating activity.
Table 1. As discussed above, paragraph (c)(1) of the standard for
construction includes "Table 1: Specified Exposure Control Methods
When Working With Materials Containing Crystalline Silica," which
identifies 18 common construction equipment/tasks known to generate
high exposures to respirable crystalline silica. For each equipment/
task identified, Table 1 specifies appropriate and effective
engineering and work practice control methods. Some entries contain
multiple engineering controls and work practices. In those instances,
OSHA has determined that the specified combination of engineering
controls and work practices is necessary for reducing exposures and
requires employers to implement all of the listed engineering controls
and work practices in order to be in compliance. Some entries contain
multiple compliance options denoted with an "OR" (e.g., (c)(1)(ix),
(c)(1)(x), (c)(1)(xii), (c)(1)(xiii), (c)(1)(xv), and (c)(1)(xviii) of
the standard for construction). For those entries, OSHA has determined
that more than one control strategy could effectively reduce exposures
and permits the employer to decide which option could be best
implemented on the worksite. Table 1 also specifies respiratory
protection for those entries where OSHA has determined from its
analysis of technological feasibility it is needed to ensure employees
are protected from exposures to respirable crystalline silica. These
respirator requirements are divided by task duration (i.e., "less than
or equal to four-hours-per-shift" and "greater than four-hours-per-
shift").
Table 1 in the final standard differs from Table 1 in the proposed
standard in a number of respects. As proposed, "Table 1--Exposure
Control Methods for Selected Construction Operations," listed 13
construction operations that expose employees to respirable crystalline
silica, as well as control strategies and respiratory protection that
reduce those exposures. In developing Table 1 for the proposed
standard, OSHA reviewed the industrial hygiene literature across the
full range of construction activities and focused on tasks where
silica-containing materials were most likely to be fractured or abraded
and where control measures existed to offer protection against a
variety of working conditions. OSHA also included additional
specifications on proposed Table 1 to ensure that the strategies listed
were properly implemented and remained effective.
Table 1 was the subject of many comments in the rulemaking record.
Commenters, such as BCTD, urged OSHA to reconsider its use of the
proposed term "operation" to describe the activities listed on Table
1 (Document ID 2371, Attachment 1, p. 23). Kellie Vazquez, on behalf of
Holes Incorporated and CISC, suggested that it would be helpful to
include more specifically-defined tasks, rather than broader operations
(Document ID 2320, pp. 8-9). In the same vein, BCTD suggested that OSHA
"revise [Table 1] to make clear that its focus is on particular silica
dust-generating tasks, not more broadly-defined operations" as "there
is an important distinction between specific tasks that may generate
silica dust and the employer's overall operation, which may include
different silica dust-generating tasks, requiring different controls"
(Document ID 2371, Attachment 1, p. 23). BCTD also recommended that, to
avoid confusion, Table 1 should specify that each task is being
performed on or with a material that contains silica (Document ID 2371,
Attachment 1, p. 24). Responding to both suggestions, OSHA has changed
the terminology used in Table 1 from "Operation" to "Equipment/
Task" to clarify that the controls apply to silica-generating
activities done by employees and silica exposure generated by
equipment, and has revised the title of Table 1 accordingly to
"Specified Exposure Control Methods When Working with Materials
Containing Crystalline Silica."
Other commenters requested that OSHA include additional activities
on Table 1. The Sheet Metal Air Conditioning Contractors National
Association (SMACNA) commented that using powder-actuated tools should
be added (Document ID 2226, p. 2), and the Interlocking Concrete
Pavement Institute (ICPI) suggested that OSHA include compacting
pavers, sweeping sand into paver joints, and compacting the aggregate
base (Document ID 2246, pp. 2, 11). NAHB noted that Table 1 failed to
cover hand-mixing concrete (Document ID 2334, p. 4). OSHA did not
receive data showing that employees engaged in many of these additional
minor tasks (pulling concrete forms, mixing concrete for post holes,
etc.) experience significant routine exposure to respirable crystalline
silica above the action level that would require their employers to
comply with provisions of this rule. Because OSHA does not currently
have data indicating that additional controls for these tasks would be
needed on a regular basis or would be effective, it has determined not
to include them on Table 1.
OSHA recognizes the possibility that employers may later discover
that there are tasks that are not covered by Table 1 where they may
have difficulty meeting the PEL. If such cases arise, OSHA can address
them in several ways, including: considering technological or economic
infeasibility defenses, and applying its variance process--either
temporary or permanent, pursuant to which an employer can apply to
exclude an industry or process from enforcement of the standard based
principally on a showing that it is providing equivalent protection
for its workers.
Several commenters requested that OSHA add tasks or activities and
equipment to Table 1 that are associated with general industry
operations such as asphalt plant operations, shale gas fracturing, and
artificial stone and granite countertop work (Document ID 2212, p. 2;
2116, Attachment 1, p. 28; 2244, p. 4). OSHA is not including these in
the construction standard for the reasons discussed in the summary and
explanation of Scope.
NUCA requested that OSHA add underground construction, specifically
excavation, onto Table 1, stating:
The nature of excavation underground construction is
continuously mobile. Exposure assessments take time to evaluate by a
lab, and in that time, the jobsite conditions will change or crews
will move to other sites. Test results simply could not be available
in enough time to be relevant to a particular jobsite. This not only
makes costly lab assessments irrelevant to particular sites, it also
does nothing to protect the workers on those sites (Document ID
2171, p. 2).
OSHA's technological feasibility analysis for underground
operations (Section 5.12 of Chapter IV of the FEA) indicates that
employees performing activities not specific to tunneling, such as
grinding, hole drilling, or chipping, receive similar exposures from
their equipment as employees performing those same activities
aboveground in enclosed environments (e.g., indoors). As a result,
employers can comply with the dust control requirements of the standard
by fully and properly implementing the dust controls specified on Table
1 of the final standard for construction for those tasks. However, as
explained in the technological feasibility analysis cited above, OSHA
determined that it was not possible to develop a clear control
specification that would prove effective for most situations where
tunnel boring machines, road headers, and similar kinds of equipment
are used. Effective dust control for operations that use these kinds of
equipment consists of a combination of water sprays at the tunnel face
and along the conveyors that remove material from the face, general
dilution ventilation through the tunnel, local exhaust ventilation for
excavating equipment and conveyor transfer points, and enclosed cabs
for the operators. Dust control may also require enclosures for
conveyors and belt cleaning mechanisms. Designing effective and
efficient dust control systems must take into account specific factors
of the tunnel project and equipment being used, and are analogous to
dust control strategies used in underground mines, as described in
NIOSH's Handbook for Dust Control in Mining (Document ID 0887). Given
the degree of complexity and project-specific considerations that
should be taken into account, OSHA determined that it was not possible
to devise an effective specification applicable to all tunnel projects
and thus has not added an entry for tunnel boring in underground
construction to Table 1.
Likewise, although abrasive blasting is a common source of silica
exposure in construction, OSHA does not include an entry for abrasive
blasting on Table 1 for reasons explained more fully below. As
described in the Introduction to Chapter IV of the FEA, the tasks
included on Table 1 of the final rule are those that have been widely
recognized as high-exposure tasks in construction, and for which there
has been considerable research performed on the effectiveness of dust
control strategies. The record indicates that the tasks reflected in
Table 1, with few exceptions such as underground construction and
abrasive blasting, are the tasks that employers will most frequently
need to address to ensure employee protection from crystalline silica
hazards. For tasks not included on Table 1 that foreseeably generate
silica exposures above the action level, construction employers will,
in accordance with paragraph (d) of the standard for construction, need
to conduct an exposure assessment and maintain exposures at or below
the PEL through use of the traditional hierarchy of controls.
Commenters also weighed in on OSHA's general approach to selecting
the engineering controls and work practices for each task. LBA argued
that there was a disconnect between the feasibility evidence and the
controls and work practices included on Table 1 (Document ID 2269, p.
17). NAHB urged OSHA to ensure that the protection methods included on
Table 1 are based on verifiable studies that show effective solutions
(Document ID 2296, p. 28). BCTD also opined that only "control
measures supported by good quality evidence should be listed on Table
1" (Document ID 2371, Attachment 1, p. 24).
OSHA agrees that the engineering controls, work practices, and
respiratory protection specified on Table 1 need to be consistent with
the evidence presented in its technological feasibility analyses (see
Chapter IV of the FEA). To that end, OSHA has based the specifications
on Table 1 on extensive exposure data collected from a variety of
sources including NIOSH reports, data submitted to the record, OSHA's
compliance case files, and published literature.
Requirements for water delivery systems and dust collection
systems. OSHA is requiring the use of an integrated water delivery
system supplied by the equipment manufacturer for several types of
equipment listed on Table 1: Stationary masonry saws; handheld power
saws (any blade diameter); walk-behind saws; drivable saws; rig-mounted
core saws or drills; handheld grinders for uses other than mortar
removal; and walk-behind milling machines and floor grinders. OSHA is
requiring the use of systems that are developed in conjunction with the
tool because they are more likely to control dust emissions effectively
by applying water at the appropriate dust emission points based on tool
configuration and not interfere with other tool components or safety
devices.
CISC commented that the requirement for an integrated water system
limited options for employers and may reduce the use of the table,
stating "...if a construction employer finds a way to effectively
deliver water through another mechanism, in the CISC's view that should
be encouraged" (Document ID 2319, p. 103; 2320, p. 16). OSHA expects
that most employers will use integrated water systems, as provided by
manufacturers, and will follow Table 1 but its intent is not to
prohibit the use of other dust suppression methods during cutting.
Employers may implement other controls or wet method configurations if
they determine that the alternative control is more appropriate for
their intended use. However, employers who choose to use controls not
listed on Table 1 will be required to conduct exposure assessments and
comply with the PEL in accordance with paragraph (d) of the standard
for construction.
CISC also questioned the appropriateness of requiring an integrated
water delivery system when most integrated systems are intended to keep
the blade cool and are not designed for dust suppression (Document ID
2319, p. 103; 2320, p. 16). In written testimony, Rashod Johnson of the
Mason Contractors Association of America stated that
the vast majority of masonry saws provide water on the blade itself.
This is solely for the purpose of keeping the blade cool during
cutting. A side effect, just happens to be dust suppression. Now,
manufacturers of these saws are starting to explicitly state that
the water used is for cooling the blade only and should not be used
to suppress dust (Document ID 2286, p. 2).
However, product literature from five major saw manufacturers
(Andreas Stihl, Husqvarna, Hilti, Makita USA, and Wacker Group)
highlights the use of water application equipment to suppress dust in
addition to blade cooling (Document ID 3998, Attachment 12a, pp. 9, 15-
16; 3998, Attachment 12e, p. 3; 3998, Attachment 12f; 3998, Attachment
12g, p. 5; 3998, Attachment 12h, p. 8). For example, Stihl's manual for
the model 410 and 420 cut-off machines (handheld masonry saws)
specifically recommends a water flow rate for dust suppression
(Document ID 3998, Attachment 12a, pp. 9, 15-16). Furthermore, Stihl is
not the only cut-off saw manufacturer to state that water used with its
product is intended to suppress dust emissions. Husqvarna's product
literature for the K 3000 Wet describes the product as a power cutter
for wet applications that is equipped with a dust extinguisher system
(Document ID 3998, Attachment 12f, p. 1). Hilti also recognizes that
water suppresses dust and recommends the use of wet cutting to reduce
dust in its instruction manual for the Hilti DSH 700/DSH 900 model
handheld masonry saws (Document ID 3998, Attachment 12e, p. 3).
CISC asked that OSHA clarify whether there needs to be a separate
integrated water delivery system in addition to the system provided by
the manufacturer to keep the blade cool (Document ID 2319, p. 104).
Beamer et al. (2005) conducted experiments to observe the differences
in the various wet cutting methods available and found that the
greatest improvement in dust reduction occurred with freely flowing
water applied at a rate of 48 gallons per hour (0.8 gallons per
minute), resulting in dust reduction of about 93 percent and confirming
the benefits of water flowing over the stationary saw cutting blade
compared with other misting systems (Document ID 1555, p. 509). That,
in addition to the manufacturer information submitted to the record,
indicates that the existing water systems for blade cooling are
effective at respirable dust capture and will satisfy the requirements
under paragraphs (c)(1)(i) through (c)(1)(xviii) of the standard for
construction where integrated water systems are required. Therefore,
OSHA has determined that, where water-based dust suppression can be
used with tools and equipment, those that are equipped with an
integrated water delivery system are effective and the best available
technology for controlling respirable crystalline silica. A separate
integrated water delivery system in addition to the system provided by
the manufacturer to keep the blade cool is not required.
OSHA is requiring the use of a commercially available dust
collection system (i.e., local exhaust ventilation (LEV)) for several
types of equipment listed on Table 1, including: handheld power saws
for fiber cement board (with a blade diameter of 8 inches or less),
handheld and stand-mounted drills (including impact and rotary hammer
drills), jackhammers and handheld power chipping tools (as an
alternative to a water delivery system), handheld grinders for mortar
removal, and handheld grinders for uses other than mortar removal (as
an alternative to a water delivery system). OSHA's intent is to ensure
that employers use equipment that is appropriately designed for the
tool being used and that will be effective in capturing dust generated
from using the tool.
CISC opposed OSHA's requirement for commercially available systems,
stating "[t]his specification eliminates specialty manufactured
products that may be equally effective" (Document ID 2320, p. 11).
However, CISC did not provide examples or describe what is meant by
"specialty manufactured products." It is not OSHA's intent to prevent
employers from using products that are custom made by aftermarket
manufacturers (i.e., made by someone other than the original tool
manufacturer) which are intended to fit the make and model of the tool
and designed to meet the particular needs and specifications of the
employer purchasing the product. These systems are designed to work
effectively with the equipment and not introduce new hazards such as
obstructing or interfering with safety mechanisms. The "commercially
available" limitation is meant only to eliminate do-it-yourself on-
site improvisations by the employer. An employer is free to improvise
and use controls that are not commercially available. However, those
systems would not meet the requirements of Table 1 and the employer
will be required to conduct exposure assessments and comply with the
PEL in accordance with paragraph (d) of the standard for construction.
In Table 1 of the proposed rule, OSHA would have required dust
collection systems be equipped with High-Efficiency Particulate Air
(HEPA) filters, which are 99.97 percent efficient in capturing
particles having an aerodynamic diameter of 0.3 [mu]m or larger. In the
final standard, OSHA is not requiring the use of HEPA filters and
instead is requiring the use of filters with a capture efficiency of 99
percent or greater for respirable particulate. Although OSHA received
comments and testimony in support of using HEPA filters to capture
silica dust (Document ID 1953, pp. 3-4; 1973, pp. 2-3), extensive
comments were submitted to the record expressing concern regarding this
requirement.
Occupational and Environmental Health Consulting Services, Inc.
(OEHCS) noted the numerous deficiencies found with HEPA filtration from
ineffective seals, deterioration of the filter, and inadequate testing
prior to use, which often results in employee exposure to potentially-
hazardous particles and possible recontamination of the work
environment (Document ID 1953, Attachment 1). The Precast/Prestressed
Concrete Institute (PCI), NUCA, and LBA noted that HEPA filters do not
work well in the construction environment because filters will clog up
quickly and must be changed often (Document ID 2276, p. 10; 3729, p. 3;
2269, p. 23). CISC noted that HEPA filters will typically not last an
entire shift, stating that they clog up quickly and need to be
monitored and changed frequently (Document ID 2320, p. 114).
Consequently, CISC asserted, HEPA filters are not effective at
filtering respirable dust or at reducing exposures to respirable silica
(Document ID 2319, p. 95).
OSHA reached the same conclusion in its technological feasibility
finding for mortar and concrete grinding as well (see Section 5.11 of
Chapter IV of the FEA). Finding that best practices may counsel toward
the use of HEPA-rated filters in the case of grinding, and particularly
mortar grinding, OSHA nonetheless determined that under field
conditions HEPA filters may rapidly clog, leading to an increase in
static pressure drop and loss of the airflow needed for LEV to
effectively capture silica dust at the point of generation (Document ID
0731, pp. 375, 384).
OSHA is persuaded that it should not require that dust collection
systems be equipped with HEPA filters because HEPA filters in some
applications will result in loss of airflow and concomitant degradation
of dust-capture efficiency. In examining manufacturers' specifications
for many commercially-available dust collectors, OSHA finds that most
offer, in addition to HEPA filters, other filters with a 99 percent
efficiency or better in the respirable-particle-size range. Many
examples of products equipped with filters that do not meet HEPA
specifications but nevertheless meet the requirement for 99 percent
efficiency in the respirable-particle-size range were submitted to the
record and include the EDCO Vortex 2000 (captures 99 percent of 0.5
[micro]m or larger particles) (Document ID 4073, Attachment 4a, Row
55), the iQ 360x stationary saw (99.5 percent, particle size
unspecified) (Document ID 4073, Attachment 4a, Row 58), a Porter-Cable
vacuum (99.85 percent, particle size unspecified) (Document ID 3998,
Attachment 13p), the Bosch 3931A (99.93 percent of 3 [micro]m
particles) (Document ID 3998, Attachment 10, p. 29), the CS Unitec
(99.93 percent of 0.3 [micro]m particles) (Document ID 4073, Attachment
4a, Row 99), and the Dustless 16-gallon collector ("almost HEPA,"
filters to 0.5 [micro]m particles) (Document ID 4073, Attachment 4a,
Row 211). A filter efficiency of at least 99 percent allows for longer
tool usage, compared to one with a HEPA filter, before significant
drops in airflow of the dust collection system. Furthermore, as
explained above, requiring that dust collectors be equipped with HEPA
filters can cause rapid airflow drop, reducing dust capture efficiency
at the shroud or hood and exposing employees to high respirable dust
and silica concentrations. Therefore, OSHA has decided not to require
HEPA filters on Table 1 for dust collection systems and instead
requires that dust collectors have a filter with 99 percent or greater
particle capture efficiency. Employers should consult with their
suppliers to determine the dust collection equipment that will best
suit their needs for a given application.
OSHA also received many specific comments about particular changes
to the notes and additional specifications, associated with the entries
on Table 1, and on the specified engineering and work practice control
methods identified for each entry, which are further discussed later in
this section.
Notes and additional specifications on Table 1. Several commenters
responded to the appropriateness of including the notes and additional
specifications in the individual entries on Table 1. OSHA included
these in the proposed rule to ensure that the strategies listed were
properly implemented and remained effective.
Some commenters stated that the notes were too detailed, while
others argued that the notes were not detailed enough (Document ID
2319, p. 6; 2262, p. 29; 3581, Tr. 1631-1632; 3585, Tr. 2924-2925,
3052-3053; 4223, pp. 95-97). Several commenters expressed concern that
certain notes were unrealistic or too confusing for an employer to
comply with. CISC stated that the inclusion of the notes left Table 1
"unworkable" for most employers in the construction industry
(Document 2319, p. 6). Others questioned whether these additional
specifications were a mandatory component of Table 1 or simply
suggested guidelines to help determine the efficacy of the control
(Document ID 2296, p. 28; 3441, pp. 4-5). On the other hand, some
commenters asserted that the additional specifications were needed on
Table 1 to ensure that controls are properly operated and effective
(Document ID 3589, Tr. 4286-4287; 3581, Tr. 1631-1632; 4223, pp. 95-
97).
To balance the need to clarify how the specifications apply to make
Table 1 workable with the need to provide more specific information
about the controls in order to ensure that they are effective, OSHA has
removed most of the notes and additional specifications from the
individual entries on Table 1 and has instead included revised
specifications for the controls in paragraph (c)(2) of the standard for
construction. This approach has the added benefit of making Table 1
more readable because specifications that apply to multiple rows can
now be addressed in a single subparagraph.
Paragraph (c)(2)(i) of the standard for construction requires
employers to provide a means of exhaust as needed to minimize the
accumulation of visible airborne dust for tasks performed indoors or in
enclosed areas. When tasks are performed indoors or in enclosed areas,
the dispersal of dust can be impeded such that concentrations can build
up without the aid of forced ventilation. Flanagan et al. (2006)
concluded that the degree to which a work area is enclosed is an
important determinant of employee exposure based on data demonstrating
increased exposures to respirable crystalline silica for enclosed
environments (those with two to four walls, as well as those having
walls, a roof, and windows), as compared to outdoor environments
(Document ID 0677, pp. 148-149). Increased exposures to respirable
crystalline silica were also demonstrated for tasks listed on Table 1
in enclosed areas, such as jackhammering inside a large pool area
(Document ID 3958, Rows 1064, 1065, 1066) and handheld sawing in a
large garage building open in front and closed on three sides (Document
ID 3777, p. 65).
Sufficient air circulation in enclosed or indoor environments is
important to ensure the effectiveness of the control strategies
included on Table 1 and to prevent the accumulation of airborne dust.
The "means of exhaust" necessary to minimize the accumulation of
visible airborne dust could include dilution ventilation through the
use of portable fans that increase air movement and assist in the
removal and dispersion of airborne dust, which would otherwise remain
in the enclosure and contribute to elevated exposures. To be effective,
the ventilation must be implemented so that movements of employees, or
the opening of doors and windows, will not adversely affect the
airflow.
Paragraph (c)(2)(ii) of the standard for construction requires
employers, for tasks performed using wet methods, to apply water at
flow rates sufficient to minimize release of visible dust generated by
the task. BCTD and LHSFNA encouraged OSHA to specify minimum flow rates
for water where there are data or studies to support such a
recommendation (Document ID 3581, Tr. 1632; 3589, Tr. 4286-4287). NIOSH
recommended a flow rate of 0.5 L/min for handheld power saws based on
experimental data and recommended that OSHA specify a minimum water
flow rate of 300 mL/minute for jackhammers based on a field study of
control equipment fabricated specifically for the study (Document ID
2177, Attachment B, pp. 19, 33; 0867, p. 6). Water has been proven an
efficient engineering control method to reduce exposures to airborne
crystalline silica-containing dust. Adequate dust capture is dependent
on a variety of factors such as dust particle size, velocity, spray
nozzle size and location, use of surfactants or other binders, and
environmental factors (water hardness, humidity, weather, etc.) that
must be considered when implementing wet methods. Water flow rates
suggested by various studies, while perhaps instructive, may not be
applicable to all of the different types of equipment that could be
used or the conditions that may be encountered by employers following
Table 1. Because the appropriate water flow rates for controlling
silica dust emissions can vary, OSHA is not establishing a required
flow rate for wet suppression systems or specifying a flow rate for
individual Table 1 entries.
Paragraphs (c)(2)(iii)(A)-(F) of the standard for construction
require employers implementing measures that include an enclosed cab or
booth to ensure that the enclosed cab or booth is maintained as free as
practicable from settled dust, has door seals and closing mechanisms
that work properly, has gaskets and seals that are in good condition
and work properly, is under positive pressure maintained through
continuous delivery of fresh air, has intake air that is filtered
through a pre-filter that is 95 percent efficient in the 0.3-10.0
[micro]m range (e.g., MERV-16 or better), and has heating and
cooling capabilities.
Dust can be unintentionally carried into enclosed cabs or booths
through a number of routes, including on employees' boots, during the
opening of doors when accessing or exiting the cab, through leaks in
the system, or when employees roll down windows. IUOE, recommending
that OSHA add specificity to the cab requirements (e.g., heating and
air conditioning, housekeeping), argued that without greater
specificity "there is a grave danger that intended safeguards become
counterproductive as dust is re-circulated within the enclosures"
(Document ID 2262, pp. 29-33).
Direct-reading instruments show that fine particle (0.3 micron
([mu]m) in size) concentrations inside operator cabs can be reduced by
an average of 93 percent when cabs are clean, sealed, and have a
functionally adequate filtration and pressurization system (Document ID
1563, p. 1). Cecala et al. (2005) studied modifications designed to
lower respirable dust levels in an enclosed cab on a 20-year-old
surface drill at a silica sand operation. The study found that
effective filtration and cab integrity (e.g., new gaskets, sealed
cracks to maintain a positive-pressure environment) are the two key
components necessary for dust control in an enclosed cab (Document ID
1563, p. 1).
OSHA determined that the requirements specified in paragraphs
(c)(2)(iii)(A)-(F) of the standard for construction reduce the
likelihood of respirable crystalline silica exposure in enclosed cabs
or booths when employees are present by lowering the potential for dust
to be re-suspended inside the enclosure, promoting the ability of the
enclosed cab or booth to keep dust from entering through cracks or
openings (e.g., seals, gaskets, and closing mechanisms are present, in
good condition, and work properly), ensuring that the working
conditions in the cab are comfortable so that employees are less likely
to open the window of the cab, and ensuring that the fresh air provided
to the employee does not contain silica particles.
IUOE also suggested that OSHA require employers to provide boot
brushes or mudflingers to minimize the dust brought into the cab, to
equip cabs with dust-resistant materials, and to affix warning labels
to the interior of the cab (Document ID 2262, p. 30; 4025, p. 17). The
Agency has not included these additional requirements since it expects
that the specifications in paragraphs (c)(2)(iii)(A)-(F) of the
standard for construction combined with frequent inspections by the
competent person will be sufficient to protect employees against the
potential respirable crystalline silica exposures within the enclosure.
OSHA has not included more specific requirements in paragraphs
(c)(2)(i)-(c)(2)(iii) of the standard for construction (e.g.,
establishing a minimum face velocity, volumetric flow rate for air
movement, or a required number of air changes; flow rate for wet
suppression systems; or a frequency for the cleaning of cabs or
booths). However, as discussed in the summary and explanation of
Written Exposure Control Plan, paragraph (g)(1)(ii) of the standard for
construction requires the employer to establish and implement a written
exposure control plan that describes the engineering controls and work
practices used to limit employee exposure to respirable crystalline
silica. This description should include details such as the appropriate
means of exhaust needed to minimize the accumulation of visible
airborne dust for a particular task, the appropriate flow rate and
droplet size needed for wet suppression systems to minimize release of
visible dust, and the procedures for maintaining and cleaning an
enclosed cab or booth. Paragraph (g)(4) of the standard for
construction also requires a competent person to make frequent and
regular inspections of the jobsite, materials, and equipment (including
engineering controls) to implement the written exposure control plan.
OSHA did not include specifications on visible dust and wet slurry,
included as notes in individual entries on proposed Table 1, in the
standard. The Agency has determined that these issues are best
addressed by other provisions of the standard, rather than as a note or
additional specification included in each relevant Table 1 entry.
Further discussion about these specifications is also included below.
Many commenters expressed concern with the note, contained in
proposed Table 1 for all but two entries, requiring employers to
operate equipment such that no visible dust is emitted from the
process. Industry commenters, including the Power Tool Institute (PTI),
Western Construction Group, SMACNA, the Independent Electrical
Contractors, the Distribution Contractors Association, CISC, the
Utility and Transportation Contractors Association of New Jersey,
Atlantic Concrete Cutting, ABC, LBA, Holes Incorporated, and N.S. Giles
Foundations objected to this note, stating that it was an unrealistic
requirement which made Table 1 unworkable (e.g., Document ID 1973, pp.
2-9; 2183, p. 3; 2226, p. 2; 2250, p. 2; 2309, p. 4; 2319, pp. 97-98;
4217, p. 6; 2356, p. 2; 2367, p. 2; 2289, p. 7; 2269, p. 21; 3441, p.
5; 3598, pp. 1-2).
Some industry commenters asserted that it is impossible to perform
tasks, such as sawing, grinding, and drilling, without generating any
visible dust (Document ID 2357, pp. 27-28; 3441, p. 6; 4073, Attachment
9e, p. 1). Holes Incorporated noted that when grinding or using other
hand-held pieces of equipment, the work cannot be performed with the
tool flush against the impacted surface, and at times, there will be a
gap and visible dust will be emitted even when local exhaust
ventilation or wet methods are utilized (Document ID 3441, p. 6).
Other commenters expressed concern that there is no true dustless
system, clarifying that even those tools marketed as "dustless"
produce some level of airborne dust (Document ID 2345, p. 4; 3585, Tr.
2960; 4216, pp. 2-3). Francisco Trujillo, safety director for Miller
and Long, stated that:
Every "dustless" system I have ever witnessed has produced
some level of airborne dust. This fact alone should show that Table
1 sets criteria that are impossible to achieve...(Document ID
2345, p. 4).
On the other hand, commenters, including NAPA and BAC, noted that
in their experience there is no visible dust generated when certain
equipment, such as asphalt machines for milling or stationary masonry
saws, is used with available dust controls (Document ID 3583, Tr. 2216;
3585, Tr. 3072). They did not, however, provide any indication that the
same results could be achieved with all of the other equipment listed
on Table 1.
Several commenters provided a different rationale for their
objections to this note. AIHA opined that the requirement to operate
equipment such that no visible dust is emitted from the process is a
subjective determination and recommended it be removed from Table 1
entries (Document ID 3578, Tr. 1029-1030; 2169, p. 5). The Masonry and
Concrete Saw Manufacturers Institute (SMI) noted that "[a]dding
requirements for...avoiding visible dust have not been researched
specific to respirable silica dust and may have no beneficial impact"
(Document ID 2316, p. 2). NAHB and Holes Incorporated expressed concern
that the requirement was a general dust rule, rather than regulating
crystalline silica since Table 1 doesn't specify whether "no visible
dust" refers to visible silica dust or just dust in general (Document
ID 2296, p. 29; 3580, Tr. 1355-1356).
Not all industry commenters objected to the note on visible dust
contained in the proposed Table 1. ICPI supported a version of Table 1
that included the no-visible-dust requirement for nearly all of the
operations listed (Document ID 2352, pp. 4-8).
Commenters from both industry and labor suggested revisions to
clarify the note and make it workable. LHSFNA believed the note was
needed to ensure the effective use of controls and was not too vague,
but acknowledged that the language could be clarified to say something
like "visible dust should be minimized" (Document ID 4207, p. 2).
BCTD also provided significantly revised language for the no-visible-
dust requirement. For those operations that involve cutting and
grinding on silica-containing substrate, BCTD suggested that, for wet
systems, Table 1 of the standard should require that water flow be
"sufficient to control the dust generated so that no visible dust . .
. is emitted from the process once the blade has entered the substrate
being cut" and that the relevant note on Table 1 be revised to read:
A small amount of visible dust may be present when the blade or
tool initially enters the substrate and when it is being removed at
the end of a task. However, if visible dust is present after the
blade or tool has entered the work surface/substrate, this is a sign
that the control is not working properly. The operation should be
stopped and the equipment and/or workers' cutting technique checked
and fixed (Document ID 4223, Appendix 1, p. 14).
PTI's suggested revisions to Table 1 include a note for many of the
entries specifying that "during operation, if excessive visible dust
is emitted from the process, immediately stop work and verify that the
dust control system is functioning properly" (Document ID 1973, pp. 2-
9).
While opinions varied widely on the utility of a no-visible-dust
requirement, no commenters suggested that excessive visible dust
generated from tasks abrading silica-containing materials (sawing,
grinding, etc.) does not present a risk of significant employee
exposure to silica. As noted above, BCTD confirmed that the presence of
visible dust after the blade or tool has entered the work surface/
substrate is a sign that the control method is not working properly
(Document ID 4223, Appendix 1, p. 14). PTI recommended that, when
excessive visible dust was present, work stop immediately until the
employer could verify the proper functioning of the control (Document
ID 1973, pp. 2-9).
OSHA agrees that excessive visible dust is an indication that a
control's effectiveness may be compromised, but, after reviewing the
entire record on this point, has decided not to include a no-visible-
dust requirement for the Table 1 entries. Instead, it has concluded
that the purpose of such a requirement is best achieved by bolstering
other requirements in the rule, as it applies to construction. First,
OSHA considers the written exposure control plan to be centrally
important and expects employers to address signs that controls may not
be working effectively (e.g., dust is visible) as part of their written
exposure control plans required under paragraph (g) of the standard for
construction (see summary and explanation of Written Exposure Control
Plan for further discussion). Second, during the designated competent
person's frequent and regular inspections of job sites, materials, and
equipment to implement the written exposure control plan, as required
under paragraph (g)(4) of the standard for construction, OSHA expects
that person to make routine observations of dust generated from tasks
being conducted. Where increases in visible dust occur, the competent
person's assigned role is to take prompt corrective action (e.g., make
corrections or adjustments as needed).
OSHA finds that the difference between the small amount of dust
generated when control measures are operated effectively and the large
amount of dust generated during tasks when control measures are not
used or not operated effectively can readily be observed. Several
videos presented in the record support this conclusion (e.g., Document
ID 4073, Attachment 4b). These videos demonstrate that when a task is
uncontrolled or inadequately controlled, a large dust plume can be
seen. When controls such as water or vacuum-based ventilation are used,
little dust is observable. These significant differences in the
observable dust generated during controlled and inadequately-controlled
tasks provide an opportunity for employers to readily detect poorly-
performing equipment and address these problems quickly. The principle
concern, however, is with a lot of visible dust, rather than any
visible dust, which is a concern for which the appropriate corrective
action is difficult to quantify or state in objective terms. Instead,
the presence of significant visible dust lends itself to a more
process-oriented control approach, as exemplified by the written
exposure control plan and competent person requirements. OSHA thus
concludes that the issue of visible dust is best addressed by the
requirement to fully and properly implement the controls specified on
Table 1, and the written exposure control plan and competent person
requirements, rather than as a note or additional specification
included in each Table 1 entry.
Commenters also objected to the specification to prevent wet slurry
from accumulating and drying when implementing wet methods, as proposed
for several Table 1 entries. Both Holes Incorporated and NAHB objected
to the ambiguity of the requirement and presented concerns about how
employers on a construction site would comply with such a requirement
(Document ID 3441, p. 9; 2296, p. 28).
Other commenters expressed concern regarding the disposal of silica
slurry (Document ID 2246, pp. 9-10; 3585, Tr. 2886; 2319, p. 94). ICPI
noted that employers have to expend extra effort to locate a place to
dispose of dust-filled slurry, which is not possible in some conditions
or locations (Document ID 2246, pp. 9-10). CISC described how slurry
created using wet-cutting methods outside can flow into storm drains,
potentially violating environmental regulations (Document ID 2319, p.
94). The Mason Contractors Association of America explained that in
California, silica slurry produced from wet cutting is classified as a
hazardous material, requiring contractors working in the state to
follow hazmat procedures for its disposal (Document ID 3585, Tr. 2886).
However, NIOSH argued that since the vast majority of masonry saws
provide water on the blade itself to cool and lubricate the blade and
suppress dust, employers already have to deal with slurry when cutting
masonry and concrete (Document ID 4233, Attachment 1, p. 6). OSHA
agrees that the standard does not pose any new requirements regarding
the disposal of slurry on employers who already use wet methods for
sawing masonry products.
OSHA concludes that any measures necessary to manage slurry in
order limit employee exposure to respirable crystalline silica (i.e.,
exposure that results from slurry drying and dust particles becoming
airborne) are best addressed through the employer's written exposure
control plan and competent person requirements, rather than as a note
or additional specification included in each Table 1 entry. These
requirements are discussed above and in the summary and explanation of
Written Exposure Control Plan.
In several Table 1 entries, OSHA has included a requirement to
operate and maintain tools in accordance with manufacturer's instructions
to minimize dust emissions. This requirement is intended to ensure
that the controls are implemented effectively to reduce exposures to
respirable crystalline silica. Manufacturer's instructions that influence
the effectiveness of the tool and controls with regard to minimizing
dust emissions may include, but are not limited to, additional
specifications for water flow rates, air flow rates, vacuum equipment,
rotation of the blade, maintaining and changing blades, and frequencies
for changing water.
Respiratory protection specified on Table 1. Industry associations,
including the American Subcontractors Association (ASA), the Institute
of Makers of Explosives (IME), the General Contractors Association of
New York (GCANY), and CISC, commented on the appropriateness of the
respirators that OSHA proposed for Table 1 (e.g., Document ID 2213, p.
2; 2187, p. 3; 2314, p. 2; 2319, p. 102). For example, ASA stated:
OSHA's proposed Table 1 for construction would seem to suggest
that the Agency believes a construction employer can achieve the PEL
with engineering and work practice controls. Yet the Agency then
requires respiratory protection for 60 percent of the operations
listed in Table 1. This failure is even more perplexing since OSHA
failed to identify, obtain and/or cite sufficient data for its
conclusions with respect to the 13 operations addressed in Table 1
(Document ID 2187, p. 3).
GCANY explained in their comments that "[c]urrent respiratory
protective equipment is cumbersome to wear and to work in and would
expose the worker to other hazards on a job site" (Document ID 2314,
p. 2). CISC urged OSHA to "eliminate the heavy use of respiratory
protection," arguing that:
OSHA's reliance on respiratory protection is analytically
inconsistent with its position that it is technologically feasible
to reach the proposed PEL in most construction operations most of
the time, and particularly when the control measures specified in
Table 1 are used. Requiring such heavy use of respirators...will
serve as a significant barrier to effective use of [Table 1]
(Document ID 2319, p. 102).
Respirator requirements on Table 1 of the final rule are based on a
review of all the evidence pertaining to exposure profiles and
available controls in the rulemaking record, including an evaluation of
the updated exposure profiles and evidence on available controls
submitted to the rulemaking record, as described in Chapter IV of the
FEA. A primary purpose of such evaluation was for OSHA to better
identify those situations where exposures above the PEL are likely to
persist despite full and proper implementation of the specified
engineering and work practice controls and supplemental respiratory
protection will therefore be necessary to ensure employees are
protected from silica-related health risks. As documented in its
analyses of technological feasibility for each Table 1 task, OSHA finds
that most of the time employees are performing tasks on Table 1,
respiratory protection will not be required. For most of the tasks or
equipment on Table 1, OSHA expects that work will be performed for four
hours or less and/or outdoors (see Chapter IV of the FEA). For certain
tasks listed on Table 1, OSHA was able to distinguish indoor
environments, where exposures are typically above 50 [micro]g/m\3\ even
with the use of engineering controls and work practices, from outdoor
environments, where engineering controls can typically maintain
exposures below 50 [micro]g/m\3\, in order to eliminate requirements
for respiratory protection where tasks are performed outdoors (e.g.,
using handheld grinders for uses other than mortar removal
(c)(1)(xii)). Elsewhere, OSHA was able to further refine the equipment
or tasks listed on Table 1 (e.g., handheld power saws (c)(1)(ii)-(iii);
walk-behind and drivable masonry saws (c)(iv)-(v); milling machines
(c)(1)(xiii)-(xv)) in order to eliminate previously proposed
requirements for respiratory protection. In other cases, OSHA found
engineering controls and work practices specified on Table 1 sufficient
to maintain employee exposures at or below 50 [micro]g/m\3\ when fully
and properly implemented (e.g., (c)(1)(i), (c)(1)(ix), (c)(1)(xiv)),
and thus determined that a respiratory protection requirement was not
necessary. Specific changes to the respiratory protection requirements
for each task listed on Table 1 are discussed in more detail below.
Consequently, required respiratory protection under Table 1 is
limited to situations in which OSHA has determined that exposures over
50 [micro]g/m\3\ will often occur. For example, OSHA is not requiring
the use of respiratory protection when handheld power saws (any blade
diameter) are used outdoors, for less than four hours, with water-based
dust suppression systems because OSHA's exposure profile indicates that
exposures will be below 50 [micro]g/m\3\ TWA most of the time that saws
are used, given typical work patterns (e.g., outdoors for less than
four hours per shift) (see Section 5.6 of Chapter IV of the FEA). Data
submitted to the record by the Concrete Sawing and Drilling Association
(CSDA) (Document ID 3497) also show that wet sawing produces exposures
below 50 [micro]g/m\3\ TWA with typical use patterns during the work
shift. In contrast, indoor use of handheld wet power saws generates
frequent exposures in excess of 50 [micro]g/m\3\ TWA with typical use
patterns during the work shift; from OSHA's exposure profile, half of
the exposure samples associated with using handheld power saws indoors
exceed 50 [micro]g/m\3\ TWA, and two indoor samples included in the
data submitted by CSDA were above a TWA of 50 [micro]g/m\3\ (Document
ID 3497, p. 5). As a result, Table 1 requires supplemental respirator
use when handheld power saws are used indoors or in an enclosed area
with water-based dust suppression systems.
OSHA has also used the terms "indoors or in an enclosed area"
rather than "indoors or within a partially sheltered area" in order
to clarify that any requirement to use respiratory protection when the
task is performed under these conditions is limited to those areas
where the dispersal of dust can be impeded such that concentrations can
build up without the aid of forced ventilation. For example, a work
area with only a roof that does not impede the dispersal of dust would
not be considered "enclosed," while it may have been considered by
some to be a "partially sheltered area."
As a result of these modifications, OSHA expects that many fewer
employees will need to use respiratory protection than was the case for
the proposed rule, and respiratory protection will not be necessary for
the most commonly encountered work situations and environments
specified on Table 1.
ISEA suggested that OSHA make the respirator requirements on Table
1 more user-friendly and performance-oriented by listing only an APF
and recommending that users consult the APF table found in the
respiratory protection standard, rather than listing generic respirator
types (Document ID 2212, p. 2). In response to this comment, OSHA has
maintained certain requirements for respiratory protection, but has
eliminated specific requirements for the type of respirator that must
be used (e.g., half-mask respirator, powered air-purifying respirator
(PAPR) with loose-fitting helmet or negative pressure full facepiece).
Instead, OSHA includes on Table 1 only the minimum Assigned Protection
Factor (APF) required. This change from the proposal provides the
employer with the option of determining which respirator offers the
best protection for its employees in the multitude of construction
environments that may be encountered. However, this is only the minimum
protection factor required for the respirator, and employers have the
flexibility to provide a more protective respirator to those employees
who request one or require a more protective respirator based on the
employer's evaluation of the worksite. As discussed in the summary and
explanation of Respiratory Protection, paragraph (d)(3)(i)(A) of the
respiratory protection standard (29 CFR 1910.134), which includes a table
that can be used to determine the type or class of respirator that is
expected to provide employees with a particular APF, can help employers
determine the type of respirator that would meet the required minimum
APF specified by Table 1. In order to reflect this change to the
respirator requirements, the Agency has modified the heading on Table 1
to "Required Respiratory Protection and Minimum Assigned Protection
Factor (APF)."
The respirator requirements on Table 1 are divided by task
duration: "less than or equal to four hours/shift" and "greater than
four hours/shift." AIHA recommended that OSHA clarify what time is
included when determining less than or greater than four hours
(Document ID 2169, p. 6). OSHA has determined that time starts when the
operator begins using the tool, and continues to be counted until he or
she completes the task. This time includes intermittent breaks in tool
usage and clean-up. For example, an employee cuts and places bricks,
one at a time, for three hours consecutively. The employee then spends
30 minutes cleaning up the saw and empting slurry or dust collectors.
All three hours spent cutting and laying bricks along with the 30
minutes for clean-up count. Tasks that are performed multiple times per
day, during distinct time periods, should be counted as separate tasks,
and times should be combined. For example, an employee cuts multiple
bricks for 15 minutes, lays bricks for two hours and returns to cut
more bricks for another 30 minutes. The two hours spent laying bricks
do not count towards the total time for compliance with Table 1.
The duration of a task that generates respirable crystalline silica
influences the extent of employee exposure and, in some cases,
requirements for use of respirators. Some commenters suggested that
OSHA modify the time breakdown for activities and respirator usage,
such as BCTD's suggestion to divide tasks on Table 1 into two hours,
four hours, and eight hours. Other commenters such as CISC, Holes
Incorporated, and the Mason Contractors Association of America,
suggested that OSHA exclude short duration tasks (e.g., 90 minutes or
less) from Table 1, and NUCA suggested that the four hour cutoff is
arbitrary and had no data to support it (Document ID 4073, Attachment
14f, p. 2; 2319, pp. 100-102; 3580, Tr. 1453; 3585, Tr. 2882; 3729, p.
3).
After reviewing these comments, OSHA has decided to maintain this
division in the standard. OSHA selected four hours as an appropriate
division point for respirator usage because it finds that employers and
employees can anticipate whether a task will take less than half of a
shift or more than half of a shift (as opposed to smaller time
intervals), and so can plan accordingly on the need for respirator use
on a given job. In addition, OSHA selected only a single durational
division for respirator tasks in all of the relevant Table 1 tasks to
avoid the confusion that could result from triggering mandatory
respirator use at different times for different tasks. OSHA also
determined that excluding short duration tasks from Table 1, although
included in the ASTM E 2625-09 consensus standard, was inappropriate,
given that employees engaged in a task listed on Table 1 are best
protected using the available engineering controls, work practices, and
respiratory protection specified for the task and are only exempt from
complying with the standard where employee exposure will remain below
25 [micro]g/m\3\ as a time-weighted average under any foreseeable
conditions (see summary and explanation of Scope for further discussion
of this exclusion).
Table 1 of the proposed rule used the phrase "4 hours per day" to
indicate when respirators were required, but Table 1 of the final
standard uses "4 hours per shift." OSHA's exposure data is largely
drawn from samples of employee exposure averaged over an 8-hour period,
which is a typical time for a shift. The proposed rule referred to a
time period of four hours "per day" for the purpose of limiting
employee's exposure during the normal 8-hour shift that most employees
work during a single day. OSHA recognizes, however, that some common
tasks such as jackhammering during nighttime highway construction may
occur during an 8-hour period that spans two calendar days (e.g., 8
p.m. until 4 a.m.). OSHA did not intend to allow employees to be
exposed to respirable crystalline silica without respiratory protection
for longer than four hours in that scenario, so OSHA has specified four
hours "per shift" in the final rule.
OSHA also recognizes that the form and length of a shift may vary
such that an employee may have a break between work periods (e.g., four
hours on, two hours off, four hours on), work shifts may be longer than
eight hours, or employees may work double shifts within a single day.
The work periods in each of those examples constitutes a "shift" for
purposes of determining the maximum amount of time that an employee may
spend on one of the applicable Table 1 tasks without respiratory
protection. OSHA's exposure data is not sufficient to support the
conclusion that a longer duration of exposure without respiratory
protection would be safe just because that exposure is spread out over
a period that is longer than the normal 8-hour shift. Thus, an employee
who works a 12-hour shift from 8 p.m. to 10 a.m. with a 2-hour rest
break in the middle would have to wear a respirator if engaged in an
applicable Table 1 task such as jackhammering outdoors if the employee
will be jackhammering from 8 p.m. to 11 p.m., taking a break from 11
p.m. until 2 a.m., and then jackhammering again from 2 a.m. until 4
a.m. for a total of five hours of jackhammering. However, assuming no
other silica exposure, the employee would not require respiratory
protection if the jackhammering is limited to 8 p.m. until 11 p.m. and
2 a.m. until 3 a.m. for a total of four hours, even if the employee
repeats the same shift and jackhammering times every day of the week.
Accordingly, the change from "per day" to "per shift" clarifies
OSHA's original intention regarding when respirator use is required for
Table 1 tasks.
The requirement to provide respirators for Table 1 tasks is based
on the anticipated duration of the task. Some commenters, such as EEI,
expressed confusion about how this requirement would apply to non-
continuous work (e.g., Document ID 2357, p. 27). EEI opined that:
The nature of non-continuous work can also make it hard to
anticipate when a certain task may exceed four hours per day.
Suppose, for example, a job task using a stationary masonry saw is
not anticipated to last beyond four hours, so all controls listed in
Table 1 are followed, and the employee does not wear a respirator.
Then, due to unforeseen complications, the job lasts beyond four
hours. Simply following the regulations as proposed, it is unclear
whether the employee would be allowed to put on a half-mask after
four hours, or if OSHA will not allow the employer to use the Table
1 option because the employee was not in a half-mask for the first
four hours (Document ID 2357, p. 27).
In contrast, other commenters suggested that, despite the variable
nature of the work, employers and employees generally know how long it
will take to complete a particular task (e.g., Document ID 3581, Tr. 1684, 1686).
OSHA recognizes, based on the comments above and the nature of
construction work in general, that application of this requirement
warrants some flexibility. For several Table 1 tasks, respiratory
protection with the appropriate APF is required if the duration of a
task is anticipated to exceed four hours, but is not required if the
duration of a task is less than or equal to four hours (e.g., (c)(1)
(ii), (c)(1)(x), (c)(1)(xii)). For these tasks, the Agency does not
expect employers to know exactly how long it will take to perform a
task. Rather, OSHA expects employers to make a good-faith judgment
of the task's anticipated duration over the work shift based on
previous experience and all other available information. If the
employer anticipates that an employee will be engaged in a task for
more than four hours, the employer must provide respirators (if
required by Table 1) to the employee at the beginning of the shift. For
example, in the case of an employee grinding concrete walls indoors,
the employer should know, in advance, the area of surface that is to be
worked on in the course of a shift. If, based on the employer's
experience, the time needed to grind that area is typically less than
four hours, the employer would not be required to provide respirators
to the employee. If, however, using the same example, the employer
experiences unforeseen difficulties that extend the task duration
beyond four hours, the employer would be required under Table 1 to
provide the listed respiratory protection as soon as it becomes evident
that the duration of the grinding task may exceed the 4-hour limit,
measured from the beginning of the task rather than the point when the
need for extra time becomes evident.
Commenters, including BCTD, Fann Contracting, and IUOE, expressed
confusion about whether an employee must wear a respirator for the
entire duration of a task when that task is expected to last more than
four hours, or rather wear the respirator for only the portion of the
task that exceeds four hours (e.g., Document ID 3581, Tr. 1681; 2116,
Attachment 1, p. 28; 2262, p. 27). OSHA hereby clarifies that the
intent is to require respirator use throughout the duration of the
task.
The objective of the silica standard is to limit an employee's
average exposure over a work shift. In each of OSHA's health standards,
this is accomplished by establishing a PEL expressed as an 8-hour TWA.
Because a PEL is a time-weighted average, the Agency has traditionally
required employees to use respirators throughout a shift when employees
work on a task or in an area where exposure to a hazardous substance
contributes significantly to an employee's exposure in excess of the
PEL at any point during that shift. This same reasoning applies to
wearing a respirator from the beginning of a shift where respirators
are required on Table 1. Thus, OSHA is continuing the same approach to
respirator use for tasks listed on Table 1 of the standard for
construction as it has for other OSHA health standards. Under Table 1
of the final standard for construction, when a respirator is required
only when a task is performed for more than four hours per shift and
when the employer estimates that the duration of the task will exceed
four hours, the employer must provide and ensure that a respirator is
used the entire time that task is performed over the shift, not just
during the time beyond the first four hours that the task is performed.
For example, if an employer anticipates that an employee will operate a
jackhammer outdoors for more than four hours, the employer must provide
respiratory protection with an APF of 10 and require that it be used
for the entire duration of the task. For tasks that are typically
intermittent, employers are required to estimate at the outset the
total time during the shift that the task itself will be performed and
provide respirators required by Table 1 based on that estimate. If an
employer knows from experience that an employee will perform a single
task listed on Table 1 for four hours or less during a single shift,
then the employer must ensure that the employee uses whichever
respirator is specified in the "<= 4 hr/shift" column on Table 1 (or
need not provide a respirator if no respirator is required on Table 1
for that duration). As another example, if a contractor needs to cut
four concrete walls using a handheld power saw (outdoors), and cutting
each wall typically takes 45 minutes to complete, for a total time of 3
hours, the employer would not be required by Table 1 to provide a
respirator. But if cutting each wall typically takes in excess of 60
minutes, the employer should expect that the total duration of the task
will exceed four hours and provide respirators as required under Table
1. The employer is required to provide respirators as soon as it
becomes evident that the duration of the task will exceed four hours.
Thus, in most situations an employee will be protected by a respirator
for all or the majority of a task that exceeds four hours because the
rate of progress on the task will become apparent to the employer early
on. An employee cannot be allowed to work more than four hours without
a respirator when one is required under Table 1 because the employer
will have certainty at that point that the task is exceeding four
hours.
The above examples assume that employees are engaged in only one
task covered by Table 1 each shift. Paragraph (c)(3) of the standard
for construction requires that, where employees perform more than one
task on Table 1 during the course of a shift for a combined total of
more than four hours, employers must provide, for the entire duration
of each task performed, respiratory protection that is consistent with
that specified in the "> 4 hr/shift" column of Table 1, even if the
individual duration of each task is less than four hours. If no
respirator is specified for a task in the "> 4 hr/shift" column of
Table 1, then respirator use would not be required for that part of the
employee's shift. For example, if an employer plans to have his
employee use a handheld grinder outdoors on a concrete wall for three
hours and then use a chipping hammer for two additional hours, the
employer would not be required to ensure that his employee uses a
respirator for the three hours the employee is using the grinder, since
respiratory protection is not specified on Table 1 for the use of a
grinder outdoors for more than four hours per shift; however, the
employer would be required to ensure that his employee uses a
respirator with an APF of 10 for the two hours the employee is using
the chipping hammer. This is so even though use of the chipping hammer,
if performed with no grinding beforehand, would not have required a
respirator for the duration that the tool was used. If the employee
will be engaged in two activities that both have "None" specified for
respiratory protection in both the "<= 4hr/shift" and the "> 4 hr/
shift" columns, such as driving a half-lane milling machine and then
operating a walk-behind milling machine equipped with an integrated
water delivery system, then respirator use would not be required for
any part of an employee's shift even if the employer knows that the
cumulative total of that work will exceed four hours.
When an employee performs multiple tasks that do not exceed a
combined total of more than four hours, employers must provide the
respiratory protection specified in the "<= 4 hr/shift" column of
Table 1 for each task. For example, if an employer plans to have his
employee use a handheld grinder for mortar removal for one hour and a
stationary masonry saw for an additional two hours, the employer is
required to ensure that his employee uses a respirator with an APF
of 10 for the one hour the employee is using the grinder. The employer
would not be required to ensure that his employee uses a respirator
for the two hours the employee is using the stationary masonry saw,
since respiratory protection is not specified on Table 1 for the use
of a stationary masonry saw.
Thus, whatever permutations may arise, the employer must estimate
the duration of the task(s) to determine whether Table 1 will trigger
the requirement for respiratory protection. If unforeseen conditions
arise that cause the estimated duration to be revised for any of the
tasks, the employer is required to provide the required respiratory
protection as soon as it becomes evident that the employee will be
engaged in the task for more than four hours during the shift.
Updating Table 1. Commenters, including LHSFNA, BAC, BCTD, Charles
Gordon, and James Hardie Building Products, Inc., suggested that the
utility of Table 1 will diminish over time if OSHA has no mechanism to
include new control methods that may be developed (e.g., Document ID
4207, pp. 2-3; 4219, pp. 20-21; 4223, pp. 98-102; 3588, Tr. 3792-3793;
2322, pp. 21-23).
Commenters also provided specific recommendations for the frequency
at which OSHA should update Table 1 and the process by which OSHA
should do so. James Hardie Building Products, Inc. commented that
additional controls demonstrated to maintain or increase employee
protection should be incorporated by reference whenever they become
available "without the need to undergo a formal rulemaking process"
(Document ID 2322, pp. 21-22). The National Consumers League and the
American Public Health Association suggested that OSHA consider
updating Table 1 periodically (e.g., every five years) and publish a
direct final rule to adopt a revised Table 1 when NIOSH deemed new dust
control technology effective and feasible (Document ID 2373, p. 3;
2178, p. 3). Similarly, the Center for Effective Government urged OSHA
to review Table 1 every five years and make revisions when new control
technologies are found to be technologically and economically feasible
(Document ID 3586, Tr. 3319).
Other commenters urged OSHA to consider mechanisms to update Table
1 without going through the rulemaking process. NIOSH suggested that
the Agency develop a database of control technologies to supplement
those on Table 1, rather than initiate rulemaking to update Table 1
(Document ID 2177, Attachment B, pp. 20-21). LHSFNA suggested that OSHA
post enforcement decisions based on objective data online and permit
employers performing similar tasks to use the controls specified in
those decisions to meet their obligations under Table 1 (Document ID
4207, pp. 2-3). Holes Incorporated argued that Table 1 should be
amendable by employers when testing proves that using such controls
would ensure compliance with the PEL (Document ID 3441, p. 12; 3580,
Tr. 1491).
IUOE, BCTD, and BAC argued that Table 1 should be an appendix to
the rule so that it can be more easily updated (Document ID 2262, pp.
48-49; 2329, p. 6; 2371, Attachment 1, pp. 30-31). BCTD offered an
approach for updating Table 1 that relied on the Agency establishing a
mechanism for employers, equipment manufacturers, and others to submit
data to the Agency for evaluation and subsequent inclusion in future
versions of Table 1. BCTD proposed:
OSHA could publish the criteria in a non-mandatory appendix to
the standard, so employers, manufacturers and researchers would have
a clear understanding of what they will have to demonstrate to get
their proposed controls onto the table.
Interested parties could then request that OSHA evaluate a
control option, supporting their request with objective data, peer-
reviewed studies, reports by NIOSH or other governmental agencies,
or other reputable sources. If OSHA determined, based on the
supporting data, that the technology meets its criteria for
inclusion on Table 1, OSHA would issue an interpretative letter to
that effect and/or issue a compliance directive advising its
compliance officers that employers that fully and properly implement
the particular control should be treated as if they were in
compliance with the requirements of Table 1. This approach would
enable OSHA to continually add to the options employers can utilize
as new technologies come on-line, while at the same time ensuring
that these additional controls meet the Agency's criteria (Document
ID 4223, p. 100).
Charles Gordon also provided a detailed suggestion for the addition
of regulatory text to address the issue of updating Table 1:
Updating controls. (i) Three years from the effective date of
this standard and every 3 years thereafter, OSHA shall request
comments on new or improved engineering controls which can achieve
the PEL or Action Level without supplementary respirator use for
operations specified in Table 1 or other operations not in Table 1
that have crystalline silica exposure over the Action Level.
(ii) If OSHA concludes that a new control will achieve the PEL
without supplementary respirator use, it shall publish a notice
permitting that control to be used for that Table 1 operation along
with the other permitted controls or publish a direct final rule
including that other operation in Table I and permitting the use of
that control.
(iii) If a commenter submits to OSHA an engineering control for
an operation in Table 1, which can achieve the action level without
supplementary respirator use based on valid studies and cost data
showing it is feasible, then no later than the date specified in
paragraph (f)(6)(i), OSHA shall publish a proposal, proposing that
that engineering control be the required engineering control for
that operation (Document ID 4236, Appendix 1, p. 1).
Based on the comments and perspective reflected in the rulemaking
record, OSHA sees the value in periodically updating Table 1 and is
concerned that a static Table 1 may discourage innovation in the
development of control technologies for reducing silica exposure.
However, while OSHA may certainly consider future updates or
adjustments to Table 1 if warranted, it will likely need to accomplish
substantive changes through additional rulemaking. In any event, it has
no intention to bind a future Administration to such rulemaking,
whether to update Table 1 in particular or the entire rule in general,
according to a schedule built into this rule. Meanwhile, the need to
revise Table 1 in the future should be limited since the controls
specified--primarily wetting the dust or ventilating and collecting the
dust--are stated in general terms that will not be rendered obsolete
by, for example, design improvements to water spraying or vacuuming
equipment.
Even if the proposed mechanisms are consistent with the law
governing rulemaking, OSHA is unwilling to specify a mechanism for
updating Table 1 for several reasons. First, the procedures outlined by
BCTD and Charles Gordon would commit the Agency to spend future
resources to accept a large volume of information from interested
parties, evaluate it in a timely manner, and prepare the needed
economic and technological feasibility analysis and other rulemaking
documents. OSHA may have higher rulemaking priorities and demands on
its resources at that time, however. Second, Table 1 cannot both
contain enforceable means of compliance and also be contained in a non-
mandatory appendix. To ensure that employers who do not conduct
exposure monitoring comply fully with the Table 1 provisions, OSHA must
include the control specifications of Table 1 in the final standard for
construction as requirements rather than as non-mandatory
recommendations. Third, the controls specified on Table 1 are flexible
and not tied to existing technology. The controls specified on Table 1
provide for the use of wet methods, ventilation, and in some cases,
isolation. OSHA did not provide specific criteria for ventilation systems
(size, air flow rate, etc.) or water flow rates. Instead, OSHA specifies
that employers must operate the tools with integrated dust controls in
accordance with the manufacturer's instructions. These instructions
provide flexibility to take advantage of advances in technology.
For example, as manufacturers develop effective surfactants to be used
with water to further reduce silica exposure, there will be no need for
OSHA to update Table 1 to specifically allow employers to use them.
The requirement to use wet methods would still be satisfied.
Thus, OSHA rejects the suggestions to establish a specific
mechanism for updating Table 1 in the future. If significant
technological advances occur that require OSHA to initiate rulemaking
in order to incorporate emerging technology not already encompassed by
this rule, it will do so in the context of its rulemaking priorities at
that time. Of course, interested parties may petition the Agency at any
time to modify the dust control specifications on Table 1 of the
standard for construction, and OSHA will consider such petitions based
on the likely benefit that will accrue to workers and the Agency's
available resources at the time.
Comparison with consensus standards. The requirements in paragraph
(c) of the standard for construction are generally consistent with ASTM
E 2625-09, the national consensus standard for controlling occupational
exposure to respirable crystalline silica in construction. The ASTM
standard provides a task-based control strategy, including five tables
that specify control measures and respiratory protection for common
construction equipment and tasks. While the ASTM standard provides this
task-based control strategy, it also applies the PEL and exposure
assessment to these tasks, as OSHA did in its proposal. However, OSHA's
final standard for construction, as discussed above, takes a different
approach by requiring specific engineering controls, work practices,
and respiratory protection for construction tasks on Table 1; where
employers fully and properly implement the engineering controls, work
practices, and respiratory protection specified on Table 1, compliance
with Table 1 is in lieu of the performance-oriented approach involving
a PEL and exposure assessment, as provided as an alternative exposure
control method in paragraph (d) of the standard for construction.
Additionally, there are numerous differences between the tasks listed
and the engineering controls, work practices, and respiratory
protection specified on OSHA's Table 1 and those included on ASTM's
tables. The ASTM standard also does not divide tasks according to
duration and does not apply the approach to tasks limited to 90 minutes
total time. The differences between OSHA's standard and the consensus
standard, including those in the overall approach to compliance and in
the format of Table 1, the tasks listed, and the engineering controls,
work practices, and respiratory protection specified, best reflect the
evidence received into the rulemaking record and the realities of the
construction industry. These differences will also enhance compliance
with OSHA's standard in the construction industry and, in doing so,
better effectuate the purposes of the OSH Act and protect employees in
the construction industry from the significant risks posed by exposures
to respirable crystalline silica.
Table 1 entries. Table 1 identifies 18 common construction
equipment/tasks known to generate high exposures to respirable
crystalline silica. For each kind of equipment/task identified, Table 1
specifies appropriate and effective engineering controls, work
practices, and, when necessary, respiratory protection. As proposed,
Table 1 listed 13 construction operations that expose employees to
respirable crystalline silica and identified control strategies and
respiratory protection that reduce those exposures. OSHA received many
specific comments about particular entries on Table 1 and on the
specified engineering controls, work practices, and respiratory
protection included for each entry. The additional equipment/tasks
included on Table 1 of the final rule for construction are handheld
power saws for cutting fiber-cement board (with blade diameter of 8
inches or less) and rig-mounted core saws and drills. Other entries on
Table 1 of the final standard for construction were broken out from
those proposed and added as separate entries. These include dowel
drilling rigs for concrete (included under "Operating Vehicle-Mounted
Drilling Rigs for Concrete" on proposed Table 1), walk-behind milling
machines and floor grinders (included under "Milling" on proposed
Table 1), small drivable milling machines (included under "Milling"
on proposed Table 1), large drivable milling machines (included under
"Milling" on proposed Table 1), heavy equipment and utility vehicles
used to abrade or fracture silica-containing materials or used during
demolition activities involving silica-containing materials (included
under "Heavy Equipment During Earthmoving" on proposed Table 1), and
heavy equipment and utility vehicles for tasks such as grading and
excavating, but not demolishing, abrading, or fracturing silica-
containing materials (included under "Heavy Equipment During
Earthmoving" on proposed Table 1). One entry on Table 1 of the final
standard for construction, vehicle-mounted drilling rigs for rock and
concrete, is the result of combining two entries from proposed Table 1
("Operating Vehicle-Mounted Drilling Rigs for Rock" and "Operating
Vehicle-Mounted Drilling Rigs for Concrete"). One proposed entry,
"Drywall Finishing," was not included on Table 1 of the final
standard for construction. A discussion of each of the 18 Table 1
entries in the construction standard, including the comments received
and the changes made from the proposed Table 1 entries, follows below
in the order in which they appear on Table 1.
Stationary masonry saws. Stationary masonry saws are used in the
construction industry to cut silica-containing masonry materials such
as bricks, concrete blocks, stone, and tile (see Section 5.7 of Chapter
IV of the FEA). They are mounted either on a table-top or a stand, and
include a flat platform where the work piece (e.g., a brick) sits
before the worker brings a rotating circular abrasive blade into
contact with the work piece by either pressing a swing arm mounted
blade onto the piece or by moving the piece on a sliding platform into
contact with a fixed blade (Document ID 4073, Attachment 4a, Rows 42-
48, 55-63, 179-188, 288-297, 343-351). The cutting surface is about
waist-high and at arm's length from the worker's breathing zone. A
nozzle for spraying water is usually attached near the blade, and is
connected to a water basin of some kind via a hose.
When using stationary masonry saws, paragraph (c)(1)(i) of the
standard for construction requires that saws be equipped with an
integrated water delivery system that continuously feeds water to the
blade and that the tool be operated and maintained in accordance with
manufacturer's instructions to minimize dust emissions. Saw designs
vary between manufacturers and, as with other operating parameters,
manufacturer's recommendations for optimizing wet methods are likely to
vary somewhat with the saw size and design. OSHA is not specifying a
minimum flow rate; based on the evidence in the record, OSHA
anticipates that the water flow rate specified by the manufacturer
will optimize dust reduction. OSHA recognizes that the employer's
best available information for reducing dust with a specific
control comes from the manufacturer's operating instructions.
This is why OSHA is requiring the saw be operated and maintained
according to the manufacturer's instruction to minimize dust.
The language describing the required control for stationary masonry
saws was revised from the proposed rule to clarify that water must be
continuously applied to the blade, and language was added to require
that manufacturer's instructions be followed. This reflects OSHA's
intent that employers use a saw with integrated water delivery system
supplied by the saw manufacturer. OSHA finds that systems that are
developed in conjunction with the tool are more likely to control dust
emission effectively by applying water at the appropriate dust emission
points based on tool configuration, and not interfere with other tool
components or safety devices. These include free-flowing water systems,
with or without a pump and basin, that are designed for blade cooling,
as well as manufacturer systems designed for dust suppression alone
(Document ID 1555, p. 509; 3998, Attachment 12a, pp. 9, 15-16; 3998,
Attachment 12e, p. 3).
The proposed entry for stationary masonry saws also included a note
requiring that water be changed frequently to avoid silt build-up in
water and that the blade not be excessively worn. CISC commented that
terms such as these were too ambiguous and would thus prevent the table
from being a realistic compliance option (Document 2319, p. 98). OSHA
understands that these notes could be subject to interpretation and in
response, has removed the notes from Table 1. However, these practices
are often included in manufacturer's instructions, and OSHA considers
these type of instructions to be part of fully and properly
implementing engineering controls (e.g., Document ID 4073, Attachment
4a, Rows 59-61).
In the FEA, OSHA's exposure profile for stationary masonry saws
shows that wet cutting is an effective dust control. The median 8-hour
TWA exposure in the profile is 34 [mu]g/m\3\ for workers using saws
with water delivery systems (Table IV-5.7-B in Section 5.7 of Chapter
IV of the FEA) and the mean exposure for wet cutting is 41 [mu]g/m\3\,
substantially lower than the mean of 329 [mu]g/m\3\ for dry cutting
operations, a disparity that affirms that use of water on stationary
saws significantly reduces exposure to respirable crystalline silica.
Additional field data also show the effectiveness of water to control
respirable crystalline silica exposures during cutting. Flanagan et
al., in their 2006 study and 2009 data set, found that wet cutting
methods (details not available) were associated with markedly lower
exposure levels than were reported for all workers using table-mounted
saws (Document ID 0677; 0677, Attachment 2). The silica concentrations
reported by Flanagan et al. over the sampling period (ranging from 12
to 505 minutes) when wet cutting ranged from 6 [mu]g/m\3\ to 316 [mu]g/
m\3\, with a mean of 73 [mu]g/m\3\ and median of 46 [mu]g/m\3\
(Document ID 0677; 0677, Attachment 2). Since most of the sample
durations in this dataset were less than 360 minutes, workers' 8-hour
TWA exposures were even lower. These data also included indoor work.
In addition to these field results, the record includes
experimental studies that examined the effectiveness of wet dust
control systems. Meeker et al. (2009) compared intensive masonry
cutting done without controls to exposures while using saws with
integrated water delivery systems and maximum flow rates of 2.3 and 2.4
liters per minute (0.6 and 0.63 gallons per minute) and found that wet
saws were associated with a 91 percent reduction in exposure to
respirable quartz (Document ID 803, p. 1; 2177, Reference 11, pp. 104,
107-108). Carlo et al. (2010) found reduction rates of 99 percent in
the respirable dust exposure when water was applied at the
manufacturer-recommended water flow rate, compared to dry cutting
(Document ID 3612, pp. 246-247, 249). While respirable dust reductions
do not always translate to exactly the same percent reduction in
respirable silica levels, OSHA finds that respirable dust reductions
are a reliable indicator of the capability of the control to reduce
respirable silica. Therefore, OSHA anticipates that the control
discussed in Carlo et al. (2010) would result in significant reductions
to silica exposures.
CISC questioned the appropriateness of requiring an integrated
water delivery system when most integrated systems are intended to keep
the blade cool and are not designed for dust suppression (Document ID
2319, p. 109). However product literature submitted to the docket from
five major saw manufacturers (Andreas Stihl, Husqvarna, Hilti, Makita
USA, and Wacker Group) highlights the use of water application
equipment to suppress dust in addition to blade cooling (Document ID
3620, pp. 6, 10, 24, 30; 3998, Attachment 12a, pp. 9, 15-16; 3998,
Attachment 12e, p. 3; 3998, Attachment 12f; 3998, Attachment 12h; 4233,
Attachment 1, p. 6). Beamer et al. (2005) conducted experiments to
observe the differences in the various wet cutting methods available
and found that the greatest improvement in dust reduction occurred with
freely flowing water applied at a rate of 48 gallons per hour (0.8
gallons per minute), resulting in dust reduction of about 93 percent
and confirming the benefits of water flowing over the stationary saw
cutting blade compared with other misting systems (Document ID 1555, p.
509). Therefore, based on the evidence in the record, OSHA has
determined that stationary masonry saws equipped with an integrated
water delivery system are effective and the best available technology
for controlling respirable crystalline silica.
Several commenters suggested that OSHA include an option for dry
cutting on Table 1 (i.e., using LEV or other non-wet methods to control
dust) because wet methods were not always available and certain
materials are required to be cut dry. Commenters explained that
freezing temperatures, lack of available water sources on new
construction sites, concerns of water damage to surrounding areas
during indoor work and problems with discoloration or water staining
materials were all reasons why an employer may elect to cut without
water (Document ID 0861, p. iv; 1431, pp. 1-6-1-9; 2296, p. 31; 2319,
p. 94; 2320, pp. 6-7; 3587, Tr. 3609-3610; 4220, p. 5).
OSHA addresses the issue of freezing temperatures and availability
of water in the technological feasibility analysis (Chapter IV of the
FEA) and has determined that these barriers can be overcome in most
instances, for example by wrapping gutter heat tape around drums of
water or adding environmentally-friendly antifreeze additives to water
(e.g., Document ID 3589, Tr. 4214, 4230). Moreover, evidence in the
record indicates that LEV is not as effective as wet methods for
controlling silica dust emissions from stationary saws. In the only
study available to OSHA that directly compared wet dust suppression
with LEV under the same experimental conditions, Carlo et al. (2010)
determined that, even though the use of LEV resulted in substantial
respirable dust capture, the water application system reduced the dust
to a greater extent, reducing respirable dust levels by a factor of 10
more than the LEV systems tested (Document ID 3612, pp. 247-250).
Unlike for wet dust control systems, there is little evidence in the
record that LEV systems have proven effective in actual field use;
the database compiled by Flanagan et al. contains no sample results
from using stationary saws with LEV (Document ID 0677, Attachment 2).
OSHA finds that the study by Carlo et al. indicates that LEV
systems on stationary saws are not as effective as water-based dust
suppression systems and that respiratory protection will likely be
needed. In the PEA, OSHA acknowledged that there was some evidence that
exposures could be reduced to or below 50 [mu]g/m\3\ with LEV when saws
were used for typical cutting periods (15 to 30 percent of the shift)
but that the effectiveness of LEV systems for stationary saws had not
been widely evaluated. However, no evidence came into the record after
the PEA that would allow OSHA to have greater confidence in the use of
LEV when dry cutting or to consider it to be as effective as wet
cutting in reducing silica dust exposure. Therefore, OSHA has not
included a control alternative for the use of dry cutting with LEV in
Table 1, and is only allowing integrated water systems for compliance
with Table 1.
OSHA understands that there may be limited situations where the use
of wet systems is not feasible for a given application. For those
situations, the employer may use other means of dust control such as
LEV systems, but the employer must then follow paragraph (d) rather
than paragraph (c) of the standard for construction, i.e., comply with
the 50 [mu]g/m\3\ PEL, perform exposure assessments to determine
compliance with the PEL, and supplement the engineering and work
practice controls with respiratory protection where the PEL is not
being met.
Stationary masonry saws with integrated water systems are readily
available from several manufacturers including EDCO, Andreas Stihl,
Hilti, Makita USA, Husqvarna, Wacker Group, MK Diamond, and Bosch (for
tile cutting) and are effective and the best control option available
(Document ID 4073, Attachment 4a, Rows 59-63, 183-188, 292-297, 347-
351, 417-419; 4073, Attachment 4b, pp. 10-12, 21; 3998, Attachment 12a;
3998, Attachment 12e; 3998, Attachment 12f; 3998, Attachment 12g; 3998,
Attachment 12h). Therefore, OSHA has determined that an integrated
water delivery system is the appropriate control for inclusion on Table
1.
In the proposed rule, OSHA required the use of a half-mask
respirator for employees who operated stationary masonry saws for more
than four hours. OSHA made this determination based on the highest
exposure results included in its exposure profile. OSHA has since
determined that when fully and properly implementing all of the
provisions under paragraph (c), employees can operate stationary
masonry saws without the use of respirators. This is supported by the
exposure profile contained in Table 5.7-B in Section 5.7 of Chapter IV
of the FEA, which shows a mean exposure of 41 [mu]g/m\3\, a median of
34 [mu]g/m\3\ and 75 percent of the sample results below 50 [mu]g/m\3\.
Flanagan et al. reported similar exposures with a mean exposure of 48
[mu]g/m\3\ crystalline silica from four exposure samples taken while
workers operated saws indoors or in enclosed areas (Document ID 0677,
Attachment 2). While water use was not described in any detail, these
data show that exposures can be consistently maintained at a level
where respiratory protection is not needed. Therefore, the final rule
does not require the use of respiratory protection when employers are
using wet stationary saws in accordance with Table 1, even when
stationary masonry saws are used indoors or in otherwise enclosed areas
(situations which are the most likely to generate high exposures).
Handheld power saws (any blade diameter). In the proposed rule,
this entry was listed as "Using Handheld Masonry Saws." OSHA has
changed the title of this entry in the final rule to clarify that the
requirements in Table 1 apply to any use of handheld power saws, not
just those involving masonry materials. However, the tools included
under this entry have not changed and include cut-off, chop, quickie,
and handheld masonry saws.
Handheld power saws are used in the construction industry for
cutting a variety of materials (see Section 5.6 of Chapter IV of the
FEA). They usually consist of a semi-enclosed circular blade, directly
adjacent to or in front of two handle grips which are perpendicular to
each other. The blade enclosure covers the half (or more) of the blade
directly facing the worker. A worker typically will use the blade to
cut a work piece (e.g., a brick) placed on the ground by starting the
device and slowly lowering the entire handheld saw with both hands to
the work piece until the rotating blade makes contact and begins to
cut, at which point the worker applies pressure to the work piece and
cuts appropriately (Document ID 4073, Attachment 4a, Row 47). A nozzle
for spraying water is usually located near the blade, and a water
source is usually connected to the saw from a water source via a hose
(Document ID 3998, Attachment 12e; 3998, Attachment 12f; 3998,
Attachment 12h, pp. 10-11).
When using handheld power saws with any blade diameter (except saws
used to cut fiber-cement board), paragraph (c)(1)(ii) of the standard
for construction requires that saws be equipped with an integrated
water delivery system that continuously feeds water to the blade and
that it be operated and maintained in accordance with manufacturer's
instructions to minimize dust emissions. Like stationary saws, designs
vary between manufacturers and, as with other operating parameters,
recommendations for optimizing wet methods are likely to vary somewhat
with the saw size and design. In light of these variables, OSHA is not
specifying a minimum flow rate. In addition, OSHA is recognizing that
the employer's best available information for reducing dust with a
specific control comes from the manufacturer's operating instructions,
which is why OSHA is requiring the saw be operated and maintained
according to the manufacturer's instructions to minimize dust. Water-
fed handheld saws are commercially available from a variety of sources
(Document ID 0615; 0737; 3998, Attachment 12e; 3998, Attachment 12a;
3998, Attachment 12f; 3998, Attachment 12g; 3998, Attachment 12h).
The data in the record and the studies reviewed by OSHA demonstrate
that water spray suppression systems reduce respirable crystalline
silica exposures substantially where the system was well designed and
properly implemented and maintained (Document ID 0868; 1181; 3497;
3610; 3777; 4073, Attachment 8a). Use of an integrated water delivery
system on the cut-off, chop, quickie or masonry saws has been shown to
reduce respirable dust exposures by 78-96 percent (Document ID 0868, p.
v; 1181, p. 443; 3610, p. 157; 3777, p. 67). Data compiled by the CSDA
from member jobsites as well as NIOSH documents showed that all outdoor
hand sawing using a saw equipped with a water supply produced exposure
levels below a TWA of 50 [mu]g/m\3\ (Document ID 3497, p. 5).
In a laboratory study, Thorpe et al. (1999) evaluated the
effectiveness of two types of water supplies commonly used with
handheld saws: (1) A pressurized portable water supply and (2) a
constant water supply (Document ID 1181, pp. 443, 445-447). During this
evaluation, 15-minute PBZ samples were collected during uncontrolled
and controlled (i.e., water-fed) cutting of concrete slabs containing
20 percent to 40 percent silica (i.e., worst-case conditions)
(Document ID 1181, p. 447). The study protocol involved short sampling
durations because handheld saws are typically used intermittently to
make short cuts. The uncontrolled mean silica concentration during
multiple 15-minute trials of intensive cutting ranged from 1,700
[mu]g/m\3\ to 4,800 [mu]g/m\3\ (reported as 1.7 to 4.8 mg/m\3\)
(Document ID 1181, p. 448). Reductions in exposure to respirable
silica dust when cutting concrete slabs using wet methods compared
with no controls were 75 percent for diamond blades and 94 percent
for resin blades when using water supplied by mains, and 75 percent
for diamond blades and 77 percent for resin blades when using water
supplied by a portable tank. Both sources of water were effective
at reducing respirable dust, however, the portable tank needed to be
periodically re-pressurized to maintain the necessary flow rate, while
the water supplied from the mains provided a more constant flow rate.
Both types of systems used to supply water to an integrated water
delivery system would be acceptable under the table.
NIOSH also evaluated the performance of a commercially available
water backpack and spray attachment, pre-set by the attachment
manufacturer to provide 1.4 liters per minute water consumption (0.36
gallons per minute) for handheld saws during concrete block cutting
(Document ID 0868, pp. 8, 11). The handheld electric abrasive cutter
was used outdoors to make cuts through concrete blocks laid lengthwise
on a plank 17 inches above the ground. During the 5- to 10-minute
trials with water-fed saws, the water spray attachment reduced quartz
exposures by an average of 90 percent from uncontrolled levels
(Document ID 0868, p. 10). Middaugh et al. (2012) conducted a workplace
field study to evaluate the effectiveness of dust controls on cut-off
saws (Document ID 3610, p. 158). Air sampling was conducted for 10 days
at 5 job sites on 4 experienced operators using gas-powered cutoff saws
with 14 inch (35.6mm) diameter blades to cut concrete curbs (Document
ID 3610, p. 159). Air sampling was conducted both with and without wet
methods; sampling ranged from 4 to 16 minutes and corresponded to the
entire duration of the task (Document ID 3610, pp. 159-161). With wet
suppression, the concentration of respirable silica levels was reduced
78 percent to 210 [mu]g/m\3\ (Document ID 3610, p. 162).
Based on the information in the record, OSHA concludes that most of
the time, handheld power saw operators use the saw for two hours or
less over the course of a workshift, typically using handheld saws for
brief, intermittent periods repeated numerous times over the course of
a shift (Document ID 1431, p. 3-63). The Mason Contractors Association
of America stated that "90 minutes is actually a really long time to
be cutting something. The vast majority of [cutting tasks] are under 15
minutes [total] in any given day" (Document ID 3585, Tr. 2911). The
Bay Area Roofers Waterproofers Training Center agreed, clarifying that
when cutting is performed as part of its work it is usually half an
hour to 45 minutes a day (Document ID 3581, Tr. 1598). Information
contained in research supports this as well. Thorpe et al. (1999) used
15-minute sampling durations in the study protocol because handheld
saws are typically used intermittently to make short cuts (Document ID
1181, pp. 447-448). Middaugh et al. (2012) explained that concrete
cutting in roadway construction is frequently performed with a handheld
saw, noting that "although some applications may require cutting for
an entire 8-hour workday, typical cutting is performed for less than
two hours per day" (Document ID 3610, p. 162). Sample times from the
Flanagan et al. database support this; the median time for using
handheld portable saws was 101 minutes and the range of cutting times
was from 9 to 447 minutes, indicating that saws are typically used for
only a portion of the shift, although some workers cut for longer
durations (Document ID 0677, Attachment 2).
Estimated TWA exposures (i.e., averaged over eight hours) using
task measurements from field studies may exceed 50 [mu]g/m\3\ when
workers cut with water for two or more hours per day (Document ID 3610;
4073, Attachment 8a, p. 1; 0868). Shepherd and Woskie (2013) estimated
that if typical cutting conditions (intensive cutting) were performed
outdoors with wet methods for two hours and no other exposure occurred
for the remainder of the day, 83 percent (88 out of 106) of the saw
operators' 8-hour TWA exposures would be 50 [mu]g/m\3\ or less
(Document ID 4073, Attachment 8a, p. 1). In further analysis, the
authors considered what would happen if operators used the water-fed
saws outdoors at this same level of intensity for a full 6 hours of the
shift, in which case 61 percent of operators would have 8-hr TWA
exposures of 50 [mu]g/m\3\ or less (Document ID 4073, Attachment 8a, p.
1).
In the proposal, OSHA based its requirement to use respiratory
protection for operating saws more than four hours per shift on the few
higher exposure values in its exposure profile, which indicated that
exposures would exceed 50 [mu]g/m\3\ occasionally when wet cutting with
portable saws. However, OSHA concludes that the study by Shepherd and
Woskie (Document ID 4073, Attachment 8a) as well as other material
contained in the record and discussed above provide a better basis on
which to determine the need for respiratory protection. Based on these
studies, OSHA determined that outdoor wet cutting for more than four
hours could result in more frequent exposures over 50 [mu]g/m\3\ than
are experienced with shorter task durations. Therefore, paragraph
(c)(1)(ii) of the standard for construction requires use of respiratory
protection having an APF of at least 10 for employees using a handheld
power saw of any blade diameter equipped with an integrated water
delivery system for more than four hours per shift. When cutting for
four hours or less outdoors, no respiratory protection is required.
The vast majority of samples reviewed by OSHA involve the use of
handheld saws outdoors. However, employees may occasionally use
handheld saws indoors. When an employee uses a water-based system
indoors or within enclosed areas, elevated exposures can still occur
(Document ID 0675; 0177; 0846; 3497; 3777). Data submitted by CSDA
shows that almost all indoor hand sawing using wet methods produced
exposure levels above 50 [mu]g/m\3\ (Document ID 3497, pp. 1-4, 6, 8).
Additionally, a field study of wet sawing found that an enclosed
location (in a large garage building open in front and closed on 3
sides) resulted in significantly higher exposures than when the work
was done outdoors (Document ID 3777, p. 1); a separate study found
levels as high as 240 and 260 [mu]g/m\3\ during indoor wet sawing
(Document ID 0675, p. 1098). OSHA's exposure profile contained in
Section 5.6 of Chapter IV of the FEA shows that using wet methods
indoors results in higher exposures when compared to outdoor cutting
with only 50 percent of the exposures in indoor environments being 50
[mu]g/m\3\ or less, compared to 80 percent of the outdoor wet sawing
samples. Although wet methods substantially reduce operator exposures
compared to uncontrolled dry cutting indoors, elevated exposures still
occur routinely. To reduce these exposures, OSHA is requiring that work
done indoors or in enclosed areas have additional general ventilation
such as exhaust trunks, fans, air ducts or other means of forced air
ventilation to prevent the accumulation of dust in the work area.
Accordingly, for indoor work, paragraph (c)(1)(ii) requires the use
respiratory protection with an APF of 10 regardless of task duration.
Representatives from the roofing industry expressed concern
regarding the use of wet methods in their industry, citing primarily
the potential increase in slips and falls from introducing water to
elevated worksites (Document ID 2320, p. 116; 2192, p. 4; 3526, p. 7).
The Tile Roofing Institute stated that in California and Arizona,
rooftop operations with roofing tiles or pavers are given an exemption
from the requirement to use a dust reduction system because there is no
way to address both the silica and fall protection hazard (Document ID
3587, Tr. 3595). Conversely, testimony from the public hearings
indicates that wet dust control systems can be used to reduce exposures
to silica during cutting of roofing tiles and pavers. Dan Smith,
director of training for the Bay Area Roofers and Waterproofers
Training Center, testified that the roofing industry in California is
starting to voluntarily cut roofing tiles and pavers wet (Document ID
3581, Tr. 1600-1601; 1638) and that use of controls may actually
increase visibility, thereby reducing a potential fall hazard (Document
ID 3581, Tr. 1603-1604). He also explained that dry cutting of roofing
tiles is prohibited in the U.K., and that the contractors association
(the National Federation of Roofing Contractors), "...provides
guidance and training. They use wet saws on scaffolding at the roof
level...they use a [water] mister on the tile saw. They use a
system like the hytile...which is a tile breaking tool" (Document
ID 3581, Tr. 1601).
OSHA understands the concerns expressed by representatives from the
roofing industry regarding the use of wet methods and increased risk
for falls; however, OSHA concludes that alternate project planning can
enable employers to use wet methods by implementing some of the
measures described above.
In the proposed rule, OSHA included an option under Table 1 for the
use of LEV when using portable masonry saws. While including LEV as an
alternative to wet methods in the table was supported by both labor and
industry groups (Document ID 2296, p. 32; 4223, p. 140; 4233,
Attachment 1, p. 1), OSHA has removed this option from Table 1 based on
information contained in the record indicating that LEV cannot
consistently maintain exposure at or below a TWA exposure level of 50
[mu]g/m\3\ (see Section 5.6 of Chapter IV of the FEA). OSHA is not
prohibiting use of LEV for dry cutting, as LEV may be effective in
reducing exposure to or below 50 [mu]g/m\3\ in situations where, for
example, saw use is intermittent. Employers who choose to do so may
still use LEV in lieu of an integrated water system; however, those
employers would be required to comply with the PEL and exposure
assessment requirements under paragraph (d) of the standard for
construction.
Handheld power saws for cutting fiber-cement board (with blade
diameter of 8 inches or less). These specialized saw configurations
consist of blades (with four to eight teeth) specifically designed for
cutting fiber-cement board (see Section 5.6 of Chapter IV of the FEA)
(Document ID 2322, p. 9; 2322, Attachment B, p. 8). The blades are
fitted to a circular saw (or occasionally to other saws) with dust
reduction systems (Document ID 2322, p. 9; 2322, Attachment B, p. 36).
These saws have been specifically designed and tested by a member of
the fiber-cement siding industry and by NIOSH for controlling the
silica exposure of installers who perform cutting in that industry, and
the saw is intended specifically for use on fiber-cement board
(Document ID 2322, pp. 5, 9; 2322 Attachment B, pp. 33, 36).
When using handheld power saws with a blade diameter of 8 inches or
less for cutting fiber-cement board outdoors, paragraph (c)(1)(iii) of
the standard for construction requires saws to be equipped with a
commercially available dust collection system that provides the air
flow recommended by the manufacturer and a filter with a 99 percent or
greater efficiency, operated in accordance with the manufacturer's
instructions to minimize dust emissions. OSHA is not providing an entry
for use of these saws indoors on Table 1 because fiber-cement board,
used as siding and fascia applied to the exterior of buildings, is
usually cut outdoors and the record lacks information on exposures to
silica that would result from cutting fiber-cement board indoors.
Therefore, employers who choose to operate saws to cut fiber-cement
board indoors must conduct exposure assessments and comply with the PEL
in accordance with paragraph (d) of the standard for construction.
This entry was added to Table 1 of the final standard for
construction in response to comments NIOSH and the fiber-cement board
industry submitted to the rulemaking record. These submissions provided
substantial data on control technology (a specially configured saw) for
controlling silica exposure when saw operators cut fiber-cement board
(Document ID 2177, Attachment B, pp. 17-19; 2322, Attachment B-E and
H).
The James Hardie Building company submitted 75 samples for workers
using specially configured circular saws (with specialty blades of less
than 8 inches) for cutting fiber-cement board with LEV (Document ID
2322, pp. 19-20). These saws were all fitted with cutting blades
designed for the fiber-cement board product and some form of dust
collector (but not always designed with vacuum suction). Workers using
these saws had a mean 8-hour TWA exposure of 11 [mu]g/m\3\ (median 7
[mu]g/m\3\), although elevated exposures (maximum exposure of 76 [mu]g/
m\3\) occurred with some saw/control configurations that proved less
reliable (for example, saws attached to a dust receptacle, without the
benefit of a vacuum dust collection device) (Document ID 2322, pp. 19-
20). Although the cutters sawed fiber-cement board products containing
15 to 50 percent silica, the respirable dust collected in the samples
was 0 to 12 percent silica and percentages in the lower half of that
range were most typical (Document ID 2322, Attachment D, pp. 5-10;
2322, Attachment E, pp. 5-9; 2322, Attachment F, pp. 5-10). Most of the
sawyers for whom exposures were elevated cut siding for approximately
half the shift (four to five hours), a duration representative of
typical cutting activities during a normal day of fiber-cement siding
installation (Document ID 2322, Attachment D, p. 16; 2322, Attachment
E, p. 16; 2322, Attachment F, p. 18). Several NIOSH reports demonstrate
that this and other saw configurations are effective in achieving
exposures of 50 [mu]g/m\3\ or below when the saw is used with a vacuum
dust collector (Document ID 4138; 4139, p. 11; 3998, Attachment 4a;
3998, Attachment 4b; 3998, Attachment 4c).
Based on the evidence in the record, commercially available dust
collection systems for handheld power saws with a blade diameter of 8
inches or less and a dust collection device providing the air flow
recommended by the manufacturer have been demonstrated to be
particularly effective in controlling silica during outdoor cutting of
fiber-cement board. One type of saw evaluated was a handheld, dust
collecting model equipped with dust collection device rated at 200 cfm
over a 7.25-inch-diameter blade (27.5 cfm per inch); however, the
measured flow rate was reported to be 69 to 106 cfm. Using this
configuration, all 21 exposure samples taken for siding cutters on
construction sites were 41 [mu]g/m\3\ TWA or less (20 sample results
were less than 25 [mu]g/m\3\) while cutting a variety of fiber-cement
board siding products containing up to 50 percent silica
(Document ID 3998, Attachment 4a; 3998, Attachment 4b; 3998,
Attachment 4c; 4138; 4139). Accordingly, OSHA is requiring in paragraph
(c)(1)(iii) that dust collectors be used with saws when cutting
fiber-cement board.
Based on the evidence in the record, OSHA is not requiring the use
of respiratory protection when employees are using handheld power saws
with a blade diameter of 8 inches or less, for cutting fiber-cement
board outdoors in accordance with Table 1 for any task duration. OSHA
has determined that in such circumstances, employee exposures will be
reduced to 50 [mu]g/m\3\ or less when the controls specified for this
task on Table 1 are fully and properly implemented.
Walk-behind saws. When using walk-behind saws (see Section 5.6 of
Chapter IV of the FEA), paragraph (c)(1)(iv) of the standard for
construction requires that saws be equipped with an integrated water
delivery system that continuously feeds water to the blade and that the
tool be operated and maintained in accordance with manufacturer's
instructions to minimize dust emissions. OSHA is specifying that the
saws be used with an integrated water feed system because the Agency
has identified this as the most effective means of reducing exposures
to respirable crystalline silica. This requirement is essentially the
same as was proposed for the entry "Using Portable Walk-Behind and
Drivable Masonry Saws." As explained below, requirements in the final
rule for drivable saws have been separated from those for walk-behind
saws.
Saw designs vary among manufacturers, and as with other operating
parameters, recommendations for optimizing wet methods are likely to
vary somewhat with the saw size and design. As with other saws, OSHA is
not specifying a minimum flow rate, but rather anticipates that the
water flow rates specified by the manufacturer will optimize dust
reduction. OSHA recognizes that the employer's best available
information for reducing dust with a specific control comes from the
manufacturer's operating instructions, which is why OSHA is requiring
the saw be operated and maintained according to the manufacturer's
instructions to minimize dust. Water-fed walk-behind saws (manual and
self-propelled) are widely available from many manufacturers and
construction tool distributors, such as Grainger, EDCO, MK Diamond, and
CS Unitec (Document ID 0715; 1676; 1185; 0643; 0615).
CSDA stated that "nearly 100% of CSDA contractors use water on
each and every job and this has to do with extending the life of the
expensive diamond tools. The use of water has an additional benefit of
containing silica particles that could become airborne" (Document ID
3496, p. 3). This was supported by others during the public hearings
(Document ID 3580, Tr. 1438; 3585, Tr. 2885) and in written comments
(Document ID 2316, p. 3). Disagreeing, both SMI and the Mason
Contractors Association of America commented that most water-fed
systems are designed to keep the blade cool, and their ability to
suppress dust has not been sufficiently researched (Document ID 2316,
p. 3; 3585, Tr. 2885). CISC similarly asked whether an additional water
feed is needed for these saws or whether the one currently integrated
for the purpose of cooling the saw will suffice (Document ID 2319, p.
104).
OSHA finds that considerable evidence in the record shows that
water application reduces dust emissions, and several saw manufacturers
state that using wet cutting will suppress dust (see discussion about
requirements for water delivery systems above). Furthermore, the water
delivery system described in Linch (2002) was for the purpose of
cooling or protecting the blade, but was effective in suppressing
respirable silica levels to below 50 [mu]g/m\3\ (Document ID 0784, p.
216). CSDA submitted exposure data collected during slab sawing with
saws "equipped with water supply," presumably for blade cooling.
Those data show that of 26 measurements of silica concentrations taken
during outdoor work, 21 (80 percent) were less than 25 [mu]g/m\3\, and
only one sample (65 [mu]g/m\3\) exceeded 50 [mu]g/m\3\ (Document ID
3497, pp. 2-4). Therefore, OSHA concludes water provided as coolant can
also control silica exposure.
CISC questioned the feasibility of using wet methods in situations
where there is no established water main on site (Document ID 2319, p.
112). OSHA finds that water tanks, which were used to provide water to
the walk-behind saws in Linch (2002), are already commonly available on
many construction sites and could provide water for a walk-behind saw
(Document ID 0784, pp. 216-217).
Data contained in the record show that none of the respirable
silica results associated with wet cutting outdoors using walk-behind
saws exceeds 50 [mu]g/m\3\, with the majority of these results being
less than or equal to the limit of detection (Document ID 0784, pp.
216-217). These results were obtained using the saw's normal water feed
system intended for cooling the blade. Therefore, OSHA has determined
that no respiratory protection is required when working outdoors with a
walk-behind saw for any task duration.
Since walk-behind saws are used to cut pavement, they are most
commonly used outdoors, though they can also be used indoors (Document
ID 1431, pp. 3-63). Although the data are limited, water-fed walk-
behind saws used indoors or in enclosed areas may result in higher
exposures than those measured outdoors. Studies by both NIOSH and
Flanagan et al. (2001) noted the potential for elevated exposure when
walk-behind saws with continuous water application are used indoors,
with Flanagan et al. reporting four 8-hour TWA sample results between
65 to 350 [mu]g/m\3\ for four to seven hours of work (Document ID 4233,
Attachment 1, p. 10; 0675, pp. 1098-1099). Additionally, the CSDA
report submitted to the record shows the only exposure result from
indoor slab sawing exceeded 50 [mu]g/m\3\ despite the use of equipment
with water supply (Document ID 3497, pp. 2-4). These results indicate
that the source for the elevated exposure is likely due to the build-up
of respirable aerosol within the enclosed space, rather than direct
exposure to slurry spray (Document ID 0675, p. 1099). While OSHA
anticipates that the results for indoor sawing can be reduced by
minimizing the build-up of dust with supplemental ventilation as
required under paragraph (c)(2)(i) of the rule, OSHA is unable to
conclude that exposures can be consistently reduced to 50 [mu]g/m\3\ or
less for this task when performed indoors. Therefore, when used indoors
or in an enclosed area, OSHA is requiring the use of respiratory
protection with an APF of 10 regardless of task duration.
Drivable saws. Paragraph (c)(1)(v) of the standard for construction
requires that, when using drivable saws to cut silica-containing
materials, the saw must be equipped with an integrated water delivery
system that continuously feeds water to the blade and that the tool be
operated and maintained in accordance with the manufacturer's
instructions to minimize dust emissions. Drivable saws include those
where the operator typically sits in a cab (open or enclosed) away from
the pavement cut point, guiding the saw to make long cuts such as are
common for utility installation along roadways. These saws are
cumbersome to move and are typically only used when making long cuts.
The blade housed by the vehicle can be large (e.g., 8 feet in diameter
and 2 inches thick) and is usually equipped with a water-fed system
to cool the blade (Document ID 1431, pp. 3-63--3-64). The requirement
to use integrated water systems on drivable saws is unchanged
substantively from the proposal.
In its Technological Feasibility analysis (see Section 5.6 of
Chapter IV of the FEA), OSHA analyzes exposures for workers using
drivable saws. The exposure profile includes three samples, two using
wet methods as required by Table 1 and one operating under other
conditions. The two samples taken on workers using wet saws showed TWA
silica exposures of 12 [mu]g/m\3\ (i.e., below the limit of detection
(LOD)) and 33 [mu]g/m\3\ over sampling times of 70 and 125 minutes,
respectively. OSHA considers these exposure results to reflect typical
work patterns in that operators will often operate the saw for one or
two hours before moving the saw to another location. CISC questioned
OSHA's use of short term samples and the assumption of zero exposure
during the unsampled portion of the shift and noted that this could
underestimate the exposures for these workers (Document ID 2319, pp.
51-52). While OSHA acknowledges that this situation may occur at times,
there is no evidence that this is the case for these drivable saws
samples. These samples were collected by OSHA inspectors, who are
instructed to sample for the entire duration of silica exposure.
Accordingly, OSHA concludes that these samples accurately characterize
the sampled workers' exposure.
In the proposed rule, dust control requirements were specified for
drivable and walk-behind saws together, and the proposed rule would
have required respirator use when operating either saw in indoor or
enclosed environments. In the final standard for construction, the
requirements for these kinds of saws are separated on Table 1 because,
unlike walk-behind saws, drivable saws are rarely, if ever, used in
indoor environments. Because the requirements of Table 1 only apply to
outdoor use of drivable saws, and the data available to OSHA
demonstrate that the wet methods described above can consistently
control exposures in that environment, Table 1 does not require the use
of respiratory protection when these controls are implemented,
regardless of task duration.
SMI and CISC commented that currently drivable saws use water to
cool the cutting tool, and the effectiveness of cooling water for
respirable crystalline silica dust mitigation has not been
comprehensively researched (Document ID 2316, Attachment 1, p. 3; 2319,
p. 112). SMI stated specifically that "parameters such as flow rate,
volume, flow delivery characteristics, velocity, and delivery location
have not been evaluated or compared" (Document ID 2316, p. 3).
However, Atlantic Concrete Cutting agreed that all of its cutting
services were performed with water (Document ID 2367, p. 2), and that
the application of water minimized and most likely eliminated exposure
to respirable crystalline silica. Atlantic Concrete Cutting also stated
that the use of a "water-fed system that delivers water continuously
at the cut point" would be an appropriate silica dust control for
drivable saws and that respirators would not be needed to further
protect employees (Document ID 2367, pp. 2-4). In light of this
testimony, OSHA concludes that it is appropriate to permit employers to
fully and properly implement water-based systems on drivable saws in
compliance with Table 1, eliminating their need to conduct exposure
assessments for employees engaged in a task using drivable saws.
Moreover, as reflected in Table 1, OSHA concludes that full and proper
implementation of this control will not require the use of respirators
for this task even if performed for more than four hours in a shift and
so has not included respiratory protection for this task.
Rig-mounted core saws or drills. Paragraph (c)(1)(vi) of the
standard for construction, an entry for rig-mounted core saws or
drills, was not included in proposed Table 1. Core saws or drills are
used to perform core cutting (also called core drilling, boring, or
concrete coring) to create round holes for pipes, ducts and conduits to
pass through walls, ceilings and floor slabs made of concrete, masonry
or other materials that may contain silica (see Section 5.6 of Chapter
IV of the FEA). Core cutting machines (also called core drills) use a
thin continuous round cutting surface on the round end of a cylindrical
coring tool ("bit") (Document ID 0679, pp. 18-20). The machine is
typically attached to the surface being drilled (bolted on via a rig
for stability) (Document ID 3998, Attachment 13e, pp. 4, 9). When the
rotating diamond core cutting bit is applied to solid material, the bit
cuts away a thin circle of material. The cut separates the central
"core" of material, within the circumference of the bit, from its
surroundings, leaving the core generally intact as it is removed from
the hole (Document ID 3501, p. 6). The cylindrical bit can range in
size; for example NIOSH described a coring operation used to produce
holes 2 to 31 inches in diameter in large sections of concrete conduit
(Document ID 0898, p. 6).
For rig-mounted core drills, there is one specified control that
consists of using a tool equipped with an integrated water delivery
system that supplies water to the cutting surface, operated and
maintained in accordance with manufacturer's instructions to minimize
dust emissions. Based on evidence in the record, OSHA has determined
that baseline conditions for core cutting involve using wet methods and
that most core cutting machines are provided with and intended to be
used with a water feed system (e.g., Document ID 0675, p. 1097; 0679,
pp. 18-21; 0898, p. 6; 3580, Tr. 1415, 1435; 3581, Tr. 1584; 3585, Tr.
2902). Like other saws included in Table 1, these existing systems will
fulfill the requirements of Table 1.
Comments submitted by SMI expressed confusion as to whether or not
core drilling was included on the table under the entry for drills and
the appropriateness of using LEV as required under the proposed table
during core cutting (Document ID 2316, p. 2). In the proposed rule,
OSHA specifically excluded core cutters from hole drillers using
handheld drills (see PEA, p. IV-403). OSHA did not include this
information because OSHA lacked specific information on exposures to
silica that result from core drilling or from industry's practice of
using water during coring operations. Upon OSHA's review of core
cutter/driller operator exposures and hearing testimony from industry,
OSHA determined that there is the potential for silica exposure when
employing core saws and that these saws are different enough from other
drills and cutting tools to warrant the inclusion of its own separate
entry on Table 1.
Kellie Vasquez of Holes Incorporated testified that the process of
core drilling is much different than other types of drilling due to the
different drill bits used, resulting in much less silica exposure
(Document ID 3580, Tr. 1484). This is supported by OSHA's review of
record data on core cutting/drilling, which shows that operators
generally experience little or no silica exposure during this low-speed
process, which is already performed using water-fed equipment as a
standard practice (Document ID 0675, pp. 1097-1098; 0898, p. 15).
Additional exposure data compiled by CSDA from member jobsites
(Document ID 3497) and other studies (Document ID 0675; 0679; 0898)
show that using a core drill with wet methods results in exposure levels
of less than 50 [mu]g/m\3\ (Document ID 3497). During hearing testimony,
BCTD commented that core drills are always used with wet methods
(Document ID 3581, Tr. 1584). This was supported by Kellie Vasquez of
Holes Incorporated who stated that her concrete cutting operations employ
water 100 percent of the time (Document ID 3580, Tr. 1483). Accordingly,
OSHA added dust control specifications for core sawing and drilling to
Table 1 of the final standard for construction. Because the available
evidence described above demonstrates that using wet dust suppression
systems for core cutting does not result in silica exposures exceeding
50 [mu]g/m\3\, the final standard for construction does not require the
use of respiratory protection.
Handheld and stand-mounted drills (including impact and rotary
hammer drills). Handheld drills are used to, among other tasks, create
holes for attachments and small openings in concrete and other silica
containing materials (see Section 5.4 of Chapter IV of the FEA). These
drills can: (1) Be electric, pneumatic, or gas-powered; (2) use rotary
hammers or percussion hammers; and (3) be free-standing or stand-
mounted. Handheld drills consist of a handle with a trigger button to
begin drilling, a motor compartment above and perpendicular to the
handle, and a socket to insert drill bits of varying lengths and styles
at the end of the motor compartment. Impact and rotary hammer drills
appear the same, but provide the ability to drill with extra motor-
generated impacts and/or torque. The drills may have a second handle in
front of the main handle for a worker to grasp with the off hand. To
control dust, they may contain attachable dust collection systems where
the end of the drill bit is surrounded by a vacuuming compartment which
connects to the rest of the drill, allowing for dust to be removed
while drilling (Document ID 4073, Attachment 4a, Row 68). Handheld
drills can also be stand-mounted, in which case a drill is turned on
its side and mounted to an adjustable stand, allowing the worker to
drill directly into a work product with precision (Document ID 4073,
Attachment 4a, Row 72).
Paragraph (c)(1)(vii) of the standard for construction requires
that handheld and stand-mounted drills be equipped with a commercially
available shroud or cowling with dust collection system that provides
at least the minimum air flow recommended by the manufacturer. The dust
collection system must include a filter cleaning mechanism and be
equipped with a filter with 99 percent or greater efficiency. The dust
collection system must be operated in accordance with the
manufacturer's instructions to minimize dust emissions. In addition,
OSHA is requiring that a HEPA-filtered vacuum be used when cleaning
debris from drill holes.
The proposed Table 1 labeled this category of tools "Using rotary
hammers or drills (except overhead)." In response to several comments,
OSHA has revised this description to make clear that drills mounted on
stands are also included and also removed the exclusion for overhead
drilling. For example, SMACNA recommended expanding the entry for
rotary hammers and drills to include overhead drilling, contending that
overhead drilling would be just a safe as other drilling if done as
directed on the table (Document ID 2226, p. 2). The Mechanical
Contractors Association of America commented that overhead drilling
should be included in Table 1 since overhead drilling is a common
operation in several trades (Document ID 2143, p. 2). OSHA received
testimony that overhead drilling along with a drill stand with a vacuum
attachment addresses both ergonomic and silica exposure hazards. After
review of the evidence in the record, OSHA has determined that it is
appropriate to remove the exclusion for overhead drilling in the Table
1 entry for handheld and stand-mounted drills.
As proposed, Table 1 had separate entries for "Rotary Hammers or
Drills" and "Jackhammers and Other Impact Drillers." OSHA received
comments from PTI suggesting that impact drills be covered by the entry
for "Rotary Hammers or Drills," rather than by the "Jackhammers and
Other Impact Tools" entry (Document ID 1973, Attachment 1, p. 4).
NIOSH also commented on the potential for confusion, noting that a
rotary hammer or drill is technically an impact driller (Document ID
2177, Attachment B, pp. 32-33). Therefore, the entry for handheld or
stand-mounted drills in final Table 1 covers activities related to the
use of impact and rotary hammer drills. Chipping and breaking
activities, which are associated with more intense silica exposures,
are covered by the entry for jackhammers and handheld power chipping
tools.
CISC commented that OSHA did not state in the proposed rule that
the dust collection system needs to be "commercially available"
(Document ID 2320, p. 112). In the final standard for construction,
OSHA has clarified that Table 1 requires that the handheld or stand-
mounted drill be equipped with a commercially available shroud or
cowling with dust collection system. Several drilling equipment
manufacturers sell dust extractors or dust collectors to minimize dust
escaping into the work area. These systems include a vacuum with a
filter cleaning mechanism and a filter with 99 percent or greater
efficiency. Some examples include Bosch, DeWalt, Hilti, and Metabo
(Document ID 3998, Attachment 10; 4073, Attachment 4a, Rows 15-18, 64-
70, 111-119, 189-195, 289-301, 352-357). OSHA has determined that it is
feasible for employers to obtain controls for handheld and stand-
mounted drills that meet the specifications in Table 1.
Based on evidence in the record, OSHA finds that, for most tools, a
commercial dust control system using an appropriate vacuum will provide
the most reliable dust capture. Average respirable quartz levels varied
among the different cowling/vacuum combinations. In one study, all
commercial cowl/vacuum combinations tested resulted in personal
breathing zone exposures of 28 [mu]g/m\3\ or less during drilling
(Document ID 1142, p. 42). Another study reported median silica
exposures of 60 [mu]g/m\3\ and 45 [mu]g/m\3\, depending on drill bit
size, in a room with limited air exchange (Document ID 1391, pp. 11-12,
15-19). These findings indicate that providing a means of exhaust when
working indoors or in enclosed areas, as required under paragraph
(c)(2)(i) of the standard for construction, in addition to using dust
collection systems, will maintain exposures below 50 [mu]g/m\3\. Based
on these findings, OSHA is not requiring the use of respiratory
protection when using handheld or stand-mounted drills, including
overhead drilling, for any task duration.
The practice of dry sweeping or brushing debris from a hole, or
using compressed air to clean holes, contributes to the exposure of
employees using drills. Based on the evidence in the record, OSHA is
requiring that holes be cleaned with a HEPA-filtered vacuum. Any method
for cleaning holes can be used, including the use of compressed air, if
a HEPA-filtered vacuum is used to capture the dust. If a HEPA-filtered
vacuum is not used when cleaning holes, then the employer must assess
and limit the exposure of that employee in accordance with paragraph
(d) of the standard for construction.
While the paragraph on housekeeping (paragraph (f) of the standard
for construction) also applies when employers are following paragraph
(c) of the standard for construction, the employer must ensure that all
of the engineering controls and work practices specified on Table 1 are
implemented. For example, paragraph (f)(2)(i) of the standard for
construction permits the use of compressed air when used in conjunction
with a ventilation system that effectively captures the dust cloud.
However, to fully and properly implement the controls on Table 1, an
employer using compressed air when cleaning holes during tasks using
handheld or stand-mounted drills or dowel drilling rigs for concrete must
use a HEPA-filtered vacuum to capture the dust, as specified in paragraphs
(c)(1)(vii) and (viii) of the standard for construction, not just a
ventilation system as specified in paragraph (f)(2)(i) of the standard
for construction.
PCI noted that anchor holes must be blown clean to obtain adequate
adhesion, and recommended that the use of compressed air and dry
sweeping be allowed unless exposures will exceed 50 [mu]g/m\3\
(Document ID 2276, pp. 10-11). This recommendation assumes exposure
assessment, however, the construction standard does not require such
assessment where the task is included in Table 1 and the employer is
following Table 1. Although OSHA is allowing the use of compressed air
if used in conjunction with a HEPA-filtered vacuum to capture the dust,
OSHA has determined that there are a number of feasible alternatives to
using compressed air. At least one tool manufacturer offers an anchor
system with "no hole cleaning requirement whatsoever," due to the use
of a drill with a ventilated drill bit (Document ID 4073, Attachment
4b, Slide 12). Another manufacturer offers a "hole cleaning kit" for
large hammer hole drilling, which consists of a doughnut-shaped dust
collection head that attaches directly to a vacuum cleaner hose. The
head is placed against the surface to be drilled and captures dust
generated as the hole is drilled (Document ID 4073, Attachment 4b,
Slide 17). This hole cleaning kit also includes two sizes of hole
cleaning tubes. Such a control could be used with existing as well as
new drills (e.g., Document ID 3998, Attachment 10, p. 42).
Data suggest that decreasing employees' reliance on blowing or dry
sweeping drilling debris can reduce exposures by approximately 50
percent (e.g., Document ID 1391, pp. 32-33). This 50 percent reduction
would bring exposure levels to 50 [mu]g/m\3\ or below for all the drill
operators who are currently exposed to silica at levels between 50
[mu]g/m\3\ and 100 [mu]g/m\3\. Thus, OSHA has determined that a HEPA-
filtered vacuum must be used when cleaning holes in order to reduce
silica exposure.
Dowel drilling rigs for concrete. Paragraph (c)(1)(viii) of the
standard for construction covers dowel drills (i.e., gang drills),
which are drills with one or more drill heads used to drill holes in
concrete for the placement of steel supports (see Section 5.9 of
Chapter IV of the FEA). When operating dowel drills, Table 1 requires
that the rig be equipped with a shroud around the drill bit and a dust
collection system that has a filter with 99 percent or greater
efficiency. In addition, Table 1 requires that dust collection
equipment be equipped with a filter cleaning mechanism.
NIOSH found that employees using compressed air to clean the filter
after dowel drilling resulted in some of the highest measured exposure
to respirable dust during the task, and could cause damage to the
filter (Document ID 4154, p. 26). NIOSH also pointed out that the
reverse pulse feature on the dust collector should preclude the need to
remove filters for cleaning (Document ID 4154, p. 26). OSHA agrees and
has included the specification for a filter cleaning mechanism for
dowel drills in Table 1. Finally, Table 1 requires that a HEPA-filtered
vacuum is used when cleaning holes. OSHA recognizes that it may be
necessary at times for employers to use compressed air to clean holes,
and thus, as with handheld and stand-mounted drills, Table 1 does not
preclude its use when cleaning the debris from holes caused by dowel
drilling, so long as a HEPA-filtered vacuum is employed at the same
time to effectively capture the dust.
In the proposed rule, OSHA included dowel drills within the entry
titled "Operating Vehicle-Mounted Drilling Rigs for Concrete."
However, OSHA has determined that the exposures that result from dowel
drilling rigs equipped with LEV systems are substantially higher than
is the case for vehicle-mounted concrete drilling rigs. Therefore,
respirator requirements are different for the two kinds of equipment
(see Sections 5.4 and 5.9 of Chapter IV of the FEA).
Exposure information on concrete dowel drilling in the record is
limited but shows that, even with LEV, exposures are likely to exceed
50 [mu]g/m\3\. Exposure studies by NIOSH on concrete dowel drills,
manufactured by both EZ Drill and Minnich Manufacturing, that were
equipped with close capture hoods and a dust collection system showed
that workers were often still exposed to respirable silica dust levels
well above 50 [mu]g/m\3\, with 8-hour TWA exposures to respirable
quartz ranging from 24 to 420 [mu]g/m\3\ with a geometric mean of 130
[mu]g/m\3\ (Document ID 4154, p. 25). NIOSH found that using an air
lance and compressed air to clean holes and to clean the filter and
hoses of the dust collector contributed to these high exposures, and
NIOSH recommended the use of a pneumatic vacuum to clean holes and
components of the dust collector (Document ID 4154, p. 26). The record
contains no information on exposures that result when vacuums are used
to clean holes. As stated previously, exposures that result from dowel
drilling rigs equipped with LEV systems are substantially higher than
is the case for vehicle-mounted concrete drilling rigs. Based on this
information, OSHA has modified the respirator requirement for dowel
drilling, and is requiring the use of respiratory protection with a
minimum APF of 10 regardless of task duration.
Comments on OSHA's proposed requirements for dowel drilling were
limited. Holes Incorporated, Atlantic Concrete Cutting and CISC all
stated that outdoor concrete dowel drilling should be included on Table
1 (Document ID 2338, p. 3; 2320, p. 14; 2367, p. 4). Atlantic Concrete
Cutting further suggested that the appropriate control for dowel
drilling is to limit this task to outdoors only and "provide
sufficient ventilation" (Document ID 2367, p. 4). As suggested, OSHA
has included a separate entry for concrete dowel drilling on Table 1,
but with more detailed control requirements than suggested by Atlantic
Concrete Cutting based on information contained in the record. OSHA
agrees with Atlantic Concrete Cutting that the entry on Table 1 should
be limited to outdoor operations since there is no information in the
record as to the appropriate level of respiratory protection needed
when operating dowel drills in enclosed areas, and has accordingly
revised Table 1 of the final rule to so indicate.
PCI commented that anchor holes must be blown clean using
compressed air to obtain adequate adhesion (Document ID 2276, p. 10).
In its feasibility analysis, OSHA identified this task as a significant
source of exposure to respirable crystalline silica. Therefore, for the
reasons previously stated, Table 1 also includes a requirement to use a
HEPA-filtered vacuum when cleaning holes, with or without the use of
compressed air, in connection with this task.
Vehicle-mounted drilling rigs for rock and concrete. Paragraph
(c)(1)(ix) of the standard for construction requires that vehicle-
mounted rock and concrete drilling rigs be equipped with a dust
collection system with a close capture hood or shroud around the drill
bit with a low-flow water spray to wet the dust discharged from the
dust collector, or be operated from within an enclosed cab in
conjunction with water applied at the drill bit for dust suppression
(see Section 5.9 of Chapter IV of the FEA). The specifications of
paragraph (c)(2)(iii) of the standard for construction apply to the
cabs.
The proposed rule had separate entries for vehicle-mounted drilling
rigs for rock and vehicle-mounted drilling rigs for concrete, both of
which specified a combination of LEV and water use. OSHA has determined
that, since the rigs and the approach to dust control are similar for
both, they can be combined in Table 1 of the final standard for
construction. OSHA has also determined that it is appropriate to allow
employers the option of having the drill operator work within an
enclosed cab meeting the requirements of paragraph (c)(2)(iii) of the
standard for construction and to apply water at the drill bit to ensure
that the operator and other employees assisting are protected when
working near the drill bit.
Workers using vehicle-mounted drilling rigs position and operate
the drill rigs from control panels mounted on the rigs. These workers
may also perform intermittent tasks near the drilling point such as
fine-tuning the bit position, moving debris away from the drill hole,
and working directly or indirectly with compressed air to blow debris
from deep within the holes. Workers using drilling rigs can be exposed
to dust generated by the action of the drill bit and from dust raised
by air movement or a compressed air nozzle. Although rig-based drilling
is often a one-person job, some of the associated activities, such as
fine-tuning the drill position and clearing debris from in or around
the holes, can be performed by a second worker (Document ID 0908, p. 1;
1563, p. 3).
In the proposed rule, OSHA specified requirements for the dust
collections systems regarding smooth ducts, transport velocities,
clean-out points, pressure gauges, and activation of the LEV. These
requirements came from a NIOSH evaluation of control technology for
dowel-pin drilling (Document ID 1628). The final rule does not require
these specific control parameters for vehicle-mounted drilling rigs for
rock and concrete. OSHA has determined that dust controls for dowel
drilling rigs are substantially different than vehicle-mounted rock and
concrete drilling rigs; they are addressed separately in the previous
section. Dust collection systems that use a hood or shroud around the
drill bit have been proven effective in reducing exposures to
respirable crystalline silica. NIOSH found that, when used properly,
modern shroud designs now help achieve dust control objectives more
consistently for rock drilling rigs than in the past (Document ID 0967,
pp. 5-9). Based on information contained in the record, OSHA finds that
dust collectors and shrouds are commercially available (Document ID
0669; 0813).
Although the LEV system will control dust emissions at the drill
bit, there are still dust emissions at the dust collector discharge
area, which can contribute to either the operator's or other employees'
exposures. Organiscak and Page (1995) found that enclosing the dust
collector discharge area with a shroud can reduce respirable dust
levels by 80 percent (Document ID 3613, p. 11). However, evidence in
the record shows that the combination of LEV at the drill bit and water
application will be more effective in that water can be used to control
dust emission points where drilled material is discharged. Organiscak
and Page (1995) illustrated the effectiveness of combined wet methods
and dust collectors in their U.S. Bureau of Mines study, which compared
rock drilling using LEV with and without the addition of water for dust
suppression. The addition of wet methods to the LEV system showed a 92
percent reduction in respirable dust and eliminated nearly all of the
visible dust. Quartz results decreased from 143 [mu]g/m\3\ when the
water was off (LEV alone) to 9 [mu]g/m\3\ when water was added. OSHA
obtained sample results of 54 [mu]g/m\3\ and 35 [mu]g/m\3\ during an
inspection for two workers drilling in granite that contained 30-40
percent crystalline silica (Document ID 0034, pp. 8, 23-26, 35-38).
Both drillers were reportedly using water and LEV, although specific
details about the configuration of the controls were not discussed
(Document ID 0034, pp. 23, 89-93). A third sample that was below the
limit of detection for crystalline silica was collected on the same
site for a laborer who helped with positioning the drills (Document ID
0034, pp. 39-42).
OSHA received many comments related to the proposed requirements
for rock and concrete drillers. CISC noted that it is more common to
use wet methods when operating vehicle-mounted drilling rigs for rocks
as opposed to using dust collection systems (Document ID 2319, pp. 108-
109). A number of other commenters noted the prevalence of wet methods
use in the industry (e.g., Document ID 1983, pp. 1-2; 2116, Attachment
1, p. 33; 3496, p. 6). For instance, CSDA commented that nearly 100
percent of CSDA contractors use water on every job in order to prolong
the life of the diamond blade (Document ID 3496, p. 6). The National
Ground Water Association (NGWA) noted that it is industry practice when
drilling water wells to use foam as a wet control method:
Industry practice is to use the engineering control of soap
injection where water is mixed with foam. The foam mixtures of water
and foam products are effective in mitigating the hazard of dust
when properly used as they can carry particles ranging from .03 mm
to the size of a quarter. There are multiple manufacturers of the
foam products and these products have been approved for use when
drilling sanitary water wells. The foam agents are NSF approved and
have also been approved for use in many states (Document ID 1983,
pp. 1-2).
NGWA also explained that all rotary drilling machines have been
equipped with some type of water injection system since the early 1970s
(Document ID 1983, p. 2).
Historically, construction and mining investigators have reported
dust control efficiencies of 96 to 98 percent through the routine use
of wet dust suppression methods, depending on the methods used;
however, the water flow necessary for dust control can create problems
under certain working conditions (e.g., moisture shortening the life of
certain drill bits (such as tricone roller bits), high-pressure water
causing spalling of the drill hole wall) (Document ID 0967, p. 6).
Advances in recent decades have produced equipment that permits workers
to use wet methods in a wider range of circumstances. New "water
separator sub" designs extend bit life beyond the previous norm and
reduce spalling in a variety of rock types (Document ID 0967, p. 6).
Several commenters stated that wet methods are used frequently and are
effective in controlling dust (Document ID 1983, pp. 1-2; 3580, Tr.
1435; 3496, p. 6).
OSHA's exposure profile contains five sample results for workers
using wet methods with no other controls while drilling. These five
samples have a mean of 24 [mu]g/m\3\ and a median of 17 [mu]g/m\3\,
with a high exposure of 57 [mu]g/m\3\ and two results below the LOD
(Document ID 0034; 0226). A review of studies by NIOSH (2008) evaluated
the use of wet methods in different types of drilling, including roof
bolting (rock bolting) and surface rock drilling (Document ID 0967).
NIOSH found that for roof bolting, silica dust was best controlled at
its source through dust collection or wet drilling, similar to the
standard practice in metal mines of using pneumatic percussion drills
with water in addition to compressed air to flush the drill cuttings
from the hole. This drilling method was found to be the best method of
dust control, with dust reductions ranging from 86 percent to 97 percent
(Document ID 0967, pp. 2, 4). The high dust reductions from wet drilling
were confirmed in later studies that evaluated the use of water mists and
foams injected through the drill steel and found that those controls
reduced dust concentrations by 91 percent and 96 percent, respectively
(Document ID 0967, p. 2). NIOSH also found that for surface drilling,
wet drilling techniques provided the best dust control. Wet drilling
provided dust control efficiencies of up to 97 percent at a water flow
rate of 4.5 L/min (1.2 gallons per minute) (Document ID 0967, p. 6).
OSHA thus finds that water directed at the material discharge point is
an effective dust suppressant in vehicle-mounted rock and concrete
drilling and specifies its use on Table 1 for this task.
OSHA also finds that the use of an enclosed cab can effectively
reduce exposures for vehicle-mounted drill operators. Enclosed cabs,
however, only benefit the operator when the operator remains in the
cab, and they do not control employee exposure during positioning or
hole-tending activities. Therefore additional controls are necessary to
protect employees from exposure to silica dust when performing
activities outside of the cab. As described above, OSHA has determined
that the use of water for dust suppression on the drill bit will
effectively reduce exposures in situations where employees must also
perform activities outside the cab.
Based on the information discussed above, Table 1 of this standard
provides the option for employees to operate a vehicle-mounted rock or
concrete drill from within an enclosed cab in conjunction with water
applied at the drill bit for dust suppression; wherever cabs are
specified in Table 1, however, the cabs must meet the requirements of
paragraph (c)(2)(iii) of the standard for construction, as discussed
above. OSHA has determined that the enclosed cab will adequately
protect the operator while the addition of water at the drill bit will
reduce exposures for employees in the area. The alternative control
option included in Table 1, a dust collection system and water sprays
at the discharge point (where the system ultimately dumps extracted
dust), has also been proven to reduce exposures for both the operator
at the drill controls and those employees in the vicinity. When the
specified dust control methods are fully and properly implemented, TWA
exposure levels are expected to remain below 50 [mu]g/m\3\, and
therefore, Table 1 does not require use of respiratory protection
regardless of task duration for either control option. In the proposed
rule, OSHA required the use of respiratory protection when the task
lasted more than four hours. However, this was due to the inclusion of
dowel drilling rigs within the entry for "Operating Vehicle-Mounted
Drilling Rigs for Concrete." As explained above, OSHA has determined
that the exposures that result from dowel drilling rigs equipped with
LEV systems, for which respirators are required regardless of task
duration, are substantially higher than is the case for vehicle-mounted
concrete drilling rigs.
