[Federal Register Volume 78, Number 177 (Thursday, September 12, 2013)]
[Proposed Rules]
[Pages 56273-56504]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-20997]
Vol. 78
Thursday,
No. 177
September 12, 2013
Part II
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; Proposed Rule
Federal Register / Vol. 78 , No. 177 / Thursday, September 12, 2013 /
Proposed Rules
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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: Proposed rule; request for comments.
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SUMMARY: The Occupational Safety and Health Administration (OSHA)
proposes to amend its existing standards for occupational exposure to
respirable crystalline silica. The basis for issuance of this proposal
is a preliminary determination by the Assistant Secretary of Labor for
Occupational Safety and Health that employees exposed to respirable
crystalline silica face a significant risk to their health at the
current permissible exposure limits and that promulgating these
proposed standards will substantially reduce that risk.
This document proposes a new permissible exposure limit, calculated
as an 8-hour time-weighted average, of 50 micrograms of respirable
crystalline silica per cubic meter of air (50 [mu]g/m\3\). OSHA also
proposes other ancillary provisions for employee protection such as
preferred methods for controlling exposure, respiratory protection,
medical surveillance, hazard communication, and recordkeeping. OSHA is
proposing two separate regulatory texts--one for general industry and
maritime, and the other for construction--in order to tailor
requirements to the circumstances found in these sectors.
DATES: Written comments. Written comments, including comments on the
information collection determination described in Section IX of the
preamble (OMB Review under the Paperwork Reduction Act of 1995), must
be submitted (postmarked, sent, or received) by December 11, 2013.
Informal public hearings. The Agency plans to hold informal public
hearings beginning on March 4, 2014, in Washington, DC. OSHA expects
the hearings to last from 9:30 a.m. to 5:30 p.m., local time; a
schedule will be released prior to the start of the hearings. The exact
daily schedule may be amended at the discretion of the presiding
administrative law judge (ALJ). If necessary, the hearings will
continue at the same time on subsequent days. Peer reviewers of OSHA's
Health Effects Literature Review and Preliminary Quantitative Risk
Assessment will be present in Washington, DC to hear testimony on the
second day of the hearing, March 5, 2014; see Section XV for more
information on the peer review process.
Notice of intention to appear at the hearings. Interested persons
who intend to present testimony or question witnesses at the hearings
must submit (transmit, send, postmark, deliver) a notice of their
intention to do so by November 12, 2013. The notice of intent must
indicate if the submitter requests to present testimony in the presence
of the peer reviewers.
Hearing testimony and documentary evidence. Interested persons who
request more than 10 minutes to present testimony, or who intend to
submit documentary evidence, at the hearings must submit (transmit,
send, postmark, deliver) the full text of their testimony and all
documentary evidence by December 11, 2013. See Section XV below for
details on the format and how to file a notice of intention to appear,
submit documentary evidence at the hearing, and request an appropriate
amount of time to present testimony.
ADDRESSES: Written comments. You may submit comments, identified by
Docket No. OSHA-2010-0034, by any of the following methods:
Electronically: You may submit comments and attachments
electronically at http://www.regulations.gov,
which is the Federal e-
Rulemaking Portal. Follow the instructions on-line for making
electronic submissions.
Fax: If your submissions, including attachments, are not longer
than 10 pages, you may fax them to the OSHA Docket Office at (202) 693-
1648.
Mail, hand delivery, express mail, messenger, or courier service:
You must submit your comments to the OSHA Docket Office, Docket No.
OSHA-2010-0034, U.S. Department of Labor, Room N-2625, 200 Constitution
Avenue NW., Washington, DC 20210, telephone (202) 693-2350 (OSHA's TTY
number is (877) 889-5627). Deliveries (hand, express mail, messenger,
or courier service) are accepted during the Department of Labor's and
Docket Office's normal business hours, 8:15 a.m.-4:45 p.m., E.T.
Instructions: All submissions must include the Agency name and the
docket number for this rulemaking (Docket No. OSHA-2010-0034). All
comments, including any personal information you provide, are placed in
the public docket without change and may be made available online at
http://www.regulations.gov.
Therefore, OSHA cautions you about
submitting personal information such as social security numbers and
birthdates.
If you submit scientific or technical studies or other results of
scientific research, OSHA requests (but is not requiring) that you also
provide the following information where it is available: (1)
Identification of the funding source(s) and sponsoring organization(s)
of the research; (2) the extent to which the research findings were
reviewed by a potentially affected party prior to publication or
submission to the docket, and identification of any such parties; and
(3) the nature of any financial relationships (e.g., consulting
agreements, expert witness support, or research funding) between
investigators who conducted the research and any organization(s) or
entities having an interest in the rulemaking. If you are submitting
comments or testimony on the Agency's scientific and technical
analyses, OSHA requests that you disclose: (1) The nature of any
financial relationships you may have with any organization(s) or
entities having an interest in the rulemaking; and (2) the extent to
which your comments or testimony were reviewed by an interested party
prior to its submission. Disclosure of such information is intended to
promote transparency and scientific integrity of data and technical
information submitted to the record. This request is consistent with
Executive Order 13563, issued on January 18, 2011, which instructs
agencies to ensure the objectivity of any scientific and technological
information used to support their regulatory actions. OSHA emphasizes
that all material submitted to the rulemaking record will be considered
by the Agency to develop the final rule and supporting analyses.
Informal public hearings. The Washington, DC hearing will be held
in the auditorium of the U.S. Department of Labor, 200 Constitution
Avenue NW., Washington, DC 20210.
Notice of intention to appear, hearing testimony and documentary
evidence. You may submit (transmit, send, postmark, deliver) your
notice of intention to appear, hearing testimony, and documentary
evidence, identified by docket number (OSHA-2010-0034), by any of the
following methods:
Electronically: http://www.regulations.gov. Follow the instructions
online for electronic submission of materials, including attachments.
Fax: If your written submission does not exceed 10 pages, including
attachments, you may fax it to the OSHA Docket Office at (202) 693-
1648.
Regular mail, express delivery, hand delivery, and messenger and
courier service: Submit your materials to the OSHA Docket Office,
Docket No. OSHA-2010-0034, U.S. Department of Labor, Room N-2625, 200
Constitution Avenue NW., Washington, DC 20210; telephone (202) 693-2350
(TTY number (877) 889-5627). Deliveries (express mail, hand delivery,
and messenger and courier service) are accepted during the Department
of Labor's and OSHA Docket Office's normal hours of operation, 8:15
a.m. to 4:45 p.m., ET.
Instructions: All submissions must include the Agency name and
docket number for this rulemaking (Docket No. OSHA-2010-0034). All
submissions, including any personal information, are placed in the
public docket without change and may be available online at
http://www.regulations.gov. Therefore, OSHA cautions you about submitting
certain personal information, such as social security numbers and
birthdates. Because of security-related procedures, the use of regular
mail may cause a significant delay in the receipt of your submissions.
For information about security-related procedures for submitting
materials by express delivery, hand delivery, messenger, or courier
service, please contact the OSHA Docket Office. For additional
information on submitting notices of intention to appear, hearing
testimony or documentary evidence, see Section XV of this preamble,
Public Participation.
Docket: To read or download comments, notices of intention to
appear, and materials submitted in response to this Federal Register
notice, go to Docket No. OSHA-2010-0034 at http://www.regulations.gov
or to the OSHA Docket Office at the address above. All comments and
submissions are listed in the http://www.regulations.gov index;
however, some information (e.g., copyrighted material) is not publicly
available to read or download through that Web site. All comments and
submissions are available for inspection and, where permissible,
copying at the OSHA Docket Office.
Electronic copies of this Federal Register document are available
at http://www.regulations.gov. Copies also are available from the OSHA
Office of Publications, Room N-3101, U.S. Department of Labor, 200
Constitution Avenue NW., Washington, DC 20210; telephone (202) 693-
1888. This document, as well as news releases and other relevant
information, is also available at OSHA's Web site at http://www.osha.gov.
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. 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 or fax (202) 693-1678. For hearing 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.
SUPPLEMENTARY INFORMATION:
The preamble to the proposed standard on occupational exposure to
respirable crystalline silica follows this outline:
I. Issues
II. Pertinent Legal Authority
III. Events Leading to the Proposed Standards
IV. Chemical Properties and Industrial Uses
V. Health Effects Summary
VI. Summary of the Preliminary Quantitative Risk Assessment
VII. Significance of Risk
VIII. Summary of the Preliminary Economic Analysis and Initial
Regulatory Flexibility Analysis
IX. OMB Review Under the Paperwork Reduction Act of 1995
X. Federalism
XI. State Plans
XII. Unfunded Mandates
XIII. Protecting Children From Environmental Health and Safety Risks
XIV. Environmental Impacts
XV. Public Participation
XVI. Summary and Explanation of the Standards
(a) Scope and Application
(b) Definitions
(c) Permissible Exposure Limit (PEL)
(d) Exposure Assessment
(e) Regulated Areas and Access Control
(f) Methods of Compliance
(g) Respiratory Protection
(h) Medical Surveillance
(i) Communication of Respirable Crystalline Silica Hazards to
Employees
(j) Recordkeeping
(k) Dates
XVII. References
XVIII. Authority and Signature
OSHA currently enforces permissible exposure limits (PELs) for
respirable crystalline silica in general industry, construction, and
shipyards. These PELs were adopted in 1971, shortly after the Agency
was created, and have not been updated since then. The PEL for quartz
(the most common form of crystalline silica) in general industry is a
formula that is approximately equivalent to 100 micrograms per cubic
meter of air ([mu]g/m\3\) as an 8-hour time-weighted average. The PEL
for quartz in construction and shipyards is a formula based on a now-
obsolete particle count sampling method that is approximately
equivalent to 250 [mu]g/m\3\. The current PELs for two other forms of
crystalline silica (cristobalite and tridymite) are one-half of the
values for quartz in general industry. OSHA is proposing a new PEL for
respirable crystalline silica (quartz, cristobalite, and tridymite) of
50 [mu]g/m\3\ in all industry sectors covered by the rule. OSHA is also
proposing other elements of a comprehensive health standard, including
requirements for exposure assessment, preferred methods for controlling
exposure, respiratory protection, medical surveillance, hazard
communication, and recordkeeping.
OSHA's proposal 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 of this preamble, 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 current PELs. These
analyses are presented in a background document entitled "Respirable
Crystalline Silica--Health Effects Literature Review and Preliminary
Quantitative Risk Assessment" and are summarized in this preamble in
Section V, Health Effects Summary, and Section VI, Summary of OSHA's
Preliminary Quantitative Risk Assessment, respectively. The available
evidence indicates that employees exposed to respirable crystalline
silica well below the current PELs are 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 VII, Significance of Risk, in this preamble,
OSHA preliminarily finds that worker exposure to respirable crystalline
silica constitutes a significant risk and that the proposed standard
will substantially reduce this risk.
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
proposed rule is presented in the Preliminary Economic Analysis and
Initial Regulatory Flexibility Analysis (PEA), and is summarized in
Section VIII of this preamble. For general industry and maritime, OSHA
has preliminarily concluded that the proposed PEL of 50 [mu]g/m\3\ is
technologically feasible for all affected industries. For construction,
OSHA has preliminarily determined that the proposed PEL of 50 [mu]g/
m\3\ is feasible in 10 out of 12 of the affected activities. Thus, OSHA
preliminarily concludes that engineering and work practices will be
sufficient to reduce and maintain silica exposures to the proposed PEL
of 50 [mu]g/m\3\ or below in most operations most of the time in the
affected industries. For those few operations within an industry or
activity where the proposed 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 proposed PEL.
OSHA developed quantitative estimates of the compliance costs of
the proposed 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
preliminarily concluded that compliance with the requirements of the
proposed rule would be economically feasible in every affected industry
sector.
OSHA directed Inforum--a not-for-profit corporation (based at the
University of Maryland) well recognized for its macroeconomic
modeling--to run its LIFT (Long-term Interindustry Forecasting Tool)
model of the U.S. economy to estimate the industry and aggregate
employment effects of the proposed silica rule. Inforum developed
estimates of the employment impacts over the ten-year period from 2014-
2023 by feeding OSHA's year-by-year and industry-by-industry estimates
of the compliance costs of the proposed rule into its LIFT model. Based
on the resulting Inforum estimates of employment impacts, OSHA has
preliminarily concluded that the proposed rule would have a
negligible--albeit slightly positive--net impact on aggregate U.S.
employment.
OSHA believes that a new PEL, expressed as a gravimetric
measurement of respirable crystalline silica, will improve compliance
because the PEL is simple and relatively easy to understand. In
comparison, the existing PELs require application of a formula to
account for the crystalline silica content of the dust sampled and, in
the case of the construction and shipyard PELs, a conversion from
particle count to mg/m\3\ as well. OSHA also expects that the approach
to methods of compliance for construction operations included in this
proposal will improve compliance with the standard. This approach,
which specifies exposure control methods for selected construction
operations, gives employers a simple option to identify the control
measures that are appropriate for these operations. Alternately,
employers could conduct exposure assessments to determine if worker
exposures are in compliance with the PEL. In either case, the proposed
rule would provide a basis for ensuring that appropriate measures are
in place to limit worker exposures.
The Regulatory Flexibility Act, as amended by the Small Business
Regulatory Enforcement Fairness Act (SBREFA), requires that OSHA either
certify that a rule would not have a significant economic impact on a
substantial number of small firms or prepare a regulatory flexibility
analysis and hold a Small Business Advocacy Review (SBAR) Panel prior
to proposing the rule. OSHA has determined that a regulatory
flexibility analysis is needed and has provided this analysis in
Section VIII.G of this preamble. OSHA also previously held a SBAR Panel
for this rule. The recommendations of the Panel and OSHA's response to
them are summarized in Section VIII.G of this preamble.
Executive Orders 13563 and 12866 direct agencies to assess all
costs and benefits of available regulatory alternatives. Executive
Order 13563 emphasizes the importance of quantifying both costs and
benefits, of reducing costs, of harmonizing rules, and of promoting
flexibility. This rule has been designated an economically significant
regulatory action under section 3(f)(1) of Executive Order 12866.
Accordingly, the rule has been reviewed by the Office of Management and
Budget, and the remainder of this section summarizes the key findings
of the analysis with respect to costs and benefits of the rule and then
presents several possible alternatives to the rule.
Table SI-1--which, like all the tables in this section, is derived
from material presented in Section VIII of this preamble--provides a
summary of OSHA's best estimate of the costs and benefits of the
proposed rule using a discount rate of 3 percent. As shown, the
proposed rule is estimated to prevent 688 fatalities and 1,585 silica-
related illnesses annually once it is fully effective, and the
estimated cost of the rule is $637 million annually. Also as shown in
Table SI-1, the discounted monetized benefits of the proposed rule are
estimated to be $5.3 billion annually, and the proposed rule is
estimated to generate net benefits of $4.6 billion annually. These
estimates are for informational purposes only and have not been used by
OSHA as the basis for its decision concerning the choice of a PEL or of
other ancillary requirements for this proposed silica rule. The courts
have ruled that OSHA may not use benefit-cost analysis or a criterion
of maximizing net benefits as a basis for setting OSHA health
standards.\1\
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\1\ Am. Textile Mfrs. Inst., Inc. v. Nat'l Cotton Council of
Am., 452 U.S. 490, 513 (1981); Pub. Citizen Health Research Group v.
U.S. Dep't of Labor, 557 F.3d 165, 177 (3d Cir. 2009); Friends of
the Boundary Waters Wilderness v. Robertson, 978 F.2d 1484, 1487
(8th Cir. 1992).
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Both the costs and benefits of Table SI-1 reflect the incremental
costs and benefits associated with achieving full compliance with the
proposed rule. They do not include (a) costs and benefits associated
with current compliance that have already been achieved with regard to
the new requirements, or (b) costs and benefits associated with
achieving compliance with existing requirements, to the extent that
some employers may currently not be fully complying with applicable
regulatory requirements. They also do not include costs or benefits
associated with relatively rare, extremely high exposures that can lead
to acute silicosis.
Subsequent to completion of the PEA, OSHA identified an industry,
hydraulic fracturing, that would be impacted by the proposed standard.
Hydraulic fracturing, sometimes called "fracking," is a process used
to extract natural gas and oil deposits from shale and other tight
geologic formations. A recent cooperative study by the National
Institute for Occupational Safety and Health (NIOSH) and industry
partners identified overexposures to silica among workers conducting
hydraulic fracturing operations. An industry focus group has been
working with OSHA and NIOSH to disseminate information about this
hazard, share best practices, and develop engineering controls to limit
worker exposures to silica. OSHA finds that there are now sufficient
data to provide the main elements of the economic analysis for this
rapidly growing industry and has done so in Appendix A to the PEA.
Based on recent data from the U.S. Census Bureau and industry
sources, OSHA estimates that roughly 25,000 workers in 444
establishments (operated by 200 business entities) in hydraulic
fracturing would be affected by the proposed standard. Annual benefits
of the proposed 50 [mu]g/m\3\ PEL include approximately 12 avoided
fatalities--2.9 avoided lung cancers (mid-point estimate), 6.3
prevented non-cancer respiratory illnesses, and 2.3 prevented cases of
renal failure--and 40.8 avoided cases of silicosis morbidity. Monetized
benefits are expected to range from $75.1 million at a seven percent
discount rate to $105.4 million at a three percent discount rate to
undiscounted benefits of $140.3 million. OSHA estimates that under the
proposed standard, annualized compliance costs for the hydraulic
fracturing industry will total $28.6 million at a discount rate of 7
percent or $26.4 million at a discount rate of 3 percent.
In addition to the proposed rule itself, this preamble discusses
several regulatory alternatives to the proposed OSHA silica standard.
These are presented below as well as in Section VIII of this preamble.
OSHA believes that this presentation of regulatory alternatives serves
two important functions. The first is to explore the possibility of
less costly ways (than the proposed rule) to provide an adequate level
of worker protection from exposure to respirable crystalline silica.
The second is tied to the Agency's statutory requirement, which
underlies the proposed rule, to reduce significant risk to the extent
feasible. If, based on evidence presented during notice and comment,
OSHA is unable to justify its preliminary findings of significant risk
and feasibility as presented in this preamble to the proposed rule, the
Agency must then consider regulatory alternatives that do satisfy its
statutory obligations.
Each regulatory alternative presented here is described and
analyzed relative to the proposed rule. Where appropriate, the Agency
notes whether the regulatory alternative, to be a legitimate candidate
for OSHA consideration, requires evidence contrary to the Agency's
findings of significant risk and feasibility. To facilitate comment,
the regulatory alternatives have been organized into four categories:
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2)
regulatory alternatives that affect proposed ancillary provisions; (3)
a regulatory alternative that would modify the proposed methods of
compliance; and (4) regulatory alternatives concerning when different
provisions of the proposed rule would take effect.
In addition, OSHA would like to draw attention to one possible
modification to the proposed rule, involving methods of compliance,
that the Agency would not consider to be a legitimate regulatory
alternative: To permit the use of respiratory protection as an
alternative to engineering and work practice controls as a primary
means to achieve the PEL.
As described in Section XVI of the preamble, Summary and
Explanation of the Proposed Standards, OSHA is proposing to require
primary reliance on engineering controls and work practices because
reliance on these methods is consistent with long-established good
industrial hygiene practice, with the Agency's experience in ensuring
that workers have a healthy workplace, and with the Agency's
traditional adherence to a hierarchy of preferred controls. The
Agency's adherence to the hierarchy of controls has been successfully
upheld by the courts (see AFL-CIO v. Marshall, 617 F.2d 636 (D.C. Cir.
1979) (cotton dust standard); United Steelworkers v. Marshall, 647 F.2d
1189 (D.C. Cir. 1980), cert. denied, 453 U.S. 913 (1981) (lead
standard); ASARCO v. OSHA, 746 F.2d 483 (9th Cir. 1984) (arsenic
standard); Am. Iron & Steel v. OSHA, 182 F.3d 1261 (11th Cir. 1999)
(respiratory protection standard); Pub. Citizen v. U.S. Dep't of Labor,
557 F.3d 165 (3rd Cir. 2009) (hexavalent chromium standard)).
Engineering controls are reliable, provide consistent levels of
protection to a large number of workers, can be monitored, allow for
predictable performance levels, and can efficiently remove a toxic
substance from the workplace. Once removed, the toxic substance no
longer poses a threat to employees. The effectiveness of engineering
controls does not generally depend on human behavior to the same extent
as personal protective equipment does, and the operation of equipment
is not as vulnerable to human error as is personal protective
equipment.
Respirators are another important means of protecting workers.
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 of these conditions can reduce or eliminate the
protection that respirators provide to some or all of the employees who
wear them.
In addition, use of respirators in the workplace presents other
safety and health concerns. Respirators impose substantial
physiological burdens on some 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.
Psychological conditions, such as claustrophobia, can also impair the
effective use of respirators by employees. These concerns about the
burdens placed on workers by the use of respirators are the basis for
the requirement 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. Although experience in industry shows that most healthy
workers do not have physiological problems wearing properly chosen and
fitted respirators, common health problems can sometime preclude an
employee from wearing a respirator. Safety problems created by
respirators that limit vision and communication must also be
considered. In some difficult or dangerous jobs, effective vision or
communication is vital. Voice transmission through a respirator can be
difficult and fatiguing.
Because respirators are less reliable than engineering and work
practice controls and may create additional problems, OSHA believes
that primary reliance on respirators to protect workers is generally
inappropriate when feasible engineering and work practice controls are
available. 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 current PELs for respirable crystalline silica, also
incorporate this hierarchy of controls. 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 2626-09, Standard Practice
for Controlling Occupational Exposure to Respirable Crystalline Silica
for Construction and Demolition Activities) incorporate the hierarchy
of controls.
It is important to note that the very concept of technological
feasibility for OSHA standards is grounded in the hierarchy of
controls. As indicated in Section II of this preamble, Pertinent Legal
Authority, 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. [See 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 at odds with this framework for evaluating
the technological feasibility of a PEL.
Alternative PELs
OSHA has examined two regulatory alternatives (named Regulatory
Alternatives 1 and 2) that would modify the PEL for
the proposed rule. Under Regulatory Alternative 1, the
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for
all industry sectors covered by the rule, and the action level would be
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action
level at one-half of the PEL). Under Regulatory Alternative 2,
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\
for all industry sectors covered by the rule, while the action level
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately
measuring exposure levels below 25 [mu]g/m\3\).
Tables SI-2 and SI-3 present, for informational purposes, the
estimated costs, benefits, and net benefits of the proposed rule under
the proposed 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 incremental benefits, and the incremental net benefits of
going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of 50 [mu]g/m\3\
and then of going from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25
[mu]g/m\3\. Table
SI-2 breaks out costs by provision and benefits by type of disease and
by morbidity/mortality, while Table SI-3 breaks out costs and benefits
by major industry sector.
[GRAPHIC] [TIFF OMITTED] TP12SE13.001
[GRAPHIC] [TIFF OMITTED] TP12SE13.002
As Tables SI-2 and SI-3 show, going from a PEL of 100 [mu]g/m\3\ to
a PEL of 50 [mu]g/m\3\ would prevent, annually, an additional 357
silica-related fatalities and an additional 632 cases of silicosis.
Based on its preliminary findings that the proposed PEL of 50 [mu]g/
m\3\ significantly reduces worker risk from silica exposure (as
demonstrated by the number of silica-related fatalities and silicosis
cases avoided) and is both technologically and economically
feasible, OSHA cannot propose a PEL of 100 [mu]g/m\3\ (Regulatory
Alternative 1) without violating its statutory obligations
under the OSH Act. However, the Agency will consider evidence that
challenges its preliminary findings.
As previously noted, Tables SI-2 and SI-3 also show the costs and
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
proposed PEL of 50 [mu]g/m\3\ to a PEL of 25 [mu]g/m\3\. Because OSHA
preliminarily 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 proposed rule).
As shown in Tables SI-2 and SI-3, going from a PEL of 50 [mu]g/m\3\
to a PEL of 25 [mu]g/m\3\ would prevent, annually, an additional 335
silica-related fatalities and an additional 186 cases of silicosis.
These estimates support OSHA's preliminarily finding that there is
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\.
However, the Agency has preliminarily determined that a PEL of 25
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically
feasible, and for that reason, cannot propose it without violating its
statutory obligations under the OSH Act.
Regulatory Alternatives That Affect Ancillary Provisions
The proposed rule contains several ancillary provisions (provisions
other than the PEL), including requirements for exposure assessment,
medical surveillance, training, and regulated areas or access control.
As shown in Table SI-2, these ancillary provisions represent
approximately $223 million (or about 34 percent) of the total
annualized costs of the rule of $658 million (using a 7 percent
discount rate). The two most expensive of the ancillary provisions are
the requirements for medical surveillance, with annualized costs of $79
million, and the requirements for exposure monitoring, with annualized
costs of $74 million.
As proposed, the requirements for exposure assessment are triggered
by the action level. As described in this preamble, OSHA has defined
the action level for the proposed standard as an airborne concentration
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an
eight-hour time-weighted average. In this proposal, as in other
standards, the action level has been set at one-half of the PEL.
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 PEL on days when no exposure measurements are made. Even when all
measurements on a given day may fall below the PEL (but are above the
action level), there is some chance that on another day, when exposures
are not measured, the employee's actual exposure may exceed the PEL.
When exposure measurements are above the action level, the employer
cannot be reasonably confident 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.
The action level is also intended to encourage employers to lower
exposure levels in order to avoid the costs associated with the
exposure assessment provisions. Some employers would be able to reduce
exposures below the action level in all work areas, and other employers
in some work areas. As exposures are lowered, the risk of adverse
health effects among workers decreases.
OSHA's preliminary risk assessment indicates that significant risk
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing
significant risk, the decision in the Asbestos case (Bldg. and Constr.
Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (D.C. Cir. 1988))
indicated that OSHA should use its legal authority to impose additional
requirements on employers to further reduce risk when those
requirements will result in a greater than de minimis incremental
benefit to workers' health. OSHA's preliminary conclusion is that the
requirements triggered by the action level will result in a very real
and necessary, but non-quantifiable, further reduction in risk beyond
that provided by the PEL alone. OSHA's choice of proposing an action
level for exposure monitoring of one-half of the PEL is based on the
Agency's successful 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).
As specified in the proposed rule, all workers exposed to
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are
subject to the medical surveillance requirements. This means that the
medical surveillance requirements would apply to 15,172 workers in
general industry and 336,244 workers in construction. OSHA estimates
that 457 possible silicosis cases will be referred to pulmonary
specialists annually as a result of this medical surveillance.
OSHA has preliminarily determined that these ancillary provisions
will: (1) Help ensure that the PEL is not exceeded, and (2) minimize
risk to workers given the very high level of risk remaining at the PEL.
OSHA did not estimate, and the benefits analysis does not include,
monetary benefits resulting from early discovery of illness.
Because medical surveillance and exposure assessment are the two
most costly ancillary provisions in the proposed rule, the Agency has
examined four regulatory alternatives (named Regulatory Alternatives
3, 4, 5, and 6) involving changes
to one or the other of these ancillary provisions. These four
regulatory alternatives are defined below and the incremental cost
impact of each is summarized in Table SI-4. In addition, OSHA is
including a regulatory alternative (named Regulatory Alternative
7) that would remove all ancillary provisions.
[GRAPHIC] [TIFF OMITTED] TP12SE13.003
Under Regulatory Alternative 3, the action level would be
raised from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ while keeping the PEL at 50
[mu]g/m\3\. As a result, exposure monitoring requirements would be
triggered only if workers were exposed
above the proposed PEL of 50 [mu]g/m\3\. As shown in Table SI-4,
Regulatory Option 3 would reduce the annualized cost of the
proposed rule by about $62 million, using a discount rate of either 3
percent or 7 percent.
Under Regulatory Alternative 4, the action level would
remain at 25 [mu]g/m\3\ but medical surveillance would now be triggered
by the action level, not the PEL. As a result, medical surveillance
requirements would be triggered only if workers were exposed at or
above the proposed action level of 25 [mu]g/m\3\. As shown in Table SI-
4, Regulatory Option 4 would increase the annualized cost of
the proposed rule by about $143 million, using a discount rate of 3
percent (and by about $169 million, using a discount rate of 7
percent).
Under Regulatory Alternative 5, the only change to the
proposed rule would be to the medical surveillance requirements.
Instead of requiring workers exposed above the PEL to have a medical
check-up every three years, those workers would be required to have a
medical check-up annually. As shown in Table SI-4, Regulatory Option
5 would increase the annualized cost of the proposed rule by
about $69 million, using a discount rate of 3 percent (and by about $66
million, using a discount rate of 7 percent).
Regulatory Alternative 6 would essentially combine the
modified requirements in Regulatory Alternatives 4 and
5. Under Regulatory Alternative 6, medical
surveillance would be triggered by the action level, not the PEL, and
workers exposed at or above the action level would be required to have
a medical check-up annually rather than triennially. The exposure
monitoring requirements in the proposed rule would not be affected. As
shown in Table SI-4, Regulatory Option 6 would increase the
annualized cost of the proposed rule by about $342 million, using a
discount rate of either 3 percent or 7 percent.
OSHA is not able to quantify the effects of these preceding four
regulatory alternatives on protecting workers exposed to respirable
crystalline silica at levels at or below the proposed PEL of 50 [mu]g/
m\3\--where significant risk remains. The Agency solicits comment on
the extent to which these regulatory options may improve or reduce the
effectiveness of the proposed rule.
The final regulatory alternative affecting ancillary provisions,
Regulatory Alternative 7, would eliminate all of the ancillary
provisions of the proposed rule, including exposure assessment, medical
surveillance, training, and regulated areas or access control. However,
it should be carefully 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 do monitoring, train workers on the use of controls, and set up
some kind of regulated areas to indicate where respirator use would be
required. It is also likely that employers would increasingly follow
the many recommendations to provide medical surveillance for employees.
OSHA has not attempted to estimate the extent to which the costs of
these activities would be reduced if they were not formally required,
but OSHA welcomes comment on the issue.
As indicated previously, OSHA preliminarily finds that there is
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\.
However, the Agency has also preliminarily determined that 50 [mu]g/
m\3\ is the lowest feasible PEL. Therefore, the Agency believes that it
is necessary to include ancillary provisions in the proposed rule to
further reduce the remaining risk. OSHA anticipates that these
ancillary provisions will reduce the risk beyond the reduction that
will be achieved by a new PEL alone.
OSHA's reasons for including each of the proposed ancillary
provisions are detailed in Section XVI of this preamble, Summary and
Explanation of the Standards. In particular, OSHA believes that
requirements for exposure assessment (or alternately, using specified
exposure control methods for selected construction operations) would
provide a basis for ensuring that appropriate measures are in place to
limit worker exposures. Medical surveillance is particularly important
because individuals exposed above the PEL (which triggers medical
surveillance in the proposed rule) are at significant risk of death and
illness. Medical surveillance would allow for identification of
respirable crystalline silica-related adverse health effects at an
early stage so that appropriate intervention measures can be taken.
OSHA believes that regulated areas and access control are important
because they serve to limit exposure to respirable crystalline silica
to as few employees as possible. Finally, OSHA believes that 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.
OSHA expects that the benefits estimated under the proposed rule
will not be fully achieved if employers do not implement the ancillary
provisions of the proposed rule. For example, OSHA believes that the
effectiveness of the proposed rule depends on regulated areas or access
control to further limit exposures and on medical surveillance to
identify disease cases when they do occur.
Both industry and worker groups have recognized that a
comprehensive standard 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 (ASTM, 2006; 2009; BCTD 2001). Moreover, as mentioned
previously, where there is continuing significant risk, the decision in
the Asbestos case (Bldg. and Constr. Trades Dep't, AFL-CIO v. Brock,
838 F.2d 1258, 1274 (D.C. Cir. 1988)) indicated that OSHA should use
its legal authority to impose additional requirements on employers to
further reduce risk when those requirements will result in a greater
than de minimis incremental benefit to workers' health. OSHA
preliminarily concludes that the additional requirements in the
ancillary provisions of the proposed standard clearly exceed this
threshold.
A Regulatory Alternative That Modifies the Methods of Compliance
The proposed standard in general industry and maritime would
require 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 would still
be required to implement them to reduce exposure as much as possible,
and to supplement them with a respiratory protection program. Under the
proposed construction standard, employers would
be given two options for compliance. The first option largely follows
requirements for the general industry and maritime proposed standard,
while the second option outlines, in Table 1 (Exposure Control Methods
for Selected Construction Operations) of the proposed rule, specific
construction exposure control methods. Employers choosing to follow
OSHA's proposed control methods would be considered to be in compliance
with the engineering and work practice control requirements of the
proposed standard, and would not be required to conduct certain
exposure monitoring activities.
One regulatory alternative (Regulatory Alternative 8)
involving methods of compliance would be to eliminate Table 1 as a
compliance option in the construction sector. Under that regulatory
alternative, OSHA estimates that there would be no effect on estimated
benefits but that the annualized costs of complying with the proposed
rule (without the benefit of the Table 1 option in construction) would
increase by $175 million, totally in exposure monitoring costs, using a
3 percent discount rate (and by $178 million using a 7 percent discount
rate), so that the total annualized compliance costs for all affected
establishments in construction would increase from $495 to $670 million
using a 3 percent discount rate (and from $511 to $689 million using a
7 percent discount rate).
Regulatory Alternatives That Affect the Timing of the Standard
The proposed rule would become effective 60 days following
publication of the final rule in the Federal Register. Provisions
outlined in the proposed standard would become enforceable 180 days
following the effective date, with the exceptions of engineering
controls and laboratory requirements. The proposed rule would require
engineering controls to be implemented no later than one year after the
effective date, and laboratory requirements would be required to begin
two years after the effective date.
OSHA will strongly consider alternatives that would reduce the
economic impact of the rule and provide additional flexibility for
firms coming into compliance with the requirements of the rule. The
Agency solicits comment and suggestions from stakeholders, particularly
small business representatives, on options for phasing in requirements
for engineering controls, medical surveillance, and other provisions of
the rule (e.g., over 1, 2, 3, or more years). These options will be
considered for specific industries (e.g., industries where first-year
or annualized cost impacts are highest), specific size-classes of
employers (e.g., employers with fewer than 20 employees), combinations
of these factors, or all firms covered by the rule.
Although OSHA did not explicitly develop or quantitatively analyze
the multitude of potential regulatory alternatives involving longer-
term or more complex phase-ins of the standard, the Agency is
soliciting comments on this issue. Such a particularized, multi-year
phase-in could have several advantages, especially from the viewpoint
of impacts on small businesses. First, it would reduce the one-time
initial costs of the standard by spreading them out over time, a
particularly useful mechanism for small businesses that have trouble
borrowing large amounts of capital in a single year. Second, a
differential phase-in for smaller firms would aid very small firms by
allowing them to gain from the control experience of larger firms.
Finally, a phase-in would be useful in certain industries--such as
foundries, for example--by allowing employers to coordinate their
environmental and occupational safety and health control strategies to
minimize potential costs. However a phase-in would also postpone the
benefits of the standard.
OSHA analyzed one regulatory alternative (Regulatory Alternative
9) involving the timing of the standard which would arise if,
contrary to OSHA's preliminary findings, a PEL of 50 [micro]g/m\3\ with
an action level of 25 [micro]g/m\3\ were found to be technologically
and economically feasible some time in the future (say, in five years),
but not feasible immediately. In that case, OSHA might issue a final
rule with a PEL of 50 [micro]g/m\3\ and an action level of 25 [micro]g/
m\3\ to take effect in five years, but at the same time issue an
interim PEL of 100 [micro]g/m\3\ and an action level of 50 [micro]g/
m\3\ to be in effect until the final rule becomes feasible. Under this
regulatory alternative, and consistent with the public participation
and "look back" provisions of Executive Order 13563, the Agency could
monitor compliance with the interim standard, review progress toward
meeting the feasibility requirements of the final rule, and evaluate
whether any adjustments to the timing of the final rule would be
needed. Under Regulatory Alternative 9, the estimated costs
and benefits would be somewhere between those estimated for a PEL of
100 [micro]g/m\3\ with an action level of 50 [micro]g/m\3\ and those
estimated for a PEL of 50 [micro]g/m\3\ with an action level of 25
[micro]g/m\3\, the exact estimates depending on the length of time
until the final rule is phased in. OSHA emphasizes that this regulatory
alternative is contrary to the Agency's preliminary findings of
economic feasibility and, for the Agency to consider it, would require
specific evidence introduced on the record to show that the proposed
rule is not now feasible but would be feasible in the future.
OSHA requests comments on these regulatory alternatives, including
the Agency's choice of regulatory alternatives (and whether there are
other regulatory alternatives the Agency should consider) and the
Agency's analysis of them.
I. Issues
OSHA requests comment on all relevant issues, including health
effects, risk assessment, significance of risk, technological and
economic feasibility, and the provisions of the proposed regulatory
text. In addition, OSHA requests comments on all of the issues raised
by the Small Business Regulatory Fairness Enforcement Act (SBREFA)
Panel, as summarized in Table VIII-H-4 in Section VIII.H of this
preamble.
OSHA is including Section I on issues at the beginning of the
document to assist readers as they review the proposal and consider any
comments they may want to submit. However, to fully understand the
questions in this section and provide substantive input in response to
them, the parts of the preamble that address these issues in detail
should be read and reviewed. These include: Section V, Health Effects
Summary; Section VI, Summary of the Preliminary Quantitative Risk
Assessment; Section VII, Significance of Risk; Section VIII, Summary of
the Preliminary Economic Analysis and Initial Regulatory Flexibility
Analysis; and Section XVI, Summary and Explanation of the Standards. In
addition, OSHA invites comment on additional technical questions and
discussions of economic issues presented in the Preliminary Economic
Analysis (PEA) of the proposed standards. Section XIX is the text of
the standards and is the final authority on what is required in them.
OSHA requests that comments be organized, to the extent possible,
around the following issues and numbered questions. Comment on
particular provisions should contain a heading setting forth the
section and the paragraph in the standard that the comment is
addressing. Comments addressing more than one section or paragraph will
have correspondingly more headings.
Submitting comments in an organized manner and with clear reference
to the issue raised will enable all participants
to easily see what issues the commenter addressed and how they were
addressed. This is particularly important in a rulemaking such as
silica, which has multiple adverse health effects and affects many
diverse processes and industries. Many commenters, especially small
businesses, are likely to confine their interest (and comments) to the
issues that affect them, and they will benefit from being able to
quickly identify comments on these issues in others' submissions. Of
course, the Agency welcomes comments concerning this proposal that fall
outside the issues raised in this section. However, OSHA is especially
interested in responses, supported by evidence and reasons, to the
following questions:
Health Effects
1. OSHA has described a variety of studies addressing the major
adverse health effects that have been associated with exposure to
respirable crystalline silica. Has OSHA adequately identified and
documented all critical health impairments associated with occupational
exposure to respirable crystalline silica? If not, what adverse health
effects should be added? Are there any additional studies, other data,
or information that would affect the information discussed or
significantly change the determination of material health impairment?
Submit any relevant information, data, or additional studies (or the
citations), and explain your reasoning for recommending the inclusion
of any studies you suggest.
2. Using currently available epidemiologic and experimental
studies, OSHA has made a preliminary determination that respirable
crystalline silica presents risks of lung cancer, silicosis, and non-
malignant respiratory disease (NMRD) as well as autoimmune and renal
disease risks to exposed workers. Is this determination correct? Are
there additional studies or other data OSHA should consider in
evaluating any of these adverse health risks? If so, submit the studies
(or citations) and other data and include your reasons for finding them
germane to determining adverse health effects of exposure to
crystalline silica.
Risk Assessment
3. OSHA has relied upon risk models using cumulative respirable
crystalline silica exposure to estimate the lifetime risk of death from
occupational lung cancer, silicosis, and NMRD among exposed workers.
Additionally, OSHA has estimated the lifetime risk of silicosis
morbidity among exposed workers. Is cumulative exposure the correct
metric for exposure for each of these models? If not, what exposure
measure should be used?
4. Some of the literature OSHA reviewed indicated that the risk of
contracting accelerated silicosis and lung cancer may be non-linear at
very high exposures and may be described by an exposure dose rate
health effect model. OSHA used the more conservative model of
cumulative exposure that is more protective to the worker. Are there
additional data to support or rebut any of these models used by OSHA?
Are there other models that OSHA should consider for estimating lung
cancer, silicosis, or NMRD risk? If so, describe the models and the
rationale for their use.
5. Are there additional studies or sources of data that OSHA should
have included in its qualitative and quantitative risk assessments?
What are these studies and have they been peer-reviewed, or are they
soon to be peer-reviewed? What is the rationale for recommending the
studies or data?
6. Steenland et al. (2001a) pooled data from 10 cohort studies to
conduct an analysis of lung cancer mortality among silica-exposed
workers. Can you provide quantitative lung cancer risk estimates from
other data sources? Have or will the data you submit be peer-reviewed?
OSHA is particularly interested in quantitative risk analyses that can
be conducted using the industrial sand worker studies by McDonald,
Hughes, and Rando (2001) and the pooled center-based case-control study
conducted by Cassidy et al. (2007).
7. OSHA has made a preliminary determination that the available
data are not sufficient or suitable for quantitative analysis of the
risk of autoimmune disease, stomach cancer, and other cancer and non-
cancer health effects. Do you have, or are you aware of, studies, data,
and rationale that would be suitable for a quantitative risk assessment
for these adverse health effects? Submit the studies (or citations),
data, and rationale.
Profile of Affected Industries
8. In its PEA of the proposed rule, summarized in Section VIII of
this preamble, OSHA presents a profile of the affected worker
population. The profile includes estimates of the number of affected
workers by industry sector or operation and job category, and the
distribution of exposures by job category. If your company has
potential worker exposures to respirable crystalline silica, is your
industry among those listed by North American Industry Classification
System (NAICS) code as affected industries? Are there additional data
that will enable the Agency to refine its profile of the worker
population exposed to respirable crystalline silica? If so, provide or
reference such data and explain how OSHA should use these data to
revise the profile.
Technological and Economic Feasibility of the Proposed PEL
9. What are the job categories in which employees are potentially
exposed to respirable crystalline silica in your company or industry?
For each job category, provide a brief description of the operation and
describe the job activities that may lead to respirable crystalline
silica exposure. How many employees are exposed, or have the potential
for exposure, to respirable crystalline silica in each job category in
your company or industry? What are the frequency, duration, and levels
of exposures to respirable crystalline silica in each job category in
your company or industry? Where responders are able to provide exposure
data, OSHA requests that, where available, exposure data be personal
samples with clear descriptions of the length of the sample, analytical
method, and controls in place. Exposure data that provide information
concerning the controls in place are more valuable than exposure data
without such information.
10. Please describe work environments or processes that may expose
workers to cristobalite. Please provide supporting evidence, or explain
the basis of your knowledge.
11. Have there been technological changes within your industry that
have influenced the magnitude, frequency, or duration of exposure to
respirable crystalline silica or the means by which employers attempt
to control such exposures? Describe in detail these technological
changes and their effects on respirable crystalline silica exposures
and methods of control.
12. Has there been a trend within your industry or an effort in
your firm to reduce or eliminate respirable crystalline silica from
production processes, products, and services? If so, please describe
the methods used and provide an estimate of the percentage reduction in
respirable crystalline silica, and the extent to which respirable
crystalline silica is still necessary in specific processes within
product lines or production activities. If you have substituted another
substance(s) for crystalline silica, identify the substance(s) and any
adverse health effects associated with exposure to the substitute
substances, and the cost impact of substitution (cost of materials,
productivity impact). OSHA also
requests that responders describe any health hazards or technical,
economic, or other deterrents to substitution.
13. Has your industry or firm used outsourcing or subcontracting,
or concentrated high exposure tasks in-house, in order to expose fewer
workers to respirable crystalline silica? An example would be
subcontracting for the removal of hardened concrete from concrete
mixing trucks, a task done typically 2-4 times a year, to a specialty
subcontractor. What methods have you used to reduce the number of
workers exposed to respirable crystalline silica and how were they
implemented? Describe any trends related to concentration of high
exposure tasks and provide any supporting information.
14. Does any job category or employee in your workplace have
exposures to respirable crystalline silica that air monitoring data do
not adequately portray due to the short duration, intermittent or non-
routine nature, or other unique characteristics of the exposure?
Explain your response and indicate peak levels, duration, and frequency
of exposures for employees in these job categories.
15. OSHA requests the following information regarding engineering
and work practice controls to control exposure to crystalline silica in
your workplace or industry:
a. Describe the operations and tasks in which the proposed PEL is
being achieved most of the time by means of engineering and work
practice controls.
b. What engineering and work practice controls have been
implemented in these operations and tasks?
c. For all operations and tasks in facilities where respirable
crystalline silica is used, what engineering and work practice controls
have been implemented to control respirable crystalline silica? If you
have installed engineering controls or adopted work practices to reduce
exposure to respirable crystalline silica, describe the exposure
reduction achieved and the cost of these controls.
d. Where current work practices include the use of regulated areas
and hygiene facilities, provide data on the implementation of these
controls, including data on the costs of installation, operation, and
maintenance associated with these controls.
e. Describe additional engineering and work practice controls that
could be implemented in each operation where exposure levels are
currently above the proposed PEL to further reduce exposure levels.
f. When these additional controls are implemented, to what levels
can exposure be expected to be reduced, or what percent reduction is
expected to be achieved?
g. What amount of time is needed to develop, install, and implement
these additional controls? Will the added controls affect productivity?
If so, how?
h. Are there any processes or operations for which it is not
reasonably possible to implement engineering and work practice controls
within one year to achieve the proposed PEL? If so, how much additional
time would be necessary?
16. OSHA requests information on whether there are any specific
conditions or job tasks involving exposure to respirable crystalline
silica where engineering and work practice controls are not available
or are not capable of reducing exposure levels to or below the proposed
PEL most of the time. Provide data and evidence to support your
response.
17. OSHA has made a preliminary determination that compliance with
the proposed PEL can be achieved in most operations most of the time
through the use of engineering and work practice controls. OSHA has
further made a preliminary determination that the proposed rule is
technologically feasible. OSHA solicits comments on the reasonableness
of these preliminary determinations.
Compliance Costs
18. In its PEA (summarized in Section VIII.3 of this preamble),
OSHA developed its estimate of the costs of the proposed rule. The
Agency requests comment on the methodological and analytical
assumptions applied in the cost analysis. Of particular importance are
the unit cost estimates provided in tables and text in Chapter V of the
PEA for all major provisions of the proposed rule. OSHA requests the
following information regarding unit and total compliance costs:
a. If you have installed engineering controls or adopted work
practices to reduce exposure to respirable crystalline silica, describe
these controls and their costs. If you have substituted another
substance(s) for crystalline silica, what has been the cost impact of
substitution (cost of materials, productivity impact)?
b. OSHA has proposed to limit the prohibition on dry sweeping to
situations where this activity could contribute to exposure that
exceeds the PEL and estimated the costs for the use of wet methods to
control dust. OSHA requests comment on the use of wet methods as a
substitute for dry sweeping and whether the prohibition on dry sweeping
is feasible and cost-effective.
c. In its PEA, OSHA presents estimated baseline levels of use of
personal protective equipment (PPE) and the incremental PPE costs
associated with the proposed rule. Are OSHA's estimated PPE compliance
rates reasonable? Are OSHA's estimates of PPE costs, and the
assumptions underlying these estimates, consistent with current
industry practice? If not, provide data and evidence describing current
industry PPE practices.
d. Do you currently conduct exposure monitoring for respirable
crystalline silica? Are OSHA's estimates of exposure assessment costs
reasonable? Would your company require outside consultants to perform
exposure monitoring?
e. Are OSHA's estimates for medical surveillance costs--including
direct medical costs, the opportunity cost of worker time for offsite
travel and for the health screening, and recordkeeping costs--
reasonable?
f. In its PEA, OSHA presents estimated baseline levels of training
and information concerning respirable crystalline silica-related
hazards and the incremental costs associated with the additional
requirements for training and information in the proposed rule. OSHA
requests information on information and training programs addressing
respirable crystalline silica that are currently being implemented by
employers and any necessary additions to those programs that are
anticipated in response to the proposed rule. Are OSHA's baseline
estimates and unit costs for training reasonable and consistent with
current industry practice?
g. Are OSHA's estimated costs for regulated areas and written
access control plans reasonable?
h. The cost estimates in the PEA take the much higher labor
turnover rates in construction into account when calculating costs. For
the proposed rule, OSHA used the most recent BLS turnover rate of 64
percent for construction (versus a turnover rate of 27.2 percent for
general industry). OSHA believes that the estimates in the PEA capture
the effect of high turnover rates in construction and solicits comments
on this issue.
i. Has OSHA omitted any costs that would be incurred to comply with
the proposed rule?
Effects on Small Entities
19. OSHA has considered the effects on small entities raised during
its SBREFA process and addressed these concerns in Chapter VIII of the
PEA. Are there additional difficulties small
entities may encounter when attempting to comply with requirements of
the proposed rule? Can any of the proposal's requirements be deleted or
simplified for small entities, while still providing equivalent
protection of the health of employees? Would allowing additional time
for small entities to comply make a difference in their ability to
comply? How much additional time would be necessary?
Economic Impacts
20. OSHA, in its PEA, has estimated compliance costs per affected
entity and the likely impacts on revenues and profits. OSHA requests
that affected employers provide comment on OSHA's estimate of revenue,
profit, and the impacts of costs for their industry or application
group. The Agency also requests that employers provide data on their
revenues, profits, and the impacts of cost, if available. Are there
special circumstances--such as unique cost factors, foreign
competition, or pricing constraints--that OSHA needs to consider when
evaluating economic impacts for particular applications and industry
groups?
21. OSHA seeks comment as to whether establishments will be able to
finance first-year compliance costs from cash flow, and under what
circumstances a phase-in approach will assist firms in complying with
the proposed rule.
22. The Agency invites comment on potential employment impacts of
the proposed silica rule, and on Inforum's estimates of the employment
impacts of the proposed silica rule on the U.S. economy.
Outreach and Compliance Assistance
23. If the proposed rule is promulgated, OSHA will provide outreach
materials on the provisions of the standards in order to encourage and
assist employers in complying. Are there particular materials that
would make compliance easier for your company or industry? What
materials would be especially useful for small entities? Submit
recommendations or samples.
Benefits and Net Benefits
24. OSHA requests comments on any aspect of its estimation of
benefits and net benefits from the proposed rule, including the
following:
a. The use of willingness-to-pay measures and estimates based on
compensating wage differentials.
b. The data and methods used in the benefits calculations.
c. The choice of discount rate for annualizing the monetized
benefits of the proposed rule.
d. Increasing the monetary value of a statistical life over time
resulting from an increase in real per capita income and the estimated
income elasticity of the value of life.
e. Extending the benefits analysis beyond the 60-year period used
in the PEA.
f. The magnitude of non-quantified health benefits arising from the
proposed rule and methods for better measuring these effects. An
example would be diagnosing latent tuberculosis (TB) in the silica-
exposed population and thereby reducing the risk of TB being spread to
the population at large.
Overlapping and Duplicative Regulations
25. Do any federal regulations duplicate, overlap, or conflict with
the proposed respirable crystalline silica rule? If so, provide or cite
to these regulations.
Alternatives/Ways to Simplify a New Standard
26. Comment on the alternative to new comprehensive standards
(which have ancillary provisions in addition to a permissible exposure
limit) that would be simply improved outreach and enforcement of the
existing standards (which is only a permissible exposure limit with no
ancillary provisions). Do you believe that improved outreach and
enforcement of the existing permissible exposure limits would be
sufficient to reduce significant risks of material health impairment in
workers exposed to respirable crystalline silica? Provide information
to support your position.
27. OSHA solicits comments on ways to simplify the proposed rule
without compromising worker protection from exposure to respirable
crystalline silica. In particular, provide detailed recommendations on
ways to simplify the proposed standard for construction. Provide
evidence that your recommended simplifications would result in a
standard that was effective, to the extent feasible, in reducing
significant risks of material health impairment in workers exposed to
respirable crystalline silica.
Environmental Impacts
28. Submit data, information, or comments pertaining to possible
environmental impacts of adopting this proposal, including any positive
or negative environmental effects and any irreversible commitments of
natural resources that would be involved. In particular, consideration
should be given to the potential direct or indirect impacts of the
proposal on water and air pollution, energy use, solid waste disposal,
or land use. Would compliance with the silica rule require additional
actions to comply with federal, state, or local environmental
requirements?
29. Some small entity representatives advised OSHA that the use of
water as a control measure is limited at their work sites due to
potential water and soil contamination. OSHA believes these limits may
only apply in situations where crystalline silica is found with other
toxic substances such as during abrasive blasting of metal or painted
metal structures, or in locations where state and local requirements
are more restrictive than EPA requirements. OSHA seeks comments on this
issue, including cites to applicable requirements.
a. Are there limits on the use of water controls in your operations
due to environmental regulations? If so, are the limits due to the non-
silica components of the waste stream? What are these non-silica
components?
b. What metals or other toxic chemicals are in your silica waste
streams and what are the procedures and costs to filter out these
metals or other toxic chemicals from your waste streams? Provide
documentation to support your cost estimates.
Provisions of the Standards
Scope
30. OSHA's Advisory Committee on Construction Safety and Health
(ACCSH) has historically advised the Agency to take into consideration
the unique nature of construction work environments by either setting
separate standards or making accommodations for the differences in work
environments in construction as compared to general industry. ASTM, for
example, has separate silica standards of practice for general industry
and construction, E 1132-06 and E 2625-09, respectively. To account for
differences in the workplace environments for these different sectors,
OSHA has proposed separate standards for general industry/maritime and
construction. Is this approach necessary and appropriate? What other
approaches, if any, should the Agency consider? Provide a rationale for
your response.
31. OSHA has proposed that the scope of the construction standard
include all occupational exposures to respirable crystalline silica in
construction work as defined in 29 CFR 1910.12(b) and covered under 29
CFR part 1926, rather
than restricting the application of the rule to specific construction
operations. Should OSHA modify the scope to limit what is covered? What
should be included and what should be excluded? Provide a rationale for
your position. Submit your proposed language for the scope and
application provision.
32. OSHA has not proposed to cover agriculture because the Agency
does not have data sufficient to determine the feasibility of the
proposed PEL in agricultural operations. Should OSHA cover respirable
crystalline silica exposure in agriculture? Provide evidence to support
your position. OSHA seeks information on agricultural operations that
involve respirable crystalline silica exposures, including information
that identifies particular activities or crops (e.g., hand picking
fruit and vegetables, shaking branches and trees, harvesting with
combines, loading storage silos, planting) associated with exposure,
information indicating levels of exposure, and information relating to
available control measures and their effectiveness. OSHA also seeks
information related to the development of respirable crystalline
silica-related adverse health effects and diseases among workers in the
agricultural sector.
33. Should OSHA limit coverage of the rule to materials that
contain a threshold concentration (e.g., 1%) of crystalline silica? For
example, OSHA's Asbestos standard defines "asbestos-containing
material" as any material containing more than 1% asbestos, for
consistency with EPA regulations. OSHA has not proposed a comparable
limitation to the definition of respirable crystalline silica. Is this
approach appropriate? Provide the rationale for your position.
34. OSHA has proposed to cover shipyards under the general industry
standard. Are there any unique circumstances in shipyard employment
that would justify development of different provisions or a separate
standard for the shipyard industry? What are the circumstances and how
would they not be adequately covered by the general industry standard?
Definitions
35. Competent person. OSHA has proposed limited duties for a
competent person relating to establishment of an access control plan.
The Agency did not propose specific requirements for training of a
competent person. Is this approach appropriate? Should OSHA include a
competent person provision? If so, should the Agency add to, modify, or
delete any of the duties of a competent person as described in the
proposed standard? Provide the basis for your recommendations.
36. Has OSHA defined "respirable crystalline silica"
appropriately? If not, provide the definition that you believe is
appropriate. Explain the basis for your response, and provide any data
that you believe are relevant.
37. The proposed rule defines "respirable crystalline silica" in
part as "airborne particles that contain quartz, cristobalite, and/or
tridymite." OSHA believes that tridymite is rarely found in nature or
in the workplace. Please describe any instances of occupational
exposure to tridymite of which you are aware. Please provide supporting
evidence, or explain the basis of your knowledge. Should tridymite be
included in the scope of this proposed rule? Please provide any
evidence to support your position.
PEL and Action Level
38. OSHA has proposed a TWA PEL for respirable crystalline silica
of 50 [micro]g/m\3\ for general industry, maritime, and construction.
The Agency has made a preliminary determination that this is the lowest
level that is technologically feasible. The Agency has also determined
that a PEL of 50 [micro]g/m\3\ will substantially reduce, but not
eliminate, significant risk of material health impairment. Is this PEL
appropriate, given the Agency's obligation to reduce significant risk
of material health impairment to the extent feasible? If not, what PEL
would be more appropriate? The Agency also solicits comment on
maintaining the existing PELs for respirable crystalline silica.
Provide evidence to support your response.
39. OSHA has proposed a single PEL for respirable crystalline
silica (quartz, cristobalite, and tridymite). Is a single PEL
appropriate, or should the Agency maintain separate PELs for the
different forms of respirable crystalline silica? Provide the rationale
for your position.
40. OSHA has proposed an action level for respirable crystalline
silica exposure of 25 [micro]g/m\3\ in general industry, maritime, and
construction. Is this an appropriate approach and level, and if not,
what approach or level would be more appropriate and why? Should an
action level be included in the final rule? Provide the rationale for
your position.
41. If an action level is included in the final rule, which
provisions, if any, should be triggered by exposure above or below the
action level? Provide the basis for your position and include
supporting information.
42. If no action level is included in the final rule, which
provisions should apply to all workers exposed to respirable
crystalline silica? Which provisions should be triggered by the PEL?
Are there any other appropriate triggers for the requirements of the
rule?
Exposure Assessment
43. OSHA is proposing to allow employers to initially assess
employee exposures using air monitoring or objective data. Has OSHA
defined "objective data" sufficiently for an employer to know what
data may be used? If not, submit an alternative definition. Is it
appropriate to allow employers to use objective data to perform
exposure assessments? Explain why or why not.
44. The proposed rule provides two options for periodic exposure
assessment: (1) A fixed schedule option, and (2) a performance option.
The performance option provides employers flexibility in the methods
used to determine employee exposures, but requires employers to
accurately characterize employee exposures. The proposed approach is
explained in the Summary and Explanation for paragraph (d) Exposure
Assessment. OSHA solicits comments on this proposed exposure assessment
provision. Is the wording of the performance option in the regulatory
text understandable and does it clearly indicate what would constitute
compliance with the provision? If not, suggest alternative language
that would clarify the provision, enabling employers to more easily
understand what would constitute compliance.
45. Do you conduct initial air monitoring or do you rely on
objective data to determine respirable crystalline silica exposures? If
objective data, what data do you use? Have you conducted historical
exposure monitoring of your workforce that is representative of current
process technology and equipment use? Describe any other approaches you
have implemented for assessing an employee's initial exposure to
respirable crystalline silica.
46. OSHA is proposing specific requirements for laboratories that
perform analyses of respirable crystalline silica samples. The
rationale is to improve the precision in individual laboratories and
reduce the variability of results between laboratories, so that
sampling results will be more reliable. Are these proposed requirements
appropriate? Will the laboratory requirements add necessary reliability
and reduce inter-lab variability, or might they be overly proscriptive?
Provide the basis for your response.
47. Has OSHA correctly described the accuracy and precision of
existing methods of sampling and analysis for
respirable crystalline silica at the proposed action level and PEL? Can
worker exposures be accurately measured at the proposed action level
and PEL? Explain the basis for your response, and provide any data that
you believe are relevant.
48. OSHA has not addressed the performance of the analytical method
with respect to tridymite since we have found little available data.
Please comment on the performance of the analytical method with respect
to tridymite and provide any data to support your position.
Regulated Areas and Access Control
49. Where exposures exceed the PEL, OSHA has proposed to provide
employers with the option of either establishing a regulated area or
establishing a written access control plan. For which types of work
operations would employers be likely to establish a written access
control plan? Will employees be protected by these options? Provide the
basis for your position and include supporting information.
50. The Summary and Explanation for paragraph (e) Regulated Areas
and Access Control clarifies how the regulated area requirements would
apply to multi-employer worksites in the proposed standard. OSHA
solicits comments on this issue.
51. OSHA is proposing limited requirements for protective clothing
in the silica rule. Is this appropriate? Are you aware of any
situations where more or different protective clothing would be needed
for silica exposures? If so, what type of protective clothing and
equipment should be required? Are there additional provisions related
to protective clothing that should be incorporated into this rule that
will enhance worker protection? Provide the rationale and data that
support your conclusions.
Methods of Compliance
52. In OSHA's cadmium standard (29 CFR 1910.1027(f)(1)(ii),(iii),
and (iv)), the Agency established separate engineering control air
limits (SECALs) for certain processes in selected industries. SECALs
were established 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. In OSHA's chromium (VI)
standard (29 CFR 1910.1026), an exception similar to SECALs was made
for painting airplanes and airplane parts. Should OSHA follow this
approach for respirable crystalline silica in any industries or
processes? If so, in what industries or processes, and at what exposure
levels, should the SECALs be established? Provide the basis for your
position and include supporting information.
53. The proposed standards do not contain a requirement for a
written exposure control program. The two ASTM standards for general
industry and construction (E 1132-06, section 4.2.6, and E 2626-09,
section 4.2.5) state that, where overexposures are persistent (such as
in regulated areas or abrasive blasting operations), a written exposure
control plan shall establish engineering and administrative controls to
bring the area into compliance, if feasible. In addition, the proposed
regulatory language developed by the Building and Construction Trades
Department, AFL-CIO contains provisions for a written program. The ASTM
standards recommend that, where there are regulated areas with
persistent exposures or tasks, tools, or operations that tend to cause
respirable crystalline silica exposure, the employer will conduct a
formal analysis and implement a written control plan (an abatement
plan) on how to bring the process into compliance. If that is not
feasible, the employer is to indicate the respiratory protection and
other protective procedures that will be used to protect employee(s)
permanently or until compliance will be achieved. Should OSHA require
employers to develop and implement a written exposure control plan and,
if so, what should be required to be in the plans?
54. Table 1 in the proposed construction standard specifies
engineering and work practice controls and respiratory protection for
selected construction operations, and exempts employers who implement
these controls from exposure assessment requirements. Is this approach
appropriate? Are there other operations that should be included, or
listed operations that should not be included? Are the specified
control measures effective? Should any other changes be made in Table
1? How should OSHA update Table 1 in the future to account for
development of new technologies? Provide data and information to
support your position.
55. OSHA requests comments on the degree of specificity used for
the engineering and work practice controls for tasks identified in
Table 1, including maintenance requirements. Should OSHA require an
evaluation or inspection checklist for controls? If so, how frequently
should evaluations or inspections be conducted? Provide any examples of
such checklists, along with information regarding their frequency of
use and effectiveness.
56. In the proposed construction standard, when employees perform
an operation listed in Table 1 and the employer fully implements the
engineering controls, work practices, and respiratory protection
described in Table 1 for that operation, the employer is not required
to assess the exposure of the employees performing such operations.
However, the employer must still ensure compliance with the proposed
PEL for that operation. OSHA seeks comment on whether employers fully
complying with Table 1 for an operation should still need to comply
with the proposed PEL for that operation. Instead, should OSHA treat
compliance with Table 1 as automatically meeting the requirements of
the proposed PEL?
57. Are the descriptions of the operations (specific task or tool
descriptions) and control technologies in Table 1 clear and precise
enough so that employers and workers will know what controls they
should be using for the listed operations? Identify the specific
operation you are addressing and whether your assessment is based on
your anecdotal experience or research. For each operation, are the data
and other supporting information sufficient to predict the range of
expected exposures under the controlled conditions? Identify
operations, if any, where you believe the data are not sufficient.
Provide the reasoning and data that support your position.
58. In one specific example from Table 1, OSHA has proposed the
option of using a wet method for hand-operated grinders, with
respirators required only for operations lasting four hours or more.
Please comment and provide OSHA with additional information regarding
wet grinding and the adequacy of this control strategy. OSHA is also
seeking additional information on the second option (commercially
available shrouds and dust collection systems) to confirm that this
control strategy (including the use of half-mask respirators) will
reduce workers' exposure to or below the PEL.
59. For impact drilling operations lasting four hours or less, OSHA
is proposing in Table 1 to allow workers to use water delivery systems
without the use of respiratory protection, as the Agency believes that
this dust suppression method alone will provide
consistent, sufficient protection. Is this control strategy
appropriate? Please provide the basis for your position and any
supporting evidence or additional information that addresses the
appropriateness of this control strategy.
60. In the case of rock drilling, in order to ensure that workers
are adequately protected from the higher exposures that they would
experience working under shrouds, OSHA is proposing in Table 1 that
employers ensure that workers use half-mask respirators when working
under shrouds at the point of operation. Is this specification
appropriate? Please provide the basis for your position and any
supporting evidence or additional information that addresses the
appropriateness of this specification.
61. OSHA has specified a control strategy for concrete drilling in
Table 1 that includes use of a dust collection system as well as a low-
flow water spray. Please provide to OSHA any data that you have that
describes the efficacy of these controls. Is the control strategy in
Table 1 adequate? Please provide the basis for your position and any
supporting evidence or additional information regarding the adequacy of
this control strategy.
62. One of the control options in Table 1 in the proposed
construction standard for rock-crushing operations is local exhaust
ventilation. However, OSHA is aware of difficulties in applying this
control to this operation. Is this control strategy appropriate and
practical for rock-crushing operations? Please provide any information
that you have addressing this issue.
63. OSHA has not proposed to prohibit the use of crystalline silica
as an abrasive blasting agent. Abrasive blasting, similar to other
operations that involve respirable crystalline silica exposures, must
follow the hierarchy of controls, which means, if feasible, that
substitution, engineering, or administrative controls or a combination
of these controls must be used to minimize or eliminate the exposure
hazard. Is this approach appropriate? Provide the basis for your
position and any supporting evidence.
64. The technological feasibility study (PEA, Chapter 4) indicates
that employers use substitutes for crystalline silica in a variety of
operations. If you are aware of substitutes for crystalline silica that
are currently being used in any operation not considered in the
feasibility study, please provide to OSHA relevant information that
contains data supporting the effectiveness, in reducing exposure to
crystalline silica, of those substitutes. Provide any information you
may have on the health hazards associated with exposure to these
substitutes.
65. Information regarding the effectiveness of dust control kits
that incorporate local exhaust ventilation in the railroad
transportation industry in reducing worker exposure to crystalline
silica is not available from the manufacturer. If you have any relevant
information on the effectiveness of such kits, please provide it to
OSHA.
66. The proposed rule prohibits the use of compressed air and dry
brushing and sweeping for cleaning of surfaces and clothing in general
industry, maritime, and construction and promotes the use of wet
methods and HEPA-filter vacuuming as alternatives. Are there any
circumstances in general industry, maritime, or construction work where
dry sweeping is the only kind of sweeping that can be done? Have you
done dry sweeping and, if so, what has been your experience with it?
What methods have you used to minimize dust when dry sweeping? Can
exposure levels be kept below the proposed PEL when dry sweeping is
conducted? How? Provide exposure data for periods when you conducted
dry sweeping. If silica respirable dust samples are not available,
provide real time respirable dust or gravimetric respirable dust data.
Is water available at most sites to wet down dust prior to sweeping?
How effective is the use of water? Does the use of water cause other
problems for the worksite? Are there other substitutes that are
effective?
67. A 30-day exemption from the requirement to implement
engineering and work practice controls was not included in the proposed
standard for construction, and has been removed from the proposed
standard for general industry and maritime. OSHA requests comment on
this issue.
68. The proposed prohibition on employee rotation is explained in
the Summary and Explanation for paragraph (f) Methods of Compliance.
OSHA solicits comment on the prohibition of employee rotation to
achieve compliance when exposure levels exceed the PEL.
Medical Surveillance
69. Is medical surveillance being provided for respirable
crystalline silica-exposed employees at your worksite? If so:
a. How do you determine which employees receive medical
surveillance (e.g., by exposure level or other factors)?
b. Who administers and implements the medical surveillance (e.g.,
company doctor or nurse, outside doctor or nurse)?
c. What examinations, tests, or evaluations are included in the
medical surveillance program? Does your medical surveillance program
include testing for latent TB? Do you include pulmonary function
testing in your medical surveillance program?
d. What benefits (e.g., health, reduction in absenteeism, or
financial) have been achieved from the medical surveillance program?
e. What are the costs of your medical surveillance program? How do
your costs compare with OSHA's estimated unit costs for the physical
examination and employee time involved in the medical surveillance
program? Are OSHA's baseline assumptions and cost estimates for medical
surveillance consistent with your experiences providing medical
surveillance to your employees?
f. How many employees are included in your medical surveillance
program?
g. What NAICS code describes your workplace?
70. Is the content and frequency of proposed examinations
appropriate? If not, how should content and frequency be modified?
71. Is the specified content of the physician or other licensed
health care professional's (PLHCP) written medical opinion sufficiently
detailed to enable the employer to address the employee's needs and
potential workplace improvements, and yet appropriately limited so as
to protect the employee's medical privacy? If not, how could the
medical opinion be improved?
72. Is the requirement for latent TB testing appropriate? Does the
proposed rule implement this requirement in a cost-effective manner?
Provide the data or cite references that support your position.
73. Is the requirement for pulmonary function testing initially and
at three-year intervals appropriate? Is there an alternate strategy or
schedule for conducting follow-up testing that is better? Provide data
or cite references to support your position.
74. Is the requirement for chest X-rays initially and at three-year
intervals appropriate? Is there an alternate strategy or schedule for
conducting follow-up chest X-rays that you believe would be better?
Provide data or cite references to support your position.
75. Are there other tests that should be included in medical
surveillance?
76. Do you provide medical surveillance to employees under another
OSHA standard or as a matter of company policy? If so, describe your
program in terms of what standards the program addresses and such
factors as content and frequency of examinations
and referrals, and reports to the employer.