IUOE commented that Table 1 would be clearer if it specified that
employers who use open cabs during concrete drilling are not exempt
from exposure assessment when employers implement the other controls
listed for vehicle-mounted drilling rigs for concrete (Document ID
2262, Attachment 1, p. 48). OSHA considers the rule to be clear as
written: If an employer chooses to operate vehicle-mounted drilling
rigs for rock and concrete from within an enclosed cab, it must follow
the requirements in paragraph (c)(2)(iii) of the standard for
construction and apply water for dust suppression at the drill bit.
Otherwise, the employer must follow the alternative shrouded dust-
collection-system compliance method in Table 1 or the requirements in
paragraph (d) of the standard for construction, which allow for
alternate exposure control methods provided that employee exposures are
assessed and exposures are kept at or below the PEL. Additionally, IUOE
suggested that OSHA explicitly state on Table 1 that the employer does
not have the option of respirator use as a means to control exposures
during rock crushing or rock and concrete drilling if the employer
chooses not to use enclosed cabs as an engineering control (Document ID
2262, Attachment 1, p. 48). OSHA notes that Table 1 of this final
standard does not require that drilling rig operators work from
enclosed cabs exclusively. Because employers can choose between the two
control methods listed on Table 1, employees that use open cabs during
drilling activities would not be required to conduct exposure
assessments if they are using a dust collection system with a close
capture hood or shroud around the drill bit and are ensuring that the
material at the dust collector discharge point is being wetted. If that
method is followed, OSHA, having found based on the exposure profile
and record evidence that exposures will consistently be at or below the
PEL, has not included a respirator requirement on Table 1; where
respirators are not required to satisfy compliance obligations (as is
the case here if Table 1 is fully and properly implemented), OSHA does
not expect employers to require the use of respirators anyway. However
employers that do not follow either control strategy specified in Table
1 must comply with paragraph (d) of the standard for construction,
which could require respirator use if exposures are measured at or
above the PEL when using feasible engineering and work practice
controls.
IME stated that the final rule should allow for the use of
equivalent, alternative control methods (Document 2213, Attachment 1,
p. 2). Table 1 is intended to represent the most reliable control
methods available for reducing exposures, based on the evidence
contained in the record. Employers who wish to implement an alternative
control method can do so, but those employers must comply with
paragraph (d) of the standard for construction.
IUOE, among others, urged OSHA to explore additional options for
exposure controls to protect operators working outside the cab when
drilling. Both IUOE and Fann Contracting asserted that Table 1 does not
address protection of operators who perform construction activities
outside the cab with or without remote controls (Document ID 2262,
Attachment 1, p. 45; 2116, Attachment 1, p. 5). In response, Table 1 of
the final standard now includes a requirement to use water for dust
suppression at the drill bit when the drill is being operated from an
enclosed cab to minimize the exposure to other employees outside the
cab.
OSHA's proposed Table 1 entry for rock drilling would have required
that employees use respirators when working under the shroud. OSHA
proposed this requirement based on a determination that employees'
exposures would be high given their proximity to the point of dust
generation. IME suggested that respirators should not be required at
all times because there are circumstances where the time spent working
under the shroud is extremely brief or infrequent and potential
exposures will be minimal or negligible (Document ID 2213, p. 2). NUCA
commented that this requirement creates hazards for employees working
under the shroud (Document ID 2171, p. 10). In response to these
comments and after reviewing the record, OSHA has not retained this
respirator requirement in the final standard. The Agency finds that the
record contains substantial evidence that when the dust controls
required by Table 1 are fully and properly implemented, TWA exposures
to silica are unlikely to exceed 50 [mu]g/m\3\ (see Section 5.9 of
Chapter IV of the FEA). In reviewing dust controls historically for
drilling operations, NIOSH found that, when used properly, modern shroud
designs now help achieve dust-control objectives more consistently
than in the past (Document ID 0967, pp. 5-9). Furthermore, the record
indicates that work under a shroud is periodic or intermittent and
contains no evidence suggesting that this work is likely to result in
silica exposures exceeding 50 [mu]g/m\3\ as an 8-hour time-weighted
average. Accordingly, Table 1, unlike in the proposed rule, does not
include a respiratory protection requirement for rock and concrete
drillers on open (or enclosed) vehicle-mounted rigs.
NSSGA recommended that OSHA clarify the requirement for wearing
respirators while working under the shroud by replacing the term
"shroud" with "engineered fugitive dust control method, e.g., a
shroud, water spray, etc." (Document ID 2327, Attachment 1, p. 21).
Since the Agency has eliminated the requirement for using respirators
under the shroud, NSSGA's suggestion is moot.
Jackhammers and handheld powered chipping tools. Hand-operated
breaking and chipping power tools and equipment, commonly known as
jackhammers, pavement breakers, breaker hammers, percussion or chipping
hammers, and needle guns, are used in construction for fracturing
materials, which often include silica (e.g., rock, concrete, asphalt,
or masonry surfaces), by delivering rapid repetitive blows (see Section
5.5 of Chapter IV of the FEA). The hammers typically consist of a large
compartment containing a motor, two attached handles to grip the tool,
and a large socket out of which the drill or hammer-like metal
breaking/chipping implement extends. A worker typically will aim the
metal drill/hammer at a target surface while standing one to five feet
away either directly overhead or at an angle, and press the point of
contact into the surface to break, fracture, or chip away at it
(Document ID 4073, Attachment 4a, Row 199).
In the proposed standard, this entry was titled "Using Jackhammers
and Other Impact Drillers." OSHA had a separate entry for "Rotary
Hammers or Drills." NIOSH commented on the potential for confusion
with these titles, noting that a rotary hammer or drill is technically
an impact driller (Document ID 2177, Attachment B, pp. 32-33). OSHA has
revised the headings for the relevant Table 1 entries ((c)(1)(vii) and
(x)). The revised heading for paragraph (c)(1)(x) removes the term
"other impact drillers" and replaces it with "handheld powered
chipping tools." This change was made to clarify that this entry
applies only to handheld tools that use an impact movement to chip or
fracture the material being worked on. The heading for (c)(1)(vii) was
revised from "Using Rotary Hammers of Drills" to "Handheld and
Stand-Mounted Drills (Including Impact and Rotary Hammer Drills)" in
order to clarify that all handheld drills, including impact drilling,
are covered under that entry.
When using jackhammers and other handheld powered chipping tools at
construction sites to fracture silica-containing material, paragraph
(c)(1)(x) of the standard for construction requires the employer to
operate the tools using either a water delivery system that supplies a
continuous stream or spray of water at the point of impact, or a tool
equipped with a commercially available shroud and dust collection
system operated and maintained in accordance with manufacturer's
instructions to minimize dust emissions. If the employer is operating a
tool with the shroud and dust collection system, Table 1 requires that
the dust collector (i.e., LEV) must provide at least the air flow
recommended by the tool manufacturer, and have a filter with 99 percent
or greater efficiency and a filter cleaning mechanism. These specified
controls are essentially the same as those that were proposed, but the
final standard makes clear that if a shroud and dust collector are
used, it must be commercially available equipment. Unlike the use of a
shrouded dust collection system, a water delivery system is not
required to be commercially available but can be assembled and
installed by the employer.
OSHA revised the respirator use requirements from the proposed rule
by distinguishing between indoor and outdoor environments. Table 1 of
the final standard for construction does not require respiratory
protection if tools are used outdoors for four hours or less per shift.
OSHA based this revision on record evidence showing that exposures can
be maintained at or below 50 [mu]g/m\3\ using either water sprays or
LEV, provided work does not exceed the median task duration (231
minutes) reported by Flanagan et al. (Document ID 0677, p. 147; 0677,
Attachment 2) (see Section 5.5 of Chapter IV of the FEA). If tools are
used outdoors for more than four hours per shift, Table 1 requires the
use of respiratory protection having a minimum APF of 10 to ensure that
employees are protected from exposures above 50 [micro]g/m\3\. If the
tools are used indoors or in an enclosed area, Table 1 requires the use
of respiratory protection having a minimum APF of 10 to ensure that
employees are protected from exposures above 50 [micro]g/m\3\,
regardless of the amount of time the tools are operated during the work
shift.
NUCA testified during the hearing that jackhammering is one of the
construction activities most likely to expose employees to silica
(Document ID 3583, Tr. 2255). OSHA's exposure profile for this task
confirms this (Table IV.5.5-B in Section 5.5 of Chapter IV of the FEA);
73 of 98 TWA sample results (74 percent) were above 50 [micro]g/m\3\
for workers using jackhammers and handheld power chipping tools
operated without controls. For tools operated with water, 12 of 16 TWA
sample results (75 percent) exceeded 50 [micro]g/m\3\, but information
on how the water was applied and whether it was sufficient was lacking.
Various studies have demonstrated that properly used wet methods can
substantially reduce respirable silica levels by 90 percent and higher
(Document ID 0865, p. iv; 0867, p. 3; 0838, p. 1; 0914; 1267, pp. 493-
494; 2177, Attachment D, p. 19). NIOSH studies that examined water
spray devices designed to optimize dust suppression (directed mist or
solid cone nozzle) have found that dust and/or silica exposures are
reduced by 72 to 90 percent at a flow rate of approximately 350
milliliters per minute (ml/min) (Document ID 0865; 0867; 1267, pp. 493-
494). Although not commercially available at this time, the record
shows a number of examples of water suppression systems that have been
developed and tested and are ready for commercial introduction or can
be easily assembled from readily available hardware materials and
instructions from the New Jersey Laborers' Health and Safety Fund
(Document ID 0741; 0838; 0914; 2177, Attachment D, pp. 4-7; 3732,
Attachment 3, p. 10).
The shroud and LEV control for jackhammers and handheld powered
chipping tools was found to be less effective than water suppression
but still reduced exposures up to 69 percent (Document ID 1267, pp.
493-494; 0865, p. iv; 0651, p. 1; 0667, pp. 1-3; 0862, pp.10-11, 14).
Also, the respirable silica levels generated by these tools are
dependent on whether they are being operated outdoors, indoors, or in
an enclosed area. Several powered impact tool manufacturers currently
offer LEV options (e.g., Document ID 1288 p. 2; 1700, p. 1). Other
companies specialize in manufacturing after-market shrouds or exhaust
ventilation systems for various handheld tools such as jackhammers and
chipping equipment (Document ID 0566, p. 1; 1264, pp. 4-9; 1266, pp.
9-28; 1671; 1366; 1399; 3806, pp. 272-273, 276).
OSHA received a number of comments on the jackhammer and handheld
powered chipping tool entries on Table 1. CISC commented that OSHA did
not indicate in the proposed Table 1 that the dust collection system
needed to be commercially available and did not set parameters for the
functioning of the dust collection system (Document ID 2319, p. 107).
Based on comments and testimony in the record, OSHA has clarified the
entry in Table 1 for jackhammers and handheld powered chipping tools to
read "use tool equipped with commercially available shroud and dust
collection system." OSHA has added to Table 1 the following
requirements: Operate and maintain the tool in accordance with the
manufacturer's instructions to minimize dust emissions; provide at
least the air flow recommended by the tool manufacturer; and use a
filter with a 99 percent or greater efficiency and a filter cleaning
mechanism.
CISC also expressed concern that using wet methods may raise
quality issues, for example by introducing water to the base when
pouring new concrete (Document ID 2319, p. 107). The water delivery
system required by Table 1 must deliver a continuous stream or spray of
water at the point of impact. The water delivery system evaluated by
NIOSH delivered between 250 and 300 ml of water per minute and the
authors observed that water applied at these flow rates did not add a
substantial amount of water to the work surface nor did it result in
substantial accumulation of water (Document ID 0867, pp. 8, 15). Given
that a substantial amount of water is not needed, OSHA finds that
proper implementation of the water delivery system is unlikely to lead
to quality control issues. Furthermore, other than the hypothetical
situation raised by CISC, there is no evidence in the record showing
that using wet methods with jackhammers and powered chipping tools
results in quality issues. Furthermore, Table 1 of the final standard
provides two options for dust control of jackhammers and handheld
powered chipping tools. The employer can use a tool that is equipped
with a commercially available shroud and dust collection system as an
alternative to using water.
Some commenters discussed that water may introduce slip hazards;
however, comments and hearing testimony described current contractor
practices that countered these concerns (Document ID 2171 p. 4; 3589,
Tr. 4295-4296). OSHA understands the concerns about possible slip
hazards from the use of water; however, NIOSH investigators noted that
the relatively low water flow rates (300 ml/min) used to suppress dust
during jackhammering did not result in a substantial accumulation of
water on work surfaces. OSHA expects that proper implementation of the
water delivery system will include taking measures to contain any
runoff to prevent the accumulation of water on walking and working
surfaces.
The water delivery systems described in OSHA's feasibility
assessment chapter on jackhammers, chipping hammers, and other powered
handheld impact tools (see Section 5.5 of Chapter IV of the FEA),
include portable water tank systems that can easily be brought to a
construction site by a pickup truck or trailer, even in a remote area
(Document ID 0867, p. 4; 0741 p. 1). These water delivery systems can
be operated by one worker and would not require a second worker to
supply the water at the point of impact (Document ID 0838, p. 2).
Handheld grinders for mortar removal (i.e., tuckpointing). Handheld
grinders are tools fitted with rotating abrasive grinding blades,
discs, or small drums. Tuckpointers are a subset of grinders who
specialize in removing deteriorating mortar from between bricks and
replacing it with fresh mortar ("tuckpointing") (see Section 5.11 of
Chapter IV of the FEA). Tuckpointing is most commonly performed for
exterior wall maintenance and so generally occurs outdoors, but can
occur indoors where there is interior masonry. The initial phase of
tuckpointing involves using handheld grinders to grind old mortar from
between bricks on a section of the wall. A grinder typically has two
handles that can form various angles with each other and are connected
to a rotating blade located between them. The worker typically holds
one handle in each hand, forming an angle allowing the worker to press
the rotating blade against the mortar between bricks to abrasively
remove it (Document ID 4073, Attachment 4a, Row 226).
Paragraph (c)(1)(xi) of the standard for construction requires that
this task be performed using a grinder equipped with a commercially
available shroud and dust collection system and operated in accordance
with manufacturer's instructions. Additionally, the dust collection
system must be capable of providing at least 25 cfm of air flow per
inch of wheel diameter and be equipped with a filter that has a 99
percent or greater efficiency and either a cyclonic pre-separator or a
filter cleaning mechanism. The proposed requirement was similar but
specified the air flow to be at least 80 cfm, rather than 25 cfm per
inch of blade diameter, and also included a number of work practices.
OSHA revised the controls for this task based on comments received in
the record, as described below.
BCTD commented that "Tuckpointing," as the entry was titled in
proposed Table 1, is an operation that consists of a series of tasks
(chipping or cutting out old mortar, preparing replacement mortar,
cleaning the joints, applying fresh mortar, and applying a sealer),
while the listed control was clearly directed at the task of using a
"hand-operated tuckpoint grinder" (Document ID 2371, p. 25). To
clarify its intent to address the grinding of old mortar, OSHA has re-
named the entry for paragraph (c)(1)(xi) of the standard for
construction to be "Handheld grinders for mortar removal (i.e.,
tuckpointing)."
Recent dust control efforts for tuckpointing have focused on using
a dust collection hood (also called a shroud) that encloses most of the
grinding blade and a vacuum cleaner system that is used to suction
(exhaust) air from these hoods to collect dust and debris. These shroud
and vacuum combinations generally capture substantial amounts of
debris. In hearing testimony, Tom Ward, representing BAC, showed a
video of local exhaust engineering controls for tuckpointing and
described them as "extremely effective" (Document ID 3585, Tr. 3069).
However, OSHA's exposure profile for tuckpointing shows that, even with
these controls, silica exposures often exceed 100 [micro]g/m\3\ (25
percent of results exceed 250 [micro]g/m\3\ when workers use LEV for
outdoor tuckpointing). An additional survey added to the rulemaking
record reported results at two tuckpointing sites using vacuum and
shroud systems. Air samples taken during 201 to 385 minutes of mortar
grinding showed 8-hour TWA silica exposures ranging from 74 to 1,100
[micro]g/m\3\ (Document ID 4073, Attachment 9l, p. 4).
CISC questioned why employers can only use commercially available
shrouds for hand-operated grinders, eliminating the use of specialty
manufactured products (Document ID 2319, p. 110). OSHA is unsure of
what CISC means by "specialty manufactured products" and CISC's
written comments and testimony did not provide further detail. However,
it is not OSHA's intent to eliminate the use of products that are
custom made by aftermarket manufacturers (i.e., made by someone other
than the original tool manufacturer) which are intended to fit the make
and model of the grinder and designed to meet the particular needs and
specifications of the employer purchasing the product. The "commercially
available" limitation is meant only to eliminate do-it-yourself on-site
improvisations by the employer. OSHA's technological feasibility
analysis provides ample evidence that exposures to silica are
substantially reduced when using commercially available dust controls
(see Chapter IV of the FEA). To meet the requirements of Table 1,
however, any specialty manufactured product has to satisfy all the
requirements for this entry.
In proposed Table 1, OSHA specified that the dust collection system
used must provide at least at 80 cfm airflow through the shroud. For
the final standard, Table 1 requires that dust collectors have an air
flow of at least 25 cfm per inch of wheel diameter. This change is due
to OSHA's review of the evidence in the rulemaking record.
Computational and laboratory studies by Heitbrink and Bennett (2006)
and Collingwood and Heitbrink (2007) found that an air flow rate of 80
to 85 cfm (based on a 4- or 4.5-inch wheel) is the minimum needed to
efficiently capture dust generated by angle grinders used for
tuckpointing (Document ID 0728, p. 366; 0600, p. 877). ACGIH (2010)
recommends 25 cfm to 60 cfm per inch of blade diameter (Document ID
3997, pp. VS-40-01--VS-40-03). For a typical 4-inch tuckpointing blade,
25 cfm/inch of diameter is equivalent to 100 cfm, higher than the 80 to
85 cfm used by Heitbrink and Bennett (2006) and Collingwood and
Heitbrink (2007). Laboratory tests conducted by Heitbrink and Bennett
indicate that a vacuum and shroud used by tuckpointers during grinding
can reduce respirable dust emissions by a factor of more than 400 under
ideal circumstances, but this reduction factor dropped to 10 when
vacuum air flow was reduced to less than 80 cfm (Document ID 0728, p.
375). Furthermore, computational modeling showed that even a modest
decrease in the air flow rate, from 85 cfm to 70 cfm, cuts the shroud's
ability to capture dust by more than half. As a result, the estimated
worker exposure level would be twice as high as it would have been if
the air flow rate had remained constant at 85 cfm.
A NIOSH field trial on a vacuum that generated an air flow of 111
cfm for a grinder with a 4-inch blade showed that exposure levels for
respirable dust were cut in half compared to using a 76 cfm flow rate
(Document ID 0863, pp. 24-35). Based on the evidence contained in the
record, OSHA has determined that the ACGIH (2010) recommendations are
more protective given the variety of blade diameters, and is requiring
a minimum 25 cfm of airflow per inch of grinding blade diameter instead
of the 80 cfm minimum airflow (regardless of blade diameter) through
the shroud.
To adequately capture debris during the grinding phase of
tuckpointing, OSHA is requiring that vacuums be equipped with a
cyclonic pre-separator to collect large debris before the air reaches
the filters or be equipped with a filter cleaning mechanism. Cyclonic
pre-separators minimize the accumulation of debris on filters in the
vacuum, enhancing the ability of the vacuum to maintain the initial air
flow rate. When testing a vacuum cleaner model equipped with a cyclonic
pre-separator, Collingwood and Heitbrink found that the collected
debris caused the average air flow rate to decrease only from 90 cfm to
77 cfm (Document ID 0600, p. 884). Heitbrink and Santalla-El[iacute]as
evaluated two different brands of commercially available vacuum
cleaners (Tiger-Vac and Dustcontrol) incorporating cyclonic pre-
separation. Air flow rates for both of these vacuums were "largely
unaffected" by debris accumulation up to 35 pounds. Debris
accumulation also had very little effect on the flow rate measured
before and after the filter was cleaned (Document ID 0731, pp. 377,
380). Similarly, during the Collingwood and Heitbrink field trials, the
Dustcontrol vacuum with cyclonic pre-separator did not lose as much air
flow as the vacuum designed with vacuum cleaner bags (bags are a more
common pre-separation method but are subject to clogging) (Document ID
0600, pp. 883-884). OSHA concludes that cyclonic pre-separation is an
effective technology for helping to maintain air flow and vacuum system
effectiveness for the duration of tuckpointing tasks by preventing the
static pressure increase caused by clogging that would otherwise lead
to a dramatic decrease in air flow and loss of effective dust capture
at the shroud.
The accumulation of material and debris on the filter (filter
caking) during work causes pressure losses that eventually limit air
flows in even the most powerful vacuums. As debris accumulates, the
filter becomes caked with collected dust and air flow decreases. Unless
the filter is properly cleaned following manufacturer's
recommendations, the air flow declines rapidly. Cooper and Susi used a
Dustcontrol 2900c vacuum with ICS Dust Director shroud and Bosch
tuckpointing grinder to evaluate dust control in a field experiment.
The authors reported that in four hours of continuous grinding up to
130 pounds of dust was collected, and that flow rates in the vacuum
dropped from 90 cfm to 80 cfm in as little as 8 minutes. Thus, regular
stops to conduct the proper reverse air pulse filter cleaning procedure
were crucial to successful dust control (Document ID 4073, Attachment
9M, pp. 4-5, 7-9). Therefore OSHA is requiring the use of a filter-
cleaning mechanism when a cyclonic pre-separator, which removes larger
debris, is not in place. To assist employees in determining when it is
time to run a filter cleaning cycle, vacuums equipped with a gauge
indicating filter pressure or equivalent device (e.g., timer to
periodically pulse the filter) may be useful (Document ID 0731, p.
885).
PTI and OEHCS submitted comments emphasizing the importance of
effective HEPA filtration in protecting employees from silica dust, and
recommended that Table 1 require that dust collectors used with
grinders be equipped with HEPA filters (Document ID 1953, pp. 3-4;
1973, p. 2-3). However, HEPA filters may rapidly clog during mortar
grinding, leading to static pressure drop and loss of air flow needed
to capture dust (see discussion about requirements for dust collection
systems above). Instead, OSHA is requiring filters having at least 99
percent dust capture efficiency.
In proposed Table 1, OSHA included a specification that the grinder
be operated flush against the work surface and that work be performed
against the natural rotation of the blade (i.e., mortar debris directed
into the exhaust). A number of commenters discussed the difficulties of
complying with this specification (Document ID 2183; 2319). Western
Construction Group commented that it is not possible to always keep the
grinder flush with the surface because the blade will be spinning at
its full speed when cutting into the wall and when the blade is
extracted from the surface, and explained that it would be difficult to
keep the blade flush when removing vertical mortar joints (Document ID
2183, p. 2). OSHA acknowledges there are circumstances that do not
always permit the tool to be operated in this manner, and has therefore
removed this provision from Table 1. However, it is OSHA's position
that full and proper implementation of Table 1 controls includes
keeping the blade flush with the surface whenever possible, in order to
optimize the effectiveness of local exhaust capture (e.g., Document ID
0728, p. 376; 0600, p. 876).
Western Construction Group also commented that it is not always
possible to operate the grinder against the natural rotation of the
blade, because a wall needs to be "prepped" in order to be in sufficient
condition for mortar to be placed back into the wall (Document ID 2183,
pp. 2-3). Western Construction Group explained that during final
preparation, the blade needs to make short passes back and forth to
clean the joint and prepare it, and that if workers only operated in
one direction, they would place a significant burden on their shoulders
and backs by having to make more passes on the wall to clean the joint
(Document ID 2183, p. 3). Similarly, CISC commented that workers must
move the grinder back and forth in short, deliberate motions when
detailing the joint in order to provide the necessary quality finish
(Document ID 2319, p. 106). OSHA recognizes that the requirement to
operate against the direction of blade rotation may have an impact on
job quality and may increase ergonomic stress. While OSHA has removed
this specification from Table 1, it is OSHA's expectation that full and
proper implementation of Table 1 controls includes operating against
the direction of blade rotation, in accordance with the manufacturer's
instructions, whenever practical.
CISC commented that a significant portion of tuckpointing takes
place at elevated locations on scaffolds and expressed concern about
the control measures listed introducing significant trip and fall
hazards at elevated locations (Document ID 2319, p. 110). Grinding
related to tuckpointing does take place on scaffolds, as evidenced by
one building project evaluated by Cooper et al. where dust collectors
were used on scaffolds to grind mortar from the exterior walls of a 12-
story building (Document ID 4073, Attachment 9l, p. 1). When mortar
grinding will take place on scaffolds, the employer's written exposure
control plan should include procedures to ensure that the dust
collector is operated in an effective and safe manner.
In the proposed standard, OSHA required personal air purifying
respirators (PAPR) with an APF of 25 to be used while tuckpointing,
regardless of task duration. The proposed requirement was based on high
exposures results, including a TWA measurement of 6,196 [mu]g/m\3\ for
an apprentice mortar grinding with LEV (Document ID 0229, p. 12).
However, it is clear from this NIOSH report that the LEV system was not
fully and properly implemented in that the grinder blade was operated
in a back-and-forth manner with frequent insertions, and the hose from
the tool to the dust collector would frequently kink and fall off.
Based on data in the record, OSHA expects that a worker engaged in
mortar grinding for four hours or less per shift can experience TWA
exposures of less than 500 [micro]g/m\3\, while a worker performing
this task more than four hours per shift could be exposed up to nearly
1,000 [micro]g/m\3\ TWA. Among tuckpointers using LEV outdoors, 40
percent of samples contained in the exposure profile measured exposures
below 50 [micro]g/m\3\, with a mean exposure of 348 [micro]g/m\3\ (see
Section 5.11 of Chapter IV of the FEA). Therefore, Table 1 of the final
standard is requiring the use of respiratory protection with a minimum
APF of 10 for work lasting four hours or less in a shift, which is
reduced from the proposed APF of 25. Based on the evidence of
continuing improvements in the effectiveness of LEV as reported in the
literature, the exposure information, and the requirement in paragraph
(c)(2)(i) to provide a means of exhaust as needed to minimize the
accumulation of visible airborne dust indoors, OSHA concludes that the
reduction to an APF of 10 is appropriate for tasks of four hours or
less in duration. For work lasting more than four hours per shift, OSHA
is maintaining the requirement to use respiratory protection with a
minimum APF of 25.
Handheld grinders for uses other than mortar removal. Handheld
grinders are tools fitted with rotating abrasive grinding blades,
discs, or small drums used to smooth, roughen, or reshape concrete
surfaces (including forming recesses or slots) (see Section 5.11 of
Chapter IV of the FEA). Grinders may also be used to remove thin layers
of concrete and surface coatings (e.g., performing small-scale spot
milling, scarifying, scabbling and needle-gunning). A grinder typically
has two handles that can form various angles with each other and are
connected to a rotating blade located between them. The worker
typically holds one handle in each hand, forming an angle allowing the
worker to press the rotating blade against the work surface and abrade
the surface and remove the layer of target material (Document ID 4073,
Attachment 4a, Row 91).
Paragraph (c)(1)(xii) of the standard for construction specifies
two control options. The first control option, which applies only when
grinders are used outdoors, is to use a grinder equipped with an
integrated water delivery system that continuously feeds water to the
grinding surface. When employers choose to use wet grinders indoors or
in an enclosed area, they must comply with the requirements of
paragraph (d) of the final rule. The second option is to use a dust
collector equipped with a commercially available shroud and dust
collection system. The dust collector must provide 25 cfm or greater of
air flow per inch of wheel diameter and have a filter with a 99 percent
or greater efficiency and a cyclonic pre-separator or filter-cleaning
mechanism. OSHA is requiring that the control must be operated and
maintained in accordance with manufacturer's instructions to minimize
dust emissions. The second option is identical to the option required
for handheld grinders used for mortar removal.
In the proposed standard, OSHA did not specify that the water
delivery system be integrated with the grinder. However, OSHA has
determined that systems that are designed and developed in conjunction
with the tool are more likely to control dust emissions effectively by
applying water at the appropriate rate and dust emission points based
on tool configuration. Further, integrated systems will not interfere
with other tool components or safety devices. These include free-
flowing water systems designed for blade cooling as well as
manufacturers' systems designed for dust suppression alone. OSHA is not
specifying a minimum flow rate, but rather anticipates that the water
flow rates specified by the manufacturer will optimize dust reduction.
OSHA also recognizes that using makeshift water delivery systems can
pose hazards. PTI commented that the use of a water feeding system not
specified by the tool manufacturer could result in serious personal
injury and electric shock for tools that are electrically operated
(Document ID 1973, p. 1). Due to the potential hazards from using a
water delivery system not specified by the manufacturer, and to ensure
the effectiveness of the system in controlling dust, OSHA has modified
Table 1 to require use of integrated water systems that are operated
and maintained according to manufacturer's instructions to minimize
dust emissions.
OSHA received a number of comments related to the use of wet
methods as a control for handheld grinders. SMI and CISC commented on
the difficulties of using an integrated water system while grinding,
arguing that there is a lack of options with both safety guards and
water supply, that grinders equipped with a water delivery system are
designed to cool the blade rather than control the dust, and that the
dust mitigation effects of the water are speculative (Document ID 2316,
p. 2; 2320, p. 10). However, NIOSH reported that "several
manufacturers of smaller grinders do offer electric grinders with
integrated water supply capability" and included the catalog of such
suppliers (Document ID 4233, Attachment 1, pp. 7-8; 3998, Attachment
10). Studies by Linch et al. (2002), Akbar-Khanzadeh (2007, 2010), and
Simcox et al. (1999) evaluated the use of wet methods during grinding
(Document ID 0784; 0552; 3609; 1146). Although there were some
differences in the effectiveness of systems tested by these
investigators, all of them reduced dust levels substantially compared
to dry grinding. Therefore the ability of water to control dust when
grinding is not speculative and has been demonstrated in various
studies throughout OSHA's technological feasibility analysis contained
in Chapter IV of the FEA. In short, OSHA concludes that, based on the
best available evidence, there are commercially available grinders with
integrated water supply capability, and that wet methods can be an
effective control for grinding in many circumstances (Document ID 0522,
p. 778; 1146, pp. 578-579).
Francisco Trujillo of Miller and Long commented that wet methods
often present significant slip and fall hazards and that attempting to
apply wet methods to any non-horizontal surface has proven ineffective
and often hazardous when using grinders (Document ID 2345, p. 2).
Similarly, Stuart Sessions, an economist testifying on behalf of CISC,
noted that it is difficult to use wet methods in winter in locations
where the water may freeze (Document ID 3580, Tr. 1322). OSHA
acknowledges that not every control option is practical in every
situation, and in such situations, Table 1 of the final standard
permits use of LEV systems to control dust. However, OSHA concludes
that wet methods represent a feasible and effective option outdoors.
Those who do not implement the wet methods described above, or
those grinding indoors, have the option to use a dust collector
equipped with a commercially available shroud and dust collection
system. Several rulemaking participants testified on the commercial
availability of such equipment, including Gerry Scarano, Executive Vice
President of BAC, Deven Johnson, director of training, health and
safety for the Operative Plasterers and Cement Masons International
Association, and Francisco Trujillo of Miller and Long (Document ID
3581, Tr. 1562, 1592-1593; 3585, Tr. 2962-2964). The record shows that
Makita, DeWalt, Bosch, and Ostec all make grinding dust collection
systems (see Chapter IV of the FEA).
The LEV-based exposure controls for surface grinding function
similarly to the LEV-based controls for mortar removal described in
paragraph (c)(1)(xi) of the standard for construction, as mortar
removal (tuckpointing) is simply a specialized form of grinding that
uses the same grinding tools. The factors that influence vacuum flow
rate for mortar removal (tuckpointing) are equally important to LEV
dust controls for all types of surface grinding, and for other hand-
operated power tools as well. Collingwood and Heitbrink note that
"vacuum cleaners will probably continue to be an important control
option for respirable dust exposures in construction for dust exposure
sources such as mortar removal, concrete grinding, hole drilling, and
brick cutting where water application is impractical" (Document ID
0600, p. 884). Older studies of LEV effectiveness have found exposure
reductions of 86-99 percent (Document ID 0611, p. 463; 0247, pp. 6, 8).
A more recent study by Akbar-Khanzadeh et al. found silica dust
exposure reduced by 98-99 percent, depending on the vacuum type used
(Document ID 3609, p. 707). Akbar-Khanzadeh and Brillhart and Echt and
Sieber both reported reduced silica exposures when workers used LEV
shrouds with vacuum attachments during surface grinding, although the
silica exposure results were variable and some exceeded 50 [micro]g/
m\3\ even with use of the controls (Document ID 0521, pp. 344-345;
0632, pp. 459-460).
OSHA received a number of comments about the proposed entry on
Table 1 for handheld (or hand-operated) grinders using LEV. The
proposed entry specified use of a grinder with a commercially available
shroud and dust control system. Several commenters questioned why
shrouds needed to be commercially available and whether appropriate
shrouds are, in fact, commercially available (e.g., Document ID 2319,
p. 105; 2316, p. 2; 2171, p. 9). Francisco Trujillo from Miller and
Long stated "dust collection systems used on hand grinders received
very disappointing results. In fact, no hand grinder equipped with a
dust collection system was capable of bringing exposure levels below
the current [i.e., the preceding] PEL" (Document ID 3585, Tr. 2963).
He further explained that this was due to the limited capabilities of
the dust collection systems maintaining complete surface contact during
the frequent grinding of columns and walls (Document ID 3585, Tr. 2963-
2964). However, he found that a vacuum system designed for use with
ceiling grinders "greatly reduced the amount of dust expelled from the
process but did not completely eliminate it. It was a very, very dusty
activity, and now it's moderately so" (Document ID 3585, Tr. 2962). He
reported that although all sampling results were below the preceding
PEL, three out of five samples were still above 50 [micro]g/m\3\. He
also reported that none of the hand grinders with dust controls that
Miller and Long evaluated were effective with columns and wall corners
and that even with these LEV systems, the same number of workers were
in Miller and Long's respiratory protection program (Document ID 3585,
Tr. 2962-2964, 3012).
In Section 5.11 of Chapter IV of the FEA, OSHA's exposure profile
shows that 60 percent of ceiling grinders who perform overhead grinding
using LEV, and 50 percent of outdoor grinders using LEV or water have
achieved exposures below 50 [micro]g/m\3\, while 25 percent of other
grinders working indoors with LEV have achieved exposures below 50
[micro]g/m\3\. These results demonstrate that exposures of 50 [micro]g/
m\3\ or below are achievable with technology available at the time of
sampling. Much of the data in the exposure profile reflects samples
collected over ten years ago, before many of the engineering studies
described in the FEA were conducted. OSHA expects that capture
technology will continue to improve in response to market demand.
In addition, Gerry Scarano, representing BAC, stated that since
2009, "the availability and effectiveness of control options have
improved, adding force to OSHA's conclusion that it is feasible to
reduce the dust in most cases down to the proposed PEL" (Document ID
3581, Tr. 1562). Thus, the effectiveness of controls available today is
likely higher than those that were used when the exposure samples
included in the exposure profile were obtained.
SMI commented that there are no commercially available dust shrouds
that currently meet American National Standards Institute (ANSI) B7.1
(and OSHA) guard design requirements (Document ID 2316, p. 2). SMI
stated that available dust shrouds are plastic and are used in place of
the original equipment's steel guards but do not meet the requirements
of ANSI B7.1, which is a safety design specification standard for
grinding wheels (Document ID 2316, p. 2). However, NIOSH reported that
several major tool manufacturers sell grinders with integrated dust
shrouds designed to meet applicable safety standards, and the tools are
labeled accordingly. For example, the Underwriter's Laboratory
(UL) mark carried by the products of several manufacturers signifies
that their tools meet the requirements of ANSI/UL/CSA 60745-2-3, which
incorporates ANSI B7.1 by reference (Document ID 4233, Attachment 1, p.
8). Catalogs of tool manufacturers submitted to the docket by NIOSH
include grinders that meet this standard and other tools that bear the
SA approval mark of the Canadian Standards Association, an OSHA
Nationally Recognized Testing Lab (NRTL, described under 29 CFR 1910.7)
(Document ID 3998, Attachment 10, pp. 7-9, 15, 45). OSHA anticipates
that, once there is a market demand, additional tool manufacturers will
offer shrouds meeting these machine guarding requirements. OSHA finds
that compliant shrouds are already commercially available, and will not
create a greater hazard.
In the proposed standard, OSHA specified that the dust collection
system must have an air flow of at least 25 cfm per inch of wheel
diameter. OSHA has maintained this requirement in the final standard.
CISC commented that for larger blades, it may be difficult to design
and operate a system that pulls air flow at 25 cfm per inch of blade
diameter (Document ID 2319, p. 105). NAHB also expressed concern that a
dust collector with a HEPA vacuum would need to be at least 112.5 cfm
for a small, 4.5-inch grinder (Document ID 2296, Attachment 1, p. 29).
PTI recommended revising the Table 1 entry for grinders to require use
of vacuums equipped with a HEPA filter that operates at 80 cubic feet
per minute or greater, noting that commercial dust collection systems
are typically rated at approximately 130 cfm (Document ID 1973, pp. 2-
3). BCTD, on the other hand, recommended that OSHA specify airflow
rates for grinder LEV based on blade diameter (Document ID 2371, p.
32). As explained above in the discussion of grinders used for mortar
removal, OSHA has determined that 25 cfm per inch of blade diameter is
more protective and consistent with established engineering principles
as reflected in the ACGIH Industrial Ventilation Manual, 28th Edition,
which generally expresses minimum cfm requirements for a variety of
(stationary) grinders in relation to the wheel diameter (Document ID
3883, pp. 13-147--13-152).
To adequately capture debris during the grinding, OSHA is requiring
that dust collection systems used with grinders have a filter with 99-
percent or greater efficiency, along with either a cyclonic pre-
separator to collect large debris before the air reaches the filters or
a filter-cleaning mechanism. Because the same factors that cause air
flow to decline during tuckpointing affect air flow during other tasks
such as surface grinding, the measures discussed in the section on
grinders used for mortar removal also need to be used when surface
grinding to minimize filter clogging.
Echt and Sieber reported respirable quartz concentrations ranging
from 44 [micro]g/m\3\ to 260 [micro]g/m\3\ during two to three hour
surface grinding tasks with LEV at a construction site. Each day, one
or two 18-pound bags of debris were collected in a vacuum cleaner. The
investigators measured actual air flow rates three times over the
course of five sampling days, reporting an air flow range from 86 to
106 cfm (Document ID 0632, pp. 459-460). As noted in the discussion of
LEV controls required for handheld grinders for mortar removal
(tuckpointing), Heitbrink and Santalla-El[iacute]as also reported that
air flow is affected by filter loading (Document ID 0731, p. 383).
Using more extensive measurements (continuous data logging every 8
seconds), Collingwood and Heitbrink evaluated the same vacuum model
used by Echt and Sieber and found that average initial air flow was 71
cfm, which declined to 48 cfm over the task-based work sessions, even
with knocking the dust from filters using the manufacturer's
recommended method as deemed necessary (Document ID 0600, p. 884). As
previously discussed, the accumulation of material and debris on the
filter (filter caking) during work causes pressure losses that
eventually limit air flows in even the most powerful vacuums. As debris
accumulates, the filter becomes caked with collected dust and air flow
decreases. Unless the filter is properly cleaned according to the
manufacturer's instructions, the air flows declines rapidly.
OSHA included three additional specifications in the proposed
standard; two of these, preventing wet slurry from accumulating and
drying, and ensuring that visible dust was not emitted from the
process, were completely removed as described above. OSHA is retaining
the third specification, which requires employers to minimize the
accumulation of visible airborne dust when working indoors or in
enclosed areas by providing sufficient ventilation when needed; this
requirement is now located in paragraph (c)(2)(i) of the standard for
construction.
In the proposed standard, OSHA required the use of a half-mask
respirator with an APF of 10 during wet grinding for more than four
hours. No respiratory protection was required when wet grinding for
four hours or less. When using a grinder equipped with a commercially
available dust collection system, OSHA required the use of a half-mask
respirator with an APF of 10 regardless of task duration. In the final
standard, OSHA has decided it is appropriate to distinguish between
respiratory protection needed when grinding outdoors and grinding
indoors or in enclosed areas. This division has allowed OSHA to more
appropriately apply the use of respirators, limiting the number of
tasks that requires their usage. Based on data in the record, OSHA
concludes that most employees using hand-operated grinders without
controls currently experience exposures above 50 [micro]g/m\3\ TWA.
However, when grinders are operated with dust collection or wet systems
outdoors, exposures will be reduced to or below 50 [micro]g/m\3\ most
of the time. The exposure profile in Table IV.5.11-B in Section 5.11 of
Chapter IV of the FEA shows that 50 percent of grinders working
outdoors using water or LEV are exposed below 50 [mu]g/m\3\. These
results demonstrate that silica exposures at or below 50 [mu]g/m\3\
have already been achieved for half of exposed workers with technology
available at the time of sampling. Much of the data in the exposure
profile reflects samples collected over ten years ago, before many of
the engineering studies described in the FEA were conducted. OSHA
expects that dust capture technology will continue to improve in
response to market demand. When fully and properly implemented, OSHA
expects that exposures to silica will be at or below 50 [mu]g/m\3\ most
of the time when water-based dust suppression or LEV systems are used
for outdoor grinding and that respiratory protection will not need to
be relied on to protect employees.
The available data presented in Table IV.5.11-B in Section 5.11 of
Chapter IV of the FEA suggest that the mean indoor grinding exposure
level with dust collection systems is about twice that for grinding
outdoors, with 50 percent of exposures between 100 and 250 [micro]g/
m\3\. Exposures measured within a test chamber during grinding
operations confirm that high exposures result from grinding concrete
indoors, even with good dust collection equipment (Document ID 3609),
with mean task-based sample results generally falling between 100 and
200 [micro]g/m\3\. Based on the available data for indoor grinding,
OSHA concludes that, when grinding with a commercially available shroud
and dust collection system for four hours or less per shift, resulting
exposures should generally be no higher than grinding outdoors for a
full shift and thus should not necessitate the use of respiratory
protection. However, for indoor grinding tasks performed more than four
hours per shift, the Agency concludes that exposures will consistently
exceed 50 [micro]g/m\3\. Therefore, Table 1 requires respiratory
protection with an APF of at least 10 when grinding with dust
collection systems for more than four hours per shift indoors or in an
enclosed area.
OSHA finds that there is inadequate evidence in the record to
demonstrate that wet grinding indoors or in an enclosed area is as
effective as using LEV. Accordingly, OSHA is permitting the use of
water-based dust control for grinding tasks outdoors only and is not
requiring the use of respiratory protection regardless of the duration
of the task. OSHA notes from its exposure profile that the vast
majority of exposure samples taken during indoor grinding where dust
controls were used made use of LEV systems rather than water-based dust
control systems (21 out of 23 samples) (see Section 5.11 of Chapter IV
of the FEA). If an employer decides to use a wet method for indoor
grinding, it will be operating outside of Table 1 and will have to
comply with the paragraph (d) alternative method of compliance.
Walk-behind milling machines and floor grinders. Paragraph
(c)(1)(xiii) of the standard for construction requires walk-behind
milling machines and floor grinders used to grate or grind solid
surfaces (such as concrete, asphalt, masonry walls and sidewalks, see
Section 5.8 of Chapter IV of the FEA) to be equipped with an integrated
water delivery system that continuously feeds water to the cutting
surface, or with a dust collection system recommended by the
manufacturer of the milling machine or floor grinder, a filter with 99
percent or greater efficiency, and a filter-cleaning mechanism. When
using an LEV dust collector system indoors or in enclosed areas, Table
1 also requires that loose dust be cleaned with a HEPA-filtered vacuum
in between passes of the milling machine or floor grinder. Both options
require that the tool be operated in accordance with the manufacturer's
instructions to minimize dust emissions. No respiratory protection is
required by Table 1, regardless of task duration or work location.
Paragraph (c)(1)(xiii) of the standard for construction covers
wheeled machines, equipped with a cutting tool, that are guided by hand
with the worker positioned more than an arm's length away from the
grinding action of the tool (e.g., milling machines, scarifiers, floor
grinders). Laborers or construction workers operate these machines
during specialty tasks such as resurfacing floors, repairing pavement,
or creating grooves for electrical cables (Document ID 0036, p. 15;
3958; 3959, p. 39). In the proposed standard, walk-behind milling
machines were included under the entry for "Milling" as "walk-behind
milling tools." In response to commenters' recommendations, and
recognizing that suitable dust control measures differ among different
milling machines, OSHA has decided it is more appropriate to divide
milling activities into three subgroups: Walk-behind machines and floor
grinders, small drivable milling machines (less than half-lane), and
large drivable milling machines (half-lane and larger) (Document ID
3583, Tr. 2171, 2212-2213; 2181, pp. 4, 7, 9).
Walk-behind milling machines and floor grinders are currently
available with water systems (e.g., Document ID 0524; 0642), and with
dust collection systems (e.g., Document ID 1276; 0636; 0642; 4073,
Attachment 4a, Rows 131-133, 150-152). Additionally, some scarifiers,
particularly those intended for indoor use, are available with both a
vacuum port (for connecting to a portable industrial vacuum system) and
a water mist system as standard equipment (Document ID 0642).
In specifying the option for a machine equipped with an integrated
water delivery system that continuously feeds water to the cutting
surface, OSHA is not specifying a minimum flow rate for water used with
the integrated delivery system, but rather anticipates that the water
flow rates specified by the manufacturer will optimize dust reduction.
Evidence in the record demonstrates the effectiveness of wet methods to
control exposures when using walk-behind milling machines and floor
grinders. ERG (2000) measured exposure levels below the LOD (12
[micro]g/m\3\) for workers using wet methods while milling a newly
installed terrazzo floor indoors (Document ID 0200, p. 11). Echt et al.
(2002) tested a custom-built water-fed system that provided a copious
amount of water (15 gallons per minute) to the concrete work surface
(not the cutting teeth) milled by a scabbler with an 8-inch cutting
width. The investigators compared results from alternating 5-minute
periods of milling with and without the water-feed activated. The water
reduced average respirable dust levels by at least 80 percent. A
separate NIOSH study on drivable milling machines reports that under
common road milling conditions, water spray provided to the cutting
drum area at 12 gallons per minute is capable of suppressing dust
generated by a 7-foot wide (84 inches) drivable milling machine cutting
drum (an application rate of just 0.14 gallons per minute per inch of
cutting width) (Document ID 1251, pp. 7-9, 14). Based on this evidence,
OSHA concludes that, with careful adjustment, water spray methods using
a fraction of the water used in the Echt et al. (2002) scabbler study
should prove at least as effective in reducing silica dust exposures
generated by walk-behind milling machines and floor grinders.
Blute et al. (1999) evaluated silica exposures among workers using
wet dust control methods for scabbling and large-scale grinding tasks
at an underground construction site. In this case, rather than being
walk-behind equipment, the scabblers and grinders were attached to the
articulated arm of front-end loaders (Document ID 0562, p. 633).
Although these workers used drivable machines (removing more material
than the typical walk-behind milling machine), their work (scabbling
and grinding excess concrete from tunnel walls) demonstrates the value
of wet methods when these activities are performed in enclosed spaces.
This is particularly relevant to walk-behind milling machines that are
frequently used indoors to mill concrete surfaces. In the underground
work environment, all three workers experienced task-based silica
concentrations below the preceding PEL with only one of the results (79
[micro]g/m\3\) exceeding 50 [micro]g/m\3\ (Document ID 0562, p. 637).
OSHA has determined that the information discussed above and in the FEA
is the best available evidence and supports the use of wet methods to
control silica dust while using walk-behind milling machines.
Alternatively, employers following Table 1 may use a machine
equipped with a dust collection system recommended by the manufacturer.
The similarity between vehicular and walk-behind milling machines
supports the use of vacuum dust collection (exhaust suction) methods
for the smaller, walk-behind form of milling equipment. A study by TNO
Bouw (2002) found that when exhaust suction methods were applied to the
milling drum area of drivable milling machines, exposure levels for
operators obtained over a five-day period ranged from less than 4
[micro]g/m\3\ to 28 [micro]g/m\3\. The study also found similar
exposure results for machine tenders, who walked next to the machines;
results ranged from less than 3 [micro]g/m\3\ to 29 [micro]g/m\3\
(Document ID 1184, p. 25). OSHA inspection data from a construction
site using a scarifier and a floor grinder, both equipped with LEV,
to mill a concrete floor found no silica exposure for either of the
workers (Document ID 3958, Rows 209-211, 214-215). OSHA's exposure
profile, contained in Section 5.8 of Chapter IV of the FEA, contains
these and four other exposure results for workers using walk-behind
equipment at two indoor construction sites using LEV, where only one
detectable result exceeded 50 [micro]g/m\3\.
Based on the evidence in the record, OSHA has determined that
employees' exposure when using walk-behind milling machines can be
further reduced by cleaning up debris when work is performed indoors or
in enclosed areas. During a study on exposures while operating a
scabbler in a parking garage, researchers noted that the worker
generated the most airborne dust when passing the machine over a
previously milled area (Document ID 0633, pp. 812-813). OSHA's OIS data
also contains a non-detectable silica exposure result for a helper who
vacuumed behind the operator of a floor grinder and scarifier preparing
an indoor concrete floor for painting where LEV was used as the dust
control (Document ID 3958, Row 211). Under paragraph (c)(1)(xiii) of
the standard for construction, when using a walk-behind milling machine
or floor grinder indoors or in an enclosed area, milling debris in the
form of loose dust must be removed with a HEPA-filtered vacuum prior to
making a second pass over an area. This prevents the debris from
interfering with the seal between machine and floor and minimizes the
gap. Additionally, it prevents debris from being re-suspended and
acting as another source of exposure. Accordingly, OSHA is requiring
the use of a vacuum with a HEPA filter to clean up any loose dust prior
to making additional passes over the area when work is conducted
indoors or in enclosed spaces with LEV (Document ID 0633, pp. 812-813;
1391, pp. 28, 40).
In addition, the effectiveness of vacuum suction also depends on
minimizing the gap between the bottom of the machine and the surface
being milled, as discussed by Hallin (1983), who found that exposures
to respirable dust increased when the housing around the base of the
tool was removed (Document ID 1391, p. 25). To achieve acceptable dust
control and ensure that the LEV system is fully and properly
implemented, milling must proceed in a manner that limits the gap
between the bottom of the walk-behind milling machine and the surface
being milled.
Based on the data described above, OSHA concludes that most
employees operating walk-behind milling machines will experience
exposure levels of 50 [micro]g/m\3\ or below most of the time when
employers implement the controls outlined in Table 1 under paragraph
(c)(1)(xiii) of the standard for construction. OSHA finds that controls
effective for driven milling machines are adaptable to the smaller
walk-behind milling machines. Even in indoor environments, low
exposures can be achieved for most walk-behind milling machine
operators through the proper use of controls, including the use of
HEPA-filtered vacuum systems intended to clear debris in between
milling passes when dry grinding and the use of ventilation as required
under paragraph (c)(2)(i) of the standard for construction. Therefore,
OSHA concludes that exposure will remain below 50 [micro]g/m\3\ most of
the time, even when working indoors for more than four hours, and is
not requiring the use of respiratory protection, regardless of task
duration or work location.
Small Drivable Milling Machines (less than half-lane). Employees
engaged in this task use small drivable milling equipment to grate or
grind solid surfaces, such as concrete floors, sidewalks, and asphalt
roads. The smaller drivable machines mill a narrower strip of pavement
than large milling machines (median of 20 inches compared to a minimum
of 79 inches for large machines), and typically are capable of milling
less depth (median 8 inches) than a large machine (median 13 inches)
(Document ID 1229; 3958). Milling machinery, both large and small,
often uses a rapidly rotating drum or a bit covered with nibs to abrade
surfaces, although other mechanisms (including systems based on impact,
shot-blast, or rotating abrasive cups) are common.
The proposed standard contained a single entry for "Milling" and
treated all drivable milling machines alike, requiring them to use a
water-fed system that continuously applied water at the cut point. In
the final standard, OSHA has separated smaller milling machines (less
than a half-lane wide) from larger ones based on comment and testimony
in the record. In response to commenters, OSHA has decided it is more
appropriate to divide drivable milling activities into separate entries
for large milling machines (half-lane and larger) and small milling
machines (less than half-lane) (Document ID, 3583, Tr. 2171, 2212-2213;
2181, pp. 4, 7, 9). IUOE and a road milling machine manufacturer
categorized drivable milling machines as either small or large (half-
lane or larger, with cutting drum about 79 inches or wider) (Document
ID 3583, Tr. 2441; 1229). NAPA commented that large milling machines
should be identified separately on Table 1 of the construction
standard. Based on these comments and evidence showing that the dust
control systems are different between the two classes of drivable
milling machine (Document ID 3583, Tr. 2171, 2212-2213), Table 1 in the
final standard treats them as two separate tasks.
Under paragraph (c)(1)(xiv) of the standard for construction, small
drivable milling machines (less than a half-lane in width) must be used
with supplemental water sprays designed to suppress dust. The water
used must be combined with a surfactant. Manufacturers of smaller
drivable milling machines currently make such systems (Document ID
1229; 4073, Attachment 4a). Unlike for larger milling machines, Table 1
does not specify as an option a water spray and exhaust ventilation
combination system for small milling machines because it appears that
such systems are not currently available.
Including a surfactant additive in the water is a practical way to
reduce employee exposures to the lowest level achievable with this wet
method (Document ID 1216, p. 3; 1217, Slides 4 and 8; 3583, Tr. 2187-
2188). This is because it offers particle binding properties that are
ideal for dust suppression (Document ID 1216, p. 3).
Small drivable milling machines generally produce less dust than
large drivable machines, since small machines are used intermittently
and have smaller cutting tools (Document ID 1229, pp. 1-3; 3583, Tr.
2213). As discussed in the technological feasibility section on millers
using portable or mobile machines (see Section 5.8 of Chapter IV of the
FEA), OSHA concluded that, rather than relying on the very limited
(two) existing data points for workers using small drivable milling
machines, the exposure profile for this group is better represented by
a surrogate data set comprising the more comprehensive and wide ranging
profile for the entire group of workers using drivable milling machines
(including operators and tenders/helpers of both large and small
drivable milling machines). Thus, the exposure profile for small
drivable milling machines (n = 31) shows a median exposure of 21
[micro]g/m\3\ and a mean exposure of 48 [micro]g/m\3\, with overall
exposures ranging from 5 [micro]g/m\3\ to 340 [micro]g/m\3\. Therefore,
considering the ample evidence on the effectiveness of water-based dust
control systems for large as well as small drivable milling machines,
OSHA finds that this control is applicable to small drivable milling
machines.
Water applied to the cutting drum helps reduce respirable silica
exposures among milling machine operators and helpers. In a study
conducted in the Netherlands, a water spray dust emission suppression
system using additives reduced the PBZ respirable quartz exposures of
asphalt milling machine drivers to a mean of 20 [micro]g/m\3\, with a
range of 9 [micro]g/m\3\ to 30 [micro]g/m\3\ (Document ID 1216, p. 4).
Milling machine tenders benefitted equally from the system, having a
mean PBZ respirable quartz exposure of 8 [micro]g/m\3\ with a range of
4 [micro]g/m\3\ to 12 [micro]g/m\3\. In his comments, Anthony Bodway,
representing NAPA, stated his belief that employee exposures from
asphalt road milling machines will be reduced to levels below 50
[micro]g/m\3\ when milling machines are fitted with effectively
designed water spray systems paired with surfactants and routine
inspections to ensure the system components are working properly
(Document ID 2181, p. 10). He noted that all six major road milling
machine manufacturers have recently begun, or will soon be, offering
dust control optimized water spray systems as standard equipment or
retrofit kits (Document ID 2181, pp. 21-29). One water spray design for
asphalt pavement milling evaluated by NIOSH showed more promise than
others, reducing dust release by 38 to 46 percent (Document ID 4141, p.
26). Although his comment was related to large drivable milling
machines, wet dust control technology is available for small drivable
milling machines (Document ID 1229; 4073, Attachment 4a).
Based on information presented here and in the technological
feasibility analysis (see Section 5.8 of Chapter IV of the FEA), OSHA
concludes that employers using the controls required by paragraph
(c)(1)(xiv) of the standard for construction can reduce exposure levels
to 50 [micro]g/m\3\ or below for most employees operating or helping
with small drivable milling machines most of the time. The similarities
to large drivable milling machines are sufficient to indicate that the
wet dust suppression control technology is transferable to the smaller
drivable machines. Even if these smaller machines do not achieve the
extent of dust suppression demonstrated for larger machines because
they perform specialty milling operations and not flat removal of
asphalt typically performed by large drivable machines prior to laying
of new asphalt, the intermittent nature of operations for which small
drivable milling machines are used will help to maintain 8-hour TWA
exposure levels substantially lower than they would be for continuous
operation (Document ID 3583, Tr. 2213-2215). Therefore, OSHA is not
requiring the use of respiratory protection regardless of task duration
when using small drivable milling machines (less than half-lane)
equipped with supplemental water sprays combined with a surfactant.
Large drivable milling machines (half-lane or larger). Paragraph
(c)(1)(xv) of the standard for construction has three control options
for employers operating large (one-half lane or wider) milling
machines. When making cuts of four inches in depth or less on any
substrate, the control options are either to use a machine equipped
with exhaust ventilation on the drum enclosure and supplemental water
sprays designed to suppress dust or a machine equipped with
supplemental water spray designed to suppress dust combined with a
surfactant. When milling only on asphalt, Table 1 allows cuts of any
depth to be made when machines are equipped with exhaust ventilation on
the drum enclosure and supplemental water sprays designed to suppress
dust.
These controls are currently available (Document ID 2181, pp. 11,
21-29). All of the manufacturers of large milling machines currently
provide dust-suppressing water spray systems on new equipment and as
retrofit kits for older machines. In addition, as discussed in the
Section 5.8.4 of Chapter IV of the FEA, new machines will be equipped
with both dust-suppressing water spray systems and dust collection
systems by 2017 at the latest, when industry members are committed
under the Silica/Asphalt Milling Machine Partnership, which includes
representatives from the road construction contractors industry and
major road milling machine manufacturers, NAPA, AEM, IUOE, LHSFNA, and
NIOSH, to equip new machines with both dust-suppressing water spray
systems and LEV (Document ID 2181, pp. 11, 21-29).
The controls included on Table 1 for large drivable milling
machines are based on research on dust control technologies conducted
by the Silica/Asphalt Milling Machine Partnership, which has been
studying dust controls for milling machines since 2003 (Document ID
2181, pp. 1-2; 3583, Tr. 2152, 2160; 4149) with the goal to develop
innovative engineering controls "that all but eliminate dust and
potential silica exposure," and methods "to retrofit existing milling
machines to ensure a safe workplace" (Document ID 3583, Tr. 2153).
Much of the data contained in the record on the effectiveness of
control strategies for large drivable milling machines come from the
Partnerhip's efforts and are contained in NIOSH publications (see Table
IV.5.8-B in Section 5.8 of Chapter IV of the FEA).
Based on the data in the record, exposures among large drivable
milling machine operators can be reduced to 50 [micro]g/m\3\ or less
most of the time. The exposure profile in Section 5.8 of Chapter IV of
the FEA shows that 79 percent of all large drivable milling machine
operators already experience silica levels below 50 [micro]g/m\3\ as a
result of using water spray intended to cool the cutting drum.
Similarly, exposure levels for 67 percent of tenders working alongside
large milling machines are below 50 [micro]g/m\3\. Based on the
Agency's review of studies in the record, which show that low silica
exposures can be achieved for both operators and tenders across varying
water spray flow rates, OSHA concludes that improvements to cooling
water spray systems can help to further reduce exposures of employees
currently experiencing exposures above 50 [micro]g/m\3\ (see Tables
IV.5.8-D and IV.5.8-E in Section 5.8 of Chapter IV of the FEA).
However, information is insufficient to confirm that the use of water
alone in existing systems will reliably control all employees'
exposures. Based on the Agency's review of evidence in the rulemaking
record, OSHA has determined that supplementing water with a dust
suppressant additive or with an exhaust ventilation on the drum
enclosure (controls that were not included on proposed Table 1), will
achieve levels below 50 [micro]g/m\3\ for all or almost all operators
and helpers most of the time when making cuts of four inches in depth
or less on any substrate (see Table IV.5.8-E in Section 5.8 of Chapter
IV of the FEA) (Document ID 1216, p. 4; 4147, pp. v, 13; 4149, pp. v,
13). Additionally, OSHA has determined that when milling asphalt only,
the addition of exhaust ventilation on the drum enclosure will achieve
levels below 50 [micro]g/m\3\ for workers making cuts of any depth
(Document ID 4149).
NIOSH recommended LEV plus water-spray dust suppression controls be
included on Table 1 for drivable milling machines (Document ID 2177,
Attachment B, p. 20). As discussed in Section 5.8.4 of Chapter IV of
the FEA, a dust suppression system with a foam additive kept exposures
below 30 [micro]g/m\3\, and the use of water sprays combined with LEV
systems kept exposures under 25 [micro]g/m\3\ (Document ID 1184, pp. 5,
25; 1217, p. 4). These methods, combined with water spray systems
purposefully designed to control dust at the cutting drum, transfer
points, and conveyors, will control silica exposures among vehicular
milling machine operators and tenders to 50 [micro]g/m\3\ or below
during typical removal operations under the typical range of conditions.
Manufacturers of large milling machines are committed under the
Silica/Asphalt Milling Machine Partnership to equip new machines
with both dust-suppressing water spray systems and LEV by 2017
(Document ID 2181, pp. 11, 21-29). Until such time that new machines
equipped with LEV and water dust suppression systems are available, all
six major road milling machine manufacturers have recently begun, or
will soon be, offering dust control optimized water spray systems as
standard equipment and/or retrofit kits, which are expected to meet the
requirements for Table 1 for cuts of four inches in depth or less on
any substrate (Document ID 2181, pp. 21-29).
Proposed Table 1 specified the use of a respirator (half-mask APF
10) for drivable milling machines with a water-fed system used more
than four hours a day irrespective of the material milled. NAPA
recommended removing the proposed requirements for use of respirators
when milling asphalt (Document ID 2181, pp. 11-12, 16). Upon review of
the evidence in the record, OSHA agrees that this is appropriate for
all asphalt and concrete milling operations. As explained in Section
5.8 of Chapter IV of the FEA, the controls contained in Table 1 in the
final standard will keep exposures below 50 [micro]g/m\3\ for most
operators and tenders of large drivable milling machines most of the
time. Evidence submitted to the record by NAPA and NIOSH shows both
water-based dust suppression systems and combination LEV/water-based
systems during asphalt milling results in employee exposures lower than
50 [mu]g/m\3\ (Document ID 2177 Attachment B, p. 20; 1184, pp. 5, 25;
1217, p. 4). Accordingly, respiratory protection is not required under
Table 1 of the final standard for operating large drivable milling
machines to mill asphalt. Although there is some qualitative evidence
indicating that exposures when milling concrete for more than four
hours may be somewhat higher, and could exceed 50 [mu]g/m\3\ some of
the time, there is no hard data permitting OSHA to treat asphalt and
concrete milling differently with respect to imposing a respirator
requirement or to conclude that most concrete milling for that duration
will be above 50 [mu]g/m\3\ most of the time. Therefore, OSHA is not
including a respirator requirement in the final standard for either
asphalt or concrete milling, regardless of task duration.
IUOE recommended separate treatment of operators and tenders of
large milling machines since the exposures of operators are lower than
the exposures of tenders. IUOE further stated that operators are
located farther from the silica source than tenders, and appropriate
protection varies depending upon the location of the worker from the
silica source (Document ID 2262, p. 24). Evidence summarized above
shows that most tenders and operators will not experience silica
exposures in excess of 50 [mu]g/m\3\ when either of the control options
required by Table 1 is implemented. The exposure profile in Table
IV.5.8-C in Section 5.8 of Chapter IV of the FEA shows that the mean of
respirable crystalline silica exposures for operators of large milling
machines is 39 [micro]g/m\3\ (median 17 [micro]g/m\3\) and the slightly
higher mean for tenders is 57 [micro]g/m\3\ (median 27 [micro]g/m\3\).
Sample results presented in the exposure profile indicate that 79
percent of all large drivable milling machine operators already
experience silica levels below 50 [micro]g/m\3\ as a result of using
water spray intended to cool the cutting drum. Similarly, exposure
levels for most tenders (67 percent) working alongside large milling
machines are already below 50 [micro]g/m\3\ (see Tables IV.5.8-D and
IV.5.8-E in Section 5.8 of Chapter IV of the FEA). Therefore, OSHA
concludes that separate control measures do not need to be specified
for operators and tenders.
Proposed Table 1 contained dust control specifications for all
drivable milling machines, including when milling concrete. OSHA
received comments from IUOE, BCTD, and NAPA recommending that Table 1
be modified to separate asphalt milling and concrete milling and
require appropriate controls based on the respective exposure levels
(Document ID 2262, pp. 3, 17; 2371, Attachment 1, p. 26; 2181, p. 9).
Concrete milling is performed less frequently than asphalt milling
(Document ID 1231; 3583, Tr. 2213-2214), but silica exposures could be
higher than when milling asphalt. This difference is likely due to the
potential for the silica content to be higher in some concrete compared
with some asphalts (Document ID 1699), and also the softness and
"stickiness" of asphalt milled warm, which likely helps reduce
separation of the pavement components and perhaps limits dust release
in hot weather (Document ID 1251, p. 14; 1231). In addition, cutting
drums for concrete have smaller teeth, which can produce more fine dust
than is the case with asphalt (Document ID 1699). Anthony Bodway,
representing NAPA, also noted that silica exposures are higher for
concrete milling than for asphalt milling (Document ID 2181, p. 15). In
the FEA, OSHA concludes that water dust suppression and LEV systems
should be equally effective for concrete and asphalt in terms of
percent reduction in dust emissions when making cuts of four inches in
depth or less on any substrate (see Section 5.8 of Chapter IV of the
FEA). However, to the extent that milling concrete is dustier (i.e., a
larger amount of respirable dust is liberated), exposures to silica
during concrete milling may be somewhat higher than is the case for
asphalt milling even with the use of dust controls. As previously
explained, however, OSHA lacks quantitative data supporting these
comments to allow it to impose more stringent requirements,
specifically a requirement to use respirators, on concrete milling and
not on asphalt milling or to conclude that exposures will be over the
PEL for most operators most of the time doing either task.
The Silica/Asphalt Milling Machine Partnership conducted field
trials for large road milling machine LEV systems making cuts up to 11
inches deep (Document ID 4147; 4149). NIOSH evaluated exposures among
workers at four road construction sites (Document ID 4147, pp. v, 5-7,
13, Table 1; 4149, pp. v, 5-7, 13, Table 1). All the samples obtained
during the studies for operators and tenders combined showed that
exposure levels never exceeded 25 [mu]g/m\3\ when workers used machines
fitted with the LEV system, even when making cuts up to 11 inches deep
in asphalt (Document ID 4147, pp. v, 6-7, 13, Table 1; 4149, pp. v, 5-
7, 13, Table 1). In fact, the highest sample result (24 [mu]g/m\3\ for
a "groundsman" walking beside a milling machine removing 11 inches of
pavement on each pass) was the only sample result to exceed 13 [mu]g/
m\3\ during the two sampling dates (Document ID 4147, pp. v, 5-7, 13,
Table 1; 4149, pp. v, 5-7, 13, Table 1). Therefore OSHA is confident
that when removing asphalt only, workers can make cuts of any depth
without elevated exposures to silica.
However, other evidence contained in the record indicates that
cutting depths of more than four inches, in one pass, reduces the
effectiveness of controls (Document ID 3798, pp. 2, 14; 0555, p. 1).
Therefore OSHA has determined that if an employer is using a large
drivable milling machine to mill concrete, or road surface material
that contains both concrete and asphalt, deeper than four inches,
it is not covered by Table 1 and the employer will be required to
conduct exposure assessments and comply with the PEL in accordance
with paragraph (d) of the standard for construction.
IUOE also recommended excluding road demolition and asphalt
reclamation from asphalt milling in Table 1. Road demolition involves
removal of the road substructure in addition to the road surface
material and asphalt reclamation involves deeper cuts than typical
"mill and fill" cuts of four inches in depth or less. IUOE asserted
that this change should eliminate the need for respirator use by
operators during typical asphalt "mill and fill" operations when
engineering controls are properly implemented (Document ID 2262, p.
23).
Paragraph (c)(1)(xv) of the standard for construction excludes road
demolition and asphalt reclamation operations by limiting milling
activities on materials other than asphalt to cuts of four inches in
depth or less. The NIOSH studies of LEV for drivable milling machines
were conducted using large asphalt road milling machines (half-lane or
wider) and provide strong evidence that exposure levels below 50 [mu]g/
m\3\ (and even below 25 [mu]g/m\3\) can be achieved for employees
operating this type of equipment during typical shallow "mill and
fill" type road milling (i.e., cuts of four inches in depth or less)
(see Table IV.5.8-E in Section 5.8 of Chapter IV of the FEA). In one
NIOSH study, the removal of excess pavement during milling machine
demolition-type work (12 inches of pavement all at once), created a
large gap between the road and the milling machine drum enclosure,
allowing more dust to escape than during typical milling conditions
(Document ID 0555, p. 1). Also, a NIOSH trial, using only drum cooling
water and alternate spray nozzles, showed elevated silica exposure
levels when the road milling machine intermittently ground through the
asphalt layer into an aggregate and concrete underlayment (Document ID
3798, pp. 2, 14). Milling operators will rarely encounter these "worst
case" conditions (Document ID 0555, p. 1).
As previously stated, when milling only on asphalt, OSHA is
allowing cuts of any depth to be made when machines are equipped with
exhaust ventilation on the drum enclosure and supplemental water sprays
designed to suppress dust. When milling all other material to a depth
of more than four inches Table 1 does not apply and employers will be
required to conduct exposure assessments and comply with the PEL in
accordance with paragraph (d) of the standard for construction.
Additionally, road demolition, such as cutting the roadway into
manageable size pieces or squares that involves equipment other than
milling machines, such as saws, dowel drills, and various kinds of
heavy equipment, is not covered under this entry on Table 1 (see
Sections 5.3, 5.6, and 5.9 of Chapter IV of the FEA). In those
instances employers will need to follow the appropriate entries on
Table 1 for the equipment used or conduct exposure assessments and
comply with the PEL in accordance with paragraph (d) of the standard
for construction.
Crushing machines. Crushing machines are used to reduce large
rocks, concrete, or construction rubble down to sizes suitable for
various construction uses (see Section 5.10 of Chapter IV of the FEA).
When using crushers, paragraph (c)(1)(xvi) of the standard for
construction requires the use of equipment designed to deliver water
spray or mist for dust suppression at crusher and other points where
dust is generated (e.g., at hoppers, conveyors, sieves/sizing or
vibrating components, and discharge points), and a remote control
station or ventilated booth that provides fresh, climate-controlled air
to the operator. In the proposed standard, OSHA listed this entry as
"Rock Crushing." For the final standard OSHA has revised the title of
this entry to clarify that it includes concrete crushing, which is
often performed at demolition projects (Document ID 4073, Attachment
9a; 4073, Attachment 10a; 4073, Attachment 10b; 4234, Attachment 1, pp.
15-16). Proposed Table 1 would have required the use of wet methods or
dust suppressants or LEV systems at feed hoppers and along conveyor
belts. Information contained in the record indicates that LEV alone is
not effective in reducing exposures to 50 [mu]g/m\3\ or below, and that
it is necessary to require both a water spray system and either a
remote control station or filtered control booth to protect the
operator and employees engaged in crushing operations (see Section 5.10
of Chapter IV of the FEA).
Wet spray methods can greatly reduce the exposure levels of
operators and laborers who work near crushers tending the equipment,
removing jammed material from hoppers, picking debris out of the
material stream, and performing other tasks (Document ID 0203, pp. 3-6,
9; 1152; 1360; 1431, pp. 3-93-3-94; 3472, pp. 61-76; 4073, Attachment
9a; 4073, Attachment 15g, p. 1). These systems are currently available
and all crushers and associated machinery (conveyors, sizing screens,
discharge points) can be retrofitted with water spray or foam systems
(Document ID 1360; 0769; 0770; 0830; 0831; 0832). Spray systems can be
installed for remote control activation (Document ID 0203, pp. 11, 12,
14; 0830). The design and application of water spray systems will vary
depending on application. For airborne dust suppression, spray nozzles
should be located far enough from the target area to provide coverage
but not so far so as to be carried away by wind. In addition, nozzles
should be positioned to maximize the time that water droplets interact
with airborne dust. Droplet size should be between 10 and 150 [mu]m
(Document ID 1540, pp. 62-63). Alternatively, to prevent airborne dust
from being generated, nozzles should be located upstream of dust
generation points and positioned to thoroughly wet the material, and
the volume and size of droplets increased to ensure that the material
is sufficiently wetted (Document ID 1540, pp. 62-63). Information from
IUOE, BCTD, and the U.K. Health and Safety Executive shows that water
application can be expected to reduce exposure levels from 78 to 90
percent (Document ID 1330, p. 94; 4025, Attachment 2; 4073, Attachment
9a, pp. 1-4; 4073, Attachment 15g, p. 2).
The record did not contain information on exposures of tenders or
other employees working near a crusher operation without dust controls.
However, OSHA concludes that employees assisting with crusher
operations can be exposed to elevated levels of respirable crystalline
silica if water sprays are not used to control dust emissions. This
conclusion is based on evidence gathered by OSHA's contractor, ERG,
which visited a concrete crusher site. At the site, ERG observed a
crusher operator who spent time outside of a control booth shoveling
dried material from under a conveyor. The operator was exposed to 54
[mu]g/m\3\ TWA despite the time he spent in the booth where the silica
concentration was non-detectable (Document ID 0203, p. 9). Thus, this
operator's TWA exposure to silica can be entirely attributed to his
work around the crusher, much as a tender would have been doing.
Without the benefit of spending some time in the booth, and the fact
that the material being crushed was wet from rain and a freeze the
night before, the operator's exposure could have been even higher
(Document ID 0203). This indicates that tenders assisting with crusher
operations, who do not have the benefit of a booth for protection from
exposure, can be exposed to excessive levels of crystalline silica-
containing dust when water is not applied to areas where dust emissions
occur. The potential exposure of tenders and other employees who are
in the vicinity of crusher operations underscores the importance of
using water spray systems to reduce dust emissions. Such systems will
reduce dust exposures generally, thereby reducing exposures for tenders
and other employees in the vicinity of the crusher. Moreover, as discussed
below, OSHA is not specifying the use of LEV systems for crushing
operations on Table 1 of the final standard because LEV has not been
proven to be an effective or widely available alternative.
CISC argued that OSHA's preliminary finding that it was feasible to
achieve exposures of 50 [mu]g/m\3\ for tenders was unfounded and based
on no data on exposures of crushing machine tenders (Document ID 2319,
pp. 62-63). However, there are data in the record that inform the
Agency with respect to exposure of crushing machine tenders and the
effectiveness of dust controls in reducing their exposures to silica.
As described above, a crusher operator performing tasks along the
conveyor belt was exposed much as a tender would be. OSHA identified
one exposure measurement from an enforcement case for a laborer working
near a mobile crusher at an asphalt plant; the laborer's exposure was
43 [mu]g/m\3\ (8-hour TWA) based on a half-day of sampling (Document ID
0186, pp. 60-61). In addition to assisting with the crusher operation,
he also mixed a blend of sand, crushed concrete, asphalt, and soil,
which likely contributed to his exposure. He was working about 50 feet
from the crusher hopper where it was evident from the inspection report
that his exposure was much lower than that of the operator (Document ID
0186, p. 37). Bello and Woskie found exposures of demolition workers,
including those near a crushing operation, were below 50 [mu]g/m\3\
when water was used as dust controls for the demolition project
(Document ID 4073, Attachment 9a, pp. 3-4). OSHA thus rejects CISC's
contention that the absence of direct evidence of exposures to tenders
means that OSHA cannot regulate them or draw reasonable inferences
about the technological feasibility of controlling their exposures
(Document ID 2319, pp. 62-63).
Crushers are currently available with remote controls as standard
equipment (Document ID 0770; 0769, p. 2). The remote operation permits
the operator to stand back from the crusher or move upwind of dust
emissions. IUOE provided exposure data from large highway
reconstruction projects (Document ID 4025, Attachment 2, p. 9). Four
samples were collected where the operator platform was next to the
crushing operation and the operator was directly exposed to the crusher
emissions, resulting in a mean respirable crystalline silica exposure
of 410 [mu]g/m\3\ (Document ID 4025, Attachment 2, p. 9). Water use was
observed but no details were provided on the extent of use or the
systems in place. There was an approximately 66 percent reduction in
exposure to respirable crystalline silica of the crusher operator
working from a remote location (the remote location mean exposure was
140 [mu]g/m\3\) (Document ID 4025, Attachment 2, p. 9). IUOE addressed
the utility of remote controls in its comments on the proposed
standard, and requested that OSHA evaluate remote control technologies
as an exposure control method and include this type of control in Table
1 (Document ID 2262, p. 45; 3583, Tr. 2341).
An isolated and ventilated operator control booth can significantly
reduce the respirable silica exposures of employees associated with
crushing. At a visit to a crusher facility, ERG found non-detectable
levels of respirable crystalline silica inside the operator's control
booth, compared to a concentration of 103 [mu]g/m\3\ outside, despite
the booth having poor door seals, using recirculated rather than fresh
air, and having foam filters (as opposed to the MERV-16 or better
filters required by paragraph (c)(2)(iii)(E) of the standard for
construction) (Document ID 0203, pp. 12-13).
Other studies of operator cabs also reported silica or dust
exposure reductions ranging from 80 percent to greater than 90 percent
(Document ID 0589, p. 3; 0590, p. 54; 1431, p. 3-95). In the PEA, OSHA
recognized that control booths for crushers are commercially available,
although they are not commonly used on construction sites (Document ID
1720, p. IV-494). However, Kyle Zimmer, director of health and safety
for IUOE Local 478, stated during the hearing that "contractors report
that they are using portable crusher control booths with air
conditioning to operate the plant remotely" (Document ID 3583, Tr.
2341).
Evidence indicates that operators experience high exposure levels
when they must operate the crusher from above the feed hopper where
dust emissions are highest (Document ID 0030; 4073, Attachment 10a). In
light of this evidence, OSHA concludes that removing or isolating the
operator from this high-exposure location will be effective in lowering
the exposure of the operator. It is not clear that a control booth
alone will be sufficient to protect the operator from exposure to
silica, since operators periodically leave the booth to perform work
around the crusher, and the booth does not offer any protection for
other employees outside the booth such as tenders. A study of crushers
used in the South Australian extraction industry found operator
exposures ranged from 20 to 400 [mu]g/m\3\ (with a median of 65 [mu]g/
m\3\) while crushing dry material and using control booths or cabs
(Document ID 0647). Four of the eight sample results were at or below
50 [mu]g/m\3\, and at least two of the sampled workers occasionally
exited the cabins to free machinery blockages (Document ID 0647).
Because providing a filtered booth for the operator will not
protect other employees assisting with the operation or working nearby,
OSHA finds that a water-based dust suppression system is necessary to
prevent excessive exposure to silica among tenders and other employees
nearby. Therefore, OSHA has determined that the combination of water
use and either a remote control station or a ventilated booth for the
mobile crusher operator will be effective in minimizing exposure of the
operators and tenders. Summary data submitted by IUOE show that, with
water use, the addition of remote control stations further reduced
operator exposures by a factor of 3 (Document ID 4025, Attachment 2, p.
9). At the crusher operation visited by ERG, the operator's TWA
exposure was 54 [mu]g/m\3\ while working in a booth, and his exposure
would have been lower had water been applied to dried material he was
shoveling from under the conveyor.
In the proposed standard, OSHA required the use of a half-mask
respirator with an APF of 10 for all employees outside of the cab,
regardless of task duration or whether water sprays or LEV were
implemented. No respiratory protection was required for those employees
who operated the crusher from within the cab. OSHA proposed to require
respirator use because the data available at the time suggested that
neither water spray nor LEV systems would consistently reduce exposures
to 50 [mu]g/m\3\ or less, and that high exposures (even in excess of
the preceding PEL) could still occur. The crushing machine entry for
Table 1 in the final standard does not require respiratory protection
for tenders or mobile crusher operators because the evidence described
above indicates that the use of water systems, combined with a remote
control station or ventilated booth, will reduce most employees'
exposures to respirable silica to 50 [mu]g/m\3\ or less most
of the time.
Information from IUOE, BCTD and the U.K. Health and Safety
Executive show that water application can be expected to reduce
exposure levels by 78 to 90 percent (Document ID 1330; 4025, Attachment
2, pp. 7-23; 4073, Attachment 9a, pp. 1-4; 4073, Attachment 15g, p. 2).
Using the mid-point of this exposure control range (84 percent) and
applying it to the highest value in the exposure profile (300 [mu]g/
m\3\), would yield an exposure of slightly less than 50 [mu]g/m\3\ TWA
for an eight-hour work day. However, other evidence suggests that wet
spray methods may not consistently achieve exposures below 50 [mu]g/
m\3\ (Document ID 0030; 4025, Attachment 2, pp. 7-23), although little
detail was available on how water was applied. The evidence is clear
that the highest exposures occur at the hopper where material is fed by
front-end loaders or another conveyor, an area that is most likely to
be tended by the operator (Document ID 0030; 4073, Attachment 10a;
0203). Therefore, OSHA finds that it is also necessary to use a remote
control station or filtered booth to ensure the protection of crusher
operators.
The use of LEV systems was discussed in the NPRM, but evidence in
the record indicates that it has yet to be proven practicable for
mobile construction crushing equipment and is not currently used
extensively. William Turley of the Construction and Demolition
Recycling Association stated, "While there are crushing operations
that have used baghouses on the crusher, none use...ventilation
equipment for conveyors" (Document ID 2220, p. 2). Phillip Rice of
Fann Contracting contended that large crushing systems with multiple
conveyor belts would make it very difficult to use LEV cost effectively
(Document ID 2116, Attachment 1, p. 31). In contrast, Kyle Zimmer of
IUOE testified that employers are using dust collectors with baghouses
at some crushing operations (Document ID 3583, Tr. 2341). Nevertheless,
the record does not contain substantial and convincing evidence that
LEV alone can be applied when using mobile crushing machines to reduce
exposure levels to the same extent as water-based dust suppression
systems combined with the use of remote control stations or filtered
control booths. Therefore, OSHA is not specifying the use of LEV
systems for crushing operations on Table 1 of the final standard.
Heavy equipment and utility vehicles used to abrade or fracture
silica containing materials (e.g., hoe-ramming, rock ripping) or used
during demolition activities involving silica-containing materials.
Employees engaged in this task operate a variety of wheeled or tracked
vehicles ranging in size from large heavy construction equipment, such
as bulldozers, scrapers, loaders, cranes and road graders, to smaller
and medium sized utility vehicles, such as tractors, bobcats and
backhoes, with attached tools that are used to move, fracture, or
abrade rock, soil, and demolition debris (see Section 5.3 of Chapter IV
of the FEA). For example, equipment operators typically perform
activities such as the demolition of concrete or masonry structures,
hoe-ramming, rock ripping, and the loading, dumping, and removal of
demolition debris, which may include the loading and dumping of rock,
and other demolition activities (see Table IV.5.3-A in Section 5.3 of
Chapter IV of the FEA).
Paragraph (c)(1)(xvii) of the standard for construction requires
the operator to be in an enclosed cab, regardless of whether other
employees are in the area and the cab must meet the requirements of
paragraph (c)(2)(iii) of the standard for construction. When other
employees are engaged in the task, water, dust suppressants, or both
combined must also be applied as necessary to minimize dust emissions.
Paragraph (c)(2)(iii) of the standard for construction requires
enclosed cabs to be kept as free as practicable from settled dust, to
have door seals and closing mechanisms that work properly, to be under
positive pressure maintained through continuous delivery of fresh air,
to have gaskets and seals that are in good condition and work properly,
to have intake air that is filtered through a filter that is 95 percent
efficient in the 0.3-10.0 [mu]m range, and to have heating and cooling
capabilities.
In the proposed Table 1, OSHA included one entry for heavy
equipment and required that an enclosed cab be used. Although OSHA
analyzed all types of work with heavy equipment, including demolition,
in its preliminary feasibility analysis for heavy equipment, the
proposed Table 1 entry described the activity as "use of heavy
equipment during earthmoving activities."
Several commenters requested clarification on what uses of heavy
equipment OSHA intended to cover in the entry on proposed Table 1. IUOE
requested that OSHA include a definition of the range of "activities
encompassed within earthmoving," and specifically acknowledge whether
or not demolition activities are intended to be encompassed within this
definition of earthmoving on Table 1 (Document ID 2262, p. 7). IUOE
further explained that while earthmoving activities are "dust-filled"
and likely to result in some exposure to respirable silica, it was
inappropriate to combine earthmoving and demolition into one entry for
heavy equipment operators on Table 1 because earthmoving "does not
fracture or abrade silica-containing materials, and thus, does not
expose any heavy equipment operators to [a] high concentration of
respirable silica." IUOE opined that treating the two tasks separately
in the final rule would allow for better control of the hazards
(Document ID 2262, pp. 3, 6, 9, 14). LHSFNA supported the IUOE position
on demolition versus earthmoving and how it should be addressed in
Table 1 (Document ID 4207, p. 3). BCTD requested that Table 1 specify
that the Table 1 controls only apply when the listed task is performed
on or with silica-containing materials, noting that some operations,
such as earthmoving equipment, do not generate silica dust unless the
material contains silica (Document ID 2371, p. 24).
OSHA agrees with these recommendations and has separated heavy
equipment into two entries on Table 1: Paragraph (c)(1)(xvii) of the
standard for construction covers heavy equipment and utility vehicles
used to abrade or fracture silica-containing materials or during
demolition activities; paragraph (c)(1)(xviii) of the standard for
construction covers heavy equipment and utility vehicles used for tasks
such as grading and excavating (but not including demolishing,
abrading, or fracturing silica-containing materials). As explained
below, only heavy equipment and utility vehicles used to abrade or
fracture silica-containing materials or during demolition activities
require an enclosed cab at all times, whereas the employer has a choice
between an enclosed cab or applying water and/or dust suppressant when
these vehicles are used for tasks such as grading and excavating,
provided there are no other employees engaged in the task beside the
heavy equipment operator.
In the proposed standard, the only control option for heavy
equipment was to operate from within enclosed cabs. Several commenters
noted that enclosed cabs do not protect other employees, such as
laborers, who perform tasks in the area but remain outside the cab
(e.g., Document ID 2262, p. 24). Fann Contracting explained that not
including laborers on Table 1 would "render the table pointless
because employers would have to conduct frequent exposure assessments
of those employees" (Document ID 2116, Attachment 1, p. 3). Because of
the reasonable concerns raised by these commenters, OSHA has included
controls (water and/or dust suppressants) on Table 1 to protect
employees, other than the operator, who are engaged in the tasks.
The other employees included under this entry for Table 1 are typically
laborers who work nearby supporting the heavy equipment operator
(i.e., applying dust suppressant, spotting, and clearing debris). When
these materials contain crystalline silica, dust generated during these
activities is a primary source of exposure for the equipment operators
and the laborers.
NUCA expressed concern that operating from within a fully enclosed
cab may reduce visibility of the work zone and impair verbal
communication. and thereby pose potential safety risks (Document ID
2171, pp. 2, 4, 22). However, modern heavy equipment already come
equipped with enclosed, filtered cabs that are designed with visibility
in mind to allow the operator to perform the work required.
Furthermore, radios or cell phones can be used for communication if
necessary. Therefore, OSHA concludes that filtered, fully enclosed cabs
have been and can continue to be used without compromising worker
safety or the effectiveness of the cab.
The exposure profile in Table IV.5.3-B in Section 5.3 of Chapter IV
of the FEA shows that approximately 8 percent (1 out of 13 samples) of
heavy equipment operators performing demolition, abrading, or
fracturing activities have exposures above 50 [mu]g/m\3\. OSHA also
found a mean TWA exposure of 25 [mu]g/m\3\ for the six samples in the
record for laborers who assisted heavy equipment operators by providing
water for dust control during demolition projects. Table IV.5.3-C in
Section 5.3 of Chapter IV of the FEA compares silica exposures among
heavy equipment operators with the silica exposures of laborers engaged
in the same task. These data are a subset of the exposure profile
(Table IV.5.3-B in Section 5.3 of Chapter IV of the FEA) and provide
evidence of the effectiveness of applying dust suppressants for dust
control during demolition activities. The results for the six samples
for laborers were less than 50 [mu]g/m\3\ and were lower than the heavy
equipment operators not in an enclosed cab.
The information presented in OSHA's technological feasibility
analysis for heavy equipment operators and ground crew laborers
(Section 5.3 of Chapter IV of the FEA) and summarized above provides
evidence that the use of enclosed cabs and water and/or dust
suppressants will reduce exposures to 50 [mu]g/m\3\ or less for
operators and laborers when these controls are fully and properly
implemented. Therefore, OSHA is not requiring the use of respiratory
protection for heavy equipment operators and laborers who assist heavy
equipment operators during demolition activities involving silica-
containing materials or activities where silica-containing materials
are abraded or fractured, regardless of the duration of the task. Fann
Contracting questioned whether operators who use enclosed cabs would be
required to wear respiratory protection when exiting the equipment cab
(Document ID 2116, Attachment 1, p. 23). Since the specified control
method on Table 1 for this task requires the use of an enclosed cab,
the task is not being performed once the operator exits the enclosed
cab and the resulting exposure will have ceased, and no respiratory
protection is required in that circumstance. However, if other
abrading, fracturing, or demolition work is continuing while an
operator is outside the cab, that operator is considered to be an
employee "engaged in the task" and must be protected by the
application of water and/or dust suppressants.
Heavy equipment and utility vehicles used for tasks such as grading
and excavating but not including demolishing, abrading, or fracturing
silica-containing materials. When operating heavy equipment and smaller
sized utility vehicles for tasks such as grading and excavating that do
not involve demolition or the fracturing or abrading of silica,
paragraph (c)(1)(xviii) of the standard for construction requires that
the employee who will be operating the equipment operate from within an
enclosed cab or that the employer applies water and/or dust
suppressants as necessary to minimize dust emissions. If other
employees (e.g., laborer) are engaged in the task, water and/or dust
suppressants must be applied as necessary to minimize dust emissions
even where the operator of the equipment is working inside an enclosed
cab. However, the employer need not provide an enclosed, filtered cab
for the operator of the equipment.
Employees engaged in this task operate a variety of wheeled or
tracked vehicles ranging in size from large heavy construction
equipment, such as bulldozers, scrapers, loaders, and road graders, to
smaller and medium sized utility vehicles, such as tractors, bobcats
and backhoes, with attached tools that are used to excavate and move
soil, rock, and other silica-containing materials (see Section 5.3 of
Chapter IV of the FEA). Typically tasks conducted with this equipment
include earthmoving, grading, excavating, and other activities such as
moving, loading, and dumping soil and rock (see Table IV.5.3-B in
Section 5.3 of Chapter IV of the FEA). In addition, the railroad
industry uses such heavy equipment to dump and grade silica-containing
ballast in track work to support the ties and rails. Such track work is
generally subject to OSHA's construction standards, and the use of
heavy railroad equipment for this purpose is therefore covered under
this task in Table 1 of the final standard.
As discussed under the explanation of (c)(1)(xvii) of the standard
for construction, OSHA included one entry for heavy equipment operators
performing earthmoving activities in the proposed standard, but has
divided this entry to distinguish between the controls needed when
using heavy equipment for abrading, fracturing, or demolishing silica-
containing material, on the one hand, and for grading and excavating
silica-containing materials, on the other hand.
OSHA's exposure profile for earthmoving (i.e., excavation)
operations shows that a large majority of exposures (87.5 percent) are
below 25 [mu]g/m\3\ (see Section 5.3 of Chapter IV of the FEA). IUOE
commented that earthmoving should not be the focus of the rule, stating
that earthmoving activity "does not fracture or abrade silica-
containing materials, and thus, does not expose heavy equipment
operators to high concentrations of respirable silica" (Document ID
2262, p. 6). Martin Turek, assistant coordinator and safety
administrator for IUOE Local 150, stated that "it is unlikely that
moving soil or clay will generate respirable silica in concentrations .
. . above the [proposed] PEL" (Document ID 3583, Tr. 2358).
Under both entries, however, the specified controls to protect
laborers are the same. Thus, as when engaged in abrading, fracturing,
or demolition tasks near or alongside heavy equipment or utility
vehicles, OSHA has included a requirement that water and/or dust
suppressants be applied as necessary to minimize dust emissions so that
employees, including such laborers, who are engaged in such tasks as
grading and excavating silica-containing materials in conjunction with
operators of heavy equipment or utility vehicles are protected from
excessive exposure to respirable crystalline silica.
Enclosed cabs are not mandated for this task. They may be used if
the equipment operator is the only employee engaged in the task, as an
alternative to water and/or dust suppressants. However, where enclosed
cabs are used, they must meet the requirements outlined in paragraph
(c)(2)(iii) of the standard for construction. Those requirements specify
that enclosed cabs must be kept as free as practicable from settled dust,
must have door seals and closing mechanisms that work properly, must have
gaskets and seals that are in good condition and work properly, must be
under positive pressure maintained through continuous delivery of fresh
air, must have intake air that is filtered through a filter that is 95
percent efficient in the 0.3-10.0 [mu]m range, and must have heating and
cooling capabilities. If employees other than the equipment operator
are engaged in the task, Table 1 requires the application of water and/
or dust suppressants as necessary to minimize dust emissions, which
protects the operator as well as the laborers from silica exposures
above the PEL. As demonstrated by OSHA's exposure profile and the other
evidence in OSHA's technological feasibility for heavy equipment
operators and ground crew laborers (Section 5.3 of Chapter IV of the
FEA), wet dust suppression methods (e.g., water or calcium chloride)
are already a common and effective means for reducing exposures among
heavy equipment operators and laborers to 50 [mu]g/m\3\ or below.
Other commenters were concerned about the availability of enclosed
cabs on heavy equipment used for these types of earthmoving activities.
NUCA, NAHB, and CISC expressed concern regarding the cab requirements;
NUCA stated that the majority of earthmoving equipment is "equipped
with open canopies or unpressurized cabs" (Document ID 2171, p. 3;
2296, p. 32; 2319, p. 114). OSHA understands that some equipment
currently in use may not be equipped with enclosed, pressurized cabs as
required by Table 1 when enclosed cabs are used. Where an employer
chooses not to retrofit existing equipment for grading and excavating,
it must apply water and/or dust suppressants as necessary to minimize
dust emissions in order to comply with Table 1. Employers that neither
choose to retrofit equipment nor suppress dust using water or other
dust suppressants must comply with the requirements of paragraph (d) of
the standard for construction.
Evidence in the record indicates that exposures of employees during
common excavation and grading operations are likely to remain below 25
[mu]g/m\3\ most of the time. OSHA has therefore determined that
respiratory protection is not needed when the employer fully and
properly implements the controls on Table 1. Fann Contracting
questioned whether operators who use enclosed cabs would be required to
wear respiratory protection when exiting the equipment cab (Document ID
2116, Attachment 1, p. 23). As explained above, there is no requirement
for respiratory protection when the employee is entering or exiting the
cab since the task is not being performed at that time. However, if
other grading or excavation work is continuing while an operator is
outside the cab, that operator is considered to be an employee
"engaged in the task" and must be protected by the application of
water and/or dust suppressants.
Drywall finishers. Table 1 of the final rule does not specify
controls for drywall finishing. In the proposed standard, "drywall
finishing (with silica-containing material)" was an entry on Table 1.
The control options on proposed Table 1 were to use a pole sander or
hand sander equipped with a dust collection system or to use wet
methods to smooth or sand the drywall seam. However, information in the
rulemaking record indicates that drywall compound currently in use does
not usually contain silica (Document ID 2296, pp. 32, 36). NAHB
commented that much of the drywall joint compound currently used in
residential construction has no or very low silica content and members
can resolve any concerns regarding silica exposure by making sure to
use low silica containing product (Document ID 2296, pp. 32, 36). While
CISC agreed that contractors "can utilize `silica-free' joint compound
and perform drywall installation in a manner that creates exposures
below the proposed PEL," it expressed concern that "silica-free"
joint compound may contain more than trace amounts of silica, which
could result in exposures to silica (Document ID 2319, pp. 38, 43).
NIOSH tested bulk samples of a commercially available joint
compound and found up to 6 percent quartz, although silica was not
listed on the safety data sheet for the product (Document ID 0213, p.
5). However, in a more recent study, NIOSH determined that three of six
drywall compounds purchased at a retail store contained only trace
amounts of silica (less than 0.5 percent) (Document ID 1335, p. iii).
The researchers concluded that for the most part the results of each
sample analysis agreed with the composition stated in the
manufacturers' material safety data sheets (Document ID 1335, pp. 3-4,
7, 10). OSHA finds that joint compound is more accurately labeled than
it was in the past, and that manufacturers' labeling and SDSs are the
best source for determining whether employees may be exposed to silica
that could become respirable.
Additionally, the exposure profile includes 15 full-shift, personal
breathing zone samples of respirable crystalline silica. The median
exposure is 12 [mu]g/m\3\, the mean is 17 [mu]g/m\3\, and the range is
8 [mu]g/m\3\ (limit of detection (LOD)) to 72 [mu]g/m\3\, which was the
only result above 50 [mu]g/m\3\. The 72 [mu]g/m\3\ sample was obtained
for a worker performing overhead sanding directly above his breathing
zone (Document ID 1335, p. 13). One other sample exceeded 25 [mu]g/m\3\
(Document ID 1335, p. 14). Therefore, because no additional controls
are needed for most drywall finishers, OSHA has not included an entry
for drywall finishers in Table 1 in the final standard.
In the event that the use of silica-free joint compound is not
possible, or during renovation work where silica-containing joint
compound might be present, OSHA has determined that there are
engineering controls, as discussed in Section 5.2 of Chapter IV of the
FEA, that reduce exposure to respirable crystalline silica to 50 [mu]g/
m\3\ or below. In that situation employers will have to comply with
paragraph (d) of the standard for construction. Johnston Construction
Company commented that a requirement for air purifying respirators
should be included in the rule for one of the dustiest tasks performed
(Document ID 1951). OSHA agrees that sanding silica-free joint compound
can potentially generate high levels of respirable nuisance dust that
does not contain silica and for which respiratory protection may be
needed in some situations. While high exposures to nuisance dusts may
result from sanding joint compound, available evidence shows exposures
to respirable crystalline silica will be low.
Abrasive blasting. Table 1 of the final standard does not specify
controls for abrasive blasting; this is unchanged from the proposed
rule.
The Society for Protective Coatings (SSPC) requested that abrasive
blasting be included in Table 1 (Document ID 2120, p. 3). SSPC
recommended the inclusion of an abrasive blasting entry which
"simplifies compliance and eliminates the need for measuring workers'
exposure to silica, while still ensuring adequate protection for
workers" (Document ID 2120, p. 3). However, OSHA has determined that
it is not appropriate to add abrasive blasting to Table 1.
There are a variety of options available to employers to control
exposure to respirable crystalline silica during blasting operations.
As discussed in the technological feasibility analysis (Section 5.1 of
Chapter IV of the FEA), these include (1) use of abrasive media other
than silica sand to reduce crystalline silica dust emissions, (2) use
of wet blasting techniques, (3) use of dust suppressors, (4) use of
dust collection systems, and (5) use of hydro-blasting technologies
that avoid having to use abrasive media.
OSHA has decided that employees will be best protected when
employers, following the traditional approach set forth in paragraph
(d) in the standard for construction, choose among these dust control
strategies to select the controls that best fit the needs of each job.
OSHA's conclusion is based on the following additional considerations:
(1) Abrasive blasting operators must, separate from this rule, be
provided with and wear the respiratory protection required by 29 CFR
1926.57(f), and (2) employees helping with the operation, or who
otherwise must be in the vicinity of the operation, must also be
adequately protected by a combination of engineering controls, work
practices, and respirators. OSHA thus concluded that the Table 1
approach did not lend itself to specifying one or more controls that
would be suitable for all such operations. Furthermore, based on its
technological feasibility analysis for abrasive blasting (see Section
5.1 of Chapter IV of the FEA), respirators will be needed whatever
engineering or work practice control the employer uses under the
hierarchy of controls to lower silica exposure to the lowest level
feasible. Accordingly, based on the reasons discussed above, the Agency
is not mandating a particular dust control approach or approaches for
abrasive blasting and has therefore not included it as an entry in
Table 1 of the final standard.
Alternative Exposure Control Methods
Paragraph (d) of the standard for construction describes the
requirements for the alternative exposure control methods approach,
which applies for tasks not listed in Table 1 or where the employer
chooses not to follow Table 1 or does not fully and properly implement
the engineering controls, work practices, and respiratory protection
described in Table 1. The alternative exposure control methods approach
is similar to OSHA's traditional approach of demonstrating compliance
with a permissible exposure limit (PEL) through required exposure
assessments and controlling employee exposures through the use of
feasible engineering controls and work practices (i.e., the hierarchy
of controls). With the exception of the option to comply with either
paragraph (c) or paragraph (d), construction employers are required to
comply with all other paragraphs of the standard for construction.
Paragraph (d)(1) specifies that construction employers who must or
choose to follow paragraph (d) shall limit employee exposures to
respirable crystalline silica at or below the PEL of 50 [mu]g/m\3\ as
an 8-hour time weighted average. The PEL is fully discussed in the
summary and explanation of Permissible Exposure Limit.
Paragraph (d)(2) specifies the requirements for exposure
assessments, such as the types of assessments that are required under
the standard (i.e., performance or scheduled monitoring options), when
or how often those assessments must be conducted, methods of sample
analysis, employee notification of results, and the opportunity for
employees or their representatives to observe monitoring. These
requirements are fully discussed in the summary and explanation of
Exposure Assessment.
Paragraph (d)(3) specifies the methods of compliance, which include
a requirement to reduce exposure through feasible engineering and work
practice controls before using respiratory protection, and cross-
references standards for abrasive blasting. These requirements are
fully discussed in the summary and explanation of Methods of
Compliance.
Permissible Exposure Limit (PEL)
Paragraph (c) of the standard for general industry and maritime
(paragraph (d)(1) in the construction standard) establishes an 8-hour
time-weighted average (TWA) exposure limit of 50 micrograms of
respirable crystalline silica per cubic meter of air (50 [mu]g/m\3\).
This limit means that over the course of any 8-hour work shift,
exposures can fluctuate but the average exposure to respirable
crystalline silica cannot exceed 50 [mu]g/m\3\. The PEL is the same for
both general industry/maritime and construction. The PEL of 50 [mu]g/
m\3\ applies in the construction standard for tasks not listed on Table
1 or where the employer is not fully and properly implementing the
specified exposure control methods in paragraph (c) of the standard.
The PEL of 50 [mu]g/m\3\ does not apply directly to tasks listed on
Table 1, but the ability to achieve that PEL was the metric by which
OSHA decided on the specified exposure control(s) listed and whether
supplementary respiratory protection is required in some or all
circumstances for a particular task.
OSHA proposed a PEL of 50 [mu]g/m\3\ because the Agency
preliminarily determined that occupational exposure to respirable
crystalline silica at the previous PELs, which were approximately
equivalent to 100 [mu]g/m\3\ for general industry and 250 [mu]g/m\3\
for construction and shipyards, resulted in a significant risk of
material health impairment to exposed workers, and that compliance with
the proposed PEL would substantially reduce that risk. OSHA also
preliminarily found the level of risk remaining at the proposed PEL to
be significant, but considered a PEL of 50 [mu]g/m\3\ to be the lowest
level that was technologically feasible overall.
The PEL was a focus of comment in the rulemaking process, revealing
sharply divided opinion on the justification for and attainability of a
PEL of 50 [mu]g/m\3\. Many commenters representing labor unions, public
health associations, academic institutions, occupational health
professionals, and others expressed support for the proposed PEL (e.g.,
Document ID 1785, p. 2; 1878, p. 1; 2080, p. 1; 2106, p. 3; 2145, p. 3;
2166, p. 1; 2173, p. 2; 2178, Attachment 1, p. 2; 2318, p. 10; 2339, p.
7; 2341, p. 2; 3399, p. 4; 3403, p. 2; 3478, p. 1; 3601, Attachment 2,
p. 5; 3588, Tr. 3769; 4204, p. 50; 4207, p. 1). Other commenters
representing a wide range of industries, including construction,
foundries, concrete, brick and tile manufacturing, mineral excavation,
utility providers, and others, did not believe the proposed PEL was
appropriate. Stakeholders also offered opinions on the proposed
alternative PELs of 25 [mu]g/m\3\ and 100 [mu]g/m\3\.
Some commenters contended that OSHA's proposed PEL was too low,
arguing that the proposed limit was infeasible or not justified by the
health and risk evidence (e.g., Document ID 1964; 1992, pp. 1, 8-10;
2024, pp. 1-2; 2067, p. 3; 2075, pp. 1-2; 2104, p. 1; 2119, Attachment
1; 2143, pp. 1-2; 2171, p. 1; 2185, pp. 2-4; 2191, p. 3; 2210,
Attachment 1, p. 6; 2268; 2269, pp. 2-3; 2279, pp. 2, 9; 2284, p. 2;
2289, p. 3; 2296; p. 39; 2301, Attachment 1, pp. 7-9; 2305, pp. 4-5,
15; 2312, p. 2; 2348, Attachment 1, pp. 32-33; 2349, p. 3; 2350, pp.
10-11; 2384, pp. 2, 9; 2182, pp. 3-4; 2102, pp. 1, 3; 2211, pp. 3-4;
2283, p. 2; 2250, p. 2; 2288, p. 8; 2300, p. 2; 2338, p. 2; 2356, p. 2;
2376; 2379, Appendix 1, p. 53; 3275, pp. 1-2). Many of these commenters
supported the adoption of the proposed alternative PEL of 100 [mu]g/
m\3\.
Other commenters, including the United Automobile, Aerospace, and
Agricultural Implement Workers of America and the American Public
Health Association, contended that the remaining risk at 50 [mu]g/m\3\
is excessive and argued that OSHA should adopt a PEL of 25 [mu]g/m\3\
or even lower (e.g., Document ID 2163, Attachment 1, pp. 3, 13; 2176,
pp. 1-2; 3577, Tr. 851-852; 3582, Tr. 1853-1854; 3589, Tr. 4165; 4236,
pp. 5-6). The American Federation of Labor and Congress of Industrial
Organizations (AFL-CIO) urged OSHA to fully evaluate the evidence and
set a lower PEL if deemed to be feasible (Document ID 3578, Tr. 923-924).
After considering the evidence in the rulemaking record, OSHA is
establishing a PEL of 50 [mu]g/m\3\. OSHA's examination of health
effects evidence, discussed in Section V, Health Effects, and Section
VI, Final Quantitative Risk Assessment and Significance of Risk,
confirms the Agency's preliminary conclusion that exposure to
respirable crystalline silica at the previous PELs results in a
significant risk of material health impairment to exposed workers, and
that compliance with the revised PEL will substantially reduce that
risk. OSHA's Quantitative Risk Assessment indicates that a 45-year
exposure to respirable crystalline silica at the preceding general
industry PEL would lead to between 11 and 54 excess deaths from lung
cancer, 11 deaths from silicosis, 85 deaths from all forms of non-
malignant respiratory disease (including silicosis as well as other
diseases such as chronic bronchitis and emphysema), and 39 deaths from
renal disease per 1000 workers. Exposures at the preceding construction
and shipyard PEL would result in even higher levels of risk. As
discussed in Section VII of this preamble, Summary of the Final
Economic Analysis and Final Regulatory Flexibility Analysis, these
results clearly represent a risk of material impairment of health that
is significant within the context of the "Benzene" decision (Indus.
Union Dep't, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607 (1980)). OSHA
has determined that lowering the PEL to 50 [mu]g/m\3\ will reduce the
lifetime excess risk of death per 1000 workers to between 5 and 23
deaths from lung cancer, 7 deaths from silicosis, 44 deaths from non-
malignant respiratory disease, and 32 deaths from renal disease.
The Agency considers the level of risk remaining at the revised PEL
to be significant. However, based on the evidence evaluated during the
rulemaking process, OSHA has determined a PEL of 50 [mu]g/m\3\ is
appropriate because it is the lowest level feasible. As discussed in
Chapters IV and VI of Final Economic Analysis and Final Regulatory
Flexibility Analysis (FEA) and summarized in Section VII of this
preamble, the PEL is technologically and economically feasible for all
industry sectors, although it will be a technological challenge for
several affected sectors and will require the use of respirators for
certain job categories and tasks. As guided by the 1988 "Asbestos"
decision (Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1266
(D.C. Cir. 1988)), OSHA is including additional requirements in the
rule to further reduce the remaining risk. OSHA anticipates that the
ancillary provisions in the rule will further reduce the risk beyond
the reduction that will be achieved by the PEL alone.
OSHA has also determined that the proposed alternative PELs, 100
[mu]g/m\3\ and 25 [mu]g/m\3\, are inappropriate. As noted above,
significant risk to employees' health exists at the previous PELs, and
at and below the PEL of 50 [mu]g/m\3\. Because OSHA has determined that
a PEL of 50 [mu]g/m\3\ is technologically and economically feasible,
the Agency concludes that setting the PEL at 100 [mu]g/m\3\--a level
the Agency knows would continue to expose workers to significant risk
of material impairment to their health greater than is the case at 50
[mu]g/m\3\--would be contrary to the mandate in the OSH Act, which
requires the Secretary to promulgate a standard
...which most adequately assures, to the extent feasible, on the
basis of the best available evidence, that no employee will suffer
material impairment of health or functional capacity even if such
employee has regular exposure to the hazard dealt with by such
standard for the period of his working life (29 U.S.C. 655(b)).
Thus, the Agency has rejected the proposed alternative PEL of 100
[mu]g/m\3\.
Even though OSHA's risk assessment indicates that a significant
risk also exists at the revised action level of 25 [mu]g/m\3\, the
Agency is not adopting the alternative PEL of 25 [mu]g/m\3\ because a
PEL of 50 [mu]g/m\3\ is the lowest exposure limit that can be found to
be technologically feasible for many of the industries covered by the
rule. Specifically, OSHA has determined that the information in the
rulemaking record either demonstrates that the proposed alternative PEL
of 25 [mu]g/m\3\ would not be achievable for most of the affected
industry sectors and application groups or the information is
insufficient to conclude that engineering and work practice controls
can consistently reduce exposures to or below 25 [mu]g/m\3\. Therefore,
OSHA cannot find that the proposed alternative PEL of 25 [mu]g/m\3\ is
achievable for most operations in the affected industries (see Section
VII of this preamble and Chapter IV of the FEA). Moreover, OSHA also
concludes that it would hugely complicate both compliance with and
enforcement of the rule if it were to set a PEL of 25 [mu]g/m\3\ for a
minority of industries or operations where it would be technologically
feasible and a PEL of 50 [mu]g/m\3\ for the remaining industries and
operations where technological feasibility at the lower PEL is
demonstrably unattainable, doubtful or unknown.
Instead, OSHA has concluded that a PEL of 50 [mu]g/m\3\ is
economically and technologically feasible for all of the affected
industries and has decided to exercise its discretion to issue this
uniform PEL to avoid the enormous compliance and enforcement
complications that would ensue if it were to bifurcate the PEL (see
Section II, Pertinent Legal Authority, discussing the chromium (VI)
decision). Other issues related to OSHA's adoption of a PEL of 50
[mu]g/m\3\ are discussed below. The discussion is organized around the
following topics: Coverage of quartz, cristobalite, and tridymite; the
PEL as a gravimetric measurement of respirable dust; industry-specific
PELs; enhanced enforcement; environmental sources of crystalline silica
exposure; collection efficiency; coal dust; and CFR entries.
Coverage of quartz, cristobalite, and tridymite. As discussed in
the summary and explanation of Definitions, the PEL applies to the
three forms of crystalline silica (i.e., quartz, cristobalite, and
tridymite) covered under previous OSHA PELs. Specifically, paragraph
(b) of the rule defines the term "respirable crystalline silica" to
mean
...quartz, cristobalite, and tridymite contained in airborne
particles whose measurement is determined by a sampling device
designed to meet the characteristics for particle-size-selective
samplers specified in International Organization for Standardization
(ISO) 7708:1995: Air Quality--Particle Size Fraction Definitions for
Health-Related Sampling.
The proposed definition of respirable crystalline silica also would
have established a single PEL that would have encompassed the three
forms of silica covered under the previous OSHA silica PELs. While
commenters generally supported a single PEL for respirable crystalline
silica, they did not all agree on whether a single PEL should include
quartz, cristobalite, and tridymite (e.g., Document ID 1731, p. 2;
2315, p. 9). Some commenters argued that the PEL should include all
three forms; some suggested that the single PEL should be for only
quartz and cristobalite (e.g., Document ID 2177, Attachment B, p. 10;
2196, Attachment 1, p. 5; 3403, p. 4; 4212, p. 3) or only quartz
(e.g., Document ID 2185, p. 6). NIOSH noted that "tridymite is
extremely rare in workplaces, so a separate PEL probably cannot be
supported by epidemiologic evidence and may not be warranted for this
material (Document ID 2177, Attachment B, p. 10). Southern Company
argued that
...the inclusion of tridymite and cristobalite are not supported
by the data and, due to their rare nature, serve to unnecessarily
create upward bias of the exposure evaluations due to the laboratory
detection limitations (Document ID 2185, p. 2).
Halliburton Energy Services said that, given that OSHA has
acknowledged that the risk to workers exposed to a given level of
respirable crystalline silica may not be equivalent in different work
environments, OSHA's "one size fits all" silica PEL for different
forms of crystalline silica with varied physicochemical properties was
unwarranted (Document ID 2302, p. 5).
As discussed in Section V, Health Effects, OSHA has concluded,
based on the available scientific evidence, that quartz, cristobalite,
and tridymite have similar toxicity and carcinogenic potency. The
Agency therefore concludes that a single PEL is appropriate for quartz,
cristobalite, and tridymite.
The PEL as a gravimetric measurement of respirable dust. The
revised PEL, like OSHA's proposed PEL, is expressed as a gravimetric
measurement of respirable crystalline silica. The preceding PELs were
formulas that were inconsistent between industries and forms of
crystalline silica. For general industry (see 29 CFR 1910.1000, Table
Z-3), the PEL for crystalline silica in the form of respirable quartz
was based on two alternative formulas: (1) A particle-count formula
(PELmppcf = 250/(% quartz + 5) as respirable dust); and (2)
a mass formula proposed by the American Conference of Governmental
Industrial Hygienists (ACGIH) in 1968 (PEL = (10 mg/m\3\)/(% quartz +
2) as respirable dust). The general industry PELs for crystalline
silica in the form of cristobalite and tridymite were one-half of the
value calculated from either of the above two formulas for quartz. For
construction (29 CFR 1926.55, Appendix A) and shipyards (29 CFR
1915.1000, Table Z), the formula for the PEL for crystalline silica in
the form of quartz (PELmppcf = 250/(% quartz + 5) as
respirable dust), which requires particle counting, was derived from
the 1970 ACGIH threshold limit value (TLV). Based on the formulas, the
PELs for quartz, expressed as time-weighted averages (TWAs), were
approximately equivalent to 100 [mu]g/m\3\ for general industry and 250
[mu]g/m\3\ for construction and shipyards. As detailed in the
discussion of sampling and analysis in Chapter IV of the FEA, OSHA
finds that the formula based on particle-counting technology used in
the preceding general industry, construction, and shipyard PELs has
been rendered obsolete by respirable mass (gravimetric) sampling.
A number of commenters supported the proposed switch from these
formulas to a PEL expressed as a gravimetric measurement of respirable
crystalline silica. For example, several stakeholders, including the
American Foundry Society (AFS), the American Petroleum Institute, the
Fertilizer Institute, and the North American Insulation Manufacturers
Association, agreed that OSHA should revise the previous formulaic PELs
into straightforward concentration/gravimetric-based thresholds (e.g.,
Document ID 2101, p. 4; 2145, p. 3; 2278, p. 2; 2301, Attachment 1, p.
4; 4213, p. 8; 4229, p. 27). Others suggested the previous formulaic
PELs are confusing, complicated (e.g., Document ID 2175, p. 5; 2185, p.
2), and outdated (e.g., Document ID 2163, Attachment 1, p. 2; 2204;
3588, Tr. 3769). Ameren Corporation also expressed support for the
elimination of the PELs calculated based on the percent silica in the
sample (Document ID 2315, p. 8).
After considering the record on this issue, OSHA has decided to
adopt a PEL which is expressed as a gravimetric measurement of
respirable crystalline silica. OSHA expects that the revised PEL will
improve compliance because the PEL is simple and relatively easy to
understand, and is consistent with modern sampling and analytical
methods. In addition, OSHA finds that a uniform PEL will provide
consistent levels of protection for workers in all sectors covered by
the rule.
Industry-specific PELs. Some commenters urged OSHA to take an
industry-specific approach to regulating respirable crystalline silica
exposures. Southern Company urged OSHA to consider a vertical standard
that addresses industries with known negative health impacts from
silica-containing materials (Document ID 2185, p. 2). Battery Council
International asked OSHA to set the PEL based on relevant particle size
and the size distribution data and recommended that OSHA adjust the PEL
for different industry segments consistent with these data (Document ID
2361, pp. 1-2). Other commenters suggested that the PEL should be lower
for certain industries, such as hydraulic fracturing and dental
equipment manufacturing (Document ID 2282, Attachment 3, p. 12; 2374,
Attachment 1, p. 5).
OSHA considers the level of risk remaining at the new PEL of 50
[mu]g/m\3\ to be significant. Although OSHA expects the ancillary
provisions of the standard to reduce this risk below what engineering
and work practice controls alone can achieve, the Agency realizes that
lower PELs might be achievable in some industries and operations, which
would reduce this risk even further. However, as explained below, OSHA
concludes that the significant costs, including opportunity costs, of
devoting the resources necessary to attempting to establish and apply
multiple PELs for the diverse group of industries and operations
covered by the standard would undermine the value of this reduction
(see Building & Constr. Trades Dep't v. U.S. Dep't of Labor, 838 F.2d
1258, 1273 (D.C. Cir. 1988) (administrative difficulties, if
appropriately spelled out, could justify a decision to select a uniform
PEL)).
Requiring OSHA to set multiple PELs--taking into account the
feasibility considerations unique to each industry or operation or
group of them--would impose an enormous evidentiary burden on OSHA to
ascertain and establish the specific situations, if any, in which a
lower PEL could be reached. Such an onerous obligation would inevitably
delay, if not preclude, the adoption of important health standards. In
addition, the demanding burden of setting multiple PELs would be
complicated by the difficulties inherent in precisely defining and
clearly distinguishing between affected industries and operations where
the classification determines legal obligations. The definitional and
line-drawing problem is far less significant when OSHA merely uses a
unit of industries and operations for analytical purposes, and when it
sets a PEL in the aggregate, i.e., when its analysis is limited to
determining whether a particular PEL is the lowest feasible level for
affected industries as a whole. If OSHA had to set multiple PELs, and
assign industries or operations to those PELs, the problem would become
much more pronounced as the consequences of imprecise classifications
would become much more significant.
OSHA also finds that a uniform PEL will ultimately make the
standard more effective by making it easier for affected employers to
understand and comply with the standard's requirements. Moreover, a
uniform PEL makes it possible for OSHA to provide clearer guidance to
the regulated community and to identify non-compliant conditions. For
these reasons, OSHA has always interpreted Section 6(b)(5) of the Act
to accord the Agency substantial discretion to set the PEL at the lowest
level that is feasible for industries and operations as a whole. In
adopting the arsenic standard, for example, OSHA expressly declined to
set different PELs, finding that "[s]uch an approach would be extremely
difficult to implement" (43 FR 19584, 19601 (5/5/1978)). In that instance,
OSHA explained:
The approach OSHA believes appropriate and has chosen for this
and other standards is the lowest level achievable through
engineering controls and work practices in the majority of
locations. This approach is intended to provide maximum protection
without excessively heavy respirator use. Id.
OSHA has also rejected such an approach in rulemakings on
benzene and chromium (VI).
(see 43 FR 5918, 5947 (2/10/1978); 71 FR 10100, 10337-10338 (2/28/
2006)).
In the case of cotton dust, where OSHA did set different PELs for
certain discrete groups, the groups involved exposures to different
kinds of cotton dust and different degrees of risk. Even so, OSHA did
not adopt a unique PEL for every single affected sector (see 43 FR
27350, 37360-37361 (6/23/1978)); OSHA set one PEL for textile
industries and a separate PEL for non-textile industries, but expressly
rejected the option of adopting different exposure limits for each non-
textile industry). OSHA recognizes that the exception from the scope of
this rule for exposures that result from the processing of sorptive
clays results in a different PEL being enforced in that sector.
However, the processing of sorptive clays is a very small industry
sector, and OSHA finds that this sector can be readily segregated from
other industry sectors covered by the rule.
Enhanced enforcement. Several commenters suggested retaining the
preceding PELs and focusing OSHA efforts on enhanced enforcement rather
than on a new rule (e.g., Document ID 1741, Attachment 1; 2067, p. 4;
2183, p. 4; 2185, p. 2; 2210, Attachment 1, pp. 3, 7; 2261, pp. 2-3;
2283, p. 2; 2292, p. 2; 2344, p. 2; 2349, p. 3; 2363, p. 10; 3486, p.
1; 3496, p. 3). Some of these commenters, such as the Small Business
Administration's Office of Advocacy, indicated that OSHA data show
widespread noncompliance with the previous PELs and suggested that
silica-related illnesses could be linked to noncompliance (e.g.,
Document ID 2349, p. 3). Others, such as Arch Masonry, urged OSHA to
consider information and testimony about noncompliant work environments
as evidence of an enforcement problem rather than evidence to support a
new rule (e.g., Document ID 3587, Tr. 3651-3652). The Mercatus Center
asked OSHA to explain how improved enforcement of the existing rule is
not superior to a more stringent PEL (Document ID 1819, p. 9).
As discussed in Section V, Health Effects, OSHA does not find these
arguments persuasive. First, many of the commenters used OSHA's
enforcement data to make this point. These data were obtained during
inspections where non-compliance was suspected and thus were skewed in
the direction of exceeding the preceding PELs. As the Building and
Construction Trades Department, AFL-CIO (BCTD) explained, OSHA data
showing noncompliance with the preceding PEL is not representative of
typical exposure levels, since sampling for compliance purposes targets
worst-case exposure scenarios (Document ID 3581, Tr. 1634-1636).
Moreover, not all commenters agreed that overexposures were
"widespread." A few other commenters (e.g., AFS) thought that OSHA
substantially overstated the number of workers occupationally exposed
above 100 [mu]g/m\3\ in its PEA (Document ID 2379, Attachment B, p.
25). In either case, OSHA's analysis evaluated risks at various
exposure levels, as is required by the OSH Act. As noted above, the
available data indicate that exposure to respirable crystalline silica
at the preceding PELs results in a significant risk of material health
impairment among exposed employees. Simply enforcing the preceding PELs
will not substantially reduce or eliminate this significant risk.
Exposure Variability. Commenters, including the Asphalt Roofing
Manufacturers Association (ARMA), argued that because OSHA PELs are
never-to-be-exceeded limits, employers must maintain average exposures
well below the PEL to have confidence that exposures are rigorously
maintained at or below the PEL every day, for every worker (e.g.,
Document ID 2291, pp. 5-7). The Construction Industry Safety Coalition
(CISC) made a similar argument regarding the need to control exposure
levels to well below the PEL due to the variability of silica exposures
on construction worksites in order to assure compliance (Document ID
4217, p. 12).
OSHA recognizes that differences in exposure can occur due to
workplace variables such as fluctuations in environmental conditions or
air movement. However, many of the major sources of day-to-day
variability can be moderated by the consistent use of engineering
controls and appropriate work practices (Document ID 3578, Tr. 971;
3589, Tr. 4251-4252; 4234, Attachment 2, pp. 31-38).
OSHA has acknowledged and discussed exposure variability in past
rulemakings where the same issue was raised (e.g., benzene, 52 FR
34534; asbestos, 53 FR 35609; lead in construction, 58 FR 26590;
formaldehyde, 57 FR 22290; cadmium, 57 FR 42102; and chromium (VI), 71
FR 10099). In its asbestos rulemaking, for example, OSHA found that
industry's argument about uncontrollable fluctuations was exaggerated
because such fluctuations could be minimized through proper inspection
and maintenance of engineering controls and through proper training and
supervision of employees whose work practices affected exposure levels
(59 FR 40964, 40967 (8/10/94)). The Agency also noted that its
enforcement policy gives employers the opportunity to show that a
compliance officer's measurement over the PEL is unrepresentatively
high and does not justify a citation, thus alleviating the concern
employers might have that they will be cited on the basis of a single
measurement that results from uncontrollable fluctuations (59 FR at
40967).
Reviewing courts have held that OSHA's obligation to show that a
PEL can be achieved in most operations most of the time has been met
despite the presence of random exposure variability. These courts have
noted, in particular, OSHA's flexible enforcement policies, which allow
the Agency to take such exposure variability into account before
issuing a citation (e.g., Building & Constr. Trades Dept. v. Brock, 838
F.2d 1258 (D.C. Cir. 1988) ("Asbestos II")). In the Asbestos II case,
the D.C. Circuit cited with approval OSHA's policy of allowing for a
possible re-inspection if OSHA measured an asbestos exposure above the
PEL during an inspection. If the employer appeared to be using, to the
extent feasible, appropriate work practices and engineering controls,
OSHA could agree not to issue a citation at that time based on that
inspection and to re-inspect at a later time. Such a re-inspection
would help determine if that over-exposure was typical or simply a
random, uncontrollable fluctuation; OSHA could then determine whether
or not to issue a citation accordingly (Asbestos II at 1268; 51 FR
22653 (6/20/1986)). Thus OSHA has, in the past, adopted fair and
flexible enforcement policies to deal with the issue of exposure
variability and will do the same for enforcement of the new silica
standards.