77. Is exposure for 30 days at or above the PEL the appropriate
number of days to trigger medical surveillance? Should the appropriate
reference for medical monitoring be the PEL or the action level? Is 30
days from initial assignment a reasonable amount of time to provide a
medical exam? Indicate the basis for your position.
78. Are PLHCPs available in your geographic area to provide medical
surveillance to workers who are covered by the proposed rule? For
example, do you have access to qualified X-ray technicians, NIOSH-
certified B-readers, and pulmonary specialists? Describe any
difficulties you may have with regard to access to PLHCPs to provide
surveillance for the rule. Note what you consider your "geographic
area" in responding to this question.
79. OSHA is proposing to allow an "equivalent diagnostic study"
in place of requirements to use a chest X-ray (posterior/anterior view;
no less than 14 x 17 inches and no more than 16 x 17 inches at full
inspiration; interpreted and classified according to the International
Labour Organization (ILO) International Classification of Radiographs
of Pneumoconioses by a NIOSH-certified "B" reader). Two other
radiological test methods, computed tomography (CT) and high resolution
computed tomography (HRCT), could be considered "equivalent diagnostic
studies" under paragraph (h)(2)(iii) of the proposal. However, the
benefits of CT or HRCT should be balanced with risks, including higher
radiation doses. Also, standardized methods for interpreting and
reporting results of CT or HRCT are not currently available. The Agency
requests comment on whether CT and HRCT should be considered
"equivalent diagnostic studies" under the rule. Provide a rationale
and evidence to support your position.
80. OSHA has not included requirements for medical removal
protection (MRP) in the proposed rule, because OSHA has made a
preliminary determination that there are few instances where temporary
worker removal and MRP will be useful. The Agency requests comment as
to whether the respirable crystalline silica rule should include
provisions for the temporary removal and extension of MRP benefits to
employees with certain respirable crystalline silica-related health
conditions. In particular, what medical conditions or findings should
trigger temporary removal and for what maximum amount of time should
MRP benefits be extended? OSHA also seeks information on whether or not
MRP is currently being used by employers with respirable crystalline
silica-exposed workers, and the costs of such programs.
Hazard Communication and Training
81. OSHA has proposed that employers provide hazard information to
employees in accordance with the Agency's Hazard Communication standard
(29 CFR 1910.1200). Compliance with the Hazard Communication standard
would mean that there would be a requirement for a warning label for
substances that contain more than 0.1 percent crystalline silica.
Should this requirement be changed so that warning labels would only be
required of substances more than 1 percent by weight of silica? Provide
the rationale for your position. The Agency also has proposed
additional training specific to work with respirable crystalline
silica. Should OSHA include these additional requirements in the final
rule, or are the requirements of the Hazard Communication standard
sufficient?
82. OSHA is providing an abbreviated training section in this
proposal as compared to ASTM consensus standards (see ASTM E 1132-06,
sections 4.8.1-5). The Hazard Communication standard is comprehensive
and covers most of the training requirements traditionally included in
an OSHA health standard. Do you concur with OSHA that performance-based
training specified in the Hazard Communication standard, supplemented
by the few training requirements of this section, is sufficient in its
scope and depth? Are there any other training provisions you would add?
83. The proposed rule does not alter the requirements for
substances to have warning labels, specify wording for labels, or
otherwise modify the provisions of the OSHA's Hazard Communication
standard. OSHA invites comment on these issues.
Recordkeeping
84. OSHA is proposing to require recordkeeping for air monitoring
data, objective data, and medical surveillance records. The proposed
rule's recordkeeping requirements are discussed in the Summary and
Explanation for paragraph (j) Recordkeeping. The Agency seeks comment
on the utility of these recordkeeping requirements as well as the costs
of making and maintaining these records. Provide evidence to support
your position.
Dates
85. OSHA requests comment on the time allowed for compliance with
the provisions of the proposed rule. Is the time proposed appropriate,
or should there be a longer or shorter phase-in of requirements? In
particular, should requirements for engineering controls and/or medical
surveillance be phased in over a longer period of time (e.g., over 1,
2, 3, or more years)? Should an extended phase-in period be provided
for specific industries (e.g., industries where first-year or
annualized cost impacts are highest), specific size-classes of
employers (e.g., employers with fewer than 20 employees), combinations
of these factors, or all firms covered by the rule? Identify any
industries, processes, or operations that have special needs for
additional time, the additional time required, and the reasons for the
request.
86. OSHA is proposing a two-year start-up period to allow
laboratories time to achieve compliance with the proposed requirements,
particularly with regard to requirements for accreditation and round
robin testing. OSHA also recognizes that requirements for monitoring in
the proposed rule will increase the required capacity for analysis of
respirable crystalline silica samples. Do you think that this start-up
period is enough time for laboratories to achieve compliance with the
proposed requirements and to develop sufficient analytic capacity? If
you think that additional time is needed, please tell OSHA how much
additional time is required and give your reasons for this request.
Appendices
87. Some OSHA health standards include appendices that address
topics such as the hazards associated with the regulated substance,
health screening considerations, occupational disease questionnaires,
and PLHCP obligations. In this proposed rule, OSHA has included a non-
mandatory appendix to clarify the medical surveillance provisions of
the rule. What would be the advantages and disadvantages of including
such an appendix in the final rule? If you believe it should be
included, comment on the appropriateness of the information included.
What additional information, if any, should be included in the
appendix?
II. Pertinent Legal Authority
The purpose of the Occupational Safety and Health Act, 29 U.S.C.
651 et seq. ("the 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 promulgate and enforce occupational safety and
health standards. 29 U.S.C. 654(b) (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 Act provides that in promulgating health standards dealing with
toxic materials or harmful physical agents, such as this proposed
standard regulating occupational exposure to 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 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 Supreme Court has held that before the Secretary can promulgate
any permanent health or safety standard, she must make a threshold
finding that significant risk is present and that such risk can be
eliminated or lessened by a change in practices. Industrial Union
Dept., AFL-CIO v. American Petroleum Institute, 448 U.S. 607, 641-42
(1980) (plurality opinion) ("The Benzene case"). Thus, section
6(b)(5) of the Act requires health standards to reduce significant risk
to the extent feasible. Id.
The Court further observed that what constitutes "significant
risk" is "not a mathematical straitjacket" and must be "based
largely on policy considerations." The Benzene case, 448 U.S. at 655.
The Court gave the example that if,
. . . the odds are one in a billion that a person will die from
cancer . . . the risk clearly could not be considered significant.
On the other hand, if the odds are one in one thousand that regular
inhalation of gasoline vapors that are 2% benzene will be fatal, a
reasonable person might well consider the risk significant. [Id.]
OSHA standards must be both technologically and economically
feasible. United Steelworkers v. Marshall, 647 F.2d 1189, 1264 (D.C.
Cir. 1980) ("The Lead I case"). The Supreme Court has defined
feasibility as "capable of being done." Am. Textile Mfrs. Inst. v.
Donovan, 452 U.S. 490, 509-510 (1981) ("The Cotton Dust case"). The
courts have further 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. [See The Lead I case, 647 F.2d at 1272]
With respect to economic feasibility, the courts have held that a
standard is feasible if it does not threaten massive dislocation to or
imperil the existence of the industry. Id. at 1265. A court must
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
. . . [T]he practical question is whether the standard threatens the
competitive stability of an industry, . . . or whether any intra-
industry or inter-industry discrimination in the standard might
wreck such stability or lead to undue concentration. [Id. (citing
Indus. Union Dep't, AFL-CIO v. Hodgson, 499 F.2d 467 (D.C. Cir.
1974))]
The courts have further observed that granting companies reasonable
time to comply with new PELs may enhance economic feasibility. The Lead
I case at 1265. While a standard must be economically feasible, the
Supreme Court has held that a cost-benefit analysis of health standards
is not required by the Act because a feasibility analysis is required.
The Cotton Dust case, 453 U.S. at 509.
Finally, sections 6(b)(7) and 8(c) of the Act authorize OSHA to
include among a standard's requirements labeling, monitoring, medical
testing, and other information-gathering and -transmittal provisions.
29 U.S.C. 655(b)(7), 657(c).
III. Events Leading to the Proposed Standards
OSHA's current standards for workplace exposure to respirable
crystalline silica were adopted in 1971, pursuant to section 6(a) of
the OSH Act (36 FR 10466, May 29, 1971). Section 6(a) provided that in
the first two years after the effective date of the Act, OSHA had 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 silica, 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, in turn, 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 is based on two
alternative formulas: (1) A particle-count formula, PELmppcf
= 250/(% quartz + 5); and (2) a mass formula proposed by ACGIH in 1968,
PEL = (10 mg/m\3\)/(% quartz + 2). The general industry PELs for
cristobalite and tridymite are one-half of the value calculated from
either of the above two formulas. 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)), which requires particle
counting, is derived from the 1970 ACGIH threshold limit value
(TLV).\2\ The formula based on particle-counting technology used in the
general industry, construction, and shipyard PELs is now considered
obsolete.
---------------------------------------------------------------------------
\2\ 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 current proposal provides
the same PEL for quartz, cristobalite, and tridymite, in general
industry, construction, and shipyards.
---------------------------------------------------------------------------
In 1974, the National Institute for Occupational Safety and Health
(NIOSH) evaluated crystalline silica as a workplace hazard and issued
criteria for a recommended standard on occupational exposure to
crystalline silica (NIOSH, 1974). NIOSH recommended that occupational
exposure to crystalline silica be controlled so that no worker is
exposed to a time-weighted average (TWA) of free (respirable
crystalline) silica greater than 50 [mu]g/m\3\ as determined by a full-
shift sample for up to a 10-hour workday, 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 Advanced Notice of Proposed
Rulemaking (ANPRM) based on the recommendations in the NIOSH criteria
document (39 FR 44771, Dec. 27, 1974). 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." OSHA also set forth the particular
issues of concern on which comments were requested. The Agency did not
pursue a final rule for crystalline silica at that time.
As information 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) evaluated the
available evidence regarding crystalline silica carcinogenicity and
concluded that it was "probably carcinogenic to humans" (IARC, 1987).
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 that "crystalline
silica inhaled in the form of quartz or cristobalite from occupational
sources is carcinogenic to humans" (IARC, 1997).
In 1991, in the Sixth Annual Report on Carcinogens, the U.S.
National Toxicology Program (NTP) concluded that respirable crystalline
silica was "reasonably anticipated to be a human carcinogen" (NTP,
1991). NTP reevaluated the available evidence and concluded, in the
Ninth Report on Carcinogens (NTP, 2000), 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" (NTP,
2000). 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/m\3\ (ACGIH, 2001). ACGIH subsequently lowered the TLV for
crystalline silica to 0.025 mg/m\3\ in 2006, which is the current value
(ACGIH, 2010).
In 1989, OSHA established 8-hour TWA PELs of 0.1 for quartz and
0.05 mg/m\3\ for cristobalite and tridymite, as part of the Air
Contaminants final rule for general industry (54 FR 2332, Jan. 19,
1989). 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, June 12, 1992). However, on July 7 of
the same year, 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)),
which 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 PELs adopted in the 1970s.
In 1994, OSHA launched a process to determine which safety and
health hazards in the U.S. needed 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 held an extensive dialogue with representatives of labor, industry,
professional and academic organizations, the States, voluntary
standards organizations, and the public. The National Advisory
Committee on Occupational Safety and Health and the Advisory Committee
on Construction Safety and Health 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 August 1996, the Agency initiated enforcement efforts under a
Special Emphasis Program (SEP) on crystalline silica. The SEP was
intended to reduce worker silica dust exposures that can cause
silicosis. It included extensive outreach as well as inspections. 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 with employees at risk of developing
silicosis.
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 (DOL, 1996). 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 to reach the
goal of eliminating silicosis. The conference highlighted the best
methods of eliminating silicosis and included problem-solving workshops
on how to prevent the disease in specific industries and job
operations; plenary sessions with senior government, labor, and
corporate officials; and opportunities to meet with safety and health
professionals who had implemented successful silicosis prevention
programs.
In 2003, OSHA examined enforcement data for the years between 1997
and 2002 and identified high rates of noncompliance with the OSHA
respirable crystalline silica PEL, particularly in construction. This
period covers the first five years of the SEP. These enforcement data,
presented in Table 1, indicate that 24 percent of silica samples from
the construction industry and 13 percent from general industry were at
least three times the OSHA PEL. 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.
Table III-1--Results of Time-Weighted Average (TWA) Exposure Respirable Crystalline Silica Samples for
Construction and General Industry
[January 1, 1997-December 31, 2002]
----------------------------------------------------------------------------------------------------------------
Construction Other than construction
---------------------------------------------------------------
Exposure (severity relative to the PEL) Number of Number of
samples Percent samples Percent
----------------------------------------------------------------------------------------------------------------
< 1 PEL......................................... 424 58 2226 66
1 x PEL to < 2 x PEL............................ 86 12 469 14
2 x PEL to < 3 x PEL............................ 48 6 215 6
>= 3 x PEL and higher (3+)...................... 180 24 453 13
---------------------------------------------------------------
Total of samples.................. 738 3363
----------------------------------------------------------------------------------------------------------------
Source: OSHA Integrated Management Information System.
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 (OSHA, 2008). 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 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 PEL continues to occur. These enforcement data,
presented in Table 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.
Table III-2--Results of Time-Weighted Average (TWA) Exposure Respirable Crystalline Silica Samples for
Construction and General Industry
[January 1, 2003-December 31, 2009]
----------------------------------------------------------------------------------------------------------------
Construction Other than construction
---------------------------------------------------------------
Exposure (severity relative to the PEL) Number of Number of
samples Percent samples Percent
----------------------------------------------------------------------------------------------------------------
< 1 PEL......................................... 548 75 948 70
1 x PEL to < 2 x PEL............................ 49 7 107 8
2 x PEL to < 3 x PEL............................ 32 4 46 3
>= 3 x PEL and higher (3+)...................... 103 14 254 19
---------------------------------------------------------------
Total of samples.................. 732 1355
----------------------------------------------------------------------------------------------------------------
Source: OSHA Integrated Management Information System.
Both industry and worker groups have recognized that a
comprehensive standard is needed to protect workers exposed to
respirable crystalline silica. For example, ASTM (originally known as
the American Society for Testing and Materials) has published
recommended 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 exposure assessment, medical
surveillance, and training guidance products.
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, Oct. 29, 1997). In November 1998, OSHA
moved "Occupational Exposure to Crystalline Silica" to the pre-rule
stage in the Regulatory Plan (63 FR 61284, 61303-304, Nov. 9, 1998).
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, May 27,
2003). The SBREFA panel, including representatives from OSHA, the Small
Business Administration (SBA), 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 (OSHA, 2003).
Throughout the crystalline silica rulemaking process, OSHA has
presented information to, and has consulted with, the Advisory
Committee on Construction Safety and Health (ACCSH) and the Maritime
Advisory Committee on Occupational Safety and Health (MACOSH). In
December of 2009, OSHA representatives met with ACCSH to discuss the
rulemaking and receive their comments and recommendations. On December
11, ACCSH passed motions supporting the concept of Table 1 in the draft
proposed construction rule and recognizing that the controls listed in
Table 1 are effective. (As discussed with regard to paragraph (f) of
the proposed rule, Table 1 presents specified control measures for
selected construction operations.) 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, Jan. 14, 2005). 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 this
Notice of Proposed Rulemaking. 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 this proposed rule. OSHA will schedule
time during the informal rulemaking hearing for participants to testify
on the Health Effects analysis and Preliminary Quantitative Risk
Assessment in the presence of peer reviewers and will request the peer
reviewers to submit any amended final comments they may wish to add to
the record. The Agency will consider amended final comments received
from the peer reviewers during development of a final rule and will
make them publicly available as part of the silica rulemaking record.
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 (IARC, 1997).
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 (Hurlbut, 1966).
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 (Bureau of
Mines, 1992).
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 (IARC, 1997).
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 (Bureau of Mines, 1992). Alpha quartz is
used in many products throughout various industries and is a common
component of building materials (Madsen et al., 1995). Common trade
names for commercially available quartz include: CSQZ, DQ 12, Min-U-
Sil, Sil-Co-Sil, Snowit, Sykron F300, and Sykron F600 (IARC, 1997).
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 (IARC, 1997). 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 (Smith, 1998).
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.
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 (IARC, 1997).
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 (IARC, 1997).
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.
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
(Madsen et al., 1995).
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. Silica is also used
to manufacture artificial stone products used as bathroom and kitchen
countertops, and the silica content in those products can exceed 93
percent (Kramer et al., 2012).
There are over thirty 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, grinding and tuckpointing, operating heavy
equipment, and road work. A more detailed discussion of the industries
affected by the proposed standard is presented in Section VIII of this
preamble. Crystalline silica exposures can also occur in mining, and in
agriculture during plowing and harvesting.
V. Health Effects Summary
This section presents a summary of OSHA's review of the health
effects literature for respirable crystalline silica. OSHA's full
analysis is contained in Section I of the background document entitled
"Respirable Crystalline Silica--Health Effects Literature Review and
Preliminary Quantitative Risk Assessment," which has been placed in
rulemaking docket OSHA-2010-0034. OSHA's review of the literature on
the adverse effects associated with exposure to crystalline silica
covers the following topics:
(1) Silicosis (including relevant data from U.S. disease
surveillance efforts);
(2) Lung cancer and cancer at other sites;
(3) Non-malignant respiratory disease (other than silicosis);
(4) Renal and autoimmune effects; and
(5) Physical factors affecting the toxicity of crystalline silica.
The purpose of the Agency's scientific review is to present OSHA's
preliminary findings on the nature of the hazards presented by exposure
to respirable crystalline silica, and to present an adequate basis for
the quantitative risk assessment section to follow. OSHA's review
reflects the relevant literature identified by the Agency through
previously published reviews, literature searches, and contact with
outside experts. Most of the evidence that describes the health risks
associated with exposure to silica consists of epidemiological studies
of worker populations; in addition, animal and in vitro studies on mode
of action and molecular toxicology are also described. OSHA's review of
the silicosis literature focused on a few particular issues, such as
the factors that affect progression of the disease and the relationship
between the appearance of radiological abnormalities indicative of
silicosis and pulmonary function decline. Exposure to respirable
crystalline silica is the only known cause of silicosis and there are
literally thousands of research papers and case studies describing
silicosis among working populations. OSHA did not review every one of
these studies, because many of them do not relate to the issues that
are of interest to OSHA.
OSHA's health effects literature review addresses exposure only to
airborne respirable crystalline silica since there is no evidence that
dermal or oral exposure presents a hazard to workers. This review is
also confined to issues related to inhalation of respirable dust, which
is generally defined as particles that are capable of reaching the gas-
exchange region of the lung (i.e., particles less than 10 [mu]m in
aerodynamic diameter). The available studies include populations
exposed to quartz or cristobalite, the two forms of crystalline silica
most often encountered in the workplace. OSHA was unable to identify
any relevant epidemiological literature concerning a third polymorph,
tridymite, which is also currently regulated by OSHA and included in
the scope of OSHA's proposed crystalline silica standard.
OSHA's approach in this review is based on a weight-of-evidence
approach, in which studies (both positive and negative) are evaluated
for their overall quality, and causal inferences are drawn based on a
determination of whether there is substantial evidence that exposure
increases the risk of a particular effect. Factors considered in
assessing the quality of studies include size of the cohort studied and
power of the study to detect a sufficiently low level of disease risk;
duration of follow-up of the study population; potential for study bias
(such as selection bias in case-control studies or survivor effects in
cross-sectional studies); and adequacy of underlying exposure
information for examining exposure-response relationships.
Studies were deemed suitable
for inclusion in OSHA's Preliminary Quantitative Risk Assessment where
there was adequate quantitative information on exposure and disease
risks and the study was judged to be sufficiently high quality
according to the criteria described above. The Preliminary Quantitative
Risk Assessment is included in Section II of the background document
and is summarized in Section VI of this preamble.
A draft health effects review document was submitted for external
scientific peer review in accordance with the Office of Management and
Budget's "Final Information Quality Bulletin for Peer Review" (OMB,
2004). A summary of OSHA's responses to the peer reviewers' comments
appears in Section III of the background document. Since the draft
health effects review document was submitted for external scientific
peer review, new studies or reviews examining possible associations
between occupational exposure to respirable crystalline silica and lung
cancer have been published. OSHA's analysis of that new information is
presented in a supplemental literature review and is available in the
docket (OSHA, 2013).
A. Silicosis and Disease Progression
1. Pathology and Diagnosis
Silicosis is a progressive disease in which accumulation of
respirable crystalline silica particles causes an inflammatory reaction
in the lung, leading to lung damage and scarring, and, in some cases,
progresses to complications resulting in disability and death. 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 usually more than 20 years (Becklake, 1994; Balaan and Banks, 1992).
In both the accelerated and chronic form 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). 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), and there is no specific treatment
for silicosis (Davis, 1996; Banks, 2005). Unlike chronic silicosis, the
acute form of the disease almost certainly arises from exposures well
in excess of current OSHA standards and presents a different
pathological picture, one of pulmonary alveolar proteinosis.
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. The scarring can be detected by chest x-ray or
computerized tomography (CT) when the lesions become large enough to
appear as visible opacities. The result is restriction of lung volumes
and decreased pulmonary compliance with concomitant reduced gas
transfer (Balaan and Banks, 1992). Early stages of chronic silicosis
can be referred to as either simple or nodular silicosis; later stages
are referred to as either pulmonary massive fibrosis (PMF),
complicated, or advanced silicosis.
The clinical diagnosis of silicosis has three requisites (Balaan
and Banks, 1992; Banks, 2005). The first is the recognition by the
physician that exposure to crystalline silica adequate to cause this
disease has occurred. The second is the presence of chest radiographic
abnormalities consistent with silicosis. The third is the absence of
other illnesses that could resemble silicosis on chest radiograph,
e.g., pulmonary fungal infection or miliary tuberculosis. To describe
the presence and severity of silicosis from chest x-ray films or
digital radiographic images, a standardized system exists to classify
the opacities seen on chest radiographs (the International Labor
Organization (ILO) International Classification of Radiographs of the
Pneumoconioses (ILO, 1980, 2002, 2011; Merchant and Schwartz, 1998;
NIOSH, 2011). This system standardizes the description of chest x-ray
films or digital radiographic images with respect to the size, shape,
and density of opacities, which together indicate the severity and
extent of lung involvement. The density of opacities seen on chest x-
ray films or digital radiographic images is classified on a 4-point
major category scale (0, 1, 2, or 3), with each major category divided
into three subcategories, giving a 12-point 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.) Major
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. 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). In addition, an assessment of pulmonary function, though not
itself necessary to confirm a diagnosis of silicosis, is important to
evaluate whether the individual has impaired lung function.
Although chest x-ray is typically used to examine workers exposed
to respirable crystalline silica for the presence of silicosis, it is a
fairly insensitive tool for detecting lung fibrosis (Hnizdo et al.,
1993; Craighead and Vallyathan, 1980; Rosenman et al., 1997). To
address the low sensitivity of chest x-rays for detecting silicosis,
Hnizdo et al. (1993) 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.
Newer imaging technologies with both research and clinical
applications include computed tomography, and high resolution
tomography. High- resolution computed tomography (HRCT) uses thinner
image slices and a different reconstruction algorithm to improve
spatial resolution over CT. Recent studies of high-resolution
computerized tomography (HRCT) have found HRCT to be superior to chest
x-ray imaging for detecting small opacities and for identifying PMF
(Sun et al., 2008; Lopes et al., 2008; Blum et al., 2008).
The causal relationship between exposure to crystalline silica and
silicosis has long been accepted in the scientific and medical
communities. Of greater interest to OSHA is the quantitative
relationship between exposure to crystalline silica and development of
silicosis. A large number of cross-sectional and retrospective studies
have been conducted to evaluate this relationship (Kreiss and Zhen,
1996; Love et al., 1999; Ng and Chan, 1994; Rosenman et al., 1996;
Hughes et al., 1998; Muir et al., 1989a, 1989b; Park et al., 2002; Chen
et al., 2001; Hnizdo and Sluis-Cremer, 1993; Miller et al., 1998;
Buchanan et al., 2003; Steenland and Brown, 1995b). In general, these
studies, particularly those that included retirees, have found a risk
of radiological silicosis (usually defined as x-ray films classified
ILO major category 1 or greater) among workers exposed near the range
of cumulative exposure permitted by current exposure limits. These
studies are presented in detail in OSHA's Preliminary Quantitative Risk
Assessment (Section II of the background document and summarized in
Section VI of this preamble).
2. Silicosis in the United States
Unlike most occupational diseases, surveillance statistics are
available that provide information on the prevalence of 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; the WoRLD Surveillance Report is compiled
from the most recent data from the WoRLD System (NIOSH, 2008c).
National statistics on mortality associated with occupational lung
diseases are also compiled in the National Occupational Respiratory
Mortality System (NORMS, available on the Internet at
http://webappa.cdc.gov/ords/norms.html),
a searchable database administered by
NIOSH. In addition, NIOSH published a recent review of mortality
statistics in its MMWR Report Silicosis Mortality, Prevention, and
Control--United States, 1968-2002 (CDC, 2005). For each of these
sources, data are compiled from death certificates reported to state
vital statistics offices, which are collected by the National Center
for Health Statistics (NCHS). Data on silicosis morbidity are available
from only a few states that administer occupational disease
surveillance systems, and from data on hospital discharges. OSHA
believes that the mortality and morbidity statistics compiled in these
sources and summarized below indicate that silicosis remains a
significant occupational health problem in the U.S. today.
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). From
1968 to 2002, the number of silicosis deaths decreased from 1,157 (8.91
per million persons aged =15 years) to 148 (0.66 per
million), corresponding to a 93-percent decline in the overall
mortality rate. In its most recent WoRLD Report (NIOSH, 2008c), NIOSH
reported that the number of silicosis deaths in 2003, 2004, and 2005
were 179, 166, and 161, respectively, slightly higher than that
reported in 2002. The number of silicosis deaths identified each year
has remained fairly constant since the late 1990's.
NIOSH cited two main factors that were likely responsible for the
declining trend in silicosis mortality since 1968. First, many of the
deaths in the early part of the study period occurred among persons
whose main exposure to crystalline silica dust probably occurred before
introduction of national standards for silica dust exposure established
by OSHA and the Mine Safety and Health Administration (MSHA) (i.e.,
permissible exposure limits (PELs)) that likely led to reduced silica
dust exposure. Second, there has been declining employment in heavy
industries (e.g., foundries) where silica exposure was prevalent (CDC,
2005). Although the factors described by NIOSH are reasonable
explanations for the steep reduction in silicosis-related mortality, it
should be emphasized that the surveillance data are insufficient for
the analysis of residual risk associated with current occupational
exposure limits for crystalline silica. Analyses designed to explore
this question must make use of appropriate exposure-response data, as
is presented in OSHA's Preliminary Quantitative Risk Assessment
(summarized in Section VI of this preamble).
Although the number of deaths from silicosis overall has declined
since 1968, the number of silicosis-associated deaths reported among
persons aged 15 to 44 had not declined substantially prior to 1995 (CDC
1998). Unfortunately, it is not known to what extent these deaths among
younger workers were caused by acute or accelerated forms of silicosis.
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, or the end of a working life,
there were 3,045 years of life lost to age 65, with an average of 9.9
years of life lost from a working life (NIOSH, 2008c).
Data on the prevalence of silicosis morbidity are available from
only three states (Michigan, Ohio, and New Jersey) that have
administered disease surveillance programs over the past several years.
These programs rely primarily on hospital discharge records, reporting
of cases from the medical community, workers' compensation programs,
and death certificate data. For the reporting period 1993-2002, the
last year for which data are available, three states (Michigan, New
Jersey and Ohio) recorded 879 cases of silicosis (NIOSH 2008c).
Hospital discharge records represent the primary ascertainment source
for all three states. It should be noted that hospital discharge
records most likely include cases of acute silicosis or very advance
chronic silicosis since it is unlikely that there would be a need for
hospitalization in cases with early radiographic signs of silicosis,
such as for an ILO category 1/0 x-ray. Nationwide hospital discharge
data compiled by NIOSH (2008c) and the Council of State and Territorial
Epidemiologists (CSTE, 2005) indicates that there are at least 1,000
hospitalizations each year due to silicosis.
Data on silicosis mortality and morbidity are likely to understate
the true impact of exposure of U.S. workers to crystalline silica. This
is in part due to underreporting that is characteristic of passive
case-based disease surveillance systems that rely on the health care
community to generate records (Froines et al., 1989). Health care
professionals play the main role in such surveillance by virtue of
their unique role in recognizing and diagnosing diseases, but most
health care professionals do not take occupational histories (Goldman
and Peters, 1981; Rutstein et al., 1983). In addition to the lack of
information about exposure histories, difficulty in recognizing
occupational illnesses that have long latency periods, like silicosis,
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) estimated that the true
incidence of silicosis mortality and morbidity were understated by a
factor of between 2.5 and 5, and that there were estimated to be from
3,600 to 7,300 new cases of silicosis occurring in the U.S. annually
between 1987 and 1996. Taken with the surveillance data presented
above, OSHA believes that exposure to crystalline silica remains a
cause of significant mortality and morbidity in the U.S.
3. Progression of Silicosis and Its Associated Impairment
As described above, silicosis is a progressive lung disease that is
usually first detected by the appearance of a diffuse nodular fibrosis
on chest x-ray films. To evaluate the clinical
significance of radiographic signs of silicosis, OSHA reviewed several
studies that have examined how exposure affects progression of the
disease (as seen by chest radiography) as well as the relationship
between radiologic findings and pulmonary function. The following
summarizes OSHA's preliminary findings from this review.
Of the several studies reviewed by OSHA that documented silicosis
progression in populations of workers, four studies (Hughes et al.,
1982; Hessel et al., 1988; Miller et al., 1998; Ng et al., 1987a)
included quantitative exposure data that were based on either current
or historical measurements of respirable quartz. The exposure variable
most strongly associated in these studies with progression of silicosis
was cumulative respirable quartz (or silica) exposure (Hessel et al.,
1988; Hughes et al., 1982; Miller et al., 1998; Ng et al., 1987a),
though both average concentration of respirable silica (Hughes et al.,
1982; Ng et al., 1987a) and duration of employment in dusty jobs have
also been found to be associated with the progression of silicosis
(Hughes et al., 1982; Ogawa et al., 2003).
The study reflecting average exposures most similar to current
exposure conditions is that of Miller et al. (1998), which followed a
group of 547 British coal miners in 1990-1991 to evaluate chest x-ray
changes that had occurred after the mines closed in 1981. This study
had data available from chest x-rays taken during health surveys
conducted between 1954 and 1978, as well as data from extensive
exposure monitoring conducted between 1964 and 1978. The mean and
maximum cumulative exposure reported in the study correspond to average
concentrations of 0.12 and 0.55 mg/m\3\, respectively, over the 15-year
sampling period. However, between 1971 and 1976, workers experienced
unusually high concentrations of respirable quartz in one of the two
coal seams in which the miners worked. For some occupations, quarterly
mean quartz concentrations ranged from 1 to 3 mg/m\3\, and for a brief
period, concentrations exceeded 10 mg/m\3\ for one job. Some of these
high exposures likely contributed to the extent of disease progression
seen in these workers; in its Preliminary Quantitative Risk Assessment,
OSHA reviewed a study by Buchanan et al. (2003), who found that short-
term exposures to high (>2 mg/m\3\) concentrations of silica can
increase the silicosis risk by 3-fold over what would be predicted by
cumulative exposure alone (see Section VI).
Among the 504 workers whose last chest x-ray was classified as ILO
0/0 or 0/1, 20 percent had experienced onset of silicosis (i.e., chest
x-ray was classified as ILO 1/0 by the time of follow up in 1990-1991),
and 4.8 percent progressed to at least category 2. However, there are
no data available to continue following the progression of this group
because there have been no follow-up surveys of this cohort since 1991.
In three other studies examining the progression of silicosis,
(Hessel et al., 1988; Hughes et al., 1982; Ng et al., 1987a) cohorts
were comprised of silicotics (individuals already diagnosed with
silicosis) that were followed further to evaluate disease progression.
These studies reflect exposures of workers to generally higher average
concentrations of respirable quartz than are permitted by OSHA's
current exposure limit. Some general findings from this body of
literature follow. First, size of opacities on initial radiograph is a
determinant for further progression. Individuals with large opacities
on initial chest radiograph have a higher probability of further
disease progression than those with small opacities (Hughes et al.,
1982; Lee, et al., 2001; Ogawa et al., 2003). Second, although
silicotics who continue to be exposed are more likely to progress than
silicotics who are not exposed (Hessel et al., 1988), once silicosis
has been detected there remains a likelihood of progression in the
absence of additional exposure to silica (Hessel et al., 1988; Miller
et al., 1998; Ogawa, et al., 2003; Yang et al., 2006). There is some
evidence in the literature that the probability of progression is
likely to decline over time following the end of the exposure, although
this observation may also reflect a survivor effect (Hughes et al.,
1982; Lee et al., 2001). In addition, of borderline statistical
significance was the association of tuberculosis with increased
likelihood of silicosis progression (Lee et al., 2001).
Of the four studies reviewed by OSHA that provided quantitative
exposure information, two studies (Miller et al., 1998; Ng et al.,
1987a) provide the information most relevant to current exposure
conditions. The range of average concentration of respirable
crystalline silica to which workers were exposed in these studies (0.12
to 0.48 mg/m\3\, respectively) is relatively narrow and is of
particular interest to OSHA because current enforcement data indicate
that exposures in this range or not much lower are common today,
especially in construction and foundries, and sandblasting operations.
These studies reported the percentage of workers whose chest x-rays
show signs of progression at the time of follow-up; the annual rate at
which workers showed disease progression were similar, 2 percent and 6
percent, respectively.
Several cross-sectional and longitudinal studies have examined the
relationship between progressive changes observed on radiographs and
corresponding declines in lung-function parameters. In general, the
results are mixed: some studies have found that pulmonary function
losses correlate with the extent of fibrosis seen on chest x-ray films,
and others have not found such correlations. The lack of a correlation
in some studies between degree of fibrotic profusion seen on chest x-
rays and pulmonary function have led some to suggest that pulmonary
function loss is an independent effect of exposure to respirable
crystalline silica, or may be a consequence of emphysematous changes
that have been seen in conjunction with radiographic silicosis.
Among studies that have reported finding a relationship between
pulmonary function and x-ray abnormalities, Ng and Chan (1992) found
that forced expiratory volume (FEV1) and forced vital
capacity (FVC) were statistically significantly lower for workers whose
x-ray films were classified as ILO profusion categories 2 and 3, but
not among workers with ILO category 1 profusion compared to those with
a profusion score of 0/0. As expected, highly significant reductions in
FEV1, FVC, and FEV1/FVC were noted in subjects
with large opacities. The authors concluded that chronic simple
silicosis, except that classified as profusion category 1, is
associated with significant lung function impairment attributable to
fibrotic disease.
Similarly, Moore et al. (1988) also found chronic silicosis to be
associated with significant lung function loss, especially among
workers with chest x-rays classified as ILO profusion categories 2 and
3. For those classified as category 1, lung function was not
diminished. B[eacute]gin et al. (1988) also found a correlation between
decreased lung function (FVC and the ratio of FEV1/FVC) and
increased profusion and coalescence of opacities as determined by CT
scan. This study demonstrated increased impairment among workers with
higher imaging categories (3 and 4), as expected, but also impairment
(significantly reduced expiratory flow rates) among persons with more
moderate pulmonary fibrosis (group 2).
In a population of gold miners, Cowie (1998) found that lung
function declined more rapidly in men with silicosis than those without. In
addition to the 24 ml./yr. decrements expected due to aging, this study
found an additional loss of 8 ml. of FEV1 per year would be
expected from continued exposure to dust in the mines. An earlier
cross-sectional study by these authors (Cowie and Mabena, 1991), which
examined 1,197 black underground gold miners who had silicosis, found
that silicosis (analyzed as a continuous variable based on chest x-ray
film classification) was associated with reductions in FVC,
FEV1, FEV1/FVC, and carbon monoxide diffusing
capacity (DLco), and these relationships persisted after
controlling for duration and intensity of exposure and smoking.
In contrast to these studies, other investigators have reported
finding pulmonary function decrements in exposed workers independent of
radiological evidence of silicosis. Hughes et al. (1982) studied a
representative sample of 83 silicotic sandblasters, 61 of whom were
followed for one to seven years. A multiple regression analysis showed
that the annual reductions in FVC, FEV1 and DLco
were related to average silica concentrations but not duration of
exposure, smoking, stage of silicosis, or time from initial exposure.
Ng et al. (1987b) found that, among male gemstone workers in Hong Kong
with x-rays classified as either Category 0 or 1, declines in
FEV1 and FVC were not associated with radiographic category
of silicosis after adjustment for years of employment. The authors
concluded that there was an independent effect of respirable dust
exposure on pulmonary function. In a population of 61 gold miners,
Wiles et al. (1992) also found that radiographic silicosis was not
associated with lung function decrements. In a re-analysis and follow-
up of an earlier study, Hnizdo (1992) found that silicosis was not a
significant predictor of lung function, except for FEV1 for
non-smokers.
Wang et al. (1997) observed that silica-exposed workers (both
nonsmokers and smokers), even those without radiographic evidence of
silicosis, had decreased spirometric parameters and diffusing capacity
(DLco). Pulmonary function was further decreased in the
presence of silicosis, even those with mild to moderate disease (ILO
categories 1 and 2). The authors concluded that functional
abnormalities precede radiographic changes of silicosis.
A number of studies were conducted to examine the role of
emphysematous changes in the presence of silicosis in reducing lung
function; these have been reviewed by Gamble et al. (2004), who
concluded that there is little evidence that silicosis is related to
development of emphysema in the absence of PMF. In addition, Gamble et
al. (2004) found that, in general, studies found that the lung function
of those with radiographic silicosis in ILO category 1 was
indistinguishable from those in category 0, and that those in category
2 had small reductions in lung function relative to those with category
0 and little difference in the prevalence of emphysema. There were
slightly greater decrements in lung function with category 3 and more
significant reductions with progressive massive fibrosis. In studies
for which information was available on both silicosis and emphysema,
reduced lung function was more strongly related to emphysema than to
silicosis.
In conclusion, many studies reported finding an association between
pulmonary function decrements and ILO category 2 or 3 background
profusion of small opacities; this appears to be consistent with the
histopathological view, in which individual fibrotic nodules
conglomerate to form a massive fibrosis (Ng and Chan, 1992). Emphysema
may also play a role in reducing lung function in workers with higher
grades of silicosis. Pulmonary function decrements have not been
reported in some studies among workers with silicosis scored as ILO
category 1. However, 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 (B[eacute]gin et al., 1988;
Cowie, 1998; Cowie and Mabena, 1991; Ng et al., 1987a; Wang et al.,
1997). It may also be that studies designed to relate x-ray findings
with pulmonary function declines are further confounded by pulmonary
function declines caused by chronic obstructive pulmonary disease
(COPD) seen among silica-exposed workers absent radiological silicosis,
as has been seen in many investigations of COPD. OSHA's review of the
literature on crystalline silica exposure and development of COPD
appears in section II.D of the background document and is summarized in
section V.D below.
OSHA believes that the literature reviewed above demonstrates
decreased lung function among workers with radiological evidence of
silicosis consistent with an ILO classification of major category 2 or
higher. Also, given the evidence of functional impairment in some
workers prior to radiological evidence of silicosis, and given the low
sensitivity of radiography, particularly in detecting early silicosis,
OSHA believes that exposure to silica impairs lung function in at least
some individuals before silicosis can be detected on chest radiograph.
4. Pulmonary Tuberculosis
As silicosis progresses, it may be complicated by severe
mycobacterial infections, the most common of which is pulmonary
tuberculosis (TB). Active tuberculosis infection is a well-recognized
complication of chronic silicosis, and such infections are known as
silicotuberculosis (IARC, 1997; NIOSH, 2002). The risk of developing TB
infection is higher in silicotics than non-silicotics (Balmes, 1990;
Cowie, 1994; Hnizdo and Murray, 1998; Kleinschmidt and Churchyard,
1997; and Murray et al., 1996). There also is evidence that exposure to
silica increases the risk for pulmonary tuberculosis independent of the
presence of silicosis (Cowie, 1994; Hnizdo and Murray, 1998;
teWaterNaude et al., 2006). In a summary of the literature on silica-
related disease mechanisms, Ding et al. (2002) noted that it is well
documented that exposure to silica can lead to impaired cell-mediated
immunity, increasing susceptibility to mycobacterial infection. Reduced
numbers of T-cells, increased numbers of B-cells, and alterations of
serum immunoglobulin levels have been observed in workers with
silicosis. In addition, according to Ng and Chan (1991), silicosis and
TB act synergistically to increase fibrotic scar tissue (leading to
massive fibrosis) or to enhance susceptibility to active mycobacterial
infection. Lung fibrosis is common to both diseases and both diseases
decrease the ability of alveolar macrophages to aid in the clearance of
dust or infectious particles.
B. Carcinogenic Effects of Silica (Cancer of the Lung and Other Sites)
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. In addition, OSHA reviewed a pooled case-control
study, a large national death certificate study, two national cancer
registry studies, and six meta-analyses. In all, OSHA's review included
approximately 60 primary epidemiological studies.
Based on its review, OSHA preliminarily concludes that the human
data summarized in this section provides ample evidence
that exposure to respirable crystalline silica
increases the risk of lung cancer among workers. The strongest evidence
comes from the worldwide cohort and case-control studies reporting
excess lung cancer mortality among workers exposed to respirable
crystalline silica dust as quartz in various industrial sectors,
including the granite/stone quarrying and processing, industrial sand,
mining, and pottery and ceramic industries, as well as to cristobalite
in diatomaceous earth and refractory brick industries. The 10-cohort
pooled case-control analysis by Steenland et al. (2001a) confirms these
findings. A more recent clinic-based pooled case-control analysis of
seven European countries by Cassidy et al. (2007) as well as two
national death certificate registry studies (Pukkala et al., 2005 in
Finland; Calvert et al., 2003 in the United States) support the
findings from the cohort and case-control analysis.
1. Overall and Industry Sector-Specific Findings
Associations between exposure to respirable crystalline silica and
lung cancer have been reported in worker populations from many
different industrial sectors. IARC (1997) concluded that crystalline
silica is a confirmed human carcinogen 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). IARC (2012) recently
reaffirmed that crystalline silica is a confirmed human carcinogen.
NIOSH (2002) also determined that crystalline silica is a human
carcinogen after evaluating updated literature.
OSHA believes that the strongest evidence for carcinogenicity comes
from studies in five industry sectors. These are:
Diatomaceous Earth Workers (Checkoway et al., 1993, 1996,
1997, and 1999; Seixas et al., 1997);
British Pottery Workers (Cherry et al., 1998; McDonald et
al., 1995);
Vermont Granite Workers (Attfield and Costello, 2004;
Graham et al., 2004; Costello and Graham, 1988; Davis et al., 1983);
North American Industrial Sand Workers (Hughes et al.,
2001; McDonald et al., 2001, 2005; Rando et al., 2001; Sanderson et
al., 2000; Steenland and Sanderson, 2001); and
British Coal Mining (Miller et al., 2007; Miller and
MacCalman, 2009).
The studies above 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. OSHA
credits these studies because in general, they are of sufficient size
and have adequate years of follow up, and have 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.
A series of studies of the diatomaceous earth industry (Checkoway
et al., 1993, 1996, 1997, 1999) demonstrated positive exposure-response
trends between cristobalite exposures and lung cancer as well as non-
malignant respiratory disease mortality (NMRD). Checkoway et al. (1993)
developed a "semi-quantitative" cumulative exposure estimate that
demonstrated a statistically significant positive exposure-response
trend (p = 0.026) between duration of employment or cumulative exposure
and lung cancer mortality. The quartile analysis showed a monotonic
increase in lung cancer mortality, with the highest exposure quartile
having a RR of 2.74 for lung cancer mortality. Checkoway et al. (1996)
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. Rice et al. (2001) conducted a re-analysis and quantitative
risk assessment of the Checkoway et al. (1997) study, which OSHA has
included as part of its assessment of lung cancer mortality risk (See
Section II, Preliminary Quantitative Risk Assessment).
In the British pottery industry, excess lung cancer risk was found
to be associated with crystalline silica exposure among workers in a
PMR study (McDonald et al., 1995) and in a cohort and nested case-
control study (Cherry et al., 1998). In the PMR study, 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. The findings of the British
pottery studies are supported by other studies within their industrial
sector. Studies by Winter et al. (1990) of British pottery workers and
by McLaughlin et al. (1992) both reported finding suggestive trends of
increased lung cancer mortality with increasing exposure to respirable
crystalline silica.
Costello and Graham (1988) and Graham et al. (2004) in a follow-up
study found that Vermont granite workers employed prior to 1930 had an
excess risk of lung cancer, but lung cancer mortality among granite
workers hired after 1940 (post-implementation of controls) was not
elevated in the Costello and Graham (1988) study and was only somewhat
elevated (not statistically significant) in the Graham et al. (2004)
study. Graham et al. (2004) 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) developed a quantitative estimate of cumulative exposure (8
exposure categories) adapted from a job exposure matrix developed by
Davis et al. (1983). They found a statistically significant trend with
log-transformed cumulative exposure. 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. Attfield and Costello (2004) concluded that exposure to
crystalline silica in the range of cumulative exposures typically
experienced by contemporarily exposed workers causes an increased risk
of lung cancer mortality. 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. Also, even though
the highest exposure group consisted of only 15 percent of the study
population, it had a disproportionate effect on dampening the exposure-
response relationship.
OSHA believes that the study by Attfield and Costello (2004) is of
superior design in that it was a categorical analysis that used
quantitative estimates of exposure and evaluated lung cancer mortality
rates by exposure group. In contrast, the findings by Graham et al.
(2004) are based on a dichotomous comparison of risk among high- versus
low-exposure groups, where date-of-hire before and after implementation
of ventilation controls is used as a surrogate for exposure.
Consequently, OSHA believes that the study by Attfield and Costello is
the more convincing study, and is one of the studies used by OSHA for
quantitative risk assessment of lung cancer mortality due to
crystalline silica exposure.
The conclusions of the Vermont granite worker study (Attfield and
Costello, 2004) are supported by the findings in studies of workers in
the U.S. crushed stone industry (Costello et al., 1995) and Danish
stone industry (Gu[eacute]nel et al., 1989a, 1989b). Costello et al.
(1995) found a non-statistically significant increase in lung cancer
mortality among limestone quarry workers and a statistically
significant increased lung cancer mortality in granite quarry workers
who worked 20 years or more since first exposure. Gu[eacute]nel et al.
(1989b), in a Danish cohort study, found statistically significant
increases in lung cancer incidence among skilled stone workers and
skilled granite stone cutters. A study of Finnish granite workers that
initially showed increasing risk of lung cancer with increasing silica
exposure, upon extended follow-up, did not show an association and is
therefore considered a negative study (Toxichemica, Inc., 2004).
Studies of two overlapping cohorts in the industrial sand industry
(Hughes et al., 2001; McDonald et al., 2001, 2005; Rando et al., 2001;
Sanderson et al., 2000; Steenland and Sanderson, 2001) reported
comparable results. These studies found a statistically significantly
increased risk of lung cancer mortality with increased cumulative
exposure in both categorical and continuous analyses. McDonald et al.
(2001) examined a cohort that entered the workforce, on average, a
decade earlier than the cohorts that Steenland and Sanderson (2001)
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) cohort worked in 16 plants, 7 of which overlapped with
the McDonald, et al. (2001) cohort. McDonald et al. (2001), Hughes et
al. (2001), and Rando et al. (2001) had access to smoking histories,
plant records, and exposure measurements that allowed for historical
reconstruction and the development of a job exposure matrix. Steenland
and Sanderson (2001) 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;
McDonald et al., 2005; Steenland and Sanderson, 2001) show 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) study in its Preliminary
Quantitative Risk Assessment (Section II).
Brown and Rushton (2005a, 2005b) found no association between risk
of lung cancer mortality and exposure to respirable crystalline silica
among British industrial sand workers. However, the small sample size
and number of years of follow-up limited the statistical power of the
analysis. Additionally, as Steenland noted in a letter review (2005a),
the cumulative exposures of workers in the Brown and Ruston (2005b)
study were over 10 times lower than the cumulative exposures
experienced by the cohorts in the pooled analysis that Steenland et al.
(2001b) performed. The low exposures experienced by this cohort would
have made detecting a positive association with lung cancer mortality
even more difficult.
Excess lung cancer mortality was reported in a large cohort study
of British coal miners (Miller et al., 2007; Miller and MacCalman,
2009). These studies examined the mortality experience of 17,800 miners
through the end of 2005. 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 are 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
the Cox regression provide strong evidence that, for these coal miners,
quartz exposures were associated with increased lung cancer risk but
that simultaneous exposures to coal dust did not cause increased lung
cancer risk. Because of these strengths, OSHA included the quantitative
analysis from this study in its Preliminary Quantitative Risk
Assessment (Section II).
Studies of lung cancer mortality in metal ore mining populations
reflect mixed results. Many of these mining studies were subject to
confounding due to exposure to other potential carcinogens such as
radon and arsenic. IARC (1997) noted that in only a few ore mining
studies was confounding from other occupational carcinogens taken into
account. IARC (1997) also noted that, where confounding was absent or
accounted for in the analysis (gold miners in the U.S., tungsten miners
in China, and zinc and lead miners in Sardinia, Italy), an association
between silica exposure and lung cancer was absent. Many of the studies
conducted since IARC's (1997) review more strongly implicate
crystalline silica as a human carcinogen. Pelucchi et al. (2006), in a
meta-analysis of studies conducted since IARC's (1997) review, reported
statistically significantly elevated relative risks of lung cancer
mortality in underground and surface miners in three cohort and four
case-control studies (See Table I-15). Cassidy et al. (2007), in a
pooled case-control analysis, showed a statistically significant
increased risk of lung cancer mortality among miners (OR = 1.48).
Cassidy et al. (2007) also demonstrated a clear linear trend of
increasing odds ratios for lung cancer with increasing exposures.
Among workers in Chinese tungsten and iron mines, mortality from
lung cancer was not found to be statistically significantly increased
(Chen et al., 1992; McLaughlin et al., 1992). In contrast, studies of
Chinese tin miners found increased lung cancer mortality rates and
positive exposure-response associations with increased silica exposure
(Chen et al., 1992). Unfortunately, in many of these Chinese tin mines,
there was potential confounding from arsenic exposure, which was highly
correlated with exposure to crystalline silica (Chen and Chen, 2002;
Chen et al., 2006). Two other studies (Carta et al. (2001) of Sardinian
miners and stone quarrymen; Finkelstein (1998) primarily of Canadian
miners) were limited to silicotics. The Sardinian study found a non-
statistically significant association between crystalline silica
exposure and lung cancer mortality but no apparent exposure-response
trend with silica exposure. The authors attributed the increased lung
cancer to increased radon exposure and smoking among cases as compared
to controls. Finkelstein (1998) found a positive association between
silica exposure and lung cancer.
Gold mining has been extensively studied in the United States,
South Africa, and Australia in four cohort and associated nested case-control
studies, and in two separate case-control studies conducted in South
Africa. As with metal ore mining, gold mining involves exposure to
radon and other carcinogenic agents, which may confound the
relationship between silica exposure and lung cancer. The U.S. gold
miner study (Steenland and Brown, 1995a) did not find an increased risk
of lung cancer, while the western Australian gold miner study (de Klerk
and Musk, 1998) showed a SMR of 149 (95% CI 1.26-1.76) for lung cancer.
Logistic regression analysis of the western Australian case control
data showed that lung cancer mortality was statistically significantly
associated with log cumulative silica exposure after adjusting for
smoking and bronchitis. After additionally adjusting for silicosis, the
relative risk remained elevated but was no longer statistically
significant. The authors concluded that their findings showed
statistically significantly increased lung cancer mortality in this
cohort but that the increase in lung cancer mortality was restricted to
silicotic members of the cohort.
Four studies of gold miners were conducted in South Africa. Two
case control studies (Hessel et al., 1986, 1990) reported no
significant association between silica exposure and lung cancer, but
these two studies may have underestimated risk, according to Hnizdo and
Sluis-Cremer (1991). Two cohort studies (Reid and Sluis-Cremer, 1996;
Hnizdo and Sluis-Cremer, 1991) and their associated nested case-control
studies found elevated SMRs and odds ratios, respectively, for lung
cancer. Reid and Sluis-Cremer (1996) attributed the increased mortality
due to lung cancer and other non-malignant respiratory diseases to
cohort members' lifestyle choices (particularly smoking and alcohol
consumption). However, OSHA notes that the study reported finding a
positive, though not statistically significant, association between
cumulative crystalline silica exposure and lung cancer, as well as
statistically significant association with renal failure, COPD, and
other respiratory diseases that have been implicated with silica
exposure.
In contrast, Hnizdo and Sluis-Cremer (1991) found a positive
exposure-response relationship between cumulative exposure and lung
cancer mortality among South African gold miners after accounting for
smoking. In a nested case-control study from the same cohort, Hnizdo et
al. (1997) found a statistically significant increase in lung cancer
mortality that was associated with increased cumulative dust exposure
and time spent underground. Of the studies examining silica and lung
cancer among South African gold miners, these two studies were the
least likely to have been affected by exposure misclassification, given
their rigorous methodologies and exposure measurements. Although not
conclusive in isolation, OSHA considers the mining study results,
particularly the gold mining and the newer mining studies, as
supporting evidence of a causal relationship between exposure to silica
and lung cancer risk.
OSHA has 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. Thus, elevated rates of lung cancer found in
these industries could not be attributed to silica. IARC previously
made a similar determination in reference to the foundry industry.
However, with respect to the construction industry, Cassidy et al.
(2007), in a large, European community-based case-control study,
reported finding a clear linear trend of increasing odds ratio with
increasing cumulative exposure to crystalline silica (estimated semi-
quantitatively) after adjusting for smoking and exposure to insulation
and wood dusts. Similar trends were found for workers in the
manufacturing and mining industries as well. This study was a very
large multi-national study that utilized information on smoking
histories and exposure to silica and other occupational carcinogens.
OSHA believes that this study provides further evidence that exposure
to crystalline silica increases the risk of lung cancer mortality and,
in particular, in the construction industry.
In addition, a recent 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). A national records and death certificate study
was also conducted in Finland by Pukkala et al. (2005), who found a
statistically significant excess of lung cancer incidence among men and
women with estimated medium and heavy exposures. OSHA believes that
these large national death certificate studies and the pooled European
community-based case-control study are strongly supportive of the
previously reviewed epidemiologic data and supports the conclusion that
occupational exposure to crystalline silica is a risk factor for lung
cancer mortality.
One of the more compelling studies evaluated by OSHA is the pooled
analysis of 10 occupational cohorts (5 mines and 5 industrial
facilities) conducted by Steenland et al. (2001a), which demonstrated
an overall positive exposure-response relationship between cumulative
exposure to silica and lung cancer mortality. These ten 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 used a nested case
control design and 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. From their analysis, the authors concluded that "[d]espite
this relatively shallow exposure-response trend, overall our results
tend to support the recent conclusion by IARC (1997) that inhaled
crystalline silica in occupational settings is a human carcinogen, and
suggest that existing permissible exposure limits for silica need to be
lowered (Steenland et al., 2001a). To evaluate the potential effect of
random and systematic errors in the underlying exposure data from these
10 cohort studies, Steenland and Bartell (Toxichemica, Inc., 2004)
conducted a series of sensitivity analyses at OSHA's request. OSHA's
Preliminary Quantitative Risk Assessment (Section II) presents
additional information on the Steenland et al. (2001a) pooled cohort
study and the sensitivity analysis performed by Steenland and Bartell
(Toxichemica, Inc., 2004).
2. Smoking, Silica Exposure, and Lung Cancer
Smoking is known to be a major risk factor for lung cancer.
However, OSHA believes it is unlikely that smoking explains the
observed exposure-response trends in the studies described above,
particularly the retrospective cohort or nested case-control studies of
diatomaceous earth, British pottery, Vermont granite, British coal,
South African gold, and industrial sand workers. Also, the positive
associations between silica exposure and lung cancer in multiple
studies in multiple sectors indicates that exposure to crystalline
silica independently increases the risk of lung cancer.
Studies by Hnizdo et al. (1997), McLaughlin et al. (1992), Hughes
et al. (2001), McDonald et al. (2001, 2005), Miller and MacCalman
(2009), and Cassidy et al. (2007) 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) and in the follow-up nested
case-control study (Hnizdo et al., 1997) found that the combined effect
of exposure to respirable crystalline silica and smoking was greater
than additive, suggesting a multiplicative effect. This synergy
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 reported by McLaughlin et al. (1992), 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 by Hughes et al. (2001) and British coal workers by Miller and
MacCalman (2009) found positive exposure-response trends after
adjusting for smoking histories, as did Cassidy et al. (2007) in their
community-based case-control study of exposed European workers.
In reference to control of potential confounding by cigarette
smoking in crystalline silica studies, Stayner (2007), in an invited
journal commentary, stated:
Of particular concern in occupational cohort studies is the
difficulty in adequately controlling for confounding by cigarette
smoking. Several of the cohort studies that adjusted for smoking
have demonstrated an excess of lung cancer, although the control for
smoking in many of these studies was less than optimal. The results
of the article by Cassidy et al. presented in this journal appear to
have been well controlled for smoking and other workplace exposures.
It is quite implausible that residual confounding by smoking or
other risk factors for lung cancer in this or other studies could
explain the observed excess of lung cancer in the wide variety of
populations and study designs that have been used. Also, it is
generally considered very unlikely that confounding by smoking could
explain the positive exposure-response relationships observed in
these studies, which largely rely on comparisons between workers
with similar socioeconomic backgrounds.
Given the findings of investigators who have accounted for the
impact of smoking, the weight of the evidence reviewed here implicates
respirable crystalline silica as an independent risk factor for lung
cancer mortality. This finding is further supported by animal studies
demonstrating that exposure to silica alone can cause lung cancer
(e.g., Muhle et al., 1995).
3. Silicosis and Lung Cancer Risk
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; Tsuda et
al., 1997) showed no association with increasing lung cancer mortality,
while Lacasse et al. (2005) demonstrated a positive dose-response for
lung cancer with increasing ILO radiographic category. A number of
other studies, discussed above, found increased lung cancer risk among
exposed workers absent radiological evidence of silicosis (Cassidy et
al., 2007; Checkoway et al., 1999; Cherry et al., 1998; Hnizdo et al.,
1997; McLaughlin et al., 1992). For example, the diatomaceous earth
study by Checkoway et al. (1999) showed a statistically significant
exposure-response for lung cancer among non-silicotics. Checkoway and
Franzblau (2000), reviewing the international literature, found all
epidemiological studies conducted to that date were insufficient to
conclusively determine the role of silicosis in the etiology of lung
cancer. OSHA preliminarily concludes that the more recent pooled and
meta-analyses do not provide compelling evidence that silicosis is a
necessary precursor to lung cancer. The analyses that do suggest an
association between silicosis and lung cancer may simply reflect that
more highly exposed individuals are at a higher risk for lung cancer.
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. This has led some of these
researchers to also 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 the inflammation (and
concomitant oxidative stress) and increased epithelial cell
proliferation associated with the development of silicosis. However,
other researchers have noted that other key factors and proposed
mechanisms, such as direct damage to DNA by silica, inhibition of p53,
loss of cell cycle regulation, stimulation of growth factors, and
production of oncogenes, may also be involved in carcinogenesis induced
by silica (see Section II.F of the background document for more
information on these studies). Thus, OSHA preliminarily concludes 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.
4. Relationship Between Silica Polymorphs and Lung Cancer Risk
OSHA's current PELs for respirable crystalline silica reflects a
once-held belief that cristobalite is more toxic than quartz (i.e., the
existing general industry PEL for cristobalite is one-half the general
industry PEL for quartz). Available evidence indicates that this does
not appear to be the case with respect to the carcinogenicity of
crystalline silica. A comparison between cohorts having principally
been exposed to cristobalite (the diatomaceous earth study and the
Italian refractory brick study) with other well conducted studies of
quartz-exposed cohorts suggests no difference in the toxicity of
cristobalite versus quartz. The data indicates that the SMRs for lung
cancer mortality among workers in the diatomaceous earth (SMR = 141)
and refractory brick (SMR=151) cohort studies are within the range of
the SMR point estimates of other cohort studies with principally quartz
exposures (quartz exposure of Vermont granite workers yielding an SMR
of 117; quartz and possible post-firing cristobalite exposure of
British pottery workers yielding an SMR of 129; quartz exposure among
industrial sand workers yielding SMRs of 129, (McDonald et al., 2001)
and 160 (Steenland and Sanderson, 2001)). Also, the SMR point estimates
for the diatomaceous earth and refractory brick studies are similar to,
and fall within the 95 percent confidence interval of, the odds ratio
(OR=1.37, 95% CI 1.14-1.65) of the recently conducted multi-center
case-control study in Europe (Cassidy et al., 2007).
OSHA believes that the current epidemiological literature provides
little, if any, support for treating cristobalite as presenting a
greater lung cancer risk than comparable exposure to respirable quartz.
Furthermore, the weight of the available toxicological literature no
longer supports the hypothesis that cristobalite has a higher toxicity
than quartz, and quantitative estimates of lung cancer risk do not suggest that cristobalite is more
carcinogenic than quartz. (See Section I.F of the background document,
Physical Factors that May Influence Toxicity of Crystalline Silica, for
a fuller discussion of this issue.) OSHA preliminary concludes that
respirable cristobalite and quartz dust have similar potencies for
increasing lung cancer risk. Both IARC (1997) and NIOSH (2002) reached
similar conclusions.
5. Cancers of Other Sites
Respirable crystalline silica exposure has also been investigated
as a potential risk factor for cancer at other sites such as the
larynx, nasopharynx and the digestive system including the esophagus
and stomach. Although many of these studies suggest an association
between exposure to crystalline silica and an excess risk of cancer
mortality, most are too limited in terms of size, study design, or
potential for confounding to be conclusive. Other than for lung cancer,
cancer mortality studies demonstrating a dose-response relationship are
quite limited. In their silica hazard review, NIOSH (2002) concluded
that, exclusive of the lung, an association has not been established
between silica exposure and excess mortality from cancer at other
sites. A brief summary of the relevant literature is presented below.
a. Cancer of the Larynx and Nasopharynx
Several studies, including three of the better-quality lung cancer
studies (Checkoway et al., 1997; Davis et al., 1983; McDonald et al.,
2001) suggest an association between exposure to crystalline silica and
increased mortality from laryngeal cancer. However, the evidence for an
association is not strong due to the small number of cases reported and
lack of statistical significance of most of the findings.
b. Gastric (Stomach) Cancer
In their 2002 hazard review of respirable crystalline silica, NIOSH
identified numerous epidemiological studies and reported statistically
significant increases in death rates due to gastric or stomach cancer.
OSHA preliminarily concurs with observations made previously by Cocco
et al. (1996) and the NIOSH (2002) crystalline silica hazard review
that the vast majority of epidemiology studies of silica and stomach
cancer have not sufficiently adjusted for the effects of confounding
factors or have not been sufficiently designed to assess a dose-
response relationship (e.g., Finkelstein and Verma, 2005; Moshammer and
Neuberger, 2004; Selikoff, 1978, Stern et al., 2001). Other studies did
not demonstrate a statistically significant dose-response relationship
(e.g., Calvert et al., 2003; Tsuda et al., 2001). Therefore, OSHA
believes the evidence is insufficient to conclude that silica is a
gastric carcinogen.
c. Esophageal Cancer
Three well-conducted nested case-control studies of Chinese workers
indicated an increased risk of esophageal cancer mortality attributed
by the study's authors to respirable crystalline silica exposure in
refractory brick production, boiler repair, and foundry workers (Pan et
al., 1999; Wernli et al., 2006) and caisson construction work (Yu et
al., 2005). Each study demonstrated a dose-response association with
some surrogate measure of exposure, but confounding due to other
occupational exposures is possible in all three work settings (heavy
metal exposure in the repair of boilers in steel plants, PAH exposure
in foundry workers, radon and radon daughter exposure in Hong Kong
caisson workers). Other less well-constructed studies also indicated
elevated rates of esophageal cancer mortality with silica exposure
(Tsuda et al., 2001; Xu et al., 1996a).
In contrast, two large national mortality studies in Finland and
the United States, using qualitatively ranked exposure estimates, did
not show a positive association between silica exposure and esophageal
cancer mortality (Calvert et al., 2003; Weiderpass et al., 2003). OSHA
preliminarily concludes that the epidemiological literature is not
sufficiently robust to attribute increased esophageal cancer mortality
to exposure to respirable crystalline silica.
d. Other Miscellaneous Cancers
In 2002, NIOSH conducted a thorough literature review of the health
effects potentially associated with crystalline silica exposure
including a review of lung cancer and other carcinogens. NIOSH noted
that for workers who may have been exposed to crystalline silica, there
have been infrequent reports of statistically significant excesses of
deaths for other cancers. A summary of these cancer studies as cited in
NIOSH (2002) have been reported in the following organ systems (see
NIOSH, 2002 for full bibliographic references): salivary gland; liver;
bone; pancreatic; skin; lymphopoetic or hematopoietic; brain; and
bladder.
According to NIOSH (2002), an association has not been established
between these cancers and exposure to crystalline silica. OSHA believes
that these isolated reports of excess cancer mortality at these sites
are not sufficient to draw any inferences about the role of silica
exposure. The findings have not been consistently seen among
epidemiological studies and there is no evidence of an exposure
response relationship.
C. Other Nonmalignant Respiratory Disease
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). COPD is a disease state characterized by airflow
limitation that is not fully reversible. The airflow limitation is
usually progressive and is associated with an abnormal inflammatory
response of the lungs to noxious particles or gases. In patients with
COPD, either chronic bronchitis or emphysema may be present or both
conditions may be present together. The following presents OSHA's
discussion of the literature describing the relationships between
silica exposure and non-malignant respiratory disease.
1. Emphysema
OSHA has considered a series of longitudinal studies of white South
African gold miners conducted by Hnizdo and co-workers. Hnizdo et al.
(1991) found a significant association between emphysema (both
panacinar and centriacinar) and years of employment in a high dust
occupation (respirable dust was estimated to contain 30 percent free
silica). There was no such association found for non-smokers, as there
were only four non-smokers with a significant degree of emphysema found
in the cohort. A further study by Hnizdo et al. (1994) looked at only
life-long non-smoking South African gold miners. In this population, no
significant degree of emphysema or association with years of exposure
or cumulative dust exposure was found. However, the degree of emphysema
was significantly associated with the degree of hilar gland nodules,
which the authors suggested might act as a surrogate for exposure to
silica. The authors concluded that the minimal degree of emphysema seen
in non-smoking miners exposed to the cumulative dust levels found in
this study (mean 6.8 mg/m\3\, SD 2.4, range 0.5 to 20.2, 30 percent
crystalline silica) was unlikely to cause meaningful impairment of lung
function.
From the two studies above, Hnizdo et al. (1994) concluded that the
statistically significant association between exposure to silica dust
and the degree of emphysema in smokers suggests that tobacco smoking
potentiates the effect of silica dust. In contrast to their previous
studies, a later study by Hnizdo et al. (2000) of South African gold
miners found that emphysema prevalence was decreased in relation to
dust exposure. The authors suggested that selection bias was
responsible for this finding.
The findings of several cross-sectional and case-control studies
were more mixed. Becklake et al. (1987), in an unmatched case-control
study of white South African gold miners, determined that a miner who
had worked in high dust for 20 years had a greater chance of getting
emphysema than a miner who had never worked in high dust. A reanalysis
of this data (de Beer et al., 1992) including added-back cases and
controls (because of possible selection bias in the original study),
still found an increased risk for emphysema, although the reported odds
ratio was smaller than previously reported by Becklake et al. (1987).
Begin et al. (1995), in a study of the prevalence of emphysema in
silica-exposed workers with and without silicosis, found that silica-
exposed smokers without silicosis had a higher prevalence of emphysema
than a group of asbestos-exposed workers with similar smoking history.
In non-smokers, the prevalence of emphysema was much higher in those
with silicosis than in those without silicosis. A study of black
underground gold miners found that the presence and grade of emphysema
were statistically significantly associated with the presence of
silicosis but not with years of mining (Cowie et al., 1993).
Several of the above studies (Becklake et al., 1987; Begin et al.,
1995; Hnizdo et al., 1994) found that emphysema can occur in silica-
exposed workers who do not have silicosis and suggest that a causal
relationship may exist between exposure to silica and emphysema. The
findings of experimental (animal) studies that emphysema occurs at
lower silica doses than does fibrosis in the airways or the appearance
of early silicotic nodules (e.g., Wright et al., 1988) tend to support
the findings in human studies that silica-induced emphysema can occur
absent signs of silicosis.
Others have also concluded that there is a relationship between
emphysema and exposure to crystalline silica. Green and Vallyathan
(1996) reviewed several studies of emphysema in workers exposed to
silica. The authors stated that these studies show an association
between cumulative dust exposure and death from emphysema. IARC (1997)
has also briefly reviewed studies on emphysema in its monograph on
crystalline silica carcinogenicity and concluded that exposure to
crystalline silica increases the risk of emphysema. In their 2002
Hazard Review, NIOSH concluded that occupational exposure to respirable
crystalline silica is associated with emphysema but that some
epidemiologic studies suggested that this effect may be less frequent
or absent in non-smokers.
Hnizdo and Vallyathan (2003) also conducted a review of studies
addressing COPD due to occupational silica exposure and concluded that
chronic exposure to silica dust at levels that do not cause silicosis
may cause emphysema.
Based on these findings, OSHA preliminarily concludes that exposure
to respirable crystalline silica or silica-containing dust can increase
the risk of emphysema, regardless of whether silicosis is present. This
appears to be clearly the case for smokers. It is less clear whether
nonsmokers exposed to silica would also be at higher risk and if so, at
what levels of exposure. It is also possible that smoking potentiates
the effect of silica dust in increasing emphysema risk.
2. Chronic Bronchitis
There were no longitudinal studies available designed to
investigate the relationship between silica exposure and bronchitis.
However, several cross-sectional studies provide useful information.
Studies are about equally divided between those that have reported a
relationship between silica exposure and bronchitis and those that have
not. Several studies demonstrated a qualitative or semiquantitative
relationship between silica exposure and chronic bronchitis. Sluis-
Cremer et al. (1967) found a significant difference between the
prevalence of chronic bronchitis in dust-exposed and non-dust exposed
male residents of a South African gold mining town who smoked, but
found no increased prevalence among non-smokers. In contrast, a
different study of South African gold miners found that the prevalence
of chronic bronchitis increased significantly with increasing dust
concentration and cumulative dust exposure in smokers, nonsmokers, and
ex-smokers (Wiles and Faure, 1977). Similarly, a study of Western
Australia gold miners found that the prevalence of chronic bronchitis,
as indicated by odds ratios (controlled for age and smoking), was
significantly increased in those that had worked in the mines for 1 to
9 years, 10 to 19 years, and more than 20 years, as compared to
lifetime non-miners (Holman et al., 1987). Chronic bronchitis was
present in 62 percent of black South African gold miners and 45 percent
of those who had never smoked in a study by Cowie and Mabena (1991).
The prevalence of what the researchers called "chronic bronchitic
symptom complex" reflected the intensity of dust exposure. A higher
prevalence of respiratory symptoms, independent of smoking and age, was
also found for granite quarry workers in Singapore in a high exposure
group as compared to low exposure and control groups, even after
excluding those with silicosis from the analysis (Ng et al., 1992b).
Other studies found no relationship between silica exposure and the
prevalence of chronic bronchitis. Irwig and Rocks (1978) compared
silicotic and non-silicotic South African gold miners and found no
significant difference in symptoms of chronic bronchitis. The
prevalence of symptoms of chronic bronchitis were also not found to be
associated with years of mining, after adjusting for smoking, in a
population of current underground uranium miners (Samet et al., 1984).
Silica exposure was described in the study to be "on occasion" above
the TLV. It was not possible to determine, however, whether miners with
respiratory diseases had left the workforce, making the remaining
population unrepresentative. Hard-rock (molybdenum) miners, with 27 and
49 percent of personal silica samples greater than 100 and 55 [mu]g/
m\3\, respectively, also showed no increase in prevalence of chronic
bronchitis in association with work in that industry (Kreiss et al.,
1989). However, the authors thought that differential out-migration of
symptomatic miners and retired miners from the industry and town might
explain that finding. Finally, grinders of agate stones (with resulting
dust containing 70.4 percent silica) in India also had no increase in
the prevalence of chronic bronchitis compared to controls matched by
socioeconomic status, age and smoking, although there was a
significantly higher prevalence of acute bronchitis in female grinders.
A significantly higher prevalence and increasing trend with exposure
duration for pneumoconiosis in the agate workers indicated that had an
increased prevalence in chronic bronchitis been present, it would have
been detected (Rastogi et al., 1991). However, control workers in this
study may also have been exposed to silica and the study and control
workers both had high tuberculosis prevalence, possibly masking an association of
exposure with bronchitis (NIOSH, 2002). Furthermore, exposure durations
were very short.
Thus, some prevalence studies supported a finding of increased
bronchitis in workers exposed to silica-containing dust, while other
studies did not support such a finding. However, OSHA believes that
many of the studies that did not find such a relationship were likely
to be biased towards the null. For example, some of the molybdenum
miners studied by Kreiss et al. (1989), particularly retired and
symptomatic miners, may have left the town and the industry before the
time that the cross-sectional study was conducted, resulting in a
survivor effect that could have interfered with detection of a possible
association between silica exposure and bronchitis. This survivor
effect may also have been operating in the study of uranium miners in
New Mexico (Samet et al., 1984). In two of the negative studies,
members of comparison and control groups were also exposed to
crystalline silica (Irwig and Rocks, 1978; Rastogi et al., 1991),
creating a potential bias toward the null. Additionally, tuberculosis
in both exposed and control groups in the agate worker study (Rastogi
et al., 1991)) may have masked an effect (NIOSH, 2002), and the
exposure durations were very short. Several of the positive studies
demonstrated a qualitative or semi-quantitative relationship between
silica exposure and chronic bronchitis.
Others have reviewed relevant studies and also concluded that there
is a relationship between exposure to crystalline silica and the
development of bronchitis. The American Thoracic Society (ATS) (1997)
published an official statement on the adverse effects of crystalline
silica exposure that included a section that discussed studies on
chronic bronchitis (defined by chronic sputum production). According to
the ATS review, chronic bronchitis was found to be common among worker
groups exposed to dusty environments contaminated with silica. In
support of this conclusion, ATS cited studies with what they viewed as
positive findings of South African (Hnizdo et al., 1990) and Australian
(Holman et al., 1987) gold miners, Indonesian granite workers (Ng et
al., 1992b), and Indian agate workers (Rastogi et al., 1991). ATS did
not mention studies with negative findings.
A review published by NIOSH in 2002 discussed studies related to
silica exposure and development of chronic bronchitis. NIOSH concluded,
based on the same studies reviewed by OSHA, that occupational exposure
to respirable crystalline silica is associated with bronchitis, but
that some epidemiologic studies suggested that this effect may be less
frequent or absent in non-smokers.
Hnizdo and Vallyathan (2003) also reviewed studies addressing COPD
due to occupational silica exposure and concluded that chronic exposure
to silica dust at levels that do not cause silicosis may cause chronic
bronchitis. They based this conclusion on studies that they cited as
showing that the prevalence of chronic bronchitis increases with
intensity of exposure. The cited studies were also reviewed by OSHA
(Cowie and Mabena, 1991; Holman et al., 1987; Kreiss et al., 1989;
Sluis-Cremer et al., 1967; Wiles and Faure, 1977).
OSHA preliminarily concludes that exposure to respirable
crystalline silica may cause chronic bronchitis and an exposure-
response relationship may exist. Smokers may be at increased risk as
compared to non-smokers. Chronic bronchitis may occur in silica-exposed
workers who do not have silicosis.
3. Pulmonary Function Impairment
OSHA has reviewed numerous studies on the relationship of silica
exposure to pulmonary function impairment as measured by spirometry.
There were several longitudinal studies available. Two groups of
researchers conducted longitudinal studies of lung function impairment
in Vermont granite workers and reached opposite conclusions. Graham et
al (1981, 1994) examined stone shed workers, who had the highest
exposures to respirable crystalline silica (between 50 and 100 [mu]g/
m\3\), along with quarry workers (presumed to have lower exposure) and
office workers (expected to have negligible exposure). The longitudinal
losses of FVC and FEV1 were not correlated with years
employed, did not differ among shed, quarry, and office workers, and
were similar, according to the authors, to other blue collar workers
not exposed to occupational dust.
Eisen et al. (1983, 1995) found the opposite. They looked at lung
function in two groups of granite workers: "survivors", who
participated in each of five annual physical exams, and "dropouts",
who did not participate in the final exam. There was a significant
exposure-response relationship between exposure to crystalline silica
and FEV1 decline among the dropouts but not among the
survivors. The dropout group had a steeper FEV1 loss, and
this was true for each smoking category. The authors concluded that
exposures of about 50 ug/m\3\ produced a measurable effect on pulmonary
function in the dropouts. Eisen et al. (1995) felt that the "healthy
worker effect" was apparent in this study and that studies that only
looked at "survivors" would be less likely to see any effect of
silica on pulmonary function.
A 12-year follow-up of age- and smoking-matched granite crushers
and referents in Sweden found that over the follow-up period, the
granite crushers had significantly greater decreases in
FEV1, FEV1/FVC, maximum expiratory flow, and
FEF50 than the referents (Malmberg et al., 1993). A
longitudinal study of South African gold miners conducted by Hnizdo
(1992) found that cumulative dust exposure was a significant predictor
of most indices of decreases in lung function, including
FEV1 and FVC. A multiple linear regression analysis showed
that the effects of silica exposure and smoking were additive. Another
study of South African gold miners (Cowie, 1998) also found a loss of
FEV1 in those without silicosis. Finally, a study of U.S.
automotive foundry workers (Hertzberg et al., 2002) found a consistent
association with increased pulmonary function abnormalities and
estimated measures of cumulative silica exposure within 0.1 mg/m\3\.
The Hnizdo (1992), Cowie et al. (1993), and Cowie (1998) studies of
South African gold miners and the Malmberg et al. (1993) study of
Swedish granite workers found very similar reductions in
FEV1 attributable to silica dust exposure.
A number of prevalence studies have described relationships between
lung function loss and silica exposure or exposure measurement
surrogates (e.g., duration of exposure). These findings support those
of the longitudinal studies. Such results have been found in studies of
white South African gold miners (Hnizdo et al., 1990; Irwig and Rocks,
1978), black South African gold miners (Cowie and Mabena, 1991), Quebec
silica-exposed workers (Begin, et al., 1995), Singapore rock drilling
and crushing workers (Ng et al., 1992b), Vermont granite shed workers
(Theriault et al., 1974a, 1974b), aggregate quarry workers and coal
miners in Spain (Montes et al., 2004a, 2004b), concrete workers in The
Netherlands (Meijer et al., 2001), Chinese refractory brick
manufacturing workers in an iron-steel plant (Wang et al., 1997),
Chinese gemstone workers (Ng et al., 1987b), hard-rock miners in
Manitoba, Canada (Manfreda et al., 1982) and Colorado (Kreiss et al.,
1989), pottery workers in France (Neukirch et al., 1994), potato
sorters exposed to diatomaceous earth containing crystalline silica in
The Netherlands (Jorna et al., 1994), slate workers in Norway (Suhr et al., 2003), and
men in a Norwegian community (Humerfelt et al., 1998). Two of these
prevalence studies also addressed the role of smoking in lung function
impairment associated with silica exposure. In contrast to the
longitudinal study of South African gold miners discussed above
(Hnizdo, 1992), another study of South African gold miners (Hnizdo et
al., 1990) found that the joint effect of dust and tobacco smoking on
lung function impairment was synergistic, rather than additive. Also,
Montes et al. (2004b) found that the criteria for dust-tobacco
interactions were satisfied for FEV1 decline in a study of
Spanish aggregate quarry workers.
One of the longitudinal studies and many of the prevalence studies
discussed above directly addressed the question of whether silica-
exposed workers can develop pulmonary function impairment in the
absence of silicosis. These studies found that pulmonary function
impairment: (1) Can occur in silica-exposed workers in the absence of
silicosis, (2) was still evident when silicosis was controlled for in
the analysis, and (3) was related to the magnitude and duration of
silica exposure rather than to the presence or severity of silicosis.
Many researchers have concluded that a relationship exists between
exposure to silica and lung function impairment. IARC (1997) has
briefly reviewed studies on airways disease (i.e., chronic airflow
limitation and obstructive impairment of lung function) in its
monograph on crystalline silica carcinogenicity and concluded that
exposure to crystalline silica causes these effects. In its official
statement on the adverse effects of crystalline silica exposure, the
American Thoracic Society (ATS) (1997) included a section on airflow
obstruction. The ATS noted that, in most of the studies reviewed,
airflow limitation was associated with chronic bronchitis. The review
of Hnizdo and Vallyathan (2003) also addressed COPD due to occupational
silica exposure. They examined the epidemiological evidence for an
exposure-response relationship for airflow obstruction in studies where
silicosis was present or absent. Hnizdo and Vallyathan (2003) concluded
that chronic exposure to silica dust at levels that do not cause
silicosis may cause airflow obstruction.
Based on the evidence discussed above from a number of longitudinal
studies and numerous cross-sectional studies, OSHA preliminarily
concludes that there is an exposure-response relationship between
exposure to respirable crystalline silica and the development of
impaired lung function. The effect of tobacco smoking on this
relationship may be additive or synergistic. Also, pulmonary function
impairment has been shown to occur among silica-exposed workers who do
not show signs of silicosis.
4. Non-malignant Respiratory Disease Mortality
In this section, OSHA reviews studies on NMRD mortality that
focused on causes of death other than from silicosis. Two studies of
gold miners, a study of diatomaceous earth workers, and a case-control
analysis of death certificate data provide useful information.
Wyndham et al. (1986) found a significant excess mortality for
chronic respiratory diseases in a cohort of white South African gold
miners. Although these data did include silicosis mortality, the
authors found evidence demonstrating that none of the miners certified
on the death certificate as dying from silicosis actually died from
that disease. Instead, pneumoconiosis was always an incidental finding
in those dying from some other cause, the most common of which was
chronic obstructive lung disease. 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 dust exposure, with the relative risk estimated to be 2.48
per ten units of 1000 particle years of exposure.
A synergistic effect of smoking and cumulative dust exposure on
mortality from COPD was found in another study of white South African
gold miners (Hnizdo, 1990). 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. For cumulative
dust exposure, an exposure-response relationship was found, with the
analysis estimating that those with exposures of 10,000, 17,500, or
20,000 particle-years of exposure had a 2.5-, 5.06-, or 6.4-times
higher mortality risk for COPD, respectively, than those with the
lowest dust exposure of less than 5000 particle-years. The authors
concluded that dust alone would not lead to increased COPD mortality
but that dust and smoking act synergistically to cause COPD and were
thus the main risk factor for death from COPD in their study.
Park et al. (2002) analyzed the California diatomaceous earth
cohort data originally studied by Checkoway et al. (1997), 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 Park et al. (2002) to at
least partially adjust for smoking. Using the exposure estimates
developed for the cohort by Rice et al. (2001) in their exposure-
response study of lung cancer risks, Park et al. (2002) evaluated the
quantitative exposure-response relationship for LDOC mortality and
found a strong positive relationship with exposure to respirable
crystalline silica. OSHA finds this study particularly compelling
because of the strengths of the study design and availability of
smoking history data on part of the cohort and high-quality exposure
and job history data; consequently, OSHA has included this study in its
Preliminary Quantitative Risk Assessment.
In a case-control analysis of death certificate data drawn from 27
U.S. states, Calvert et al. (2003) found increased mortality odds
ratios among those in the medium and higher crystalline silica exposure
categories, a significant trend of increased risk for COPD mortality
with increasing silica exposures, and a significantly increased odds
ratio for COPD mortality in silicotics as compared to those without
silicosis.
Green and Vallyathan (1996) also reviewed several studies of NMRD
mortality in workers exposed to silica. The authors stated that these
studies showed an association between cumulative dust exposure and
death from the chronic respiratory diseases.
Based on the evidence presented in the studies above, OSHA
preliminarily concludes that respirable crystalline silica increases
the risk for mortality from non-malignant respiratory disease (not
including silicosis) in an exposure-related manner. However, it appears
that the risk is strongly influenced by smoking, and the effects of
smoking and silica exposure may be synergistic.
D. Renal and Autoimmune Effects
In recent years, evidence has accumulated that suggests an
association between exposure to crystalline silica and an increased
risk of renal disease. Over the past 10 years, epidemiologic studies have
been conducted that provide evidence of exposure-response trends to
support this association. There is also suggestive evidence that silica
can increase the risk of rheumatoid arthritis and other autoimmune
diseases (Steenland, 2005b). In fact, an autoimmune mechanism has been
postulated for some silica-associated renal disease (Calvert et al.,
1997). This section will discuss the evidence supporting an association
of silica exposure with renal and autoimmune diseases.
Overall, there is substantial evidence suggesting an association
between exposure to crystalline silica and increased risks of renal and
autoimmune diseases. In addition to a number of case reports,
epidemiologic studies have found statistically significant associations
between occupational exposure to silica dust and chronic renal disease
(e.g., Calvert et al., 1997), subclinical renal changes (e.g., Ng et
al., 1992c), end-stage renal disease morbidity (e.g., Steenland et al.,
1990), chronic renal disease mortality (Steenland et al., 2001b,
2002a), and Wegener's granulomatosis (Nuyts et al., 1995). In other
findings, silica-exposed individuals, both with and without silicosis,
had an increased prevalence of abnormal renal function (Hotz et al.,
1995), and renal effects have been reported to persist after cessation
of silica exposure (Ng et al., 1992c). Possible mechanisms suggested
for silica-induced renal disease include 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; Gregorini et al., 1993).
Several studies of exposed worker populations reported finding
excess renal disease mortality and morbidity. Wyndham et al. (1986)
reported finding excess mortality from acute and chronic nephritis
among South African goldminers that had been followed for 9 years.
Italian ceramic workers experienced an overall increase in the
prevalence of end-stage renal disease (ESRD) cases compared to regional
rates; the six cases that occurred among the workers had cumulative
exposures to crystalline silica of between 0.2 and 3.8 mg/m\3\-years
(Rapiti et al., 1999).
Calvert et al. (1997) found an increased incidence of non-systemic
ESRD cases among 2,412 South Dakota gold miners exposed to a median
crystalline silica concentration of 0.09 mg/m\3\. In another study of
South Dakota gold miners, Steenland and Brown (1995a) reported a
positive trend of chronic renal disease mortality risk and cumulative
exposure to respirable crystalline silica, but most of the excess
deaths were concentrated among workers hired before 1930 when exposures
were likely higher than in more recent years.
Excess renal disease mortality has also been described among North
American industrial sand workers. McDonald et al., (2001, 2005) found
that nephritis/nephrosis mortality was elevated overall among 2,670
industrial sand workers hired 20 or more years prior to follow-up, but
there was no apparent relationship with either cumulative or average
exposure to crystalline silica. However, Steenland et al. (2001b) did
find that increased mortality from acute and chronic renal disease was
related to increasing quartiles of cumulative exposure among a larger
cohort of 4,626 industrial sand workers. In addition, they also found a
positive trend for ESRD case incidence and quartiles of cumulative
exposure.
In a pooled cohort analysis, Steenland et al. (2002a) combined the
industrial sand cohort from Steenland et al. (2001b), gold mining
cohort from Steenland and Brown (1995a), and the Vermont granite cohort
studies by Costello and Graham (1988). In all, the combined cohort
consisted of 13,382 workers with exposure information available for
12,783. The exposure estimates were validated by the monotonically
increasing exposure-response trends seen in analyses of silicosis,
since cumulative silica levels are known to predict silicosis risk. The
mean duration of exposure, cumulative exposure, and concentration of
respirable silica for the cohort were 13.6 years, 1.2 mg/m\3\-years,
and 0.07 mg/m\3\, respectively.
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 0.5 mg/m\3\ or more
(Steenland et al., 2002a).
Other studies failed to find an excess renal disease risk among
silica-exposed workers. Davis et al. (1983) found an elevated, but not
a statistically significant increase, in 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) among
Finnish granite workers, where there were 4 deaths due to urinary tract
disease compared to 1.8 expected. Both Carta et al. (1994) and Cocco et
al. (1994) reported finding no increased mortality from urinary tract
disease among workers in an Italian lead mine and a zinc mine. However,
Cocco et al. (1994) commented that exposures to respirable crystalline
silica were low, averaging 0.007 and 0.09 mg/m\3\ in the two mines,
respectively, and that their study in particular had low statistical
power to detect excess mortality.
There are many case series, case-control, and cohort studies that
provide support for a causal relationship between exposure to
respirable crystalline silica and an increased renal disease risk
(Kolev et al., 1970; Osorio et al., 1987; Steenland et al., 1990;
Gregorini et al., 1993; Nuyts et al., 1995). In addition, a number of
studies have demonstrated early clinical signs of renal dysfunction
(i.e., urinary excretion of low- and high-molecular weight proteins and
other markers of renal glomerular and tubular disruption) in workers
exposed to crystalline silica, both with and without silicosis (Ng et
al., 1992c; Hotz et al., 1995; Boujemaa, 1994; Rosenman et al., 2000).
OSHA believes that there is substantial evidence on which to base a
finding that exposure to respirable crystalline silica increases the
risk of renal disease mortality and morbidity. In particular, OSHA
believes that the 3-cohort pooled analysis conducted by Steenland et
al. (2002a) is particularly convincing. OSHA believes that the findings
of this pooled analysis seem credible because the analysis involved a
large number of workers from three cohorts with well-documented,
validated job-exposure matrices and found a positive and monotonic
increase in renal disease risk with increasing exposure for both
underlying and multiple cause data. However, there are considerably
less data, and thus the findings based on them are less robust, than
what is available for silicosis mortality or lung cancer mortality.
Nevertheless, OSHA preliminarily concludes that the underlying data are
sufficient to provide useful estimates of risk and has included the
Steenland et al. (2002a) analysis in its Preliminary Quantitative Risk
Assessment.
Several studies of different designs, including case series,
cohort, registry linkage and case-control, conducted in a variety of
exposed groups suggest an association between silica exposure and
increased risk of systemic autoimmune disease (Parks et al., 1999).
Studies have found that the most common autoimmune diseases associated
with silica exposure are scleroderma (e.g., Sluis-Cremer et al., 1985);
rheumatoid arthritis (e.g. Klockars et al., 1987; Rosenman and Zhu,
1995); and systemic lupus erythematosus (e.g., Brown et al., 1997).
Mechanisms suggested for silica-related autoimmune disease include an
adjuvant effect of silica (Parks et al., 1999), activation of the
immune system by the fibrogenic proteins and growth factors released as
a result of the interaction of silica particles with macrophages (e.g.,
Haustein and Anderegg, 1998), and a direct local effect of non-
respirable silica particles penetrating the skin and producing
scleroderma (Green and Vallyathan, 1996). However, there are no
quantitative exposure-response data available at this time on which to
base a quantitative risk assessment for autoimmune diseases.
Therefore, OSHA preliminarily concludes that there is substantial
evidence that silica exposure increases the risks of renal and
autoimmune disease. The positive and monotonic exposure-response trends
demonstrated for silica exposure and renal disease risk more strongly
suggest a causal link. The studies by Steenland et al. (2001b, 2002a)
and Steenland and Brown (1995a) provide evidence of a positive
exposure-response relationship. For autoimmune diseases, the available
data did not provide an adequate basis for assessing exposure-response
relationships. However, OSHA believes that the available exposure-
response data on silica exposure and renal disease is sufficient to
allow for quantitative estimates of risk.
E. Physical Factors That May Influence Toxicity of Crystalline Silica
Much research has been conducted to investigate the influence of
various physical factors on the toxicologic potency of crystalline
silica. Such factors examined include crystal polymorphism; the age of
fractured surfaces of the crystal particle; the presence of impurities,
particularly metals, on particle surfaces; and clay occlusion of the
particle. These factors likely vary among different workplace settings
suggesting that the risk to workers exposed to a given level of
respirable crystalline silica may not be equivalent in different work
environments. In this section, OSHA examines the research demonstrating
the effects of these factors on the toxicologic potency of silica.
The modification of surface characteristics by the physical factors
noted above may alter the toxicity of silica by affecting the physical
and biochemical pathways of the mechanistic process. Thus, OSHA has
reviewed the proposed mechanisms by which silica exposure leads to
silicosis and lung cancer. It has been proposed that silicosis results
from a cycle of cell damage, oxidant generation, inflammation, scarring
and fibrosis. A silica particle entering the lung can cause lung damage
by two major mechanisms: direct damage to lung cells due to the silica
particle's unique surface properties or by the activation or
stimulation of alveolar macrophages (after phagocytosis) and/or
alveolar epithelial cells. In either case, an elevated production of
reactive oxygen and nitrogen species (ROS/RNS) results in oxidant
damage to lung cells. The oxidative stress and lung injury stimulates
alveolar macrophages and/or alveolar epithelial cells to produce growth
factors and fibrogenic mediators, resulting in fibroblast activation
and pulmonary fibrosis. A continuous ingestion-reingestion cycle, with
cell activation and death, is established.
OSHA has 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; Wagner et al., 1980). 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; Guthrie and Heaney, 1995).
Furthermore, a difference in toxicity between cristobalite and quartz
has not been observed in epidemiologic studies (tridymite has not been
studied) (NIOSH, 2002). In an analysis of exposure-response for lung
cancer, Steenland et al. (2001a) found similar exposure-response trends
between cristobalite-exposed workers and other cohorts exposed to
quartz.
A number of studies have compared the toxicity of freshly fractured
versus aged silica. Although animal studies have demonstrated that
freshly fractured silica is more toxic than aged silica, aged silica
still retains significant toxicity (Porter et al., 2002; Shoemaker et
al., 1995; Vallyathan et al., 1995). 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; Goodman et al., 1992). There
have been no studies, however, comparing workers exposed to freshly
fractured silica to those exposed to aged silica. 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).
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. Aluminum has been shown
to decrease toxicity (Castranova et al., 1997; Donaldson and Borm,
1998; Fubini, 1998). Silica coated with aluminosilicate clay exhibits
lower toxicity, possibly as a result of reduced bioavailability of the
silica particle surface (Donaldson and Borm, 1998; Fubini, 1998). This
reduced bioavailability may be due to aluminum ions left on the silica
surface by the clay (Bruch et al., 2004; Cakmak et al., 2004; Fubini et
al., 2004). Aluminum and 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). An epidemiologic
study found that the risk of silicosis was less in pottery workers than
in tin and tungsten miners (Chen et al., 2005; Harrison et al., 2005),
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. The authors concluded that clay
occlusion of silica particles can be a factor in reducing disease risk.
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 had been conducted to investigate the surface
characteristics of crystalline silica particles and their influence on
fibrogenic activity, NIOSH (2002) 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. According to NIOSH (2002), such exposures may
include work processes that produce freshly fractured silica surfaces
or that involve quartz contaminated with trace elements such as iron.
NIOSH called for further in vitro and in vivo studies of the toxicity
and pathogenicity of alpha quartz compared with its polymorphs, quartz
contaminated with trace elements, and further research on the
association of surface properties with specific work practices and
health effects.
In discussing the "considerable" heterogeneity shown across the
10 studies used in the pooled lung cancer risk analysis, Steenland et
al. (2001a) pointed to hypotheses that physical differences in silica
exposure (e.g., freshness of particle cleavage) between cohorts may be
a partial explanation of observed differences in exposure-response
coefficients derived from those cohort studies. However, the authors
did not have specific information on whether or how these factors might
have actually influenced the observed differences. Similarly, in the
pooled analysis and risk assessments for silicosis mortality conducted
by Mannetje et al. (2002b), differences in biological activity of
different types of silica dust could not be specifically taken into
account. Mannetje et al. (2002b) determined that the exposure-response
relationship between silicosis and log-transformed cumulative exposure
to crystalline silica was comparable between studies and no significant
heterogeneity was found. The authors therefore concluded that their
findings were relevant for different circumstances of occupational
exposure to crystalline silica. Both the Steenland et al. (2001a) and
Mannetje et al. (2002b) studies are discussed in detail in OSHA's
Preliminary Quantitative Risk Assessment (section II of the background
document and summarized in section VI of this preamble).
OSHA preliminarily concludes that there is considerable evidence to
support the hypothesis that surface activity of crystalline silica
particles plays an important role in producing disease, and that
several environmental influences can modify surface activity to either
enhance or diminish the toxicity of silica. However, OSHA believes that
the available information is insufficient to determine in any
quantitative way how these influences may affect disease risk to
workers in any particular workplace setting.
VI. Summary of OSHA's Preliminary Quantitative Risk Assessment
A. Introduction
The Occupational Safety and Health Act (OSH Act or Act) and some
landmark court cases have led OSHA to rely on quantitative risk
assessment, to the extent possible, to support the risk determinations
required to set a permissible exposure limit (PEL) for a toxic
substance in standards under the OSH Act. A determining factor in the
decision to perform a quantitative risk assessment is the availability
of suitable data for such an assessment. In the case of crystalline
silica, there has been extensive research on its health effects, and
several quantitative risk assessments have been published in the peer-
reviewed scientific literature that describe the risk to exposed
workers of lung cancer mortality, silicosis mortality and morbidity,
non-malignant respiratory disease mortality, and renal disease
mortality. These assessments were based on several studies of
occupational cohorts in a variety of industry sectors, the underlying
studies of which are described in OSHA's review of the health effects
literature (see section V of this preamble). In this section, OSHA
summarizes its Preliminary Quantitative Risk Assessment (QRA) for
crystalline silica, which is presented in Section II of the background
document entitled "Respirable Crystalline Silica--Health Effects
Literature Review and Preliminary Quantitative Risk Assessment"
(placed in Docket OSHA-2010-0034).
OSHA has done what it believes to be a comprehensive review of the
literature to provide quantitative estimates of risk for crystalline
silica-related diseases. Quantitative risk assessments for lung cancer
and silicosis mortality were published after the International Agency
for Research on Cancer (IARC) determined more than a decade ago that
there was sufficient evidence to regard crystalline silica as a human
carcinogen (IARC, 1997). This finding was based on several studies of
worker cohorts demonstrating associations between exposure to
crystalline silica and an increased risk of lung cancer. Although IARC
judged the overall evidence as being sufficient to support this
conclusion, IARC also noted that some studies of crystalline silica-
exposed workers 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. These findings led Steenland et
al. (2001a) and Mannetje et al. (2002b) to conduct comprehensive
exposure-response analyses of the risk of lung cancer and silicosis
mortality associated with exposure to crystalline silica. These
studies, referred to as the IARC multi-center studies of lung cancer
and silicosis mortality, 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. In addition, OSHA identified
four single-cohort studies of lung cancer mortality that it judged
suitable for quantitative risk assessment; two of these cohorts
(Attfield and Costello, 2004; Rice et al., 2001) were included among
the 10 used in the IARC multi-center study and studies of two other
cohorts appeared later (Hughes et al., 2001; McDonald et al., 2001,
2005; Miller and MacCalman, 2009). For non-malignant respiratory
disease mortality, in addition to the silicosis mortality study by
Mannetje et al. (2002b), Park et al. (2002) conducted an exposure-
response analysis of non-malignant respiratory disease mortality
(including silicosis and other chronic obstructive pulmonary diseases)
among diatomaceous earth workers. Exposure-response analyses for
silicosis morbidity have been published in several single-cohort
studies (Chen et al., 2005; Hnizdo and Sluis-Cremer, 1993; Steenland
and Brown, 1995b; Miller et al., 1998; Buchanan et al., 2003). Finally,
a quantitative assessment of end-stage renal disease mortality based on
data from three worker cohorts was developed by Steenland et al.
(2002a).
In addition to these published studies, OSHA's contractor,
Toxichemica, Inc., commissioned Drs. Kyle Steenland and Scott Bartell
of Emory University to perform an uncertainty analysis to examine the
effect on lung cancer and silicosis mortality risk estimates of
uncertainties that exist in the exposure assessments underlying the two
IARC multi-center analyses (Toxichemica, Inc., 2004).
OSHA's Preliminary QRA presents estimates of the risk of silica-
related diseases assuming exposure over a working life (45 years) to
the proposed 8-hour time-weighted average (TWA) PEL and action level of
0.05 and 0.025 mg/m\3\, respectively, of respirable crystalline silica,
as well as to OSHA's current PELs. OSHA's current general industry PEL
for respirable quartz is expressed both in terms of a particle count
formula and a gravimetric concentration formula, while the current
construction and shipyard employment PELs for respirable quartz are
only expressed in terms of a particle count formula. The current PELs
limit exposure to respirable dust; the specific limit in any given
instance depends on the concentration of crystalline silica in the
dust. For quartz, the gravimetric general industry PEL approaches a
limit of 0.1 mg/m\3\ as respirable quartz as the quartz content
increases (see discussion in Section XVI of this preamble, Summary and
Explanation for paragraph (c)). OSHA's Preliminary QRA presents risk
estimates for exposure over a working lifetime to 0.1 mg/m\3\ to represent the risk
associated with exposure to the current general industry PEL. OSHA's
current PEL for construction and shipyard employment is a formula PEL
that limits exposure to respirable dust expressed as a respirable
particle count concentration. As with the gravimetric general industry
PEL, the limit varies depending on quartz content of the dust. There is
no single mass concentration equivalent for the construction and
shipyard PELs; OSHA's Preliminary QRA reviews several studies that
suggest that the current construction/shipyard PEL likely lies in the
range between 0.25 and 0.5 mg/m\3\ respirable quartz, and OSHA presents
risk estimates for this range of exposure to represent the risks
associated with exposure to the current construction/shipyard PEL. In
general industry, for both the gravimetric and particle count PELs,
OSHA's current PEL for cristobalite and tridymite are half the value
for quartz. Thus, OSHA's Preliminary QRA presents risk estimates
associated with exposure over a working lifetime to 0.025, 0.05, 0.1,
0.25, and 0.5 mg/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\-
years).
Risk estimates for lung cancer mortality, silicosis and non-
malignant respiratory disease mortality, and renal disease mortality
are presented in terms of lifetime (up to age 85) 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 the 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.
A draft preliminary quantitative risk assessment document was
submitted for external scientific peer review in accordance with the
Office of Management and Budget's "Final Information Quality Bulletin
for Peer Review" (OMB, 2004). A summary of OSHA's responses to the
peer reviewers' comments appears in Section III of the background
document.
In the sections below, OSHA describes the studies and the published
risk assessments it uses to estimate the occupational risk of
crystalline silica-related disease. (The Preliminary QRA itself also
discusses several other available studies that OSHA does not include
and OSHA's reasons for not including these studies.)
B. Lung Cancer Mortality
1. Summary of Studies
In its Preliminary QRA, OSHA discusses risk assessments from six
published studies that quantitatively analyzed exposure-response
relationships for crystalline silica and lung cancer; some of these
also provided estimates of risks associated with exposure to OSHA's
current PEL or NIOSH's Recommended Exposure Limit (REL) of 0.05 mg/
m\3\. These studies include: (1) A quantitative analysis by Steenland
et al. (2001a) of worker cohort data pooled from ten studies; (2) an
exposure-response analysis by Rice et al. (2001) of a cohort of
diatomaceous earth workers primarily exposed to cristobalite; (3) an
analysis by Attfield and Costello (2004) of U.S. granite workers; (4) a
risk assessment by Kuempel et al. (2001), who employed a kinetic rat
lung model to describe the relationship between quartz lung burden and
cancer risk, then calibrated and validated that model using the
diatomaceous earth worker and granite worker cohort mortality data; (5)
an exposure-response analysis by Hughes et al., (2001) of U.S.
industrial sand workers; and (6) a risk analysis by Miller et al.
(2007) and Miller and MacCalman (2009) of British coal miners. These
six studies are described briefly below and are followed by a summary
of the lung cancer risk estimates derived from these studies.
a. Steenland et al. (2001a) Pooled Cohort Analysis
OSHA considers the lung cancer analysis conducted by Steenland et
al. (2001a) to be of prime importance for risk estimation because of
its size, incorporation of data from multiple cohorts, and availability
of detailed exposure and job history data. Subsequent to its
publication, Steenland and Bartell (Toxichemica, Inc., 2004) conducted
a quantitative uncertainty analysis on the pooled data set to evaluate
the potential impact on the risk estimates of random and systematic
exposure misclassification, and Steenland (personal communication,
2010) conducted additional exposure-response modeling.
The original study consisted of a pooled exposure-response analysis
and risk assessment based on raw data obtained from ten cohorts of
silica-exposed workers (65,980 workers, 1,072 lung cancer deaths).
Steenland et al. (2001a) initially identified 13 cohort studies as
containing exposure information sufficient to develop a quantitative
exposure assessment; the 10 studies included in the pooled analysis
were those for which data on exposure and health outcome could be
obtained for individual workers. The cohorts in the pooled analysis
included U.S. gold miners (Steenland and Brown, 1995a), U.S.
diatomaceous earth workers (Checkoway et al., 1997), Australian gold
miners (de Klerk and Musk, 1998), Finnish granite workers (Koskela et
al., 1994), U.S. industrial sand employees (Steenland and Sanderson,
2001), Vermont granite workers (Costello and Graham, 1988), South
African gold miners (Hnizdo and Sluis-Cremer, 1991; Hnizdo et al.,
1997), and Chinese pottery workers, tin miners, and tungsten miners
(Chen et al., 1992).
The exposure assessments developed for the pooled analysis are
described by Mannetje et al. (2002a). The exposure information and
measurement methods used to assess exposure from each of the 10 cohort
studies varied by cohort and by time and included dust measurements
representing particle counts, mass of total dust, and respirable dust
mass. All exposure information was converted to units of mg/m\3\
respirable crystalline silica by generating cohort-specific conversion
factors based on the silica content of the dust to which workers were
exposed.
A case-control study design was employed for which cases and
controls were matched for race, sex, age (within 5 years) and study;
100 controls were matched to each case. To test the reasonableness of
the cumulative exposure estimates for cohort members, Mannetje et al.
(2002a) examined exposure-response relationships for silicosis
mortality by performing a nested case-control analysis for silicosis or
unspecified pneumoconiosis using conditional logistic regression. Each
cohort was stratified into quartiles by cumulative exposure, and
standardized rate ratios (SRR) for silicosis were calculated using the
lowest-exposure quartile as the baseline. Odds ratios (OR) for
silicosis were also calculated for the pooled data set overall, which
was stratified into quintiles based on cumulative exposure.
For the pooled data set, the relationship between odds ratio for
silicosis mortality and increasing cumulative exposure was "positive
and reasonably monotonic", ranging from 3.1 for the lowest quartile of
exposure to 4.8 for the highest. In addition, in seven of the ten
individual cohorts, there were statistically significant trends between
silicosis mortality rate ratios (SRR) and cumulative exposure. For two
of the cohorts (U.S. granite workers and U.S. gold miners), the trend
test was not statistically significant (p=0.10). A trend analysis could
not be performed on the South African gold miner cohort since silicosis
was not coded as an underlying cause of death in that country. A more
rigorous analysis of silicosis mortality on pooled data from six of
these cohorts also showed a strong, statistically significant
increasing trend with increasing decile of cumulative exposure
(Mannetje et al., 2002b), providing additional evidence for the
reasonableness of the exposure assessment used for the Steenland et al
(2001a) lung cancer analysis.
For the pooled lung cancer mortality analysis, Steenland et al.
(2001a) conducted a nested case-control analysis via Cox regression, in
which there were 100 controls chosen for each case randomly selected
from among cohort members who survived past the age at which the case
died, and matched on age (the time variable in Cox regression), study,
race/ethnicity, sex, and date of birth within 5 years (which, in
effect, matched on calendar time given the matching on age). Using
alternative continuous exposure variables in a log-linear relative risk
model (log RR=[beta]x, where x represents the exposure variable and
[beta] the coefficient to be estimated), Steenland et al. (2001a) found
that the use of either 1) cumulative exposure with a 15-year lag, 2)
the log of cumulative exposure with a 15-year lag, or 3) average
exposure resulted in positive statistically significant (p<=0.05)
exposure-response coefficients. The models that provided the best fit
to the data were those that used cumulative exposure and log-
transformed cumulative exposure. The fit of the log-linear model with
average exposure was clearly inferior to those using cumulative and
log-cumulative exposure metrics.
There was significant heterogeneity among studies (cohorts) using
either cumulative exposure or average exposure. The authors suggested a
number of possible reasons for such heterogeneity, including errors in
measurement of high exposures (which tends to have strong influence on
the exposure-response curve when untransformed exposure measures are
used), the differential toxicity of silica depending on the crystalline
polymorph, the presence of coatings or trace minerals that alter the
reactivity of the crystal surfaces, and the age of the fractured
surfaces. Models that used the log transform of cumulative exposure
showed no statistically significant heterogeneity among cohorts
(p=0.36), possibly because they are less influenced by very high
exposures than models using untransformed cumulative exposure. For this
reason, as well as the good fit of the model using log-cumulative
exposure, Steenland et al. (2001a) conducted much of their analysis
using log-transformed cumulative exposure. The sensitivity analysis by
Toxichemica, Inc. (2004) repeated this analysis after correcting some
errors in the original coding of the data set. At OSHA's request,
Steenland (2010) also conducted a categorical analysis of the pooled
data set and additional analyses using linear relative risk models
(with and without log-transformation of cumulative exposure) as well as
a 2-piece spline model.
The cohort studies included in the pooled analysis relied in part
on particle count data and the use of conversion factors to estimate
exposures of workers to mass respirable quartz. A few studies were able
to include at least some respirable mass sampling data. OSHA believes
that uncertainty in the exposure assessments that underlie each of the
10 studies included in the pooled analysis is likely to represent one
of the most important sources of uncertainty in the risk estimates. To
evaluate the potential impact of uncertainties in the underlying
exposure assessments on estimates of the risk, OSHA's contractor,
Toxichemica, Inc. (2004), commissioned Drs. Kyle Steenland and Scott
Bartell of Emory University to conduct an uncertainty analysis using
the raw data from the pooled cancer risk assessment. The uncertainty
analysis employed a Monte Carlo technique in which two kinds of random
exposure measurement error were considered; these were (1) random
variation in respirable dust measurements and (2) random error in
estimating respirable quartz exposures from historical data on particle
count concentration, total dust mass concentration, and respirable dust
mass concentration measurements. Based on the results of this
uncertainty analysis, OSHA does not have reason to believe that random
error in the underlying exposure estimates in the Steenland et al.
(2001a) pooled cohort study of lung cancer is likely to have
substantially influenced the original findings, although a few
individual cohorts (particularly the South African and Australian gold
miner cohorts) appeared to be sensitive to measurement errors.
The sensitivity analysis also examined the potential effect of
systematic bias in the use of conversion factors to estimate respirable
crystalline silica exposures from historical data. Absent a priori
reasons to suspect bias in a specific direction (with the possible
exception of the South African cohort), Toxichemica, Inc. (2004)
considered possible biases in either direction by assuming that
exposure was under-estimated by 100% (i.e., the true exposure was twice
the estimated) or over-estimated by 100% (i.e., the true exposure was
half the estimated) for any given cohort in the original pooled
dataset. 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. Therefore, based on the results of the uncertainty analysis,
OSHA believes that misclassification errors of a reasonable magnitude
in the estimation of historical exposures for the 10 cohort studies
were not likely to have substantially biased risk estimates derived
from the exposure-response model used by Steenland et al. (2001a).
b. Rice et al. (2001) Analysis of Diatomaceous Earth Workers
Rice et al. (2001) applied a variety of exposure-response models to
the same California diatomaceous earth cohort data originally reported
on by Checkoway et al. (1993, 1996, 1997) and included in the pooled
analysis conducted by Steenland et al. (2001a) described above. 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. (2001) relied on the dust exposure
assessment developed by Seixas et al. (1997) from company records of
over 6,000 samples collected from 1948 to 1988; cristobalite was the
predominate form of crystalline silica to which the cohort was exposed.
Analysis was based on both Poisson regression models Cox's proportional
hazards models with various functions of cumulative silica exposure in
mg/m\3\-years to estimate the relationship between silica exposure and
lung cancer mortality rate. Rice et al. (2001) 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.
c. Attfield and Costello (2004) Analysis of Granite Workers
Attfield and Costello (2004) analyzed the same U.S. granite cohort
originally studied by Costello and Graham (1988) and Davis et al.
(1983) and included in the Steenland et al. (2001a) pooled analysis,
consisting 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. Their 2004 report extended follow-up
from 1982 to 1994, and found 201 deaths. Workers' cumulative exposures
were estimated by Davis et al. (1983) based on historical exposure data
collected in six environmental surveys conducted between 1924 and 1977,
plus work history information.
Using Poisson regression models and seven cumulative exposure
categories, the authors reported that the results of the categorical
analysis showed a generally increasing trend of lung cancer rate ratios
with increasing cumulative exposure, with seven lung cancer death rate
ratios ranging from 1.18 to 2.6. A complication of this analysis was
that the rate ratio for the highest exposure group in the analysis
(cumulative exposures of 6.0 mg/m\3\-years or higher) was substantially
lower than those for other exposure groups. Attfield and Costello
(2004) reported that the best-fitting model was based on a 15-year lag,
use of untransformed cumulative exposure, and omission of the highest
exposure group.
The authors argued that it was appropriate to base their risk
estimates on a model that was fitted without the highest exposure group
for several reasons. They believed the underlying exposure data for the
high-exposure group was weaker than for the others, and that there was
a greater likelihood that competing causes of death and misdiagnoses of
causes of death attenuated the lung cancer death rate. Second, all of
the remaining groups comprised 85 percent of the deaths in the cohort
and showed a strong linear increase in lung cancer mortality with
increasing exposure. Third, Attfield and Costello (2004) believed that
the exposure-response relationship seen in the lower exposure groups
was more relevant given that the exposures of these groups were within
the range of current occupational standards. Finally, the authors
stated that risk estimates derived from the model after excluding the
highest exposure group were more consistent with other published risk
estimates than was the case for estimates derived from the model using
all exposure groups. Because of these reasons, OSHA believes it is
appropriate to rely on the model employed by Attfield and Costello
(2004) after omitting the highest exposure group.
d. Kuempel et al. (2001) Rat-Based Model for Human Lung Cancer
Kuempel et al. (2001) published a rat-based toxicokinetic/
toxicodynamic model for silica exposure for predicting human lung
cancer, based on lung burden concentrations necessary to cause the
precursor events that can lead to adverse physiological effects in the
lung. These adverse physiological effects can then lead to lung
fibrosis and an indirect genotoxic cause of lung cancer. The
hypothesized first step, or earliest expected response, in these
disease processes is chronic lung inflammation, which the authors
consider as a disease limiting step. Since the NOAEL of lung burden
associated with this inflammation, based on the authors' rat-to-human
lung model conversion, is the equivalent of exposure to 0.036 mg/m\3\
(Mcrit) for 45 years, exposures below this level would
presumably not lead to (based on an indirect genotoxic mechanism) lung
cancer, at least in the "average individual." Since silicosis also is
inflammation mediated, this exposure could also be considered to be an
average threshold level for that disease as well.
Kuempel et al. (2001) have used their rat-based lung cancer model
with human data, both to validate their model and to estimate the lung
cancer risk as a function of quartz lung burden. First they
"calibrated" human lung burdens from those in rats based on exposure
estimates and lung autopsy reports of U.S. coal miners. Then they
validated these lung burden estimates using quartz exposure data from
U.K. coal miners. Using these human lung burden/exposure concentration
equivalence relationships, they then converted the cumulative exposure-
lung cancer response slope estimates from both the California
diatomaceous earth workers (Rice et al., 2001) and Vermont granite
workers (Attfield and Costello, 2001) to lung burden-lung cancer
response slope estimates. Finally, they used these latter slope
estimates in a life table program to estimate lung cancer risk
associated with their "threshold" exposure of 0.036 mg/m\3\ and to
the OSHA PEL and NIOSH REL. Comparing the estimates from the two
epidemiology studies with those based on a male rat chronic silica
exposure study the authors found that, " the lung cancer excess risk
estimates based on male rat data are approximately three times higher
than those based on the male human data." Based on this modeling and
validation exercise, Keumpel et al. concluded, "the rat-based
estimates of excess lung cancer risk in humans exposed to crystalline
silica are reasonably similar to those based on two human occupational
epidemiology studies."
Toxichemica, Inc. (2004) investigated whether use of the dosimetry
model would substantially affect the results of the pooled lung cancer
data analysis initially conducted by Steenland et al. (2001a). They
replicated the lung dosimetry model using Kuempel et al.'s (2001)
reported median fit parameter values, and compared the relationship
between log cumulative exposure and 15-year lagged lung burden at the
age of death in case subjects selected for the pooled case-control
analysis. The two dose metrics were found to be highly correlated
(r=0.99), and models based on either log silica lung burden or log
cumulative exposure were similarly good predictors of lung cancer risk
in the pooled analysis (nearly identical log-likelihoods of -4843.96
and--4843.996, respectively). OSHA believes that the Kuempel et al.
(2001) analysis is a credible attempt to quantitatively describe the
retention and accumulation of quartz in the lung, and to relate the
external exposure and its associated lung burden to the inflammatory
process. However, using the lung burden model to convert the cumulative
exposure coefficients to a different exposure metric appears to add
little additional information or insight to the risk assessments
conducted on the diatomaceous earth and granite cohort studies.
Therefore, for the purpose of quantitatively evaluating lung cancer
risk in exposed workers, OSHA has chosen to rely on the epidemiology
studies themselves and the cumulative exposure metrics used in those
studies.
e. Hughes et al. (2001), McDonald et al. (2001), and McDonald et al.
(2005) Study of North American Industrial Sand Workers
McDonald et al. (2001), Hughes et al. (2001) and McDonald et al.
(2005) followed up on a cohort study of North American industrial sand
workers that overlapped with the industrial sand cohort (18 plants,
4,626 workers) studied by Steenland and Sanderson (2001) and included
in Steenland et al.'s (2001a) pooled cohort analysis. The McDonald et
al. (2001) follow-up 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. Information on cause of
death was obtained, from 1960 through 1994, for 99 percent of the
deceased workers for a total 1,025 deaths representing 38 percent of
the cohort. A nested case-control study and analysis based on 90 lung
cancer deaths from this cohort was also conducted by Hughes et al.
(2001). A later update through 2000, of both the cohort and nested
case-control studies by McDonald et al. (2005), eliminated the Canadian
plant, following 2,452 men from the eight U.S. plants. For the lung
cancer case-control part of the study the update included 105 lung
cancer deaths. Both the initial and updated case control studies used
up to two controls per case.
Although the cohort studies provided evidence of increased risk of
lung cancer (SMR = 150, p = 0.001, based on U.S. rates) for deaths
occurring 20 or more years from hire, the nested case-control studies,
Hughes et al. (2001) and McDonald et al. (2005), allowed for individual
job, exposure, and smoking histories to be taken into account in the
exposure-response analysis for lung cancer. Both of these case-control
analyses relied on an analysis of exposure information reported by
Sanderson et al. (2000) and by Rando et al. (2001) to provide
individual estimates of average and cumulative exposure. Statistically
significant positive exposure-response trends for lung cancer were
found for both cumulative exposure (lagged 15 years) and average
exposure concentration, but not for duration of employment, after
controlling for smoking. A monotonic increase was seen for both lagged
and unlagged cumulative exposure when the four upper exposure
categories were collapsed into two. With exposure lagged 15 years and
after adjusting for smoking, increasing quartiles of cumulative silica
exposure were associated with lung cancer mortality (odds ratios of
1.00, 0.84, 2.02 and 2.07, p-value for trend=0.04). There was no
indication of an interaction effect of smoking and cumulative silica
exposure (Hughes et al., 2001).
OSHA considers this Hughes et al. (2001) study and analysis to be
of high enough quality to provide risk estimates for excess lung cancer
for silica exposure to industrial sand workers. Using the median
cumulative exposure levels of 0, 0.758, 2.229 and 6.183 mg/m\3\-years,
Hughes et al. estimated lung cancer odds ratios, ORs (no. of deaths),
for these categories of 1.00 (14), 0.84 (15), 2.02 (31), and 2.07 (30),
respectively, on a 15-year lag basis (p-value for trend=0.04.) For the
updated nested case control analysis, McDonald et al. (2005) found very
similar results, with exposure lagged 15 years and, after adjusting for
smoking, increasing quartiles of cumulative silica exposure were
associated with lung cancer ORs (no. of deaths) of 1.00 (13), 0.94
(17), 2.24 (38), and 2.66 (37) (p-value for trend=0.006). Because the
Hughes et al. (2001) report contained information that allowed OSHA to
better calculate exposure-response estimates and because of otherwise
very similar results in the two papers, OSHA has chosen to base its
lifetime excess lung cancer risk estimate for these industrial sand
workers on the Hughes et al. (2001) case-control study. Using the
median exposure levels of 0, 0.758, 2.229 and 6.183 mg-years/m\3\,
respectively, for each of the four categories described above, and
using the model: ln OR = [alpha] + [beta] x Cumulative Exposure, the
coefficient for the exposure estimate was [beta] = 0.13 per (mg/m\3\-
years), with a standard error of [beta] = 0.074 (calculated from the
trend test p-value in the same paper). In this model, with background
lung cancer risks of about 5 percent, the OR provides a suitable
estimate of the relative risk.
f. Miller et al. (2007) and Miller and MacCalman (2009) Study of
British Coal Workers Exposed to Respirable Quartz
Miller et al. (2007) and Miller and MacCalman (2009) continued a
follow-up mortality study, begun in 1970, of 18,166 coalminers from 10
British coalmines initially followed through the end of 1992 (Miller et
al., 1997). The two recent reports on mortality analyzed the cohort of
17,800 miners and extended the analysis through the end of 2005. By
that time there were 516,431 person years of observation, an average of
29 years per miner, with 10,698 deaths from all causes. Causes of
deaths of interest included pneumoconiosis, other non-malignant
respiratory diseases (NMRD), lung cancer, stomach cancer, and
tuberculosis. Three of the strengths of this study are its use of
detailed time-exposure measurements of both quartz and total mine dust,
detailed individual work histories, and individual smoking histories.
However, the authors noted that no additional exposure measurements
were included in the updated analysis, since all the mines had closed
by the mid 1980's.
For this cohort mortality study there were analyses using both
external (regional age-time and cause specific mortality rates)
internal controls. For the analysis from external mortality rates, the
all-cause mortality SMR from 1959 through 2005 was 100.9 (95% C.I.,
99.0-102.8), based on all 10,698 deaths. However, these death ratios
were not uniform over time. For the period from 1990 to 2005, the all-
cause SMR was 109.6 (95% C.I., 106.5-112.8), while the ratios for
previous periods were less than 100. This pattern of recent increasing
SMRs was also seen in the recent cause-specific death rate for lung
cancer, SMR=115.7 (95% C.I., 104.8-127.7). For the analysis based on
internal rates and using Cox regression methods, the relative risk for
lung cancer risk based on a cumulative quartz exposure equivalent to
approximately 0.055 mg/m\3\ for 45 years was RR = 1.14 (95% C.I., 1.04
to 1.25). This risk is adjusted for concurrent coal dust exposure and
smoking status, and incorporated a 15-year lag in quartz exposures. The
analysis showed a strong effect for smoking (independent of quartz
exposure) on lung cancer. For lung cancer, OSHA believes that the
analyses based on the Cox regression method provides strong evidence
that for these coal miners' quartz exposures were associated with
increased lung cancer risk, but that simultaneous exposures to coal
dust did not cause increased lung cancer risk. To estimate lung cancer
risk from this study, OSHA estimated the regression slope for a log-
linear relative risk model based on the Miller and MacCalman's (2009)
finding of a relative risk of 1.14 for a cumulative exposure of 0.055
mg/m\3\-years.
2. Summary of OSHA's Estimates of Lung Cancer Mortality Risk
Tables VI-1 and VI-2 summarize the excess lung cancer risk
estimates from occupational exposure to crystalline silica, based on
five of the six lung cancer risk assessments discussed above. OSHA's
estimates of lifetime excess lung cancer risk associated with 45 years
of exposure to crystalline silica at 0.1 mg/m\3\ (approximately the
current general industry PEL) range from 13 to 60 deaths per 1,000
workers. For exposure to the proposed PEL of 0.05 mg/m\3\, the lifetime
risk estimates calculated by OSHA are in the range of 6 to 26 deaths
per 1,000 workers. For a 45-year exposure at the proposed action level
of 0.025 mg/m\3\, OSHA estimates the risk to range from 3 to 23 deaths
per 1,000 workers. The results from these assessments are reasonably
consistent despite the use of data from different cohorts and the
reliance on different analytical techniques for evaluating dose-
response relationships. Furthermore, OSHA notes that in this range of
exposure, 0.025--0.1 mg/m\3\, there is statistical consistency between
the risk estimates, as evidenced by the considerable overlap in the 95-
percent confidence intervals of the risk estimates presented in Table
VI-1.
OSHA also estimates the lung cancer risk associated with 45 years
of exposure to the current construction/shipyard PEL (in the range of
0.25 to 0.5 mg/m\3\) to range from 37 to 653 deaths per 1,000 workers.
Exposure to 0.25 or 0.5 mg/m\3\ over 45 years represents cumulative
exposures of 11.25 and 22.5 mg-years/m\3\, respectively. This range of
cumulative exposure is well above the median cumulative exposure for
most of the cohorts used in the risk assessment, primarily because most
of the individuals in these cohorts had not been exposed for as long as
45 years. Thus, estimating lung cancer excess risks over this higher
range of cumulative exposures of interest to OSHA required some degree
of extrapolation and adds uncertainty to the estimates.
C. Silicosis and Non-Malignant Respiratory Disease Mortality
There are two published quantitative risk assessment studies of
silicosis and non-malignant respiratory disease (NMRD) mortality; a
pooled analysis of silicosis mortality by Mannetje et al. (2002b) of
data from six epidemiological studies, and an exposure-response
analysis of NMRD mortality among diatomaceous earth workers (Park et
al., 2002).
1. Mannetje et al. (2002b) Six Cohort Pooled Analysis
The Mannetje et al. (2002b) silicosis analysis was part of the IARC
ten cohort pooled study included in the Steenland et al. (2001a) lung
cancer mortality analysis above. These studies included 18,634 subjects
and 170 silicosis deaths (n = 150 for silicosis, and n = 20 unspecified
pneumoconiosis). The silicosis deaths had a median duration of exposure
of 28 years, a median cumulative exposure of 7.2 mg/m\3\-years, and a
median average exposure of 0.26 mg/m\3\, while the respective values of
the whole cohort were 10 years, 0.62 mg/m\3\-years, and 0.07 mg/m\3\.
Rates for silicosis adjusted for age, calendar time, and study were
estimated by Poisson regression; rates 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\-years) to
299/100,000 person-years in the highest category (>28.10 mg/m\3\-
years). Quantitative estimates of exposure to respirable silica (mg/
m\3\) were available for all six cohorts (Mannetje et al. 2002a).
Lifetime risk of silicosis mortality was estimated by accumulating
mortality rates over time using the formula
Risk = 1 - exp(-[sum]time * rate).
To estimate the risk of silicosis mortality at the current and
proposed PELs, OSHA used the model described by Mannetje et al. (2002b)
to estimate risk to age 85 but used rate ratios that were estimated
from a nested case-control design that was part of a sensitivity
analysis conducted by Toxichemica, Inc. (2004), rather than the Poisson
regression originally conducted by Mannetje et al. (2002b). The case-
control design was selected because it was expected to better control
for age; in addition, the rate ratios derived from the case-control
study reflect exposure measurement uncertainty via conduct of a Monte
Carlo analysis (Toxichemica, Inc., 2004).
2. Park et al. (2002) Study of Diatomaceous Earth Workers
Park et al. (2002) analyzed the California diatomaceous earth
cohort data originally studied by Checkoway et al. (1997), 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. Industrial hygiene data for
the cohort were available from the employer for total dust, silica
(mostly cristobalite), and asbestos. Park et al. (2002) used the
exposure assessment previously reported by Seixas et al. (1997) and
used by Rice et al. (2001) to estimate cumulative crystalline silica
exposures for each worker in the cohort based on detailed work history
files. The mean silica concentration for the cohort overall was 0.29
mg/m\3\ over the period of employment (Seixas et al., 1997). The mean
cumulative exposure values for total respirable dust and respirable
crystalline silica were 7.31 and 2.16 mg/m\3\-year, respectively.
Similar cumulative exposure estimates were made for asbestos. 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) to at least partially adjust for smoking. Estimates of LDOC
mortality risks were derived via Poisson and Cox's proportional hazards
models; a variety of relative rate model forms were fit to the data,
with a linear relative rate model being selected for risk estimation.
3. Summary Risk Estimates for Silicosis and NMRD Mortality
Table VI-2 presents OSHA's risk estimates for silicosis and NMRD
mortality derived from the Mannetje et al. (2002b) and Park et al.
(2002) studies, respectively. For 45 years of exposure to the current
general industry PEL (approximately 0.1 mg/m\3\ respirable crystalline
silica), OSHA's estimates of excess lifetime risk are 11 deaths per
1,000 workers for the pooled analysis and 83 deaths per 1,000 workers
based on Park et al.'s (2002) estimates. At the proposed PEL, estimates
of silicosis and NMRD mortality are 7 and 43 deaths per 1,000,
respectively. For exposures up to 0.25 mg/m\3\, the estimates based on
Park et al. are about 5 to 11 times as great as those calculated for
the pooled analysis of silicosis mortality (Mannetje et al., 2002b).
However, these two sets of risk estimates are not directly comparable.
First, the Park et al. analysis used untransformed cumulative exposure
as the exposure metric, whereas the Mannertje et al. analysis used log
cumulative exposure, which causes the exposure-response to flatten out
in the higher exposure ranges. Second, the mortality endpoint for the
Park et al. (2002) analysis is death from all non-cancer lung diseases,
including pneumoconiosis, emphysema, and chronic bronchitis, whereas
the pooled analysis by Mannetje et al. (2002b) included only deaths
coded as silicosis or other pneumoconiosis. Less than 25 percent of the
LDOC deaths in the Park et al. (2002) analysis were coded as silicosis
or other pneumoconiosis (15 of 67). As noted by Park et al. (2002), it
is likely that silicosis as a cause of death is often misclassified as
emphysema or chronic bronchitis; thus, Mannetje et al.'s (2002b)
selection of deaths may tend to underestimate the true risk of
silicosis mortality, and Park et al.'s (2002) analysis would more
fairly capture the total respiratory mortality risk from all non-
malignant causes, including silicosis and chronic obstructive pulmonary
disease.
D. Renal Disease Mortality
Steenland et al. (2002a) examined renal disease mortality in three
cohorts and evaluated exposure-response relationships from the pooled
cohort data. The three cohorts included U.S. gold miners (Steenland and
Brown, 1995a), U.S. industrial sand workers (Steenland et al., 2001b),
and Vermont granite workers (Costello and Graham, 1988), all three of
which are included in both the lung cancer mortality and silicosis
mortality pooled analyses reported above. Follow up for the U.S.
gold miners study was extended six years from that in the other pooled
analyses. Steenland et al. (2002a) reported that these cohorts were
chosen because data were available for both underlying cause mortality
and multiple cause mortality; this was believed important because renal
disease is often listed on death certificates without being identified
as an underlying cause of death. In the three cohorts, there were 51
total renal disease deaths using underlying cause, and 204 total renal
deaths using multiple cause mortality.
The combined cohort for the pooled analysis (Steenland et al.,
2002a) consisted of 13,382 workers with exposure information available
for 12,783 (95 percent). Exposure matrices for the three cohorts had
been used in previous studies (Steenland and Brown, 1995a; Attfield and
Costello, 2001; Steenland et al., 2001b). The mean duration of
exposure, the mean cumulative exposure, and the mean concentration of
respirable silica for the pooled cohort were 13.6 years, 1.2 mg/m\3\-
years, and 0.07 mg/m\3\, respectively. 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).
OSHA's estimates of renal disease mortality appear in Table VI-2.
Based on the life table analysis, OSHA estimates that exposure to the
current (0.10 mg/m\3\) and proposed general industry PEL (0.0.05 mg/
m\3\) over a working life would result in a lifetime excess renal
disease risk of 39 (95% CI 2-200) and 32 (95% CI 1.7-147) deaths per
1,000, respectively. For exposure to the current construction/shipyard
PEL, OSHA estimates the excess lifetime risk to range from 52 (95% CI
2.2-289) to 63 (95% CI 2.5-368) deaths per 1,000 workers.
E. Silicosis Morbidity
OSHA's Preliminary QRA summarizes the principal cross-sectional and
cohort studies that have quantitatively characterized relationships
between exposure to crystalline silica and development of radiographic
evidence of silicosis. Each of these studies relied on estimates of
cumulative exposure to evaluate the relationship between exposure and
silicosis prevalence in the worker populations examined. The health
endpoint of interest in these studies is the appearance of opacities on
chest roentgenograms indicative of pulmonary fibrosis.
The International Labour Organization's (ILO) 1980 International
Classification of Radiographs of the Pneumoconioses is accepted as the
standard against which chest radiographs are measured in epidemiologic
studies, for medical surveillance and for clinical evaluation.
According to this standard, if radiographic findings are or may be
consistent with pneumoconiosis, then the size, shape, and extent of
profusion of opacities are characterized by comparing the radiograph to
standard films. Classification by shape (rounded vs. irregular) and
size involves identifying primary and secondary types of small
opacities on the radiograph and classifying them into one of six size/
shape categories. The extent of profusion is judged from the
concentrations of opacities as compared with that on the standard
radiographs and is graded on a 12-point scale of four major categories
(0-3, with Category 0 representing absence of opacities), each with
three subcategories. 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.
Chest radiography is not the most sensitive tool used to diagnose
or detect silicosis. In 1993, Hnizdo et al. reported the results of a
study that compared autopsy and radiological findings of silicosis in a
cohort of 557 white South African gold miners. The average period from
last x-ray to autopsy was 2.7 years. Silicosis was not diagnosed
radiographically for over 60 percent of the miners for whom
pathological examination of lung tissue showed slight to marked
silicosis. The likelihood of false negatives (negative by x-ray, but
silicosis is actually present) increased with years of mining and
average dust exposure of the miners. The low sensitivity seen for
radiographic evaluation suggests that risk estimates derived from
radiographic evidence likely understate the true risk of developing
fibrotic lesions as a result of exposure to crystalline silica.
OSHA's Preliminary QRA examines multiple studies from which
silicosis occupational morbidity risks can be estimated. The studies
evaluated fall into three major types. Some are cross-sectional studies
in which radiographs taken at a point in time were examined to
ascertain cases (Kreiss and Zhen, 1996; Love et al., 1999; Ng and Chan,
1994; Rosenman et al., 1996; Churchyard et al., 2003, 2004); these
radiographs may have been taken as part of a health survey conducted by
the investigators or represent the most recent chest x-ray available
for study subjects. Other studies were designed to examine radiographs
over time in an effort to determine onset of disease. Some of these
studies examined primarily active, or current, workers (Hughes et al.,
1998; Muir et al., 1989a, 1989b; Park et al., 2002), while others
included both active and retired workers (Chen et al., 2001, 2005;
Hnizdo and Sluis-Cremer, 1993; Miller et al., 1998; Buchanan et al.,
2003; Steenland and Brown, 1995b).
Even though OSHA has presented silicosis risk estimates for all of
the studies identified, the Agency is relying primarily on those
studies that examined radiographs over time and included both active
and retired workers. It has been pointed out by others (Chen et al.,
2001; Finkelstein, 2000; NIOSH, 2002) that lack of follow-up of retired
workers consistently resulted in lower risk estimates compared to
studies that included retired workers. OSHA believes 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. Brief descriptions of these cumulative risk studies used
to estimate silicosis morbidity risks are presented below.
1. Hnizdo and Sluis Cremer (1993) Study of South African White Gold
Miners
Hnizdo and Sluis-Cremer (1993) described the results of a
retrospective cohort study of 2,235 white gold miners in South Africa.
These workers had received annual examinations and chest x-rays while
employed; most returned for occasional examinations after employment. A
case was defined as one with an x-ray classification of ILO 1/1 or
greater. A total of 313 miners had developed silicosis and had been
exposed for an average of 27 years at the time of diagnosis. Forty-
three percent of the cases were diagnosed while employed and the
remaining 57 percent were diagnosed an average of 7.4 years after
leaving the mines. The average latency for the cohort was 35 years
(range of 18-50 years) from start of exposure to diagnosis.
The average respirable dust exposure for the cohort overall was
0.29 mg/m\3\ (range 0.11-0.47), corresponding to an estimated average
respirable silica concentration of 0.09 mg/m\3\ (range
0.033-0.14). The average cumulative dust exposure for the overall
cohort was 6.6 mg/m\3\-years (range 1.2-18.7), or an average cumulative
silica exposure of 1.98 mg/m\3\-years (range 0.36-5.61). OSHA believes
that the exposure estimates for the cohort are uncertain given the need
to rely on particle count data generated over a fairly narrow
production period.
Silicosis risk increased exponentially with cumulative exposure to
respirable dust and was modeled using log-logistic regression. Using
the exposure-response relationship developed by Hnizdo and Sluis-Cremer
(1993), and assuming a quartz content of 30 percent in respirable dust,
Rice and Stayner (1995) and NIOSH (2002) estimated the risk of
silicosis to be 70 percent and 13 percent for a 45-year exposure to 0.1
and 0.05 mg/m\3\ respirable crystalline silica, respectively.
2. Steenland and Brown (1995b) Study of South Dakota Gold Miners
Three thousand three hundred thirty South Dakota gold miners who
had worked at least a year underground between 1940 and 1965 were
studied by Steenland and Brown (1995b). Workers were followed though
1990 with 1,551 having died; loss to follow up was low (2 percent).
Chest x-rays taken in cross-sectional surveys in 1960 and 1976 and
death certificates were used to ascertain cases of silicosis. One
hundred twenty eight cases were found via death certificate, 29 by x-
ray (defined as ILO 1/1 or greater), and 13 by both. Nine percent of
deaths had silicosis mentioned on the death certificate. Inclusion of
death certificate diagnoses probably increases the risk estimates from
this study compared to those that rely exclusively on radiographic
findings to evaluate silicosis morbidity risk (see discussion of Hnizdo
et al. (1993) above).
Exposure was estimated by conversion of impinger (particle count)
data and was based on measurements indicating an average of 13 percent
silica in the dust. Based on these data, the authors estimated the mean
exposure concentration to be 0.05 mg/m\3\ for the overall cohort, with
those hired before 1930 exposed to an average of 0.15 mg/m\3\. The
average duration of exposure for cases 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 authors estimated a risk of 47 percent associated with
45 years of exposure to 0.09 mg/m\3\ respirable crystalline silica,
which reduced to 35 percent after adjustment for age and calendar time.
3. Miller et al. (1995, 1998) and Buchanan et al. (2003) Study of
Scottish Coal Miners
Miller et al. (1995, 1998) and Buchanan et al. (2003) reported on a
1990/1991 follow-up study of 547 survivors of a 1,416 member cohort of
Scottish coal workers from a single mine. These men had 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. The population's exposures to both coal
and quartz dust had been measured in unique detail, for a substantial
proportion of the men's working lives." Thus, this cohort allowed for
the study of the effects of both higher and lower silica
concentrations, and exposure-rate effects on the development of
silicosis. The 1,416 men had all had previous radiographs dating from
before, during, or just after this high concentration period, and the
547 participating survivors received their follow-up chest x-rays
between November 1990 and April 1991. Follow-up interviews consisted of
questions on current and past smoking habits, and occupational history
since leaving the coal mine, which closed in 1981.