Such an enforcement policy recognizes the possibility that OSHA may
measure silica exposures on a day when exposures are above the PEL due
to unforeseeable, random exposure variations. In such a case, when the
employer has previously monitored the work area, OSHA inspectors would
review the employer's long-term body of data demonstrating the exposure
pattern for tasks/operations that are representative of those under
OSHA's evaluation. After comparing the employer's exposure data with
OSHA's sampling results, OSHA's determination whether to resample would
be governed by the inspector's judgment of whether the OSHA sampling
results are representative.
Where an employer can show, based on a series of measurements made
pursuant to the sampling and analytical protocols set out in these
standards or other relevant data, that the OSHA one-day measurement may
be unrepresentatively high, OSHA may re-inspect the workplace and
measure exposures again. If, after such a reinspection, OSHA has reason
to believe that there are circumstances that account for the high
exposure measurement, OSHA may decide not to issue a citation.
For OSHA to consider a reinspection rather than citation, an
employer must demonstrate that the inspector's one-day sample is
unrepresentative of normal exposure levels. In most cases, this
demonstration would consist of a series of full shift measurements
representative of the exposure of the employee under consideration.
These measurements should consist of all valid measurements related to
the employee under consideration taken within the last year and should
show that only on rare occasions could random fluctuations result in
TWA concentrations above the PEL.
Environmental sources of crystalline silica exposure. Some
stakeholders raised concerns about the extent to which crystalline
silica dust from naturally-occurring environmental sources (e.g., in
southwestern regions of the United States) might contribute to employee
exposures to respirable crystalline silica and artificially inflate
sampling measurements (e.g., Document ID 1785, p. 4; 2116, Attachment
1, pp. 19-20; 3230, p. 1; 3533, p. 22). SMI cited an EPA study
published in 1996 (Document ID 3637), and indicated that mean
concentrations of ambient atmospheric respirable crystalline silica
across 22 cities in the United States range from 0.9 to 8 [mu]g/m\3\
(Document ID 3533, p. 20). OSHA recognizes that there can be occasions
when environmental sources of silica may affect occupational sampling
results. However, OSHA notes that the data utilized in the 1996 study
were originally published in an earlier (1984) journal article by Davis
et al. (Document ID 3852), and the EPA report included important
caveats about the environmental data that were available at the time
(Document ID 3637, pp. 3-29, 3-31--3-34). For example, the section of
the EPA report on "Limitations of Current Data" states:
The lack of current, direct measures of ambient quartz
concentrations is a major limitation of the data available for use
in estimating U.S. ambient silica concentrations (Document ID 3637,
pp. 3-31).
The report also indicated that "...another limitation of the
available data is the fact that neither current nor dated quartz
measurements were taken using PM10 samplers" (Document ID
3637, pp. 3-33).
In addition, OSHA notes that the sampling methodology used in the
Davis study does not measure respirable crystalline silica, as defined
in OSHA's silica rule. Rather, the Davis study presents data from
dichotomous samplers that are equipped with particle size selection
inlets. These samplers allow for measurement of two particle size
fractions: A fine fraction with particle sizes having aerodynamic
diameter less than 2.5 microns (PM2.5) and a coarse fraction
designed to eliminate particles greater than about 15 microns in
aerodynamic diameter (PM15). By contrast, OSHA's definition
for respirable crystalline silica is tied to an International
Organization for Standardization (ISO) sampling methodology that has
different size-specific mass collection efficiencies. Of particular
importance, the dichotomous samplers from the Davis study collect
particles with aerodynamic diameters between 10 and 15 microns that are
generally excluded from the ISO sampling methodology; and the
dichotomous samplers likely collect a considerably higher portion of
particles with aerodynamic diameters between 5 and 10 microns.
OSHA concludes that the sampling results presented in the Davis
study are not comparable to respirable crystalline silica measurements,
as defined in OSHA's rule. It is clear that the sampling methodology
considered in the Davis study would overstate respirable crystalline
silica levels measured using the ISO sampling methodology. Moreover,
OSHA has demonstrated that compliance with the PEL is technologically
feasible. OSHA's evaluation of the technological feasibility of the PEL
involved evaluation of thousands of respirable crystalline silica
samples collected in a variety of occupational settings that include
contributions from environmental sources in different geographic areas.
Because the exposure data considered by OSHA in its evaluation of the
technological feasibility of the PEL includes contributions from
environmental sources, these contributions are already taken into
account in determining the feasibility of the PEL. Therefore, OSHA
finds that environmental sources of respirable crystalline silica
exposure, to the extent they contribute to workplace exposures, are
already considered in the Agency's conclusion that the revised PEL is
feasible.
Collection efficiency. In the rule, OSHA is adopting the ISO/CEN
particle size-selective criteria for respirable dust samplers used to
measure exposures to respirable crystalline silica. Several commenters,
including U.S. Aggregates, the National Industrial Sand Association,
and the U.S. Chamber of Commerce, argued that moving from the current
criteria to the ISO/CEN convention effectively decreases the PEL and
action level below the levels intended, since more dust would be
collected by samplers that conform to the ISO/CEN convention than by
those that conform to the current criteria (Document ID 2174; 2195, p.
30; 2285, pp. 3-4; 2317, p. 2; 3456, p. 10; 4194, pp. 15-16). However,
as discussed in Chapter IV of the FEA, the Dorr-Oliver 10-mm cyclone
used by OSHA for enforcement of respirable dust standards conforms to
the ISO/CEN specification with acceptable bias and accuracy when
operated in accordance with OSHA's existing method (i.e., measurements
taken using the Dorr-Oliver 10-mm cyclone following OSHA's existing
method provide results that are consistent with the ISO/CEN convention,
and therefore are acceptable for measuring respirable crystalline
silica exposures under the rule). The change from the previous criteria
to the ISO/CEN convention is therefore effectively a continuation of
current practice.
Coal dust. Southern Company, the American Iron and Steel Institute,
and Ameren Corporation indicated that revising the respirable
crystalline silica PEL creates uncertainty with regard to the PEL for
coal dust, which continues to use the previous criteria for calculation
of respirable crystalline silica (Document ID 2185, p. 2; 2261, pp. 2,
5; 2315, p. 8). They urged the Agency to address how the existing coal
dust PEL will interact with the new PEL and calculation for exposure to
respirable crystalline silica. For example, Southern Company stated:
...it is unclear to us what the expectation would be in
evaluating and managing exposures to either of these substances when
the effective source of these exposures is the same. If both PELs
apply, this would mean duplicate or dual sampling (Document ID 2185,
p. 2).
Ameren also questioned whether employers would be required to sample
for both respirable crystalline silica and respirable coal dust on
workers who are potentially exposed to both substances. Ameren
suggested that OSHA should consider changing the PELs for amorphous
silica and coal dust so that they are consistent with the revised PEL
for respirable crystalline silica (Document ID 2315, pp. 2, 8).
OSHA clarifies that the respirable crystalline silica rule does not
change the existing PEL for coal dust. However, as indicated
previously, the Dorr-Oliver 10-mm cyclone used by OSHA for enforcement
of respirable dust standards exhibits acceptable bias against the ISO/
CEN specification when operated in accordance with OSHA's existing
method. Employers can continue to use the Dorr-Oliver cyclone to
evaluate compliance with the new respirable crystalline silica PEL, as
well as with the PEL for coal dust; duplicate sampling is not
necessary. Employers can also use other ISO/CEN-compliant samplers to
evaluate compliance with either or both PELs.
CFR entries. The rule revises entries for crystalline silica in 29
CFR 1910.1000 Table Z-1 to cross-reference the new standard, 1910.1053.
A comparable revision to 29 CFR 1915.1000 Table Z cross-references
1915.1053, which in turn cross-references 1910.1053. The entries for
crystalline silica in 29 CFR 1926.55 Appendix A are revised to cross-
reference 1926.1153. General industry standards are located in Part
1910; maritime standards are located in Part 1915; and construction
standards are located in Part 1926.
The preceding PELs for respirable crystalline silica are retained
in 29 CFR 1910.1000 Table Z-3, 29 CFR 1915.1000 Table Z, and 29 CFR
1926.55 Appendix A. Footnotes are added to make clear that these PELs
apply to any sectors or operations where the new PEL of 50 [mu]g/m\3\
is not in effect, such as the processing of sorptive clays. These PELs
are also applicable during the time between publication of the silica
rule and the dates established for compliance with the rule, as well as
in the event of regulatory delay, a stay, or partial or full
invalidation by the Court.
While the preceding PELs for respirable crystalline silica in 29
CFR 1910.1000 Table Z-3 are being retained, the PELs for total
crystalline silica dust are being deleted. OSHA proposed to delete the
previous general industry PELs for exposure to total crystalline silica
dust because development of crystalline silica-related disease is
related to the respirable fraction of, rather than total, dust exposure
(see Section V, Health Effects). This view is consistent with that of
ACGIH, which no longer has a Threshold Limit Value for total
crystalline silica dust. NIOSH does not have a Recommended Exposure
Level for total crystalline silica exposure, and neither the National
Toxicology Program nor the International Agency for Research on Cancer
has linked exposure to total crystalline silica dust exposure to
cancer, as they have with respirable crystalline silica exposure.
Exposure Assessment
Paragraph (d) of the standard for general industry and maritime
(paragraph (d)(2) of the standard for construction) sets forth
requirements for assessing employee exposures to respirable crystalline
silica. The requirements are issued pursuant to section 6(b)(7) of the
OSH Act, which mandates that any standard promulgated under section
6(b) shall, where appropriate, "provide for monitoring or measuring
employee exposure at such locations and intervals, and in such manner
as may be necessary for the protection of employees" (29 U.S.C.
655(b)(7)).
Assessing employee exposure to toxic substances is a well-
recognized and accepted risk management tool. The purposes of requiring
an assessment of employee exposures to respirable crystalline silica
include: Determination of the extent and degree of exposure at the
worksite; identification and prevention of employee overexposure;
identification of the sources of exposure; collection of exposure data
so that the employer can select the proper control methods to be used;
and evaluation of the effectiveness of those selected methods.
Assessment enables employers to meet their legal obligation to ensure
that their employees are not exposed in excess of the permissible
exposure limit (PEL) and to ensure employees have access to accurate
information about their exposure levels, as required by section 8(c)(3)
of the Act (29 U.S.C. 657(c)(3)). In addition, exposure data enable the
physicians or other licensed health care professionals (PLHCP)
performing medical examinations to be informed of the extent of
occupational exposures.
In the proposed standard for general industry and maritime, OSHA
included a requirement for employers to assess the exposure of
employees who are reasonably expected to be exposed to respirable
crystalline silica at or above the action level of 25 [micro]g/m\3\.
This obligation consisted of: An initial exposure assessment, unless
monitoring had been performed in the previous 12 months, or the
employer had objective data to demonstrate that exposures would be
below the action level under any expected conditions; periodic exposure
assessments, following either a scheduled monitoring option (with the
frequency of monitoring determined by the results of the initial and
subsequent monitoring) or a performance option (i.e., use of any
combination of air monitoring data or objective data sufficient to
accurately characterize employee exposures); and additional exposure
assessments when changes in the workplace resulted in new or additional
exposures to respirable crystalline silica at or above the action
level. The proposed standard also included provisions for the method of
sample analysis, employee notification of assessment results, and
observation of monitoring.
The proposed standard for construction included the same
requirements for exposure assessment as the proposed standard for
general industry and maritime; however, employers were not required to
assess the exposure of employees performing tasks on Table 1 where the
employer fully implemented the engineering controls, work practices,
and respiratory protection specified in Table 1. This exception to the
general requirement for exposure assessment was intended to relieve the
construction employer of the burden of performing an exposure
assessment in these situations, because appropriate control measures
are already identified.
Commenters, such as the American Federation of Labor and Congress
of Industrial Organizations (AFL-CIO), the American Society of Safety
Engineers (ASSE), the National Industrial Sand Association (NISA), and
the International Diatomite Producers Association, supported the
inclusion of an exposure assessment provision in the general industry
standard (e.g., Document ID 4204, pp. 52-54; 2339, p. 4; 2195, pp. 5-6,
9-10, 33; 2196, Attachment 1, p. 4), while other commenters, including
the American Public Health Association (APHA), the National Consumers
League (NCL) and Dr. James Cone, more generally concurred with OSHA's
proposed exposure assessment requirements (e.g., Document ID 2178,
Attachment 1, p. 2; 2373, p. 2; 2157, p. 7). However, commenters from
the construction industry, including the National Utility Contractors
Association, the American Subcontractors Association (ASA), the Leading
Builders of America (LBA), the Associated Builders and Contractors (ABC),
the Associated General Contractors of America, Fann Contracting, Inc.,
the National Association of Home Builders (NAHB), and the Construction
Industry Safety Coalition (CISC), as well as the American Fuel and
Petrochemical Manufacturers (AFPM), whose members regularly perform
construction tasks, contended that the proposed exposure assessment
requirements were unworkable, impractical, or exceedingly expensive due
to the dynamic construction environment where frequent changes in
environmental conditions, materials, tasks and the amount of time tasks
are performed, locations, and personnel would require constant
assessment and monitoring (e.g., Document ID 2171, p. 2; 2187, p. 5;
2269, p. 6; 2289, p. 6; 2323, p. 1; 2116, Attachment 1, pp. 13-14;
2296, pp. 24-25; 2350, p. 10; 3521, p. 7; 4217, pp. 12-13). More
specifically, commenters, including the Distribution Contractors
Association and the Sheet Metal and Air Conditioning Contractors
National Association (SMACNA), expressed concerns about the initial or
periodic assessment requirements (e.g., Document ID 2309, p. 3; 2226,
p. 2). Fann Contracting, ASA, and the Edison Electric Institute (EEI)
argued that initial and periodic exposure assessments do not make sense
for construction projects where conditions, tasks, and potential
exposures are constantly changing (Document ID 2116, Attachment 1, pp.
5, 16; 2187, p. 5; 2357, p. 13).
Other commenters from both construction and general industry,
including Ameren Corporation (Ameren), the Concrete Company, the Glass
Association of North America, the Washington Aggregates and Concrete
Association, the North American Insulation Manufacturers Association
(NAIMA), EEI, the National Stone, Sand, and Gravel Association (NSSGA),
the National Association of Manufacturers (NAM), Lafarge North America
(Lafarge), the Asphalt Roofing Manufacturers Association (ARMA), and
NAHB, argued that employers should not be required to conduct air
monitoring for employees on each shift, for each job classification,
and in each work area unless differences exist between shifts (e.g.,
Document ID 2315, p. 3; 2317, p. 2; 2215, p. 9; 2312, p. 2; 2348,
Attachment 1, p. 39; 2357, p. 23; 2327, Attachment 1, p. 18; 2380,
Attachment 2, pp. 26-28; 2179, p. 3; 2291, pp. 20-21). The American
Foundry Society (AFS) argued that repetitious full shift sampling is
also "burdensome and unnecessarily dangerous to employees who must
wear heavy and awkward equipment during the sampling session"
(Document ID 2379, Attachment B, p. 28). Commenters from the
construction industry, including ABC, LBA, the Hunt Construction Group,
and CISC argued that conducting air monitoring for employees on each
shift, for each job classification, and in each work area or
representative sampling of employees was not possible in constantly
changing construction environments (e.g., Document ID 2289, p. 6; 2269,
p. 6; 3442, pp. 2-3; 2319, pp. 83-84).
In response to these comments, OSHA restructured the exposure
assessment requirements in order to provide employers with greater
flexibility to meet their exposure assessment obligations using either
the performance option or the scheduled monitoring option. This
restructuring emphasizes the performance option in order to provide
additional flexibility for employers who are able to characterize
employee exposures through alternative methods. Commenters, including
Arch Masonry, Inc., the Building and Construction Trades Department,
AFL-CIO (BCTD), and the Precast/Prestressed Concrete Institute (PCI),
strongly supported this approach (e.g., Document ID 2292, p. 3; 3587,
Tr. 3655; 2371, Attachment 1, p. 10; 4223, p. 68; 2276, p. 10).
However, some commenters from the construction industry, including
CISC, Holes Incorporated, and ABC, considered a performance option to
be unworkable in the construction industry due to variability in
exposures (e.g., Document ID 2319, p. 85; 3580, Tr. 1448-1450; 4216,
pp. 2-3; 2226, p. 2). SMACNA also suggested that using historical air
monitoring data or objective data is not a legitimate option for small
employers who do not have this type of information (Document ID 2226,
p. 2).
While some small businesses and construction employers, like Holes
Incorporated, noted the difficulties with utilizing this option, there
were other similarly situated commenters, like Arch Masonry, that felt
the performance option was necessary to fulfill their exposure
assessment obligations (e.g., Document ID 3580, Tr. 1448-1450; 2292, p.
3). OSHA understands that the performance option may not be the
preferred choice of every employer, but it expects it will provide many
employers with substantial flexibility to meet their exposure
assessment obligations. Thus, the Agency has included the performance
option in the rule to complement the scheduled monitoring option.
In addition, the restructured standard for construction provides
added flexibility to construction employers in another significant way.
As described in the summary and explanation of Specified Exposure
Control Methods, where the employer fully and properly implements the
engineering controls, work practices, and respiratory protection
specified on Table 1 for a task, the employer is not required to assess
the exposure of employees engaged in that task or take additional
measures to ensure that the exposures of those employees do not exceed
the revised PEL (see paragraph (c)(1) of the standard for
construction). These revisions will relieve construction employers of
the burden of performing exposure assessment in many situations and
will provide them with greater flexibility to meet the requirements of
the standard, while still providing construction workers with the same
level of protection as that provided to other workers.
The rule also includes the scheduled monitoring option in order to
provide employers with a clearly defined, structured approach to
assessing employee exposures. Some commenters, such as CISC and ASSE,
urged OSHA to reconsider the inclusion of the scheduled monitoring
option, finding it to be impractical, infeasible, and burdensome (e.g.,
Document ID 2319, p. 86; 3578, Tr. 1052). On the other hand, NISA and
the Shipbuilders Council of America (SCA) supported the inclusion of
both a performance option and a scheduled monitoring option for
exposure assessment (Document ID 2195, p. 36; 2255, p. 3). AFL-CIO
supported periodic exposure assessments when exposures are above the
action level, with more frequent assessments required if exposures
exceed the PEL, as required under the scheduled monitoring option. It
also noted that similar requirements for periodic exposure assessments
are included in all other health standards that include exposure
monitoring and argued that they should also be included in the rule
(Document ID 4204, pp. 53-54). As discussed below, the Agency finds
that this option may be useful for certain employers and has retained
it in order to maximize flexibility in the rule.
General requirement for exposure assessment. Paragraph (d)(1) of
the standard for general industry and maritime (paragraph (d)(2)(i) of
the standard for construction) contains the general requirement for
exposure assessment. This provision, which remains the same as proposed
except for minor editorial changes, requires employers to assess the
exposure of each employee who is or may reasonably be expected to be
exposed to respirable crystalline silica at or above the action level
of 25 [micro]g/m\3\ in accordance with either the performance option or
the scheduled monitoring option. All employers covered by the standard
for general industry and maritime must abide by this provision.
However, as discussed in the summary and explanation of Specified
Exposure Control Methods, employers following the standard for
construction need only follow this provision, and the remainder of
paragraph (d)(2), for tasks not listed in Table 1 or where the employer
does not fully and properly implement the engineering controls, work
practices, and respiratory protection described in Table 1 (see
paragraph (d) of the standard for construction).
OSHA received a number of comments on this general provision. For
example, the Center for Progressive Reform (CPR) recommended that OSHA
require employers to conduct exposure assessments for each employee who
is or may "foreseeably" be exposed at or above the action level,
rather than only for those employees "reasonably expected" to be
exposed at or above the action level. They argued that "expected"
exposures might be lower than "foreseeable" exposures, and cited
equipment malfunctions and problems with respiratory protection
programs as situations that are "foreseeable" but may not be
"expected" (Document ID 4005, pp. 2-4). OSHA is not persuaded by this
argument. The Agency has decided that employers should not be required
to conduct assessments when employee exposures are only likely to
exceed the action level during a foreseeable, but unexpected event.
Therefore, an employer who reasonably expects the exposure of an
employee to remain below the action level does not have to assess the
exposure of that employee. However, if equipment malfunctions or other
unexpected events that could affect employee exposures occur, then the
employer may not be able to reasonably expect employee exposure to
remain below the action level and would be required to conduct an
assessment. As to CPR's comment that anticipated problems with
respiratory protection programs might be foreseeable, but unexpected,
OSHA reminds employers that this rule defines "employee exposure" to
mean exposure that would occur without the use of a respirator, so
inadequacies in an employer's respiratory protection program do not
affect the requirement for exposure assessment.
OSHA also received a number of comments on whether triggering
exposure monitoring at an action level of 25 [micro]g/m\3\ is
appropriate. Some commenters, including the Center for Effective
Government (CEG), APHA, NCL, and the Association of Occupational and
Environmental Clinics (AOEC) agreed that the proposed action level
trigger of 25 [micro]g/m\3\ for exposure assessment was needed (e.g.,
Document ID 2341, pp. 2-3; 2178, Attachment 1, p. 2; 2373, p. 2; 3399,
p. 5). CEG argued that an action level trigger of 25 [micro]g/m\3\ is
needed to ensure that exposures are reduced below the PEL (Document ID
2341, p. 3). AOEC commented that this trigger is needed to help protect
employees from crystalline silica isomorphs that are particularly toxic
(Document ID 3399, p. 5). Dr. Franklin Mirer, Professor of
Environmental and Occupational Health at CUNY School of Public Health,
representing AFL-CIO, and the United Automobile, Aerospace and
Agricultural Implement Workers of America (UAW), supported an action
level trigger, but stated that an action level below 25 [micro]g/m\3\
might be necessary in order to ensure that exposures are continuously
below the PEL (Document ID 2256, Attachment 3, p. 1; 2282, Attachment
3, pp. 1, 14).
Other commenters, including NISA, the Industrial Minerals
Association--North America, the Institute of Makers of Explosives
(IME), and the American Petroleum Institute (API), agreed that
assessing exposures at an action level was necessary, but believed the
action level should be 50 [micro]g/m\3\ (with a PEL of 100 [micro]g/
m\3\) (e.g., Document ID 2195, pp. 5-6; 2200, pp. 2-3; 2213, p. 3;
2301, Attachment 1, p. 4). NISA, for example, disagreed with OSHA's
characterization of significant risk at the proposed PEL and action
level, but argued that an action level trigger is needed in order to
maintain individual employees' exposures below the PEL (Document ID
2195, p. 6). Francisco Trujillo, safety director for Miller and Long,
proposed that exposure assessment should be triggered at an action
level of 75 [micro]g/m\3\ (with a PEL of 100 [micro]g/m\3\) for the
construction industry (Document ID 2345, p. 2). The American
Exploration and Production Council (AXPC) encouraged OSHA to trigger
all ancillary provisions in this rule (presumably including exposure
assessment) only when exposures are at or above an action level of 50
[micro]g/m\3\ after "discount[ing] exposure levels to reflect the
demonstrated effectiveness of respiratory protection..." (Document
ID 2375, Attachment 1, p. 3). The National Institute for Occupational
Safety and Health and CPR agreed that the action level should be the
trigger, but did not specify where the action level should be set
(Document ID 3579, Tr. 138-139; 2351, p. 10).
On the other hand, commenters including the Fertilizer Institute,
NSSGA, and Acme Brick Company and others in the brick industry did not
believe that an action level trigger for exposure assessment was
necessary and that the PEL should be the trigger for exposure
assessment (e.g., Document ID 2101, p. 10; 3583, Tr. 2303-2305; 2023,
p. 6). NSSGA argued that triggering sampling at the action level is not
sufficient to ensure compliance and instead, the individual employer
should determine when and how much sampling should be done in order to
ensure compliance with the PEL (Document ID 3583, Tr. 2303-2305). In
addition, several commenters, such as Lafarge, ASA, NSSGA, AFPM, the
Tile Council of North America (TCNA), the American Iron and Steel
Institute, and CISC discussed the challenges of measuring exposures at
an action level of 25 [micro]g/m\3\ (e.g., Document ID 2179, pp. 2-3;
2187, p. 5; 2327, Attachment 1, p. 16; 2350, p. 9; 2363, p. 4; 3492, p.
3; 2319, pp. 85-86).
OSHA concludes that an action level trigger for exposure assessment
is appropriate and agrees with commenters that an action level trigger
is needed in order to maintain exposures below the PEL. An action level
trigger, typically set at half the PEL, is consistent with other OSHA
health standards, such as the standards for 1,3-butadiene (29 CFR
1910.1051), methylene chloride (29 CFR 1910.1052), and chromium (VI)
(29 CFR 1910.1026). It provides employees and employers with some
assurance that variations in exposure levels will be accurately tracked
and exposures above the PEL will be identified and corrective actions
will be taken to protect employees. Assessment at the action level is
also necessary to determine eligibility for medical surveillance in the
standard for general industry and maritime. Where it is possible for
employers to reduce exposures below the action level, the trigger
encourages employers to do so in order to minimize their exposure
assessment obligations while maximizing the protection of employees'
health. As discussed in Chapter IV of the Final Economic Analysis
and Final Regulatory Flexibility Analysis (FEA), OSHA has also concluded
that it is technologically feasible to reliably measure employee
exposures at an action level of 25 [micro]g/m\3\.
OSHA disagrees with AXPC's suggestion to consider the effect of
respiratory protection when setting the exposure assessment trigger or
when triggering other provisions in this rule. Although there may be
some circumstances where a breathing zone sample does not reflect the
actual exposure of an employee who is being protected by a respirator,
this argument overlooks the fact that exposure monitoring is not a
single purpose activity. It is necessary to know employee exposure
levels without the use of respiratory protection to evaluate the
effectiveness of the required engineering and work practice controls
and to determine whether additional controls must be instituted. In
addition, monitoring is necessary to determine which respirator, if
any, must be used by the employee, and it is also necessary for
compliance purposes.
In addition, as discussed in the summary and explanation of Methods
of Compliance, respirators will not protect employees if they are not
fitted and maintained correctly and replaced as necessary or if
employees do not use them consistently and properly. If any one of
these conditions is not met, the protection a respirator provides to an
employee can be reduced or eliminated. Thus, discounting exposure
levels based on respirator use would be inappropriate. Moreover, the
requirement to use respiratory protection under paragraph (f)(1) of the
standard for general industry and maritime (paragraph (d)(3)(i) of the
standard for construction) is triggered by employee exposures that
exceed the PEL. It is unclear how AXPC believes the original exposure
assessment level (to which the discount would be applied) could be
derived without conducting an exposure assessment. Therefore, OSHA
declines to adopt this suggestion.
EEI urged OSHA to consider exempting intermittent and short-
duration work in the electric utility industry from the exposure
assessment requirement where employees exposed at or above the action
level wear appropriate personal protective equipment required under
either 29 CFR part 1910, subpart I or 29 CFR part 1926, subpart E
(Document ID 2357, pp. 13-14). While OSHA understands that conducting
exposure monitoring in these situations may present challenges, it is
important that employees who perform intermittent and short-duration
work in the electric utility industry have their exposures assessed;
the need for accurate information on exposures is no less for these
employees than for other employees exposed to respirable crystalline
silica at or above the action level. Where exposure assessments are
required for intermittent and short-duration work, the performance
option provides considerable flexibility for meeting these obligations.
However, other provisions of the rule may relieve employers from
conducting exposure assessments in some of these situations. For
general industry and maritime, in situations where employers have
objective data demonstrating that employee exposure will remain below
25 [micro]g/m\3\ as an 8-hour TWA under any foreseeable conditions,
including during intermittent and short-duration work, paragraph (a)(2)
exempts the employer from the scope of the rule. For construction, in
situations where employee exposure will remain below 25 [micro]g/m\3\
as an 8-hour TWA under any foreseeable conditions, including during
intermittent and short-duration work, paragraph (a) exempts the
employer from the scope of the rule. In addition, as discussed in the
summary and explanation of Scope, where tasks performed in a general
industry or maritime setting are indistinguishable from construction
tasks listed on Table 1, OSHA permits employers to comply with either
all of the provisions of the standard for general industry and maritime
or all of the provisions of the standard for construction. When this
occurs and the employer fully complies with the standard for
construction, the employer will not be required to conduct exposure
assessments for employees engaged in those tasks. Therefore, OSHA has
concluded that a specific exemption from exposure assessment
requirements for intermittent and short-duration work in the electric
utility industry is neither needed nor sufficiently protective.
As discussed above, paragraph (d)(1) of the standard for general
industry and maritime (paragraph (d)(2)(i) of the standard for
construction), unlike the general exposure assessment requirement in
the proposal, provides two options for exposure assessment--a
performance option and a scheduled monitoring option. The scheduled
monitoring option provides a framework that is familiar to many
employers, and has been successfully applied in the past. The
performance option provides flexibility for employers who are able to
characterize employee exposures through alternative methods. In either
case, employers must assess the exposure of each employee who is or may
reasonably be expected to be exposed to respirable crystalline silica
at or above the action level.
The performance option. Paragraph (d)(2) of the standard for
general industry and maritime (paragraph (d)(2)(ii) of the standard for
construction) describes the performance option. This option provides
employers flexibility to assess the 8-hour TWA exposure for each
employee on the basis of any combination of air monitoring data or
objective data sufficient to accurately characterize employee exposures
to respirable crystalline silica. OSHA recognizes that exposure
monitoring may present challenges in certain instances, particularly
when tasks are of short duration or performed under varying
environmental conditions. The performance option is intended to allow
employers flexibility in assessing the respirable crystalline silica
exposures of their employees.
Where the employer elects this option, the employer must conduct
the exposure assessment prior to the time the work commences, and must
demonstrate that employee exposures have been accurately characterized.
To accurately characterize employee exposures under the performance
option, the assessment must reflect the exposures of employees on each
shift, for each job classification, in each work area. However, under
this option, the employer has flexibility to determine how to achieve
this. For example, under this option an employer could determine that
there are no differences between the exposure of an employee in a
certain job classification who performs a task in a particular work
area on one shift and the exposure of another employee in the same job
classification who performs the same task in the same work area on
another shift. In that case, the employer could characterize the
exposure of the second employee based on the characterization of the
first employee's exposure.
Accurately characterizing employee exposures under the performance
option is also an ongoing duty. In order for exposures to continue to
be accurately characterized, the employer is required to reassess
exposures whenever a change in production, process, control equipment,
personnel, or work practices may reasonably be expected to result in
new or additional exposures at or above the action level, or when the
employer has any reason to believe that new or additional exposures at
or above the action level have occurred (see discussion below of
paragraph (d)(4) of the standard for general industry and maritime and
paragraph (d)(2)(iv) of the standard for construction).
When using the performance option, the burden is on the employer to
demonstrate that the data accurately characterize employee exposure.
However, the employer can characterize employee exposure within a
range, in order to account for variability in exposures. For example, a
general industry or maritime employer could use the performance option
and determine that an employee's exposure is between the action level
and the PEL. Based on this exposure assessment, the employer would be
required under paragraph (i)(1)(i) to provide medical surveillance if
the employee is exposed for more than 30 days per year. Where an
employer uses the performance option and finds exposures to be above
the PEL after implementing all feasible controls, the employer would be
required to provide the appropriate level of respiratory protection.
For example, an employer who has implemented all feasible controls
could use the performance option to determine that exposures exceed the
PEL, but do not exceed 10 times the PEL. The employer would be required
under paragraph (g) of the standard for general industry and maritime
(paragraph (e) of the standard for construction) to provide respiratory
protection with an assigned protection factor of at least 10, as well
as medical surveillance for employees exposed for more than 30 days per
year.
Several commenters requested that OSHA provide more guidance as to
how employers should implement the performance option. Commenters,
including AFL-CIO, the International Union of Bricklayers and Allied
Craftworkers (BAC), the United Steelworkers, BCTD, and the
International Union of Operating Engineers (IUOE), felt that
clarification and guidance on the kind of data that may or may not be
relied upon was needed in order to ensure that the data adequately
reflected employee exposures (Document ID 2256, Attachment 2, p. 10;
2329, p. 4; 2336, p. 6; 2371, Attachment 1, pp. 11-13; 3581, Tr. 1693-
1694; 3583, Tr. 2341; 4204, p. 54; 4223, p. 70). The American College
of Occupational and Environmental Medicine recommended that OSHA more
precisely specify the type and periodicity of collection of industrial
hygiene data that would be required to assure representative exposure
measurements (Document ID 2080, p. 4). The American Industrial Hygiene
Association (AIHA) argued that a sufficient number of samples and a
sampling strategy that is representative of the employees and tasks
being sampled is needed to ensure that exposure assessments using the
performance option accurately characterize employee exposure (Document
ID 3578, Tr. 1049-1050). To do this, AIHA suggested that OSHA,
...point to American Industrial Hygiene Association language on
what an acceptable judgment of exposure can be based upon: number of
samples for statistical validity, an acceptable tolerance for an
error in that statistical judgment, and the connection of the sample
set to a set of conditions occurring during the worker exposure
measurement (Document ID 2169, p. 3).
CISC also indicated that the construction industry needed
additional guidance, such as how often and when monitoring should be
conducted under the performance option in order to determine whether it
would be effective and viable (Document ID 2319, p. 86). Charles
Gordon, a retired occupational safety and health attorney, suggested
the performance option was too flexible and needed to be omitted until
real-time monitoring could be incorporated into it (Document ID 2163,
Attachment 1, p. 17).
OSHA has not included specific criteria for implementing the
performance option in the rule. Since the goal of the performance
option is to give employers flexibility to accurately characterize
employee exposures using whatever combination of air monitoring data or
objective data is most appropriate for their circumstances, OSHA
concludes it would be inconsistent to specify in the standard exactly
how and when data should be collected. Where employers want a more
structured approach for meeting their exposure assessment obligations,
OSHA also provides the scheduled monitoring option.
OSHA does, however, offer two clarifying points. First, the Agency
clarifies that when using the term "air monitoring data" in this
paragraph, OSHA refers to any monitoring conducted by the employer to
comply with the requirements of this standard, including the prescribed
accuracy and confidence requirements. Second, the term does not include
historic air monitoring data, which are "objective data." Additional
discussion of the types of data and exposure assessment strategies that
may be used by employers as "objective data" to accurately
characterize employee exposures to respirable crystalline silica can be
found in the summary and explanation of Definitions.
For example, trade associations and other organizations could
develop objective data based on industry-wide surveys that members
could use to characterize employee exposures to respirable crystalline
silica. For example, the National Automobile Dealers Association (NADA)
conducted air monitoring for employees performing a variety of tasks in
automobile body shops (Document ID 4197; 4198). NADA worked to ensure
that the results of the study were representative of typical
operations. The sampling procedures and techniques for controlling dust
were documented. These data may allow body shops that perform tasks in
a manner consistent with that described in the NADA survey to rely on
this objective data to characterize employee exposures to respirable
crystalline silica.
Employers could also use portable, direct-reading instruments to
accurately characterize employee exposures to respirable crystalline
silica. These devices measure all respirable dusts, not only
crystalline silica. But where the employer is aware of the proportion
of crystalline silica in the dust, direct-reading instruments have the
advantage of providing real-time monitoring results. For example, in a
facility using pure crystalline silica, the employer could assume that
the respirable crystalline silica concentration in the air is
equivalent to the respirable dust measurement provided by the direct
reading instrument. Where exposures involve dusts that are not pure
crystalline silica, the employer could determine the concentration of
crystalline silica by analysis of bulk samples (e.g., geotechnical
profiling) or information on safety data sheets, and calculate the air
concentration accordingly. In such situations, the analysis of bulk
samples or safety data sheets would be part of the objective data
relied on by the employer. In addition, employers could use a wide
variety of other types of objective data to assess exposures, including
data developed using area sampling or area exposure profile mapping
approaches. Where new methods become available in the future that
accurately characterize employee exposure to respirable crystalline
silica, data generated using those methods could also be considered
objective data and could be used by employers to assess employee
exposures.
Where employers rely on objective data generated by others as an
alternative to developing their own air monitoring data, they will be
responsible for ensuring that the data relied upon from other sources
are accurate measures of their employees' exposures. Thus, the burden
is on the employer to show that the exposure assessment is sufficient
to accurately characterize employee exposures to respirable crystalline
silica.
CPR suggested that OSHA require an independent audit of employers'
objective data calculations to ensure that they provide the same degree
of assurance of accurate exposure characterization as air monitoring
data (Document ID 2351, pp. 12-13). As explained above, employers using
the performance option must ensure that the exposure assessment is
sufficient to accurately characterize employee exposure to respirable
crystalline silica. Because employers already bear the burden of
ensuring accurate characterization of employee exposures, OSHA does not
find that an independent audit of employers' objective data is
necessary to assure proper compliance.
The Laborers' Health and Safety Fund of North America urged OSHA to
collect and post all objective data that meet the definition on its Web
site, so that it could be used by anyone performing the same task under
the same conditions (Document ID 2253, p. 4). Other commenters,
including BAC, BCTD, and IUOE, agreed that developing a means for
collecting and sharing objective data was important (Document ID 2329,
p. 4; 2371, Attachment 1, p. 13; 3583, Tr. 2394-2395). OSHA recognizes
that the collection and sharing of objective data can be a useful tool
for employers characterizing exposures using the performance option.
OSHA anticipates that there could be a substantial volume of objective
data that would require significant resources to collect, organize,
present, and maintain in a way that is accessible, understandable, and
valuable to employers. The Agency does not have the resources to do
this; however, employers, professional and trade associations, unions,
and others that generate objective data are encouraged to aggregate and
disseminate this type of information.
As with the standard for chromium (VI), 29 CFR 1910.1026, OSHA does
not limit when objective data can be used to characterize exposure.
OSHA permits employers to rely on objective data for meeting their
exposure assessment obligations, even where exposures may exceed the
action level or PEL. OSHA's intent is to allow employers flexibility to
assess employee exposures to respirable crystalline silica, but to
ensure that the data used are accurate in characterizing employee
exposures. For example, where an employer has a substantial body of
data (from previous monitoring, industry-wide surveys, or other
sources) indicating that employee exposures in a given task exceed the
PEL, the employer may choose to rely on those data to determine his or
her compliance obligations (e.g., implementation of feasible
engineering and work practice controls, respiratory protection, medical
surveillance).
OSHA has also not established time limitations for air monitoring
results used to characterize employee exposures under the performance
option. Although the proposed standard would have limited employers
using air monitoring data for initial exposure assessment purposes to
data collected no more than twelve months prior to the rule's effective
date, there were no such time restrictions on monitoring data used to
conduct periodic exposure assessments under the performance option.
Nevertheless, many commenters, including Ameren, TCNA, NAM, NAIMA,
Associated General Contractors of New York State, ARMA, EEI, the
National Rural Electric Cooperative Association, the Glass Packaging
Institute, Verallia North America, and Holes Incorporated, found the
12-month limit on the use of monitoring results for initial exposure
assessments using existing data to be too restrictive (e.g., Document
ID 2315, p. 3; 2363, p. 6; 2380, Attachment 2, pp. 28-29; 3544, pp. 12-
13; 2145, p. 3; 2291, pp. 2, 21-23; 2348, pp. 37-39; 2357, pp. 22-23;
2365, pp. 10-11, 23; 2290, p. 4; 3493, p. 6; 3584, Tr. 2848; 3580, Tr.
1492). For example, Southern Company noted that:
We have been collecting data on silica for several years as well
as sharing within our industry group. This provision seems to be
arbitrary and provides only a short window of time for data
collection while eliminating the value and importance of past
[efforts] we have placed on this issue (Document ID 2185, p. 7).
OSHA has been persuaded by these commenters not to establish time
limitations for monitoring results used to assess exposures under the
performance option, as long as the employer can demonstrate the data
accurately characterize current employee exposures to respirable
crystalline silica. The general principle that the burden is on the
employer to show that the data accurately characterize employee
exposure to respirable crystalline silica applies to the age of the
data as well as to the source of the data. For example, monitoring
results obtained 18 months prior to the effective date of the standard
could be used to determine employee exposures, but only if the employer
could show that the data were obtained during work operations conducted
under workplace conditions closely resembling the processes, types of
material, control methods, work practices, and environmental conditions
in the employer's current operations. Regardless of when they were
collected, the data must accurately reflect current conditions.
Any air monitoring data relied upon by employers must be maintained
and made available in accordance with the recordkeeping requirements in
paragraph (k)(1) of the standard for general industry and maritime
(paragraph (j)(1) of the standard for construction). Any objective data
relied upon must be maintained and made available in accordance with
the recordkeeping requirements in paragraph (k)(2) of the standard for
general industry and maritime (paragraph (j)(2) of the standard for
construction).
NISA commented that a performance option needs to be consistently
interpreted by compliance officers in order for such an approach to be
truly useful to employers (Document ID 2195, p. 36). OSHA agrees. OSHA
regularly establishes policies and directives to guide compliance
officers in a uniform, consistent manner when enforcing standards.
These policies ensure that all the provisions of OSHA standards,
including performance options, are consistently applied in the field.
The scheduled monitoring option. Paragraph (d)(3) of the standard
for general industry and maritime (paragraph (d)(2)(iii) of the
standard for construction) describes the scheduled monitoring option.
This option provides employers with a clearly defined, structured
approach to assessing employee exposures. Under paragraph (d)(3)(i) of
the standard for general industry and maritime (paragraph
(d)(2)(iii)(A) of the standard for construction), employers who select
the scheduled monitoring option must conduct initial monitoring to
determine employee exposure to respirable crystalline silica.
Monitoring to determine employee exposures must represent the
employee's time-weighted average exposure to respirable crystalline
silica over an eight-hour workday. Samples must be taken within the
employee's breathing zone (i.e., "personal breathing zone samples" or
"personal samples"), and must represent the employee's exposure
without regard to the use of respiratory protection. OSHA intends for
employers using the scheduled monitoring option to conduct initial
monitoring as soon as work begins. Employers must be aware of the level
of exposure when work is performed to identify situations where control
measures are needed.
Under the scheduled monitoring option, just as under the
performance option, employers must accurately characterize the exposure
of each employee to respirable crystalline silica. In some cases, this
will entail monitoring all exposed employees. In other cases,
monitoring of "representative" employees is sufficient.
Representative exposure sampling is permitted when several employees
perform essentially the same job on the same shift and under the same
conditions. For such situations, it may be sufficient to monitor a
subset of these employees in order to obtain data that are
"representative" of the remaining employees. Representative personal
sampling for employees engaged in similar work, with respirable
crystalline silica exposure of similar duration and magnitude, is
achieved by monitoring the employee(s) reasonably expected to have the
highest respirable crystalline silica exposures. For example, this
could involve monitoring the respirable crystalline silica exposure of
the employee closest to an exposure source. The exposure result may
then be attributed to other employees in the group who perform the same
tasks on the same shift and in the same work area.
Exposure monitoring should include, at a minimum, one full-shift
sample taken for each job function in each job classification, in each
work area, for each shift. These samples must consist of at least one
sample characteristic of the entire shift or consecutive representative
samples taken over the length of the shift. Where employees are not
performing the same job under the same conditions, representative
sampling will not adequately characterize actual exposures, and
individual monitoring is necessary.
Stakeholders offered numerous comments and suggestions about the
proposed provisions that would have required employers to assess
employee exposure on the basis of personal breathing zone air samples
that reflect the exposure of employees on each shift, for each job
classification, and in each work area. Many of these comments and
suggestions involved specific concerns with the practicality and
necessity of assessing employee exposure on each shift, for each job
classification, and in each work area (e.g., Document ID 2315, p. 3;
2317, p. 2; 2215, p. 9; 2312, p. 2; 2348, Attachment 1, p. 39; 2357, p.
23; 2327, Attachment 1, p. 18; 2380, Attachment 2, pp. 26-28; 2179, p.
3; 2291, pp. 20-21). As discussed previously, OSHA responded to these
comments by restructuring the exposure assessment requirements to allow
employers to use the performance option for all exposure assessments
required by this rule. Although employers utilizing the performance
option must still accurately characterize the exposures of each of
their employees, these employers have latitude to broadly consider the
best way this can be accomplished.
NAIMA suggested that OSHA should make adjustments to exposure
monitoring requirements for extended work shifts (e.g., 12-hour
shifts). They proposed that
...exposure assessment should follow the standard practice of
measuring any continuous 8-hour period in the shift that is
representative, or allow using multiple samples to sample the entire
extended shift and selecting the 8 hours which represent the highest
potential exposure (Document ID 3544, p. 14).
OSHA agrees that this is an appropriate way to conduct sampling for
extended work shifts. This practice is already reflected in the OSHA
Technical Manual, which describes the two approaches advanced by NAIMA,
including sampling the worst (highest exposure) eight hours of a shift
or collecting multiple samples over the entire work shift and using the
highest samples to calculate an 8-hour TWA (OSHA Technical Manual,
Section II, Chapter 1, 2014, https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html#extended_workshifts).
CISC argued that the ASTM Standard E 2625-09, Standard Practice for
Controlling Occupational Exposure to Respirable Crystalline Silica for
Construction and Demolition Activities, takes what CISC considered to
be a more reasonable approach to representative air monitoring in the
construction industry. The ASTM standard states that measurements
"need to be representative of the worker's customary activity and be
representative of work shift exposure" (Document ID 1504). CISC argued
that this approach is,
...more reasonable because it inherently recognizes that an
employee's exposure would vary on any given day due to a multitude
of factors and that an employer should attempt to understand the
exposure levels when performing his/her customary activity (Document
ID 2319, pp. 83-84).
OSHA acknowledges that variability in exposures is a concern in the
construction industry. The construction standard does not require
exposure assessment for employees engaged in a task identified on Table
1 where the employer fully and properly implements the specified
exposure control methods presented on Table 1 (see paragraph (c) of the
standard for construction). As noted above, the performance option, in
paragraph (d)(2) of the standard for general industry and maritime
(paragraph (d)(2)(ii) of the standard for construction), also provides
flexibility to characterize employee exposures in a manner that
accounts for variability, in that it allows exposures to be assessed
using any combination of air monitoring data and objective data. But
OSHA does not consider that it is appropriate to allow exposure
assessment to include only an employee's "customary activity,"
because such an approach would ignore activities that may involve
higher exposures to respirable crystalline silica, and the higher
levels of risk associated with those exposures.
Under the scheduled monitoring option, requirements for periodic
monitoring depend on the results of initial monitoring and, thereafter,
any required subsequent monitoring. Paragraphs (d)(3)(ii)-(iv) of the
standard for general industry and maritime (paragraphs (d)(2)(iii)(B)-
(D) of the standard for construction) describe the employers' duties
depending on the initial (and, after that, the most recent) monitoring
results. If the initial monitoring indicates that employee exposures
are below the action level, no further monitoring is required. If the
most recent exposure monitoring reveals employee exposures to be at or
above the action level but at or below the PEL, the employer must
repeat monitoring within six months of the most recent monitoring. If
the most recent exposure monitoring reveals employee exposures to be
above the PEL, the employer must repeat monitoring within three months
of the most recent monitoring.
Paragraph (d)(3)(v) of the standard for general industry and
maritime (paragraph (d)(2)(iii)(E) of the standard for construction)
provides that if the most recent (non-initial) exposure monitoring
indicates that employee exposures are below the action level, and those
results are confirmed within six months of the most recent monitoring
by a second measurement taken consecutively at least seven days
afterwards, the employer may discontinue monitoring for those employees
whose exposures are represented by such monitoring. As discussed below,
reassessment is always required whenever a change in the workplace may
be reasonably expected to result in new or additional exposures at or
above the action level or the employer has any reason to believe that
new or additional exposures at or above the action level have occurred,
regardless of whether the employer has ceased monitoring because
exposures are below the action level under paragraph (d)(3)(ii) or
(d)(3)(v) of the standard for general industry and maritime (paragraph
(d)(2)(iii)(B) or (d)(2)(iii)(E) of the standard for construction)
(see paragraph (d)(4) of the standard for general industry and
maritime (paragraph (d)(2)(iv) of the standard for construction)).
OSHA made a number of minor changes to the requirements for
periodic monitoring under the scheduled monitoring option from the
proposal based on stakeholder comments. For example, paragraph
(d)(3)(i)(B) of the proposed regulatory text provided that "[w]here
initial or subsequent exposure monitoring reveals that employee
exposures are above the PEL, the employer shall repeat such monitoring
at least every three months." Subparagraph (C) then stated: "the
employer shall continue monitoring at the required frequency until at
least two consecutive measurements, taken at least 7 days apart, are
below the action level, at which time the employer may discontinue
monitoring..."
ARMA argued that these provisions were confusing and "might be
interpreted to require employers to continue monitoring quarterly, even
if two consecutive measurements are at or above the action level but at
or below the PEL"--a reading that ARMA believed conflicted with the
language of paragraph (d)(3)(i)(A), which provided that "[w]here
initial or subsequent exposure monitoring reveals that employee
exposures are at or above the action level but at or below the PEL, the
employer shall repeat such monitoring at least every six months"
(Document ID 2291, p. 23). ARMA added that it anticipated that OSHA
intended these provisions to impose the same periodic monitoring
requirements that appear routinely in other OSHA health standards. It
explained: "[u]nder that approach, even if periodic monitoring must be
conducted quarterly because the initial (or subsequent) assessment
shows exposures in excess of the PEL, the frequency can be reduced to
quarterly once two consecutive measurements more than seven days apart
fall below the PEL but above the action level" (Document ID 2291, p.
23).
OSHA agrees with ARMA's comment and has revised the periodic
monitoring provisions under the scheduled monitoring option to better
reflect OSHA's intent--as a general rule, the most recent exposure
monitoring sample determines how often an employer must monitor. OSHA
has also revised proposed paragraph (d)(3)(i)(C) to clarify the
circumstances under which employers who choose the scheduled monitoring
option may discontinue periodic monitoring.
Stakeholders also commented on how often employers should be
required to conduct exposure monitoring. Several commenters, including
the National Tile Contractors Association (NTCA), Dal-Tile, Grede
Holdings, ORCHSE Strategies (ORCHSE), Benton Foundry, PCI, TCNA, and
NISA, disagreed with the proposed frequency of monitoring and suggested
other frequencies (every 6 months, 12 months, 18 months, or as
determined by a competent person) (e.g., Document ID 2267, p. 7; 2147,
p. 3; 2298, p. 4; 2277, p. 3; 1972, p. 2; 2276, p. 6; 3584, Tr. 2744;
2363, p. 7; 2195, p. 36). IUOE and EEI, among others, suggested that
the three or six-month intervals for follow-up exposure assessment will
do nothing to protect employees on jobs of short duration (e.g.,
Document ID 2262, p. 11; 2357, p. 31). AFS suggested that a scheduled
monitoring option "that includes quarterly and semi-annual monitoring
does not gather useful information and is punitive in intent"
(Document ID 2379, Appendix 1, p. 55). EEI urged OSHA to revise the
scheduled monitoring option to either:
...(a) permit employers to conduct subsequent exposure
assessments without an arbitrary timetable of three or six months;
(b) permit employers to conduct subsequent exposure assessments in
longer, more reasonable intervals, such as annually or biennially;
or (c) create an exception to periodic exposure assessment
requirement when no changes in the workplace, control equipment, or
work practices have occurred (Document ID 2357, p. 21).
Francisco Trujillo, representing Miller and Long, proposed that
where exposures were between the action level and the PEL, exposure
assessment be required at least every six months unless employers
implement the same controls used to control exposures above the PEL
(Document ID 2345, p. 3). OSHA recognizes that exposures in the
workplace may fluctuate. Periodic monitoring, however, is intended to
provide the employer with reasonable assurance the employees are not
experiencing exposures that are higher than the PEL and require the use
of additional control measures. If the employer installs or upgrades
controls, periodic monitoring will demonstrate whether or not controls
are working properly or if additional controls are needed. In addition,
periodic monitoring reminds employees and employers of the continued
need to protect against the hazards associated with exposure to
respirable crystalline silica. Because of the fluctuation in exposures,
OSHA finds that when initial monitoring results equal or exceed the
action level, but are at or below the PEL, employers must continue to
monitor employees to ensure that exposures remain at or below the PEL.
Likewise, when initial monitoring results exceed the PEL, periodic
monitoring allows the employer to maintain an accurate profile of
employee exposures. Selection of appropriate respiratory protection
also depends on adequate knowledge of employee exposures.
In general, the more frequently periodic monitoring is performed,
the more accurate the employee exposure profile. Selecting an
appropriate interval between measurements is a matter of judgment. OSHA
concludes that the frequencies of six months for subsequent periodic
monitoring for exposures in between the action level and the PEL, and
three months for exposures above the PEL, provide intervals that are
both practical for employers and protective for employees. This finding
is supported by OSHA's experience with comparable monitoring intervals
in other standards, including those for chromium (VI) (1910.1026),
cadmium (29 CFR 1910.1027), methylenedianiline (29 CFR 1910.1050),
methylene chloride (29 CFR 1910.1052), and formaldehyde (29 CFR
1910.1048). Where employers find that a different frequency of
monitoring is sufficient to accurately characterize employee exposure
to respirable crystalline silica, they can use that air monitoring data
to meet their exposure assessment obligations under the performance
option.
Commenters, including National Electrical Carbon Products, Lapp
Insulators, the Indiana Manufacturers Association, ORCHSE, Murray
Energy Corporation, the Motor and Equipment Manufacturers Association,
IME, PCI, and NAM, urged OSHA to permit employers to cease monitoring
or monitor on a reduced schedule when it has been determined it is
infeasible to reduce exposures below the PEL using engineering and work
practice controls (e.g., Document ID 1785, p. 5; 2130, p. 2; 2151, p.
2; 2277, p. 3; 2102, p. 2; 2326, pp. 2-3; 2213, p. 4; 2276, p. 6; 2380,
Attachment 2, pp. 29-30). OSHA concludes, however, that periodic air
monitoring serves as a useful tool for evaluating the continuing
effectiveness of engineering and work practice controls, and can assist
employers in ensuring that they have met their obligation to use all
feasible controls to limit employee exposures to the PEL. Nevertheless,
an employer may decide that continued monitoring does not serve to
better characterize employee exposure. In these cases, as long as the
air monitoring data continue to accurately characterize employee
exposure, employers can use the existing data to meet their exposure
assessment obligations under the performance option without conducting
additional monitoring.
Reassessment of exposures. Paragraph (d)(4) of the standard for
general industry and maritime (paragraph (d)(2)(iv) of the standard for
construction) requires employers assessing exposures using either the
performance option or the scheduled monitoring option to reassess
employee exposures whenever there has been a change in the production,
process, control equipment, personnel, or work practices that may
reasonably be expected to result in new or additional exposures to
respirable crystalline silica at or above the action level, or when the
employer has any reason to believe that new or additional exposures at
or above the action level have occurred. For example, if an employer
has conducted monitoring while a task is performed using local exhaust
ventilation and the flow rate of the ventilation system is decreased,
additional monitoring would be necessary to assess employee exposures
under the modified conditions. In addition, there may be other
situations that can result in new or additional exposures to respirable
crystalline silica that are unique to an employee's work situation.
OSHA inserted the phrase "or when the employer has any reason to
believe that new or additional exposures at or above the action level
have occurred" in the rule to make clear that reassessment of
exposures is required whenever there is reason to believe that a change
in circumstances could result in new or additional exposures at or
above the action level. For instance, an employee may move from an
open, outdoor location to an enclosed or confined space. Even though
the task performed and the materials used may remain constant, the
changed environment could reasonably be expected to result in higher
exposures to respirable crystalline silica. In order to account for
these situations, the rule requires employers to reassess employee
exposures whenever a change may result in new or additional exposures
at or above the action level. OSHA considers this reevaluation
necessary to ensure that the exposure assessment accurately represents
existing exposure conditions. The exposure information gained from such
assessments will enable the employer to take appropriate action to
protect exposed employees, such as instituting additional engineering
controls or providing appropriate respiratory protection.
Some commenters, including Southern Company, EEI, API, and AFPM,
raised concerns about the requirement to conduct additional exposure
assessments (e.g., Document ID 2185, p. 7; 2357, pp. 21-22; 2301,
Attachment 1, p. 80; 2350, p. 10). Southern Company commented that
employers should not have to reassess exposures for every personnel
change, but rather only those changes that result in significant
changes in employee exposure (Document ID 2185, p. 7). EEI urged OSHA
to clarify what kind of change could trigger additional assessments
(Document ID 2357, pp. 21-22). API presented concerns that this
requirement could be interpreted to require additional assessments at
unworkably frequent intervals (Document ID 2301, Attachment 1, p. 80).
AFPM argued that the provision would require its members to conduct
continuous monitoring given the requirement to reassess every time
there is an environmental shift that would result in a new respirable
crystalline silica level (Document ID 2350, p. 10).
As described above, the requirement to reassess exposures only
applies where there are changes in the workplace that may reasonably be
expected to result in new or additional exposures at or above the
action level or when the employer has any reason to believe that new or
additional exposures at or above the action level have occurred. OSHA
does not intend for employers to conduct additional monitoring simply
because a change has occurred, so long as the change is not reasonably
expected to result in new or additional exposures to respirable
crystalline silica at or above the action level. Thus, in some of the
situations highlighted by the commenters, employers may not need to
reassess exposures. For example, where a personnel change does not have
an expected impact on the magnitude of employee exposure to respirable
crystalline silica, the employer would not have to reassess exposures.
When the environmental conditions on a construction site change in ways
that would not result in new or additional exposures at or above the
action level, such as a change from dry, dusty conditions to wet, rainy
conditions, the employer would not have to reassess exposures. Other
changes that would be reasonably expected to lower exposures to
respirable crystalline silica, rather than result in new or additional
exposures at or above the action level, such as moving from an indoor
to an outdoor location or using a product with a lower silica content
than that previously used in the same process, would not require the
employer to reassess exposures.
Methods of sample analysis. Paragraph (d)(5) of the standard for
general industry and maritime (paragraph (d)(2)(v) of the standard for
construction) requires employers to ensure that all samples taken to
satisfy the monitoring requirements are evaluated in accordance with
Appendix A, which contains specifications for the methods to be used
for analysis of respirable crystalline silica samples. The proposed
provision would also have required employers to ensure that all samples
taken to satisfy the air monitoring requirements in the exposure
assessment paragraph were evaluated using the procedures specified in
certain analytical methods. However, in the proposal, the analytical
methods were laid out in paragraph (d), rather than in a separate
Appendix.
Several commenters, including the Korte Company, AFS, TCNA, and NAM
expressed concerns that the proposal placed responsibility for
laboratory performance on the employers, who are not in a position to
ensure that laboratories are complying with specific analytical
requirements (e.g., Document ID 3230, p. 1; 2379, Appendix 1, p. 56;
2363, p. 7; 2380, Attachment 2, p. 31). OSHA does not expect employers
to oversee laboratory practices. An employer who engages an independent
laboratory to analyze respirable crystalline silica samples can rely on
a statement from that laboratory confirming that the specifications in
Appendix A were met.
One stakeholder, Southern Company, recommended that OSHA require
use of accredited laboratories and move all other laboratory
requirements to an appendix as a guide for laboratories that analyze
silica samples (Document ID 2185, p. 7). OSHA agrees with this
suggestion and has decided to retain the substance of the proposed
provisions addressing analysis of samples, but has moved these
provisions to a new appendix. The Agency concludes that segregating
these requirements in an appendix to each standard provides greater
clarity for both employers and the laboratories that analyze samples.
The specifications contained in Appendix A are discussed in the summary
and explanation of Appendix A in this section.
Commenters, including NSSGA, SCA, OSCO Industries, ORCHSE,
Associated General Contractors of Michigan (AGCM), and PCI expressed
concern about the availability of a sufficient number of qualified
laboratories capable of analyzing the increased number of air samples
expected given the standard's exposure assessment requirements
(e.g., Document ID 1992, p. 12; 2255, p. 1; 2265, Attachment 1, p. 2;
2277, p. 3; 2327, Attachment 1, pp. 4-6; 3589, Tr. 4357). There are
approximately 40 laboratories that are accredited by AIHA Laboratory
Accreditation Programs for the analysis of crystalline silica; these
laboratories are already capable of analyzing samples in accordance with
the laboratory requirements of this rule (Document ID 3586, Tr. 3284).
While the number of accredited laboratories for the analysis of
crystalline silica has declined over the last 10 or 20 years, William
Walsh, the Vice Chair of the Analytical Accreditation Board of the AIHA
Laboratory Accreditation Programs, testified that there is still
sufficient capacity available to analyze crystalline silica samples and,
in fact, "each lab's capacity has gone up" due to increased efficiency
in the sample analysis process (Document ID 3586, Tr. 3311).
OSHA expects that the additional demand for respirable crystalline
silica exposure monitoring and associated laboratory analysis with the
rule will be modest. Most construction employers are expected to
implement the specified exposure control measures in paragraph (c) of
the standard for construction, and will therefore not be required to
conduct exposure monitoring. The performance option for exposure
assessment provided in both the standard for general industry and
maritime at paragraph (d)(2) and the standard for construction at
paragraph (d)(2)(ii) also serves to lessen the future volume of
exposure monitoring and associated laboratory analysis for crystalline
silica. As discussed in the summary and explanation of Dates, the time
allowed for compliance with the standard for general industry and
maritime also serves to diminish concerns about laboratory capacity by
providing additional time for laboratory capacity to increase and
distributing demand for sample analysis over an extended period of
time.
Employee notification of assessment results. Paragraph (d)(6) of
the standard for general industry and maritime (paragraph (d)(2)(vi) of
the standard for construction) contains the requirements for employee
notification of assessment results and corrective actions. Under
paragraph (d)(6)(i) of the standard for general industry and maritime,
employers must notify each affected employee of the results of the
exposure assessment within 15 working days of completing the
assessment. Paragraph (d)(2)(vi)(A) of the standard for construction
requires this notification not more than five working days after the
exposure assessment has been completed. Notification is required under
both standards whenever an exposure assessment has been conducted,
regardless of whether or not employee exposure exceeds the action level
or PEL. Employers must either notify each individual employee in
writing or post the assessment results in an appropriate location
accessible to all affected employees. The term "affected" as used
here means all employees for which an exposure assessment has been
conducted, either individually or as part of a representative
monitoring strategy. It includes employees whose exposure was assessed
based on other employees who were sampled, and employees whose
exposures have been assessed on the basis of objective data. As
discussed with regard to the performance option, exposures can be
characterized as a range, e.g., below the action level or between the
action level and the PEL. The employer is notifying employees of
employee exposures, i.e., exposures that would occur if the employee
were not using a respirator. Any engineering and work practice controls
used would be reflected in the assessment results.
The provisions in the rule are identical to the proposed provisions
for both general industry and maritime and construction. A number of
commenters offered opinions on these provisions. For example, some
commenters, including Southern Company and EEI, objected to the
differences between the general industry and construction notification
requirements. These stakeholders argued that establishing different
reporting requirements for general industry and construction (i.e.,
requiring notification within 5 working days in construction and 15
working days in general industry), would create confusion and make
compliance difficult to achieve, especially for employers with blended
general industry/construction operations, such as electric utilities
(Document ID 2185, p. 4; 2357, p. 23). EEI urged OSHA to harmonize the
requirements or clarify which section applies to the situation with
blended general industry/construction operations (Document ID 2357, p.
23).
This issue is not unique to this rulemaking. In October 2002, OSHA
published the second phase of its Standard Improvement Project (SIPS),
which proposed to revise a number of health provisions in its standards
for general industry, shipyard employment, and construction. The
proposal was part of OSHA's effort to continue to remove and revise
provisions of its standards that are outdated, duplicative,
unnecessary, or inconsistent. One of the issues OSHA examined in Phase
II of SIPS was the "variety of different time limits between receipt
of employees' exposure monitoring results and notification of
employees" in OSHA's substance specific standards. After a thorough
review of the record, OSHA adopted a 15-day notification period for
general industry and a 5-day period in construction. The Agency
explained that its decision to set two different time frames was due,
in part, to the general differences in the industries, i.e., general
industry on average has "a more stable workforce," while
"[e]mployment at a particular location is often brief in construction
. . ." (70 FR 1112, 1126 (1/5/05)).
Some stakeholders from the construction industry, including CISC
and ASA, were concerned that they could not comply with the proposed
five-day notification requirement due to the often short duration of
tasks and employment in this sector. They argued that employers and
employees will frequently have moved to a different job before the
results are available, making it difficult or impossible to reach
affected employees and rendering the data irrelevant to the new project
with varying conditions and circumstances (e.g., Document ID 2319, p.
87; 2187, p. 5). These comments suggest that a 5-working-day
notification period would be too long for many employers in the
construction industry. Thus, OSHA concludes that it would make little
sense to lengthen the notification period in the construction standard
to correspond to the time period proposed in general industry and
maritime.
OSHA also concludes that shortening the proposed provision in
general industry to mirror that in construction would likewise make
little sense, especially insofar as most of OSHA's health standards for
general industry already utilize a 15-working-day period. As OSHA
explained in Phase II of SIPS, "a uniform time limit for notifying
employees in general industry has substantial benefits[,]" including
reduced employer paperwork burdens because of simpler, uniform
compliance programs and probable improvement in employee protection due
to improved compliance. Therefore, OSHA finds that the reasons
discussed in the SIPS rulemaking apply equally here. Consequently, OSHA
has chosen to adopt the proposed 5 and 15-working-day assessment
results notification periods in the rule.
OSHA has also considered commenters' concerns that the nature of
construction work will make it logistically difficult to notify employees
of assessment results because they may have moved on to different
jobsites or employers. Employers have options available for notifying
employees in such circumstances; for example, notifications could be made
individually in writing by including the assessment results in the
employees' final paycheck.
OSHA considers notification of assessment results to be important,
even if the work conditions and circumstances have changed by the time
the assessment results are available. Notification is not simply for
purposes of identifying appropriate controls at the time the work is
performed. The assessment results are still relevant after the exposure
has occurred, to inform employees of their exposure, to provide context
for future work that may be performed under similar conditions and
circumstances, and to inform PLHCPs who provide medical surveillance
for the employee.
NAM urged OSHA to provide flexibility as to when an assessment is
deemed complete rather than obligating the employer to notify employees
within five days of receiving a laboratory result (Document ID 2380,
Attachment 2, p. 32). NAM argued that employers need time to perform
and get the results of comprehensive surveys, perform appropriate
quality assurance of those results, and meet with employees as
appropriate to discuss the results. OSHA recognizes the value of these
measures, but also considers the necessity of assessing exposures and
notifying employees in a timely manner so that appropriate protective
measures are taken. The Agency is convinced that the required
notification can be made within the required 15 or 5 day time period,
which are standard in OSHA health standards. Additional information
that is developed from the collection of data in comprehensive surveys,
any revisions to initial results as a result of quality assurance
activities, or meetings to discuss the assessment results can take
place at a later date.
Where the employer follows the performance option provided in
paragraph (d)(2) of the standard for general industry and maritime
(paragraph (d)(2)(ii) of the standard for construction), the 15 (or 5)
day period commences when the employer completes an assessment of
employee exposure levels (i.e., normally prior to the time the work
operation commences, and whenever exposures are re-evaluated). OSHA
expects that many construction employers will follow the performance
option, where they are not using the specified exposure control methods
approach. Therefore, OSHA expects that it will not be difficult to
reach affected employees as the assessment would take place prior to
the time the work operation begins and the assessment results could
then be posted in a location accessible to employees at the beginning
of the job. Where the employer follows the scheduled monitoring option
provided in paragraph (d)(3) of the standard for general industry and
maritime (paragraph (d)(2)(iii) of the standard for construction), the
15 (or 5) day period for notification commences when monitoring results
are received by the employer.
In addition, as discussed in the summary and explanation of Scope,
where tasks performed in a general industry setting may be essentially
indistinguishable from construction tasks listed on Table 1, OSHA
permits employers to comply with either all of the provisions of the
standard for general industry and maritime or all of the provisions of
the standard for construction. When choosing to follow the construction
standard, the employer must notify employees within five working days
after completing an exposure assessment.
The notification provisions in the rule, like those in the
proposal, require employers to notify "affected" employees. As noted
above, the term "affected" as used here means all employees for which
an exposure assessment has been conducted, either individually or as
part of a representative monitoring strategy. It includes employees
whose exposure was assessed based on other employees who were sampled,
and employees whose exposures have been assessed on the basis of
objective data. Several commenters, including Ameren and EEI, suggested
that notification should only be required where air monitoring has been
performed, should not be applicable to employers who choose the
performance option for meeting the exposure assessment requirement, and
should already be captured by training or a written safety program
(e.g., Document ID 2315, p. 3; 2357, p. 23). Newmont Mining Corporation
commented that notification for every exposure assessment would be
excessive and should only be required when the results change (e.g.,
exposures above the PEL drop below PEL) (Document ID 1963, p. 4).
OSHA disagrees. Notifying employees of their exposures provides
them with knowledge that can permit and encourage them to be more
proactive in working to control their own exposures through better and
safer work practices and more active participation in safety programs.
As OSHA noted with respect to its Hazard Communication Standard:
"Employees provided with information and training on chemical hazards
are able to fully participate in the protective measures instituted in
their workplaces" (77 FR 17574, 17579 (3/26/12)). Exposures to
respirable crystalline silica below the PEL may still be hazardous, and
making employees aware of such exposures may encourage them to take
whatever steps they can, as individuals, to reduce their exposures as
much as possible. The results of exposure assessment are not
specifically required to be communicated to employees under the hazard
communication and employee information and training requirements in
paragraph (j) of the standard for general industry and maritime
(paragraph (i) of the standard for construction) nor as a part of the
written exposure control plan required in paragraph (f)(2) of the
standard for general industry and maritime (paragraph (g) of the
standard for construction). Exposure assessments are likely to be
conducted more frequently than training and, given the differences in
timing, OSHA concludes that it would not make sense to incorporate them
into a written exposure control plan. Thus, it is important to separate
the notification of exposure assessment results from other information
and training employees are required to receive under the rule.
NAM offered its opinion on what information the notification should
provide to employees and urged OSHA to provide flexibility in this
area:
Many employers require that air sampling results be accompanied
by statements concerning the relationship of the results to existing
standards, practices and procedures required as a result of the
exposure levels, and a discussion of any steps the employer is
taking in addition to further control exposures. OSHA acknowledges
that employees benefit from having information about the exposures
and potential control measures, including the use of PPE, to reduce
their risk. OSHA should recognize that an assessment may include
more than simple analytical results from a laboratory. Therefore,
OSHA should propose language to make clear that the employers have
this flexibility in communicating the results to employees (Document
ID 2380, Attachment 2, p. 32).
The notification requirement specifies what information must be
included; however, this does not limit employers from including the
types of information described by NAM in the written notification to
employees.
The standard also requires employers to either notify each affected
employee in writing or post the assessment results in an appropriate
location accessible to all affected employees. CPR urged OSHA to
strengthen the notification requirements by requiring: Personal
notification to workers in writing; notification in a language the
employee can understand; and inclusion of information about the silica
standard, silica-related disease from an individual or community
perspective, and available health care benefits (Document ID 2351, p.
12). The Agency has determined that the notification requirements and
the training requirements in the rule adequately address these
suggestions. As discussed, the rule requires employers to notify
employees, either in writing or by posting in an appropriate location.
The training requirements in paragraph (j)(3) of the standard for
general industry and maritime (paragraph (i)(2) of the standard for
construction) require the employer to ensure that each covered employee
can demonstrate knowledge and understanding of the silica standard,
tasks that could result in exposure to respirable crystalline silica,
the health hazards associated with exposure, specific procedures the
employer has implemented to protect employees from exposure, and the
medical surveillance provided under the rule. OSHA intends that these
requirements will ensure that employees comprehend their exposure to
respirable crystalline silica, the potential adverse effects of that
exposure, and protective measures that are available. This would
include employee understanding of any corrective action the employer is
taking to reduce exposures below the PEL that is described in the
written notification. The notification requirement, however, does not
require that employers provide notification in a language that the
employee can understand; as with other information provided to
employees (e.g., labels and safety data sheets), training ensures that
the information is understood.
In addition, paragraph (d)(6)(ii) of the standard for general
industry and maritime (paragraph (d)(2)(vi)(B) of the standard for
construction) requires that whenever the PEL has been exceeded, the
written notification must contain a description of the corrective
action(s) being taken by the employer to reduce employee exposures to
or below the PEL. Several commenters raised issues with the requirement
to notify employees about corrective actions being taken where
exposures are above the PEL. ASA and CISC suggested that in the
construction environment, five days is not sufficient time to determine
what caused the exposure, to research alternative solutions to limit
future exposure, and to decide on the appropriate corrective action
(Document ID 2187, p. 5; 2319, p. 87; 3442, pp. 3-4).
Similarly, in the general industry context, Newmont Mining
Corporation argued that "[d]etermination of controls to reduce
exposures when exposure assessments exceed the PEL may take more than
15 days" and suggested that OSHA revise the proposed language to allow
employers 60 to 90 days to develop a corrective action plan and explain
it to employees (Document ID 1963, p. 4). NAM also noted that the
requirement to notify employees of the corrective actions being taken
to reduce employee exposures below the PEL does not make sense for
situations where it is infeasible to bring the exposure level down to
the PEL (Document ID 2380, Attachment 2, p. 32).
OSHA disagrees. In OSHA's view, the requirement to inform employees
of the corrective actions the employer is taking to reduce the exposure
level to or below the PEL is necessary to assure employees that the
employer is making efforts to furnish them with a safe and healthful
work environment, and is required under section 8(c)(3) of the OSH Act
(29 U.S.C. 657(c)(3)). OSHA understands that it may take more than 15
days to determine what engineering controls may be appropriate in a
particular situation. However, the corrective action described in the
written notification is not limited to engineering controls; when the
exposure assessment indicates that exposures exceed the PEL, and the
employer needs more than 15 days (or, in the case of the standard for
construction, 5 days) to identify the engineering controls that will be
necessary to limit exposures to the PEL, the employer is required to
provide exposed employees with appropriate respiratory protection. In
such a situation, respiratory protection is the corrective action that
would be described in the written notification. Similarly, respiratory
protection is the corrective action that would be described in the
written notification in situations where it is infeasible to limit
exposures to the PEL.
CEG and Upstate Medical University suggested that exposure
assessment results should not only be reported to employees, but also
should be reported to OSHA (Document ID 3586, Tr. 3321; 2244, p. 4).
OSHA has not included such a requirement in the rule as such
information would not be of practical use to the Agency. OSHA does not
possess the resources to review and consider all of the material that
will be generated by employers assessing employee exposures under the
rule. OSHA would not have sufficient context to consider that material
even if sufficient resources were available, given that only limited
information is included in such assessments. Where such information
would be of practical value to OSHA, such as when compliance staff
conduct workplace inspections, the Agency is able to review exposure
records in accordance with the standard addressing access to exposure
and medical records (29 CFR 1910.1020).
Observation of monitoring. Paragraph (d)(7) of the standard for
general industry and maritime (paragraph (d)(2)(vii) of the standard
for construction) requires the employer to provide affected employees
or their designated representatives an opportunity to observe any air
monitoring of employee exposure to respirable crystalline silica,
whether the employer uses the performance option or the scheduled
monitoring option. When observation of monitoring requires entry into
an area where the use of protective clothing or equipment is required
for any workplace hazard, the employer must provide the observer with
that protective clothing or equipment at no cost, and assure that the
observer uses such clothing or equipment.
The requirement for employers to provide employees or their
representatives the opportunity to observe monitoring is consistent
with the OSH Act. Section 8(c)(3) of the OSH Act mandates that
regulations developed under section 6 of the Act provide employees or
their representatives with the opportunity to observe monitoring or
measurements (29 U.S.C. 657(c)(3)). Also, section 6(b)(7) of the OSH
Act states that, where appropriate, OSHA standards are to prescribe
suitable protective equipment to be used in dealing with hazards (29
U.S.C. 655(b)(7)). The provision for observation of monitoring and
protection of the observers is also consistent with OSHA's other
substance-specific health standards such as those for cadmium (29 CFR
1910.1027) and methylene chloride (29 CFR 1910.1052).
In his testimony, Shawn Ragle of UAW Local 974, in responding to
Rebecca Reindel of AFL-CIO, described the importance of allowing the
observation of monitoring:
MS. REINDEL:...Mr. Ragle, you mentioned that there's limited
air monitoring in your plant. I was wondering, as a safety rep, have
you ever been allowed to observe the air monitoring that has been
done?
MR. RAGLE:...Actually, I've requested to be an observer for
air monitoring, and the company has denied me that access. They've
chosen to go with the employee that they put the monitor on.
Really, if you're doing your job, how are you going to monitor
your monitor to make sure everything is going correctly? I really
think that we need to have a little more voice, or at least some
validation that the monitoring is being done correctly.
We shouldn't put that on the employee wearing the monitor
(Document ID 3582, Tr. 1895-1896).
Similarly, James Schultz, a former foundry employee from the
Wisconsin Coalition for Occupational Safety and Health, testified that
he was,
...heartened to see that the proposal mandates that the
employer provide protective clothing and equipment at no cost to the
observers that are doing the observation and the monitoring of the
hazards in the workplace (Document ID 3586, Tr. 3200).
Opposing this requirement, CISC and Hunt Construction Group argued that
the provision was unnecessary given that the observer will not be close
enough to the silica-generated tasks to pose a risk (Document ID 2319,
pp. 87-88; 3442, pp. 4-5). ASA expressed concern about the unnecessary
cost of providing protective clothing to an observer (Document ID 2187,
p. 5). Similarly, AGCM argued that requiring the employer to provide
personal protective equipment and training is an unnecessary additional
cost and requirement (Document ID 2265, Attachment 1, p. 2).
Commenters, including the Korte Company and ASA, were also
concerned that this requirement burdened the employer with providing
the employee's representative with protective clothing or equipment
whether or not the representative is trained or qualified to be wearing
the required PPE (e.g., medical evaluation or fit test to wear a
respirator) (e.g., Document ID 3230, p. 1; 2187, p. 5). Commenters,
including NTCA and TCNA, asked OSHA to state that it is the
responsibility of the employer of the employee's representative to
provide the necessary respirator and ensure that the employee's
representative is medically cleared, appropriately trained, and fit
tested if a respirator is needed to observe the monitoring (e.g.,
Document ID 2267, p. 5; 2363, p. 5). NAHB argued that this provision is
"neither reasonable nor prudent" as it "needlessly impos[es]
liability on covered employers by requiring them to assume
responsibility for an `observer' who may come onto a jobsite where
silica may be present" (Document ID 2296, p. 25). AGCM argued that the
observer's employer is already required to provide the necessary
personal protective equipment and training, not the employer being
observed (Document ID 2265, Attachment 1, p. 2).
Section 8(c)(3) of the OSH Act states that occupational safety and
health standards which require employers to monitor or measure employee
exposure to potentially toxic materials "shall provide employees or
their representatives with an opportunity to observe such monitoring or
measuring." Provisions requiring employers to provide affected
employees or their designated representatives an opportunity to observe
any monitoring, as well as protective clothing or equipment where it is
required, appear in 15 substance-specific health standards. Two
substance-specific health standards (1,3-butadiene and methylene
chloride) require employers to "provide the observer with protective
clothing or equipment at no cost" (Sec. 1910.1051(d)(8)(ii) and Sec.
1910.1052(d)(6)(ii)), as does this rule for respirable crystalline
silica.
OSHA's policy conclusion is that employers conducting monitoring
must bear the cost of complying with the standard's provisions for
observer protections, even if the observer is not an employee of the
employer. First, the Agency concludes that it would be an extremely
rare occurrence for an observer to be unfamiliar with the use of the
types of protective clothing or equipment that would be necessary for
observation. In OSHA's experience, observers, whether they are another
employee or a designated representative, typically have knowledge and
experience such that they would already be medically cleared to use
appropriate respiratory protection and may even have access to an
appropriate respirator. Thus, OSHA expects the employer conducting the
monitoring in these situations to communicate with the observer about
what hazards are present in the workplace and what protective clothing
and equipment, including medical clearances, are needed to observe the
monitoring at their establishment. OSHA also expects the employer to
assess whether the observer already has the necessary equipment and
training to observe the monitoring. In situations where the necessary
equipment is not already available to the observer, OSHA considers it
to be the employer's responsibility to provide the protective clothing
and equipment, as well as other training, clearance, or evaluation
needed to ensure that the observer uses such clothing and equipment.
Second, OSHA recognizes that, in some situations, observers may not
need to enter an area requiring the use of protective clothing or
equipment in order to effectively observe monitoring. In those cases,
no protective clothing or equipment is needed by the observer and OSHA
would not expect or require the employer to provide such observer with
any protective clothing or equipment. Some possible options to avoid
exposing the observer to hazards that require the use of protective
clothing or equipment include conducting the set-up for the monitoring
outside of hazardous areas and ensuring that the observer can view the
monitoring while remaining outside of the hazardous areas or, where
exposure to respirable crystalline silica is the only hazard requiring
the use of protective clothing or equipment, conducting the set-up for
monitoring before the exposure-generating task is performed and
ensuring that the observer can view the monitoring while remaining
outside of the area of exposure.
Third, OSHA finds that employers conducting monitoring are in the
best position to understand the hazards present at the workplace,
including the protective clothing and equipment needed to protect
against those hazards and the training, clearance, or evaluation needed
to ensure that the observer is protected from those hazards. OSHA
concludes that employers' familiarity with the worksite, the work, and
their employees puts them in the best position to conduct exposure
monitoring in a timely, effective, and safe manner. Therefore, OSHA
appropriately requires the employer to bear the responsibility for
ensuring that any observer in his or her establishment is adequately
protected.
OSHA thus decided that employers conducting monitoring are
responsible for the full costs of protecting observers, by providing
the necessary equipment as well as any training, clearance, or
evaluation needed to properly use the equipment, regardless of whether
the observers are employees or designated representatives.
The requirements for exposure assessment in the rule are consistent
with ASTM E 1132-06, Standard Practice for Health Requirements Relating
to Occupational Exposure to Respirable Crystalline Silica, and ASTM E
2625-09, Standard Practice for Controlling Occupational Exposure to
Respirable Crystalline Silica for Construction and Demolition Activities,
the national consensus standards for controlling occupational exposure to
respirable crystalline silica in general industry and in construction,
respectively. Each of these voluntary standards has explicit
requirements for exposure assessment. For general industry, the ASTM
standard includes requirements for: Initial sampling; periodic
sampling; sampling and analytical methods; observation of monitoring;
and notification of assessment results. Similarly, for construction,
the ASTM standard includes requirements for: Initial sampling;
reassessment of exposures when changes have the potential to result in
new or additional exposures; sampling and analytical methods; and
notification of assessment results. It also notes the challenges of
monitoring in a dynamic construction environment and suggests that
employers may also use a combination of historical data, objective
data, or site-specific employee exposure monitoring to assess
exposures.
While OSHA's standard for respirable crystalline silica includes
these elements, it includes a performance-oriented approach to exposure
assessment that best reflects the realities of assessing exposures to
respirable crystalline silica. The standard also includes a scheduled
approach, which provides specific requirements for initial and periodic
monitoring, for industries and tasks that can utilize such an option.
Including both of these options maximizes the flexibility for employers
to meet their exposure assessment obligations, and in doing so, better
effectuates the purposes of the OSH Act and protects employees from
exposures to respirable crystalline silica. OSHA thus concludes that
the exposure assessment provision in the rule achieves the important
purpose of assessing employee exposure, while providing sufficient
flexibility for employers.
Regulated Areas
Paragraph (e) of the standard for general industry and maritime
sets forth the requirements for regulated areas. In paragraph (e)(1),
employers are required to establish regulated areas wherever an
employee's exposure to airborne concentrations of respirable
crystalline silica is, or can reasonably be expected to be, in excess
of the permissible exposure limit (PEL). In paragraph (e)(2) and
(e)(3), employers must demarcate regulated areas, and limit access to
regulated areas to persons authorized by the employer and required by
work duties to be present in the regulated area, persons observing
exposure monitoring, or any person authorized by the Occupational
Safety and Health (OSH) Act or regulations issued under it to be in a
regulated area. Finally, paragraph (e)(4) requires employers to provide
each employee and the employee's designated representative entering a
regulated area with an appropriate respirator and require its use while
in the regulated area.
The requirements for regulated areas serve several important
purposes. First, requiring employers to establish and demarcate
regulated areas ensures that the employer makes employees aware of the
presence of respirable crystalline silica at levels above the PEL.
Second, the demarcation of regulated areas must include warning signs
describing the dangers of respirable crystalline silica exposure in
accordance with paragraph (j) of the standard for general industry and
maritime, which provides notice to employees entering or nearing
regulated areas of the posted dangers. Third, limiting access to
regulated areas restricts the number of people potentially exposed to
respirable crystalline silica at levels above the PEL and ensures that
those who must be exposed are properly protected, thereby limiting the
serious health effects associated with such exposure.
The proposed requirements for regulated areas were included in
paragraph (e) of both the proposed standard for general industry and
maritime and the proposed standard for construction. Under proposed
paragraph (e)(1), employers would have been required to establish and
implement either a regulated area or an access control plan wherever an
employee's exposure to airborne concentrations of respirable
crystalline silica is, or reasonably could be expected to be, in excess
of the PEL. The substantive requirements for the regulated area option
were contained in proposed paragraph (e)(2) and those for access
control plans were in proposed paragraph (e)(3). In the standard for
general industry and maritime, OSHA has retained the requirement for
employers to establish and implement regulated areas. However, the
Agency has decided against requiring regulated areas in the standard
for construction; an alternate provision has been included as a
component of the written exposure control plan requirements for
construction.
OSHA has concluded that requirements for regulated areas are
appropriate for general industry and maritime, but not for
construction, because the worksites and conditions and other factors,
such as environmental variability normally present in the construction
industry, differ substantially from those typically found in general
industry. Commenters, including the National Council of La Raza, the
National Institute for Occupational Safety and Health (NIOSH), the
Associated General Contractors of America, the Small Business
Administration's Office of Advocacy, and the Building and Construction
Trades Department, AFL-CIO (BCTD), noted some of the differences
between construction and general industry worksites, including that
general industry establishments are typically more stable, are likely
to be indoors, and are usually at a fixed location (e.g., Document ID
2166, p. 3; 2177, Attachment B, p. 7; 2323, p. 1; 2349, pp. 5-6; 2371,
Attachment 1, p. 42). OSHA finds that these factors make establishing
regulated areas generally suitable in general industry and maritime
workplace settings, and their absence in construction settings makes a
regulated areas requirement generally unworkable.
Some commenters, particularly those representing unions in general
industry, supported the idea of regulated areas wherever an employee's
exposure to airborne concentrations of respirable crystalline silica
is, or reasonably could be expected to be, in excess of the PEL (e.g.,
Document ID 2282, Attachment 3, p. 2; 2315, p. 3; 2318, p. 10). For
example, the International Brotherhood of Teamsters stated that
ancillary provisions, such as regulated areas, would reduce the risk
beyond the reduction that will be achieved by a new PEL alone (Document
ID 2318, p. 10). Similarly, the United Automobile, Aerospace and
Agricultural Implement Workers of America (UAW) expressed concerns that
workers would not receive adequate protection if OSHA did not adopt a
requirement for regulated areas in general industry (Document ID 2282,
Attachment 3, pp. 2, 16). The United Steelworkers said that OSHA's
proposed general industry and maritime standard should be revised to
require employers to establish regulated areas where processes exceed
the proposed PEL for respirable crystalline silica (Document ID 2336,
p. 5).
Other general industry stakeholders argued that establishing
regulated areas would be unworkable and infeasible, particularly in
foundries (Document ID 1992, p. 10; 2149, p. 2; 2248, p. 7; 2349, p. 5;
2379, Attachment B, pp. 30-31; 3584, Tr. 2669) and in certain other
sectors of general industry (Document ID 1785, p. 6; 2337, p. 1; 2348,
p. 36; 2380, Attachment 2, pp. 32-33). Some of these commenters focused
on how an employer would be able to determine which parts of the facility
should be designated as regulated areas. For example, the American
Foundry Society (AFS) indicated that defining a regulated area would be
difficult because the standard is based on employee 8-hour time weighted
average (TWA) exposures, not on specific geographic areas (Document ID
2379, Attachment B, pp. 30-31). AFS explained that "[i]f the standard
allowed real time monitoring and exposure mapping as an alternative to
8 hr. TWA sampling, one might be able to construct a basis for defining
regulated areas" (Document ID 2379, Attachment B, pp. 30-31). AFS offered
a specific example to illustrate its concern:
...a maintenance worker who has an exposure above the PEL may
work in many areas of the plant including the office. It does not
make sense to turn the office into a regulated area because the
maintenance worker spent some time there on the day of sampling
(Document ID 2379, Attachment B, pp. 30-31; 3487, p. 21).
The scenario described by AFS is not consistent with the definition
of the term "regulated area" that OSHA proposed nor that of the final
standard. Paragraph (b) of the proposed and final standard for general
industry and maritime defines regulated area to mean "an area,
demarcated by the employer where an employee's exposure to airborne
concentrations of respirable crystalline silica exceeds, or can
reasonably be expected to exceed, the PEL." This definition makes
clear that a regulated area is defined by employee exposure, not by
which employee(s) might be in it. In other words, just because a
particular employee's exposure assessment results indicate that the
employee's exposure is above the PEL, that does not mean that employee
exposure in every area that the employee visited on the day he or she
was sampled exceeds, or can reasonably be expected to exceed, the PEL.
In the scenario posed by AFS, the employer would be required by
paragraph (d)(1) of the standard for general industry and maritime to
assess the exposure of each employee who is, or may reasonably be
expected to be, exposed to respirable crystalline silica at or above
the action level in accordance with either the performance option
(i.e., use of any combination of air monitoring data or objective data
sufficient to accurately characterize employee exposure) or the
scheduled monitoring option (i.e., one or more personal breathing zone
air samples). As explained in the summary and explanation of Exposure
Assessment, if real time monitoring and exposure mapping, the methods
suggested by AFS, allow an employer to accurately characterize employee
exposures, then the employer would be allowed to use such methods to
assess employee exposures under the performance option. This exposure
information would also be helpful in determining where higher exposures
may be occurring.
If an employee's exposure is above the PEL, paragraph (f)(1) of the
standard for general industry and maritime would require the employer
to use engineering and work practices to reduce and maintain employee
exposure to respirable crystalline silica. In order to control
exposures, the employer would need to determine where the exposures are
generated. As explained by Dr. Franklin Mirer, Professor of
Environmental and Occupational Health at CUNY School of Public Health,
during his testimony on behalf of the American Federation of Labor and
Congress of Industrial Organizations (AFL-CIO), setting up a regulated
area in a foundry is not complicated--employers must simply determine
the extent of the dust cloud, possibly using measures like short-term
or real-time monitoring or exposure mapping (Document ID 3578, Tr.
1003-1005).
Dr. William Bunn, who testified on behalf of the U.S. Chamber of
Commerce, also offered testimony that suggests that some foundries are
capable of establishing regulated areas. In response to questioning
during the public hearings, Dr. Bunn spoke about the efficacy of OSHA
inspections for aiding foundries in reducing silica exposures. Based on
his experience as an employee of Navistar International and as a
consultant to multiple automotive engine foundries, Dr. Bunn stated
that there was no feasible way to attain compliance with the proposed
PEL without using respiratory protection. However, Dr. Bunn emphasized
that this occurred at certain specific, restricted areas that could be
easily observed (Document ID 3576, Tr. 473). OSHA concludes from this
testimony that where exposures above the PEL occur in foundries, they
typically occur in limited areas that can be readily identified, and
the provisions for establishment, demarcation, access restriction, and
provision of respirators can be applied.
Edison Electric Institute stated that, given requirements for
establishing regulated areas in other OSHA substance-specific
standards, OSHA should consider creating uniform provisions for
regulated areas, to minimize the complications that arise when multiple
regulated substances begin to "stack" in one regulated area (Document
ID 2357, pp. 32-33). OSHA recognizes that standards for asbestos,
benzene, cadmium, chromium (VI), 13 carcinogens, methylenedianiline,
and others also contain requirements for regulated areas; however,
these requirements are not in conflict with one another. Where an
employer establishes a regulated area for multiple substances, the
employer can and must comply with the requirements for each applicable
standard for that regulated area. Persons allowed access to the
regulated area include employees who are performing tasks required by
work duties subject to the regulated area requirements of another
standard even if that exposure (e.g., to asbestos) is unrelated to
tasks that generate silica exposures. But this would be a very uncommon
scenario--for the most part, multiple standards apply when exposures to
multiple hazardous substances result from a single source, e.g., fly
ash in electric utilities contains lead, chromium (VI), silica, etc.
Other general industry commenters felt that regulated areas were
unnecessary. For example, Morgan Advanced Materials asserted that
regulated areas or access control programs may be appropriate for areas
where the conditions may cause an immediate health effect or injury,
but are not appropriate for chronic hazards like respirable crystalline
silica, especially since "...nearly everyone is exposed to some
level of crystalline silica on a daily basis" (Document ID 2337, pp.
1-2). OSHA rejects Morgan Advanced Materials' position because, unlike
"everyone" who is exposed to background levels, employees who are
exposed to respirable crystalline silica at levels exceeding the
revised PEL are at significant risk of developing silica-related
disease; this risk cannot be ignored simply because silica exposure
does not cause an immediate death or injury. Regulated areas are an
effective means of limiting the risk associated with respirable
crystalline silica exposure, and are therefore appropriate for
protecting employees.
Paragraph (e)(2) of the standard for general industry and maritime
includes requirements for demarcation of regulated areas. The proposed
provision on demarcation would have required employers to demarcate
regulated areas from the rest of the workplace in any manner that
adequately establishes and alerts employees to the boundary of the
regulated area. The proposed provision also stipulated that the
demarcation minimize the number of employees exposed to respirable
crystalline silica within regulated areas. In the proposed rule,
OSHA did not specify how employers were to demarcate regulated areas.
In the standard for general industry and maritime, because the Agency
has adopted requirements for posting signs, OSHA has removed the
language "in any manner that adequately establishes and alerts
employees to the boundary of the regulated area."
A number of stakeholders submitted comments on the proposed
provision. For example, the AFL-CIO argued that other health standards
that regulate carcinogens require warning signs at regulated areas, and
that OSHA provided no justification for departing from this precedent
(Document ID 4204, pp. 56-57). Many other stakeholders were supportive
of warning sign requirements and submitted specific language for
inclusion on signs that demarcate regulated areas (Document ID 2163,
Attachment 1, p. 15; 2178, pp. 2-3; 2282, Attachment 3, p. 25; 2310,
Attachment 2, p. 1; 2371, Attachment 1, p. 36; 2373, p. 2; 3582, Tr.
1920-1921; 4030, Attachment 1, p. 3; 4030, Exhibit D; 4073, Exhibit
15b, p. 18). For example, BCTD and the International Union of Operating
Engineers encouraged OSHA to review the discussion of regulated areas
in Ontario's Guideline on Silica Construction Projects with respect to
ropes and barriers (Document ID 4073, Attachment 15b; 4234, Attachment
2, p. 57). Ontario's Guideline states that:
Ropes or barriers do not prevent the release of contaminated
dust or other contaminants into the environment. However, they can
be used to restrict access of workers who are not adequately
protected with proper PPE, and also prevent the entry of workers not
directly involved in the operation. Ropes or barriers should be
placed at a distance far enough from the operation that allows the
silica-containing dust to settle. If this is not achievable, warning
signs should be posted at the distance where the silica-containing
dust settles to warn that access is restricted to persons wearing
PPE (Document ID 4073, Ex.15 b).
Others identified particular topics that should be covered by the
signs without proposing language. For example, Upstate Medical
University argued that all regulated areas should have warning signs
addressing the hazards of silica dust (Document ID 2244, p. 4).
As is further explained in the summary and explanation of
Communication of Respirable Crystalline Silica Hazards to Employees,
OSHA agrees with these commenters with respect to the requirement for
warning signs at entrances to regulated areas. Employees must recognize
when they are entering a regulated area, and understand the hazards
associated with the area, as well as the need for respiratory
protection. Signs are an effective means of accomplishing these
objectives. Therefore, OSHA has included a requirement that employers
are obligated to post all entrances to regulated areas with signs that
bear the following legend:
DANGER
RESPIRABLE CRYSTALLINE SILICA
MAY CAUSE CANCER
CAUSES DAMAGE TO LUNGS
WEAR RESPIRATORY PROTECTION IN THIS AREA
AUTHORIZED PERSONNEL ONLY
The rulemaking record also indicates that use of signs is also
consistent with general industry practices. For example, a plan
developed by the National Service, Transmission, Exploration, and
Production Safety Network (STEPS Network) for the hydraulic fracturing
industry recommends signs to warn of potential silica exposure and the
requirement for respirator use near exposure zones (Document ID 4024,
Attachment 1, p. 1; Attachment 2, p. 1).
The Unified Abrasives Manufacturers Association argued that
demarcation of regulated areas would require the construction of a
complete physical separation between the regulated area and adjacent
areas (Document ID 3398, p. 1). Aside from the requirement of specific
language for posting signs, however, the standard does not specify the
method of demarcation; cones, stanchions, tape, barricades, lines, or
textured flooring may each be effective means of demarcating the
boundaries of regulated areas. As in the proposed rule, therefore, so
long as the demarcation is accomplished in a manner that minimizes the
number of employees exposed to respirable crystalline silica within the
regulated area, the employer will be in compliance, without necessarily
installing a complete physical separation in the workplace.
Factors that OSHA considers to be appropriate considerations for
employers when they are determining how to demarcate regulated areas
include the configuration of the area, whether the regulated area is
permanent, the airborne respirable crystalline silica concentration,
the number of employees in adjacent areas, and the period of time the
area is expected to have exposure levels above the PEL. Permitting
employers to choose how best to demarcate regulated areas is consistent
with OSHA's use of performance-based approaches where the Agency has
determined that employers, based on their knowledge of the specific
conditions of their workplaces, are in the best position to make such
determinations.
The flexibility of this provision aims to address some of the
concerns identified by commenters. For example, National Electrical
Carbon Products commented that:
The concept seems to be that there are hazardous areas where
access must be restricted. In reality: there are hazardous
exposures, where exposures must be controlled...Exposure to
airborne crystalline silica, on the other hand, is most typically
associated with intermittent activities that are not necessarily
associated with a location (Document ID 1785, p. 6).
OSHA understands that for certain work processes, exposure may indeed
be associated with an intermittent activity rather than a fixed
location. In such cases where silica-generating activities are
conducted only sporadically, employers may elect to demarcate a
regulated area by means of movable stanchions, portable cones,
barricade tape, and the like, as long as the required warning sign with
prescribed hazard language is posted at all entrances to each regulated
area. Similarly, in a case where work activity migrates to different
areas of a worksite, these movable forms of demarcation could likewise
be repositioned to indicate the regulated area as work progresses. This
flexibility should also help employers with open-design facilities
establish regulated areas when needed.
A few commenters expressed concern that provisions for demarcation
of regulated areas may interfere with heat stress programs currently in
place as well as the current sanitation standard in general industry
(29 CFR 1910.141) (Document ID 2379, Appendix 1, p. 59; 3577, Tr. 751-
752; 3586, Tr. 3370). The AFS stated that:
Foundries often have areas with high heat exposures and
encourage workers to drink water. The proposal [is] not clear on
hygiene rules for regulated areas. The final rule must not be
drafted in a way that could be interpreted to ban drinking water in
a regulated area (Document ID 2379, Appendix 1, p. 59).
OSHA's standards addressing sanitation in general industry and
maritime with respect to consumption of food and beverages are
unchanged by this rulemaking. The standards in paragraphs 29 CFR
1910.141(g)(2) and 1917.127(c) prohibit consumption of food or beverage
in any area exposed to a toxic material. OSHA appreciates the
importance of providing access to drinking water, particularly in hot
work environments, and recognizes that in many cases employees will
need access to drinking water in order to remain hydrated. However, as
explained in more detail below, paragraph (e)(4) of the standard for
general industry and maritime requires all employees within the
demarcated boundaries of a regulated area to wear a respirator
continually while in the area, and thereby the consumption of water
within boundaries of a regulated area is not feasible. An employee
will need to leave the regulated area temporarily to access water
and food, in accordance with OSHA's sanitation standards.
Paragraph (e)(3) of the standard for general industry and maritime
requires employers to limit access to regulated areas. As in the
proposed rule, employers are required to limit access to: (A) Persons
authorized by the employer and required by work duties to be present in
the regulated area; (B) any person entering such an area as designated
representatives of employees for the purpose of exercising the right to
observe exposure monitoring procedures under paragraph (d) of this
section; and (C) any person authorized by the OSH Act or regulations
issued under it to be in a regulated area.
The first group, persons the employer authorizes or requires to be
in a regulated area to perform work duties, includes employees and
other persons whose jobs involve operating machinery, equipment, and
processes located in regulated areas; performing maintenance and repair
tasks on machinery, equipment, and processes in those areas; conducting
inspections or quality control tasks; and supervising those who work in
regulated areas. Persons allowed access to the regulated area include
employees who are performing tasks required by work duties subject to
the regulated area requirements of another standard even if that
exposure is unrelated to tasks that generate silica exposures.
The second group is made up of persons entering a regulated area as
designated representatives of employees for the purpose of exercising
the right to observe exposure monitoring under paragraph (d) of the
standard for general industry and maritime. As explained in the summary
and explanation of Exposure Assessment, providing employees and their
representatives with the opportunity to observe monitoring is
consistent with the OSH Act and OSHA's other substance-specific health
standards, such as those for cadmium (29 CFR 1910.1027) and methylene
chloride (29 CFR 1910.1052).
The third group consists of persons authorized by law to be in a
regulated area. This category includes persons authorized to enter
regulated areas by the OSH Act, OSHA regulations, or any other
applicable law. OSHA compliance officers fall into this group.
Some commenters expressed concerns about restricting access to
regulated areas. For example, OSCO Industries argued that control of
ingress and egress from regulated areas would be very problematic
because of high traffic volumes, indicating, for example, that it may
be necessary to reroute pedestrian and fork truck traffic outside the
building in order to avoid the regulated area (Document ID 1992, p.
10). Similarly, a representative of the Non-Ferrous Founders' Society
(NFFS) testified that smaller foundries would experience difficulty in
establishing and restricting access to regulated areas (Document ID
3584, Tr. 2814).
Other commenters indicated that restricted areas were already in
place at their workplaces. For example, Kenny Jordan, Executive
Director of the Association of Energy Service Companies, testified that
restricted areas with limited access are already used in hydraulic
fracturing operations (Document ID 3589, Tr. 4066-4067). Mr. Jordan
went on to describe how the presence of these restricted areas is
communicated to other employees on the multiemployer worksite (Document
ID 3589, Tr. 4079-4080).
OSHA finds that requirements for establishing and limiting access
to regulated areas are reasonable and generally feasible for general
industry and maritime workplaces. With regard to the concerns expressed
by OSCO Industries about rerouting traffic to avoid regulated areas,
the intent of the standard is to restrict unnecessary pedestrian and
vehicle traffic in areas where exposures exceed the PEL; employees who
would otherwise be exposed when traversing the regulated area will thus
be better protected. Where work duties require these employees to enter
the regulated area, the standard provides for access, with appropriate
respiratory protection. OSHA also considers that the exposure
assessment performed in accordance with paragraph (d) of the standard
for general industry and maritime will provide a basis for establishing
the boundaries of the regulated area, and thus establishment of
regulated areas will not be as problematic as NFFS suggests.
Paragraph (e)(4) of the standard for general industry and maritime
requires employers to provide each employee and the employee's
designated representative entering a regulated area with an appropriate
respirator in accordance with paragraph (g) of the standard. The
provision also mandates that employers require each employee or
employee representative to use the respirator while in the regulated
area. The provision in the standard requiring use of respirators in
regulated areas is identical to the proposed provision. The boundary of
the regulated area indicates where respirators must be donned prior to
entering, and where respirators can be doffed, or removed, upon exiting
the regulated area. This provision was intended to establish a clear
and consistent requirement for respirator use for all employees who
enter a regulated area, regardless of the duration of their presence in
the regulated area.
OSHA received comments from stakeholders in both construction and
general industry, generally opposing this requirement (e.g., Document
ID 1785, p. 7; 2267, p. 5; 2291, p. 25; 2296, p. 26; 2319, p. 90; 2348,
p. 36; 2363, p. 5; 2380, Attachment 2, pp. 32-33; 3577, Tr. 752; 3586,
Tr. 3408-3417). For example, the National Association of Home Builders
(NAHB) stated that the proposed requirements were overly restrictive
because respiratory protection would be required even when risks are
low, such as when an employee was in a regulated area for a very short
period of time (Document ID 2296, p. 30). Several commenters
representing general industry entities also expressed similar concerns
with respect to increases in respirator usage (e.g., Document ID 1785,
p. 7; 2291, p. 25; 2337, p. 1; 2348, p. 36; 2380, Attachment 2, pp. 32-
33; 4229, p. 25). The Asphalt Roofing Manufacturers Association (ARMA)
indicated that the proposed requirement for respirator use would place
a significant and unnecessary burden on ARMA member companies (Document
ID 2291, p. 25). The National Association of Manufacturers (NAM)
recommended that OSHA should limit requirements for respirator use to
situations where entry into the regulated area will be of such
frequency and duration as to constitute a hazard (Document ID 2380,
Attachment 2, pp. 32-33). National Electrical Carbon Products also
expressed concerns about the requirements for respirators in regulated
areas, and encouraged the adoption of a time specification. They argued
that the proposed requirement was inconsistent with the concept of the
8-hour TWA PEL (Document ID 1785, p. 7).
After reviewing these comments, OSHA has decided to retain the
requirement for employers to provide and require the use of respirators
in regulated areas in the standard for general industry and maritime.
Although OSHA recognizes that some employees entering regulated areas
may not be exposed above the PEL (expressed as an 8-hour TWA), many
employees who are assigned to work in these areas may remain in these
locations for long enough periods of time so that they would be
needlessly overexposed to respirable crystalline silica if they did not
wear respirators. Furthermore, OSHA finds that allowing some employees
to work in regulated areas without respiratory protection, while
requiring it for others, would create confusion and compliance
difficulties in the workplace. To the extent that some employees in
regulated areas who may not be exposed on a particular day above the
PEL are nonetheless required to wear respirators, this time-limited use
of respirators should further reduce the significant risk that remains
at the PEL.
In the proposed rule, OSHA also included a provision related to
protective work clothing. Proposed paragraph (e)(2)(v)(A) would have
required employers to either provide protective clothing or provide
other means of removing excessive silica dust from contaminated
clothing. Under proposed paragraph (e)(2)(v)(B), employers would have
been required to ensure that clothing was removed or cleaned upon
exiting a regulated area when there was potential for employees'
clothing to become "grossly contaminated" by fine particles of
crystalline silica that could become airborne and inhaled. The purpose
was not to protect employees from dermal exposure to silica, but rather
to protect the employee from those situations wherein contamination of
clothing has the potential to contribute significantly to employee
inhalation of respirable crystalline silica.
The proposed provision for protective clothing was more limited
than similar provisions in other OSHA substance-specific standards. As
noted in the preamble of the Notice of Proposed Rulemaking OSHA limited
the proposed provision for protective clothing to regulated areas
because dermal exposure to crystalline silica is not associated with
adverse health effects. Nonetheless, OSHA solicited information from
stakeholders regarding protective clothing for respirable crystalline
silica, largely because a provision for protective clothing had been
recommended by the Agency's Advisory Committee on Construction Safety
and Health.
Several employees in silica-exposed industries described the extent
of contamination to their clothing by silica dust and how this dust
would even be brought home with them (Document ID 3571, Attachment 7,
p. 1; 3581, Tr. 1595, 1599-1600; 3582, Tr. 1840). OSHA heard testimony
from Dan Smith, Director of Training for the Bay Area Roofers and
Waterproofers Training Center in Livermore, California and member of
the National Curriculum Development Committee of the United Union of
Roofers, Waterproofers and Allied Workers, which represents roughly
25,000 workers. Mr. Smith said:
Some years back, one of my members walked into my office with a
very unusual object: a plumbing trap. [He] handed it to me. First
thing I noticed, it was pretty heavy, two to three pounds. He said,
`That's from my shower at home.' At the time, he had been in the
tile industry, cutting tile for about 10 years. He said, `My drain
kept getting clogged. No matter what I put in there, I couldn't get
it unclogged. I called the plumber. He couldn't get it unclogged. He
took it off. I looked inside. It was filled with...what I would
call reconstituted cement.' This came off of his body (Document ID
3581, Tr. 1599-1600).
UAW Local 523 President Jeff P'Poole spoke about making silicon metal
out of granite with an electric arc furnace reduction process, "...
people come out with like raccoon eyes...you'll look like a coal
miner at times..." (Document ID 3582; Tr. 1840). Construction
employee Santiago Hernandez testified that employees often have to
throw away their work clothing because dust remains embedded even after
washing the clothes (Document ID 3571, Attachment 7, p. 1).
OSHA received comments supporting a requirement for employer
provision of work clothing, or storage, handling, removal and cleaning
responsibilities for contaminated work clothing (Document ID 2212, p.
2; 2256, Attachment 2, p. 11; 2277, p. 4; 2310, Attachment 1, pp. 2-4;
2315, p. 9; 3586, Tr. 3199-3200). For example, the International Safety
Equipment Association requested that OSHA require employers to provide
protective garments at no cost to the employee, indicating that this
would be consistent with other OSHA standards that require employers to
pay for personal protective equipment (Document ID 2212, p. 2).
However, numerous comments received on the provision for protective
work clothing in regulated areas were opposed to OSHA's proposed
requirement for employers to either provide protective clothing or
other means of removing excessive silica dust from contaminated
clothing, and to ensure that clothing is removed or cleaned upon
exiting a regulated area when there is potential for employees'
clothing to become grossly contaminated by silica dust (Document ID
1785, p. 8; 2116, Attachment 1, p. 11; 2187, p. 6; 2195, p. 7; 2296, p.
40; 2319, pp. 90-91; 2337, p. 2; 2339, p. 8; 2357, pp. 29-30; 2363, p.
6; 3577, Tr. 713-714; 3580, Tr. 1376-1377; 3584, Tr. 2669; 4035, p. 9).
Many contended that the language in the provision was vague or
subjective. For example, the Tile Council of North America, the
National Tile Contractors Association, and Morgan Advanced Materials
argued that the term "grossly" is subjective, and its use in this
context would subject the employer to the whim of the compliance
inspector (Document ID 2267, p. 6; 2363, p. 6; 2337, p. 2).
The American Society of Safety Engineers (ASSE) indicated that no
special clothing should be required, as crystalline silica does not
present a hazard from skin contact. Instead, ASSE suggested that
employers need to implement programs to assure employees whose clothing
is contaminated with crystalline silica do not create exposure issues
outside of the workplace (Document ID 2339, p. 8). NAHB argued that
protective clothing such as coveralls would be difficult for workers in
residential construction to use because coveralls frequently restrict
movement, are often not durable enough for the conditions encountered
in construction, and could contribute to heat stress (Document ID 2296,
p. 40).
The evidence regarding the extent to which dust-contaminated
clothing may exacerbate employee exposure to respirable crystalline
silica is mixed. NIOSH stated that past studies have shown a
significant increase in workers' respirable dust exposure from
contaminated work clothing, referencing a Bureau of Mines study
involving highly-exposed machine operators bagging mineral products
into paper bags (Document ID 2177, Attachment B, p. 15). On the other
hand, the National Industrial Sand Association (NISA) stated that:
NISA member companies have years of experience conducting root
cause analyses of exceedances of the PEL. In that experience,
contaminated work clothing can be the source of such an exceedance,
but such circumstances are uncommon (Document ID 2195, p. 37).
OSHA agrees that contaminated work clothing can contribute to
respirable dust exposures in some circumstances, as NIOSH indicated.
However, OSHA concludes that the evidence in the rulemaking record does
not show that contaminated work clothing contributes appreciably to
employee exposures to respirable crystalline silica in workplace
conditions covered by this rule. OSHA is therefore not including a
requirement for protective clothing in the rule because it is unable to
determine that the use of protective clothing would provide appreciable
protection from inhalation of respirable crystalline silica in most
circumstances. OSHA understands that many of the activities covered
under the rule involve generation of substantial amounts of dust.
However, the dust of concern in this rulemaking is composed only of
respirable crystalline silica particles--those particles small enough
to penetrate deep into the lungs. OSHA proposed protective clothing
requirements in regulated areas in an attempt to focus on those areas
in the workplace where high exposures to respirable crystalline silica
occur. However, it is not clear that measures to address dust on
employees' clothing are likely to have any meaningful effect on exposures
to respirable crystalline silica in most workplaces covered by the rule.
Protective clothing is primarily designed to mitigate against
dermal hazards, which are not the problem here; nor is dermal exposure
(as opposed to respiratory exposure) the mechanism by which silica
causes its adverse health effects. Therefore, special or employer-
provided protective clothing would be no more protective than ordinary
clothing in this context. Moreover, OSHA understands the practical
difficulty that employers would encounter in attempting to determine
when clothing is sufficiently contaminated to trigger a requirement for
protective measures. Therefore, OSHA has not included a requirement for
employers to provide protective work clothing or other means of
removing silica dust from clothing in the rule. There may be instances
where providing protective clothing or other means of removing
excessive silica dust from clothing are feasible methods of limiting
employee exposures to respirable crystalline silica; in such cases,
these methods become an option for complying with the requirement to
limit employee exposures to the PEL.
OSHA has also decided not to include the proposed option to
establish and implement an access control plan in lieu of a regulated
area in the rule. As noted above, paragraph (e)(1) of the proposed
standards for general industry/maritime and construction would have
required the establishment and implementation of either a regulated
area or an access control plan wherever an employee's exposure to
airborne concentrations of respirable crystalline silica is, or
reasonably could be expected to be, in excess of the PEL. OSHA
recognized that establishing regulated areas in some workplaces might
be difficult. As such, the Agency proposed an option for establishing
and implementing a written access control plan in lieu of a regulated
area.
The option for a written access control plan contained provisions
for: A competent person to identify the presence and location of areas
where respirable crystalline silica exposures exceed the PEL; notifying
employees and demarcating such areas; communicating with other
employers on multi-employer worksites; limiting access to areas where
exposures exceed the PEL; providing respirators; and addressing
measures regarding contaminated work clothing. The proposed rule also
included a requirement for an annual employer review and evaluation of
the written access control plan, and the plan was to be made available
upon request for examination and copying to employees, their
representatives, and the Assistant Secretary and the Director.
The intent of the provision for establishing written access control
plans in lieu of regulated areas was to provide employers with
flexibility to adapt to the particular circumstances of their worksites
while maintaining equivalent protection for employees. The option for
establishing a written access control plan was thought to be best
suited for changing or mobile worksites such as those found in
construction and utilities.
The North American Insulation Manufacturers Association supported
the option for a written access control plan, claiming that it is
similar to current mineral wool industry practices for limiting access
(Document ID 2348, p. 36). The National Concrete Masonry Association
and approximately five of its member companies stated that access
control plans may be effective for tasks in which personal protective
equipment is needed (e.g., mixer cleaning), but not for operations that
cannot be performed in a controlled, limited areas (e.g., general plant
clean-up) (e.g., Document ID 2279, p. 10; 2388, p. 9).
Commenters including American Subcontractors Association (ASA),
Leading Builders of America (LBA), NAHB, and the Construction Industry
Safety Coalition (CISC), thought that a written access control plan was
impractical in the construction industry, stating reasons such as
uncertainty about its requirements or how such plans would differ from
a regulated area (e.g., Document ID 2187, p. 5; 2269, p. 22; 2296, pp.
25-26; 2319, pp. 88-89). Additionally, the Communication Workers of
America (CWA), UAW, and AFL-CIO felt that, given issues of
enforceability, it did not appear the written access control plan would
adequately protect workers and limit access to high-exposure work
areas. Thus, CWA, UAW, and AFL-CIO recommended elimination of the
option for a written access plan, and for the provision to be limited
to a regulated areas requirement only (Document ID 2240, p. 2; 2282,
Attachment 3, p. 16; 3578, Tr. 924-925). Fann Contracting, Inc.
indicated that neither written access control plans nor regulated areas
were conducive to outdoor, heavy highway and road and bridge
construction where the entire worksite has potential for silica
exposure (Document ID 2116, Attachment 1, pp. 26-27).
OSHA concludes that the option for a written access control plan
may prove less protective and would be difficult to enforce, so has
decided not to include the option for employers to develop and maintain
written access control plans in lieu of regulated areas in the rule.
OSHA no longer views a written access control plan to be a viable
substitute for establishment and maintenance of regulated areas in the
rule, especially in light of its decision not to include a regulated
areas requirement in the standard for construction. The requirement for
a competent person in paragraph (g)(4) of the standard for construction
provides an alternate approach to restricting access to areas where
high exposures can occur, and OSHA's expectation is that it will
achieve a comparable level of protection without imposing the burden of
maintaining a written access control plan.
The decision not to require regulated areas in the standard for
construction reflects OSHA's acknowledgment of the impracticality of
establishing and demarcating regulated areas in many construction
industry workplaces. However, as described in further detail in the
summary and explanation of Written Exposure Control Plan, OSHA has
concluded that implementing a written exposure control plan, which
includes a requirement to describe procedures to restrict access to
work areas, is practical in construction industry workplaces. OSHA
notes that a written access control plan as contemplated in the
proposed rule is different from a written exposure control plan as
mandated in the rule. Written exposure control plans are included in
the industry consensus standards: ASTM E 1132-06, Standard Practice for
Health Requirements Relating to Occupational Exposure to Respirable
Crystalline Silica and ASTM E 2625-09, Standard Practice for
Controlling Occupational Exposure to Respirable Crystalline Silica for
Construction and Demolition Activities (Document ID 1466, p. 2; 1504, p. 2).
OSHA finds that written exposure control plans provide a systematic approach
for ensuring proper function of engineering controls and effective work
practices that can prevent overexposures from occurring. The ASTM standards
do not specifically call for procedures to restrict access; however, they do
call for a description of administrative controls to reduce exposures
(Document ID 1466, p. 2; 1504, p. 2). An example of such an
administrative control for minimizing the number of employees exposed
to respirable crystalline silica would be to schedule high-exposure
tasks to be conducted when others will not be in adjacent areas
(Document ID 3583, Tr. 2385-2386).
Commenters from the construction industry submitted comments on the
regulated area option. Some of the comments were generally supportive
(Document ID 2169, p. 4; 2177, Attachment B, p. 14; 2262, pp. 43-44;
2339, p. 4). However, other stakeholders felt that OSHA's proposed
requirements for regulated areas would be unworkable and infeasible in
construction (e.g., Document ID 2116, Attachment 1, p. 13; 2183, pp. 1-
2; 2187, p. 5-6; 2269, p. 4; 2276, p. 5; 2319, pp. 89-90; 2323, p. 1;
2338, p. 3; 2345, p. 3). They expressed serious concerns with the
proposed provisions for establishing and limiting access to regulated
areas, often citing challenges posed by constantly changing work
activities, multiple employers on the worksite, lack of employer
control in outside construction projects, the possibility of an entire
worksite needing to be classified as a regulated area (on small
worksites), and the prevalence of silica in the natural environment,
particularly in certain regions of the country (e.g., Document ID 2116,
pp. 13-14, 22, 27; 2183, pp. 1-2; 2319, p. 89; 2323, p. 1; 2210,
Attachment 1, p. 7; 2187, pp. 5-6; 2246, p. 11; 2269, p. 22; 2296, p.
26; 3230, p. 2). For example, ASA questioned a subcontractor's ability
to control the environment on a multiemployer job site, stating:
...even if a trade contractor were to establish a regulated area,
it may not be able to limit access or operations by individuals
outside of its management or control, particularly in the absence of
a representative of a general contractor or construction manager
(Document ID 2187, p. 6).
The Interlocking Concrete Pavement Institute indicated that other
construction trade workers labor in the same area from 10 to 90 percent
of the time, and that efforts by OSHA to restrict access among trades
on a job site would result in chaos (Document ID 2246, p. 11). The LBA
added that, although OSHA's proposed requirements might be suitable for
a single-employer setting where working conditions are somewhat
consistent, they were unworkable in the construction industry (Document
ID 2269, p. 8).
OSHA received feedback from employee representatives and public
health advocates indicating support for a requirement that employers
establish and limit access to areas where high exposures may occur in
the construction industry (Document ID 2177, Attachment B, p. 14; 2371,
Attachment 1, pp. 17-19; 3589, Tr. 4263; 4223, p. 102). For example,
the Laborers Health and Safety Fund of North America argued that
regulated areas are helpful because they provide a visible indicator
that a hazardous area exists for employees in different trades who may
be on the worksite but would not otherwise be aware of the potential
for exposure to respirable crystalline silica in that area (Document ID
3589, Tr. 4263). NIOSH supported the need to protect workers on a
construction site from exposure via regulated areas and/or a written
access control plan. NIOSH also noted the importance of competent
persons and how they play an integral role in establishing regulated
areas (Document ID 2177, Attachment B, pp. 8-10, 14).
Several commenters representing public health organizations and
unions opined that construction employers could implement regulated
areas on construction sites without a great deal of difficulty
(Document ID 3585, Tr. 3090-3091; 4234, Part 1, pp. 24-25). The
American Industrial Hygiene Association (AIHA) suggested how an
employer might determine whether a regulated area needs to be
established:
Utilization of the Table 1 as a compliance option when
respirators are required means the surrounding area must be
considered a regulated area or under an access control plan. This
combined with the engineering controls can help address the common
problem of adjacent workers being inadvertently exposed to silica
particulates. The need for a regulated area or control plan would
now be an objective determination by the competent person. This in
turn would help identify workers or areas where inadvertent exposure
may occur and consequently allow procedures to be implemented to
prevent this (Document ID 2169, p. 4).
Other commenters indicated that, to an extent, regulated areas
already exist on construction sites. At the public hearings, the Mason
Contractors Association of America provided testimony pointing out that
a vast majority of masonry work is already carried out in restricted
zones, and that access to these zones by other workers is limited. They
noted that access to these restricted work zones was ultimately
controlled by the general contractor (Document ID 3585, pp. 2933-2934).
BCTD noted that Kevin Turner of Hunt Construction Group, testifying on
behalf of CISC, indicated that contractors creating a hazard on
construction worksites identify their work areas to avoid putting other
workers at risk, and explained how different contractors on a multi-
employer site routinely establish exclusion zones to exclude other
workers from hazardous areas. BCTD argued that there is no reason why
such an approach would not work for areas with high silica exposure as
well (Document ID 4223, p. 102-105). ASSE indicated that, while the
organization recognized the potential value of establishing regulated
areas where silica overexposures are anticipated, there may be valid,
practical reasons for exempting short-term construction worksites from
this requirement as long as alternative worker protections are in place
(Document ID 3430, p. 3)
After a review of these comments submitted on the proposed rule by
construction industry stakeholders, OSHA concludes that a requirement
for regulated areas is not appropriate for the construction standard.
OSHA proposed to require regulated areas wherever an employee's
exposure to respirable crystalline silica is, or can reasonably be
expected to be, in excess of the PEL. However, OSHA expects that a
majority of the regulated community in construction will implement the
specified exposure control methods presented in paragraph (c) of the
standard for construction (i.e., the controls listed in Table 1) for
the purposes of reducing occupational exposure to respirable
crystalline silica and to assure compliance with the standard.
Employers who implement the specified exposure control methods
presented in paragraph (c) of the standard for construction will not be
required to assess employee exposures to respirable crystalline silica,
and thus will not necessarily be aware of situations where employee
exposures exceed the PEL. Furthermore, these employers who are not
necessarily required to conduct an exposure assessment would thereby
not have the data necessary to establish and demarcate the boundaries
of regulated areas (i.e., the point at which exposures no longer exceed
the PEL). Therefore, most construction employers will not have an objective
basis for establishing regulated areas.
In addition, OSHA basis its decision not to require regulated areas
in the standard for construction in part on its recognition that
conditions at construction worksites present challenges to establishing
regulated areas for respirable crystalline silica exposure due to the
varied and changing nature of construction work. Various commenters
representing construction interests expressed how factors such as
environmental variability normally present in construction differ
substantially from those typically found in general industry and
maritime workplaces. These commenters noted that construction tasks are
often of relatively short duration; they are commonly performed
outdoors, sometimes under adverse environmental conditions; and they
are normally performed at non-fixed workstations or worksites. These
factors make establishment of regulated areas impractical for many
construction tasks. Silica-generating tasks in construction often
involve movement to different locations during the workday, and
respirable crystalline silica may be subject to changes in wind
currents, meaning that exposure patterns may frequently shift.
Accordingly, in the typical construction project involving silica-
generating tasks, it is difficult to determine appropriate boundaries
for regulated areas because the work and worksite are varied and
subject to environmental influences (e.g., Document ID 2246, p. 11;
2269, pp. 4, 9-10; 2289, pp. 6-7; 2309, p. 3; 2327, p. 20).
OSHA finds the evidence of the particular and varying nature of
construction work persuasive. Furthermore, the requirement for a
competent person as part of the written exposure control plan
requirements in paragraph (g)(4) of the standard for construction
provides that a designated competent person on the worksite will have
the responsibility to restrict access to work areas, where necessary,
to limit exposures to respirable crystalline silica. OSHA concludes
that this requirement will achieve the primary objectives of a
regulated area.
OSHA realizes that in some cases general industry work tasks and
work environments may be comparable to those found in construction.
Although no exceptions have been carved out of the requirement in the
standard for general industry and maritime, where the general industry
or maritime employer can show compliance is not feasible, regulated
areas will not have to be established insofar as infeasibility is a
complete defense to an OSHA citation. See United Steelworkers v.
Marshall, 647 F.2d 1189 (D.C. Cir. 1980); Marshall v. West Point
Pepperell, Inc., 588 F.2d 979 (5th Cir. 1979). As a general matter,
however, OSHA's longstanding distinction between general industry
(including, for these purposes, the maritime sector), on the one hand,
and the construction sector, on the other hand, provides an appropriate
line for delineating between those tasks where the employer generally
is reasonably able to establish regulated areas where exposures to
respirable crystalline silica exceed the PEL versus tasks where
regulated areas are generally not practicable.