Silicosis cases were identified as such if the median
classification of the three readers indicated an ILO (1980)
classification of 1/0 or greater, plus a progression from the earlier
reading. Of the 547 men, 203 (38 percent) showed progression of at
least one ILO category from the 1970's surveys to the 1990-91 survey;
in 128 of these (24 percent) there was progression of two or more
steps. In the 1970's survey 504 men had a profusion score of 0; of
these, 120 (24 percent) progressed to an ILO classification of 1/0 or
greater. Of the 36 men who had shown earlier profusions of 1/0 or
greater, 27 (75 percent) showed further progression at the 1990/1991
follow-up. Only one subject showed a regression from any earlier
reading, and that was slight, from ILO 1/0 to 0/1.
To study the effects of exposure to high concentrations of quartz
dust, the Buchanan et al. (2003) analysis presented the results of
logistic regression modeling that incorporated two independent terms
for cumulative exposure, one arising from exposure to concentrations
less than 2 mg/m\3\ respirable quartz and the other from exposure to
concentrations greater than or equal to 2 mg/m\3\. Both of the
cumulative quartz exposure concentration variables were "highly
statistically significant in the presence of the other," and
independent of the presence of coal dust. Since these quartz variables
were in the same units, g-hr/m\3\, the authors noted that coefficient
for exposure concentrations equal to or above 2.0 mg/m\3\ was 3 times
that of the coefficient for concentrations less than 2.0 mg/m\3\. From
this, the authors concluded that their analysis showed that "the risk
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) provided analysis and risk estimates only
for silicosis cases defined as having an x-ray classified as ILO 2/1+,
after adjusting for the disproportionately severe effect of exposure to
high concentrations on silicosis risk. Estimating the risk of acquiring
a chest x-ray classified as ILO 1/0+ from the Buchanan (2003) or the
earlier Miller et al. (1995, 1998) publications can only be roughly
approximated because of the limited summary information included; this
information suggests that the risk of silicosis defined as an ILO
classification of 1/0+ could be about three times higher than the risk
of silicosis defined as an ILO 2/1+ x-ray. OSHA has a high degree of
confidence in the estimates of progression to stages 2/1+ from this
Scotland coal mine study, mainly because of the highly detailed and
extensive exposure measurements, the radiographic records, and the
detailed analyses of high exposure-rate effects.
4. Chen et al. (2001) Study of Tin Miners
Chen et al. (2001) 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%) workers had either retired or
died, and only 400 (13.3%) remained employed at the mines.
The study incorporated occupational histories, dust measurements
and medical examination records. Exposure data consisted of high-flow,
short-term gravimetric total dust measurements made routinely since
1950; the authors used data from 1950 to represent earlier exposures
since dust control measures were not implemented until 1958. Results
from a 1998-1999 survey indicated that respirable silica measurements
were 3.6 percent (s.d = 2.5 percent) of total dust measurements. Annual
radiographs were taken since 1963 and all 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.
According to Chen et al. (2001), these four categories under the
Chinese system were found to agree closely with ILO categories 0/1,
Category 1, Category 2, and Category 3, respectively, based on studies
comparing the Chinese and ILO classification systems. Silicosis was
observed in 33.7 percent of the group; 67.4 percent of the cases
developed after exposure ended.
5. Chen et al. (2005) Study of Chinese Pottery Workers, Tin Miners, and
Tungsten Miners
In a later study, Chen et al. (2005) 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 selected from a total of 20 workplaces. Cohort
members included all males employed after January 1, 1950 and who
worked for at least one year between 1960 and 1974. Radiological
follow-up was through December 31, 1994 and x-rays were scored
according to the Chinese classification system as described above by
Chen et al. (2001) for the tin miner study. Exposure estimates of
cohort members to respirable crystalline silica were based on the same
data as described by Chen et al. (2001). In addition, the investigators
measured the extent of surface occlusion of crystalline silica
particles by alumino-silicate from 47 dust samples taken at 13
worksites using multiple-voltage scanning electron microscopy and
energy dispersive X-ray spectroscopy (Harrison et al., 2005); this
method yielded estimates of the percent of particle surface that is
occluded.
Compared to tin and tungsten miners, pottery workers were exposed
to significantly higher mean total dust concentrations (8.2 mg/m\3\,
compared to 3.9 mg/m\3\ for tin miners and 4.0 mg/m\3\ for tungsten
miners), worked more net years in dusty occupations (mean of 24.9 years
compared to 16.4 years for tin miners and 16.5 years for tungsten
miners), and had higher mean cumulative dust exposures (205.6 mg/m\3\-
years compared to 62.3 mg/m\3\-years for tin miners and 64.9 mg/m\3\-
years for tungsten miners) (Chen et al., 2005). Applying the authors'
conversion factors to estimate respirable crystalline silica from
Chinese total dust measurements, the approximate mean cumulative
exposures to respirable silica for pottery, tin, and tungsten workers
are 6.4 mg/m\3\-years, 2.4 mg/m\3\-years, and 3.2 mg/m\3\-years,
respectively. Measurement of particle surface occlusion 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.
Based on Chen et al. (2005), OSHA estimated the cumulative
silicosis risk associated with 45 years of exposure to 0.1 mg/m\3\
respirable crystalline silica (a cumulative exposure of 4.5 mg/m\3\-
years) to be 6 percent for pottery workers, 12 percent for tungsten
miners, and 40 percent for tin miners. For a cumulative exposure of
2.25 mg/m\3\-years (i.e., 45 years of exposure to 0.05 mg/m\3\),
cumulative silicosis morbidity risks were estimated to be 2, 2, and 10
percent for pottery workers, tungsten miners, and tin miners,
respectively. 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 workers, despite their having been more heavily exposed.
6. Summary of Silicosis Morbidity Risk Estimates.
Table VI-2 presents OSHA's risk estimates for silicosis morbidity
that are derived from each of the studies described above. Estimates of
silicosis morbidity derived from the seven cohorts in cumulative risk
studies with post-employment follow-up range from 60 to 773 per 1,000
workers for 45-year exposures to the current general industry PEL of
0.10 mg/m\3\, and from 20 to 170 per 1,000 workers for a 45-year
exposure to the proposed PEL of 0.05 mg/m\3\. The study results provide
substantial evidence that the disease can progress for years after
exposure ends. Results from an autopsy study (Hnizdo et al., 1993),
which found pathological evidence of silicosis absent radiological
signs, suggest that silicosis cases based on radiographic diagnosis
alone tend to underestimate risk since pathological evidence of
silicosis. Other results (Chen et al., 2005) suggest that surface
properties among various types of silica dusts can have different
silicosis potencies. Results from the Buchanan et al. (2003) study of
Scottish coal miners suggest that short-term exposures to >2 mg/m\3\
silica can cause a disproportionately higher risk of silicosis than
would be predicted by cumulative exposure alone, suggesting a dose-rate
effect for exposures to concentrations above this level. OSHA believes
that, given the consistent finding of a monotonic exposure-response
relationship for silicosis morbidity with cumulative exposure in the
studies reviewed, that cumulative exposure is a reasonable exposure
metric upon which to base risk estimates in the exposure range of
interest to OSHA (i.e., between 0.025 and 0.5 mg/m\3\ respirable
crystalline silica).
F. Other Considerations in OSHA's Risk Analysis
Uncertainties are inherent to any risk modeling process and
analysis; assessing risk and associated complexities of silica exposure
among workers is no different. However, the Agency has a high level of
confidence that the preliminary risk assessment results reasonably
reflect the range of risks experienced by workers exposed to silica in
all occupational settings. First, the preliminary assessment is based
on an analysis of a wide range of studies, conducted in multiple
industries across a wide range of exposure distributions, which
included cumulative exposures equivalent to 45 years of exposure to and
below the current PEL.
Second, risk models employed in this 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
job. Consequently, these models predict the same risk for a given
cumulative exposure regardless of the pattern of exposure. For example,
a manufacturing plant worker exposed to silica at 0.05 mg/m\3\ for
eight hours per day will have the same cumulative exposure over a given
period of time as a construction worker who is exposed each day to
silica at 0.1 mg/m\3\ for one hour, at 0.075 mg/m\3\ for four hours and
not exposed to silica for three hours. The cumulative exposure metric
thus reflects a worker's long-term average exposure without regard to
the pattern of exposure experienced by the worker, and is therefore
generally applicable to all workers who are exposed to silica in the
various industries. For example, at construction sites, conditions may
change often since the nature of work can be intermittent and involve
working with a variety of materials that contain different
concentrations of quartz. Additionally, workers may perform
construction operations for relatively short periods of time where they
are exposed to concentrations of silica that may be significantly
higher than many continuous operations in general industry. However,
these differences are taken into account by the use of the cumulative
exposure metric that relates exposure to disease risk. OSHA believes
that use of cumulative exposure is the most appropriate dose-metric
because each of the studies that provide the basis for the risk
assessment demonstrated strong exposure-response relationships between
cumulative exposure and disease risk. This metric is especially
important in terms of progression of silica-related disease, as
discussed in Section VII of the preamble, Significance of Risk, in
section B.1.a.
OSHA's risk assessment relied upon many studies that utilized
cumulative exposures of cohort members. Table VI-3 summarizes these
lung cancer studies, including worker exposure quartile data across a
number of industry sectors. The cumulative exposures exhibited in these
studies are equivalent to the cumulative exposure that would result
from 45 years of exposure to the current and proposed PELs (i.e., 4.5
and 2,25 mg/m\3\, respectively). For this reason, OSHA has a high
degree of confidence in the risk estimates associated with exposure to
the current and proposed PELs; additionally, the risk assessment does
not require significant low-dose extrapolation of the model beyond the
observed range of exposures. OSHA acknowledges there is greater
uncertainty in the risk estimates for the proposed action level of
0.025 mg/m\3\, particularly given some evidence of a threshold for
silicosis between the proposed PEL and action level. Given the Agency's
findings that controlling exposures below the proposed PEL would not be
technologically feasible for employers, OSHA believes that estimating
risk for exposures below the proposed action level, which becomes
increasingly more uncertain, is not necessary to further inform the
Agency's regulatory action.
Although the Agency believes that the results of its risk
assessment are broadly relevant to all occupational exposure situations
involving crystalline silica, OSHA acknowledges that differences exist
in the relative toxicity of crystalline silica particles present in
different work settings due to factors such as the presence of mineral
or metal impurities on quartz particle surfaces, whether the particles
have been freshly fractured or are aged, and size distribution of
particles. At this time, however, OSHA preliminarily concludes that it
is not yet possible to use available information on factors that
mediate the potency of silica to refine available quantitative
estimates of the lung cancer and silicosis mortality risks, and that
the estimates from the studies and analyses relied upon are fairly
representative of a wide range of workplaces reflecting differences in
silica polymorphism, surface properties, and impurities.
Table VI-1--Estimates of Lifetime \a\ Lung Cancer Mortality Risk Resulting from 45-Years of Exposure to Crystalline Silica
[Deaths per 1,000 workers (95% confidence interval)]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Exposure level (mg/m\3\)
Cohort Model Exposure Model parameters (standard -------------------------------------------------------------------------------
lag (years) error) 0.025 0.05 0.10 0.25 0.50
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Ten pooled cohorts (see Table II-1)...... Log-linear \b\............. 15 [beta] = 0.60 (0.015)...... 22 (11-36) 26 (12-41) 29 (13-48) 34 (15-56) 38 (17-63)
Linear \b\................. 15 [beta] = 0.074950 23 (9-38) 26 (10-43) 29 (11-47) 33 (12-53) 36 (14-58)
(0.024121).
Linear..................... 15 [beta]1 = 0.16498 (0.0653) 9 (2-16) 18 (4-31) 22 (6-38) 27 (12-43) 36 (20-51)
and.
SplineSec. \c\ \d\........ ........... [beta]2 = -0.1493 (0.0657). .............. .............. .............. .............. ..............
Range from 10 cohorts.................... ........................... 15 Various.................... 0.21-13 0.41-28 0.83-69 2.1-298 4.2-687
Log-linear \c\............. ........... .............. .............. .............. .............. ..............
Diatomaceous earth workers............... Linear \c\................. 10 [beta] = 0.1441 \e\........ 9 (2-21) 17 (5-41) 34 (10-79) 81 (24-180) 152 (46-312)
U.S.Granite workers...................... Log-linear \c\............. 15 [beta] = 0.19 \e\.......... 11 (4-18) 25 (9-42) 60 (19-111) 250 (59-502) 653 (167-760)
North American industrial sand workers... Log-linear \c\............. 15 [beta] = 0.13 (0.074) \f\.. 7 (0-16) 15 (0-37) 34 (0-93) 120 (0-425) 387 (0-750)
British coal miners...................... Log-linear \c\............. 15 [Bgr] = 0.0524 (0.0188).... 3 (1-5) 6 (2-11) 13 (4-23) 37 (9-75) 95 (20-224)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Risk to age 85 and based on 2006 background mortality rates for all males (see Appendix for life table method).
\b\ Model with log cumulative exposure (mg/m\3\-days + 1).
\c\ Model with cumulative exposure (mg/m\3\-years).
\d\ 95% confidence interval calculated as follows (where CE = cumulative exposure in mg/m\3\-years and SE is standard error of the parameter estimate):
For CE <= 2.19: 1 + [([beta]1 (1.96*SE1)) * CE].
For CE > 2.19: 1 + [([beta]1 * CE) + ([beta]2 * (CE-2.19))] 1.96 * SQRT[ (CE\2\ * SE1\2\) + ((CE-2.19)\2\* SE2\2\) + (2*CE*(CE-3.29)*-0.00429)].
\e\ Standard error not reported, upper and lower confidence limit on beta estimated from confidence interval of risk estimate reported in original article.
\f\ Standard error of the coefficient was estimated from the p-value for trend.
Table VI-2--Summary of Lifetime or Cumulative Risk Estimates for Crystalline Silica
----------------------------------------------------------------------------------------------------------------
Risk associated with 45 years of occupational exposure (per 1,000 workers)
-------------------------------------------------------------------------------
Health endpoint (source) Respirable crystalline silica exposure level (mg/m\3\)
-------------------------------------------------------------------------------
0.025 0.05 0.100 0.250 0.500
----------------------------------------------------------------------------------------------------------------
Lung Cancer Mortality (Lifetime
Risk):
Pooled Analysis, 9-23 18-26 22-29 27-34 36-38
Toxichemica, Inc (2004) \a\
\b\........................
Diatomaceous Earth Worker 9 17 34 81 152
study (Rice et al., 2001)
\a\ \c\....................
U.S. Granite Worker study 11 25 60 250 653
(Attfield and Costello,
2004) \a\ \d\..............
North American Industrial 7 15 34 120 387
Sand Worker study (Hughes
et al., 2001) \a\ \e\......
British Coal Miner study 3 6 13 37 95
(Miller and MacCalman,
2009) \a\ \f\..............
Silicosis and Non-Malignant Lung
Disease Mortality (Lifetime
Risk):
Pooled Analysis 4 7 11 17 22
(Toxichemica, Inc., 2004)
(silicosis) \g\............
Diatomaceous Earth Worker 22 43 83 188 321
study (Park et al., 2002)
(NMRD) \h\.................
Renal Disease Mortality
(Lifetime Risk):
Pooled Cohort study 25 32 39 52 63
(Steenland et al., 2002a)..
Silicosis Morbidity (Cumulative
Risk):
Chest x-ray category of 2/1 21 55 301 994 1000
or greater (Buchanan et
al., 2003) \j\.............
Silicosis mortality and/or x- 31 74 431 593 626
ray of 1/1 or greater
(Steenland and Brown,
1995b) \k\.................
Chest x-ray category of 1/1 6 127 773 995 1000
or greater (Hnizdo and
Sluis-Cremer, 1993) \l\....
Chest x-ray category of 1 or 40 170 590 1000 1000
greater (Chen et al., 2001)
\m\........................
Chest x-ray category of 1 or .............. .............. .............. .............. ..............
greater (Chen et al., 2005)
\n\
Tin miners.............. 40 100 400 950 1000
Tungsten miners......... 5 20 120 750 1000
Pottery workers......... 5 20 60 300 700
----------------------------------------------------------------------------------------------------------------
From Table II-12, "Respirable Crystalline Silica--Health Effects Literature Review and Preliminary Quantitative
Risk Assessment" (Docket OSHA-2010-0034).
Table VI-3--Exposure Distribution in Lung Cancer Studies
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Cum(exp) (mg/m\3\-y) Average* exposure (mg/m\3\) Mean respirable
No. of -------------------------------------------------------------------------------- crystalline
Primary exposure (as deaths silica exposure
Study n described in study) from lung median 25th median 75th over employment
cancer q\1\ (q\2\) q\3\ max (q\1\) (q\2\) (q\3\) max period (mg/
m[caret]3)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. diatomaceous earth workers \1\ 2,342 cristobalite............... 77 0.37 1.05 2.48 62.52 0.11 0.18 0.46 2.43 n/a
(Checkoway et al., 1997).
S. African gold miners \1\ (Hnizdo and 2,260 quartz and other silicates. 77 n/a 4.23 n/a n/a 0.15 0.19 0.22 0.31 n/a
Sluis-cremer, 1991 & Hnizdo et al.,
1997).
U.S. gold miners \1\ (Steenland and 3,328 silica dust................ 156 0.1 0.23 0.74 6.2 0.02 0.05 0.1 0.24 n/a
Brown, 1995a).
Australian gold miners \1\ (de Klerk and 2,297 silica dust................ 135 6.52 11.37 17.31 50.22 0.25 0.43 0.65 1.55 n/a
Musk, 1998).
U.S. granite workers (Costello and 5,414 silica dust from granite... 124 0.14 0.71 2.19 50 0.02 0.05 0.08 1.01 n/a
Graham, 1988).
Finnish granite workers (Koskela et al., 1,026 quartz dust................ 38 0.84 4.63 15.42 100.98 0.39 0.59 1.29 3.6 n/a
1994).
U.S. industrial sand workers \1\ 4,626 silica dust................ 85 0.03 0.13 5.2 8.265 0.02 0.04 0.06 0.4 n/a
(Steenland et al., 2001b).
North American industrial sand workers 90 crystalline silica......... 95 1.11 2.73 5.20 n/a 0.069 0.15 0.025 n/a n/a
\1\ (Hughes et al., 2001).
Ch. Tungsten (Chen et al., 1992)......... 28,442 silica dust................ 174 3.49 8.56 29.79 232.26 0.15 0.32 1.28 4.98 6.1
Ch. Pottery (Chen et al., 1992).......... 13,719 silica dust................ 81 3.89 6.07 9.44 63.15 0.18 0.22 0.34 2.1 11.4
Ch. Tin (Chen et al., 1992).............. 7,849 silica dust................ 119 2.79 5.27 5.29 83.09 0.12 0.19 0.49 1.95 7.7
British coal workers \1\ (Miller and 17,820 quartz..................... 973 n/a n/a n/a n/a n/a n/a n/a n/a n/a
MacCalman, 2009).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Study adjusted for effects smoking.
* Average exposure is cumulative exposure averaged over the entire exposure period.
n/a Data not available.
VII. Significance of Risk
A. Legal Requirements
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."
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.
The Agency's burden to establish significant risk derives from the
OSH Act, 29 U.S.C. 651 et seq. Section 3(8) of the Act requires that
workplace safety and health standards be "reasonably necessary and
appropriate to provide safe or healthful employment." 29 U.S.C.
652(8). The Supreme Court, in the "benzene" decision, stated that
section 3(8) "implies 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). Examining section 3(8) more closely, the Court
described OSHA's obligation to demonstrate significant risk:
"[S]afe" is not the equivalent of "risk-free." A workplace can
hardly be considered "unsafe" unless it threatens the workers with
a significant risk of harm. Therefore, before the Secretary can
promulgate any permanent health or safety standard, he must make a
threshold finding that the place of employment is unsafe in the
sense that significant risks are present and can be eliminated or
lessened by a change in practices.
Id. While clarifying OSHA's responsibilities, the Court emphasized
the Agency's discretion in determining what constitutes significant
risk, stating, "[the Agency's] determination that a particular level
of risk is `significant' will be based largely on policy
considerations." Benzene, 448 U.S. at 655, n. 62. The Court explained
that significant risk is not a "mathematical straitjacket," and
maintained that OSHA could meet its burden without "wait[ing] for
deaths to occur before taking any action." Benzene, 448 U.S. at 655.
Because section 6(b)(5) of the Act requires that the Agency base
its findings on the "best available evidence," 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. 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." Id. Furthermore, "the Agency is free to use
conservative assumptions in interpreting the data with respect to
carcinogens, risking error on the side of over protection rather than
under protection," so long as such assumptions are based in "a body
of reputable scientific thought." Id.
The Act also requires that the Agency make a finding that the toxic
material or harmful physical agent at issue causes material impairment
to workers' health. Section 6(b)(5) of the Act directs the Secretary of
Labor 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 . . .
for the period of his working life." 29 U.S.C. 655(b)(5). As with
significant risk, what constitutes material impairment in any given
case is a policy determination for 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--and that OSHA may act with a "pronounced bias towards worker
safety." Id; Bldg & Constr. Trades Dep't v. Brock, 838 F.2d 1258, 1266
(D.C. Cir. 1988).
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
judicial guidance, the language of the OSH Act, and Agency policy
considerations. Thus, using the best available 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.
In this case, OSHA has reviewed extensive toxicological,
epidemiological, and experimental research pertaining to adverse health
effects of occupational exposure to respirable crystalline silica,
including silicosis, other non-malignant respiratory disease, lung
cancer, and autoimmune and renal diseases. As a result of this review,
the Agency has developed preliminary quantitative estimates of the
excess risk of mortality and morbidity that is attributable to
currently allowable respirable crystalline silica exposure
concentrations. The Agency is proposing a new PEL of 0.05 mg/m\3\
because exposures at and above this level present a significant risk to
workers' health. Even though OSHA's preliminary risk assessment
indicates that a significant risk exists at the proposed action level
of 0.025 mg/m\3\, the Agency is not proposing a PEL below the proposed
0.05 mg/m\3\ limit because OSHA must also consider technological and
economic feasibility in determining exposure limits. As explained in
the Summary and Explanation for paragraph (c), Permissible Exposure
Limit (PEL), OSHA has preliminary determined that the proposed PEL of
0.05 mg/m\3\ is technologically and economically feasible, but that a
lower PEL of 0.025 mg/m\3\ is not technologically feasible. OSHA has
preliminarily determined that long-term exposure at the current PEL
presents a significant risk of material harm to workers' health, and
that adoption of the proposed PEL will substantially reduce this risk
to the extent feasible.
As discussed in Section V of this preamble (Health Effects
Summary), inhalation exposure to respirable crystalline silica
increases the risk of a variety of adverse health effects, including
silicosis, chronic obstructive pulmonary disease (COPD), lung cancer,
immunological effects, kidney disease, and infectious tuberculosis
(TB). OSHA considers each of these conditions to be a material
impairment of health. These diseases result in significant discomfort,
permanent functional limitations including permanent disability or
reduced ability to work, reduced quality of life, and decreased life
expectancy. When these diseases coexist, as is common, the effects are
particularly debilitating (Rice and Stayner, 1995; Rosenman et al.,
1999). Based on these findings and on the scientific evidence that
respirable crystalline silica substantially increases the risk of each
of these conditions, OSHA preliminarily concludes that workers who are
exposed to respirable crystalline silica at the current PEL are at
significant risk of material impairment of health or functional
capacity.
B. OSHA's Preliminary Findings
1. Material Impairments of Health
Section I of OSHA's Health Effects Literature Review and
Preliminary Quantitative Risk Assessment (available in Docket OSHA-
2010-0034) describes in detail the adverse health conditions that
workers who are exposed to respirable crystalline silica are at risk of
developing. The Agency's findings are summarized in Section V of this
preamble (Health Effects Summary). The adverse health effects discussed
include lung cancer, silicosis, other non-malignant respiratory disease
(NMRD), and immunological and renal effects.
a. Silicosis
Silicosis refers to a spectrum of lung diseases attributable to the
inhalation of respirable crystalline silica. As described in Section V
(Health Effects Summary), 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 exposed person
drowning in their own lung fluid (NIOSH, 1996). 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). Both acute and accelerated silicosis are
associated with exposures that are substantially above the current
general industry PEL, although precise information on the relationships
between exposure and occurrence of disease are not available.
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). 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 alveolar sacs and
the ends of the lung tissue. The scarring can be detected in chest x-
ray films when the lesions become large enough to appear as visible
opacities. The result is restriction of lung volumes and decreased
pulmonary compliance with concomitant reduced gas transfer (Balaan and
Banks, 1992). Chronic silicosis is characterized by small, rounded
opacities that are symmetrically distributed in the upper lung zones on
chest radiograph.
The diagnosis of silicosis is based on a history of exposure to
respirable crystalline silica, chest radiograph findings, and the
exclusion of other conditions, including tuberculosis (TB). 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, 2002, 2011) is the currently accepted
standard against which chest radiographs are evaluated in epidemiologic
studies, for medical surveillance, and for 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.
The small rounded opacities seen in early stage chronic silicosis
(i.e., 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, disability, and premature
death. In cases involving PMF, death is commonly attributable to
progressive respiratory insufficiency (Balaan and Banks, 1992).
The appearance of ILO category 2 or 3 background profusion of small
opacities has been shown to increase the risk of developing large
opacities characteristic of PMF. In one study of silicosis patients in
Hong Kong, Ng and Chan (1991) 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 median
survival times compared to the general population (Infante-Rivard et
al., 1991; Ng et al., 1992a; Westerholm, 1980).
Silicosis is the oldest known occupational lung disease and is
still today the cause of significant premature mortality. In 2005,
there were 161 deaths in the U.S. where silicosis was recorded as an
underlying or contributing cause of death on a death certificate
(NIOSH, 2008c). Between 1996 and 2005, deaths attributed to silicosis
resulted in an average of 11.6 years of life lost by affected workers
(NIOSH, 2007). In addition, exposure to respirable crystalline silica
remains an important cause of morbidity and hospitalizations. State-
based hospital discharge data show that in the year 2000, 1,128
silicosis-related hospitalizations occurred, indicating that silicosis
continues to be a significant health issue in the U.S. (CSTE, 2005).
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). 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), errors in recording
occupation on death certificates, or misdiagnosis of disease by health
care providers (Goodwin, 2003; Windau et al., 1991; Rosenman et al.,
2003). 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;
Craighead and Vallyathan, 1980; Rosenman et al., 1997).
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 (for example,
Hughes et al., 1982; Hessel et al., 1988; Miller et al., 1998; Ng et
al., 1987a; Yang et al., 2006). 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). Although there were periods of extremely high exposure to
respirable quartz in the mine (greater than 2 mg/m\3\ in some jobs
between 1972 and 1976, and more than 10 percent of exposures between
1969 and 1977 were greater than 1 mg/m\3\), the mean cumulative
exposure for the cohort over the period 1964-1978 was 1.8 mg/m\3\-
years, corresponding to an average silica concentration of 0.12 mg/
m\3\. In a population of granite quarry workers exposed to an average
respirable silica concentration of 0.48 mg/m\3\ (mean length of
employment was 23.4 years), 45 percent of those diagnosed with simple
silicosis showed radiological progression of disease after 2 to 10
years of follow up (Ng et al., 1987a). Among a population of gold
miners, 92 percent progressed in 14 years; exposures of high-, medium-,
and low-exposure groups were 0.97, 0.45, and 0.24 mg/m\3\, respectively
(Hessel et al., 1988). 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). These and other
studies discussed in the Health Effects section are of populations of
workers exposed to average concentrations of respirable crystalline
silica above those permitted by OSHA's current general industry PEL.
The studies, however, are of interest to OSHA because the Agency's
current enforcement data indicate that exposures in this range are
still common in some industry sectors. Furthermore, the Agency's
preliminary risk assessment is based on use of an exposure metric that
is less influenced by exposure pattern and, instead, characterizes the
accumulated exposure of workers over time. Further, the use of a
cumulative exposure metric reflects the progression of silica-related
diseases: While it is not known that silicosis is a precursor to lung
cancer, continued exposure to respirable crystalline silica among
workers with silicosis has been shown to be associated with malignant
respiratory disease (Chen et al., 1992). The Chinese pottery workers
study offers an example of silicosis-associated lung cancer among
workers in the clay industry, reflecting the variety of health outcomes
associated with diverse silica exposures across industrial settings.
The risk of silicosis, and particularly its progression, carries
with it an increased risk of reduced lung function. 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 1998; Hughes et al., 1982; Malmberg et al., 1993; Ng and Chan,
1992). The rates of decline in lung function are greater in those whose
disease showed evidence of radiologic progression (B[eacute]gin et al.,
1987a; Cowie 1998; Ng and Chan, 1992; Ng et al., 1987a). Additionally,
the average deterioration of lung function exceeds that in smokers
(Hughes et al., 1982).
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; Begin et al., 1988; Moore et al., 1988). A study by Cowie
(1998), however, found a statistically significantly greater annual
loss in FVC and FEV1 among those with category 1 profusion
compared to category 0. In another study, Cowie and Mabena (1991) found
that the degree of profusion of opacities was associated with
reductions in several pulmonary function metrics. Still, other studies
have reported no associations between radiographic silicosis and
decreases in pulmonary function (Ng et al., 1987a; Wiles et al., 1992;
Hnizdo, 1992), with some studies (Ng et al., 1987a; Wang et al., 1997)
finding that measurable changes in pulmonary function are evident well
before the changes seen on chest x-ray. This may reflect the general
insensitivity of chest radiography in detecting lung fibrosis, and/or
may reflect that exposure to respirable silica has also been shown to
increase the risk of chronic obstructive pulmonary disease (COPD) (see
Section V, Health Effects Summary).
Finally, silicosis, and exposure to respirable crystalline silica
in and of itself, 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). More recent findings demonstrate that exposure to silica, even
without silicosis, increases the risk of infectious (i.e., active)
pulmonary TB (Sherson et al., 1990; Cowie, 1994; Hnizdo and Murray,
1998; WaterNaude et al., 2006). Both conditions together can hasten the
development of respiratory impairment and increase mortality risk even
beyond that experienced by unexposed persons with active TB (Banks,
2005).
Based on the information presented above and in its review of the
health literature, OSHA preliminarily concludes that silicosis remains
a significant cause of early mortality and of serious morbidity,
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
preliminarily finds that silicosis of any form, and at any stage, is a
material impairment of health and that fibrotic scarring of the lungs
represents loss of functional respiratory capacity.
b. Lung Cancer
OSHA considers lung cancer, an irreversible and usually fatal
disease, to be a clear material impairment of health. According to the
National Cancer Institute (Horner et al., 2009), 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. OSHA's preliminary finding that
respirable crystalline silica exposure substantially increases the risk
of lung cancer mortality 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 (IARC, 1997), the National
Toxicology Program (NTP, 2000), the National Institute for Occupational
Safety and Health (NIOSH, 2002), the American Thoracic Society (1997),
and the American Conference of Governmental Industrial Hygienists
(ACGIH, 2001). 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. Studies key
to OSHA's risk assessment are outlined in Table VII-1, which summarizes
exposure characterization and related lung cancer risk across several
different industries. 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) and in two
community-based studies (Pukkala et al., 2005; Cassidy et al., 2007),
as well as in a pooled analysis of 10 occupational cohort studies
(Steenland et al., 2001a).
Table VII-1-- Summary of Key Lung Cancer Studies
--------------------------------------------------------------------------------------------------------------------------------------------------------
Type of study and
Industry sector/population description of Exposure No. of lung cancer Risk ratios (95% Additional Source
population characterization deaths/cases CI) information
--------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. Diatomaceous earth workers Cohort study. Same Assessment based on 77................ SMR 129 (CI 101- Smoking history Checkoway et al.,
as Checkoway et almost 6,400 161) based on available for 1997.
al., 1993, samples taken from national rates, half cohort.
excluding 317 1948-1988; about and SMR 144 (CI Under worst-case
workers whose 57 percent of 114-180) based on assumptions, the
exposures could samples local rates. Risk risk ratio for
not be represented ratios by the high-exposure
characterized, particle counts, exposure quintile group would be
and including 89 17 percent were were 1.00, 0.96, reduced to 1.67
workers with personal 0.77, 1.26, and after accounting
asbestos exposure respirable dust 2.15, with the for smoking.
who were samples. JEM latter being
previously included 135 jobs stat. sig. RR=
excluded from the over 4 time 2.15 and 1.67.
1993 study. periods (Seixas et
Follow up through al., 1997).
1994.
South African gold miners...... Cohort study. Particle count data 77................ RR 1.023 (CI 1.005- Model adjusted for Hnizdo and Sluis-
N=2,209 white from Beadle (1971). 1.042) per 1,000 smoking and year Cremer, 1991.
male miners particle-years of of birth. Lung
employed between exposure based on cancer was
1936 and 1943. Cox proportional associated with
Followed from hazards model. silicosis of the
1968-1986. hilar glands not
silicosis of lung
or pleura.
Possible
confounding by
radon exposure
among miners with
20 or more years
experience.
South African gold miners...... Nested case- Particle count data 78................ RR 2.45 (CI 1.2- Lung cancer Hnizdo et al.,
control study converted to 5.2) when mortality 1997.
from population respirable dust silicosis was associated with
study by Hnizdo mass (Beadle and included in model. smoking,
and Sluis- Bradley, 1970, and cumulative dust
Cremer,1991. N=78 Page-Shipp and exposure, and
cases, 386 Harris, 1972). duration of
controls. underground work.
Latter two
factors were most
significantly
associated with
lung cancer with
exposure lagged
20 years.
US gold miners................. Cohort and nested Particle count 115............... SMR 113 (CI 94- Smoking data Steenland and
case-control data, conversion 136) overall. available for Brown, 1995a,
study, same to mass SMRs increased part of cohort, 1995b
population as concentration for workers with habits comparable
Brown et al. based on Vt. 30 or more years to general US
(1986); workers Granite study, of latency, and population;
with at least 1 construction of when local cancer attributable
year underground JEM. Median quartz rates used as smoking-related
work between 1940 exposures were referents. Case- cancer risk
and 1965. Follow 0.15, 0.07, and control study estimated to be
up through 1990. 0.02 mg/m\3\ prior showed no 1.07.
to 1930, from 1930- relationship of
1950, and after risk to
1950 respectively. cumulative
exposure to dust.
Australian gold miners......... Cohort and nested Expert ranking of Nested case SMR 126 (CI 107- Association de Klerk and Musk,
case-control dustiness by job. control of 138 159) lower bound; between exposure 1998
study. N=2,297, lung cancer SMR 149 (CI 126- and lung cancer
follow up of deaths. 176) upper bound. mortality not
Armstrong et al. From case- stat. sig. after
(1979). Follow up control, RR 1.31 adjusting for
through 1993. (CI 1.10-1.7) per smoking,
unit exposure bronchitis, and
score. silicosis.
Authors concluded
lung cancer
restricted to
miners who
received
compensation for
silicosis..
U.S. (Vermont) granite shed and Cohort study. Exposure data not 53 deaths among SMR 129 for pre- Dust controls Costello and
quarry workers -. N=5,414 employed used in analysis. those hired 1930 hires (not employed between Graham, 1988.
at least 1 year before 1930; 43 stat. sig.); SMR 1938 and 1940
between 1950 and deaths among 95 for post-1940 with continuing
1982. those hired after hires (not stat. improvement
1940. sig). SMR 181 afterwards.
(stat. sig) for
shed workers
hired before 1930
and with long
tenure and
latency.
Finnish granite workers........ Cohort and nested Personal sampling 31 through 1989... Through 1989, SMR Smoking habits Koskela et al.,
case-control data collected 140 (CI 98-193). similar to other 1987, 1990, 1994.
studies. N=1,026, from 1970-1972 For workers in Finnish
follow up from included total and two regions where occupational
1972-1981, respirable dust silica content of groups. Minimal
extended to 1985 and respirable rock was highest, work-related
(Koskella et al., silica sampling. SMRs were 126 (CI exposures to
1990) and 1989 Average silica 71-208) and 211 other carcinogens.
(Koskella et al., concentrations (CI 120-342),
1994). ranged form 0.3- respectively.
4.9 mg/m\3\.
North American industrial sand Case-control study Assessment based on 95 cases, two OR 1.00, 0.84, Adjusted for Hughes et al.,
workers. from McDonald et 14,249 respirable controls per case. 2.02 and 2.07 for smoking. Positive 2001.
al. (2001) cohort. dust and silica increasing association
samples taken from quartiles of between silica
1974 to 1998. exposure p for exposure and lung
Exposures prior to trend=0.04). cancer. Median
this based on exposure for
particle count cases and
data. Adjustments controls were
made for 0.148 and 0.110
respirator use mg/m\3\
(Rando et al., respirable
2001). silica,
respectively.
U.S. industrial sand workers... Cohort and nested Exposure assessment 109 deaths overall SMR 160 (CI 131- Smoking data from Steenland and
case-control based on 4,269 193) overall. 358 workers Sanderson, 2001.
study. N=4,626 compliance dust Positive trends suggested that
workers. Follow samples taken from seen with smoking could not
up from 1960-1996. 1974-1996 and cumulative silica explain the
analyzed for exposure (p=0.04 observed increase
respirable quartz. for unlagged, in lung cancer
Exposures prior to p=0.08 for mortality rates.
1974 based on lagged).
particle count
data and quartz
analysis of
settled dust and
dust collected by
high-volume air
samplers, and use
of a conversion
factor (1
mppcf=0.1 mg/m\3\).
Chinese Tin, Tungsten, and Cohort study. Measurements for .................. SMRs 198 for tin Non-statistically Chen et al., 1992.
Copper miners. N=54,522 workers total dust, quartz workers (no CI significantly
employed 1 yr. or content, and reported but increased risk
more between 1972 particle size stat. sig.). No ratio for lung
and 1974. Follow taken from 1950's- stat. sig. cancer among
up through 1989. 1980's. Exposures increased SMR for silicotics. No
categorized as tungsten or increased
high, medium, low, copper miners. gradient in risk
or non-exposed. observed with
exposure.
Chinese Pottery workers........ Cohort study. Measurements of job- .................. SMR 58 (p<0.05) No reported Chen et al., 1992.
N=13,719 workers specific total overall. RR 1.63 increase in lung
employed in 1972- dust and quartz (CI 0.8-3.4) cancer with
1974. Follow up content of settled among silicotics increasing
through 1989. dust used to compared to non- exposure.
classify workers silicotics.
into one of four
total dust
exposure groups.
British Coal workers........... Cohort study. Quartz exposure 973............... Significant Adjusted for Miller et al,
N=17,820 miners assessed from relationship smoking. 2007; Miller and
from 10 personal between MacCalman, 2009
collieries.. respirable dust cumulative silica
samples. exposure (lagged
15 years) and
lung cancer
mortality VIA Cox
regression.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Toxicity studies provide additional evidence of the carcinogenic
potential of crystalline silica (Health Effects Summary, Section V).
Acellular studies using DNA exposed directly to freshly fractured
crystalline silica demonstrate the direct effect silica has on DNA
breakage. Cell culture research has investigated the processes by which
crystalline silica disrupts normal gene expression and replication
(Section V). Studies demonstrate that chronic inflammatory and fibrotic
processes resulting in oxidative and cellular damage set up another
possible mechanism that leads to neoplastic changes in the lung
(Goldsmith, 1997; see also Health Effects discussion in Section V). In
addition, the biologically damaging physical characteristics of
crystalline silica, and the direct and indirect genotoxicity of
crystalline silica (Schins, 2002; Borm and Driscoll, 1996), support the
Agency's preliminary position that respirable crystalline silica should
be considered as an occupational carcinogen that causes lung cancer, a
clear material impairment of health.
c. Non-Malignant Respiratory Disease (Other Than Silicosis)
Exposure to respirable crystalline silica increases the risk of
developing chronic obstructive pulmonary disease (COPD), in particular
chronic bronchitis and emphysema. COPD results in loss of pulmonary
function that restricts normal activity in individuals afflicted with
these conditions (ATS, 2003). Both chronic bronchitis and emphysema can
occur in conjunction with development of silicosis. Several studies
have documented increased prevalence of chronic bronchitis and
emphysema among silica-exposed workers even absent evidence of
silicosis (see Section I of the Health Effects Literature Review and
Preliminary Quantitative Risk Assessment; NIOSH, 2002; ATS, 1997).
There is evidence that smoking may have an additive or synergistic
effect on silica-related COPD morbidity or mortality (Hnizdo, 1990;
Hnizdo et al., 1990; Wyndham et al., 1986; NIOSH, 2002). In a study of
diatomaceous earth workers, Park et al. (2002) found a positive
exposure-response relationship between exposure to respirable
cristobalite and increased mortality from non-malignant respiratory
disease.
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, 1974a, 1974b; Ng et
al., 1992b; Montes et al., 2004b), South African gold miners (Irwig and
Rocks, 1978; Hnizdo et al., 1990; Cowie and Mabena, 1991), gemstone
cutters (Ng et al., 1987b), concrete workers (Meijer et al., 2001),
refractory brick workers (Wang et al., 1997), hard rock miners
(Manfreda et al., 1982; Kreiss et al., 1989), pottery workers (Neukirch
et al., 1994), slate workers (Suhr et al., 2003), and potato sorters
(Jorna et al., 1994).
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 Vermont granite
workers exposed to an average of 60 [mu]g/m\3\, Graham did not find
exposure-related decrements in pulmonary function (Graham et al., 1981,
1994). However, Eisen et al.
(1995) 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 et al., 1993), in two
5-year studies of South African miners (Hnizdo, 1992; Cowie, 1998), and
in a study of foundry workers whose lung function was assessed between
1978 and 1992 (Hertzberg et al., 2002).
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), reported that the rate of decline in
FEV1 seen among the dropout subgroup of Vermont granite
workers was 4 ml per mg/m\3\-year 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., (2002) reported finding a 1.1 ml/year
decline in FEV1 and a 1.6 ml/year decline in FVC for each
mg/m\3\-year of respirable silica exposure after controlling for
ethnicity and smoking. From these rates of decline, they estimated that
exposure to the current OSHA quartz standard of 0.1 mg/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. (2002) 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. OSHA believes that this magnitude of reduced pulmonary
function, as well as the increased morbidity and mortality from non-
malignant respiratory disease that has been documented in the studies
summarized above, constitute material impairments of health and loss of
functional respiratory capacity.
d. Renal and Autoimmune Effects
OSHA's review of the literature summarized in Section V, Health
Effects Summary, reflects substantial evidence that exposure to
crystalline silica increases the risk of renal and autoimmune diseases.
Epidemiologic studies have found statistically significant associations
between occupational exposure to silica dust and chronic renal disease
(e.g., Calvert et al., 1997), subclinical renal changes including
proteinurea and elevated serum creatinine (e.g., Ng et al., 1992c;
Rosenman et al., 2000; Hotz et al., 1995), end-stage renal disease
morbidity (e.g., Steenland et al., 1990), chronic renal disease
mortality (Steenland et al., 2001b, 2002a), and Wegener's
granulomatosis (Nuyts et al., 1995), the latter of which represents
severe injury to the glomeruli that, if untreated, rapidly leads to
renal failure. Possible mechanisms suggested for silica-induced renal
disease include 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;
Gregorini et al., 1993). Steenland et al. (2002a) 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), rheumatoid arthritis (e.g. Klockars
et al., 1987; Rosenman and Zhu, 1995), and systemic lupus erythematosus
(e.g., Brown et al., 1997). 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 believes that chronic renal disease, end-stage renal
disease mortality, Wegener's granulomatosis, scleroderma, rheumatoid
arthritis, and systemic lupus erythematosus clearly represent material
impairments of health.
2. Significance of Risk
To evaluate the significance of the health risks that result from
exposure to hazardous chemical agents, OSHA relies on toxicological,
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
current standards and compliance with the new standard being proposed.
In the case of crystalline silica, the current general industry,
construction, and shipyard PELs are formulas that limit 8-hour TWA
exposures to respirable dust; the limit on exposure decreases with
increasing crystalline silica content of the dust. OSHA's current
general industry PEL for respirable quartz is expressed both in terms
of a particle count as well as a gravimetric concentration, while the
current construction and shipyard employment PELs for respirable quartz
are only expressed in terms of a particle count formula. For general
industry, the gravimetric formula PEL for quartz approaches 0.1 mg/m\3\
(100 [mu]g/m\3\) of respirable crystalline silica when the quartz
content of the dust is about 10 percent or greater. For the
construction and shipyard industries, the current PEL is a formula that
is based on concentration of respirable particles in the air; on a mass
concentration basis, it is believed by OSHA to lie within a range of
between about 0.25 mg/m\3\ (250 [mu]g/m\3\) to 0.5 mg/m\3\ (500 [mu]g/
m\3\) expressed as respirable quartz (see Section VI). In general
industry, the current PELs for cristobalite and tridymite are one-half
the PEL for quartz.
OSHA is proposing to revise the current PELs for general industry,
construction, and shipyards to 0.05 mg/m\3\ (50 [mu]g/m\3\) of
respirable crystalline silica. OSHA is also proposing an action level
of 0.025 mg/m\3\ (25 [mu]g/m\3\). In the Summary of the Preliminary
Quantitative Risk Assessment (Section VI of the preamble), OSHA
presents estimates of health risks associated with 45 years of exposure
to 0.025, 0.05, and 0.1 mg/m\3\ respirable crystalline silica to
represent the risks associated with exposure over a working lifetime to
the proposed action level, proposed PEL, and current general industry
PEL, respectively. OSHA also presents estimates associated with
exposure to 0.25 and 0.5 mg/m\3\ to represent a range of risks likely
to be associated with exposure to the current construction and shipyard
PELs. Risk estimates are presented for mortality due to lung cancer, silicosis and other non-
malignant lung disease, and end-stage renal disease, as well as
silicosis morbidity. The preliminary findings from this assessment are
summarized below.
a. Summary of Excess Risk Estimates for Excess Lung Cancer Mortality
For preliminary 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; Toxichemica, Inc., 2004) as well as on
individual studies of granite (Attfield and Costello, 2004),
diatomaceous earth (Rice et al., 2001), and industrial sand (Hughes et
al., 2001) worker cohorts, and a study of coal miners exposed to
respirable quartz (Miller et al., 2007; Miller and MacCalman, 2009).
OSHA believes these studies are suitable for use to quantitatively
characterize health risks to exposed workers because (1) study
populations were of sufficient size to provide adequate power to detect
low levels of risk, (2) sufficient quantitative exposure data were
available 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. Where investigators estimated
excess lung cancer risks associated with exposure to the current PEL or
NIOSH recommended exposure limit, OSHA provided these estimates in its
Preliminary Quantitative Risk Assessment. However, 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 constant 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) 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), U.S. diatomaceous earth workers
(Checkoway et al., 1997), Australian gold miners (deKlerk and Musk,
1998), Finnish granite workers (Koskela et al., 1994), South African
gold miners (Hnizdo et al., 1997), U.S. industrial sand employees
(Steenland et al., 2001b), Vermont granite workers (Costello and
Graham, 1988), and Chinese pottery workers, tin miners, and tungsten
miners (Chen et al., 1992). 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). Exposure measurement data
were available for all 10 cohorts and included measurements of particle
counts, total dust mass, respirable dust mass, and, for one cohort,
respirable quartz. Cohort-specific conversion factors were used to
estimate cumulative exposures to respirable crystalline silica. A case-
control analysis of silicosis mortality (Mannetje et al., 2002b) showed
a strong positive exposure-response trend, indicating that cumulative
exposure estimates for the cohorts were not subject to random
misclassification errors of such a magnitude so as to obscure observing
an exposure-response relationship between silica and silicosis despite
the variety of dust measurement metrics relied upon and the need to
make assumptions to convert the data to a single exposure metric (i.e.,
mass concentration of respirable crystalline silica). In effect, the
known relationship between exposure to respirable silica and silicosis
served as a positive control to assess the validity of exposure
estimates. Quantitative assessment of lung cancer risks were based on
use of a log-linear model (log RR = [beta]x, where x represents the
exposure variable and [beta] the coefficient to be estimated) with a
15-year exposure lag providing the best fit. Models based on
untransformed or log-transformed cumulative dose metrics provided an
acceptable fit to the pooled data, with the model using untransformed
cumulative dose providing a slightly better fit. However, there was
substantial heterogeneity among the exposure-response coefficients
derived from the individual cohorts when untransformed cumulative dose
was used, which could result in one or a few of the cohorts unduly
influencing the pooled exposure-response coefficient. For this reason,
the authors preferred the use of log-transformed cumulative exposure in
the model to derive the pooled coefficient since heterogeneity was
substantially reduced.
OSHA's implementation of this model is based on a re-analysis
conducted by Steenland and Bartow (Toxichemica, 2004), which corrected
small errors in the assignment of exposure estimates in the original
analysis. In addition, subsequent to the Toxichemica report, and in
response to suggestions made by external peer reviewers, Steenland and
Bartow conducted additional analyses based on use of a linear relative
risk model having the general form RR = 1 + [beta]x, as well as a
categorical analysis (personal communication, Steenland 2010). The
linear model was implemented with both untransformed and log-
transformed cumulative exposure metrics, and was also implemented as a
2-piece spline model.
The categorical analysis indicates that, for the pooled data set,
lung cancer relative risks increase steeply at low exposures, after
which the rate of increase in relative risk declines and the exposure-
response curve becomes flat (see Figure II-2 of the Preliminary
Quantitative Risk Assessment). Use of either the linear relative risk
or log-linear relative risk model with untransformed cumulative
exposure (with or without a 15-year lag) failed to capture this initial
steep slope, resulting in an underestimate of the relative risk
compared to that suggested by the categorical analysis. In contrast,
use of log-transformed cumulative exposure with the linear or log-
linear model, and use of the 2-piece linear spline model with
untransformed exposure, better reflected the initial rise and
subsequent leveling out of the exposure-response curve, with the spline
model fitting somewhat better than either the linear or log-linear
models (all models incorporated a 15-year exposure lag). Of the three
models that best reflect the shape of the underlying exposure-response
curve suggested by the categorical analysis, there is no clear
rationale to prefer one over the other. Use of log-transformed
cumulative exposure in either the linear or log-linear models has the
advantage of reducing heterogeneity among the 10 pooled studies,
lessening the likelihood that the pooled coefficient would be overtly
influenced by outliers; however, use of a log-transformed exposure
metric complicates comparing results with those from other risk
analyses considered by OSHA that are based on untransformed exposure
metrics. Since all three of these models yield comparable estimates of
risk the choice of model is not critical for the purpose of assessing
significance of the risk, and therefore OSHA believes that the risk
estimates derived from the pooled study are best represented as a range of estimates based on all three of
these models.
From these models, the estimated lung cancer risk associated with
45 years of exposure to 0.1 mg/m\3\ (about equal to the current general
industry PEL) is between 22 and 29 deaths per 1,000 workers. The
estimated risk associated with exposure to silica concentrations in the
range of 0.25 and 0.5 mg/m\3\ (about equal to the current construction
and shipyard PELs) is between 27 and 38 deaths per 1,000. At the
proposed PEL of 0.05 mg/m\3\, the estimated excess risk ranges from 18
to 26 deaths per 1,000, and, at the proposed action level of 0.025 mg/
m\3\, from 9 to 23 deaths per 1,000.
As previously discussed, the exposure-response coefficients derived
from each of the 10 cohorts exhibited significant heterogeneity; risk
estimates based on the coefficients derived from the individual studies
for untransformed cumulative exposure varied by almost two orders of
magnitude, with estimated risks associated with exposure over a working
lifetime to the current general industry PEL ranging from a low of 0.8
deaths per 1,000 (from the Chinese pottery worker study) to a high of
69 deaths per 1,000 (from the South African miner study). It is
possible that the differences seen in the slopes of the exposure-
response relationships reflect physical differences in the nature of
crystalline silica particles generated in these workplaces and/or the
presence of different substances on the crystal surfaces that could
mitigate or enhance their toxicity (see Section V, Health Effects
Summary). It may also be that exposure estimates for some cohorts were
subject to systematic misclassification errors resulting in under- or
over-estimation of exposures due to the use of assumptions and
conversion factors that were necessary to estimate mass respirable
crystalline silica concentrations from exposure samples analyzed as
particle counts or total and respirable dust mass. OSHA believes that,
given the wide range of risk estimates derived from these 10 studies,
use of log-transformed cumulative exposure or the 2-piece spline model
is a reasonable approach for deriving a single summary statistic that
represents the lung cancer risk across the range of workplaces and
exposure conditions represented by the studies. However, use of these
approaches results in a non-linear exposure-response and suggests that
the relative risk of silica-related lung cancer begins to attenuate at
cumulative exposures in the range of those represented by the current
PELs. Although such exposure-response relationships have been described
for some carcinogens (for example, from metabolic saturation or a
healthy worker survivor effect, see Staynor et al., 2003), OSHA is not
aware of any specific evidence that would suggest that such a result is
biologically plausible for silica, except perhaps the possibility that
lung cancer risks increase more slowly with increasing exposure because
of competing risks from other silica-related diseases. Attenuation of
the exposure-response can also result from misclassification of
exposure estimates for the more highly-exposed cohort members (Staynor
et al., 2003). OSHA's evaluation of individual cohort studies discussed
below indicates that, with the exception of the Vermont granite cohort,
attenuation of exposure-related lung cancer response has not been
directly observed.
In addition to the pooled cohort study, OSHA's Preliminary
Quantitative Risk Assessment presents risk estimates 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) and one on
Vermont granite workers (Attfield and Costello, 2004), were included in
the 10-cohort pooled study (Steenland et al., 2001a; Toxichemica,
2004). The other two were of British coal miners (Miller et al., 2007;
Miller and MacCalman, 2010) and North American industrial sand workers
(Hughes et al., 2001).
Rice et al. (2001) presents an exposure-response analysis of the
diatomaceous worker cohort studied by Checkoway et al. (1993, 1996,
1997), who found a significant relationship between exposure to
respirable cristobalite and increased lung cancer mortality. 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. The risk analysis relied on an extensive job-specific exposure
assessment developed by Sexias et al. (1997), which included use of
over 6,000 samples taken during the period 1948 through 1988. The mean
cumulative exposure for the cohort was 2.16 mg/m\3\-years for
respirable crystalline silica dust. Rice et al. (2001) evaluated
several model forms for the exposure-response analysis and found
exposure to respirable cristobalite to be a significant predictor of
lung cancer mortality with the best-fitting model being a linear
relative risk model (with a 15-year exposure lag). From this model, the
estimates of the excess risk of lung cancer mortality are 34, 17, and 9
deaths per 1,000 workers for 45-years of exposure to 0.1, 0.05, and
0.025 mg/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 81 and 152 deaths per 1,000 workers.
Somewhat higher risk estimates are derived from the analysis
presented by Attfield and Costello (2004) of Vermont granite workers.
This study involved a cohort of 5,414 male granite workers who were
employed in the Vermont granite industry between 1950 and 1982 and who
were followed through 1994. Workers' cumulative exposures were
estimated by Davis et al. (1983) based on historical exposure data
collected in six environmental surveys conducted between 1924 and 1977.
A categorical analysis showed an increasing trend of lung cancer risk
ratios with increasing exposure, and Poisson regression was used to
evaluate several exposure-response models with varying exposure lags
and use of either untransformed or log-transformed exposure metrics.
The best-fitting model was based on use of a 15-year lag, use of
untransformed cumulative exposure, and omission of the highest exposure
group. The investigators believed that the omission of the highest
exposure group was appropriate since: (1) The underlying exposure data
for the high-exposure group was weaker than for the others; (2) there
was a greater likelihood that competing causes of death and
misdiagnoses of causes of death attenuated the lung cancer death rate
in the highest exposure group; (3) all of the remaining groups
comprised 85 percent of the deaths in the cohort and showed a strong
linear increase in lung cancer mortality with increasing exposure; and
(4) the exposure-response relationship seen in the lower exposure
groups was more relevant given that the exposures of these groups were
within the range of current occupational standards. OSHA's use of the
exposure coefficient from this analysis in a log-linear relative risk
model yielded a risk estimate of 60 deaths per 1,000 workers for 45
years of exposure to the current general industry PEL of 0.1 mg/m\3\,
25 deaths per 1,000 for 45 years of exposure to the proposed PEL of
0.05 mg/m\3\, and 11 deaths per 1,000 for 45 years of exposure at the
proposed action level of 0.025 mg/m\3\. Estimated risks associated with
45 years of exposure at the current construction PEL range from 250 to
653 deaths per 1,000.
Hughes et al. (2001) conducted a nested case-control study of 95
lung cancer deaths from a cohort of 2,670
industrial sand workers in the U.S. and Canada studied by McDonald et
al. (2001). (This cohort overlaps with the cohort studied by Steenland
and Sanderson (2001), which was included in the 10-cohort pooled study
by Steenland et al., 2001a). Both categorical analyses and conditional
logistic regression were used to examine relationships with cumulative
exposure, log of cumulative exposure, and average exposure. Exposure
levels over time were estimated via a job-exposure matrix developed for
this study (Rando et al., 2001). The 50th percentile (median) exposure
level of cases and controls for lung cancer were 0.149 and 0.110 mg/
m\3\ respirable crystalline silica, respectively, slightly above the
current OSHA general industry standard. There did not appear to be
substantial misclassification of exposures, as evidenced by silicosis
mortality showing a positive exposure-response trend with cumulative
exposure and average exposure concentration. Statistically significant
positive exposure-response trends for lung cancer were found for both
cumulative exposure (lagged 15 years) and average exposure
concentration, but not for duration of employment, after controlling
for smoking. There was no indication of an interaction effect of
smoking and cumulative silica exposure. Hughes et al. (2001) reported
the exposure coefficients for both lagged and unlagged cumulative
exposure; there was no significant difference between the two (0.13 per
mg/m\3\-year for lagged vs. 0.14 per mg/m\3\-year for unlagged). Use of
the coefficient from Hughes et al. (2001) that incorporated a 15-year
lag generates estimated cancer risks of 34, 15, and 7 deaths per 1,000
for 45 years exposure to the current general industry PEL of 0.1, the
proposed PEL of 0.05 mg/m\3\, and the proposed action level of 0.025
mg/m\3\ respirable silica, respectively. For 45 years of exposure to
the construction PEL, estimated risks range from 120 to 387 deaths per
1,000 workers.
Miller and MacCalman (2010, also reported in Miller et al., 2007)
extended the follow-up of a previously published cohort mortality study
(Miller and Buchanan, 1997). The follow-up study included 17,800 miners
from 10 coal mines in the U.K. who were followed through the end of
2005; observation in the original study began in 1970. By 2005, there
were 516,431 person years of observation, an average of 29 years per
miner, with 10,698 deaths from all causes. Exposure estimates of cohort
members were not updated from the earlier study since the mines closed
in the 1980s; however, some of these men might have had additional
exposure at other mines or facilities. An analysis of cause-specific
mortality was performed using external controls; it demonstrated that
lung cancer mortality was statistically significantly elevated for coal
miners exposed to silica. An analysis using internal controls was
performed via Cox proportional hazards regression methods, which
allowed for each individual miner's measurements of age and smoking
status, as well as the individual's detailed dust and quartz time-
dependent exposure measurements. From the Cox regression, Miller and
MacCalman (2009) estimated that cumulative exposure of 5 g-h/m\3\
respirable quartz (incorporating a 15-year lag) was associated with a
relative risk of 1.14 for lung cancer. This cumulative exposure is
about equivalent to 45 years of exposure to 0.055 mg/m\3\ respirable
quartz, or a cumulative exposure of 2.25 mg/m\3\-yr, assuming 2,000
hours of exposure per year. OSHA applied this slope factor in a log-
relative risk model and estimated the lifetime lung cancer mortality
risk to be 13 per 1,000 for 45 years of exposure to 0.1 mg/m\3\
respirable crystalline silica. For the proposed PEL of 0.05 mg/m\3\ and
proposed action level of 0.025 mg/m\3\, the lifetime risks are
estimated to be 6 and 3 deaths per 1,000, respectively. The range of
risks estimated to result from 45 years of exposure to the current
construction and shipyard PELs is from 37 to 95 deaths per 1,000
workers.
The analysis from the Miller and MacCalman (2009) study yields risk
estimates that are lower than those obtained from the other cohort
studies described above. Possible explanations for this include: (1)
Unlike the studies on diatomaceous earth workers and granite workers,
the mortality analysis of the coal miners was adjusted for smoking; (2)
lung cancer risks might have been lower among the coal miners due to
high competing mortality risks observed in the cohort (mortality was
significantly increased for several diseases, including tuberculosis,
chronic bronchitis, and non-malignant respiratory disease); and (3) the
lower risk estimates derived from the coal miner study could reflect an
actual difference in the cancer potency of the quartz dust in the coal
mines compared to that present in the work environments studied
elsewhere. OSHA believes that the risk estimates derived from this
study are credible. In terms of design, the cohort was based on union
rolls with very good participation rates and good reporting. The study
group was the largest of any of the individual cohort studies reviewed
here (over 17,000 workers) and there was an average of nearly 30 years
of follow-up, with about 60 percent of the cohort having died by the
end of follow-up. Just as important were the high quality and detail of
the exposure measurements, both of total dust and quartz.
b. 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) of data from
six of the ten epidemiological studies in the Steenland et al. (2001a)
pooled analysis of lung cancer mortality. Cohorts included in the
silicosis study were U.S. diatomaceous earth workers (Checkoway et al.,
1997); Finnish granite workers (Koskela et al., 1994); U.S. granite
workers (Costello and Graham, 1988); U.S. industrial sand workers
(Steenland and Sanderson, 2001); U.S. gold miners (Steenland and Brown,
1995b); and Australian gold miners (deKlerk and Musk, 1998). These six
cohorts contained 18,634 subjects 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). Analysis
of exposure-response was performed in a categorical analysis where the
cohort was divided into cumulative exposure deciles and Poisson
regression was used to estimate silicosis rate ratios for each
category, adjusted for age, calendar period, and study. Exposure-
response was examined in more detail using a nested case-control design
and logistic regression. Although Mannetje et al. (2002b) estimated
silicosis risks at the current OSHA PEL from the Poisson regression, a
subsequent analysis based on the case-control design was conducted by
Steenland and Bartow (Toxichemica, 2004), which resulted in slightly
lower estimates of risk. Based on the Toxichemica analysis, OSHA
estimates that the lifetime risk (over 85 years) of silicosis mortality
associated with 45 years of exposure to the current general industry
PEL of 0.1 mg/m\3\ is 11 deaths per 1,000 workers. Exposure for 45
years to the proposed PEL of 0.05 mg/m\3\ and action level of 0.025 mg/
m\3\ results in an estimated 7 and 4 silicosis deaths per 1,000,
respectively. Lifetime risks associated with exposure at the current
construction and shipyard PELs range from 17 to 22 deaths per 1,000
workers.
To study non-malignant respiratory diseases, of which silicosis is
one, Park et al. (2002) analyzed the California
diatomaceous earth cohort data originally studied by Checkoway et al.
(1997), consisting of 2,570 diatomaceous earth workers employed for 12
months or more from 1942 to 1994. The authors quantified 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. Less than 25 percent of the LDOC deaths in the analysis were
coded as silicosis or other pneumoconiosis (15 of 67). As noted by Park
et al. (2002), it is likely that silicosis as a cause of death is often
misclassified as emphysema or chronic bronchitis. Exposure-response
relationships were explored using both Poisson regression models and
Cox's proportional hazards models fit to the same series of relative
rate exposure-response models that were evaluated by Rice et al. (2001)
for lung cancer (i.e., log-linear, log-square root, log-quadratic,
linear relative rate, a power function, and a shape function). Relative
or excess rates were modeled using internal controls and adjusting for
age, calendar time, ethnicity (Hispanic versus white), and time since
first entry into the cohort, or using age- and calendar time-adjusted
external standardization to U.S. population mortality rates. There were
no LDOC deaths recorded among workers having cumulative exposures above
32 mg/m\3\-years, causing the response to level off or decline in the
highest exposure range; possible explanations considered included
survivor selection, depletion of susceptible populations in high dust
areas, and/or a higher degree of misclassification of exposures in the
earlier years where exposure data were lacking and when exposures were
presumably the highest. Therefore, Park et al. (2002) performed
exposure-response analyses that restricted the dataset to observations
where cumulative exposures were below 10 mg/m\3\-years, a level more
than four times higher than that resulting from 45 years of exposure to
the current general industry PEL for cristobalite (which is about 0.05
mg/m\3\), as well as analyses using the full dataset. Among the models
based on the restricted dataset, the best-fitting model with a single
exposure term was the linear relative rate model using external
adjustment.
OSHA's estimates of the lifetime chronic lung disease mortality
risk based on this model are substantially higher than those that OSHA
derived from the Mannetje et al. (2002b) silicosis analysis. For the
current general industry PEL of 0.1 mg/m\3\, exposure for 45 years is
estimated to result in 83 deaths per 1,000 workers. At the proposed PEL
of 0.05 mg/m\3\ and action level of 0.025 mg/m\3\, OSHA estimates the
lifetime risk from 45 years of exposure to be 43 and 22 deaths per
1,000, respectively. The range of risks associated with exposure at the
construction and shipyard PELs over a working lifetime is from 188 to
321 deaths per 1,000 workers. It should be noted that the Mannetje
study (2002b) was not adjusted for smoking while the Park study (2002)
had data on smoking habits for about one-third of the workers who died
from LDOC and about half of the entire cohort. The Poisson regression
on which the risk model is based was partially stratified on smoking.
Furthermore, analyses without adjustment for smoking suggested to the
authors that smoking was acting as a negative confounder.
c. 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 crystalline silica
increases the risk of renal and autoimmune disease (see Section V,
Health Effects Summary). Studies have found statistically significant
associations between occupational exposure to silica dust and chronic
renal disease, sub-clinical renal changes, end-stage renal disease
morbidity, chronic renal disease mortality, and Wegener's
granulomatosis. A strong exposure-response association for renal
disease mortality and silica exposure has also been demonstrated.
OSHA's assessment of the renal disease risks that result from
exposure to respirable crystalline silica are based on an analysis of
pooled data from three cohort studies (Steenland et al., 2002a). The
combined cohort for the pooled analysis (Steenland et al., 2002a)
consisted of 13,382 workers and included industrial sand workers
(Steenland et al., 2001b), U.S. gold miners (Steenland and Brown,
1995a), and Vermont granite workers (Costello and Graham, 1998).
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 0.07 mg/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). Exposure-response analysis was also conducted as part of
a nested case-control study, which showed statistically significant
monotonic trends of increasing risk with increasing exposure again for
both multiple cause (p = 0.004 linear trend, 0.0002 log trend) and
underlying cause (p = 0.21 linear trend, 0.03 log trend) analysis. The
authors found that use of log-cumulative dose in a log relative risk
model fit the pooled data better than cumulative exposure, average
exposure, or lagged exposure. OSHA's estimates of renal disease
mortality risk, which are based on the log relative risk model with log
cumulative exposure, are 39 deaths per 1,000 for 45 years of exposure
at the current general industry PEL of 0.1 mg/m\3\, 32 deaths per 1,000
for exposure at the proposed PEL of 0.05 mg/m\3\, and 25 deaths per
1,000 at the proposed action level of 0.025 mg/m\3\. OSHA also
estimates that 45 years of exposure at the current construction and
shipyard PELs would result in a renal disease mortality risk ranging
from 52 to 63 deaths per 1,000 workers.
d. Summary of Risk Estimates for Silicosis Morbidity
OSHA's Preliminary Quantitative Risk Assessment reviewed several
cross-sectional studies designed to characterize relationships between
exposure to respirable crystalline silica and development of silicosis
as determined by chest radiography. Several of these studies could not
provide information on exposure or length of employment prior to
disease onset. Others did have access to sufficient historical medical
data to retrospectively determine time of disease onset but included
medical examination at follow up of primarily active workers with
little or no post-employment follow-up. Although OSHA presents
silicosis risk estimates that were reported by the investigators of
these studies, OSHA believes that such estimates are likely to
understate lifetime risk of developing radiological silicosis; in fact,
the risk estimates reported in these studies are generally lower than
those derived from studies that included retired workers in follow up
medical examinations.
Therefore, OSHA believes that the most useful studies for
characterizing lifetime risk of silicosis morbidity are retrospective
cohort studies that included a large proportion of retired workers in the cohort and that
were able to evaluate disease status over time, including post-
retirement. 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, 1993; Steenland and Brown, 1995b; Miller et al., 1998; Buchanan
et al., 2003; Chen et al., 2001; Chen et al., 2005). Study populations
included five mining cohorts and a Chinese pottery worker cohort.
Except for the Chinese studies (Chen et al., 2001; Chen et al., 2005),
chest radiographs were interpreted in accordance with the ILO system
described earlier in this section, and x-ray films were read by panels
of B-readers. In the Chinese studies, films were evaluated using a
Chinese system of classification that is analogous to the ILO system.
In addition, the Steenland and Brown (1995b) study of U.S. gold miners
included silicosis mortality as well as morbidity in its analysis.
OSHA's estimates of silicosis morbidity risks are based on implementing
the various exposure-response models reported by the investigators;
these are considered to be cumulative risk models in the sense that
they represent the risk observed in the cohort at the time of the last
medical evaluation and do not reflect all of the risk that may become
manifest over a lifetime. With the exception of a coal miner study
(Buchanan et al., 2003), risk estimates reflect 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 crystalline silica, the estimated
risk of developing lesions consistent with an ILO classification of
category 1 or greater is estimated to range from 120 to 773 cases per
1,000 workers exposed at the current general industry PEL of 0.1 mg/
m\3\ for 45 years. For 45 years of exposure to the proposed PEL of 0.05
mg/m\3\, the range in estimated risk is from 20 to 170 cases per 1,000
workers. The risk predicted from exposure to the proposed action level
of 0.025 mg/m\3\ ranges from 5 to 40 cases per 1,000. From the coal
miner study of Buchanan et al. (2003), the estimated risks of acquiring
an abnormal chest x-ray classified as ILO category 2 or higher are 301,
55, and 21 cases per 1,000 workers exposed for 45 years to 0.1, 0.05,
and 0.025 mg/m\3\, respectively. These estimates are within the range
of risks obtained from the other mining studies. At exposures at or
above 0.25 mg/m\3\ for 45 years (equivalent to the current construction
and shipyard PELs), the risk of acquiring an abnormal chest x-ray
approaches unity. Risk estimates based on the pottery cohort are 60,
20, and 5 cases per 1,000 workers exposed for 45 years to 0.1, 0.05,
and 0.025 mg/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
alumino-silicates on the particle surfaces. According to Chen et al.
(2005), 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. 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; Hessel, 2006; Miller and Soutar, 2007) as
well as a lower silicosis risk per unit of cumulative exposure (Love et
al., 1999; Miller and Soutar, 2007).
3. Significance of Risk and Risk Reduction
The Supreme Court's benzene decision of 1980, discussed above in
this section, states that "before he can promulgate any permanent
health or safety standard, the Secretary [of Labor] is required to make
a threshold finding that a place of employment is unsafe--in the sense
that significant risks are present and can be eliminated or lessened by
a change in practices." Benzene, 448 U.S. at 642. While making it
clear that it is up to the Agency to determine what constitutes a
significant risk, the Court offered general guidance on the level of
risk OSHA might determine to be significant.
It is the Agency's responsibility to determine in the first
instance what it considers to be a "significant" risk. Some risks
are plainly acceptable and others are plainly unacceptable. If, for
example, 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 and take appropriate steps to decrease
or eliminate it.
Benzene, 448 U.S. at 655. The Court further stated that the
determination of significant risk is not a mathematical straitjacket
and that "the Agency has no duty to calculate the exact probability of
harm." Id.
In this section, OSHA presents its preliminary 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.
a. Mortality Risks
OSHA's Preliminary Quantitative Risk Assessment (and the Summary of
the Preliminary Quantitative Risk Assessment in section VI) presents
risk estimates for four causes of excess mortality: Lung cancer,
silicosis, non-malignant respiratory disease (including silicosis and
COPD), and renal disease. Table VII-2 presents the estimated excess
lifetime risks (i.e., to age 85) of these fatal diseases associated
with various levels of crystalline silica exposure allowed under the
current rule, based on OSHA's risk assessment and assuming 45 years of
occupational exposure to crystalline silica.
Table VII-2--Expected Excess Deaths per 1,000 Workers
----------------------------------------------------------------------------------------------------------------
Current
Current general construction/
Fatal health outcome industry PEL shipyard PEL Proposed PEL
(0.1 mg/m\3\) (0.25-0.5 mg/ (0.05 mg/m\3\)
m\3\)
----------------------------------------------------------------------------------------------------------------
Lung Cancer:
10-cohort pooled analysis............................. 22-29 27-38 18-26
Single cohort study-lowest estimate................... 13 37-95 6
Single cohort study-highest estimate.................. 60 250-653 25
Silicosis................................................. 11 17-22 7
Non-Malignant Respiratory Disease (including silicosis)... 83 188-321 43
Renal Disease............................................. 39 52-63 32
----------------------------------------------------------------------------------------------------------------
The purpose of the OSH Act, as stated in Section 6(b), is to ensure
"that no employee will suffer material impairment of health or
functional capacity even if such employee has regular exposure to the
hazard . . . for the period of his working life." 29 U.S.C. 655(b)(5).
Assuming a 45-year working life, as OSHA has done in significant risk
determinations for previous standards, the Agency preliminarily finds
that the excess risk of disease mortality related to exposure to
respirable crystalline silica at levels permitted by current 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 might consider unacceptable. Benzene, 448 U.S. at
655. For lung cancer, OSHA estimates the range of risk at the current
general industry PEL to be between 13 and 60 deaths per 1,000 workers.
The estimated risk for silicosis mortality is lower, at 11 deaths per
1,000 workers; however, the estimated lifetime risk for non-malignant
respiratory disease mortality, including silicosis, is about 8-fold
higher than that for silicosis alone, at 83 deaths per 1,000. OSHA
believes that the estimate for non-malignant respiratory disease
mortality 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 COPD,
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 current
limits for construction and shipyards result in even higher risk
estimates, as presented in Table VII-2.
To further demonstrate significant risk, OSHA compares the risk
from currently permissible crystalline silica exposures to risks found
across a broad variety of occupations. The Agency has used similar
occupational risk comparisons in the significant risk determination for
substance-specific standards promulgated since the benzene decision.
This approach is supported by 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: "In determining the priority for establishing
standards under this section, 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).
Fatal injury rates for most U.S. industries and occupations may be
obtained from data collected by the Bureau of Labor Statistics. Table
VII-3 shows annual fatality rates per 1,000 employees for several
industries for 2007, as well as projected fatalities per 1,000
employees assuming exposure to workplace hazards for 45 years based on
these annual rates (BLS, 2010). While it is difficult to meaningfully
compare aggregate industry fatality rates to the risks estimated in the
quantitative risk assessment for 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 6-60 excess lung cancer deaths per
1,000 workers from regular occupational exposure to respirable
crystalline silica in the range of 0.05--0.1 mg/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 VII-3). Regular exposures at higher levels, including the
current construction and shipyard PELs for respirable crystalline
silica, are expected to cause substantially more deaths per 1,000
workers from lung cancer (ranging from 37 to 653 per 1,000) than result
from occupational injuries in most private industry. At the proposed
PEL of 0.05 mg/m\3\ respirable crystalline silica, the Agency's
estimate of excess lung cancer mortality, from 6 to 26 deaths per 1,000
workers, is still 3- to10-fold or more 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.
Table VII-3--Fatal Injuries per 1000 Employees, by Industry or Sector
------------------------------------------------------------------------
Over 1 year Over 45 years
------------------------------------------------------------------------
All Private Industry.................... 0.043 1.9
Mining (General)........................ 0.214 9.6
Construction............................ 0.108 4.8
Manufacturing........................... 0.024 1.1
Wholesale Trade......................... 0.045 2.0
Transportation and Warehousing.......... 0.165 7.4
Financial Activities.................... 0.012 0.5
Educational and Health Services......... 0.008 0.4
------------------------------------------------------------------------
Source: BLS (2010).
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 crystalline silica,
were based on animal or human data of reasonable or high quality and
used the best information then available. Table VII-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. These risks were
judged by the Agency to be significant.
Table VII-4--Selected OSHA Risk Estimates for Prior and Current PELs
[Excess Cancers per 1000 workers]
----------------------------------------------------------------------------------------------------------------
Standard Risk at prior PEL Risk at current PEL Federal Register date
----------------------------------------------------------------------------------------------------------------
Ethylene Oxide................... 63-109 per 1000..... 1.2-2.3 per 1000.... June 22, 1984.
Asbestos......................... 64 per 1000......... 6.7 per 1000........ June 20, 1986.
Benzene.......................... 95 per 1000......... 10 per 1000......... September 11, 1987.
Formaldehyde..................... 0.4-6.2 per 1000.... 0.0056 per 1000..... December 4, 1987.
Methylenedianiline............... *6-30 per 1000...... 0.8 per 1000........ August 10, 1992.
Cadmium.......................... 58-157 per 1000..... 3-15 per 1000....... September 14, 1992.
1,3-Butadiene.................... 11.2-59.4 per 1000.. 1.3-8.1 per 1000.... November 4, 1996.
Methylene Chloride............... 126 per 1000........ 3.6 per 1000........ January 10, 1997.
Chromium VI...................... 101-351 per 1000.... 10-45 per 1000...... February 28, 2006
Crystalline Silica:
General Industry PEL......... **13-60 per 1000.... ***6-26 per 1000.... N/A
Construction/Shipyard PEL.... **27-653 per 1000... ***6-26 per 1000.... .................................
----------------------------------------------------------------------------------------------------------------
* no prior standard; reported risk is based on estimated exposures at the time of the rulemaking
** estimated excess lung cancer risks at the current PEL
*** estimated excess lung cancer risks at the proposed new PEL
The estimated excess lung cancer risks associated with respirable
crystalline silica at the current general industry PEL, 13-60 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 VII-
4, "Selected OSHA Risk Estimates for Prior and Current PELs"). The
estimated excess lung cancer risks associated with exposure to the
current construction and shipyard PELs are even higher. The estimated
risk from lifetime occupational exposure to respirable crystalline
silica at the proposed PEL is 6-26 excess lung cancer deaths per 1,000
workers, a range still higher than the risks from exposure to many
other carcinogens regulated by OSHA (see Table VII-4, "Selected OSHA
Risk Estimates for Prior and Current PELs").
OSHA's preliminary risk assessment also shows that reduction of the
current PELs to the proposed level of 0.05 mg/m\3\ will result in
substantial reduction in risk, although quantification of that
reduction is subject to model uncertainty. 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; also Toxichemica,
2004; Steenland 2010) suggests risk will be reduced by about 14 percent
from the current general industry PEL and by 28-41 percent from the
current 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;
Attfield and Costello, 2004; Hughes et al., 2001; Miller and MacCalman,
2009), which used linear or log-linear relative risk models with
untransformed cumulative exposure as the dose metric. These single
cohort studies suggest that reducing the current PELs to the proposed
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 current general industry and construction/shipyard PELs,
respectively. Non-malignant respiratory disease mortality risks will be
reduced by 48 percent and by 77-87 percent from reducing the general
industry and construction/shipyard PELs, respectively, to the proposed
PEL. There is also a substantial reduction in renal disease mortality
risks; an 18-percent reduction associated with reducing the general
industry PEL and a 38- to 49-percent reduction associated with reducing
the construction/shipyard PEL.
Thus, OSHA believes that the proposed PEL of 0.05 mg/m\3\
respirable crystalline silica will substantially reduce the risk of
material health impairments associated with exposure to silica.
However, even at the proposed PEL, as well as the action level of 0.025
mg/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.
b. Silicosis Morbidity Risks
OSHA's Preliminary Risk Assessment characterizes the risk of
developing lung fibrosis as detected by chest x-ray. For 45 years of
exposure at the current general industry PEL, 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 construction and shipyard PELs, the risk
approaches unity. 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 believes that each of these risk
estimates clearly represent a significant risk of developing fibrotic
lesions in the lung. Exposure to the proposed PEL of 0.05 mg/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 promulgation of the proposed PEL would result in a reduction in
risk by about two-thirds or more, which the Agency believes 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). 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; Begin et al., 1998; Moore et al., 1988; Ng
et al., 1992a; Infante-Rivard et al., 1991). From this study, OSHA
estimates that the risk associated with 45 years of exposure to the
current general industry PEL is 301 cases per 1,000 workers, again a
clearly significant risk. Exposure to the proposed PEL of 0.05 mg/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+ degree of small opacity profusion.
As is the case for other health effects addressed in the
preliminary risk assessment (i.e., lung cancer, silicosis morbidity
defined as ILO 1+ level of profusion), there is some evidence that this
risk will vary according to the nature of quartz particles present in
different workplaces. In particular, risk may vary depending on whether
quartz is freshly fractured during work operations and the co-existence
of other minerals and substances that could alter the biological
activity of quartz. Using medical and exposure data taken from a cohort
of heavy clay workers first studied by Love et al. (1999), Miller and
Soutar (2007) compared the silicosis prevalence within the cohort to
that predicted by the exposure-response model derived by Buchanan et
al. (2003) and used by OSHA to estimate the risk of radiologic
silicosis with a classification of ILO 2+. They found that the model
predicted about a 4-fold higher prevalence of workers having an
abnormal x-ray than was actually seen in the clay cohort (31 cases
predicted vs. 8 observed). Unlike the coal miner study, the clay worker
cohort included only active workers and not retirees (Love et al.,
1999); however, Miller and Soutar believed this could not explain the
magnitude of the difference between the model prediction and observed
silicosis prevalence in the clay worker cohort. OSHA believes that the
result obtained by Miller and Soutar (2007) likely does reflect
differences in the toxic potency of quartz particles in different work
settings. Nevertheless, even if the risk estimates predicted by the
model derived from the coal worker study were reduced substantially,
even by more than a factor of 10, the resulting risk estimate would
still reflect the presence of a significant risk.
The Preliminary Quantitative Risk Assessment also discusses the
question of a threshold exposure level for silicosis. There is little
quantitative data available with which to estimate a threshold exposure
level for silicosis or any of the other silica-related diseases
addressed in the risk assessment. The risk assessment discussed one
study that perhaps provides the best information. This is an analysis
by Kuempel et al. (2001) who used a rat-based toxicokinetic/
toxicodynamic model along with a human lung deposition/clearance model
to estimate a minimum lung burden necessary to cause the initial
inflammatory events that can lead to lung fibrosis and an indirect
genotoxic cause of lung cancer. They estimated that the threshold
effect level of lung burden associated with this inflammation
(Mcrit) is the equivalent of exposure to 0.036 mg/m\3\ for
45 years; thus, exposures below this level would presumably not lead to
an excess lung cancer risk (based on an indirect genotoxic mechanism)
nor to silicosis, at least in the "average individual." This might
suggest that exposures to a concentration of silica at the proposed
action level would not be associated with a risk of silicosis, and
possibly not of lung cancer. However, OSHA does not believe that the
analysis by Kuemple et al. is definitive with respect to a threshold
for silica-related disease. First, since the critical quartz burden is
a mean value derived from the model, the authors estimated that a 45-
year exposure to a concentration as low as 0.005 mg/m\3\, or 5 times
below the proposed action level, would result in a lung quartz burden
that was equal to the 95-percent lower confidence limit on
Mcrit. Due to the statistical uncertainty in Kuemple et
al.'s estimate of critical lung burden, OSHA cannot rule out the
existence of a threshold lung burden that is below that resulting from
exposure to the proposed action level. In addition, with respect to
silica-related lung cancer, if at least some of the risk is from a
direct genotoxic mechanism (see section II.F of the Health Effects
Literature Review), then this threshold value is not relevant to the
risk of lung cancer. Supporting evidence comes from Steenland and
Deddens (2002), who found that, for the 10-cohort pooled data set, a
risk model that incorporated a threshold did fit better than a no-
threshold model, but the estimated threshold was very low, 0.010 mg/
m\3\ (10 [mu]g/m\3\). OSHA acknowledges that a threshold exposure level
might lie within the range of the proposed action level, as suggested
by the work of Kuempel et al. (2001) and that this possibility adds
uncertainty to the estimated risks associated with exposure to the
action level. However, OSHA believes that available information cannot
firmly establish a threshold exposure level for silica-related effects,
and there is no empirical evidence that a threshold exists at or above
the proposed PEL of 0.05 mg/m\3\ for respirable crystalline silica.
VIII. Summary of the Preliminary Economic Analysis and Initial
Regulatory Flexibility Analysis
A. Introduction and Summary
OSHA's Preliminary Economic Analysis and Initial Regulatory
Flexibility Analysis (PEA) addresses issues related to the costs,
benefits, technological and economic feasibility, and the economic
impacts (including impacts on small entities) of this proposed
respirable crystalline silica rule and evaluates regulatory
alternatives to the proposed 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 PEA 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 PEA is to:
Identify the establishments and industries potentially
affected by the proposed rule;
Estimate current exposures and the technologically
feasible methods of controlling these exposures;
Estimate the benefits resulting from employers coming into
compliance with the proposed 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 proposed rule;
Assess the economic feasibility of the proposed rule for
affected industries; and
Assess the impact of the proposed rule on small entities
through an Initial Regulatory Flexibility Analysis (IRFA), to include
an evaluation of significant regulatory alternatives to the proposed
rule that OSHA has considered.
The Preliminary Economic Analysis contains the following chapters:
Chapter I. Introduction
Chapter II. Assessing the Need for Regulation
Chapter III. Profile of Affected Industries
Chapter IV. Technological Feasibility
Chapter V. Costs of Compliance
Chapter VI. Economic Impacts
Chapter VII. Benefits and Net Benefits
Chapter VIII. Regulatory Alternatives
Chapter IX. Initial Regulatory Flexibility Analysis
Chapter X. Environmental Impacts
Key findings of these chapters are summarized below and in sections
VIII.B through VIII.I of this PEA summary.
Profile of Affected Industries
The proposed rule would affect employers and employees in many
different industries across the economy. As described in Section VIII.C
and reported in Table VIII-3 of this preamble, OSHA estimates that a
total of 2.1 million employees in 550,000 establishments and 533,000
firms (entities) are potentially at risk from exposure to respirable
crystalline silica. This total includes 1.8 million employees in
477,000 establishments and 486,000 firms in the construction industry
and 295,000 employees in 56,000 establishments and 47,000 firms in
general industry and maritime.
Technological Feasibility
As described in more detail in Section VIII.D of this preamble and
in Chapter IV of the PEA, OSHA assessed, for all affected sectors, the
current exposures and the technological feasibility of the proposed PEL
of 50 [micro]g/m\3\ and, for analytic purposes, an alternative PEL of
25 [micro]g/m\3\.
Tables VIII-6 and VIII-7 in section VIII.D of this preamble
summarize all the industry sectors and construction activities studied
in the technological feasibility analysis and show how many operations
within each can achieve levels of 50 [mu]g/m\3\ through the
implementation of engineering and work practice controls. The table
also summarizes the overall feasibility finding for each industry
sector or construction activity based on the number of feasible versus
infeasible operations. For the general industry sector, OSHA has
preliminarily concluded that the proposed PEL of 50 [mu]g/m\3\ is
technologically feasible for all affected industries. For the
construction activities, OSHA has determined that the proposed PEL of
50 [mu]g/m\3\ is feasible in 10 out of 12 of the affected activities.
Thus, OSHA preliminarily concludes that engineering and work practices
will be sufficient to reduce and maintain silica exposures to the
proposed PEL of 50 [mu]g/m\3\ or below in most operations most of the
time in the affected industries. For those few operations within an
industry or activity where the proposed PEL is not technologically
feasible even when workers use recommended engineering and work
practice controls (seven out of 108 operations, see Tables VIII-6 and
VIII-7), employers can supplement controls with respirators to achieve
exposure levels at or below the proposed PEL.
Based on the information presented in the technological feasibility
analysis, the Agency believes that 50 [mu]g/m\3\ is the lowest feasible
PEL. An alternative PEL of 25 [mu]g/m\3\ would not be feasible because
the engineering and work practice controls identified to date will not
be sufficient to consistently reduce exposures to levels below 25
[mu]g/m\3\ in most operations most of the time. OSHA believes that an
alternative PEL of 25 [mu]g/m\3\ would not be feasible for many
industries, and that the use of respiratory protection would be
necessary in most operations most of the time to achieve compliance.
Additionally, the current methods of sampling analysis create higher
errors and lower precision in measurement as concentrations of silica
lower than the proposed PEL are analyzed. However, the Agency
preliminarily concludes that these sampling and analytical methods are
adequate to permit employers to comply with all applicable requirements
triggered by the proposed action level and PEL.
Costs of Compliance
As described in more detail in Section VIII.E and reported by
industry in Table VIII-8 of this preamble, the total annualized cost of
compliance with the proposed standard is estimated to be about $658
million. The major cost elements associated with the revisions to the
standard are costs for engineering controls, including controls for
abrasive blasting ($344 million); medical surveillance ($79 million);
exposure monitoring ($74 million); respiratory protection ($91
million); training ($50 million) and regulated areas or access control
($19 million). Of the total cost, $511 million would be borne by firms
in the construction industry and $147 million would be borne by firms
in general industry and maritime.
The compliance costs are expressed as annualized costs in order to
evaluate economic impacts against annual revenue and annual profits, to
be able to compare the economic impact of the rulemaking with other
OSHA regulatory actions, and to be able to add and track Federal
regulatory compliance costs and economic impacts in a consistent
manner. Annualized costs also represent a better measure for assessing
the longer-term potential impacts of the rulemaking. The annualized
costs were calculated by annualizing the one-time costs over a period
of 10 years and applying discount rates of 7 and 3 percent as
appropriate.
The estimated costs for the proposed silica standard rule include
the additional costs necessary for employers to achieve full
compliance. They do not include costs associated with current
compliance that has already been achieved with regard to the new
requirements or costs necessary to achieve compliance with existing
silica requirements, to the extent that some employers may currently
not be fully complying with applicable regulatory requirements.
OSHA's exposure profile represents the Agency's best estimate of
current exposures (i.e., baseline exposures). OSHA did not attempt to
determine the extent to which current exposures in compliance with the
current silica PELs are the result of baseline engineering controls or
the result of circumstances leading to low exposures. This information
is not needed to estimate the costs of (additional) engineering
controls needed to comply with the proposed standard.
Because of the severe health hazards involved, the Agency expects
that the estimated 15,446 abrasive blasters in the construction sector
and the estimated 4,550 abrasive blasters in the maritime sector are
currently wearing respirators in compliance with OSHA's abrasive
blasting provisions. Furthermore, for the construction baseline, an
estimated 241,269 workers, including abrasive blasters, will need to
use respirators to achieve compliance with the proposed
rule, and, based on the NIOSH/BLS respirator use survey (NIOSH/BLS,
2003), an estimated 56 percent of construction employers currently
require such respiratory use and have respirator programs that meet
OSHA's respirator standard. OSHA has not taken any costs for employers
and their workers currently in compliance with the respiratory
provisions in the proposed rule.
In addition, under both the general industry and construction
baselines, an estimated 50 percent of employers have pre-existing
training programs that address silica-related risks (as required under
OSHA's hazard communication standard) and partially satisfy the
proposed rule's training requirements (for costing purposes, estimated
to satisfy 50 percent of the training requirements in the proposed
rule). These employers will need fewer resources to achieve full
compliance with the proposed rule than those employers without pre-
existing training programs that address silica-related risks.
Other than respiratory protection and worker training concerning
silica-related risks, OSHA did not assume baseline compliance with any
ancillary provisions, even though some employers have reported that
they do currently monitor silica exposure and some employers have
reported conducting medical surveillance.
Economic Impacts
To assess the nature and magnitude of the economic impacts
associated with compliance with the proposed rule, OSHA developed
quantitative estimates of the potential economic impact of the new
requirements on entities in each of the affected industry sectors. The
estimated compliance costs were compared with industry revenues and
profits to provide an assessment of the economic feasibility of
complying with the revised standard and an evaluation of the potential
economic impacts.
As described in greater detail in Section VIII.F of this preamble,
the costs of compliance with the proposed rulemaking are not large in
relation to the corresponding annual financial flows associated with
each of the affected industry sectors. The estimated annualized costs
of compliance represent about 0.02 percent of annual revenues and about
0.5 percent of annual profits, on average, across all firms in general
industry and maritime, and about 0.05 percent of annual revenues and
about 1.0 percent of annual profits, on average, across all firms in
construction. Compliance costs do not represent more than 0.39 percent
of revenues or more than 8.8 percent of profits in any affected
industry in general industry or maritime, or more than 0.13 percent of
revenues or more than 3 percent of profits in any affected industry in
construction.
Based on its analysis of international trade effects, OSHA
concluded that most or all costs arising from this proposed silica rule
would be passed on in higher prices rather than absorbed in lost
profits and that any price increases would result in minimal loss of
business to foreign competition.
Given the minimal potential impact on prices or profits in the
affected industries, OSHA has preliminarily concluded that compliance
with the requirements of the proposed rulemaking would be economically
feasible in every affected industry sector.
In addition, OSHA directed Inforum--a not-for-profit corporation
with over 40 years of experience in the design and application of
macroeconomic models--to run its LIFT (Long-term Interindustry
Forecasting Tool) model of the U.S. economy to estimate the industry
and aggregate employment effects of the proposed silica rule. Inforum
developed estimates of the employment impacts over the ten-year period
from 2014-2023 by feeding OSHA's year-by-year and industry-by-industry
estimates of the compliance costs of the proposed rule into its LIFT
model. The most important Inforum result is that the proposed silica
rule would have a negligible--albeit slightly positive--net effect on
aggregate U.S. employment.
Based on its analysis of the costs and economic impacts associated
with this rulemaking and on Inforum's estimates of associated
employment and other macroeconomic impacts, OSHA preliminarily
concludes that the effect of the proposed standard on employment,
wages, and economic growth for the United States would be negligible.
Benefits, Net Benefits, and Cost-Effectiveness
As described in more detail in Section VIII.G of this preamble,
OSHA estimated the benefits, net benefits, and incremental benefits of
the proposed silica rule. That section also contains a sensitivity
analysis to show how robust the estimates of net benefits are to
changes in various cost and benefit parameters. A full explanation of
the derivation of the estimates presented there is provided in Chapter
VII of the PEA for the proposed rule. OSHA invites comments on any
aspect of its estimation of the benefits and net benefits of the
proposed rule.
OSHA estimated the benefits associated with the proposed PEL of 50
[mu]g/m\3\ and, for analytical purposes to comply with OMB Circular A-
4, with an alternative PEL of 100 [mu]g/m\3\ for respirable crystalline
silica by applying the dose-response relationship developed in the
Agency's quantitative risk assessment--summarized in Section VI of this
preamble--to current exposure levels. OSHA determined current exposure
levels by first developing an exposure profile (presented in Chapter IV
of the PEA) 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 summarized in Table VIII-5
in Section VIII.C of this preamble.
By applying the dose-response relationship to estimates of current
exposure levels across industries, it is possible to project the number
of cases of the following diseases expected to occur in the worker
population given current exposure levels (the "baseline"):
Fatal cases of lung cancer,
fatal cases of non-malignant respiratory disease
(including silicosis),
fatal cases of end-stage renal disease, and
cases of silicosis morbidity.
Table VIII-1 provides a summary of OSHA's best estimate of the
costs and benefits of the proposed rule using a discount rate of 3
percent. As shown, the proposed rule is estimated to prevent 688
fatalities and 1,585 silica-related illnesses annually once it is fully
effective, and the estimated cost of the rule is $637 million annually.
Also as shown in Table VIII-1, the discounted monetized benefits of the
proposed rule are estimated to be $5.3 billion annually, and the
proposed rule is estimated to generate net benefits of $4.6 billion
annually. Table VIII-1 also presents the estimated costs and benefits
of the proposed rule using a discount rate of 7 percent. The estimated
costs and benefits of the proposed rule, disaggregated by industry
sector, were previously presented in Table SI-3 in this preamble.
Table VIII-1--Annualized Benefits, Costs and Net Benefits of OSHA's Proposed Silica Standard of 50 [mu]g/m\3\
----------------------------------------------------------------------------------------------------------------
Discount rate 3% 7%
----------------------------------------------------------------------------------------------------------------
Annualized Costs
Engineering Controls (includes Abrasive Blasting)..... $329,994,068 $343,818,700
Respirators........................................... 90,573,449 90,918,741
Exposure Assessment................................... 72,504,999 74,421,757
Medical Surveillance.................................. 76,233,932 79,069,527
Training.............................................. 48,779,433 50,266,744
Regulated Area or Access Control...................... 19,243,500 19,396,743
-----------------------------------------------------
Total Annualized Costs (point estimate)........... 637,329,380 657,892,211
Annual Benefits: Number of Cases Prevented
Fatal Lung Cancers (midpoint estimate)................ 162
Fatal Silicosis & other Non-Malignant Respiratory 375
Diseases.............................................
Fatal Renal Disease................................... 151
------------------
Silica-Related Mortality.............................. 688 3,203,485,869 2,101,980,475
Silicosis Morbidity................................... 1,585 1,986,214,921 1,363,727,104
-----------------------------------
Monetized Annual Benefits (midpoint estimate)..... 5,189,700,790 3,465,707,579
Net Benefits...................................... 4,552,371,410 2,807,815,368
----------------------------------------------------------------------------------------------------------------
Initial Regulatory Flexibility Analysis
OSHA has prepared an Initial Regulatory Flexibility Analysis (IRFA)
in accordance with the requirements of the Regulatory Flexibility Act,
as amended in 1996. Among the contents of the IRFA are an analysis of
the potential impact of the proposed rule on small entities and a
description and discussion of significant alternatives to the proposed
rule that OSHA has considered. The IRFA is presented in its entirety
both in Chapter IX of the PEA and in Section VIII.I of this preamble.
The remainder of this section (Section VIII) of the preamble is
organized as follows:
B. The Need for Regulation
C. Profile of Affected Industry
D. Technological Feasibility
E. Costs of Compliance
F. Economic Feasibility Analysis and Regulatory Flexibility
Determination
G. Benefits and Net Benefits
H. Regulatory Alternatives
I. Initial Regulatory Flexibility Analysis.
B. Need for Regulation
Employees in work environments addressed by the proposed 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 PEA
in support of the proposed rule, the risks to employees are excessively
large due to the existence of various types of market failure, and
existing and alternative methods of overcoming these negative
consequences--such as workers' compensation systems, tort liability
options, and information dissemination programs--have been shown to
provide insufficient worker protection.
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 proposed 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
1. Introduction
Chapter III of the PEA presents profile data for industries
potentially affected by the proposed 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 at-
risk workers, and the average revenue for affected entities and
establishments. \3\ 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 proposed 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.
---------------------------------------------------------------------------
\3\ An establishment is a single physical location at which
business is conducted or services or industrial operations are
performed. An entity is an aggregation of all establishments owned
by a parent company within an industry with some annual payroll.
---------------------------------------------------------------------------
The methodological basis for the industry and at-risk worker data
presented here comes from ERG (2007a, 2007b, 2008a, and 2008b). The
actual data presented here comes from the technological feasibility
analyses presented in Chapter IV of the PEA and from ERG (2013), which
updated ERG's earlier spreadsheets to reflect the most recent industry
data available. The technological feasibility analyses identified the
job categories with potential worker exposure to silica. ERG (2007a,
2007b) matched the BLS Occupational Employment Survey (OES)
occupational titles in NAICS industries with the at-risk job categories
and then calculated the percentages of production employment
represented by each at-risk job title.\4\ These percentages were then
used to project the number of employees in the at-risk job categories
by NAICS industry. OSHA welcomes additional information and data that
might help improve the accuracy and usefulness of the industry profile
presented here and in Chapter III of the PEA.
---------------------------------------------------------------------------
\4\ Production employment includes workers in building and
grounds maintenance; forestry, fishing, and farming; installation
and maintenance; construction; production; and material handling
occupations.
---------------------------------------------------------------------------
2. Selection of NAICS Industries for Analysis
The technological feasibility analyses presented in Chapter IV of
the PEA identify the general industry and maritime sectors and the
construction activities potentially affected by the proposed silica
standard.
a. 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 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 challenged to limit
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. 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 25 industry subsectors in the overall general industry and
maritime sectors that OSHA identified as being potentially affected by
the proposed silica standard are as follows:
Asphalt Paving Products
Asphalt Roofing Materials
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 of the PEA, and captive foundries,\5\ 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 of the PEA.
---------------------------------------------------------------------------
\5\ Captive foundries include establishments in other industries
with foundry processes incidental to the primary products
manufactured. ERG (2008b) 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.
---------------------------------------------------------------------------
As described in ERG (2008b), OSHA identified the six-digit NAICS
codes for these subsectors to develop a list of industries potentially
affected by the proposed silica standard. Table VIII-2 presents the
sectors listed above with their corresponding six-digit NAICS
industries.
BILLING CODE 4510-26-P
[GRAPHIC] [TIFF OMITTED] TP12SE13.004
[GRAPHIC] [TIFF OMITTED] TP12SE13.005
BILLING CODE 4510-26-C
b. Construction
The construction sector is an integral part of the nation's
economy, accounting for almost 6 percent of total 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 12 construction activities, by job category, that OSHA
identified as being potentially affected by the proposed silica
standard are as follows:
Abrasive Blasters
Drywall Finishers
Heavy Equipment Operators
Hole Drillers Using Hand-Held Drills
Jackhammer and Impact Drillers
Masonry Cutters Using Portable Saws
Masonry Cutters Using Stationary Saws
Millers Using Portable or Mobile Machines
Rock and Concrete Drillers
Rock-Crushing Machine Operators and Tenders
Tuckpointers and Grinders
Underground Construction Workers
As shown in ERG (2008a) and in Chapter IV of the PEA, these
construction activities occur in the following construction industries,
accompanied by their four-digit NAICS codes: \6\ \7\
---------------------------------------------------------------------------
\6\ 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 and
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.
\7\ In addition, 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.
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
Characteristics of Affected Industries
Table VIII-3 provides an overview of the industries and estimated
number of workers affected by the proposed rule. Included in Table
VIII-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 VIII-3 identify each industry in
which workers are routinely exposed to respirable crystalline silica
(preceded by the industry's NAICS code) and the total number of
entities, establishments, and employees for that industry. Note that
not all entities, establishments, and employees in these affected
industries necessarily engage in activities involving silica exposure.
The next three columns in Table VIII-3 show, for each affected
industry, OSHA's estimate of the number of affected entities,
establishments, and workers--that is, the number of entities and
establishments in which workers are actually exposed to silica and the
total number of workers exposed to silica. Based on ERG (2007a, 2007b),
OSHA's methodology focused on estimation of the number of affected
workers. 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.\8\
---------------------------------------------------------------------------
\8\ 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.
Table VIII-3--Characteristics of Industries Affected by OSHA's Proposed Standard for Silica--All Entities
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total Total affected Total FTE
NAICS Industry Total entities establish- Total Total affected establishments Total affected affected Total revenues Revenues per Revenues per
\a\ ments \a\ employment \a\ entities \b\ \b\ employment \b\ employees \b\ ($1,000) \c\ entity establishment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Construction
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
236100....... Residential 197,600 198,912 966,198 54,973 55,338 55,338 27,669 $374,724,410 $1,896,379 $1,883,870
Building
Construction.
236200....... Nonresidential 43,634 44,702 741,978 43,634 44,702 173,939 34,788 313,592,140 7,186,876 7,015,170
Building
Construction.
237100....... Utility System 20,236 21,232 496,628 20,236 21,232 217,070 96,181 98,129,343 4,849,246 4,621,766
Construction.
237200....... Land Subdivision 12,383 12,469 77,406 6,466 6,511 6,511 3,255 24,449,519 1,974,442 1,960,824
237300....... Highway, Street, 11,081 11,860 325,182 11,081 11,860 204,899 66,916 96,655,241 8,722,610 8,149,683
and Bridge
Construction.
237900....... Other Heavy and 5,326 5,561 90,167 5,326 5,561 46,813 18,835 19,456,230 3,653,066 3,498,693
Civil
Engineering
Construction.
238100....... Foundation, 116,836 117,456 1,167,986 116,836 117,456 559,729 111,946 157,513,197 1,348,156 1,341,040
Structure, and
Building
Exterior
Contractors.
238200....... Building 179,051 182,368 1,940,281 19,988 20,358 20,358 10,179 267,537,377 1,494,196 1,467,019
Equipment
Contractors.
238300....... Building 132,219 133,343 975,335 119,000 120,012 120,012 60,006 112,005,298 847,120 839,979
Finishing
Contractors.
238900....... Other Specialty 73,922 74,446 557,638 73,922 74,446 274,439 137,219 84,184,953 1,138,835 1,130,819
Trade
Contractors.
999000....... State and local 14,397 N/A 5,762,939 14,397 NA 170,068 85,034 N/A N/A N/A
governments \d\.
----------------------------------------------------------------------------------------------------------------------------------------------------------------
Subtotals--Co 806,685 802,349 13,101,738 485,859 477,476 1,849,175 652,029 1,548,247,709 1,954,148 1,929,644
nstruction.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
General Industry and Maritime
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121....... Asphalt paving 480 1,431 14,471 480 1,431 5,043 .............. 8,909,030 18,560,480 6,225,737
mixture and
block
manufacturing.
324122....... Asphalt shingle 121 224 12,631 121 224 4,395 .............. 7,168,591 59,244,556 32,002,640
and roofing
materials.
325510....... Paint and 1,093 1,344 46,209 1,093 1,344 3,285 .............. 24,113,682 22,061,923 17,941,728
coating
manufacturing
\e\.
327111....... Vitreous china 31 41 5,854 31 41 2,802 .............. 818,725 26,410,479 19,968,899
plumbing
fixtures &
bathroom
accessories
manufacturing.
327112....... Vitreous china, 728 731 9,178 728 731 4,394 .............. 827,296 1,136,395 1,131,731
fine
earthenware, &
other pottery
product
manufacturing.
327113....... Porcelain 110 125 6,168 110 125 2,953 .............. 951,475 8,649,776 7,611,802
electrical
supply mfg.
327121....... Brick and 104 204 13,509 104 204 5,132 .............. 2,195,641 21,111,931 10,762,945
structural clay
mfg.
327122....... Ceramic wall and 180 193 7,094 180 193 2,695 .............. 1,217,597 6,764,429 6,308,794
floor tile mfg.
327123....... Other structural 45 49 1,603 45 49 609 .............. 227,406 5,053,461 4,640,933
clay product
mfg.
327124....... Clay refractory 108 129 4,475 108 129 1,646 .............. 955,377 8,846,082 7,406,022
manufacturing.
327125....... Nonclay 81 105 5,640 81 105 2,075 .............. 1,453,869 17,948,999 13,846,371
refractory
manufacturing.
327211....... Flat glass 56 83 11,003 56 83 271 .............. 3,421,674 61,101,328 41,224,993
manufacturing.
327212....... Other pressed 457 499 20,625 457 499 1,034 .............. 3,395,635 7,430,274 6,804,880
and blown glass
and glassware
manufacturing.
327213....... Glass container 32 72 14,392 32 72 722 .............. 4,365,673 136,427,289 60,634,351
manufacturing.
327320....... Ready-mixed 2,470 6,064 107,190 2,470 6,064 43,920 .............. 27,904,708 11,297,453 4,601,700
concrete
manufacturing.
327331....... Concrete block 599 951 22,738 599 951 10,962 .............. 5,127,518 8,560,131 5,391,712
and brick mfg.
327332....... Concrete pipe 194 385 14,077 194 385 6,787 .............. 2,861,038 14,747,620 7,431,268
mfg.
327390....... Other concrete 1,934 2,281 66,095 1,934 2,281 31,865 .............. 10,336,178 5,344,456 4,531,424
product mfg.
327991....... Cut stone and 1,885 1,943 30,633 1,885 1,943 12,085 .............. 3,507,209 1,860,588 1,805,048
stone product
manufacturing.
327992....... Ground or 171 271 6,629 171 271 5,051 .............. 2,205,910 12,900,061 8,139,891
treated mineral
and earth
manufacturing.
327993....... Mineral wool 195 321 19,241 195 321 1,090 .............. 5,734,226 29,406,287 17,863,633
manufacturing.
327999....... All other misc. 350 465 10,028 350 465 4,835 .............. 2,538,560 7,253,028 5,459,268
nonmetallic
mineral product
mfg.
331111....... Iron and steel 686 805 108,592 523 614 614 .............. 53,496,748 77,983,597 66,455,587
mills.
331112....... Electrometallurg 22 22 2,198 12 12 12 .............. 1,027,769 46,716,774 46,716,774
ical ferroalloy
product
manufacturing.
331210....... Iron and steel 186 240 21,543 94 122 122 .............. 7,014,894 37,714,484 29,228,725
pipe and tube
manufacturing
from purchased
steel.
331221....... Rolled steel 150 170 10,857 54 61 61 .............. 4,494,254 29,961,696 26,436,790
shape
manufacturing.
331222....... Steel wire 232 288 14,669 67 83 83 .............. 3,496,143 15,069,584 12,139,387
drawing.
331314....... Secondary 119 150 7,381 33 42 42 .............. 4,139,263 34,783,724 27,595,088
smelting and
alloying of
aluminum.
331423....... Secondary 29 31 1,278 7 7 7 .............. 765,196 26,386,082 24,683,755
smelting,
refining, and
alloying of
copper.
331492....... Secondary 195 217 9,383 48 53 53 .............. 3,012,985 15,451,203 13,884,721
smelting,
refining, and
alloying of
nonferrous
metal (except
cu & al).
331511....... Iron foundries.. 457 527 59,209 457 527 22,111 .............. 9,753,093 21,341,560 18,506,818
331512....... Steel investment 115 132 16,429 115 132 5,934 .............. 2,290,472 19,917,147 17,352,060
foundries.
331513....... Steel foundries 208 222 17,722 208 222 6,618 .............. 3,640,441 17,502,121 16,398,383
(except
investment).
331524....... Aluminum 441 466 26,565 441 466 9,633 .............. 3,614,233 8,195,541 7,755,866
foundries
(except die-
casting).
331525....... Copper foundries 251 256 6,120 251 256 2,219 .............. 747,437 2,977,835 2,919,674
(except die-
casting).
331528....... Other nonferrous 119 124 4,710 119 124 1,708 .............. 821,327 6,901,910 6,623,607
foundries
(except die-
casting).
332111....... Iron and steel 358 398 26,596 135 150 150 .............. 5,702,872 15,929,811 14,328,825
forging.
332112....... Nonferrous 67 77 8,814 43 50 50 .............. 2,080,000 31,044,783 27,012,993
forging.
332115....... Crown and 50 59 3,243 15 18 18 .............. 905,206 18,104,119 15,342,473
closure
manufacturing.
332116....... Metal stamping.. 1,556 1,641 64,724 347 366 366 .............. 10,418,233 6,695,523 6,348,710
332117....... Powder 111 129 8,362 41 47 47 .............. 1,178,698 10,618,900 9,137,193
metallurgy part
manufacturing.
332211....... Cutlery and 138 141 5,779 32 33 33 .............. 1,198,675 8,686,049 8,501,240
flatware
(except
precious)
manufacturing.
332212....... Hand and edge 1,056 1,155 36,622 189 207 207 .............. 6,382,593 6,044,123 5,526,055
tool
manufacturing.
332213....... Saw blade and 127 136 7,304 39 41 41 .............. 1,450,781 11,423,474 10,667,509
handsaw
manufacturing.
332214....... Kitchen utensil, 64 70 3,928 20 22 22 .............. 1,226,230 19,159,850 17,517,577
pot, and pan
manufacturing.
332323....... Ornamental and 2,408 2,450 39,947 53 54 54 .............. 6,402,565 2,658,873 2,613,292
architectural
metal work.
332439....... Other metal 364 401 15,195 78 86 86 .............. 2,817,120 7,739,340 7,025,236
container
manufacturing.
332510....... Hardware 734 828 45,282 227 256 256 .............. 9,268,800 12,627,793 11,194,203
manufacturing.
332611....... Spring (heavy 109 113 4,059 22 23 23 .............. 825,444 7,572,882 7,304,815
gauge)
manufacturing.
332612....... Spring (light 270 340 15,336 69 87 87 .............. 2,618,283 9,697,344 7,700,832
gauge)
manufacturing.
332618....... Other fabricated 1,103 1,198 36,364 189 205 205 .............. 5,770,701 5,231,823 4,816,946
wire product
manufacturing.
332710....... Machine shops... 21,135 21,356 266,597 1,490 1,506 1,506 .............. 32,643,382 1,544,518 1,528,534
332812....... Metal coating 2,363 2,599 56,978 2,363 2,599 4,695 .............. 11,010,624 4,659,595 4,236,485
and allied
services.
332911....... Industrial valve 394 488 38,330 175 216 216 .............. 8,446,768 21,438,497 17,308,951
manufacturing.
332912....... Fluid power 306 381 35,519 161 201 201 .............. 8,044,008 26,287,608 21,112,882
valve and hose
fitting
manufacturing.
332913....... Plumbing fixture 126 144 11,513 57 65 65 .............. 3,276,413 26,003,281 22,752,871
fitting and
trim
manufacturing.
332919....... Other metal 240 268 18,112 91 102 102 .............. 3,787,626 15,781,773 14,132,931
valve and pipe
fitting
manufacturing.
332991....... Ball and roller 107 180 27,197 91 154 154 .............. 6,198,871 57,933,374 34,438,172
bearing
manufacturing.
332996....... Fabricated pipe 711 765 27,201 143 154 154 .............. 4,879,023 6,862,198 6,377,808
and pipe
fitting
manufacturing.
332997....... Industrial 459 461 5,281 30 30 30 .............. 486,947 1,060,887 1,056,285
pattern
manufacturing.
332998....... Enameled iron 72 76 5,655 72 76 96 .............. 1,036,508 14,395,940 13,638,259
and metal
sanitary ware
manufacturing.
332999....... All other 3,043 3,123 72,201 397 408 408 .............. 12,944,345 4,253,811 4,144,843
miscellaneous
fabricated
metal product
manufacturing.
333319....... Other commercial 1,253 1,349 53,012 278 299 299 .............. 12,744,730 10,171,373 9,447,539
and service
industry
machinery
manufacturing.
333411....... Air purification 303 351 14,883 72 84 84 .............. 2,428,159 8,013,727 6,917,833
equipment
manufacturing.
333412....... Industrial and 142 163 10,506 52 59 59 .............. 1,962,040 13,817,181 12,037,053
commercial fan
and blower
manufacturing.
333414....... Heating 377 407 20,577 108 116 116 .............. 4,266,536 11,317,071 10,482,888
equipment
(except warm
air furnaces)
manufacturing.
333511....... Industrial mold 2,084 2,126 39,917 221 226 226 .............. 4,963,915 2,381,917 2,334,861
manufacturing.
333512....... Machine tool 514 530 17,220 94 97 97 .............. 3,675,264 7,150,320 6,934,461
(metal cutting
types)
manufacturing.
333513....... Machine tool 274 285 8,556 46 48 48 .............. 1,398,993 5,105,812 4,908,746
(metal forming
types)
manufacturing.
333514....... Special die and 3,172 3,232 57,576 319 325 325 .............. 7,232,706 2,280,172 2,237,842
tool, die set,
jig, and
fixture
manufacturing.
333515....... Cutting tool and 1,482 1,552 34,922 188 197 197 .............. 4,941,932 3,334,637 3,184,235
machine tool
accessory
manufacturing.
333516....... Rolling mill 70 73 3,020 17 17 17 .............. 652,141 9,316,299 8,933,437
machinery and
equipment
manufacturing.
333518....... Other 362 383 12,470 67 70 70 .............. 2,605,582 7,197,740 6,803,086
metalworking
machinery
manufacturing.
333612....... Speed changer, 197 226 12,374 61 70 70 .............. 2,280,825 11,577,790 10,092,145
industrial high-
speed drive,
and gear
manufacturing.
333613....... Mechanical power 196 231 15,645 75 88 88 .............. 3,256,010 16,612,294 14,095,280
transmission
equipment
manufacturing.
333911....... Pump and pumping 413 490 30,764 147 174 174 .............. 7,872,517 19,061,785 16,066,362
equipment
manufacturing.
333912....... Air and gas 272 318 21,417 104 121 121 .............. 6,305,944 23,183,616 19,830,011
compressor
manufacturing.
333991....... Power-driven 137 150 8,714 45 49 49 .............. 3,115,514 22,740,979 20,770,094
handtool
manufacturing.
333992....... Welding and 250 275 15,853 82 90 90 .............. 4,257,678 17,030,713 15,482,466
soldering
equipment
manufacturing.
333993....... Packaging 583 619 21,179 113 120 120 .............. 4,294,579 7,366,345 6,937,931
machinery
manufacturing.
333994....... Industrial 312 335 10,720 56 61 61 .............. 1,759,938 5,640,828 5,253,548
process furnace
and oven
manufacturing.
333995....... Fluid power 269 319 19,887 95 112 112 .............. 3,991,832 14,839,523 12,513,579
cylinder and
actuator
manufacturing.
333996....... Fluid power pump 146 178 13,631 63 77 77 .............. 3,019,188 20,679,367 16,961,728
and motor
manufacturing.
333997....... Scale and 95 102 3,748 20 21 21 .............. 694,419 7,309,671 6,808,027
balance (except
laboratory)
manufacturing.
333999....... All other 1,630 1,725 52,454 280 296 296 .............. 9,791,511 6,007,062 5,676,238
miscellaneous
general purpose
machinery
manufacturing.
334518....... Watch, clock, 104 106 2,188 12 12 12 .............. 491,114 4,722,250 4,633,151
and part
manufacturing.
335211....... Electric 99 105 7,425 20 22 22 .............. 2,175,398 21,973,717 20,718,076
housewares and
household fans.
335221....... Household 116 125 16,033 43 47 47 .............. 4,461,008 38,456,968 35,688,066
cooking
appliance
manufacturing.
335222....... Household 18 26 17,121 18 26 50 .............. 4,601,594 255,644,105 176,984,380
refrigerator
and home
freezer
manufacturing.
335224....... Household 17 23 16,269 17 23 47 .............. 4,792,444 281,908,445 208,367,112
laundry
equipment
manufacturing.
335228....... Other major 39 45 12,806 32 37 37 .............. 4,549,859 116,663,058 101,107,984
household
appliance
manufacturing.
336111....... Automobile 167 181 75,225 167 181 425 .............. 87,308,106 522,803,033 482,365,229
manufacturing.
336112....... Light truck and 63 94 103,815 63 94 587 .............. 139,827,543 2,219,484,812 1,487,527,055
utility vehicle
manufacturing.
336120....... Heavy duty truck 77 95 32,122 77 95 181 .............. 17,387,065 225,806,042 183,021,739
manufacturing.
336211....... Motor vehicle 728 820 47,566 239 269 269 .............. 11,581,029 15,908,007 14,123,206
body
manufacturing.
336212....... Truck trailer 353 394 32,260 163 182 182 .............. 6,313,133 17,884,229 16,023,179
manufacturing.
336213....... Motor home 79 91 21,533 79 91 122 .............. 5,600,569 70,893,283 61,544,718
manufacturing.
336311....... Carburetor, 102 116 10,537 52 60 60 .............. 2,327,226 22,815,945 20,062,296
piston, piston
ring, and valve
manufacturing.
336312....... Gasoline engine 810 876 66,112 345 373 373 .............. 30,440,351 37,580,680 34,749,259
and engine
parts
manufacturing.
336322....... Other motor 643 697 62,016 323 350 350 .............. 22,222,133 34,560,082 31,882,544
vehicle
electrical and
electronic
equipment
manufacturing.
336330....... Motor vehicle 214 257 39,390 185 223 223 .............. 10,244,934 47,873,524 39,863,557
steering and
suspension
components
(except spring)
manufacturing.
336340....... Motor vehicle 188 241 33,782 149 191 191 .............. 11,675,801 62,105,323 48,447,306
brake system
manufacturing.
336350....... Motor vehicle 432 535 83,756 382 473 473 .............. 31,710,273 73,403,409 59,271,538
transmission
and power train
parts
manufacturing.
336370....... Motor vehicle 635 781 110,578 508 624 624 .............. 24,461,822 38,522,554 31,321,154
metal stamping.
336399....... All other motor 1,189 1,458 149,251 687 843 843 .............. 42,936,991 36,111,851 29,449,239
vehicle parts
manufacturing.
336611....... Ship building 575 635 87,352 575 635 2,798 .............. 14,650,189 25,478,589 23,071,163
and repair.
336612....... Boat building... 1,066 1,129 54,705 1,066 1,129 1,752 .............. 10,062,908 9,439,876 8,913,116
336992....... Military armored 47 57 6,899 32 39 39 .............. 2,406,966 51,212,047 42,227,477
vehicle, tank,
and tank
component
manufacturing.
337215....... Showcase, 1,647 1,733 59,080 317 334 334 .............. 8,059,533 4,893,462 4,650,625
partition,
shelving, and
locker
manufacturing.
339114....... Dental equipment 740 763 15,550 399 411 411 .............. 3,397,252 4,590,881 4,452,493
and supplies
manufacturing.
339116....... Dental 7,028 7,261 47,088 7,028 7,261 33,214 .............. 3,852,293 548,135 530,546
laboratories.
339911....... Jewelry (except 1,760 1,777 25,280 1,760 1,777 7,813 .............. 6,160,238 3,500,135 3,466,650
costume)
manufacturing.
339913....... Jewelers' 261 264 5,199 261 264 1,607 .............. 934,387 3,580,028 3,539,346
materials and
lapidary work
manufacturing.
339914....... Costume jewelry 590 590 6,775 590 590 1,088 .............. 751,192 1,273,206 1,273,206
and novelty
manufacturing.
339950....... Sign 6,291 6,415 89,360 487 496 496 .............. 11,299,429 1,796,126 1,761,407
manufacturing.
423840....... Industrial 7,016 10,742 111,198 250 383 383 .............. 19,335,522 2,755,918 1,799,993
supplies,
wholesalers.
482110....... Rail N/A N/A N/A N/A N/A 16,895 .............. N/A N/A N/A
transportation.
621210....... Dental offices.. 119,471 124,553 817,396 7,655 7,980 7,980 .............. 88,473,742 740,546 710,330
----------------------------------------------------------------------------------------------------------------------------------------------------------------
Subtotals--Ge 219,203 238,942 4,406,990 47,007 56,121 294,886 .............. 1,101,555,989 5,025,278 4,610,140
neral
Industry and
maritime.
----------------------------------------------------------------------------------------------------------------------------------------------------------------
Totals--All 1,025,888 1,041,291 17,508,728 532,866 533,597 2,144,061 652,029 $2,649,803,698 $2,619,701 $2,544,729
Industries.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
a U.S. Census Bureau, Statistics of U.S. Businesses, 2006.
\b\ OSHA estimates of employees potentially exposed to silica and associated entities and establishments. Affected entities and establishments constrained to be less than or equal to the
number of affected employees.
\c\ Estimates based on 2002 receipts and payroll data from U.S. Census Bureau, Statistics of U.S. Businesses, 2002, and payroll data from the U.S. Census Bureau, Statistics of U.S. Businesses,
2006. Receipts are not reported for 2006, but were estimated assuming the ratio of receipts to payroll remained unchanged from 2002 to 2006.
\d\ State-plan states only. State and local governments are included under the construction sector because the silica risks for public employees are the result of construction-related
activities.
\e\ OSHA estimates that only one-third of the entities and establishments in this industry, as reported above, use silica-containing inputs.
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG, 2013.
As shown in Table VIII-3, OSHA estimates that a total of 533,000
entities (486,000 in construction; 47,000 in general industry and
maritime), 534,000 establishments (477,500 in construction; 56,100 in
general industry and maritime), and 2.1 million workers (1.8 million in
construction; 0.3 million in general industry and maritime) would be
affected by the proposed silica rule. Note that only slightly more than
50 percent of the entities and establishments, and about 12 percent of
the workers in affected industries, actually engage in activities
involving silica exposure.\9\
---------------------------------------------------------------------------
\9\ 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
14 percent of the workers in construction, but only 7 percent of
workers in general industry, actually engage in activities involving
silica exposure. As an example within construction, about 63 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.
---------------------------------------------------------------------------
The ninth column in Table VIII-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.\10\
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 VIII-3, the 1.8 million affected workers in
construction converts to approximately 652,000 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.
---------------------------------------------------------------------------
\10\ 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).
---------------------------------------------------------------------------
The last three columns in Table VIII-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 PEA 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 proposed rule.
Chapter IV of the PEA includes a section with a detailed
description of the methods used to develop the exposure profile and to
assess the technological feasibility of the proposed standard. That
section documents how OSHA selected and used the data to establish the
exposure profiles for each operation in the affected industry sectors,
and discusses sources of uncertainly including the following:
Data Selection--OSHA discusses how exposure samples with
sample durations of less than 480 minutes (an 8-hour shift) are used in
the analysis.
Use of IMIS data--OSHA discusses the limitations of data
from its Integrated Management Information System.
Use of analogous information--OSHA discusses how
information from one industry or operation is used to describe
exposures in other industries or operations with similar
characteristics.
Non-Detects--OSHA discusses how exposure data that is
identified as "less than the LOD (limit of detection)" is used in the
analysis.
OSHA seeks comment on the assumptions and data selection criteria
the Agency used to develop the exposure profiles shown in Chapter IV of
the PEA.
Table VIII-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 VIII-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 1,026,000 workers (851,000 in construction; 176,000 in
general industry and maritime) currently have silica exposures at or
above the proposed action level of 25 [mu]g/m\3\; an estimated 770,000
workers (648,000 in construction; 122,000 in general industry and
maritime) currently have silica exposures above the proposed PEL of 50
[mu]g/m\3\; and an estimated 501,000 workers (420,000 in construction;
81,000 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
[GRAPHIC] [TIFF OMITTED] TP12SE13.006
[GRAPHIC] [TIFF OMITTED] TP12SE13.007
BILLING CODE 4510-26-C
Table VIII-5--Numbers of Workers Exposed to Silica (by Affected Industry and Exposure Level ([mu]g/m\3\))
--------------------------------------------------------------------------------------------------------------------------------------------------------
Numbers exposed to Silica
NAICS Industry Number of Number of ----------------------------------------------------------------
establishments employees >=0 >=25 >=50 >=100 >=250
--------------------------------------------------------------------------------------------------------------------------------------------------------
Construction
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100......................... Residential Building 198,912 966,198 55,338 32,260 24,445 14,652 7,502
Construction.
236200......................... Nonresidential 44,702 741,978 173,939 83,003 63,198 39,632 20,504
Building Construction.
237100......................... Utility System 21,232 496,628 217,070 76,687 53,073 28,667 9,783
Construction.
237200......................... Land Subdivision...... 12,469 77,406 6,511 1,745 1,172 560 186
237300......................... Highway, Street, and 11,860 325,182 204,899 58,441 39,273 19,347 7,441
Bridge Construction.
237900......................... Other Heavy and Civil 5,561 90,167 46,813 12,904 8,655 4,221 1,369
Engineering
Construction.
238100......................... Foundation, Structure, 117,456 1,167,986 559,729 396,582 323,119 237,537 134,355
and Building Exterior
Contractors.
238200......................... Building Equipment 182,368 1,940,281 20,358 6,752 4,947 2,876 1,222
Contractors.
238300......................... Building Finishing 133,343 975,335 120,012 49,202 37,952 24,662 14,762
Contractors.
238900......................... Other Specialty Trade 74,446 557,638 274,439 87,267 60,894 32,871 13,718
Contractors.
999000......................... State and local NA 5,762,939 170,068 45,847 31,080 15,254 5,161
governments [d].
------------------------------------------------------------------------------------------------------------------------
Subtotals--Construction.... ...................... 802,349 13,101,738 1,849,175 850,690 647,807 420,278 216,003
--------------------------------------------------------------------------------------------------------------------------------------------------------
General Industry and Maritime
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121......................... Asphalt paving mixture 1,431 14,471 5,043 48 48 0 0
and block
manufacturing.
324122......................... Asphalt shingle and 224 12,631 4,395 4,395 1,963 935 0
roofing materials.
325510......................... Paint and coating 1,344 46,209 3,285 404 404 404 404
manufacturing.
327111......................... Vitreous china 41 5,854 2,802 2,128 1,319 853 227
plumbing fixtures &
bathroom accessories
manufacturing.
327112......................... Vitreous china, fine 731 9,178 4,394 3,336 2,068 1,337 356
earthenware, & other
pottery product
manufacturing.
327113......................... Porcelain electrical 125 6,168 2,953 2,242 1,390 898 239
supply mfg.
327121......................... Brick and structural 204 13,509 5,132 3,476 2,663 1,538 461
clay mfg.
327122......................... Ceramic wall and floor 193 7,094 2,695 1,826 1,398 808 242
tile mfg.
327123......................... Other structural clay 49 1,603 609 412 316 182 55
product mfg.
327124......................... Clay refractory 129 4,475 1,646 722 364 191 13
manufacturing.
327125......................... Nonclay refractory 105 5,640 2,075 910 459 241 17
manufacturing.
327211......................... Flat glass 83 11,003 271 164 154 64 45
manufacturing.
327212......................... Other pressed and 499 20,625 1,034 631 593 248 172
blown glass and
glassware
manufacturing.
327213......................... Glass container 72 14,392 722 440 414 173 120
manufacturing.
327320......................... Ready-mixed concrete 6,064 107,190 43,920 32,713 32,110 29,526 29,526
manufacturing.
327331......................... Concrete block and 951 22,738 10,962 5,489 3,866 2,329 929
brick mfg.
327332......................... Concrete pipe mfg..... 385 14,077 6,787 3,398 2,394 1,442 575
327390......................... Other concrete product 2,281 66,095 31,865 15,957 11,239 6,769 2,700
mfg.
327991......................... Cut stone and stone 1,943 30,633 12,085 10,298 7,441 4,577 1,240
product manufacturing.
327992......................... Ground or treated 271 6,629 5,051 5,051 891 297 0
mineral and earth
manufacturing.
327993......................... Mineral wool 321 19,241 1,090 675 632 268 182
manufacturing.
327999......................... All other misc. 465 10,028 4,835 2,421 1,705 1,027 410
nonmetallic mineral
product mfg.
331111......................... Iron and steel mills.. 805 108,592 614 456 309 167 57
331112......................... Electrometallurgical 22 2,198 12 9 6 3 1
ferroalloy product
manufacturing.
331210......................... Iron and steel pipe 240 21,543 122 90 61 33 11
and tube
manufacturing from
purchased steel.
331221......................... Rolled steel shape 170 10,857 61 46 31 17 6
manufacturing.
331222......................... Steel wire drawing.... 288 14,669 83 62 42 23 8
331314......................... Secondary smelting and 150 7,381 42 31 21 11 4
alloying of aluminum.
331423......................... Secondary smelting, 31 1,278 7 5 4 2 1
refining, and
alloying of copper.
331492......................... Secondary smelting, 217 9,383 53 39 27 14 5
refining, and
alloying of
nonferrous metal
(except cu & al).
331511......................... Iron foundries........ 527 59,209 22,111 16,417 11,140 6,005 2,071
331512......................... Steel investment 132 16,429 5,934 4,570 3,100 1,671 573
foundries.
331513......................... Steel foundries 222 17,722 6,618 4,914 3,334 1,797 620
(except investment).
331524......................... Aluminum foundries 466 26,565 9,633 7,418 5,032 2,712 931
(except die-casting).
331525......................... Copper foundries 256 6,120 2,219 1,709 1,159 625 214
(except die-casting).
331528......................... Other nonferrous 124 4,710 1,708 1,315 892 481 165
foundries (except die-
casting).
332111......................... Iron and steel forging 398 26,596 150 112 76 41 14
332112......................... Nonferrous forging.... 77 8,814 50 37 25 13 5
332115......................... Crown and closure 59 3,243 18 14 9 5 2
manufacturing.
332116......................... Metal stamping........ 1,641 64,724 366 272 184 99 34
332117......................... Powder metallurgy part 129 8,362 47 35 24 13 4
manufacturing.
332211......................... Cutlery and flatware 141 5,779 33 24 16 9 3
(except precious)
manufacturing.
332212......................... Hand and edge tool 1,155 36,622 207 154 104 56 19
manufacturing.
332213......................... Saw blade and handsaw 136 7,304 41 31 21 11 4
manufacturing.
332214......................... Kitchen utensil, pot, 70 3,928 22 17 11 6 2
and pan manufacturing.
332323......................... Ornamental and 2,450 39,947 54 26 19 7 7
architectural metal
work.
332439......................... Other metal container 401 15,195 86 64 43 23 8
manufacturing.
332510......................... Hardware manufacturing 828 45,282 256 190 129 69 24
332611......................... Spring (heavy gauge) 113 4,059 23 17 12 6 2
manufacturing.
332612......................... Spring (light gauge) 340 15,336 87 64 44 24 8
manufacturing.
332618......................... Other fabricated wire 1,198 36,364 205 153 104 56 19
product manufacturing.
332710......................... Machine shops......... 21,356 266,597 1,506 1,118 759 409 141
332812......................... Metal coating and 2,599 56,978 4,695 2,255 1,632 606 606
allied services.
332911......................... Industrial valve 488 38,330 216 161 109 59 20
manufacturing.
332912......................... Fluid power valve and 381 35,519 201 149 101 55 19
hose fitting
manufacturing.
332913......................... Plumbing fixture 144 11,513 65 48 33 18 6
fitting and trim
manufacturing.
332919......................... Other metal valve and 268 18,112 102 76 51 28 10
pipe fitting
manufacturing.
332991......................... Ball and roller 180 27,197 154 114 77 42 14
bearing manufacturing.
332996......................... Fabricated pipe and 765 27,201 154 114 77 42 14
pipe fitting
manufacturing.
332997......................... Industrial pattern 461 5,281 30 22 15 8 3
manufacturing.
332998......................... Enameled iron and 76 5,655 96 56 38 16 11
metal sanitary ware
manufacturing.
332999......................... All other 3,123 72,201 408 303 205 111 38
miscellaneous
fabricated metal
product manufacturing.
333319......................... Other commercial and 1,349 53,012 299 222 151 81 28
service industry
machinery
manufacturing.
333411......................... Air purification 351 14,883 84 62 42 23 8
equipment
manufacturing.
333412......................... Industrial and 163 10,506 59 44 30 16 6
commercial fan and
blower manufacturing.
333414......................... Heating equipment 407 20,577 116 86 59 32 11
(except warm air
furnaces)
manufacturing.
333511......................... Industrial mold 2,126 39,917 226 168 114 61 21
manufacturing.
333512......................... Machine tool (metal 530 17,220 97 72 49 26 9
cutting types)
manufacturing.
333513......................... Machine tool (metal 285 8,556 48 36 24 13 5
forming types)
manufacturing.
333514......................... Special die and tool, 3,232 57,576 325 241 164 88 30
die set, jig, and
fixture manufacturing.
333515......................... Cutting tool and 1,552 34,922 197 146 99 54 18
machine tool
accessory
manufacturing.
333516......................... Rolling mill machinery 73 3,020 17 13 9 5 2
and equipment
manufacturing.
333518......................... Other metalworking 383 12,470 70 52 35 19 7
machinery
manufacturing.
333612......................... Speed changer, 226 12,374 70 52 35 19 7
industrial high-speed
drive, and gear
manufacturing.
333613......................... Mechanical power 231 15,645 88 66 44 24 8
transmission
equipment
manufacturing.
333911......................... Pump and pumping 490 30,764 174 129 88 47 16
equipment
manufacturing.
333912......................... Air and gas compressor 318 21,417 121 90 61 33 11
manufacturing.
333991......................... Power-driven handtool 150 8,714 49 37 25 13 5
manufacturing.
333992......................... Welding and soldering 275 15,853 90 67 45 24 8
equipment
manufacturing.
333993......................... Packaging machinery 619 21,179 120 89 60 32 11
manufacturing.
333994......................... Industrial process 335 10,720 61 45 31 16 6
furnace and oven
manufacturing.
333995......................... Fluid power cylinder 319 19,887 112 83 57 31 11
and actuator
manufacturing.
333996......................... Fluid power pump and 178 13,631 77 57 39 21 7
motor manufacturing.
333997......................... Scale and balance 102 3,748 21 16 11 6 2
(except laboratory)
manufacturing.
333999......................... All other 1,725 52,454 296 220 149 80 28
miscellaneous general
purpose machinery
manufacturing.
334518......................... Watch, clock, and part 106 2,188 12 9 6 3 1
manufacturing.
335211......................... Electric housewares 105 7,425 22 10 8 3 3
and household fans.
335221......................... Household cooking 125 16,033 47 22 16 6 6
appliance
manufacturing.
335222......................... Household refrigerator 26 17,121 50 24 17 7 7
and home freezer
manufacturing.
335224......................... Household laundry 23 16,269 47 23 17 6 6
equipment
manufacturing.
335228......................... Other major household 45 12,806 37 18 13 5 5
appliance
manufacturing.
336111......................... Automobile 181 75,225 425 316 214 115 40
manufacturing.
336112......................... Light truck and 94 103,815 587 436 296 159 55
utility vehicle
manufacturing.
336120......................... Heavy duty truck 95 32,122 181 135 91 49 17
manufacturing.
336211......................... Motor vehicle body 820 47,566 269 200 135 73 25
manufacturing.
336212......................... Truck trailer 394 32,260 182 135 92 50 17
manufacturing.
336213......................... Motor home 91 21,533 122 90 61 33 11
manufacturing.
336311......................... Carburetor, piston, 116 10,537 60 44 30 16 6
piston ring, and
valve manufacturing.
336312......................... Gasoline engine and 876 66,112 373 277 188 101 35
engine parts
manufacturing.
336322......................... Other motor vehicle 697 62,016 350 260 176 95 33
electrical and
electronic equipment
manufacturing.
336330......................... Motor vehicle steering 257 39,390 223 165 112 60 21
and suspension
components (except
spring) manufacturing.
336340......................... Motor vehicle brake 241 33,782 191 142 96 52 18
system manufacturing.
336350......................... Motor vehicle 535 83,756 473 351 238 128 44
transmission and
power train parts
manufacturing.
336370......................... Motor vehicle metal 781 110,578 624 464 315 170 58
stamping.
336399......................... All other motor 1,458 149,251 843 626 425 229 79
vehicle parts
manufacturing.
336611......................... Ship building and 635 87,352 2,798 2,798 1,998 1,599 1,199
repair.
336612......................... Boat building......... 1,129 54,705 1,752 1,752 1,252 1,001 751
336992......................... Military armored 57 6,899 39 29 20 11 4
vehicle, tank, and
tank component
manufacturing.
337215......................... Showcase, partition, 1,733 59,080 334 248 168 91 31
shelving, and locker
manufacturing.
339114......................... Dental equipment and 763 15,550 411 274 274 137 0
supplies
manufacturing.
339116......................... Dental laboratories... 7,261 47,088 33,214 5,357 1,071 0 0
339911......................... Jewelry (except 1,777 25,280 7,813 4,883 3,418 2,442 977
costume)
manufacturing.
339913......................... Jewelers' materials 264 5,199 1,607 1,004 703 502 201
and lapidary work
manufacturing.
339914......................... Costume jewelry and 590 6,775 1,088 685 479 338 135
novelty manufacturing.
339950......................... Sign manufacturing.... 6,415 89,360 496 249 172 57 57
423840......................... Industrial supplies, 10,742 111,198 383 306 153 77 0
wholesalers.