ASTM E 1132-06 and ASTM E 2625-09 do not include requirements for
regulated areas. However, both industry consensus standards indicate
that workers should not work in areas where visible dust is generated
from crystalline silica-containing materials without the use of
respiratory protection, unless proven protective measures are used or
sampling shows exposure is below the exposure limit (see Section
4.4.3.1 in each standard) (Document ID 1466, p. 4; 1504, p. 3). OSHA
considers the approach taken in its standard for construction to be
consistent with the approach taken in the ASTM standards. OSHA further
considers that the requirement for regulated areas in the standard for
general industry and maritime better effectuates the purposes of the
OSH Act because the establishment of regulated areas in those
workplaces, where they are most effective, serves to limit the number
of employees exposed and the level of exposure of employees who would
otherwise be at significant risk of suffering adverse health effects
from exposure to respirable crystalline silica. As explained above,
regulated areas make employees aware of the presence of respirable
crystalline silica at levels above the PEL and the need for protective
measures, and serve to limit respirable crystalline silica exposure to
as few employees as possible. Additionally, OSHA notes that the
industry consensus standards addressing occupational exposure to
respirable crystalline silica do not include requirements for
protective clothing. The OSHA rule is consistent with the consensus
standards in this respect also.
Methods of Compliance
Paragraph (f)(1) of the standard for general industry and maritime
(paragraph (d)(3)(i) of the standard for construction) establishes a
hierarchy of controls that employers must use to reduce and maintain
exposures to respirable crystalline silica to or below the permissible
exposure limit (PEL) of 50 [mu]g/m\3\. The rule requires employers to
implement engineering and work practice controls as the primary means
to reduce exposure to the PEL or to the lowest feasible level above the
PEL. In situations where engineering and work practice controls are not
sufficient to reduce exposures to or below the PEL, employers are
required to supplement these controls with respiratory protection,
according to the requirements of paragraph (g) of the standard for
general industry and maritime (paragraph (e) of the standard for
construction).
OSHA's long-standing hierarchy of controls policy was supported by
many commenters including the National Institute for Occupational
Safety and Health (NIOSH), the American Society of Safety Engineers
(ASSE), the American Industrial Hygiene Association, the American
Federation of Labor and Congress of Industrial Organizations (AFL-CIO),
the American Public Health Association (APHA), the National Asphalt
Pavement Association (NAPA), the National Utility Contractors
Association, the American Road and Transportation Builders Association
(ARTBA), and the International Safety Equipment Association (ISEA)
(e.g., Document ID 1757, p. 4; 1771, p. 1; 1797, p. 5; 1800, p. 5;
2106, p. 2; 2166, p. 3; 2173, p. 4; 2178, Attachment 1, pp. 3-4; 2181,
p. 9; 2240, p. 2; 2256, Attachment 2, pp. 11-12; 2278, p. 3; 2313, p.
6; 2315, p. 3; 2329, p. 5; 2336, p. 7; 2371, Attachment 1, p. 22; 2373,
pp. 3-4; ; 3468, p. 3; 3516, p. 3; 3577, Tr. 791; 3578, Tr. 1044-1045;
3579, Tr. 182-183; 3581, Tr. 1564, 1648-1651; 3583, Tr.2237, 2243-2244,
2451, 2456; 3584, Tr. 2576-2577; 3955, Attachment 1, p. 2; 3585, Tr.
3112; 3586, Tr. 3162, 3200; 3589, Tr. 4147; 1759; 4203, p. 4; 4204, pp.
64-65; 4219, pp. 16, 20; 4223, p. 86; 4227, p. 1; 4233, Attachment 1,
p. 14; 4235, p. 14). Tom Ward, a bricklayer and member of the
International Union of Bricklayers and Allied Craftworkers (BAC)
testified:
[The hierarchy of controls] is the first thing we are supposed
to do. Whenever feasible, eliminate the hazard. PPE is and always
should be the last line of defense. Switching it is going backwards
...(Document ID 3585, Tr. 3070).
Many industry commenters, including trade associations, generally
objected to OSHA's proposed application of the hierarchy of controls in
the rule. These commenters included the U.S. Chamber of Commerce (the
Chamber), Associated Builders and Contractors, the Association of
American Railroads (AAR), Battery Council International (BCI), the
Motor and Equipment Manufacturers Association (MEMA), the Institute of
Makers of Explosives (IME), the Association of Energy Service Companies,
and the Precast/Prestressed Concrete Institute (PCI) (e.g., Document ID
1728; 1992, pp. 10-11; 2102, p. 2; 2130, pp. 1-2; 2151, p. 1; 2211, pp.
6-7; 2213, pp. 3-4; 2276, p. 3; 2288, pp. 12-13;2289, p. 7; 2325, p. 2;
2326, p. 2; 2344, p. 2; 2361, p. 3; 2366, p. 5; 4194, pp. 12-13). These
commenters asked OSHA to reconsider its preference for engineering and
work practice controls and permit the use of respiratory protection, such
as powered air-purifying respirators (PAPRs), instead of engineering and
work practice controls to reduce exposures to respirable crystalline
silica to or below the PEL. For example, the Chamber urged OSHA to
support
...new technology and policies favoring effective, comfortable,
respirators and clean filtered air helmets, which provide full
protection but are not favored by OSHA's outdated `hierarchy of
control' policy (Document ID 4194, p. 4).
Similarly, the American Foundry Society (AFS) argued that:
OSHA's preference for controls other than respirators is based
on a policy that was adopted decades ago, and fails to take into
account changes in respirator technology that have resulted in
improved performance, improved reliability, improved worker
acceptance, and increased protection (Document ID 3487, p. 25).
Greg Sirianni, an industrial hygienist testifying for the Chamber,
commented that some respiratory protection, such as PAPRs, "should not
be looked at as mere respirators, but as microenvironmental engineering
controls" (Document ID 2364, p. 12). He described several studies
demonstrating the effectiveness of PAPRs with helmets/hoods (Document
ID 2364, pp. 6-7). He also referenced studies showing that PAPRs reduce
physiological burdens, as well as provide increased comfort, ease of
use, and improved communication, when compared to traditional air-
purifying respirators (Document ID 2364, pp. 8-10). Other industry
commenters, including the National Association of Manufacturers (NAM),
AFS, and National Mining Association, echoed Mr. Sirianni's conclusion
about the effectiveness of PAPRs (Document ID 2211, pp. 6-7; 2379,
Appendix 1, p. 49; 2380, Attachment 2, pp. 22-23; 3489, p. 5;). Peter
Mark, Corporate Director of Safety, Health, and Environment at Grede
Holdings, testified that some respirators, such as air-supplied
helmets, can also provide eye and face protection (Document ID 3584,
Tr. 2685-2686). The George Washington University Regulatory Studies
Center argued that OSHA's hierarchy of controls eliminates the
incentive to develop more effective, lower cost, and more comfortable
respirators and "distorts the development of new knowledge that could
provide superior protection for employees" (Document ID 1831, p. 15).
Other commenters pointed to the disadvantages of engineering
controls. The Construction Industry Safety Coalition (CISC), NAM, PCI,
and AFS noted that engineering controls are subject to human error and
maintenance concerns (Document ID 2319, p. 95; 2380, Attachment 2, p.
22; 3487, p. 25; 3581, Tr. 1738, 1762; 3589, Tr. 4357). The Tile
Roofing Institute (TRI), National Roofing Contractors Association
(NRCA), National Association of Home Builders (NAHB), CISC, and NAM
described situations where the use of engineering and work practice
controls could present other hazards, such as falls (Document ID 2191,
pp. 9-10; 2214, pp. 3-4; 2296, p. 28; 2319, p. 93; 3587, Tr. 3593-3594;
4225, p. 2; 4226, p. 3). OSCO Industries (OSCO) commented that where
ventilation requires all doors and windows to be closed, engineering
controls can put physiological and psychological strain on employees
(Document ID 1992, p. 10).
NIOSH provided evidence that recent improvements in PAPRs have not
eliminated all of their disadvantages. NIOSH cited several studies
suggesting that psychological issues, medical disqualifications,
communication impairment, hearing degradation, and visual impairment
remained even for PAPRs (Document ID 4233, Attachment 1, pp. 17-20).
NIOSH also noted that there are no maximum weight requirements for
PAPRs, some of which can be fairly heavy (Document ID 4233, Attachment
1, p. 18). When questioned about the use of PAPRs in the brick
industry, Thomas Brown, the Director of Health and Safety at Acme Brick
Company, testified that:
No, we have not used [PAPRs]. And the reason why [is] it would
be almost virtually impossible to wear those type[s] of respirators
and perform the tasks that they are doing (Document ID 3577, Tr.
752).
No commenter representing employees or public health organizations
agreed that PAPRs have improved to the point that they have become
preferable to engineering controls. For example, when asked whether
PAPRs should be viewed as an alternative to engineering controls and
treated on the same level in the hierarchy of controls, Frank Hearl,
Chief of Staff at NIOSH, testified that, "...in terms of the PAPR
and other respirators, it all sort of falls into the hierarchy of
controls and suffers the same problems as the other respirators in that
it doesn't control the entire environment" (Document ID 3579, Tr.
233). The Building and Construction Trades Department, AFL-CIO (BCTD)
testified that PAPRs are not an adequate alternative given that they do
not "...control the hazards at the source for all workers"
(Document ID 3581, Tr. 1668-1669). Similarly, ISEA commented that ". .
. the association does not believe PAPRs can be used as engineering
controls" since they do not remove hazards from the workplace
(Document ID 4227, p. 1).
NIOSH, public health organizations, labor unions, individual
employees, trade associations, public interest organizations and
employers also provided additional evidence of the discomfort and
difficulties experienced by employees who wear respirators (e.g.,
extreme temperatures, visibility restrictions, communication
impairment, psychological issues, strain on respiratory and cardiac
systems) (Document ID 1758; 2116, Attachment 1, p. 28; 2178, Attachment
1, p. 4; 2181, pp. 9, 12; 2262, p. 26; 2314, p. 2; 2373, p. 4; 3571,
Attachment 1, p. 2; 3577, Tr. 839-841; 3579, Tr. 183-184; 3580, Tr.
1526-1527; 3582, Tr. 1872-1874, 1897, 1899-1901; 3583, Tr. 2434-2435;
3585, Tr. 3112; 3586, Tr. 3174-3175, 3180, 3250, 3252-3253; 3587, Tr.
3583-3584, 3637-3638; 4233, Attachment 1, pp. 18-19; 4235, p. 12).
Other commenters, including NIOSH, the International Union of Operating
Engineers (IUOE), the Brick Industry Association, TRI, NAPA, ARTBA, the
Interlocking Concrete Pavement Institute, Black Roofing, the National
Tile Contractors Association, Acme Brick, and iQ Power Tools also
described how respirator use can exacerbate various safety and health
threats to employees, such as trips, falls, "struck by" hazards, saw
hazards, and heat stress (Document ID 2262, p. 25; 2293; 3529, p. 2;
3577, Tr. 714, 750-752; 3583, Tr. 2170, 2237, 2372, 2435-2437; 3586,
Tr. 3341, 3406; 3587, Tr. 3583-3584, 3594; 3589, Tr. 4373; 4225, p. 6;
4233, Attachment 1, p. 18; 4234, Part 1 and Part 2, pp. 30-31; 4235, p.
12). IUOE, the Laborers' Health and Safety Fund of North America
(LHSFNA), and Arch Masonry further noted that reliance on respirators
to protect employees from exposures to respirable crystalline silica could
end the careers of employees who cannot pass the medical evaluation, but
can do the work (Document ID 2262, p. 27; 2292, p. 4; 3587, Tr. 3656-3567;
3589, Tr. 4274-4275).
In addition, NIOSH and other public health professionals described
how respirators are more prone to misuse or other human error, as they
depend on human behavior to achieve beneficial results (Document ID
2374, Attachment 1, pp. 5-6; 3577, Tr. 848-849; 3579, Tr. 183-184). On
the other hand, engineering controls are easier to monitor and
maintain. As Dr. Celeste Monforton testified:
It is illogical to suggest that diligently meeting all the
laborious requirements necessary for an effective respiratory
protection program for a whole crew of employees is easier than
ensuring that a handful of silica-generating pieces of equipment are
maintained (Document ID 3577, Tr. 849).
Various individuals and organizations detailed the lack of adequate
fit testing and respiratory protection programs in practice, which can
significantly impact respirator effectiveness. These included Dr.
Monforton, ASSE, the National Council of La Raza, the National
Consumers League (NCL), APHA, the National Council for Occupational
Safety and Health, NRCA, and Arch Masonry as well as workers, including
James Schultz and Allen Schultz (Document ID 2166, p. 3; 2173, p. 5;
2178, Attachment 1, pp. 3-4; 2373, pp. 3-4; 3577, Tr. 848-849; 3578,
Tr. 1040-1041, 1042-1043; 3586, Tr. 3161, 3213-3214, 3236-3237, 3253-
3254; 3587, Tr. 3625, 3680-3681; 3955, Attachment 1, p. 2). Workers,
including James Schultz, Jonass Mendoza, Santiago Hernandez, Juan Ruiz,
Norlan Trejo and Jose Granados described their negative experiences
with respirator use, including the lack of fit testing, training, and
proper maintenance (Document ID 3571, Attachment 2, p. 3; 3571,
Attachment 3, p. 2; 3571, Attachment 5, p. 1; 3571, Attachment 7, p. 1;
3583, Tr. 2487; 3586, Tr. 3201-3202;). Dr. Laura Welch, representing
BCTD, testified that in her experience, respiratory protection does not
prevent employees from developing lung disease, but that engineering
controls are effective (Document ID 3581, Tr. 1648-1649).
Further, NIOSH, labor organizations (e.g., LHSFNA, the
International Association of Sheet Metal, Air, and Rail Transportation
Workers, the Operative Plasterers' and Cement Masons' International
Association, the International Union of Painters and Allied Trades
(IUPAT), the United Union of Roofers, Waterproofers, and Allied
Workers, BAC, the United Steelworkers, BCTD, and AFL-CIO), public
health organizations (e.g., APHA), public interest organizations (e.g.,
the Center for Biological Diversity, the Center for Effective
Government, and NCL), and individual workers described how limiting
exposure to respirable crystalline silica at its source through
engineering and work practice controls best protects employees involved
in dust-generating operations, as well as other employees and the
public from these exposures (e.g., Document ID 2178, Attachment 1, p.
4; 2253, pp. 1-2; 2329, p. 4; 2373, p. 4; 2374, Attachment 1, pp. 5-6;
3516, p. 3; 3579, Tr. 184-185, 233; 3581, Tr. 1590, 1593-1594, 1649-
1651,1669, 1708-1709; 3582, Tr. 1878-1879, 1881-1883; 3583, Tr. 2455-
2456; 3584, Tr. 2578-2579; 3585, Tr. 3067-3069; 4204, pp. 68, 72-74;
3589, Tr. 4232-4233; 4223, pp. 86-87; 4233, Attachment 1, pp. 11-14).
For example, LHSFNA noted that using controls on jackhammers, chipping
guns, hand-held grinders, and drywall sanders can reduce exposures to
nearby laborers (Document ID 2253, pp. 1-2). Norlan Trejo testified
that when cutting ceramic and granite, wet cutting helps protect both
the employee and bystanders (Document ID 3583, Tr. 2455-2456). Sean
Barrett, a terrazzo worker, testified that grinding floors in the
terrazzo industry exposes everyone on the worksite if controls are not
used:
Every other trade has to walk through the cloud [of dust] to get
in and out of the building to use the outhouses or to go to the
coffee truck or even go home at the end of the day...[T]hey have
no choice but to walk through the dust (Document ID 3585, Tr. 3068).
Additionally, James Schultz, a former foundry employee from the
Wisconsin Coalition for Occupational Safety and Health, provided
testimony about how the lack of engineering controls creates dusty
conditions that can lead to other hazards. He described how dusty
conditions in a foundry led to incidents where employees were struck by
forklifts (Document ID 3586, Tr. 3242-3243).
Some of the same industry commenters advocating for the use of
PAPRs in place of engineering controls have acknowledged the importance
of engineering controls to protect employees from exposures to
respirable crystalline silica. For example, AFS, in its Guide for
Selection and Use of Personal Protective Equipment and Special Clothing
for Metalcasting Operations, describes the hierarchy of controls as the
basis for choosing strategies for protecting employers from exposures
to airborne contaminants. The guide concludes that air-supplied hoods
and PAPRs are important options when choosing respiratory or personal
protection, but does not support using these in lieu of engineering
controls (Document ID 2379, Appendix 6). NAM noted that they were not
opposed to using engineering controls where they are feasible and
effective (Document ID 3581, Tr. 1753). Greg Sirianni, an expert for
the Chamber, testified that:
...there are obviously benefits to engineering controls, and by
all means I want the use of engineering controls when they are
possible. And in certain work environments...you need to have
something that can protect all workers in all scenarios, and
engineering controls are good for most cases, but there are a lot of
workers out there that need [PAPRs], and I really recommend their
use (Document ID 3578, Tr. 1104-1105).
Other industry groups provided additional evidence that the hierarchy
of controls is embraced and applied in practice. For example, Wayne
D'Angelo of the American Petroleum Institute (API) testified that the
organization supports the traditional use of the hierarchy of controls
to protect employees (Document ID 3589, Tr. 4065). The National
Industrial Sand Association (NISA) has built the hierarchy of controls
into its Practical Guide to an Occupational Health Program for
Respirable Crystalline Silica (Document ID 1965, Attachment 2, pp. vii,
44). The National Stone, Sand, and Gravel Association's occupational
health program, which is based on NISA's program, also supports the
industrial hygiene hierarchy of controls (Document ID 3583, Tr. 2312).
OSHA concludes that requiring primary reliance on engineering
controls and work practices is necessary and appropriate because
reliance on these methods is consistent with good industrial hygiene
practice, and with the Agency's experience in ensuring that employees
have a healthy workplace. The Agency finds that engineering controls:
(1) Control crystalline silica-containing dust particles at the source;
(2) are reliable, predictable, and provide consistent levels of
protection to a large number of employees; (3) can be monitored
continually and relatively easily; and (4) are not as susceptible to
human error as is the use of personal protective equipment. The use of
engineering controls to prevent the release of silica-containing dust
particles at the source also minimizes the silica exposure of other
employees in surrounding work areas who are not directly involved in
the task that is generating the dust, and may not be wearing respirators.
This issue of secondary exposures to other laborers and bystanders is
especially of concern at construction sites (e.g., Document ID 2177,
Attachment B, pp. 14-15; 2329, p. 4; 2319, p. 28, 3581, Tr. 1587-1588).
Under the hierarchy of controls, respirators can be another
effective means of protecting employees from exposure to air
contaminants. However, to be effective, respirators must be
individually selected, fitted and periodically refitted,
conscientiously and properly worn, regularly maintained, and replaced
as necessary. In many workplaces, these conditions for effective
respirator use are difficult to achieve. The absence of any one of
these conditions can reduce or eliminate the protection the respirator
provides to some or all of the employees. For example, certain types of
respirators require the user to be clean shaven to achieve an effective
seal where the respirator contacts the employee's skin. Failure to
ensure a tight seal due to the presence of facial hair compromises the
effectiveness of the respirator.
Respirator effectiveness ultimately relies on the good work
practices of individual employees. In contrast, the effectiveness of
engineering controls does not rely so heavily on actions of individual
employees. Engineering and work practice controls are capable of
reducing or eliminating a hazard from a worksite, while respirators
protect only the employees who are wearing them correctly. Furthermore,
engineering and work practice controls permit the employer to evaluate
their effectiveness directly through air monitoring and other means. It
is considerably more difficult to directly measure the effectiveness of
respirators on a regular basis to ensure that employees are not
unknowingly being overexposed. OSHA therefore continues to consider the
use of respirators to be the least satisfactory approach to exposure
control.
In addition, use of respirators in the workplace presents other
safety and health concerns. Respirators can impose substantial
physiological burdens on employees, including the burden imposed by the
weight of the respirator; increased breathing resistance during
operation; limitations on auditory, visual, and olfactory sensations;
and isolation from the workplace environment. Job and workplace factors
such as the level of physical work effort, the use of protective
clothing, and temperature extremes or high humidity can also impose
physiological burdens on employees wearing respirators. These stressors
may interact with respirator use to increase the physiological strain
experienced by employees.
Certain medical conditions can compromise an employee's ability to
tolerate the physiological burdens imposed by respirator use, thereby
placing the employee wearing the respirator at an increased risk of
illness, injury, and even death. These medical conditions include
cardiovascular and respiratory diseases (e.g., a history of high blood
pressure, angina, heart attack, cardiac arrhythmias, stroke, asthma,
chronic bronchitis, emphysema), reduced pulmonary function caused by
other factors (e.g., smoking or prior exposure to respiratory hazards),
neurological or musculoskeletal disorders (e.g., epilepsy, lower back
pain), and impaired sensory function (e.g., a perforated ear drum,
reduced olfactory function). Psychological conditions, such as
claustrophobia, can also impair the effective use of respirators by
employees and may also cause, independent of physiological burdens,
significant elevations in heart rate, blood pressure, and respiratory
rate that can jeopardize the health of employees who are at high risk
for cardiopulmonary disease (see 63 FR 1152, 1208-1209 (1/8/98)).
In addition, safety problems created by respirators that limit
vision and communication must always be considered. In some difficult
or dangerous jobs, effective vision or communication is vital. Voice
transmission through a respirator can be difficult, annoying, and
fatiguing. In addition, movement of the jaw in speaking can cause
leakage, thereby reducing the efficiency of the respirator and
decreasing the protection afforded the employee. Skin irritation can
result from wearing a respirator in hot, humid conditions. Such
irritation can cause considerable distress to employees and can cause
employees to refrain from wearing the respirator, thereby rendering it
ineffective.
These potential burdens placed on employees by the use of
respirators were acknowledged in OSHA's revision of its respiratory
protection standard, and are the basis for the requirement (29 CFR
1910.134(e)) that employers provide a medical evaluation to determine
the employee's ability to wear a respirator before the employee is fit
tested or required to use a respirator in the workplace (see 63 FR at
1152). Although experience in industry shows that most healthy
employees do not have physiological problems wearing properly chosen
and fitted respirators, nonetheless common health problems can cause
difficulty in breathing while an employee is wearing a respirator.
While OSHA acknowledges that certain types of respirators, such as
PAPRs, may lessen problems associated with breathing resistance and
skin discomfort, they do not eliminate them. OSHA concludes that
respirators do not provide employees with a level of protection that is
equivalent to engineering controls, regardless of the type of
respirator used. It is well-recognized that certain types of
respirators are superior to other types of respirators with regard to
the level of protection offered, or impart other advantages like
greater comfort. OSHA has evaluated the level of protection provided by
different types of respirators in the Agency's Assigned Protection
Factors rulemaking (68 FR 34036 (06/06/03)). Even in situations where
engineering controls are not sufficiently effective to reduce exposure
levels to or below the PEL, the reduction in exposure levels benefits
employees by reducing the required protection factor of the respirator,
which provides a wider range of options in the type of respirators that
can be used. For example, for situations in which dust concentrations
are reduced through use of engineering controls to levels that are less
than ten times the PEL, employers would have the option of providing
approved half-mask respirators with an assigned protection factor (APF)
of 10 that may be lighter and easier to use when compared with full-
facepiece respirators.
All OSHA substance-specific health standards have recognized and
required employers to observe the hierarchy of controls, favoring
engineering and work practice controls over respirators. OSHA's PELs,
including the previous PELs for respirable crystalline silica, also
incorporate this hierarchy of controls. The Agency's adherence to the
hierarchy of controls has been successfully upheld by the courts (see
Section II, Pertinent Legal Authority for further discussion of these
cases). In addition, the industry consensus standards for crystalline
silica (ASTM E 1132-06, Standard Practice for Health Requirements
Relating to Occupational Exposure to Respirable Crystalline Silica, and
ASTM E 2625-09, Standard Practice for Controlling Occupational Exposure
to Respirable Crystalline Silica for Construction and Demolition
Activities) incorporate the hierarchy of controls. NRCA also pointed
out that the ANSI Z10, Standard for Occupational Health and Safety
Management Systems, supports the hierarchy of controls (Document ID
2214, p. 3) and Dr. Celeste Monforton noted that the hierarchy of
controls has been followed and adopted by safety and health regulatory
agencies around the world, including Safe Work Australia, the country's
tripartite health and safety body, and the Canadian Province of Ontario's
Health and Safety Agency (Document ID 3577, Tr. 847-848).
As explained in Section II, Pertinent Legal Authority, the very
concept of technological feasibility for OSHA standards is grounded in
the hierarchy of controls. The courts have clarified that a standard is
technologically feasible if OSHA proves a reasonable possibility,
...within the limits of the best available evidence...that
the typical firm will be able to develop and install engineering and
work practice controls that can meet the PEL in most of its
operations (United Steelworkers v. Marshall, 647 F.2d 1189, 1272
(D.C. Cir. 1980)).
Allowing use of respirators instead of engineering and work practice
controls would be a significant departure from this framework for
evaluating the technological feasibility of a PEL.
While labor groups were opposed to any exemptions from the
hierarchy of controls (Document ID 3586, Tr. 3235-3237), industry
commenters, including both individual employers and trade associations,
urged OSHA to consider making exemptions to the hierarchy in various
situations. Commenters, including the Edison Electric Institute (EEI),
Dal-Tile, the Glass Association of North America (GANA), the Tile
Council of North America, the Non-Ferrous Founders' Society (NFFS),
PCI, and the Chamber, argued that employers need flexibility to
determine when enough engineering controls have been added and when
respirators can be used (Document ID 2147, p. 3; 2215, p. 6; 2276, p.
6; 2357, pp. 25-26; 2363, p. 4; 3491, p. 4; 3576, Tr. 466; 3589, Tr.
4364). NAM echoed this, arguing that employers will never know when or
if they are in compliance with the requirement to incorporate all
feasible engineering and work practice controls and the Agency should
thus base its requirements on objective criteria, while allowing
flexibility to achieve compliance (Document ID 3581, Tr. 1738). Lapp
Insulators, the Indiana Manufacturing Association, Murray Energy
Corporation, BCI, Rheem Manufacturing Company, MEMA, IME, CISC, AFS,
NFFS, and NAM urged OSHA to permit the use of respirators to satisfy
the obligation to control exposures where feasible engineering and work
practice controls are insufficient to bring exposure levels to or below
the PEL (Document ID 1801, pp. 3-4; 2102, p. 2; 2130, pp. 1-2; 2151, p.
1; 2213, pp. 3-4; 2319, p. 95; 2325, p. 2; 2326, p. 2; 2361, p. 3;
2380, Appendix 2, pp. 22-23; 3486, p. 2; 3491, pp. 4-5; 3581, Tr. 1752-
1753; 4226, p. 2). This concern was echoed by other commenters who
encouraged OSHA to permit the use of respirators in industries using
large amounts of crystalline silica (e.g., oil and gas operations where
hydraulic fracturing is conducted), where engineering controls alone
would not be likely to reduce exposures to or below the PEL (Document
ID 2283, p. 3; 3578, Tr. 1090-1091).
OSHA disagrees. Instead, the Agency considers engineering controls
to be the most effective method of protecting employees and allows
respiratory protection only after all feasible engineering controls and
work practices have been implemented or where such controls have been
found infeasible. If an employer has adopted all feasible engineering
controls, and no other feasible engineering controls are available, the
rule would permit the use of respirators. On the other hand, if
feasible engineering controls are available that would reduce
respirable crystalline silica exposures that exceed the PEL, then these
controls are required. Thus, OSHA has concluded these engineering
controls better protect employees.
Commenters, including CISC and OSCO, urged OSHA to permit the use
of respirators for short duration, intermittent, or non-routine tasks
(Document ID 1992, pp. 3, 5; 2319, pp. 95, 115; 3580, Tr. 1463-1464).
Others, such as the Glass Packaging Institute (GPI) and NAM, argued
that OSHA should permit the use of respirators for maintenance
activities (Document ID 2290, pp. 2, 3; 2380, Attachment 2, pp. 14-15;
3493, pp. 2-3). Verallia North America recommended that respirators be
allowed in all refractory repairs (Document ID 3584, Tr. 2848).
Where OSHA requires respirator use in this rule, the requirement is
tied to expected or recorded exposures above the PEL, not categorically
to specific operations or tasks per se. The rule permits the use of
respirators where exposures exceed the PEL during tasks for which
engineering and work practice controls are not feasible. Some tasks,
such as certain maintenance and repair activities, may present a
situation where engineering and work practice controls are not
feasible. For example, GPI noted that respirators are needed to address
failures of any conveyance system (elevators, conveyors, or pipes),
failures of dust collecting bag systems, or section head failures at
glass plant facilities (Document ID 3493, p. 3). OSCO described how
engineering controls are not feasible for cupola (furnace) repair work
and baghouse maintenance activities (Document ID 1992, pp. 3, 5). The
Agency agrees that for tasks, such as certain maintenance and repair
activities, where engineering and work practice controls are not
feasible, the use of respirators is permitted.
The Chamber and the American Subcontractors Association (ASA)
suggested that the hierarchy of controls is not appropriate for silica
exposures in construction workplaces (Document ID 2187, p. 6; 2283, p.
3). While ASSE generally supported the hierarchy of controls, it
acknowledged that there might be practical issues with implementation
on short-term construction worksites (Document ID 2339, p. 4). More
specifically, the Mason Contractors Association of America and Holes
Incorporated urged OSHA to consider the approach taken by the ASTM
standard for the construction industry (ASTM E 2625-09), which provides
an exception to the hierarchy for brief, intermittent silica generating
tasks of 90 minutes or less per day (Document ID 3580, Tr. 1453; 3585,
Tr. 2882). Conversely, BCTD argued that even for silica dust-generating
tasks of short duration where respiratory protection is employed, a
failure to employ engineering controls could result in dangerous
exposures (Document ID 4219, p. 17). They contended that:
There is no evidence in the record that exposures of only 90
minutes a day pose a lower risk of harm, such that respirators would
provide sufficient protection. Moreover...the industry failed to
prove that it is infeasible--or even difficult--to use engineering
controls in most silica-generating tasks (Document ID 4223, p. 88).
OSHA finds, as discussed above, that primary reliance on
respirators to protect employees is inappropriate when feasible
engineering and work practice controls are available. This is as true
for the construction industry, as it is for other industries with
respirable crystalline silica exposures. Even where employees are
conducting intermittent silica generating tasks for 90 minutes or less
per day, if the exposures are above the PEL and feasible engineering
and work practice controls are available, they must be applied.
Further, although an exemption for employees conducting silica
generating tasks for 90 minutes or less per day is included in the ASTM
standard for the construction industry, the standard also includes the
hierarchy of controls, as well as task-based methods of compliance
based on engineering and work practice controls that are feasible and
available for many construction tasks (ASTM E 2625-09). This approach
is consistent with the specified exposure control methods for construction
in paragraph (c)(1) described in the summary and explanation of Specified
Exposure Control Methods. OSHA concludes that requiring the use of all
feasible engineering and work practice controls in the construction
industry, even for tasks of short duration generating respirable
crystalline silica, is reasonably necessary and appropriate to protect
employees from exposures to respirable crystalline silica.
AFS, NISA, GANA, EEI, the North American Insulation Manufacturers
Association (NAIMA), and the Asphalt Roofing Manufacturers Association
urged OSHA to consider allowing employers to use respirators to achieve
compliance for operations where exposures exceed the PEL for 30 days or
less per year (Document ID 4229, p. 11; 2195, pp. 7, 38-39; 2215, pp.
9-10; 2291, pp. 2, 18; 2348, Attachment 1, pp. 17, 26-28, 40; 2357, p.
26; 2379, Appendix 1, pp. 48, 68-69; 3487, pp. 22-23). Similarly, NAM
proposed that OSHA could establish a maximum number of days a year when
respirators can be used in place of engineering controls (Document ID
2380, Attachment 2, pp. 24-25).
Many of the examples mentioned by the commenters supporting this
exemption described maintenance and repair activities, such as baghouse
cleaning and furnace rebuilds. As discussed above, some tasks, such as
certain maintenance and repair activities, may present a situation
where engineering and work practice controls are not feasible. OSHA
agrees that, for tasks of this nature where engineering and work
practice controls are not feasible, the use of respirators is
permitted. Permitting employers to use respirators instead of feasible
engineering and work practice controls for exposures occurring for 30
days or less per year does not best effectuate the purpose of the
rule--to protect employees from exposures to respirable crystalline
silica. Thus, the Agency concludes that the hierarchy of controls is
appropriate whenever feasible engineering and work practice controls
are available.
The American Composite Manufacturers Association suggested that
small businesses be exempt from the hierarchy of controls (Document ID
3588, Tr. 3933-3936). Bret Smith urged OSHA to allow small entities to
use respiratory protection temporarily to allow time to prepare for the
costs of implementation (Document ID 2203). OSHA does not agree that
there should be a distinction between the protection employees receive
in a small business or a large business. Protecting the safety and
health of employees is part of doing business. Thus, exposures to
respirable crystalline silica above the PEL, wherever they occur, must
first be controlled using all feasible engineering and work practice
controls available, before turning to respiratory protection. For the
reasons previously discussed, implementing and maintaining a
comprehensive respiratory protection program is a considerable
undertaking for many employers, and likely even more so for small
businesses. If employers are unable to properly train and fit employees
and maintain the equipment, respirators will not effectively protect
employees from exposures to respirable crystalline silica.
NAM proposed that OSHA adopt language to allow respirators to be
used when exposures are below a specified level:
Where airborne exposures to RCS on a time-weighted-average basis
are below XX milligrams per cubic meter, employers may require the
use of respirators in accordance with the requirements of 1910.134.
Where exposures exceed this level, employers are required to adopt
engineering and administrative controls to reduce exposures
(Document ID 2380, Attachment 2, pp. 24-25).
They specifically provided the example of 5 mg/m\3\ (i.e., 5,000 [mu]g/
m\3\), the respirable dust PEL, which would permit the use of
respirators that provide a protection factor of 100 to achieve
compliance with the PEL of 50 [mu]g/m\3\.
As discussed above, this approach is in conflict with the concept
of technological feasibility for OSHA standards. Technological
feasibility is determined based on the ability of a typical firm to
develop and install engineering controls and work practice controls
that can meet the PEL without regard to the use of respirators. The
approach advanced by NAM would permit the use of respirators to achieve
the PEL, even where exposures reached 100 times the PEL. If
technological feasibility were based solely on the ability of
respirators to meet the PEL, OSHA could determine that a much lower PEL
would indeed be feasible. Further, a failure of respiratory protection
in situations where exposures reach 100 times the PEL could result in
extremely dangerous exposures.
Therefore, OSHA rejects the various comments recommending upsetting
the long-established hierarchy of controls. Because engineering and
work practice controls are capable of reducing or eliminating a hazard
from the workplace, while respirators protect only the employees who
are wearing them and depend on the selection and maintenance of the
respirator and the actions of employees, OSHA holds to the view that
engineering and work practice controls offer more reliable and
consistent protection to a greater number of employees, and are
therefore preferable to respiratory protection. Thus, the Agency
continues to conclude that engineering and work practice controls
provide a more protective first line of defense than respirators and
must be used first when feasible.
Engineering controls. The engineering controls that are required by
the standard can be grouped into four categories: (1) Substitution; (2)
isolation; (3) ventilation; and (4) dust suppression. Depending on the
sources of crystalline silica dust and the operations conducted, a
combination of control methods may reduce silica exposure levels more
effectively than a single method.
Substitution refers to the replacement of a toxic material with
another material that reduces or eliminates the harmful exposure. OSHA
considers substitution to be an ideal control measure if it replaces a
toxic material in the work environment with a non-toxic material, thus
eliminating the risk of adverse health effects.
As indicated in Chapter IV of the Final Economic Analysis and Final
Regulatory Flexibility Analysis (FEA), employers use substitutes for
crystalline silica in a variety of operations. For example, some
employers use substitutes in abrasive blasting operations, repair and
replacement of refractory materials, operations performed in foundries,
and in the railroad transportation industry. Commenters, such as NIOSH,
John Adams, Vice President of the American Federation of Government
Employees Local 2778, Kyle Roberts, and the National Automobile Dealers
Association (NADA) also identified several situations where substitute
materials and products were available or used in place of silica-
containing products, including: The use of plastic curbs in place of
concrete curbs to repair a highway overpass; the use of materials
containing aluminum oxide instead of crystalline silica in dental labs;
the use of aluminum pellets instead of sand in hydraulic fracturing
operations; the availability of silica-free OEM and auto-refinish paint
systems; and the availability of silica-free body fillers and silica-
free abrasives for auto body repair work (Document ID 1763, p. 2; 1800,
p. 5; 2177, Attachment B, pp. 37-38; 2358, p. 4).
Commenters also identified many situations where no substitute
materials and products were available to replace silica-containing
materials and products. For example, Grede Holdings and AFS noted that
there were no substitutes for sand for most foundry applications
(Document ID 2298, p. 2; 2379, Appendix 1, pp. 14-16; 3486, p. 4). The
General Contractors Association of New York, ASA, CISC, and NAHB noted
that the construction industry cannot select alternate materials to
avoid silica exposure, since nearly all construction materials and
products contain silica (Document ID 2187, p. 6; 2314, pp. 1-2; 2296,
pp. 7, 35; 2319, pp. 93-34). AAR and the American Short Line and
Regional Railroad Association noted that substitute ballast materials
with lower silica content cannot be used because they introduce safety
hazards for employees and the public (Document ID 2366, pp. 5-6). GANA
and NAIMA noted that silica is indispensable to the flat glass industry
(Document ID 2215, p. 5; 2348, Attachment 1, pp. 8-10). NAM noted that
viable alternatives of lower silica content are not available for some
products made by their members (Document ID 3581, Tr. 1728). The
Porcelain Enamel Institute noted that there are no proven replacements
for mill-added crystalline silica for wet-applied enamel systems, given
that the technical advantages offered by silica cannot be practically
and economically achieved with other materials (Document ID 2281, p.
3).
The American College of Occupational and Environmental Medicine
(ACOEM), the Mount Sinai-Irving J. Selikoff Centers for Occupational
and Environmental Medicine, and Samantha Gouveia urged OSHA to more
explicitly encourage the use of substitution where feasible (Document
ID 1771, p. 1; 2080, pp. 4-5; 2208).
Commenters also expressed concerns about the safety of substitutes
(Document ID 2080, pp. 4-5; 2187, p. 6; 2278, pp. 3-4). ACOEM suggested
that OSHA only endorse the use of substitutes when they have been
demonstrated to be safe in short- and long-term inhalation toxicology
studies and urged OSHA to request that NIOSH conduct a periodic
assessment that evaluates substitutes to determine which ones have been
found to be safe based upon results of inhalation toxicity and
epidemiologic studies (Document ID 2080, pp. 4-5). Dr. George
Gruetzmacher, an industrial hygiene engineer, urged OSHA to encourage
the use of alternative materials to silica when feasible, but only when
the substitute has been demonstrated to be safe in short- and long-term
inhalation toxicology studies or to prohibit the substitution of
materials which have not been demonstrated to be less toxic by
inhalation (Document ID 2278, pp. 3-4).
While OSHA finds that substitution can be an ideal control measure
in certain circumstances, the Agency recognizes that this approach may
not be feasible or safer in many others. Because some alternatives to
silica or silica-containing materials may present health risks, OSHA is
not implying that any particular alternative is an appropriate or safe
substitute for silica. In its technological feasibility analyses, the
Agency identified information about situations where substitution may
be an available control strategy. OSHA strongly encourages employers to
thoroughly evaluate potential alternatives, where available, to
determine if a substitute can mitigate employees' exposure to
respirable crystalline silica without posing a greater or new
significant hazard to employees. Additionally, when substituting,
employers must comply with Section 5(a)(1) of the OSH Act (29 U.S.C.
654(a)(1)), which prohibits occupational exposure to "recognized
hazards that are causing or are likely to cause death or serious
physical harm," and with applicable occupational safety and health
standards. For example, with respect to chemical hazards, OSHA's hazard
communication standard imposes specific requirements for employee
training, safety data sheets, and labeling (see 29 CFR 1910.1200).
Isolation, i.e., separating workers from the source of the hazard,
is another effective engineering control employed to reduce exposures
to crystalline silica. Isolation can be accomplished by either
containing the hazard or isolating workers from the source of the
hazard. For example, to contain the hazard, an employer might install a
physical barrier around the source of exposure to contain a toxic
substance within the barrier. Isolating the source of a hazard within
an enclosure restricts respirable dust from spreading throughout a
workplace and exposing employees who are not directly involved in dust-
generating operations. Or, alternatively, an employer might isolate
employees from the hazard source by placing them in a properly
ventilated cab or at some distance from the source of the respirable
crystalline silica exposure.
Ventilation is another engineering control method used to minimize
airborne concentrations of a contaminant by supplying or exhausting
air. Two types of systems are commonly used: Local exhaust ventilation
(LEV) and dilution ventilation. LEV is used to remove an air
contaminant by capturing it at or near the source of emission, before
the contaminant spreads throughout the workplace. Dilution ventilation
allows the contaminant to spread over the work area but dilutes it by
circulating large quantities of air into and out of the area.
Consistent with past recommendations such as those included in the
chromium (VI) standard, OSHA prefers the use of LEV systems to control
airborne toxics because, if designed properly, they efficiently remove
contaminants and provide for cleaner and safer work environments.
Dust suppression methods are generally effective in controlling
respirable crystalline silica dust, and they can be applied to many
different operations such as material handling, rock crushing, abrasive
blasting, and operation of heavy equipment (Document ID 1147). Dust
suppression can be accomplished by one of three systems: Wet dust
suppression, in which a liquid or foam is applied to the surface of the
dust-generating material; airborne capture, in which moisture is
dispensed into a dust cloud, collides with particles, and causes them
to drop from the air; and stabilization, which holds down dust
particles by physical or chemical means (lignosulfonate, calcium
chloride, and magnesium chloride are examples of stabilizers).
The most common dust suppression controls are wet methods (see
Chapter IV of the FEA). Water is generally an inexpensive and readily
available resource and has been proven an efficient engineering control
method to reduce exposures to airborne crystalline silica-containing
dust. Dust, when wet, is less able to become or remain airborne.
Work practice controls. Work practice controls systematically
modify how employees perform an operation, and often involve employees'
use of engineering controls. For crystalline silica exposures, OSHA's
technological feasibility analysis shows that work practice controls
are generally applied complementary to engineering controls, to adjust
the way a task is performed (see Chapter IV of the FEA). For work
practice controls to be most effective, it is essential that employees
and supervisors are trained to be fully aware of the exposures
generated by relevant workplace activities and the impact of the
engineering controls installed. Work practice controls are preferred
over the use of personal protective equipment, since work practice
controls can address the exposure of silica at the source of emissions,
thus protecting nearby employees.
Work practice controls can also enhance the effects of engineering
controls. For example, to ensure that LEV is working effectively, an
employee would position the LEV equipment so that it captures the full
range of dust created, thus minimizing silica exposures. For many
operations, a combination of engineering and work practice controls
reduces silica exposure levels more effectively than a single control
method.
The requirement to use engineering and work practice controls is
consistent with ASTM E 1132-06 and ASTM E 2625-09, the national
consensus standards for controlling occupational exposure to respirable
crystalline silica in general industry and in construction,
respectively. Each of these standards has explicit requirements for the
methods of compliance to be used to reduce exposures below exposure
limits. These voluntary standards specifically identify several
controls, which include use of properly designed engineering controls
such as ventilation or other dust suppression methods and enclosed
workstations such as control booths and equipment cabs; requirements
for maintenance and evaluation of engineering controls; and
implementation of certain work practices such as not working in areas
where visible dust is generated from respirable crystalline silica
containing materials without use of respiratory protection. For
employers in general industry and maritime, as well as those in
construction following paragraph (d) for tasks not listed in Table 1 or
where the employer does not fully and properly implement the
engineering controls, work practices, and respiratory protection
described in Table 1, OSHA similarly requires the use of engineering
and work practices controls to reduce employee exposures to or below
the PEL; however, this is a performance requirement and does not
specify any particular engineering and work practice controls that must
be implemented.
Paragraph (f)(2)(i) of the standard for general industry and
maritime (paragraph (g)(1) of the standard for construction) requires
that employers establish and implement a written exposure control plan.
Paragraphs (f)(2)(i)(A)-(C) (paragraphs (g)(1)(i)-(iv) of the standard
for construction) specify the contents for written exposure control
plans. Paragraph (f)(2)(ii) (paragraph (g)(2) of the standard for
construction) specifies requirements for the employer to review the
plan at least annually and update it as needed. Paragraph (f)(2)(iii)
(paragraph (g)(3) of the standard for construction) requires the
employer to make the plan available to employees, employee
representatives, OSHA, and NIOSH. Details about the written exposure
control plan, including comments from stakeholders and OSHA's responses
to those comments, are included in the summary and explanation of
Written Exposure Control Plan.
SECALs. In the NPRM, OSHA asked stakeholders to provide input as to
whether the Agency should establish separate engineering control air
limits (SECALs) for certain processes in selected industries. In OSHA's
cadmium standard (29 CFR 1910.1027 (f)(1)(ii), (iii), and (iv)), the
Agency established SECALs where compliance with the PEL by means of
engineering and work practice controls was infeasible. For these
industries, a SECAL was established at the lowest feasible level that
could be achieved by engineering and work practice controls. The PEL
was set at a lower level, and could be achieved by any allowable
combination of controls, including respiratory protection. A similar
exception was included in OSHA's chromium (VI) standard (29 CFR
1910.1026) for painting aircraft and large aircraft parts.
OSHA received feedback from several commenters who supported
establishing SECALs (e.g., Document ID 2082, p. 8; 2379, Appendix 1, p.
61; 2380, Attachment 2, p. 23). For example, AFS argued for a SECAL of
150 or 200 [mu]g/m\3\ for foundries, with a PEL of 100 [mu]g/m\3\. AFS
indicated that many foundries now operate under a formal or informal
arrangement with OSHA that allows use of respirators as an acceptable
control to achieve compliance with the current PEL after implementing
all feasible engineering controls (Document ID 2379, Appendix 1, p.
61). ORCHSE Strategies stated that the use of SECALs could provide more
definitive expectations for employers based on the feasibility for
engineering controls in specific operations (Document ID 2277, p. 2).
The United Automobile, Aerospace and Agricultural Implement Workers of
America recommended that the PEL be even lower than OSHA proposed (25
[mu]g/m\3\), and suggested that SECALs could be established for those
industries for which 25 [mu]g/m\3\ is not feasible (Document ID 2282,
p. 16).
Other commenters did not favor establishing SECALs. CISC stated
that it did not support the concept of SECALs, but that CISC would
continue to examine whether a SECAL was appropriate for the
construction industry (Document ID 2319, p. 128). NIOSH did not support
the use of SECALs and stated that the requirement to meet the PEL for
silica generating processes should be maintained (Document ID 2177,
Attachment B, p. 16).
OSHA stresses that, where incorporated in a standard, a SECAL is
intended for application to discrete processes and operations within an
industry, rather than application to an entire industry, as some
supporters of SECALs seemed to suggest. For example, in OSHA's cadmium
standard, OSHA established SECALs for certain plating and other
processes in a few affected industries. OSHA did not receive evidence
to support establishing a SECAL for any discrete task or operation
within a particular industry in the respirable crystalline silica rule.
OSHA therefore has not established SECALs in the rule.
Abrasive blasting. Abrasive blasting requirements remain the same
as proposed, except for minor editorial changes. Paragraph (f)(3) of
the standard for general industry and maritime (paragraph (d)(3)(ii) of
the standard for construction) requires the employer to comply with
paragraph (f)(1) of the standard for general industry and maritime
(paragraph (d)(3)(i) of the standard for construction) where abrasive
blasting is conducted using crystalline silica-containing blasting
agents, or where abrasive blasting is conducted on substrates that
contain crystalline silica. Thus, for abrasive blasting, employers must
follow the hierarchy of controls applicable to other tasks covered by
the rule.
In this provision addressing abrasive blasting, the proposed
standard referred to "where abrasive operations are conducted," but
for simplicity, this standard refers to "where abrasive blasting is
conducted." OSHA intends this change to be editorial only, and does
not intend a substantive change from the proposed requirements.
In addition, paragraph (f)(3) of the standard for general industry
and maritime indicates that the employer must comply with the
requirements of 29 CFR 1910.94 (Ventilation), 29 CFR 1915.34
(Mechanical paint removers) and 29 CFR 1915 Subpart I, as applicable,
where abrasive blasting is conducted using crystalline silica-
containing blasting agents, or where abrasive blasting is conducted on
substrates that contain crystalline silica. Paragraph (d)(3)(ii) of the
standard for construction indicates that the employer must comply with
the requirements of 29 CFR 1926.57 (Ventilation) in such circumstances.
OSHA's general industry (29 CFR 1910.94) and construction
ventilation standards (29 CFR 1926.57), as well as the standards for
mechanical paint removers (29 CFR 1915.34) and personal protective
equipment for shipyard employment (29 CFR 1915 subpart I) provide
requirements for respiratory protection for abrasive blasting operators
and others involved in abrasive blasting. This rule includes cross-
references to these standards. Employers using abrasive blasting need
to consult these referenced standards to ensure that they comply with
their provisions for personal protective equipment and ventilation, and
other operation-specific safety requirements.
ISEA urged OSHA to add a reference to the APF table at 29 CFR
1910.134(d)(3)(i)(A) in the general industry and construction standards
for ventilation, and to require that if the employer has no sampling
data to support the use of an abrasive blasting respirator with an APF
of 25, the employer must select a respirator with an APF of 1,000
(Document ID 2212, p. 1). The 3M Company similarly questioned the
respirator requirements under the ventilation standards, arguing that
without considering the performance (APF) of the respirator, some
employees could be overexposed to silica (Document ID 2313, pp. 1, 5-
6). Charles Gordon, a retired occupational safety and health attorney,
commented that even with the reference to the ventilation standards,
the provision is not protective enough. He encouraged the Agency to
require the most protective abrasive blasting hood and respirators and
require the best work practices (Document ID 2163, Attachment 1, p.
19).
Given the high levels of hazardous dust generated during abrasive
blasting, OSHA has concluded, for reasons discussed in its
technological feasibility analyses for construction and for certain
general industry sectors like foundries and shipyards that perform
abrasive blasting in their operations, that respiratory protection will
continue to be necessary to reduce silica exposure below the PEL, even
with engineering and work practice controls in place (see the
discussion of abrasive blasting in Chapter IV of the FEA). This
standard also takes respirator use into account by cross-referencing
the specific respirator requirements already in place for abrasive
blasting. Employers are also required to comply with the requirements
of 29 CFR 1910.134 whenever respiratory protection is required by this
section. Under 29 CFR 1910.134, the employer is required to select and
provide an appropriate respirator based on the respiratory hazards to
which the employee is exposed and is required to use the APF table at
29 CFR 1910.134(d)(3)(i)(A). This includes note four of the APF table,
which requires the employer to have evidence to support an APF of 1000
for helmet/hood respirators. In addition, paragraph (d) of the standard
for general industry and maritime and paragraph (d)(2) of the standard
for construction require employers to assess the exposure of each
employee who is or may reasonably be expected to be exposed to
respirable crystalline silica at or above the action level, which will
provide employers with information to make appropriate respirator
selection decisions. OSHA concludes that these requirements, including
the referenced provisions in other OSHA standards, will adequately
protect employees from exposures to respirable crystalline silica
during abrasive blasting.
Many commenters, including NIOSH, labor unions, public health
organizations, trade associations, occupational health medical
professionals, and public interest organizations, urged OSHA to ban the
use of silica sand as an abrasive blasting agent (Document ID 2167;
2173, p. 4; 2175, pp. 7-8; 2177, Attachment B, p. 37; 2178, Attachment
1, p. 3; 2212, p. 1; 2240, p. 2; 2244, p. 2; 2256, Attachment 2, pp.
12-13; 2282, Attachment 3, pp. 2, 18; 2341, p. 3; 2371, Attachment 1,
p. 31; 2373, p. 3; 3399, p. 6; 3403, p. 7; 3577, Tr. 779-780, 785, 790;
3586, Tr. 3319-3320, 3163; 3588, Tr. 3752; 4204, p. 81; 4223, pp. 104-
106). Some noted that 4 countries (Great Britain, Germany, Sweden, and
Belgium), several U.S. military departments, and 23 state Departments
of Transportation have already banned the practice (Document ID 2167;
2175, pp. 7-8; 2178, Attachment 1, p. 3; 2256, Attachment 2, pp. 12-13;
2212, p. 1; 2282, Attachment 3, p. 18; 2371, Attachment 1, p. 31; 2373,
p. 3; 3399, p. 6; 4204, p. 76).
Fann Contracting, Dr. Kenneth Rosenman, an expert in occupational
and environmental disease, and Novetas Solutions noted the broad trend
of abrasive blasting operations moving away from sand (Document ID
2116, Attachment 1, pp. 31-32; 3577, Tr. 858; 3588, Tr. 3992-3993). The
American Federation of State, County and Municipal Employees reported
that several local Maryland unions no longer use silica-based blasting
agents and have substituted other materials, such as aluminum shot
(Document ID 2106, p. 2). Sarah Coyne, a former painter and current
Health and Safety Director for IUPAT, discussed how their signatory
contractors have largely transitioned from silica sand to coal slag for
abrasive blasting (Document ID 3581, Tr. 1644). API noted that many oil
and gas companies have limited or eliminated respirable crystalline
silica exposure in sandblasting operations by using media options that
do not contain silica (Document ID 2301, Attachment 1, p. 5). NADA also
noted that product substitution has minimized potential exposures to
airborne crystalline silica-containing media (Document ID 2358, p. 4).
The Interstate Natural Gas Association of America stated that members
utilize other abrasives to the extent feasible, including fused glass
in limited applications (Document ID 2081, p. 2).
As OSHA indicated in its NPRM, the use of silica sand for abrasive
blasting operations is decreasing (Document ID 1420). This reduction
might reflect the use of alternative blasting media, the increased use
of high-pressure water-jetting techniques, and the use of cleaning
techniques that do not require open sand blasting. Several substitutes
for silica sand are available for abrasive blasting operations, and
current data indicate that the abrasive products with the highest U.S.
consumptions are: Coal slag, copper slag, nickel slag, garnet,
staurolite, olivine, steel grit, and crushed glass. Several commenters
(Adam Webster, Charles Gordon, and the Association of Occupational and
Environmental Clinics) also noted the general availability of
alternative abrasive blast media, including baking soda, water, dry
ice, coal/copper slag, glass beads, walnut shells, and carbon dioxide
(Document ID 2163, p. 19; 2167; 3399, p. 6). Additional alternatives
are discussed and evaluated in Chapter IV of the FEA. On the other
hand, PCI commented that the use of alternative abrasive blast media
was precluded in the precast concrete structures industry, since many
alternatives will not meet aesthetic requirements, are not aggressive
enough to provide the desired finished, or are simply cost prohibitive
(Document ID 2276, p. 9). Furthermore, CISC warned about possible
hazards associated with the substitutes for silica sand (Document ID
2319, p. 37). PCI and Novetas Solutions cautioned that coal and copper
slags, commonly used as a substitute for silica sand in abrasive
blasting, contain hazardous substances such as beryllium that cause
adverse health effects in employees (Document ID 2276, p. 9; 3588, Tr.
3992-4004). Meeker et al. (2006) found elevated levels of exposure to
arsenic, beryllium, and other toxic metals among painters using three
alternative blasting abrasives (Document ID 3855).
A NIOSH study compared the short-term pulmonary toxicity of several
abrasive blasting agents (Document ID 1422). This study reported that
specular hematite and steel grit presented less short-term in vivo
toxicity and respirable dust exposure in comparison to blast sand.
Overall, crushed glass, nickel glass, staurolite, garnet, and copper
slag were similar to blast sand in both categories. Coal slag and
olivine showed more short-term in vivo toxicity than blast sand and
were reported as similar to blast sand regarding respirable dust
exposure. This study did not examine long-term hazards or non-pulmonary
effects.
Additionally, another NIOSH study monitored exposures to several
OSHA-regulated toxic substances that were created by the use of silica
sand and substitute abrasive blasting materials (Document ID 0772). The
study showed that several substitutes create exposures or potential
exposures to various OSHA-regulated substances, including: (1) Arsenic,
when using steel grit, nickel slag, copper slag and coal slag; (2)
beryllium, when using garnet, copper slag, and coal slag; (3) cadmium,
when using nickel slag and copper slag; (4) chromium, when using steel
grit, nickel slag, and copper slag; and (5) lead, when using copper
slag. Since these studies were performed, OSHA has learned that
specular hematite is not being manufactured in the United States due to
patent-owner specification. In addition, the elevated cost of steel has
a substantial impact on the availability to some employers of
substitutes like steel grit and steel shot.
Evidence in the rulemaking record indicates that elevated silica
exposures have been found during the use of low-silica abrasives as
well, even when blasting on non-silica substrates. For example, the use
of the blasting media Starblast XL (staurolite), which contains less
than one percent quartz according to its manufacturer, resulted in a
respirable quartz level of 1,580 [mu]g/m\3\. The area sample (369-
minute) was taken inside a containment structure erected around two
steel tanks. The elevated exposure occurred because the high levels of
abrasive generated during blasting in containment overwhelmed the
ventilation system (Document ID 0212). This example emphasizes the
impact of control methods in specific working environments. In order to
reduce elevated exposures to or as close as feasible to the PEL in
situations like these, employers need to examine the full spectrum of
available controls and how these controls perform in specific working
conditions.
After considering the arguments for and against prohibition, OSHA
concludes that prohibiting the use of silica sand as an abrasive
blasting agent is not appropriate. In so concluding, the Agency
considered whether such a prohibition is an effective risk mitigation
measure, as well as the technological feasibility of substitutes. The
Agency finds that many of the silica sand substitutes used in abrasive
blasting can create hazardous levels of toxic dust other than silica,
as documented in studies conducted by NIOSH on the toxicity of silica
sand substitutes for abrasive blasting; NIOSH found that many,
including coal slag, garnet, copper and nickel slags, olivine, and
crushed glass, produced lung damage and inflammatory reactions in
rodent lung similar to that of silica sand, indicating that use of such
materials would present lung disease risks to employees (Document ID
3857; 3859). OSHA further finds that additional toxicity data are
necessary before the Agency can reach any conclusions about the hazards
of these substitutes relative to the hazards of silica. Given the
concerns about potential harmful exposures to other substances that the
alternatives might introduce in a workplace, as well as the potential
for continued exposure to respirable crystalline silica, OSHA concludes
that banning the use of silica sand as an abrasive blasting agent would
not necessarily effectively mitigate risk. OSHA also concludes, as
detailed in the FEA, that the general prohibition of silica sand in
abrasive blasting is not technologically or economically feasible.
Thus, the Agency has decided against a ban or limitation on the use of
silica sand as an abrasive blasting agent in the rule.
BCTD urged OSHA to ban the use of silica sand as an abrasive
blasting agent, but said that if banning the use of silica sand as an
abrasive blasting agent was not possible, OSHA should prohibit the use
of dry silica sand as an abrasive blasting agent (Document ID 2371,
Attachment 1, p. 31). However, PCI noted that wet blasting with silica
sand cannot be used to finish concrete surfaces (Document ID 2276, p.
9). CISC noted the problems associated with excessive water application
on some worksites and argued that different environments and conditions
had not been analyzed to determine the effectiveness of wet methods for
abrasive blasting (Document ID 2319, p. 36).
OSHA finds that a separate requirement for the use of wet blasting
methods when silica sand is used as a blasting agent is neither
necessary nor appropriate. Under paragraph (f)(1) of the standard for
general industry and maritime (paragraph (d)(3)(i) of the standard for
construction), employers are required to use engineering and work
practice controls, which include wet methods, to reduce and maintain
employee exposure to respirable crystalline silica at or below the PEL,
unless the employer can demonstrate that such controls are not
feasible. Therefore, where employee exposures exceed the PEL from
abrasive blasting with silica sand, employers must implement wet
blasting methods whenever such methods are feasible and would reduce
exposures, even if implementing this control does not reduce exposures
to or below the PEL. By not specifically mandating the use of wet
methods whenever sand is used as a blasting agent, the rule gives
employers who cannot feasibly use wet methods flexibility to determine
what controls to implement in order with comply with the PEL.
Charles Gordon argued for a partial ban on the use of silica sand
as an abrasive blasting agent:
Abrasive blasting with crystalline silica should be banned in
confined spaces and in the maritime industry. That is where acute
silicosis was most common and where it is hardest to protect
adjacent workers.
In all other areas and operations, the employer must consult
MSDS's for substitutes for crystalline silica. If it is reasonable
to conclude that a substitute for crystalline silica is a safer
blasting media and will lead to a reasonable surface, then the
employer must adopt the substitute. If the employer concludes that
there is no safer reasonable substitute for crystalline silica, then
the employer must keep a brief written record of that determination
(Document ID 2163, Attachment 1, pp. 18-19).
While OSHA has declined to ban abrasive blasting with crystalline
silica in any setting, the Agency considers that the process of
selecting, evaluating, and adopting safer blasting agent substitutes
where feasible, is consistent with the analysis required under
paragraph (f)(1) of the standard for general industry and maritime
(paragraph (d)(3)(i) of the standard for construction). As part of
complying with this paragraph, employers must consider whether
substitutes for crystalline silica abrasive blasting agents are
available. Safer, effective, and feasible substitutes, where available,
should be included as part of the package of feasible engineering and
work practice controls required to reduce employee exposure to
respirable crystalline silica to or below the PEL. The Agency expects
that the requirements in the rule will incentivize employer evaluation
and adoption of substitute materials where substitution is appropriate
for the task and shown to be safe, while avoiding substitutions that
pose comparable or greater risk and maintaining flexibility for employers
to determine what controls to implement in order to comply with the PEL.
CISC questioned the application of the hierarchy of controls to
abrasive blasting, given the Agency's acknowledgement that respiratory
protection will still be necessary in many situations even after
implementing engineering and work practice controls (Document ID 2319,
p. 37). As discussed above, the Agency maintains its position that
adherence to the hierarchy of controls, which includes, where
appropriate and feasible, substitutes for silica sand, wet blasting,
LEV, proper work practices and housekeeping practices that reduce dust
emissions, is essential to help reduce the extremely high exposures to
respirable crystalline silica experienced by abrasive blasting workers
and workers who may be near them. The FEA describes how extremely high
exposures associated with dry abrasive blasting were significantly
reduced where controls, such as wet blasting and non-silica containing
abrasive blast media, were used (see Chapter IV of the FEA for further
discussion). By using engineering controls to reduce these exposures,
employees will be able to wear less restrictive respirators and will be
better protected if their respiratory protection fails. Engineering
controls also help protect others on the worksite from exposure to
respirable crystalline silica. Therefore, requiring the use of
controls, even where respiratory protection will also be required, is
reasonably necessary and appropriate to protect employees from
exposures to respirable crystalline silica.
The requirements in the rule for abrasive blasting are consistent
with ASTM E 1132--06 and ASTM E 2625--09, the national consensus
standards for controlling occupational exposure to respirable
crystalline silica in general industry and in construction,
respectively. Each of these standards clarifies that the hierarchy of
controls (i.e., using alternative materials, wet suppression systems,
or exhaust ventilation, where feasible, to reduce exposures) applies to
abrasive blasting and refers to the existing requirements under OSHA's
ventilation standards (29 CFR 1910.94 and 29 CFR 1926.57).
Employee rotation. OSHA proposed, but is not including in the final
rule, a provision specifying that the employer must not rotate
employees to different jobs to achieve compliance with the PEL. The
Agency proposed this prohibition because silica is a carcinogen, and
OSHA considers that any level of exposure to a carcinogen places an
employee at risk. With employee rotation, the population of exposed
employees increases. A prohibition on rotation has been included in
other OSHA health standards that address carcinogens, such as the
standards for asbestos (29 CFR 1910.1001), chromium (VI) (29 CR
1910.1026), 1,3-butadiene (29 CFR 1910.1051), methylene chloride (29
CFR 1910.1052), cadmium (29 CFR 1910.1027), and methylenedianiline (29
CFR 1910.1050). However, other standards addressing chemicals that were
associated with non-cancer health effects, such as the standards for
lead and cotton dust (29 CFR 1910.1025 and 29 CFR 1910.1043), do not
include a prohibition on employee rotation to achieve the PEL. In
response to a recommendation by the Small Business Advocacy Review
Panel, OSHA solicited comment in the NPRM on the prohibition of
employee rotation to achieve compliance with the PEL (78 FR 56273,
56290 (9/12/13)).
A prohibition on employee rotation to achieve compliance with the
PEL was supported by EEI, Dr. George Gruetzmacher, and James Schultz
(Document ID 2278, p. 4; 2357, p. 30; 3586, Tr. 3200). However, many
commenters representing employers from the concrete, brick, tile,
construction, electric utility, and foundry industries, over 20 trade
associations, ASSE, and academics from the George Washington University
Regulatory Studies Center urged OSHA to reconsider this prohibition
(e.g., Document ID 1785, p. 8; 1831, p. 15; 1992, p. 11; 2023, p. 7;
2024, p. 3; 2075, p. 3; 2102, p. 2; 2116, Attachment 1, pp. 34-35;
2119, Attachment 3, p. 7; 2145, pp. 5-6; 2147, p. 4; 2150, p. 2; 2154,
Attachment 3, p. 7; 2185, pp. 6-7; 2195, p. 39; 2213, p. 4; 2215, p.
11; 2222, p. 2; 2241, p. 2; 2245, p. 3; 2255, p. 3; 2276, p. 10; 2279,
p. 10; 2288, p. 12; 2296, p. 42; 2305, pp. 11, 15; 2309, p. 3; 2322, p.
14; 2326, p. 3; 2339, p. 4; 2348, Attachment 1, p. 36; 2355, p. 2;
2359, Attachment 1, p. 11; 2370, p. 2; 2379, Appendix 1, p. 69; 2380,
Attachment 2, p. 21; 2384, p. 10; 2391, p. 2; 3245, p. 2; 3275, p. 2;
3489, p. 4; 3491, p. 4; 3578, Tr. 1035-1036, 1044; 3729, p. 3; 4194, p.
12; 4213, p. 7; 4226, p. 2).
Some commenters misunderstood the prohibition on employee rotation
to achieve compliance with the PEL, or believed that the provision
could be misunderstood by the regulated community. These commenters
were concerned that the prohibition would preclude the use of rotation
for other reasons, such as limiting exposure to physical hazards (e.g.,
noise, vibration, repetitive motion stresses), providing cross-
training, improving productivity, preventing fatigue, and filling in
for other employees. OSHA explained in the NPRM that the proposed
provision was not intended as a general prohibition on employee
rotation. However, commenters including National Electrical Carbon
Products, OSCO, the Ohio Cast Metals Association, PCI, and AFS
expressed concerns that using employee rotation for these other reasons
could be misinterpreted as a violation of the prohibition (e.g.,
Document ID 1785, p. 8; 1992, p. 11; 2119, Attachment 3, p. 7; 2276, p.
10; 3489, p. 4;). NISA also asked the Agency to clarify that rotation
may be performed for purposes other than achieving compliance with the
PEL (Document ID 2195, p. 39).
NISA and the Chamber argued that if the risks of silicosis are
subject to a threshold, then rotation to maintain exposures at low
levels could only be protective (Document ID 2195, p. 39; 2288, p. 12;
4194, p. 12). ASSE argued that job rotation may be warranted as an
alternative to burdensome engineering and administrative controls or
PPE for tasks that involve some levels of exposure to silica, but are
performed on an infrequent basis (Document ID 2339, p. 4; 3578, Tr.
1035-1036, 1044). ASSE, as well as Dal-Tile, noted that since silica is
a ubiquitous substance and present in many raw materials, virtually all
employees would be exposed to some level of respirable crystalline
silica. Therefore, they argued that a prohibition on rotation in this
circumstance does not make sense (Document ID 2147, p. 4; 2339, p. 4).
In addition, AFS indicated that rotation as an administrative control
is permitted by Canadian provinces with exposure limits for respirable
crystalline silica (Document ID 4035, p. 14). OSHA also notes that the
industry consensus standards for respirable crystalline silica, ASTM E
1132-06 and ASTM E 2625-09, expressly permit employee rotation as an
administrative control to limit exposures (Document ID 1466, p. 4;
1504, pp. 3, 7).
OSHA does not consider employee rotation to be an acceptable
alternative to avoid the costs associated with implementation of
engineering and administrative controls, nor does the Agency consider
that pervasive exposures to respirable crystalline silica justify
allowing rotation. OSHA has nonetheless concluded that there may be
situations where employee rotation may be an acceptable measure to
limit the need for respiratory protection. For example, OSHA has
determined that the majority of employers covered by the rule will be
in construction, and expects that most construction employers will
implement the controls listed on Table 1 in paragraph (c) of the
standard for construction. A number of tasks listed on Table 1 require
respiratory protection, in addition to engineering and work practice
controls, when performed for more than four hours per shift. Where the
employer has implemented the engineering and work practice controls
specified in Table 1, OSHA accepts the rationale that it may be
reasonable to rotate employees to avoid exceeding the four-hour
threshold that would trigger a requirement for respirator use. As
discussed earlier in this section, respirator use can restrict visibility,
impair communication, contribute to heat stress, strain the respiratory
and cardiac systems, and exacerbate other safety and health hazards, such
as trip and fall hazards. Under such circumstances, rotation of employees
to limit use of respiratory protection may serve to reduce overall risks
to employees. Rotation may also allow employees to continue to work if
they are unable to pass the medical evaluation for respirator use, but
are otherwise capable of performing the work.
OSHA also recognizes that a provision prohibiting employee rotation
to achieve the PEL has little practical application for purposes of
enforcement. Because the prohibition is limited to rotation for the
sole purpose of achieving the PEL, an employer can provide any other
reason to justify employee rotation. As described above, there are many
legitimate reasons for an employer to rotate employees. As a result,
OSHA has almost never cited employers for violating provisions
prohibiting employee rotation for achieving the PEL. For the 7
standards that contain these provisions, which have been in effect for
periods ranging from 8 to 29 years, Federal OSHA has only cited one of
these provisions on one occasion.
For the reasons described above, OSHA has determined that a
prohibition on employee rotation to achieve the PEL is not reasonably
necessary or appropriate for the silica rule. The Agency recognizes
that this determination differs from the determinations made in
previous rulemakings addressing carcinogens. This is not intended as a
reversal of OSHA's prior practice of prohibiting employee rotation to
achieve the PEL for carcinogens, nor a precedent that will control
future rulemakings, which necessarily will be based on different
rulemaking records. Nevertheless, in this rule OSHA expects that the
majority of employers covered by the rule will implement all feasible
engineering and work practice controls to achieve the PEL (as the rule
requires), and rotation will generally be used to limit use of
respiratory protection that is triggered by working more than four
hours in conditions where exposures are expected above the PEL even
with the full implementation of engineering and work practice controls.
OSHA finds that these factors justify omitting the prohibition on
rotation from this rule. Therefore, the prohibition, which was included
in the proposed rule, is not included in the final rule.
Respiratory Protection
Paragraph (g) of the standard for general industry and maritime
(paragraph (e) of the standard for construction) establishes
requirements for the use of respiratory protection, to which OSHA's
respiratory protection standard (29 CFR 1910.134) also applies.
Specifically, respirators are required under the rule: Where exposures
exceed the PEL during periods necessary to install or implement
engineering and work practice controls; where exposures exceed the PEL
during tasks, such as certain maintenance and repair tasks, for which
engineering and work practice controls are not feasible; and during
tasks for which all feasible engineering and work practice controls
have been implemented but are not sufficient to reduce exposure to or
below the PEL. The standard for general industry and maritime also
requires respiratory protection during periods when an employee is in a
regulated area. The standard for construction also requires respiratory
protection where specified by Table 1 of paragraph (c), but does not
include a requirement to establish a regulated area, and thus does not
contain a provision requiring the use of respirators in regulated
areas.
These provisions of the rule for the required use of respirators
are consistent with those proposed and are generally consistent with
other OSHA health standards, such as methylene chloride (29 CFR
1910.1052) and chromium (VI) (29 CFR 1910.1026). They reflect the
Agency's determination that, as discussed in the summary and
explanation of Methods of Compliance, respirators are inherently less
reliable than engineering and work practice controls in reducing
employee exposure to respirable crystalline silica. OSHA therefore is
allowing reliance on respirators to protect against exposure to
respirable crystalline silica only in specific circumstances where
engineering and work practice controls are in the process of being
installed or implemented (and thus are not yet fully operational), are
not feasible, or cannot by themselves reduce exposures to the PEL. In
those circumstances, OSHA's hierarchy of controls contemplates
requiring the use of respirators as a necessary supplement to
engineering, work practice, and administrative controls.
Paragraph (e)(1) of the standard for construction is revised from
the proposed standard in order to clarify where respiratory protection
is required. Paragraph (e)(1)(i) of the standard for construction
provides that, for employers following the specified exposure control
methods approach set forth in paragraph (c) of the standard for
construction, respiratory protection is required under the standard
where specified by Table 1. Table 1 in paragraph (c) of the standard
for construction specifies respirator use for certain listed tasks;
employers whose employees are engaged in those tasks have the option of
following Table 1 in order to comply with the standard. The specific
respiratory protection and minimum assigned protection factors (APF)
for the tasks listed on Table 1 are discussed in the summary and
explanation of Specified Exposure Control Methods. Paragraph (e)(1)(ii)
of the standard for construction establishes where respirators are
required for employees who are not performing tasks listed on Table 1
or where the engineering controls, work practices, and respiratory
protection described in Table 1 are not fully and properly implemented
(including where the employer chooses to follow paragraph (d) rather
than follow paragraph (c)). Specifically, respirators are required in
each of the situations described in paragraphs (e)(1)(ii)(A)-(C).
Paragraph (g)(1)(i) of the standard for general industry and
maritime (paragraph (e)(1)(ii)(A) of the standard for construction)
requires the use of respirators in areas where exposures exceed the PEL
during periods when feasible engineering and work practice controls are
being installed or implemented. OSHA recognizes that respirators may be
needed to achieve the PEL under these circumstances. During these
times, employees will have to use respirators for temporary protection
until the hierarchy of controls has been implemented, at which point
respirators will not be needed, provided the PEL is no longer exceeded.
Employers must follow the requirements for exposure assessment (see the
summary and explanation of Exposure Assessment) to determine the extent
of employee exposures once engineering and work practice controls are
installed or implemented. While there is not an established time for
exposure assessments to occur after the installation or implementation
of controls, employers are required to reassess exposures whenever a
change in control equipment may reasonably be expected to result in new
or additional exposures above the action level. Employers must also
ensure that employee exposures are accurately characterized, so they
would need to reassess exposures after the installation or
implementation of controls in order to meet this obligation.
OSHA anticipates that engineering controls will be in place by the
dates specified in paragraphs (l)(2) and (l)(3) of the general industry
and maritime standard (paragraph (k)(2) of the standard for
construction) (see the summary and explanation of Dates for discussion
of these requirements). However, the Agency realizes that in some cases
employers may commence operations, install new or modified equipment,
or make other workplace changes that result in new or additional
exposures to respirable crystalline silica after the dates specified.
In these cases, a reasonable amount of time may be needed before
appropriate engineering controls can be installed and proper work
practices implemented. When employee exposures exceed the PEL in these
situations (see the summary and explanation of Exposure Assessment for
an explanation of the requirements to assess employee exposure to
respirable crystalline silica), employers must provide their employees
with respiratory protection and ensure its use.
Paragraph (g)(1)(ii) of the general industry and maritime standard
(paragraph (e)(1)(ii)(B) of the standard for construction) requires
respiratory protection in areas where exposures exceed the PEL during
tasks in which engineering and work practice controls are not feasible.
OSHA anticipates that there will be few situations where no feasible
engineering or work practice controls are available to limit employee
exposure to respirable crystalline silica. However, the Agency
recognizes that it may be infeasible to control respirable crystalline
silica exposure with engineering and work practice controls during
certain tasks, such as maintenance and repair tasks, and permits the
use of respirators in these situations. For example, maintenance and
repair to address temporary failures in operating systems or control
systems to achieve the PEL such as failures of conveyance systems
(elevators, conveyors, or pipes), failures of dust collecting bag
systems, and section head failures at glass plant facilities as well as
cupola (furnace) repair work and baghouse maintenance activities, may
present a situation where engineering and work practice controls are
not feasible and the use of respirators is permitted (Document ID 3493,
p. 3; 1992, pp. 3, 5). In situations where respirators are used as the
only means of protection, the employer must be prepared to demonstrate
that engineering and work practice controls are not feasible.
Paragraph (g)(1)(iii) of the standard for general industry and
maritime (paragraph (e)(1)(ii)(C) of the standard for construction)
requires the use of respirators for supplemental protection in
circumstances where feasible engineering and work practice controls
alone are not sufficient to reduce exposure levels to or below the PEL.
The employer is required to install and implement all feasible
engineering and work practice controls, even if these controls alone
cannot reduce employee exposures to or below the PEL. Whenever
respirators are used as supplemental protection, the burden is on the
employer to demonstrate that engineering and work practice controls
alone are insufficient to achieve the PEL.
Paragraph (g)(1)(iv) of the standard for general industry and
maritime requires employers to provide respiratory protection during
periods when an employee is in a regulated area. Paragraph (e) of the
standard for general industry and maritime requires employers to
establish a regulated area wherever an unprotected employee's exposure
to airborne concentrations of respirable crystalline silica is, or can
reasonably be expected to be, in excess of the PEL. OSHA included the
provision requiring respirator use in regulated areas to make it clear
that each employee is required to wear a respirator when present in a
regulated area, regardless of the duration of time spent in the area.
Because of the potentially serious results of exposure, OSHA has
concluded that this provision is necessary and appropriate because it
would limit unnecessary exposures to employees who enter regulated
areas, even if they are only in a regulated area for a short period of
time. The standard for construction does not include a requirement to
establish a regulated area and thus, does not contain a similar
provision in the respiratory protection section of the standard.
Further discussion about this can be found in the summary and
explanation of Regulated Areas and Written Exposure Control Plan.
OSHA proposed to require the use of respiratory protection when
specified by the written access control plan--an option given to
employers in the proposed rule as an alternative to establishing
regulated areas. The Agency is not including an access control plan
option in the rule (see discussion in the summary and explanation of
Regulated Areas). Thus, without an option for an employer to develop a
written access control plan, there is no reason to require respirators
pursuant to a written access control plan.
Commenters, including Charles Gordon, a retired occupational safety
and health attorney, and the American Industrial Hygiene Association
recommended that OSHA require employers to provide employees with
respirators upon request in certain situations where they are not
required under the rule (e.g., exposures below the PEL, Table 1 tasks
for which respirators are not required) (Document ID 2163, Attachment
1, p. 16; 2169, p. 5). Dr. George Gruetzmacher, an industrial hygiene
engineer, suggested that OSHA require respiratory protection and a
respiratory protection program at the action level (Document ID 2278,
p. 4).
While the Agency considers the level of risk remaining at the PEL
to be significant, OSHA is not including a provision in this rule
permitting employees to request and receive a respirator in situations
where they are not required under the rule, nor is OSHA requiring
respiratory protection and a respiratory protection program at the
action level. There has been significant residual risk below the PEL in
many previous health standards, but OSHA has only rarely included
provisions permitting employees to request and receive a respirator to
mitigate this risk (cotton dust (29 CFR 1910.1043(f)(1)(v)), lead (29
CFR 1910.1025(f)(1)(iii)), cadmium (29 CFR 1910.1027(g)(1)(v))) and the
Agency has never established a requirement for respiratory protection
and a respiratory protection program at a standard's action level.
OSHA anticipates that most construction employers covered by the
rule will choose to implement the control measures specified in
paragraph (c) of the standard for construction. Employers who implement
the specified exposure control methods will not be required to assess
employee exposures to respirable crystalline silica. Therefore, many
employers covered by the rule will not be aware if their employees are
exposed to respirable crystalline silica at or above the action level.
In order to impose a requirement for employers to provide respirators to
employees exposed at or above the action level, OSHA would first need to
require employers to assess the exposures of all employees in order to
determine which employees are exposed at or above the action level. As
discussed in the summary and explanation of Specified Exposure Control
Methods, OSHA has concluded that such an exposure assessment
requirement is not necessary for employers who implement the controls
listed on Table 1.
With regard to permitting employees to request respirators for
Table 1 tasks where respiratory protection is not specified, OSHA has
relied on its technological feasibility analyses to determine which
tasks can be performed at or below the PEL most of the time with the
use of engineering and work practice controls only (i.e., without
respirators), and has concluded that employers who implement the
controls listed on Table 1 for these tasks will provide equivalent
overall protection for their employees as employers who perform
exposure assessment and follow the alternative exposure control methods
option provided in paragraph (d). If an employer follows Table 1 and
Table 1 does not require use of a respirator, the employee's exposure
will generally be below the PEL. There may be exceptions, but this is
no different than when monitoring is conducted--monitoring two or four
times a year does not perfectly characterize exposures, and there will
be situations where exposures exceed the PEL even when good faith
monitoring efforts by the employer indicate that exposures would be
below the PEL.
If respirators were mandated at the action level or available upon
employee request in situations where they are not required under the
rule, employers would need to have respirators available at all times.
Moreover, they would need to establish and implement a full respiratory
protection program for all employees exposed to silica--a considerable
undertaking for many employers that involves not only the purchase and
retention of suitable respirators but an ongoing program of training,
fit-testing, and maintenance. OSHA concludes that "on request"
respirator use or requiring respiratory protection at the action level
is not a practical or responsible approach to occupational safety and
health regulation, and requiring such an investment in respirators
would divert resources from the development and implementation of
engineering controls that could more effectively reduce exposure levels
to or below the PEL. Thus, OSHA's approach for reducing employee
exposure to respirable crystalline silica in this and all other
standards for air contaminants is to focus on engineering controls,
rather than additional requirements for respiratory protection. For
these reasons, OSHA has determined that a requirement for employers to
provide respirators to employees upon request in situations where they
are not required under the rule, or a requirement to provide
respirators to employees exposed at or above the action level, is not
reasonably necessary and appropriate for this respirable crystalline
silica rule.
At the same time, OSHA does not prohibit employers from supplying
or employees from using respirators outside the requirements of the
rule. Therefore, although this rule does not include a provision
providing employees with a right to request and receive respirators
where not required by the rule, or requiring respiratory protection at
the action level, employers may continue to provide respirators at the
request of employees or permit employees to use their own respirators
in situations where respirator use is not required, as provided for in
the respiratory protection standard (29 CFR 1910.134(c)(2)(i)). OSHA's
understanding, however, is that such use beyond what is required in a
comprehensive OSHA standard is not a common occurrence, and the Agency
does not expect non-mandated respirator use to proliferate with respect
to this rule, as might well be the case if a provision requiring
employers to provide respirators "on request" was written into the
rule and would certainly be the case if the action level were used as
the trigger for respirator use.
Industry commenters, including the Construction Industry Safety
Coalition, OSCO Industries, American Foundry Society, National
Association of Manufacturers, Glass Packaging Institute, American
Composite Manufacturers Association, Small Business Administration's
Office of Advocacy, U.S. Chamber of Commerce, and American
Subcontractors Association, urged OSHA to consider discarding the
hierarchy of controls and permitting the use of respirators in lieu of
engineering and work practices controls in various circumstances,
including: During short duration tasks performed intermittently
(Document ID 1992, pp. 3, 5; 2319, p. 115); where exposures exceed the
PEL for 30 days or less per year (Document ID 4229, p. 11); where
exposures are below the respirable dust PEL of 5 mg/m\3\ (Document ID
2380, Attachment 2, p. 24); for unanticipated maintenance issues
(Document ID 3493, pp. 2-3); for small businesses (Document ID 3588,
Tr. 3933-3936); for construction employers (Document ID 2187, p. 6;
2283, p. 3; 2349, p. 5); and for industries using large amounts of
crystalline silica (e.g., oil and gas operations where hydraulic
fracturing is conducted) (Document ID 2283, p. 3; 3578, Tr. 1091).
These comments are discussed in the summary and explanation of Methods
of Compliance. As indicated in that section, OSHA's longstanding
hierarchy of controls policy reflects the common assessment among
industrial hygienists and the public health community that respirators
are inherently less reliable than engineering and work practice
controls in reducing employee exposure to air contaminants like
respirable crystalline silica, and therefore, except in limited
circumstances, they should not be allowed as an alternative to
engineering and work practice controls, which are more reliable in
controlling exposures. Thus, the Agency has not included additional
situations where respirators are required in the respiratory protection
paragraph, but as previously discussed, recognizes that, in some
circumstances, such as certain maintenance and repair activities,
engineering and work practice controls may not be feasible and the use
of respiratory protection would be required.
Paragraph (g)(2) of the general industry and maritime standard
(paragraph (e)(2) of the standard for construction) requires the
employer to implement a comprehensive respiratory protection program in
accordance with OSHA's respiratory protection standard (29 CFR
1910.134) whenever respirators are used to comply with the requirements
of the respirable crystalline silica standard. As contemplated in the
NPRM, a respiratory protection program that complies with the
respiratory protection standard will ensure that respirators are
properly used in the workplace and are effective in protecting
employees. In accordance with that standard, the program must include:
Procedures for selecting respirators for use in the workplace; medical
evaluation of employees required to use respirators; fit-testing
procedures for tight-fitting respirators; procedures for proper use of
respirators in routine and reasonably foreseeable emergency situations;
procedures and schedules for respirator maintenance; procedures to ensure
adequate quality, quantity, and flow of breathing air for atmosphere-supplying
respirators; training of employees in respiratory hazards to which they
might be exposed and the proper use of respirators; and procedures for
evaluating the effectiveness of the program (78 FR 56274, 56467 (9/12/
13)).
Many employers commented that they already have respiratory
protection programs in place to protect employees from exposures to
respirable crystalline silica (Document ID 1964; 2183, p. 1; 2276, p.
5; 2292, p. 2; 2301, Attachment 1, p. 5, 37; 2338, p. 2; 2366, p. 3;
3577, Tr. 711; 3583, Tr. 2386-2387). The International Union of
Bricklayers and Allied Craftworkers and the International Union of
Operating Engineers also indicated that their members' employers have
established respiratory protection programs (Document ID 2329, p. 7;
3583, Tr. 2342, 2367).
The American Association of Occupational Health Nurses, Ameren
Corporation, 3M Company, and Dr. George Gruetzmacher supported the
reference to the respiratory protection standard (Document ID 2134;
2278, p. 3; 2313, p. 6; 2315, p. 4). For example, the 3M Company, which
manufactures respirators, stated:
3M believes that by not requiring separate, individual
respiratory protection provisions for respirable crystalline silica,
the...rule should enhance consolidation and uniformity of the
1910.134 respirator requirements and could result in better
compliance concerning the use of respiratory protection. Many of our
customers use respirators to help protect workers from exposures to
multiple contaminants and the reference in the respirable
crystalline silica standard to the requirements of 1910.134 brings
uniformity that could likely result in better compliance and
protection for workers with exposures to silica and other materials
(Document ID 2313, p. 6).
Expressing an opposing view, the National Stone, Sand, and Gravel
Association commented that the respiratory protection paragraph was
duplicative of existing requirements in 29 CFR 1910.134 (Document ID
2327, Attachment 1, p. 11).
OSHA concludes that referencing the requirements in the respiratory
protection standard is important for ensuring that respirators are
properly used in the workplace and are effective in protecting
employees. Simply cross-referencing these requirements merely brings
the applicable requirements to the attention of the employer; the
cross-reference does not add to the employer's existing legal
obligations, but it makes it more likely that the employer covered by
this standard will meet all its obligations with regard to providing
respirators when required to do so. Thus, the Agency has incorporated
in the rule the reference to the respiratory protection standard that
was proposed.
A representative of a local union and individual employees
recommended specific respirators that they believed should be used to
protect employees exposed to respirable crystalline silica (Document ID
1763, p. 3; 1798, p. 6; 2135). OSHA is not singling out silica-specific
respirators but concludes instead that, for purposes of consistency and
to ensure that the appropriate respirator is used, the provisions of
the respiratory protection standard should apply to substance-specific
standards unless there is convincing evidence that alternative
respirator selection requirements are justified. The commenters who
recommended specific respirators did not provide any evidence to
support their recommendations. As no basis has been established for
distinguishing respirator requirements for respirable crystalline
silica from other air contaminants, OSHA finds it appropriate to adopt
its usual policy of requiring employers to follow the provisions of the
respiratory protection standard.
Paragraph (e)(3) of the standard for construction states that, for
the tasks listed in Table 1 in paragraph (c), if the employer fully and
properly implements the engineering controls, work practices, and
respiratory protection described in Table 1, the employer shall be
considered to be in compliance with paragraph (e)(1) of the standard
for construction and with the requirements for selection of respirators
in paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134. Employers
following Table 1 must still comply with all other provisions of 29 CFR
1910.134. Paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134 require
the employer to evaluate respiratory hazards in the workplace, identify
relevant workplace and user factors, and base respirator selection on
these factors. Because Table 1, in specifying the required respiratory
protection and minimum APF for a particular task, has already done
this, employers following Table 1 are considered to be in compliance
with paragraphs (d)(1)(iii) and (d)(3) of 29 CFR 1910.134 for exposure
to respirable crystalline silica. While not required for employers
fully and properly implementing Table 1, paragraph (d)(3)(i)(A) of the
respiratory protection standard (29 CFR 1910.134), which includes a
table that can be used to determine the type or class of respirator
that is expected to provide employees with a particular APF, can help
employers determine the type of respirator that would meet the required
minimum APF specified by Table 1. For example, Table 1 requires
employers to provide employees with respiratory protection with an APF
of 10 for some of the listed tasks. An employer could consult the table
in 29 CFR 1910.134(d)(3)(i)(A) to find the types of respirators (e.g.,
half-mask air-purifying respirator) that provide at least an APF of 10.
Unions, labor groups, and others urged OSHA to include a provision
in the rule that allows employees to choose a powered air-purifying
respirator (PAPR) in place of a negative pressure respirator (Document
ID 2106, p. 3; 2163, Attachment 1, pp. 15-16; 2173, p. 5; 2244, p. 4;
2253, p. 7; 2256, Attachment 2, pp. 13-14; 2336, p. 7; 2371, Attachment
1, pp. 33-34; 3581, Tr. 1668-1669; 3955, Attachment 1, p. 2; 4204, pp.
78-79). They asserted that employees are more likely to get better
protection from PAPRs, since they are more comfortable and thus, more
likely to be used. They also argued that this will allow employees who
may encounter breathing resistance or other difficulty in wearing a
negative pressure respirator the ability to continue working in a job
where silica exposures cannot feasibly be controlled below the PEL
using engineering and work practice controls, without revealing their
health status or health condition to their employer. They noted that
previous health standards, such as the standards for asbestos (29 CFR
1910.1001(g)(2)(ii)) and cadmium (29 CFR 1910.1027(g)(3)(ii)), include
provisions that allow employees to request and obtain a PAPR without
revealing their health status or health condition to their employer.
In some cases, employers are already providing PAPRs to employees
who request them. The North American Insulation Manufacturers
Association reported that some member companies provide PAPRs upon
employee request in certain circumstances, including accommodating
religious practices and where the work is physically taxing (Document
ID 4213, pp. 4-5). James Schultz, a former foundry employee from the
Wisconsin Coalition for Occupational Safety and Health, testified that
he was able to get his employer to provide a PAPR in some, but not all,
instances when he requested one (Document ID 3586, Tr. 3201).
OSHA has long understood that it is good industrial hygiene
practice to provide a respirator that the employee considers acceptable.
Under the respiratory protection standard, employers must allow employees
to select from a sufficient number of respirator models and sizes so that
the respirator is acceptable to and correctly fits the user
(29 CFR 1910.134 (d)(1)(iv)). In addition, fit testing protocols under the
respiratory protection standard require that an employee has an opportunity
to reject respirator facepieces that the employee considers unacceptable
(see 29 CFR 1910.134 Appendix A). The Agency also recognizes that in some
circumstances employees may prefer PAPRs over other types of respirators.
However, the rulemaking record does not provide a sufficient basis for OSHA
to conclude that a requirement for employers to provide PAPRs upon request
would lead to any meaningful additional benefit for employees exposed to
respirable crystalline silica.
With regard to employees who have difficulty breathing when using a
negative pressure respirator or cannot wear such a respirator, the
respiratory protection standard requires employers to provide a PAPR if
the employee's health is at increased risk if a negative pressure
respirator is used (29 CFR 1910.134(e)(6)(ii)). Under the medical
surveillance provisions of this rule, as well as the medical
determination provisions of the respiratory protection standard (29 CFR
1910.134(e)(6)), the PLHCP's written medical opinion for the employer
must contain any recommended limitations on the employee's use of
respirators. Thus, including a provision in this rule that provides
employees the ability to choose a PAPR in place of a negative pressure
respirator would not appreciably add a benefit to what is already
provided pursuant to required medical determinations. Therefore, OSHA
finds that a provision specific to this rule permitting employees to
request and receive a PAPR in place of a negative pressure respirator
is neither necessary nor appropriate in this rule.
These requirements are consistent with ASTM E 1132-06, Standard
Practice for Health Requirements Relating to Occupational Exposure to
Respirable Crystalline Silica, and ASTM E 2625-09, Standard Practice
for Controlling Occupational Exposure to Respirable Crystalline Silica
for Construction and Demolition Activities, the national consensus
standards for controlling occupational exposure to respirable
crystalline silica in general industry and in construction,
respectively. Each of these standards requires respirators to be used
in work situations in which engineering and work practice controls are
not sufficient to reduce exposures of employees to or below the PEL.
Like the consensus standards, where the use of respirators is required,
the standards that comprise this rule require employers to establish
and enforce a respiratory protection program, as specified in 29 CFR
1910.134.
Housekeeping
Paragraph (h) of the standard for general industry and maritime
(paragraph (f) of the standard for construction) requires employers to
adhere to housekeeping practices. This is a new paragraph in the rule,
but it is derived from the proposed requirements for cleaning methods
(included in the Methods of Compliance paragraph in the proposed rule)
and revised in response to further analysis and public comments. The
requirements apply to all employers covered under this rule, including
where the employer has fully and properly implemented the control
methods specified in Table 1 in the standard for construction.
OSHA proposed a requirement that accumulations of crystalline
silica be cleaned by high-efficiency particulate air (HEPA)-filter
vacuuming or wet methods where such accumulations could, if disturbed,
contribute to employee exposure that exceeds the PEL. The proposed rule
would also have prohibited the use of compressed air, dry sweeping, and
dry brushing to clean clothing or surfaces contaminated with
crystalline silica where such activities could contribute to exposures
exceeding the PEL. OSHA included these provisions in the proposed rule
because evidence shows that use of HEPA-filtered vacuums and wet
methods instead of dry sweeping, dry brushing and blowing compressed
air effectively reduces worker exposure to respirable crystalline
silica during cleaning activities. For example, a study of Finnish
construction workers compared respirable crystalline silica exposure
levels during dry sweeping to exposure levels when using alternative
cleaning methods. Compared with dry sweeping, estimated worker
exposures were about three times lower when workers used wet sweeping
and five times lower when they used vacuums (Document ID 1163).
Some commenters, including the International Union of Bricklayers
and Allied Craftworkers (BAC), the United Steelworkers (USW), the
Building and Construction Trades Department, AFL-CIO (BCTD), the United
Automobile, Aerospace and Agricultural Implement Workers of America
(UAW), BlueGreen Alliance (BGA), and Upstate Medical University,
expressed support for the proposed requirement to use HEPA-filtered
vacuums and wet methods and to prohibit the use of compressed air and
dry sweeping for cleaning activities (e.g., Document ID 2282,
Attachment 3, pp. 2, 18-19; 2329, p. 6; 2336, pp. 8-10; 2371, Comment
1, pp. 32-33; 2176, p. 3; 2244, p. 4). For example, UAW stated that the
prohibitions on the use of compressed air and dry sweeping constitute
sound industrial hygiene and are necessary to ensure that dust is
controlled (Document ID 2282, Attachment 3, p. 18). Similarly, BCTD
argued that the record firmly supports the use of HEPA-filtered vacuums
and wet methods in lieu of compressed air and dry sweeping. BCTD
pointed to specific studies referenced in OSHA's Preliminary Economic
Analysis (PEA) that it believes demonstrate that performing
housekeeping duties using compressed air or dry sweeping is a major
source of silica exposure in a number of work operations (Document ID
2371, p. 34). BCTD also noted and agreed with studies in the PEA that
recommend reducing silica exposure by eliminating these practices and
instead relying on HEPA-filtered vacuums and wet methods (Document ID
2371, p. 34). Based on this evidence, BCTD agreed with the inclusion of
the cleaning provisions. However, as discussed more extensively below,
BCTD, and many of the other commenters that supported these provisions,
argued that OSHA should expand the requirement to apply to cleaning
whenever silica dust is present, not only where employee exposure could
exceed the PEL (e.g., Document ID 2240, p. 3; 2256, Attachment 2, p.
13; 2282, Attachment 3, p. 2; 4204, p. 77).
The National Institute for Occupational Safety and Health (NIOSH)
also supported OSHA's proposed requirement to use wet methods and HEPA-
filtered vacuums and prohibit the use of dry sweeping and compressed
air during cleaning activities. In its written comments and testimony
during the hearings, NIOSH cited U.S. Bureau of Mines research
indicating that dry sweeping can increase respirable dust exposures,
and provided several recommendations, including using water to wash
down facilities that may have silica contamination, and using portable
or centralized vacuum systems to clean off equipment (Document ID 2177,
Attachment B, p. 38; 3579, p. 142).
Other commenters, such as Ameren, Acme Brick, the American Iron and
Steel Institute (AISI), Fann Contracting, Inc., Leading Builders of
America (LBA), Edison Electric Institute (EEI), the National Association
of Home Builders (NAHB), Eramet and Bear Metallurgy Company, Accurate
Castings, the Asphalt Roofing Manufacturers Association (ARMA), the
Small Business Administration's Office of Advocacy, the Glass Association
of North America (GANA), the National Association of Manufacturers (NAM),
the American Foundry Society (AFS), the Ohio Cast Metals Association (OCMA),
the Tile Council of North America (TCNA), the North American Insulation
Manufacturers Association (NAIMA), the Non-Ferrous Founders Society
(NFFS), the National Concrete Masonry Association (NCMA), and the
American Society of Safety Engineers (ASSE), objected to the proposed
provisions (e.g., Document ID 2023, pp. 5-6; 2082, pp. 5-7; 2116,
Attachment 1, pp. 9-10, 32-33; 2261, p. 3; 2269, pp. 4, 22-23; 2291,
pp. 2, 13, 18-20, 27; 2296, pp. 9, 41-42; 2315, p. 8; 2339, p. 9; 2349,
pp. 4-5; 2357, pp. 7, 24-25; 2381, p. 2; 3432, p. 3; 3492, p. 2; 2119,
Attachment 3, p. 7; 2215, p. 9; 2248, p. 8; 2279, pp. 7-8; 2348,
Comment 1, p. 37; 2363, p. 3; 3490, p. 3; 3581, Tr. 1726-1727; 4213, p.
5). Many of these commenters cited problems with the use of wet methods
or HEPA-filtered vacuums in particular circumstances, or noted specific
circumstances where they believed dry sweeping or using compressed air
was necessary.
For example, AISI indicated that using wet methods in areas of
steel making facilities where molten metal is present creates the
potential for a significant and immediate safety hazard from steam
explosions (Document ID 2261, p. 3; 3492, p. 2). The National Concrete
Masonry Association argued that wet methods cannot generally be used in
concrete block and brick plants:
In general, wet methods to control dust are NOT appropriate in
the concrete masonry as a replacement for dry-sweeping...Not
only do wet floors create fall hazards, any dust or debris that
contains cement dust will react and harden in the presence of water,
creating additional problems in concrete block production facilities
(Document ID 2279, pp. 7-8).
EEI and Ameren indicated that the use of wet methods can also cause fly
ash to harden (Document ID 2357, pp. 24-25; 2315, p. 8).
NAHB indicated that use of wet methods in residential construction
would damage many surfaces and could lead to structural problems,
indoor air quality degradation, and the development of molds (Document
ID 2296, p. 37). It argued that there are many circumstances in
residential construction where dry sweeping is the only alternative for
cleanup activities (Document ID 2296, pp. 41-42). LBA indicated that
HEPA-filter vacuums will not collect large debris and that, during the
collection process, dirt will clog the HEPA filter, preventing
cleaning. It stressed that dry sweeping must be used (Document ID 2269,
pp. 4, 22-23). Ameren and EEI argued that dry sweeping should be
allowed because wet methods cannot be used around certain electrical
equipment and when temperatures are below freezing (Document ID 2315,
p. 8; 2357, pp. 7, 24-25). Fann Contracting said that it is necessary
to dry sweep at the end of the milling process when milling roadways in
order to clean the loose leftover material. It indicated that if water
is used, it would create a thin layer of mud on the bottom of the
milled trench, which would interfere with the paving process (Document
ID 2116, Attachment 1, pp. 9-10, 32-33).
Commenters representing foundries argued that wet methods and HEPA-
filtered vacuuming were not appropriate for cleaning in foundries. For
example, Accurate Castings explained that wet methods would result in
water going into the shell sand mold and would eventually lead to an
explosion when molten metal enters the mold. It stressed that it must
use compressed air for these applications (Document ID 2381, p. 2).
Similarly, ESCO Corporation commented that it cannot use water in
foundries due to potential for fire and explosion hazards. ESCO
Corportation stressed that it also must use compressed air to clean
castings (Document ID 3372, pp. 2-3). AFS also argued that the use of
wet methods in foundries increases the likelihood of explosions as well
as tripping hazards (Document ID 3490, p. 3). OCMA argued that vacuums
can cause damage to molds and using wet methods would damage equipment,
make floors slippery, and cause explosions (Document ID 2119,
Attachment 3, p. 7). NFFS argued that compressed air is "the only
viable means of cleaning complex or intricate castings" (Document ID
2247, p. 8; 2248, p. 8). AFS argued that a ban on dry sweeping would
require the vacuuming of hundreds of tons per week in many foundry
operations, and that collecting this amount of sand with a vacuum
system is not feasible. AFS also expressed concern that the proposed
rule would prohibit use of operator-driven power (dry) sweepers in
foundries, arguing that power sweepers substantially reduce the release
of fugitive dust from aisles and other vehicle traffic areas and that
these machines cannot be replaced with wet sweepers because the
quantity of material handled would gum up the sweeping mechanism with
sludge (Document ID 2379, Attachment B, pp. 33-34).
Several commenters indicated that compressed air is needed to clean
difficult to reach places (e.g., Document ID 2215, p. 9; 2279, pp. 7-8;
3581, Tr. 1726; 2023, p. 5; 2348, Comment 1, p. 37; 3544, pp. 15-16;
4213, pp. 5; 2119, Attachment 3, p. 7). For example, GANA stressed that
it is "not technologically feasible to prohibit completely the use of
compressed air for clean-up," because tight spaces and hard-to-reach
crevices can only be cleaned using compressed air (Document ID 2215, p.
9). NAM testified to the need to use compressed air in space-restricted
situations and where there is a potential for explosions when using
water and there are no other alternatives (Document ID 3581, Tr. 1726).
Acme Brick also indicated that compressed air must be used in tight
spaces or under equipment because these areas cannot be accessed by
brooms or vacuums (Document ID 2023, p. 5).
After reviewing the evidence in the record, OSHA concludes that use
of wet methods and HEPA-filter vacuums, as proposed, is highly
effective in reducing respirable crystalline silica exposures during
cleaning and that compressed air, dry sweeping, and dry brushing can
contribute to employee exposures. However, OSHA finds convincing
evidence that wet methods and HEPA-filtered vacuums are not safe and
effective in all situations. Therefore, the Agency has revised the
proposed language to take these situations into account. Paragraph
(h)(1) of the standard for general industry and maritime (paragraph
(f)(1) for construction) allows for the use of dry sweeping and dry
brushing in the limited circumstances where wet methods and HEPA-
filtered vacuuming are not feasible. Paragraph (h)(2) of the standard
for general industry and maritime (paragraph (f)(2) for construction)
allows employers to use compressed air for cleaning where the
compressed air is used in conjunction with a ventilation system that
effectively captures the dust cloud created by the compressed air, or
where no alternative method is feasible. These limited exceptions will
encompass the situations described above by commenters, and give them
the necessary flexibility in permitting the use of compressed air, dry
sweeping, or dry brushing in situations where wet methods or HEPA-
filtered vacuums are infeasible, or where the dust cloud created by use
of compressed air is captured and therefore does not present a hazard to
employees. Thus, in situations where wet methods or HEPA-filtered
vacuuming would not be effective, would cause damage, or would create a
hazard in the workplace, the employer is not required to use these cleaning
methods. OSHA concludes that these limited exceptions balance the need to
protect employees from exposures caused by dry sweeping, dry brushing,
and the use of compressed air with stakeholder concerns about the need
to use such methods under certain circumstances.
Although OSHA is allowing for dry sweeping and dry brushing and the
use of compressed air for cleaning clothing and surfaces under these
limited circumstances, the Agency anticipates that these circumstances
will be extremely limited. The "unless" clause indicates that the
employer bears the burden of showing that wet methods are not feasible
in a particular situation, and OSHA expects that the vast majority of
operations will use wet methods that minimize the likelihood of
exposure. Where the employer uses dry sweeping, therefore, the employer
must be able to demonstrate that HEPA-filtered vacuuming, wet methods,
or other methods that minimize the likelihood or exposure are not
feasible. Similarly, where compressed air is used to clean clothing and
surfaces without a ventilation system designed to capture the dust
cloud created, the employer must be able to demonstrate that no
alternative cleaning method is feasible.
OSHA has also revisited the triggers for these provisions based on
stakeholder comments. Some stakeholders disagreed with triggering these
provisions based on the PEL. For example, the American Federation of
State, County, and Municipal Employees (AFSCME), the American
Federation of Labor and Congress of Industrial Organizations (AFL-CIO),
BCTD, BAC, UAW, USW, and others argued that dry sweeping and use of
compressed air should be prohibited at any exposure level, not just
where the use of such measures contributes to exposures that exceed the
PEL (e.g., Document ID 2142, p. 3; 2257, Attachment 2, p. 13; 2282,
Attachment 3, pp. 18-19; 2329, p. 6; 2336, p. 10; 2371, Comment 1, pp.
32-33). AFL-CIO stated:
OSHA has determined that exposure at the PEL still poses a
significant risk to workers. All feasible efforts should be made to
reduce those risks. OSHA should follow the well-established approach
in its other health standard[s] and prohibit practices of dry
sweeping, [use of] compressed [air] and require HEPA-filter[ ]
vacuuming or wet methods whenever silica dust is present (Document
ID 2257, Attachment 2, p. 13).
Similarly, AFSCME indicated that there is no reason why cleaning
methods need to be tied to the PEL. It argued that requiring that all
accumulations be dealt with in a uniform way would provide clarity for
employers and employees alike (Document ID 2142, p. 3). BCTD argued
that OSHA's proposed requirements would be unenforceable because they
are tied to overexposure (Document ID 2371, Attachment 1, p. 33).
Finally, AFL-CIO also recommended that OSHA expand the proposed
requirements to require that accumulations of dust be kept as low as
practicable. It noted that this requirement has appeared in previous
OSHA health standards that regulate exposure to dusts, such as asbestos
(29 CFR 1910.1001), lead (29 CFR 1910.1025), and cadmium (29 CFR
1910.1027).
On the other hand, the Precast/Prestressed Concrete Institute (PCI)
argued that a general prohibition on the use of compressed air, dry
brushing, and dry sweeping to clean areas where silica-containing
material has accumulated is too broad, and not directly related to a
particular exposure risk. It maintained that the use of compressed air
and dry sweeping should be permitted as long as silica exposures are
below the PEL (Document ID 4029, Cover Letter 1, p. 3). Similarly, the
National Tile Contractors Association (NTCA) and TCNA both recommended
that the proposed language be changed to read as follows:
To the extent practical compressed air, dry sweeping, and dry
brushing shall not be used to clean clothing or surfaces
contaminated with crystalline silica where such activities could
contribute to employee exposure to respirable crystalline silica
that exceeds the PEL (Document ID 2267, p. 3; 2363, p. 3).
After consideration of these comments, OSHA has decided to revise
the trigger for the housekeeping provisions in the rule to apply to
situations where dry sweeping, dry brushing or use of compressed air
could contribute to employee exposure to respirable crystalline silica,
regardless of whether that exposure exceeds the PEL. OSHA finds this
change is necessary because the risk of material impairment of health
remains significant at and below the revised PEL of 50 [mu]g/m\3\,
including at the new action level of 25 [mu]g/m\3\. By triggering the
housekeeping provisions wherever the use of dry sweeping, dry brushing,
and compressed air could contribute to employee exposures, OSHA aims to
minimize this risk. The Agency concludes that the limited exceptions
discussed above not only balance the concerns of employers with the
need to protect employees, but align the rule with the realities of the
workplace, which do not always lend themselves to the method that
produces the lowest silica exposure.
OSHA has decided not to include an affirmative requirement to clean
accumulations of crystalline silica that could, if disturbed,
contribute to employee exposure that exceeds the PEL. In addition, the
Agency has determined that it is not appropriate for the respirable
crystalline silica rule to require accumulations of dust to be kept at
the lowest level practicable. As noted above, OSHA recognizes that
exposure to respirable crystalline silica is hazardous at
concentrations below the PEL. However, crystalline silica is ubiquitous
in many work environments. Crystalline silica is a component of the
soil and sand at many construction sites and other outdoor workplaces,
and may be present in large quantities at many other workplaces such as
foundries and oil and gas drilling sites where hydraulic fracturing is
performed. For purposes of cleaning, the employer may not be able to
distinguish large crystalline silica particles from the fine particles
which can, if airborne, be respirable. In many cases, the employer may
not be able to distinguish crystalline silica particles from other
workplace dusts. Because of these factors, many unique to respirable
crystalline silica, OSHA is convinced that the best approach to address
potentially hazardous exposures from cleaning is by requiring proper
housekeeping practices to minimize exposure to respirable crystalline
silica.
OSHA also received a number of miscellaneous comments on the
proposed provisions, including suggestions for items the Agency should
or should not include in the final rule and questions about the
application of the proposed provisions to particular situations. For
example, ARMA argued that OSHA should not require HEPA filters on
central vacuum systems that discharge outdoors or into a non-occupied
area, such as a baghouse (Document ID 2291, pp. 19-20). GPI also
indicated it uses central vacuum systems, and argued that OSHA should
allow for vacuum systems that discharge outside the facility (Document
ID 2290, pp. 4-5). OSHA agrees that a prohibition on central vacuum
systems that discharge respirable crystalline silica outside of the
workplace is unnecessary, because such systems do not contribute to
employee exposure. OSHA clarifies that the rule therefore allows for
use of vacuum systems that discharge respirable crystalline silica
outside of the workplace. These requirements are similar to housekeeping
requirements in other OSHA health standards, such as the standards for
lead (29 CFR 1910.1025) and cadmium (29 CFR 1910.1027). Discharge of
respirable crystalline silica from such systems may be subject to
environmental regulations; see Section XIV, Environmental Impacts.
Occupational & Environmental Health Consulting Services (OEHCS)
urged OSHA to require vacuums that meet the definition of a Portable
High-Efficiency Air Filtration (PHEAF) device (Document ID 1953,
Comment 1, pp. 4-6). This suggested revision would involve a
requirement for field testing of portable air filtration devices using
a laser particle counter to ensure that HEPA filters function as
intended. OEHCS argued that, in many cases, HEPA filters do not perform
effectively in the field due to inadequate, damaged, or deteriorating
sealing surfaces; replacement filters that do not fit correctly; filter
cabinets that are damaged; filters that are punctured; and other
problems (Document ID 1953, Comment 1, p. 2). OEHCS further indicated
that it is participating in an ongoing, multi-year research effort with
the National Institutes of Health to test HEPA-filtered equipment
(Document ID 1953, Comment 1, p. 2). However, OEHCS did not provide
documentation to support the use and effectiveness of meeting the
requirements and definition of this device, nor is there other evidence
in the rulemaking record supporting such a requirement. OSHA encourages
employers to ensure that HEPA filters function as intended in the
field. However, lacking adequate documentation and support in the
record, OSHA has concluded that it is not appropriate to include a
requirement that HEPA vacuums meet the PHEAF standards in the rule.
OSHA also received a few comments related to the use of compressed
air, dry sweeping, and dry brushing to clean clothing. Specifically,
NIOSH and ASSE maintained that there are ways that clothing can be
safely cleaned using compressed air. The two organizations advocated
for the use of clothes cleaning booths, also referred to as mobile air
showers (Document ID 2177, Attachment B, pp. 15, 38; 3403, p. 5; 2339,
p. 9). This technology uses compressed air to clean clothes by blowing
dust from an employee's clothing in an enclosed booth. Dust is blown
out of the employee's breathing zone and is captured by a filter. NIOSH
argued that the booths adequately capture the dust and prevent exposure
to employees and the environment (Document ID 3403, p. 5). OSHA
recognizes that this technology may be useful for cleaning dust off of
clothing, and the rule does not prohibit the use of such systems.
Clothes cleaning booths that use compressed air to clean clothing are
permitted under the rule, as long as the compressed air is used in
conjunction with a ventilation system that effectively captures the
dust cloud created by the compressed air. The provision has been
modified from that proposed to clearly allow the use of compressed air
in conjunction with a ventilation system that effectively captures the
dust cloud that is created, preventing it from entering the employee's
breathing zone.
In addition, the American Subcontractors Association (ASA) offered
a comment related to dry brushing. It argued that the term "dry
brushing" could be misunderstood, and that an employer could receive a
citation if an employee reflexively brushes visible dust off clothing
(Document ID 2187, p. 6). OSHA's intent in the proposed rule was to
restrict dry brushing activity that was comparable to dry sweeping,
such as using a brush as a tool to clean clothing or surfaces. OSHA
clarifies that the rule does not prohibit employees from using their
hands to remove small amounts of visible dust from their clothing.
Finally, OSHA received comments on how often or at what point
employers need to clean up dust in their facility. For instance,
HalenHardy, a firm that provides products and services to limit
exposures to dangerous dusts, argued that there should be some visible
evidence of silica dust in order to require cleaning (Document ID 3588,
Tr. 3920-3922). NCMA commented that dry sweeping can produce dust and
indicated that best practices suggest that it is important to prevent
the dust or debris from reaching the floor. If not cleaned regularly,
this can lead to buildups of dust on the floor (Document ID 2279, p.
7).
The proposed rule would have required accumulations of crystalline
silica to be cleaned by HEPA-filtered vacuuming or wet methods where
such accumulations could, if disturbed, contribute to employee exposure
to respirable crystalline silica that exceeds the PEL. As explained
above, OSHA's final rule does not require employers to clean up dust.
However, OSHA agrees that housekeeping is an important work practice to
be used to limit employee exposures. And, as discussed in Chapter IV of
the Final Economic Analysis and Final Regulatory Flexibility Analysis,
some employers will need to perform housekeeping in order to limit
employee exposures to the PEL. In recognition of this fact and because
some cleaning methods can contribute to employee exposure, OSHA has
included housekeeping as one of the items employers must address in
their written exposure control plans (see the summary and explanation
of Written Exposure Control Plan).
Moreover, for employers following the general industry and maritime
standard and, in construction, for tasks not listed in Table 1, or
where the employer does not fully and properly implement the control
methods described in Table 1, the rule requires employers to assess the
exposure of each employee who is or may reasonably be expected to be
exposed to respirable crystalline silica at or above the action level.
Where exposure assessment reveals that an employee's exposure exceeds
the PEL, the rule requires employers to use engineering and work
practice controls to reduce and maintain employee exposure to or below
the PEL, unless the employer can demonstrate that such controls are not
feasible. Good housekeeping is one such work practice control that
employers should consider. And, as NCMA suggests, employers may choose
to clean up dust regularly as a best practice.
In addition, paragraph (c) of the standard for construction
includes several housekeeping provisions that apply to employers who
choose to follow Table 1. For instance, paragraphs (c)(1)(vii) and
(c)(1)(viii) of the standard for construction require employers whose
employees are engaged in a task using handheld or stand-mounted drills
(including impact and rotary hammer drills) or dowel drilling rigs for
concrete to use a HEPA-filtered vacuum when cleaning holes. Similarly,
under paragraph (c)(1)(xiii), when using a walk-behind milling machine
or floor grinder indoors or in an enclosed area, milling debris must be
cleaned up using a HEPA-filtered vacuum prior to making a second pass
over an area. This prevents the milling debris from interfering with
the seal between machine and floor and minimizes the gap. Additionally,
it prevents debris from being re-suspended and acting as another source
of exposure.
If an employer chooses to follow paragraph (c) of the standard for
construction, then the employer must implement any applicable
housekeeping measures specified in Table 1. An employer who does not do
so has not fully and properly implemented the controls identified on
Table 1 and, thus, will be required to assess and limit the exposure of
employees in accordance with paragraph (d). For example, if an employer
has an employee who is using a handheld or stand-mounted drill, the
employee must use a HEPA-filtered vacuum when cleaning holes. Any method
for cleaning holes can be used, including the use of compressed air, if
a HEPA-filtered vacuum is used to capture the dust. If a HEPA-filtered
vacuum is not used when cleaning holes, then the employer must assess and
limit the exposure of that employee in accordance with paragraph (d).
While the paragraph on housekeeping (paragraph (f) of the
construction standard) also applies when employers are following
paragraph (c), the employer must ensure that all of the engineering
controls and work practices specified on Table 1 are implemented. For
example, paragraph (f)(2)(i) of the construction standard permits the
use of compressed air when used in conjunction with a ventilation
system that effectively captures the dust cloud. However, to fully and
properly implement the controls on Table 1, an employer using
compressed air when cleaning holes drilled by handheld or stand-mounted
drills or dowel drilling rigs for concrete must use a HEPA-filtered
vacuum to capture the dust, as specified in paragraphs (c)(1)(vii) and
(c)(1)(viii), not just a ventilation system as specified in paragraph
(f)(2)(i).
The housekeeping requirements of the rule are generally consistent
with the provisions of the industry consensus standards, ASTM E 1132-
06, Standard Practice for Health Requirements Relating to Occupational
Exposure to Respirable Crystalline Silica, and ASTM E 2626-09, Standard
Practice for Controlling Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities. Both
consensus standards specify that compressed air shall not be used to
blow respirable crystalline silica-containing materials from surfaces
or clothing, unless the method has been approved by an appropriate
Regulatory agency (4.4.3.3. and 4.4.3.2, respectively). Both consensus
standards also list HEPA vacuums, water spray, and wet floor sweepers
among available means to reduce exposure to dust (4.4.3.6. and 4.4.3.5,
respectively). In addition, ASTM E 1132-06 includes restrictions on dry
sweeping (4.4.3.2).
Written Exposure Control Plan
Paragraph (f)(2) of the standard for general industry and maritime
(paragraph (g) of the standard for construction) sets forth the
requirements for written exposure control plans, which describe methods
used to identify and control workplace exposures, such as engineering
controls, work practices, and housekeeping measures. OSHA did not
propose a requirement for a written exposure control plan, but raised
it as an issue in the preamble of the Notice of Proposed Rulemaking
(NPRM) in Question 53 under Methods of Compliance (78 FR 56273, 56289
(9/12/13)). Written exposure control plans are included in ASTM
International (ASTM) standards, E 1132-06, Standard Practice for Health
Requirements Relating to Occupational Exposure to Respirable
Crystalline Silica (Section 4.2.6) and E 2625-09, Standard Practice for
Controlling Occupational Exposure to Respirable Crystalline Silica for
Construction and Demolition Activities (Section 4.2.5), and in a draft
standard by the Building and Construction Trades Department, AFL-CIO
(BCTD) (Document ID 1466, p. 2; 1504, p. 2; 1509, pp. 3-4).
The only written plan that OSHA proposed was an access control
plan, which was an alternative approach to establishing regulated
areas; it described methods for identifying areas where exposures
exceeded the permissible exposure limit (PEL), limiting access to those
areas, communicating with others on the worksite, and providing
personal protective equipment (PPE) to individuals entering those
areas. Several stakeholders commented on the proposed written access
control plans, whether or not the rule should contain a written plan,
and their preference for the type of written plan.
A number of commenters questioned the practicality of a written
access control plan in workplaces with continually changing tasks,
conditions, or materials, which they argued can lead to the need for
multiple plans and subsequent costs. The National Stone, Sand, and
Gravel Association (NSSGA) commented that written access control plans
and establishing boundaries are not feasible in many workplaces, such
as aggregate facilities or large construction sites, because of varying
silica amounts in materials (Document ID 2327, Attachment 1, p. 20).
The Construction Industry Safety Coalition (CISC) stated that a written
access control plan is impractical in construction and especially
difficult and costly for small businesses because a different plan
would need to be developed for each project, as a result of changing
materials, tasks, and environmental conditions (Document ID 2319, pp.
5-6, 91-92). Associated Builders and Contractors, Inc. (ABC),
Associated General Contractors of America, and American Society of
Safety Engineers (ASSE) expressed similar concerns about constantly
changing conditions on construction sites (Document ID 2289, pp. 6-7;
2323, p. 1; 4201, p. 2). The National Federation of Independent
Business and Leading Builders of America also expressed concerns about
time and resource burdens that a requirement for a written access
control plan would impose on construction companies or small businesses
(Document ID 2210, Attachment 1, p. 7; 2269, p. 22). ABC and CISC
further stated that a written access control plan is not needed if
employees are trained (Document ID 2289, pp. 6-7; 4217, p. 25).
CISC noted that section 4.2.5 of the ASTM standard E 2625-09 limits
the need for a written exposure control plan to areas where
overexposures are persistent, and contemplated that it is not needed
when the PEL may be exceeded on a particular day because of conditions
such as weather or silica content in a material. CISC stated that
OSHA's requirement for a regulated area or written access control plan
when exposures can reasonably be expected to exceed the PEL deviated
from section 4.2.5 of the ASTM standard (Document ID 2319, p. 89; 1504,
p. 2). OSHA clarifies that a written access control plan, which
describes specified methods for limiting access to high-exposure areas,
is different from a written exposure control plan, which can address
specified protections for controlling exposure other than limiting
access to high-exposure areas.
Commenters representing industry, labor, and employee health
advocate groups addressed the issue of what, if any, type of written
plan should be required and what level of respirable crystalline silica
exposure should trigger that requirement. Some industry representatives
favored a written access control plan over a regulated area, while
others opposed a written exposure control plan. For example, in
comparing regulated areas and the written access control plan, Edison
Electric Institute favored the flexibility of the written access
control plan and stated that it might use that option in larger areas
or for activities that can change over time. It opposed a written
exposure control plan, asserting that the training required by OSHA's
hazard communication standard (HCS) was sufficient to keep employees
informed (Document ID 2357, pp. 33, 37). The Non-Ferrous Founders'
Society expressed concerns about costs if a consulting industrial
hygienist would need to be hired to develop a written access control
plan (Document ID 2248, p. 13). The National Association of Home
Builders (NAHB) stated that some of its members would prefer a
written access control plan over regulated areas, while other members
expressed concern that developing a written access control plan
might be difficult for many small companies. NAHB also commented that
many small companies would not have the knowledge to develop a written
exposure control plan and would have to hire a professional to develop
it. NAHB opposed a written exposure control plan, stating that a
standard checklist was adequate for protecting employees from exposure
(Document ID 2296, pp. 40 and 41). On the other hand, National
Electrical Carbon Products (NECP) commented that if OSHA required a
written plan, NECP would prefer an exposure control plan rather than an
access control plan. It stated that OSHA's proposed access restrictions
do not relate to the goal of ensuring compliance with the PEL (Document
ID 1785, pp. 6-7).
Commenters from labor organizations and employee health advocate
groups supported the inclusion of a written exposure control plan. For
example, BCTD stated that the proposed written access control plan
could be used as a starting point for the development of a written
exposure control plan, which it said should be required for every
employer that has employees who may be exposed to respirable
crystalline silica (Document ID 2371, Attachment 1, pp. 14-16).
International Union of Operating Engineers (IUOE), Public Citizen,
American Federation of Labor and Congress of Industrial Organizations
(AFL-CIO), and International Union of Bricklayers and Allied
Craftworkers (BAC) also supported a requirement for a written plan for
all covered employers and not just those with regulated areas or
exposures exceeding the PEL (Document ID 2262, p. 42; 2249, p. 3; 4204,
p. 62; 4219, pp. 25-26; 4223, p. 119).
Other commenters, such as ASSE, favored a written exposure control
plan for suspected or documented overexposure scenarios (Document ID
2339, p. 8). The National Industrial Sand Association (NISA) originally
opposed a written exposure control program in its prehearing comments
(Document ID 2195, p. 38). However, in its post-hearing comments, it
supported one, stating that formulating and writing down an exposure
control program would ensure that an employer thinks through the
engineering and administrative controls required to achieve compliance
in situations with persistent overexposures. NISA also stated that the
plan would help employers defend against potential liability by
documenting due care (Document ID 4208, pp. 20-21).
The American Foundry Society (AFS) disagreed with the need for a
separate written exposure control plan and instead called for planning
as part of other business initiatives. It supported written exposure
control plans in enforcement situations. AFS favored an approach
similar to that in the ASTM standard. AFS stated that the ASTM's
approach, which involves identifying and analyzing dust sources in
scenarios with overexposures to determine effective controls, was more
effective in reducing exposures than requiring controls to be installed
by a certain date (Document ID 2379, Appendix 1, pp. 61-62; 4229, p.
26).
Advocates of written exposure control plans explained why they
supported those plans. The National Institute for Occupational Safety
and Health (NIOSH) stated that written exposure control plans could be
a simple mechanism for ensuring performance of maintenance checks and,
for construction employers, maintaining Table 1 conditions (Document ID
2177, Attachment B, pp. 16-17). Dr. Paul Schulte, Director of the
Education and Information Division at NIOSH, testified that "...a
written plan would greatly improve reliability of the protection
provided." (Document ID 3403, p. 5). AFL-CIO, NISA, and BCTD agreed
(Document ID 4204, p. 61; 4208, pp. 20-21; 4223, p. 74). Eileen Betit,
representing BCTD, testified:
Written exposure control plans are important for identifying
operations that will result in exposures, the specific control
measures, and how they will be implemented and the procedures for
determining if controls are being properly used and maintained. Such
plans also facilitate the communication of this information to other
employers on multi-employer worksites so that they, in turn, can
take steps to protect their employees. Without such plans, there's
no assurance that employers and employees will take a systematic and
comprehensive approach to identifying, controlling, and sharing
information about silica exposures on job sites (Document ID 3581,
Tr. 1569-1570).