482110......................... Rail transportation... NA NA 16,895 11,248 5,629 2,852 1,233
621210......................... Dental offices........ 124,553 817,396 7,980 1,287 257 0 0
------------------------------------------------------------------------------------------------------------------------
Subtotals--General Industry ...................... 238,942 4,406,990 294,886 175,801 122,472 80,731 48,956
and Maritime.
------------------------------------------------------------------------------------------------------------------------
Totals................. ...................... 1,041,291 17,508,728 2,144,061 1,026,491 770,280 501,009 264,959
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on Table III-5 and the technological
feasibility analysis presented in Chapter IV of the PEA.
D. Technological Feasibility Analysis of the Proposed Permissible
Exposure Limit to Crystalline Silica Exposures
Chapter IV of the Preliminary Economic Analysis (PEA) provides the
technological feasibility analysis that guided OSHA's selection of the
proposed PEL, 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) (emphasis added).
The Court of Appeals for the D.C. Circuit has clarified the Agency's
obligation to demonstrate 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 America, AFL-CIO-CIC v. Marshall, 647 F.2d 1189,
1272 (D.C. Cir. 1980).
Additionally, the D.C. Circuit has 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. . . ." American Iron &
Steel Inst. v. OSHA, 939 F.2d 975, 990 (D.C. Cir. 1991).
To demonstrate the limits of feasibility, OSHA's analysis examines
the technological feasibility of the proposed PEL of 50 [mu]g/m\3\, as
well as the technological feasibility of an alternative PEL of 25 [mu]g/m\3\.
In total, OSHA analyzed technological feasibility in 108 operations in
general industry, maritime, and construction industries. This analysis
addresses two different aspects of technological feasibility: (1) The
extent to which engineering controls can reduce and maintain exposures;
and (2) the capability of existing sampling and analytical methods to
measure silica exposures. The discussion below summarizes the findings
in Chapter IV of the PEA (see Docket No. OSHA-2010-0034).
Methodology
The technological feasibility analysis relies on information from a
wide variety of sources. These sources include published literature,
OSHA inspection reports, NIOSH reports and engineering control
feasibility studies, and information from other federal agencies, state
agencies, labor organizations, industry associations, and other groups.
OSHA has limited the analysis to job categories that are associated
with substantial direct silica exposure. The technological feasibility
analyses group the general industry and maritime workplaces into 23
industry sectors.\11\ The Agency has divided each industry sector into
specific job categories on the basis of common 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.
---------------------------------------------------------------------------
\11\ Note that OSHA's technological feasibility analysis
contains 21 general industry sections. The number is expanded to 23
in this summary because Table VIII.D-1 describes the foundry
industry as three different sectors (ferrous, nonferrous, and non-
sand casting foundries) to provide a more detailed analysis of
exposures.
---------------------------------------------------------------------------
OSHA has organized the construction industry by grouping workers
into 12 general construction activities. The Agency organized
construction workers into general activities that create silica
exposures rather than organizing them by job titles because
construction workers often perform multiple activities and job titles
do not always coincide with the sources of exposure. In organizing
construction worker activity this way, OSHA was able to create a more
accurate exposure profile and apply control methods to workers who
perform these activities in any segment of the construction industry.
The exposure profiles include silica exposure data only for workers
in the United States. Information on international exposure levels is
occasionally referenced for perspective or in discussions of control
options. It is important to note that the vast majority of crystalline
silica encountered by workers 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 measurements of personal breathing zone
(PBZ) respirable crystalline silica.
In general and maritime industries, the exposure profiles in the
technological feasibility analysis consist mainly of full-shift
samples, collected over periods of 360 minutes or more. By using full-
shift sampling results, OSHA minimizes the number of results that are
less than the limit of detection (LOD) and eliminates the ambiguity
associated with the LOD for low air volume samples. Thus, results that
are reported in the original data source as below the LOD are included
without contributing substantial uncertainty regarding their
relationship to the proposed PEL. This is particularly important for
general industry samples, which on average have lower silica levels
than typical results for many tasks in the construction industry.
In general and maritime industries, the exposure level for the
period sampled is assumed to have continued over any unsampled portion
of the worker's shift. OSHA has preliminarily determined that this
sample criterion is valid because workers in these industries are
likely to work at the same general task or same repeating set of tasks
over most of their shift; thus, unsampled periods generally are likely
to be similar to the sampled periods.
In the construction industry, much of the data analyzed for the
defined activities consisted of full-shift samples collected over
periods of 360 minutes or more. Construction workers are likely to
spend a shift working at multiple discrete tasks, independent of
occupational titles, and do not normally engage in those discrete tasks
for the entire duration of a shift. Therefore, the Agency occasionally
included partial-shift samples (periods of less than 360 minutes), but
has limited the use of partial-shift samples with results below the
LOD, giving preference to data covering a greater part of the workers'
shifts.
OSHA believes that the partial-shift samples were collected for the
entire duration of the task and that the exposure to silica ended when
the task was completed. Therefore, OSHA assumes that the exposure to
silica was zero for the remaining unsampled time. OSHA understands that
this may not always be the case, and that there may be activities other
than the sampled tasks that affect overall worker exposures, but the
documentation regarding these factors is insufficient to use in
calculating a time-weighted average. It is important to note, however,
that the Agency has identified to the best of its ability the
construction activities that create significant exposures to respirable
crystalline silica.
In cases where exposure information from a specific job category is
not available, OSHA has based that portion of the exposure profile on
surrogate data from one or more similar job categories in related
industries. The surrogate data is selected based on strong similarities
of raw materials, equipment, worker activities, and exposure duration
between the job categories. When used, OSHA has clearly identified the
surrogate data and the relationship between the industries or job
categories.
1. Feasibility Determination of Sampling and Analytical Methods
As part of its technological feasibility analysis, OSHA examined
the capability of currently available sampling methods and sensitivity
\12\ and precision of currently available analytical methods to measure
respirable crystalline silica (please refer to the "Feasibility of
Measuring Respirable Crystalline Silica Exposures at The Proposed PEL"
section in Chapter IV of the PEA). The Agency understands that several
commercially available personal sampling cyclones exist that can be
operated at flow rates that conform to the ISO/CEN particle size
selection criteria with an acceptable level of bias. Some of these
sampling devices are the Dorr-Oliver, Higgens-Dowel, BGI GK 2.69, and
the SKC G-3 cyclones. Bias against the ISO/CEN criteria will fall
within 20 percent, and often is within 10
percent.
---------------------------------------------------------------------------
\12\ Note that sensitivity refers to the smallest quantity that
can be measured with a specified level of accuracy, expressed either
as the limit of detection or limit of quantification.
---------------------------------------------------------------------------
Additionally, the Agency preliminarily concludes that all of the
mentioned cyclones are capable of allowing a sufficient quantity of
quartz to be collected from atmospheric concentrations as low as 25
[mu]g/m\3\ to exceed the limit of quantification for the OSHA ID-142
analytical method, provided that a sample duration is at least 4 hours.
Furthermore, OSHA believes that these devices are also capable of
collecting more than the minimum amount of cristobalite at the proposed
PEL and action level necessary for quantification with OSHA's method ID-142 for a full
shift. One of these cyclones (GK 2.69) can also collect an amount of
cristobalite exceeding OSHA's limit of quantification (LOQ) with a 4-
hour sample at the proposed PEL and action level.
Regarding analytical methods to measure silica, OSHA investigated
the sensitivity and precision of available methods. The Agency
preliminarily concludes that the X-Ray Diffraction (XRD) and Infrared
Spectroscopy (IR) methods of analysis are both sufficiently sensitive
to quantify levels of quartz and cristobalite that would be collected
on air samples taken from concentrations at the proposed PEL and action
level. Available information shows that poor inter-laboratory agreement
and lack of specificity render colorimetric spectrophotometry (another
analytical method) inferior to XRD or IR techniques. As such, OSHA is
proposing not to permit employers to rely on exposure monitoring
results based on analytical methods that use colorimetric methods.
For the OSHA XRD Method ID-142 (revised December 1996), precision
is 23 percent at a working range of 50 to 160 [micro]g
crystalline silica, and the SAE (sampling and analytical error) is
19 percent. The NIOSH and MSHA XRD and IR methods report a
similar degree of precision. OSHA's Salt Lake Technical Center (SLTC)
evaluated the precision of ID-142 at lower filter loadings and has
shown an acceptable level of precision is achieved at filter loadings
of approximately 40 [micro]g and 20 [micro]g corresponding to the
amounts collected from full-shift sampling at the proposed PEL and
action level, respectively. This analysis showed that at filter
loadings corresponding to the proposed PEL, the precision and SAE for
quartz are 17 and 14 percent, respectively. For
cristobalite, the precision and SAE are 19 and 16 percent, respectively. These results indicate that employers
can have confidence in sampling results for the purpose of assessing
compliance with the PEL and identifying when additional engineering and
work practice controls and/or respiratory protection are needed.
For example, given an SAE for quartz of 0.14 at a filter load of 40
[micro]g, employers can be virtually certain that the PEL is not
exceeded where exposures are less than 43 [micro]g/m\3\, which
represents the lower 95-percent confidence limit (i.e., 50 [micro]g/
m\3\ minus 50*0.14). At 43 [micro]g/m\3\, a full-shift sample that
collects 816 L of air will result in a filter load of 35 [micro]g of
quartz, or more than twice the LOQ for Method ID-142. Thus, OSHA
believes that the method is sufficiently sensitive and precise to allow
employers to distinguish between operations that have sufficient dust
control to comply with the PEL from those that do not. Finally, OSHA's
analysis of PAT data indicates that most laboratories achieve good
agreement in results for samples having filter loads just above 40
[micro]g quartz (49-70 [micro]g).
At the proposed action level, the study by SLTC found the precision
and SAE of the method for quartz at 20 [micro]g to be 19
and 16 percent, respectively. For cristobalite, the
precision and SAE at 20 [micro]g were also 19 and 16 percent, respectively. OSHA believes that these results show
that Method ID-142 can achieve a sufficient degree of precision for the
purpose of identifying those operations where routine exposure
monitoring should be conducted.
However, OSHA also believes that limitations in the
characterization of the precision of the analytical method in this
range of filter load preclude the Agency from proposing a PEL of 25
[micro]g/m\3\ at this time. First, the measurement error increases by
about 4 to 5 percent for a full-shift sample taken at 25 [micro]g/m\3\
compared to one taken at 50 [micro]g/m\3\, and the error would be
expected to increase further as filter loads approach the limit of
detection. Second, for an employer to be virtually certain that an
exposure to quartz did not exceed 25 [micro]g/m\3\ as an exposure
limit, the exposure would have to be below 21 [micro]g/m\3\ given the
SAE of 16 percent calculated from the SLTC study. For a
full-shift sample of 0.816 L of air, only about 17 [micro]g of quartz
would be collected at 21 [micro]g/m\3\, which is near the LOQ for
Method ID-142 and at the maximum acceptable LOD that would be required
by the proposed rule. Thus, given a sample result that is below a
laboratory's reported LOD, employers might not be able to rule out
whether a PEL of 25 [micro]g/m\3\ was exceeded.
Finally, there are no available data that describe the total
variability seen between laboratories at filter loadings in the range
of 20 [micro]g crystalline silica since the lowest filter loading used
in PAT samples is about 50 [micro]g. Given these considerations, OSHA
believes that a PEL of 50 [micro]g/m\3\ is more appropriate in that
employers will have more confidence that sampling results are properly
informing them where additional dust controls and respiratory
protection is needed.
Based on the evaluation of the nationally recognized sampling and
analytical methods for measuring respirable crystalline silica
presented in the section titled "Feasibility of Measuring Respirable
Crystalline Silica Exposures at The Proposed PEL" in Chapter IV of the
PEA, OSHA preliminarily concludes that it is technologically feasible
to reliably measure exposures of workers at the proposed PEL of 50
[micro]g/m\3\ and action level of 25 [micro]g/m\3\. OSHA notes that the
sampling and analytical error is larger at the proposed action level
than that for the proposed PEL. In the "Issues" section of this
preamble (see Provisions of the Standards--Exposure Assessment), OSHA
solicits comments on whether measurements of exposures at the proposed
action level and PEL are sufficiently precise to permit employers to
adequately determine when additional exposure monitoring is necessary
under the standard, when to provide workers with the required medical
surveillance, and when to comply with all other requirements of the
proposed standard. OSHA also solicits comments on the appropriateness
of specific requirements in the proposed standard for laboratories that
perform analyses of respirable crystalline silica samples to reduce the
variability between laboratories.
2. Feasibility Determination of Control Technologies
The Agency has conducted a feasibility analysis for each of the
identified 23 general industry sectors and 12 construction industry
activities that are potentially affected by the proposed silica
standard. Additionally, the Agency identified 108 operations within
those sectors/activities and developed exposure profiles for each
operation, except for two industries, engineered stone products and
landscape contracting industries. For these two industries, data
satisfying OSHA's criteria for inclusion in the exposure profile were
unavailable (refer to the Methodology section in Chapter 4 of the PEA
for criteria). However, the Agency obtained sufficient information in
both of these industries to make feasibility determinations (see
Chapter IV Sections C.7 and C.11 of the PEA). Each feasibility analysis
contains a description of the applicable operations, the baseline
conditions for each operation (including the respirable silica samples
collected), additional controls necessary to reduce exposures, and
final feasibility determinations for each operation.
3. Feasibility Findings for the Proposed Permissible Exposure Limit of
50 [mu]g/m\3\
Tables VIII-6 and VIII-7 summarize all the industry sectors and
construction activities studied in the technological feasibility analysis and show
how many operations within each can achieve levels of 50 [mu]g/m\3\
through the implementation of engineering and work practice controls.
The tables also summarize the overall feasibility finding for each
industry sector or construction activity based on the number of
feasible versus not feasible operations. For the general industry
sector, OSHA has preliminarily concluded that the proposed PEL of 50
[mu]g/m\3\ is technologically feasible for all affected industries. For
the construction activities, OSHA has determined that the proposed PEL
of 50 [mu]g/m\3\ is feasible in 10 out of 12 of the affected
activities. Thus, OSHA preliminarily concludes that engineering and
work practices will be sufficient to reduce and maintain silica
exposures to the proposed PEL of 50 [mu]g/m\3\ or below in most
operations most of the time in the affected industries. For those few
operations within an industry or activity where the proposed PEL is not
technologically feasible even when workers use recommended engineering
and work practice controls (seven out of 108 operations, see Tables
VIII-6 and VIII-7), employers can supplement controls with respirators
to achieve exposure levels at or below the proposed PEL.
4. Feasibility Findings for an Alternative Permissible Exposure Limit
of 25 [mu]g/m\3\
Based on the information presented in the technological feasibility
analysis, OSHA believes that engineering and work practice controls
identified to date will not be sufficient to consistently reduce
exposures to PELs lower than 50 [mu]g/m\3\. The Agency believes that a
proposed PEL of 25 [mu]g/m\3\, for example, would not be feasible for
many industries, and to use respiratory protection would have to be
required in most operations and most of the time to achieve compliance.
However, OSHA has data indicating that an alternative PEL of 25
[mu]g/m\3\ has already been achieved in several industries (e.g.
asphalt paving products, dental laboratories, mineral processing, and
paint and coatings manufacturing in general industry, and drywall
finishers and heavy equipment operators in construction). In these
industries, airborne respirable silica concentrations are inherently
low because either small amounts of silica containing materials are
handled or these materials are not subjected to high energy processes
that generate large amounts of respirable dust.
For many of the other industries, OSHA believes that engineering
and work practice controls will not be able to reduce and maintain
exposures to an alternative PEL of 25 [mu]g/m\3\ in most operations and
most of the time. This is especially the case in industries that use
silica containing material in substantial quantities and industries
with high energy operations. For example, in general industry, the
ferrous foundry industry would not be able to comply with an
alternative PEL of 25 [mu]g/m\3\ without widespread respirator use. In
this industry, silica containing sand is transported, used, and
recycled in significant quantities to create castings, and as a result,
workers can be exposed to high levels of silica in all steps of the
production line. Additionally, some high energy operations in foundries
create airborne dust that causes high worker exposures to silica. One
of these operations is the shakeout process, where operators monitor
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 workers in a foundry. For small,
medium, and large castings, exposure information with engineering
controls in place show that exposures below 50 [mu]g/m\3\ can be
consistently achieved, but exposures above an alternative PEL of 25
[mu]g/m\3\ still occur. With engineering controls in place, exposure
data for these operations range from 13 [mu]g/m\3\ to 53 [mu]g/m\3\,
with many of the reported exposures above 25 [mu]g/m\3\.
In the construction industry, OSHA estimates that an alternative
PEL of 25 [mu]g/m\3\ would be infeasible in most operations because
most of them are high energy operations that produce significant levels
of dust, causing workers to have elevated exposures, and available
engineering controls would not be able to maintain exposures at or
below the alternative PEL most of the time. For example, jackhammering
is a high energy operation that creates a large volume of silica
containing dust, which disburses rapidly in highly disturbed air. OSHA
estimates that the exposure levels of most workers operating
jackhammers outdoors will be reduced to less that 100 [mu]g/m\3\ as an
8-hour TWA, by using either wet methods or LEV paired with a suitable
vacuum.
OSHA believes that typically, the majority of jackhammering is
performed for less than four hours of a worker's shift, and in these
circumstances the Agency estimates that most workers will experience
levels below 50 [mu]g/m\3\. Jackhammer operators who work indoors or
with multiple jackhammers will achieve similar results granted that the
same engineering controls are used and that fresh air circulation is
provided to prevent accumulation of respirable dust in a worker's
vicinity. OSHA does not have any data indicating that these control
strategies would reduce exposures of most workers to levels of 25
[mu]g/m\3\ or less.
5. Overall Feasibility Determination
Based on the information presented in the technological feasibility
analysis, the Agency believes that 50 [mu]g/m\3\ is the lowest feasible
PEL. An alternative PEL of 25 [mu]g/m\3\ would not be feasible because
the engineering and work practice controls identified to date will not
be sufficient to consistently reduce exposures to levels below 25
[mu]g/m\3\ in most operations most of the time. OSHA believes that an
alternative PEL of 25 [mu]g/m\3\ would not be feasible for many
industries, and that the use of respiratory protection would be
necessary in most operations most of the time to achieve compliance.
Additionally, the current methods of sampling analysis create higher
errors and lower precision in measurement as concentrations of silica
lower than the proposed PEL are analyzed. However, the Agency
preliminarily concludes that these sampling and analytical methods are
adequate to permit employers to comply with all applicable requirements
triggered by the proposed action level and PEL.
Table VIII-6--Summary of Technological Feasibility of Control Technologies in General and Maritime Industries
Affected by Silica Exposures
----------------------------------------------------------------------------------------------------------------
Number of Number of
operations for operations for
which the which the
Total number proposed PEL is proposed PEL is Overall feasibility finding
Industry sector of affected achievable with NOT achievable for industry sector
operations engineering with engineering
controls and work controls and work
practice controls practice controls
----------------------------------------------------------------------------------------------------------------
Asphalt Paving Products...... 3 3 0 Feasible.
Asphalt Roofing Materials.... 2 2 0 Feasible.
Concrete Products............ 6 5 1 Feasible.
Cut Stone.................... 5 5 0 Feasible.
Dental Equipment and 1 1 0 Feasible.
Suppliers.
Dental Laboratories.......... 1 1 0 Feasible.
Engineered Stone Products.... 1 1 0 Feasible.
Foundries: Ferrous*.......... 12 12 0 Feasible.
Foundries: Nonferrous*....... 12 12 0 Feasible.
Foundries: Non-Sand Casting*. 11 11 0 Feasible.
Glass........................ 2 2 0 Feasible.
Jewelry...................... 1 1 0 Feasible.
Landscape Contracting........ 1 1 0 Feasible.
Mineral Processing........... 1 1 0 Feasible.
Paint and Coatings........... 2 2 0 Feasible.
Porcelain Enameling.......... 2 2 0 Feasible.
Pottery...................... 5 5 0 Feasible.
Railroads.................... 5 5 0 Feasible.
Ready-Mix Concrete........... 5 4 1 Feasible.
Refractories................. 5 5 0 Feasible.
Refractory Repair............ 1 1 0 Feasible.
Shipyards (Maritime Industry) 2 1 1 Feasible.
Structural Clay.............. 3 3 0 Feasible.
=================
Totals................... 89 96.6% 3.4% ...........................
----------------------------------------------------------------------------------------------------------------
* Section 8 of the Technological Feasibility Analysis includes four subsectors of the foundry industry. Each
subsector includes its own exposure profile and feasibility analysis in that section. This table lists three
of those four subsectors individually based on the difference in casting processes used and subsequent
potential for silica exposure. The table does not include captive foundries because the captive foundry
operations are incorporated into the larger manufacturing process of the parent foundry.
Table VIII-7--Summary of Technological Feasibility of Control Technologies in Construction Activities Affected
by Silica Exposures
----------------------------------------------------------------------------------------------------------------
Number of Number of
operations for operations for
which the which the
Total number proposed PEL is proposed PEL is Overall feasibility finding
Construction activity of affected achievable with NOT achievable for activity
operations engineering with engineering
controls and work controls and work
practice controls practice controls
----------------------------------------------------------------------------------------------------------------
Abrasive Blasters............ 2 0 2 Not Feasible.
Drywall Finishers............ 1 1 0 Feasible.
Heavy Equipment Operators.... 1 1 0 Feasible.
Hole Drillers Using Hand-Held 1 1 0 Feasible.
Drills.
Jackhammer and Impact 1 1 0 Feasible.
Drillers.
Masonry Cutters Using 3 3 0 Feasible.
Portable Saws.
Masonry Cutters Using 1 1 0 Feasible.
Stationary Saws.
Millers Using Portable and 3 3 0 Feasible.
Mobile Machines.
Rock and Concrete Drillers... 1 1 0 Feasible.
Rock-Crushing Machine 1 1 0 Feasible.
Operators and Tenders.
Tuckpointers and Grinders.... 3 1 2 Not Feasible.
Underground Construction 1 1 0 Feasible.
Workers.
----------------------------------------------------------------------------------
Totals................... 19 78.9% 21.1%
----------------------------------------------------------------------------------------------------------------
E. Costs of Compliance
Chapter V of the PEA in support of the proposed silica rule
provides a detailed assessment of the costs to establishments in all
affected industry sectors of reducing worker exposures to silica to an
eight-hour time-weighted average (TWA) permissible exposure limit (PEL)
of 50 [mu]g/m\3\ and of complying with the proposed standard's
ancillary requirements. The discussion below summarizes the findings in
the PEA cost chapter. OSHA's preliminary cost assessment is based on
the Agency's technological feasibility analysis presented in Chapter IV of the PEA (2013); analyses of the
costs of the proposed standard conducted by OSHA's contractor, Eastern
Research Group (ERG, 2007a, 2007b, and 2013); and the comments
submitted to the docket as part of the SBREFA panel process.
OSHA estimates that the proposed rule will cost $657.9 million per
year in 2009 dollars. Costs originally estimated for earlier years were
adjusted to 2009 dollars using the appropriate price indices. All costs
are annualized using a discount rate of 7 percent. (A sensitivity
analysis using discount rates of 3 percent and 0 percent is presented
in the discussion of net benefits.) One-time costs are annualized over
10-year annualization period, and capital goods are annualized over the
life of the equipment. OSHA has historically annualized one-time costs
over at least a 10-year period, which approximately reflects the
average life of a business in the United States. (The Agency has chosen
a longer annualization period under special circumstances, such as when
a rule involves longer and more complex phase-in periods. In general, a
longer annualization period, in such cases, will tend to reduce
annualized costs slightly.)
The estimated costs for the proposed silica standard rule include
the additional costs necessary for employers to achieve full
compliance. They do not include costs associated with current
compliance that has already been achieved with regard to the new
requirements or costs necessary to achieve compliance with existing
silica requirements, to the extent that some employers may currently
not be fully complying with applicable regulatory requirements.
Table VIII-8 provides the annualized costs of the proposed rule by
cost category for general industry, maritime, and construction. As
shown in Table VIII-8, of the total annualized costs of the proposed
rule, $132.5 million would be incurred by general industry, $14.2
million by maritime, and $511.2 million by construction.
Table VIII-9 shows the annualized costs of the proposed rule by
cost category and by industry for general industry and maritime, and
Table VIII-10 shows the annualized costs similarly disaggregated for
construction. These tables show that engineering control costs
represent 69 percent of the costs of the proposed standard for general
industry and maritime and 47 percent of the costs of the proposed
standard for construction. Considering other leading cost categories,
costs for exposure assessment and respirators represent, respectively,
20 percent and 5 percent of the costs of the proposed standard for
general industry and maritime; costs for respirators and medical
surveillance represent, respectively, 16 percent and 15 percent of the
costs of the proposed standard for construction.
While the costs presented here represent the Agency's best estimate
of the costs to industry of complying with the proposed rule under
static conditions (that is, using existing technology and the current
deployment of workers), OSHA recognizes that the 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 PEA, OSHA provides a sensitivity analysis of its cost
estimates by modifying certain critical unit cost factors. Beyond the
sensitivity analysis, however, OSHA believes its cost estimates may
significantly overstate the actual costs of the proposed rule because,
in response to the rule, industry may be able to take two types of
actions to reduce compliance costs.
First, in construction, 53 percent of the estimated costs of the
proposed rule (all costs except engineering controls) vary directly
with the number of workers exposed to silica. However, as shown in
Table VIII-3 of this preamble, almost three times as many construction
workers would be affected by the proposed rule as would the number of
full-time-equivalent construction workers necessary to do the work.
This is because most construction workers currently do work involving
silica exposure for only a portion of their workday. In 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.\13\ Were this
approach fully implemented in construction, the actual cost of the
proposed rule would decline by over 25 percent, or by $180 million
annually, to under $480 million annually.\14\
---------------------------------------------------------------------------
\13\ 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).
\14\ OSHA expected that such a structural change in construction
work assignments would not have a significant effect on the benefits
of the proposed rule. As discussed in Chapter VII of the PEA, the
benefits of the proposed rule are relatively insensitive to changes
in average occupational tenure or how total silica exposure in an
industry is distributed among individual workers.
---------------------------------------------------------------------------
Second, the costs presented here do not take into account the
likely development and dissemination of cost-reducing compliance
technology in response to the proposed rule.\15\ One possible example
is the development of safe substitutes for silica sand in abrasive
blasting operations, repair and replacement of refractory materials,
foundry operations, and the railroad transportation industry. Another
is expanded uses 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 production equipment
as standard equipment. Such advances would both increase the
effectiveness and reduce the costs of silica controls retrofitted to
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. Of
course, all the possible technological advances in response to the
proposed rule and their effects on costs are difficult to predict.\16\
---------------------------------------------------------------------------
\15\ Evidence of such technological responses to regulation is
widespread (see for example Ashford, Ayers, and Stone (1985), OTA
(1995), and OSHA's regulatory reviews of existing standards under
Sec. 610 of the Regulatory Flexibility Act ("610 lookback
reviews")).
\16\ 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 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.
---------------------------------------------------------------------------
OSHA has decided at this time not to create a more dynamic and
predictive analysis of possible cost-reducing technological advances or worker specialization because the
technological and economic feasibility of the proposed rule can easily
be demonstrated using existing technology and employment patterns.
However, OSHA believes that actual costs, if future developments of
this type were fully accounted for, would be lower than those estimated
here.
OSHA invites comment on this discussion concerning the costs of the
proposed rule.
Table VIII-8--Annualized Compliance Costs for Employers in General Industry, Maritime, and Construction Affected by OSHA's Proposed Silica Standard
[2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Engineering
controls Regulated
Industry (includes Respirators Exposure Medical Training areas or Total
abrasive assessment surveillance access control
blasting)
--------------------------------------------------------------------------------------------------------------------------------------------------------
General Industry........................ $88,442,480 $6,914,225 $29,197,633 $2,410,253 $2,952,035 $2,580,728 $132,497,353
Maritime................................ 12,797,027 NA 671,175 646,824 43,865 70,352 14,229,242
Construction............................ 242,579,193 84,004,516 44,552,948 76,012,451 47,270,844 16,745,663 511,165,616
---------------------------------------------------------------------------------------------------------------
Total............................... 343,818,700 90,918,741 74,421,757 79,069,527 50,266,744 19,396,743 657,892,211
--------------------------------------------------------------------------------------------------------------------------------------------------------
U.S. Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2007a, 2007b, and 2013).
Table VIII-9--Annualized Compliance Costs for All General Industry and Maritime Establishments Affected by the Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
Engineering
controls
NAICS Industry (includes Respirators Exposure Medical Training Regulated Total
abrasive assessment surveillance areas
blasting)
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121................... Asphalt paving mixture and $179,111 $2,784 $8,195 $962 $49,979 $1,038 $242,070
block manufacturing.
324122................... Asphalt shingle and roofing 2,194,150 113,924 723,761 39,364 43,563 42,495 3,157,257
materials.
325510................... Paint and coating 0 23,445 70,423 8,179 33,482 8,752 144,281
manufacturing.
327111................... Vitreous china plumbing 1,128,859 76,502 369,478 26,795 29,006 28,554 1,659,194
fixtures & bathroom
accessories manufacturing.
327112................... Vitreous china, fine 1,769,953 119,948 579,309 42,012 45,479 44,770 2,601,471
earthenware, & other
pottery product
manufacturing.
327113................... Porcelain electrical supply 1,189,482 80,610 389,320 28,234 30,564 30,087 1,748,297
mfg.
327121................... Brick and structural clay 6,966,654 154,040 554,322 53,831 51,566 57,636 7,838,050
mfg.
327122................... Ceramic wall and floor tile 3,658,389 80,982 306,500 28,371 27,599 30,266 4,132,107
mfg.
327123................... Other structural clay 826,511 18,320 72,312 6,417 6,302 6,838 936,699
product mfg.
327124................... Clay refractory 304,625 21,108 124,390 7,393 17,043 7,878 482,438
manufacturing.
327125................... Nonclay refractory 383,919 26,602 156,769 9,318 21,479 9,929 608,017
manufacturing.
327211................... Flat glass manufacturing... 227,805 8,960 29,108 3,138 2,800 3,344 275,155
327212................... Other pressed and blown 902,802 34,398 111,912 12,048 10,708 12,839 1,084,706
glass and glassware
manufacturing.
327213................... Glass container 629,986 24,003 78,093 8,374 7,472 8,959 756,888
manufacturing.
327320................... Ready-mixed concrete 7,029,710 1,862,221 5,817,205 652,249 454,630 695,065 16,511,080
manufacturing.
327331................... Concrete block and brick 2,979,495 224,227 958,517 78,536 113,473 83,692 4,437,939
mfg.
327332................... Concrete pipe mfg.......... 1,844,576 138,817 593,408 48,621 70,250 51,813 2,747,484
327390................... Other concrete product mfg. 8,660,830 651,785 2,786,227 228,290 329,844 243,276 12,900,251
327991................... Cut stone and stone product 5,894,506 431,758 1,835,498 151,392 126,064 161,080 8,600,298
manufacturing.
327992................... Ground or treated mineral 3,585,439 51,718 867,728 18,134 52,692 19,295 4,595,006
and earth manufacturing.
327993................... Mineral wool manufacturing. 897,980 36,654 122,015 12,852 11,376 13,675 1,094,552
327999................... All other misc. nonmetallic 1,314,066 98,936 431,012 34,691 50,435 36,911 1,966,052
mineral product mfg.
331111................... Iron and steel mills....... 315,559 17,939 72,403 6,129 5,836 6,691 424,557
331112................... Electrometallurgical 6,375 362 1,463 124 118 135 8,577
ferroalloy product
manufacturing.
331210................... Iron and steel pipe and 62,639 3,552 14,556 1,239 1,222 1,328 84,537
tube manufacturing from
purchased steel.
331221................... Rolled steel shape 31,618 1,793 7,348 625 617 670 42,672
manufacturing.
331222................... Steel wire drawing......... 42,648 2,419 9,911 843 832 904 57,557
331314................... Secondary smelting and 21,359 1,213 4,908 419 406 453 28,757
alloying of aluminum.
331423................... Secondary smelting, 3,655 207 857 72 71 78 4,940
refining, and alloying of
copper.
331492................... Secondary smelting, 27,338 1,551 6,407 539 531 580 36,946
refining, and alloying of
nonferrous metal (except
cu & al).
331511................... Iron foundries............. 11,372,127 645,546 2,612,775 223,005 216,228 241,133 15,310,815
331512................... Steel investment foundries. 3,175,862 179,639 739,312 62,324 58,892 67,110 4,283,138
331513................... Steel foundries (except 3,403,790 193,194 794,973 67,027 65,679 72,174 4,596,837
investment).
331524................... Aluminum foundries (except 5,155,172 291,571 1,220,879 101,588 97,006 108,935 6,975,150
die-casting).
331525................... Copper foundries (except 1,187,578 67,272 309,403 23,668 23,448 25,095 1,636,463
die-casting).
331528................... Other nonferrous foundries 914,028 51,701 212,778 17,937 16,949 19,314 1,232,708
(except die-casting).
332111................... Iron and steel forging..... 77,324 4,393 19,505 1,538 1,555 1,640 105,955
332112................... Nonferrous forging......... 25,529 1,451 6,440 508 513 541 34,982
332115................... Crown and closure 9,381 532 2,236 186 186 199 12,720
manufacturing.
332116................... Metal stamping............. 188,102 10,676 45,595 3,734 3,736 3,988 255,832
332117................... Powder metallurgy part 24,250 1,375 5,727 481 479 514 32,828
manufacturing.
332211................... Cutlery and flatware 16,763 952 4,229 333 337 355 22,970
(except precious)
manufacturing.
332212................... Hand and edge tool 106,344 6,041 26,356 2,110 2,118 2,255 145,223
manufacturing.
332213................... Saw blade and handsaw 21,272 1,209 5,090 418 411 451 28,851
manufacturing.
332214................... Kitchen utensil, pot, and 11,442 650 2,886 228 230 243 15,678
pan manufacturing.
332323................... Ornamental and 28,010 1,089 4,808 383 572 406 35,267
architectural metal work.
332439................... Other metal container 44,028 2,502 11,106 876 885 934 60,330
manufacturing.
332510................... Hardware manufacturing..... 131,574 7,476 33,190 2,617 2,646 2,790 180,292
332611................... Spring (heavy gauge) 11,792 670 2,974 235 237 250 16,158
manufacturing.
332612................... Spring (light gauge) 44,511 2,529 11,228 885 895 944 60,992
manufacturing.
332618................... Other fabricated wire 105,686 6,005 26,659 2,102 2,125 2,241 144,819
product manufacturing.
332710................... Machine shops.............. 774,529 44,074 211,043 15,533 16,157 16,423 1,077,759
332812................... Metal coating and allied 2,431,996 94,689 395,206 33,145 48,563 35,337 3,038,935
services.
332911................... Industrial valve 111,334 6,316 25,894 2,197 2,159 2,361 150,261
manufacturing.
332912................... Fluid power valve and hose 103,246 5,863 24,854 2,040 2,021 2,189 140,213
fitting manufacturing.
332913................... Plumbing fixture fitting 33,484 1,901 8,060 661 655 710 45,472
and trim manufacturing.
332919................... Other metal valve and pipe 52,542 2,984 12,648 1,038 1,028 1,114 71,354
fitting manufacturing.
332991................... Ball and roller bearing 79,038 4,488 19,027 1,561 1,547 1,676 107,338
manufacturing.
332996................... Fabricated pipe and pipe 78,951 4,483 19,006 1,560 1,545 1,674 107,219
fitting manufacturing.
332997................... Industrial pattern 15,383 874 3,703 304 301 326 20,891
manufacturing.
332998................... Enameled iron and metal 46,581 2,225 9,304 774 969 831 60,684
sanitary ware
manufacturing.
332999................... All other miscellaneous 209,692 11,915 53,603 4,181 4,256 4,446 288,093
fabricated metal product
manufacturing.
333319................... Other commercial and 154,006 8,741 37,161 3,053 3,046 3,266 209,273
service industry machinery
manufacturing.
333411................... Air purification equipment 43,190 2,453 10,037 847 823 916 58,265
manufacturing.
333412................... Industrial and commercial 30,549 1,735 7,099 599 582 648 41,212
fan and blower
manufacturing.
333414................... Heating equipment (except 59,860 3,399 13,911 1,174 1,141 1,269 80,754
warm air furnaces)
manufacturing.
333511................... Industrial mold 116,034 6,597 30,348 2,317 2,375 2,460 160,131
manufacturing.
333512................... Machine tool (metal cutting 49,965 2,839 12,313 988 985 1,059 68,151
types) manufacturing.
333513................... Machine tool (metal forming 24,850 1,411 6,157 495 500 527 33,940
types) manufacturing.
333514................... Special die and tool, die 167,204 9,513 44,922 3,346 3,458 3,545 231,988
set, jig, and fixture
manufacturing.
333515................... Cutting tool and machine 101,385 5,764 26,517 2,025 2,075 2,150 139,916
tool accessory
manufacturing.
333516................... Rolling mill machinery and 8,897 506 2,327 178 182 189 12,279
equipment manufacturing.
333518................... Other metalworking 36,232 2,060 9,476 724 742 768 50,002
machinery manufacturing.
333612................... Speed changer, industrial 35,962 2,043 8,308 702 674 763 48,452
high-speed drive, and gear
manufacturing.
333613................... Mechanical power 45,422 2,581 10,493 886 852 963 61,197
transmission equipment
manufacturing.
333911................... Pump and pumping equipment 89,460 5,077 21,139 1,767 1,746 1,897 121,086
manufacturing.
333912................... Air and gas compressor 62,241 3,534 14,975 1,230 1,219 1,320 84,518
manufacturing.
333991................... Power-driven handtool 25,377 1,441 6,105 501 497 538 34,459
manufacturing.
333992................... Welding and soldering 46,136 2,622 10,882 904 879 978 62,401
equipment manufacturing.
333993................... Packaging machinery 61,479 3,491 15,004 1,219 1,218 1,304 83,714
manufacturing.
333994................... Industrial process furnace 31,154 1,768 7,694 620 626 661 42,523
and oven manufacturing.
333995................... Fluid power cylinder and 57,771 3,280 13,532 1,137 1,113 1,225 78,057
actuator manufacturing.
333996................... Fluid power pump and motor 39,598 2,247 9,296 782 772 840 53,535
manufacturing.
333997................... Scale and balance (except 10,853 616 2,688 216 218 230 14,822
laboratory) manufacturing.
333999................... All other miscellaneous 152,444 8,657 36,677 3,012 2,985 3,232 207,006
general purpose machinery
manufacturing.
334518................... Watch, clock, and part 6,389 363 1,596 127 129 135 8,740
manufacturing.
335211................... Electric housewares and 11,336 437 1,641 149 203 163 13,928
household fans.
335221................... Household cooking appliance 24,478 944 3,543 321 438 352 30,077
manufacturing.
335222................... Household refrigerator and 26,139 1,009 3,784 343 468 376 32,118
home freezer manufacturing.
335224................... Household laundry equipment 24,839 958 3,596 326 444 357 30,521
manufacturing.
335228................... Other major household 19,551 754 2,830 256 350 281 24,023
appliance manufacturing.
336111................... Automobile manufacturing... 218,635 12,444 49,525 4,203 3,914 4,636 293,357
336112................... Light truck and utility 301,676 17,170 68,335 5,799 5,400 6,397 404,778
vehicle manufacturing.
336120................... Heavy duty truck 93,229 5,303 21,179 1,800 1,692 1,977 125,181
manufacturing.
336211................... Motor vehicle body 138,218 7,849 32,738 2,722 2,674 2,931 187,131
manufacturing.
336212................... Truck trailer manufacturing 93,781 5,325 21,786 1,841 1,791 1,989 126,512
336213................... Motor home manufacturing... 62,548 3,557 14,284 1,212 1,147 1,326 84,073
336311................... Carburetor, piston, piston 30,612 1,739 7,044 598 576 649 41,219
ring, and valve
manufacturing.
336312................... Gasoline engine and engine 192,076 10,910 44,198 3,753 3,616 4,073 258,625
parts manufacturing.
336322................... Other motor vehicle 180,164 10,233 41,457 3,520 3,392 3,820 242,586
electrical and electronic
equipment manufacturing.
336330................... Motor vehicle steering and 114,457 6,504 26,216 2,228 2,128 2,427 153,960
suspension components
(except spring)
manufacturing.
336340................... Motor vehicle brake system 98,118 5,573 22,578 1,917 1,847 2,080 132,114
manufacturing.
336350................... Motor vehicle transmission 243,348 13,832 55,796 4,730 4,510 5,160 327,377
and power train parts
manufacturing.
336370................... Motor vehicle metal 321,190 18,237 73,408 6,282 6,057 6,810 431,985
stamping.
336399................... All other motor vehicle 433,579 24,628 99,769 8,472 8,162 9,194 583,803
parts manufacturing.
336611................... Ship building and repair... 7,868,944 NA 412,708 397,735 26,973 43,259 8,749,619
336612................... Boat building.............. 4,928,083 NA 258,467 249,089 16,892 27,092 5,479,624
336992................... Military armored vehicle, 20,097 1,142 4,786 394 383 426 27,227
tank, and tank component
manufacturing.
337215................... Showcase, partition, 171,563 9,741 41,962 3,405 3,412 3,638 233,720
shelving, and locker
manufacturing.
339114................... Dental equipment and 272,308 15,901 48,135 5,524 4,157 5,930 351,955
supplies manufacturing.
339116................... Dental laboratories........ 103,876 62,183 892,167 21,602 335,984 23,193 1,439,004
339911................... Jewelry (except costume) 260,378 198,421 876,676 69,472 81,414 73,992 1,560,353
manufacturing.
339913................... Jewelers' materials and 53,545 40,804 180,284 14,287 16,742 15,216 320,878
lapidary work
manufacturing.
339914................... Costume jewelry and novelty 54,734 27,779 122,885 9,726 11,337 10,359 236,821
manufacturing.
339950................... Sign manufacturing......... 227,905 9,972 44,660 3,491 5,173 3,718 294,919
423840................... Industrial supplies, 97,304 8,910 60,422 3,149 4,199 3,315 177,299
wholesalers.
482110................... Rail transportation........ 0 327,176 1,738,398 110,229 154,412 121,858 2,452,073
621210................... Dental offices............. 24,957 14,985 251,046 5,286 87,408 5,572 389,256
-------------------------------------------------------------------------------------------------
Total...................... 101,239,507 6,914,225 29,868,808 3,057,076 2,995,900 2,651,079 146,726,595
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).
Table VIII-10--Annualized Compliance Costs for Construction Employers Affected by OSHA's Proposed Silica Standard
[2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Engineering
controls Regulated
NAICS Industry (includes Respirators Exposure Medical Training areas and Total
abrasive assessment surveillance access
blasting) control
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100................... Residential Building $14,610,121 $2,356,507 $1,949,685 $2,031,866 $1,515,047 $825,654 $23,288,881
Construction.
236200................... Nonresidential Building 16,597,147 7,339,394 4,153,899 6,202,842 4,349,517 1,022,115 39,664,913
Construction.
237100................... Utility System Construction 30,877,799 2,808,570 4,458,900 2,386,139 5,245,721 941,034 46,718,162
237200................... Land Subdivision........... 676,046 59,606 128,183 51,327 173,183 22,443 1,110,789
237300................... Highway, Street, and Bridge 16,771,688 2,654,815 3,538,146 2,245,164 4,960,966 637,082 30,807,861
Construction.
237900................... Other Heavy and Civil 4,247,372 430,127 825,247 367,517 1,162,105 131,843 7,164,210
Engineering Construction.
238100................... Foundation, Structure, and 66,484,670 59,427,878 17,345,127 50,179,152 14,435,854 8,034,530 215,907,211
Building Exterior
Contractors.
238200................... Building Equipment 3,165,237 366,310 394,270 316,655 526,555 133,113 4,902,138
Contractors.
238300................... Building Finishing 34,628,392 2,874,918 2,623,763 5,950,757 3,156,004 1,025,405 50,259,239
Contractors.
238900................... Other Specialty Trade 43,159,424 4,044,680 5,878,597 4,854,336 7,251,924 2,815,017 68,003,978
Contractors.
999000................... State and Local Governments 11,361,299 1,641,712 3,257,131 1,426,696 4,493,968 1,157,427 23,338,234
[c].
-------------------------------------------------------------------------------------------------
Total--Construction........ 242,579,193 84,004,516 44,552,948 76,012,451 47,270,844 16,745,663 511,165,616
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).
1. Unit Costs, Other Cost Parameters, and Methodological Assumptions by
Major Provision
Below, OSHA summarizes its methodology for estimating unit and
total costs for the major provisions required under the proposed silica
standard. For a full presentation of the cost analysis, see Chapter V
of the PEA and ERG (2007a, 2007b, 2011, 2013). OSHA invites comment on
all aspects of its preliminary cost analysis.
a. Engineering Controls
Engineering controls include such measures as local exhaust
ventilation, equipment hoods and enclosures, dust suppressants, spray
booths and other forms of wet methods, high efficient particulate air
(HEPA) vacuums, and control rooms.
Following ERG's (2011) methodology, OSHA estimated silica control
costs on a per-worker basis, allowing the costs to be related directly
to the estimates of the number of overexposed workers. OSHA then
multiplied the estimated control cost per worker by the numbers of
overexposed workers for both the proposed PEL of 50 [mu]g/m\3\ and the
alternative PEL of 100 [mu]g/m\3\, introduced for economic analysis
purposes. The numbers of workers needing controls (i.e., workers
overexposed) are based on the exposure profiles for at-risk occupations
developed in the technological feasibility analysis in Chapter IV of
the PEA and estimates of the number of workers employed in these
occupations developed in the industry profile in Chapter III of the
PEA. This worker-based method is necessary because, even though the
Agency has data on the number of firms in each affected industry, on
the occupations and industrial activities with worker exposure to
silica, on exposure profiles of at-risk occupations, and on the costs
of controlling silica exposure for specific industrial activities, OSHA
does not have a way to match up these data at the firm level. Nor does
OSHA have facility-specific data on worker exposure to silica or even
facility-specific data on the level of activity involving worker
exposure to silica. Thus, OSHA could not directly estimate per-
affected-facility costs, but instead, first had to estimate aggregate
compliance costs and then calculate the average per-affected-facility
costs by dividing aggregate costs by the number of affected facilities.
In general, OSHA viewed the extent to which exposure controls are
already in place to be reflected in the distribution of overexposures
among the affected workers. Thus, for example, if 50 percent of workers
in a given occupation are found to be overexposed relative to the
proposed silica PEL, OSHA judged this equivalent to 50 percent of
facilities lacking the relevant exposure controls. The remaining 50
percent of facilities are expected either to have installed the
relevant controls or to engage in activities that do not require that
the exposure controls be in place. OSHA recognizes that some facilities
might have the relevant controls in place but are still unable, for
whatever reason, to achieve the PEL under consideration. ERG's review
of the industrial hygiene literature and other source materials (as
noted in ERG, 2007b), however, suggest that the large majority of
overexposed workers lack relevant controls. Thus, OSHA has generally
assumed that overexposures occur due to the absence of suitable
controls. This assumption results in an overestimate of costs since, in
some cases, employers may merely need to upgrade or better maintain
existing controls or to improve work practices rather than to install
and maintain new controls.
There are two situations in which the proportionality assumption
may oversimplify the estimation of the costs of the needed controls.
First, some facilities may have the relevant controls in place but are
still unable, for whatever reason, to achieve the PEL under
consideration for all employees. ERG's review of the industrial hygiene
literature and other source materials (as noted in ERG, 2007b, pg. 3-
4), however, suggest that the large majority of overexposed workers
lack relevant controls. Thus, OSHA has generally assumed that
overexposures occur due to the absence of suitable controls. This
assumption could, in some cases, result in an overestimate of costs
where employers merely need to upgrade or better maintain existing
controls or to improve work practices rather than to install and
maintain new controls. Second, there may be situations where facilities
do not have the relevant controls in place but nevertheless have only a
fraction of all affected employees above the PEL. If, in such
situations, an employer would have to install all the controls
necessary to meet the PEL, OSHA may have underestimated the control
costs. However, OSHA believes that, in general, employers could come
into compliance by such methods as checking the work practices of the
employee who is above the PEL or installing smaller amounts of LEV at
costs that would be more or less proportional to the costs for all
employees. Nevertheless there may be situations in which a complete set
of controls would be necessary if even one employee in a work area is
above the PEL. OSHA welcomes comment on the extent to which this
approach may yield underestimates or overestimates of costs.
At many workstations, employers must improve ventilation to reduce
silica exposures. Ventilation improvements will take a variety of
forms at different workstations and in different facilities and
industries. The cost of ventilation enhancements generally reflects 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 operation costs for the
heating, ventilation, and air conditioning (HVAC) system for the
facility.
For a number of occupations, the technological feasibility analysis
indicates that, in addition to ventilation, the use of wet methods,
improved housekeeping practices, and enclosure of process equipment are
needed to reduce silica exposures. The degree of incremental
housekeeping depends upon how dusty the operations are and the
applicability of HEPA vacuums or other equipment to the dust problem.
The incremental costs for most such occupations arise due to the labor
required for these additional housekeeping efforts. Because additional
labor for housekeeping will be required on virtually every work shift
by most of the affected occupations, the costs of housekeeping are
substantial. Employers also need to purchase HEPA vacuums and must
incur the ongoing costs of HEPA vacuum filters. To reduce silica
exposures by enclosure of process equipment, such as in the use of
conveyors near production workers in mineral processing, covers can be
particularly effective where silica-containing materials are
transferred (and notable quantities of dust become airborne), or, as
another example, where dust is generated, such as in sawing or grinding
operations.
For construction, ERG (2007a) defined silica dust control measures
for each representative job as specified in Table 1 of the proposed
rule. Generally, these controls involve either a dust collection system
or a water-spray approach (wet method) 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 small hand-pressurized tank to a
large tank for earth drilling operations. Depending on the tool, dust
collection methods entail vacuum equipment, including a vacuum unit and
hoses, and either a dust shroud or an extractor. For example, concrete
grinding operations using hand-held tools require dust shroud adapters
for each tool and a vacuum. The capacity of the vacuum depends on the
type and size of tool being used. Some equipment, such as concrete
floor grinders, comes with a dust collection system and a port for a
vacuum hose. The estimates of control costs for those jobs using dust
collection methods assume that an HEPA filter will be required.
For each job, ERG estimated the annual cost of the appropriate
controls and translated this cost to a daily charge. The unit costs for
control equipment were based on price information collected from
manufacturers and vendors. In some cases, control equipment costs were
based on data on equipment rental charges.
As noted above, included among the engineering controls in OSHA's
cost model are housekeeping and dust-suppression controls in general
industry. For the maritime industry and for construction, abrasive
blasting operations are expected to require the use of wet methods to
control silica dust.
Tables V-3, V-4, V-21, V-22, and V-31 in Chapter V of the PEA and
Tables V-A-1 and V-A-2 in Appendix V-A provide details on the unit
costs, other unit parameters, and methodological assumptions applied by
OSHA to estimate engineering control costs.
b. 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 technical
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).\17\ For the proposed 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\. For this preliminary cost
analysis, OSHA estimates that ten percent of the at-risk workers in
general industry would require respirators, at least occasionally,
after the implementation of engineering controls to achieve compliance
with the proposed PEL of 50 [mu]g/m\3\. For workers in maritime, the
only activity with silica exposures above the proposed PEL of 50 [mu]g/
m\3\ is abrasive blasting, and maritime workers engaged in abrasive
blasting are already required to use respirators under the existing
OSHA ventilation standard (29 CFR 1910.94(a)). Therefore, OSHA has
estimated no additional costs for maritime workers to use respirators
as a result of the proposed silica rule.
---------------------------------------------------------------------------
\17\ 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 [micro]g/m\3\.
---------------------------------------------------------------------------
For construction, employers whose workers receive exposures above
the PEL are assumed to adopt the appropriate task-specific engineering
controls and, where required, respirators prescribed in Table 1 and
under paragraph (g)(1) in the proposed 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) that 56 percent of establishments in the
construction industry are already using respirators that would be in
compliance with the proposed silica rule.
ERG (2013) used respirator cost information from a 2003 OSHA
respirator study to estimate the annual cost of $570 (in 2009 dollars)
for a half-mask, non-powered, air-purifying respirator and $638 per
year (in 2009 dollars) for a full-face non-powered air-purifying
respirator (ERG, 2003). These unit costs reflect the annualized cost of
respirator use, including accessories (e.g., filters), training, fit
testing, and cleaning.
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 two hours for
program revision. Consistent with the findings from the NIOSH
Respiratory Survey (2003), OSHA estimates that 56 percent of
establishments in the construction industry that would require
respirators to achieve compliance with the proposed PEL already have a
respirator program.\18\ 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.
---------------------------------------------------------------------------
\18\ OSHA's derivation of the 56 percent current compliance rate
in construction, in the context of the proposed silica rule, is
described in Chapter V in the PEA.
---------------------------------------------------------------------------
c. Exposure Assessment
Most establishments wishing to perform exposure monitoring will
require the assistance of an outside consulting industrial hygienist
(IH) to obtain accurate results. While some firms might already employ
or train qualified staff, ERG (2007b) judged that the testing protocols
are fairly challenging and that few firms have sufficiently skilled
staff to eliminate the need for outside consultants.
Table V-8 in the PEA 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 $225 to $412 per sample in general
industry and maritime and from $228 to $415 per sample in construction.
For costing purposes, based on ERG (2007b), OSHA estimated that
there are four workers per work area. OSHA interpreted the initial
exposure assessment 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. This may
result in overestimated exposure assessment costs in construction
because OSHA anticipates that many employers, aware that their
operations currently expose their workers to silica levels above the
PEL, will simply choose to comply with Table 1 and avoid the costs of
conducting exposure assessments.
For periodic monitoring, the proposed standard provides employers
an option of assessing employee exposures either under a fixed schedule
(paragraph (d)(3)(i)) or a performance-based schedule (paragraph
(d)(3)(ii)). Under the fixed schedule, the proposed standard requires
semi-annual sampling for exposures at or above the action level and
quarterly sampling for exposures above the 50 [mu]g/m\3\ PEL.
Monitoring must be continued until the employer can demonstrate that
exposures are no longer at or above the action level. 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 proposed rule, whenever
there is a change in the production, process, control equipment,
personnel, or work practices that may result in new or additional
exposures at or above the action level or when the employer has any
reason to suspect that a change may result in new or additional
exposures at or above the action level, the employer must conduct
additional monitoring. Based on ERG (2007a, 2007b), OSHA estimated that
approximately 15 percent of workers whose initial exposure or
subsequent monitoring was at or above the action level would undertake
additional monitoring.
A more detailed description of unit costs, other unit parameters,
and methodological assumptions for exposure assessments is presented in
Chapter V of the PEA.
d. Medical Surveillance
Paragraph (h) of the proposed standard requires an initial health
screening and then triennial periodic screenings for workers exposed
above the proposed PEL of 50 [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. 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-10 in the PEA presents ERG's unit cost data and
modeling assumptions used by OSHA to estimate medical surveillance
costs.
In accordance with the paragraph (h)(2) of the proposed rule, the
initial (baseline) medical examination would consist of (1) a medical
and work history, (2) a physical examination with special emphasis on
the respiratory system, (3) a chest X-ray that is interpreted according
to guidelines of the International Labour Organization, (4) a pulmonary
function test that meets certain criteria and is administered by
spirometry technician with current certification from a NIOSH-approved
spirometry course, (5) testing for latent tuberculosis (TB) infection,
and (6) any other tests deemed appropriate by the physician or licensed
health care professional (PLHCP).
As shown in Table V-10 in the PEA, the estimated unit cost of the
initial health screening for current employees in general industry and
maritime ranges from approximately $378 to $397 and includes direct
medical costs, the opportunity cost of worker time (i.e., lost work
time, evaluated at the worker's 2009 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
Chapter V in the PEA, the estimated unit cost of the initial health
screening for new hires in general industry and maritime ranges from
approximately $380 to $399.
The unit costs of medical surveillance in construction were derived
using identical methods. As shown in Table V-39 of the PEA, the
estimated unit costs of the initial health screening for current
employees in construction range from approximately $389 to $425; the
estimated unit costs of the initial health screening for new hires in
construction range from approximately $394 to $429.
In accordance with paragraph (h)(3) of the proposed rule, the
periodic medical examination (every third year after the initial health
screening) would consist of (1) a medical and work history review and
update, (2) a physical examination with special emphasis on the
respiratory system, (3) a chest X-ray that meets certain standards of
the International Labour Organization, (4) a pulmonary function test
that meets certain criteria and is administered by a spirometry
technician with current certification
from a NIOSH-approved spirometry course, (5) testing for latent TB
infection, if recommended by the PLHCP, and (6) any other tests deemed
appropriate by the PLHCP.
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-10 in the PEA, these triennial
unit costs in general industry and maritime vary from $378 to $397. For
construction, as shown in Table V-39 in the PEA, the triennial unit
costs for periodic health screening vary from roughly $389 to $425. 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.
ERG (2013) estimated a turnover rate of 27.2 percent in general
industry and maritime and 64.0 percent in construction, based on
estimates of the separations rate (layoffs, quits, and retirements)
provided by the Bureau of Labor Statistics (BLS, 2007). However, not
all new hires would require initial medical testing. As specified in
paragraph (h)(2) of the proposed rule, employees who had received a
qualifying medical examination within the previous twelve months would
be exempt from the 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 general
industry, maritime, and construction currently provide some medical
testing to their silica-exposed employees, the Agency doubts that many
provide the comprehensive health screening required under the proposed
rule. Therefore for costing purposes for the proposed rule, OSHA has
assumed no current compliance with the proposed health screening
requirements. OSHA requests information from interested parties on the
current levels and the comprehensiveness of health screening in general
industry, maritime, and construction.
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 $307 for workers in general industry and
maritime and $333 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 PEA for a full discussion of OSHA's analysis
of medical surveillance costs under the proposed standard.
e. Information and Training
As specified in paragraph (i) of the proposed rule and 29 CFR
1910.1200, training is required for all employees in jobs where there
is potential exposure to respirable crystalline silica. In addition,
new hires would require training before starting work. As previously
noted, ERG (2013) provided an estimate of the new-hire rate in general
industry and maritime, based on the BLS-estimated separations rate of
27.2 percent in manufacturing, and an estimate of the new-hire rate in
construction, based on the BLS-estimated separations rate in
construction of 64.0 percent.
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 proposed 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. ERG
(2007b) judged that establishments could purchase sufficient training
materials at an average cost of $2 per worker, encompassing the cost of
handouts, video presentations, and training manuals and exercises. ERG
(2013) included in the cost estimates for training the value of worker
and trainer time as measured by 2009 hourly wage rates (to include
fringe benefits). ERG also developed estimates of average class sizes
as a function of establishment size. For initial training, ERG
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, ERG 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-14 (for
general industry/maritime) and V-43 (for construction) in the PEA.
Based on ERG's work, OSHA estimated the annualized cost (annualized
over 10 years) of initial training per current employee at between
$3.02 and $3.57 and the annual cost of new-hire training at between
$22.50 and $32.72 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 $3.68 and
$4.37 and the annual cost of new hire training at between $27.46 and
$40.39 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. Consistent with some estimates developed by ERG (2007a and
2007b), OSHA estimates that 50 percent of affected establishments
already provide such training. However, some of the training specified
in the proposed rule requires that workers be familiar with the
training and medical surveillance provisions in the rule. OSHA expects
that these training requirements in the proposed rule are not currently
being provided. Therefore, for costing purposes for the proposed rule,
OSHA has estimated that 50 percent of affected establishments currently
provide their workers, and would provide new hires, with training that
would comply with approximately 50 percent of the training
requirements. In other words, OSHA estimates that those 50 percent of
establishments currently providing training on workplace silica hazards
would provide an additional 30 minutes of training to comply with the
proposed rule; the remaining 50 percent of establishments would provide
60 minutes of training to comply with the proposed rule. OSHA also
recognizes that many new hires may have been previously employed in the
same industry, and in some cases by the same establishment, so that
they might have already received (partial) silica training. However,
for purposes of cost estimation, OSHA estimates that all new hires will
receive the full silica training from the new employer. OSHA requests
comments from interested parties on the reasonableness of these
assumptions.
f. Regulated Areas and Access Control
Paragraph (e)(1) of the proposed standard requires that 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, each employer shall establish and implement either a
regulated area in accordance with paragraph (e)(2) or an access control
plan in accordance with paragraph (e)(3). For costing purposes, OSHA
estimated that employers in general industry and maritime would
typically prefer and choose option (e)(2) and would therefore establish
regulated areas when an employee's exposure to airborne concentrations
of silica exceeds, or can reasonably be expected to exceed, the PEL.
OSHA believes that general industry and maritime employers will prefer
this option as it is expected to be the most practical alternative in
fixed worksites. Requirements in the proposed rule for a regulated area
include demarcating the boundaries of the regulated area (as separate
from the rest of the workplace), limiting access to the regulated area,
providing an appropriate respirator to each employee entering the
regulated area, and providing protective clothing as needed in the
regulated area.
Based on ERG (2007b), 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.
Unit costs include planning time (estimated at eight hours of
supervisor time annually); material costs for signs and boundary
markers (annualized at $63.64 in 2009 dollars); and costs of $500
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. In addition, for costing purposes, OSHA estimates that, in
response to the protective work clothing requirements in regulated
areas, ten percent of employees in regulated areas would wear
disposable protective clothing daily, estimated at $5.50 per suit, for
an annual clothing cost of $1,100 per regulated area. Tables V-16 in
the PEA 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 $1,732 annually in general industry and maritime.
For construction, OSHA estimated that some employers would select
the (e)(2) option concerning regulated areas while other employers
would prefer the (e)(3) option concerning written access control plans
whenever an employee's exposure to airborne concentrations of
respirable crystalline silica exceeds, or can reasonably be expected to
exceed, the PEL.
Based on the respirator specifications developed by ERG (2007a) and
shown in Table V-34 in the PEA, ERG derived the full-time-equivalent
number of workers engaged in construction tasks where respirators are
required and estimated the costs of establishing a regulated area for
these workers.
Under the second option for written access control plans, the
employer must include the following elements in the plan: competent
person provisions; notification and demarcation procedures; multi-
employer workplace procedures; provisions for limiting access;
provisions for supplying respirators; and protective clothing
procedures. OSHA anticipates that employers will incur costs for labor,
materials, respiratory protection, and protective clothing to comply
with the proposed access control plan requirements.
Table V-45 in the PEA shows the unit costs and assumptions for
developing costs for regulated areas and for access control plans in
construction. ERG estimated separate development and implementation
costs. ERG judged that developing either a regulated area or an access
control plan would take approximately 4 hours of a supervisor's time.
The time allowed to set up a regulated area or an access control plan
is intended to allow for the communication of access restrictions and
locations at multi-employer worksites. ERG estimated a cost of $116 per
job based on job frequency and the costs for hazard tape and warning
signs (which are reusable). ERG estimated a labor cost of $27 per job
for implementing a written access control plan (covering the time
expended for revision of the access control plan for individual jobs
and communication of the plan). In addition, OSHA estimated that there
would be annual disposable clothing costs of $333 per crew for
employers who implement either regulated areas or the access control
plan option. In addition, OSHA estimated that there would be annual
respirator costs of $60 per crew for employers who implement either
option.
ERG aggregated costs by estimating an average crew size of four in
construction and an average job length of ten days. ERG judged that
employers would choose to establish regulated areas in 75 percent of
the instances where either regulated areas or an access control plan is
required, and that written access control plans would be established
for the remaining 25 percent.
See Chapter V in the PEA for a full discussion of OSHA's analysis
of costs for regulated areas and written access control plans under the
proposed standard.
F. Economic Feasibility Analysis and Regulatory Flexibility
Determination
Chapter VI of the PEA presents OSHA's analysis of the economic
impacts of its proposed 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 proposed rule is economically feasible for all affected
industries, and (2) to determine if the Agency can certify that the
proposed 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 directed 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 proposed
silica rule. The Agency invites comment on any aspect of the methods
and data presented here or in Chapter VI of the PEA.
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 costs of compliance by raising the prices they charge;
under this scenario, 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. 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. Over time, because of rising real
incomes and productivity increases, firms in most industries are able
to ensure an adequate profit. 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, or a combination of the
two, 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 no decline in quantity
demanded. Such a situation 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.
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 proposed standard)
if the industry attempted to maintain production at the same level as
previously. 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 in the industry with hope of an adequate return
on investment, then some or all of the firms in the industry would
close. This scenario is highly unlikely to occur, however, because it
can only arise when there are other products--unaffected by the
proposed rule--that are, in the eyes of their customers, perfect
substitutes for the products the affected establishments make.
A common intermediate case would be a price elasticity of demand of
one (in absolute terms). In this situation, 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 a result, industry
revenues would remain the same, with somewhat lower production, but
with similar profit rates (in most situations where the marginal costs
of production net of regulatory costs would fall as well). 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 American Dental Association v. Secretary of Labor,
is the more typical case.
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 expanding industry, new entry may be delayed until demand equals
supply. In many cases it will be a combination of all three kinds of
reductions in output. Which possibility is most likely depends on the
form that the costs of the regulation take. 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, on the other hand, 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), then reductions
in output are more likely to 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 PEA, 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 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 entries to the industry will not have to
bear.
Capital costs of engineering controls in general industry due to
this standard are relatively small as compared to the total costs,
representing less than 8 percent of total annualized costs and
approximately $362 per year per affected establishment in general
industry.
Some initial costs are fixed in the sense that they will only be
borne by firms in the industry today--these include initial costs for
general training not currently required and initial costs of medical
surveillance. Both of 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 4
percent of total costs and less than $55 per affected establishment.
As a result of these considerations, OSHA expects that it is
somewhat more likely that reductions in industry output will be met by
reductions in output at each affected facility rather than as a result
of plant closures. 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,\19\ particularly since most industries have at
least some ability to raise prices to reflect increased costs and, as
shown in the PEA, normal price variations for products typically exceed
three percent a year. Of course, OSHA recognizes that even when costs
are within this range, there could be unusual circumstances requiring
further analysis.
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\19\ See OSHA's Web page, http://www.osha.gov/dea/lookback.html#Completed, for a link to all completed OSHA lookback
reviews.
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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 has historically considered 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--as shown in the
PEA--normal year-to-year variations in profit rates in an industry can
exceed 40 percent or more. 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 seventy-one percent of profits and thus would be
affordable from profits without 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
markets and otherwise being threatened with short-term insolvency.
In general, because it is usually the case that firms would able to
pass on some or all of the costs of the proposed rule, OSHA 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 proposed 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 this reason,
OSHA also examines the differential costs by size of firm.
b. Regulatory Flexibility Screening Analysis
The Regulatory Flexibility Act (RFA), Pub. L. No. 96-354, 94 Stat.
1164 (codified at 5 U.S.C. 601), requires Federal agencies to consider
the economic impact that a proposed rulemaking will have on small
entities. The RFA states that whenever a Federal agency is required to
publish general notice of proposed rulemaking for any proposed rule,
the agency must prepare and make available for public comment an
initial regulatory flexibility analysis (IRFA). 5 U.S.C. 603(a).
Pursuant to section 605(b), in lieu of an IRFA, the head of an agency
may certify that the proposed 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
proposed rulemaking or at the time of publication of the final rule. 5
U.S.C. 605(b).
To determine if the Assistant Secretary of Labor for OSHA can
certify that the proposed silica rule 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 proposed rule on small entities. These screening tests are similar
in concept to those OSHA developed above to identify minimum threshold
effects for purposes of demonstrating economic feasibility.
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 SBA)
and also to very small entities (defined by OSHA as entities 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. 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 IRFA will not be prepared, only if
OSHA can be highly confident that a proposed rule will not have a
significant economic impact on a substantial number of small entities
in any affected industry.
2. Impacts in General Industry and Maritime
a. Economic Feasibility Screening Analysis: All Establishments
To determine whether the proposed 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 VIII-11, using annualized costs per establishment for the
proposed 50 [mu]g/m\3\ PEL. 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 costs were annualized using a 7
percent discount rate. The annualized cost of the proposed rule for the
average establishment in all of general industry and maritime is
estimated at $2,571 in 2009 dollars. It is clear from Table VIII-11
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 $40,468 for NAICS 327111 (Vitreous china
plumbing fixtures and bathroom accessories manufacturing) and $38,422
for NAICS 327121 (Brick and structural clay manufacturing) to $107 for
NAICS 325510 (Paint and coating manufacturing) and $49 for NAICS 621210
(Dental offices).
Table VIII-11 also shows that, within the general industry and
maritime sectors, there are no industries in which the annualized costs
of the proposed rule exceed 1 percent of annual revenues or 10 percent
of annual profits. NAICS 327123 (Other structural clay product
manufacturing) has both the highest cost impact as a percentage of
revenues, of 0.39 percent, and the highest cost impact as a percentage
of profits, of 8.78 percent. Based on these results, even if the costs
of the proposed rule were 50 percent higher than OSHA has estimated,
the highest cost impact as a percentage of revenues in any affected
industry in general industry or maritime would be less than 0.6
percent. Furthermore, the costs of the proposed rule would have to be
more than 150 percent higher than OSHA has estimated for the cost
impact as a percentage of revenues to equal 1 percent in any affected
industry. For all affected establishments in general industry and
maritime, the estimated annualized cost of the proposed rule is, on
average, equal to 0.02 percent of annual revenue and 0.5 percent of
annual profit.
Table VIII-11--Screening Analysis for Establishments in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Annualized
Total Number of costs per Revenues per Profit rate \a\ Profits per Costs as a Costs as a
NAICS Industry annualized affected affected establishment (percent) establishment percentage of percentage of
costs establishments establishment revenues profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121.................... Asphalt paving mixture and $242,070 1,431 $169 $6,617,887 7.50 $496,420 0.00 0.03
block manufacturing.