The United Steelworkers (USW), Public Citizen, the United Automobile,
Aerospace and Agricultural Implement Workers of America (UAW), and AFL-
CIO also supported a requirement for a written exposure control plan as
a method to continually, systematically, or comprehensively identify or
control exposures (Document ID 2336, p. 9; 2249, p. 2; 2282, Attachment
3, p. 17; 4204, p. 60). NIOSH, Public Citizen, and BAC also stated that
written exposure control plans are a useful way to communicate
protections to employees (Document ID 2177, Attachment B, pp. 16-17;
2249, p. 3; 2329, p. 5).
BlueGreen Alliance, UAW, USW, and AFL-CIO also supported a written
plan because requiring the written plan would be consistent with the
many other OSHA substance-specific standards that include written plans
or programs (Document ID 2176, p. 3; 2282, Attachment 3, p. 17; 3584,
Tr. 2540; 4204, p. 62). In addition, commenters observed that other
U.S. and Canadian regulatory agencies require written plans. Frank
Hearl, Chief of Staff at NIOSH, stated that the Mine Safety and Health
Administration requires a dust control plan to be filed at coal mines
(Document ID 3579, Tr. 235-236). In addition, AFL-CIO and BCTD noted
that written dust or silica control plans are included in a proposed
standard for the Canadian Province of British Columbia and a standard
promulgated in the Canadian Province of Newfoundland (Document ID 4204,
p. 61; 4223, p. 73 Fn. 14; 4072, Attachment 38, pp. 6-7, Attachment 41,
p. 7).
BCTD stated that a requirement for a written exposure control plan
would not be unduly burdensome to employers because creating such plans
is an extension of planning functions in construction (Document ID
4223, pp. 74-80). In fact, several hearing participants testified that
written safety or hazard control plans are already being developed and
used in the construction industry (Document ID 4223, pp. 74-80; 3580,
Tr. 1383-1385; 3583, Tr. 2267-2268, 2385; 3585, Tr. 3093-3094; 3587,
Tr. 3560). For example, Kevin Turner, Director of Safety at Hunt
Construction Group and representing CISC testified: "...we require
a site-specific safety plan which addresses the hazards dealt with in
that [particular] contractor's scope of work." (Document ID 3580, Tr.
1383).
In addition, written plans are consistent with general industry
practices. For example, the National Service, Transmission,
Exploration, and Production Safety Network (STEPS Network), whose
members are involved in the oil and gas industry, recommends a written
plan that describes how exposures to respirable crystalline silica will
be reduced or prevented (Document ID 4024, Attachment 2, p. 1). Member
companies of the National Ready Mix Concrete Association, who hire
third-party contractors to chip out their drum mixers, follow strict
written practices and procedures to ensure that exposures do not exceed
the PEL. Specifically, they require the contractors to submit to them a
company-approved safety and health policy and procedures and plans
(Document ID 2305, pp. 8-9). AFL-CIO submitted to the record a silica
dust control plan developed by Sonic Drilling
(Document ID 4072, Attachment 11).
BCTD stressed that preparing a written exposure control plan does
not have to be burdensome and, along with BAC and AFL-CIO, pointed to
online tools that are available to help users create written exposure
control plans, such as the CPWR-Center for Construction Research and
Training (CPWR) tool, available free of charge, on the silica-safe.org
Web site (Document ID 2329, p. 5; 4204, p. 61; 4223, pp. 80-81; 4073,
Attachment 5a and 5b). AFL-CIO and BCTD also pointed to guidance
products and model exposure control plans from the Canadian Province of
British Columbia as additional resources for assisting users in
developing written exposure control plans (Document ID 4204, p. 61;
4223, p. 81; 4072, Attachment 14, 19, 20). Industry associations are
another resource to help employers prepare written plans. For example,
Anthony Zimbelman, general contractor, representing NAHB, testified
that his industry association teaches courses and helps businesses
develop safety plans (Document ID 3587, Tr. 3559-3560).
OSHA finds the evidence on the benefits of a written exposure
control plan--as distinct from the proposed written access control
plan--convincing and has concluded that a requirement for a written
exposure control plan is needed for both the standard for general
industry/maritime and the standard for construction because the plan
will improve employee protections. OSHA agrees with commenters who
stated that a written plan should not be limited to scenarios where the
PEL is exceeded. Therefore, OSHA concludes that it is appropriate for
the rule to require a written exposure control plan, instead of a
written access control plan that would only apply to restricting access
to areas where exposures to respirable crystalline silica exceed the
PEL. Requiring a written exposure control plan for all employers
covered by the rule is more protective than the ASTM approach of only
requiring written exposure control plans for persistent overexposures.
Even if exposures are below the PEL due to the use of engineering
controls or work practices, a systematic approach for ensuring proper
function of engineering controls and effective work practices is
crucial for ensuring that those controls and practices remain
effective. Thus, OSHA finds that a written exposure control plan is
integral to preventing overexposures from occurring.
OSHA agrees with NISA that requiring employers to articulate
conditions resulting in exposure and how those exposures will be
controlled will help to ensure that they have a complete understanding
of the controls needed to comply with the rule. OSHA expects a written
exposure control plan will be instrumental in ensuring that employers
comprehensively and consistently protect their employees. Even in cases
where employees are well trained, the written plan can help to ensure
that controls are consistently used and become part of employees'
routine skill sets. Employers could opt to use the plans to ensure that
maintenance checks are routinely performed and optimal conditions are
maintained. In addition, OSHA concludes the written plans are a useful
method for communicating protections to employees.
Requiring a written plan maintains consistency with the majority of
OSHA substance-specific standards for general industry and
construction, such as lead (29 CFR 1910.1025 and 1926.62) and cadmium
(29 CFR 1910.1027 and 1926.1127), which require written compliance
plans. A requirement for a written exposure control plan is also
consistent with Canadian standards. In addition, it is generally
consistent with industry practices, as evidence in the record indicates
that some employers in general industry and construction are already
developing and using written plans. OSHA concludes that even for small
businesses, preparing a written exposure control plan based on
identifying and controlling respirable crystalline silica hazards will
not be unduly burdensome, because of the widespread availability of
tools and guidance from groups such as CPWR and the Canadian
government. In addition, OSHA anticipates that industry associations
will provide guidance on developing written exposure control plans for
respirable crystalline silica.
Contrary to the concerns indicated by comments from representatives
from the construction industry, OSHA does not intend or expect that
employers will need to develop a new written plan for each job or
worksite. Many of the same tasks will be conducted using the same
equipment and materials at various worksites. For example, a stationary
masonry saw used outdoors to cut concrete will perform similarly in any
outdoor setting. Most construction employers are expected to use the
specified exposure control methods in Table 1 of paragraph (c), which
will help them identify tasks and controls to be included in the
written exposure control plan. Table 1 does not usually specify
different controls for different types of crystalline silica-containing
materials, thus supporting the conclusion that a new plan does not need
to be continually developed. Table 1 does list some conditions, such as
time performing tasks or use of equipment in enclosed areas, that would
require respirator use in addition to the specified controls; those
different scenarios can be indicated in the written exposure control
plan, as applicable. Therefore, the written exposure control plan does
not have to be limited by materials, tasks, and conditions for a
particular job site and can include all materials, tasks, and
conditions typically encountered. In many cases there will be no need
to modify the written plan just because the location has changed.
However, the plan must address all materials, tasks, and conditions
that are relevant to the work performed by a particular company. OSHA
is including in the docket a sample written exposure control plan for a
bricklaying company for reference.
OSHA concludes that it is appropriate to include a requirement for
a written exposure control plan in the respirable crystalline silica
standards for general industry/maritime and construction. Therefore
paragraph (f)(2)(i) of the standard for general industry and maritime
(paragraph (g)(1) of the standard for construction) requires the
employer to establish and implement a written exposure control plan
that contains at least the elements specified in paragraphs
(f)(2)(i)(A)-(C) of the standard for general industry and maritime
(paragraph (g)(1)(i)-(iv) of the standard for construction). This
provision not only requires that a written exposure control plan be
established but also implemented. OSHA does not consider it sufficient
to develop a plan and have a copy of it on a shelf. It must be followed
in the day-to-day performance of tasks identified.
OSHA considered existing written exposure control plans, such as
the ASTM plans, and commenter suggestions to determine what should be
included in a written exposure control plan. Section 4.2.5 of ASTM
standard E 2625-09 concerning construction and demolition provides:
In areas where overexposures are persistent, a written exposure
control plan shall be established to implement engineering, work
practice, and administrative controls to reduce silica exposures to
below the PEL, or other elected limit, whichever is lower, to the
extent feasible. Conduct a root cause analysis for all exposures in
excess of the PEL that cannot be accounted for. Root cause analysis
involves investigating cause(s) for the excessive exposure,
providing remedies, and conducting follow-up sampling to document
that exposures are below the PEL (Document ID 1504, p. 2).
The exposure control plan described in section 4.2.6 of ASTM
standard E 1132-06 is substantively consistent with the approach
described by section 4.2.5 of ASTM standard E 2625-09 (Document ID
1466, p. 2; 1504, p. 2).
Several stakeholders commented on what should be included in
provisions for a written exposure control plan. ASSE described an
approach similar to that in the ASTM standards, and AFS preferred the
ASTM approach during enforcement actions (Document ID 2339, p. 8; 2379,
Appendix 1, pp. 61-62).
NIOSH stated that the exposure control plan could be based on
OSHA's Job Hazard Analysis approach (Document ID 2177, Attachment B, p.
16; OSHA document 3071, Revised 2002). The OSHA job hazard analysis
form calls for descriptions of tasks, hazards, hazard controls, and
rationale and comments (OSHA document 3071, Revised 2002, Appendix 3).
Similarly, NISA recommended that written exposure control programs
convey an understanding of work processes and their appropriate
controls for managing exposures (Document ID 4208, p. 21).
Some labor unions, such as AFL-CIO and BCTD, recommended more
extensive requirements for a written exposure control or compliance
program that included identification of exposures and controls, in
addition to exposure assessment methods or results, and descriptions of
the respiratory protection, medical surveillance, and training programs
(Document ID 2371, Attachment 1, pp. 16-17; 4204, p. 62; 4223, p. 82).
Commenters such as Public Citizen, USW, UAW, and BCTD all agreed
that the value of a written exposure control plan is that it allows for
consistent identification and control of respirable crystalline silica
hazards (Document ID 2249, p. 2; 2336, pp. 8-9; 2282, Attachment 3, p.
17; 3581, Tr. 1569-1571; 4204, p. 60). OSHA affirms that the purpose of
the written exposure control plan is the consistent identification and
control of respirable crystalline silica hazards, and it is basing the
requirements for a written exposure control plan on that purpose.
As discussed more fully below, the written exposure control plan
required under this rule for respirable crystalline silica is similar
to the ASTM standards in most, but not all, respects. The major
difference between the written plans in the ASTM standards and in this
rule is that written exposure control plans in this rule are not
limited to overexposure scenarios.
OSHA thus considered the ASTM standards and commenter suggestions
to develop requirements for a written exposure control plan. The Agency
also considered which aspects of the proposed written access control
plan should be retained or modified. Therefore, the requirement for a
written exposure control plan evolved from comments on OSHA's proposed
written access control plan and in response to OSHA raising the
possible inclusion of a written exposure control plan as an issue.
Requirements for the written exposure control plan. Paragraphs
(f)(2)(i)(A)-(C) of the standard for general industry and maritime
(paragraphs (g)(1)(i)-(iv)) of the standard for construction) identify
the elements to be addressed in a written exposure control plan.
Requirements for the written exposure control plan are performance-
based to allow employers to tailor written exposure control plans to
their particular worksites. The following discussion describes the
minimum requirements for the written exposure control plan and the
evidence that supports those requirements. It also recommends general
information to include for each section of the plan.
Paragraph (f)(2)(i)(A) of the standard for general industry and
maritime (paragraph (g)(1)(i)) of the standard for construction)
requires a description of tasks involving exposures to respirable
crystalline silica. The proposed written access control plan called for
identification of areas where respirable crystalline silica exposure
may exceed the PEL. Communication Workers of America (CWA), Public
Citizen, USW, AFL-CIO, NISA, and BCTD recommended that the written
exposure control plan describe tasks, operations, or work processes
that result in exposures to respirable crystalline silica (Document ID
2240, p. 2; 2249, p. 3; 2336, p. 9; 4204, p. 62; 4208, p. 21; 4223, p.
82). A description of tasks involving exposures to respirable
crystalline silica is consistent with the first step of the root cause
analysis in the ASTM exposure control plans, which involves
investigating sources of overexposures (Document ID 1466, p. 2; 1504,
p. 2). It is also consistent with the identification of tasks and
hazards in the OSHA Job Hazard Analysis approach that is recommended by
NIOSH as a model for a respirable crystalline silica written exposure
control plan (Document ID 2177, Attachment B, p. 16; OSHA Document
3071, Revised 2002, Appendix 3).
Paragraph (f)(2)(i)(A) of the standard for general industry and
maritime (paragraph (g)(1)(i) of the standard for construction)
reflects OSHA's agreement with commenters that it is important for
employers to consistently identify tasks resulting in exposure to
ensure that appropriate employee protections are applied when needed.
The identification of tasks with potential respirable crystalline
silica exposure is no longer limited to exposures above the PEL, as it
was in the proposed written access control plan. This is more
protective because it identifies all tasks that could contribute to
employee exposures, thereby furthering the purpose of the rule.
In preparing this section of the written plan, employers must list
all tasks that employees perform that could expose them to respirable
crystalline silica dust. This section of the written plan could include
a description of factors that affect exposures, such as types of
silica-containing materials handled in those tasks (e.g., concrete,
tile). It could also describe factors such as weather (e.g., wind,
humidity) and soil compositions (e.g., clay versus rock) (Document ID
3583, Tr. 2350-2352, 2356-2360; 4234, Part 2, pp. 37-38). Another
factor that could affect exposure and protective requirements and thus
could be described in the written plan is the location of the task, for
instance, whether the task is performed in an enclosed space (Document
ID 2177, Attachment B, pp. 16-17). For example, the Table 1 entry for
walk-behind saws with integrated water delivery systems indicates that
a respirator is only required when the equipment is used indoors or in
an enclosed area.
Paragraph (f)(2)(i)(B) of the standard for general industry and
maritime (paragraph (g)(1)(ii) of the standard for construction)
requires a description of engineering controls, work practices, and
respiratory protection used to limit employee exposure to respirable
crystalline silica for each task. CWA, Public Citizen, USW, AFL-CIO,
NISA, and BCTD requested that the written plan describe controls for
managing exposures. Engineering and work practice controls were
specifically mentioned by Public Citizen, USW, AFL-CIO, and BCTD
(Document ID 2240, p. 2; 2249, pp. 3-4; 2336, p. 9; 4204, p. 62; 4208,
p. 21; 4223, p. 82). AFL-CIO further recommended that the written plan
describe jobs where respiratory protection is required (Document ID
4204, p. 62). BCTD also requested that the written plan describe
procedures for implementing the controls and for determining if the
controls are being used and maintained correctly (Document ID 4223, p.
82). NIOSH stated that a written exposure control plan can be a simple
mechanism for ensuring that maintenance checks are conducted and Table
1 conditions are maintained (Document ID 2177, Attachment B, pp. 16-
17).
Paragraph (f)(2)(i)(B) of the standard for general industry and
maritime (paragraph (g)(1)(ii) of the standard for construction)
reflects OSHA's agreement that the written exposure control plan must
address controls, work practices, and respiratory protection used to
manage exposures for each task identified in paragraph (f)(2)(i)(A) of
the standard for general industry and maritime (paragraph (g)(1)(i) of
the standard for construction). The purpose of this requirement is to
ensure that exposures to respirable crystalline silica hazards are
consistently controlled. Therefore, written exposure control plans must
include information such as types of controls used (e.g., dust
collector with manufacturer's recommended air flow and a filter with 99
percent efficiency), effective work practices (e.g., positioning local
exhaust over the exposure source), and if required, appropriate
respiratory protection (e.g., a respirator with an assigned protection
factor (APF) of 10) for each task. The requirement is consistent with
the exposure control plans in the ASTM standards that address
implementation of engineering controls and work practices to reduce
respirable crystalline silica exposures (Document ID 1466, p. 2; 1504,
p. 2). It is also consistent with OSHA's Job Hazard Analysis approach,
which is recommended by NIOSH as a model for the exposure control plan
and calls for a description of controls (Document ID 2177, Attachment
B, p. 16; OSHA document 3071, Revised 2002, Appendix 1 and 3).
OSHA also agrees with NIOSH and BCTD about the necessity of
addressing the proper implementation and maintenance of controls for
each task. This is reflected in paragraph (c) of the standard for
construction, in the Table 1 requirements to operate or maintain tools
according to manufacturers' instructions. Proper implementation and
maintenance of controls is also necessary to meet the PEL under
paragraph (c) of the standard for general industry and maritime and
paragraph (d)(1) of the standard for construction for construction
employers who choose or are required to follow the alternative exposure
control methods. Therefore, to help ensure compliance with the rule,
the employer, in this section of the written exposure control plan,
could indicate signs that controls may not be working effectively
(e.g., dust is visible, no water is delivered to the blade). The plan
could also include a description of procedures the employer uses for
verifying that controls are functioning effectively (e.g., pressure
checks on local exhaust ventilation) and schedules for conducting
maintenance checks.
OSHA finds the written exposure control plan especially important
for construction employers who use the specified exposure control
methods in Table 1 of paragraph (c). For them, the description of
engineering controls, work practices, and respiratory protection is
especially necessary to ensure adequate protection of employees and the
use of controls according to the manufacturer's instructions, since
employers are not required to conduct exposure assessments to verify
that controls are working properly. In cases where the employer owns a
particular type of equipment and it is repeatedly used at different job
sites, describing the manufacturer's instructions for operating the
dust controls in a written exposure control plan will demonstrate that
the employer has a complete understanding of and is applying those
specifications needed to control dust emissions. Describing those
specifications in the written exposure control plans will also serve as
a convenient reference for employees.
As an example, in completing this section of the written plan, an
employer whose employees use a Stihl[supreg] Model TS 410 saw to cut
concrete could consult the user's manual to list or summarize those
instructions in his or her written exposure control plan. Based on the
user's manual, this section of the plan could indicate that (1) before
using a Stihl[supreg] Model TS 410 saw for cutting concrete, the
employee must examine the diamond cutting wheel for signs of excessive
wear, damage, or "built-up edges" (i.e., a pale, grey deposit on the
top of the diamond segments that clogs and blunts them) and (2) while
cutting, the employee must use a water flow rate no less than 0.6
liters (20 fluid ounces) per minute, stop and rinse the screen on the
water connection if no or too little water is delivered while cutting,
and not cut into the ballast layer of road surfaces to avoid excessive
wear on the cutting wheel (Document ID 3998, Attachment 12a, pp. 9, 21-
23). The specified exposure control methods in Table 1 indicate that
the employee must wear a respirator with an APF of 10 when using this
saw outdoors for more than 4 hours a day, and this type of information
must be included in this section, if applicable.
Paragraph (f)(2)(i)(C) of the standard for general industry and
maritime (paragraph (g)(1)(iii) of the standard for construction)
requires a description of the housekeeping measures used to limit
employee exposure to respirable crystalline silica. BCTD requested that
the exposure control plan describe housekeeping methods (Document ID
2371, Attachment 1, pp. 16-17). Similarly, CWA and USW recommended that
the written plan describe procedures for preventing the migration of
silica, and USW further noted that the plan should address keeping
surfaces visibly clean (Document ID 2240, p. 2; 2336, p. 9). USW also
requested that the written exposure control plan describe procedures
for removing, laundering, storing, cleaning, repairing, or disposing of
protective clothing and equipment (Document ID 2336, p. 9).
Paragraph (f)(2)(i)(C) of the standard for general industry and
maritime (paragraph (g)(1)(iii)) of the standard for construction)
reflects OSHA's agreement that housekeeping needs to be addressed in
the written exposure control plan because some cleaning methods can
contribute to employee exposure to respirable crystalline silica. OSHA
intends this requirement to help ensure that employers identify and
implement appropriate cleaning methods so that employees are protected
from respirable crystalline silica dust that can become airborne while
performing housekeeping activities. Ensuring safe housekeeping methods
helps to consistently control exposures and hazards related to
respirable crystalline silica. Housekeeping is another type of work
practice to be used to limit employee exposures, and thus, it is
consistent with the written exposure control plans in the ASTM
standards, which call for implementing work practices to decrease
exposures (Document ID 1466, p. 2; 1504, p. 2). It is also consistent
with OSHA's Job Hazard Analysis approach, which is recommended by NIOSH
as a model for the exposure control plan and calls for a description of
controls (Document ID 2177, Attachment B, pp. 16-17; OSHA document
3071, Revised 2002, Appendix 1 and 3).
OSHA concludes that requiring the written exposure control plan to
include a description of housekeeping methods is important because
acceptable housekeeping methods can vary among different companies. As
described more fully in the summary and explanation of Housekeeping,
certain housekeeping practices, such as wet sweeping, are infeasible in
some work scenarios. Therefore, OSHA modified proposed prohibitions on
cleaning activities, such as dry sweeping or compressed air, to indicate
that those housekeeping methods can be used if there are no other feasible
methods. However, to comply with the rule, employers must ensure that
wet sweeping, HEPA-filtered vacuuming, or other appropriate cleaning
methods are used wherever feasible, if dry sweeping or dry brushing
could contribute to employee exposure to respirable crystalline silica.
It is therefore important for the employer to specify in the written
exposure control plan the housekeeping practices the employer uses to
limit employee exposures and any special protections that are needed
when a particular housekeeping method is used.
To ensure that cleaning methods used comply with paragraph (h) of
the standard for general industry and maritime (paragraph (f) of the
standard for construction), this section of the written plan could
include a description of acceptable and prohibited cleaning methods
used by the employer to minimize generation of airborne dust and
special instructions regarding cleaning methods (e.g., using local
exhaust ventilation if compressed air must be used). Hygiene-related
subjects, such as not using compressed air to clean clothing, could
also be addressed in this section of the written exposure control plan.
Paragraph (g)(1)(iv) of the standard for construction requires a
description of the procedures used to restrict access to work areas,
when necessary, to limit the number of employees exposed to respirable
crystalline silica and the levels to which they are exposed, including
exposures generated by other employers or sole proprietors. No such
requirement is included in the written exposure control plan provision
for general industry and maritime. The reasons for the differing
requirements in the two standards are discussed below.
The proposed written access control plans for general industry and
maritime and construction called for procedures for notifying employees
about the presence and location of areas where respirable crystalline
silica concentrations are or can be reasonably expected to exceed the
PEL and for demarcating those areas from the workplace if needed. Also
included in the proposed access control plan were provisions for
limiting access to areas where respirable crystalline silica exposures
may exceed the PEL, in order to minimize the numbers of employees
exposed and employee exposure levels.
AFL-CIO and BCTD recommended that written plans describe procedures
that employers will use to limit exposure to employees who are not
performing respirable crystalline silica-related tasks (Document ID
4204, p. 63; 4223, p. 82). Similarly, BAC stated that the written plan
should contain provisions for a regulated area (Document ID 2329, p.
5). USW requested the written plan address labeling of areas with
potential respirable crystalline silica exposure (Document ID 2336, p.
14).
Paragraph (g)(1)(iv) of the standard for construction reflects
OSHA's agreement that written exposure control plans must address
limiting exposure to construction employees who are not engaged in
respirable crystalline-silica-related tasks. However, as explained in
the summary and explanation of Regulated Areas, regulated areas are not
required in the standard for construction because most employers are
expected to rely on the specified exposure control methods in Table 1
of paragraph (c) and, therefore, will not have air monitoring data to
estimate boundaries of the regulated area. In the summary and
explanation of Regulated Areas, OSHA also acknowledges the
impracticality of demarcating regulated areas in many construction
scenarios. Nonetheless, it remains crucial that access to high-exposure
areas and employee exposure levels be limited at construction
worksites. A written description of the employer's plan for limiting
access is another tool the employer has that helps to consistently
control hazards.
The exposure control plans in the ASTM standards do not
specifically call for procedures used to restrict access. However, they
do call for a description of administrative controls used to reduce
exposures (Document ID 1466, p. 2; 1504, p. 2). An example of an
administrative control that can be used to minimize the number of
employees exposed to respirable crystalline silica is scheduling high-
exposure tasks when others will not be in the area (Document ID 3583,
Tr. 2385-2386). For example, Anthony Zimbelman stated that when granite
countertops are being installed, silica dust may be generated when
drilling holes for plumbing fixtures or grinding to make adjustments,
but the installers are usually the only employees at the job site at
that time (Document ID 3521, pp. 6-7). CISC stated that in lieu of
developing a written access control plan, employers could instruct
employees to stay out of areas where dust is generated or, if employees
have to be in those areas, to avoid dust clouds (Document ID 2319, pp.
91-92). OSHA considers the CISC recommendation to be an additional
example of administrative controls for limiting access or exposures
that could be addressed in the written exposure control plan.
Similarly, a written exposure control plan could include guidance
requiring employees to maintain a safe distance from dust created by
the use of explosives in demolition and to stay out of the affected
area until the dust sufficiently dissipates; this would also serve as
an acceptable administrative control. Therefore, a requirement for the
written plan in the construction standard to address minimizing the
number of employees exposed and their exposure levels is consistent
with the exposure control plans in the ASTM standards.
OSHA concludes that the written exposure control plan for the
construction standard must address restricting access of those
employees who are not engaged in tasks that generate respirable
crystalline silica (i.e., bystanders). Therefore, as noted above,
paragraph (g)(1)(iv) of the standard for construction requires a
description of the procedures used to restrict access to work areas,
when necessary, to limit the number of employees exposed and their
exposure levels, including exposures generated by other employers or
sole proprietors (i.e., self-employed individuals). Restricting access
is necessary where respirator use is required under Table 1 or an
exposure assessment reveals that exposures are in excess of the PEL.
The competent person, who is designated by the employer to implement
the written exposure control plan under paragraph (g)(4) of the
standard for construction, could further identify situations where
limiting access is necessary. For example, limiting access may be
necessary when an employer or sole proprietor exposes another company's
employees to respirable crystalline silica levels that could reasonably
be considered excessive (e.g., above the PEL).
Such a situation might occur when an employee engaged in a Table 1
task with fully and properly implemented controls is exposed to clearly
visible dust emissions by an employee or sole proprietor who is
performing a task not listed on Table 1, is not fully and properly
implementing Table 1 controls, or is performing a Table 1 task
requiring a higher level of respiratory protection. In that case, the
competent person would assess the situation to determine if it presents
a reasonably anticipated hazard, and if it does, take immediate and
effective steps to protect employees by implementing the procedures
described in the written exposure control plan. Actions by the
competent person could include reminding employees to stay out of the
areas where respirable crystalline silica is being generated or
repositioning employees so that they will not be exposed to respirable
crystalline silica.
This approach is consistent with current industry practices. For
example, Anthony Zimbelman testified that in his experience,
implementing a safety plan was sufficient to protect employees in
situations where subcontractors that are not required to comply with
the Occupational Safety and Health (OSH) Act are working alongside
employees. Mr. Zimbelman further testified that in the home building
industry, this situation does not happen often and contractors would
stop working with a subcontractor who does not comply with OSHA
standards (Document ID 3587, Tr. 3547-3549). OSHA expects that
excessive exposures created by sole proprietors not covered by the
respirable crystalline silica rule will be an infrequent occurrence
because, as CISC indicated in its post-hearing brief, employers and
general contractors will likely demand that everyone on the site follow
regulatory requirements (Document ID 4217, Appendix B, p. 16). OSHA
thus expects that the employers or their competent persons will work
with general contractors of construction sites to avoid high exposures
of employees working alongside others generating respirable crystalline
silica. For example, the competent person could ask the general
contractor to schedule high-exposure tasks when employees will not be
in the area.
OSHA is not retaining the proposed requirement in the written
access control plan that the employer describe how employees will be
notified about respirable crystalline silica exposures and how areas
will be demarcated. The requirements of the written exposure control
plan are more performance-oriented to permit each employer to address
unique scenarios of worksites. Demarcation (i.e., direct access
control), notifying or briefing employees, and scheduling high-exposure
tasks when others are not around, are likely to be the most common
methods of restricting access. Demarcating areas is not required
because, as noted above, it is not applicable to many construction
scenarios. However, if it is possible to demarcate areas, such as by
posting a warning sign, and that is the employer's chosen method for
limiting access or exposures, it must be described in this section of
the written exposure control plan. If notifying or briefing employees
is the method chosen to limit access or exposures, the procedures for
doing that must be described under this section of the written exposure
control plan.
As noted above, the standard for general industry and maritime does
not require the written exposure control plan to address how access to
high-exposure areas or employee exposures will be limited. As described
in more detail in the summary and explanation of Regulated Areas, OSHA
concludes that establishing regulated areas is reasonable and generally
feasible in general industry and maritime workplaces. Therefore, the
standard for general industry and maritime clearly specifies
establishment of regulated areas that are demarcated and have warning
signs posted at the entrances to those areas (paragraph (e)(1) and
(2)(i) and (ii)). With the procedure clearly laid out in the standard,
there is no reason to address it in the written exposure control plan.
However, employers can address more than the minimum requirements for a
written exposure control plan, and general industry and maritime
employers always have the option of describing methods for limiting
access in their written exposure control plan.
The proposed written access control plan called for a description
of the methods that employers at multi-employer sites would use to
notify other employers about the presence and location of areas where
respirable crystalline silica may exceed the PEL and any precautionary
methods needed to protect employees. AFL-CIO, BAC, and BCTD commented
that written plans should provide for a method of communication at
multi-employer sites (Document ID 4204, pp. 62-63; 4219, pp. 25-27;
4223, pp. 83-84). BCTD stated that a requirement for a written plan to
describe methods of communication at multi-employer sites was not
sufficient and requested that employers also be required to give their
written plan to a general contractor or other "controlling employer"
at a multi-employer construction site. The controlling employer would
be required to share that information with other employers or use the
plan to coordinate activities to reduce exposures to employees
(Document ID 4223, pp. 118-123). AFL-CIO and BAC endorsed BCTD's
approach and/or recommended a similar method for using the written
exposure control plan to communicate at multi-employer worksites
(Document ID 4204, p. 63; 4219, pp. 25-27). Similarly, ASSE stated that
employers who generate respirable crystalline silica exposures at
multi-employer sites should inform the general contractor or host
employer about the need for access control and work cooperatively with
the general contractor or host employer to ensure compliance and notify
other employers at the site (Document ID 2339, p. 8).
In contrast, NSSGA commented that the HCS already requires
employers to establish methods for communicating hazards to employees
of other employers (Document ID 2327, Attachment 1, p. 11). NAHB
commented that "...the imposition of multi-employer burdens in the
proposed rule is inconsistent with the clear wording of Sec.
1910.12(a) requiring a construction employer to protect `each of his
employees engaged in construction work' (Emphasis added)" (Document ID
2296, pp. 27-28). OSHA disagrees that a requirement to communicate the
presence of crystalline silica to other employers contradicts the 29
CFR 1910.12(a) requirement that employers protect their employees.
Communication among employers about areas where respirable crystalline
silica exposures may exceed the PEL will provide each employer with the
information needed to protect its own employees.
OSHA nonetheless concludes that the written exposure control plan
need not specify communication methods at multi-employer sites, or
require that employers share their written exposure control plans at
multi-employer sites. Communication at multi-employer worksites is
already addressed in the HCS. As part of the written hazard
communication program required under the HCS, employers who use
hazardous chemicals in such a way that employees of other employers may
be exposed must include specific information in the written hazard
communication program. This includes methods the employer will use to
inform the other employers of any precautionary measures that need to
be taken to protect employees (29 CFR 1910.1200(e)(2)(ii)). Because the
provisions for a written hazard communication program under the HCS
already require employers to share relevant information on hazards and
protective measures with other employers in multi-employer workplaces,
OSHA does not find it necessary to restate a requirement for sharing of
information between employers in the respirable crystalline silica
rule. However, as discussed above, written exposure control plans are
useful for communicating information, and employers may decide that
they are a convenient way for sharing information with other employers
at multi-employer workplaces.
Additional provisions that were part of the proposed access control
plan but are not required for the written exposure control plan are
procedures for providing employees and their designated representatives
an appropriate respirator, protective clothing, or a means for cleaning
clothing when entering areas where exposures exceed the PEL or where
clothing could become grossly contaminated with finely divided
material. OSHA is not requiring the written exposure control plan to
address this subject because procedures related to providing employees
with appropriate respirators, such as selection of respirators, medical
evaluations, and training, must already be described in a written
respiratory protection program (29 CFR 1910.134(c)(1)). In most cases,
the designated representative, who requires entry into a regulated area
or an area with restricted access for purposes such as observing air
monitoring, is likely to have access to appropriate respiratory
protection and be medically cleared to wear it (see summary and
explanation of Exposure Assessment). As OSHA determined in the summary
and explanation of Exposure Assessment, requirements of the written
respiratory protection program related to providing an appropriate
respirator would also apply to the designated representative in the
very rare case where the representative does not have a respirator.
Protective clothing is not addressed in the written exposure control
plan because it is not required by the rule. Recommendations concerning
cleaning of clothing, such as not using compressed air, could be
addressed as part of housekeeping measures or work practice controls.
Some commenters requested that written plans address additional
topics and requirements. For example, Public Citizen, BCTD, and AFL-
CIO, requested that the written exposure control plan describe exposure
assessment methods or programs (e.g., air monitoring or objective data)
and results (Document ID 2249, pp. 3-4; 2371, Attachment 1, p. 16;
4204, p. 62; 4223, p. 82). Public Citizen indicated that this should
include detailed descriptions of analytical methods and air sampling
protocols or objective exposure assessment methods, and BCTD stated
that employers using Table 1 could indicate the portion of Table 1 upon
which they are relying (Document ID 2249, pp. 3-4; 4223, p. 82). BCTD
and AFL-CIO recommended that the written plan address respiratory
protection, medical surveillance, and training programs, including
documentation that employees have received respiratory fit testing,
medical evaluations or examinations, and training (Document ID 4204, p.
62; 4223, p. 82). Public Citizen requested that the plan be prepared by
a technically qualified person if the employer lacks the expertise to
prepare and implement the plan (Document ID 2249, p. 4). ASSE preferred
that the plans be developed by a certified safety professional or
certified industrial hygienist (CIH) (Document ID 2339, p. 8). NAHB
expressed concern about costs if small companies had to hire safety
consultants or industrial hygienists to develop the plan (Document ID
2296, p. 41).
OSHA disagrees with commenters that the written exposure control
plan needs to address these topics. The major purpose of a written
exposure control plan is to ensure that respirable crystalline silica
hazards are consistently identified and controlled. OSHA concludes that
this purpose is best served if the written plan is limited to
information useful for the employer or the employer's designated
representative who will conduct inspections on job sites to ensure that
employees are adequately and consistently protected. Requiring a
written exposure control plan to contain information that is not
directly relevant to identifying and controlling hazards at job sites
would needlessly increase the burdens to employers preparing the
written plans and could make the plans cumbersome for them to use on
job sites. In addition, OSHA does not see the need for including a
description of the respiratory protection program because employers are
already required to develop a written respiratory protection program
under the respiratory protection standard (29 CFR 1910.134(c)).
Recordkeeping requirements are clearly specified for fit testing and
medical evaluations in the respiratory protection standard (29 CFR
1910.134) and for medical examinations and exposure assessments in this
rule. The respirable crystalline silica rule does not require employers
to keep training records. As explained in more detail in the summary
and explanation of Recordkeeping, the rule does not require training
records because employers must instead ensure that employees
demonstrate knowledge and understanding of training subjects and in
addition, such a requirement would increase paperwork burdens for
employers and would not be consistent with the HCS and most OSHA
standards.
Therefore, OSHA is neither requiring nor precluding employers to
include in written exposure control plans descriptions of exposure
assessment methods and results or information on respiratory
protection, medical surveillance, and training programs. Requiring
information, such as highly technical details on analytical methods,
would increase the likelihood that small employers would need to hire a
safety and health professional to develop the plans, thus increasing
the costs and burdens to those employers. Although OSHA encourages
companies to seek professional assistance when needed to develop the
plans, requiring a plan that is so complex that many employers would
not develop it themselves defeats the advantage of employers gaining an
increased understanding of the rule by articulating its requirements.
The additional information may be useful as part of a compliance plan,
and employers have the option to develop such a plan if they find it
helpful.
Paragraph (f)(2)(ii) of the standard for general industry and
maritime (paragraph (g)(2) of the standard for construction) requires
the employer to review and evaluate the effectiveness of the written
exposure control plan at least annually and update it as necessary. A
similar requirement was included in the proposed written access control
plan. Public Citizen requested revisions of written exposure control
plans as needed, including after annual review of exposure assessment
methods (Document ID 2249, p. 4). OSHA agrees with Public Citizen that
the written exposure control plan needs to be periodically reviewed and
updated as needed because work conditions can change (e.g., the
employer purchases a new type of equipment). As discussed above, a
written exposure control plan will not likely need to be updated often
because employees tend to use the same equipment to perform the same
tasks at many locations. However, a yearly review is needed to ensure
that all current scenarios are captured in the plan.
Paragraph (f)(2)(iii) of the standard for general industry and
maritime (paragraph (g)(3) of the standard for construction) requires
that the employer make the written exposure control plan readily
available for examination and copying, upon request, to each employee
covered by this section, his or her designated representative, the
Assistant Secretary (i.e., OSHA), or the Director (i.e., NIOSH). A
similar requirement was included in the proposed written access control
plan. Public Citizen, USW, BCTD, and AFL-CIO requested a requirement to
make written exposure control plans available upon request by employees
or their representatives (Document ID 2249, p. 4; 2336, p. 9; 2371,
Attachment 1, p. 17; 4204, p. 63). NIOSH, Public Citizen, and BAC also
stated that written exposure control plans are a useful way to communicate
protections to employees (Document ID 2177, Attachment B, pp. 16-17;
2249, p. 3; 2329, p. 5). OSHA agrees with commenters that a written
exposure control plan is an effective method for communicating protections
to employees and their designated representatives. Making the written plan
readily available to employees and their designated representatives upon
request empowers and protects employees by giving them and their
representatives the information to question employers if controls are not
fully and properly implemented or maintained. Similarly, making written
exposure control plans readily available to OSHA or NIOSH allows them to
verify effectiveness of employee protections.
BCTD also requested that the rule require employers to address in
their written plans how temporary workers will be protected and that
the rule require staffing agencies and employers who use temporary
staff to share their written exposure control plans (Document ID 4223,
pp. 83-84). OSHA disagrees with BCTD that the rule needs to include a
requirement for host employers and temporary staffing agencies to share
their written exposure control plans with each other. However, OSHA
agrees with the importance of ensuring that temporary workers receive
the protections they are entitled to under the OSH Act. As BCTD noted
in its comments, OSHA addresses the issue of temporary employee
protections in its July 15, 2014, memorandum titled Policy Background
on the Temporary Worker Initiative (Document ID 4223, p. 84). The
policy memorandum indicates that both the host and staffing agency are
responsible for the health and safety of temporary employees and
encourages compliance officers to review written contracts between the
staffing agency and host employer to determine if they have fully
addressed employee health and safety. For example, the policy
memorandum indicates that host employers are well suited for assuming
responsibility for compliance related to workplace hazards, while
staffing agencies may be best positioned to provide medical
surveillance. The memorandum also states that although the host
employer has the primary responsibility for assessing hazards and
complying with occupational safety and health rules in his or her
workplace, staffing agencies must also ensure that they are not sending
employees to workplaces where the employees would be inadequately
protected from or trained about hazards. A temporary staffing agency
could review a host employer's written exposure control plan to verify
that the employer has identified hazards and is implementing the
appropriate controls. Staffing agencies and host employers would have
the option to supplement their written contract with a written exposure
control plan if that is useful for them. OSHA is not requiring that
host employers and staffing agencies share written exposure control
plans for respirable crystalline silica because sharing information is
an issue that affects all OSHA safety and health regulations and is
therefore most efficiently addressed through general policy statements.
Competent Person (Construction). In paragraph (b) of the standard
for construction, OSHA defines competent person as an individual who is
capable of identifying existing and foreseeable respirable crystalline
silica hazards in the workplace and who has authorization to take
prompt corrective measures to eliminate or minimize them. The
definition also specifies that the competent person have the knowledge
and ability necessary to fulfill the responsibilities set forth in
paragraph (g). In paragraph (g)(4) of the standard for construction,
the employer is required to designate a competent person to make
frequent and regular inspections of job sites, materials, and equipment
to implement the written exposure control plan.
OSHA included a competent person requirement in the draft general
industry/maritime and construction standards presented for review to
the Small Business Regulatory Enforcement Fairness Act (SBREFA) review
panel. In the draft standards submitted for SBREFA review, duties of
the competent person included evaluating workplace exposures and the
effectiveness of controls, implementing corrective measures to maintain
exposures at or below the PEL, establishing and maintaining boundaries
of regulated areas, and evaluating alternate media for abrasive
blasting operations. Small entity representatives (SERs) from the
construction industry who reviewed the SBREFA draft standard found the
requirements for a competent person hard to understand, reasoning that
(1) the competent person required a high skill level, (2) a large
proportion of their employees would need to be trained, and (3) the
requirements would be costly and difficult to comply with (78 FR at
56443-56444).
OSHA's Advisory Committee on Construction Safety and Health
(ACCSH), made up of representatives of employees, employers, and state
and federal governments, recommended that the Agency retain a competent
person requirement in the proposed construction standard because many
OSHA standards include that requirement, it is an accepted approach for
construction, many small construction employers do not have full-time
health and safety staff, it can ensure that designated employees get
training on hazards and proper use of controls, and it can increase
confidence that controls and PPE are being used and maintained
correctly (Document ID 4073, Attachment 14g, pp. 2-3).
OSHA included a competent person provision in the proposed
standards, but the only duty that OSHA proposed for the competent
person was identifying areas where respirable crystalline silica
concentrations are, or could reasonably be expected to be, in excess of
the PEL when the employer chose to develop a written access control
plan in lieu of establishing regulated areas. OSHA proposed this
limited competent person duty because the Agency thought that
provisions of the proposed standard, such as requirements for
engineering controls and work practices to reduce and maintain employee
exposure to respirable crystalline silica at or below the PEL, would
effectively communicate the requirements of the rule, without
involvement of a designated competent person. However, the Agency was
aware that competent person requirements have been included in other
health and safety standards and that some parties thought such
requirements would be useful in the silica rule (78 FR at 56443-56444).
Therefore, OSHA requested comments regarding the appropriateness of the
limited competent person requirement, whether a competent person
provision should be included, and if the proposed duties for a
competent person should be modified or deleted (78 FR at 56288).
Many commenters representing labor unions and employee health
advocate groups disagreed with OSHA proposing to include only a limited
role for the competent person in construction. Commenters such as
NIOSH, the Laborers' Health and Safety Fund of North America (LHSFNA),
ASSE, IUOE, and BCTD supported an expanded competent person role
because many construction companies are small and cannot afford safety
or health professionals, but as NIOSH stated, small companies can have
trained and authorized employees ensure employee protections (Document
ID 3403, p. 4; 3589, Tr. 4256-4257; 4201, pp. 2-3; 4025, Attachment 1,
p. 2; 4223, pp. 107-109). OSHA estimates that approximately 93 percent
of construction companies covered by the respirable crystalline silica
standard have fewer than 20 employees (see Chapter III of the Final
Economic Analysis and Final Regulatory Flexibility Analysis). In further
explaining why a competent person is needed in construction, Dr. Schulte
testified:
The need for expanding the duties of the silica-competent person
is especially important when employers plan to rely on Table 1
because it is less likely that an industrial hygienist will visit
the project to evaluate the job, collect air samples, or check the
effectiveness of controls. Effectiveness deteriorates when controls
or personal protective equipment (PPE) are not maintained; this
performance degradation may not be obvious to workers using the
devices (Document ID 3403, p. 4).
The American Industrial Hygiene Association (AIHA), IUOE, and BCTD
agreed that a competent person is needed to ensure that Table 1
controls are functioning effectively (Document ID 3578, Tr. 1030; 3583,
Tr. 2347; 4223, pp. 109-110). BCTD stated:
...because the technology for controlling silica exposures
largely consists of equipment that is attached to or directed at the
tools the workers use in their silica-generating tasks, the manner
in which it is deployed and maintained is critical to its success.
Thus, whether these controls are effective depends on successfully
combining the engineering controls with work practices: Accurately
assessing the potential exposures, selecting the proper control for
the job, using the equipment properly, and making sure the equipment
is functioning effectively. All of this must be done on an on-going
basis (Document ID 4223, p. 109).
Exposure variability in construction is another reason that
commenters cited in support of expanded competent person duties. For
example, ASSE commented that varying silica exposures can occur as a
result of wind pattern and geological changes as contractors move from
one site to another or to a new area at the same site (Document ID
4201, p. 2). LHSFNA explained that a competent person can help to
reduce exposure variability by identifying major sources of variability
and ensuring that controls are used and maintained effectively
(Document ID 4207, p. 4). Similarly, NIOSH stated that a competent
person could reduce exposure variability by recognizing sources of
variability, such as tasks done in an enclosed area or equipment that
is not working correctly (Document ID 3579, Tr. 175-176, 194-195). In
explaining how a competent person could reduce exposure variability,
Kyle Zimmer, Director of Health and Safety for IUOE Local 478,
testified that the competent person could respond to changing
conditions by repositioning equipment so that employees are upwind of
the dust created, adjusting water controls based on environmental
factors, or addressing an unexpected encounter of a concrete sub-base
during asphalt milling (Document ID 3583, Tr. 2351-2352).
Commenters also addressed a competent person's role regarding
bystanders (i.e., employees working nearby other employees who are
engaged in tasks that generate respirable crystalline silica but are
not themselves engaged in those tasks). BCTD commented that the
potential for bystander exposure is another reason why competent
persons are needed in construction (Document ID 4223, p. 110). Hearing
participants described how a competent person could minimize bystander
exposure. For example, Travis Parsons, Senior Safety and Health
Specialist for LHSFNA, stated that the competent person could ensure
communication about exposures being generated between employees from
different trades working at the same construction site (Document ID
3589, Tr. 4232). Donald Hulk, Safety Director for Manafort Brothers,
Inc. and representing IUOE, testified that a sufficiently trained
competent person would be able to recognize when secondary exposures
could occur, and in those situations, subcontractors might be able
reschedule activities to avoid bystander exposures (Document ID 3583,
Tr. 2385-2386).
Another reason why commenters stated that a competent person is
needed in construction is because they thought that employers are not
adequately recognizing respirable crystalline silica-related health
hazards. As evidence that employers do not believe that respirable
crystalline silica is an issue, Chris Trahan, CIH, representing BCTD,
pointed to the volume of testimony claiming that declining silicosis
mortality rates are evidence that silicosis is not a problem and that
respirable crystalline silica is an "alleged carcinogen." Ms. Trahan
disagreed with these commenters and said their testimony demonstrates
the hurdles that the industry must overcome before silica is recognized
as a hazard and controlled (Document ID 3581, Tr. 1641-1642; 4223, pp.
108-109). LHSFNA claimed that most contactors have not adequately
addressed respirable crystalline silica-related health hazards because
of the long latency of silica-related disease compared to the common
short tenure of employment at any one company. LHSFNA commented that
this blunted the ability of workers' compensation to provide an
incentive for disease prevention (Document ID 4207, p. 3). In support
of the importance of a competent person for preventing disease, LHSFNA
and BCTD pointed to the following statement in the AIHA White Paper on
competent persons (Document ID 3589, Tr. 4199; 4223, p. 106).
A key component in preventing overexposure to silica and
subsequent disease is to have at least one individual on the jobsite
who is capable of recognizing and evaluating situations where
overexposure may be occurring; who knows how to evaluate the
exposure potential; and who can make an initial recommendation on
how to control that exposure. This is the role of the silica
competent person (Document ID 4076, p. 3).
Commenters stressed that the competent person is a well-known
concept in construction. LHSFNA and BCTD commented that requiring a
competent person under the silica regulation maintains consistency with
19 OSHA construction standards (Document ID 4207, p. 3; 4223, p. 107).
Standards requiring a competent person include asbestos (29 CFR
1926.1101), lead (29 CFR 1926.62), and cadmium (29 CFR 1926.1127)
(Document ID 4223, p. 107). In addition, NIOSH and LHSFNA commented
that competent person provisions are commonly included in American
National Standard Institute (ANSI) standards for construction (Document
ID 2177, Attachment B, p. 8; 3589, Tr. 4200). NIOSH further said that
it and its state partners routinely recommend the need for, and role
of, designated competent persons in investigation reports conducted
under NIOSH's Fatality Assessment and Control Evaluation program
(Document ID 2177, Attachment B, p. 8).
The competent person requirement is also consistent with
construction industry practices. For example, Donald Hulk testified
that at Manafort Brothers construction sites, a highly trained person
has the authority to ensure that best practices are implemented
(Document ID 3583, Tr. 2380). Anthony Zimbelman testified that owners
or competent persons of subcontracting companies conduct assessments
and develop procedures for controlling dust before remodeling or
construction of homes (Document ID 3587, Tr. 3538-3539). Safety
Director Francisco Trujillo from Miller and Long, Inc. testified ". .
. we have competent persons for almost everything..." and explained
that competent persons are required to evaluate the adequacy of protective
equipment when dust collection systems are used because of the limitations
of those systems and changing site conditions
(Document ID 3585, Tr. 2963-2964, 2980).
Specific duties for a competent person were recommended by a
diverse group of commenters, including AIHA, NIOSH, National Asphalt
Pavement Association (NAPA), IUOE, National Rural Electric Cooperative
Association (NRECA), retired occupational safety and health attorney
Charles Gordon, LHSFNA, and BCTD (Document ID 2169, p. 5; 2177,
Attachment B, pp. 9-10, 14; 2181, pp. 10-11; 2262, pp. 38-39, 42-43;
2365, pp. 19-20; 3588, Tr. 3800-3801; 3589, Tr. 4197-4201; 4223, pp.
106-114). BCTD, which had among the most extensive recommendations,
noted that OSHA standards for lead, asbestos, and cadmium specify
duties for a competent person (Document ID 4223, p. 112). For the
respirable crystalline silica standard, BCTD requested that the
employer designate a competent person to be on site whenever work
covered by the standard is being conducted to ensure that the
employer's written exposure control plan is implemented, and to:
...use the written exposure control plan to identify locations
where silica is present or is reasonably expected to be present in
the workplace prior to the performance of work. In addition the
competent person's duties shall include ensuring: (1) The employer
has assessed the exposures as required by this section; (2) where
necessary, regulated areas are established and access to and from
those areas is limited to authorized persons; (3) the engineering
controls and work practices required by this standard, including all
elements of Table 1 (if it is being used), are fully and properly
implemented, maintained in proper operating condition, and
functioning properly; (4) employees have been provided with
appropriate PPE, including respiratory protection, if required; and
(5) that all employees exposed to silica have received the
appropriate silica training...(Document ID 4223, p. 113).
NIOSH recommended similar duties in addition to indicating that the
competent person should assure proper hygiene to prevent employees from
taking home silica dust on clothing and to conduct daily checks of
engineering controls and respirators in abrasive blasting operations
involving sand (Document ID 2177, Attachment B, pp. 9-10, 14). IUOE
stated that the competent person could assist with employee training,
ensure good housekeeping in heavy equipment cabs, and assume
responsibility for exposure assessments (Document ID 2262, p. 41; 3583,
Tr. 2369-2370; 3583, Tr. 2345). NISA stated that a competent person
could conduct qualitative objective exposure assessments or determine
frequency of exposure estimates under the performance option (Document
ID 2195, pp. 35-36).
CISC opposed a requirement for a competent person and stated that
thorough training eliminated the need for a competent person and access
control plan (Document ID 4217, pp. 25-26). In disputing the value of
expanding the competent person role in the standard, CISC claimed that
the ubiquitous presence of silica in construction precluded the need
for a designated person who is capable of identifying existing and
predictable respirable crystalline silica hazards and has authorization
to take prompt corrective actions (Document ID 2319, p. 127).
Commenters also addressed the practicality of a competent person
requirement. IUOE commented that an employer would not need to hire
additional personnel to serve as silica competent persons because they
could designate a competent person to oversee more than one
construction activity or task, as long as that person is able to
identify existing and predictable hazards and is authorized to take
prompt corrective action (Document ID 4234, Part 3, pp. 62-63). In
contrast, CISC commented that requiring a competent person at all
construction sites is not realistic for small companies and pointed to
testimony from Kellie Vazquez, Vice President of Holes Incorporated, as
an example (Document ID 4217, pp. 26-27). Ms. Vazquez testified:
...my guys are one-man crews. So I will have one operator in a
truck and that truck is loaded with his equipment to go do his
multiple jobs per day. He is his own operator, his own equipment
operator, his own supervisor, his own foreman. He has the right to
shut down any job he feels that is not safe. I don't have a second
man, or a competent person, or a supervisor go with him on site to
look at the job and verify if it is safe or not. That's his
responsibility. That's what he is trained to do. My operators have
30-hour OSHA [training]. They are trained in trenching and
excavation. They are competent people in trenching and excavation.
They are scaffold builders. They get aerial lift trained (Document
ID 3580, Tr. 1389).
OSHA observes that the description of Ms. Vazquez's employees is
consistent with the definition of a competent person for safety issues
(i.e., extensive training on safety issues and the authority to close
down a job site if they feel that it is not safe), and Ms. Vazquez
admitted that her employees are already competent persons in trenching
and excavation. It is likely that her employees already have the
knowledge to fully and properly implement controls on the tools they
use and recognize if they are not functioning properly. With the
training required under paragraph (i) of the standard for construction
and the authority to take corrective actions, those employees could be
designated as competent persons for respirable crystalline silica. OSHA
concludes there is no need to designate a separate competent person in
that situation.
In addition, any prompt corrective measures that competent persons
would take to eliminate or minimize respirable crystalline silica
hazards would likely have minimal impact on work activities in most
cases. Such measures might include briefly stopping work to clear a
clogged water line on a tool with wet method controls or clean a filter
on a tool with vacuum controls if the competent person sees signs that
controls are not functioning effectively. OSHA concludes that even for
small businesses, a competent person requirement will not be unduly
burdensome because knowledgeable employees, who will already be on
site, can be designated as competent persons.
OSHA concludes that the ubiquitous presence of respirable
crystalline silica and the many variables that can affect employee
exposure when performing construction tasks justify a requirement for a
competent person in construction, who is not only trained to identify
and correct respirable crystalline silica hazards, but also is
authorized to take immediate corrective actions to eliminate or
minimize them.
Exposures and hazards can vary according to environmental
conditions such as wind and humidity, geological profile of soil, if
work is performed indoors or outdoors, or how well exposure controls
are maintained. Consequently, there is an obvious need for a competent
person to frequently inspect the construction job site, identify
respirable crystalline silica hazards, and verify that effective
control measures are being used. Site assessment is a continuous
process because of changing environmental and work conditions as a
construction job is being completed. In cases where the competent
person is the only person from his or her company on a job site,
frequent inspections of the job site would equate to continuous
assessment of variables associated with the job that the competent
person is conducting (e.g., signs that the controls are not functioning
effectively, a change in weather condition that might require an
adjustment of controls, or moving from an outdoor area to an enclosed
area).
Therefore, paragraph (g)(4) of the standard for construction requires
an employer to designate a competent person to make frequent and
regular inspections of job sites, materials, and equipment to implement
the written exposure control plan. OSHA concludes that the uniqueness
and complexity of scenarios on construction sites justify the
designation of a competent person.
OSHA agrees with commenters that a competent person is needed in
construction because employers who use the specified exposure control
methods in Table 1 are not required to conduct exposure assessments and
because large numbers of small construction companies do not typically
employ health and safety professionals. Another reason for including a
competent person provision in the construction standard is because at
multi-employer worksites, the actions of one employer may expose
employees of other employers to hazards. For these reasons, OSHA agrees
with ACCSH and commenters from NIOSH, labor unions, and employee health
advocate groups that a requirement for a designated competent person is
needed and will improve employee protections in construction.
In addition, as noted above, a requirement for a competent person
is consistent with OSHA substance-specific standards for construction,
such as lead (29 CFR 1926.62), asbestos (29 CFR 1926.1101), and cadmium
(29 CFR 1926.1127). OSHA's general safety and health provisions for
construction require the employer to initiate and maintain programs for
accident prevention, as may be necessary, and such programs require
frequent and regular inspections of job sites, materials, and equipment
by a designated competent person (29 CFR 1926.20(b)(1) and (2)).
Designating a competent person is consistent with current construction
industry practices because, as the record indicates, employers in the
construction industry are already using competent persons.
OSHA is requiring that the competent person implement the written
exposure control plan because, as discussed above, the plan specifies
what must be done to consistently identify and control respirable
crystalline silica hazards on a job site. In construction, a competent
person is needed to ensure that the requirements of the written
exposure control plan are being met under variable conditions. The
subjects that must be described in the written exposure control plan
for construction--tasks involving exposure to respirable crystalline
silica; engineering controls, work practices, and respiratory
protection; housekeeping methods for limiting exposure; and procedures
for restricting access when needed to minimize exposures or numbers of
employees exposed--are consistent with the duties of a competent person
suggested by representatives from NIOSH, labor unions, employee health
advocates, and some industries. Therefore, having the competent person
implement the written exposure control plan is consistent with many of
the competent person duties recommended by commenters. It also makes
the competent person requirements easy to understand.
Implementation of the written exposure control plan does not
address every competent person duty that was recommended by commenters,
such as training or specific duties related to abrasive blasting with
sand. OSHA is not mandating that the competent person conduct training
because training could, in many cases, be performed by other
individuals. For example, ensuring that an employee can demonstrate
knowledge and understanding of health hazards, contents of the rule,
and medical surveillance, and providing the employee with any needed
training, may be better addressed by an individual other than the
designated competent person, or at another location before the employee
reports to the job site. A competent person could use the written
exposure control plan to recognize employees who are not knowledgeable
about full and proper implementation of controls or work practices and
take appropriate action, such as reminding them of proper practices or
recommending additional training to the employer.
The standard does not specify a duty for the competent person
regarding abrasive blasting with sand, but unique aspects of that
operation, such as more frequent checks of controls, could be specified
in the written exposure control plan. OSHA reasons that evaluating
alternate media for use in abrasive blasting, as was recommended in the
draft standard for SBREFA, requires specialized knowledge in toxicology
or a related science, and is thus beyond the knowledge of a typical
employee who would be designated a competent person and unduly
burdensome to employers. Also, as discussed in the summary and
explanation section of Methods of Compliance, OSHA recognizes that
alternative media may present health risks. Other duties that
commenters recommended, such as conducting exposure assessment, are
usually done by professionals such as industrial hygienists. Requiring
an industrial hygienist to be on worksites daily would be very
burdensome, especially to small employers. In addition, OSHA expects
the need for exposure assessments in construction to be limited because
most employers will likely rely on Table 1 in paragraph (c) rather than
do exposure assessments, based on the number of comments OSHA received
about exposure assessments being impractical in construction (see
summary and explanation of Exposure Assessment).
In its prehearing comments, BCTD also requested that the exposure
control plan list the identity of the competent person (Document ID
2371, Attachment 1, pp. 16-17). OSHA is not requiring that the written
exposure control plan include the identity of the competent person
because it is both impractical and unnecessary. Construction companies
could have more than one designated competent person because they need
a backup competent person or they have jobs being conducted at various
construction sites. Therefore the identity of the competent person
could change from day to day if employees work at different job sites,
or if a backup person is sent to a particular job site. However, it is
important for employees to be able to identify the competent person.
Therefore, OSHA is requiring that employers covered by the standard for
construction notify employees about the identity of the competent
person as part of the training provision under paragraph (i)(2)(i)(E).
OSHA expects this could simply involve announcing the identity of the
competent person at the start of each work shift.
As stated above, paragraph (b) (Definitions) of the standard for
construction specifies that the competent person have the knowledge and
ability necessary to fulfill his or her responsibilities. The proposed
rule did not specify particular training requirements for competent
persons. Rather, the requirement for a competent person was
performance-based in that the competent person needed to be capable of
effectively performing the duty assigned under the standard, which was
to identify, in advance, areas where exposures were reasonably expected
to exceed the PEL. In the standard for construction, the duties of the
competent person have been expanded, and expanded training requirements
for the competent person therefore need to be considered.
OSHA received many comments regarding knowledge and competencies
for a competent person. IUOE recommended inclusion of specific training
requirements for competent persons in the standard for construction
because it thought that without them, competent persons may not get the
training needed to train employees in the implementation and
maintenance of controls or understand and adjust to variables that
affect exposures, smaller employers might not understand the scope of
appropriate training, employers might avoid expenditures for
appropriate training, and the standard would be more difficult to
enforce (Document ID 4234, Part 2, p. 52). IUOE summarized one case
concerning an occupational fatality resulting from inadequate training
or knowledge and other cases supporting specific training for competent
persons (Document ID 4234, Part 2, pp. 55-56). ASSE cautioned that many
OSHA standards do not specify parameters for determining competency and
referred to the challenges in judging competency when litigating
citations (Document ID 4201, pp. 4-5).
NIOSH requested that OSHA require competency training, as it did
for asbestos (29 CFR 1926.1101(o)(4)), and list requirements for
silica-specific training and capabilities for competent persons in the
standard or an appendix of the standard. NIOSH further stated that
"OSHA could consider allowing appropriate experience to qualify (e.g.,
learning by apprenticing to a trained silica-competent person)." NIOSH
noted that such an approach is consistent with the ANSI A10.38 standard
that defines a competent person based on specific education, training,
or experience (Document ID 2177, Attachment B, p. 9).
IUOE, ASSE, LHSFNA, and BCTD endorsed the competency objectives set
forth in an AIHA White Paper as a minimum body of knowledge for a
silica competent person (Document ID 4201, p. 6; 4207, p. 3; 4223, pp.
113-114). BCTD requested that the White Paper be included as a non-
mandatory appendix to the rule (Document ID 4223, pp. 113-114). The
AIHA White Paper indicates that a silica competent person can
demonstrate competency by completing a training course addressing the
criteria in the White Paper or successfully demonstrating the
capabilities described in the White Paper through training or direct
job experience. The competency objectives listed in the AIHA White
Paper include an understanding of (a) the role of a competent person;
(b) what silica is and where it is found; (c) silica hazards and
exposures, occupational exposure limits, and regulations; (d) how to
determine if silica is present through bulk sample analyses, safety
data sheets, or material checklists; (e) exposure ranges for common
construction tasks in the absence of controls and under conditions that
can result in higher exposures, and recognition of situations when a
qualified person needs to be called in; (f) effective use of controls
to reduce exposures and basic understanding of respiratory protection;
(g) understanding of need for oversight and quality assurance,
including review of exposure monitoring by a qualified person and
communication to other employers on a multi-employer sight; (h)
understanding of OSHA standard; and (i) understanding of authority,
responsibilities and procedures (e.g., resolving safety or health
situations) (Document ID 4076, pp. 4-9).
Commenters further elaborated on training requirements and
competencies for a silica competent person. ASSE requested that OSHA
give clear guidance on what qualifies an individual to be designated a
competent person, asserted that certification in safety or industrial
hygiene should presume competency, recommended similar competency
requirements as the AIHA White Paper, and suggested that OSHA include
training competency requirements in a non-mandatory appendix. ASSE also
noted that the asbestos standard, 29 CFR 1926.1101(o)(4), requires
competent persons to complete an Environmental Protection Agency
course, and although an equivalent course does not exist for
crystalline silica, training to address competencies for a silica
competent person could be added to a 30-hour course for construction
(Document ID 4201, pp. 2-6).
As discussed in detail in the summary and explanation of
Communication of Respirable Crystalline Silica Hazards to Employees,
BCTD requested a tiered approach to training in which the competent
person would receive training necessary to perform his or her duties,
in addition to awareness training for all covered employees and hands-
on training on engineering controls and work practices for employees
performing tasks that generate silica dust (Document ID 4223, pp. 117-
118). IUOE, LHSFNA, and BAC similarly advocated competent person
training as part of a tiered approach and stressed that the competent
person receive site-specific training on engineering controls (Document
ID 2262, pp. 39-40; 4207, p. 5; 4219, p. 24). Tom Nunziata, Training
Coordinator for LHSFNA, stressed that the minimum training for a
competent person should be at least the training required for employees
performing tasks that generate silica dust (Document ID 3589, Tr.
4221). Similar to NIOSH, Travis Parsons testified that experience can
contribute to a competent person's knowledge (Document ID 3589, Tr.
4197-4198).
LHSFNA indicated that competent person training should be tailored
based on needs and exposure potential (Document ID 4207, p. 5). Other
commenters provided numerous examples of unique training requirements
for heavy equipment operators. For example, Gary Fore, retired Vice
President for Health, Safety, and Environment for NAPA, referenced best
practices for inspection of controls on asphalt milling machines by
competent persons and testified that those machines are very
complicated and sophisticated (Document ID 3583, Tr. 2182-2183).
Therefore, training is required to detect issues requiring maintenance,
such as a plugged or inappropriately placed nozzle (Document ID 2181,
p. 10). IUOE commented that a competent person must have the knowledge
to make informed judgments about the potential for silica exposures to
exceed the action level (Document ID 2262, pp. 42-43). Martin Turek,
Assistant Coordinator and Safety Administrator for IUOE Local 150, and
Kyle Zimmer gave several examples of variables that could affect silica
exposures in earth moving tasks, such as weather (e.g., wind, humidity)
and soil compositions and handling (e.g., clay versus rock, distance
soil is dropped from a bucket) (Document ID 3583, Tr. 2351-2352, 2356-
2359). Matt Gillen, Deputy Director of NIOSH's Office of Construction
Safety and Health, testified that a competent person should be able to
recognize variability issues and make changes to address them (Document
ID 3579, Tr. 205-206).
NRECA commented that a competent person for rural electric
utilities should be trained in setting up air monitoring, setting
boundaries for control zones, physical characteristics of crystalline
silica, and PPE such as respirators (Document ID 2365, pp. 19-20).
Francisco Trujillo testified that a competent person should have
knowledge of work processes and their associated hazards and possibly,
some knowledge of previous sampling evaluations to know if employees
might be overexposed (Document ID 3585, Tr. 2980-2981). Upstate Medical
University recommended that the competent person be trained on the
respirable crystalline silica standard, the hierarchy of controls,
exposure determinants, and the written control plan (Document ID 2244,
p. 4).
Ameren Corporation opposed specific training requirements for a
competent person (Document ID 2315, p. 2). CISC stated that if OSHA
does include a competent person requirement in the standard, the agency
should not require training because:
An individual's experience, job training, and silica awareness
training, in the CISC's view, will provide the capabilities
envisioned by OSHA for a competent person with respect to
crystalline silica. For silica in construction, the CISC
respectfully believes that no specific training for a "competent
person" is required. Furthermore, the Agency has traditionally not
included specific competent person training requirements in its
construction standards, instead taking a performance-oriented
approach to the requirements and definition. There is nothing unique
about silica that would cause the Agency to deviate from this past
approach (Document ID 2319, pp. 127-128).
OSHA concludes, after consideration of all the comments, that it is
not practical to specify in the rule the elements and level of training
required for a competent person. The Agency does not find it
appropriate to mandate a "one size fits all" set of training
requirements to establish the competency of competent persons in every
conceivable construction setting. Therefore, the training requirement
for a competent person is performance-oriented. This approach is
consistent with most OSHA construction standards, such as cadmium (29
CFR 1926.1127) and lead (29 CFR 1926.62), which include a performance-
based approach by not specifying training or qualifications required
for a competent person.
It is evident from the comments that controlling respirable
crystalline silica exposures involves tailoring controls and work
practices to each particular work setting. Moreover, training is
addressed by the HCS and paragraph (i) of the standard for
construction. The HCS and paragraph (i) require that employees be
trained on subjects that overlap with competencies listed in the AIHA
White Paper. For example paragraph (h)(3)(i) of the HCS (29 CFR
1910.1200) requires training of covered employees on methods to detect
the release of hazardous chemicals (in this case, respirable
crystalline silica). The respirable crystalline silica standard for
construction requires training on health hazards, tasks that could
result in exposures, engineering and work practice controls and
respiratory protection, and the contents of the standard (paragraphs
(i)(2)(i)(A-D)).
OSHA concludes that successful completion of training requirements
in the HCS and the standard for construction impart a high level of
competency to employees. The training focuses on general requirements
that apply to most construction settings and should be sufficient to
provide an employee with the knowledge and ability to be designated a
competent person at some companies. Competent persons might require
more knowledge and training in certain circumstances, but that would
vary widely among construction companies. For example, competent
persons at a small residential construction company might only need
training on controls for power tools that they do not typically use to
perform their own tasks, so that they could assist employees with
questions about or problems with dust controls on those tools. In
contrast, a competent person for heavy equipment tasks may require more
specialized training in heavy equipment inspection or identifying
various soil types to estimate exposure potential. Because companies
covered under the construction standard conduct a wide range of tasks
involving unique scenarios, training requirements will vary widely
among different companies. It is, therefore, the employer's
responsibility to identify and provide any additional training that the
competent person needs to implement the employer's written exposure
control plan.
Finally, a compliance officer could ascertain whether the employer
is in compliance with the competent person requirement by asking
questions to assess whether the competent person has adequate knowledge
to perform his or her duties, such as an understanding of engineering
controls and how to recognize if they are not functioning properly. As
is the case with training of all employees, the employer is responsible
for determining that a competent person is adequately trained and
knowledgeable to perform his or her duties.
Competent Person (General Industry). As part of the proposed
written access control plan, OSHA proposed that a competent person
identify and maintain regulated areas in workplaces covered by the
general industry and maritime standard. AFL-CIO and USW requested
expanded competent person duties and training requirements for general
industry and maritime because a competent person could recognize and
take action to protect employees from high exposures (Document ID 4204,
pp. 58-60; 4214, pp. 14-16). AFL-CIO urged OSHA to reinstate the
competent person duties from the 2003 SBREFA draft standard (Document
ID 4204, pp. 58-60). USW commented that a competent person could ensure
that hazards are recognized, employees receive proper training,
adequate controls and PPE are implemented, and an effective exposure
control plan is developed (Document ID 4214, pp. 14-15). In describing
how a competent person is relevant to general industry, AFL-CIO pointed
to testimony by employees who were trained to evaluate the function of
ventilation systems (Document ID 4204, p. 60). AFL-CIO also asserted
that NIOSH and AIHA urged OSHA to include a competent person
requirement for both general industry and construction (Document ID
4204, pp. 59-60). OSHA examined the AIHA and NIOSH comments referenced
by AFL-CIO and identified only recommendations for a competent person
regarding construction-related topics, such as Table 1 (Document ID
2169, pp. 4-5; 2177, Attachment B, pp. 8-10, 25-26).
OSHA is not requiring a competent person for the general industry
and maritime standard. OSHA has determined that in most cases, general
industry scenarios are not as variable as those in construction. For
example, most work is performed indoors and therefore, not subject to
variables such as wind shifts and moving exposure sources that could
significantly affect exposures or complicate establishment of regulated
areas. In general industry and maritime, controls are not usually built
into tools that require action by the individual employees who use them
to function effectively. The exposure assessments that employers in
general industry and maritime are required to conduct will verify that
controls are functioning effectively. Employers covered under the
general industry and maritime standard are more likely to have health
and safety professionals on staff who could assist with implementation
of the standard. Finally, competent persons have not been included in
other OSHA substance-specific standards for general industry. For
example, a competent person requirement was included in the
construction standard for cadmium because of environmental variability
and the presence of multiple employers on the job site, but a competent
person requirement was not included in the general industry standard
for cadmium (29 CFR 1910.1027; 29 CFR 1926.1127; 57 FR 42101, 42382 (9/
14/1992)). Moreover, as explained in the summary and explanation of
Regulated Areas, establishing regulated areas is reasonable in most
general industry scenarios because employers are required to conduct
exposure assessment and are thus able to determine the boundaries of a
regulated area. Therefore, the general industry and maritime standard
requires regulated areas that are demarcated and posted with warning
signs. This negates the need for a competent person to identify and
maintain regulated areas. These factors explain and support OSHA's
conclusion that there is no regulatory need for including a competent
person requirement in the respirable crystalline silica standard for
general industry and maritime.
Comparison to ASTM Standards. The written exposure control plan is
comparable to the ASTM standards in some respects and different in
others. Section 4.2.6 of ASTM Standard E 1132-06 and Section 4.2.5 of
ASTM standard E 2625-09 recommend written exposure control plans for
areas with persistent overexposures; address engineering, work
practice, and administrative controls; and call for a root cause
analysis to investigate the causes of the overexposure, identify
remedies, and conduct follow-up sampling to verify that exposures are
below the PEL (Document ID 1466, p. 2; 1504, p. 2). The major
difference between the written plans in the ASTM standards and the
written plans in the respirable crystalline silica rule is that the
written plans for the respirable crystalline silica rule are not
limited to overexposure scenarios. The ASTM standards address work
practices and administrative controls, but the written exposure control
plans in the respirable crystalline silica rule further explain what
those practices and controls are (i.e., restricting access as needed
(construction standard only), engineering controls, work practices,
respiratory protection, and housekeeping methods). In addition, the
written exposure control plans in the respirable crystalline silica
rule are implemented by a competent person (construction standard
only), are required to be reviewed and updated at least annually by the
employer, and are to be made available to employees, employee
representatives, OSHA, and NIOSH upon request.
The requirements of the rule for respirable crystalline silica
better protect employees and, therefore, better effectuate the purposes
of the OSH Act of 1970 than the ASTM standards. Because the written
plans are required for all workplaces covered by the rule, they help to
maintain comprehensive and consistent controls, which can prevent
overexposures from occurring. The provision for annual review ensures
that the plans remain effective, and the provision for making the plans
available to employees helps to make employees aware of the protections
they should expect. More details about how the requirements of the rule
better effectuate the requirements of the OSH Act are discussed above.
Medical Surveillance
Paragraph (i) of the standard for general industry and maritime
(paragraph (h) of the standard for construction) sets forth
requirements for the medical surveillance provisions. The paragraph
specifies which employees must be offered medical surveillance, as well
as the frequency and content of medical examinations. It also sets
forth the information that the physician or other licensed health care
professional (PLHCP) is to provide to the employee and employer.
The purpose of medical surveillance for respirable crystalline
silica is, where reasonably possible, (1) to identify respirable
crystalline silica-related adverse health effects so that appropriate
intervention measures can be taken; (2) to determine if an employee can
be exposed to respirable crystalline silica in his or her workplace
without increased risk of experiencing adverse health effects, or in
other words, to determine if an employee has any condition, regardless
of the cause, that might make him or her more sensitive to respirable
crystalline silica exposure; and (3) to determine the employee's
fitness to use respirators. The inclusion of medical surveillance in
this rule is consistent with Section 6(b)(7) of the Occupational Safety
and Health (OSH) Act (29 U.S.C. 655(b)(7)) which requires that, where
appropriate, medical surveillance programs be included in OSHA
standards to determine whether the health of employees is adversely
affected by exposure to the hazard addressed by the standard. Almost
all other OSHA health standards have also included medical surveillance
requirements and OSHA finds that a medical surveillance requirement is
appropriate for the respirable crystalline silica rule because of the
health risks resulting from exposure.
General. Paragraph (i)(1)(i) of the standard for general industry
and maritime requires employers to make medical surveillance available
for employees who will be occupationally exposed to respirable
crystalline silica at or above the 25 [mu]g/m\3\ action level for 30 or
more days per year. Paragraph (h)(1)(i) of the standard for
construction requires employers to make medical surveillance available
to employees who will be required under this section to use a
respirator for 30 or more days per year. Thus, employers are required
to determine if their employees will be exposed at or above the action
level of 25 [mu]g/m\3\ in general industry and maritime, or required to
wear a respirator under the construction standard for 30 or more days
per year (i.e., the next 365 days), and then make a medical examination
available to those employees who meet these criteria under two
scenarios: (1) Within 30 days of initial assignment, unless the
employee has had a current examination that meets the requirements of
this rule within the last three years (paragraph (i)(2) of the standard
for general industry and maritime, paragraph (h)(2) of the standard for
construction) and (2) within three years from the last initial or
periodic examination (paragraph (i)(3) of the standard for general
industry and maritime, paragraph (h)(3) of the standard for
construction). As in previous OSHA standards, both standards are
intended to encourage participation by requiring that medical
surveillance be offered at no cost to the employee and at a reasonable
time and place. Under the "at no cost to the employee" proviso, if
participation requires travel away from the worksite, the employer will
be required to bear the cost of travel, and employees will have to be
paid for time spent taking medical examinations, including travel time.
Some employers and industry representatives questioned the general
need for medical surveillance or expressed their concerns with the
medical surveillance requirement. For example, OSCO Industries, Inc.
argued that medical surveillance would not identify many employees with
silicosis and OSCO Industries and National Association of Home Builders
(NAHB) emphasized the progress that has already been made in
eliminating silicosis (Document ID 1992, p. 11; 2296, p. 43). Fann
Contracting, Inc. stated that medical surveillance is not needed
because employees exposed above the permissible exposure limit (PEL)
are required to wear respirators and they should therefore be protected
(Document ID 2116, Attachment 1, p. 43).
OSHA does not find these comments persuasive. As discussed in
Section VI, Final Quantitative Risk Assessment and Significance of
Risk, OSHA has found that employees exposed to respirable crystalline
silica at the preceding PELs are at significant risk of material
impairment of health. Although the revised PEL of 50 [mu]g/m\3\
substantially decreases risks, the risk remains significant at and
below the PEL, including at the action level of 25 [mu]g/m\3\.
Consequently, even employees exposed at the action level are at
significant risk of developing silicosis and other respirable
crystalline silica-related diseases. Based on these risk assessment
findings, OSHA concludes that silicosis and other respirable
crystalline silica-related illnesses are an ongoing occupational risk.
OSHA expects that those illnesses are likely to be detected as part of
medical surveillance, and the detection of these illnesses will benefit
employees.
Even employees required to wear respiratory protection in high
exposure environments are at risk of developing disease. As OSHA notes
in the summary and explanation of Methods of Compliance, respirators
fully protect employees only if they are properly fitted and maintained
correctly and replaced as necessary; they do not protect employees if
they are not used consistently and properly. The committee that
developed the ASTM International (ASTM) standard, ASTM E 2625-09,
Standard Practice for Controlling Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities, also
concluded that medical surveillance is needed for employees who wear
respirators to ensure that the respiratory protection is working
(Document ID 3580, Tr. 1452). (This requirement is consistent with that
in ASTM E 1132-06, Standard Practice for Health Requirements Relating
to Occupational Exposure to Respirable Crystalline Silica.)
Consequently, OSHA concludes that the requirement for respiratory
protection for exposures exceeding the PEL does not obviate the need
for medical surveillance.
Employers also expressed concern about responsibility for exposures
occurring through other employment or non-occupational sources (e.g.,
environmental exposures) (e.g., Document ID 2116, Attachment 1, pp. 20,
36, 37, 39; 2295, p. 2; 2296, p. 31; 3531, p. 9). Construction Industry
Safety Coalition (CISC) and Holes Incorporated questioned how medical
surveillance would decrease exposures, and Holes Incorporated stated it
would not prevent the onset of silicosis (Document ID 2319, p. 116;
2338, p. 6).
OSHA stresses that the main purposes of medical surveillance are
early detection of disease related to respirable crystalline silica
exposure so appropriate intervention methods can be taken, to let
employees know if they have a condition that might make them more
sensitive to respirable crystalline silica exposure, and to assess
fitness to wear a respirator. The purpose of medical surveillance is
not to identify which employer is responsible for illnesses resulting
from respirable crystalline silica exposures or must offer financial
compensation. OSHA agrees with the Building Construction and Trades
Department, AFL-CIO (BCTD), which stated that "[e]arly detection of
silica-related medical conditions will enable employees to make
informed decisions about their work, their medical care and their
lifestyles" (Document ID 4223, p. 123). For example, as the American
College of Occupational and Environmental Medicine (ACOEM) and the
National Institute for Occupational Safety and Health (NIOSH) stated,
an early diagnosis allows an employee to consider employment choices
that minimize or eliminate respirable crystalline silica exposure to
decrease the risk of progression or exacerbation of disease (Document
ID 1505, p. 3; 3579, Tr. 257). In another example, an early diagnosis
of silicosis allowed bricklayer Dennis Cahill, representing the
International Union of Bricklayers and Allied Craftworkers (BAC), to
manage his health by getting flu and pneumonia shots, avoiding the
public during cold season, and staying indoors during periods of high
air pollution (Document ID 3585, Tr. 3089, 3104). OSHA finds that
although medical surveillance does not reduce exposures, like
engineering controls do, it is nonetheless an integral component of
this (and most) occupational safety and health standards and important
in its own right for safeguarding the health of employees exposed to
respirable crystalline silica.
OSHA also agrees with the viewpoint expressed so well by Mr.
Cahill, that employees who are knowledgeable about their health risks
will take actions in response to information from medical surveillance.
Such actions will likely benefit not only the employees but also
employers because their employees are likely to be healthier. Members
of the medical community, labor unions, employee health advocate
groups, and industry groups emphasized the value of early detection for
intervention purposes (e.g., Document ID 2080, p. 9; 2178, Attachment
1, p. 2; 2351, p. 15; 3541, p. 1; 3577, Tr. 570-571; 3588, Tr. 3751;
3589, Tr. 4292; 4204, p. 79; 4219, p. 28; 4223, pp. 123-124). In
addition, more than 100 commenters including construction employees,
employee health advocates, medical professionals, and employers or
industry representatives voiced their general support for medical
examinations in the respirable crystalline silica rule (e.g., Document
ID 1771, p. 1; 2030; 2268; 2134, p. 10; 2403; 3294).
Some commenters representing the construction industry questioned
the practicality of medical surveillance for construction employees due
to a number of particular difficulties, such as the short-term nature
and high turnover rate of construction jobs (e.g., Document ID 2116,
Attachment 1, p. 20; 2187, p. 7; 2247, p. 1; 2276, p. 10; 2289, p. 8;
2295, p. 2; 2296, pp. 42-43; 3230, p. 1; 3442, pp. 5-6; 4029, p. 3;
4217, p. 21). For example, American Subcontractors Association and Hunt
Construction Group stated that the difficulty in tracking medical
surveillance in a mobile work force could result in repeated,
unnecessary testing for construction employees (Document ID 2187, p. 7;
3442; pp. 5-6). Kenny Jordan, Executive Director of the Association for
Energy Services Companies (AESC), which represents another industry
with high turnover rates, expressed similar concerns about repeated
testing, although he did not oppose medical surveillance and asked for
a medical record that would follow the employee (Document ID 3589, Tr.
4063). The Laborers' Health and Safety Fund of North America (LHSFNA)
supported medical surveillance, but expressed concerns about repeated
testing and urged OSHA to include provisions for contractor
associations and union management funds to coordinate medical
examinations for employees who work for several contractors in a year
to avoid unnecessary medical examinations (Document ID 4207, p. 5).
After considering these comments, OSHA concludes that the necessity
for medical surveillance is not negated by the practical challenges of
tracking medical surveillance in a mobile work force. OSHA has included
medical surveillance in other health standards where construction has
been a primary industry impacted by those rules (e.g., lead, asbestos,
and chromium (VI)) and finds no reason why the respirable crystalline
silica standard for construction should be an exception. Moreover,
there are practical solutions for tracking medical surveillance to
avoid duplicative, unneeded testing. One simple solution, which OSHA
has included in this rule, is to have employers ensure that each
employee receives a dated copy of the PLHCP's written medical opinion
for the employer. The employee can then provide the opinion to his or
her next employer as proof of up-to-date medical surveillance (Document
ID 4207, p. 5; 4223, p. 125). Employers could also work with a third
party, such as an industry association, union, or local medical
facility, to coordinate, provide, or keep records of medical
examinations (Document ID 4207, p. 5; 4236, pp. 3-4, Appendix 1, pp. 1-
2). Such an approach has been used by LHSFNA to avoid unnecessary
testing of employees who work for several contractors in a year
(Document ID 3759, Appendix 3). The respirable crystalline silica rule
does not preclude such pooled employer-funded approaches, and OSHA
expects such coordination to occur in response to this rule. OSHA
concludes that there are practical solutions for addressing the
challenge posed by employee mobility and turnover in the construction
industry, and those factors should not prevent construction employees
who are eligible for medical surveillance under the standard (i.e.,
those who will be engaged in tasks requiring respirator use for 30 or
more days in the upcoming year) from being offered such surveillance as
part of the employer's compliance obligations.
In the proposed standards, OSHA specified that employers must
"make medical surveillance available" to those employees who would be
occupationally exposed to respirable crystalline silica above the PEL
for 30 or more days a year. The Agency received a variety of comments
on this provision. First, NAHB expressed concern about employees
refusing to participate in medical surveillance (Document ID 2296, p.
32). OSHA emphasizes that the mandate to offer medical surveillance to
eligible employees does not include a requirement for employee
participation, and no liability for non-participation arises so long as
the employer does not discourage such participation.
Second, OSHA received numerous comments related to the proposed
triggers for determining which employees should be provided medical
surveillance. Some commenters focused on the level of exposure at which
medical surveillance should be triggered. For example, Ameren
Corporation agreed with the proposed PEL trigger, noting that it is
consistent with the asbestos standard (Document ID 2315, p. 9). Some
stakeholders from industry, the medical community, and employee health
advocate groups also supported a trigger based on a PEL (e.g., Document
ID 1785, pp. 4-5; 2175, p. 5; 2291, p. 26; 2327, Attachment 1, p. 26;
2339, p. 5; 2379, Appendix 1, p. 71; 3577, Tr. 784-785).
Other commenters advocated that medical surveillance should be
triggered on an action level. However, these stakeholders disagreed on
what the action level should be. For example, some commenters, like the
National Industrial Sand Association (NISA), American Petroleum
Institute, and other employers and industry groups, advocated an action
level trigger of 50 [mu]g/m\3\ (with a higher PEL of 100 [mu]g/m\3\)
(e.g., Document ID 1963, pp. 1-2; 2196, Attachment 1, pp. 1-2; 2200,
pp. 1-2; 2213, p. 3; 2232, p. 1; 2233, p. 1; 2301, Attachment 1, p. 78;
2311, p. 3; 4208, pp. 7-9). NISA did not agree with OSHA that
significant risk remains at 50 [mu]g/m\3\, but stated that an action
level trigger is consistent with other OSHA standards; can lead to
identification of individuals who might be more susceptible to silica
exposures because of factors, such as genetic variability, prior work
exposures, or smoking; addresses variability in workplace exposures;
and provides an economic incentive for employers to maintain lower
exposures (Document ID 2195, pp. 6, 30, 32).
Other stakeholders, including representatives of labor unions, the
medical community, and other employee health advocate groups, stated
that the proposed action level of 25 [mu]g/m\3\, or even a lower level,
should trigger medical surveillance in general industry (e.g., Document
ID 2157, p. 7; 2178, Attachment 1, p. 2; 2240, p. 3; 2282, Attachment
3, p. 14; 2336, p. 11; 2256, Attachment 2, p. 9; 2351, pp. 13-15; 3516,
p. 3; 3541, p. 4). Other members of the medical community and employee
health advocate groups also voiced general support for an action level
trigger of 25 [mu]g/m\3\ or lower (e.g., Document ID 2080, p. 5; 2176,
p. 2; 3538, Attachment 1, pp. 3-4).
American Federation of Labor and Congress of Industrial
Organizations (AFL-CIO) supported an action level trigger of 25 [mu]g/
m\3\ because the union agreed with OSHA about the remaining significant
risk for diseases at a PEL of 50 [mu]g/m\3\ and because an action level
at half the PEL would be consistent with the majority of OSHA health
standards (Document ID 4204, pp. 51, 79-80). Other representatives from
the medical community, labor unions, and other employee health advocate
groups, who also supported an action level trigger of 25 [mu]g/m\3\ or
lower, expressed similar thoughts about significant risk or consistency
with past standards (Document ID 2080, p. 5; 2157, p. 7; 2176, p. 2;
2178, Attachment 1, p. 2; 2282, Attachment 3, p. 22; 2336, p. 11; 3516,
p. 3; 3535, p. 2; 3541, pp. 14-15). Some of those same commenters,
including the United Automobile, Aerospace and Agricultural Implement
Workers of America (UAW) and ACOEM, supported an action level trigger
because of the variability of workplace exposures (Document ID 2282,
Attachment 3, p. 14; 3577, Tr. 766-767); the medical society Collegium
Ramazzini and United Steelworkers (USW) also noted an economic benefit
for employers to maintain lower exposures (Document ID 2336, p. 11;
3541, p. 15). Lastly, AFL-CIO noted that because OSHA proposed a
requirement for exposure assessment in general industry, employers will
know if employees are exposed above the action level; the same is not
true in construction because employers may use Table 1 instead of
conducting exposure assessments (Document ID 4204, pp. 80-81).
OSHA also received comments on whether medical surveillance should
be triggered by a number of days of exposure at a certain level. For
example, NISA objected to the proposed 30-day exposure-duration trigger
for medical surveillance and stated that it should be offered to all
employees with likely exposure to respirable crystalline silica above
the action level (Document ID 4208, p. 8, Fn 12). The Asphalt Roofing
Manufacturers Association (ARMA) supported the 30-day exposure-duration
trigger for medical surveillance because some employees are only
infrequently exposed above the PEL as a result of scheduled maintenance
tasks performed once or twice per year or when filling in for other
employees, and the 30-day trigger would exclude employees with lower
average exposures (Document ID 2291, p. 26). Other commenters
representing industry or the medical community also agreed with the 30-
day exposure-duration trigger (e.g., Document ID 2080, p. 5; 2157, p.
7; 2175, p. 5; 2178, Attachment 1, p. 2; 2301, Attachment 1, p. 78;
2311, p. 3; 2315, p. 9; 2327, Attachment 1, p. 26; 2379, Appendix 1, p.
71; 3541, p. 14).
OSHA agrees with the majority of commenters who indicated that
maintaining the 30-day exposure-duration trigger is appropriate for
general industry and maritime because the health effects of respirable
crystalline silica occur as a result of repeated exposures and
concludes that a 30-day trigger is a reasonable benchmark for capturing
cumulative effects caused by repeated exposures. Including a 30-day
exposure-duration trigger also maintains consistency with other OSHA
standards, such as chromium (VI) (29 CFR 1910.1026), cadmium (29 CFR
1910.1027), lead (29 CFR 1910.1025), and asbestos (29 CFR 1910.1001).
OSHA also agrees with commenters who indicated that triggering medical
surveillance at the action level of 25 [mu]g/m\3\ addresses residual
significant risk and varying susceptibility of employees that can
result in some experiencing adverse health effects at lower exposure
levels. An action level trigger in the standard for general industry
and maritime is also appropriate based on variability in exposure
levels and the availability of exposure assessment data in general
industry and maritime. However, OSHA has concluded that a delayed
implementation of the action level trigger for medical surveillance is
appropriate. Therefore, as indicated in the Summary and Explanation for
Dates, medical surveillance will be triggered by exposures exceeding
the PEL for 30 or more days per year during the first two years after
medical surveillance requirements commence (i.e., beginning two years
after the effective date). After that time (i.e., four years after the
effective date), medical surveillance will be triggered by exposures
exceeding the action level for 30 or more days per year (paragraph
(l)(4)). This approach will focus initial medical surveillance efforts
on those employees at greatest risk, while giving most employers
additional time to fully evaluate the engineering controls they have
implemented in order to determine which employees meet the action level
trigger for medical surveillance.
OSHA intends to conduct a retrospective review five years after the
action level trigger is fully implemented (i.e., at nine years after
the effective date of the standard for general industry and maritime)
to gain a better understanding of the effectiveness of the action level
trigger for medical surveillance. OSHA will engage other federal
agencies, such as NIOSH, and stakeholders as appropriate, and will
issue a report about the findings of the evaluation.
Construction industry representatives, employee health advocates,
and others also commented on OSHA's proposed use of the PEL to trigger
medical surveillance in the standard for construction. The Center for
Progressive Reform (CPR) and Charles Gordon, a retired occupational
safety and health attorney, advocated an action level trigger for
medical surveillance; Mr. Gordon also requested that conducting Table 1
activities trigger medical surveillance (Document ID 2351, p. 13; 4236,
pp. 3-4). Fann Contracting supported a PEL trigger for medical
surveillance (Document ID 2116, Attachment 1, p. 42). BAC and BCTD
supported the PEL (as determined by monitoring) or Table 1 tasks
requiring respirator use as triggers for medical surveillance in
construction because employees using Table 1 would not be required to
conduct exposure assessments and therefore would not know if exposures
exceed the action level (Document ID 4219, p. 29; 4223, p. 124). [Note
1 for proposed Table 1 indicated that required respirator use in Table
1 presumed exposures exceeding the PEL (78 FR 56273, 56499 (9/12/13))].
In prehearing comments, LHSFNA supported a PEL trigger as a practical
approach and requested that medical surveillance be triggered by tasks
(Document ID 2253, p. 5). In its post-hearing comments, however, LHSFNA
recommended that medical surveillance be required for employees who are
required to wear a respirator since those employees would already need
to undergo a medical evaluation to make sure they can safely wear a
respirator (as required by the respiratory protection standard)
(Document ID 4207, pp. 4-5).
After reviewing these comments, OSHA concludes that an action level
trigger is not practical in the construction industry because many
employers will be using Table 1, and, therefore, will not have an
exposure assessment indicating if the action level is met or exceeded.
OSHA acknowledges that some construction employees who are not required
to use respirators for 30 or more days per year are at significant
risk, but has decided that triggering medical surveillance based on
respirator use is the most practical trigger for the construction
standard. Triggering medical surveillance in this manner is consistent
with the proposed rule, because respirator use under Table 1 is based
on tasks in which exposures consistently (more often than not) exceed
the revised PEL, as found in OSHA's technological feasibility analyses
of the various tasks included in Table 1 (see Chapter IV of the Final
Economic Analysis and Final Regulatory Flexibility Analysis (FEA) and
the summary and explanation for Specified Exposure Control Methods).
OSHA expects most construction employers to be following Table 1, and
therefore decided it also made the most practical sense to tie medical
surveillance to required respirator use. In addition, use of the
respirator trigger allows construction employers to more efficiently
determine if the 30-day duration trigger is met in cases where one of
their employees may be required to use respirators when doing Table 1
tasks and while doing tasks (e.g., abrasive blasting) that are not on
Table 1 but are determined to have exposures above the PEL based on
exposures assessments conducted under paragraph (d)(2) of the standard
for construction. Finally, OSHA decided not to expand the trigger for
medical surveillance to Table 1 tasks that do not require respirator
use because many employees engaged in those tasks will be exposed below
the action level (see Chapter III of the FEA).
Some commenters expressed concerns about the practicality of
requiring employers to offer medical surveillance for exposures
exceeding a trigger level for 30 days or more in the construction
industry. George Kennedy, Vice President of Safety for the National
Utility Contractors Association, testified that they do not know what
employees are doing in the field each day and so will have to assume
that they are exposed and, therefore, offer medical surveillance to
every employee (Document ID 3583, Tr. 2245). BCTD questioned the
feasibility of the 30-day exposure-duration trigger because the
transient nature of construction work makes it difficult to predict if
an employee will be exposed for 30 days; the American Industrial
Hygiene Association (AIHA), AFL-CIO, and LHSFNA expressed similar views
(Document ID 2169, p. 6; 4204, p. 81; 4207, p. 4; 4223, p. 125). CISC
and some of its member companies questioned how an employer would know
if employees were exposed above the PEL for 30 or more days a year
unless they were following Table 1 or conducting near continuous
monitoring (Document ID 2269, pp. 6-7; 2289, p. 8; 2319, p. 116). CISC
and AIHA questioned how OSHA could verify the number of days an
employee was exposed (Document ID 2169, p. 6; 2319, p. 116). Larger
employers, such as Fann Contracting, expressed the challenges of
tracking employee exposures due to large numbers of employees and
various ongoing projects (e.g., Document ID 2116, Attachment 1, p. 11).
OSHA acknowledges that tracking exposures in construction can be
challenging but observes that some employers are currently able to
track employee exposures to determine which employees should be offered
medical surveillance. For example, Kevin Turner, Director of Safety at
Hunt Construction Group and representing CISC, testified that safety
representatives on job sites keep track of exposures based on
employees' schedules, and the company provides medical surveillance for
employees exposed above the preceding construction PEL for 30 or more
days a year (Document ID 3580, Tr. 1535-1536). Francisco Trujillo,
Safety Director at Miller and Long, Inc., testified that at his
company, they conduct hazard assessments based mainly on the tasks the
employees will be performing, to determine which employees are likely
to be exposed above the preceding PEL, and they offer those employees
medical evaluations as part of the company's respiratory protection
program. The company has a system that monitors participating
employees' training, medical evaluations, and fit tests. The system
sends email reminders to company representatives when the participating
employees are due to be re-examined or re-evaluated. However,
Mr. Trujillo expressed concern that if the number of employees
participating in the program greatly increases, then maintaining the
company's tracking program would become a more daunting task
(Document ID 3585, Tr. 3008-3010).
After reviewing the comments and testimony submitted on the
proposed construction trigger, OSHA concludes that the special
circumstances in construction, such as lack of exposure data for
employees using Table 1 or difficulties in tracking exposures for
numerous short-term assignments conducted at various sites, warrant a
simpler approach for triggering medical surveillance. Therefore, OSHA
revised paragraph (h)(1)(i) of the standard for construction to require
that employers offer medical surveillance to employees who will be
required to wear a respirator under this standard for 30 or more days a
year to limit exposure to respirable crystalline silica. Under the
standard for construction, employees must wear a respirator when
required to do so under Table 1 (paragraph (c)) or when, pursuant to
the performance option or the scheduled monitoring option set forth in
paragraph (d)(2), their exposures exceed the PEL (paragraph
(e)(1)(ii)). Respirator use under Table 1 is equivalent to the PEL
because the tasks that require respirator use are those that, in its
technological feasibility analysis of the construction industry, OSHA
has determined result in exposures exceeding 50 [mu]g/m\3\ a majority
of the time (see Chapter IV of the FEA and the summary and explanation
of Specified Exposure Control Methods). Based on the number of
commenters who indicated that exposure assessment is not practical in
construction because of changing tasks and conditions (see summary and
explanation of Exposure Assessment), OSHA expects most employers to use
Table 1 for tasks listed on the Table (i.e., most of the tasks that
generate silica exposure in construction). Under any available exposure
control method, however, the most convenient way for construction
employers to determine eligibility for medical surveillance is by
counting the number of days the employee will be required to wear a
respirator. Because respirator use is tied with certain tasks in Table
1, medical surveillance based on respirator use in Table 1 is
consistent with the task-based approach described by Francisco Trujillo
above. It is also consistent with the task-based triggers in the
cadmium construction standard (29 CFR 1926.1127) and operation-based
triggers (e.g., Class I work) in the asbestos construction standard (29
CFR 1926.1101).
OSHA concludes that a trigger based on respirator use will greatly
simplify determining which employees covered by the construction
standard must be offered medical surveillance. Consistent with the
approach described by Kevin Turner above, company personnel on site,
such as supervisors, could easily record or estimate when employees
perform, or will perform, tasks requiring respirator use. Such
information could be conveyed to a company employee who tracks it.
Despite testifying that he would have a hard time tracking a greater
number of employees who may require medical surveillance if the PEL or
action level in effect at that time were lowered, Francisco Trujillo,
from Miller and Long, a company with approximately 1,500 field
employees, indicated that his company has a system that monitors and
sends emails when employees are due for another medical examination
(Document ID 3585, Tr. 3008-3010). OSHA sees no reason why this system
could not be applied to larger numbers of employees, and this shows
that it is possible for large companies to track exposures for numerous
employees. Tracking exposures or days of respirator use will likely be
easier for smaller companies who have fewer employees to track; OSHA
estimates from existing data that approximately 93 percent of
construction companies covered by the respirable crystalline silica
standard have fewer than 20 employees (see Chapter III of the FEA). In
addition, compliance officers would be able to determine if employees
were exposed for 30 or more days a year but not offered medical
surveillance by questioning employees about how often they engage in
tasks that require respirator use for that employer.
Fann Contracting asked how a trigger for medical surveillance would
apply to employees, such as heavy machine operators, who may briefly
use respirators, such as when outside a cab for 30 minutes (Document ID
2116, Attachment 1, p. 3). OSHA clarifies that if an employee is
required to wear a respirator at any time during a given day, whether
to comply with the specified exposure control methods in paragraph (c)
or to limit exposure to the PEL under the construction standard for
respirable crystalline silica, that day counts toward the 30-day
threshold.
Commenters also questioned the appropriateness of a 30-day
exposure-duration trigger for construction. For example, American
Society of Safety Engineers (ASSE) voiced concerns about the standard
not addressing temporary employees who are continually exposed from job
to job but may never stay with an employer for a full 30 days (Document
ID 2339, p. 5). Conversely, CISC questioned why OSHA diverged from the
ASTM exposure-duration trigger of 120 days, which would reduce the need
to make medical surveillance available for short-term employees, and
stated that OSHA needed to explain how this would improve the health of
employees (Document ID 2319, p. 118; 1504, pp. 4-5). Members of the
ASTM committee that developed the ASTM E 2625-09 standard testified
that a 120-day exposure-duration trigger was selected so that employers
did not have to provide medical surveillance to transient employees and
that even a trigger of less than 90 days was considered but would have
resulted in too much pressure and cost for employers because of the
transient nature of construction work (Document ID 3580, Tr. 1452-1453;
3585, Tr. 2919-2920).
OSHA understands that offering medical surveillance for a transient
workforce may be challenging, especially for small companies. However,
the requirement to offer periodic medical examinations every three
years rather than annually will reduce the cost and burden of providing
such examinations considerably (see Chapter V of the FEA). OSHA finds
both the 120-day exposure-duration trigger (in the ASTM standards) and
the 90-day trigger (considered by the ASTM committee) overly exclusive
and insufficiently protective. Under those longer triggers, many short-
term employees (i.e., those doing tasks requiring respirator use or
otherwise exposed above the PEL for 30 or more days a year but
nonetheless exposed for less than 90 days with the same employer) would
be deprived of the health benefits of medical surveillance, such as
early detection of disease, despite being at risk due to repeated
exposures with different employers. As noted above, the health effects
of respirable crystalline silica are most likely to occur as a result
of repeated exposures. OSHA concludes that a 30-day exposure-duration
trigger strikes a reasonable balance between the administrative burden
of offering medical surveillance to all employees, many of whom may not
be further exposed or only occasionally exposed, and the need for
medical surveillance for employees who are regularly exposed and more
likely to experience adverse health effects. The 30-day trigger is also
administratively convenient insofar as it is consistent with OSHA
standards for construction, including asbestos (29 CFR 1926.1101),
cadmium (29 CFR 1926.1127), chromium (VI) (29 CFR 1926.1126), and
lead (29 CFR 1926.62).
Commenters also raised other issues regarding the 30-day exposure-
duration trigger that could apply to both the general industry and
maritime standard and the construction standard. One concern was that
inclusion of a 30-day trigger would result in discriminatory actions by
employers in order to avoid offering medical surveillance. For example,
Dr. Daniel Anna, Vice President of AIHA, was concerned that employers
might refuse to hire someone approaching 30 days of exposure (Document
ID 3578, Tr. 1048-1049); BAC also expressed concerns about employers
terminating employees approaching their 30th day of exposure (Document
ID 4219, p. 29). In addition, BAC noted that employers rotating
employees to maintain employee exposure below 30 days might result in
more employees being exposed to silica (Document ID 2329, p. 8).
Comments indicating that an employer might refuse to hire employees
approaching their 30th day of exposure are based on an interpretation
that medical surveillance is triggered by a total of 30 days of
exposure per year with any employer. Such an interpretation was
conveyed by the Shipbuilders Council of America and ASSE who commented
that employers would need to know employee exposures with past
employers when determining total days of exposure above the PEL
(Document ID 2255, p. 3; 3578, Tr. 1048). That is not OSHA's intent,
and OSHA clarifies that exposures occurring with past employers do not
count towards the 30-day-per-year exposure-duration trigger with the
current employer (i.e., the trigger is for employment with each
particular employer). However, the 30-day-per-year exposure-duration
trigger would apply when an employer hires a particular employee for
more than one short-term assignment during a year, totaling 30 days or
more. An advantage of not considering total exposures with all
employers in triggering medical surveillance is that it avoids creating
an incentive not to hire. With regard to comments about possible
discriminatory practices (e.g., termination before the 30th day) or
rotating employees to avoid medical surveillance, OSHA rejects the
reasoning that employers will base employment and placement decisions
on the 30-day exposure-duration trigger because the cost of medical
examinations is modest (i.e., the FEA estimates the average cost of
each medical examination at approximately $400 every three years).
Charles Gordon suggested that employers give each departing
employee a card indicating the number of days they were exposed above
the trigger point so that future employers would have a better idea if
the employee was eligible for another medical examination based on 30
days of exposure (Document ID 4236, pp. 3-4). Such a record of past
exposure with any prior employer is not necessary because of OSHA's
decision to not consider exposures with past employers when triggering
medical surveillance. Requiring employers to record exposures with past
employers and to give employees a card indicating the number of days
they were exposed above the trigger point increases recordkeeping and
paperwork burdens for employers. It also imposes a burden on employees
because it gives them an additional document that they need to
maintain. To avoid these added burdens and for the reasons previously
given for not counting exposures with other employers towards an
employee's medical surveillance requirement, OSHA rejects Mr. Gordon's
suggestion.
NIOSH and Fann Contracting questioned the 30-day-per-year exposure-
duration trigger because employees who have been exposed to silica for
years, but are not currently exposed 30 days per year, would be at risk
of developing lung diseases (Document ID 2116, Attachment 1, p. 41;
2177, Attachment B, pp. 39-40). NIOSH recommended that medical
surveillance continue after an employee is no longer exposed to
respirable crystalline silica but continues to work for the same
employer (Document ID 2177, Attachment B, p. 39). James Schultz, safety
director at Navistar Waukesha Foundry and representing the Wisconsin
Coalition for Occupational Safety and Health (WisCOSH), testified that
medical surveillance should continue after employees have left "this
type of work environment" (Document ID 3586, Tr. 3200-3201). However,
NIOSH also stated that considerations for continued medical
surveillance include the number of years an employee was required to be
monitored and if the employee is showing signs of silica-related
illness (Document ID 2177, Attachment B, p. 39).
OSHA agrees with NIOSH that silica is retained in the lungs and can
cause progressive damage after exposures end. However, the lack of
clear criteria in the record for determining when continued medical
surveillance would be beneficial precludes OSHA from mandating
continued medical surveillance after exposure ends. In addition, OSHA
policy is clear that requirements are imposed on current employers. In
the benzene standard, OSHA articulated that policy in deciding not to
mandate continued medical surveillance for employees who are no longer
exposed above the trigger, noting administrative difficulties in
keeping track of employees who had moved on to other jobs (52 FR 34460,
34550 (9/11/1987)).
CISC, American Subcontractors Association, OSCO Industries, and
Holes Incorporated questioned why medical surveillance is needed for
younger employees when respirable crystalline silica-related diseases
take years to develop (Document ID 1992, p. 11; 2187, p. 7; 2319, pp.
116-117; 3580, Tr. 1471). CISC recommended that OSHA trigger medical
surveillance after a minimum duration of exposure or when a silica-
related disease is diagnosed. In contrast, Andrew O'Brien, Vice
President of Safety and Health at Unimin Corporation and representing
NISA, emphasized the importance of establishing a baseline for future
measurement (Document ID 3577, Tr. 570). When asked if age or duration
of exposures should be considered in determining frequency of medical
surveillance, Dr. Laura Welch, occupational physician with BCTD,
responded:
...we're looking at different disease outcomes. If we were only
concerned about silicosis, you could probably...make that
argument, but silica exposure also causes [chronic obstructive
pulmonary disease], and that has an earlier onset and...it's
good to have a baseline of a couple of tests before someone develops
disease so you can more clearly see an early decline (Document ID
3581, Tr. 1667).
When a BAC panel was asked if 20 years after first exposure is the
appropriate time to start medical surveillance, terrazzo worker Sean
Barret responded:
According to their 20-year standard, you wouldn't even find out
I was sick until next year. I was sick a year ago, and it probably
showed five years before that. So, I mean, that's ludicrous
(Document ID 3585, Tr. 3055).
OSHA agrees that employees' baseline findings are important for
future diagnoses and notes Dr. Welch's testimony that other silica-
related diseases, such as chronic obstructive pulmonary disease (COPD),
develop in shorter times than silicosis. Based on such evidence, OSHA
concludes that it is appropriate to start medical surveillance in young
or newly exposed employees before they experience declines in health or
function associated with age or respirable crystalline silica exposure.
Paragraph (i)(1)(ii) of the standard for general industry and
maritime (paragraph (h)(1)(ii) of the standard for construction)
requires that the medical examinations made available under the rule be
performed by a PLHCP, who is defined (see summary and explanation of
Definitions) as an individual whose legally permitted scope of practice
(i.e., license, registration, or certification) allows him or her to
independently provide or be delegated the responsibility to provide
some or all of the particular health services required by paragraph (i)
of the standard for general industry and maritime (paragraph (h) of the
standard for construction). This provision is unchanged from the
proposed rule.
The American Public Health Association (APHA) requested changes to
the definition of PLHCP that would require the PLHCP to be licensed for
independent practice (Document ID 2178, Attachment 1, p. 5). OSHA finds
that requested change to be too restrictive. To assure competency while
providing for increased flexibility, OSHA continues to find it
appropriate to allow any professional to perform medical examinations
and procedures made available under the standard when he or she is
licensed by state law to do so. In this respect, which and how a health
care professional can function as a PLHCP under the rule may vary from
state to state depending on each state's licensing requirements and
laws governing what diagnostic examinations and procedures they are
permitted to perform. In no case, however, is the authorization in this
rule to use any PLHCP narrower or stricter than what is authorized in
the particular state where an examination occurs.
Some commenters expressed concern about the availability of PLHCPs
or other medical professionals in certain geographical locations. For
example, Fann Contracting and the National Rural Electric Cooperative
Association commented that PLHCPs who can offer the required
examinations or occupational health resources may not be available for
employers located in rural areas or near retirement communities
(Document ID 2116, Attachment 1, p. 43; 2365, p. 10). Under the rule, a
PLHCP, as defined, does not have to be an occupational medicine
physician or even a physician to conduct the initial and periodic
examinations required by the rule, but can be any health care
professional who is state-licensed to provide or be delegated the
responsibility to provide those services. The procedures required for
initial and periodic medical examinations are commonly conducted in the
general population (i.e., medical history, physical examination, chest
X-ray, spirometry test, and tuberculosis test) by practitioners with
varying qualifications. Because medical examinations consist of
procedures conducted in the general population and because OSHA is
giving employers maximum flexibility in selecting a PLHCP who can offer
these services, OSHA intends to assure that employers will not
experience great difficulty in finding PLHCPs who are state-licensed to
provide or be delegated the responsibility to provide these services.
Even in the case of X-rays, OSHA finds that the availability of digital
X-ray technology allows for electronic submission to a remotely located
B Reader for interpretation, and thus does not expect a limited number
of B readers in a certain geographic location to be an obstacle to
employers covered by the rule.
Initial examination. Paragraph (i)(2) of the standard for general
industry and maritime (paragraph (h)(2) of the standard for
construction) specifies that an initial (baseline) medical examination
must be made available within 30 days of initial assignment (i.e., the
day the employee starts working in a job with potential exposures above
the trigger point), unless the employee received an examination that
meets the requirements of this section within the past three years.
This provision is unchanged from the proposed rule. The requirement for
an initial examination within 30 days of assignment provides a health
baseline for future reference and lets employees know of any conditions
that could increase their sensitivity to respirable crystalline silica
exposure. For example, Dr. Tee Guidotti, an occupational medicine
physician representing the Association of Occupational and
Environmental Clinics (AOEC), testified that existing COPD may make an
individual more sensitive to respirable crystalline silica exposure
(Document ID 3577, Tr. 797-798).
Newmont Mining Corporation, Nevada Mining Association, and
Distribution Contractors Association (DCA) questioned whether recent or
future exposures should be considered in triggering certain aspects of
the initial examination (e.g., physical examination, chest X-ray, or
pulmonary function tests) and indicated that baseline examinations
should only be required near the time when exposures begin (Document ID
1963, p. 2; 2107, p. 3; 2309, p. 5). The requirement is for employers
to offer initial examinations to employees who "will be"
occupationally exposed to respirable silica at or above the action
level for 30 or more days a year in the standard for general industry
and maritime (paragraph (i)(1)(i)) or who "will be" required to use a
respirator under this section for 30 or more days per year in the
standard for construction (paragraph (h)(1)(i)). Therefore, eligibility
for medical examinations is based on expected exposure with the current
employer. These triggers apply to both initial and periodic medical
surveillance, and inclusion of the terms "will be occupationally
exposed" or "will be required" makes it clear that requirements to
offer medical surveillance are not based on past exposures. OSHA is
aware that unexpected circumstances may result in employees being
exposed more frequently than initially anticipated. In those cases,
employers should make medical surveillance available as soon as it
becomes apparent that the employee will be exposed above the
appropriate trigger point for 30 or more days per year.
In the preamble of the Notice of Proposed Rulemaking (NPRM), OSHA
indicated that where an examination that complies with the requirements
of the standard has been provided in the past three years, an
additional initial examination would not be needed (78 FR at 56468).
Ameren agreed with OSHA's preliminary determination on this issue and
asked the Agency to verify that examinations conducted in the last
three years could be supplemented with any additional requirements of
the rule, such as tuberculosis testing (Document ID 2315, p. 4). OSHA
agrees that this is a reasonable approach. For example, if an employee
received an examination that met all the requirements of the initial
medical examination, with the exception of a tuberculosis test, within
the last three years, the employer could supplement that examination by
offering only the tuberculosis test. That same employer or a future
employer could then offer a periodic medical examination, which does
not require a tuberculosis test, three years from the last medical
examination. New hires, who received medical surveillance that met the
requirements of the respirable crystalline silica rule from a past
employer, should have a copy of the PLHCP's written medical opinion for
the employer, which the employer must ensure that the employee receives
within 30 days of the examination (paragraph (i)(6)(iii) of the
standard for general industry and maritime, paragraph (h)(6)(iii) of
the standard for construction), as proof of a current initial or
periodic medical examination that met the requirements of this section
(see example of the PLHCP's written medical opinion for the employer in
Appendix B). If a newly hired employee eligible for medical
surveillance presents proof of an examination that met the requirements
of the rule, the employer's obligation is to offer the periodic
examination required by paragraph (i)(3) of the standard for general
industry and maritime (paragraph (h)(3) of the standard for
construction) within three years of the previous examination.
Commenting on the three year period in which the result of a prior
examination can substitute for a new initial (baseline) examination,
APHA, Collegium Ramazzini, and the American Federation of State, County
and Municipal Employees (AFSCME) opined that three years between
examinations is an excessive time period because it does not provide
for an adequate baseline; Collegium Ramazzini further commented that
medical findings and medical or work histories can change in three
years and that spirometry performed at other locations does not provide
an adequate baseline (Document ID 2178, Attachment 1, p. 4; 3541, pp.
4-5; 4203, p. 6). Dr. Celeste Monforton, from George Washington
University School of Public Health, agreed with APHA (Document ID 3577,
Tr. 846). OSHA disagrees. The three-year interval is consistent with
the frequency of periodic examinations, and the reasons for this
interval, such as the typical slow progression of respirable
crystalline silica-related diseases, are discussed below.
The American Foundry Society (AFS) supported the 30-day period for
offering medical surveillance, stating that it addressed the turnover
rates in its industry because employees who work 30 days are likely to
continue their employment (Document ID 2379, Appendix 1, p. 71). AESC
requested that OSHA allow medical examinations to be provided within 90
days of assignment to address the turnover rate in its industry
(Document ID 2344, p. 2). The National Stone, Sand and Gravel
Association (NSSGA) noted difficulties in scheduling medical
examinations within 30 days in remote locations because testing vans
that offer medical examinations might not be available within that time
period (Document ID 3583, Tr. 2316-2317). Because a 30-day period for
offering medical examinations is reasonable for AFS, which represents
an industry with high turnover rates, OSHA concludes that a 30-day
period should be reasonable in most general industry settings. OSHA
does not agree with AESC that the period to offer medical surveillance
should be extended to 90 days in the standard for general industry and
maritime. That longer time period to offer medical surveillance would
exclude and leave unprotected many employees who may be exposed to
significant amounts of silica while working short-term assignments, for
periods up to 90 days, for numerous companies within the same industry.
Representatives from the construction industry also commented on
the 30-day period to offer medical surveillance. BAC and BCTD
recommended that medical examinations be made available as soon as
practicable, instead of within 30 days after assignment, in the
construction industry because it would be difficult for employers to
predict if an employee would be exposed for 30 days or more during the
upcoming year, and it could encourage employers to terminate employees
before the 30-day period ends (Document ID 4219, p. 29; 4223, p. 125).
Fann Contracting suggested that a better trigger would be after the
employee has been exposed for 30 days instead of within the first 30
days of assignment (Document ID 2116, Attachment 1, p. 43).
OSHA rejects this reasoning, and is maintaining the requirement to
offer medical surveillance within 30 days of assignment for the
construction standard. The requirement better assures that medical
examinations will be offered within a reasonable time period than
allowing the employer to offer them "as soon as practicable." As
noted above, employers can determine who will be eligible for medical
surveillance based on required respirator use under Table 1 or similar
task-based approaches. Even at the time of initial assignment, OSHA
expects that employers will know the tasks that the employee will be
performing, and in the case of short-term employees, the approximate
duration the employee will be with the company. In addition,
terminating employees to avoid offering medical surveillance would not
be cost effective because the employer would incur more costs from
constantly having to train new employees.
The Precast/Prestressed Concrete Institute commented that local
union halls from which they hire employees and the Americans with
Disability Act may prohibit pre-hire medical testing (Document ID 2276,
p. 10). National Electrical Contractors Association expressed concern
about economic burdens associated with pre- and post-employment medical
evaluations in transient or temporary employees (Document ID 2295, p.
2). OSHA clarifies that no pre-hire or post-employment testing is
required in the respirable crystalline silica rule, which requires that
medical examinations related to respirable crystalline silica exposure
be offered within 30 days after initial assignment to employees who
will meet the trigger for medical surveillance.
Contents of initial medical examination. Paragraphs (i)(2)(i)-(vi)
of the standard for general industry and maritime (paragraphs
(h)(2)(i)-(vi) of the standard for construction) specify that the
initial medical examination provided by the PLHCP must consist of: A
medical and work history; a physical examination with special emphasis
on the respiratory system; a chest X-ray; a pulmonary function test; a
latent tuberculosis test; and other tests deemed appropriate by the
PLHCP. Special emphasis must be placed on the portions of the medical
and work history focusing on exposure to respirable crystalline silica,
dust or other agents affecting the respiratory system, any history of
respiratory system dysfunction (including signs and symptoms, such as
shortness of breath, coughing, and wheezing), any history of
tuberculosis, and current or past smoking. The only changes from the
proposed rule are reflected in paragraphs (i)(2)(iii) and (iv) of the
standard for general industry and maritime (paragraphs (h)(2)(iii) and
(iv) of the standard for construction), and those revisions are
discussed below.
OSHA received a range of comments related to the contents of the
initial examination. Some stakeholders, including NIOSH and commenters
representing the medical community, labor unions, and industry,
supported the contents of medical surveillance that OSHA proposed,
though some wanted to expand the contents, as addressed below (e.g.,
Document ID 2175, p. 6; 2177, Attachment B, pp. 38-39; 2282, Attachment
3, p. 19; 2336, p. 12; 2371, Attachment 1, p. 43; 3589, Tr. 4205; 4204,
p. 82). Further, the contents of medical surveillance in this standard
are fairly consistent with the recommendations in occupational health
programs, such as those by NISA and NSSGA (Document ID 2195, pp. 40-41;
2327, Attachment 1, p. 23).
However, not all stakeholders agreed that the list of proposed
initial examination contents was appropriate. For example, Fann
Contracting favored limiting the contents of medical examinations to
X-rays, while Dal-Tile Corporation, the 3M Company, and the Tile Council
of North America indicated that requirements for medical examinations under
the respiratory protection standard were sufficient (Document ID 2116,
Attachment 1, p. 37; 2147, p. 3; 2313, p. 7; 2363, pp. 5-6). Similarly,
Nevada Mining Association commented that the need to conduct physical
examinations, X-rays, or pulmonary function testing should be left to
the discretion of the PLHCP (Document ID 2107, pp. 3-4). Newmont Mining
also said that one or more of these tests should be at the discretion
of the PLHCP (Document ID 1963, pp. 2-3).
OSHA finds that X-rays alone are not sufficient because, as
explained in more detail below, some employees may have symptoms or
abnormal lung function that are not detected by X-ray but may become
evident by other tests, such as spirometry. The Agency also finds that
the evaluations offered under the respiratory protection standard are
insufficient because the information gathered under that standard is
limited and may not involve examinations, while the respirable
crystalline silica rule requires examinations that include objective
measures, such as physical examinations, spirometry testing and X-rays,
that may detect early disease in asymptomatic employees. In addition,
OSHA does not agree that all required tests should be left to the
discretion of the PLHCP because the Agency has determined that
employees who must be offered medical surveillance are at risk of
developing respirable crystalline silica-related diseases, and the
required tests are the minimum tests needed to screen for those
diseases. Therefore, OSHA concludes that limiting medical surveillance
to only X-rays, the evaluations performed under the respiratory
protection standard, or only tests selected by the PLHCP is not
sufficiently protective.
The first item required as part of the initial medical examination
is a medical and work history, with emphasis on: Past, present, and
anticipated exposure to respirable crystalline silica, dust, and other
agents affecting the respiratory system; any history of respiratory
system dysfunction, including signs and symptoms of respiratory disease
(e.g., shortness of breath, cough, wheezing); history of tuberculosis;
and smoking status and history (paragraph (i)(2)(i) of the standard for
general industry and maritime, paragraph (h)(2)(i) of the standard for
construction). OSHA is requiring medical and work histories because
they are an efficient and inexpensive means for collecting information
that can aid in identifying individuals who are at risk due to
hazardous exposures (Document ID 1505, p. 2; 1517, p. 25). Recording of
symptoms is important because, in some cases, symptoms indicating onset
of disease can occur in the absence of abnormal laboratory test
findings (Document ID 1517, p. 25).
Because symptoms may be the earliest sign of disease and to allow
for consistent and comprehensive data collection, Collegium Ramazzini
recommended that an appendix with a standardized questionnaire be
included; it also recommended that the questionnaire address non-
respiratory effects, such as renal disease and connective tissue
disorders (Document ID 3541, pp. 3, 6). While not going as far as this
recommendation, OSHA includes in the rule an appendix for medical
surveillance (Appendix B), which gives PLHCPs detailed information on
what is to be collected as part of the medical history. The appendix
recommends collecting information on renal disease and connective
tissue disorders. OSHA intends for this approach to allow PLHCPs to
easily standardize their method for gathering information for work and
medical histories related to respirable crystalline silica exposure.
Newmont Mining and Nevada Mining Association objected to a
requirement for a medical and work history, asserting that a personal
medical history is not related to silica exposure (Document ID 1963, p.
2; 2107, p. 3). Commenters, including DCA and International Brotherhood
of Teamsters, objected to employees revealing medical and work history
information not related to respirable crystalline silica exposure
because of privacy concerns (e.g., Document ID 2309, p. 5; 2318, pp.
13-14). Retired foundry employee, Allen Schultz, representing WisCOSH,
expressed concern that information, such as smoking history, could be
used against employees (Document ID 3586, Tr. 3255). As noted above, a
purpose of medical surveillance is to inform employees if they may be
at increased risk of adverse effects from respirable crystalline silica
exposure. Personal habits, such as smoking, could lead to compromised
lung function or increased risk of lung cancer, and exposure to
respirable crystalline silica could compound those effects (see Section
V, Health Effects). Collecting information, such as smoking habits and
related medical history, allows the PLHCP to warn employees about their
increased risks from exposure to respirable crystalline silica so
employees can make informed health decisions.
As discussed below, OSHA is addressing employee privacy issues by
reducing the information to be included in the PLHCP's written medical
opinion for the employer without the employee's permission (paragraphs
(i)(6)(i)(A)-(C) of the standard for general industry and maritime and
paragraphs (h)(6)(i)(A)-(C) of the standard for construction); under
those paragraphs, the only medically related information that is to be
reported to the employer without authorization from the employee is
limitations on respirator use. Personal habits, such as smoking, are
not included in the medical opinion for the employer. Therefore,
employees' privacy will not be compromised as a result of the
information collected as part of the exposure and medical history.
The second item required as part of the initial medical examination
is a physical examination that focuses on the respiratory system
(paragraph (i)(2)(ii) of the standard for general industry and
maritime, paragraph (h)(2)(ii) of the standard for construction), which
is known to be susceptible to respirable crystalline silica toxicity.
OSHA finds that aspects of the physical examination, such as visual
inspection, palpation, tapping, and listening with a stethoscope, allow
the PLHCP to detect abnormalities in chest shape or lung sounds that
are associated with compromised lung function (Document ID 1514, p. 74;
1517, pp. 26-27). Dr. Michael Fischman, occupational and environmental
physician/toxicologist and professor at the University of California,
representing ACOEM, strongly endorsed a physical examination and noted
that another valuable aspect is that it allows the employee to have a
face-to-face interaction with the clinician to talk about symptoms or
other concerns (Document ID 3577, Tr. 767). OSHA agrees and concludes
that the physical examination is necessary.
The third item required as part of the initial medical examination
is a chest X-ray, specifically a single posteroanterior radiographic
projection or radiograph of the chest at full inspiration recorded on
either film (no less than 14 x 17 inches and no more than 16 x 17
inches) or digital radiography systems, interpreted and classified
according to the International Labour Office (ILO) International
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B
Reader (paragraph (i)(2)(iii) of the standard for general industry and
maritime, paragraph (h)(2)(iii) of the standard for construction). The
proposed rule specified only film X-rays but would have allowed for an
equivalent diagnostic study, such as digital X-rays; OSHA also sought comment
on whether computed tomography (CT) or high resolution computed tomography
(HRCT) scans should be considered equivalent diagnostic tests (78 FR at
56469-56470). As discussed in greater detail below, OSHA received many
comments on the proposed provision, and in response to those comments,
the current provision differs substantially from the proposed rule in
two main ways. First, the rule now specifically allows for chest X-rays
to be recorded on either film or digital radiography systems. Second,
the rule does not allow for an "equivalent diagnostic study."
Medical experts including ACOEM, the American Thoracic Society
(ATS), and NIOSH recommend X-rays as part of medical examinations for
employees exposed to respirable crystalline silica (e.g., Document ID
1505, p. 2; 2175, p. 6; 2177, Attachment B, pp. 38-39). The initial X-
ray provides baseline data against which to assess any subsequent
changes. An initial chest X-ray can be useful for diagnosing silicosis
and for detecting mycobacterial disease (e.g., active pulmonary
tuberculosis, which employees with latent tuberculosis infections and
exposed to respirable crystalline silica are at greater risk of
developing (Document ID 1514, pp. 75, 100). X-rays are important
because the findings can lead to the initiation of employment choices
that can reduce exposures to respirable crystalline silica and might
decrease the risk of silicosis progression or allow for treatment of
mycobacterial infections (Document ID 1505, p. 3).
As noted above, OSHA proposed that the required chest X-ray be
interpreted and classified according to ILO International
Classification of Radiographs of Pneumoconiosis by a NIOSH-certified B
Reader. The ILO system was designed to assess X-ray and digital
radiographic image quality and to describe radiographic findings of
pneumoconiosis in a simple and reproducible way by comparing an
employee's X-ray to a standard X-ray to score opacities according to
shape, size, location, and profusion (Document ID 1475, p. 1; 1511, pp.
64-68; 1514, pp. 77-78). A NIOSH-certified B Reader is a physician who
has demonstrated competency in the ILO classification system by passing
proficiency and periodic recertification examinations (Document ID
1498, p. 1). The NIOSH certification procedures were designed to
improve the proficiency of X-ray and digital radiographic image readers
and minimize variability of readings.
In 2011, the ILO made standard digital radiographic images
available and published guidelines on the interpretation and
classification of digital radiographic images (Document ID 1475). The
guidelines included requirements for display monitors. NIOSH also
published guidelines for conducting digital radiography and displaying
digital radiographic images in a manner that will allow for
classification according to ILO guidelines (Document ID 1513). Based on
these developments, OSHA stated in the preamble of the NPRM that
digital X-rays could now be evaluated according to the same guidelines
as film X-rays and could therefore be considered equivalent diagnostic
tests. The Agency also noted several advantages of digital X-rays:
Compared to film X-rays, digital imaging systems offer more consistent
image quality, faster results, increased ability to share images with
multiple readers, simplified storage of images, and reduced risk for
technicians and the environment due to the elimination of chemicals for
developing film (Document ID 1495, p. 2).
Commenters, such as Collegium Ramazzini, NIOSH, and the Dow
Chemical Company, agreed with OSHA that digital radiographic images are
equivalent to conventional X-rays; NIOSH and Dow Chemical suggested
OSHA clarify that the proposed requirement for chest X-rays may be
satisfied either with conventional film-based technology or with
digital technology; and NIOSH and Collegium Ramazzini referred OSHA to
an interim final regulation for coal miners that allows for digital
technology (Document ID 2177, Attachment B, pp. 40-41; 2270, p. 13;
3541, p. 7). After reviewing the record evidence on this issue, OSHA
reaffirms its preliminary conclusion that X-rays recorded on digital
radiography systems are equivalent to those recorded on film.
Therefore, OSHA has revised paragraph (i)(2)(iii) of the standard for
general industry and maritime (paragraph (h)(2)(iii) of the standard
for construction) to indicate that X-rays can be recorded on either
film or digital systems, using language that is consistent with that in
the interim final regulation for coal miners (42 CFR part 37.2 (10-1-13
Edition)).
NSSGA commented that good quality digital images reproduced on film
should also be considered acceptable as equivalent to X-rays (Document
ID 2327, Attachment 1, p. 23). OSHA disagrees. The Agency does not
recommend classification using hard copies printed from digital images
because a 2009 study by Franzblau et al. indicates that they give the
appearance of more opacities compared to films or digital images
(Document ID 1512). OSHA does not find hard copy printouts of digital
images equivalent to conventional X-rays. Consequently, classification
through the use of hard copies printed from digital images may not be
used to satisfy the requirement for chest X-rays.
As indicated above, the proposed rule called for the chest X-ray to
be interpreted and classified by a NIOSH-certified B reader. A number
of commenters offered opinions on this requirement. For example, Dow
Chemical urged OSHA to allow board certified radiologists to interpret
the X-rays because it claimed that insufficient numbers of B Readers
would lead to a backlog of X-ray interpretation that would make it
impossible for B Readers to get their reports back to PLHCPs within the
required 30 days (Document ID 2270, p. 9). Other representatives from
industry, such as the Mason Contractors Association of America, ARMA,
and the North American Insulation Manufacturers Association, expressed
similar concerns about numbers of B Readers (e.g., Document ID 2286,
pp. 2-3; 2291, p. 26; 2348, Attachment 1, pp. 39-40).
The rulemaking record contains ample evidence of sufficient numbers
of B Readers and the value of B Reader interpretation according to ILO
methods. CISC and NIOSH estimated demands on B Readers based on OSHA's
estimate in the preamble of the NPRM that 454,000 medical examinations
would be required in the first year after the rule is promulgated (78
FR at 56468). Based on the 242 B Readers accounted for as of February
12, 2013 (78 FR at 56470), CISC estimated 1,876 chest X-rays for each B
Reader, requiring each B Reader to interpret more than five chest X-
rays per day, which CISC claimed would result in a backlog (Document ID
2319, p. 118). However, Dr. David Weissman, Director of NIOSH's
Division of Respiratory Disease Studies, indicated that a B Reader can
easily classify 10 images in an hour (Document ID 3579, Tr. 196,
Attachment 2, p. 1). NIOSH estimated that a B Reader working 1 hour per
day, 5 days per week, 50 weeks per year can classify 2,500 images and
that 182 B Readers working a minimum of 1 hour per day and 50 weeks per
year would be needed to classify X-rays for 454,000 employees (Document
ID 4233, Attachment 1, p. 40). As of May 19, 2014, there were 221
certified B Readers in the United States, an adequate number to meet
the demands for the respirable crystalline silica rule (Document ID
3998, Attachment 15, p. 2). Based on the new triggers and more recent data
on turnover rates, OSHA estimates that approximately 520,000 medical
examinations will be required in the first year after the rule is
promulgated. Using Dr. Weissman's assumptions, OSHA estimates that 221
B Readers would need to spend less than 1 hour a day to classify X-rays
for 520,000 employees.
Dr. Weissman testified that the number of B Readers is driven by
supply and demand created by a free market and that many physicians
choose to become B Readers based on demands for such services (Document
ID 3579, Tr. 197-198, Attachment 2, p. 1). He went on to state that
NIOSH provides several pathways for physicians to become B Readers,
such as free self-study materials by mail or download and free B Reader
examinations. In addition, courses and examinations for certification
are offered for a fee every three years through the American College of
Radiology. Dr. Robert Cohen, pulmonary physician and clinical professor
at the University of Illinois, representing ATS, agreed that NIOSH is
able to train enough B Readers to handle any potential increase in
demand (Document ID 3577, Tr. 777). Moreover, even if B Readers are
scarce in certain geographical locations, digital X-rays can easily be
transmitted electronically to B Readers located anywhere in the U.S.
(Document ID 2116, Attachment 1, p. 43; 3580, Tr. 1471-1472; 3585, Tr.
2887; 2270, p. 13; 2195, p. 44; 3577, Tr. 817-818). Based on this
information, OSHA concludes that numbers of B Readers in the U.S. are
adequate to interpret X-rays conducted as part of the respirable
crystalline silica rule.
Some commenters questioned the value of requiring B Readers. Dow
Chemical claimed that board certified radiologists are able to provide
interpretations of X-rays that are consistent with those of B Readers
and that such an approach is consistent with that of the OSHA Asbestos
standard (29 CFR 1910.1001, Appendix E) (Document ID 2270, pp. 9-10).
Dow Chemical also stated that digital radiography has improved
interpretation accuracy for radiologists who are not B Readers.
American Road and Transportation Builders Association (ARTBA) commented
that inadequate numbers of B Readers could result in misinterpretations
of X-rays. It also cited a study by Gitlin et al. (2004), which it
interpreted as showing that B Readers can be biased by exposure
information; according to ARBTA, the study reported that B Readers
hired for asbestos litigation cases read 95.9 percent of X-rays as
positive, while independent, blinded B readers only read 4.5 percent of
those X-rays as positive (Document ID 2245, pp. 2-3).
Based on record evidence, OSHA finds that the requirement for B
Readers to demonstrate proficiency in ILO methods results in more
consistent X-ray interpretation. For example, guidelines by the World
Health Organization (WHO) acknowledge the value of consistent, high-
quality X-rays for reducing interpretation variability and note that B
Reader certification may also improve consistency of X-ray
interpretation (Document ID 1517, p. 21). Robert Glenn, Certified
Industrial Hygienist representing the Brick Industry Association and
previously in charge of the B Reader program at NIOSH, said he thought
the reduced variability (i.e., lower prevalence of small opacities
graded 1/0 or greater in unexposed populations) in the U.S. compared to
Europe in a study by Meyer et al. (1997) could be attributed to the
success of the B Reader program (Document ID 3577, Tr. 668, 670, 682;
3419, p. 404). Dr. James Cone, occupational medicine physician at the
New York City Department of Health, stated that development of ILO
methods for evaluating pneumoconiosis by chest X-ray has led to greater
precision and sensitivity. Dr. Cone gave the example that two B Readers
who evaluated X-rays performed on foundry employees as part of a NIOSH
Health Hazard Evaluation identified six cases of X-rays and
occupational history consistent with silicosis that had been classified
as normal by company physicians (Document ID 2157, pp. 4-5). Based on
the record evidence demonstrating the value of B Reader certification,
OSHA rejects the suggestion that the standard should allow X-ray
interpretation by board-certified radiologists.
The evidence discussed above supports OSHA's conclusions that
adequate numbers of B Readers are available locally or by electronic
means to interpret chest X-rays of respirable crystalline silica-
exposed employees and that B Reader certification improves the quality
of X-ray interpretation. OSHA concludes that standardized procedures
for the evaluation of X-ray films and digital images by certified B
Readers is warranted based on the seriousness of silicosis and is
therefore retaining that requirement in the rule.
OSHA noted in the preamble for the NPRM that CT or HRCT scans could
be considered "equivalent diagnostic studies." CT and HRCT scans are
superior to chest X-ray in the early detection of silicosis and the
identification of progressive massive fibrosis. However, CT and HRCT
scans have risks and disadvantages that include higher radiation doses
and current unavailability of standardized methods for interpreting and
reporting the results (78 FR at 56470). Because of these concerns, OSHA
specifically sought comment on whether CT and HRCT scans should be
considered equivalent diagnostic studies under the rule, and a number
of stakeholders provided comments on this issue.
In its prehearing comments, ATS stated that despite the lack of
standardized interpretation and reporting methods, CT or HRCT are
reasonable "equivalent diagnostic studies" to standard chest X-rays
because they are more sensitive than X-rays for early detection of
diseases, such as silicosis and lung cancer; however, the group's
representative, Dr. Robert Cohen, later testified that HRCT is not
ready as a screening technique but is a useful diagnostic tool
(Document ID 2175, p. 6; 3577, Tr. 825). USW noted that interpretation
methods are being developed for the evaluation of pneumoconiosis by CT
scan and suggested approaches for the use of low dose CT (LDCT) scans
to evaluate silicosis and lung cancer in some employees (Document ID
4214, pp. 9-12).
Physicians, such as those representing ACOEM, Collegium Ramazzini,
and NIOSH, did not consider CT or HRCT to be equivalent diagnostic
studies because of the lack of a widely-accepted standardized system of
interpretation, such as the ILO method (e.g., Document ID 2080, pp. 7-
8; 2177, Attachment B, p. 40; 3541, p. 7). In addition, NIOSH, APHA,
Edison Electric Institute (EEI), Collegium Ramazzini, and ACOEM
indicated the higher radiation doses received from CT and HRCT scans
make it inappropriate to consider these methods equivalent to X-rays
(Document ID 2177, Attachment B, p. 40; 2178, Attachment 1, p. 6; 2357,
pp. 34-35; 3541, p.7; 3577, Tr. 768).
NIOSH and Collegium Ramazzini also commented on the increased
sensitivity of CT scans in detecting abnormalities that require follow-
up, which they cited as another reason why CT scans should not be
considered equivalent to X-rays (Document ID 2177, Attachment B, p. 40;
3541, p. 7). NIOSH said the abnormalities can suggest lung cancer, but
most are found to be "false positives" (Document ID 2177, Attachment
B, p. 40). Detection of abnormalities that might suggest cancer can
lead to anxiety in patients; it can also lead to follow-up with more
imaging tests that increase radiation exposures or invasive biopsy
procedures that have a risk of complications (Document ID 2177,
Attachment B, p. 40; 3978, pp. 2423, 2427). Commenters also noted that
CT scans cost more than X-rays (Document ID 2177, Attachment B, p. 40;
2178, Attachment 1, p. 6; 3541, p. 7). In addition, Collegium Ramazzini
stated that chest X-rays are readily accessible in most cases, but
availability of CT scanning is more limited, especially in rural areas
(Document ID 3541, p. 7).
ACOEM, NIOSH, APHA, NSSGA, EEI, and AFL-CIO stated that CT scans
are appropriate in some cases, such as a part of follow-up examinations
or if recommended by the PLHCP (Document ID 2080, p. 8; 2177,
Attachment B, pp. 40-41; 2178, Attachment 1, p. 6; 2327, Attachment 1,
p. 26; 2357, pp. 34-35; 4204, p. 82). Dr. David Weissman and Dr.
Rosemary Sokas, occupational physician from Georgetown University,
representing APHA, indicated that if an employee happens to have had a
CT scan that was conducted as part of a clinical workup or diagnosis,
it should be accepted in place of X-rays (Document ID 3577, Tr. 792;
3579, Tr. 256).
After reviewing the record on this issue, OSHA has determined that
CT or HRCT scans should not be considered "equivalent diagnostic
studies" to conventional film or digital chest X-rays for screening of
silicosis because of higher radiation exposures, lack of a standardized
classification system for pneumoconiosis, increased false positive
findings, higher costs, and limited availability in some areas. OSHA
also agrees with commenters that CT scans may be useful for follow-up
purposes, as determined on a case-by-case basis by the PLHCP. For
example, the PLHCP could request a CT scan to diagnose possible
abnormalities detected by X-ray or other testing done as part of
surveillance, and the rule gives the PLHCP this option (paragraph
(i)(2)(vi) of the standard for general industry and maritime, paragraph
(h)(2)(vi) of the standard for construction). However OSHA does not
agree that a CT scan conducted within the past three years can meet the
requirement for an X-ray because the CT scan cannot be evaluated
according to ILO methods.
OSHA also received comments on the use of CT scans to screen for
lung cancer, and those comments are discussed below, as part of the
Agency's discussion of additional tests that commenters proposed for
inclusion in medical examinations.
In sum, unlike the proposed rule, paragraph (i)(2)(iii) of the
standard for general industry and maritime (paragraph (h)(2)(iii) of
the standard for construction) specifically allows for digital X-rays,
but does not allow for an equivalent diagnostic study. The rule was
revised to allow for digital radiography because OSHA determined that
digital X-rays are equivalent to film X-rays. The rule was also revised
to remove the allowance for equivalent diagnostic studies because OSHA
determined that CT scans are not equivalent to X-rays for screening
purposes and no other imaging tests are equivalent to film or digital
X-rays interpreted by ILO methods at this time. The provision for X-
rays does not contain any other substantive changes compared to the
proposed provision.
The fourth item required as part of the initial medical examination
is a pulmonary function test, including forced vital capacity (FVC),
forced expiratory volume in one second (FEV1), and
FEV1/FVC ratio, administered by a spirometry technician with
a current certificate from a NIOSH-approved spirometry course
(paragraph (i)(2)(iv) of the standard for general industry and
maritime, paragraph (h)(2)(iv) of the standard for construction). FVC
is the total volume of air exhaled after a full inspiration,
FEV1 is the volume of air exhaled in the first second, and
the FEV1/FVC ratio is the speed of expired air (Document ID
3630, p. 2). OSHA proposed the inclusion of pulmonary function testing
(i.e., spirometry, as required by this rule) because it is useful for
obtaining information about the employee's lung capacity and expiratory
flow rate and for determining baseline lung function status against
which to assess any subsequent lung function changes.
Some industry representatives, such as Fann Contracting and CISC,
opposed the requirement for spirometry testing because reduced
pulmonary function can be related to smoking or exposures other than
respirable crystalline silica (Document ID 2116, Attachment 1, Page 39;
2319, pp. 118-119). CISC further commented that OSHA did not address
statements in the ASTM standard about the non-specificity of lung
function changes to respirable crystalline silica exposure, and a lack
of evidence that routine spirometry is useful for detecting respirable
crystalline silica-related diseases in early stages.
In contrast, commenters, such as Collegium Ramazzini and NIOSH,
noted that spirometry is useful for detecting lung function changes
associated with COPD, a disease outcome related to respirable
crystalline silica exposure (Document ID 3541, p. 8; 3579, Tr. 255).
ACOEM and Collegium Ramazzini explained that respirable crystalline
silica exposures can result in lung function changes in the absence of
radiological abnormalities, and spirometry is important for detecting
those changes in the early stages of disease; ACOEM further commented
that early detection of abnormal lung function is important to fully
assess employees' health and apply protective intervention methods
(Document ID 2080, p. 8; 3541, p. 8).
ASSE and some industry representatives, including Newmont Mining,
NISA and AFS, also supported spirometry testing (e.g., Document ID
1963, pp. 2-3; 2339, p. 9; 2379, Appendix 1, p. 70; 4208, p. 22). NISA
includes spirometry testing as part of its occupational health program
for respirable crystalline silica-exposed employees; it emphasized that
spirometry testing: (1) Allows for early detection and measurement of
severity of lung function loss, the most direct symptom of silicosis or
other nonmalignant respiratory disease, and (2) is useful for
determining an employee's ability to safely wear a negative pressure
respirator (Document ID 4208, p. 22).
After reviewing the comments submitted, OSHA reaffirms that
spirometry testing should be included in the rule. OSHA concludes that
even though declines in lung function may not always be related to
respirable crystalline silica exposure, the test results are
nonetheless useful for detecting lung function abnormalities that can
worsen with further exposure to respirable crystalline silica,
providing a baseline of lung function status against which to assess
any subsequent changes, and assessing the health of employees who wear
respirators. The requirement for lung function testing is also
consistent with other OSHA standards, such as asbestos (29 CFR
1910.1001) and cadmium (29 CFR 1910.1027). Thus, OSHA decided to retain
the proposed requirement for a pulmonary function test in the rule.
OSHA proposed that spirometry be administered by a spirometry
technician with current certification from a NIOSH-approved spirometry
course. NIOSH recommended changing "current certification" to "a
current certificate" to clarify that NIOSH does not certify individual
technicians (Document ID 2177, Attachment B, p. 43). OSHA agrees with
NIOSH that the change provides clarity, without modifying the original
meaning of the provision, and thus made the change to the proposed
provision.
Some stakeholders questioned whether a certificate from a NIOSH-
approved course should be required. For example, Dow Chemical recommended
that OSHA follow the asbestos standard and allow for spirometry testing
to be conducted by a person who has completed "a training course in
spirometry sponsored by an appropriate academic or professional
institution" (29 CFR 1910.1001(l)(1)(ii)(B)) (Document ID 2270, pp. 11-12).
However, other stakeholders, including NIOSH and commenters from the
medical community and labor unions, agreed that the standard should require
a current certificate from a NIOSH-approved course (Document ID 2157, p. 6;
2177, Attachment B, pp. 38-39, 43; 3541, p. 10; 3577, Tr. 777; 4223, pp.
129-130). Dr. Robert Cohen stated:
...spirometry performed by certified NIOSH technicians would be
very important. We don't want garbage spirometry that we see out in
the industry all the time. We want real, not what I call cosmetic or
ceremonial spirometry (Document ID 3577, Tr. 777).
Dr. James Cone noted an example in which a NIOSH Health Hazard
Evaluation at a foundry found that the company had recorded abnormal
pulmonary function test results for 43 employees; however, spirometry
testing later conducted by NIOSH found that only 9 of those same
employees had abnormal pulmonary function results. Dr. Cone thought
that the difference in findings most likely resulted from differences
in equipment and test procedures used to motivate and elicit
cooperation of employees during testing (Document ID 2157, pp. 4-5). He
concluded:
The difference does suggest that proper equipment, certification
and training of pulmonary technicians, and standardized reading of
pulmonary function tests are important to maintain uniformity and
comparability of such tests (Document ID 2157, p. 5).
Some commenters, including Collegium Ramazzini, suggested other
ways that the rule for respirable crystalline silica could improve
quality of spirometry results. It recommended that the rule specify
spirometry conducted according to ATS/European Respiratory Society
(ERS) or similar guidelines, that spirometers meet ATS/ERS
recommendations, and that the third National Health and Nutrition
Examination Survey (NHANES III) reference values be used for
interpretation of results (Document ID 3541, pp. 8-10). Collegium
Ramazzini emphasized that quality spirometry results depend on
standardized equipment, test performance, and interpretation of
results, including criteria, such as acceptability and reproducibility
of results (Document ID 3541, p. 8). Labor unions, such as LHSFNA and
BCTD, also supported more stringent spirometry requirements (Document
ID 3589, Tr. 4205; 4223, pp. 129-130). ACOEM, NIOSH, and BCTD
recommended that reference values or other spirometry guidelines be
added to the appendix on medical surveillance (Document ID 2080, p. 9;
2177, Attachment B, pp. 45-46; 4223, pp. 128-129).
After considering the record to determine what the rule must
include to improve spirometry quality, OSHA concludes that requiring
technicians to have a current certificate from a NIOSH-approved
spirometry course is essential for maintaining and improving spirometry
quality. The purpose of requiring spirometry technicians to have a
current certificate from a NIOSH-approved spirometry course is to
improve their proficiency in generating quality results that are
interpreted in a standardized way. OSHA included the certification
requirement in the proposed rule because spirometry must be conducted
according to strict standards for quality control and results must be
consistently interpreted. The NIOSH-approved spirometry training is
based upon procedures and interpretation standards developed by the
ATS/ERS and addresses factors, such as instrument calibration, testing
performance, data quality, and interpretation of results (Document ID
3625, pp. 2-3).
NIOSH approves a spirometry training course if it meets the minimum
OSHA/NIOSH criteria for performance of spirometry testing in the cotton
textile industry. Since these course criteria are based on
recommendations from ATS/ERS, they are applicable to spirometry testing
in all industries. The curriculum of NIOSH-approved courses encompasses
ATS/ERS recommendations on instrument accuracy (e.g., calibration
checks); test performance (e.g., coaching, recognizing improperly
performed maneuvers), and data quality with emphasis on repeatability
and interpretation of results. Students taking the course use actual
equipment, while supervised, and are evaluated on their spirometry
testing skills (Document ID 3625, pp. 2-3). NIOSH periodically audits
spirometry course sponsors who provide the courses
(see http://www.cdc.gov/niosh/topics/spirometry/sponsor-renewal-dates.html).
Therefore, based on the evidence in the record for this rulemaking,
OSHA concludes that completing a NIOSH-certified course will make
spirometry technicians knowledgeable about various issues that
commenters raised regarding spirometry quality, and has determined that
the best way to ensure that spirometry technicians receive the level of
quality training approved by NIOSH is to require a certificate from a
NIOSH-approved course.
In considering the alternative suggestions, OSHA concludes that
requiring a current certificate from a NIOSH-approved course is a
better approach than mandating requirements for equipment, testing
procedures, reference values, and interpretation of results, which
could become outdated. OSHA fully expects that the NIOSH-approved
initial and periodic refresher courses required to maintain a current
certificate under this rule will ensure that technicians keep up-to-
date on the most recent ATS/ERS recommendations on spirometry equipment
and procedures as technology and methods evolve over time.
In addition, OSHA agrees with commenters that the NHANES III
reference values should be used to interpret spirometry results because
they are the most widely endorsed for use in the U.S. (Document ID
3630, p. 28-29). In cross-sectional testing to evaluate lung function
at a single point in time, spirometry results are compared to reference
values (i.e., spirometry values for individuals of the same gender,
age, height, and ethnicity as the employee being tested). Although
agreeing with commenters on the value of spirometry testing and use of
the NHANES III data set for cross-sectional testing, OSHA disagrees
with commenters that procedures for conducting spirometry and NHANES
III reference values should be included as part of an appendix. As
stated above, OSHA's approach to improving spirometry quality is to
require technicians to have a current certificate from a NIOSH-approved
course. Describing procedures in an appendix is not necessary because
spirometry guidance documents, including a comprehensive guidance
document from OSHA, are widely available. The OSHA spirometry guidance
is available from the OSHA Web site and lists the NHANES III values in
an appendix. OSHA encourages individuals who conduct or interpret
spirometry to review the OSHA guidance on spirometry, which is based on
recommendations by ATS/ERS, ACOEM, and NIOSH (Document ID 3630; 3624;
3629; 3631; 3633; 3634).
OSHA received one comment regarding the practicality of requiring a
current certificate from a NIOSH-approved course. Dow Chemical claimed
that availability of NIOSH-approved courses may be limited outside of
metropolitan areas (Document ID 2270, p. 11). However, NIOSH's Web site
indicates that course sponsors are located throughout the U.S. and that
some sponsors will travel to a requested site to teach a course
(Document ID 3625, p. 3). Moreover, Dow Chemical also reported that it
and another local company had teamed up to bring in an instructor to
teach a NIOSH-approved course in their geographical area (Document
ID 2270, p. 11). OSHA expects that this is a cost-effective means
of providing NIOSH-approved training in places where none currently
exists and can be replicated by other spirometry providers that
provide services to companies covered by this rule. Maintaining a
certificate from a NIOSH-approved course currently requires initial
training and then refresher training every five years (Document ID
3625, p. 1). Because courses appear to be widely available throughout
the U.S. and the required training is infrequent, OSHA concludes that
the requirement for a technician to maintain a certificate from a
NIOSH-approved course will not impose substantial burdens on providers
of spirometry testing.
The fifth item required as part of the initial medical examination
is a test for latent tuberculosis infection (paragraph (i)(2)(v) of the
standard for general industry and maritime, paragraph (h)(2)(v) of the
standard for construction). This provision is unchanged from the
proposed rule. "Latent" refers to a stage of infection that does not
result in symptoms or possible transmission of the disease to others.
OSHA proposed the inclusion of a test for latent tuberculosis infection
because exposure to respirable crystalline silica increases the risk of
a latent tuberculosis infection becoming active (i.e., the infected
person shows signs and symptoms and is contagious), even in employees
who do not have silicosis (see Section VI, Final Quantitative Risk
Assessment and Significance of Risk) (Document ID 0360; 0465; 0992,
p.1461-1462). This places not only the employee, but also his or her
coworkers, at increased risk of acquiring this potentially fatal
disease.
OSHA sought comment on its preliminary determination that all
employees receiving an initial medical examination should be tested for
latent tuberculosis infection. A number of stakeholders, including Dr.
James Cone, ATS, NIOSH, APHA, NISA, NSSGA, ASSE, BCTD, and ACOEM agreed
with OSHA's preliminary conclusion that testing for latent tuberculosis
infection should be part of the initial examination (e.g., Document ID
2157, p. 6; 2175, p. 6; 2177, Attachment B, pp. 38-39; 2178, Attachment
1, p. 5; 2195, p. 41; 2327, Attachment 1, p. 23; 2339, p. 9; 2371,
Attachment 1, p. 43). However, other stakeholders, such as Newmont
Mining, Nevada Mining Association, and EEI, recommended that testing
for latent tuberculosis infection be limited to employees who have
silicosis (e.g., Document ID 1963, p. 2; 2107, p. 3; 2357, p. 34). EEI
specifically opposed testing for latent tuberculosis infection in the
absence of radiological evidence of silicosis, arguing that there are
no good methods for quantifying the benefits of that testing.
After reviewing the comments on this issue, OSHA affirms its
conclusion that testing for latent tuberculosis infections is a
necessary and important part of the initial examination. As noted
above, evidence demonstrates that exposure to respirable crystalline
silica increases the risk for developing active pulmonary tuberculosis
infection in individuals with latent tuberculosis infection,
independent of the presence of silicosis (Document ID 0360; 0465; 0992,
pp. 1461-1462). Active tuberculosis cases are prevented by identifying
and treating those with latent tuberculosis infections. Therefore, OSHA
concludes it is appropriate to test for latent tuberculosis infection
in all employees who will be exposed to respirable crystalline silica
and are eligible for medical surveillance, for their protection and to
prevent transmission of an active, potentially fatal infection to their
coworkers. Any concerns about a lack of good methods for calculating
benefits associated with latent tuberculosis infection testing do not
negate the scientific evidence demonstrating that exposure to
respirable crystalline silica increases the risk of a latent infection
becoming active.
Newmont Mining, Nevada Mining Association, and Fann Contracting did
not support testing for latent tuberculosis infection because employees
with the infection may not have contracted it in an occupational
setting (Document ID 1963, p. 2; 2107, p. 3; 2116, Attachment 1, p.
38). While that may be true, testing for latent tuberculosis infection
provides another example and support for two of the main objectives of
medical surveillance: (1) To identify conditions that might make
employees more sensitive to respirable crystalline silica exposure; and
(2) to allow for intervention methods to prevent development of serious
disease. Employees with latent tuberculosis infections are at greater
risk of developing active disease with exposure to respirable
crystalline silica, and informing them that they have a latent
infection allows for intervention in the form of treatment to eliminate
the infection. Treating latent tuberculosis disease before it becomes
active and can be transmitted to coworkers (and others) is in the best
interest of both the employer and the affected employee.
Dr. James Cone and APHA have stated that a positive boosted or
initial test for tuberculosis infection warrants medical referral for
further evaluation (Document ID 2157, p. 6; 2178, Attachment 1, p. 5).
Ameren commented that a positive tuberculosis test warrants medical
removal (Document ID 2315, p. 9). OSHA agrees that employees who test
positive for active tuberculosis should be referred to their local
public health departments as required by state public health law
(Document ID 2177, Attachment B, p. 50). Those employees will need
treatment and, if necessary, to be quarantined until they are no longer
contagious. That is the appropriate action for employees with active
tuberculosis to prevent infection of coworkers and others, according to
procedures established by state public health laws. In the case of
latent tuberculosis, the PLHCP may refer the employee to the local
public health department, where the employee may get recommendations or
prescriptions for treatment. Removal is not necessary for latent
tuberculosis infections because employees with latent tuberculosis
infections are not contagious. More information about testing for
latent tuberculosis infections is included in Appendix B.
The sixth and final item required as part of the initial medical
examination is any other test deemed appropriate by the PLHCP
(paragraph (i)(2)(vi) of the standard for general industry and
maritime, paragraph (h)(2)(vi) of the standard for construction). This
provision, which is unchanged from the proposed rule, gives the
examining PLHCP the flexibility to determine additional tests deemed to
be appropriate. While the tests conducted under this section are for
screening purposes, diagnostic tests may be necessary to address a
specific medical complaint or finding related to respirable crystalline
silica exposure (Document ID 1511, p. 61). For example, the PLHCP may
decide that additional tests are needed to address abnormal findings in
a pulmonary function test. OSHA considers the PLHCP to be in the best
position to decide if any additional medical tests are necessary for
each individual examined. Under this provision, if a PLHCP decides
another test related to respirable crystalline silica exposure is medically
indicated, the employer must make it available. EEI commented that OSHA
should clarify that additional tests must be related to occupational
exposure to respirable crystalline silica (Document ID 2357, p. 35).
OSHA agrees and intends the phrase "deemed appropriate" to mean that
additional tests requested by the PLHCP must be both related to
respirable crystalline silica exposure and medically necessary, based
on the findings of the medical examination.
Finally, some stakeholders suggested additional tests to be
included as part of medical examinations. OSHA did not propose a
requirement for the initial examination to include a CT scan to screen
for lung cancer, but a number of commenters thought the rule should
contain such a requirement. UAW requested that OSHA consider LDCT
scanning for lung cancer, with guidance from NIOSH and other medical
experts (Document ID 2282, Attachment 3, pp. 19-20). Charles Gordon
asked Dr. David Weissman if OSHA should consider CT scans for lung
cancer screening of silica-exposed employees, as has been recently
recommended by the U.S. Preventive Service Task Force (USPSTF) for
persons at high risk of lung cancer. Dr. Weissman responded:
Well, the recommendation that you're referring to related to
very heavy cigarette smokers, people who are age 55 to 80, had a
history of smoking I believe at least 30 pack-years and had smoked
as recently as 15 years ago. That group has a very, very high risk
of lung cancer, and as of this time, there are no recommendations
that parallel that for occupational carcinogens (Document ID 3579,
Tr. 159-160, Attachment 2, p. 2).
Collegium Ramazzini and USW asked OSHA to consider various
scenarios for LDCT lung cancer screening of employees exposed to
respirable crystalline silica; the different scenarios considered age
(as a proxy for latency), smoking history, and other risk factors, such
as non-malignant respiratory disease (Document ID 4196, pp. 5-6; 4214,
pp. 10-12). Both groups recommended screening in non-smokers, and
Collegium Ramazzini also recommended screening in employees less than
50 years of age; both groups cited National Comprehensive Cancer
Network (NCCN) guidelines as a basis for one or more recommendations,
and Collegium Ramazzini also cited the American Association for
Thoracic Surgery (AATS) guidelines. The Communication Workers of
America (CWA) requested LDCT scans every three years for silica-exposed
employees over 50 years of age (Document ID 2240, p. 3). Consistent
with one scenario presented by USW, AFL-CIO requested that OSHA require
LDCT scans if recommended by the PLHCP or specialist, and AFL-CIO also
requested that OSHA include a provision (for employees exposed to
respirable crystalline silica) to allow for regular LDCT scans if
recommended by an authoritative group (Document ID 4204, p. 82). Dr.
Rosemary Sokas and Dr. James Melius, occupational physician/
epidemiologist for LHSFNA, requested that OSHA reserve the right to
allow for adoption of LDCT scans (Document ID 3577, Tr. 793; 3589, Tr.
4205-4206). Dr. Sokas went on to say that OSHA should start convening
agencies and organizations to look at levels of risk that warrant LDCT
(Document ID 3577, Tr. 793).
In addition to the issues that Dr. Weissman testified about
regarding the USPSTF recommendations, OSHA notes that the USPSTF
recommendations are based on modeling studies to determine optimum ages
and frequency for screening and the scenarios in which benefits of LDCT
screening (e.g., increased survival) would outweigh harms (e.g., cancer
risk from radiation exposure). The screening scenario recommended by
USPSTF (55- to 80-year-olds with a 30-pack-year smoking history who
have not quit more than 15 years ago) is estimated to result in a 14
percent decrease in lung cancer deaths, with a less than 1 percent risk
for radiation-related lung cancer (Document ID 3965, p. 337). USPSTF
stresses that LDCT screening should be limited to high-risk persons
because persons at lower risk are expected to experience fewer benefits
and more harm; they cautioned that starting LDCT screening before age
50 might result in increased rates of radiation-related lung cancer
deaths (Document ID 3965, p. 336). USPSTF also warns about the high
rate of false positive findings with LDCT, which often lead to more
radiation exposure through additional imaging tests and can result in
invasive procedures, which have their own risks, to rule out cancer. It
cautions that lower rates of lung cancer mortality from LDCT screening
are most likely to be found at institutions demonstrating accurate
diagnoses, appropriate follow-up procedures for abnormal findings, and
clear standards for performing invasive procedures (Document ID 3965,
pp. 333, 336).
Both NCCN and AATS guidelines recommend screening scenarios that
are similar to the USPSTF guideline (e.g., 55 or more years of age and
at least a 30-pack-year history) (Document ID as cited in 3965, p. 338;
3976, p. 33). NCCN and AATS guidelines also recommend screening for 50-
year-olds or older, who have a 20-pack-year or more smoking history and
an additional risk factor. AATS specifies that the additional risk
factor should result in a cumulative lung cancer risk of at least 5
percent in the next 5 years, and they identify additional risk factors,
such as COPD, with an FEV1 of 70 percent or less of
predicted value, and environmental or occupational exposures, including
silica (Document ID 3976, pp. 33, 35-37). Neither the NCCN nor AATS
guideline recommend screening for individuals younger than 50 years of
age or nonsmokers, and neither NCCN nor AATS indicates that its
guidelines are based on risk-benefit analyses.
OSHA agrees that employees exposed to respirable crystalline silica
are at increased risk of developing lung cancer, as addressed in
Section V, Health Effects. However, OSHA has two major concerns that
preclude the Agency from requiring LDCT screening for lung cancer under
the respirable crystalline silica rule. The first concern is that
availability of LDCT is likely to be limited. Few institutions that
offer LDCT have the specialization to effectively conduct screening for
lung cancer. The second major concern is the lack of a risk-benefit
analysis. There is no evidence in the rulemaking record showing that
the benefits of lung cancer screening using LDCT in respirable
crystalline silica-exposed employees outweigh the risks of lung cancer
from radiation exposure. OSHA has also not identified authoritative
recommendations based on risk-benefit analyses for LDCT scanning for
lung cancer in persons who do not smoke or are less than 50 years of
age. OSHA concludes that without authoritative risk-benefit analyses,
the record does not support mandating LDCT screening for respirable
crystalline silica-exposed employees.
Periodic examinations. In paragraph (i)(3) of the standard for
general industry and maritime (paragraph (h)(3) of the standard for
construction), OSHA requires periodic examinations that include all of
the items required by the initial examination, except for testing for
latent tuberculosis infection, i.e., a medical and work history, a
physical examination emphasizing the respiratory system, chest X-rays,
pulmonary function tests, and other tests deemed to be appropriate by
the PLHCP. Employers must offer these examinations every three years,
or more frequently if recommended by the PLHCP. The frequency of
periodic examinations and their requirements is unchanged from the
proposed rule.
Some commenters disagreed with the proposed three-year interval for
periodic medical examinations. WisCOSH and Charles Gordon thought that
medical examinations should be offered more often than every three
years (Document ID 3586, Tr. 3200-3201; 2163, Attachment 1, p. 14).
Other commenters, including AFSCME and some employee health advocates
and labor unions, requested that one or more components of medical
examinations be offered annually (Document ID 1960; 2208; 2240, p. 3;
2351, p. 15; 4203, p. 6). Collegium Ramazzini recommended annual
medical surveillance consisting of medical and work history and
spirometry testing to better characterize symptoms, changes in health
and work history that could be forgotten, and lung function changes
(Document ID 3541, p. 12). CISC stated that OSHA did not explain why it
found an examination every three years necessary and appropriate
(Document ID 2319, p. 119).
ATS, NIOSH, USW, and AFS supported the three-year frequency
requirement for medical surveillance (Document ID 2175, p. 6; 2177,
Attachment B, pp. 38-39; 2336, p. 11; 2379, Appendix 1, p. 70). NSSGA,
however, recommended examinations every three to five years (Document
ID 2327, Attachment 1, p. 24). Although WHO guidelines recommend an
annual history and spirometry test, the guidelines state that if that
is not possible, those examinations can be conducted at the same
frequency they recommend for X-rays (every 2-to-5 years) (Document ID
1517, p. 32). In support of triennial medical examinations, ATS
commented that an examination provided every three years is appropriate
to address a lung disease that typically has a long latency period
(Document ID 2175, p. 6).
ACOEM agreed with a frequency of every three years for a medical
examination, provided that a second baseline examination (excluding X-
rays) is conducted at 18 months following the initial baseline
examination; this approach was recommended to detect possible symptoms
of acute silicosis and to more effectively establish a spirometry
baseline since rapid declines in lung function can occur in dusty work
environments (Document ID 2080, pp. 5-6). Dr. Celeste Monforton agreed
with a follow-up examination at 18 months (Document ID 3577, Tr. 846).
APHA, AFL-CIO, BAC, and BCTD also agreed with ACOEM's suggestion
for a follow-up examination within 18-months, adding that a three-year
interval between examinations is acceptable if medical examinations are
offered to employees experiencing signs and symptoms related to
respirable crystalline silica exposure (Document ID 2178, Attachment 1,
pp. 4-5; 4204, pp. 81-82; 4219, pp. 30-31; 4223, pp. 127-128).
BlueGreen Alliance, UAW, Center for Effective Government (CEG), CPR,
WisCOSH, and AFSCME also requested that medical surveillance be offered
for employees experiencing symptoms (Document ID 2176, p. 2; 2282,
Attachment 3, pp. 22-23; 2341, pp. 2-3; 2351, p. 15, Fn 29; 3586, Tr.
3200-3201; 4203, p. 6). The AFL-CIO and UAW stated that a symptom
trigger is appropriate based on the high level of risk remaining at
OSHA's proposed action level and PEL (Document ID 2282, Attachment 3,
p. 22; 4204, p. 81). APHA, CEG, and BCTD also argued that employees
should be allowed to see a PLHCP if they are concerned about excessive
exposure levels or their ability to use a respirator (Document ID 2178,
p. 5: 2341, pp. 2-3; 4223, pp. 127-128).
After considering all comments on this issue, OSHA concludes that
the record supports requiring periodic examinations to be offered to
employees at least every three years after the initial (baseline) or
most recent periodic medical examination for employees who are eligible
for initial and continued medical surveillance under the rule.
Accordingly, paragraph (i)(3) of the standard for general industry and
maritime (paragraph (h)(3) of the standard for construction) requires
periodic examinations at least every three years, or more frequently if
recommended by the PLHCP. One of the main goals of periodic medical
surveillance for employees exposed to respirable crystalline silica is
to detect adverse health effects, such as silicosis and other non-
malignant lung diseases, at an early stage so that medical and other
appropriate interventions can be taken to improve health. Consistent
with the NIOSH and ATS comments, OSHA finds that medical examinations
offered at a frequency of at least every three years is appropriate for
most employees exposed to respirable crystalline silica in light of the
slow progression of most silica-related diseases. This decision is also
consistent with ASTM standards E 1132-06 and E 2625-09 (Section 4.6.5),
which recommend that medical surveillance be conducted no less than
every three years (Document ID 1466, p. 5; 1504, p. 5).
OSHA declines to adopt ACOEM's recommendation for a second baseline
examination at 18 months. As noted above, this request was based upon
detection of possible acute silicosis symptoms. Considering that acute
silicosis and the rapid declines in lung function associated with it,
as a result of extremely high exposures, are rare, OSHA determines that
this extra examination would not benefit the vast majority of employees
exposed to respirable crystalline silica. However, as noted above,
paragraph (i)(3) of the standard for general industry and maritime
(paragraph (h)(3) of the standard for construction) authorizes the
PLHCP to recommend, and requires the employer to make available,
increased frequency of medical surveillance. OSHA agrees with Dr. James
Melius that more frequent medical examinations are appropriate if
requested by the PLHCP based on abnormal findings or signs of possible
illness, and the Agency agrees with ACOEM that the PLHCP may recommend
more frequent medical surveillance based on an exposure history
indicating unknown or high exposure to respirable crystalline silica
(Document ID 2080, p. 6; 3589, Tr. 4203). OSHA concludes that allowing
the PLHCP to determine when increased frequency of medical examinations
is needed is a better approach than requiring all employees to receive
annual medical examinations or a second baseline examination at 18
months.
OSHA did not include a symptom trigger because symptoms of silica-
related lung diseases (e.g., cough, shortness of breath, and wheeze)
are very common and non-specific, unlike symptoms resulting from
exposures to some other chemicals OSHA has regulated. In addition,
based on the employee health privacy concerns expressed in this
rulemaking (discussed below), OSHA does not expect many employees to
ask their employer for a medical examination when they experience
symptoms. Furthermore, employees who are the most likely to develop
symptoms are those exposed above the PEL. Those employees, who would be
required to wear respirators, and also construction employees required
to wear respirators under Table 1, are entitled to an additional
medical evaluation under the respiratory protection standard if they
report signs or symptoms that are related to ability to use a
respirator (29 CFR 1910.134(e)(7)(i)). Therefore, employees at the
highest risk of developing symptoms will be able to take advantage of
that provision in the respiratory protection standard.
AIHA recommended that OSHA consider decreased frequency of testing
in employees with less than 10 to 15 years of experience because of the
small chance of finding disease, and it noted that this was done in the
asbestos standard (29 CFR 1910.1001, 1926.1101) (Document ID 2169, p. 6).
Medical surveillance guidelines from ACOEM, Industrial Minerals
Association (IMA)/Mine Safety and Health Administration (MSHA) and NISA
recommend periodic medical examinations at intervals from two to four
years (with the exception of a follow-up examination in some cases),
depending on age, years since first exposure, exposure levels, or
symptoms (Document ID 1505, pp. 3-4; 1511, pp. 78-79; 1514, pp. 109-110).
As noted by the IMA/MSHA guidelines, a compromise schedule that is easier
to administer is acceptable if it is difficult to offer surveillance based
on multiple considerations (Document ID 1511, pp. 78-79). OSHA agrees with
the IMA/MSHA approach of choosing a schedule that is easy to administer.
The Agency concludes that surveillance every three years is an
administratively convenient frequency that strikes a reasonable balance
between the resources required to provide surveillance and the need to
diagnose health effects at an early stage to allow for interventions.
In addition to the above general comments as to the appropriate
frequency of periodic examinations, some stakeholders offered comments
on particular components of periodic examinations, in particular chest
X-rays and pulmonary function tests. As noted above, chest X-rays are
included in the periodic, as well as initial (baseline), medical
examinations. Periodic chest X-rays are appropriate tools for detecting
and monitoring the progression of silicosis and possible complications,
such as mycobacterial disease, including tuberculosis infection
(Document ID 1505, p. 3; 1511, pp. 63, 79). Safety professional Albert
Condello III stated that X-rays should be offered annually (Document ID
1960). OSHA concludes that every three years is an appropriate interval
for X-ray examinations. The frequency is within ranges recommended by
ACOEM, IMA/MSHA, NISA, and WHO (Document ID 1505, pp. 3-4; 1511 pp. 78-
79; 1514, pp. 109-110; 1517, p. 32). Commenters representing NIOSH, the
medical community, and industry agreed that a frequency of every three
years is appropriate for X-rays (Document ID 2157, p. 6; 2177,
Attachment B, pp. 38-39; 2315, p. 9; 2327, Attachment 1, p. 25; 2379,
Appendix 1, p. 70; 3541, p. 5).
OSHA also received comments on the inclusion of pulmonary function
(i.e., spirometry) tests in periodic examinations and the appropriate
frequency for such tests. As noted under the discussion of tests
included as part of the initial medical evaluation, some commenters
questioned whether spirometry in general should be required for
employees exposed to respirable crystalline silica. For the same reason
that OSHA decided to include spirometry as a required element in the
initial medical examination, it concludes that requiring spirometry as
part of the periodic examination is appropriate; that reason is that a
spirometry test is a valuable tool for detecting possible lung function
abnormalities associated with respirable crystalline silica-related
disease and for monitoring the health of exposed employees. Spirometry
tests that adhere to strict quality standards and that are administered
by a technician who has a current certificate showing successful
completion of a NIOSH-approved spirometry course, are useful for
monitoring progressive lung function changes in individual employees
and in groups of employees.
The proposed interval of three years for spirometry testing was an
issue in the rulemaking. OSHA proposed this interval because exposure
to respirable crystalline silica does not usually cause severe declines
in lung function over short time periods. Spirometry testing conducted
every three years is within ranges of recommended frequencies, based on
factors such as age and exposure duration or intensity, in guidelines
by ACOEM and BCTD, although ACOEM and BCTD recommend an evaluation at
18 months following the baseline test (Document ID 1505, p. 3; 1509, p.
15; 2080, pp. 5-6; 4223, p. 128). Guidelines from WHO recommend yearly
spirometry tests, but indicate that if that is not possible, spirometry
can be conducted at the same frequency as X-rays (every 2-to-5 years)
(Document ID 1517, p. 32).
OSHA specifically requested comment on the appropriate frequency of
lung function testing, which it proposed at intervals of every three
years. ASSE agreed that spirometry testing every three years is
consistent with most credible occupational health programs for
respirable crystalline silica exposure (Document ID 2339, p. 9).
Industry stakeholders, such as Ameren, NSSGA, and AFS, also supported
conducting spirometry testing every three years (Document ID 2315, p.
9; 2327, Attachment 1, pp. 24-25; 2379, Appendix 1, p. 70).
Collegium Ramazzini stated that spirometry testing should be
conducted annually rather than triennially (Document ID 3541, pp. 12-
13). In support of its statement, Collegium Ramazzini interpreted data
from a Wang and Petsonk (2004) study to mean that an FEV1
loss of 990 milliliters (mL) or higher could occur before detection of
lung function loss with testing every three years (Document ID 3541,
pp. 12-13; 3636).
The Wang and Petsonk 2004 study was designed to measure lung
function changes in coal miners over 6- to 12-month intervals. The
study authors reported that in the group of coal miners studied, a
year-to-year decline in lung function (i.e., FEV1) of 8
percent or 330 mL or more, based on the 5th percentile, should not be
considered normal (i.e., the results did not likely occur by chance in
healthy males). To understand the implications of this finding, OSHA
consulted 2014 ATS guidelines. Those guidelines urge caution in
interpreting early lung function changes in miners because early, rapid
declines in lung function are often temporary and might occur because
of inflammation. They further indicate that estimates of lung function
decline are more precise as the length of follow-up increases and that
real declines in lung function become easier to distinguish from
background variability. In addition, ATS cautions that short-term
losses in lung function can be difficult to evaluate because of
variability (Document ID 3632, pp. 988-989).
OSHA notes that, in fact, Figure 1 of the Wang and Petsonk study
shows that lung function loss measured over a 5-year period in that
cohort of miners is much less variable than changes measured over 6- to
12-month intervals. OSHA therefore finds that this study indicates that
long-term measurements in lung function are more reliable for assessing
the level of lung function decline over time. Based on Table 1 of the
Wang and Petsonk study, mean annual FEV1 loss, when
evaluated over a 5-year period, was 36 and 56 mL/year in stable and
healthy miners, respectively. Even among rapid decliners evaluated over
five years, mean decline in FEV1 was 122 mL/year. Unlike
Collegium Ramazzini, OSHA does not interpret the Wang and Petsonk study
to mean that an FEV1 loss of 990 mL or higher could occur
before detection of lung function loss with testing every three years
The study authors themselves conclude:
However, even among workers in our study who met this >8% or
>330 mL criterion, many did not show accelerated declines over the
entire 5 years of follow up (data not shown), emphasizing that a
finding of an increased year-to-year decline in an individual
requires further assessment and confirmation (Document ID 3636, p.
595).
In sum, OSHA finds that the Wang and Petsonk study is not a basis
for concluding that triennial spirometry testing is inadequate for
assessing lung function loss in most employees exposed to respirable
crystalline silica.
Collegium Ramazzini also cited a 2012 Hnizdo study that
demonstrated greater stability and predictability for excessive loss of
lung function with more frequent testing. In that study, spirometry
data were useful for predicting decline only after the fourth or fifth
year of follow-up; Collegium Ramazzini stated that only two spirometry
tests would be available in six years if employees are tested every
three years (Document ID 3541, p. 13; 3627, p. 1506). OSHA notes that
three spirometry reports would be available following six years of
triennial testing (the initial examination, the three-year examination,
and the six-year examination). In addition, Hnizdo concluded that
annual spirometry was best, but even in employees tested every three
years, useful clinical data were generated with five to six years of
follow-up (Document ID 3627, p. 1511).
The ATS committee also reviewed the Hnizdo study and concluded that
precision in determining rate of FEV1 decline improves with
greater frequency of measurement and duration of follow-up. Because
chronic diseases, such as COPD and pneumoconiosis, typically develop
over a span of years, the ATS committee concluded that spirometry
performed every two-to-three years should be sufficient to monitor the
development of such diseases (Document ID 3632, p. 988). NIOSH Division
of Respiratory Disease Studies Director, Dr. David Weissman, who was on
the ATS committee, also agreed that spirometry testing every three
years is appropriate for respirable crystalline silica-exposed
employees (Document ID 3632, p. 1; 3579, Tr. 255).
After consideration of the rulemaking evidence on this issue, OSHA
concludes that spirometry testing every three years is appropriate to
monitor employees' lung function and that the frequency is well
supported in the record. Therefore, consistent with its proposed rule,
OSHA is including a frequency of at least every three years for
spirometry testing.
As discussed above in connection with the initial testing
requirement, spirometry usually involves cross-sectional testing for
assessing lung function at a single time point. Longitudinal spirometry
testing that compares employees' lung function to their baseline levels
is also useful for detecting excessive declines in lung function that
could lead to severe impairment over time. OSHA did not propose a
requirement to assess longitudinal changes in lung function. Commenters
including Collegium Ramazzini, LHSFNA, and BCTD requested that the
standard include requirements or instructions for longitudinal testing
to compare an employee's current lung function value to his or her
baseline value (Document ID 3541, p. 10; 3589, Tr. 4205; 4223, p. 129).
As noted by Dr. L. Christine Oliver, associate clinical professor of
medicine at Harvard Medical School, representing Collegium Ramazzini:
Excessive loss of lung function may indicate early development
of silica-related disease, even in the absence of an abnormal test
result. So spirometry at one point in time may be normal, but
compared to the baseline of that individual, there may have been a
decline. So even though the test result itself is normal, it doesn't
mean that there is not something going on with regard to that
individual's lung function (Document ID 3588; Tr. 3855).
Both Collegium Ramazzini and BCTD requested that the standard
require referral to a specialist for excessive losses of pulmonary
function. Collegium Ramazzini recommended specialist referral for a
year-to-year decline in FEV1 of greater than 8 percent or
330 mL based on the study by Wang and Petsonk discussed above (Document
ID 3541, pp. 3, 9-10; 3636). BCTD recommended specialist referral for a
year-to-year decline in FEV1 of greater than 10 percent
based on ACOEM guidance (Document ID 4223, p. 129; 3634, pp. 579-580).
OSHA endorses in principle the value of longitudinal spirometry
analyses to compare employees' lung function to their baseline values,
but is not adopting the specific recommendation to incorporate it into
the rule. Based on a review of the available evidence, OSHA is
concerned about several challenges in determining an employee's change
from baseline values, which preclude the Agency from requiring
longitudinal analyses with an across-the-board trigger of 8-to-10
percent loss of baseline lung function for specialist referral. First,
a lung function loss of 8-to-10 percent is more stringent than general
recommendations from ACOEM and ATS. OSHA notes that the complete ACOEM
recommendation for evaluating longitudinal changes in lung function
states:
When high-quality spirometry testing is in place, ACOEM
continues to recommend medical referral for workers whose
FEV1 losses exceed 15%, after allowing for the expected
loss due to aging. Smaller declines of 10% to 15%, after allowing
for the expected loss due to aging, may be important when the
relationship between longitudinal results and the endpoint disease
is clear. These smaller declines must first be confirmed, and then,
if the technical quality of the pulmonary function measurement is
adequate, acted upon (Document ID 3634, p. 580).
The ACOEM recommendation is based on ATS guidelines indicating that
year-to-year changes in lung function exceeding 15 percent are probably
unusual in healthy individuals. A recent ATS committee restated that
position:
ATS recommends that a decline of 15% or more over a year in
otherwise healthy individuals be called "significant," beyond what
would be expected from typical variability (Document ID 3632, p.
989).
As ATS indicated, actual lung function losses must be distinguished
from measurement variability. Variability in spirometry findings can
occur as a result of technical factors (e.g., testing procedures,
technician competence, and variations in equipment) and biological
factors related to employees being tested (e.g., circadian rhythms,
illness, or recovery from surgery) (Document ID 3630, p. 32). The
requirement for testing by a technician with a current certificate from
a NIOSH-approved course improves spirometry quality and reduces
variability related to testing technique and technician competence.
However, OSHA is aware that even with high quality spirometry programs,
variability in results can still occur from factors such as changes in
equipment and/or testing protocol.
Collegium Ramazzini noted that spirometry performed at a location
other than that of the first employer may not provide an adequate
baseline to evaluate lung function changes in the absence of quality
control and standardized equipment, methodology, and interpretation
(Document ID 3541, p. 5). OSHA is concerned about the ability to
differentiate lung function changes from variability, even with
standardization and quality control. ACOEM has concluded that frequent
changing of spirometry providers may prevent a meaningful evaluation of
longitudinal testing results (Document ID 3633, p. 1309). OSHA
recognizes that changes in spirometry providers could preclude
evaluating changes in lung function from baseline values and that
employees in high-turnover industries, e.g., construction, could be
particularly affected if they undergo spirometry testing on different
types of spirometers used by different providers contracted by the
different employers for whom they work.
In addressing the issue of construction employees frequently
changing employers, Dr. L. Christine Oliver recommended storing
spirometry results in a central database or providing them to employees
to allow comparison of current results with past results
(Document ID 3588, Tr. 3873-3875). As indicated above, technical quality
of past spirometry should be evaluated before examining longitudinal
change in lung function. Full spirometry reports should be examined for
indicators of test quality (e.g., acceptability and repeatability of
spirometry maneuvers). OSHA encourages PLHCPs to give employees copies of
their full medical records, including spirometry reports with numerical
values and graphical illustrations of expiratory curves. Employees
(including former employees) also have a right to access their medical
records under OSHA's access to medical and exposure records rule (29
CFR 1910.1020). Presenting past spirometry records to a new PLHCP might
allow for the interpretation of lung function compared to baseline
values, but the PLHCP would have to determine if this evaluation is
possible based on spirometry technical quality.
In sum, OSHA recognizes the value of longitudinal analyses that
compare an individual's lung function to their baseline values. Recent
studies have shown that excessive decline in lung function can be an
early warning sign for risk of COPD development (Document ID 1516).
Therefore, identifying employees who are at risk of developing severe
decrements in lung function can allow for interventions to possibly
prevent or slow progression of disease and thus justifies periodic
spirometry. But because of the complexities and challenges described
above, OSHA is not mandating testing to compare employees' lung
function values to baseline values or specifying a lung function loss
trigger for referral to a specialist. OSHA concludes that spirometry
conducted every three years is appropriate to detect the possible
development of lung function impairment. However, the PLHCP is in the
best position to determine how spirometry results should be evaluated.
Under paragraph (i)(5)(iv) of the standard for general industry and
maritime (paragraph (h)(5)(iv) of the standard for construction),
PLHCPs have the authority to recommend referral to a specialist if
"otherwise deemed appropriate," and an informed judgment or suspicion
that excessive lung function loss or an actual lung function
abnormality has occurred would be an appropriate reason for referral to
a specialist with the necessary skills and capability to make that
evaluation.
Information provided to the PLHCP. Paragraph (i)(4)(i)-(iv) of the
standard for general industry and maritime (paragraph (h)(4)(i)-(iv) of
the standard for construction) requires the employer to ensure that the
examining PLHCP has a copy of the standard, and to provide the
following information to the PLHCP: A description of the employee's
former, current, and anticipated duties as they relate to respirable
crystalline silica exposure; the employee's former, current, and
anticipated exposure levels; a description of any personal protective
equipment (PPE) used, or to be used, by the employee, including when
and for how long the employee has used or will use that equipment; and
information from records of employment-related medical examinations
previously provided to the employee and currently within the control of
the employer. OSHA determined that the PLHCP needs this information to
evaluate the employee's health in relation to assigned duties and
fitness to use PPE.
Some of these provisions reflect minor edits from the proposed
rule. In paragraphs (i)(4)(i) and (iv) of the standard for general
industry and maritime (paragraphs (h)(4)(i) and (iv) of the standard
for construction), OSHA changed "affected employee" to "employee."
OSHA removed the word "affected" because it is clear that the
provisions refer to employees who will be undergoing medical
examinations. In paragraph (i)(4)(iii) of the standard for general
industry and maritime (paragraph (h)(4)(iii) of the standard for
construction), OSHA changed "has used the equipment" to "has used or
will use the equipment" to make it consistent with the earlier part of
the provision that states "personal protective equipment used or to be
used." These non-substantive changes simply remove superfluous
language or clarify OSHA's intent, which has not changed from the
proposed rule.
OSHA received few comments regarding information to be supplied to
the PLHCP. NAHB was concerned about obtaining or verifying information,
such as PPE use, exposure information, and medical information, from
past employers to give to the PLHCP (Document ID 2296, p. 31).
Paragraph (i)(4)(iv) of the standard for general industry and maritime
(paragraph (h)(4)(iv) of the standard for construction) is explicit,
however, that employers must only provide the information within their
control. Employers are not expected to provide information to PLHCPs on
exposures experienced by employees while the employees were working for
prior employers. Similarly, OSHA intends that where the employer does
not have information on the employee's past or current exposure level,
such as when a construction employer uses Table 1 in lieu of exposure
monitoring, providing the PLHCP with an indication of the exposure
associated with the task (e.g., likely to be above the PEL) fulfills
the requirement.
OSHA identifies the information that the employer must provide to
the PLHCP, along with information collected as part of the exposure and
work history, as relevant to the purposes of medical surveillance under
the rule because it can assist the PLHCP in determining if symptoms or
a health finding may be related to respirable crystalline silica
exposure or if the employee might be particularly sensitive to such
exposure. For example, a finding of abnormal lung function caused by
asthma might indicate increased sensitivity to a workplace exposure.
The information will also aid the PLHCP's evaluation of the employee's
health in relation to recommended limitations on the employee's use of
respirators or exposure to respirable crystalline silica. For these
reasons, OSHA is retaining the proposed provisions detailing
information to be provided to the PLHCP in the rule.
Written medical reports and opinions. The proposed rule provided
for the PLHCP to give a written medical opinion to the employer, but
relied on the employer to give the employee a copy of that opinion;
thus, there was no difference between information the employer and
employee received. The rule differentiates the types of information the
employer and employee receive by including two separate paragraphs
within the medical surveillance section that require a written medical
report to go to the employee, and a more limited written medical
opinion to go to the employer. The former requirement is in paragraph
(i)(5) of the standard for general industry and maritime (paragraph
(h)(5) of the standard for construction); the latter requirement is in
paragraph (i)(6) of the standard for general industry and maritime
(paragraph (h)(6) of the standard for construction). This summary and
explanation for those paragraphs first discusses the proposed
requirements and general comments received in response to the proposed
requirements. OSHA then explains in this subsection of the preamble its
decision in response to these comments to change from the proposed
requirement for a single opinion to go to both the employee and
employer and replace it with two separate and distinct requirements:
(1) A full report of medical findings, recommended limitations on
respirator use or exposure to respirable crystalline silica, and any
referral for specialist examination directly to the employee; and (2) an
opinion focused primarily on any recommended limitations on respirator
use, and with the employee's consent, recommended limitations on the
employee's exposure to respirable crystalline silica and referral to a
specialist. The ensuing two subsections will then discuss the specific
requirements and the record comments and testimony relating to those
specific requirements.
OSHA proposed that the employer obtain from the PLHCP a written
medical opinion containing: (1) A description of the employee's health
condition as it relates to exposure to respirable crystalline silica,
including any conditions that would put the employee at increased risk
of material impairment of health from further exposure to respirable
crystalline silica; (2) recommended limitations on the employee's
exposure to respirable crystalline silica or use of PPE, such as
respirators; (3) a statement that the employee should be examined by a
pulmonary disease specialist if the X-ray is classified as 1/0 or
higher by the B reader, or if referral to a pulmonary disease
specialist is otherwise deemed appropriate by the PLHCP; and (4) a
statement that the PLHCP explained to the employee the medical
examination results, including conditions related to respirable
crystalline silica exposure that require further evaluation or
treatment and any recommendations related to use of protective clothing
or equipment. The proposed rule would also have required the employer
to ensure that the PLHCP did not include findings unrelated to
respirable crystalline silica exposure in the written medical opinion
provided to the employer or otherwise reveal such findings to the
employer. OSHA raised the contents of the PLHCP's written medical
opinion, including privacy concerns, as an issue in the preamble of the
NPRM in Question 71 in the "Issues" section (78 FR at 56290).
OSHA received a number of comments on these provisions. The
majority of these comments related to the proposed contents of the
PLHCP's written medical opinion and its transmission to the employer.
For example, Dr. Laura Welch expressed concern that the provision that
would have required the PLHCP to disclose "a medical condition that
puts him or her at risk of material impairment to health from exposure
to silica" could be read to require disclosure of the employee's
medical diagnosis (Document ID 3581, Tr. 1580). Dr. Steven Markowitz,
physician and director of the Center for Biology of Natural Systems at
Queens College, representing USW, explained:
So, for example, if I were the examining healthcare provider and
I saw an employee, and he had what I identified as idiopathic
pulmonary fibrosis, which is diffuse scarring of the lungs with an
unknown cause, in this case, not silica, is that information that I
would need to turn over to the employer because further exposure to
silica might impair that person's health or not? Or what if the
worker has emphysema, which is a silica-related condition, and the
provider believes that that emphysema is not due to silica exposure
but to the employee's long-time smoking history. Is that information
that the healthcare provider is supposed to turn over to the
employer? It isn't at all clear (Document ID 3584, Tr. 2518-2519).
Some commenters offered suggestions to address privacy concerns
regarding the content of the proposed PLHCP's written medical opinion
for the employer and the proposed requirement that the opinion be given
to the employer instead of the employee. One suggestion advocated by
UAW, LHSFNA, AFSCME, AFL-CIO, and BCTD was for OSHA to use a model
based on the black lung rule for coal miners (Document ID 2282,
Attachment 3, pp. 20-21; 3589, Tr. 4207; 4203, p. 6; 4204, p. 88; 4223,
p. 134). Under the coal miner regulations, miners receive the medical
information and employers are prohibited from requiring that
information from miners (30 CFR 90.3). Commenters including BlueGreen
Alliance, CWA, USW, and Collegium Ramazzini also urged OSHA to require
that findings from medical surveillance only be given to employers upon
authorization by the employee (Document ID 2176, p. 2; 2240, pp. 3-4;
2336, p. 12; 3541, p. 13). UAW, AFL-CIO, and BCTD referred OSHA to
ACOEM's recommendations for workplace confidentiality of medical
information (Document ID 2282, Attachment 3, p. 20; 3578, Tr. 929;
3581, Tr. 1579-1580). The ACOEM guidelines state:
Physicians should disclose their professional opinion to both
the employer and the employee when the employee has undergone a
medical assessment for fitness to perform a specific job. However,
the physician should not provide the employer with specific medical
details or diagnoses unless the employee has given his or her
permission (Document ID 3622, p. 2).
Exceptions to this recommendation listed under the ACOEM guidelines
include health and safety concerns. Collegium Ramazzini, BCTD, USW, and
BAC argued that providing an employer with information about an
employee's health status violates an employee's privacy and is not
consistent with societal views reflected in laws, such as the Health
Insurance Portability and Accountability Act (HIPAA) (Document ID 3541,
p. 13; 3581, Tr. 1578-1579; 3584, Tr. 2519; 4219, p. 31).
Although HIPAA regulations allow medical providers to provide
medical information to employers for the purpose of complying with OSHA
standards (Document ID 4214, p. 7), OSHA has accounted for stakeholder
privacy concerns in devising the medical disclosure requirements in the
rule. OSHA understands that the need to inform employers about a
PLHCP's recommendations on work limitations associated with an
employee's exposure to respirable crystalline silica must be balanced
against the employee's privacy interests. As discussed in further
detail below, OSHA finds it appropriate to distinguish between the
PLHCP's recommendations and the underlying medical reasons for those
recommendations. In doing so, OSHA intends for the PLHCP to limit
disclosure to the employer to what the employer needs to know to
protect the employee, which does not include an employee's diagnosis.
Contrary to some of the comments, it was not OSHA's intent, either in
the proposed rule or in earlier standards that require information on
an employee's medical or health condition, to transmit diagnostic
information to the employer; OSHA intended for the PLHCP merely to
convey whether or not the employee is at increased risk from exposure
to respirable crystalline silica (or other workplace hazards in other
standards) based on any medical condition, whether caused by such
exposure or not. In re-evaluating how to express this intent, however,
OSHA concludes that the employer primarily needs to know about any
recommended limitations without conveying the medical reasons for the
limitations. Thus, in response to the weight of opinion in this
rulemaking record and to evolving notions about where the balance
between preventive health policy and patient privacy is properly
struck, OSHA is taking a more privacy- and consent-based approach
regarding the contents of the PLHCP's written medical opinion for the
employer compared to the proposed requirements and earlier OSHA
standards. These changes, which are reflected in paragraph (i)(6) of
the standard for general industry and maritime (paragraph (h)(6) of the
standard for construction), and the comments that led to these changes,
are more fully discussed below.
Reinforcing the privacy concerns, various stakeholders, including
labor unions, physicians, and employees, were also concerned that
employees' current or future employment might be jeopardized if medical
information is reported to employers (e.g., Document ID 2282, Attachment
3, p. 20; 3581, Tr. 1582; 3583, Tr. 2470-2471; 3585, Tr. 3053-3054; 3586,
Tr. 3245; 3589, Tr. 4227-4228, 4294-4295; 4203, pp. 6-7; 4214, pp. 7-8).
The same concerns were expressed by Sarah Coyne, a painter and Health and
Safety Director from the International Union of Painters and Allied Trades,
who testified that many of her fellow union members who have silicosis
refused to testify at the silica hearings because they feared they would
lose their jobs if their employers found out they were ill (Document ID 3581,
Tr. 1613-14). Dr. L. Christine Oliver testified that her patients do not want
medical information reported to employers, and Dr. James Melius stated
that LHSFNA members are leery of medical surveillance because they fear
losing their jobs (Document ID 3588, Tr. 3881-3882; 3589, Tr. 4228).
Deven Johnson, cement mason, described employees hiding injuries from
supervisors on jobsites for fear of being blacklisted, and said that:
The same is true with occupational illnesses, that the last
thing that a worker wants is to have any information that he's
somehow compromised because, even though we want to think the best
of the employer, that somebody wouldn't take action against that
individual, we know for a fact that it happens. It's happened to our
membership (Document ID 3581, Tr. 1656).
Industry representatives indirectly confirmed that discrimination
based on medical results was possible. For example, CISC noted that
some employers might refuse to hire an employee with silicosis because
they might have to offer workers' compensation or be held liable if the
disease progresses (Document ID 4217, pp. 22-23).
Evidence in the record demonstrates that a likely outcome of
employees' reluctance to let employers know about their health status
is refusal to participate in medical surveillance. For example, Dr.
Rosemary Sokas stated that employees who lack job security would likely
avoid medical surveillance if the employer receives the results
(Document ID 3577, Tr. 819-820). In discussing the Coal Workers' Health
Surveillance Program, Dr. David Weissman stated that maintaining
confidentiality is critical because:
One of the biggest reasons in focus groups that miners have
given for not participating in surveillance is fear of their medical
information being shared without their permission (Document ID 3579,
Tr. 169).
When asked if employees would participate in medical surveillance
that lacked both employee confidentiality and anti-retaliation and
discrimination protection, employees Sarah Coyne, Deven Johnson, and
Dale McNabb stated that they would not (Document ID 3581, Tr. 1657;
3585, Tr. 3053-3054). BAC and BCTD emphasized that employees must
choose to participate in medical surveillance in order for it to be
successful (Document ID 4219, p. 31; 4223, p. 131).
Industry groups, such as OSCO Industries and NAHB, commented that
they or employers from their member companies are reluctant to handle
or maintain confidential medical information (Document ID 1992, p. 12;
2296, p. 32). NAHB indicated:
Members have expressed strong concerns that much of [the medical
information], if not all, would be covered by privacy laws and
should be between a doctor and patient....Moreover, the PLHCP
should provide a copy of the written medical opinion to the employee
directly, not the employer, once it is written (Document ID 2296,
pp. 31-32).
However, other industry groups asserted that employers should
receive detailed information from medical surveillance. In particular,
NISA argued that reporting medical surveillance findings to employers
would facilitate epidemiological studies to better understand hazards
and the effectiveness of a new standard (Document ID 4208, p. 14).
OSHA agrees that epidemiology studies are important; indeed its
health effects and significant risk findings in this rule are
overwhelmingly based on epidemiological studies. However, as noted
above, it was never OSHA's intent for the PLHCP's written medical
opinion on respirable crystalline silica to contain specific diagnoses
or detailed findings that might be useful for an epidemiology study. As
noted in the summary and explanation of Recordkeeping, OSHA's access to
employee exposure and medical records standard (29 CFR 1910.1020)
requires employers to ensure that most employee medical records are
retained for the duration of employment plus 30 years for employees
employed more than one year. Such records obtained through appropriate
legal means, and with personal identifying information omitted or
masked, would be a possible avenue for conducting epidemiology studies.
CISC also noted that in past standards, the purpose of medical
surveillance was to improve health practices by allowing employers to
understand effects of hazards and, therefore, make changes to the
worksite, such as implementing controls or removing employees from
exposure (Document ID 4217, p. 24). Attorney Brad Hammock, representing
CISC at the public hearing, stated that if OSHA expects employers to
make placement decisions based on health outcomes and exposure, then
there would be some value in an employer receiving the PLHCP's opinion.
However, Mr. Hammock further explained that if the purpose of
surveillance is simply to educate employees about their health
situation, then there would be arguably little value in the employer
receiving the opinion (Document ID 3580, Tr. 1466-1467). Other
commenters, including ACOEM, AOEC, and NISA, also noted the importance
of medical surveillance for identifying adverse health effects among
employees in order to make workplace changes or evaluate the
effectiveness of regulations or workplace programs (Document ID 2080,
pp. 9-10; 3577, Tr. 784; 4208, pp. 13, 16-17). Andrew O'Brien testified
that if employers are not allowed to see medical findings, the first
time they are made aware of a problem is when they receive a letter
from the compensation system. Mr. O'Brien stated:
Without access to that data, you can't...potentially see
disease beginning and take preventative action to prevent it from
actually having a negative health effect (Document ID 3577, Tr.
614).
In contrast to those views, USW questioned the value in providing
employers with the PHLCP's medical opinion. It stated:
Exactly what corrections in the workplace will the employer make
based on newfound knowledge that one of his workers has a silica-
related condition? Silicosis occurs 15 or more years following onset
of exposure, so that today's silicosis is due to exposure that
likely occurred decades ago. (Exceptions are acute and accelerated
silicosis, which are rare and are not expected to occur at the
recommended PEL.) What inference is the employer supposed to make
about the magnitude or effect of current exposures under these
circumstances? Indeed, to make sense of the issue, the employer
would have to know about the worker's prior silica exposures, quite
often at different workplaces. But the employer and, quite likely,
even the worker are unlikely to have high quality data on exposures
to silica that occurred decades ago. In the absence of such
information, it is unclear how an employer can properly interpret
current exposures as causing silicosis. By contrast, the best
information on current exposures derives from current exposure
monitoring, and the notion that documenting silicosis can somehow
provide useful information about current exposures above and beyond
what proper exposure monitoring is ill-conceived (Document ID 4214,
p. 8). Similarly, Peg Seminario, Director of Safety and Health with
AFL-CIO, testified that employers should be basing their decisions on
exposure levels and how well controls are working (Document ID 3578,
Tr. 1008). NAHB and CISC questioned how an employer should respond if
an employee has signs of lung disease and the employer has already
implemented engineering controls and respirator use (Document ID 2296,
p. 31; 2319, p. 117).
OSHA agrees that because of the long latency period of most
respirable crystalline silica-related diseases, a diagnosis of such an
illness in an employee will not provide useful information about
current controls or exposure conditions. Employers should be basing
their actions on exposure assessments and ensuring properly functioning
controls, such as those listed and required for employers using Table
1. In the case where an employee may have disease related to respirable
crystalline silica and the employer has properly implemented
engineering controls, the only further action by the employer would be
to follow PLHCP recommendations to protect the worker who may be
especially sensitive to continuing exposure and need special
accommodations. Such recommendations could include limitations on
respirator use; they might also include specialist referral or
limitations on respirable crystalline silica exposure (if the employee
gives authorization for the employer to receive this information)
(paragraph (i)(6)(i)(C) or (ii)(A) and (B) of the standard for general
industry and maritime and paragraph (h)(6)(i)(C) or (ii)(A) and (B) of
the standard for construction).
In taking a more consent-based approach than in the proposed rule
regarding the PLHCP's written medical opinion for the employer, OSHA
considered the countervailing factor that employers will not be able to
report occupational illnesses to OSHA if they are not given medical
surveillance information. USW refuted the utility of employer reporting
of workplace illnesses, stating:
However, this loss is minor, because few believe that such
employer-generated reporting of chronic occupational conditions
does, or even could, under the best of circumstances, provide proper
counts of occupational illnesses (Document ID 4214, p. 8).
On a similar note, Fann Contracting and ASSE requested clarification on
what information would be reportable or recordable (Document ID 2116,
Attachment 1, p. 20; 2339, p. 9).
This rule does not change OSHA reporting or recording requirements,
and employers who need more information on recording or reporting of
occupational illnesses should refer to OSHA's standard on recording and
reporting occupational injuries and illnesses (29 CFR 1904). OSHA finds
that if employees do not participate in medical surveillance because of
discrimination or retaliation fears, illnesses associated with
respirable crystalline silica would generally not be identified.
Although not disclosing medical information to employers appears
inconsistent with the objective of recording illnesses, the net effect
of that decision is improving employee protections due to more
employees participating in medical surveillance. Also, as noted above,
OSHA never intended for employers to get specific information, such as
diagnoses, and this would further limit employers' ability to report
disease. Although state surveillance systems are likely to
underestimate silicosis cases (see Section V, Health Effects), they are
still likely to be a better way to get information on trends of
silicosis cases than employer reports. Reporting of silicosis cases by
health care providers is required by 25 states
(see http://www.cste2.org/izenda/ReportViewer.aspx?rn=Condition+All&p1value=2010&p2value=Silicosis).
PLHCPs are more likely to have the information needed to report
silicosis cases to state health authorities than employers. Thus, OSHA
concludes that exclusion of health-related information from the PLHCP's
written medical opinion for the employer will not have a significant
impact on silicosis surveillance efforts.
An additional consideration relating to what information, if any,
goes to the employer is that withholding information, such as
conditions that might place an employee at risk of health impairment
with further exposure, may leave employers with no medical basis to aid
in the placement of employees. Although NSSGA did not want to receive
confidential medical records, it stressed the importance of continuing
to receive information concerning how the workplace could affect an
employee's condition and on recommended respirator restrictions
(Document ID 3583, Tr. 2315-2316; 4026, p. 5). NISA stated that
employers should receive the results of medical surveillance because
employers might be held liable if employees choose to keep working in
settings that might aggravate their illnesses (Document ID 4208, p.
14). However, labor unions, such as USW, BAC, and BCTD, strongly
opposed employers making job placement decisions based on employees'
medical findings (Document ID 4214, pp. 7-8; 4219, pp. 31-32; 4223, p.
133). USW and BCTD noted that as long as employees are capable of
performing their work duties, decisions to continue working should be
theirs; BCTD further noted that the employee should make such decisions
with guidance from the PLHCP, and USW noted that the employee should
decide because of the significance of job loss or modifications
(Document ID 2371, Attachment 1, pp. 45-46; 4214, pp. 7-8). Sarah Coyne
agreed that employees should make decisions about placement. Ms. Coyne
stated, "I might have silicosis. I might have asbestosis. I know if I
can work or not. Let me decide" (Document ID 3581, Tr. 1656).
OSHA agrees that employees have the most at stake in terms of their
health and employability, and they should not have to choose between
continued employment and the health benefits offered by medical
surveillance, which they are entitled to under the OSH Act. OSHA agrees
that employees should make employment decisions, following discussions
with the PLHCP that include the risks of continued exposure. Before
that can happen, however, employees need to have confidence that
participation in medical surveillance will not threaten their
livelihoods. After considering the various viewpoints expressed during
the rulemaking on these issues, OSHA concludes that the best way to
maximize employee participation in medical surveillance, therefore
promoting the protective and preventative purposes of this rule, is by
limiting required disclosures of information to the employer to only
the bare minimum of what the employer needs to know to protect employee
health--recommended restrictions on respirator use and, only with
consent of the employee, the PLHCP's recommended limitations on
exposure to respirable crystalline silica and specialist referrals.
Thus, OSHA views this consent-based approach to reporting of medical
surveillance findings critical to the ultimate success of this
provision, which will be measured not just in the participation rate,
but in the benefits to participating employees--early detection of
silica-related disease so that employees can make employment,
lifestyle, and medical decisions to mitigate adverse health effects and
to possibly retard progression of the disease.
Expressing a different view, CISC stated that OSHA lacks the legal
authority to require employers to pay for ongoing medical surveillance
with no nexus to the workplace (Document ID 4217, p. 24). However, the
medical surveillance requirement in this rule, and every OSHA rule,
does have a nexus to the workplace. In the case of the respirable
crystalline silica rule, the nexus to the workplace is that exposure in
the workplace can result in or exacerbate disease and that medical
surveillance information will allow employees to make health and
lifestyle decisions that will benefit both them and the employer. In
addition, medical surveillance provides the employer with information
on fitness to wear a respirator, which is vitally important because of
risks to employees who wear a respirator when they should not do so
because of medical reasons.
NISA supported providing the proposed medical opinion to employers,
partly because some employers might have a better understanding of
medical surveillance results than employees, who might not have the
training or understanding to make health-protective decisions based on
those results (Document ID 4208, pp. 13-14). OSHA recognizes that
larger companies that employ health, safety, and medical personnel may
have in-house expertise to answer employee questions and stress the
importance of protective measures, such as work practices or proper use
of respirators. However, it is not likely that owners or management of
small companies would have a better understanding than their employees
or would be able to provide them any additional guidance. Consequently,
OSHA does not find the fact some employers might have a better
understanding of medical surveillance results than employees to be a
compelling argument against limiting the information that is to be
reported to the employer in the absence of employee consent. In
addition, OSHA expects that the training required under the rule will
give employees knowledge to understand protective measures recommended
by the PLHCP.
In sum, OSHA concludes that the record offers compelling evidence
for modifying the proposed content of the PLHCP's written medical
opinion for the employer. The evidence includes privacy concerns
expressed by both employees and employers, as well as evidence on the
limited utility for giving medical surveillance findings to employers.
OSHA is particularly concerned that the proposed requirements would
have led to many employees not participating in medical surveillance
and therefore not receiving its benefits. OSHA therefore has limited
the information to be given to the employer under this rule, but is
requiring that the employee receive a separate written medical report
with more detailed medical information.
The requirements for the type of information provided to the
employer are different from requirements of other OSHA standards, which
remain in effect for those other standards. The requirements for this
rule are based on the evidence obtained during this rulemaking for
respirable crystalline silica, in particular that many employees would
not take advantage of medical surveillance without privacy protections
and because the findings of medical examinations would not likely
reflect current workplace conditions in most cases. The action taken in
this rulemaking does not preclude OSHA from adopting its traditional
approach, or any other approach for reporting of medical findings to
employers, in the future when it concludes, based on health effects
information, that such an approach would contribute information that is
relevant to current workplace conditions and would allow for design or
implementation of controls to protect other employees.
PLHCP's written medical report for the employee. OSHA did not
propose a separate report given directly by the PLHCP to the employee,
but as discussed in detail above, several commenters requested that a
report containing medical information only be given to the employee.
OSHA agrees and in response to those comments, paragraph (i)(5) of the
standard for general industry and maritime (paragraph (h)(5) of the
standard for construction) requires the employer to ensure that the
PLHCP explains the results of the medical examination and provides the
employee with a written medical report within 30 days.
The contents of the PLHCP's written medical report for the employee
are set forth in paragraphs (i)(5)(i)-(iv) of the standard for general
industry and maritime (paragraphs (h)(5)(i)-(iv) of the standard for
construction). They include: The results of the medical examination,
including any medical condition(s) that would place the employee at
increased risk of material impairment of health from exposure to
respirable crystalline silica and any medical conditions that require
further evaluation or treatment; any recommended limitations on the
employee's use of respirators; any recommended limitations on
respirable crystalline silica exposure; and a statement that the
employee should be examined by a specialist if the chest X-ray provided
in accordance with this section is classified as 1/0 or higher by the B
reader, or if referral to a specialist is deemed appropriate by the
PLHCP. Appendix B contains an example of a PLHCP's written medical
report for the employee.
The health-related information in the PLHCP's written medical
report for the employee is generally consistent with the proposed
PLHCP's written medical opinion for the employer, with two notable
exceptions. Because only the employee will be receiving the PLHCP's
written medical report, the written medical report may include
diagnoses and specific information on health conditions, including
those not related to respirable crystalline silica, and medical
conditions that require further evaluation or follow-up are not limited
to those related to respirable crystalline silica exposure. Although
the focus of the examination is on silica-related conditions, the PLHCP
may happen to detect health conditions that are not related to
respirable crystalline silica exposure during the examination, and
could include information about such conditions in the written medical
report for the employee. The employer, however, is not responsible for
further evaluation of conditions not related to respirable crystalline
silica exposure. A minor difference from the proposed written medical
opinion for the employer and the written medical report for the
employee in the rule is that it specifies limitations on respirator use
rather than PPE because respirators are the only type of PPE required
by the rule. The requirements for the PLHCP's written medical report
for the employee are consistent with the overall goals of medical
surveillance: To identify respirable crystalline silica-related adverse
health effects so that the employee can consider appropriate steps to
manage his or her health; to let the employee know if he or she can be
exposed to respirable crystalline silica in his or her workplace
without increased risk of experiencing adverse health effects; and to
determine the employee's fitness to use respirators. By providing the
PLHCP's written medical report to employees, those who might be at
increased risk of health impairment from respirable crystalline silica
exposure will be able to consider interventions (i.e., health
management strategies) with guidance from the PLHCP. Dr. Laura Welch
testified that her recommendations to a patient diagnosed with
silicosis would include employment choices to limit exposures, using a
respirator for additional protection, quitting smoking, and getting
influenza and pneumonia vaccines (Document ID 3581, p. 1663).
The requirement for a verbal explanation in paragraph (i)(5) of the
standard for general industry and maritime (paragraph (h)(5) of the
standard for construction) allows the employee to confidentially ask
questions or discuss concerns with the PLHCP. The requirement for a
written medical report ensures that the employee receives a record of
all findings. As noted by BCTD, giving the employee the written report
will ensure the employee understands medical conditions that require
follow-up and could affect decisions of where and how to work; BCTD
also noted that employees would be able to provide the PLHCP's written
medical report to future health care providers (Document ID 2371,
Attachment 1, p. 48); this would include PLHCPs conducting subsequent
periodic examinations under the rule.
PLHCP's written medical opinion for the employer. As discussed in
detail above, many commenters objected to OSHA's proposed content for
the PLHCP's written medical opinion for the employer based on employee
privacy concerns. OSHA agrees with these privacy concerns and is thus
revising the contents of the written medical opinion. In developing the
contents of the PLHCP's written medical opinion for the employer, OSHA
considered what type of information needs to be included to provide
employers with information to protect employee health, while at the
same time protecting employee privacy. Commenters representing labor
unions and the medical community stated that the only information that
employers need to know is limitations on respirator use (Document ID
2178, Attachment 1, p. 5; 2240, pp. 3-4; 2282, Attachment 3, p. 21;
2336, p. 12; 3589, Tr. 4207; 4196, p. 6; 4203, p. 6; 4204, p. 89; 4219,
pp. 31-32; 4223, p. 133). Dr. Laura Welch stated that giving the
employer information on an employee's ability to use a respirator, but
not specific medical information, strikes the appropriate balance
between the employee's privacy and the employer's right to know; she
noted that employees who are not fit to wear a respirator and then do
can be at risk of sudden incapacitation or death (Document ID 3581, Tr.
1582, 1662).
BCTD further noted that the medical surveillance model it is
recommending for respirable crystalline silica presents a different
circumstance than what it advocated for regarding asbestos in
Industrial Union Department, AFL-CIO v. Hodgson. There, the union was
not granted its request for results of medical examinations to be given
to the employer only with the employees' consent under the asbestos
standard. The court ruled that employers needed the medical results
because the asbestos standard requires employers to reassign employees
without loss of pay or seniority if the employee was found unable to
safely wear a respirator. For respirable crystalline silica, BCTD has
concluded that providing employers with information regarding
limitations on respirator use and nothing else that is medically
related is reasonable if the employee is not requesting accommodations
or additional examinations from the employer (Document ID 4223, pp.
134-135).
Based on record evidence, OSHA has determined that for the
respirable crystalline silica rule, the PLHCP's written medical opinion
for the employer must contain only the date of the examination, a
statement that the examination has met the requirements of this
section, and any recommended limitations on the employee's use of
respirators. These requirements are laid out in paragraphs
(i)(6)(i)(A)-(C) of the standard for general industry and maritime
(paragraphs (h)(6)(i)(A)-(C) of the standard for construction). OSHA is
persuaded by arguments to include limitations on respirator use, and no
other medically-related information, in the PLHCP's written medical
opinion for the employer. The Agency notes that the limitation on
respirator use is consistent with information provided to the employer
under the respiratory protection standard (29 CFR 1910.134). OSHA
concludes that only providing information on respirator limitations in
the PLHCP's written medical opinion for the employer is consistent with
the ACOEM confidentiality guidelines that recommend reporting of health
and safety concerns to the employer (Document ID 3622, p. 2). The date
and statement about the examination meeting the requirements of this
section are to provide both the employer and employee with evidence
that requirements for medical surveillance are current. Employees would
be able to show this opinion to future employers to demonstrate that
they have received the medical examination, as was recommended by
LHSFNA and BCTD (Document ID 4207, p. 5; 4223, p. 125).
Paragraphs (i)(6)(ii)(A)-(B) of the standard for general industry
and maritime (paragraphs (h)(6)(ii)(A)-(B) of the standard for
construction) state that if the employee provides written
authorization, the written medical opinion for the employer must also
contain either or both of the following: (1) Any recommended
limitations on exposure to respirable crystalline silica; (2) a
statement that the employee should be examined by a specialist if the
chest X-ray provided in accordance with this section is classified as
1/0 or higher by the B reader, or if referral to a specialist is
otherwise deemed appropriate by the PLHCP. OSHA intends for this
provision to allow the employee to give authorization for the PLHCP's
written medical opinion for the employer to contain only the
recommendation on exposure limitations, only the recommendation for
specialist referral, or both recommendations. The Agency expects that
the written authorization could easily be accomplished through the use
of a form that allows the employee to check, initial, or otherwise
indicate which (if any) of these items the employee wishes to be
included in the PLHCP's written medical opinion for the employer. An
example of an authorization form is included in Appendix B.
OSHA is convinced that routinely including recommended limitations
on respirable crystalline silica exposure and specialist referrals in
the PLHCP's written medical opinion for the employer could adversely
affect employees' willingness to participate in medical surveillance.
The requirements for this paragraph are consistent with recommendations
from labor unions. For example, UAW, BAC, and BCTD suggested letting
the employee decide to forward the recommendation for an examination by
a specialist if the employee wanted the employer to cover the costs of
that examination (Document ID 3582, Tr. 1909; 4219, p. 32; 4223, pp.
133-134). BAC and BCTD also stated the employee should decide whether
recommended accommodations (i.e., recommended limitations on exposure)
should be reported to the employer. As both BAC and BCTD emphasized,
information given to the employer should only indicate that a referral
is recommended and the nature of the limitation on exposure, not an
underlying diagnosis. OSHA considers this reasonable. Appendix B
contains an example of a PLHCP's written medical opinion for the
employer.
OSHA finds that this new format for the PLHCP's medical opinion for
respirable crystalline silica will better address concerns of NAHB and
Dow Chemical, who feared they would be in violation if the PLHCP's
written medical opinion for the employer included information that OSHA
proposed the PLHCP not report to the employer, such as an unrelated
diagnosis (Document ID 2270, p. 4; 2296, pp. 31-32). OSHA finds that
removing the prohibition on unrelated diagnoses and instead specifying
the only information that is to be included in the PLHCP's written
medical opinion for the employer remedies this concern because it makes
the contents of the opinion easier to understand and less subject to
misinterpretation. The new format also addresses NAHB's request that
PLHCPs' opinions be standardized so that employers could understand the
results (Document ID 2296, pp. 31-32).
OSHA recognizes that some employees might be exposed to multiple
OSHA-regulated substances at levels that trigger medical surveillance
and requirements for written opinions. The PLHCP can opt to prepare one
written medical opinion for the employer for each employee that
addresses the requirements of all relevant standards, as noted in
preambles for past rulemakings, such as chromium (VI) (71 FR 10100,
10365 (2/28/06)). However, the combined written medical opinion for the
employer must include the information required under each relevant OSHA
standard. For example, if the PLHCP opts to combine written medical
opinions for an employee exposed to both chromium (VI) and respirable
crystalline silica in a workplace covered by construction standards,
then the combined opinion to the employer must contain the information
required by paragraphs (i)(5)(A)-(C) of the chromium (VI) standard for
construction (29 CFR 1926.1126) and the information required by
paragraphs (h)(6)(i)(A)-(C) (and paragraphs (h)(6)(ii)(A)-(B), with
written authorization from the employee) of the respirable crystalline
silica standard for construction.
Other commenter recommendations for information to be included in
the PLHCP's written medical opinion for the employer were not adopted
by OSHA. Collegium Ramazzini and BCTD requested that the PLHCP's
written medical opinion for the employer contain a statement that the
employee was informed that respirable crystalline silica increases the
risk of lung cancer, and Collegium Ramazzini also requested that the
opinion indicate that the employee was told that smoking can compound
the risk of developing lung cancer with exposure to respirable
crystalline silica (Document ID 3541, p. 14; 4223, p. 137). On a
similar note, Collegium Ramazzini also requested that employers
establish smoking cessation programs (Document ID 3541, p. 4). OSHA
notes that training provisions in paragraph (j)(3)(i)(A) of the
standard for general industry and maritime (paragraph (i)(2)(i)(A) of
the standard for construction) already require employers to ensure that
each employee can demonstrate knowledge of the health hazards
associated with exposure to respirable crystalline silica, which
include lung cancer. OSHA concludes that the training required under
the respirable crystalline silica rule is sufficient to inform
employees about lung cancer risk.
Labor unions including UAW, CWA, USW, AFL-CIO, and BCTD requested
that the rule prohibit employers from asking employees or the PLHCP for
medical information (Document ID 2282, Attachment 3, p. 21; 2240, pp.
3-4; 2336, p. 12; 4204, p. 90; 4223, p. 134); as most of these
commenters noted, a similar prohibition is included in the black lung
rule for coal miners (30 CFR 90.3). OSHA is not including such a
prohibition in the rule because employers may have legitimate reasons
for requesting medical information, such as X-ray findings, to conduct
epidemiology studies, and if employees are not concerned about
discrimination or retaliation, they could authorize the employer to
receive such information.
The proposed written medical opinion for the employer called for a
statement that the PLHCP had explained to the employee the results of
the medical examination, including findings of any medical conditions
related to respirable crystalline silica exposure that require further
evaluation or treatment, and any recommendations related to use of
protective clothing or equipment. As noted above, OSHA has retained the
requirement that the employer ensure that the PLHCP explains the
results to the employee in paragraph (i)(5) of the standard for general
industry and maritime (paragraph (h)(5) of the standard for
construction), but no longer requires the PLHCP to include a statement
of this fact in the written medical opinion for the employer. OSHA is
not mandating how the employer ensures that the employee gets the
required information because there are various ways this could be done,
such as in a contractual agreement between the employer and PLHCP.
PLHCPs could still include the verification in the PLHCP's written
medical opinion for the employer if that is a convenient method for
them to do so.
Paragraph (i)(6)(iii) of the standard for general industry and
maritime (paragraph (h)(6)(iii) of the standard for construction)
requires the employer to ensure that employees receive a copy of the
PLHCP's written medical opinion for the employer within 30 days of each
medical examination performed. OSHA is requiring that employees receive
a copy of the PLHCP's written medical opinion for the employer because
they can present it as proof of a current medical examination to future
employers. This is especially important in industries with high
turnover because employees may work for more than one employer during a
three-year period and this ensures that tests, such as X-rays, are not
performed more frequently than required.
As indicated above, the rule requires that employers ensure that
employees get a copy of the PLHCP's written medical report and opinion
and that they get a copy of the PLHCP's opinion within 30 days of each
medical examination (paragraphs (i)(5), (6)(i), and (6)(iii) of the
standard for general industry and maritime, paragraphs (h)(5), (6)(i),
and (6)(iii) of the standard for construction). By contrast, the
proposed rule would have required that the employer obtain the PLHCP's
written medical opinion within 30 days of the medical examination and
then provide a copy to the employee within 2 weeks after receiving it.
Dow Chemical expressed concern about compliance if a PLHCP took more
than 30 days to deliver the PLHCP's written medical opinion, which is a
situation that is out of the employer's control (Document ID 2270, p.
4). Ameren and EEI requested 30 days for the employer to give the
employee a copy of the PLHCP's written medical opinion (Document ID
2315, p. 4; 2357, p. 35).
The purpose of these requirements is to ensure that the employee
and employer are informed in a timely manner. To ensure timely delivery
and demonstrate a good faith effort in meeting the requirements of the
standard, the employer could inform PLHCPs about the time requirements
and follow-up with PLHCPs if there is concern about timely delivery of
these documents. Similar 30-day requirements are included in other OSHA
standards, such as chromium (VI) (1910.1026) and methylene chloride
(1910.1052). Because the PLHCP will be providing the employee with a
copy of the PLHCP's written medical report, he or she could give the
employee a copy of the written medical opinion at the same time. This
would eliminate the need for the employer to give the employee a copy
of the PLHCP's written medical opinion for the employer, but the
employer would still need to ensure timely delivery.
Additional examinations with a specialist. Paragraph (i)(7)(i) of
the standard for general industry and maritime (paragraph (h)(7)(i) of
the standard for construction) requires that the employer make
available a medical examination by a specialist within 30
days of receiving the written medical opinion in which the PLHCP
recommends that the employee be examined by a specialist. As is the
case with the PLHCP's examination, the employer is responsible for
providing the employee with a medical examination by a specialist, at
no cost, and at a reasonable time and place, if the employer receives a
PLHCP's referral recommendation.
OSHA proposed referral to a specialist under two circumstances: (1)
Where a B reader classifies an employee's chest X-ray as 1/0 or higher
and (2) where the PLHCP determines referral is otherwise appropriate.
The first trigger point for specialist referral relates to the
interpretation and classification of the chest X-ray employees receive
as part of their initial or periodic medical examination. The second
trigger point empowers the PLHCP to refer the employee to a specialist
for any other appropriate reason. After considering the comments on the
proposed rule (discussed below), OSHA retained the triggers for
referral in Paragraphs (i)(5)(iv) and (i)(6)(ii)(B) of the standard for
general industry and maritime (paragraphs (h)(5)(iv) and (h)(6)(ii)(B)
of the standard for construction).
As discussed above, paragraph (i)(2)(iii) of the standard for
general industry and maritime (paragraph (h)(2)(iii) of the standard
for construction) requires that X-rays be interpreted according to the
ILO classification system. The ILO's system is a standardized manner of
classifying opacities seen in chest radiographs. It describes the
presence and severity of pneumoconiosis on the basis of size, shape,
and profusion (concentration) of small opacities, which together
indicate the severity and extent of lung involvement (Document ID
1475). The profusion of opacities seen on chest radiographs is compared
to standard X-rays and classified on a 4-point category scale (0, 1, 2,
or 3), with each category representing increasing profusion of small
opacities. Each category is divided into two subcategories, giving a
12-subcategory scale between 0/- and 3/+. The first subcategory value
represents the B Reader's first choice for profusion rating and the
second subcategory value represents the B Reader's second choice for
profusion rating. CDC/NIOSH considers a category 1/0 X-ray to be
consistent with silicosis (Document ID 1711, p. 41).
The respirable crystalline silica rule's 1/0 category trigger point
for referral is lower than in the ASTM standards, which recommend that
employees with profusion opacities greater than 1/1 be evaluated at a
frequency determined by a physician qualified in pulmonary disease
(Section 4.7.1 of E 1132-06 and E 2625-09) and receive annual
counseling by a physician or other person knowledgeable in occupational
safety and health (Section 4.7.2 of E 1132-06 and E 2625-09) (Document
ID 1466, p. 5; 1504, p. 5). CISC questioned what medical evidence OSHA
had that a specialist is necessary at this stage and stated that OSHA
did not explain why it deviated from the ASTM standard (Document ID
2319, p. 120). However, ACOEM agreed with a cut-off point of 1/0 for
abnormality, and ATS agreed with specialist referral at a category of
1/0 (Document ID 2080, p. 7; 2175, p. 6).
Other evidence in the record also weighs in favor of referral where
an employee's X-ray is classified as 1/0 or higher. For example, a
study by Hnizdo et al. (1993) compared X-rays read by B Readers to
autopsy findings and demonstrated that a classification of 1/0 is
highly specific for radiological silicosis, with 89 percent of 1/0
readings of radiological silicosis found to be true positives (Document
ID 1050, pp. 427, 440). Based on the high level of specificity for 1/0
readings, i.e., the low probability of a false positive reading, OSHA
concludes it is appropriate to address silicosis at that stage to allow
for earlier intervention to possibly slow disease progression and
improve health. Therefore, based on the evidence in the record, OSHA
decided to retain the 1/0 or higher trigger point for referral to a
specialist.
OSHA also decided to retain the second referral trigger point
contained in the proposed rule: Referral to a specialist if otherwise
deemed appropriate by the PLHCP. Such referrals based on a PLHCP's
written medical opinion for the employer allow potential findings of
concern to be investigated further. Together, the two triggers for
specialist referral in this rule are intended to ensure that employees
with abnormal findings can be given the opportunity to be seen by an
American Board Certified Specialist with expertise in pulmonary disease
or occupational medicine, who can provide not only expert medical
judgment, but also counseling regarding work practices and personal
habits that could affect these individuals' respiratory health.
As indicated above, the employee must provide written authorization
before the PLHCP's written medical opinion for the employer may include
a recommendation for specialist examination (paragraph (i)(6)(ii)(B) of
the standard for general industry and maritime, paragraph (h)(6)(ii)(B)
of the standard for construction). If the employer's opinion contains a
recommendation for specialist referral, then paragraph (i)(7)(i) of the
standard for general industry and maritime (paragraph (h)(7)(i) of the
standard for construction) requires the employer to make available a
medical examination by a specialist within 30 days after receiving the
PLHCP's written medical opinion. If the employer does not receive the
PLHCP's referral because the employee did not authorize the employer to
receive it, then the employer is not responsible for offering
additional examinations and covering their costs.
Although the criteria for referral, i.e., X-ray classification or
PLHCP's opinion that a referral is appropriate, have not changed since
the proposed rule, the professional to whom the employee would be
referred has changed. Specifically, the proposed rule would have
required the employer to provide the referred employee with a medical
examination with a pulmonary disease specialist. As discussed further
in the summary and explanation of Definitions, OSHA agreed with a
number of commenters that an occupational medicine specialist is
qualified to examine employees referred for a possible respirable
crystalline silica-related disease (Document ID 2215, p. 9; 2291, p.
26; 2348, Attachment 1, p. 40; 3577, Tr. 778; 4223, p. 129). Therefore,
the Agency has added the term "specialist" to the definitions in
paragraph (b) of the rule and defined the term to mean an American
Board Certified Specialist in Pulmonary Disease or an American Board
Certified Specialist in Occupational Medicine. Paragraphs (i)(5)(iv)
and (i)(6)(ii)(B) of the standard for general industry and maritime
(paragraphs (h)(5)(iv) and (h)(6)(ii)(B) of the standard for
construction) were also revised to specify referral to a
"specialist."
Paragraph (i)(7)(i) of the standard for general industry and
maritime (paragraph (h)(7)(i) of the standard for construction) sets
time limits for additional examinations to be made available.
Specifically, it requires that the employer make available a medical
examination by a specialist within 30 days of receiving a written
medical opinion in which the PLHCP recommends that the employee be
examined by a specialist. This requirement is unchanged from the
proposed rule. Some commenters, including Dow Chemical, Ameren, and
EEI, commented that it might take more than 30 days to get an
appointment with a specialist (e.g., Document ID 2270, p. 5; 2315, p.
4; 2357, p. 36). OSHA does not expect this will be the case based on the
numbers of available specialists in the U.S. As of March 10, 2015, the
American Board of Internal Medicine (ABIM) reported that 13,715 physicians
in the U.S. had valid certificates in pulmonary disease
(see http://www.abim.org/pdf/data-candidates-certified/all-candidates.pdf).
ABIM does not report how many of these physicians are practicing. However,
ABIM does report that more than 400 new certificates in pulmonary disease
were issued per year from 2011 to 2014 and a total of 4,378 new certificates
in pulmonary disease were issued in the period from 2001 to 2010
(see http://www.abim.org/pdf/data-candidates-certified/Number-Certified-Annually.pdf).
Because physicians are likely to practice for some time after receiving
their certification, the numbers indicate that a substantial number of
pulmonary disease specialists are available in the U.S. The American
Board of Preventative Medicine reports that between 2001 and 2010,
863 physicians passed their examinations for board certification in
occupational medicine (see https://www.theabpm.org/pass_rates.cfm).
In a comparison with total numbers of physicians who were board certified
in pulmonary disease during 2001 to 2010, the addition of board certified
occupational medicine physicians will likely increase specialist numbers by
approximately 20 percent. The expansion of the specialist definition to
board certified occupational medicine physicians will mean that more physicians
will be available for referrals, making appointments easier to get.
Consequently, OSHA considers the 30-day period to be reasonable, and
expects that this deadline will ensure that employees receive timely
examinations.
Under paragraph (i)(7)(ii) of the standard for general industry and
maritime (paragraph (h)(7)(ii) of the standard for construction), the
employer must provide the specialist with the same information that is
provided to the PLHCP (i.e., a copy of the standard; a description of
the employee's former, current, and anticipated duties as they relate
to respirable crystalline silica exposure; the employee's former,
current, and anticipated exposure level; a description of any PPE used,
or to be used, by the employee, including when and for how long the
employee has used or will use that equipment; and information from
records of employment-related medical examinations previously provided
to the employee and currently within the control of the employer). The
information the employer is required to give the specialist is largely
unchanged from the proposed rule. The few changes and the reasons why
the specialist should receive this information are the same as those
for the PLHCP and are addressed above.
Under paragraph (i)(7)(iii) of the standard for general industry
and maritime (paragraph (h)(7)(iii) of the standard for construction),
the employer must ensure that the specialist explains medical findings
to the employee and gives the employee a written medical report
containing results of the examination, including conditions that might
increase the employee's risk from exposure to respirable crystalline
silica, conditions requiring further follow-up, recommended limitations
on respirator use, and recommended limitations on respirable
crystalline silica exposure. The reasons why the specialist is to give
the employee this information and the changes from the proposed rule
are discussed above, under the requirements for the PLHCP's written
medical report for the employee. For the same reasons as addressed
above, paragraph (i)(7)(iv) of the standard for general industry and
maritime (paragraph (h)(7)(iv) of the standard for construction)
requires the specialist to provide the employer with a written medical
opinion indicating the date of the examination, any recommended
limitations on the employee's use of respirators, and with the written
authorization of the employee, any recommended limitations on the
employee's exposure to respirable crystalline silica.
The rule does not address further communication between the
specialist and the referring PHLCP. OSHA expects that because the PLHCP
has the primary relationship with the employer and employee, the
specialist may want to communicate his or her findings to the PLHCP and
have the PLHCP simply update the original written medical report for
the employee and written medical opinion for the employer and employee.
This is permitted under the rule, so long as all requirements and time
deadlines are met.
Medical removal protection. Some OSHA standards contain provisions
for medical removal protection (MRP) that typically require the
employer to temporarily remove an employee from exposure when such an
action is recommended in a written medical opinion. During the time of
removal, the employer is required to maintain the employee's total
normal earnings, as well as all other employee rights and benefits. MRP
provisions vary among health standards, depending on the hazard, the
adverse health effects, medical surveillance requirements, and the
evidence presented during the particular rulemaking. Although virtually
every previous OSHA substance-specific health standard includes
provisions for medical surveillance, OSHA has found MRP necessary for
only six of those standards. They are lead (1910.1025), cadmium
(1910.1027), benzene (1910.1028), formaldehyde (1910.1048),
methylenedianiline (1910.1050), and methylene chloride (1910.1052).
OSHA did not include a provision for MRP in the proposed rule
because the Agency preliminarily concluded that there would be few
instances where temporary removal and MRP would be useful. However,
OSHA asked for comment on whether the rule should include an MRP
provision, which medical conditions or findings should trigger
temporary removal, and what should be the maximum period for receiving
benefits (78 FR at 56291).
Labor groups, industry representatives, the medical community, and
other employee health advocates offered comments on this issue. NIOSH,
ASSE, and some employers and industry groups agreed with OSHA's
preliminary findings that MRP or temporary removal from exposure is not
appropriate for the respirable crystalline silica rule (e.g., Document
ID 2116, Attachment 1, pp. 44-45; 2177, Attachment B, p. 39; 2195, p.
44; 2319, p. 129; 2327, Attachment 1, p. 27; 2339, p. 10; 2357, p. 35;
2379, Appendix 1, p. 72). Among the reasons noted were an inability to
relocate employees to different positions, interference with workers'
compensation systems, or the permanent nature of silica-related health
effects.
CWA, UAW, USW, and AFL-CIO advocated for the inclusion of MRP (in
the general industry and maritime standard) with provisions for
multiple physician review, similar to MRP in cadmium (Document ID 2240,
p. 4; 2282, Attachment 3, pp. 23-24; 3584, Tr. 2541-2546; 4204, pp. 91-
98). None of the labor groups requested an MRP provision for the
construction standard. According to Collegium Ramazzini and AFL-CIO,
benefits of MRP include: Encouraging employees to participate in
medical surveillance and allowing for transfer when an employee is
unable to wear a respirator (e.g., cadmium, asbestos, cotton dust);
they further indicated that MRP is appropriate for the respirable
crystalline silica rule because it can be applied when employees are
referred to a specialist (e.g., benzene) and it is not limited to
permanent conditions in other OSHA standards. AFL-CIO further commented
that MRP gives employers time to find other positions involving lower
exposures for at-risk workers, and indicated that it is widely
supported by physicians (Document ID 3541, pp. 16-17; 4204, pp. 94-97).
Physicians representing employee health advocate or public health
groups testified or commented that removal from exposure can prevent or
slow progression of silicosis or benefit employees during short-term
periods of COPD exacerbation, which can be further exacerbated with
continued exposure to respirable crystalline silica (Document ID 2244,
p. 4; 3577, Tr. 830-832; 3541, p. 16).
OSHA did not propose MRP for respirable crystalline silica because
the adverse health effects associated with respirable crystalline
silica exposure (e.g., silicosis) are chronic conditions that are not
remedied by temporary removal from exposure. In contrast, removal under
the cadmium standard (29 CFR 1910.1027) could allow for biological
monitoring results to return to acceptable levels or for improvement in
the employee's health. The evidence submitted during the rulemaking has
led OSHA to conclude that its preliminary reasoning was correct and
that for the reasons discussed below, there will be few instances where
temporary removal from respirable crystalline silica exposures would
improve employee health.
OSHA has declined to adopt MRP provisions in other health standards
under similar circumstances. For example, in its chromium (VI)
standard, OSHA did not include an MRP provision because chromium (VI)-
related health effects are either chronic conditions that will not be
improved by temporary removal from exposure (e.g., lung cancer,
respiratory or dermal sensitization), or they are conditions that can
be addressed through proper application of control measures (e.g.,
irritant dermatitis) (71 FR at 10366). OSHA did not include MRP
provisions in the ethylene oxide (EtO) standard, concluding that,
...the effects of exposure to EtO are not highly reversible, as
evidenced by the persistence of chromosomal aberrations after the
cessation of exposure, and the record contains insufficient evidence
to indicate that temporary removal would provide long-term employee
health benefits (49 FR 29734, 25788 (6/22/1984)).
Similarly, the 1,3-butadiene standard, which primarily addresses
irreversible effects, such as cancer, does not include MRP provisions
(61 FR 56746 (11/4/96)).
OSHA recognizes that some employees might benefit from removal from
respirable crystalline silica exposure to possibly prevent further
progression of disease. However, the health effects evidence suggests
that crystalline silica-related diseases are permanent (Document ID
2177, Attachment B, p. 39). Thus, to be beneficial, any such removals
would have to be permanent, not temporary. Even in cases where
employees might benefit from temporary removal, such as to alleviate
exacerbation of COPD symptoms, COPD itself is not reversible. In
response to commenters indicating that temporary removal might
alleviate COPD symptoms, OSHA anticipates that periods of exacerbation
will continue to recur absent permanent removal from respirable
crystalline silica exposure. OSHA views MRP as a tool for dealing with
temporary removals only, as reflected in the Agency's decisions not to
adopt MRP in the chromium (VI), ethylene oxide, and 1,3-butadiene
standards. Workers' compensation is the appropriate remedy when
permanent removal from exposure is required.
When the D.C. Circuit Court reviewed OSHA's initial decision not to
include MRP in its formaldehyde standard, it remanded the case for OSHA
to consider the appropriateness of MRP for permanently removed
employees (see UAW v. Pendergrass, 878 F.2d 389, 400 (D.C. Cir. 1989)).
OSHA ultimately decided to adopt an MRP provision for formaldehyde.
However, as discussed below, the Agency did not rely on a need to
protect employees permanently unable to return to their jobs. Indeed,
OSHA expressly rejected that rationale for MRP, noting that "[t]he MRP
provisions [were] not designed to cover employees...determined to
be permanently sensitized to formaldehyde" (57 FR 22290, 22295 (5/27/
92)). An important objective of MRP is to prevent permanent health
effects from developing by facilitating employee removal from exposure
at a point when the effects are reversible, and that objective cannot
be met where the effects are already permanent.
Given that MRP benefits apply only to a temporary period, it is
logical that eligibility be limited to employees with a temporary need
for removal, as has been done in a number of standards, such as cadmium
(1910.1027(l)(12)), benzene (1910.1028(i)(9)) and methylene chloride
(1910.1052(j)(12)). Temporary wage and benefit protections may address
the concerns of employees who fear temporary removal, but employees who
fear permanent removal are unlikely to be persuaded by a few months of
protection. The evidence in the record does not demonstrate that
affected employees are unlikely to participate in medical surveillance
absent wage and benefit protection. In contrast, extensive evidence in
the record demonstrates that lack of confidentiality regarding medical
findings would more likely lead to employees refusing medical
examinations (e.g., Document ID 3577, Tr. 819-820; 3579, Tr. 169; 3581,
Tr. 1657; 3585, Tr. 3053-3054); OSHA has remedied that situation by
strengthening confidentially requirements for medical examinations.
A major reason for inclusion of MRP in the formaldehyde standard is
that medical surveillance depends on employee actions. The formaldehyde
standard does not have a medical examination trigger, such as an action
level, but instead relies on annual medical questionnaires and employee
reports of signs and symptoms. Thus, the approach is completely
dependent on employee cooperation (57 FR at 22293). Unlike the
formaldehyde standard, respirable crystalline silica medical
surveillance programs for the general industry/maritime and
construction standards are not entirely dependent on employee reports
of signs and symptoms. The respirable crystalline silica standard for
general industry and maritime requires that regular medical
examinations be offered to employees exposed at or above the action
level for 30 or more days per year, and the construction standard
requires that medical examinations be offered to employees required to
wear a respirator for 30 or more days a year. Both standards mandate
that those examinations include a physical examination, chest X-ray,
and spirometry testing. Independent of any subjective symptoms that may
or may not be reported by the employee, PLHCPs conducting these
examinations can make necessary medical findings based on objective
findings from the physical examination, X-ray, and spirometry tests.
Lead is another example of a standard in which medical surveillance
findings may be influenced by employee actions. In the lead standard,
OSHA adopted an MRP provision in part due to evidence that employees
were using chelating agents to achieve a rapid, short-term reduction in
blood lead levels because they were desperate to avoid economic loss,
despite the possible hazard to their health from the use of chelating
agents. In the case of the lead standard, successful periodic
monitoring of blood lead levels depends on employees not attempting to
alter their blood lead levels (43 FR 54354, 54446 (11/21/78)).
Unlike the lead standard, in which blood lead levels are reported to
employers, the respirable crystalline silica rule has privacy
protections that do not allow information other than limitations on
respirator use to be communicated to the employer, in the absence of
employee authorization. With the privacy protections, it is unlikely
that employees will try and take actions to sabotage medical findings.
Other reasons OSHA has cited for needing to include MRP in its
health standards are similarly inapplicable to respirable crystalline
silica. In lead, for example, OSHA explained that the new blood lead
level removal criteria for the lead standard were much more stringent
than criteria being used by industry at that time. Therefore, many more
temporary removals would be expected under the new standard, thereby
increasing the utility of MRP (43 FR at 54445-54446). There are no
criteria in this new rule that are likely to increase the number of
medical removals that may be occurring.
OSHA adopted MRP in the lead standard because it "...
anticipate[d] that MRP w[ould] hasten the pace by which employers
compl[ied] with the new lead standard" (43 FR at 54450). OSHA reasoned
that the greater the degree of noncompliance, the more employees would
suffer health effects necessitating temporary medical removal and the
more MRP costs the employer would be forced to incur. OSHA thought that
MRP would serve as an economic stimulus for employers to protect
employees by complying with the standard. With respect to respirable
crystalline silica, its disease outcomes (e.g., silicosis, COPD, lung
cancer) generally take years to develop. Because of the latency period
of most respirable crystalline silica-related diseases, the costs of
MRP would not serve as a financial incentive for employers to comply
with the requirements of the respirable crystalline silica rule. For
example, most current high exposures would not result in adverse health
effects until years later and most health effects requiring medical
removal likely resulted from exposures that occurred years earlier, and
in some cases, before the eligible employee worked for the current
employer.
In addition, although OSHA required medical removal in the benzene
standard after referral to a specialist (1910.1028(i)(8)(i)), the
circumstances there are also distinguishable from respirable
crystalline silica. MRP was required in the benzene standard because
some benzene-related blood abnormalities could rapidly progress to
serious and potentially life threatening disease, and continued benzene
exposure could affect progression (52 FR at 34555). With the exception
of acute silicosis, which is rare, silica-related diseases progress
slowly over a span of years. Thus, in most cases, there is no urgent
need for removal from respirable crystalline silica exposure while
awaiting a specialist determination.
OSHA also notes that there are three health standards that provide
limited MRP under their requirements for respiratory protection. They
are asbestos, (1910.1001(g)(2)(iii)), cotton dust
(1910.1043(f)(2)(ii)), and cadmium (29 CFR 1910.1027(l)(ii)). These
standards require MRP when a medical determination is made that an
employee who is required to wear a respirator is not medically able to
wear the respirator and must be transferred to a position with
exposures below the PEL, where respiratory protection is not required.
OSHA has determined that such a provision is unnecessary for the
respirable crystalline silica rule because OSHA has since revised its
respiratory protection standard to specifically deal with the problem
of employees who are medically unable to wear negative pressure
respirators by requiring the employer to provide a powered air-
purifying respirator (29 CFR 1910.134(e)(6)). Such an approach has been
used by employers who are unable to move employees to jobs with lower
exposure (Document ID 3577, p. 610). In this rule, OSHA requires
employers to comply with 29 CFR 1910.134, including medical evaluations
mandated under that standard.
In summary, OSHA finds MRP to be neither reasonably necessary nor
appropriate for the respirable crystalline silica rule. In other health
standards, OSHA has stated that the purpose of MRP is to encourage
employees to participate in medical surveillance by assuring them that
they will not suffer wage or benefit loss if they are temporarily
removed from further exposure as a result of findings made in the
course of medical surveillance. OSHA's primary reason for not including
MRP in the respirable crystalline silica rule is that the Agency does
not expect a significant number of employees to benefit from temporary
removal from their jobs as a result of medical surveillance findings.
In addition, the medical surveillance program in the respirable
crystalline silica rule is less dependent on employee action that could
influence medical surveillance findings than the programs in some other
health standards that include MRP, such as lead and formaldehyde. Other
considerations that have led OSHA to use MRP in the past are also not
applicable in the context of respirable crystalline silica. OSHA
expects that respirable crystalline silica-related health effects would
result in very few temporary medical removals, and the evidence
demonstrates that any removals that would occur would likely need to be
permanent. OSHA concludes that the evidence in the record, relevant
court decisions, and the criteria OSHA has previously applied to
determine necessity for MRP do not support a finding that MRP is
reasonably necessary or appropriate for the respirable crystalline
silica rule.
Requests for anti-discrimination/retaliation clause. Labor groups
and other employee health advocates requested that OSHA add a clause to
prohibit employers from retaliating or discriminating against employees
for participating in medical surveillance or because of the findings of
medical surveillance (e.g., Document ID 2176, p. 2; 2282, Attachment 3,
p. 21; 2336, p. 12; 3577, Tr. 879; 3589, Tr. 4207; 4204, p. 90; 4219,
pp. 33-36; 4223, p. 139). USW, BAC, and BCTD also requested that the
anti-retaliation or anti-discrimination provisions address OSHA
activities beyond medical surveillance (e.g., reporting unsafe working
conditions), and in addition, BAC requested formal procedures for
filing a complaint (Document ID 3584, Tr. 2548; 4219, pp. 33-38; 4223,
p. 139). Employees, unions, and employee health advocates reported
instances where employees were afraid to ask for protections or file
complaints; some reported employer threats or retribution in response
to such actions (e.g., Document ID 2124; 2173, p. 3; 3571, Attachment
3, p. 2, Attachment 4, p. 3; 3577, Tr. 816-817; 3581, Tr. 1787, 1796;
3583, Tr. 2464; 3584, Tr. 2567-2568; 3585, Tr. 3101; 3586, Tr. 3168).
To address the possibility that some employees may decline to
participate in medical surveillance because of fear of retaliation or
discrimination, NISA suggested that OSHA require employee participation
in medical surveillance, as well as include a prohibition on
discrimination in the rule or clarify that Section 11(c) of the OSH Act
applies to discrimination based on medical surveillance findings. NISA
requested that OSHA at least confirm that employers are free to require
medical surveillance as a condition of employment (Document ID 4208,
pp. 15-18).
As indicated in the NISA comments, Section 11(c) of the OSH Act
prohibits discharge or discrimination against any employee for
exercising any right afforded by the Act (29 U.S.C. (660(c)(1)).
OSHA observes that these rights include filing an OSHA complaint,
participating in an inspection or talking to an inspector, seeking
access to employer exposure and injury records, reporting an injury,
and raising a safety or health complaint with the employer. Medical
surveillance and the other requirements provided under the respirable
crystalline silica rule are also rights afforded under the Act.
Therefore, an employer may not discharge or otherwise discriminate
against any employee because the employee participates in medical
surveillance offered under the rule. This includes discharge or
discrimination based on medical findings for an employee who is able to
perform the essential functions of the job.
Although acknowledging that the 11(c) protections are important
because they establish that employees cannot be discriminated against
for exercising their rights under the Act, Peg Seminario, on behalf of
the AFL-CIO, stated that the enforcement mechanisms are very weak. Ms.
Seminario pointed to the lack of an administrative process through the
Review Commission, such as exists for compliance violations under
standards, and she also stated that very few 11(c) cases are moved
forward. In addition, Ms. Seminario testified that 11(c) deals with
individual cases but does not address broad practices (Document ID
3578, Tr. 981-982). BCTD pointed to testimony given by Professor Emily
Spieler before a Senate Subcommittee on Employment and Workplace Safety
that described weaknesses of 11(c) and gave recommendations for
improving it (Document ID 4072, Attachment 27; 4223, p. 138). BCTD
concluded that an anti-discrimination/retaliation provision might
provide employees with "an alternative, and potentially quicker,
mechanism for gaining the Act's protections" (Document ID 4223, p.
139).
OSHA recognizes that Section 11(c) of the Act has been an imperfect
avenue for preventing retaliation and addressing employee complaints of
discharge or discrimination for exercising rights afforded by the Act.
For this reason, separate from this rulemaking, OSHA has made
considerable efforts in recent years to enhance the effectiveness of
its Section 11(c) program to protect employees from retaliation for
exercising their rights under the OSH Act and other anti-retaliation
statutes enforced by OSHA. These efforts include administrative
restructuring to create a separate Directorate of Whistleblower
Protection Programs as one of eight Directorates in OSHA; adding
additional investigators; and providing additional training for
investigators and Labor Department solicitors who work on whistleblower
cases. The Agency's Whistleblower Investigations Manual updated
procedures and provided further guidance to help ensure consistency and
quality of investigations (see https://www.osha.gov/OshDoc/Directive_pdf/CPL_02-03-005.pdf),
and OSHA's memo to whistleblower enforcement staff on Employer Safety
Incentive and Disincentive Policies and Practices, clarified that employer
policies that discourage reporting of injuries and illnesses constitute
violations of section 11(c) (see https://www.osha.gov/laws-regs/standardinterpretations/2012-03-12-0).
In addition, the Department of Labor has established a Whistleblower
Protection Advisory Committee to advise, consult with, and make
recommendations to the Secretary of Labor and the Assistant Secretary
of Labor for Occupational Safety and Health on ways to improve the
fairness, efficiency, effectiveness, and transparency of OSHA's
administration of whistleblower protections (77 FR 29368 (5/17/12)).
OSHA concludes that the Agency's limited resources will be best
utilized by continuing to focus on strengthening enforcement of Section
11(c), rather than creating, on an ad hoc basis, a separate and
alternative enforcement mechanism in the respirable crystalline silica
rule. OSHA emphasizes that, in response to commenters' concerns about
privacy and the possibility for retaliation based on employers'
knowledge of employee medical information, it has made changes to the
medical surveillance disclosure requirements of the rule, discussed
above, in order to both encourage participation in medical surveillance
and discourage discriminatory or retaliatory actions. Retaliation based
on other activities, such as reporting injuries and illnesses or noting
the failure of engineering controls, is not unique to the silica rule
and thus does not, in OSHA's judgment, warrant a silica-specific
response.