324122.................... Asphalt shingle and roofing 3,157,257 224 14,095 34,018,437 7.50 2,551,788 0.04 0.55
materials.
325510.................... Paint and coating 144,281 1,344 107 19,071,850 5.38 1,026,902 0.00 0.01
manufacturing.
327111.................... Vitreous china plumbing 1,659,194 41 40,468 21,226,709 4.41 937,141 0.19 4.32
fixtures & bathroom
accessories manufacturing.
327112.................... Vitreous china, fine 2,601,471 731 3,559 1,203,017 4.41 53,112 0.30 6.70
earthenware, & other
pottery product
manufacturing.
327113.................... Porcelain electrical supply 1,748,297 125 13,986 8,091,258 4.41 357,222 0.17 3.92
mfg.
327121.................... Brick and structural clay 7,838,050 204 38,422 11,440,887 4.41 505,105 0.34 7.61
mfg.
327122.................... Ceramic wall and floor tile 4,132,107 193 21,410 6,706,175 4.41 296,072 0.32 7.23
mfg.
327123.................... Other structural clay 936,699 49 19,116 4,933,258 4.41 217,799 0.39 8.78
product mfg.
327124.................... Clay refractory 482,438 129 3,740 7,872,516 4.41 347,565 0.05 1.08
manufacturing.
327125.................... Nonclay refractory 608,017 105 5,791 14,718,533 4.41 649,810 0.04 0.89
manufacturing.
327211.................... Flat glass manufacturing.... 275,155 83 3,315 43,821,692 3.42 1,499,102 0.01 0.22
327212.................... Other pressed and blown 1,084,706 499 2,174 7,233,509 3.42 247,452 0.03 0.88
glass and glassware
manufacturing.
327213.................... Glass container 756,888 72 10,512 64,453,615 3.42 2,204,903 0.02 0.48
manufacturing.
327320.................... Ready-mixed concrete 16,511,080 6,064 2,723 4,891,554 6.64 324,706 0.06 0.84
manufacturing.
327331.................... Concrete block and brick mfg 4,437,939 951 4,667 5,731,328 6.64 380,451 0.08 1.23
327332.................... Concrete pipe mfg........... 2,747,484 385 7,136 7,899,352 6.64 524,366 0.09 1.36
327390.................... Other concrete product mfg.. 12,900,251 2,281 5,656 4,816,851 6.64 319,747 0.12 1.77
327991.................... Cut stone and stone product 8,600,298 1,943 4,426 1,918,745 5.49 105,320 0.23 4.20
manufacturing.
327992.................... Ground or treated mineral 4,595,006 271 16,956 8,652,610 5.49 474,944 0.20 3.57
and earth manufacturing.
327993.................... Mineral wool manufacturing.. 1,094,552 321 3,410 18,988,835 5.49 1,042,303 0.02 0.33
327999.................... All other misc. nonmetallic 1,966,052 465 4,228 5,803,139 5.49 318,536 0.07 1.33
mineral product mfg.
331111.................... Iron and steel mills........ 424,557 614 692 70,641,523 4.49 3,173,209 0.00 0.02
331112.................... Electrometallurgical 8,577 12 692 49,659,392 4.49 2,230,694 0.00 0.03
ferroalloy product
manufacturing.
331210.................... Iron and steel pipe and tube 84,537 122 694 31,069,797 4.49 1,395,652 0.00 0.05
manufacturing from
purchased steel.
331221.................... Rolled steel shape 42,672 61 694 28,102,003 4.49 1,262,339 0.00 0.05
manufacturing.
331222.................... Steel wire drawing.......... 57,557 83 694 12,904,028 4.49 579,647 0.01 0.12
331314.................... Secondary smelting and 28,757 42 692 29,333,260 4.46 1,309,709 0.00 0.05
alloying of aluminum.
331423.................... Secondary smelting, 4,940 7 695 26,238,546 4.42 1,158,438 0.00 0.06
refining, and alloying of
copper.
331492.................... Secondary smelting, 36,946 53 695 14,759,299 4.42 651,626 0.00 0.11
refining, and alloying of
nonferrous metal (except cu
& al).
331511.................... Iron foundries.............. 15,310,815 527 29,053 19,672,534 4.11 809,290 0.15 3.59
331512.................... Steel investment foundries.. 4,283,138 132 32,448 18,445,040 4.11 758,794 0.18 4.28
331513.................... Steel foundries (except 4,596,837 222 20,706 17,431,292 4.11 717,090 0.12 2.89
investment).
331524.................... Aluminum foundries (except 6,975,150 466 14,968 8,244,396 4.11 339,159 0.18 4.41
die-casting).
331525.................... Copper foundries (except die- 1,636,463 256 6,392 3,103,580 4.11 127,675 0.21 5.01
casting).
331528.................... Other nonferrous foundries 1,232,708 124 9,941 7,040,818 4.11 289,646 0.14 3.43
(except die-casting).
332111.................... Iron and steel forging...... 105,955 150 705 15,231,376 4.71 716,646 0.00 0.10
332112.................... Nonferrous forging.......... 34,982 50 705 28,714,500 4.71 1,351,035 0.00 0.05
332115.................... Crown and closure 12,720 18 697 16,308,872 4.71 767,343 0.00 0.09
manufacturing.
332116.................... Metal stamping.............. 255,832 366 700 6,748,606 4.71 317,526 0.01 0.22
332117.................... Powder metallurgy part 32,828 47 696 9,712,731 4.71 456,990 0.01 0.15
manufacturing.
332211.................... Cutlery and flatware (except 22,970 33 705 9,036,720 5.22 472,045 0.01 0.15
precious) manufacturing.
332212.................... Hand and edge tool 145,223 207 702 5,874,133 5.22 306,843 0.01 0.23
manufacturing.
332213.................... Saw blade and handsaw 28,851 41 698 11,339,439 5.22 592,331 0.01 0.12
manufacturing.
332214.................... Kitchen utensil, pot, and 15,678 22 705 18,620,983 5.22 972,693 0.00 0.07
pan manufacturing.
332323.................... Ornamental and architectural 35,267 54 654 2,777,899 4.70 130,669 0.02 0.50
metal work.
332439.................... Other metal container 60,330 86 705 7,467,745 3.58 267,613 0.01 0.26
manufacturing.
332510.................... Hardware manufacturing...... 180,292 256 705 11,899,309 5.22 621,577 0.01 0.11
332611.................... Spring (heavy gauge) 16,158 23 705 7,764,934 5.22 405,612 0.01 0.17
manufacturing.
332612.................... Spring (light gauge) 60,992 87 705 8,185,896 5.22 427,602 0.01 0.16
manufacturing.
332618.................... Other fabricated wire 144,819 205 705 5,120,358 5.22 267,469 0.01 0.26
product manufacturing.
332710.................... Machine shops............... 1,077,759 1,506 716 1,624,814 5.80 94,209 0.04 0.76
332812.................... Metal coating and allied 3,038,935 2,599 1,169 4,503,334 4.85 218,618 0.03 0.53
services.
332911.................... Industrial valve 150,261 216 694 18,399,215 6.81 1,252,418 0.00 0.06
manufacturing.
332912.................... Fluid power valve and hose 140,213 201 698 22,442,750 6.81 1,527,658 0.00 0.05
fitting manufacturing.
332913.................... Plumbing fixture fitting and 45,472 65 698 24,186,039 6.81 1,646,322 0.00 0.04
trim manufacturing.
332919.................... Other metal valve and pipe 71,354 102 698 15,023,143 6.81 1,022,612 0.00 0.07
fitting manufacturing.
332991.................... Ball and roller bearing 107,338 154 698 36,607,380 6.81 2,491,832 0.00 0.03
manufacturing.
332996.................... Fabricated pipe and pipe 107,219 154 698 6,779,536 6.81 461,477 0.01 0.15
fitting manufacturing.
332997.................... Industrial pattern 20,891 30 698 1,122,819 6.81 76,429 0.06 0.91
manufacturing.
332998.................... Enameled iron and metal 60,684 76 798 14,497,312 6.81 986,819 0.01 0.08
sanitary ware manufacturing.
332999.................... All other miscellaneous 288,093 408 707 4,405,921 6.81 299,907 0.02 0.24
fabricated metal product
manufacturing.
333319.................... Other commercial and service 209,273 299 699 10,042,625 4.86 487,919 0.01 0.14
industry machinery
manufacturing.
333411.................... Air purification equipment 58,265 84 694 7,353,577 4.55 334,804 0.01 0.21
manufacturing.
333412.................... Industrial and commercial 41,212 59 694 12,795,249 4.55 582,559 0.01 0.12
fan and blower
manufacturing.
333414.................... Heating equipment (except 80,754 116 694 11,143,189 4.55 507,342 0.01 0.14
warm air furnaces)
manufacturing.
333511.................... Industrial mold 160,131 226 710 2,481,931 5.29 131,278 0.03 0.54
manufacturing.
333512.................... Machine tool (metal cutting 68,151 97 702 7,371,252 5.29 389,890 0.01 0.18
types) manufacturing.
333513.................... Machine tool (metal forming 33,940 48 702 5,217,940 5.29 275,994 0.01 0.25
types) manufacturing.
333514.................... Special die and tool, die 231,988 325 714 2,378,801 5.29 125,823 0.03 0.57
set, jig, and fixture
manufacturing.
333515.................... Cutting tool and machine 139,916 197 710 3,384,805 5.29 179,034 0.02 0.40
tool accessory
manufacturing.
333516.................... Rolling mill machinery and 12,279 17 710 9,496,141 5.29 502,283 0.01 0.14
equipment manufacturing.
333518.................... Other metalworking machinery 50,002 70 710 7,231,602 5.29 382,504 0.01 0.19
manufacturing.
333612.................... Speed changer, industrial 48,452 70 693 10,727,834 2.63 281,813 0.01 0.25
high-speed drive, and gear
manufacturing.
333613.................... Mechanical power 61,197 88 693 14,983,120 2.63 393,597 0.00 0.18
transmission equipment
manufacturing.
333911.................... Pump and pumping equipment 121,086 174 696 17,078,357 4.58 781,566 0.00 0.09
manufacturing.
333912.................... Air and gas compressor 84,518 121 698 21,079,073 4.58 964,653 0.00 0.07
manufacturing.
333991.................... Power-driven handtool 34,459 49 698 22,078,371 4.58 1,010,384 0.00 0.07
manufacturing.
333992.................... Welding and soldering 62,401 90 696 16,457,683 4.58 753,162 0.00 0.09
equipment manufacturing.
333993.................... Packaging machinery 83,714 120 700 7,374,940 4.58 337,503 0.01 0.21
manufacturing.
333994.................... Industrial process furnace 42,523 61 702 5,584,460 4.58 255,565 0.01 0.27
and oven manufacturing.
333995.................... Fluid power cylinder and 78,057 112 695 13,301,790 4.58 608,737 0.01 0.11
actuator manufacturing.
333996.................... Fluid power pump and motor 53,535 77 695 18,030,122 4.58 825,122 0.00 0.08
manufacturing.
333997.................... Scale and balance (except 14,822 21 702 7,236,854 4.58 331,184 0.01 0.21
laboratory) manufacturing.
333999.................... All other miscellaneous 207,006 296 698 6,033,776 4.58 276,127 0.01 0.25
general purpose machinery
manufacturing.
334518.................... Watch, clock, and part 8,740 12 703 4,924,986 5.94 292,667 0.01 0.24
manufacturing.
335211.................... Electric housewares and 13,928 22 643 22,023,076 4.21 927,874 0.00 0.07
household fans.
335221.................... Household cooking appliance 30,077 47 643 37,936,003 4.21 1,598,316 0.00 0.04
manufacturing.
335222.................... Household refrigerator and 32,118 26 1,235 188,132,355 4.21 7,926,376 0.00 0.02
home freezer manufacturing.
335224.................... Household laundry equipment 30,521 23 1,327 221,491,837 4.21 9,331,875 0.00 0.01
manufacturing.
335228.................... Other major household 24,023 37 643 107,476,620 4.21 4,528,196 0.00 0.01
appliance manufacturing.
336111.................... Automobile manufacturing.... 293,357 181 1,621 512,748,675 2.04 10,462,470 0.00 0.02
336112.................... Light truck and utility 404,778 94 4,306 1,581,224,101 2.04 32,264,364 0.00 0.01
vehicle manufacturing.
336120.................... Heavy duty truck 125,181 95 1,318 194,549,998 2.04 3,969,729 0.00 0.03
manufacturing.
336211.................... Motor vehicle body 187,131 269 696 15,012,805 2.04 306,331 0.00 0.23
manufacturing.
336212.................... Truck trailer manufacturing. 126,512 182 694 17,032,455 2.04 347,542 0.00 0.20
336213.................... Motor home manufacturing.... 84,073 91 924 65,421,325 2.04 1,334,901 0.00 0.07
336311.................... Carburetor, piston, piston 41,219 60 693 21,325,990 2.04 435,150 0.00 0.16
ring, and valve
manufacturing.
336312.................... Gasoline engine and engine 258,625 373 693 36,938,061 2.04 753,709 0.00 0.09
parts manufacturing.
336322.................... Other motor vehicle 242,586 350 693 33,890,776 2.04 691,530 0.00 0.10
electrical and electronic
equipment manufacturing.
336330.................... Motor vehicle steering and 153,960 223 692 42,374,501 2.04 864,638 0.00 0.08
suspension components
(except spring)
manufacturing.
336340.................... Motor vehicle brake system 132,114 191 693 51,498,927 2.04 1,050,819 0.00 0.07
manufacturing.
336350.................... Motor vehicle transmission 327,377 473 692 63,004,961 2.04 1,285,596 0.00 0.05
and power train parts
manufacturing.
336370.................... Motor vehicle metal stamping 431,985 624 692 33,294,026 2.04 679,354 0.00 0.10
336399.................... All other motor vehicle 583,803 843 693 31,304,202 2.04 638,752 0.00 0.11
parts manufacturing.
336611.................... Ship building and repair.... 8,749,619 635 13,779 24,524,381 5.86 1,437,564 0.06 0.96
336612.................... Boat building............... 5,479,624 1,129 4,854 9,474,540 5.86 555,376 0.05 0.87
336992.................... Military armored vehicle, 27,227 39 697 44,887,321 6.31 2,832,073 0.00 0.02
tank, and tank component
manufacturing.
337215.................... Showcase, partition, 233,720 334 701 4,943,560 4.54 224,593 0.01 0.31
shelving, and locker
manufacturing.
339114.................... Dental equipment and 351,955 411 856 4,732,949 10.77 509,695 0.02 0.17
supplies manufacturing.
339116.................... Dental laboratories......... 1,439,004 7,261 198 563,964 10.77 60,734 0.04 0.33
339911.................... Jewelry (except costume) 1,560,353 1,777 878 3,685,009 5.80 213,566 0.02 0.41
manufacturing.
339913.................... Jewelers' materials and 320,878 264 1,215 3,762,284 5.80 218,045 0.03 0.56
lapidary work manufacturing.
339914.................... Costume jewelry and novelty 236,821 590 401 1,353,403 5.80 78,437 0.03 0.51
manufacturing.
339950.................... Sign manufacturing.......... 294,919 496 594 1,872,356 5.80 108,513 0.03 0.55
423840.................... Industrial supplies, 177,299 383 463 1,913,371 3.44 65,736 0.02 0.70
wholesalers.
482110.................... Rail transportation......... 2,452,073 N/A N/A N/A N/A N/A N/A N/A
621210.................... Dental offices.............. 389,256 7,980 49 755,073 7.34 55,429 0.01 0.09
---------------------------------------------------------------------------------------------------------------------------------------
Total....................... 146,726,595 56,121 2,571 ............... ............... ............... ............... ...............
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[\a\] Profit rates were calculated by ERG (2013) as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
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 increase in industry revenues or prices of
one percent or more are common. Examples of year-to-year changes in an
industry that could cause such an increase in revenues or prices
include increases in fuel, material, real estate, or other costs; tax
increases; and shifts in demand.
To demonstrate the normal year-to-year variation in prices for all
the manufacturers in general industry and maritime affected by the
proposed rule, OSHA developed in the PEA year-to-year producer price
indices and year-to-year percentage changes in producer prices, by
industry, for the years 1998-2009. For the combined affected
manufacturing industries in general industry and maritime over the 12-
year period, the average change in producer prices was 3.8 percent a
year. For the three industries in general industry and maritime with
the largest estimated potential annual cost impact as a percentage of
revenue (of approximately 0.35 percent, on average), the average annual
changes in producer prices in these industries over the 12-year period
averaged 3.5 percent.
Based on these data, it is clear that the potential price impacts
of the proposed rule in general industry and maritime are all well
within normal year-to-year variations in prices in those industries.
Thus, OSHA preliminarily concludes that the potential price impacts of
the proposed 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 proposed rule, OSHA presented data in the PEA on year-to-year
profit rates and year-to-year percentage changes in profit rates, by
industry, for the years 2000-2006. For the combined affected
manufacturing industries in general industry and maritime over the 7-
year period, the average change in profit rates was 38.9 percent a
year. For the 7 industries in general industry and maritime with the
largest estimated potential annual cost impacts as a percentage of
profit--ranging from 4 percent to 9 percent--the average annual changes
in profit rates in these industries over the 7-year period averaged 35
percent.
Nevertheless, a longer-term reduction in profit rates in excess of
10 percent a year could be 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 proposed rule in the form of higher prices rather than to bear
the costs of the proposed rule in reduced profits. After all, it defies
common sense to suggest that the demanded 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 significantly
contract in response to a 0.4 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 such that an entire
industry would be significantly affected by small potential 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. Below, OSHA examines
the threat of foreign competition for affected U.S. establishments in
general industry and maritime.
c. International Trade Effects
The magnitude and strength of foreign competition is a critical
factor in determining the ability of firms in the U.S. to pass on (part
or all of) the costs of the proposed rule. If firms are unable to do
so, they would likely absorb the costs of the proposed 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.
In the PEA, OSHA 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), which was prepared specifically to help analyze the
international trade impacts of OSHA's proposed silica rule. A summary
of the PEA results is presented below.
ERG (2007c) focused its analysis on eight of the industries likely
to be most affected by the proposed silica rule and for which import
and export data were available. ERG 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, ERG 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 proposed 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.
ERG'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.
ERG also estimated 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 of
increased imports and the loss of 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 proposed 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 proposed 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 proposed rule for any affected industry would be 0.39 percent of
revenue, this means that the maximum loss to foreign competition in any
affected industry as a result of the proposed rule would be 0.12
percent of industry revenue--which, even for the most affected
industry, 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, OSHA preliminarily
concludes that the annualized costs of the proposed rule are below the
threshold level that could threaten the economic viability of any
industry in general industry or maritime. OSHA further notes that while
there would be additional costs (not attributable to the proposed rule)
for some employers in general industry and maritime to come into
compliance with the current silica standard, these costs would not
affect the Agency's preliminary determination of the economic
feasibility of the proposed rule.
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 and found that the proposed
standard did not threaten the survival of these industries. Now OSHA
wishes to demonstrate that the competitive structure of these
industries would not be significantly altered.
To address this issue, OSHA examined the annualized costs per
affected small entity and per very small entity for each affected
industry in general industry and maritime. Again, OSHA used a 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.
As shown in Table VIII-12 and Table VIII-13, the annualized cost of
the proposed rule is estimated to be $2,103 for the average small
entity in general industry and maritime and $616 for the average very
small entity in general industry and maritime. These tables also show
that there are no industries in general industry and maritime in which
the annualized costs of the proposed rule for small entities or very
small entities exceed one percent of annual revenues. NAICS 327111
(Vitreous china plumbing fixtures & bathroom accessories manufacturing)
has the highest potential cost impact as a percentage of revenues, of
0.61 percent, for small entities, and NAICS 327112 (Vitreous china,
fine earthenware, & other pottery product manufacturing) has the
highest potential cost impact as a percentage of revenues, of 0.75
percent, for very small entities. Small entities in two industries in
general industry and maritime--NAICS 327111 and NAICS 327123 (Other
structural clay product mfg.)--have annualized costs in excess of 10
percent of annual profits (13.91 percent and 10.63 percent,
respectively). NAICS 327112 is the only industry in general industry
and maritime in which the annualized costs of the proposed rule for
very small entities exceed ten percent of annual profits (16.92
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
less 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 and, as verified by OSHA's
lookback reviews, have not been of such a magnitude to lead to their
economic failure.
Table VIII-12--Screening Analysis for Small Entities in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total Number of Annualized cost Costs as a Costs as a
NAICS Industry annualized affected small per affected Revenues per Profit rate [a] Profits per percentage of percentage of
costs entities entity entity (percent) entity revenues profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121.................... Asphalt paving mixture and $140,305 431 $326 $10,428,583 7.50 $782,268 0.00 0.04
block manufacturing.
324122.................... Asphalt shingle and roofing 872,614 106 8,232 14,067,491 7.50 1,055,229 0.06 0.78
materials.
325510.................... Paint and coating 71,718 1,042 69 6,392,803 5.38 344,213 0.00 0.02
manufacturing.
327111.................... Vitreous china plumbing 231,845 25 9,274 1,509,677 4.41 66,651 0.61 13.91
fixtures & bathroom
accessories manufacturing.
327112.................... Vitreous china, fine 1,854,472 717 2,586 693,637 4.41 30,623 0.37 8.45
earthenware, & other
pottery product
manufacturing.
327113.................... Porcelain electrical supply 1,004,480 97 10,355 4,574,464 4.41 201,959 0.23 5.13
mfg.
327121.................... Brick and structural clay 3,062,272 93 32,928 9,265,846 4.41 409,079 0.36 8.05
mfg.
327122.................... Ceramic wall and floor tile 2,189,278 173 12,655 3,236,635 4.41 142,895 0.39 8.86
mfg.
327123.................... Other structural clay 510,811 42 12,162 2,592,114 4.41 114,440 0.47 10.63
product mfg.
327124.................... Clay refractory 212,965 96 2,218 6,026,297 4.41 266,056 0.04 0.83
manufacturing.
327125.................... Nonclay refractory 211,512 68 3,110 7,346,739 4.41 324,352 0.04 0.96
manufacturing.
327211.................... Flat glass manufacturing.... 275,155 56 4,913 64,950,007 3.42 2,221,884 0.01 0.22
327212.................... Other pressed and blown 243,132 228 1,068 935,353 3.42 31,998 0.11 3.34
glass and glassware
manufacturing.
327213.................... Glass container 57,797 24 2,408 10,181,980 3.42 348,317 0.02 0.69
manufacturing.
327320.................... Ready-mixed concrete 10,490,561 2,401 4,369 7,245,974 6.64 480,994 0.06 0.91
manufacturing.
327331.................... Concrete block and brick mfg 2,862,910 567 5,049 6,318,185 6.64 419,407 0.08 1.20
327332.................... Concrete pipe mfg........... 1,441,766 181 7,966 7,852,099 6.64 521,229 0.10 1.53
327390.................... Other concrete product mfg.. 8,826,516 1,876 4,705 3,521,965 6.64 233,791 0.13 2.01
327991.................... Cut stone and stone product 8,028,431 1,874 4,284 1,730,741 5.49 95,001 0.25 4.51
manufacturing.
327992.................... Ground or treated mineral 2,108,649 132 15,975 6,288,188 5.49 345,160 0.25 4.63
and earth manufacturing.
327993.................... Mineral wool manufacturing.. 291,145 175 1,664 6,181,590 5.49 339,309 0.03 0.49
327999.................... All other misc. nonmetallic 1,130,230 326 3,467 4,299,551 5.49 236,004 0.08 1.47
mineral product mfg.
331111.................... Iron and steel mills........ 424,557 523 812 82,895,665 4.49 3,723,664 0.00 0.02
331112.................... Electrometallurgical 4,987 7 692 24,121,503 4.49 1,083,535 0.00 0.06
ferroalloy product
manufacturing.
331210.................... Iron and steel pipe and tube 84,537 94 896 40,090,061 4.49 1,800,841 0.00 0.05
manufacturing from
purchased steel.
331221.................... Rolled steel shape 42,672 54 787 31,848,937 4.49 1,430,651 0.00 0.05
manufacturing.
331222.................... Steel wire drawing.......... 57,557 67 862 16,018,794 4.49 719,562 0.01 0.12
331314.................... Secondary smelting and 15,277 20 777 18,496,524 4.46 825,857 0.00 0.09
alloying of aluminum.
331423.................... Secondary smelting, 4,206 6 722 20,561,614 4.42 907,800 0.00 0.08
refining, and alloying of
copper.
331492.................... Secondary smelting, 18,357 25 741 9,513,728 4.42 420,033 0.01 0.18
refining, and alloying of
nonferrous metal (except cu
& al).
331511.................... Iron foundries.............. 5,312,382 408 13,021 5,865,357 4.11 241,290 0.22 5.40
331512.................... Steel investment foundries.. 1,705,373 101 16,885 8,489,826 4.11 349,255 0.20 4.83
331513.................... Steel foundries (except 2,521,998 192 13,135 11,977,647 4.11 492,738 0.11 2.67
investment).
331524.................... Aluminum foundries (except 4,316,135 412 10,476 4,039,244 4.11 166,167 0.26 6.30
die-casting).
331525.................... Copper foundries (except die- 1,596,288 246 6,489 2,847,376 4.11 117,136 0.23 5.54
casting).
331528.................... Other nonferrous foundries 620,344 112 5,539 2,640,180 4.11 108,612 0.21 5.10
(except die-casting).
332111.................... Iron and steel forging...... 47,376 63 756 8,310,925 4.71 391,034 0.01 0.19
332112.................... Nonferrous forging.......... 13,056 17 760 21,892,338 4.71 1,030,048 0.00 0.07
332115.................... Crown and closure 5,080 7 732 6,697,995 4.71 315,145 0.01 0.23
manufacturing.
332116.................... Metal stamping.............. 212,110 279 759 5,360,428 4.71 252,211 0.01 0.30
332117.................... Powder metallurgy part 17,537 23 762 6,328,522 4.71 297,761 0.01 0.26
manufacturing.
332211.................... Cutlery and flatware (except 10,419 14 738 2,852,835 5.22 149,022 0.03 0.50
precious) manufacturing.
332212.................... Hand and edge tool 87,599 113 772 3,399,782 5.22 177,592 0.02 0.43
manufacturing.
332213.................... Saw blade and handsaw 9,221 12 752 5,385,465 5.22 281,317 0.01 0.27
manufacturing.
332214.................... Kitchen utensil, pot, and 10,475 13 798 10,355,293 5.22 540,923 0.01 0.15
pan manufacturing.
332323.................... Ornamental and architectural 28,608 42 673 2,069,492 4.70 97,346 0.03 0.69
metal work.
332439.................... Other metal container 43,857 56 784 5,260,693 3.58 188,521 0.01 0.42
manufacturing.
332510.................... Hardware manufacturing...... 78,538 104 756 4,442,699 5.22 232,070 0.02 0.33
332611.................... Spring (heavy gauge) 14,071 19 754 6,621,896 5.22 345,904 0.01 0.22
manufacturing.
332612.................... Spring (light gauge) 36,826 44 834 4,500,760 5.22 235,103 0.02 0.35
manufacturing.
332618.................... Other fabricated wire 113,603 148 765 3,440,489 5.22 179,719 0.02 0.43
product manufacturing.
332710.................... Machine shops............... 1,032,483 1,399 738 1,464,380 5.80 84,907 0.05 0.87
332812.................... Metal coating and allied 2,492,357 2,301 1,083 2,904,851 4.85 141,018 0.04 0.77
services.
332911.................... Industrial valve 53,520 71 752 5,841,019 6.81 397,593 0.01 0.19
manufacturing.
332912.................... Fluid power valve and hose 41,712 55 757 6,486,405 6.81 441,524 0.01 0.17
fitting manufacturing.
332913.................... Plumbing fixture fitting and 19,037 25 752 9,183,477 6.81 625,111 0.01 0.12
trim manufacturing.
332919.................... Other metal valve and pipe 30,618 40 764 9,432,914 6.81 642,090 0.01 0.12
fitting manufacturing.
332991.................... Ball and roller bearing 13,624 18 741 5,892,239 6.81 401,079 0.01 0.18
manufacturing.
332996.................... Fabricated pipe and pipe 74,633 99 754 4,377,576 6.81 297,978 0.02 0.25
fitting manufacturing.
332997.................... Industrial pattern 20,767 28 736 1,127,301 6.81 76,734 0.07 0.96
manufacturing.
332998.................... Enameled iron and metal 13,779 22 630 3,195,173 6.81 217,493 0.02 0.29
sanitary ware manufacturing.
332999.................... All other miscellaneous 230,825 311 742 2,904,500 6.81 197,707 0.03 0.38
fabricated metal product
manufacturing.
333319.................... Other commercial and service 123,816 165 750 4,960,861 4.86 241,023 0.02 0.31
industry machinery
manufacturing.
333411.................... Air purification equipment 27,021 36 748 4,449,669 4.55 202,591 0.02 0.37
manufacturing.
333412.................... Industrial and commercial 27,149 34 791 7,928,953 4.55 361,000 0.01 0.22
fan and blower
manufacturing.
333414.................... Heating equipment (except 45,308 61 741 5,667,272 4.55 258,027 0.01 0.29
warm air furnaces)
manufacturing.
333511.................... Industrial mold 143,216 193 743 2,121,298 5.29 112,203 0.04 0.66
manufacturing.
333512.................... Machine tool (metal cutting 44,845 60 746 4,136,962 5.29 218,818 0.02 0.34
types) manufacturing.
333513.................... Machine tool (metal forming 30,365 40 758 4,358,035 5.29 230,511 0.02 0.33
types) manufacturing.
333514.................... Special die and tool, die 203,742 274 743 2,083,166 5.29 110,186 0.04 0.67
set, jig, and fixture
manufacturing.
333515.................... Cutting tool and machine 104,313 140 746 2,082,357 5.29 110,143 0.04 0.68
tool accessory
manufacturing.
333516.................... Rolling mill machinery and 9,604 13 744 8,330,543 5.29 440,630 0.01 0.17
equipment manufacturing.
333518.................... Other metalworking machinery 38,359 50 765 5,680,062 5.29 300,438 0.01 0.25
manufacturing.
333612.................... Speed changer, industrial 25,087 32 777 6,028,137 2.63 158,355 0.01 0.49
high-speed drive, and gear
manufacturing.
333613.................... Mechanical power 26,182 35 754 9,094,798 2.63 238,915 0.01 0.32
transmission equipment
manufacturing.
333911.................... Pump and pumping equipment 41,360 54 762 6,220,799 4.58 284,686 0.01 0.27
manufacturing.
333912.................... Air and gas compressor 23,948 32 758 6,290,845 4.58 287,891 0.01 0.26
manufacturing.
333991.................... Power-driven handtool 9,867 13 732 3,816,319 4.58 174,648 0.02 0.42
manufacturing.
333992.................... Welding and soldering 23,144 31 745 5,635,771 4.58 257,913 0.01 0.29
equipment manufacturing.
333993.................... Packaging machinery 54,872 74 742 4,240,165 4.58 194,045 0.02 0.38
manufacturing.
333994.................... Industrial process furnace 34,418 45 757 4,470,378 4.58 204,580 0.02 0.37
and oven manufacturing.
333995.................... Fluid power cylinder and 32,249 43 756 5,830,077 4.58 266,805 0.01 0.28
actuator manufacturing.
333996.................... Fluid power pump and motor 15,258 20 772 4,401,836 4.58 201,444 0.02 0.38
manufacturing.
333997.................... Scale and balance (except 12,129 16 764 4,987,858 4.58 228,262 0.02 0.33
laboratory) manufacturing.
333999.................... All other miscellaneous 123,384 166 745 3,262,128 4.58 149,287 0.02 0.50
general purpose machinery
manufacturing.
334518.................... Watch, clock, and part 6,646 9 732 2,878,581 5.94 171,059 0.03 0.43
manufacturing.
335211.................... Electric housewares and 3,326 5 643 6,088,365 4.21 256,514 0.01 0.25
household fans.
335221.................... Household cooking appliance 6,521 10 649 10,460,359 4.21 440,715 0.01 0.15
manufacturing.
335222.................... Household refrigerator and 32,118 18 1,784 271,746,735 4.21 11,449,210 0.00 0.02
home freezer manufacturing.
335224.................... Household laundry equipment 30,521 17 1,795 299,665,426 4.21 12,625,478 0.00 0.01
manufacturing.
335228.................... Other major household 1,917 3 671 8,269,046 4.21 348,391 0.01 0.19
appliance manufacturing.
336111.................... Automobile manufacturing.... 293,357 167 1,757 555,733,594 2.04 11,339,563 0.00 0.02
336112.................... Light truck and utility 404,778 63 6,425 2,359,286,755 2.04 48,140,479 0.00 0.01
vehicle manufacturing.
336120.................... Heavy duty truck 125,181 77 1,626 240,029,218 2.04 4,897,718 0.00 0.03
manufacturing.
336211.................... Motor vehicle body 187,131 239 784 16,910,028 2.04 345,044 0.00 0.23
manufacturing.
336212.................... Truck trailer manufacturing. 54,137 72 748 9,018,164 2.04 184,013 0.01 0.41
336213.................... Motor home manufacturing.... 84,073 79 1,064 75,358,742 2.04 1,537,671 0.00 0.07
336311.................... Carburetor, piston, piston 10,269 14 748 2,242,044 2.04 45,748 0.03 1.64
ring, and valve
manufacturing.
336312.................... Gasoline engine and engine 65,767 94 703 4,245,230 2.04 86,623 0.02 0.81
parts manufacturing.
336322.................... Other motor vehicle 71,423 101 706 6,746,386 2.04 137,658 0.01 0.51
electrical and electronic
equipment manufacturing.
336330.................... Motor vehicle steering and 25,492 36 708 7,742,773 2.04 157,989 0.01 0.45
suspension components
(except spring)
manufacturing.
336340.................... Motor vehicle brake system 32,886 46 710 6,554,128 2.04 133,735 0.01 0.53
manufacturing.
336350.................... Motor vehicle transmission 46,869 66 710 6,058,947 2.04 123,631 0.01 0.57
and power train parts
manufacturing.
336370.................... Motor vehicle metal stamping 159,156 201 792 11,477,248 2.04 234,190 0.01 0.34
336399.................... All other motor vehicle 169,401 235 721 6,985,145 2.04 142,530 0.01 0.51
parts manufacturing.
336611.................... Ship building and repair.... 8,749,619 575 15,217 27,083,446 5.86 1,587,570 0.06 0.96
336612.................... Boat building............... 2,612,088 814 3,209 5,304,212 5.86 310,921 0.06 1.03
336992.................... Military armored vehicle, 27,227 32 845 54,437,815 6.31 3,434,642 0.00 0.02
tank, and tank component
manufacturing.
337215.................... Showcase, partition, 176,800 235 751 3,637,716 4.54 165,266 0.02 0.45
shelving, and locker
manufacturing.
339114.................... Dental equipment and 261,393 292 895 2,619,222 10.77 282,066 0.03 0.32
supplies manufacturing.
339116.................... Dental laboratories......... 1,397,271 7,011 199 532,828 10.77 57,381 0.04 0.35
339911.................... Jewelry (except costume) 1,392,054 1,751 795 2,615,940 5.80 151,608 0.03 0.52
manufacturing.
339913.................... Jewelers' materials and 257,285 258 997 2,775,717 5.80 160,868 0.04 0.62
lapidary work manufacturing.
339914.................... Costume jewelry and novelty 242,158 588 412 971,681 5.80 56,314 0.04 0.73
manufacturing.
339950.................... Sign manufacturing.......... 264,810 428 618 1,642,826 5.80 95,211 0.04 0.65
423840.................... Industrial supplies, 143,614 226 636 5,001,467 3.44 171,830 0.01 0.37
wholesalers.
482110.................... Rail transportation......... N/A N/A N/A N/A N/A N/A N/A N/A
621210.................... Dental offices.............. 370,174 7,423 50 663,948 7.34 48,739 0.01 0.10
---------------------------------------------------------------------------------------------------------------------------------------
Total....................... 86,520,059 41,136 2,103
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[a] Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
Table VIII-13--Screening Analysis for Very Small Entities (fewer than 20 employees) in General Industry and Maritime Affected by OSHA's Proposed Silica Standard
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Number of Annualized
Total affected costs per Revenues per Profit rate [a] Profits per Costs as a Costs as a
NAICS Industry annualized entities with affected entity (percent) entity percentage of percentage of
costs <20 employees entities revenues profits
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
324121.................... Asphalt paving mixture and $27,770 260 $107 $4,335,678 7.50 $325,227 0.00 0.03
block manufacturing.
324122.................... Asphalt shingle and roofing 85,253 57 1,496 4,013,780 7.50 301,081 0.04 0.50
materials.
325510.................... Paint and coating 18,910 324 58 1,871,296 5.38 100,758 0.00 0.06
manufacturing.
327111.................... Vitreous china plumbing 26,606 19 1,400 327,368 4.41 14,453 0.43 9.69
fixtures & bathroom
accessories manufacturing.
327112.................... Vitreous china, fine 747,902 645 1,160 155,258 4.41 6,855 0.75 16.92
earthenware, & other
pottery product
manufacturing.
327113.................... Porcelain electrical supply 79,824 57 1,400 601,316 4.41 26,548 0.23 5.28
mfg.
327121.................... Brick and structural clay 76,696 31 2,474 715,098 4.41 31,571 0.35 7.84
mfg.
327122.................... Ceramic wall and floor tile 382,871 136 2,815 807,291 4.41 35,641 0.35 7.90
mfg.
327123.................... Other structural clay 67,176 25 2,687 782,505 4.41 34,547 0.34 7.78
product mfg.
327124.................... Clay refractory 29,861 55 543 1,521,469 4.41 67,172 0.04 0.81
manufacturing.
327125.................... Nonclay refractory 34,061 40 852 1,506,151 4.41 66,495 0.06 1.28
manufacturing.
327211.................... Flat glass manufacturing.... 4,450 4 1,075 905,562 3.42 30,978 0.12 3.47
327212.................... Other pressed and blown 87,895 79 1,107 370,782 3.42 12,684 0.30 8.73
glass and glassware
manufacturing.
327213.................... Glass container 4,798 4 1,107 2,690,032 3.42 92,024 0.04 1.20
manufacturing.
327320.................... Ready-mixed concrete 1,897,131 1,429 1,328 1,922,659 6.64 127,628 0.07 1.04
manufacturing.
327331.................... Concrete block and brick mfg 544,975 339 1,608 1,995,833 6.64 132,485 0.08 1.21
327332.................... Concrete pipe mfg........... 116,670 67 1,741 2,375,117 6.64 157,662 0.07 1.10
327390.................... Other concrete product mfg.. 1,885,496 1,326 1,422 974,563 6.64 64,692 0.15 2.20
327991.................... Cut stone and stone product 2,753,051 1,471 1,872 946,566 5.49 51,957 0.20 3.60
manufacturing.
327992.................... Ground or treated mineral 389,745 78 4,997 1,635,092 5.49 89,751 0.31 5.57
and earth manufacturing.
327993.................... Mineral wool manufacturing.. 48,575 46 1,061 1,398,274 5.49 76,752 0.08 1.38
327999.................... All other misc. nonmetallic 311,859 235 1,327 1,457,181 5.49 79,985 0.09 1.66
mineral product mfg.
331111.................... Iron and steel mills........ 9,342 12 777 4,177,841 4.49 187,668 0.02 0.41
331112.................... Electrometallurgical 0 0 N/A 1,202,610 4.49 54,021 N/A N/A
ferroalloy product
manufacturing.
331210.................... Iron and steel pipe and tube 1,706 2 774 2,113,379 4.49 94,933 0.04 0.82
manufacturing from
purchased steel.
331221.................... Rolled steel shape 1,612 2 774 2,108,498 4.49 94,713 0.04 0.82
manufacturing.
331222.................... Steel wire drawing.......... 2,939 4 774 835,444 4.49 37,528 0.09 2.06
331314.................... Secondary smelting and 1,254 2 774 2,039,338 4.46 91,055 0.04 0.85
alloying of aluminum.
331423.................... Secondary smelting, 0 0 N/A 2,729,146 4.42 120,492 N/A N/A
refining, and alloying of
copper.
331492.................... Secondary smelting, 2,897 4 774 1,546,332 4.42 68,271 0.05 1.13
refining, and alloying of
nonferrous metal (except cu
& al).
331511.................... Iron foundries.............. 330,543 201 1,644 1,031,210 4.11 42,422 0.16 3.88
331512.................... Steel investment foundries.. 47,902 27 1,774 1,831,394 4.11 75,340 0.10 2.35
331513.................... Steel foundries (except 162,670 102 1,595 1,577,667 4.11 64,902 0.10 2.46
investment).
331524.................... Aluminum foundries (except 503,027 235 2,141 874,058 4.11 35,957 0.24 5.95
die-casting).
331525.................... Copper foundries (except die- 370,110 164 2,257 814,575 4.11 33,510 0.28 6.73
casting).
331528.................... Other nonferrous foundries 162,043 77 2,104 837,457 4.11 34,451 0.25 6.11
(except die-casting).
332111.................... Iron and steel forging...... 4,089 5 774 1,175,666 4.71 55,316 0.07 1.40
332112.................... Nonferrous forging.......... 784 1 774 1,431,874 4.71 67,371 0.05 1.15
332115.................... Crown and closure 992 1 774 1,715,882 4.71 80,733 0.05 0.96
manufacturing.
332116.................... Metal stamping.............. 27,154 35 775 1,146,408 4.71 53,939 0.07 1.44
332117.................... Powder metallurgy part 2,072 3 774 1,580,975 4.71 74,386 0.05 1.04
manufacturing.
332211.................... Cutlery and flatware (except 2,217 3 774 391,981 5.22 20,476 0.20 3.78
precious) manufacturing.
332212.................... Hand and edge tool 19,535 25 774 770,858 5.22 40,267 0.10 1.92
manufacturing.
332213.................... Saw blade and handsaw 2,296 3 774 975,698 5.22 50,967 0.08 1.52
manufacturing.
332214.................... Kitchen utensil, pot, and 0 0 N/A 826,410 5.22 43,169 N/A N/A
pan manufacturing.
332323.................... Ornamental and architectural 9,527 14 694 695,970 4.70 32,737 0.10 2.12
metal work.
332439.................... Other metal container 5,279 7 788 1,027,511 3.58 36,822 0.08 2.14
manufacturing.
332510.................... Hardware manufacturing...... 11,863 15 777 776,986 5.22 40,587 0.10 1.92
332611.................... Spring (heavy gauge) 1,927 2 786 1,774,584 5.22 92,698 0.04 0.85
manufacturing.
332612.................... Spring (light gauge) 4,960 6 774 1,085,302 5.22 56,692 0.07 1.36
manufacturing.
332618.................... Other fabricated wire 19,946 26 774 778,870 5.22 40,685 0.10 1.90
product manufacturing.
332710.................... Machine shops............... 416,115 537 774 649,804 5.80 37,677 0.12 2.06
332812.................... Metal coating and allied 613,903 885 694 602,598 4.85 29,254 0.12 2.37
services.
332911.................... Industrial valve 5,886 8 774 1,294,943 6.81 88,146 0.06 0.88
manufacturing.
332912.................... Fluid power valve and hose 4,491 6 774 1,350,501 6.81 91,927 0.06 0.84
fitting manufacturing.
332913.................... Plumbing fixture fitting and 1,505 2 774 811,318 6.81 55,226 0.10 1.40
trim manufacturing.
332919.................... Other metal valve and pipe 2,710 3 781 2,164,960 6.81 147,367 0.04 0.53
fitting manufacturing.
332991.................... Ball and roller bearing 1,132 1 774 1,808,246 6.81 123,086 0.04 0.63
manufacturing.
332996.................... Fabricated pipe and pipe 12,453 16 774 1,237,265 6.81 84,220 0.06 0.92
fitting manufacturing.
332997.................... Industrial pattern 8,917 12 774 503,294 6.81 34,259 0.15 2.26
manufacturing.
332998.................... Enameled iron and metal 3,287 5 690 725,491 6.81 49,384 0.10 1.40
sanitary ware manufacturing.
332999.................... All other miscellaneous 55,981 72 774 933,734 6.81 63,558 0.08 1.22
fabricated metal product
manufacturing.
333319.................... Other commercial and service 19,776 26 774 1,127,993 4.86 54,803 0.07 1.41
industry machinery
manufacturing.
333411.................... Air purification equipment 4,745 6 774 1,152,661 4.55 52,480 0.07 1.47
manufacturing.
333412.................... Industrial and commercial 1,675 2 774 1,454,305 4.55 66,214 0.05 1.17
fan and blower
manufacturing.
333414.................... Heating equipment (except 6,087 8 777 901,560 4.55 41,047 0.09 1.89
warm air furnaces)
manufacturing.
333511.................... Industrial mold 43,738 56 774 716,506 5.29 37,898 0.11 2.04
manufacturing.
333512.................... Machine tool (metal cutting 8,756 11 776 911,891 5.29 48,233 0.09 1.61
types) manufacturing.
333513.................... Machine tool (metal forming 4,666 6 774 1,308,768 5.29 69,225 0.06 1.12
types) manufacturing.
333514.................... Special die and tool, die 65,867 85 774 816,990 5.29 43,213 0.09 1.79
set, jig, and fixture
manufacturing.
333515.................... Cutting tool and machine 31,406 41 775 771,162 5.29 40,789 0.10 1.90
tool accessory
manufacturing.
333516.................... Rolling mill machinery and 1,361 2 774 2,243,812 5.29 118,683 0.03 0.65
equipment manufacturing.
333518.................... Other metalworking machinery 6,766 9 774 965,694 5.29 51,079 0.08 1.51
manufacturing.
333612.................... Speed changer, industrial 3,318 4 774 1,393,898 2.63 36,617 0.06 2.11
high-speed drive, and gear
manufacturing.
333613.................... Mechanical power 3,114 4 774 2,113,156 2.63 55,511 0.04 1.39
transmission equipment
manufacturing.
333911.................... Pump and pumping equipment 7,209 9 774 1,343,868 4.58 61,500 0.06 1.26
manufacturing.
333912.................... Air and gas compressor 4,228 5 774 1,644,664 4.58 75,266 0.05 1.03
manufacturing.
333991.................... Power-driven handtool 2,212 3 774 2,158,268 4.58 98,770 0.04 0.78
manufacturing.
333992.................... Welding and soldering 3,835 5 774 1,331,521 4.58 60,935 0.06 1.27
equipment manufacturing.
333993.................... Packaging machinery 9,742 13 774 809,474 4.58 37,044 0.10 2.09
manufacturing.
333994.................... Industrial process furnace 5,631 7 774 1,324,790 4.58 60,627 0.06 1.28
and oven manufacturing.
333995.................... Fluid power cylinder and 3,955 5 774 916,613 4.58 41,947 0.08 1.84
actuator manufacturing.
333996.................... Fluid power pump and motor 2,670 3 774 1,417,549 4.58 64,872 0.05 1.19
manufacturing.
333997.................... Scale and balance (except 1,947 3 774 1,527,651 4.58 69,911 0.05 1.11
laboratory) manufacturing.
333999.................... All other miscellaneous 32,637 42 774 871,700 4.58 39,892 0.09 1.94
general purpose machinery
manufacturing.
334518.................... Watch, clock, and part 1,322 2 774 586,350 5.94 34,844 0.13 2.22
manufacturing.
335211.................... Electric housewares and 0 0 N/A 847,408 4.21 35,703 N/A N/A
household fans.
335221.................... Household cooking appliance 722 1 698 2,228,319 4.21 93,883 0.03 0.74
manufacturing.
335222.................... Household refrigerator and 0 0 N/A 4,917,513 4.21 207,184 N/A N/A
home freezer manufacturing.
335224.................... Household laundry equipment 0 0 N/A 1,767,776 4.21 74,480 N/A N/A
manufacturing.
335228.................... Other major household 0 0 N/A 1,706,991 4.21 71,919 N/A N/A
appliance manufacturing.
336111.................... Automobile manufacturing.... 2,147 3 774 1,507,110 2.04 30,752 0.05 2.52
336112.................... Light truck and utility 795 1 774 1,089,801 2.04 22,237 0.07 3.48
vehicle manufacturing.
336120.................... Heavy duty truck 943 1 774 4,371,350 2.04 89,196 0.02 0.87
manufacturing.
336211.................... Motor vehicle body 12,371 16 774 1,720,545 2.04 35,107 0.04 2.20
manufacturing.
336212.................... Truck trailer manufacturing. 5,147 7 774 2,706,375 2.04 55,223 0.03 1.40
336213.................... Motor home manufacturing.... 1,193 2 774 2,184,388 2.04 44,572 0.04 1.74
336311.................... Carburetor, piston, piston 1,329 2 774 870,496 2.04 17,762 0.09 4.36
ring, and valve
manufacturing.
336312.................... Gasoline engine and engine 11,683 15 774 867,703 2.04 17,705 0.09 4.37
parts manufacturing.
336322.................... Other motor vehicle 8,618 11 774 1,383,831 2.04 28,237 0.06 2.74
electrical and electronic
equipment manufacturing.
336330.................... Motor vehicle steering and 2,876 4 774 1,543,436 2.04 31,493 0.05 2.46
suspension components
(except spring)
manufacturing.
336340.................... Motor vehicle brake system 2,386 3 774 1,378,684 2.04 28,132 0.06 2.75
manufacturing.
336350.................... Motor vehicle transmission 6,390 8 774 864,746 2.04 17,645 0.09 4.38
and power train parts
manufacturing.
336370.................... Motor vehicle metal stamping 5,759 7 778 1,519,875 2.04 31,013 0.05 2.51
336399.................... All other motor vehicle 16,021 21 774 1,369,097 2.04 27,936 0.06 2.77
parts manufacturing.
336611.................... Ship building and repair.... 212,021 65 3,252 770,896 5.86 45,188 0.42 7.20
336612.................... Boat building............... 391,950 121 3,247 1,101,324 5.86 64,557 0.29 5.03
336992.................... Military armored vehicle, 0 0 N/A 1,145,870 6.31 72,296 N/A N/A
tank, and tank component
manufacturing.
337215.................... Showcase, partition, 28,216 36 774 866,964 4.54 39,387 0.09 1.96
shelving, and locker
manufacturing.
339114.................... Dental equipment and 79,876 87 922 657,192 10.77 70,773 0.14 1.30
supplies manufacturing.
339116.................... Dental laboratories......... 1,040,112 6,664 156 326,740 10.77 35,187 0.05 0.44
339911.................... Jewelry (except costume) 533,353 1,532 348 673,857 5.80 39,054 0.05 0.89
manufacturing.
339913.................... Jewelers' materials and 86,465 218 397 919,422 5.80 53,285 0.04 0.74
lapidary work manufacturing.
339914.................... Costume jewelry and novelty 100,556 368 274 454,292 5.80 26,329 0.06 1.04
manufacturing.
339950.................... Sign manufacturing.......... 89,586 140 639 521,518 5.80 30,225 0.12 2.12
423840.................... Industrial supplies, 50,612 95 531 2,432,392 3.44 83,567 0.02 0.64
wholesalers.
482110.................... Rail transportation......... N/A N/A N/A N/A N/A N/A N/A N/A
621210.................... Dental offices.............. 320,986 6,506 49 562,983 7.34 41,328 0.01 0.12
---------------------------------------------------------------------------------------------------------------------------------------
Total....................... 15,745,425 25,544 616
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the Internal Revenue Service's Corporation Source
Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
As a point of clarification, OSHA would like to draw attention to
industries with captive foundries. There are three industries with
captive foundries whose annualized costs for very small entities
approach five percent of annual profits: NAICS 336311 (Carburetor,
piston ring, and valve manufacturing); NAICS 336312 (Gasoline engine
and engine parts manufacturing); and NAICS 336350 (Motor vehicle
transmission and power train parts manufacturing). For very small
entities in all three of these industries, the annualized costs as a
percentage of annual profits are approximately 4.4 percent. OSHA
believes, however, that very small entities in industries with captive
foundries are unlikely to actually have captive foundries and that the
captive foundries allocated to very small entities in fact belong in
larger entities. This would have the result that the costs as
percentage of profits for these larger entities would be lower than the
4.4 percent reported above. 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 captive foundries, none of the entities with fewer than
20 employees have captive foundries or, if they do, that the impacts
are much smaller than estimated here. OSHA invites comment about
whether and to what extent very small entities have captive foundries
(in industries with captive foundries).
Regardless of whether the cost estimates have been inflated for
very small entities in the three industries with captive foundries
listed above, there are two reasons why OSHA is confident that the
competitive structure of these industries would not be threatened by
adverse competitive conditions for very small entities. First, as shown
in Appendix VI-B of the PEA, very small entities in NAICS 336311, NAICS
336312, and NAICS 336350 account for 3 percent, 2 percent, and 3
percent, respectively, of the total number of establishments in the
industry. Although it is possible that some of these very small
entities could exit the industry in response to the proposed rule,
courts interpreting the OSH Act have historically taken the view that
losing at most 3 percent of the establishments in an industry would
alter the competitive structure of that industry. Second, very small
entities in industries with captive foundries, when confronted with
higher foundry costs as a result of the proposed rule, have the option
of dropping foundry activities, purchasing foundry products and
services from businesses directly in the foundry industry, and focusing
on the main goods and services produced in the industry. This, after
all, is precisely what the rest of the establishments in these
industries do.
e. Regulatory Flexibility Screening Analysis
To determine if the Assistant Secretary of Labor for OSHA can
certify that the proposed silica rule 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 proposed rule 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 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 VIII-12 and Table VIII-13 show that, in general industry and
maritime, the annualized costs of the proposed rule do not exceed one
percent of annual revenues for small entities or for very small
entities in any industry. These tables also show that the annualized
costs of the proposed rule exceed five percent of annual profits for
small entities in 10 industries and for very small entities in 13
industries. OSHA is therefore unable to certify that the proposed rule
will not have a significant economic impact on a substantial number of
small entities in general industry and maritime and must prepare an
Initial Regulatory Flexibility Analysis (IRFA). The IRFA is presented
in Section VIII.I of this preamble.
3. Impacts in Construction
a. Economic Feasibility Screening Analysis: All Establishments
To determine whether the proposed rule's projected 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 chapter 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 VIII-14, using annualized costs per establishment
for the proposed 50 [mu]g/m\3\ PEL. The annualized cost of the proposed
rule for the average establishment in construction, encompassing all
construction industries, is estimated at $1,022 in 2009 dollars. It is
clear from Table VIII-14 that the estimates of the annualized costs per
affected establishment in the 10 construction industries vary widely.
These estimates range from $2,598 for NAICS 237300 (Highway, street,
and bridge construction) and $2,200 for NAICS 237100 (Utility system
construction) to $241 for NAICS 238200 (Building finishing contractors)
and $171 for NAICS 237200 (Land subdivision).
Table VIII-14 shows that in no construction industry do the
annualized costs of the proposed rule exceed one percent of annual
revenues or ten percent of annual profits. NAICS 238100 (Foundation,
structure, and building exterior contractors) has both the highest cost
impact as a percentage of revenues, of 0.13 percent, and the highest
cost impact as a percentage of profits, of 2.97 percent. Based on these
results, even if the costs of the proposed rule were 50 percent higher
than OSHA has estimated, the highest cost impact as a percentage of
revenues in any affected construction industry would be less than 0.2
percent. Furthermore, the costs of the proposed rule would have to be
more than 650 percent higher than OSHA has estimated for the cost
impact as a percentage of revenues to equal 1 percent in any affected
construction industry. For all affected establishments in construction,
the estimated annualized cost of the proposed rule is, on average,
equal to 0.05 percent of annual revenue and 1.0 percent of annual
profit.
Therefore, even though the annualized costs of the proposed rule
incurred by the construction industry as a whole are almost four times
the combined annualized costs incurred by general industry and
maritime, OSHA preliminarily 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 further notes that while there would be
additional costs (not attributable to the proposed rule) for some
employers in construction industries to come into compliance with the
current silica standard, these costs would not affect the Agency's
preliminary determination of the economic feasibility of the proposed
rule.
Below, OSHA provides additional information to further support the
Agency's conclusion that the proposed rule would not threaten the
economic viability of any construction industry.
Table VIII-14--Screening Analysis for Establishments in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
Annualized
Total Affected costs per Revenues per Profit rate Profits per Costs as a Costs as a
NAICS Industry annualized establishments affected establishment \a\ establishment percentage percentage
costs establishment (percent) of revenues of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100......... Residential $23,288,881 55,338 $421 $2,002,532 4.87 $97,456 0.02 0.43
Building
Construction.
236200......... Nonresidential 39,664,913 44,702 887 7,457,045 4.87 362,908 0.01 0.24
Building
Construction.
237100......... Utility System 46,718,162 21,232 2,200 4,912,884 5.36 263,227 0.04 0.84
Construction.
237200......... Land Subdivision.. 1,110,789 6,511 171 2,084,334 11.04 230,214 0.01 0.07
237300......... Highway, Street, 30,807,861 11,860 2,598 8,663,019 5.36 464,156 0.03 0.56
and Bridge
Construction.
237900......... Other Heavy and 7,164,210 5,561 1,288 3,719,070 5.36 199,264 0.03 0.65
Civil Engineering
Construction.
238100......... Foundation, 215,907,211 117,456 1,838 1,425,510 4.34 61,832 0.13 2.97
Structure, and
Building Exterior
Contractors.
238200......... Building Equipment 4,902,138 20,358 241 1,559,425 4.34 67,640 0.02 0.36
Contractors.
238300......... Building Finishing 50,259,239 120,012 419 892,888 4.34 38,729 0.05 1.08
Contractors.
238900......... Other Specialty 68,003,978 74,446 913 1,202,048 4.48 53,826 0.08 1.70
Trade Contractors.
999000......... State and local 23,338,234 N/A N/A N/A N/A N/A N/A N/A
governments \d\.
--------------------------------------------------------------------------------------------------------------------
Total............. 511,165,616 477,476 1,022 ............. ............ ............. ............ ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
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
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 construction affected by the proposed
rule, OSHA presented data in the PEA on year-to-year profit rates and
year-to-year percentage changes in profit rates, by industry, for the
years 2000--2006. For the combined affected manufacturing industries in
general industry and maritime over the 7-year period, the average
change in profit rates was 15.4 percent a year.
What these data indicate is that, even if, theoretically, the
annualized costs of the proposed rule for the most significantly
affected construction industries were completely absorbed in reduced
annual profits, the magnitude of reduced annual profit rates are well
within normal year-to-year variations in profit rates in those
industries and do 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 proposed rule
would be absorbed in lost profits. Given that, as discussed in Chapter
VI of the PEA, 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 PEA are variable costs, there is a
reasonable chance that most firms will see small declines in output
rather than that any but the most extremely marginal firms would close.
Considering the costs of the proposed rule relative to the size of
construction activity in the United States, OSHA preliminarily
concludes that the price and profit impacts of the proposed rule on
construction industries would, in practice, be quite limited. Based on
ERG (2007a), on an annual basis, the cost of the proposed rule would be
equal to approximately 2 percent of the value of affected, silica-
generating construction activity, and silica-generating construction
activity accounts for approximately 4.8 percent of all construction
spending in the U.S. Thus, the annualized cost of the proposed rule
would be equal to approximately 0.1 percent of the value of annual
construction activity in the U.S. On top of that, construction activity
in the U.S. is not subject to any meaningful foreign competition, and
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 sectors: residential building construction, nonresidential
building construction, and nonbuilding construction.
Residential Building Construction: Residential housing 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. In
the long run, it is reasonable to expect the demand for the stock of
housing to reflect similar levels of price sensitivity. Since housing
investments include changes in the existing stock (renovations,
depreciation, etc.) as well as new construction, it is likely that the
price elasticity of demand for new residential construction will be
lower than that for residential construction as a whole.
OSHA judges that many of the silica-generating construction
activities affected by the proposed rule are not widely used in single-
family construction. This assessment is consistent with the cost
estimates that show relatively low impacts for residential building
contractors. 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. But given the costs of the proposed rule relative
to the size of construction spending in the United States, the
resultant price or revenue effects are likely to be so small as to be
barely detectable.
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). 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, OSHA believes, therefore, that the price elasticity of
demand for public investment is 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 (in absolute terms) would be implied. 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.
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 and found that the
proposed standard did not threaten the survival of these construction
industries. Now OSHA wishes to demonstrate that the competitive
structure of these industries would not be significantly altered.
To address this issue, OSHA examined the annualized costs per
affected small and very small entity for each affected construction
industry. Table VIII-15 and Table VIII-16 show that in no construction
industries do the annualized costs of the proposed rule exceed one
percent of annual revenues or ten percent of annual profits either for
small entities or for very small entities. Therefore, OSHA
preliminarily 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.
Table VIII-15--Screening Analysis for Small Entities in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
Annualized
Total Affected costs per Revenues per Profit rate Profits per Costs as a Costs as a
NAICS Industry annualized small affected entities \a\ entities percentage percentage
costs entities entities (percent) of revenues of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100............ Residential Building $18,527,934 44,212 $419 $1,303,262 4.87 $67,420 0.03 0.62
Construction.
236200............ Nonresidential 24,443,185 42,536 575 4,117,755 4.87 200,396 0.01 0.29
Building
Construction.
237100............ Utility System 30,733,201 20,069 1,531 3,248,053 5.36 174,027 0.05 0.88
Construction.
237200............ Land Subdivision.... 546,331 3,036 180 1,215,688 11.04 134,272 0.01 0.13
237300............ Highway, Street, and 13,756,992 10,350 1,329 3,851,971 5.36 206,385 0.03 0.64
Bridge Construction.
237900............ Other Heavy and 5,427,484 5,260 1,032 2,585,858 5.36 138,548 0.04 0.74
Civil Engineering
Construction.
238100............ Foundation, 152,160,159 115,345 1,319 991,258 4.34 42,996 0.13 3.07
Structure, and
Building Exterior
Contractors.
238200............ Building Equipment 3,399,252 13,933 244 1,092,405 4.34 47,383 0.02 0.51
Contractors.
238300............ Building Finishing 36,777,673 87,362 421 737,930 4.34 32,008 0.06 1.32
Contractors.
238900............ Other Specialty 53,432,213 73,291 729 1,006,640 4.48 45,076 0.07 1.62
Trade Contractors.
999000............ State and local 2,995,955 13,482 222 N/A N/A N/A N/A N/A
governments [d].
---------------------------------------------------------------------------------------------------------------
Total............... 342,200,381 428,876 798 ............ ............ ............ ............ ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
Table VIII-16--Screening Analysis for Very Small Entities (Fewer Than 20 Employees) in Construction Affected by OSHA's Proposed Silica Standard
--------------------------------------------------------------------------------------------------------------------------------------------------------
Affected Annualized
Total entities costs per Revenues per Profit rate Profits per Costs as a Costs as a
NAICS Industry annualized with <20 affected entities [a] entities percentage percentage
costs employees entities (percent) of revenues of profits
--------------------------------------------------------------------------------------------------------------------------------------------------------
236100............ Residential Building $13,837,293 32,042 $432 $922,275 4.87 $44,884 0.05 0.96
Construction.
236200............ Nonresidential 10,777,269 35,746 301 1,902,892 4.87 92,607 0.02 0.33
Building
Construction.
237100............ Utility System 8,578,771 16,113 532 991,776 5.36 53,138 0.05 1.00
Construction.
237200............ Land Subdivision.... 546,331 3,036 180 1,215,688 11.04 134,272 0.01 0.13
237300............ Highway, Street, and 4,518,038 8,080 559 1,649,324 5.36 88,369 0.03 0.63
Bridge Construction.
237900............ Other Heavy and 1,650,007 4,436 372 834,051 5.36 44,688 0.04 0.83
Civil Engineering
Construction.
238100............ Foundation, 81,822,550 105,227 778 596,296 4.34 25,864 0.13 3.01
Structure, and
Building Exterior
Contractors.
238200............ Building Equipment 1,839,588 7,283 253 579,724 4.34 25,146 0.04 1.00
Contractors.
238300............ Building Finishing 21,884,973 50,749 431 429,154 4.34 18,615 0.10 2.32
Contractors.
238900............ Other Specialty 30,936,078 68,075 454 600,658 4.48 26,897 0.08 1.69
Trade Contractors.
999000............ State and local N/A N/A N/A N/A N/A N/A N/A N/A
governments [d].
---------------------------------------------------------------------------------------------------------------
Total............... 176,390,899 330,786 533 ............ ............ ............ ............ ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Profit rates were calculated by ERG, 2013, as the average of profit rates for 2000 through 2006, based on balance sheet data reported in the
Internal Revenue Service's Corporation Source Book (IRS, 2007).
Source: U.S. Dept. of Labor, OSHA, Office of Regulatory Analysis, based on ERG (2013).
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. Given the simplicity of many control
measures, however, such as the use of wet methods on machines already
manufactured to accommodate them, 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 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 might exist, small construction firms might 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. Given
the likelihood that small firms can, under most circumstances, call
upon independent training specialists at competitive prices, and the widespread
availability of medical services for health screenings, the advantage
for large firms is, again, expected to be fairly modest.
f. Regulatory Flexibility Screening Analysis
To determine if the Assistant Secretary of Labor for OSHA can
certify that the proposed silica rule 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 proposed rule 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 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 VIII-15 and Table VIII-16 show that in no construction
industries do the annualized costs of the proposed 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 proposed rule will
not have a significant economic impact on a substantial number of small
entities in general industry and maritime and must prepare an Initial
Regulatory Flexibility Analysis (IRFA). The IRFA is presented in
Section VIII.I of this preamble.
4. Employment Impacts on the U.S. Economy
In October 2011, OSHA directed Inforum--a not-for-profit Maryland
corporation (based at the University of Maryland)--to run its
macroeconomic model to estimate the employment impacts of the costs of
the proposed silica rule.\20\ The specific model of the U.S. economy
that Inforum used--called the LIFT 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.\21\
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 GDP, employment, prices, etc.
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\20\ Inforum has over 40 years experience designing and using
macroeconomic models of the United States (and other countries).
\21\ LIFT stands for Long-Term Interindustry Forecasting Tool.
This model combines a dynamic input-output core for 97 productive
sectors with a full macroeconomic model with more than 800
macroeconomic variables. LIFT employs a "bottoms-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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In order to estimate the possible macroeconomic impacts of the
proposed rule, Inforum had to run its model twice: once to establish a
baseline and then again with changes in industry expenditures to
reflect the year-by-year costs of the proposed silica rule as estimated
by OSHA in its Preliminary Economic Analysis (PEA).\22\ The difference
in employment, GDP, etc. between the two runs of the model revealed the
estimated economic impacts of the proposed rule.\23\
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\22\ OSHA worked with Inforum to disaggregate compliance costs
into categories that mapped into specific LIFT production sectors.
Inforum also established a mapping between OSHA's NAICS-based
industries and the LIFT production sectors. OSHA's compliance cost
estimates were based on production and employment levels in affected
industries in 2006 (although the costs were then inflated to 2009
dollars). Therefore, Inforum benchmarked compliance cost estimates
in future years to production and employment conditions in 2006
(that is, compliance costs in a future year were proportionately
adjusted to production and employment changes from 2006 to that
future year). See Inforum (2011) for a discussion of these and other
transformations of OSHA's cost estimates to conform to the
specifications of the LIFT model.
\23\ Because OSHA's analysis of the hydraulic fracturing
industry for the proposed silica rule was not conducted until after
the draft PEA had been completed, OSHA's estimates of the compliance
costs for this industry were not included in Inforum's analysis of
the rule's employment and other macroeconomic impacts on the U.S.
economy. It should be noted that, according to the Agency's
estimates, compliance costs for the hydraulic fracturing industry
represent only about 4 percent of the total compliance costs for all
affected industries.
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OSHA selected 2014 as the starting year for running the Inforum
model under the assumption that that would be the earliest that a final
silica rule could take effect. Inforum ran the model through the year
2023 and reported its annual and cumulative results for the ten-year
period 2014-2023. The most important Inforum result is that the
proposed silica rule cumulatively generates an additional 8,625 job-
years over the period 2014-2023, or an additional 862.5 job-years
annually, on average, over the period (Inforum, 2011).\24\
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\24\ 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.
---------------------------------------------------------------------------
For a fuller discussion of the employment and other macroeconomic
impacts of the silica rule, see Inforum (2011) and Chapter VI of the
PEA for the proposed rule.
G. Benefits and Net Benefits
In this section, OSHA presents a summary of the estimated benefits,
net benefits, and incremental benefits of the proposed silica rule.
This section also contains a sensitivity analysis to show how robust
the estimates of net benefits are to changes in various cost and
benefit parameters. A full explanation of the derivation of the
estimates presented here is provided in Chapter VII of the PEA for the
proposed rule. OSHA invites comments on any aspect of its estimation of
the benefits and net benefits of the proposed rule.
1. Estimation of the Number of Silica-Related Diseases Avoided
OSHA estimated the benefits associated with the proposed PEL of 50
[mu]g/m\3\ and, for economic analysis purposes, with an alternative PEL
of 100 [mu]g/m\3\ for respirable crystalline silica by applying the
dose-response relationship developed in the Agency's quantitative risk
assessment (QRA)--summarized in Section VI of this preamble--to
exposures at or below the current PELs. OSHA determined exposures at or
below the current PELs by first developing an exposure profile
(presented in Chapter IV of the PEA) 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
was previously presented in Section VIII.C of this preamble.
By applying the dose-response relationship to estimates of
exposures at or below the current PELs across industries, it is
possible to project the number of cases of the following diseases
expected to occur in the worker population given exposures at or below
the current PELs (the "baseline"):
Fatal cases of lung cancer,
fatal cases of non-malignant respiratory disease
(including silicosis),
fatal cases of end-stage renal disease, and
cases of silicosis morbidity.
In addition, it is possible to project the number of these cases
that would be avoided under alternative, lower PELs.