In response to the suggestion that OSHA prohibit employees from
opting out of medical surveillance, OSHA observes that Section
(6)(c)(7) of the OSH Act specifies that medical examinations or other
tests "be made available," not that they be required. OSHA considers
the medical surveillance offered under the rule to offer important
protections for employees, and the Agency encourages all eligible
employees to take advantage of these protections. However, the Agency
recognizes that employees may choose not to take advantage of medical
surveillance for a variety of reasons. OSHA does not find it
appropriate to require all eligible employees to receive medical
surveillance simply to preclude the possibility that an employer might
discriminate against those who receive medical surveillance. The Agency
also notes that Section 20(a)(5) of the OSH Act generally precludes
OSHA from requiring medical surveillance for those who object on
religious grounds. At the same time, nothing in the rule precludes an
employer from requiring participation in medical surveillance programs
as appropriate under applicable laws and/or labor-management contracts.
ASTM standards. Most medical surveillance requirements in the
respirable crystalline silica rule are generally consistent with ASTM
standards for addressing control of occupational exposure to respirable
crystalline silica (Section 4.6 and 4.7 in both E 1132-06 and E 2625-
09) (Document ID 1466, p. 5; 1504, p. 5). Commenters noted differences
between the ASTM standards and the respirable crystalline silica rule
(i.e., 120- versus 30-day exposure duration trigger, optional versus
mandatory spirometry testing, and referrals based on a 1/1 versus 1/0
category X-ray). As explained above, the requirements of the rule
better protect employees and therefore better effectuate the purposes
of the OSH Act than the ASTM standards. There are additional
differences between the ASTM standards and the rule, which are
discussed briefly below.
The ASTM standards require that medical surveillance be triggered
by the PEL or other occupational exposure limit, but for the general
industry and maritime standard, OSHA is triggering medical surveillance
at the action level because of remaining significant risk, exposure
variability, and increased sensitivity of some employees. The ASTM
standards recommend medical examinations before placement but OSHA
allows the examinations to be conducted within 30 days to offer more
flexibility.
The ASTM standards recommend tuberculosis testing for employees
with radiographic evidence of silicosis, but the rule requires
tuberculosis testing in the initial examination for all employees who
qualify for medical surveillance. OSHA's requirement is based on
evidence that exposure to respirable crystalline silica increases the
risk for a latent tuberculosis infection becoming active, even in the
absence of silicosis. The ASTM standards do not specifically mention a
specialist, but the requirement for specialist referral in the respirable
crystalline silica rule is conceptually consistent with the provision
in the ASTM standards for counseling (by a physician or other person
qualified in occupational safety and health) regarding work practices
and personal habits that could affect employees' respiratory health.
Lastly, the E 1132-06 standard allows the health provider to report
information to the employer, such as if the employee has a condition
that might put him or her at risk for health impairment or if
limitations on respirator use are related to medical or emotional
reasons. Under the rule for respirable crystalline silica, medical
findings are withheld from the employer and only reported to the
employee because of privacy concerns and discrimination/retaliation
fears that might prevent participation in medical surveillance. Both
ASTM standards require the employer to follow the physician's placement
or job assignment recommendations; the OSHA rule differs from the ASTM
standards in this respect by allowing employees to make their own
placement decisions if they are able to do the work.
Communication of Respirable Crystalline Silica Hazards to Employees
Paragraph (j) of the standard for general industry and maritime
(paragraph (i) of the standard for construction) sets forth
requirements intended to ensure that the dangers of respirable
crystalline silica exposure are communicated to employees. Employees
need to know about the hazards to which they are exposed, along with
associated protective measures, in order to understand how they can
minimize potential health hazards. As part of an overall hazard
communication program, training serves to explain and reinforce the
information presented on labels and in safety data sheets (SDSs). These
written forms of communication will be effective and relevant only when
employees understand the information presented and are aware of the
actions to be taken to avoid or minimize exposures, thereby reducing
the possibility of experiencing adverse health effects. Numerous
commenters, including industry stakeholders and dozens of construction
employees and concerned individuals, generally supported inclusion of a
hazard communication requirement in the rule (e.g., Document ID 2039;
2113; 2116, Attachment 1, p. 45; 2302, p. 1; 2315, p. 4; 2345, p. 3;
3302, p. 1; 3295; 4217, p. 25).
Paragraph (j)(1) of the standard for general industry and maritime
(paragraph (i)(1) of the standard for construction) requires the
employer to (1) include respirable crystalline silica in the program
established to comply with the hazard communication standard (HCS) (29
CFR 1910.1200); (2) ensure that each employee has access to labels on
containers of crystalline silica and SDSs, and is trained in accordance
with the provisions of the HCS and the provisions on employee
information and training (contained in paragraph (j)(3) of the standard
for general industry and maritime, paragraph (i)(2) of the standard for
construction), and (3) ensure that at least the following hazards are
addressed: Cancer, lung effects, immune system effects, and kidney
effects. These requirements remain unchanged from the proposed rule,
after OSHA considered comments addressing these requirements (discussed
below).
The approach in paragraph (j)(1) of the standard for general
industry and maritime (paragraph (i)(1) of the standard for
construction) is consistent with other OSHA substance-specific health
standards, which were revised as part of the 2012 update of the HCS to
conform to the United Nations' Globally Harmonized System of
Classification and Labelling of Chemicals (GHS). The 2012 update of the
substance-specific standards involved revising the hazard communication
requirements to refer to the HCS requirements for labels, SDSs, and
training, and to identify the hazards that need to be addressed in the
employer's hazard communication program for each substance-specific
standard. In applying the approach described in paragraph (j)(1) of the
standard for general industry and maritime (paragraph (i)(1) of the
standard for construction), OSHA intends for the hazard communication
requirements in the respirable crystalline silica rule to be
substantively as consistent as possible with the HCS, while including
additional specific requirements needed to protect employees exposed to
respirable crystalline silica. A goal of this approach is to avoid a
duplicative administrative burden on employers who must comply with
both the HCS and this rule.
Some stakeholders agreed with OSHA that additional hazard
communication provisions are needed in this rule. For example, the
National Industrial Sand Association (NISA) generally agreed with
OSHA's approach for communication of hazards to employees and indicated
that the generic training elements of the HCS alone are insufficient
(Document ID 2195, p. 45). In addition, labor unions such as the United
Automobile, Aerospace and Agricultural Implement Workers of America
(UAW), International Union of Operating Engineers (IUOE), American
Federation of Labor and Congress of Industrial Organizations (AFL-CIO),
International Union of Bricklayers and Allied Craftworkers (BAC), and
Building and Construction Trades Department, AFL-CIO (BCTD) generally
agreed that employees exposed to respirable crystalline silica need
additional information and training (Document ID 2282, Attachment 3, p.
24; 3583, Tr. 2367; 4204, p. 98; 4219, p. 22; 4223, p. 114).
However, other stakeholders expressed the view that OSHA's existing
HCS requirements are sufficient, and that hazard communication
provisions in this rule are not warranted. For example, the National
Stone, Sand, and Gravel Association (NSSGA) asserted that requiring
information and training under the respirable crystalline silica rule
would be duplicative and unnecessary because OSHA's existing HCS
adequately addresses communication of hazards and training of employees
(Document ID 2327, Attachment 1, p. 11). The Portland Cement
Association and National Association of Home Builders (NAHB) expressed
similar views (Document ID 2284, p. 6; 2296, p. 44).
OSHA understands that the HCS already addresses communication of
hazards but, after reviewing rulemaking record comments, reaffirms that
employees exposed to respirable crystalline silica need additional
training and information. Therefore, OSHA has decided to include in the
rule the approach set forth in the proposed rule. The rule thus
requires compliance with the HCS and the additional requirements that
address aspects of employee protection that are not specified in the
HCS but are relevant to these standards; examples of these provisions
include health hazards specific to respirable crystalline silica, signs
at entrances to regulated areas, training on medical surveillance, and
training on engineering controls. Specific comments on these
requirements and OSHA's rationale for their inclusion in the rule are
discussed below. OSHA expects this approach will reduce the
administrative burden on employers who must comply with both the HCS
and this rule, while providing employees with adequate information and
effective training on respirable crystalline silica hazards.
Which hazards should be addressed in employers' HCS programs was a
matter of debate among commenters. For example, the American Coatings
Association (ACA) asserted that OSHA's listing of health effects
associated with crystalline silica was contrary to the revised HCS,
which ACA argued allows qualified health professionals to established
hazard classifications based on actual data (Document ID 2239, p. 2).
Associated Builders and Contractors, Inc. and the Construction Industry
Safety Coalition (CISC) did not support the inclusion of cancer, immune
system effects, and kidney effects on the list of hazards to be
addressed, asserting that OSHA did not meet its burden of showing a
link between these diseases and exposure to crystalline silica
(Document ID 2289, p. 8; 2319, p. 120).
OSHA does not find these arguments persuasive. As discussed in
Section V, Health Effects, OSHA evaluated the best available published,
peer-reviewed literature on respirable crystalline silica and
considered comments from stakeholders to determine that exposure to
respirable crystalline silica is associated with silicosis and other
non-malignant respiratory disease, lung cancer, immune system effects,
and kidney effects. Inclusion of a minimum list of health effects to
address as part of hazard communication, based primarily on information
from OSHA's rulemakings, is consistent with the 2012 revision of all
substance-specific standards (77 FR 17574, 17749-17751, 17778-17785 (3/
26/2012)). Therefore, the Agency concludes that including a list of
hazards to be addressed, and the specific hazards listed, are
appropriate.
Commenters such as the United Steelworkers (USW) and the American
Federation of State, County, and Municipal Employees (AFSCME) requested
that the rule require training on tuberculosis (Document ID 2336, pp.
14-15; 4203, p. 7). OSHA did not specifically list tuberculosis as a
health hazard to be addressed because initial tuberculosis infection is
not related to respirable crystalline silica exposure. In addition, the
HCS describes health hazards in terms of target organs affected, such
as lungs, or specific endpoints, such as carcinogenicity. Tuberculosis
is not an endpoint listed in the HCS; thus, listing it in this rule
would be inconsistent with the HCS. Consequently, OSHA has decided not
to add tuberculosis to the list of hazards that must be addressed.
However, because respirable crystalline silica exposure increases the
risk of a latent tuberculosis infection becoming active, OSHA
encourages employers to address tuberculosis as part of their hazard
communication program.
Paragraph (j)(2) of the standard for general industry and maritime
requires employers to post signs at all entrances to regulated areas.
Although OSHA proposed a requirement for demarcating regulated areas,
the Agency did not propose a requirement for warning signs at entrances
to regulated areas, and instead noted that the areas could be
effectively demarcated by signs, barricades, lines, or textured
flooring (78 FR at 56273, 56450 (9/12/13)). The AFL-CIO argued that
warning signs are an important method of making employees aware of
potential hazards and noted that warning signs are required at
entrances to regulated areas by many OSHA standards (Document ID 4204,
pp. 100-101). A number of commenters, including the Communication
Workers of America (CWA), Upstate Medical University, the American
Public Health Association (APHA), UAW, and HalenHardy, agreed that
warning signs must be required at regulated areas (e.g., Document ID
2240, p. 4; 2244, p. 4; 2178, Attachment 1, p. 2; 2282, Attachment 3,
p. 25; 4030, Exhibit A, pp. 5-6). Similarly, USW commented on the need
for warning signs in areas with potential respirable crystalline silica
exposure (Document ID 2336, p. 14). Charles Gordon, a retired
occupational safety and health attorney, argued that the absence of a
requirement for warning signs was inconsistent with Section 6(b)(7) of
the Occupational Safety and Health (OSH) Act, which requires labels or
other warnings to inform employees of hazards (Document ID 3588, Tr.
3797). Evidence in the rulemaking record indicates that inclusion of
warning signs is also consistent with general industry practices. For
example, a plan developed by the National Service, Transmission,
Exploration, and Production Safety Network (STEPS Network) for the
hydraulic fracturing industry recommends signs to warn of potential
silica exposure and the requirement for respirator use near exposure
zones (Document ID 4024, Attachment 2, p. 1).
OSHA finds these arguments persuasive and agrees that it is
appropriate to require signs at entrances to regulated areas, which are
required only in the general industry and maritime standard (see
summary and explanation for Regulated Areas). Employees must recognize
when they are entering a regulated area and understand the hazards
associated with the area, as well as the need for respiratory
protection. Signs are an effective means of accomplishing these
objectives. Therefore, paragraph (j)(2) of the standard for general
industry and maritime requires that regulated areas be posted with
signs that bear the exact cautionary wording specified in the standard.
The required legend, which begins with the word "Danger", warns that
respirable crystalline silica is present and may cause cancer, states
that it causes damage to lungs, states that respiratory protection is
required, and indicates authorized personnel only are permitted to
enter. The purpose of these signs is to minimize the number of
employees in a regulated area by alerting them that they must be
authorized by their employer to enter, and to ensure that employees
take appropriate protective measures when entering. The signs will warn
employees who may not know they are entering a regulated area or may
not know of the hazards present in the area. They will supplement the
training that employees are to receive under other provisions of
paragraph (j) of the standard for general industry and maritime because
even trained employees need to be reminded of the locations of
regulated areas and of the necessary precautions they must take before
entering these dangerous areas.
The required language for the signs is consistent with labeling
requirements in Appendix C of the HCS, which specifies standardized
language to communicate information to employees. The revised HCS
requires the use of one of two signal words--"Danger" or
"Warning"--on labels of hazardous chemicals. The word "Danger" is
used for more severe hazard categories, such as carcinogens. OSHA is
requiring the word "Danger" based on the evidence of lung toxicity
and carcinogenicity of respirable crystalline silica. "Danger" is
used to alert employees that they are in an area where the permissible
exposure limit (PEL) is or can reasonably be expected to be exceeded
and to emphasize the importance of the message that follows.
Charles Gordon requested that warning signs also warn about kidney
hazards (Document ID 4236, p. 6). The hazard statements about cancer
and lung damage required on signs are the minimum requirements and
focus on the most prominent adverse health effects associated with
respirable crystalline silica exposure. OSHA concludes that it is
unnecessary to list every relevant hazard warning on signs at entrances
to regulated areas because other sources of information, such as SDSs
and training, will provide more comprehensive information to employees.
In addition, addressing cancer and lung damage is conceptually
consistent with specific wording suggestions from APHA, National
Consumers League, BCTD, HalenHardy, and AFL-CIO (Document ID 2178,
Attachment 1, pp. 2-3; 2373, p. 2; 2371, Attachment 1, pp. 36-37; 4030,
Exhibit D; 4204, p. 101). Including an abbreviated list of health hazards
on signs is also consistent with other OSHA standards such as lead
(29 CFR 1910.1025), benzene (29 CFR 1910.1028), and vinyl chloride
(29 CFR 1910.1017). Therefore, OSHA has decided not to add a requirement
to include warnings about kidney hazards on warning signs. Employers may
choose to include a warning about kidney hazards on the signs required
under this standard, provided that the additional information included is
not confusing or misleading and does not detract from warnings required by
the standard.
The warning sign must include notice about the need for respiratory
protection in regulated areas required under the general industry and
maritime standards. As explained in the summary and explanation of
Regulated Areas, employers covered by the standard for general industry
and maritime are required to provide each employee and his or her
designated representative entering a regulated area with an appropriate
respirator and require the employee and designated representative to
use the respirator while in the regulated area. APHA, National
Consumers League, and Charles Gordon requested that warning signs also
indicate that protective clothing is required (Document ID 2178,
Attachment 1, p. 3; 2373, p. 2; 4236, p. 6). As discussed in the
summary and explanation of Regulated Areas, protective clothing is not
required in this rule, and therefore no corresponding notice is
required on signs.
Some labor unions that represent construction employees, such as
BCTD, IUOE, and BAC, asked OSHA to include requirements for warning
signs in the construction standard to warn employees about health
hazards or requirements for control measures (e.g., Document ID 2371,
Attachment 1, pp. 36-37; 4025, Attachment 1, pp. 24-25; 4219, p. 27).
Some employers, like construction company Miller and Long, Inc.,
opposed requiring barricades and signs at construction sites (e.g.,
Document ID 3585, Tr. 2967).
As discussed in the summary and explanation of Regulated Areas,
OSHA is not requiring regulated areas in the standard for construction
because of the impracticality of establishing regulated areas in many
construction settings. Employers using specified exposure control
methods in Table 1 of paragraph (c) of the standard for construction
are not required to conduct exposure assessments and therefore will not
have the information necessary to establish the boundaries for the
regulated area (i.e., the point at which exposures would no longer
exceed the PEL). Even though regulated areas with warning signs are not
required for the construction standard, the employer may choose to
include procedures for posting warning signs in its written exposure
control plan as a method to restrict access to work areas, when
necessary, to limit the numbers of employees exposed to respirable
crystalline silica and the levels to which they are exposed, including
exposures generated by other employers or sole proprietors (paragraph
(g)(1)(iv) of the standard for construction). Because of the unique and
often-changing work areas at construction sites, OSHA concludes that a
universal requirement for regulated areas with signs is unwarranted,
and the construction employer is in the best position to determine when
warning signs should be posted.
IUOE requested a requirement to affix warning labels listing the
health hazards of respirable crystalline silica on enclosed cabs to
remind operators not to work with windows open (Document ID 2262, pp.
34-35). Where enclosed cabs are used to limit exposures to respirable
crystalline silica, the employer must ensure that these controls are
properly implemented (paragraph (c)(1) of the standard for
construction) and that employees can demonstrate knowledge of the
controls (paragraph (i)(2)(i)(C) of the standard for construction).
Therefore, OSHA concludes that a general requirement to affix warning
labels to cabs is unwarranted and construction employers are in the
best position to determine if there is a need for warning labels in
their workplaces as a reminder to properly implement controls. As a
result, OSHA has not included such a requirement in the standard.
Proposed paragraph (i)(2)(i) included the requirements related to
employee information and training. The proposed rule called for the
employer to ensure that each "affected employee" can demonstrate
knowledge of the specified training elements discussed below. OSHA
defined "affected employee" as any employee who may be exposed to
respirable crystalline silica under normal conditions of use or in a
foreseeable emergency. OSHA received several comments related to a
trigger for training requirements. For example, the American Iron and
Steel Institute (AISI) commented that the terms "each employee" and
"each affected employee" were used interchangeably in the proposed
rule and that OSHA needed to clarify which employees needed to receive
training; both Newport News Shipbuilding and AISI commented that
training should be limited to those employees who could foreseeably be
exposed above the PEL (Document ID 2144, p. 2; 3492, p. 3). Southern
Company was concerned that training would be required for all employees
potentially exposed to silica, and although disagreeing with an action
level of 25 micrograms per cubic meter of air ([mu]g/m\3\), requested
an action level-based trigger for training (Document ID 2185, p. 5). In
contrast, CISC supported training for all employees potentially exposed
to respirable crystalline at a construction site (Document ID 4217, p.
25). A number of other employers and industry representatives expressed
views on exposure levels that should trigger training, such as action
levels or PELs (e.g., Document ID 2196, Attachment 1, p. 11; 2279, p.
9; 2301, Attachment 1, p. 4; 2357, pp. 31-32; 2379, Appendix 1, p. 54).
BCTD requested that, in addition to employees performing work covered
by this section, OSHA require training for supervisors and on-site
managers who are responsible for, or who supervise, employees who
perform work covered by the standard (Document ID 4223, p. 117).
OSHA has clarified the trigger for training requirements in the
rule by aligning these requirements with the scope of the rule.
Paragraph (j)(3)(i) of the standard for general industry and maritime
(paragraph (i)(2)(i) of the standard for construction) requires
training for each employee covered by the rule. Consistent with the
scope provision in paragraph (a)(2) of the standard for general
industry and maritime, training is required for each employee, unless
the employer has objective data demonstrating that exposures will
remain below 25 [mu]g/m\3\ as an 8-hour time-weighted average under any
foreseeable conditions. Consistent with the scope provision in
paragraph (a) of the standard for construction, training is required
for all employees who are or could foreseeably be exposed to respirable
crystalline silica at or above the action level of 25 [mu]g/m\3\ as an
8-hour time-weighted average. Therefore, actual or foreseeable exposure
at or above the action level is used to determine which employees are
covered by the rule, and covered employers are required to provide
training for any employee covered by the rule. OSHA concludes that it is
appropriate to train employees covered by the rule because they will
benefit from receiving information such as the role of controls in
reducing exposures and illnesses associated with respirable crystalline
silica.
Stakeholders also offered comments on the proposed requirement that
employers ensure that affected employees can "demonstrate knowledge"
of the training subjects in proposed paragraphs (i)(2)(i)(A)-(D). The
proposed rule did not specify precisely how training should be
accomplished. Instead, it defined the hazard communication requirements
in terms of objectives meant to ensure that employees are made aware of
the hazards associated with respirable crystalline silica in their
workplace and how they can help to protect themselves. The proposed
rule's performance-oriented approach was consistent with the HCS and
many of OSHA's substance-specific standards.
Some stakeholders commented on OSHA's performance-based approach to
training. For example, Diane Matthew Brown, Health and Safety
Specialist from AFSCME, testified that training should be as
interactive as possible to allow for different learning styles
(Document ID 3585, Tr. 3115). CISC supported the performance-oriented
approach to training but also stated it would support a requirement
that employees be able to ask questions during training (Document ID
4217). IUOE recommended interactive training so that employees could
have their questions answered during the training (Document ID 3583,
Tr. 2369). Although agreeing with the importance of a knowledgeable
person to answer trainee questions, Ameren Corporation considered it
burdensome to have someone immediately available to answer questions
(Document ID 2315, p. 4). The Laborers' Health and Safety Fund of North
America (LHSFNA) indicated that hands-on training is the best approach
to training an employee who performs tasks that generate dust in the
proper operation of a tool and associated engineering controls
(Document ID 3589, Tr. 4220-4221).
After considering the comments on this issue, OSHA has decided that
the training requirements under the respirable crystalline silica rule,
like those in the HCS, are best accomplished when they are performance-
oriented. OSHA concludes that the employer is in the best position to
determine how the training can most effectively be accomplished. Hands-
on training, videotapes, slide presentations, classroom instruction,
informal discussions during safety meetings, written materials, or any
combination of these methods may be appropriate. However, to ensure
that employees comprehend the material presented during training, it is
critical that trainees have the opportunity to ask questions and
receive answers if they do not fully understand the material that is
presented to them. OSHA reiterates that when videotape presentations or
computer-based programs are used, this requirement may be met by having
a qualified trainer available to address questions after the
presentation, or providing a telephone hotline so that trainees will
have direct access to a qualified trainer. Although it is important
that employees be able to ask questions, OSHA finds that the employer
is in the best position to determine whether an instructor must be
available for questions during training or if a trainer can answer
questions after the training session. Such performance-oriented
requirements are intended to encourage employers to tailor training to
the needs of their workplaces, thereby resulting in the most effective
training program for each workplace.
In addition to asking about how training should be accomplished,
stakeholders posed questions about how employers can determine that
they have fulfilled the training requirements. For example, the
American Foundry Society stated that the term "demonstrate knowledge"
is vague and requested that the rule include language to specify when a
training requirement is met (Document ID 2379, Appendix 1, p. 72). OSHA
concludes that employers can determine whether employees have the
requisite knowledge through methods such as discussion of the required
training subjects, written tests, or oral quizzes. Retired industrial
hygienist Bill Kojola, testifying on behalf of the National Council for
Occupational Safety and Health (NCOSH), suggested that compliance
officers could question employees to determine if they know about
medical surveillance and work practices or engineering controls to
reduce exposures (Document ID 3586, Tr. 3259). Similarly, UAW
coordinator, Andrew Comai, and a private citizen, Cara Ivens, opined
that compliance officers could ask employees if they are aware that
they are working with hazardous chemicals or know about the health
effects of respirable crystalline silica (Document ID 1801, p. 4; 3582,
Tr. 1869). OSHA concludes that employers can similarly assess their
employees' knowledge and understanding of training topics.
The proposed rule did not include a provision that required
training to be conducted in a language and manner that the employee
understands. A number of labor unions and employee advocate groups
requested that the rule include a requirement for training to be
conducted in a language and manner that employees understand (e.g.,
Document ID 2240, p. 4; 2282, Attachment 3, p. 25; 3585, Tr. 3115;
3955, Attachment 2, p. 2; 3583, Tr. 2451; 4204, p. 99; 4025, Attachment
1, p. 2; 4219, p. 24).
OSHA agrees. Paragraph (j)(3)(i) of the standard for general
industry and maritime (paragraph (i)(2)(i) of the standard for
construction) requires the employer to ensure that each employee
covered by the standard demonstrates knowledge and understanding of the
required training subjects. The requirement for employers to ensure
that the employee demonstrates knowledge in the training subjects
obligates the employer to provide training in a language and manner
that the employee understands. The employee must understand training in
order to demonstrate knowledge of the specified training elements. To
clarify this requirement, OSHA has revised the proposed text to require
the employer to ensure that employees demonstrate understanding, in
addition to knowledge. This requirement is consistent with Assistant
Secretary David Michaels' memorandum to OSHA Regional Administrators
(Document ID 1499). The memorandum explains that because employees have
varying educational levels, literacy, and language skills, training
must be presented in a language, or languages, and at a level of
understanding that accounts for these differences in order to ensure
that employees understand the training. As stated by Assistant
Secretary Michaels:
...an employer must instruct its employees using both a language
and vocabulary that the employees can understand. For example, if an
employee does not speak or comprehend English, instruction must be
provided in a language that the employee can understand. Similarly,
if the employee's vocabulary is limited, the training must account
for that limitation. By the same token, if employees are not
literate, telling them to read training materials will not satisfy
the employer's training obligation (Document ID 1499, p. 2).
This may mean, for example, providing materials, instruction, or
assistance in Spanish rather than English if the employees being
trained are Spanish-speaking and do not understand English. However,
the employer is not required to provide training in the employee's
preferred language if the employee understands the language used
for training.
Proposed paragraphs (i)(2)(i)(A)-(D) specified the contents of
training for affected employees. The proposed list included training on
operations that could result in exposures and methods for protecting
employees from exposure, the contents of the respirable crystalline
silica rule, and the purpose and a description of the employer's
medical surveillance program. The proposed rule did not contain a
provision requiring training on health effects. However, under the HCS,
employers would have to train employees on the health hazards
associated with chemicals in the work area (29 CFR
1910.1200(h)(3)(ii)). In addition, the preamble to the proposed rule
mentioned that training on medical surveillance under proposed
paragraph (i)(2)(i)(D) should cover the signs and symptoms of
respirable crystalline silica-related health effects (78 FR at 56474).
OSHA asked for comments on the scope and depth of the proposed
training requirements and whether additional training provisions needed
to be added (78 FR at 56291). Stakeholders offered a number of comments
on these proposed provisions. For example, concerned individuals, a
medical school, and labor unions requested that training address the
health effects associated with respirable crystalline silica exposure
(e.g., Document ID 1771, p. 1; 2188; 3479, p. 1; 4025, Attachment 1, p.
2; 4203, p. 7). Training on health hazards of respirable crystalline
silica is consistent with stakeholder practices. For example, health
hazards are addressed in training plans or modules by the National
Precast Concrete Association, IUOE, and the STEPS Network (e.g.,
Document ID 2067, pp. 2-3; 3583, Tr. 2414; 4024, Attachment 2, p. 1).
Several commenters stated that employees would not ask for or use
appropriate protection without knowledge of health hazards (e.g.,
Document ID 2166, p. 3; 3571, Attachment 1, pp. 2-3, 3585, Tr. 2976).
For example, in discussing her experience with overhead drilling of
concrete, Sandra Darling-Roberts commented:
I had a dust mask and a pair of safety glasses for my
protection....We were not offered better personal protection
gear and did not request any as we were not made aware of the risks
of silica exposure (Document ID 1758).
Operating engineer Keith Murphy, representing IUOE, testified that
employees will wear respirators if informed that they are exposed to
dangerous concentrations of respirable crystalline silica (Document ID
3583, Tr. 2375-2376). In testifying about her experiences in training
construction employees, Mari[eacute]n Casillas Pabell[oacute]n,
Director of New Labor, stated:
[Seventy percent] of these workers were not able to say what
silica was or if they were...exposed to it. When they learned
about the long term effects to their health many were alarmed.
Training has been key in getting workers to demand...the right
equipment and tools to complete their task safely. Always after
trainings we follow up with the participants to measure the impact
of the trainings. [Fifty-five percent] of the workers that received
training around these issues expressed that they have demanded
personal protective equipment and other tools to do their work
safely after the training (Document ID 3571, Attachment 6, p. 2).
In addition, several employees indicated that neither they nor their
coworkers had received adequate or even any training on silica's health
effects (e.g., Document ID 3582, Tr. 1892-1893; 3589, Tr. 4299-4300;
4032, Attachment 1, p. 1; 3477, p. 1).
Based on the evidence showing the need for and positive impact of
health hazard training and to ensure that covered employees receive
that training, OSHA is requiring training on health hazards
specifically associated with respirable crystalline silica. The
requirement is contained in paragraph (j)(3)(i)(A) of the standard for
general industry and maritime (paragraph (i)(2)(i)(A) of the standard
for construction).
Proposed paragraph (i)(2)(i)(A) required that employees be trained
on specific operations in the workplace that could result in exposure
to respirable crystalline silica, especially operations where exposures
may exceed the PEL. BCTD recommended that "tasks" rather than
"operations" be used, because operations could include various tasks;
it also requested that OSHA remove the statement "especially
operations where exposure may exceed the PEL" (Document ID 2371,
Attachment 1, pp. 23, 35). OSHA agrees that "tasks" is the more
appropriate term. The Agency also agrees that employers and employees
must understand all sources of potential respirable crystalline silica
exposure and, therefore, removed the phrase "especially operations
where exposure may exceed the PEL." Therefore, OSHA has revised the
proposed language so that paragraph (j)(3)(i)(B) of the standard for
general industry and maritime (paragraph (i)(2)(i)(B) of the
construction standard) now requires training on specific workplace
tasks that could result in exposure to respirable crystalline silica.
Proposed paragraph (i)(2)(i)(B) required that employees be trained
on procedures implemented by the employer to protect them from
respirable crystalline silica exposure, including appropriate work
practices and use of personal protective equipment (PPE), such as
respirators and protective clothing. Labor unions and employee advocate
groups, such as CWA, UAW, USW, NCOSH, AFSCME, IUOE, and BCTD, requested
that OSHA also specify training on engineering controls (Document ID
2240, p. 4; 2282, Attachment 3, p. 24; 2336, p. 15; 3955, Attachment 2,
p. 2; 4203, p. 7; 4025, Attachment 1, p. 2; 4223, p. 118). The value of
training on engineering controls is demonstrated by the testimony of
construction employee and New Labor Safety Liaison, Norlan Trejo, who
stated that because of his training, he is aware of the types of
engineering controls needed on job sites and he requests such controls
if the employer does not provide them (Document ID 3583, Tr. 2462-
2463).
Because engineering controls are a vital aspect of reducing
exposures, OSHA has concluded that employees covered by this rule must
understand how they work in order to use the appropriate work practices
to fully and properly implement those controls and to be able to
recognize if engineering controls are malfunctioning. Therefore, OSHA
has revised the proposed provision to also require training on
engineering controls. OSHA has also removed the term "appropriate"
because it is implicit that any work practice or other methods used to
protect employees be appropriate. In addition, "personal protective
equipment" and "protective clothing" were removed from the paragraph
because respirators are the only type of PPE required by the rule.
Thus, paragraph (j)(3)(i)(C) of the standard for general industry and
maritime (paragraph (i)(2)(i)(C) of the standard for construction)
requires training on specific measures implemented by the employer to
protect employees from respirable crystalline silica exposure,
including engineering controls, work practices, and respirators to be
used.
Several labor unions that represent employees in the construction
industry highlighted additional training that they thought necessary
for some construction employees. For example, BCTD requested that OSHA
establish tiered training requirements in the construction standard to
include: (1) Basic awareness training for all employees potentially
exposed to respirable crystalline silica, (2) additional equipment-specific
training for employees who perform tasks that generate respirable
crystalline silica, and (3) training for a competent person. BCTD
noted that similar approaches were taken in other OSHA standards, such
as asbestos (29 CFR 1926.1101(k)(9)) (Document ID 4223, pp. 114, 116-117).
The tiered approach to training recommended by BCTD was also supported
by IUOE, LHSFNA, and BAC (Document ID 3583, Tr. 2367-2368; 4207, p. 5;
4219, pp. 22-24).
In supporting a tiered approach, BCTD noted "the effectiveness of
the standard and the engineering controls used to limit silica exposure
depend heavily on how the controls are used." (Document ID 4223, p.
117). Dr. Paul Schulte, Director of the Education and Information
Division at the National Institute for Occupational Safety and Health,
testified that engineering controls listed in Table 1 are only
effective if they are maintained and employees are trained on their
correct use (Document ID 3403, p. 6). Similar views regarding training
and effectiveness of controls were expressed by Joel Guth, President of
iQ Power Tools, Bill Kojola, and Tom Nunziata, instructor/training
coordinator for LHSFNA; Mr. Nunziata also noted the importance of
hands-on training (Document ID 3585, Tr. 2982-2983; 3586, Tr. 3204-
3206; 3589, Tr. 4220-4221).
Evidence in the record further demonstrates knowledge of work
practices that employees must have for controls to function
effectively. For example, the user's manual for Stihl's gasoline-
powered hand-held portable saws recommends training of operators, and
it indicates that operators need to know minimum water flow rates, how
to control flow rate to ensure an adequate volume of water to the
cutting area, and to rinse the screen if no or little water is fed to
the cutting wheel during use (Document ID 3998, Attachment 12a, pp. 3,
15, 23). Similarly, the effectiveness of local exhaust ventilation
systems, another common method used to control exposures to respirable
crystalline silica, is often enhanced by the use of proper work
practices. For instance, when tuckpointing, employees should ensure
that the shroud surrounding the grinding wheel remains flush against
the working surface, when possible, to minimize the amount of dust that
escapes from the collection system. Operating the grinder in one
direction (counter to the direction of blade rotation) is effective in
directing mortar debris into the exhaust system, and backing the blade
off before removing it from the slot permits the exhaust system to
clear accumulated dust (78 FR at 56474). Employees using vacuum
controls also need to be aware of appropriate ways to clean the filter,
such as using a valve on the vacuum to clean the filter with
backpressure instead of pounding the filter on a surface (Document ID
3998, Attachment 13b, p. 460).
The record also contains evidence demonstrating the importance of
employees understanding how to effectively operate and maintain
controls on heavy equipment to prevent exposures to respirable
crystalline silica in the construction industry. For example, IUOE
noted that the role of operating engineers in ensuring integrity of
enclosed cabs includes keeping windows and doors closed, maintaining
good housekeeping practices, cleaning dust from boots before entering
the cab, and reporting malfunctioning seals and air conditioning
(Document ID 2262, pp. 35-36). In addition, IUOE noted that operator
control of water flow rates for dust suppression is important for
protecting employees from exposure and preventing excessive water
runoff into the environment (Document ID 4234, Part 1, pp. 27-28).
Anthony Bodway, Special Projects Manager at Payne & Dolan, Inc.,
representing the National Asphalt Pavement Association (NAPA), noted
that all Payne & Dolan's operators have been trained to conduct daily
maintenance checks of their equipment (Document ID 3583, Tr. 2194-
2195). A best practices bulletin developed in part by NAPA requires
machine operators to demonstrate knowledge of the machine's dust
suppression system including flow rates, maintenance, troubleshooting,
and visual inspections; in addition a letter from manufacturer Wirtgen
America stressed the importance of operator training on operating and
maintaining machines to minimize respirable dust (Document ID 2181, pp.
25, 52).
OSHA agrees that actions, such as controlling water flow rates,
ensuring integrity of controls, addressing a non-functioning control,
and proper housekeeping in cabs, are work practices that promote
effectiveness of controls. However, the Agency does not agree that
construction employees who perform tasks that generate respirable
crystalline silica dust require training beyond what paragraph
(i)(2)(i)(C) of the standard for construction already requires. As
noted above, paragraph (i)(2)(i)(C) of the standard for construction
requires employers to ensure that employees covered by the standard can
demonstrate knowledge and understanding of specific measures the
employer has implemented to protect them from respirable crystalline
silica exposure, including engineering controls, work practices, and
respirators to be used. Under this provision, the knowledge required of
each employee depends on the tasks he or she performs. That was the
intent of the proposed standard and it has not changed in the standard.
OSHA concludes that this provision, as written, requires employers to
provide employees with the different types and levels of training they
need, depending on the types of tasks they conduct. For example,
laborers who do not operate equipment that generates respirable
crystalline silica dust would only need to be aware of the general
types of controls used, such as water and local exhaust. However, those
laborers would need to know about work practices for tasks they
perform, such as appropriate clean-up of respirable crystalline silica
dust accumulations. On the other hand, employees who operate tools with
built-in controls, such as saws with integrated water delivery systems,
would need to demonstrate knowledge and understanding of the full and
proper implementation of the controls on those tools.
OSHA is also not mandating additional training for a competent
person in paragraph (i) of the standard for construction. As discussed
in more detail in the summary and explanation of Written Exposure
Control Plan, the training requirements mandated by this standard
already impart a high level of competence. OSHA recognizes that there
may be situations in which an employee needs additional training in
order to ensure that he or she has the knowledge, skill, and ability to
be a designated competent person, but because of unique scenarios in
construction environments, those training requirements would vary
widely. OSHA concludes, therefore, that it is the employer's
responsibility to identify and provide any additional training that the
competent person would need to implement the written exposure control
plan.
AFL-CIO and USW requested that the standard for general industry
also mandate a tiered approach that includes a higher level of training
for employees who perform silica dust-generating tasks and training of
a competent person; both those groups and UAW noted the importance of
workplace- or job-specific training on engineering controls and work
practices (Document ID 2282, Attachment 3, p. 24; 4204, p. 99; 4214, p.
14).
OSHA concludes that employees are already required to demonstrate
workplace- and job-specific knowledge and understanding of work
practices associated with the tasks they conduct under paragraph
(j)(3)(i)(C) of the standard for general industry and maritime. That
was the intent of the proposed standard and it has not changed in the
standard. Engineering controls in general industry commonly involve
measures such as ventilation systems that protect several employees,
and are often not subject to the direct control of the employee
performing the task (see Chapter IV of the Final Economic Analysis and
Final Regulatory Flexibility Analysis). In those cases, training would
include a description of the specific types of engineering controls
used at that facility, including signs that the controls may not be
working effectively (e.g., visible dust emission). Training would also
address any work practices needed for the controls to function
effectively (e.g., not opening windows near local exhaust sources,
positioning the local exhaust hood directly over the exposure source).
If employees covered by the general industry and maritime standard
operate equipment with built in controls that are under their control,
those employees are required to demonstrate knowledge and understanding
of the full and proper implementation of those controls. Therefore,
OSHA is not requiring additional training for general industry and
maritime employees who perform tasks that generate respirable
crystalline silica dust because it is already required by paragraph
(j)(3)(i)(C) of the standard for general industry and maritime.
Training of a competent person is not applicable to the general
industry and maritime standard because OSHA is not requiring a
competent person. As explained in the summary and explanation of
Written Exposure Control Plan, OSHA is not requiring a competent person
because reasons for designating a competent person in construction are
not applicable to most general industry worksites. For example, general
industry worksites usually have less environmental variability and it
is reasonable and generally feasible to establish regulated areas to
limit access and perform exposure assessments to verify effective
control of exposure.
OSHA has retained the proposed requirement for training on the
contents of the respirable crystalline silica rule in paragraph
(j)(3)(i)(D) of the standard for general industry and maritime
(paragraph (i)(2)(i)(D) of the standard for construction). This
paragraph parallels the HCS requirement to inform employees about the
requirements of the HCS section (29 CFR 1910.1200(h)(2)(i)), and
similar paragraphs have been included in all OSHA substance-specific
standards.
Proposed paragraph (i)(2)(i)(D) required employers to train
employees about the purpose and description of the medical surveillance
program, and OSHA has retained that requirement in the rule under
paragraph (j)(3)(i)(E) of the standard for general industry and
maritime (paragraph (i)(2)(i)(F) of the standard for construction).
Paragraph (i) of the standard for general industry and maritime
(paragraph (h) of the standard for construction) describes the
requirements of the medical surveillance program, such as the
examinations that must be offered to qualifying employees. OSHA finds
that employees will benefit from learning about the purpose of medical
surveillance and symptoms associated with respirable crystalline
silica-related diseases, as described in the summary and explanation of
Medical Surveillance. OSHA recommends that employers in construction or
other high-turnover industries inform employees to keep their copy of
the physician or other licensed health care professional's written
medical opinion for the employer as proof of a current medical
examination and that proof of a current examination could ensure that
employees get timely examinations or spare employees from unnecessary
testing, such as X-rays. OSHA also recommends that employers inform
employees that they cannot be retaliated against for participating in
medical surveillance. This information will help to ensure that
employees are able to effectively participate in medical surveillance.
The proposed rule did not require employees to be trained on the
identity of the competent person. Several labor unions, including IUOE,
LHSFNA, BAC, and BCTD requested that employees receive training on the
written exposure control plan or identity of the competent person
(Document ID 3583, Tr. 2367-2368; 3589, Tr. 4222; 2329, p. 5; 4223, p.
118). Paragraph (g)(4) of the standard for construction requires
employers to designate a competent person to make frequent and regular
inspections of job sites, materials, and equipment to implement the
written exposure control plan. The written exposure control plan in the
construction standard describes tasks in the workplace that involve
exposure to respirable crystalline silica; engineering controls, work
practices, and respiratory protection used to limit employee exposures;
housekeeping methods used to limit employee exposures; and procedures
used to restrict access, when necessary, to minimize employees exposed
and their level of exposure, including exposures generated by other
employers or sole proprietors (paragraph (g)(1)(i)-(iv)). OSHA is not
requiring the identity of the competent person to be listed in the
written exposure control plan because it could change daily. However,
construction employees must be able to identify the competent person in
situations where they have a question or concern about the subjects
covered in the written exposure control plan. For example, if an
engineering control is not working properly, an employee may need to
contact the competent person for help in addressing the problem.
Therefore, paragraph (i)(2)(i)(E) of the standard for construction
requires employees to be informed of the competent person's identity.
However, OSHA is not specifying training on the written exposure
control plan because the contents of that plan, including its
availability to employees, is already addressed by training on the
contents of this section under paragraph (i)(2)(i)(D) of the standard
for construction.
Some stakeholders requested that OSHA provide greater specificity
on training requirements. For example, Fann Contracting, Inc. asked
OSHA to spell out what training is required for different industries
(Document ID 2116, Attachment 1, p. 46). NAHB stated that specifying
training requirements would simplify training for construction
employers (Document ID 2296, p. 44). John Scardella, Program
Administrator for USW, testified that training should not be left to
the discretion of employers because they might not prioritize employee
health and safety (Document ID 3479, p. 2). USW and LHSFNA requested
more detailed training requirements, such as those of the asbestos
standard (29 CFR 1910.1001; 1926.1101) that specify what is to be
addressed under each major training topic (Document ID 2336, pp. 14-15;
3589, Tr. 4219).
Although OSHA agrees with these commenters that comprehensive
training is a key part of hazard communication, the Agency recognizes
that it is difficult to provide more specificity as a result of unique
scenarios among different employers and industries. However, to help
employers develop training programs that are comprehensive for general
training subjects that apply to most covered industries, OSHA has
developed a number of guidance products that are already available
through its Web site. In addition, the Agency is planning to develop
guidance products specific to the rule, as has been suggested by NAHB
(Document ID 2296, p. 39). Numerous governmental and other
organizations have already developed guidance products for training
(e.g., Document ID 1722; 4025, Attachment 2; 4053, Exhibit 3a-3e and 4;
4073, Attachment 8i). As has been the case with all OSHA standards,
OSHA expects that the private sector will develop training products and
programs, which will further help ensure comprehensive training.
Commenters also argued that OSHA should include requirements for
training on other topics. For example, IUOE requested training on
topics such as SDSs, signs, use and care of respiratory protection, and
work practices for heavy machine operators (Document ID 2262, pp. 36-
38; 4025, Attachment 1, p. 2). LHSFNA and BCTD requested training on
exposure assessment (Document ID 3589, Tr. 4222; 4223, p. 118). AFSCME
requested training on personal hygiene (Document ID 4203, p. 7).
OSHA concludes, however, that the employee information and training
provisions in the respirable crystalline silica rule and the HCS are
sufficiently informative. For example, the HCS requires employers to
provide training on SDSs and on the signal words and hazard statements
that are used on the signs required by the general industry and
maritime standard. Under the HCS, employers must also train employees
about the location and availability of the written HCS program,
including the required list(s) of hazardous chemicals and SDSs. The HCS
also requires employers to train employees on the methods and
observations that may be used to detect the presence or release of a
hazardous chemical in the work area; in the case of respirable
crystalline silica, this could include a description of the employer's
exposure assessments methods (e.g., objective assessments, personal
breathing zone air sampling, direct readings of respirable dust) and
warnings that visible dust emissions might indicate a problem.
Because employers must meet the requirements of the HCS, OSHA does
not find it necessary to repeat the training requirements of that
standard in their entirety in the respirable crystalline silica rule.
Moreover, even if all training requirements of the HCS were repeated in
the respirable crystalline silica rule, most employers would still have
to consult the hazard communication requirements of other hazardous
chemicals, because they have employees exposed to other chemicals in
their workplace. Consequently, OSHA concludes that these provisions,
and the other requirements of the HCS and this standard, are
sufficient.
OSHA also concludes that additional training on respiratory
protection or personal hygiene is unnecessary. Training on the use and
care of respiratory protection is already required under the
respiratory protection standard (29 CFR 1910.134). OSHA similarly
concludes that training in personal hygiene is not needed as a required
training topic in this rule because personal hygiene measures relevant
to respirable crystalline silica exposure, such as avoiding use of
compressed air as a method to clean dust off of clothing, are
adequately addressed by other requirements of the rule and are covered
by training on work practices. Some training topics suggested by
commenters, such as communication methods for employees in enclosed
cabs, are specific to certain work scenarios. OSHA has concluded that
employers are in the best position to determine which additional,
unique training requirements are relevant to their type of industry.
For example, in construction, the competent person might be able to
identify situations where employees need more training because they are
not demonstrating knowledge and understanding of a specific measure the
employee has implemented to protect them.
OSHA's proposed rule required the employer to make a copy of the
standard readily available without cost to each employee covered by the
respirable crystalline silica rule, and OSHA has retained this
requirement in paragraph (j)(3)(ii) of the standard for general
industry and maritime (paragraph (i)(2)(ii) of the standard for
construction). This is a common requirement in OSHA standards such as
chromium (VI) (29 CFR 1910.1026), acrylonitrile (29 CFR 1910.1045), and
cotton dust (29 CFR 1910.1043). The provision leaves employers free to
determine the best way to make the standard available, such as a
printed or electronic copy in a central location that employees can
easily access. OSHA concludes that employees need to be familiar with
and have access to the respirable crystalline silica standard for
general industry and maritime or construction, as applicable, and be
aware of the employer's obligations to comply with it.
OSHA did not propose a requirement for labels or signs in languages
other than English. Ameren requested the rule include a requirement
that labels include appropriate languages for employees who do not
understand English (Document ID 2315, p. 4). Charles Gordon and BAC
requested that warning signs be presented in a language or manner that
employees can understand, and, as noted by BAC, the method could
include graphics (Document ID 3588, Tr. 3805; 4219, p. 27).
Requirements for labels on hazardous chemicals are set forth in
paragraph (f) of the HCS, which does not require languages other than
English. However, the HCS requires the inclusion of certain information
on labels on shipped containers, including pictograms (29 CFR
1910.1200(f)(1)(iv)), and mandates that containers in the workplace be
labeled either in accordance with the rules for shipping containers or
with product identifier and combinations of words, pictures, or symbols
to warn of hazards. OSHA has concluded that with training required
under the HCS (29 CFR 1910.1200(h)(3)(iv)), even employees who are not
literate in English will have sufficient knowledge of respirable
crystalline silica hazards. Likewise, with training, employees will be
able to recognize the meaning of signs at the entrances to regulated
areas and the need for respiratory protection in these areas.
OSHA's proposed rule did not specify when and how often employees
must be trained. Some stakeholders offered opinions about when an
employer's obligation to train covered employees should begin. For
example, USW, NCOSH, and LHSFNA requested that the rule for respirable
crystalline silica require training before or at the time employees are
assigned or placed in a job with respirable crystalline silica exposure
(Document ID 3479, p.1; 3955, Attachment 2, p. 1; 3589, Tr. 4222). CWA,
Upstate Medical College, UAW, AFSCME, AFL-CIO, and BCTD requested that
the rule for respirable crystalline silica require training before
employees are assigned to or placed in a job or task with respirable
crystalline silica exposure (Document ID 2240, p. 4; 2244, p. 4; 2282,
Attachment 3, pp. 24-25; 4203 p. 7; 4204, p. 99; 4223, p. 117).
OSHA agrees that each employee needs to be trained sufficiently to
understand the specified training elements at the time of initial
assignment to a position involving exposure to respirable crystalline
silica. The rule requires the employer to ensure that each employee can
demonstrate knowledge and understanding of the specified training
elements; this requirement applies from the time that the employee is
covered by the rule. This requirement is consistent with the HCS, which
requires that employers provide employees with effective information
and training on hazardous chemicals in their work area at the time of
their initial assignment (29 CFR 1910.1200(h)(1)).
Stakeholders also commented on how often employers should be
required to train their employees. CWA, Upstate Medical College, UAW,
NCOSH, AFSCME, and LHSFNA recommended periodic refresher training and
additional training if methods, equipment, or controls change (Document
ID 2240, p. 4; 2244, p. 4; 2282, Attachment 3, pp. 24-25; 3955,
Attachment 2, p. 2; 4203 p. 8; 3589, Tr. 4222). Similarly, USW and AFL-
CIO asked that OSHA require periodic refresher training (Document ID
3479, p.1; 4204, p. 99). In addition, BCTD recommended additional
training when the employer believes an employee requires more training
because of a lack of skill or understanding (Document ID 4223, p. 117).
OSHA agrees with commenters that additional or repeated training
may be necessary under certain circumstances but does not consider it
appropriate to impose a fixed schedule of periodic training. Therefore,
the requirement for training is performance-oriented in order to allow
flexibility for employers to provide training as needed to ensure that
each employee can demonstrate the knowledge and understanding required
under the rule. For example, if an employer observes an employee
engaging in activities that contradict knowledge gained through
training, it is a sign to the employer that the employee may require a
reminder or periodic retraining on work practices.
Because paragraph (j)(3)(i)(C) of the standard for general industry
and maritime (paragraph (i)(2)(i)(C) of the standard for construction)
requires training on the specific measures the employee has implemented
to protect employees, additional training is already required after new
engineering controls are installed, new work practices are implemented,
or employees are given new types of respirators. Because this provision
requires employers to provide additional training following changes in
protective measures or equipment, they ensure that employees are able
to properly use the new controls, implement work practices relating to
those controls, and properly use respirators to actively protect
themselves under the conditions found in the workplace, even if those
conditions change.
OSHA did not include a requirement for employees to be certified as
having received training in the proposed rule. Commenters including Dr.
Ruth Ruttenberg, representing the AFL-CIO, have voiced support for a
portable training record or certification-based approach; Dr.
Ruttenberg noted that this would reduce costs by avoiding the need for
each new employer to conduct full training (Document ID 1950, pp. 11-
12; 2256, Attachment 4, p. 5; 4235, p. 14). OSHA is not including a
requirement for a portable training record in the rule. This approach
is consistent with the HCS, which neither requires nor precludes a
training record that could be portable. Employee training requirements
might be partially fulfilled by training obtained through trade
associations, unions, colleges, or professional schools. However, the
employer is always ultimately responsible for ensuring that employees
are adequately trained, regardless of the method relied upon to comply
with the training requirements.
OSHA concludes that a portable training record is unlikely to
eliminate the need for employer-specific or site-specific training. For
example, Barbara McCabe, Program Manager for IUOE, testified that IUOE
local unions train employees but employees would need site-specific
training when they report to the worksite (Document ID 3583, Tr. 2368).
An example of a case where site-specific training is needed was noted
by BAC, who commented that an employee who operated a saw with water
controls at one site may be given a saw with vacuum controls at another
site (Document ID 4219, p. 23).
OSHA concludes that some site-specific or employer-specific
training is always necessary, such as training on specific tasks that
could result in exposures, controls or work practices that the employer
has implemented, or the identity of the competent person (paragraphs
(j)(3)(i)(B) and (C) of the standard for general industry and maritime
and paragraphs (i)(2)(i)(B), (C), and (E) of the standard for
construction). Full training would not be required if an employee is
already able to demonstrate knowledge in health hazards, the contents
of the respirable crystalline silica rule, or medical surveillance for
respirable crystalline silica (paragraphs (j)(3)(i)(A), (D), and (E) of
the standard for general industry and maritime, paragraphs
(i)(2)(i)(A), (D) and (F) of the standard for construction). Site-
specific training is unlikely to be costly or time-consuming. OSHA
concludes that assessing an employee's knowledge to determine the type
and level of additional training required is more meaningful than
simply accepting a certificate of training.
Bill Kojola requested that the rule specify that training be
provided at no cost to the employee and during work hours (Document ID
3955, Attachment 2, p. 2). In addition, Norlan Trejo from New Labor
testified that he never saw an employer pay for training (Document ID
3583, Tr. 2469). As stated above, an employer may rely on an employee's
previous training, if the employee can demonstrate knowledge in
training requisites. Any training provided by the employer to meet the
requirements of the rule must be provided at no cost to the employee.
Employees must also be paid for time spent in training. This is
consistent with other OSHA standards that do not include an explicit
requirement for employer payment for training in the regulatory text,
e.g., the HCS requires training (1910.1200(h)(3)) but does not mention
cost; the compliance directive (CPL 02-02-079 says "Training is
required to be provided at no cost to the employees. Employees must be
paid for the time they spend at training.)"
In the Notice of Proposed Rulemaking, OSHA asked whether labeling
of substances containing more than 0.1 percent crystalline silica was
appropriate, as required by the HCS, or if the threshold for labeling
should be greater than 1 percent crystalline silica (78 FR at 56291). A
number of industry groups suggested a threshold for including
respirable crystalline silica on labels or SDSs. With the exception of
NISA, who favored a 0.1 percent threshold, the commenters requested a
threshold of 1 percent or greater or thought that a 0.1 percent
threshold could be problematic (Document ID 1785, p. 4; 2179, pp. 3-4;
2101, pp. 8-9; 2284, p. 10; 2296, p. 44; 2312, p. 3; 2317, p. 3; 2319,
p. 120; 2327, Attachment 1, p. 14; 4208, pp. 19-20). The International
Diatomite Producers Association agreed with NISA that the threshold for
hazard communication should be 0.1 percent for respirable crystalline
silica but requested an exception for respirable crystalline silica in
natural (uncalcined) diatomaceous earth, according to OSHA's current
policy (Document ID 4212, pp. 6-7).
The classification of hazardous chemicals, including chemicals
containing silica, is determined by the HCS. As explained in Section V,
Health Effects, OSHA has determined, consistent with the National
Toxicology Program and International Agency for Research on Cancer
classifications, that respirable crystalline silica is a carcinogen.
Under the HCS, a mixture that contains a carcinogen must itself be
classified as a carcinogen when at least one ingredient in it has been
classified as a Category 1 or Category 2 carcinogen and is present at or
above the appropriate cut-off value/concentration limit specified in
HCS Table A.6.1 (29 CFR 1910.1200, Appendix A, A.6.3.1). Table A.6.1
sets the cut-off value at greater than or equal to 0.1 percent. Footnote 7
to 1910.1200, Appendix A, A.6.3 notes that the cut-off value is the
primary means of classification of carcinogens and may only be modified on
a case-by-case evaluation based on available test data for the mixture as
a whole. Classification of a chemical under the HCS triggers labeling
requirements under that standard, and OSHA does not find it appropriate to
impose different requirements in this rule. To do so would be at odds with
the concept of harmonizing national and international requirements for
classification and labelling of chemicals that is the basis of the GHS
and HCS.
OSHA also did not propose requirements related to the creation and
retention of training records, but some commenters expressed opinions
on this issue. For example, CISC commented that they would agree to
document that employees completed training and demonstrated knowledge
(Document ID 4217, p. 25). Consistent with the HCS, employers are not
required to keep records of training under the rule for respirable
crystalline silica, but employers may find it valuable to do so.
Comments on this issue and OSHA's rationale for this decision are
discussed in the summary and explanation of Recordkeeping.
ASTM standards. The training requirements in the respirable
crystalline silica standards are generally consistent with but differ
slightly from ASTM International (ASTM) standards ASTM E 1132-06,
Standard Practice for Health Requirements Relating to Occupational
Exposure to Respirable Crystalline Silica and ASTM E 2625-09, Standard
Practice for Controlling Occupational Exposure to Respirable
Crystalline Silica for Construction and Demolition Activities (Section
4.8 in both E 1132-06 and E 2625-09) (Document ID 1466, p. 6; 1504, p.
6). The E 1132-06 standard requires training for employees exposed at
any level and the E 2625-09 standard for construction and demolition
requires training for employees potentially exposed to high levels. The
ASTM standards also include: (1) More specificity on training
requirements such as annual training (E 1132-06 only), training when
employees demonstrate unsafe work practices, training in an appropriate
language and manner, and documentation of training (certification in
the case of E 1132-06); (2) training on tuberculosis and relationships
between smoking and silica exposure in both standards and no training
for autoimmune and kidney hazards in E 2625-09; (3) training on
respirator use and hygiene; and (4) warning signs for construction and
demolition workplaces in E 2625-09.
OSHA is requiring that each employee covered by the rule receive
training; employees may be at significant risk even if they are not
exposed to "high levels" of respirable crystalline silica. In
comparison to the ASTM standards, the requirements for training under
the respirable crystalline silica rule are more performance-based in
terms of when training is required. The health hazards addressed in the
rule are based upon OSHA's health effects assessments and consistency
with health hazard classification in the HCS. OSHA already requires
training on respirator use under its respiratory protection standard
(29 CFR 1910.134). The rule does not specify training on hygiene
because personal hygiene is addressed by other requirements of the rule
and training on work practices. OSHA is not requiring warning signs in
the standard for construction because employers are in the best
position to determine if and when signs are appropriate for restricting
access to work areas to limit employee exposure to respirable
crystalline silica. For the reasons described above, OSHA concludes
that the requirements of the rule better effectuate the purposes of the
OSH Act of 1970 than the ASTM standards.
Recordkeeping
Paragraph (k) of the standard for general industry and maritime
(paragraph (j) of the standard for construction) requires employers to
make and maintain air monitoring data, objective data, and medical
surveillance records. The recordkeeping requirements are in accordance
with section 8(c) of the Occupational Safety and Health (OSH) Act (29
U.S.C. 657(c)), which authorizes OSHA to require employers to keep and
make available records as necessary or appropriate for the enforcement
of the OSH Act or for developing information regarding the causes and
prevention of occupational accidents and illnesses.
Paragraph (k)(1)(i) of the standard for general industry and
maritime (paragraph (j)(1)(i) of the standard for construction) is
substantively unchanged from the proposed rule. It requires the
employer to make and maintain accurate records of all exposure
measurements taken to assess employee exposure to respirable
crystalline silica, as prescribed in paragraph (d) of the standard for
general industry and maritime (paragraph (d)(2) of the standard for
construction). OSHA has added the words "make and" prior to
"maintain" in order to clarify that the employer's obligation is to
create and preserve such records. This clarification has also been made
for other records required by the silica rule. In addition, OSHA now
refers to "measurements taken to assess employee exposure" rather
than "measurement results used or relied on to characterize employee
exposure." This change is editorial, and is intended to clarify OSHA's
intent that all measurements of employee exposure to respirable
crystalline silica be maintained. Paragraph (k)(1)(ii) of the standard
for general industry and maritime (paragraph (j)(1)(ii) of the standard
for construction) requires that such records include the following
information: The date of measurement for each sample taken; the task
monitored; sampling and analytical methods used; the number, duration,
and results of samples taken; the identity of the laboratory that
performed the analysis; the type of personal protective equipment, such
as respirators, worn by the employees monitored; and the name, social
security number, and job classification of all employees represented by
the monitoring, indicating which employees were actually monitored.
OSHA has made one editorial modification that differs from the
proposed rule in paragraph (k)(1)(ii)(B) of the standard for general
industry and maritime (paragraph (j)(1)(ii)(B) of the standard for
construction) and that is to change "the operation monitored" to
"the task monitored." Both "task" and "operation" are commonly
used in describing work. However, OSHA uses the term "task"
throughout the rule, and the Agency is using "task" in the
recordkeeping provision for consistency and to avoid any potential
misunderstanding that could result from using a different term. This
editorial change neither increases nor decreases an employer's
obligations as set forth in the proposed rule.
The recordkeeping provision that received the most comments was
proposed paragraph (j)(1)(ii)(G) (now paragraph (k)(1)(ii)(G) of the
standard for general industry and maritime, paragraph (j)(1)(ii)(G) of
the standard for construction), which, consistent with existing
recordkeeping requirements in OSHA health standards, requires the
employer to include in the standard's mandated records the employee's
social security number. Morgan Electro Ceramics, National Electrical
Carbon Products, Inc. (NECP), Southern Company, the National Tile
Contractors Association (NTCA), Dow Chemical Company, the Asphalt Roofing
Manufacturers Association (ARMA), the American Petroleum Institute
(API), the Marcellus Shale Coalition, Ameren Corporation, the North
American Insulation Manufacturers Association (NAIMA), Edison Electric
Institute (EEI), the Tile Council of North America (TCNA), the American
Foundry Society (AFS), the Nevada Mining Association (NMA), Newmont
Mining Corporation (NM), and others opposed the requirement (e.g.,
Document ID 1772, p.1; 1785, pp. 9-10; 2185, pp. 8; 2267, p. 7; 2270,
p. 3; 2291, p. 26; 2301, Attachment 1, pp. 80-81; 2311, p. 3; 2315, p.
7; 2348, Attachment 1, p. 39; 2357, pp. 36-37; 2363, p. 7; 2379,
Appendix 1, p. 73; 2107, p. 4; 1963, p. 3). The commenters, citing
employee privacy and identity theft concerns, wanted to be allowed to
use an identifier other than the social security number, such as an
employee identification number, an employee driver's license number, or
another unique personal identification number. For example, NAIMA
stated "Using social security numbers is a dangerous threat to
personal privacy and identify theft that OSHA should affirmatively
discourage" (Document ID 2348, Attachment 1, p. 39). Commenters
acknowledged that social security numbers must be used for some reports
to the government and thus are present in some employer records, but
that access to these records is usually more restricted than to air
monitoring records.
OSHA has considered the comments it received on this issue and has
decided to retain the requirement for including the employee's social
security number in the recordkeeping requirements of the rule. The
requirement to use an employee's social security number is a long-
standing OSHA practice, based on the fact that it is a number that is
both unique to an individual and is retained for a lifetime, and does
not change as an employee changes employers. The social security number
is therefore a useful tool for tracking employee exposures,
particularly where exposures are associated with diseases such as
silicosis that generally have a long latency period and can develop
over a period of time during which an employee may have several
employers.
OSHA is cognizant of the privacy concerns expressed by commenters
regarding this requirement, and understands the need to balance that
interest against the public health interest in requiring the social
security identifier. Instances of identity theft and breeches of
personal privacy are widely reported and concerning. However, OSHA has
concluded that this rule should adhere to the past, consistent practice
of requiring employee social security numbers on exposure records
mandated by every OSHA substance-specific health standard, and that any
change to the Agency's requirements for including employee social
security numbers on exposure records should be comprehensive. Some
employers who are covered by this rule, such as employers who perform
abrasive blasting on surfaces coated with lead, cadmium, or chromium
(VI), will be covered by more than one OSHA standard. OSHA examined
alternative forms of identification in Phase II of the Agency's
Standards Improvement Project, but did not revise requirements for the
use of social security numbers (70 FR 1111-1144 (1/5/2005)).
Nevertheless, given increasing concerns regarding identity theft and
privacy issues, as evidenced by stakeholder comments in this rulemaking
record, OSHA intends to examine the requirements for social security
numbers in all of its substance-specific health standards in a future
rulemaking. In the meantime, the requirement to use and retain social
security numbers to comply with this rule remains.
The remaining requirements of paragraph (k)(1)(ii) of the standard
for general industry and maritime (paragraph (j)(1)(ii) of the standard
for construction) are generally consistent with those found in other
OSHA standards, such as the standards for methylene chloride (29 CFR
1910.1052) and chromium (VI) (29 CFR 1910.1026). The additional
requirement to include the identity of the laboratory that performed
the analysis of exposure measurements is for the reason stated in the
preamble to the Notice of Proposed Rulemaking (NPRM), which is that
analysis of crystalline silica samples must conform with the
requirements listed in the rule (i.e., in Appendix A), and that can
only be determined by knowing the identity of the laboratory that
performed the analysis.
Fann Contracting, Inc. commented that OSHA's proposed rule would
create a "recordkeeping nightmare" and raised concerns about the
difficulties of managing air monitoring data for over 200 employees
scattered around the state, with 7 to 8 ongoing projects and 12 to 15
total projects per year (Document ID 2116, Attachment 1, p. 11). The
American Subcontractors Association expressed concerns about the high
costs of transferring data to new technology or keeping records in
paper format (Document ID 2187, p. 7).
OSHA understands that, as with any recordkeeping requirement in a
comparable rule, there will be time, effort, and expense involved in
developing and maintaining records. However, OSHA expects that even
employers who manage multiple projects will have a system for
maintaining these records, just as they do for their other business
records. As for high expenses of transferring data to new technology,
the Agency understands that there are multiple ways to maintain these
records and there are expenses involved in doing so. Therefore, the
Agency is allowing employers the option to use whatever method works
best for them, paper or electronic.
Paragraph (k)(1)(iii) of the standard for general industry and
maritime (paragraph (j)(1)(iii) of the standard for construction) is
unchanged from the proposed rule. It requires the employer to ensure
that exposure records are maintained and made available in accordance
with OSHA's access to employee exposure and medical records standard,
which specifies that exposure records must be maintained for 30 years
(29 CFR 1910.1020(d)(i)(ii)). Commenters addressed the issue of how
long an employer should maintain exposure records. The National
Industrial Sand Association (NISA) noted that its occupational health
program requires NISA members to retain employee air monitoring records
indefinitely (Document ID 2195, p. 35). NISA supported the proposed
requirement that air monitoring records be retained for 30 years
(Document ID 2195, p. 46). Other commenters advocated recordkeeping
durations ranging from 10 years to 40 years (e.g., Document ID 2210,
Attachment 1, p. 8; 2319, p. 122; 2339, p. 10; 4025, pp. 8-9). The
American Society of Safety Engineers (ASSE) recommended that air
monitoring records should be retained for 40 years or the duration of
employment plus 20 years, whichever is longer, due to latency periods
of some silica-related illnesses (Document ID 2339, p. 10). The
International Union of Operating Engineers indicated that 10 years is
more than adequate time to retain air monitoring data; it commented
that British Columbia, Canada requires retention for 10 years (Document
ID 4025, pp. 8-9). The Construction Industry Safety Coalition and the
National Federation of Independent Business (NFIB) expressed the view
that 30 years is too long, but did not make recommendations for what
they considered a suitable duration (Document ID 2319, pp. 121-122;
2210, Attachment 1, p. 8). NFIB alleged that employers will have to
maintain and make available records of all activities relating to each
requirement of the rule if the company wants to ensure it can show a
good-faith effort to comply, and indicated that keeping records for 30
years would lead to a "staggering" amount of paperwork
(Document ID 2210, Attachment 1, p. 8).
After reviewing the comments in this record, OSHA has concluded
that the best approach is to maintain consistency with 29 CFR 1910.1020
and its required time period for retention of exposure records of 30
years. OSHA explained in that rulemaking that it is necessary to keep
exposure records for this extended time period because of the long
latency period between exposure and development of silica-related
disease (45 FR 35212, 35268-35271 (5/23/80)). For example, silicosis is
often not detected until 20 years or more after initial exposure. The
extended record retention period is therefore needed because
establishing causality of disease in employees is assisted by, and in
some cases can only be made by, having present and past exposure data
(as well as any objective data relied on by the employer and present
and past medical surveillance records, as discussed below).
In retaining the 30-year retention period, OSHA does not agree with
commenters who recommended extending it to at least 40 years, or even
indefinitely. The Agency concludes that the 30-year retention period
specified in 29 CFR 1910.1020 represents a reasonable balance between
the need to maintain exposure records and the administrative burdens
associated with maintaining those records for extended time periods.
Because the 30-year records-retention requirement is included in 29 CFR
1910.1020, this duration is consistent with longstanding Agency and
employer practice. Other substance-specific rules are also subject to
the retention requirements of 29 CFR 1910.1020, such as the standards
addressing exposure to methylene chloride (29 CFR 1910.1052) and
chromium (VI) (29 CFR 1910.1026). The Agency also disagrees that the
30-year retention requirement will lead to a "staggering" amount of
paperwork, as NFIB commented (Document ID 2210, Attachment 1, p. 8).
Electronic recordkeeping has become commonplace. Commenters such as the
Association of Energy Service Companies and ASSE support the use of
electronic or digital records to ease paperwork burdens (Document ID
2344, p. 2; 2339, p. 5). Thus, OSHA finds that the 30-year retention
period is necessary and appropriate for air monitoring data.
Paragraph (k)(2)(i) of the standard for general industry and
maritime (paragraph (j)(2)(i) of the standard for construction) is
substantively unchanged from the proposed rule. It requires employers
who rely on objective data to keep accurate records of the objective
data. Paragraph (k)(2)(ii) of the standard for general industry and
maritime (paragraph (j)(2)(ii) of the standard for construction)
requires the record to include: The crystalline silica-containing
material in question; the source of the objective data; the testing
protocol and results of testing; a description of the process, task, or
activity on which the objective data were based; and other data
relevant to the process, task, activity, material, or exposures on
which the objective data were based. Paragraphs (k)(2)(ii)(D) and (E)
of the standard for general industry and maritime (paragraphs
(j)(2)(ii)(D) and (E) of the standard for construction) have been
modified from the proposed rule to substitute the word "task" for
"operation" and to clarify the requirements for records of objective
data. These changes are editorial, and do not affect the employer's
obligations as set forth in the proposed rule.
Since the rule allows objective data to be used to exempt the
employer from monitoring requirements and to provide a basis for
selection of respirators, OSHA considers it critical that the use of
objective data be documented. As authorized in the rule, reliance on
objective data is intended to provide the same degree of assurance that
employer monitoring of employee exposures by taking air samples does.
The specified content elements are required to ensure that the records
are capable of demonstrating to OSHA a reasonable basis for the
conclusions drawn by the employer from the objective data.
OSHA considers objective data to be employee exposure records that
must be maintained. Paragraph (k)(2)(iii) of the standard for general
industry and maritime (paragraph (j)(2)(iii) of the standard for
construction) is unchanged from the proposed rule. It requires the
employer to ensure that objective data are maintained and made
available for 30 years in accordance with 29 CFR 1910.1020(d)(1)(ii)).
The National Asphalt Pavement Association recommended that OSHA
clarify that "...for an operation provided the controls outlined in
Table 1, no further records of objective data would be required"
(Document ID 2181, p. 13). OSHA confirms that an employer who fully and
properly implements the control measures in Table 1 does not need to
have objective data since no exposure assessment (including those based
on objective data) is required when the employer is following Table 1.
Therefore, following Table 1 does not trigger a recordkeeping or
retention requirement.
Associated Builders and Contractors, Inc. (ABC) and ASSE addressed
the issue of retaining objective data records for 30 years (Document ID
2289, p. 8; 2339, p. 10). ABC expressed concerns that data could be
lost or destroyed during the 30-year period, and thought it would be
difficult to enforce this provision. Furthermore, it commented that
there is a "...large and burdensome amount of records that an
employer would need to store and maintain" (Document ID 2289, p. 8).
ABC did not make a recommendation on how long employers should maintain
objective data records. ASSE commented that 30 years is too short and
recommended that objective data records be retained for 40 years or the
duration of the employment plus 20 years, whichever is longer, due to
latency periods of some silica-related illnesses (Document ID 2339, p.
10). For the same reasons noted in the explanation above for retaining
air monitoring data pursuant to paragraph (k)(1)(iii) of the standard
for general industry and maritime (paragraph (j)(1)(iii) of the
standard for construction), OSHA finds that the 30-year retention
period is necessary and appropriate for objective data.
Paragraph (k)(3)(i) of the standard for general industry and
maritime (paragraph (j)(3)(i) of the standard for construction)
requires the employer to make and maintain an accurate record for each
employee subject to medical surveillance under paragraph (i) of the
standard for general industry and maritime (paragraph (h) of the
standard for construction). Paragraph (k)(3)(ii) of the standard for
general industry and maritime (paragraph (j)(3)(ii) of the standard for
construction) lists the categories of information that an employer is
required to record: The name and social security number of the
employee; a copy of the PLHCPs' and specialists' written medical
opinions for the employer; and a copy of the information provided to
the PLHCPs and specialists where required by paragraph (i)(4) of the
standard for general industry and maritime (paragraph (h)(4) of the
standard for construction). The information provided to the PLHCPs and
specialists includes the employee's duties as they relate to
crystalline silica exposure, crystalline silica exposure levels,
descriptions of personal protective equipment used by the employee, and
information from employment-related medical examinations previously
provided to the employee (paragraph (i)(4) of the standard for general
industry and maritime, paragraph (h)(4) of the standard for construction).
In paragraph (k)(3)(ii)(B) of the standard for general industry and
maritime (paragraph (j)(3)(ii)(B) of the standard for construction),
OSHA has changed the "PLHCP's and pulmonary specialist's written
opinions" to the "PLHCPs' and specialists' written medical
opinions." The change, consistent with paragraph (i) of the standard
for general industry and maritime (paragraph (h) of the standard for
construction), is made to reflect the revised definition for the term
"specialist" included in the rule.
Paragraph (k)(3)(iii) of the standard for general industry and
maritime (paragraph (j)(3)(iii) of the standard for construction) is
unchanged from the proposed rule. It requires that medical records must
be maintained for at least the duration of employment plus 30 years in
accordance with 29 CFR 1910.1020(d)(1)(i), which governs application of
the retention requirements in this rule. Pursuant to 29 CFR
1910.1020(d)(1)(i)(C), medical records of employees who have worked for
less than one year for the employer need not be retained beyond the
term of employment if they are provided to the employee upon the
termination of employment. This exception allows employers flexibility
and the option not to retain medical records in these circumstances (53
FR 38140, 38153-38155 (9/29/88)). This provision greatly reduces the
recordkeeping burden on employers of short-term employees, including
many construction employees covered by this rule. Of course, neither
this rule nor 29 CFR 1910.1020 prohibits employers from keeping the
medical records of employees who worked less than one year, and some
employers may choose to keep the records. As indicated earlier,
employers have the option to keep records in electronic or paper form.
The employer is responsible for the maintenance of records in his
or her possession (e.g., the PLHCP's written medical opinion for the
employer described in paragraph (i)(6) of the standard for general
industry and maritime (paragraph (h)(6) of the standard for
construction)). The employer is also responsible for ensuring the
retention of records in the possession of the PLHCP (e.g., the written
medical report for the employee described in paragraph (i)(5) of the
standard for general industry and maritime (paragraph (h)(5) of the
standard for construction)) that are created pursuant to this rule's
medical surveillance requirements. This responsibility, which derives
from 29 CFR 1910.1020(b), means that employers must ensure that the
PLHCP retains a copy of medical records for the employee's duration of
employment plus 30 years. The employer can generally fulfill this
obligation by including the retention requirement in the agreement
between the employer and the PLHCP.
Commenters objecting to the recordkeeping requirements for medical
records were concerned with privacy and costs. OSCO Industries asserted
that the medical recordkeeping provisions would be subject to the
Health Insurance Portability and Accountability Act (HIPAA), and thus
employers would be denied access to the records (Document ID 1992, p.
12). The National Electrical Contractors Association (NECA) also
expressed concerns about the application of HIPAA (Document ID 2295, p.
2). NECA indicated that the recordkeeping requirements would "...
inundate most businesses with paperwork..." and would be "...an
economic burden to employers in the construction industry..."
(Document ID 2295, p. 2). Fann Contracting and Leading Builders of
America said that medical records would be very expensive and difficult
to maintain (Document ID 2116, Attachment 1, p. 11; 2269, p. 19). Fann
Contracting commented that they have multiple projects, as many as 7 to
8 ongoing and 12 to 15 per year, with over 200 employees scattered
around the state, which makes the new requirements "a recordkeeping
nightmare" (Document ID 2116, Attachment 1, p. 11).
As to the expense and difficulty of maintaining the medical
records, OSHA recognizes that there will be time, effort, and expense
involved in maintaining medical records. However, as stated earlier,
OSHA expects that employers who manage multiple projects will have a
system for maintaining these records, just as they do for their other
business records. The adverse health effects associated with
crystalline silica are very serious, and OSHA has concluded that the
recordkeeping requirements are necessary to ensure that records are
available to assist PLHCPs in identifying health conditions that may
place employees at increased risk from exposure, as well as identifying
and treating adverse health effects that may develop among employees.
Therefore, OSHA concludes that the requirements for making and
maintaining medical records are reasonable, and are essential for the
health and safety of employees.
As to the concerns expressed regarding the application of HIPAA,
the requirement for retention of medical records in this standard (like
those in other OSHA standards) is consistent with HIPAA. HIPAA allows
for disclosure of certain health information to an employer where
needed to comply with OSHA requirements for medical surveillance (45
CFR 164.512). Moreover, this standard's requirement that medical
surveillance reports be provided to workers rather than to employers
eliminates much of this concern.
Morgan Electro Ceramics, NECP, Southern Company, NTCA, Dow
Chemical, ARMA, API, the Marcellus Shale Coalition, Ameren, NAIMA, EEI,
TCNA, AFS, NMA, NM and others also questioned the requirement that the
employee's social security number be included in medical records
(Document ID 1772, p. 1; 1785, pp. 9-10; 2185, pp. 8; 2267, p. 7; 2270,
p. 3; 2291, p. 26; 2301, Attachment 1, pp. 80-81; 2311, p. 3; 2315, p.
7; 2348, Attachment 1, p. 39; 2357, pp. 36-37; 2363, p. 7; and 2379,
Appendix 1, p. 73; 2107, p. 4; 1963, p. 3).
As noted above in the discussion on air monitoring data, OSHA finds
the privacy and security issues associated with the required use of
social security numbers are of concern. However, for the same reasons
discussed above with regard to employee exposure records, the Agency
has decided to retain the requirement for use of social security
numbers in medical records. As stated above, OSHA intends separately
from this rulemaking to examine the requirements for social security
numbers in all of its substance-specific health standards in order to
address the issue comprehensively and ensure consistency among
standards.
In total, the recordkeeping requirements fulfill the purposes of
Section 8(c) of the OSH Act, and help protect employees because such
records contribute to the evaluation of employees' health and enable
employees and their healthcare providers to make informed health care
decisions. These records are especially important when an employee's
medical condition places him or her at increased risk of health
impairment from further exposure to respirable crystalline silica.
Furthermore, the records can be used by the Agency and others to
identify illnesses and deaths that may be attributable to respirable
crystalline silica exposure, evaluate compliance programs, and assess
the efficacy of the standard. OSHA concludes that medical surveillance
records, like exposure records, are necessary and appropriate for
protection of employee health, enforcement of the standard, and
development of information regarding the causes and prevention of
occupational illnesses.
Commenters, such as NISA and ASSE, addressed the issue of duration
of retention of medical records (Document ID 2339, p. 10; 2195, p. 35).
NISA indicated that 30 years is an appropriate retention period
(Document ID 2195, p. 35). ASSE indicated that medical records should
be retained for 40 years or the duration of the employment plus 20
years, whichever is longer, due to latency periods of some silica-
related illnesses (Document ID 2339, p. 10).
As with exposure records and objective data records, OSHA has
concluded that the best approach is to maintain consistency with 29 CFR
1910.1020 and its required retention period for medical records; that
period is the duration of employment plus 30 years. It is necessary to
keep medical records for this extended time period because of the long
latency period between exposure and development of silica-related
disease (45 FR at 35268-35271). OSHA recognizes that in some cases, the
latency period for silica-related diseases may extend beyond 30 years.
However, the Agency concludes that the retention period specified in 29
CFR 1910.1020 represents a reasonable balance between the need to
maintain records and the administrative burdens associated with
maintaining those records for extended time periods. Because the
duration of employment plus the 30-year records retention requirement
is currently included in 29 CFR 1910.1020, this time period is
consistent with longstanding Agency and employer practice.
Charles Gordon, a retired occupational safety and health attorney,
advocated for a provision for trade associations, unions, and medical
practices to provide medical exams and keep medical records (Document
ID 2163, Testimony 1, p. 14). After considering this suggestion, OSHA
decided not to incorporate it into the rule. OSHA anticipates that, in
some cases, employers may be able to work with unions or trade
associations to ensure that medical examinations are provided that meet
the requirements of the rule, and that records are maintained. However,
in many cases, unions and trade associations will not be available to
provide such services. And in any case, the employer is ultimately
responsible for ensuring that medical examinations are provided in
accordance with the rule. Consistent with OSHA's access to employee
exposure and medical records standard (29 CFR 1910.1020), the rule
therefore requires the employer to maintain such records, and the
employer must ensure the PLHCP retains the medical records for the
employee's duration of employment plus 30 years. As stated earlier, the
employer can generally fulfill this obligation by including the
retention requirement in the contractual agreement between the employer
and the PLHCP.
Commenters such as the International Union of Bricklayers and
Allied Craftworkers (BAC) and ASSE stated that records should be made
available to the employee and the employee's designated
representative(s), at the request of the employee (e.g., Document ID
2329, p. 8; 2339, p. 5). OSHA agrees, and employees and their
representatives are permitted to obtain a copy of exposure and medical
records pursuant to 29 CFR 1910.1020(e)(iii).
Commenters such as the Building and Construction Trades Department,
AFL-CIO (BCTD) and BAC requested the addition of a provision for
retaining training records in the rule (e.g., Document ID 2371,
Attachment 1, p. 50; 2329, p. 8). BAC recommended that employers in the
construction industry could use a portable training management system
that is designed to track employees' training throughout their career
(Document ID 4053, Attachment 1 and Exhibit 2). To keep track of
training records, BCTD recommended that employers could use the same
portable training management system recommended by BAC or use a
portable database, as described in a report by the Mount Sinai Irving
J. Selikoff Center for Occupational and Environmental Medicine
(Document ID 4223, p. 126; 4073, Attachment 2b).
OSHA is not including a provision for retaining training records in
the rule because the Agency has concluded that requiring such records
is not necessary. The performance-oriented requirements for training in
paragraph (j) of the standard for general industry and maritime
(paragraph (i) of the standard for construction) specify that employees
must be able to demonstrate knowledge of the health hazards associated
with exposure to respirable crystalline silica; tasks that could result
in exposure; procedures to protect employees from exposure; as well as
the silica standard and the medical surveillance program it requires.
These requirements will be sufficient to ensure that employees are
adequately trained with regard to recognizing silica hazards and taking
protective measures. Moreover, adding a provision for retention of
training records would involve additional paperwork burdens for
employers. The absence of a requirement for retention of training
records in the rule is consistent with OSHA's hazard communication
standard (29 CFR 1910.1200), addressing training for all hazardous
chemicals, as well as the most recent OSHA substance-specific health
standards, addressing exposure to 1,3-butadiene (29 CFR 1910.1051),
methylene chloride (29 CFR 1910.1052), and chromium (VI) (29 CFR
1910.1026).
The recordkeeping requirements of the rule are also generally
consistent with the recordkeeping provisions of the industry consensus
standards, ASTM E 1132-06, Standard Practice for Health Requirements
Relating to Occupational Exposure to Respirable Crystalline Silica and
ASTM E 2625-09, Standard Practice for Controlling Occupational Exposure
to Respirable Crystalline Silica for Construction and Demolition
Activities. The main substantive differences are related to the use of
social security numbers and duration of retention of records. ASTM E
1132-06 and ASTM E 2625-09 specify that the employer should include an
identification number for each employee monitored for dust exposure,
but do not indicate that the number must be a social security number,
whereas OSHA's rule requires the employer to include the employee's
social security number. As noted above, although OSHA intends to
reconsider this policy for all standards in a future rulemaking, the
Agency has determined that the use of social security numbers is
appropriate for this rule. ASTM E 1132-06 specifies that medical and
exposure records should be retained for 40 years or the duration of
employment plus 20 years, whichever is longer. ASTM E 2625-09 does not
specify a duration for retaining exposure or medical records. OSHA has
determined that the retention requirements of 29 CFR 1910.1020 are
appropriate for exposure and medical records collected under this rule,
because the requirements represent a reasonable balance between the
need to maintain records and the administrative burdens associated with
maintaining those records, and are consistent with longstanding
practice by the Agency with which employers are familiar and to which
they are accustomed; changing the duration of retention requirement for
this one rule could therefore cause confusion.
Dates
Paragraph (l) of the standard for general industry and maritime
(paragraph (k) of the standard for construction) sets forth the
effective date of the standard and the date(s) for compliance with the
requirements of the standard. OSHA proposed identical requirements for
both standards: An effective date 60 days after publication of the rule;
a date for compliance with all provisions except engineering controls
and laboratory requirements of 180 days after the effective date; a date
for compliance with engineering controls requirements, which was one year
after the effective date; and a date for compliance with laboratory
requirements of two years after the effective date.
The United Steelworkers supported the proposed effective and start-
up dates, arguing that they provide adequate time for employers to come
into compliance with the rule (Document ID 2336, p. 16). Employers and
industry representatives such as the American Exploration and
Production Council, the Tile Council of North America, and Ameren
requested that the effective date of the rule be extended (e.g.,
Document ID 2147, p. 2; 2267, p. 7; 2315, p. 4; 2375, Attachment 1, p.
3; 2363 p. 7).
OSHA sets the effective date to allow sufficient time for employers
to obtain the standard, read and understand its requirements, and
undertake the necessary planning and preparation for compliance.
Section 6(b)(4) of the OSH Act allows the effective date of a standard
to be delayed for up to 90 days from the date of publication in the
Federal Register. Given the requests by commenters, OSHA's interest in
having employers implement effective compliance efforts, and the
minimal effect of an additional 30 day delay, the Agency has decided
that it is appropriate to set the effective date at 90 days from
publication, rather than at 60 days. Accordingly, the rule will become
effective 90 days after publication in the Federal Register.
Paragraphs (l)(2), (3) and (4) of the standard for general industry
and maritime (paragraphs (k)(2) and (3) of the standard for
construction) establish dates for compliance with the requirements of
the standard. Employers and industry representatives such as the
American Petroleum Institute, the National Industrial Sand Association,
Dow Chemical Company, the Glass Association of North America (GANA),
and the American Foundry Society (AFS) contended that substantially
more time was needed to implement engineering controls than the one
year from the effective date that had been proposed (e.g., Document ID
2195, pp. 8, 22; 2147, p. 1; 2267, p. 3; 2149, p. 2; 2277, p. 1; 1992,
pp. 4, 12; 2023, p. 4; 2315 pp. 4, 9; 2137; 2047; 2215, p. 10; 2311, p.
3; 2291, p. 16; 2105. p. 1; 2348, Attachment 1, p. 40; 2357, p. 18;
2365, pp. 10-22; 2301, Attachment 1, pp. 64, 82; 2302, p. 9; 2327,
Attachment 1; 2270, p. 1; 2279, pp. 6, 11; 2290, pp. 3-4; 2296, p. 36;
2384, p. 6; 2493, p. 5; 2379, Appendix 1, pp. 22, 73-74; 2544, p. 11).
General industry employers and trade associations were concerned
with the length of time needed for the design, approval, and
installation of engineering controls. For example, the AFS provided
examples of how implementation of engineering controls could take
longer than one year for foundries:
The proposed compliance period fails to account for the
substantial time required for a comprehensive engineering evaluation
of the overall silica exposure at the facility and the design of a
proposed engineering control system. The engineering phase alone for
a 10,000 cfm or larger system typically takes 4 to 6 months--longer
for large or complex exposure problems. This issue is further
complicated by the fact that the current national economy has
substantially reduced the number of firms offering these
environmental services, and all of the affected foundries will be
competing for these limited services. The compliance period also
fails to take into effect the fact that to attempt to meet the
proposed PEL with local exhaust ventilation would require custom
control equipment (primarily baghouses) which are not stock items
and are custom built for each application. These control systems
typically require a minimum of 2 to 4 months for manufacture after
the completion of the engineering specifications and submission of
an order. This period is significantly longer for specialized or
large orders (Document ID 2379, Attachment B, p. 37).
Another issue raised by general industry representatives and
employers such as Morgan Electro Ceramics, the Asphalt Roofing
Manufacturers Association, the Fertilizer Institute, and the National
Association of Manufacturers, was the potential length of time involved
in environmental permitting processes (e.g., Document ID 1772, p. 1;
1992, Attachment 1, p. 4; 2291, Attachment 1, pp. 16-17; 3487, pp. 26-
27; 3492, Attachment 1, pp. 5-6; 3584, Tr. 2845; 2290, Attachment 1, p.
3; 2380, Attachment 2, p. 20). The AFS testified on the permitting
issue:
Because many of the controls involve additions or changes to
ventilation systems, OSHA must recognize the additional time
required for modelling and permitting by state or federal EPA
authorities. The proposed one year compliance period is totally
unrealistic. In some states, the mandatory permitting requirement
for both new and modified systems requires up to 18 months, and this
does not include the design and modelling work necessary to prepare
the permit application, or the construction and installation time
after approval. For foundries which have a Title V permit, the
approval includes an additional time period for the US EPA to review
and make comments, and if the facility is subject to the federal
Prevention of Significant Deterioration (PSD) or Lowest Achievable
Emission Rate (LAER) rules the permit approval can take an
additional 6 to 18 months for the detailed review and approval
necessary (Document ID 3487, p. 26).
OSHA is persuaded that the concerns expressed by commenters
regarding the time needed to implement engineering controls are
reasonable, and is extending the compliance deadline for general
industry and maritime to allow two years from the effective date for
employers to comply with the standard. In extending the proposed
compliance date for engineering controls in the general industry and
maritime standard by one year, OSHA has concluded that engineering
controls can be implemented within two years of the effective date in
most general industry and maritime workplaces. However, because permit
requirements and application processes vary by jurisdiction, OSHA is
willing to use its enforcement discretion in situations where an
employer can show it has made good faith efforts to implement
engineering controls, but has been unable to implement such controls
due to the time needed for environmental permitting.
OSHA understands that some general industry employers may face
difficulties in implementing engineering controls due to continuous
operation of facilities in particular industries. Trade associations
such as the North American Insulation Manufacturers Association (NAIMA)
and the GANA noted that their industries have plants that run
constantly and shut down only on rare occasions, making installation of
engineering controls, which would require a shutdown, unusually
difficult and expensive (e.g., Document ID 2348, Attachment 1, p. 40;
2215, Attachment 1, p. 10). OSHA is willing to provide latitude and
work with such employers on an individual basis to schedule
implementation of engineering controls during shutdowns, provided they
are working in good faith toward compliance and that they provide and
assure employees use appropriate respirators until engineering controls
are installed.
Paragraph (l)(3)(ii) of the standard for general industry and
maritime allows five years from the effective date--four years more
than the proposed standard--for employers to comply with obligations
for engineering controls in hydraulic fracturing operations in the
oil and gas industry. Additional time is provided to implement
engineering controls in this industry to allow employers to take
advantage of further development of emerging technologies discussed in
Chapter IV of the Final Economic Analysis and Final Regulatory
Flexibility Analysis (FEA). Paragraph (l)(3)(iii) specifies that
obligations for medical surveillance in paragraph (i)(l)(i) commence in
accordance with paragraph (l)(4) for hydraulic fracturing operations in
the oil and gas industry. Paragraph (l)(4) is discussed below.
Paragraph (k)(2) of the standard for construction allows one year
after the effective date to come into compliance with all obligations
other than the requirements for methods of sample analysis. This
extends the time (one year compared to 180 days) for compliance with
the standard's ancillary provisions and retains the one year period
after the effective date for engineering controls. Commenting on the
proposed compliance dates for construction work, several stakeholders
raised issues that might impact the ability of employers to implement
engineering controls within one year after the effective date (e.g.,
Document ID 2296, Attachment 1, p. 36; 2357, p. 18). OSHA expects that
the vast majority of construction employers will choose to implement
the controls specified in paragraph (c) of the construction standard.
These controls are generally commercial products that are readily
available and can be purchased and put into use in a very short period
of time. For the limited number of construction tasks that require more
sophisticated controls (e.g., enclosed cabs on heavy equipment used
during the demolition of concrete or masonry structures), the controls
are already either commonly in use or could be implemented within one
year. Moreover, by implementing the controls specified in paragraph (c)
of the construction standard, employers will not be required to assess
employee exposures to respirable crystalline silica, so no time will be
needed for assessing employee exposures prior to implementing
engineering controls. OSHA finds that the ready availability of
engineering controls for construction will enable construction
employers to implement engineering controls within one year of the
effective date, and the Agency is therefore requiring that construction
employers implement engineering controls required by the standard
within one year of the effective date.
In requiring that general industry and maritime employers comply
with most obligations of the standard two years after the effective
date, and in requiring that construction employers comply with all
ancillary and engineering controls one year after the effective date,
OSHA has aligned the compliance dates for other provisions of the
standards with the compliance dates for engineering controls. This will
allow employers to focus their efforts on implementation of engineering
controls. OSHA decided that staggering the compliance dates for some
provisions of the rule could serve to divert attention and resources
away from the implementation of engineering controls. For example, if
respiratory protection were to be required six months after the
effective date (as OSHA proposed), employers would need to assess
employee exposures, and would need to develop a respiratory protection
program and provide appropriate respirators to employees exposed above
the PEL, while simultaneously working to implement engineering
controls. A requirement for respiratory protection prior to
implementation of engineering controls would be particularly
problematic where construction employers implement the controls
specified in paragraph (c) of the construction standard. This is
because those employers would not otherwise be required to assess
employee exposures.
In determining the compliance dates for provisions other than
engineering controls, OSHA considered the relatively short time period
before engineering controls must be implemented in construction work.
The Agency recognizes the longer time period allowed for general
industry and maritime employers to implement engineering controls.
However, general industry employers must comply with a PEL that is
approximately equivalent to 100 [mu]g/m\3\ during the period before
compliance with the revised PEL of 50 [mu]g/m\3\ is required, whereas
construction work will be subject to a higher PEL of approximately 250
[mu]g/m\3\. The lower PEL of approximately 100 [mu]g/m\3\ that will
apply to general industry will mitigate respirable crystalline silica
exposures in this sector to some extent during the interim period.
Moreover, because employers will be using this time to implement
engineering controls, OSHA expects that exposures will continue to
decline during this period. Construction will continue to be subject to
the higher PEL of approximately 250 [mu]g/m\3\ during this interim, but
that period will only be one year from the effective date, compared to
two years from the effective date for general industry and maritime.
OSHA finds that establishing consistent compliance dates for
engineering controls and other provisions of the standards is less
confusing, more practical, and will better enable employers to focus
their time and resources on implementing the control measures that will
best protect employees. For hydraulic fracturing operations in the oil
and gas industry, OSHA is providing an extra three years--a total of
five years from the effective date--for employers to implement
engineering controls for hydraulic fracturing operations. During these
additional three years, employers must comply with all other
requirements of the standard, including requirements for respiratory
protection to protect employees exposed to respirable crystalline
silica at levels that exceed the revised PEL of 50 [mu]g/m\3\.
The issue of how much time to allow for laboratories to come into
compliance with respect to methods of sample analysis received
considerable comment during the rulemaking. Employers and trade and
professional associations such as the National Tile Contractors
Association, the Fertilizer Institute, OSCO Industries, Edison Electric
Institute, and Fann Contracting, Inc. expressed concerns about the
proposed rule's provisions that gave all employers one year to
implement engineering controls and allowed two years before employers
would be required to follow requirements for methods of sample analysis
(e.g., Document ID 2267, pp. 6-7; 2149, p. 2; 1992, pp. 10, 12; 2179,
p. 3; 2312, p. 2; 2317, p. 2; 2314, p. 3; 2357, pp. 18-19; 2365, p. 22;
2116, Attachment 1, p. 48; 2327, p. 29; 2368, p. 3; 2379, Attachment B,
p. 37; 3398, pp. 1-2; 3487, p. 27; 3491, p. 5; 2363, p. 6). For
example, Andy Fulton of ME Global stated:
OSHA is giving laboratories 2 years to improve their procedures
for accurate silica analysis. However, OSHA is requiring foundries
to install expensive engineering controls within one year, before
accurate exposure levels are available. This does not make sense,
especially when it could involve millions of dollars (Document ID
2149, p. 2).
In proposing to require employers to implement engineering controls
and comply with other provisions of the rule before the laboratory
requirements came into effect, OSHA intended to allow time for
laboratory capacity to develop. As indicated in Chapter IV of the FEA,
OSHA finds that it is feasible to measure exposures to respirable
crystalline silica at the revised PEL and action level with a
reasonable degree of accuracy and precision using methods that are
currently available. Many laboratories are capable of analyzing samples
in accordance with the laboratory requirements of the silica rule; OSHA
encourages employers to follow these requirements prior to the time
that they are mandated. There are approximately 40 laboratories that
are accredited by AIHA Laboratory Accreditation Programs for the
analysis of crystalline silica (Document ID 3586, Tr. 3284). These
laboratories are already capable of analyzing samples in accordance
with the laboratory requirements of the silica rule.
OSHA anticipates that the additional demand for respirable
crystalline silica exposure monitoring and associated laboratory
analysis with the rule will be modest. Most construction employers are
expected to implement the specified exposure control measures in
paragraph (c) of the construction standard, and will therefore not be
required to assess employee exposures, thus placing no demands on
laboratories. The performance option for exposure assessment provided
in both the general industry and maritime standard at paragraph (d)(2)
and the construction standard at paragraph (d)(2)(ii) also serves to
lessen the anticipated volume of exposure monitoring. The additional
time allowed for compliance with the general industry and maritime
standard further serves to diminish concerns about laboratory capacity
by providing additional time for laboratory capacity to increase and
distributing demand for sample analysis over an extended period of
time. OSHA therefore concludes that the compliance date for methods of
sample analysis of two years after the effective date is reasonable in
both the general industry/maritime and construction standards. OSHA
also anticipates that construction employers who perform air monitoring
before the laboratory requirements go into effect (see paragraph (k)(3)
of the construction standard) will be able to obtain reliable
measurements of their employees' exposures to respirable crystalline
silica.
Paragraph (l)(4) of the standard for general industry and maritime
specifies that obligations in paragraph (i)(1)(i) regarding medical
surveillance take effect for employees who will be occupationally
exposed to respirable crystalline silica above the PEL for 30 or more
days per year beginning two years after the effective date. Obligations
in paragraph (i)(l)(i) for employees who will be occupationally exposed
to respirable crystalline silica at or above the action level (but at
or below the PEL) for 30 or more days per year will commence four years
after the effective date. In other words, medical surveillance will be
triggered by exposures above the PEL for 30 or more days per year,
beginning two years after the effective date and continuing through
four years after the effective date, and will then be triggered by
exposures at or above the action level for 30 or more days per year
beginning four years after the effective date. As indicated in the
Summary and Explanation for Medical Surveillance, this approach focuses
initial medical surveillance efforts on those employees who are at
greatest risk, while giving most employers additional time to fully
evaluate the engineering controls they have implemented in order to
determine which employees meet the action level trigger for medical
surveillance.
Commenters such as NAIMA and the National Concrete Masonry
Association voiced concerns about the proposed rule's effects on small
businesses, and asked for compliance extensions for small businesses
(e.g., Document ID 2348, Attachment 1, p. 41; 2279, Attachment 1, p.
10). OSHA has considered these concerns, and has found that the
compliance dates set forth in this section are reasonable for employers
of all sizes. Therefore, OSHA has not created exceptions extending the
compliance period for specific business classes or sizes.
OSHA also considered comments from the U.S. Chamber of Commerce and
the National Stone, Sand, and Gravel Association, among others,
expressing concern that the rule would create increased demand for
health and safety professionals and for medical professionals; they
alleged there are not enough professionals in those fields to service
the demand that would be created by the rule (e.g., Document ID 2365,
Attachment 1, p. 10; 2237, Attachment 1, p. 4; 3578, Tr. 1127). The
Agency does not find these arguments convincing. Most of the provisions
of the rule do not generally require the involvement of a health or
safety professional, or require only limited oversight from a health or
safety professional. For example, exposure monitoring does not need to
be performed by certified industrial hygienists; technicians and other
trained employees can perform this task. Employer compliance with the
specified exposure control methods in paragraph (c) of the construction
standard can generally be accomplished without the involvement of a
health or safety professional. Compliance with other obligations, such
as housekeeping and training requirements, can also be achieved without
the involvement of a health or safety professional or with minimal
oversight from them. There are a sufficient number of medical
professionals available for employers to implement the medical
surveillance provisions of the rule. The availability of medical
professionals is confirmed and discussed in detail in the summary and
explanation of Medical Surveillance in this preamble. Therefore, the
Agency finds no evidence in the record that a shortage of available
health and safety professionals, or a shortage of medical
professionals, will preclude employers from complying with the rule by
the dates set forth in this paragraph.
Thus, the effect of changes made to the proposed rule is that: (1)
All obligations (i.e., exposure assessment and other ancillary
provisions, engineering controls) for general industry and maritime
employers (other than hydraulic fracturing operations in the oil and
gas industry and an action level trigger for medical surveillance for
all general industry and maritime employers) will become enforceable
two years after the 90-day effective date of the rule; (2) all
obligations for hydraulic fracturing operations in the oil and gas
industry (except obligations for engineering controls and an action
level trigger for medical surveillance) will become enforceable two
years after the 90-day effective date; (3) obligations for engineering
controls for hydraulic fracturing operations in the oil and gas
industry will become enforceable five years after the 90-day effective
date; (4) obligations for an action level trigger for medical
surveillance in the standard for general industry and maritime,
including hydraulic fracturing operations in the oil and gas industry,
will become enforceable four years after the 90-day effective date; (5)
all obligations (other than requirements for methods of sample
analysis) for construction employers will become enforceable one year
after the 90-day effective date; and (6) requirements for methods of
sample analysis, applicable to laboratories covered by paragraph
(d)(2)(v) of the standard for construction, become enforceable two
years after the effective date, i.e., one year after the other
requirements in the construction standard and on the same date as all
obligations in general industry and maritime (other than hydraulic
fracturing).
Appendix A to Sec. 1910.1053 and Sec. 1926.1153--Methods of Sample
Analysis
Appendix A, which specifies methods of sample analysis, is included
as part of each standard, 29 CFR 1910.1053 and 29 CFR 1926.1153.
Employers must ensure that all samples taken to satisfy monitoring
requirements of the standards are evaluated by a laboratory that
analyzes air samples for respirable crystalline silica in accordance
with the procedures in Appendix A (paragraph (d)(5) of the standard for
general industry and maritime and paragraph (d)(2)(v) of the standard for
construction).
OSHA proposed analysis requirements that it had included as part of
paragraph (d) of both standards. The Southern Company recommended that
OSHA require use of accredited laboratories and move all other
laboratory requirements to an Appendix as a guide for laboratories that
analyze silica samples (Document ID 2185, p. 7).
OSHA has retained the substance of the proposed provisions
addressing analysis of samples, but has moved these provisions to a new
appendix in each standard. The Agency has decided that segregating
these specifications in an appendix to each final standard provides
greater clarity for both employers and the laboratories that analyze
samples.
Appendix A specifies procedures for the laboratories conducting the
analysis, but employers must ensure samples taken to satisfy the
monitoring requirements of the standard are analyzed by an accredited
laboratory using the methods and quality control procedures described
in this Appendix. Putting the requirements in a separate appendix,
rather than in the regulatory text, facilitates the communication of
these requirements to the laboratory analyzing samples. The appendix
approach is also meant to clarify that an employer who engages a
laboratory to analyze respirable crystalline silica samples may rely on
an assurance from that laboratory that the specified requirements were
met. For example, the laboratory could include a statement that it
complied with the requirements of the standard along with the sampling
results provided to the employer, or the employer could obtain the
information from the laboratory or industrial hygiene service provider.
Appendix A to the final standards describes the specific analytical
methods to be used, as well as the qualifications of the laboratories
at which the samples are analyzed. As discussed in greater detail in
Chapter IV of the Final Economic Analysis and Final Regulatory
Flexibility Analysis (FEA), the sampling and analysis methods required
by the rule are technologically feasible in that they are widely used
and accepted as the best available methods for measuring individual
exposures to respirable crystalline silica. The Agency has determined
that the provisions in Appendix A are needed to ensure the accuracy of
monitoring required by the rule to measure employee exposures.
OSHA has typically included specifications for the accuracy of
exposure monitoring methods in substance-specific standards, but has
not always specified the analytical methods to be used or the
qualifications of the laboratory that analyzes the samples. Exceptions
are the asbestos standards for general industry (29 CFR 1910.1001,
Appendix A) and construction (29 CFR 1926.1101, Appendix A), which
specify the sampling and analytical methods to be used, as well as
quality control procedures to be implemented by laboratories.
Consistent with the evaluation of sampling and analysis methods in
the FEA, under the Appendix (A.1), all samples taken to satisfy the
monitoring requirements of this section must be evaluated using the
procedures specified in one of the following analytical methods: OSHA
ID-142; NMAM 7500, NMAM 7602; NMAM 7603; MSHA P-2; or MSHA P-7. OSHA
has determined based on inter-laboratory comparisons that laboratory
analysis by either X-ray diffraction (XRD) or infrared (IR)
spectroscopy is required to ensure the accuracy of the monitoring
results. The specified analytical methods are the XRD or IR methods for
analysis of respirable crystalline silica that have been established by
OSHA, NIOSH, or MSHA.
To ensure the accuracy of air sampling data relied on by employers
to achieve compliance with the standard, the standard requires that
employers must have air samples analyzed only at laboratories that meet
requirements listed in A.2 through A.6.3. The requirements were
developed based on recommendations for quality control procedures to
improve agreement in analytical results obtained by laboratories (Eller
et al., 1999, Document ID 1688, pp. 23-24). According to Dr. Rosa Key-
Schwartz, NIOSH's expert in crystalline silica analysis, NIOSH worked
closely with AIHA Laboratory Accreditation Programs to implement a
silica emphasis program for site visitors who audit accredited
laboratories to ensure that these quality control procedures are being
followed (Document ID 3579, Tr. 153). As discussed in the FEA, analysis
of recent data from the AIHA Proficiency Analytical Testing (PAT)
program showed that laboratory performance has improved in recent
years, resulting in greater agreement between labs, and this has been
attributed to improvement in quality control procedures (Document ID
3998, Attachment 8; see also Section IV of the FEA).
A.2 requires employers to ensure that samples taken to monitor
employee exposures are analyzed by a laboratory that is accredited to
ANS/ISO/IEC Standard 17025 "General requirements for the competence of
testing and calibration laboratories" (EN ISO/IEC 17025:2005) by an
accrediting organization that can demonstrate compliance with the
requirements of ISO/IEC 17011 "Conformity assessment--General
requirements for accreditation bodies accrediting conformity assessment
bodies" (EN ISO/IEC 17011:2004). ANS/ISO/IEC 17025 is a consensus
standard that was developed by the International Organization for
Standardization and the International Electrotechnical Commission (ISO/
IEC) and approved by the American Society for Testing and Materials
(ASTM). This standard establishes criteria by which laboratories can
demonstrate proficiency in conducting laboratory analysis through the
implementation of quality control measures. To demonstrate competence,
laboratories must implement a quality control (QC) program that
evaluates analytical uncertainty and provides employers with estimates
of sampling and analytical error (SAE) when reporting samples. ISO/IEC
17011 establishes criteria for organizations that accredit laboratories
under ISO/IEC 17025. For example, the AIHA accredits laboratories for
proficiency in the analysis of crystalline silica using criteria based
on the ISO 17025 and other criteria appropriate for the scope of the
accreditation.
Appendix A.3-A.6.3 contain additional quality control procedures
for laboratories that have been demonstrated to improve accuracy and
reliability through inter-laboratory comparisons. The proposed rule
would have required that laboratories participate in a round robin
testing program with at least two other independent laboratories at
least every six months. OSHA deleted this requirement in the final rule
since accredited laboratories must participate in the AIHA PAT program.
The laboratory must use the most current National Institute of
Standards and Technology (NIST) or NIST-traceable standards for
instrument calibration or instrument calibration verification (Appendix
A.3). The laboratory must have an internal quality control (QC) program
that evaluates analytical uncertainty and provides employers with
estimates of sampling and analytical error (Appendix A.4). The
laboratory must characterize the sample material by identifying
polymorphs of respirable crystalline silica present, identifying the
presence of any interfering compounds that might affect the analysis,
and making the corrections necessary in order to obtain accurate sample
analysis (Appendix A.5). The laboratory must analyze quantitatively for
respirable crystalline silica only after confirming that the sample
matrix is free of uncorrectable analytical interferences, and corrects
for analytical interferences (Appendix A.6). The laboratory must
perform routine calibration checks with standards that bracket the
sample concentrations using five or more calibration standard levels to
prepare calibration curves, and use instruments optimized to obtain a
quantitative limit of detection that represents a value no higher than
25 percent of the PEL (Appendix A.6.1-A.6.3).
Several stakeholders commented that requiring employers to analyze
samples for all polymorphs (e.g., quartz, cristobalite, tridymite)
would be unnecessarily burdensome, especially where the employer knows
that some polymorphs are not present in its operations (Document ID
2215, p. 9; 2291, p. 24; 2348, Attachment 1, pp. 33-34; 4213, p. 4;
3588, Tr. 3968). OSHA does not intend for A.5 to require analysis for
all polymorphs for every sample. Employers can consult with their
laboratories or industrial hygiene service providers to determine which
polymorphs are likely to be present in a sample given the nature of the
material and processes employed. For example, if a material used by an
employer is known to contain only quartz, and that material is not
subjected to high temperatures, it is unlikely that cristobalite is
present. Likewise, if prior sampling results failed to find
cristobalite in airborne dust, there would be no need to analyze
samples for cristobalite on a continuing basis. OSHA expects that
laboratories and industrial hygiene service providers will be able to
guide employers on the sample analyses necessary to ensure compliance
with the rule without having to incur unnecessary analytical costs.
Appendix B to Sec. 1910.1053 and Sec. 1926.1153--Medical Surveillance
Appendix B of each standard, 29 CFR 1910.1053 and 29 CFR 1926.1153,
contains medical surveillance guidelines to assist in complying with
the medical surveillance provisions and provides other helpful
recommendations and information. Appendix B is for informational and
guidance purposes only and none of the statements in Appendix B should
be construed as imposing a mandatory requirement on employers that is
not otherwise imposed by the standard. In addition, this appendix is
not intended to detract from any obligation that the rule imposes.
American College of Occupational Medicine (ACOEM), National Institute
for Occupational Safety and Health (NIOSH), American Public Health
Association, and the National Consumers League supported the inclusion
of an appendix for medical surveillance guidelines (Document ID 2080,
p. 2; 2177, Attachment B, p. 41; 2178, Attachment 1, p. 4; 2373, p. 4).
The medical surveillance guidelines were in Appendix A of each
proposed standard but were moved to Appendix B of the final standards,
following the addition of Appendix A for methods of sample analysis.
OSHA received some comments recommending corrections or clarifications
to Appendix B. For example, NIOSH and the National Industrial Sand
Association requested that OSHA update the discussion of digital
radiography to include the most recent International Labour Office
policy, as was done in the preamble, and NIOSH suggested several
clarifications to the discussions on silicosis, specialists and
specialist referrals, and tuberculosis (Document ID 2177, Attachment B,
pp. 41, 48-50; 2195, pp. 44, 46). OSHA considered those comments and
made changes as needed. In addition, OSHA revised Appendix B to make it
consistent with the updates to the rule.
American Federation of Labor and Congress of Industrial
Organizations (AFL-CIO) requested that the appendix discuss medical
confidentiality and provide guidance on information that may be
provided to the employer without the employee's informed consent
(Document ID 4204, p. 90). OSHA agrees that it is important to discuss
this type of information in Appendix B because the information that the
physician or licensed health care professional (PLHCP) is to provide to
the employer under the standards has changed substantially from the
proposal, and Appendix B may serve as the PLHCP's primary source of
information about medical surveillance under the standards. Therefore
OSHA has included a discussion on medical confidentiality. In addition,
OSHA has included examples of the PLHCP's written medical report for
the employee, the PLHCP's written medical opinion for the employer, and
an authorization form to allow limitations on respirable crystalline
silica exposure or recommendations for a specialist examination to be
reported to the employer. OSHA expects the example report, opinion, and
authorization form will greatly clarify the type of information that is
to be reported to the employer.
Some commenters requested that additional information be added to
the appendix. ACOEM, NIOSH and Building and Construction Trades
Department, AFL-CIO requested that the appendix include spirometry
guidelines or reference values (Document ID 2080, p. 9; 2177,
Attachment B, pp. 45-46; 4223, pp. 128-130). Collegium Ramazzini
requested that the appendix include a standardized medical and exposure
history (Document ID 3541, pp. 3, 6). AFL-CIO recommended that the
appendix include a discussion on low dose computed tomography (LDCT)
screening for lung cancer (Document ID, 4204, p. 82). OSHA is not
including the information requested by these commenters in Appendix B
for reasons discussed more fully in the summary and explanation for
Medical Surveillance. OSHA is not including spirometry guidance because
of the widespread availability of useful guidance, including an OSHA
spirometry guidance available through OSHA's Web site. Instead of
including a standardized medical and exposure history form, Appendix B
includes a discussion of the information to be collected as part of a
history that will allow PLHCPs to easily update their current history
forms. Appendix B also does not include a discussion about LDCT
screening for lung cancer because too little is currently known about
the risks and benefits of such screening for employees exposed to
respirable crystalline silica.
List of Subjects in 29 CFR Parts 1910, 1915, and 1926
Cancer, Chemicals, Cristobalite, Crystalline silica, Hazardous
substances, Health, Lung Diseases, Occupational safety and health,
Quartz, Reporting and recordkeeping requirements, Silica, Silicosis,
Tridymite.
Authority and Signature
This document was prepared under the direction of David Michaels,
Ph.D., MPH, Assistant Secretary of Labor for Occupational Safety and
Health, U.S. Department of Labor, 200 Constitution Avenue NW.,
Washington, DC 20210.
The Agency issues the sections under the following authorities:
Sections 4, 6, and 8 of the Occupational Safety and Health Act of 1970
(29 U.S.C. 653, 655, 657); section 107 of the Contract Work Hours and
Safety Standards Act (the Construction Safety Act) (40 U.S.C. 3704);
section 41 of the Longshore and Harbor Worker's Compensation Act
(33 U.S.C. 941); Secretary of Labor's Order 1-2012 (77 FR 3912 (1/25/
2012)); and 29 CFR part 1911.
David Michaels,
Assistant Secretary of Labor for Occupational Safety and Health.
Amendments to Standards
For the reasons set forth in the preamble, 29 CFR parts 1910, 1915,
and 1926, of the Code of Federal Regulations are amended as follows:
PART 1910--OCCUPATIONAL SAFETY AND HEALTH STANDARDS
Subpart Z--[Amended]
0
1. The authority citation for subpart Z of part 1910 is revised to read
as follows:
Authority: Secs. 4, 6, 8 of the Occupational Safety and Health
Act of 1970 (29 U.S.C. 653, 655, 657); Secretary of Labor's Order
No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90
(55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR 50017), 5-2002 (67 FR
65008), 5-2007 (72 FR 31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR
3912), as applicable; and 29 CFR part 1911. All of subpart Z issued
under section 6(b) of the Occupational Safety and Health Act of
1970, except those substances that have exposure limits listed in
Tables Z-1, Z-2, and Z-3 of 29 CFR 1910.1000. The latter were issued
under section 6(a) (29 U.S.C. 655(a)).
Section 1910.1000, Tables Z-1, Z-2 and Z-3 also issued under 5
U.S.C. 553, but not under 29 CFR part 1911 except for the arsenic
(organic compounds), benzene, cotton dust, and chromium (VI)
listings.
Section 1910.1001 also issued under section 107 of the Contract
Work Hours and Safety Standards Act (40 U.S.C. 3704) and 5 U.S.C.
553.
Section 1910.1002 also issued under 5 U.S.C. 553, but not under
29 U.S.C. 655 or 29 CFR part 1911.
Sections 1910.1018, 1910.1029, and 1910.1200 also issued under
29 U.S.C. 653.
Section 1910.1030 also issued under Pub. L. 106-430, 114 Stat.
1901.
Section 1910.1201 also issued under 49 U.S.C. 1801-1819 and 5
U.S.C. 553.
0
2. In Sec. 1910.1000, paragraph (e):
0
a. Amend Table Z-1--Limits on Air Contaminants by:
0
i. Revising the entries for "Silica, crystalline cristobalite,
respirable dust"; "Silica, crystalline quartz, respirable dust";
Silica, crystalline tripoli (as quartz), respirable dust"; and
"Silica, crystalline tridymite, respirable dust"; and
0
ii. Adding footnote 7.
0
b. Amend Table Z-3-Mineral Dusts by:
0
i. Revising the entries for "Silica: Crystalline Quartz
(Respirable)", "Silica: Crystalline Cristobalite", and "Silica:
Crystalline Tridymite";
0
ii. Removing entries in columns 1, 2, and 3 for "Silica: Crystalline
Quartz (Total Dust)" and
0
iii. Adding footnote f.
The revisions and addition read as follows:
Sec. 1910.1000 Air contaminants.
* * * * *
The revisions and addition read as follows:
Sec. 1910.1000 Air contaminants.
* * * * *
Table Z-1--Limits for Air Contaminants
----------------------------------------------------------------------------------------------------------------
Skin
Substance CAS No. (c) ppm(a) \1\ mg/m\3\(b) \1\ designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust
Cristobalite; see 1910.1053 \7\............. 14464-46-1 .............. .............. ..............
Quartz; see 1910.1053 \7\................... 14808-60-7 .............. .............. ..............
Tripoli (as quartz); see 1910.1053 \7\...... 1317-95-9 .............. .............. ..............
Tridymite; see 1910.1053 \7\................ 15468-32-3 .............. .............. ..............
* * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * * * *
\1\ The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit. They are to be
determined from breathing-zone air samples.
(a) Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
(b) Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
listed with a ppm entry, it is approximate.
(c) The CAS number is for information only. Enforcement is based on the substance name. For an entry covering
more than one metal compound, measured as the metal, the CAS number for the metal is given--not CAS numbers
for the individual compounds.
(d) The final benzene standard in 1910.1028 applies to all occupational exposures to benzene except in some
circumstances the distribution and sale of fuels, sealed containers and pipelines, coke production, oil and
gas drilling and production, natural gas processing, and the percentage exclusion for liquid mixtures; for the
excepted subsegments, the benzene limits in Table Z-2 apply. See 1910.1028 for specific circumstances.
(e) This 8-hour TWA applies to respirable dust as measured by a vertical elutriator cotton dust sampler or
equivalent instrument. The time-weighted average applies to the cottom waste processing operations of waste
recycling (sorting, blending, cleaning and willowing) and garnetting. See also 1910.1043 for cotton dust
limits applicable to other sectors.
(f) All inert or nuisance dusts, whether mineral, inorganic, or organic, not listed specifically by substance
name are covered by the Particulates Not Otherwise Regulated (PNOR) limit which is the same as the inert or
nuisance dust limit of Table Z-3.
* * * * * * *
\3\ See Table Z-3.
* * * * * * *
\7\ See Table Z-3 for the exposure limit for any operations or sectors where the exposure limit in Sec.
1910.1053 is stayed or is otherwise not in effect.
* * * * * * *
Table Z-3--Mineral Dusts
------------------------------------------------------------------------
Substance mppcf \a\ mg/m\3\
------------------------------------------------------------------------
Silica: .............. ..............
Crystalline .............. ..............
Quartz (Respirable) \f\............. 250 \b\ 10 mg/m\3\ \e\
%SiO2+5 % SiO2+2
Cristobalite: Use \1/2\ the value .............. ..............
calculated from the count or mass
formulae for quartz \f\
Tridymite: Use \1/2\ the value .............. ..............
calculated from the formulae for quartz
\f\....................................
* * * * * * *
------------------------------------------------------------------------
* * * * * * *
\a\ Millions of particles per cubic foot of air, based on impinger
samples counted by light-field techniques.
\b\ The percentage of crystalline silica in the formula is the amount
determined from airborne samples, except in those instances in which
other methods have been shown to be applicable.
* * * * * * *
\e\ Both concentration and percent quartz for the application of this
limit are to be determined from the fraction passing a size-selector
with the following characteristics:
------------------------------------------------------------------------
Percent passing
Aerodynamic diameter (unit density sphere) selector
------------------------------------------------------------------------
2.............................................. 90
2.5............................................ 75
3.5............................................ 50
5.0............................................ 25
10............................................. 0
------------------------------------------------------------------------
The measurements under this note refer to the use of an AEC (now NRC)
instrument. The respirable fraction of coal dust is determined with an
MRE; the figure corresponding to that of 2.4 mg/m\3\ in the table for
coal dust is 4.5 mg/m\3K\.
\f\ This standard applies to any operations or sectors for which the
respirable crystalline silica standard, 1910.1053, is stayed or is
otherwise not in effect.
0
4. Add Sec. 1910.1053 to read as follows:
Sec. 1910.1053 Respirable Crystalline Silica.
(a) Scope and application. (1) This section applies to all
occupational exposures to respirable crystalline silica, except:
(i) Construction work as defined in 29 CFR 1910.12(b) (occupational
exposures to respirable crystalline silica in construction work are
covered under 29 CFR 1926.1153);
(ii) Agricultural operations covered under 29 CFR part 1928; and
(iii) Exposures that result from the processing of sorptive clays.
(2) This section does not apply where the employer has objective
data demonstrating that employee exposure to respirable crystalline
silica will remain below 25 micrograms per cubic meter of air (25
[mu]g/m\3\) as an 8-hour time-weighted average (TWA) under any
foreseeable conditions.
(3) This section does not apply if the employer complies with 29
CFR 1926.1153 and:
(i) The task performed is indistinguishable from a construction
task listed on Table 1 in paragraph (c) of 29 CFR 1926.1153; and
(ii) The task will not be performed regularly in the same
environment and conditions.
(b) Definitions. For the purposes of this section the following
definitions apply:
Action level means a concentration of airborne respirable
crystalline silica of 25 [mu]g/m\3\, calculated as an 8-hour TWA.
Assistant Secretary means the Assistant Secretary of Labor for
Occupational Safety and Health, U.S. Department of Labor, or designee.
Director means the Director of the National Institute for
Occupational Safety and Health (NIOSH), U.S. Department of Health and
Human Services, or designee.
Employee exposure means the exposure to airborne respirable
crystalline silica that would occur if the employee were not using a
respirator.
High-efficiency particulate air [HEPA] filter means a filter that
is at least 99.97 percent efficient in removing mono-dispersed
particles of 0.3 micrometers in diameter.
Objective data means information, such as air monitoring data from
industry-wide surveys or calculations based on the composition of a
substance, demonstrating employee exposure to respirable crystalline
silica associated with a particular product or material or a specific
process, task, or activity. The data must reflect workplace conditions
closely resembling or with a higher exposure potential than the
processes, types of material, control methods, work practices, and
environmental conditions in the employer's current operations.
Physician or other licensed health care professional [PLHCP] means
an individual whose legally permitted scope of practice (i.e., license,
registration, or certification) allows him or her to independently
provide or be delegated the responsibility to provide some or all of
the particular health care services required by paragraph (i) of this
section.
Regulated area means an area, demarcated by the employer, where an
employee's exposure to airborne concentrations of respirable
crystalline silica exceeds, or can reasonably be expected to exceed,
the PEL.
Respirable crystalline silica means quartz, cristobalite, and/or
tridymite contained in airborne particles that are determined to be
respirable by a sampling device designed to meet the characteristics
for respirable-particle-size-selective samplers specified in the
International Organization for Standardization (ISO) 7708:1995: Air
Quality--Particle Size Fraction Definitions for Health-Related
Sampling.
Specialist means an American Board Certified Specialist in
Pulmonary Disease or an American Board Certified Specialist in
Occupational Medicine.
This section means this respirable crystalline silica standard, 29
CFR 1910.1053.
(c) Permissible exposure limit (PEL). The employer shall ensure
that no employee is exposed to an airborne concentration of respirable
crystalline silica in excess of 50 [mu]g/m\3\, calculated as an 8-hour
TWA.
(d) Exposure assessment--(1) General. The employer shall assess the
exposure of each employee who is or may reasonably be expected to be
exposed to respirable crystalline silica at or above the action level in
accordance with either the performance option in paragraph (d)(2) or the
scheduled monitoring option in paragraph (d)(3) of this section.
(2) Performance option. The employer shall assess the 8-hour TWA
exposure for each employee on the basis of any combination of air
monitoring data or objective data sufficient to accurately characterize
employee exposures to respirable crystalline silica.
(3) Scheduled monitoring option. (i) The employer shall perform
initial monitoring to assess the 8-hour TWA exposure for each employee
on the basis of one or more personal breathing zone air samples that
reflect the exposures of employees on each shift, for each job
classification, in each work area. Where several employees perform the
same tasks on the same shift and in the same work area, the employer
may sample a representative fraction of these employees in order to
meet this requirement. In representative sampling, the employer shall
sample the employee(s) who are expected to have the highest exposure to
respirable crystalline silica.
(ii) If initial monitoring indicates that employee exposures are
below the action level, the employer may discontinue monitoring for
those employees whose exposures are represented by such monitoring.
(iii) Where the most recent exposure monitoring indicates that
employee exposures are at or above the action level but at or below the
PEL, the employer shall repeat such monitoring within six months of the
most recent monitoring.
(iv) Where the most recent exposure monitoring indicates that
employee exposures are above the PEL, the employer shall repeat such
monitoring within three months of the most recent monitoring.
(v) Where the most recent (non-initial) exposure monitoring
indicates that employee exposures are below the action level, the
employer shall repeat such monitoring within six months of the most
recent monitoring until two consecutive measurements, taken 7 or more
days apart, are below the action level, at which time the employer may
discontinue monitoring for those employees whose exposures are
represented by such monitoring, except as otherwise provided in
paragraph (d)(4) of this section.
(4) Reassessment of exposures. The employer shall reassess
exposures whenever a change in the production, process, control
equipment, personnel, or work practices may reasonably be expected to
result in new or additional exposures at or above the action level, or
when the employer has any reason to believe that new or additional
exposures at or above the action level have occurred.
(5) Methods of sample analysis. The employer shall ensure that all
samples taken to satisfy the monitoring requirements of paragraph (d)
of this section are evaluated by a laboratory that analyzes air samples
for respirable crystalline silica in accordance with the procedures in
Appendix A to this section.
(6) Employee notification of assessment results. (i) Within 15
working days after completing an exposure assessment in accordance with
paragraph (d) of this section, the employer shall individually notify
each affected employee in writing of the results of that assessment or
post the results in an appropriate location accessible to all affected
employees.
(ii) Whenever an exposure assessment indicates that employee
exposure is above the PEL, the employer shall describe in the written
notification the corrective action being taken to reduce employee
exposure to or below the PEL.
(7) Observation of monitoring. (i) Where air monitoring is
performed to comply with the requirements of this section, the employer
shall provide affected employees or their designated representatives an
opportunity to observe any monitoring of employee exposure to
respirable crystalline silica.
(ii) When observation of monitoring requires entry into an area
where the use of protective clothing or equipment is required for any
workplace hazard, the employer shall provide the observer with
protective clothing and equipment at no cost and shall ensure that the
observer uses such clothing and equipment.
(e) Regulated areas--(1) Establishment. The employer shall
establish a regulated area wherever an employee's exposure to airborne
concentrations of respirable crystalline silica is, or can reasonably
be expected to be, in excess of the PEL.
(2) Demarcation. (i) The employer shall demarcate regulated areas
from the rest of the workplace in a manner that minimizes the number of
employees exposed to respirable crystalline silica within the regulated
area.
(ii) The employer shall post signs at all entrances to regulated
areas that bear the legend specified in paragraph (j)(2) of this
section.
(3) Access. The employer shall limit access to regulated areas to:
(A) Persons authorized by the employer and required by work duties
to be present in the regulated area;
(B) Any person entering such an area as a designated representative
of employees for the purpose of exercising the right to observe
monitoring procedures under paragraph (d) of this section; and
(C) Any person authorized by the Occupational Safety and Health Act
or regulations issued under it to be in a regulated area.
(4) Provision of respirators. The employer shall provide each
employee and the employee's designated representative entering a
regulated area with an appropriate respirator in accordance with
paragraph (g) of this section and shall require each employee and the
employee's designated representative to use the respirator while in a
regulated area.
(f) Methods of compliance--(1) Engineering and work practice
controls. The employer shall use engineering and work practice controls
to reduce and maintain employee exposure to respirable crystalline
silica to or below the PEL, unless the employer can demonstrate that
such controls are not feasible. Wherever such feasible engineering and
work practice controls are not sufficient to reduce employee exposure
to or below the PEL, the employer shall nonetheless use them to reduce
employee exposure to the lowest feasible level and shall supplement
them with the use of respiratory protection that complies with the
requirements of paragraph (g) of this section.
(2) Written exposure control plan. (i) The employer shall establish
and implement a written exposure control plan that contains at least
the following elements:
(A) A description of the tasks in the workplace that involve
exposure to respirable crystalline silica;
(B) A description of the engineering controls, work practices, and
respiratory protection used to limit employee exposure to respirable
crystalline silica for each task; and
(C) A description of the housekeeping measures used to limit
employee exposure to respirable crystalline silica.
(ii) The employer shall review and evaluate the effectiveness of
the written exposure control plan at least annually and update it as
necessary.
(iii) The employer shall make the written exposure control plan
readily available for examination and copying, upon request, to each
employee covered by this section, their designated representatives, the
Assistant Secretary and the Director.
(3) Abrasive blasting. In addition to the requirements of paragraph
(f)(1) of this section, the employer shall comply
with other OSHA standards, when applicable, such as 29 CFR 1910.94
(Ventilation), 29 CFR 1915.34 (Mechanical paint removers), and 29 CFR
1915 Subpart I (Personal Protective Equipment), where abrasive blasting
is conducted using crystalline silica-containing blasting agents, or
where abrasive blasting is conducted on substrates that contain
crystalline silica.
(g) Respiratory protection--(1) General. Where respiratory
protection is required by this section, the employer must provide each
employee an appropriate respirator that complies with the requirements
of this paragraph and 29 CFR 1910.134. Respiratory protection is
required:
(i) Where exposures exceed the PEL during periods necessary to
install or implement feasible engineering and work practice controls;
(ii) Where exposures exceed the PEL during tasks, such as certain
maintenance and repair tasks, for which engineering and work practice
controls are not feasible;
(iii) During tasks for which an employer has implemented all
feasible engineering and work practice controls and such controls are
not sufficient to reduce exposures to or below the PEL; and
(iv) During periods when the employee is in a regulated area.
(2) Respiratory protection program. Where respirator use is
required by this section, the employer shall institute a respiratory
protection program in accordance with 29 CFR 1910.134.
(h) Housekeeping. (1) The employer shall not allow dry sweeping or
dry brushing where such activity could contribute to employee exposure
to respirable crystalline silica unless wet sweeping, HEPA-filtered
vacuuming or other methods that minimize the likelihood of exposure are
not feasible.
(2) The employer shall not allow compressed air to be used to clean
clothing or surfaces where such activity could contribute to employee
exposure to respirable crystalline silica unless:
(i) The compressed air is used in conjunction with a ventilation
system that effectively captures the dust cloud created by the
compressed air; or
(ii) No alternative method is feasible.
(i) Medical surveillance--(1) General. (i) The employer shall make
medical surveillance available at no cost to the employee, and at a
reasonable time and place, for each employee who will be occupationally
exposed to respirable crystalline silica at or above the action level
for 30 or more days per year.
(ii) The employer shall ensure that all medical examinations and
procedures required by this section are performed by a PLHCP as defined
in paragraph (b) of this section.
(2) Initial examination. The employer shall make available an
initial (baseline) medical examination within 30 days after initial
assignment, unless the employee has received a medical examination that
meets the requirements of this section within the last three years. The
examination shall consist of:
(i) A medical and work history, with emphasis on: Past, present,
and anticipated exposure to respirable crystalline silica, dust, and
other agents affecting the respiratory system; any history of
respiratory system dysfunction, including signs and symptoms of
respiratory disease (e.g., shortness of breath, cough, wheezing);
history of tuberculosis; and smoking status and history;
(ii) A physical examination with special emphasis on the
respiratory system;
(iii) A chest X-ray (a single posteroanterior radiographic
projection or radiograph of the chest at full inspiration recorded on
either film (no less than 14 x 17 inches and no more than 16 x 17
inches) or digital radiography systems), interpreted and classified
according to the International Labour Office (ILO) International
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B
Reader;
(iv) A pulmonary function test to include forced vital capacity
(FVC) and forced expiratory volume in one second (FEV1) and
FEV1/FVC ratio, administered by a spirometry technician with
a current certificate from a NIOSH-approved spirometry course;
(v) Testing for latent tuberculosis infection; and
(vi) Any other tests deemed appropriate by the PLHCP.
(3) Periodic examinations. The employer shall make available
medical examinations that include the procedures described in paragraph
(i)(2) of this section (except paragraph (i)(2)(v)) at least every
three years, or more frequently if recommended by the PLHCP.
(4) Information provided to the PLHCP. The employer shall ensure
that the examining PLHCP has a copy of this standard, and shall provide
the PLHCP with the following information:
(i) A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
(ii) The employee's former, current, and anticipated levels of
occupational exposure to respirable crystalline silica;
(iii) A description of any personal protective equipment used or to
be used by the employee, including when and for how long the employee
has used or will use that equipment; and
(iv) Information from records of employment-related medical
examinations previously provided to the employee and currently within
the control of the employer.
(5) PLHCP's written medical report for the employee. The employer
shall ensure that the PLHCP explains to the employee the results of the
medical examination and provides each employee with a written medical
report within 30 days of each medical examination performed. The
written report shall contain:
(i) A statement indicating the results of the medical examination,
including any medical condition(s) that would place the employee at
increased risk of material impairment to health from exposure to
respirable crystalline silica and any medical conditions that require
further evaluation or treatment;
(ii) Any recommended limitations on the employee's use of
respirators;
(iii) Any recommended limitations on the employee's exposure to
respirable crystalline silica; and
(iv) A statement that the employee should be examined by a
specialist (pursuant to paragraph (i)(7) of this section) if the chest
X-ray provided in accordance with this section is classified as 1/0 or
higher by the B Reader, or if referral to a specialist is otherwise
deemed appropriate by the PLHCP.
(6) PLHCP's written medical opinion for the employer. (i) The
employer shall obtain a written medical opinion from the PLHCP within
30 days of the medical examination. The written opinion shall contain
only the following:
(A) The date of the examination;
(B) A statement that the examination has met the requirements of
this section; and
(C) Any recommended limitations on the employee's use of
respirators.
(ii) If the employee provides written authorization, the written
opinion shall also contain either or both of the following:
(A) Any recommended limitations on the employee's exposure to
respirable crystalline silica;
(B) A statement that the employee should be examined by a
specialist (pursuant to paragraph (i)(7) of this section) if the chest
X-ray provided in accordance with this section is classified as 1/0 or
higher by the B Reader, or if referral to a specialist is otherwise
deemed appropriate by the PLHCP.
(iii) The employer shall ensure that each employee receives a copy
of the written medical opinion described in paragraph (i)(6)(i) and
(ii) of this section within 30 days of each medical examination
performed.
(7) Additional examinations. (i) If the PLHCP's written medical
opinion indicates that an employee should be examined by a specialist,
the employer shall make available a medical examination by a specialist
within 30 days after receiving the PLHCP's written opinion.
(ii) The employer shall ensure that the examining specialist is
provided with all of the information that the employer is obligated to
provide to the PLHCP in accordance with paragraph (i)(4) of this
section.
(iii) The employer shall ensure that the specialist explains to the
employee the results of the medical examination and provides each
employee with a written medical report within 30 days of the
examination. The written report shall meet the requirements of
paragraph (i)(5) (except paragraph (i)(5)(iv)) of this section.
(iv) The employer shall obtain a written opinion from the
specialist within 30 days of the medical examination. The written
opinion shall meet the requirements of paragraph (i)(6) (except
paragraph (i)(6)(i)(B) and (i)(6)(ii)(B)) of this section.
(j) Communication of respirable crystalline silica hazards to
employees--(1) Hazard communication. The employer shall include
respirable crystalline silica in the program established to comply with
the hazard communication standard (HCS) (29 CFR 1910.1200). The
employer shall ensure that each employee has access to labels on
containers of crystalline silica and safety data sheets, and is trained
in accordance with the provisions of HCS and paragraph (j)(3) of this
section. The employer shall ensure that at least the following hazards
are addressed: Cancer, lung effects, immune system effects, and kidney
effects.
(2) Signs. The employer shall post signs at all entrances to
regulated areas that bear the following legend:
DANGER
RESPIRABLE CRYSTALLINE SILICA
MAY CAUSE CANCER
CAUSES DAMAGE TO LUNGS
WEAR RESPIRATORY PROTECTION IN THIS AREA
AUTHORIZED PERSONNEL ONLY
(3) Employee information and training. (i) The employer shall
ensure that each employee covered by this section can demonstrate
knowledge and understanding of at least the following:
(A) The health hazards associated with exposure to respirable
crystalline silica;
(B) Specific tasks in the workplace that could result in exposure
to respirable crystalline silica;
(C) Specific measures the employer has implemented to protect
employees from exposure to respirable crystalline silica, including
engineering controls, work practices, and respirators to be used;
(D) The contents of this section; and
(E) The purpose and a description of the medical surveillance
program required by paragraph (i) of this section.
(ii) The employer shall make a copy of this section readily
available without cost to each employee covered by this section.
(k) Recordkeeping--(1) Air monitoring data. (i) The employer shall
make and maintain an accurate record of all exposure measurements taken
to assess employee exposure to respirable crystalline silica, as
prescribed in paragraph (d) of this section.
(ii) This record shall include at least the following information:
(A) The date of measurement for each sample taken;
(B) The task monitored;
(C) Sampling and analytical methods used;
(D) Number, duration, and results of samples taken;
(E) Identity of the laboratory that performed the analysis;
(F) Type of personal protective equipment, such as respirators,
worn by the employees monitored; and
(G) Name, social security number, and job classification of all
employees represented by the monitoring, indicating which employees
were actually monitored.
(iii) The employer shall ensure that exposure records are
maintained and made available in accordance with 29 CFR 1910.1020.
(2) Objective data. (i) The employer shall make and maintain an
accurate record of all objective data relied upon to comply with the
requirements of this section.
(ii) This record shall include at least the following information:
(A) The crystalline silica-containing material in question;
(B) The source of the objective data;
(C) The testing protocol and results of testing;
(D) A description of the process, task, or activity on which the
objective data were based; and
(E) Other data relevant to the process, task, activity, material,
or exposures on which the objective data were based.
(iii) The employer shall ensure that objective data are maintained
and made available in accordance with 29 CFR 1910.1020.
(3) Medical surveillance. (i) The employer shall make and maintain
an accurate record for each employee covered by medical surveillance
under paragraph (i) of this section.
(ii) The record shall include the following information about the
employee:
(A) Name and social security number;
(B) A copy of the PLHCPs' and specialists' written medical
opinions; and
(C) A copy of the information provided to the PLHCPs and
specialists.
(iii) The employer shall ensure that medical records are maintained
and made available in accordance with 29 CFR 1910.1020.
(l) Dates. (1) This section is effective June 23, 2016.
(2) Except as provided for in paragraphs (l)(3) and (4) of this
section, all obligations of this section commence June 23, 2018.
(3) For hydraulic fracturing operations in the oil and gas
industry:
(i) All obligations of this section, except obligations for medical
surveillance in paragraph (i)(1)(i) and engineering controls in
paragraph (f)(1) of this section, commence June 23, 2018;
(ii) Obligations for engineering controls in paragraph (f)(1) of
this section commence June 23, 2021; and
(iii) Obligations for medical surveillance in paragraph (i)(1)(i)
commence in accordance with paragraph (l)(4) of this section.
(4) The medical surveillance obligations in paragraph (i)(1)(i)
commence on June 23, 2018, for employees who will be occupationally
exposed to respirable crystalline silica above the PEL for 30 or more
days per year. Those obligations commence June 23, 2020, for employees
who will be occupationally exposed to respirable crystalline silica at
or above the action level for 30 or more days per year.
Appendix A to Sec. 1910.1053--Methods of Sample Analysis
This appendix specifies the procedures for analyzing air samples
for respirable crystalline silica, as well as the quality control
procedures that employers must ensure that laboratories use when
performing an analysis required under 29 CFR 1910.1053 (d)(5).
Employers must ensure that such a laboratory:
1. Evaluates all samples using the procedures specified in one
of the following analytical methods: OSHA ID-142; NMAM 7500; NMAM
7602; NMAM 7603; MSHA P-2; or MSHA P-7;
2. Is accredited to ANS/ISO/IEC Standard 17025:2005 with respect
to crystalline silica analyses by a body that is compliant with ISO/
IEC Standard 17011:2004 for implementation of quality assessment
programs;
3. Uses the most current National Institute of Standards and
Technology (NIST) or NIST traceable standards for instrument
calibration or instrument calibration verification;
4. Implements an internal quality control (QC) program that
evaluates analytical uncertainty and provides employers with
estimates of sampling and analytical error;
5. Characterizes the sample material by identifying polymorphs
of respirable crystalline silica present, identifies the presence of
any interfering compounds that might affect the analysis, and makes
any corrections necessary in order to obtain accurate sample
analysis; and
6. Analyzes quantitatively for crystalline silica only after
confirming that the sample matrix is free of uncorrectable
analytical interferences, corrects for analytical interferences, and
uses a method that meets the following performance specifications:
6.1 Each day that samples are analyzed, performs instrument
calibration checks with standards that bracket the sample
concentrations;
6.2 Uses five or more calibration standard levels to prepare
calibration curves and ensures that standards are distributed
through the calibration range in a manner that accurately reflects
the underlying calibration curve; and
6.3 Optimizes methods and instruments to obtain a quantitative
limit of detection that represents a value no higher than 25 percent
of the PEL based on sample air volume.
Appendix B to Sec. 1910.1053--Medical Surveillance Guidelines
Introduction
The purpose of this Appendix is to provide medical information
and recommendations to aid physicians and other licensed health care
professionals (PLHCPs) regarding compliance with the medical
surveillance provisions of the respirable crystalline silica
standard (29 CFR 1910.1053). Appendix B is for informational and
guidance purposes only and none of the statements in Appendix B
should be construed as imposing a mandatory requirement on employers
that is not otherwise imposed by the standard.
Medical screening and surveillance allow for early
identification of exposure-related health effects in individual
employee and groups of employees, so that actions can be taken to
both avoid further exposure and prevent or address adverse health
outcomes. Silica-related diseases can be fatal, encompass a variety
of target organs, and may have public health consequences when
considering the increased risk of a latent tuberculosis (TB)
infection becoming active. Thus, medical surveillance of silica-
exposed employees requires that PLHCPs have a thorough knowledge of
silica-related health effects.
This Appendix is divided into seven sections. Section 1 reviews
silica-related diseases, medical responses, and public health
responses. Section 2 outlines the components of the medical
surveillance program for employees exposed to silica. Section 3
describes the roles and responsibilities of the PLHCP implementing
the program and of other medical specialists and public health
professionals. Section 4 provides a discussion of considerations,
including confidentiality. Section 5 provides a list of additional
resources and Section 6 lists references. Section 7 provides sample
forms for the written medical report for the employee, the written
medical opinion for the employer and the written authorization.
1. Recognition of Silica-Related Diseases
1.1. Overview. The term "silica" refers specifically to the
compound silicon dioxide (SiO2). Silica is a major component of
sand, rock, and mineral ores. Exposure to fine (respirable size)
particles of crystalline forms of silica is associated with adverse
health effects, such as silicosis, lung cancer, chronic obstructive
pulmonary disease (COPD), and activation of latent TB infections.
Exposure to respirable crystalline silica can occur in industry
settings such as foundries, abrasive blasting operations, paint
manufacturing, glass and concrete product manufacturing, brick
making, china and pottery manufacturing, manufacturing of plumbing
fixtures, and many construction activities including highway repair,
masonry, concrete work, rock drilling, and tuck-pointing. New uses
of silica continue to emerge. These include countertop
manufacturing, finishing, and installation (Kramer et al. 2012; OSHA
2015) and hydraulic fracturing in the oil and gas industry (OSHA
2012).
Silicosis is an irreversible, often disabling, and sometimes
fatal fibrotic lung disease. Progression of silicosis can occur
despite removal from further exposure. Diagnosis of silicosis
requires a history of exposure to silica and radiologic findings
characteristic of silica exposure. Three different presentations of
silicosis (chronic, accelerated, and acute) have been defined.
Accelerated and acute silicosis are much less common than chronic
silicosis. However, it is critical to recognize all cases of
accelerated and acute silicosis because these are life-threatening
illnesses and because they are caused by substantial overexposures
to respirable crystalline silica. Although any case of silicosis
indicates a breakdown in prevention, a case of acute or accelerated
silicosis implies current high exposure and a very marked breakdown
in prevention.
In addition to silicosis, employees exposed to respirable
crystalline silica, especially those with accelerated or acute
silicosis, are at increased risks of contracting active TB and other
infections (ATS 1997; Rees and Murray 2007). Exposure to respirable
crystalline silica also increases an employee's risk of developing
lung cancer, and the higher the cumulative exposure, the higher the
risk (Steenland et al. 2001; Steenland and Ward 2014). Symptoms for
these diseases and other respirable crystalline silica-related
diseases are discussed below.
1.2. Chronic Silicosis. Chronic silicosis is the most common
presentation of silicosis and usually occurs after at least 10 years
of exposure to respirable crystalline silica. The clinical
presentation of chronic silicosis is:
1.2.1. Symptoms--shortness of breath and cough, although
employees may not notice any symptoms early in the disease.
Constitutional symptoms, such as fever, loss of appetite and
fatigue, may indicate other diseases associated with silica
exposure, such as TB infection or lung cancer. Employees with these
symptoms should immediately receive further evaluation and
treatment.
1.2.2. Physical Examination--may be normal or disclose dry rales
or rhonchi on lung auscultation.
1.2.3. Spirometry--may be normal or may show only a mild
restrictive or obstructive pattern.
1.2.4. Chest X-ray--classic findings are small, rounded
opacities in the upper lung fields bilaterally. However, small
irregular opacities and opacities in other lung areas can also
occur. Rarely, "eggshell calcifications" in the hilar and
mediastinal lymph nodes are seen.
1.2.5. Clinical Course--chronic silicosis in most cases is a
slowly progressive disease. Under the respirable crystalline silica
standard, the PLHCP is to recommend that employees with a 1/0
category X-ray be referred to an American Board Certified Specialist
in Pulmonary Disease or Occupational Medicine. The PLHCP and/or
Specialist should counsel employees regarding work practices and
personal habits that could affect employees' respiratory health.
1.3. Accelerated Silicosis. Accelerated silicosis generally
occurs within 5-10 years of exposure and results from high levels of
exposure to respirable crystalline silica. The clinical presentation
of accelerated silicosis is:
1.3.1. Symptoms--shortness of breath, cough, and sometimes
sputum production. Employees with exposure to respirable crystalline
silica, and especially those with accelerated silicosis, are at high
risk for activation of TB infections, atypical mycobacterial
infections, and fungal superinfections. Constitutional symptoms,
such as fever, weight loss, hemoptysis (coughing up blood), and
fatigue may herald one of these infections or the onset of lung
cancer.
1.3.2. Physical Examination--rales, rhonchi, or other abnormal
lung findings in relation to illnesses present. Clubbing of the
digits, signs of heart failure, and cor pulmonale may be present in
severe lung disease.
1.3.3. Spirometry--restrictive or mixed restrictive/obstructive
pattern.
1.3.4. Chest X-ray--small rounded and/or irregular opacities
bilaterally. Large opacities and lung abscesses may indicate
infections, lung cancer, or progression to complicated silicosis,
also termed progressive massive fibrosis.
1.3.5. Clinical Course--accelerated silicosis has a rapid,
severe course. Under the respirable crystalline silica standard, the
PLHCP can recommend referral to a Board Certified Specialist in
either Pulmonary Disease or Occupational Medicine, as deemed
appropriate, and referral to a Specialist is recommended whenever
the diagnosis of accelerated silicosis is being considered.
1.4. Acute Silicosis. Acute silicosis is a rare disease caused
by inhalation of extremely high levels of respirable crystalline
silica particles. The pathology is similar to alveolar proteinosis
with lipoproteinaceous material accumulating in the alveoli. Acute
silicosis develops rapidly, often, within a few months to less than
2 years of exposure, and is almost always fatal. The clinical
presentation of acute silicosis is as follows:
1.4.1. Symptoms--sudden, progressive, and severe shortness of
breath. Constitutional symptoms are frequently present and include
fever, weight loss, fatigue, productive cough, hemoptysis (coughing
up blood), and pleuritic chest pain.
1.4.2. Physical Examination--dyspnea at rest, cyanosis,
decreased breath sounds, inspiratory rales, clubbing of the digits,
and fever.
1.4.3. Spirometry--restrictive or mixed restrictive/obstructive
pattern.
1.4.4. Chest X-ray--diffuse haziness of the lungs bilaterally
early in the disease. As the disease progresses, the "ground
glass" appearance of interstitial fibrosis will appear.
1.4.5. Clinical Course--employees with acute silicosis are at
especially high risk of TB activation, nontuberculous mycobacterial
infections, and fungal superinfections. Acute silicosis is
immediately life-threatening. The employee should be urgently
referred to a Board Certified Specialist in Pulmonary Disease or
Occupational Medicine for evaluation and treatment. Although any
case of silicosis indicates a breakdown in prevention, a case of
acute or accelerated silicosis implies a profoundly high level of
silica exposure and may mean that other employees are currently
exposed to dangerous levels of silica.
1.5. COPD. COPD, including chronic bronchitis and emphysema, has
been documented in silica-exposed employees, including those who do
not develop silicosis. Periodic spirometry tests are performed to
evaluate each employee for progressive changes consistent with the
development of COPD. In addition to evaluating spirometry results of
individual employees over time, PLHCPs may want to be aware of
general trends in spirometry results for groups of employees from
the same workplace to identify possible problems that might exist at
that workplace. (See Section 2 of this Appendix on Medical
Surveillance for further discussion.) Heart disease may develop
secondary to lung diseases such as COPD. A recent study by Liu et
al. 2014 noted a significant exposure-response trend between
cumulative silica exposure and heart disease deaths, primarily due
to pulmonary heart disease, such as cor pulmonale.
1.6. Renal and Immune System. Silica exposure has been
associated with several types of kidney disease, including
glomerulonephritis, nephrotic syndrome, and end stage renal disease
requiring dialysis. Silica exposure has also been associated with
other autoimmune conditions, including progressive systemic
sclerosis, systemic lupus erythematosus, and rheumatoid arthritis.
Studies note an association between employees with silicosis and
serologic markers for autoimmune diseases, including antinuclear
antibodies, rheumatoid factor, and immune complexes (Jalloul and
Banks 2007; Shtraichman et al. 2015).
1.7. TB and Other Infections. Silica-exposed employees with
latent TB are 3 to 30 times more likely to develop active pulmonary
TB infection (ATS 1997; Rees and Murray 2007). Although respirable
crystalline silica exposure does not cause TB infection, individuals
with latent TB infection are at increased risk for activation of
disease if they have higher levels of respirable crystalline silica
exposure, greater profusion of radiographic abnormalities, or a
diagnosis of silicosis. Demographic characteristics, such as
immigration from some countries, are associated with increased rates
of latent TB infection. PLHCPs can review the latest Centers for
Disease Control and Prevention (CDC) information on TB incidence
rates and high risk populations online (See Section 5 of this
Appendix). Additionally, silica-exposed employees are at increased
risk for contracting nontuberculous mycobacterial infections,
including Mycobacterium avium-intracellulare and Mycobacterium
kansaii.
1.8. Lung Cancer. The National Toxicology Program has listed
respirable crystalline silica as a known human carcinogen since 2000
(NTP 2014). The International Agency for Research on Cancer (2012)
has also classified silica as Group 1 (carcinogenic to humans).
Several studies have indicated that the risk of lung cancer from
exposure to respirable crystalline silica and smoking is greater
than additive (Brown 2009; Liu et al. 2013). Employees should be
counseled on smoking cessation.
2. Medical Surveillance
PLHCPs who manage silica medical surveillance programs should
have a thorough understanding of the many silica-related diseases
and health effects outlined in Section 1 of this Appendix. At each
clinical encounter, the PLHCP should consider silica-related health
outcomes, with particular vigilance for acute and accelerated
silicosis. In this Section, the required components of medical
surveillance under the respirable crystalline silica standard are
reviewed, along with additional guidance and recommendations for
PLHCPs performing medical surveillance examinations for silica-
exposed employees.
2.1. History
2.1.1. The respirable crystalline silica standard requires the
following: A medical and work history, with emphasis on: Past,
present, and anticipated exposure to respirable crystalline silica,
dust, and other agents affecting the respiratory system; any history
of respiratory system dysfunction, including signs and symptoms of
respiratory disease (e.g., shortness of breath, cough, wheezing);
history of TB; and smoking status and history.
2.1.2. Further, the employer must provide the PLHCP with the
following information:
2.1.2.1. A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
2.1.2.2. The employee's former, current, and anticipated levels
of occupational exposure to respirable crystalline silica;
2.1.2.3. A description of any personal protective equipment used
or to be used by the employee, including when and for how long the
employee has used or will use that equipment; and
2.1.2.4. Information from records of employment-related medical
examinations previously provided to the employee and currently
within the control of the employer.
2.1.3. Additional guidance and recommendations: A history is
particularly important both in the initial evaluation and in
periodic examinations. Information on past and current medical
conditions (particularly a history of kidney disease, cardiac
disease, connective tissue disease, and other immune diseases),
medications, hospitalizations and surgeries may uncover health
risks, such as immune suppression, that could put an employee at
increased health risk from exposure to silica. This information is
important when counseling the employee on risks and safe work
practices related to silica exposure.
2.2. Physical Examination
2.2.1. The respirable crystalline silica standard requires the
following: A physical examination, with special emphasis on the
respiratory system. The physical examination must be performed at
the initial examination and every three years thereafter.
2.2.2. Additional guidance and recommendations: Elements of the
physical examination that can assist the PHLCP include: An
examination of the cardiac system, an extremity examination (for
clubbing, cyanosis, edema, or joint abnormalities), and an
examination of other pertinent organ systems identified during the
history.
2.3. TB Testing
2.3.1. The respirable crystalline silica standard requires the
following: Baseline testing for TB on initial examination.
2.3.2. Additional guidance and recommendations:
2.3.2.1. Current CDC guidelines (See Section 5 of this Appendix)
should be followed for the application and interpretation of
Tuberculin skin tests (TST). The interpretation and documentation of
TST reactions should be performed within 48 to 72 hours of
administration by trained PLHCPs.
2.3.2.2. PLHCPs may use alternative TB tests, such as
interferon-[gamma] release assays (IGRAs), if sensitivity and
specificity are comparable to TST (Mazurek et al. 2010; Slater et
al. 2013). PLHCPs can consult the current CDC guidelines for
acceptable tests for latent TB infection.
2.3.2.3. The silica standard allows the PLHCP to order
additional tests or test at a greater frequency than required by the
standard, if deemed appropriate. Therefore, PLHCPs might perform
periodic (e.g., annual) TB testing as appropriate, based on
employees' risk factors. For example, according to the American
Thoracic Society (ATS), the diagnosis of silicosis or exposure to
silica for 25 years or more are indications for annual TB testing
(ATS 1997). PLHCPs should consult the current CDC guidance on risk
factors for TB (See Section 5 of this Appendix).
2.3.2.4. Employees with positive TB tests and those with
indeterminate test results should be referred to the appropriate
agency or specialist, depending on the test results and clinical
picture. Agencies, such as local public health departments, or
specialists, such as a pulmonary or infectious disease specialist,
may be the appropriate referral. Active TB is a nationally
notifiable disease. PLHCPs should be aware of the reporting
requirements for their region. All States have TB Control Offices
that can be contacted for further information. (See Section 5 of
this Appendix for links to CDC's TB resources and State TB Control
Offices.)
2.3.2.5. The following public health principles are key to TB
control in the U.S. (ATS-CDC-IDSA 2005):
(1) Prompt detection and reporting of persons who have
contracted active TB;
(2) Prevention of TB spread to close contacts of active TB
cases;
(3) Prevention of active TB in people with latent TB through
targeted testing and treatment; and
(4) Identification of settings at high risk for TB transmission
so that appropriate infection-control measures can be implemented.
2.4. Pulmonary Function Testing
2.4.1. The respirable crystalline silica standard requires the
following: Pulmonary function testing must be performed on the
initial examination and every three years thereafter. The required
pulmonary function test is spirometry and must include forced vital
capacity (FVC), forced expiratory volume in one second
(FEV1), and FEV1/FVC ratio. Testing must be
administered by a spirometry technician with a current certificate
from a National Institute for Occupational Health and Safety
(NIOSH)-approved spirometry course.
2.4.2. Additional guidance and recommendations: Spirometry
provides information about individual respiratory status and can be
used to track an employee's respiratory status over time or as a
surveillance tool to follow individual and group respiratory
function. For quality results, the ATS and the American College of
Occupational and Environmental Medicine (ACOEM) recommend use of the
third National Health and Nutrition Examination Survey (NHANES III)
values, and ATS publishes recommendations for spirometry equipment
(Miller et al. 2005; Townsend 2011; Redlich et al. 2014). OSHA's
publication, Spirometry Testing in Occupational Health Programs:
Best Practices for Healthcare Professionals, provides helpful
guidance (See Section 5 of this Appendix). Abnormal spirometry
results may warrant further clinical evaluation and possible
recommendations for limitations on the employee's exposure to
respirable crystalline silica.
2.5. Chest X-ray
2.5.1. The respirable crystalline silica standard requires the
following: A single posteroanterior (PA) radiographic projection or
radiograph of the chest at full inspiration recorded on either film
(no less than 14 x 17 inches and no more than 16 x 17 inches) or
digital radiography systems. A chest X-ray must be performed on the
initial examination and every three years thereafter. The chest X-
ray must be interpreted and classified according to the
International Labour Office (ILO) International Classification of
Radiographs of Pneumoconioses by a NIOSH-certified B Reader.
Chest radiography is necessary to diagnose silicosis, monitor
the progression of silicosis, and identify associated conditions
such as TB. If the B reading indicates small opacities in a
profusion of 1/0 or higher, the employee is to receive a
recommendation for referral to a Board Certified Specialist in
Pulmonary Disease or Occupational Medicine.
2.5.2. Additional guidance and recommendations: Medical imaging
has largely transitioned from conventional film-based radiography to
digital radiography systems. The ILO Guidelines for the
Classification of Pneumoconioses has historically provided film-
based chest radiography as a referent standard for comparison to
individual exams. However, in 2011, the ILO revised the guidelines
to include a digital set of referent standards that were derived
from the prior film-based standards. To assist in assuring that
digitally-acquired radiographs are at least as safe and effective as
film radiographs, NIOSH has prepared guidelines, based upon accepted
contemporary professional recommendations (See Section 5 of this
Appendix). Current research from Laney et al. 2011 and Halldin et
al. 2014 validate the use of the ILO digital referent images. Both
studies conclude that the results of pneumoconiosis classification
using digital references are comparable to film-based ILO
classifications. Current ILO guidance on radiography for
pneumoconioses and B-reading should be reviewed by the PLHCP
periodically, as needed, on the ILO or NIOSH Web sites (See Section
5 of this Appendix).
2.6. Other Testing. Under the respirable crystalline silica
standards, the PLHCP has the option of ordering additional testing
he or she deems appropriate. Additional tests can be ordered on a
case-by-case basis depending on individual signs or symptoms and
clinical judgment. For example, if an employee reports a history of
abnormal kidney function tests, the PLHCP may want to order a
baseline renal function tests (e.g., serum creatinine and
urinalysis). As indicated above, the PLHCP may order annual TB
testing for silica-exposed employees who are at high risk of
developing active TB infections. Additional tests that PLHCPs may
order based on findings of medical examinations include, but is not
limited to, chest computerized tomography (CT) scan for lung cancer
or COPD, testing for immunologic diseases, and cardiac testing for
pulmonary-related heart disease, such as cor pulmonale.
3. Roles and Responsibilities
3.1. PLHCP. The PLHCP designation refers to "an individual
whose legally permitted scope of practice (i.e., license,
registration, or certification) allows him or her to independently
provide or be delegated the responsibility to provide some or all of
the particular health care services required" by the respirable
crystalline silica standard. The legally permitted scope of practice
for the PLHCP is determined by each State. PLHCPs who perform
clinical services for a silica medical surveillance program should
have a thorough knowledge of respirable crystalline silica-related
diseases and symptoms. Suspected cases of silicosis, advanced COPD,
or other respiratory conditions causing impairment should be
promptly referred to a Board Certified Specialist in Pulmonary
Disease or Occupational Medicine.
Once the medical surveillance examination is completed, the
employer must ensure that the PLHCP explains to the employee the
results of the medical examination and provides the employee with a
written medical report within 30 days of the examination. The
written medical report must contain a statement indicating the
results of the medical examination, including any medical
condition(s) that would place the employee at increased risk of
material impairment to health from exposure to respirable
crystalline silica and any medical conditions that require further
evaluation or treatment. In addition, the PLHCP's written medical
report must include any recommended limitations on the employee's
use of respirators, any recommended limitations on the employee's
exposure to respirable crystalline silica, and a statement that the
employee should be examined by a Board Certified Specialist in
Pulmonary Disease or Occupational medicine if the chest X-ray is
classified as 1/0 or higher by the B Reader, or if referral to a
Specialist is otherwise deemed appropriate by the PLHCP.
The PLHCP should discuss all findings and test results and any
recommendations regarding the employee's health, worksite safety and
health practices, and medical referrals for further evaluation, if
indicated. In addition, it is suggested that the PLHCP offer to
provide the employee with a complete copy of their examination and
test results, as some employees may want this information for their
own records or to provide to their personal physician or a future
PLHCP. Employees are entitled to access their medical records.
Under the respirable crystalline silica standard, the employer
must ensure that the PLHCP provides the employer with a written
medical opinion within 30 days of the employee examination, and that
the employee also gets a copy of the written medical opinion for the
employer within 30 days. The PLHCP may choose to directly provide
the employee a copy of the written medical opinion. This can be
particularly helpful to employees, such as construction employees,
who may change employers frequently. The written medical opinion can
be used by the employee as proof of up-to-date medical surveillance.
The following lists the elements of the written medical report for
the employee and written medical opinion for the employer. (Sample
forms for the written medical report for the employee, the written
medical opinion for the employer, and the written authorization are
provided in Section 7 of this Appendix.)
3.1.1. The written medical report for the employee must include
the following information:
3.1.1.1. A statement indicating the results of the medical
examination, including any medical condition(s) that would place the
employee at increased risk of material impairment to health from
exposure to respirable crystalline silica and any medical conditions
that require further evaluation or treatment;
3.1.1.2. Any recommended limitations upon the employee's use of
a respirator;
3.1.1.3. Any recommended limitations on the employee's exposure
to respirable crystalline silica; and
3.1.1.4. A statement that the employee should be examined by a
Board Certified Specialist in Pulmonary Disease or Occupational
Medicine, where the standard requires or where the PLHCP has
determined such a referral is necessary. The standard requires
referral to a Board Certified Specialist in Pulmonary Disease or
Occupational Medicine for a chest X-ray B reading indicating small
opacities in a profusion of 1/0 or higher, or if the PHLCP
determines that referral to a Specialist is necessary for other
silica-related findings.
3.1.2. The PLHCP's written medical opinion for the employer must
include only the following information:
3.1.2.1. The date of the examination;
3.1.2.2. A statement that the examination has met the
requirements of this section; and
3.1.2.3. Any recommended limitations on the employee's use of
respirators.
3.1.2.4. If the employee provides the PLHCP with written
authorization, the written opinion for the employer shall also
contain either or both of the following:
(1) Any recommended limitations on the employee's exposure to
respirable crystalline silica; and
(2) A statement that the employee should be examined by a Board
Certified Specialist in Pulmonary Disease or Occupational Medicine
if the chest X-ray provided in accordance with this section is
classified as 1/0 or higher by the B Reader, or if referral to a
Specialist is otherwise deemed appropriate.
3.1.2.5. In addition to the above referral for abnormal chest X-
ray, the PLHCP may refer an employee to a Board Certified Specialist
in Pulmonary Disease or Occupational Medicine for other findings of
concern during the medical surveillance examination if these
findings are potentially related to silica exposure.
3.1.2.6. Although the respirable crystalline silica standard
requires the employer to ensure that the PLHCP explains the results
of the medical examination to the employee, the standard does not
mandate how this should be done. The written medical opinion for the
employer could contain a statement that the PLHCP has explained the
results of the medical examination to the employee.
3.2. Medical Specialists. The silica standard requires that all
employees with chest X-ray B readings of 1/0 or higher be referred
to a Board Certified Specialist in Pulmonary Disease or Occupational
Medicine. If the employee has given written authorization for the
employer to be informed, then the employer shall make available a
medical examination by a Specialist within 30 days after receiving
the PLHCP's written medical opinion.
3.2.1. The employer must provide the following information to
the Board Certified Specialist in Pulmonary Disease or Occupational
Medicine:
3.2.1.1. A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
3.2.1.2. The employee's former, current, and anticipated levels
of occupational exposure to respirable crystalline silica;
3.2.1.3. A description of any personal protective equipment used
or to be used by the employee, including when and for how long the
employee has used or will use that equipment; and
3.2.1.4. Information from records of employment-related medical
examinations previously provided to the employee and currently
within the control of the employer.
3.2.2. The PLHCP should make certain that, with written
authorization from the employee, the Board Certified Specialist in
Pulmonary Disease or Occupational Medicine has any other pertinent
medical and occupational information necessary for the specialist's
evaluation of the employee's condition.
3.2.3. Once the Board Certified Specialist in Pulmonary Disease
or Occupational Medicine has evaluated the employee, the employer
must ensure that the Specialist explains to the employee the results
of the medical examination and provides the employee with a written
medical report within 30 days of the examination. The employer must
also ensure that the Specialist provides the employer with a written
medical opinion within 30 days of the employee examination. (Sample
forms for the written medical report for the employee, the written
medical opinion for the employer and the written authorization are
provided in Section 7 of this Appendix.)
3.2.4. The Specialist's written medical report for the employee
must include the following information:
3.2.4.1. A statement indicating the results of the medical
examination, including any medical condition(s) that would place the
employee at increased risk of material impairment to health from
exposure to respirable crystalline silica and any medical conditions
that require further evaluation or treatment;
3.2.4.2. Any recommended limitations upon the employee's use of
a respirator; and
3.2.4.3. Any recommended limitations on the employee's exposure
to respirable crystalline silica.
3.2.5. The Specialist's written medical opinion for the employer
must include the following information:
3.2.5.1. The date of the examination; and
3.2.5.2. Any recommended limitations on the employee's use of
respirators.
3.2.5.3. If the employee provides the Board Certified Specialist
in Pulmonary Disease or Occupational Medicine with written
authorization, the written medical opinion for the employer shall
also contain any recommended limitations on the employee's exposure
to respirable crystalline silica.
3.2.5.4. Although the respirable crystalline silica standard
requires the employer to ensure that the Board Certified Specialist
in Pulmonary Disease or Occupational Medicine explains the results
of the medical examination to the employee, the standard does not
mandate how this should be done. The written medical opinion for the
employer could contain a statement that the Specialist has explained
the results of the medical examination to the employee.
3.2.6. After evaluating the employee, the Board Certified
Specialist in Pulmonary Disease or Occupational Medicine should
provide feedback to the PLHCP as appropriate, depending on the
reason for the referral. OSHA believes that because the PLHCP has
the primary relationship with the employer and employee, the
Specialist may want to communicate his or her findings to the PLHCP
and have the PLHCP simply update the original medical report for the
employee and medical opinion for the employer. This is permitted
under the standard, so long as all requirements and time deadlines
are met.
3.3. Public Health Professionals. PLHCPs might refer employees
or consult with public health professionals as a result of silica
medical surveillance. For instance, if individual cases of active TB
are identified, public health professionals from state or local
health departments may assist in diagnosis and treatment of
individual cases and may evaluate other potentially affected
persons, including coworkers. Because silica-exposed employees are
at increased risk of progression from latent to active TB, treatment
of latent infection is recommended. The diagnosis of active TB,
acute or accelerated silicosis, or other silica-related diseases and
infections should serve as sentinel events suggesting high levels of
exposure to silica and may require consultation with the appropriate
public health agencies to investigate potentially similarly exposed
coworkers to assess for disease clusters. These agencies include
local or state health departments or OSHA. In addition, NIOSH can
provide assistance upon request through their Health Hazard
Evaluation program. (See Section 5 of this Appendix)
4. Confidentiality and Other Considerations
The information that is provided from the PLHCP to the employee
and employer under the medical surveillance section of OSHA's
respirable crystalline silica standard differs from that of medical
surveillance requirements in previous OSHA standards. The standard
requires two separate written communications, a written medical
report for the employee and a written medical opinion for the
employer. The confidentiality requirements for the written medical
opinion are more stringent than in past standards. For example, the
information the PLHCP can (and must) include in his or her written
medical opinion for the employer is limited to: The date of the
examination, a statement that the examination has met the
requirements of this section, and any recommended limitations on the
employee's use of respirators. If the employee provides written
authorization for the disclosure of any limitations on the employee's
exposure to respirable crystalline silica, then the PLHCP can
(and must) include that information in the written medical opinion for
the employer as well. Likewise, with the employee's written authorization,
the PLHCP can (and must) disclose the PLHCP's referral recommendation
(if any) as part of the written medical opinion for the employer.
However, the opinion to the employer must not include information
regarding recommended limitations on the employee's exposure to
respirable crystalline silica or any referral recommendations without
the employee's written authorization.
The standard also places limitations on the information that the
Board Certified Specialist in Pulmonary Disease or Occupational
Medicine can provide to the employer without the employee's written
authorization. The Specialist's written medical opinion for the
employer, like the PLHCP's opinion, is limited to (and must
contain): The date of the examination and any recommended
limitations on the employee's use of respirators. If the employee
provides written authorization, the written medical opinion can (and
must) also contain any limitations on the employee's exposure to
respirable crystalline silica.
The PLHCP should discuss the implication of signing or not
signing the authorization with the employee (in a manner and
language that he or she understands) so that the employee can make
an informed decision regarding the written authorization and its
consequences. The discussion should include the risk of ongoing
silica exposure, personal risk factors, risk of disease progression,
and possible health and economic consequences. For instance, written
authorization is required for a PLHCP to advise an employer that an
employee should be referred to a Board Certified Specialist in
Pulmonary Disease or Occupational Medicine for evaluation of an
abnormal chest X-ray (B-reading 1/0 or greater). If an employee does
not sign an authorization, then the employer will not know and
cannot facilitate the referral to a Specialist and is not required
to pay for the Specialist's examination. In the rare case where an
employee is diagnosed with acute or accelerated silicosis, co-
workers are likely to be at significant risk of developing those
diseases as a result of inadequate controls in the workplace. In
this case, the PLHCP and/or Specialist should explain this concern
to the affected employee and make a determined effort to obtain
written authorization from the employee so that the PLHCP and/or
Specialist can contact the employer.
Finally, without written authorization from the employee, the
PLHCP and/or Board Certified Specialist in Pulmonary Disease or
Occupational Medicine cannot provide feedback to an employer
regarding control of workplace silica exposure, at least in relation
to an individual employee. However, the regulation does not prohibit
a PLHCP and/or Specialist from providing an employer with general
recommendations regarding exposure controls and prevention programs
in relation to silica exposure and silica-related illnesses, based
on the information that the PLHCP receives from the employer such as
employees' duties and exposure levels. Recommendations may include
increased frequency of medical surveillance examinations, additional
medical surveillance components, engineering and work practice
controls, exposure monitoring and personal protective equipment. For
instance, more frequent medical surveillance examinations may be a
recommendation to employers for employees who do abrasive blasting
with silica because of the high exposures associated with that
operation.
ACOEM's Code of Ethics and discussion is a good resource to
guide PLHCPs regarding the issues discussed in this section (See
Section 5 of this Appendix).
5. Resources
5.1. American College of Occupational and Environmental Medicine
(ACOEM):
ACOEM Code of Ethics. Accessed at: http://www.acoem.org/codeofconduct.aspx
Raymond, L.W. and Wintermeyer, S. (2006) ACOEM evidenced-based
statement on medical surveillance of silica-exposed workers: Medical
surveillance of workers exposed to crystalline silica. J Occup
Environ Med, 48, 95-101.
5.2. Center for Disease Control and Prevention (CDC)
Tuberculosis Web page: http://www.cdc.gov/tb/default.htm
State TB Control Offices Web page: http://www.cdc.gov/tb/links/tboffices.htm
Tuberculosis Laws and Policies Web page: http://www.cdc.gov/tb/programs/laws/default.htm
CDC. (2013). Latent Tuberculosis Infection: A Guide for Primary
Health Care Providers. Accessed at: http://www.cdc.gov/tb/publications/ltbi/pdf/targetedltbi.pdf
5.3. International Labour Organization
International Labour Office (ILO). (2011) Guidelines for the use of
the ILO International Classification of Radiographs of
Pneumoconioses, Revised edition 2011. Occupational Safety and Health
Series No. 22: http://www.ilo.org/safework/info/publications/WCMS_168260/lang-en/index.htm
5.4. National Institute of Occupational Safety and Health
(NIOSH)
NIOSH B Reader Program Web page. (Information on interpretation of
X-rays for silicosis and a list of certified B-readers). Accessed
at: http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html
NIOSH Guideline (2011). Application of Digital Radiography for the
Detection and Classification of Pneumoconiosis. NIOSH publication
number 2011-198. Accessed at: http://www.cdc.gov/niosh/docs/2011-198/.
NIOSH Hazard Review (2002), Health Effects of Occupational Exposure
to Respirable Crystalline Silica. NIOSH publication number 2002-129:
Accessed at http://www.cdc.gov/niosh/docs/2002-129/
NIOSH Health Hazard Evaluations Programs. (Information on the NIOSH
Health Hazard Evaluation (HHE) program, how to request an HHE and
how to look up an HHE report). Accessed at: http://www.cdc.gov/niosh/hhe/
5.5. National Industrial Sand Association:
Occupational Health Program for Exposure to Crystalline Silica in
the Industrial Sand Industry. National Industrial Sand Association,
2nd ed. 2010. Can be ordered at:http://www.sand.org/silica-occupational-health-program
5.6. Occupational Safety and Health Administration (OSHA)
Contacting OSHA: http://www.osha.gov/html/Feed_Back.html
OSHA's Clinicians Web page. (OSHA resources, regulations and links
to help clinicians navigate OSHA's Web site and aid clinicians in
caring for workers.) Accessed at: http://www.osha.gov/dts/oom/clinicians/index.html
OSHA's Safety and Health Topics Web page on Silica. Accessed at:
http://www.osha.gov/dsg/topics/silicacrystalline/index.html
OSHA (2013). Spirometry Testing in Occupational Health Programs:
Best Practices for Healthcare Professionals. (OSHA 3637-03 2013).
Accessed at: http://www.osha.gov/Publications/OSHA3637.pdf
OSHA/NIOSH (2011). Spirometry: OSHA/NIOSH Spirometry InfoSheet (OSHA
3415-1-11). (Provides guidance to employers). Accessed at http://www.osha.gov/Publications/osha3415.pdf
OSHA/NIOSH (2011) Spirometry: OSHA/NIOSH Spirometry Worker Info.
(OSHA 3418-3-11). Accessed at http://www.osha.gov/Publications/osha3418.pdf
5.7. Other
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA
Cancer J Clin, 64, 63-69. (This article reviews not only silica and
lung cancer but also all the known silica-related health effects.
Further, the authors provide guidance to clinicians on medical
surveillance of silica-exposed workers and worker counselling on
safety practices to minimize silica exposure.)
6. References
American Thoracic Society (ATS). Medical Section of the American
Lung Association (1997). Adverse effects of crystalline silica
exposure. Am J Respir Crit Care Med, 155, 761-765.
American Thoracic Society (ATS), Centers for Disease Control (CDC),
Infectious Diseases Society of America (IDSA) (2005). Controlling
Tuberculosis in the United States. Morbidity and Mortality Weekly
Report (MMWR), 54(RR12), 1-81. Accessed at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5412a1.htm.
Brown, T. (2009). Silica exposure, smoking, silicosis and lung
cancer--complex interactions. Occupational Medicine, 59, 89-95.
Halldin, C.N., Petsonk, E.L., and Laney, A.S. (2014). Validation of
the International Labour Office digitized standard images for
recognition and classification of radiographs of pneumoconiosis.
Acad Radiol, 21, 305-311. International Agency for Research on Cancer.
(2012). Monographs on the evaluation of carcinogenic risks to humans:
Arsenic, Metals, Fibers, and Dusts Silica Dust, Crystalline, in the
Form of Quartz or Cristobalite. A Review of Human Carcinogens.
Volume 100 C. Geneva, Switzerland: World Health Organization.
Jalloul, A.S. and Banks D.E. (2007). Chapter 23. The health effects
of silica exposure. In: Rom, W.N. and Markowitz, S.B. (Eds).
Environmental and Occupational Medicine, 4th edition. Lippincott,
Williams and Wilkins, Philadelphia, 365-387.
Kramer, M.R., Blanc, P.D., Fireman, E., Amital, A., Guber, A.,
Rahman, N.A., and Shitrit, D. (2012). Artifical stone silicosis:
Disease resurgence among artificial stone workers. Chest, 142, 419-
424.
Laney, A.S., Petsonk, E.L., and Attfield, M.D. (2011). Intramodality
and intermodality comparisons of storage phosphor computed
radiography and conventional film-screen radiography in the
recognition of small pneumonconiotic opacities. Chest, 140, 1574-
1580.
Liu, Y., Steenland, K., Rong, Y., Hnizdo, E., Huang, X., Zhang, H.,
Shi, T., Sun, Y., Wu, T., and Chen, W. (2013). Exposure-response
analysis and risk assessment for lung cancer in relationship to
silica exposure: A 44-year cohort study of 34,018 workers. Am J Epi,
178, 1424-1433.
Liu, Y., Rong, Y., Steenland, K., Christiani, D.C., Huang, X., Wu,
T., and Chen, W. (2014). Long-term exposure to crystalline silica
and risk of heart disease mortality. Epidemiology, 25, 689-696.
Mazurek, G.H., Jereb, J., Vernon, A., LoBue, P., Goldberg, S.,
Castro, K. (2010). Updated guidelines for using interferon gamma
release assays to detect Mycobacterium tuberculosis infection--
United States. Morbidity and Mortality Weekly Report (MMWR),
59(RR05), 1-25.
Miller, M.R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R.,
Coates, A., Crapo, R., Enright, P., van der Grinten, C.P.,
Gustafsson, P., Jensen, R., Johnson, D.C., MacIntyre, N., McKay, R.,
Navajas, D., Pedersen, O.F., Pellegrino, R., Viegi, G., and Wanger,
J. (2005).
American Thoracic Society/European Respiratory Society (ATS/ERS)
Task Force: Standardisation of Spirometry. Eur Respir J, 26, 319-
338.
National Toxicology Program (NTP) (2014). Report on Carcinogens,
Thirteenth Edition. Silica, Crystalline (respirable Size). Research
Triangle Park, NC: U.S. Department of Health and Human Services,
Public Health Service. http://ntp.niehs.nih.gov/ntp/roc/content/profiles/silica.pdf.
Occupational Safety and Health Administration/National Institute for
Occupational Safety and Health (OSHA/NIOSH) (2012). Hazard Alert.
Worker exposure to silica during hydraulic fracturing.
Occupational Safety and Health Administration/National Institute for
Occupational Safety and Health (OSHA/NIOSH) (2015). Hazard alert.
Worker exposure to silica during countertop manufacturing,
finishing, and installation. (OSHA-HA-3768-2015).
Redlich, C.A., Tarlo, S.M., Hankinson, J.L., Townsend, M.C,
Eschenbacher, W.L., Von Essen, S.G., Sigsgaard, T., Weissman, D.N.
(2014). Official American Thoracic Society technical standards:
Spirometry in the occupational setting. Am J Respir Crit Care Med;
189, 984-994.
Rees, D. and Murray, J. (2007). Silica, silicosis and tuberculosis.
Int J Tuberc Lung Dis, 11(5), 474-484.
Shtraichman, O., Blanc, P.D., Ollech, J.E., Fridel, L., Fuks, L.,
Fireman, E., and Kramer, M.R. (2015). Outbreak of autoimmune disease
in silicosis linked to artificial stone. Occup Med, 65, 444-450.
Slater, M.L., Welland, G., Pai, M., Parsonnet, J., and Banaei, N.
(2013). Challenges with QuantiFERON-TB gold assay for large-scale,
routine screening of U.S. healthcare workers. Am J Respir Crit Care
Med, 188, 1005-1010.
Steenland, K., Mannetje, A., Boffetta, P., Stayner, L., Attfield,
M., Chen, J., Dosemeci, M., DeKlerk, N., Hnizdo, E., Koskela, R.,
and Checkoway, H. (2001). International Agency for Research on
Cancer. Pooled exposure-response analyses and risk assessment for
lung cancer in 10 cohorts of silica-exposed workers: An IARC
multicentre study. Cancer Causes Control, 12(9):773-84.
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA
Cancer J Clin, 64, 63-69.
Townsend, M.C. ACOEM Guidance Statement. (2011). Spirometry in the
occupational health setting--2011 Update. J Occup Environ Med, 53,
569-584.
7. Sample Forms
Three sample forms are provided. The first is a sample written
medical report for the employee. The second is a sample written
medical opinion for the employer. And the third is a sample written
authorization form that employees sign to clarify what information
the employee is authorizing to be released to the employer.
BILLING CODE 4510-26-P
BILLING CODE 4510-26-C
PART 1915--OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD
EMPLOYMENT
0
5. The authority citation for part 1915 is revised to read as follows:
Authority: Section 41, Longshore and Harbor Workers'
Compensation Act (33 U.S.C. 941); Sections 4, 6, and 8 of the
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655,
657); Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR
25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-
2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 31160), 4-
2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable; 29 CFR
part 1911.
Sections 1915.120 and 1915.152 of 29 CFR also issued under 29
CFR part 1911.
0
6. In Sec. 1915.1000, amend Table Z by:
0
a. Revising the entries for "Silica, crystalline cristobalite,
respirable dust", "Silica, crystalline quartz, respirable
dust", "Silica, crystalline tripoli (as quartz), respirable dust",
and "Silica, crystalline tridymite, respirable dust";
0
b. Under the "MINERAL DUSTS" heading of the table, revising the entry
for "Silica: Cystalline Quartz";
0
c. Adding footnote 5; and
0
d. Add footnote p.
The revisions and additions should read as follows:
Sec. 1915.1000 Air contaminants.
* * * * *
Table Z--Shipyards
----------------------------------------------------------------------------------------------------------------
Skin
Substance CAS No.d ppm a * mg/m 3 b * designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust
Cristobalite; see 1915.1053................. 14464-46-1
Quartz; see 1915.1053 5..................... 14808-60-7
Tripoli (as quartz); see 1915.1053 5........ 1317-95-9
Trydimite; see 1915.1053.................... 15468-32-3
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Mineral Dusts
----------------------------------------------------------------------------------------------------------------
Substance mppcf (j)
----------------------------------------------------------------------------------------------------------------
SILICA:
Crystalline................................................................................. 250 (k)
---------------
Quartz. Threshold Limit calculated from the formula (p)......................................... % SiO2+5
* * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * * * *
\5\ See Mineral Dusts table for the exposure limit for any operations or sectors where the exposure limit in
Sec. 1915.1053 is stayed or is otherwise not in effect.
* The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit. They are to be
determined from breathing-zone air samples.
a Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
b Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
listed with a ppm entry, it is approximate.
* * * * * * *
p This standard applies to any operations or sectors for which the respirable crystalline silica standard,
1915.1053, is stayed or otherwise is not in effect.
0
7. Add Sec. 1915.1053 to read as follows:
Sec. 1915.1053 Respirable crystalline silica.
The requirements applicable to shipyard employment under this
section are identical to those set forth at Sec. 1910.1053 of this
chapter.
PART 1926--SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION
Subpart D--Occupational Health and Environmental Controls
0
8. The authority citation for subpart D of part 1926 is revised to read
as follows:
Authority: Section 107 of the Contract Work Hours and Safety
Standards Act (40 U.S.C. 3704); Sections 4, 6, and 8 of the
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655,
657); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR
111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR
31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable;
and 29 CFR part 1911.
Sections 1926.58, 1926.59, 1926.60, and 1926.65 also issued
under 5 U.S.C. 553 and 29 CFR part 1911.
Section 1926.61 also issued under 49 U.S.C. 1801-1819 and 6
U.S.C. 553.
Section 1926.62 also issued under section 1031 of the Housing
and Community Development Act of 1992 (42 U.S.C. 4853).
Section 1926.65 also issued under section 126 of the Superfund
Amendments and Reauthorization Act of 1986, as amended (reprinted at
29 U.S.C.A. 655 Note), and 5 U.S.C. 553.
0
9. In Sec. 1926.55, amend appendix A:
0
a. By revising the entries for "Silica, crystalline cristobalite,
respirable dust", "Silica, crystalline quartz, respirable dust",
"Silica, crystalline tripoli (as quartz), respirable dust", and
"Silica, crystalline tridymite, respirable dust";
0
b. Under the "MINERAL DUSTS" heading of the table, by revising the
entry for "Silica: Cystalline Quartz" in column 1;
0
c. Adding footnote 5; and
0
d. Adding footnote p .
The revisions and additions read as follows:
Sec. 1926.55 Gases, vapors, fumes, dusts, and mists.
* * * * *
Appendix A to Sec. 1926.55--1970 American Conference of Governmental
Industrial Hygienists' Threshold Limit Values of Airborne Contaminants
Threshold Limit Values of Airborne Contaminants for Construction
----------------------------------------------------------------------------------------------------------------
Skin
Substance CAS No.d ppm a * mg/m 3 b * designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust
Cristobalite; see 1926.1153................. 14464-46-1 .............. .............. ..............
Quartz; see 1926.11153 5.................... 14808-60-7 .............. .............. ..............
Tripoli (as quartz); see 1926.1153 5........ 1317-95-9 .............. .............. ..............
Trydimite; see 1926.1153.................... 15468-32-3 .............. .............. ..............
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Mineral Dusts
----------------------------------------------------------------------------------------------------------------
SILICA:
Crystalline................................................................................. 250 (k)
---------------
Quartz. Threshold Limit calculated from the formula (p)......................................... % SiO2+5
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Footnotes.
* * * * * * *
\5\ See Mineral Dusts table for the exposure limit for any operations or sectors where the exposure limit in
Sec. 1926.1153 is stayed or is otherwise not in effect.
* * * * * * *
a Parts of vapor or gas per million parts of contaminated air by volume at 25 [deg]C and 760 torr.
b Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when
listed with a ppm entry, it is approximate.
* * * * * * *
d The CAS number is for information only. Enforcement is based on the substance name. For an entry covering more
than one metal compound, measured as the metal, the CAS number for the metal is given--not CAS numbers for the
individual compounds.
* * * * * * *
p This standard applies to any operations or sectors for which the respirable crystalline silica standard,
1926.1153, is stayed or otherwise is not in effect.
Subpart Z--Toxic and Hazardous Substances
0
10. The authority for subpart Z of part 1926 is revised to read as
follows:
Authority: Section 107 of the Contract Work Hours and Safety
Standards Act (40 U.S.C. 3704); Sections 4, 6, and 8 of the
Occupational Safety and Health Act of 1970 (29 U.S.C. 653, 655,
657); and Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76
(41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR
111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR
31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 3912), as applicable;
and 29 CFR part 1911.
Section 1926.1102 not issued under 29 U.S.C. 655 or 29 CFR part
1911; also issued under 5 U.S.C. 553.
0
11. Add Sec. 1926.1153 to read as follows:
Sec. 1926.1153 Respirable crystalline silica.
(a) Scope and application. This section applies to all occupational
exposures to respirable crystalline silica in construction work, except
where employee exposure will remain below 25 micrograms per cubic meter
of air (25 [mu]g/m\3\) as an 8-hour time-weighted average (TWA) under
any foreseeable conditions.
(b) Definitions. For the purposes of this section the following
definitions apply:
Action level means a concentration of airborne respirable
crystalline silica of 25 [mu]g/m\3\, calculated as an 8-hour TWA.
Assistant Secretary means the Assistant Secretary of Labor for
Occupational Safety and Health, U.S. Department of Labor, or designee.
Director means the Director of the National Institute for
Occupational Safety and Health (NIOSH), U.S. Department of Health and
Human Services, or designee.
Competent person means an individual who is capable of identifying
existing and foreseeable respirable crystalline silica hazards in the
workplace and who has authorization to take prompt corrective measures
to eliminate or minimize them. The competent person must have the
knowledge and ability necessary to fulfill the responsibilities set
forth in paragraph (g) of this section.
Employee exposure means the exposure to airborne respirable
crystalline silica that would occur if the employee were not using a
respirator.
High-efficiency particulate air [HEPA] filter means a filter that
is at least 99.97 percent efficient in removing mono-dispersed
particles of 0.3 micrometers in diameter.
Objective data means information, such as air monitoring data from
industry-wide surveys or calculations based on the composition of a
substance, demonstrating employee exposure to respirable crystalline
silica associated with a particular product or material or a specific
process, task, or activity. The data must reflect workplace conditions
closely resembling or with a higher exposure potential than the
processes, types of material, control methods, work practices, and
environmental conditions in the employer's current operations.
Physician or other licensed health care professional [PLHCP] means
an individual whose legally permitted scope of practice (i.e., license,
registration, or certification) allows him or her to independently
provide or be delegated the responsibility to provide some or all of
the particular health care services required by paragraph (h) of this
section.
Respirable crystalline silica means quartz, cristobalite, and/or
tridymite contained in airborne particles that are determined to be
respirable by a sampling device designed to meet the characteristics
for respirable-particle-size-selective samplers specified in the
International Organization for Standardization (ISO) 7708:1995: Air
Quality--Particle Size Fraction Definitions for Health-Related
Sampling.
Specialist means an American Board Certified Specialist in
Pulmonary Disease or an American Board Certified Specialist in
Occupational Medicine.
This section means this respirable crystalline silica standard, 29
CFR 1926.1153.
(c) Specified exposure control methods. (1) For each employee
engaged in a task identified on Table 1, the employer shall fully and
properly implement the engineering controls, work practices, and
respiratory protection specified for the task on Table 1, unless the
employer assesses and limits the exposure of the employee to respirable
crystalline silica in accordance with paragraph (d) of this section.
Table 1--Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica
----------------------------------------------------------------------------------------------------------------
Required respiratory protection and minimum
Engineering and work assigned protection factor (APF)
Equipment/task practice control methods ---------------------------------------------------
<=4 hours/shift >4 hours/shift
----------------------------------------------------------------------------------------------------------------
(i) Stationary masonry saws...... Use saw equipped with None.................... None.
integrated water
delivery system that
continuously feeds water
to the blade.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
(ii) Handheld power saws (any Use saw equipped with
blade diameter). integrated water
delivery system that
continuously feeds water
to the blade.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions:
--When used outdoors.. None.................... APF 10.
--When used indoors or APF 10.................. APF 10.
in an enclosed area.
(iii) Handheld power saws for For tasks performed
cutting fiber-cement board (with outdoors only: None.................... None.
blade diameter of 8 inches or Use saw equipped with
less). commercially available
dust collection system.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide the air flow
recommended by the tool
manufacturer, or
greater, and have a
filter with 99% or
greater efficiency.
(iv) Walk-behind saws............ Use saw equipped with
integrated water
delivery system that
continuously feeds water
to the blade.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions:
--When used outdoors.. None.................... None.
--When used indoors or APF 10.................. APF 10.
in an enclosed area.
(v) Drivable saws................ For tasks performed
outdoors only:
Use saw equipped with None.................... None.
integrated water
delivery system that
continuously feeds water
to the blade.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
(vi) Rig-mounted core saws or Use tool equipped with None.................... None.
drills. integrated water
delivery system that
supplies water to
cutting surface.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
(vii) Handheld and stand-mounted Use drill equipped with None.................... None.
drills (including impact and commercially available
rotary hammer drills). shroud or cowling with
dust collection system.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide the air flow
recommended by the tool
manufacturer, or
greater, and have a
filter with 99% or
greater efficiency and a
filter-cleaning
mechanism.
Use a HEPA-filtered
vacuum when cleaning
holes.
(viii) Dowel drilling rigs for For tasks performed
concrete. outdoors only:
Use shroud around drill APF 10.................. APF 10.
bit with a dust
collection system. Dust
collector must have a
filter with 99% or
greater efficiency and a
filter-cleaning
mechanism.
Use a HEPA-filtered
vacuum when cleaning
holes.
(ix) Vehicle-mounted drilling Use dust collection None.................... None.
rigs for rock and concrete. system with close
capture hood or shroud
around drill bit with a
low-flow water spray to
wet the dust at the
discharge point from the
dust collector.
OR
Operate from within an None.................... None.
enclosed cab and use
water for dust
suppression on drill bit.
(x) Jackhammers and handheld Use tool with water
powered chipping tools. delivery system that
supplies a continuous
stream or spray of water
at the point of impact:
--When used outdoors.. None.................... APF 10.
--When used indoors or APF 10.................. APF 10.
in an enclosed area.
OR
Use tool equipped with
commercially available
shroud and dust
collection system.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide the air flow
recommended by the tool
manufacturer, or
greater, and have a
filter with 99% or
greater efficiency and a
filter-cleaning
mechanism:
--When used outdoors.. None.................... APF 10.
--When used indoors or APF 10.................. APF 10.
in an enclosed area.
(xi) Handheld grinders for mortar Use grinder equipped with APF 10.................. APF 25.
removal (i.e., tuckpointing). commercially available
shroud and dust
collection system.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide 25 cubic feet
per minute (cfm) or
greater of airflow per
inch of wheel diameter
and have a filter with
99% or greater
efficiency and a
cyclonic pre-separator
or filter-cleaning
mechanism.
(xii) Handheld grinders for uses For tasks performed None.................... None.
other than mortar removal. outdoors only:
Use grinder equipped with
integrated water
delivery system that
continuously feeds water
to the grinding surface.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
OR
Use grinder equipped with
commercially available
shroud and dust
collection system.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide 25 cubic feet
per minute (cfm) or
greater of airflow per
inch of wheel diameter
and have a filter with
99% or greater
efficiency and a
cyclonic pre-separator
or filter-cleaning
mechanism:
--When used outdoors.. None.................... None.
--When used indoors or None.................... APF 10.
in an enclosed area.
(xiii) Walk-behind milling Use machine equipped with None.................... None.
machines and floor grinders. integrated water
delivery system that
continuously feeds water
to the cutting surface.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
OR
Use machine equipped with None.................... None.
dust collection system
recommended by the
manufacturer.
Operate and maintain tool
in accordance with
manufacturer's
instructions to minimize
dust emissions.
Dust collector must
provide the air flow
recommended by the
manufacturer, or
greater, and have a
filter with 99% or
greater efficiency and a
filter-cleaning
mechanism.
When used indoors or in
an enclosed area, use a
HEPA-filtered vacuum to
remove loose dust in
between passes.
(xiv) Small drivable milling Use a machine equipped None.................... None.
machines (less than half-lane). with supplemental water
sprays designed to
suppress dust. Water
must be combined with a
surfactant.
Operate and maintain
machine to minimize dust
emissions.
(xv) Large drivable milling For cuts of any depth on None.................... None.
machines (half-lane and larger). asphalt only:
Use machine equipped with
exhaust ventilation on
drum enclosure and
supplemental water
sprays designed to
suppress dust.
Operate and maintain
machine to minimize dust
emissions.
For cuts of four inches
in depth or less on any
substrate:
Use machine equipped with None.................... None.
exhaust ventilation on
drum enclosure and
supplemental water
sprays designed to
suppress dust.
Operate and maintain
machine to minimize dust
emissions.
OR
Use a machine equipped None.................... None.
with supplemental water
spray designed to
suppress dust. Water
must be combined with a
surfactant.
Operate and maintain
machine to minimize dust
emissions.
(xvi) Crushing machines.......... Use equipment designed to None.................... None.
deliver water spray or
mist for dust
suppression at crusher
and other points where
dust is generated (e.g.,
hoppers, conveyers,
sieves/sizing or
vibrating components,
and discharge points).
Operate and maintain
machine in accordance
with manufacturer's
instructions to minimize
dust emissions.
Use a ventilated booth
that provides fresh,
climate-controlled air
to the operator, or a
remote control station.
(xvii) Heavy equipment and Operate equipment from None.................... None.
utility vehicles used to abrade within an enclosed cab. None.................... None.
or fracture silica-containing When employees outside of
materials (e.g., hoe-ramming, the cab are engaged in
rock ripping) or used during the task, apply water
demolition activities involving and/or dust suppressants
silica-containing materials. as necessary to minimize
dust emissions.
(xviii) Heavy equipment and Apply water and/or dust None.................... None.
utility vehicles for tasks such suppressants as
as grading and excavating but necessary to minimize
not including: Demolishing, dust emissions.
abrading, or fracturing silica- OR.......................
containing materials.
When the equipment None.................... None.
operator is the only
employee engaged in the
task, operate equipment
from within an enclosed
cab.
----------------------------------------------------------------------------------------------------------------
(2) When implementing the control measures specified in Table 1,
each employer shall:
(i) For tasks performed indoors or in enclosed areas, provide a
means of exhaust as needed to minimize the accumulation of visible
airborne dust;
(ii) For tasks performed using wet methods, apply water at flow
rates sufficient to minimize release of visible dust;
(iii) For measures implemented that include an enclosed cab or
booth, ensure that the enclosed cab or booth:
(A) Is maintained as free as practicable from settled dust;
(B) Has door seals and closing mechanisms that work properly;
(C) Has gaskets and seals that are in good condition and working
properly;
(D) Is under positive pressure maintained through continuous
delivery of fresh air;
(E) Has intake air that is filtered through a filter that is 95%
efficient in the 0.3-10.0 [micro]m range (e.g., MERV-16 or better); and
(F) Has heating and cooling capabilities.
(3) Where an employee performs more than one task on Table 1 during
the course of a shift, and the total duration of all tasks combined is
more than four hours, the required respiratory protection for each task
is the respiratory protection specified for more than four hours per
shift. If the total duration of all tasks on Table 1 combined is less
than four hours, the required respiratory protection for each task is
the respiratory protection specified for less than four hours per
shift.
(d) Alternative exposure control methods. For tasks not listed in
Table 1, or where the employer does not fully and properly implement
the engineering controls, work practices, and respiratory protection
described in Table 1:
(1) Permissible exposure limit (PEL). The employer shall ensure
that no employee is exposed to an airborne concentration of respirable
crystalline silica in excess of 50 [mu]g/m\3\, calculated as an 8-hour
TWA.
(2) Exposure assessment--(i) General. The employer shall assess the
exposure of each employee who is or may reasonably be expected to be
exposed to respirable crystalline silica at or above the action level
in accordance with either the performance option in paragraph
(d)(2)(ii) or the scheduled monitoring option in paragraph (d)(2)(iii)
of this section.
(ii) Performance option. The employer shall assess the 8-hour TWA
exposure for each employee on the basis of any combination of air
monitoring data or objective data sufficient to accurately characterize
employee exposures to respirable crystalline silica.
(iii) Scheduled monitoring option. (A) The employer shall perform
initial monitoring to assess the 8-hour TWA exposure for each employee
on the basis of one or more personal breathing zone air samples that
reflect the exposures of employees on each shift, for each job
classification, in each work area. Where several employees perform the
same tasks on the same shift and in the same work area, the employer
may sample a representative fraction of these employees in order to
meet this requirement. In representative sampling, the employer shall
sample the employee(s) who are expected to have the highest exposure to
respirable crystalline silica.
(B) If initial monitoring indicates that employee exposures are
below the action level, the employer may discontinue monitoring for
those employees whose exposures are represented by such monitoring.
(C) Where the most recent exposure monitoring indicates that
employee exposures are at or above the action level but at or below the
PEL, the employer shall repeat such monitoring within six months of the
most recent monitoring.
(D) Where the most recent exposure monitoring indicates that
employee exposures are above the PEL, the employer shall repeat such
monitoring within three months of the most recent monitoring.
(E) Where the most recent (non-initial) exposure monitoring
indicates that employee exposures are below the action level, the
employer shall repeat such monitoring within six months of the most
recent monitoring until two consecutive measurements, taken seven or
more days apart, are below the action level, at which time the employer
may discontinue monitoring for those employees whose exposures are
represented by such monitoring, except as otherwise provided in
paragraph (d)(2)(iv) of this section.
(iv) Reassessment of exposures. The employer shall reassess
exposures whenever a change in the production, process, control
equipment, personnel, or work practices may reasonably be expected to
result in new or additional exposures at or above the action level, or
when the employer has any reason to believe that new or additional
exposures at or above the action level have occurred.
(v) Methods of sample analysis. The employer shall ensure that all
samples taken to satisfy the monitoring requirements of paragraph
(d)(2) of this section are evaluated by a laboratory that analyzes air
samples for respirable crystalline silica in accordance with the
procedures in Appendix A to this section.
(vi) Employee notification of assessment results. (A) Within five
working days after completing an exposure assessment in accordance with
paragraph (d)(2) of this section, the employer shall individually
notify each affected employee in writing of the results of that
assessment or post the results in an appropriate location accessible to
all affected employees.
(B) Whenever an exposure assessment indicates that employee
exposure is above the PEL, the employer shall describe in the written
notification the corrective action being taken to reduce employee
exposure to or below the PEL.
(vii) Observation of monitoring. (A) Where air monitoring is
performed to comply with the requirements of this section, the employer
shall provide affected employees or their designated representatives an
opportunity to observe any monitoring of employee exposure to
respirable crystalline silica.
(B) When observation of monitoring requires entry into an area
where the use of protective clothing or equipment is required for any
workplace hazard, the employer shall provide the observer with
protective clothing and equipment at no cost and shall ensure that the
observer uses such clothing and equipment.
(3) Methods of compliance--(i) Engineering and work practice
controls. The employer shall use engineering and work practice controls
to reduce and maintain employee exposure to respirable crystalline
silica to or below the PEL, unless the employer can demonstrate that
such controls are not feasible. Wherever such feasible engineering and
work practice controls are not sufficient to reduce employee exposure
to or below the PEL, the employer shall nonetheless use them to reduce
employee exposure to the lowest feasible level and shall supplement
them with the use of respiratory protection that complies with the
requirements of paragraph (e) of this section.
(ii) Abrasive blasting. In addition to the requirements of
paragraph (d)(3)(i) of this section, the employer shall comply with
other OSHA standards, when applicable, such as 29 CFR 1926.57
(Ventilation), where abrasive blasting is conducted using crystalline
silica-containing blasting agents, or where abrasive blasting is
conducted on substrates that contain crystalline silica.
(e) Respiratory protection--(1) General. Where respiratory
protection is required by this section, the employer must provide each
employee an appropriate respirator that complies with the requirements
of this paragraph and 29 CFR 1910.134. Respiratory protection is
required:
(i) Where specified by Table 1 of paragraph (c) of this section; or
(ii) For tasks not listed in Table 1, or where the employer does
not fully and properly implement the engineering controls, work
practices, and respiratory protection described in Table 1:
(A) Where exposures exceed the PEL during periods necessary to
install or implement feasible engineering and work practice controls;
(B) Where exposures exceed the PEL during tasks, such as certain
maintenance and repair tasks, for which engineering and work practice
controls are not feasible; and
(C) During tasks for which an employer has implemented all feasible
engineering and work practice controls and such controls are not
sufficient to reduce exposures to or below the PEL.
(2) Respiratory protection program. Where respirator use is
required by this section, the employer shall institute a respiratory
protection program in accordance with 29 CFR 1910.134.
(3) Specified exposure control methods. For the tasks listed in
Table 1 in paragraph (c) of this section, if the employer fully and
properly implements the engineering controls, work practices, and
respiratory protection described in Table 1, the employer shall be
considered to be in compliance with paragraph (e)(1) of this section
and the requirements for selection of respirators in 29 CFR
1910.134(d)(1)(iii) and (d)(3) with regard to exposure to respirable
crystalline silica.
(f) Housekeeping. (1) The employer shall not allow dry sweeping or
dry brushing where such activity could contribute to employee exposure
to respirable crystalline silica unless wet sweeping, HEPA-filtered
vacuuming or other methods that minimize the likelihood of exposure are
not feasible.
(2) The employer shall not allow compressed air to be used to clean
clothing or surfaces where such activity could contribute to employee
exposure to respirable crystalline silica unless:
(i) The compressed air is used in conjunction with a ventilation
system that effectively captures the dust cloud created by the
compressed air; or
(ii) No alternative method is feasible.
(g) Written exposure control plan. (1) The employer shall establish
and implement a written exposure control plan that contains at least
the following elements:
(i) A description of the tasks in the workplace that involve
exposure to respirable crystalline silica;
(ii) A description of the engineering controls, work practices, and
respiratory protection used to limit employee exposure to respirable
crystalline silica for each task;
(iii) A description of the housekeeping measures used to limit
employee exposure to respirable crystalline silica; and
(iv) A description of the procedures used to restrict access to
work areas, when necessary, to minimize the number of employees exposed
to respirable crystalline silica and their level of exposure, including
exposures generated by other employers or sole proprietors.
(2) The employer shall review and evaluate the effectiveness of the
written exposure control plan at least annually and update it as
necessary.
(3) The employer shall make the written exposure control plan
readily available for examination and copying, upon request, to each
employee covered by this section, their designated representatives, the
Assistant Secretary and the Director.
(4) The employer shall designate a competent person to make
frequent and regular inspections of job sites, materials, and equipment
to implement the written exposure control plan.
(h) Medical surveillance--(1) General. (i) The employer shall make
medical surveillance available at no cost to the employee, and at a
reasonable time and place, for each employee who will be required under
this section to use a respirator for 30 or more days per year.
(ii) The employer shall ensure that all medical examinations and
procedures required by this section are performed by a PLHCP as defined
in paragraph (b) of this section.
(2) Initial examination. The employer shall make available an
initial (baseline) medical examination within 30 days after initial
assignment, unless the employee has received a medical examination that
meets the requirements of this section within the last three years. The
examination shall consist of:
(i) A medical and work history, with emphasis on: Past, present,
and anticipated exposure to respirable crystalline silica, dust, and
other agents affecting the respiratory system; any history of
respiratory system dysfunction, including signs and symptoms of
respiratory disease (e.g., shortness of breath, cough, wheezing);
history of tuberculosis; and smoking status and history; (ii) A physical
examination with special emphasis on the respiratory system;
(iii) A chest X-ray (a single posteroanterior radiographic
projection or radiograph of the chest at full inspiration recorded on
either film (no less than 14 x 17 inches and no more than 16 x 17
inches) or digital radiography systems), interpreted and classified
according to the International Labour Office (ILO) International
Classification of Radiographs of Pneumoconioses by a NIOSH-certified B
Reader;
(iv) A pulmonary function test to include forced vital capacity
(FVC) and forced expiratory volume in one second (FEV1) and
FEV1/FVC ratio, administered by a spirometry technician with
a current certificate from a NIOSH-approved spirometry course;
(v) Testing for latent tuberculosis infection; and
(vi) Any other tests deemed appropriate by the PLHCP.
(3) Periodic examinations. The employer shall make available
medical examinations that include the procedures described in paragraph
(h)(2) of this section (except paragraph (h)(2)(v)) at least every
three years, or more frequently if recommended by the PLHCP.
(4) Information provided to the PLHCP. The employer shall ensure
that the examining PLHCP has a copy of this standard, and shall provide
the PLHCP with the following information:
(i) A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
(ii) The employee's former, current, and anticipated levels of
occupational exposure to respirable crystalline silica;
(iii) A description of any personal protective equipment used or to
be used by the employee, including when and for how long the employee
has used or will use that equipment; and
(iv) Information from records of employment-related medical
examinations previously provided to the employee and currently within
the control of the employer.
(5) PLHCP's written medical report for the employee. The employer
shall ensure that the PLHCP explains to the employee the results of the
medical examination and provides each employee with a written medical
report within 30 days of each medical examination performed. The
written report shall contain:
(i) A statement indicating the results of the medical examination,
including any medical condition(s) that would place the employee at
increased risk of material impairment to health from exposure to
respirable crystalline silica and any medical conditions that require
further evaluation or treatment;
(ii) Any recommended limitations on the employee's use of
respirators;
(iii) Any recommended limitations on the employee's exposure to
respirable crystalline silica; and
(iv) A statement that the employee should be examined by a
specialist (pursuant to paragraph (h)(7) of this section) if the chest
X-ray provided in accordance with this section is classified as 1/0 or
higher by the B Reader, or if referral to a specialist is otherwise
deemed appropriate by the PLHCP.
(6) PLHCP's written medical opinion for the employer. (i) The
employer shall obtain a written medical opinion from the PLHCP within
30 days of the medical examination. The written opinion shall contain
only the following:
(A) The date of the examination;
(B) A statement that the examination has met the requirements of
this section; and
(C) Any recommended limitations on the employee's use of
respirators.
(ii) If the employee provides written authorization, the written
opinion shall also contain either or both of the following:
(A) Any recommended limitations on the employee's exposure to
respirable crystalline silica;
(B) A statement that the employee should be examined by a
specialist (pursuant to paragraph (h)(7) of this section) if the chest
X-ray provided in accordance with this section is classified as 1/0 or
higher by the B Reader, or if referral to a specialist is otherwise
deemed appropriate by the PLHCP.
(iii) The employer shall ensure that each employee receives a copy
of the written medical opinion described in paragraph (h)(6)(i) and
(ii) of this section within 30 days of each medical examination
performed.
(7) Additional examinations. (i) If the PLHCP's written medical
opinion indicates that an employee should be examined by a specialist,
the employer shall make available a medical examination by a specialist
within 30 days after receiving the PLHCP's written opinion.
(ii) The employer shall ensure that the examining specialist is
provided with all of the information that the employer is obligated to
provide to the PLHCP in accordance with paragraph (h)(4) of this
section.
(iii) The employer shall ensure that the specialist explains to the
employee the results of the medical examination and provides each
employee with a written medical report within 30 days of the
examination. The written report shall meet the requirements of
paragraph (h)(5) (except paragraph (h)(5)(iv)) of this section.
(iv) The employer shall obtain a written opinion from the
specialist within 30 days of the medical examination. The written
opinion shall meet the requirements of paragraph (h)(6) (except
paragraph (h)(6)(i)(B) and (ii)(B)) of this section.
(i) Communication of respirable crystalline silica hazards to
employees--(1) Hazard communication. The employer shall include
respirable crystalline silica in the program established to comply with
the hazard communication standard (HCS) (29 CFR 1910.1200). The
employer shall ensure that each employee has access to labels on
containers of crystalline silica and safety data sheets, and is trained
in accordance with the provisions of HCS and paragraph (i)(2) of this
section. The employer shall ensure that at least the following hazards
are addressed: Cancer, lung effects, immune system effects, and kidney
effects.
(2) Employee information and training. (i) The employer shall
ensure that each employee covered by this section can demonstrate
knowledge and understanding of at least the following:
(A) The health hazards associated with exposure to respirable
crystalline silica;
(B) Specific tasks in the workplace that could result in exposure
to respirable crystalline silica;
(C) Specific measures the employer has implemented to protect
employees from exposure to respirable crystalline silica, including
engineering controls, work practices, and respirators to be used;
(D) The contents of this section;
(E) The identity of the competent person designated by the employer
in accordance with paragraph (g)(4) of this section; and
(F) The purpose and a description of the medical surveillance
program required by paragraph (h) of this section.
(ii) The employer shall make a copy of this section readily
available without cost to each employee covered by this section.
(j) Recordkeeping--(1) Air monitoring data. (i) The employer shall
make and maintain an accurate record of all exposure measurements taken
to assess employee exposure to respirable crystalline silica, as
prescribed in paragraph (d)(2) of this section.
(ii) This record shall include at least the following information:
(A) The date of measurement for each sample taken;
(B) The task monitored;
(C) Sampling and analytical methods used;
(D) Number, duration, and results of samples taken;
(E) Identity of the laboratory that performed the analysis;
(F) Type of personal protective equipment, such as respirators,
worn by the employees monitored; and
(G) Name, social security number, and job classification of all
employees represented by the monitoring, indicating which employees
were actually monitored.
(iii) The employer shall ensure that exposure records are
maintained and made available in accordance with 29 CFR 1910.1020.
(2) Objective data. (i) The employer shall make and maintain an
accurate record of all objective data relied upon to comply with the
requirements of this section.
(ii) This record shall include at least the following information:
(A) The crystalline silica-containing material in question;
(B) The source of the objective data;
(C) The testing protocol and results of testing;
(D) A description of the process, task, or activity on which the
objective data were based; and
(E) Other data relevant to the process, task, activity, material,
or exposures on which the objective data were based.
(iii) The employer shall ensure that objective data are maintained
and made available in accordance with 29 CFR 1910.1020.
(3) Medical surveillance. (i) The employer shall make and maintain
an accurate record for each employee covered by medical surveillance
under paragraph (h) of this section.
(ii) The record shall include the following information about the
employee:
(A) Name and social security number;
(B) A copy of the PLHCPs' and specialists' written medical
opinions; and
(C) A copy of the information provided to the PLHCPs and
specialists.
(iii) The employer shall ensure that medical records are maintained
and made available in accordance with 29 CFR 1910.1020.
(k) Dates. (1) This section shall become effective June 23, 2016.
(2) All obligations of this section, except requirements for
methods of sample analysis in paragraph (d)(2)(v), shall commence June
23, 2017.
(3) Requirements for methods of sample analysis in paragraph
(d)(2)(v) of this section commence June 23, 2018.
Appendix A to Sec. 1926.1153--Methods of Sample Analysis
This This appendix specifies the procedures for analyzing air
samples for respirable crystalline silica, as well as the quality
control procedures that employers must ensure that laboratories use
when performing an analysis required under 29 CFR 1926.1153
(d)(2)(v). Employers must ensure that such a laboratory:
1. Evaluates all samples using the procedures specified in one
of the following analytical methods: OSHA ID-142; NMAM 7500; NMAM
7602; NMAM 7603; MSHA P-2; or MSHA P-7;
2. Is accredited to ANS/ISO/IEC Standard 17025:2005 with respect
to crystalline silica analyses by a body that is compliant with ISO/
IEC Standard 17011:2004 for implementation of quality assessment
programs;
3. Uses the most current National Institute of Standards and
Technology (NIST) or NIST traceable standards for instrument
calibration or instrument calibration verification;
4. Implements an internal quality control (QC) program that
evaluates analytical uncertainty and provides employers with
estimates of sampling and analytical error;
5. Characterizes the sample material by identifying polymorphs
of respirable crystalline silica present, identifies the presence of
any interfering compounds that might affect the analysis, and makes
any corrections necessary in order to obtain accurate sample
analysis; and
6. Analyzes quantitatively for crystalline silica only after
confirming that the sample matrix is free of uncorrectable
analytical interferences, corrects for analytical interferences, and
uses a method that meets the following performance specifications:
6.1 Each day that samples are analyzed, performs instrument
calibration checks with standards that bracket the sample
concentrations;
6.2 Uses five or more calibration standard levels to prepare
calibration curves and ensures that standards are distributed
through the calibration range in a manner that accurately reflects
the underlying calibration curve; and
6.3 Optimizes methods and instruments to obtain a quantitative
limit of detection that represents a value no higher than 25 percent
of the PEL based on sample air volume.
Appendix B to Sec. 1926.1153--Medical Surveillance Guidelines
Introduction
The purpose of this Appendix is to provide medical information
and recommendations to aid physicians and other licensed health care
professionals (PLHCPs) regarding compliance with the medical
surveillance provisions of the respirable crystalline silica
standard (29 CFR 1926.1153). Appendix B is for informational and
guidance purposes only and none of the statements in Appendix B
should be construed as imposing a mandatory requirement on employers
that is not otherwise imposed by the standard.
Medical screening and surveillance allow for early
identification of exposure-related health effects in individual
employee and groups of employees, so that actions can be taken to
both avoid further exposure and prevent or address adverse health
outcomes. Silica-related diseases can be fatal, encompass a variety
of target organs, and may have public health consequences when
considering the increased risk of a latent tuberculosis (TB)
infection becoming active. Thus, medical surveillance of silica-
exposed employees requires that PLHCPs have a thorough knowledge of
silica-related health effects.
This Appendix is divided into seven sections. Section 1 reviews
silica-related diseases, medical responses, and public health
responses. Section 2 outlines the components of the medical
surveillance program for employees exposed to silica. Section 3
describes the roles and responsibilities of the PLHCP implementing
the program and of other medical specialists and public health
professionals. Section 4 provides a discussion of considerations,
including confidentiality. Section 5 provides a list of additional
resources and Section 6 lists references. Section 7 provides sample
forms for the written medical report for the employee, the written
medical opinion for the employer and the written authorization.
1. Recognition of Silica-Related Diseases
1.1. Overview. The term "silica" refers specifically to the
compound silicon dioxide (SiO2). Silica is a major
component of sand, rock, and mineral ores. Exposure to fine
(respirable size) particles of crystalline forms of silica is
associated with adverse health effects, such as silicosis, lung
cancer, chronic obstructive pulmonary disease (COPD), and activation
of latent TB infections. Exposure to respirable crystalline silica
can occur in industry settings such as foundries, abrasive blasting
operations, paint manufacturing, glass and concrete product
manufacturing, brick making, china and pottery manufacturing,
manufacturing of plumbing fixtures, and many construction activities
including highway repair, masonry, concrete work, rock drilling, and
tuck-pointing. New uses of silica continue to emerge. These include
countertop manufacturing, finishing, and installation (Kramer et al.
2012; OSHA 2015) and hydraulic fracturing in the oil and gas
industry (OSHA 2012).
Silicosis is an irreversible, often disabling, and sometimes
fatal fibrotic lung disease. Progression of silicosis can occur
despite removal from further exposure. Diagnosis of silicosis
requires a history of exposure to silica and radiologic findings
characteristic of silica exposure. Three different presentations of
silicosis (chronic, accelerated, and acute) have been defined.
Accelerated and acute silicosis are much less common than chronic
silicosis. However, it is critical to recognize all cases of
accelerated and acute silicosis because these are life-threatening
illnesses and because they are caused by substantial overexposures
to respirable crystalline silica. Although any case of silicosis
indicates a breakdown in prevention, a case of acute or accelerated
silicosis implies current high exposure and a very marked breakdown
in prevention.
In addition to silicosis, employees exposed to respirable
crystalline silica, especially those with accelerated or acute
silicosis, are at increased risks of contracting active TB and other
infections (ATS 1997; Rees and Murray 2007). Exposure to respirable
crystalline silica also increases an employee's risk of developing
lung cancer, and the higher the cumulative exposure, the higher the
risk (Steenland et al. 2001; Steenland and Ward 2014). Symptoms for
these diseases and other respirable crystalline silica-related
diseases are discussed below.
1.2. Chronic Silicosis. Chronic silicosis is the most common
presentation of silicosis and usually occurs after at least 10 years
of exposure to respirable crystalline silica. The clinical
presentation of chronic silicosis is:
1.2.1. Symptoms--shortness of breath and cough, although
employees may not notice any symptoms early in the disease.
Constitutional symptoms, such as fever, loss of appetite and
fatigue, may indicate other diseases associated with silica
exposure, such as TB infection or lung cancer. Employees with these
symptoms should immediately receive further evaluation and
treatment.
1.2.2. Physical Examination--may be normal or disclose dry rales
or rhonchi on lung auscultation.
1.2.3. Spirometry--may be normal or may show only a mild
restrictive or obstructive pattern.
1.2.4. Chest X-ray--classic findings are small, rounded
opacities in the upper lung fields bilaterally. However, small
irregular opacities and opacities in other lung areas can also
occur. Rarely, "eggshell calcifications" in the hilar and
mediastinal lymph nodes are seen.
1.2.5. Clinical Course--chronic silicosis in most cases is a
slowly progressive disease. Under the respirable crystalline silica
standard, the PLHCP is to recommend that employees with a 1/0
category X-ray be referred to an American Board Certified Specialist
in Pulmonary Disease or Occupational Medicine. The PLHCP and/or
Specialist should counsel employees regarding work practices and
personal habits that could affect employees' respiratory health.
1.3. Accelerated Silicosis. Accelerated silicosis generally
occurs within 5-10 years of exposure and results from high levels of
exposure to respirable crystalline silica. The clinical presentation
of accelerated silicosis is:
1.3.1. Symptoms--shortness of breath, cough, and sometimes
sputum production. Employees with exposure to respirable crystalline
silica, and especially those with accelerated silicosis, are at high
risk for activation of TB infections, atypical mycobacterial
infections, and fungal superinfections. Constitutional symptoms,
such as fever, weight loss, hemoptysis (coughing up blood), and
fatigue may herald one of these infections or the onset of lung
cancer.
1.3.2. Physical Examination--rales, rhonchi, or other abnormal
lung findings in relation to illnesses present. Clubbing of the
digits, signs of heart failure, and cor pulmonale may be present in
severe lung disease.
1.3.3. Spirometry--restrictive or mixed restrictive/obstructive
pattern.
1.3.4. Chest X-ray--small rounded and/or irregular opacities
bilaterally. Large opacities and lung abscesses may indicate
infections, lung cancer, or progression to complicated silicosis,
also termed progressive massive fibrosis.
1.3.5. Clinical Course--accelerated silicosis has a rapid,
severe course. Under the respirable crystalline silica standard, the
PLHCP can recommend referral to a Board Certified Specialist in
either Pulmonary Disease or Occupational Medicine, as deemed
appropriate, and referral to a Specialist is recommended whenever
the diagnosis of accelerated silicosis is being considered.
1.4. Acute Silicosis. Acute silicosis is a rare disease caused
by inhalation of extremely high levels of respirable crystalline
silica particles. The pathology is similar to alveolar proteinosis
with lipoproteinaceous material accumulating in the alveoli. Acute
silicosis develops rapidly, often, within a few months to less than
2 years of exposure, and is almost always fatal. The clinical
presentation of acute silicosis is as follows:
1.4.1. Symptoms--sudden, progressive, and severe shortness of
breath. Constitutional symptoms are frequently present and include
fever, weight loss, fatigue, productive cough, hemoptysis (coughing
up blood), and pleuritic chest pain.
1.4.2. Physical Examination--dyspnea at rest, cyanosis,
decreased breath sounds, inspiratory rales, clubbing of the digits,
and fever.
1.4.3. Spirometry--restrictive or mixed restrictive/obstructive
pattern.
1.4.4. Chest X-ray--diffuse haziness of the lungs bilaterally
early in the disease. As the disease progresses, the "ground
glass" appearance of interstitial fibrosis will appear.
1.4.5. Clinical Course--employees with acute silicosis are at
especially high risk of TB activation, nontuberculous mycobacterial
infections, and fungal superinfections. Acute silicosis is
immediately life-threatening. The employee should be urgently
referred to a Board Certified Specialist in Pulmonary Disease or
Occupational Medicine for evaluation and treatment. Although any
case of silicosis indicates a breakdown in prevention, a case of
acute or accelerated silicosis implies a profoundly high level of
silica exposure and may mean that other employees are currently
exposed to dangerous levels of silica.
1.5. COPD. COPD, including chronic bronchitis and emphysema, has
been documented in silica-exposed employees, including those who do
not develop silicosis. Periodic spirometry tests are performed to
evaluate each employee for progressive changes consistent with the
development of COPD. In addition to evaluating spirometry results of
individual employees over time, PLHCPs may want to be aware of
general trends in spirometry results for groups of employees from
the same workplace to identify possible problems that might exist at
that workplace. (See Section 2 of this Appendix on Medical
Surveillance for further discussion.) Heart disease may develop
secondary to lung diseases such as COPD. A recent study by Liu et
al. 2014 noted a significant exposure-response trend between
cumulative silica exposure and heart disease deaths, primarily due
to pulmonary heart disease, such as cor pulmonale.
1.6. Renal and Immune System. Silica exposure has been
associated with several types of kidney disease, including
glomerulonephritis, nephrotic syndrome, and end stage renal disease
requiring dialysis. Silica exposure has also been associated with
other autoimmune conditions, including progressive systemic
sclerosis, systemic lupus erythematosus, and rheumatoid arthritis.
Studies note an association between employees with silicosis and
serologic markers for autoimmune diseases, including antinuclear
antibodies, rheumatoid factor, and immune complexes (Jalloul and
Banks 2007; Shtraichman et al. 2015).
1.7. TB and Other Infections. Silica-exposed employees with
latent TB are 3 to 30 times more likely to develop active pulmonary
TB infection (ATS 1997; Rees and Murray 2007). Although respirable
crystalline silica exposure does not cause TB infection, individuals
with latent TB infection are at increased risk for activation of
disease if they have higher levels of respirable crystalline silica
exposure, greater profusion of radiographic abnormalities, or a
diagnosis of silicosis. Demographic characteristics, such as
immigration from some countries, are associated with increased rates
of latent TB infection. PLHCPs can review the latest Centers for
Disease Control and Prevention (CDC) information on TB incidence
rates and high risk populations online (See Section 5 of this
Appendix). Additionally, silica-exposed employees are at increased
risk for contracting nontuberculous mycobacterial infections,
including Mycobacterium avium-intracellulare and Mycobacterium
kansaii.
1.8. Lung Cancer. The National Toxicology Program has listed
respirable crystalline silica as a known human carcinogen since 2000
(NTP 2014). The International Agency for Research on Cancer (2012)
has also classified silica as Group 1 (carcinogenic to humans).
Several studies have indicated that the risk of lung cancer from
exposure to respirable crystalline silica and smoking is greater
than additive (Brown 2009; Liu et al. 2013). Employees should be
counseled on smoking cessation.
2. Medical Surveillance
PLHCPs who manage silica medical surveillance programs should
have a thorough understanding of the many silica-related diseases
and health effects outlined in Section 1 of this Appendix. At each
clinical encounter, the PLHCP should consider silica-related health
outcomes, with particular vigilance for acute and accelerated
silicosis. In this Section, the required components of medical
surveillance under the respirable crystalline silica standard are
reviewed, along with additional guidance and recommendations for
PLHCPs performing medical surveillance examinations for
silica-exposed employees.
2.1. History.
2.1.1. The respirable crystalline silica standard requires the
following: A medical and work history, with emphasis on: Past,
present, and anticipated exposure to respirable crystalline silica,
dust, and other agents affecting the respiratory system; any history
of respiratory system dysfunction, including signs and symptoms of
respiratory disease (e.g., shortness of breath, cough, wheezing);
history of TB; and smoking status and history.
2.1.2. Further, the employer must provide the PLHCP with the
following information:
2.1.2.1. A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
2.1.2.2. The employee's former, current, and anticipated levels
of occupational exposure to respirable crystalline silica;
2.1.2.3. A description of any personal protective equipment used
or to be used by the employee, including when and for how long the
employee has used or will use that equipment; and
2.1.2.4. Information from records of employment-related medical
examinations previously provided to the employee and currently
within the control of the employer.
2.1.3. Additional guidance and recommendations: A history is
particularly important both in the initial evaluation and in
periodic examinations. Information on past and current medical
conditions (particularly a history of kidney disease, cardiac
disease, connective tissue disease, and other immune diseases),
medications, hospitalizations and surgeries may uncover health
risks, such as immune suppression, that could put an employee at
increased health risk from exposure to silica. This information is
important when counseling the employee on risks and safe work
practices related to silica exposure.
2.2. Physical Examination.
2.2.1. The respirable crystalline silica standard requires the
following: A physical examination, with special emphasis on the
respiratory system. The physical examination must be performed at
the initial examination and every three years thereafter.
2.2.2. Additional guidance and recommendations: Elements of the
physical examination that can assist the PHLCP include: An
examination of the cardiac system, an extremity examination (for
clubbing, cyanosis, edema, or joint abnormalities), and an
examination of other pertinent organ systems identified during the
history.
2.3. TB Testing.
2.3.1. The respirable crystalline silica standard requires the
following: Baseline testing for TB on initial examination.
2.3.2. Additional guidance and recommendations:
2.3.2.1. Current CDC guidelines (See Section 5 of this Appendix)
should be followed for the application and interpretation of
Tuberculin skin tests (TST). The interpretation and documentation of
TST reactions should be performed within 48 to 72 hours of
administration by trained PLHCPs.
2.3.2.2. PLHCPs may use alternative TB tests, such as
interferon-[gamma] release assays (IGRAs), if sensitivity and
specificity are comparable to TST (Mazurek et al. 2010; Slater et
al. 2013). PLHCPs can consult the current CDC guidelines for
acceptable tests for latent TB infection.
2.3.2.3. The silica standard allows the PLHCP to order
additional tests or test at a greater frequency than required by the
standard, if deemed appropriate. Therefore, PLHCPs might perform
periodic (e.g., annual) TB testing as appropriate, based on
employees' risk factors. For example, according to the American
Thoracic Society (ATS), the diagnosis of silicosis or exposure to
silica for 25 years or more are indications for annual TB testing
(ATS 1997). PLHCPs should consult the current CDC guidance on risk
factors for TB (See Section 5 of this Appendix).
2.3.2.4. Employees with positive TB tests and those with
indeterminate test results should be referred to the appropriate
agency or specialist, depending on the test results and clinical
picture. Agencies, such as local public health departments, or
specialists, such as a pulmonary or infectious disease specialist,
may be the appropriate referral. Active TB is a nationally
notifiable disease. PLHCPs should be aware of the reporting
requirements for their region. All States have TB Control Offices
that can be contacted for further information. (See Section 5 of
this Appendix for links to CDC's TB resources and State TB Control
Offices.)
2.3.2.5. The following public health principles are key to TB
control in the U.S. (ATS-CDC-IDSA 2005):
(1) Prompt detection and reporting of persons who have
contracted active TB;
(2) Prevention of TB spread to close contacts of active TB
cases;
(3) Prevention of active TB in people with latent TB through
targeted testing and treatment; and
(4) Identification of settings at high risk for TB transmission
so that appropriate infection-control measures can be implemented.
2.4. Pulmonary Function Testing.
2.4.1. The respirable crystalline silica standard requires the
following: Pulmonary function testing must be performed on the
initial examination and every three years thereafter. The required
pulmonary function test is spirometry and must include forced vital
capacity (FVC), forced expiratory volume in one second
(FEV1), and FEV1/FVC ratio. Testing must be
administered by a spirometry technician with a current certificate
from a National Institute for Occupational Health and Safety
(NIOSH)-approved spirometry course.
2.4.2. Additional guidance and recommendations: Spirometry
provides information about individual respiratory status and can be
used to track an employee's respiratory status over time or as a
surveillance tool to follow individual and group respiratory
function. For quality results, the ATS and the American College of
Occupational and Environmental Medicine (ACOEM) recommend use of the
third National Health and Nutrition Examination Survey (NHANES III)
values, and ATS publishes recommendations for spirometry equipment
(Miller et al. 2005; Townsend 2011; Redlich et al. 2014). OSHA's
publication, Spirometry Testing in Occupational Health Programs:
Best Practices for Healthcare Professionals, provides helpful
guidance (See Section 5 of this Appendix). Abnormal spirometry
results may warrant further clinical evaluation and possible
recommendations for limitations on the employee's exposure to
respirable crystalline silica.
2.5. Chest X-ray.
2.5.1. The respirable crystalline silica standard requires the
following: A single posteroanterior (PA) radiographic projection or
radiograph of the chest at full inspiration recorded on either film
(no less than 14 x 17 inches and no more than 16 x 17 inches) or
digital radiography systems. A chest X-ray must be performed on the
initial examination and every three years thereafter. The chest X-
ray must be interpreted and classified according to the
International Labour Office (ILO) International Classification of
Radiographs of Pneumoconioses by a NIOSH-certified B Reader.
Chest radiography is necessary to diagnose silicosis, monitor
the progression of silicosis, and identify associated conditions
such as TB. If the B reading indicates small opacities in a
profusion of 1/0 or higher, the employee is to receive a
recommendation for referral to a Board Certified Specialist in
Pulmonary Disease or Occupational Medicine.
2.5.2. Additional guidance and recommendations: Medical imaging
has largely transitioned from conventional film-based radiography to
digital radiography systems. The ILO Guidelines for the
Classification of Pneumoconioses has historically provided film-
based chest radiography as a referent standard for comparison to
individual exams. However, in 2011, the ILO revised the guidelines
to include a digital set of referent standards that were derived
from the prior film-based standards. To assist in assuring that
digitally-acquired radiographs are at least as safe and effective as
film radiographs, NIOSH has prepared guidelines, based upon accepted
contemporary professional recommendations (See Section 5 of this
Appendix). Current research from Laney et al. 2011 and Halldin et
al. 2014 validate the use of the ILO digital referent images. Both
studies conclude that the results of pneumoconiosis classification
using digital references are comparable to film-based ILO
classifications. Current ILO guidance on radiography for
pneumoconioses and B-reading should be reviewed by the PLHCP
periodically, as needed, on the ILO or NIOSH Web sites (See Section
5 of this Appendix).
2.6. Other Testing. Under the respirable crystalline silica
standards, the PLHCP has the option of ordering additional testing
he or she deems appropriate. Additional tests can be ordered on a
case-by-case basis depending on individual signs or symptoms and
clinical judgment. For example, if an employee reports a history of
abnormal kidney function tests, the PLHCP may want to order a
baseline renal function tests (e.g., serum creatinine and urinalysis).
As indicated above, the PLHCP may order annual TB testing for
silica-exposed employees who are at high risk of developing active TB
infections. Additional tests that PLHCPs may order based on findings
of medical examinations include, but is not limited to, chest
computerized tomography (CT) scan for lung cancer or COPD, testing for
immunologic diseases, and cardiac testing for pulmonary-related heart
disease, such as cor pulmonale.
3. Roles and Responsibilities
3.1. PLHCP. The PLHCP designation refers to "an individual
whose legally permitted scope of practice (i.e., license,
registration, or certification) allows him or her to independently
provide or be delegated the responsibility to provide some or all of
the particular health care services required" by the respirable
crystalline silica standard. The legally permitted scope of practice
for the PLHCP is determined by each State. PLHCPs who perform
clinical services for a silica medical surveillance program should
have a thorough knowledge of respirable crystalline silica-related
diseases and symptoms. Suspected cases of silicosis, advanced COPD,
or other respiratory conditions causing impairment should be
promptly referred to a Board Certified Specialist in Pulmonary
Disease or Occupational Medicine.
Once the medical surveillance examination is completed, the
employer must ensure that the PLHCP explains to the employee the
results of the medical examination and provides the employee with a
written medical report within 30 days of the examination. The
written medical report must contain a statement indicating the
results of the medical examination, including any medical
condition(s) that would place the employee at increased risk of
material impairment to health from exposure to respirable
crystalline silica and any medical conditions that require further
evaluation or treatment. In addition, the PLHCP's written medical
report must include any recommended limitations on the employee's
use of respirators, any recommended limitations on the employee's
exposure to respirable crystalline silica, and a statement that the
employee should be examined by a Board Certified Specialist in
Pulmonary Disease or Occupational medicine if the chest X-ray is
classified as 1/0 or higher by the B Reader, or if referral to a
Specialist is otherwise deemed appropriate by the PLHCP.
The PLHCP should discuss all findings and test results and any
recommendations regarding the employee's health, worksite safety and
health practices, and medical referrals for further evaluation, if
indicated. In addition, it is suggested that the PLHCP offer to
provide the employee with a complete copy of their examination and
test results, as some employees may want this information for their
own records or to provide to their personal physician or a future
PLHCP. Employees are entitled to access their medical records.
Under the respirable crystalline silica standard, the employer
must ensure that the PLHCP provides the employer with a written
medical opinion within 30 days of the employee examination, and that
the employee also gets a copy of the written medical opinion for the
employer within 30 days. The PLHCP may choose to directly provide
the employee a copy of the written medical opinion. This can be
particularly helpful to employees, such as construction employees,
who may change employers frequently. The written medical opinion can
be used by the employee as proof of up-to-date medical surveillance.
The following lists the elements of the written medical report for
the employee and written medical opinion for the employer. (Sample
forms for the written medical report for the employee, the written
medical opinion for the employer, and the written authorization are
provided in Section 7 of this Appendix.)
3.1.1. The written medical report for the employee must include
the following information:
3.1.1.1. A statement indicating the results of the medical
examination, including any medical condition(s) that would place the
employee at increased risk of material impairment to health from
exposure to respirable crystalline silica and any medical conditions
that require further evaluation or treatment;
3.1.1.2. Any recommended limitations upon the employee's use of
a respirator;
3.1.1.3. Any recommended limitations on the employee's exposure
to respirable crystalline silica; and
3.1.1.4. A statement that the employee should be examined by a
Board Certified Specialist in Pulmonary Disease or Occupational
Medicine, where the standard requires or where the PLHCP has
determined such a referral is necessary. The standard requires
referral to a Board Certified Specialist in Pulmonary Disease or
Occupational Medicine for a chest X-ray B reading indicating small
opacities in a profusion of 1/0 or higher, or if the PHLCP
determines that referral to a Specialist is necessary for other
silica-related findings.
3.1.2. The PLHCP's written medical opinion for the employer must
include only the following information:
3.1.2.1. The date of the examination;
3.1.2.2. A statement that the examination has met the
requirements of this section; and
3.1.2.3. Any recommended limitations on the employee's use of
respirators.
3.1.2.4. If the employee provides the PLHCP with written
authorization, the written opinion for the employer shall also
contain either or both of the following:
(1) Any recommended limitations on the employee's exposure to
respirable crystalline silica; and
(2) A statement that the employee should be examined by a Board
Certified Specialist in Pulmonary Disease or Occupational Medicine
if the chest X-ray provided in accordance with this section is
classified as 1/0 or higher by the B Reader, or if referral to a
Specialist is otherwise deemed appropriate.
3.1.2.5. In addition to the above referral for abnormal chest X-
ray, the PLHCP may refer an employee to a Board Certified Specialist
in Pulmonary Disease or Occupational Medicine for other findings of
concern during the medical surveillance examination if these
findings are potentially related to silica exposure.
3.1.2.6. Although the respirable crystalline silica standard
requires the employer to ensure that the PLHCP explains the results
of the medical examination to the employee, the standard does not
mandate how this should be done. The written medical opinion for the
employer could contain a statement that the PLHCP has explained the
results of the medical examination to the employee.
3.2. Medical Specialists. The silica standard requires that all
employees with chest X-ray B readings of 1/0 or higher be referred
to a Board Certified Specialist in Pulmonary Disease or Occupational
Medicine. If the employee has given written authorization for the
employer to be informed, then the employer shall make available a
medical examination by a Specialist within 30 days after receiving
the PLHCP's written medical opinion.
3.2.1. The employer must provide the following information to
the Board Certified Specialist in Pulmonary Disease or Occupational
Medicine:
3.2.1.1. A description of the employee's former, current, and
anticipated duties as they relate to the employee's occupational
exposure to respirable crystalline silica;
3.2.1.2. The employee's former, current, and anticipated levels
of occupational exposure to respirable crystalline silica;
3.2.1.3. A description of any personal protective equipment used
or to be used by the employee, including when and for how long the
employee has used or will use that equipment; and
3.2.1.4. Information from records of employment-related medical
examinations previously provided to the employee and currently
within the control of the employer.
3.2.2. The PLHCP should make certain that, with written
authorization from the employee, the Board Certified Specialist in
Pulmonary Disease or Occupational Medicine has any other pertinent
medical and occupational information necessary for the specialist's
evaluation of the employee's condition.
3.2.3. Once the Board Certified Specialist in Pulmonary Disease
or Occupational Medicine has evaluated the employee, the employer
must ensure that the Specialist explains to the employee the results
of the medical examination and provides the employee with a written
medical report within 30 days of the examination. The employer must
also ensure that the Specialist provides the employer with a written
medical opinion within 30 days of the employee examination. (Sample
forms for the written medical report for the employee, the written
medical opinion for the employer and the written authorization are
provided in Section 7 of this Appendix.)
3.2.4. The Specialist's written medical report for the employee
must include the following information:
3.2.4.1. A statement indicating the results of the medical
examination, including any medical condition(s) that would place the
employee at increased risk of material impairment to health from
exposure to respirable crystalline silica and any medical conditions
that require further evaluation or treatment;
3.2.4.2. Any recommended limitations upon the employee's use of
a respirator; and
3.2.4.3. Any recommended limitations on the employee's exposure
to respirable crystalline silica.
3.2.5. The Specialist's written medical opinion for the employer
must include the following information:
3.2.5.1. The date of the examination; and
3.2.5.2. Any recommended limitations on the employee's use of
respirators.
3.2.5.3. If the employee provides the Board Certified Specialist
in Pulmonary Disease or Occupational Medicine with written
authorization, the written medical opinion for the employer shall
also contain any recommended limitations on the employee's exposure
to respirable crystalline silica.
3.2.5.4. Although the respirable crystalline silica standard
requires the employer to ensure that the Board Certified Specialist
in Pulmonary Disease or Occupational Medicine explains the results
of the medical examination to the employee, the standard does not
mandate how this should be done. The written medical opinion for the
employer could contain a statement that the Specialist has explained
the results of the medical examination to the employee.
3.2.6. After evaluating the employee, the Board Certified
Specialist in Pulmonary Disease or Occupational Medicine should
provide feedback to the PLHCP as appropriate, depending on the
reason for the referral. OSHA believes that because the PLHCP has
the primary relationship with the employer and employee, the
Specialist may want to communicate his or her findings to the PLHCP
and have the PLHCP simply update the original medical report for the
employee and medical opinion for the employer. This is permitted
under the standard, so long as all requirements and time deadlines
are met.
3.3. Public Health Professionals. PLHCPs might refer employees
or consult with public health professionals as a result of silica
medical surveillance. For instance, if individual cases of active TB
are identified, public health professionals from state or local
health departments may assist in diagnosis and treatment of
individual cases and may evaluate other potentially affected
persons, including coworkers. Because silica-exposed employees are
at increased risk of progression from latent to active TB, treatment
of latent infection is recommended. The diagnosis of active TB,
acute or accelerated silicosis, or other silica-related diseases and
infections should serve as sentinel events suggesting high levels of
exposure to silica and may require consultation with the appropriate
public health agencies to investigate potentially similarly exposed
coworkers to assess for disease clusters. These agencies include
local or state health departments or OSHA. In addition, NIOSH can
provide assistance upon request through their Health Hazard
Evaluation program. (See Section 5 of this Appendix)
4. Confidentiality and Other Considerations
The information that is provided from the PLHCP to the employee
and employer under the medical surveillance section of OSHA's
respirable crystalline silica standard differs from that of medical
surveillance requirements in previous OSHA standards. The standard
requires two separate written communications, a written medical
report for the employee and a written medical opinion for the
employer. The confidentiality requirements for the written medical
opinion are more stringent than in past standards. For example, the
information the PLHCP can (and must) include in his or her written
medical opinion for the employer is limited to: The date of the
examination, a statement that the examination has met the
requirements of this section, and any recommended limitations on the
employee's use of respirators. If the employee provides written
authorization for the disclosure of any limitations on the
employee's exposure to respirable crystalline silica, then the PLHCP
can (and must) include that information in the written medical
opinion for the employer as well. Likewise, with the employee's
written authorization, the PLHCP can (and must) disclose the PLHCP's
referral recommendation (if any) as part of the written medical
opinion for the employer. However, the opinion to the employer must
not include information regarding recommended limitations on the
employee's exposure to respirable crystalline silica or any referral
recommendations without the employee's written authorization.
The standard also places limitations on the information that the
Board Certified Specialist in Pulmonary Disease or Occupational
Medicine can provide to the employer without the employee's written
authorization. The Specialist's written medical opinion for the
employer, like the PLHCP's opinion, is limited to (and must
contain): The date of the examination and any recommended
limitations on the employee's use of respirators. If the employee
provides written authorization, the written medical opinion can (and
must) also contain any limitations on the employee's exposure to
respirable crystalline silica.
The PLHCP should discuss the implication of signing or not
signing the authorization with the employee (in a manner and
language that he or she understands) so that the employee can make
an informed decision regarding the written authorization and its
consequences. The discussion should include the risk of ongoing
silica exposure, personal risk factors, risk of disease progression,
and possible health and economic consequences. For instance, written
authorization is required for a PLHCP to advise an employer that an
employee should be referred to a Board Certified Specialist in
Pulmonary Disease or Occupational Medicine for evaluation of an
abnormal chest X-ray (B-reading 1/0 or greater). If an employee does
not sign an authorization, then the employer will not know and
cannot facilitate the referral to a Specialist and is not required
to pay for the Specialist's examination. In the rare case where an
employee is diagnosed with acute or accelerated silicosis, co-
workers are likely to be at significant risk of developing those
diseases as a result of inadequate controls in the workplace. In
this case, the PLHCP and/or Specialist should explain this concern
to the affected employee and make a determined effort to obtain
written authorization from the employee so that the PLHCP and/or
Specialist can contact the employer.
Finally, without written authorization from the employee, the
PLHCP and/or Board Certified Specialist in Pulmonary Disease or
Occupational Medicine cannot provide feedback to an employer
regarding control of workplace silica exposure, at least in relation
to an individual employee. However, the regulation does not prohibit
a PLHCP and/or Specialist from providing an employer with general
recommendations regarding exposure controls and prevention programs
in relation to silica exposure and silica-related illnesses, based
on the information that the PLHCP receives from the employer such as
employees' duties and exposure levels. Recommendations may include
increased frequency of medical surveillance examinations, additional
medical surveillance components, engineering and work practice
controls, exposure monitoring and personal protective equipment. For
instance, more frequent medical surveillance examinations may be a
recommendation to employers for employees who do abrasive blasting
with silica because of the high exposures associated with that
operation.
ACOEM's Code of Ethics and discussion is a good resource to
guide PLHCPs regarding the issues discussed in this section (See
Section 5 of this Appendix).
5. Resources
5.1. American College of Occupational and Environmental Medicine
(ACOEM):
ACOEM Code of Ethics. Accessed at: http://www.acoem.org/codeofconduct.aspx
Raymond, L.W. and Wintermeyer, S. (2006) ACOEM evidenced-based
statement on medical surveillance of silica-exposed workers: Medical
surveillance of workers exposed to crystalline silica. J Occup
Environ Med, 48, 95-101.
5.2. Center for Disease Control and Prevention (CDC)
Tuberculosis Web page: http://www.cdc.gov/tb/default.htm
State TB Control Offices Web page: http://www.cdc.gov/tb/links/tboffices.htm
Tuberculosis Laws and Policies Web page: http://www.cdc.gov/tb/programs/laws/default.htm
CDC. (2013). Latent Tuberculosis Infection: A Guide for Primary
Health Care Providers. Accessed at: http://www.cdc.gov/tb/publications/ltbi/pdf/targetedltbi.pdf
5.3. International Labour Organization
International Labour Office (ILO). (2011) Guidelines for the use of
the ILO International Classification of Radiographs of
Pneumoconioses, Revised edition 2011. Occupational Safety and Health
Series No. 22: http://www.ilo.org/safework/info/publications/WCMS_168260/lang-en/index.htm
5.4. National Institute of Occupational Safety and Health
(NIOSH)
NIOSH B Reader Program Web page. (Information on interpretation of
X-rays for silicosis and a list of certified B-readers). Accessed
at: http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html
NIOSH Guideline (2011). Application of Digital Radiography for the
Detection and Classification of Pneumoconiosis. NIOSH publication
number 2011-198. Accessed at: http://www.cdc.gov/niosh/docs/2011-198/
NIOSH Hazard Review (2002), Health Effects of Occupational Exposure
to Respirable Crystalline Silica. NIOSH publication number 2002-129:
Accessed at http://www.cdc.gov/niosh/docs/2002-129/
NIOSH Health Hazard Evaluations Programs. (Information on the NIOSH
Health Hazard Evaluation (HHE) program, how to request an HHE and
how to look up an HHE report). Accessed at: http://www.cdc.gov/niosh/hhe/
5.5. National Industrial Sand Association:
Occupational Health Program for Exposure to Crystalline Silica in
the Industrial Sand Industry. National Industrial Sand Association,
2nd ed. 2010. Can be ordered at: http://www.sand.org/silica-occupational-health-program
5.6. Occupational Safety and Health Administration (OSHA)
Contacting OSHA: http://www.osha.gov/html/Feed_Back.html
OSHA's Clinicians Web page. (OSHA resources, regulations and links
to help clinicians navigate OSHA's Web site and aid clinicians in
caring for workers.) Accessed at: http://www.osha.gov/dts/oom/clinicians/index.html
OSHA's Safety and Health Topics Web page on Silica. Accessed at:
http://www.osha.gov/dsg/topics/silicacrystalline/index.html
OSHA (2013). Spirometry Testing in Occupational Health Programs:
Best Practices for Healthcare Professionals. (OSHA 3637-03 2013).
Accessed at: http://www.osha.gov/Publications/OSHA3637.pdf
OSHA/NIOSH (2011). Spirometry: OSHA/NIOSH Spirometry InfoSheet (OSHA
3415-1-11). (Provides guidance to employers). Accessed at http://www.osha.gov/Publications/osha3415.pdf
OSHA/NIOSH (2011) Spirometry: OSHA/NIOSH Spirometry Worker Info.
(OSHA 3418-3-11). Accessed at http://www.osha.gov/Publications/osha3418.pdf
5.7. Other
Steenland, K. and Ward E. (2014). Silica: A lung carcinogen. CA
Cancer J Clin, 64, 63-69. (This article reviews not only silica and
lung cancer but also all the known silica-related health effects.
Further, the authors provide guidance to clinicians on medical
surveillance of silica-exposed workers and worker counselling on
safety practices to minimize silica exposure.)
6. References
American Thoracic Society (ATS). Medical Section of the American
Lung Association (1997). Adverse effects of crystalline silica
exposure. Am J Respir Crit Care Med, 155, 761-765.
American Thoracic Society (ATS), Centers for Disease Control (CDC),
Infectious Diseases Society of America (IDSA) (2005). Controlling
Tuberculosis in the United States. Morbidity and Mortality Weekly
Report (MMWR), 54(RR12), 1-81. Accessed at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5412a1.htm
Brown, T. (2009). Silica exposure, smoking, silicosis and lung
cancer--complex interactions. Occupational Medicine, 59, 89-95.
Halldin, C.N., Petsonk, E.L., and Laney, A.S. (2014). Validation of
the International Labour Office digitized standard images for
recognition and classification of radiographs of pneumoconiosis.
Acad Radiol, 21, 305-311.
International Agency for Research on Cancer. (2012). Monographs on
the evaluation of carcinogenic risks to humans: Arsenic, Metals,
Fibers, and Dusts Silica Dust, Crystalline, in the Form of Quartz or
Cristobalite. A Review of Human Carcinogens. Volume 100 C. Geneva,
Switzerland: World Health Organization.
Jalloul, A.S. and Banks D.E. (2007). Chapter 23. The health effects
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7. Sample Forms
Three sample forms are provided. The first is a sample written
medical report for the employee. The second is a sample written
medical opinion for the employer. And the third is a sample written
authorization form that employees sign to clarify what information
the employee is authorizing to be released to the employer.
BILLING CODE 4510-26-P
[FR Doc. 2016-04800 Filed 3-24-16; 8:45 am]
BILLING CODE 4510-26-C