As a simplified example, suppose that the risk per worker of a given
health endpoint is 2 in 1,000 at 100 [mu]g/m\3\ and 1 in 1,000 at 50
[mu]g/m\3\ and that there are 100,000 workers currently exposed at 100
[mu]g/m\3\. In this example, the proposed PEL would lower exposures to
50 [mu]g/m\3\, thereby cutting the risk in half and lowering the number
of expected cases in the future from 200 to 100.
The estimated benefits for the proposed silica rule represent the
additional benefits derived from employers achieving full compliance
with the proposed PEL relative to the current PELs. They do not include
benefits associated with current compliance that has already been
achieved with regard to the new requirements or benefits obtained from
future compliance with existing silica requirements, to the extent that
some employers may currently not be fully complying with applicable
regulatory requirements.
The technological feasibility analysis, described earlier in this
section of the preamble, demonstrated the effectiveness of controls in
meeting or exceeding the proposed OSHA PEL. For purposes of estimating
the benefit of reducing the PEL, OSHA has made some simplifying
assumptions. On the one hand, given the lack of background information
on respirator use related to existing exposure data, OSHA used existing
personal exposure measurement information, unadjusted for potential
respirator use.\25\ On the other hand, OSHA assumed that compliance
with the existing and proposed rule would result in reductions in
exposure levels to exactly the existing standard and proposed PEL,
respectively. However, in many cases, indivisibilities in the
application of respirators, as well as certain types of engineering
controls, may cause employers to reduce exposures to some point below
the existing standard or the proposed PEL. This is particularly true in
the construction sector for employers who opt to follow Table 1, which
specifies particular controls.
---------------------------------------------------------------------------
\25\ Based on available data, the Agency estimated the weighted
average for the relevant exposure groups to match up with the
quantitative risk assessment. For the 50-100 [mu]g/m\3\ exposure
range, the Agency estimated an average exposure of 62.5 [mu]g/m\3\.
For the 100-250 [mu]g/m\3\ range, the Agency estimated an average
exposure of 125 [mu]g/m\3\.
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In order to examine the effect of simply changing the PEL, OSHA
compared the number of various kinds of cases that would occur if a
worker were exposed for an entire working life to PELs of 50 [mu]g/m\3\
or 100 [mu]g/m\3\ to the number of cases that would occur at levels of
exposure at or below the current PELs. The number of avoided cases over
a hypothetical working life of exposure for the current population at a
lower PEL is then equal to the difference between the number of cases
at levels of exposure at or below the current PEL for that population
minus the number of cases at the lower PEL. This approach represents a
steady-state comparison based on what would hypothetically happen to
workers who received a specific average level of occupational exposure
to silica during an entire working life. (In order to incorporate the
element of timing to assess the economic value of the health benefits,
OSHA presents a modified approach later in this section.)
Based on OSHA's application of the Steenland et al. (2001) log-
linear and the Attfield and Costello (2004) models, Table VIII-17 shows
the estimated number of avoided fatal lung cancers for PELs of 50
[mu]g/m\3\ and 100 [mu]g/m\3\. At the proposed PEL of 50 [mu]g/m\3\, an
estimated 2,404 to 12,173 lung cancers would be prevented over the
lifetime of the current worker population, with a midpoint estimate of
7,289 fatal cancers prevented. This is the equivalent of between 53 and
271 cases avoided annually, with a midpoint estimate of 162 cases
avoided annually, given a 45-year working life of exposure.
Following Park (2002), as discussed in summary of the Agency's QRA
in Section VI of this preamble, OSHA also estimates that the proposed
PEL of 50 [mu]g/m\3\ would prevent an estimated 16,878 fatalities over
a lifetime from non-malignant respiratory diseases arising from silica
exposure. This is equivalent to 375 fatal cases prevented annually.
Some of these fatalities would be classified as silicosis, but most
would be classified as other pneumoconioses and chronic obstructive
pulmonary disease (COPD), which includes chronic bronchitis and
emphysema.
As also discussed in the summary of the Agency's QRA in Section VI
of this preamble, OSHA finds that workers with large exposures to
silica are at elevated risk of end-stage renal disease (ESRD). Based on
Steenland, Attfield, and Mannetje (2002), OSHA estimates that the
proposed PEL of 50 [mu]g/m\3\ would prevent 6,774 cases of end-stage
renal disease over a working life of exposure, or about 151 cases
annually.
Combining the three major fatal health endpoints--for lung cancer,
non-malignant respiratory diseases, and end-stage renal disease--OSHA
estimates that the proposed PEL would prevent between 26,055 and 35,825
premature fatalities over a lifetime, with a midpoint estimate of
30,940 fatalities prevented. This is the equivalent of between 579 and
796 premature fatalities avoided annually, with a midpoint estimate of
688 premature fatalities avoided annually, given a 45-year working life
of exposure.
In addition, the rule would prevent a large number of cases of
silicosis morbidity. Based on Rosenman et al. (2003), the Agency
estimates that between 2,700 and 5,475 new cases of silicosis, at an
ILO X-ray rating of 1/0 or higher, occur annually at the present PELs
as a result of silica exposure at establishments within OSHA's
jurisdiction. Based on the studies summarized in OSHA's QRA, OSHA
expects that the proposed rule will eliminate the large majority of
these cases.
The Agency has not included the elimination of the less severe
silicosis cases in its estimates of the monetized benefits and net
benefits of the proposed rule. Instead, OSHA separately estimated the
number of silicosis cases reaching the more severe levels of 2/1 and
above. Based on a study by Buchannan et al. (2003) of a cohort of coal
miners (as discussed in the Agency's QRA), OSHA estimates that the
proposed PEL of 50 [mu]g/m\3\ would prevent 71,307 cases of moderate-
to-severe silicosis (registering 2/1 or more, using the ILO method for
assessing severity) over a working life, or about 1,585 cases of
moderate-to-severe silicosis prevented annually.
Note that the Agency based its estimates of reductions in the
number of silica-related diseases over 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. While the Agency is legally obligated to examine the effect of
exposures from a working lifetime of exposure,\26\ in an alternative
analysis purely for informational purposes, the Agency examined, in
Chapter VII of the PEA, the effect of assuming that workers are exposed
for only 25 working years, as opposed to the 45 years assumed in the
main analysis. While all workers are assumed to have less cumulative
exposure under the 25-years-of-exposure assumption, the effective exposed population over time is
proportionately increased. Estimated prevented cases of end-stage renal
disease and silicosis morbidity are lower in the 25-year model, whereas
cases of fatal non-malignant lung disease are higher. In the case of
lung cancer, the effect varies by model, with a lower high-end estimate
(Attfield & Costello, 2004) and a higher low-end estimate (Steenland
et. al., 2001 log-linear model). Overall, however, the 45-year-working-
life assumption yields larger estimates of the number of cases of
avoided fatalities and illnesses than does the 25-years-of-exposure
assumption. For example, the midpoint estimates of the number of
avoided fatalities and illnesses under the proposed PEL of 50 [mu]g/
m\3\ would decline from 688 and 1,585, respectively, under the 45-year-
working-life assumption to 683 and 642, respectively, under the 25-
year-working-life assumption. Note the effect, in this case, of going
from a 45-year-working-life assumption to a 25-year-working-life
assumption would be a 1 percent reduction in the number of avoided
fatalities and a 59 percent reduction in the number of avoided
illnesses. The divergence reflects differences in the mathematical
structure of the risk assessment models that are the basis for these
estimates.\27\
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\26\ 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 it is necessary for
OSHA to reach a determination of significant risk over a working
life, it is a logical extension to estimate what this translates
into in terms of estimated benefits for the affected population over
the same period.
\27\ Technically, this analysis assumes that workers receive 25
years worth of silica exposure, but that they receive it over 45
working years, as is assumed by the risk models in the QRA. It also
accounts for the turnover implied by 25, as opposed to 45, years of
work. However, it is possible that an alternate analysis, which
accounts for the larger number of post-exposure worker-years implied
by workers departing their jobs before the end of their working
lifetime, might find larger health effects for workers receiving 25
years worth of silica exposure.
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OSHA believes that 25 years of worker exposure to respirable
crystalline silica may be a reasonable alternative estimate for
informational purposes. However, to accommodate the possibility that
average worker exposure to silica over a working life may be shorter,
at least in certain industries (see the following paragraph), the
Agency also examined the effect of assuming only 13 years of exposure
for the average worker. The results were broadly similar to the 25
years of exposure--annual fatalities prevented were higher (788), but
illnesses prevented lower (399), with the lower average cumulative
exposure being offset to a substantial degree by a larger exposed
population. The same effect is seen if one assumes only 6.6 years of
cumulative exposure to silica for the average worker: estimated
fatalities rise to 832 cases annually, with 385 cases of silicosis
morbidity. In short, the aggregate estimated benefits of the rule
appear to be relatively insensitive to implicit assumptions of average
occupational tenure. Nonetheless, the Agency is confident that the
typical affected worker sustains an extended period of exposure to
silica.
Even in the construction industry, which has an extremely high rate
of job turnover, the mean job tenure with one's current employer is 6.6
years (BLS, 2010a), and the median age of construction workers in the
U.S. is 41.6 years (BLS, 2010b). OSHA is unaware of any data on job
tenure within an industry, but the Agency would expect job tenure in
the construction industry would be at least twice the job tenure with
one's current employer. Furthermore, many workers may return to the
construction industry after unemployment or work in another industry.
Of course, job tenure is longer in the other industries affected by the
proposed rule.
The proposed rule also contains 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. The
Agency 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. However, the Agency welcomes comment on the likely
magnitude of these currently non-quantified health benefits arising
from the proposed rule and on methods for better measuring 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) and Mannetje et
al. (2002). 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; 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 believes 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, OSHA believes
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.
Another source of uncertainty involves 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 job. Consequently, these models
predict 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, and
are therefore generally applicable to all workers who are exposed to
silica in the various industries. Section VI of this preamble provides
evidence supporting the use of cumulative exposure as the preferred
dose metric. Although the Agency believes that the results of its risk
assessment are broadly relevant to all occupational exposure situations
involving crystalline silica, OSHA acknowledges that differences exist
in the relative toxicity of crystalline silica particles present in
different work settings due to factors such as the presence of mineral
or metal impurities on quartz particle surfaces, whether the particles
have been freshly fractured or are aged, and size distribution of
particles. However, in its preliminary risk assessment, OSHA
preliminarily concludes that the estimates from the studies and
analyses relied upon are fairly representative of a wide range of
workplaces reflecting differences in silica polymorphism, surface
properties, and impurities.
Thus, OSHA has a high degree of confidence in the risk estimates
associated with exposure to the current and proposed PELs. OSHA
acknowledges there is greater uncertainty in the risk estimates for the
proposed action level of 0.025 mg/m\3\ than exists at the current (0.1
mg/m\3\)
and proposed (0.05 mg/m\3\) PELs, particularly given some evidence of a
threshold for silicosis between the proposed PEL and action level.
Given the Agency's findings that controlling exposures below the
proposed PEL would not be technologically feasible for employers, OSHA
believes that a precise estimate of the risk for exposures below the
proposed action level is not necessary to further inform the Agency's
regulatory action. OSHA requests comment on remaining sources of
uncertainties in its risk and benefits estimates that have not been
specifically characterized by OSHA in its analysis.
[GRAPHIC] [TIFF OMITTED] TP12SE13.008
2. Estimating the 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 proposed 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.
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 would
gradually decline as a result of the proposed rule, they would not
reach the steady-state level until 45 years had passed. The reduction
in cases estimated to occur 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. 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 proposed 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 proposed 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 proposed 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.
A more complete discussion of the functioning and results of this
model is presented in Chapter VII of the PEA.
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. As a practical matter,
however, there is no overriding reason for stopping the benefits
analysis at 60 years. An internal analysis by OSHA indicated that, both
in terms of cases prevented, and even with regard to monetized
benefits, particularly when lower discount rates are used, the
estimated benefits of the standard are noticeably larger on an
annualized basis if the analysis extends further into the future. The
Agency welcomes comment on the merit of extending the benefits analysis
beyond the 60 years analyzed in the PEA.
In order to compare costs to benefits, OSHA assumes that economic
conditions remain constant and that annualized costs--and the
underlying costs--will repeat for the entire 60-year time horizon used
for the benefits analysis (as discussed in Chapter V of the PEA). OSHA
welcomes comments on the assumption for both the benefit and cost
analysis that economic conditions remain constant for sixty years. OSHA
is particularly interested in what assumptions and time horizon should
be used instead and why.
3. Monetizing the Benefits
To estimate the monetary value of the reductions in the number of
silica-related fatalities, OSHA relied, as OMB recommends, 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.\28\
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\28\ See, for example, Thaler and Rosen (1976), pp. 265-266. In
addition, see Sunstein (2004), p. 433. "This point demonstrates a
general and badly neglected problem for WTP as it is currently used:
agencies consider people's WTP to eliminate statistical risks,
without taking account of the fact that others--especially family
members and close friends--would also be willing to pay something to
eliminate those risks."
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For estimates using the willingness-to-pay concept, OSHA relied 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 accuracy,
particularly that workers understand the risks to which they are
exposed and that workers have legitimate choices between high- and low-
risk jobs. These assumptions are far from obviously met in actual labor
markets.\29\ A number of academic studies, as summarized in Viscusi &
Aldy (2003), 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.\30\ OSHA has used this approach in many recent
proposed and final rules. Although this approach has been found to
yield results that are less than statistically robust (see, for
example, Hintermann, Alberini and Markandya, 2010), OSHA views these
estimates as the best available, and will use them for its basic
estimates. OSHA welcomes comments on the use of willingness-to-pay
measures and estimates based on compensating wage differentials.
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\29\ On the former assumption, see the discussion in Chapter II
of the PEA on imperfect information. On the latter, see, for
example, the discussion of wage compensation for risk for union
versus nonunion workers in Dorman and Hagstrom (1998).
\30\ 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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Viscusi & 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. This $7 million base number in 2000 dollars yields an estimate
of $8.7 million in 2009 dollars for each fatality avoided.\31\
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\31\ 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) for discussion of
VSLY theory and FDA (2003), pp. 41488-9, for an application of VSLY
in rulemaking. OSHA has not investigated this approach, but welcomes
comment on the issue.
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In addition to the benefits that are based on the implicit value of
fatalities avoided, workers also place an implicit 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 adversely affect
individuals for years or even decades in non-fatal cases, or before
ultimately proving fatal. Because measures of the benefits of avoiding
these illnesses are rare and difficult to find, OSHA has included a
range based on a variety of estimation methods.
Consistent with Buchannan et al. (2003), OSHA estimated the total
number of moderate to severe silicosis cases prevented by the proposed
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, for this preliminary analysis, the Agency
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 2009 dollars) that runs from approximately $62,000 per
case--which reflects estimates developed by Viscusi and Aldy (2003),
based on a series of studies primarily describing simple accidents--to
upwards of $5.1 million per case--which reflects work developed by
Magat, Viscusi & Huber (1996) for non-fatal cancer. The latter number
is based on an approach that places a willingness-to-pay value to avoid
serious illness that is calibrated relative to the value of an avoided
fatality. OSHA (2006) previously used this approach in the Final
Economic Analysis (FEA) supporting its hexavalent chromium final rule,
and EPA (2003) used this approach in its Stage 2 Disinfection and
Disinfection Byproducts Rule concerning regulation of primary drinking
water. Based on Magat, Viscusi & Huber (1996), EPA used studies 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 $5.1 million for an avoided
case of non-fatal cancer is based on this 58.3 percent figure.
The Agency believes this 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.\32\ OSHA therefore is applying these values to those
situations as well.
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\32\ 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. For a fuller discussion of these estimates, see
Chapter VII of the PEA.
---------------------------------------------------------------------------
The Agency is interested in 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. The Monetized Benefits of the Proposed Rule
Table VIII-18 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. (Mid-point estimates of
the undiscounted benefits for each of the first 60 years are provided
in the middle columns of Table VII-A-1 in Appendix VII-A in the PEA.
The estimates by year reach a peak of $11.9 billion in the 60th year.)
As shown, the full range of monetized benefits, undiscounted, for
the proposed PEL of 50 [mu]g/m\3\ runs from $3.2 billion annually, in
the case of the lowest estimate of lung cancer risk and the lowest
valuation for morbidity, up to $10.9 billion annually, for the highest
of both. Note that the value of total benefits is more sensitive to the
valuation of morbidity (ranging from $3.5 billion to $10.3 billion,
given estimates at the midpoint of the lung cancer models) than to the
lung cancer model used (ranging from $6.4 to $7.4 billion, given
estimates at the midpoint of the morbidity valuation).\33\
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\33\ 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 $3.2 billion and $10.9 billion..
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This 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 ($3.4 billion out of $3.5 billion at the case
frequency midpoint), whereas at the high end the majority of the
benefits are related to morbidity ($6.9 billion out of $10.3 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, $3.4
billion in benefits are related to mortality, $1.0 billion are related
to morbidity preceding mortality, and $2.4 billion are related to
morbidity not preceding mortality.
[GRAPHIC] [TIFF OMITTED] TP12SE13.009
b. A Suggested Adjustment to Monetized Benefits
OSHA's estimates of the monetized benefits of the proposed rule are
based on the imputed value of each avoided fatality and each avoided
silica-related disease. To this point, these imputed values have been
assumed to remain constant over time.
OSHA now would like to suggest that an adjustment be made to
monetized benefits to reflect the fact that the imputed value of
avoided fatalities and avoided diseases will tend to increase over
time. Two related factors suggest such an increase in value over time.
First, economic theory suggests that the value of reducing life-
threatening and health-threatening risks will increase as real per capita income
increases. With increased income, an individual's health and life
become more valuable relative to other goods because, unlike other
goods, they are without close substitutes and in relatively fixed or
limited supply. 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) is not subject to the
same type of diminishing returns--implying that an effective way to
increase lifetime utility is by extending one's life and maintaining
one's good health (Hall and Jones, 2007).
Second, real per capita income has broadly been increasing
throughout U.S. history, including recent periods. 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) \34\ 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). More important is the fact that real U.S. per capita income is
projected to grow significantly in future years. For example, the
Annual Energy Outlook (AEO) projections, prepared by the Energy
Information Administration (EIA) in the Department of Energy (DOE),
show an average annual growth rate of per capita income in the United
States of 2.7 percent for the period 2011-2035.\35\ The U.S.
Environmental Protection Agency prepared its economic analysis of the
Clean Air Act using the AEO projections. Although these estimates may
turn out to be somewhat higher or lower than predicted, OSHA believes
that it is reasonable to use the same AEO projections employed by DOE
and EPA, and correspondingly projects that per capita income in the
United States will increase by 2.7 percent a year.
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\34\ 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).
\35\ The EIA used DOE's National Energy Modeling System (NEMS)
to produce the Annual Energy Outlook (AEO) projections (EIA, 2011).
Future per capita GDP was calculated by dividing the projected real
gross domestic product each year by the projected U.S. population
for that year.
---------------------------------------------------------------------------
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 is considering adjusting
its estimates of the benefits of the proposed rule to reflect the
anticipated increase in their value over time. This type of adjustment
has been recognized by OMB (2003), supported by EPA's Science Advisory
Board (EPA, 2000), and applied by EPA.\36\ OSHA proposes to accomplish
this adjustment by modifying benefits in year i from [Bi] to
[Bi * (1 + [eta])\i\], where "[eta]" is the estimated
annual increase in the magnitude of the benefits of the proposed rule.
---------------------------------------------------------------------------
\36\ See, for example, EPA (2003, 2008).
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What remains is to estimate a value for "[eta]" with which to
increase benefits annually in response to annual increases in real per
capita income. Probably the most direct evidence of the value of
"[eta]" 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 "[eta]" 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. Other, more indirect evidence comes from estimates
in the economics literature on the income elasticity for the value of a
statistical life. Viscusi and Aldy (2003) performed a meta-analysis on
50 wage-risk studies and concluded that the point estimates across a
variety of model specifications ranged between 0.5 and 0.6. Applied to
a long-term increase in per capita income of about 2.7 percent a year,
this would suggest a value of "[eta]" of about 1.5 percent a year.
More recently, Kniesner, Viscusi, and Ziliak (2010), 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 "[eta]" of about 3.9 percent a year.
Based on the preceding discussion of these two approaches for
estimating the annual increase in the value of the benefits of the
proposed rule and the fact that, as previously noted, the projected
increase in real per capita income in the United States has flattened
in the most recent 25 year period, OSHA suggests a value of "[eta]"
of approximately 2 percent a year. The Agency invites comment on this
estimate and on estimates of the income elasticity of the value of a
statistical life.
While the Agency believes 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 proposed rule, OSHA is at
this time only offering these adjusted monetized benefits as analytic
alternatives for consideration. Table VIII-19, which follows the
discussion on discounting monetized benefits, shows estimates of the
monetized benefits of the proposed rule (under alternative discount
rates) both with and without this suggested increase in monetized
benefits over time. The Agency invites comment on this suggested
adjustment to monetized benefits.
4. Discounting of Monetized Benefits
As previously noted, the estimated stream of benefits arising from
the proposed 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 \37\ 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.
---------------------------------------------------------------------------
\37\ 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.
---------------------------------------------------------------------------
a. Alternative Discount Rates for Annualizing Benefits
Following OMB (2003) guidelines, OSHA has estimated the annualized
benefits of the proposed rule using separate discount rates of 3
percent and 7 percent. Consistent with the Agency's own practices in
recent proposed and final rules, OSHA has also estimated, for
benchmarking purposes, undiscounted benefits--that is, benefits using a
zero percent discount rate.
The question remains, what is the "appropriate" or "preferred"
discount rate to use to monetize health benefits? The choice of
discount rate is a controversial topic, one that has been the source of
scholarly economic debate for several decades. However, in simplest
terms, the basic choices involve a social opportunity cost of capital
approach or social rate of time preference approach.
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). The rate of time preference approach is intended to measure
the tradeoff between current consumption and future consumption, or in
the context of the proposed 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) .
The 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). 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.
In accordance with OMB Circular A-4 (2003), 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 Agency is
interested in any evidence, theoretical or applied, that would inform
the application of discount rates to the costs and benefits of a
regulation.
b. Summary of Annualized Benefits Under Alternative Discount Rates
Table VIII-19 presents OSHA's estimates of the sum of the
annualized benefits of the proposed rule, using alternative discount
rates at 0, 3, and 7 percent, with a breakout between construction and
general industry, and including the possible alternative of increasing
monetized benefits in response to annual increases in per capita income
over time.
Given that the stream of benefits extends out 60 years, the value
of future benefits is sensitive to the choice of discount rate. As
previously established in Table VIII-18, the undiscounted benefits
range from $3.2 billion to $10.9 billion annually. Using a 7 percent
discount rate, the annualized benefits range from $1.6 billion to $5.4
billion. As can be seen, going from undiscounted benefits to a 7
percent discount rate has the effect of cutting the annualized benefits
of the proposed rule approximately in half.
The Agency's best estimate of the total annualized benefits of the
proposed rule--using a 3 percent discount rate with no adjustment for
the increasing value of health benefits over time-- is between $2.4 and
$8.1 billion, with a mid-point value of $5.3 billion.
As previously mentioned, OSHA has not attempted to estimate the
monetary value of less severe silicosis cases, measured at 1/0 to 1/2
on the ILO scale. The Agency believes the economic loss to individuals
with less severe cases of silicosis could be substantial, insofar as
they may be accompanied by a lifetime of medical surveillance and lung
damage, and potentially may require a change in career. However, many
of these effects can be difficult to isolate and measure in economic
terms, particularly in those cases where there is no obvious effect yet
on physiological function or performance. The Agency invites public
comment on this issue.
[GRAPHIC] [TIFF OMITTED] TP12SE13.010
5. Net Benefits of the Proposed Rule
OSHA has estimated, in Table VIII-20, the net benefits of the
proposed rule (with a PEL of 50 [mu]g/m\3\), based on the benefits and
costs previously presented. Table VIII-20 also provides estimates of
annualized net benefits for an alternative PEL of 100 [mu]g/m\3\. Both
the proposed rule and the alternative rule have the same ancillary
provisions and an action level equal to half of the PEL in both cases.
Table VIII-20 is being provided for informational purposes only. 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 net
benefits has not been used by OSHA as the basis for its decision
concerning the choice of a PEL or of other ancillary requirements for
this proposed silica rule.
Table VIII-20 shows net benefits using alternative discount rates
of 0, 3, and 7 percent for benefits and costs and includes a possible
adjustment to monetized benefits to reflect increases in real per
capita income over time. (An expanded version of Tables VIII-20, with a
breakout of net benefits between construction and general industry/
maritime, is provided in Table VII-B-1 in Appendix B, of the PEA.) OSHA
has relied on a uniform discount rate applied to both costs and
benefits. The Agency is interested in any evidence, theoretical or
applied, that would support or refute the application of differential
discount rates to the costs and benefits of a regulation.
As previously noted, 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
under all scenarios. (Conversely, as noted in Chapter V of the PEA, the
choice of discount rate for annualizing costs has only a very minor
effect on annualized costs.)
Based on the results presented in Table VIII-20, OSHA finds:
While the net benefits of the proposed rule vary
considerably--depending on the choice of discount rate used to
annualize benefits and on whether the benefits being used are in the
high, midpoint, or low range-- benefits exceed costs for the proposed
50 [mu]g/m\3\ PEL in all cases that OSHA considered.
The Agency's best estimate of the net annualized benefits
of the proposed rule--using a uniform discount rate for both benefits
and costs of 3 percent--is between $1.8 billion and $7.5 billion, with
a midpoint value of $4.6 billion.
The alternative of a 100 [mu]g/m\3\ PEL was found to have
lower net benefits under all assumptions, relative to the proposed 50
[mu]g/m\3\ PEL. However, for this alternative PEL, benefits were found
to exceed costs in all cases that OSHA considered.
6. Incremental Benefits of the Proposed 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 proposed 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 proposed
rule.
OSHA provided, in Table VIII-20, estimates of the net benefits of
an alternative 100 [mu]g/m\3\ PEL. The incremental costs, benefits, and
net benefits of going from a 100 [mu]g/m\3\ PEL to a 50 [mu]g/m\3\ PEL
(as well as meeting a 50 [mu]g/m\3\ PEL and then going to a 25 [mu]g/
m\3\ PEL--which the Agency has determined is not feasible), for
alternative discount rates of 3 and 7 percent, are presented in Tables
VIII-21 and VIII-22. Table VIII-21 breaks out costs by provision and
benefits by type of disease and by morbidity/mortality, while Table
VIII-22 breaks out costs and benefits by major industry sector. As
Table VIII-21 shows, at a discount rate of 3 percent, a PEL of 50
[mu]g/m\3\, relative to a PEL of 100 [mu]g/m\3\, imposes additional
costs of $339 million per year; additional benefits of $2.5 billion per
year, and additional net benefits of $2.16 billion per year. The
proposed PEL of 50 [mu]g/m\3\ also has higher net benefits using either
a 3 percent or 7 percent discount rate.
Table VIII-22 continues this incremental analysis but with
breakdowns between construction and general industry/maritime. This
table shows that construction provides most of the incremental costs,
but the incremental benefits are more evenly divided between the two
sectors. Nevertheless, both sectors show strong positive net benefits,
which are greater for the proposed PEL of 50 [mu]g/m\3\ than the
alternative of 100 [mu]g/m\3\.
Tables VIII-21 and VIII-22 demonstrate that, across all discount
rates, there are net benefits to be achieved by lowering exposures to
100 [mu]g/m\3\ and then, in turn, lowering them further to 50 [mu]g/
m\3\. However, the majority of the benefits and costs attributable to
the proposed rule are from the initial effort to lower exposures to 100
[mu]g/m\3\. Consistent with the previous analysis, net benefits decline
across all increments as the discount rate for annualizing benefits
increases.
In addition to examining alternative PELs, OSHA also examined
alternatives to other provisions of the standard. These alternatives
are discussed in Section VIII.H of this preamble.
Table VIII-20--Annual Monetized net Benefits Resulting From a Reduction in Exposure to Crystalline Silica due to
Proposed PEL of 50 [mu]g/m\3\ and Alternative PEL of 100 [mu]g/m\3\
[$Billions]
----------------------------------------------------------------------------------------------------------------
PEL
----------------------------------------------------------------------------- 50 100
Discount rate Range
----------------------------------------------------------------------------------------------------------------
Undiscounted (0%)........................... Low........................... $2.5 $1.2
Midpoint...................... 6.4 3.4
High.......................... 10.2 5.6
Discounted at 3%, with a suggested increased Low........................... 2.3 1.1
in monetized benefits over time. Midpoint...................... 5.8 3.1
High.......................... 9.3 5.1
3%.......................................... Low........................... 1.8 0.8
Midpoint...................... 4.6 2.5
High.......................... 7.5 4.1
Discounted at 7%, with a suggested increased Low........................... 1.3 0.6
in monetized benefits over time. Midpoint...................... 3.6 1.9
High.......................... 5.9 3.3
7%.......................................... Low........................... 1.0 0.5
Midpoint...................... 2.8 1.5
High.......................... 4.7 2.6
----------------------------------------------------------------------------------------------------------------
Source: U.S. Department of Labor, Occupational Safety and Health Administration, Directorate of Standards and
Guidance, Office of Regulatory Analysis.
[GRAPHIC] [TIFF OMITTED] TP12SE13.011
[GRAPHIC] [TIFF OMITTED] TP12SE13.012
7. Sensitivity Analysis
In this section, OSHA presents the results of two different types
of sensitivity analysis to demonstrate how robust the estimates of net
benefits are to changes in various cost and benefit parameters. 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 proposed rule.
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
were doubled, the corresponding labor costs would 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 proposed rule.
The results of the individual sensitivity tests are summarized in Table
VIII-23 and are described in more detail below.
In the first of these sensitivity test where OSHA doubled the
estimated portion of employees in regulated areas requiring disposable
clothing, from 10 to 20 percent, and estimates of other input
parameters remained unchanged, Table VIII-23 shows that the estimated
total costs of compliance would increase by $3.6 million annually, or
by about 0.54 percent, while net benefits would also decline by $3.6
million, from $4,582 million to $4,528 million annually.
In a second sensitivity test, OSHA decreased the estimated current
prevalence of baseline silica training by half, from 50 percent to 25
percent. As shown in Table VIII-23, if OSHA's estimates of other input
parameters remained unchanged, the total estimated costs of compliance
would increase by $7.9 million annually, or by about 1.19 percent,
while net benefits would also decline by $7.9 million annually, from
$4,532 million to $4,524 million annually.
[GRAPHIC] [TIFF OMITTED] TP12SE13.013
In a third sensitivity test, OSHA doubled the estimated travel time
for employees to and from medical exams from 60 to 120 minutes. As
shown in Table VIII-23, if OSHA's estimates of other input parameters
remained unchanged, the total estimated costs of compliance would
increase by $1.4 million annually, or by about 0.22 percent, while net
benefits would also decline by $1.4 million annually, from $4,532
million to $4,530 million annually.
In a fourth sensitivity test, OSHA reduced its estimate of the
number of workers who could be represented by an exposure monitoring
sample from four to three. This would have the effect of increasing
such costs by one-third. As shown in Table VIII-23, if OSHA's estimates
of other input parameters remained unchanged, the total estimated costs
of compliance would increase by $24.8 million annually, or by about
3.77 percent, while net benefits would also decline by $24.8 million
annually, from $4,532 million to $4,507 million annually.
In a fifth sensitivity test, OSHA increased by 50 percent the size
of the productivity penalty arising from the use of engineering
controls in construction. As shown in Table VIII-
23, if OSHA's estimates of other input parameters remained unchanged,
the total estimated costs of compliance would increase by $35.8 million
annually, or by about 5.44 percent (and by 7.0 percent in
construction), while net benefits would also decline by $35.8 million
annually, from $4,532 million to $4,496 million annually.
In a sixth sensitivity test, based on the discussion in Chapter V
of this PEA, OSHA reduced the costs of respirator cartridges to reflect
possible reductions in costs since the original costs per filter were
developed in 2003, and inflated to current dollars. For this purpose,
OSHA reduced respirator filter costs by 40 percent to reflect the
recent lower-quartile estimates of costs relative to the costs used in
OSHA's primary analysis. As shown in Table VIII-23, the total estimated
costs of compliance would be reduced by $21.2 million annually, or by
about 3.23 percent, while net benefits would also increase by $21.2
million annually, from $4,532 million to $4,553 million annually.
In a seventh sensitivity test, OSHA reduced the average crew size
in general industry and maritime subject to a "unit" of engineering
controls from 4 to 3. This would have the effect of increasing such
costs by one-third. As shown in Table VIII-23, if OSHA's estimates of
other input parameters remained unchanged, the total estimated costs of
compliance would increase by $20.8 million annually, or by about 3.16
percent (and by 14.2 percent in general industry and maritime), while
net benefits would also decline by $20.8 million annually, from $4,532
million to $4,511 million annually.
In an eighth sensitivity test, OSHA considered the effect on
annualized net benefits of varying the discount rate for costs and the
discount rate for benefits separately. In particular, the Agency
examined the effect of reducing the discount rate for costs from 7
percent to 3 percent. As indicated in Table VIII-23, this parameter
change lowers the estimated annualized cost by $20.6 million, or 3.13
percent. Total annualized net benefits would increase from $4,532
million annually to $4,552 million annually.
The Agency also performed sensitivity tests on several input
parameters used to estimate the benefits of the proposed rule. In the
first two tests, in an extension of results previously presented in
Table VIII-21, 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 number of different fatal lung
cancer cases prevented, as well as the valuation of individual
morbidity cases. Table VIII-23 presents the effect on annualized net
benefits of using the extreme values of these ranges, the high
mortality count and high morbidity valuation case, and the low
mortality count and low morbidity valuation case. As indicated, using
the high estimate of mortality cases prevented and morbidity valuation,
the benefits rise by 56% to $8.1 billion, yielding net benefits of $7.5
billion. For the low estimate of both cases and valuation, the benefits
decline by 54 percent, to $2.4 billion, yielding net benefits of $1.7
billion.
In the third sensitivity test of benefits, the Agency examined the
effect of raising the discount rate for benefits to 7 percent. The
fourth sensitivity test of benefits examines the effect of adjusting
monetized benefits to reflect increases in real per capita income over
time. The results of these two sensitivity tests were previously shown
in Table VIII-20 and are repeated in Table VIII-23. Raising the
interest rate to 7 percent lowers the estimated benefits by 33 percent,
to $3.5 billion, yielding annualized net benefits of $2.8 billion.
Adjusting monetized benefits to reflect increases in real per capita
income over time raises the benefits by 22 percent, to $6.3 billion,
yielding net benefits of $5.7 billion.
"Break-Even" Analysis
OSHA also performed sensitivity tests on several other parameters
used to estimate the net costs and benefits of the proposed 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 VIII-24.
[GRAPHIC] [TIFF OMITTED] TP12SE13.014
In one break-even test on cost estimates, OSHA examined how much
costs would have to increase in order for costs to equal benefits. As
shown in Table VIII-24, this point would be reached if costs increased
by $4.5 billion, or 689 percent.
In a second test, looking specifically at the estimated engineering
control costs, the Agency found that these costs would need to increase
by $4.5 billion, or 1,318 percent, for costs to equal 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 $1.9 billion, while the
estimated costs are $0.6 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.
The Agency, 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 VIII-24, an 87 percent reduction in the monetized value
of all avoided illnesses and fatalities would be necessary for costs to
equal benefits, reducing the estimated value to $1.1 million per life
saved, and an equivalent percentage reduction to about $0.3 million per
illness prevented.
In a fourth break-even sensitivity test, OSHA estimated how many
fewer silica-related fatalities and illnesses would be required for
benefits to equal costs. Paralleling the previous discussion,
eliminating either the prevented mortality or morbidity cases alone
would be insufficient to lower benefits to the break-even point. The
Agency therefore examined them as a group. As shown in Table VIII-24, a
reduction of 87 percent, for both simultaneously, is required to reach
the break-even point--600 fewer mortality cases prevented annually, and
1,384 fewer morbidity cases prevented annually.
Taking into account both types of sensitivity analysis the Agency
performed on its point estimates of the annualized costs and annualized
benefits of the proposed rule, the results demonstrate that net
benefits would be positive in all plausible cases tested. In
particular, this finding would hold even with relatively large
variations in individual input parameters. Alternately, one would have
to imagine extremely large changes in costs or benefits for the rule to
fail to produce net benefits. OSHA concludes that its finding of
significant net benefits resulting from the proposed rule is a robust
one.
OSHA welcomes input from the public regarding all aspects of this
sensitivity analysis, including any data or information regarding the
accuracy of the preliminary estimates of compliance costs and benefits
and how the estimates of costs and benefits may be affected by varying
assumptions and methodological approaches.
H. Regulatory Alternatives
This section discusses various regulatory alternatives to the
proposed OSHA silica standard. OSHA believes that this presentation of
regulatory alternatives serves two important functions. The first is to
explore the possibility of less costly ways (than the proposed rule) to
provide an adequate level of worker protection from exposure to
respirable crystalline silica. The second is tied to the Agency's
statutory requirement, which underlies the proposed rule, to reduce
significant risk to the extent feasible. If, based on evidence
presented during notice and comment, OSHA is unable to justify its
preliminary findings of significant risk and feasibility as presented
in this preamble to the proposed rule, the Agency must then consider
regulatory alternatives that do satisfy its statutory obligations.
Each regulatory alternative presented here is described and
analyzed relative to the proposed rule. Where appropriate, the Agency
notes whether the regulatory alternative, to be a legitimate candidate
for OSHA consideration, requires evidence contrary to the Agency's
findings of significant risk and feasibility. To facilitate comment,
the regulatory alternatives have been organized into four categories:
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2)
regulatory alternatives that affect proposed ancillary provisions; (3)
a regulatory alternative that would modify the proposed methods of
compliance; and (4) regulatory alternatives concerning when different
provisions of the proposed rule would take effect.
Alternative PELs
OSHA is proposing a new PEL for respirable crystalline silica of 50
[mu]g/m\3\ for all industry sectors covered by the rule. OSHA's
proposal 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 of this preamble, 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 current PELs. These
analyses are presented in a background document entitled "Respirable
Crystalline Silica--Health Effects Literature Review and Preliminary
Quantitative Risk Assessment" and are summarized in this preamble in
Section V, Health Effects Summary, and Section VI, Summary of OSHA's
Preliminary Quantitative Risk Assessment, respectively. The available
evidence indicates that employees exposed to respirable crystalline
silica well below the current PELs are 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. As discussed in Section VII, Significance of
Risk, in this preamble, OSHA preliminarily finds that worker exposure
to respirable crystalline silica constitutes a significant risk and
that the proposed 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 proposed rule is presented in the Preliminary
Economic Analysis and Initial Regulatory Flexibility Analysis (PEA),
and is summarized in this section (Section VIII) of this preamble. For
general industry and maritime, OSHA has preliminarily concluded that
the proposed PEL of 50 [mu]g/m\3\ is technologically feasible for all
affected industries. For construction, OSHA has preliminarily
determined that the proposed PEL of 50 [mu]g/m\3\ is feasible in 10 out
of 12 of the affected activities. Thus, OSHA preliminarily concludes
that engineering and work practices will be sufficient to reduce and
maintain silica exposures to the proposed PEL of 50 [mu]g/m\3\ or below
in most operations most of the time in the affected industries. For
those few operations within an industry or activity where the proposed
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
proposed PEL.
OSHA developed quantitative estimates of the compliance costs of
the proposed 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
preliminarily concluded that compliance with the
requirements of the proposed 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 proposed rule. Under Regulatory Alternative 1, the
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for
all industry sectors covered by the rule, and the action level would be
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action
level at one-half of the PEL). Under Regulatory Alternative 2,
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\
for all industry sectors covered by the rule, while the action level
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately
measuring exposure levels below 25 [mu]g/m\3\).
Tables VIII-25 and VIII-26 present, for informational purposes, the
estimated costs, benefits, and net benefits of the proposed rule under
the proposed 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 incremental benefits, and the incremental net benefits of
going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of 50 [mu]g/m\3\
and then of going from the proposed PEL of 50 [mu]g/m\3\ to a PEL of 25
[mu]g/m\3\. Table VIII-25 breaks out costs by provision and benefits by
type of disease and by morbidity/mortality, while Table VIII-26 breaks
out costs and benefits by major industry sector.
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As Tables VIII-25 and VIII-26 show, going from a PEL of 100 [mu]g/
m\3\ to a PEL of 50 [mu]g/m\3\ would prevent, annually, an additional
357 silica-related fatalities and an additional 632 cases of silicosis.
Based on its preliminary findings that
the proposed PEL of 50 [mu]g/m\3\ significantly reduces worker risk
from silica exposure (as demonstrated by the number of silica-related
fatalities and silicosis cases avoided) and is both technologically and
economically feasible, OSHA cannot propose a PEL of 100 [mu]g/m\3\
(Regulatory Alternative 1) without violating its statutory
obligations under the OSH Act. However, the Agency will consider
evidence that challenges its preliminary findings.
As previously noted, Tables VIII-25 and VIII-26 also show the costs
and 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 proposed 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 proposed rule).
As shown in Tables VIII-25 and VIII-26, going from a PEL of 50
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ would prevent, annually, an
additional 335 silica-related fatalities and an additional 186 cases of
silicosis. These estimates support OSHA's preliminarily finding that
there is significant risk remaining at the proposed PEL of 50 [mu]g/
m\3\. However, the Agency has preliminarily determined that a PEL of 25
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically
feasible, and for that reason, cannot propose it without violating its
statutory obligations under the OSH Act.
Regulatory Alternatives That Affect Ancillary Provisions
The proposed rule contains several ancillary provisions (provisions
other the PEL), including requirements for exposure assessment, medical
surveillance, silica training, and regulated areas or access control.
As shown in Table VIII-25, these ancillary provisions represent
approximately $223 million (or about 34 percent) of the total
annualized costs of the rule of $658 million (using a 7 percent
discount rate). The two most expensive of the ancillary provisions are
the requirements for medical surveillance, with annualized costs of $79
million, and the requirements for exposure monitoring, with annualized
costs of $74 million.
As proposed, the requirements for exposure assessment are triggered
by the action level. As described in this preamble, OSHA has defined
the action level for the proposed standard as an airborne concentration
of respirable crystalline silica of 25 [mu]g/m\3\ calculated as an
eight-hour time-weighted average. In this proposal, as in other
standards, the action level has been set at one-half of the PEL.
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 PEL on days when no exposure measurements are made. Even when all
measurements on a given day may fall below the PEL (but are above the
action level), there is some chance that on another day, when exposures
are not measured, the employee's actual exposure may exceed the PEL.
When exposure measurements are above the action level, the employer
cannot be reasonably confident 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.
The action level is also intended to encourage employers to lower
exposure levels in order to avoid the costs associated with the
exposure assessment provisions. Some employers would be able to reduce
exposures below the action level in all work areas, and other employers
in some work areas. As exposures are lowered, the risk of adverse
health effects among workers decreases.
OSHA's preliminary risk assessment indicates that significant risk
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing
significant risk, the decision in the Asbestos case (Bldg. and
Constr.Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (DC Cir.
1988)) indicated that OSHA should use its legal authority to impose
additional requirements on employers to further reduce risk when those
requirements will result in a greater than de minimis incremental
benefit to workers' health. OSHA's preliminary conclusion is that the
requirements triggered by the action level will result in a very real
and necessary, but non-quantifiable, further reduction in risk beyond
that provided by the PEL alone. OSHA's choice of proposing an action
level for exposure monitoring of one-half of the PEL is based on the
Agency's successful 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).
As specified in the proposed rule, all workers exposed to
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are
subject to the medical surveillance requirements. This means that the
medical surveillance requirements would apply to 15,172 workers in
general industry and 336,244 workers in construction. OSHA estimates
that 457 possible silicosis cases will be referred to pulmonary
specialists annually as a result of this medical surveillance.
OSHA has preliminarily determined that these ancillary provisions
will: (1) help to ensure the PEL is not exceeded, and (2) minimize risk
to workers given the very high level of risk remaining at the PEL. OSHA
did not estimate, and the benefits analysis does not include, monetary
benefits resulting from early discovery of illness.
Because medical surveillance and exposure assessment are the two
most costly ancillary provisions in the proposed rule, the Agency has
examined four regulatory alternatives (named Regulatory Alternatives
3, 4, 5, and 6) involving changes
to one or the other of these ancillary provisions. These four
regulatory alternatives are defined below and the incremental cost
impact of each is summarized in Table VIII-27. In addition, OSHA is
including a regulatory alternative (named Regulatory Alternative
7) that would remove all ancillary provisions.
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Under Regulatory Alternative 3, the action level would be
raised from 25 [micro]g/m\3\ to 50 [micro]g/m\3\ while keeping the PEL
at 50 [micro]g/m\3\. As a result, exposure monitoring requirements
would be triggered only if workers were exposed
above the proposed PEL of 50 [micro]g/m\3\. As shown in Table VIII-27,
Regulatory Option 3 would reduce the annualized cost of the
proposed rule by about $62 million, using a discount rate of either 3
percent or 7 percent.
Under Regulatory Alternative 4, the action level would
remain at 25 [micro]g/m\3\ but medical surveillance would now be
triggered by the action level, not the PEL. As a result, medical
surveillance requirements would be triggered only if workers were
exposed at or above the proposed action level of 25 [micro]g/m\3\. As
shown in Table VIII-27, Regulatory Option 4 would increase the
annualized cost of the proposed rule by about $143 million, using a
discount rate of 3 percent (and by about $169 million, using a discount
rate of 7 percent).
Under Regulatory Alternative 5, the only change to the
proposed rule would be to the medical surveillance requirements.
Instead of requiring workers exposed above the PEL to have a medical
check-up every three years, those workers would be required to have a
medical check-up annually. As shown in Table VIII-27, Regulatory Option
5 would increase the annualized cost of the proposed rule by
about $69 million, using a discount rate of 3 percent (and by about $66
million, using a discount rate of 7 percent).
Regulatory Alternative 6 would essentially combine the
modified requirements in Regulatory Alternatives 4 and
5. Under Regulatory Alternative 6, medical
surveillance would be triggered by the action level, not the PEL, and
workers exposed at or above the action level would be required to have
a medical check-up annually rather than triennially. The exposure
monitoring requirements in the proposed rule would not be affected. As
shown in Table VIII-27, Regulatory Option 6 would increase the
annualized cost of the proposed rule by about $342 million, using a
discount rate of either 3 percent or 7 percent.
OSHA is not able to quantify the effects of these preceding four
regulatory alternatives on protecting workers exposed to respirable
crystalline silica at levels at or below the proposed PEL of 50
[micro]g/m\3\--where significant risk remains. The Agency solicits
comment on the extent to which these regulatory options may improve or
reduce the effectiveness of the proposed rule.
The final regulatory alternative affecting ancillary provisions,
Regulatory Alternative 7, would eliminate all of the ancillary
provisions of the proposed rule, including exposure assessment, medical
surveillance, training, and regulated areas or access control. However,
it should be carefully 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 do monitoring, train workers on the use of controls, and set up
some kind of regulated areas to indicate where respirator use would be
required. It is also likely that employers would increasingly follow
the many recommendations to provide medical surveillance for employees.
OSHA has not attempted to estimate the extent to which the costs of
these activities would be reduced if they were not formally required,
but OSHA welcomes comment on the issue.
As indicated previously, OSHA preliminarily finds that there is
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\.
However, the Agency has also preliminarily determined that 50 [mu]g/
m\3\ is the lowest feasible PEL. Therefore, the Agency believes that it
is necessary to include ancillary provisions in the proposed rule to
further reduce the remaining risk. OSHA anticipates that these
ancillary provisions will reduce the risk beyond the reduction that
will be achieved by a new PEL alone.
OSHA's reasons for including each of the proposed ancillary
provisions are detailed in Section XVI of this preamble, Summary and
Explanation of the Standards. In particular, OSHA believes that
requirements for exposure assessment (or alternately, using specified
exposure control methods for selected construction operations) would
provide a basis for ensuring that appropriate measures are in place to
limit worker exposures. Medical surveillance is particularly important
because individuals exposed above the PEL (which triggers medical
surveillance in the proposed rule) are at significant risk of death and
illness. Medical surveillance would allow for identification of
respirable crystalline silica-related adverse health effects at an
early stage so that appropriate intervention measures can be taken.
OSHA believes that regulated areas and access control are important
because they serve to limit exposure to respirable crystalline silica
to as few employees as possible. Finally, OSHA believes that 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.
OSHA expects that the benefits estimated under the proposed rule
will not be fully achieved if employers do not implement the ancillary
provisions of the proposed rule. For example, OSHA believes that the
effectiveness of the proposed rule depends on regulated areas or access
control to further limit exposures and on medical surveillance to
identify disease cases when they do occur.
Both industry and worker groups have recognized that a
comprehensive standard 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 (ASTM, 2006; 2009; BCTD 2001). Moreover, as mentioned
previously, where there is continuing significant risk, the decision in
the Asbestos case (Bldg. and Constr. Trades Dep't, AFL-CIO v. Brock,
838 F.2d 1258, 1274 (DC Cir. 1988)) indicated that OSHA should use its
legal authority to impose additional requirements on employers to
further reduce risk when those requirements will result in a greater
than de minimis incremental benefit to workers' health. OSHA
preliminarily concludes that the additional requirements in the
ancillary provisions of the proposed standard clearly exceed this
threshold.
A Regulatory Alternative That Modifies the Methods of Compliance
The proposed standard in general industry and maritime would
require 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 would still
be required to implement them to reduce exposure as much as possible,
and to supplement them with a respiratory protection program. Under the
proposed construction standard, employers would be given two options for
compliance. The first option largely follows requirements for the
general industry and maritime proposed standard, while the second
option outlines, in Table 1 (Exposure Control Methods for Selected
Construction Operations) of the proposed rule, specific construction
exposure control methods. Employers choosing to follow OSHA's proposed
control methods would be considered to be in compliance with the
engineering and work practice control requirements of the proposed
standard, and would not be required to conduct certain exposure
monitoring activities.
One regulatory alternative (Regulatory Alternative 8)
involving methods of compliance would be to eliminate Table 1 as a
compliance option in the construction sector. Under this regulatory
alternative, OSHA estimates that there would be no effect on estimated
benefits but that the annualized costs of complying with the proposed
rule (without the benefit of the Table 1 option in construction) would
increase by $175 million, totally in exposure monitoring costs, using a
3 percent discount rate (and by $178 million using a 7 percent discount
rate), so that the total annualized compliance costs for all affected
establishments in construction would increase from $495 to $670 million
using a 3 percent discount rate (and from $511 to $689 million using a
7 percent discount rate).
Regulatory Alternatives That Affect the Timing of the Standard
The proposed rule would become effective 60 days following
publication of the final rule in the Federal Register. Provisions
outlined in the proposed standard would become enforceable 180 days
following the effective date, with the exceptions of engineering
controls and laboratory requirements. The proposed rule would require
engineering controls to be implemented no later than one year after the
effective date, and laboratory requirements would be required to begin
two years after the effective date.
One regulatory alternative (Regulatory Alternative 9)
involving the timing of the standard would arise if, contrary to OSHA's
preliminary findings, a PEL of 50 [micro]g/m\3\ with an action level of
25 [micro]g/m\3\ were found to be technologically and economically
feasible some time in the future (say, in five years), but not feasible
immediately. In that case, OSHA might issue a final rule with a PEL of
50 [micro]g/m\3\ and an action level of 25 [micro]g/m\3\ to take effect
in five years, but at the same time issue an interim PEL of 100
[micro]g/m\3\ and an action level of 50 [micro]g/m\3\ to be in effect
until the final rule becomes feasible. Under this regulatory
alternative, and consistent with the public participation and "look
back" provisions of Executive Order 13563, the Agency could monitor
compliance with the interim standard, review progress toward meeting
the feasibility requirements of the final rule, and evaluate whether
any adjustments to the timing of the final rule would be needed. Under
Regulatory Alternative 9, the estimated costs and benefits
would be somewhere between those estimated for a PEL of 100 [micro]g/
m\3\ with an action level of 50 [micro]g/m\3\ and those estimated for a
PEL of 50 [micro]g/m\3\ with an action level of 25 [micro]g/m\3\, the
exact estimates depending on the length of time until the final rule is
phased in. OSHA emphasizes that this regulatory alternative is contrary
to the Agency's preliminary findings of economic feasibility and, for
the Agency to consider it, would require specific evidence introduced
on the record to show that the proposed rule is not now feasible but
would be feasible in the future.
Although OSHA did not explicitly develop or quantitatively analyze
any other regulatory alternatives involving longer-term or more complex
phase-ins of the standard (possibly involving more delayed
implementation dates for small businesses), OSHA is soliciting comments
on this issue. Such a particularized, multi-year phase-in would have
several advantages, especially from the viewpoint of impacts on small
businesses. First, it would reduce the one-time initial costs of the
standard by spreading them out over time, a particularly useful
mechanism for small businesses that have trouble borrowing large
amounts of capital in a single year. A differential phase-in for
smaller firms would also aid very small firms by allowing them to gain
from the control experience of larger firms. A phase-in would also be
useful in certain industries--such as foundries, for example--by
allowing employers to coordinate their environmental and occupational
safety and health control strategies to minimize potential costs.
However a phase-in would also postpone the benefits of the standard,
recognizing, as described in Chapter VII of the PEA, that the full
benefits of the proposal would take a number of years to fully
materialize even in the absence of a phase-in.
As previously discussed in the Introduction to this preamble, OSHA
requests comments on these regulatory alternatives, including the
Agency's choice of regulatory alternatives (and whether there are other
regulatory alternatives the Agency should consider) and the Agency's
analysis of them.
I. Initial Regulatory Flexibility Analysis
The Regulatory Flexibility Act, as amended in 1996, requires the
preparation of an Initial Regulatory Flexibility Analysis (IRFA) for
proposed rules where there would be a significant economic impact on a
substantial number of small entities. (5 U.S.C. 601-612). Under the
provisions of the law, each such analysis shall contain:
1. A description of the impact of the proposed rule on small
entities;
2. A description of the reasons why action by the agency is being
considered;
3. A succinct statement of the objectives of, and legal basis for,
the proposed rule;
4. A description of and, where feasible, an estimate of the number
of small entities to which the proposed rule will apply;
5. A description of the projected reporting, recordkeeping, and
other compliance requirements of the proposed rule, including an
estimate of the classes of small entities which will be subject to the
requirements and the type of professional skills necessary for
preparation of the report or record;
6. An identification, to the extent practicable, of all relevant
Federal rules which may duplicate, overlap, or conflict with the
proposed rule; and
7. A description and discussion of any significant alternatives to
the proposed rule which accomplish the stated objectives of applicable
statutes and which minimize any significant economic impact of the
proposed rule on small entities, such as
(a) The establishment of differing compliance or reporting
requirements or timetables that take into account the resources
available to small entities;
(b) The clarification, consolidation, or simplification of
compliance and reporting requirements under the rule for such small
entities;
(c) The use of performance rather than design standards; and
(d) An exemption from coverage of the rule, or any part thereof,
for such small entities.
5 U.S.C. 603, 607.
The Regulatory Flexibility Act further states that the required
elements of the IRFA 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 IRFA. 5 U.S.C. 605.
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 PEA and its supporting materials, this IRFA will summarize the
key aspects of OSHA's analysis as they affect small entities.
A Description of the Impact of the Proposed Rule on Small Entities
Section VIII.F of this preamble summarized the impacts of the
proposed rule on small entities. Tables VIII-12 and VIII-15 showed
costs as a percentage of profits and revenues for small entities in
general industry and maritime and in construction, respectively,
classified as small by the Small Business Administration, and Tables
VIII-13 and VIII-16 showed costs as a percentage of revenues and
profits for business entities with fewer than 20 employees in general
industry and maritime and in construction, respectively. (The costs in
these tables were annualized using a discount rate of 7 percent.)
A Description of the Reasons Why Action by the Agency Is Being
Considered
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 analysis of the scientific literature and silica-related
health risks are presented in the background document entitled
"Respirable Crystalline Silica--Health Effects Literature Review and
Preliminary Quantitative Risk Assessment" (placed in Docket OSHA-2010-
0034).
Based on a review of over 60 epidemiological studies covering more
than 30 occupational groups, OSHA preliminarily concludes that
crystalline silica is a human carcinogen. Most of these studies
documented that exposed workers experience higher lung cancer mortality
rates than do unexposed workers or the general population, and that the
increase in lung cancer mortality is related to cumulative exposure to
crystalline silica. These exposure-related trends strongly implicate
crystalline silica as a likely causative agent. This is consistent with
the conclusions of other government and public health organizations,
including the International Agency for Research on Cancer (IARC), the
Agency for Toxic Substance and Disease Registry (ATSDR), the World
Health Organization (WHO), the U.S. Environmental Protection Agency
(EPA), the National Toxicology Program (NTP), the National Academies of
Science (NAS), the National Institute for Occupational Safety and
Health (NIOSH), and the American Conference of Governmental Industrial
Hygienists (ACGIH).
OSHA believes that the strongest evidence for carcinogenicity comes
from studies in five industry sectors (diatomaceous earth, pottery,
granite, industrial sand, and coal mining) as well as a study by
Steenland et al. (2001) that analyzed pooled data from 10 occupational
cohort studies; each of these studies found a positive relationship
between exposure to crystalline silica and lung cancer mortality. Based
on a variety of relative risk models fit to these data sets, OSHA
estimates that the excess lifetime risk to workers exposed over a
working life of 45 years at the current general industry permissible
exposure limit (PEL) (approximately 100 [mu]g/m\3\ respirable
crystalline silica) is between 13 and 60 deaths per 1,000 workers. For
exposure over a working life at the current construction and shipyard
employment PELs (estimated to range between 250 and 500 [mu]g/m\3\),
the estimated risk lies between 37 and 653 deaths per 1,000. Reducing
these PELs to the proposed PEL of 50 [mu]g/m\3\ respirable crystalline
silica results in a substantial reduction of these risks, to a range
estimated to be between 6 and 26 deaths per 1,000 workers.
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. (2002), which pooled data from six worker cohort studies to derive
a quantitative relationship between exposure and death rate for
silicosis. For non-malignant respiratory disease, risk estimates are
based on an epidemiologic study of diatomaceous earth workers, which
included a quantitative exposure-response analysis (Park et al., 2002).
For 45 years of exposure to the current general industry PEL, OSHA's
estimates of excess lifetime risk are 11 deaths per 1,000 workers for
the pooled analysis and 83 deaths per 1,000 workers based on Park et
al.'s (2002) estimates. At the proposed PEL, estimates of silicosis and
non-malignant respiratory disease mortality are 7 and 43 deaths per
1,000, respectively. As noted by Park et al. (2002), it is likely that
silicosis as a cause of death is often misclassified as emphysema or
chronic bronchitis; thus, Mannetje et al.'s selection 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 seven studies that quantitatively described
relationships between exposure to respirable crystalline silica and
silicosis morbidity, as diagnosed from chest radiography (i.e., chest
x-rays or computerized tomography). Estimates of silicosis morbidity
derived from these cohort studies range from 60 to 773 cases per 1,000
workers for a 45-year exposure to the current general industry PEL, and
approach unity for a 45-year exposure to the current construction/
shipyard PEL. Estimated risks of silicosis morbidity range from 20 to
170 cases per 1,000 workers for a 45-year exposure to the proposed PEL,
reflecting a substantial reduction in the risk associated with exposure
to the current PELs.
OSHA's estimates of crystalline silica-related renal disease
mortality risk are derived from an analysis by Steenland et al. (2002),
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. From
this study, OSHA estimates that exposure to the current general
industry and proposed PELs over a working life would result in a
lifetime excess renal disease risk of 39 and 32 deaths per 1,000
workers, respectively. For exposure to the current construction/
shipyard PEL, OSHA estimates the excess lifetime risk to range from 52
to 63 deaths per 1,000 workers.
A Statement of the Objectives of, and Legal Basis for, the Proposed
Rule
The objective of the proposed 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 to perform their jobs safely. The legal basis for the rule is
the responsibility given 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. Sec. 655(b)(5). See
Section II of this preamble for a more detailed discussion of the
Secretary's legal authority to promulgate standards.
A Description of and Estimate of the Number of Small Entities To Which
the Proposed Rule Will Apply
OSHA has completed a preliminary analysis of the impacts associated
with this proposal, including an analysis of the type and number of
small entities to which the proposed rule would apply, as described
above. 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 470,000 small business or
government entities would be affected by the proposed standard. Within
these small entities, roughly 1.3 million workers are exposed to
crystalline silica and would be protected by the proposed standard. A
breakdown, by industry, of the number of affected small entities is
provided in Table III-3 in Chapter III of the PEA.
OSHA estimates that approximately 356,000 very small entities would
be affected by the proposed standard. Within these very small entities,
roughly 580,000 workers are exposed to crystalline silica and would be
protected by the proposed standard. A breakdown, by industry, of the
number of affected very small entities is provided in Table III-4 in
Chapter III of the PEA.
A Description of the Projected Reporting, Recordkeeping, and Other
Compliance Requirements of the Proposed Rule
Tables VIII-28 and VIII-29 show the average costs of the proposed
standard by NAICS code and by compliance requirement for, respectively,
small entities (classified as small by SBA) and very small entities
(fewer than 20 employees). For the average small entity in general
industry and maritime, the estimated cost of the proposed rule would be
about $2,103 annually, with engineering controls accounting for 67
percent of the costs and exposure monitoring accounting for 23 percent
of the costs. For the average small entity in construction, the
estimate cost of the proposed rule would be about $798 annually, with
engineering controls accounting for 47 percent of the costs, exposure
monitoring accounting for 17 percent of the costs, and medical
surveillance accounting for 15 percent of the costs.
For the average very small entity in general industry and maritime,
the estimate cost of the proposed rule would be about $616 annually,
with engineering controls accounting for 55 percent of the costs and
exposure monitoring accounting for 33 percent of the costs. For the
average very small entity in construction, the estimate cost of the
proposed rule would be about $533 annually, with engineering controls
accounting for 45 percent of the costs, exposure monitoring accounting
for 16 percent of the costs, and medical surveillance accounting for 16
percent of the costs.
Table VIII-30 shows the unit costs which form the basis for these
cost estimates for the average small entity and very small entity.
Table VIII-28--Average Costs for Small Entities Affected by the Proposed Silica Standard for General Industry, Maritime, and Construction
[2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Engineering
controls Regulated
NAICS Industry (includes Respirators Exposure Medical Training areas or Total
abrasive monitoring surveillance access
blasting) control
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121................... Asphalt paving mixture and $232 $4 $13 $1 $74 $1 $326
block manufacturing.
324122................... Asphalt shingle and roofing 5,721 297 1,887 103 114 111 8,232
materials.
325510................... Paint and coating 0 10 36 3 15 4 69
manufacturing.
327111................... Vitreous china plumbing 6,310 428 2,065 150 162 160 9,274
fixtures & bathroom
accessories manufacturing.
327112................... Vitreous china, fine 1,679 114 663 41 47 42 2,586
earthenware, & other
pottery product
manufacturing.
327113................... Porcelain electrical supply 6,722 458 2,656 162 188 170 10,355
mfg.
327121................... Brick and structural clay 28,574 636 3,018 226 237 236 32,928
mfg.
327122................... Ceramic wall and floor tile 10,982 245 1,160 87 91 91 12,655
mfg.
327123................... Other structural clay 10,554 235 1,115 83 87 87 12,162
product mfg.
327124................... Clay refractory 1,325 92 653 33 81 34 2,218
manufacturing.
327125................... Nonclay refractory 1,964 136 802 48 110 51 3,110
manufacturing.
327211................... Flat glass manufacturing... 4,068 160 520 56 50 60 4,913
327212................... Other pressed and blown 889 34 110 12 11 13 1,068
glass and glassware
manufacturing.
327213................... Glass container 2,004 76 248 27 24 29 2,408
manufacturing.
327320................... Ready-mixed concrete 1,728 460 1,726 163 121 171 4,369
manufacturing.
327331................... Concrete block and brick 3,236 245 1,257 87 134 91 5,049
mfg.
327332................... Concrete pipe mfg.......... 5,105 386 1,983 137 211 143 7,966
327390................... Other concrete product mfg. 3,016 228 1,171 81 125 85 4,705
327991................... Cut stone and stone product 2,821 207 1,040 74 65 77 4,284
manufacturing.
327992................... Ground or treated mineral 12,034 174 3,449 62 191 65 15,975
and earth manufacturing.
327993................... Mineral wool manufacturing. 1,365 56 185 20 17 21 1,664
327999................... All other misc. nonmetallic 2,222 168 863 60 92 62 3,467
mineral product mfg.
331111................... Iron and steel mills....... 604 34 138 12 11 13 812
331112................... Electrometallurgical 514 29 118 10 10 11 692
ferroalloy product
manufacturing.
331210................... Iron and steel pipe and 664 38 154 13 13 14 896
tube manufacturing from
purchased steel.
331221................... Rolled steel shape 583 33 135 12 11 12 787
manufacturing.
331222................... Steel wire drawing......... 638 36 148 13 12 14 862
331314................... Secondary smelting and 577 33 133 11 11 12 777
alloying of aluminum.
331423................... Secondary smelting, 534 30 125 11 10 11 722
refining, and alloying of
copper.
331492................... Secondary smelting, 548 31 128 11 11 12 741
refining, and alloying of
nonferrous metal (except
cu & al).
331511................... Iron foundries............. 9,143 522 2,777 185 200 194 13,021
331512................... Steel investment foundries. 11,874 675 3,596 240 249 251 16,885
331513................... Steel foundries (except 9,223 526 2,802 187 202 196 13,135
investment).
331524................... Aluminum foundries (except 7,367 419 2,231 149 155 156 10,476
die-casting).
331525................... Copper foundries (except 4,563 260 1,382 92 96 96 6,489
die-casting).
331528................... Other nonferrous foundries 3,895 222 1,179 79 82 82 5,539
(except die-casting).
332111................... Iron and steel forging..... 531 30 161 11 12 11 756
332112................... Nonferrous forging......... 533 30 162 11 12 11 760
332115................... Crown and closure 514 29 156 10 11 11 732
manufacturing.
332116................... Metal stamping............. 533 30 162 11 12 11 759
332117................... Powder metallurgy part 535 31 163 11 12 11 762
manufacturing.
332211................... Cutlery and flatware 518 30 157 10 11 11 738
(except precious)
manufacturing.
332212................... Hand and edge tool 542 31 165 11 12 12 772
manufacturing.
332213................... Saw blade and handsaw 528 30 160 11 12 11 752
manufacturing.
332214................... Kitchen utensil, pot, and 560 32 170 11 12 12 798
pan manufacturing.
332323................... Ornamental and 524 20 102 7 11 8 673
architectural metal work.
332439................... Other metal container 550 31 167 11 12 12 784
manufacturing.
332510................... Hardware manufacturing..... 531 30 161 11 12 11 756
332611................... Spring (heavy gauge) 529 30 161 11 12 11 754
manufacturing.
332612................... Spring (light gauge) 585 33 178 12 13 12 834
manufacturing.
332618................... Other fabricated wire 537 31 163 11 12 11 765
product manufacturing.
332710................... Machine shops.............. 518 30 157 10 11 11 738
332812................... Metal coating and allied 843 33 165 12 18 12 1,083
services.
332911................... Industrial valve 528 30 160 11 12 11 752
manufacturing.
332912................... Fluid power valve and hose 532 30 162 11 12 11 757
fitting manufacturing.
332913................... Plumbing fixture fitting 528 30 160 11 12 11 752
and trim manufacturing.
332919................... Other metal valve and pipe 536 31 163 11 12 11 764
fitting manufacturing.
332991................... Ball and roller bearing 545 31 131 11 11 12 741
manufacturing.
332996................... Fabricated pipe and pipe 529 30 161 11 12 11 754
fitting manufacturing.
332997................... Industrial pattern 517 29 157 10 11 11 736
manufacturing.
332998................... Enameled iron and metal 484 23 97 8 10 9 630
sanitary ware
manufacturing.
332999................... All other miscellaneous 521 30 158 11 11 11 742
fabricated metal product
manufacturing.
333319................... Other commercial and 526 30 160 11 12 11 750
service industry machinery
manufacturing.
333411................... Air purification equipment 525 30 160 11 11 11 748
manufacturing.
333412................... Industrial and commercial 555 32 169 11 12 12 791
fan and blower
manufacturing.
333414................... Heating equipment (except 520 30 158 11 11 11 741
warm air furnaces)
manufacturing.
333511................... Industrial mold 522 30 159 11 11 11 743
manufacturing.
333512................... Machine tool (metal cutting 524 30 159 11 11 11 746
types) manufacturing.
333513................... Machine tool (metal forming 532 30 162 11 12 11 758
types) manufacturing.
333514................... Special die and tool, die 522 30 158 11 11 11 743
set, jig, and fixture
manufacturing.
333515................... Cutting tool and machine 524 30 159 11 11 11 746
tool accessory
manufacturing.
333516................... Rolling mill machinery and 522 30 159 11 11 11 744
equipment manufacturing.
333518................... Other metalworking 537 31 163 11 12 11 765
machinery manufacturing.
333612................... Speed changer, industrial 546 31 166 11 12 12 777
high-speed drive, and gear
manufacturing.
333613................... Mechanical power 529 30 161 11 12 11 754
transmission equipment
manufacturing.
333911................... Pump and pumping equipment 535 31 163 11 12 11 762
manufacturing.
333912................... Air and gas compressor 532 30 162 11 12 11 758
manufacturing.
333991................... Power-driven handtool 514 29 156 10 11 11 732
manufacturing.
333992................... Welding and soldering 523 30 159 11 11 11 745
equipment manufacturing.
333993................... Packaging machinery 521 30 158 11 11 11 742
manufacturing.
333994................... Industrial process furnace 531 30 161 11 12 11 757
and oven manufacturing.
333995................... Fluid power cylinder and 531 30 161 11 12 11 756
actuator manufacturing.
333996................... Fluid power pump and motor 542 31 165 11 12 11 772
manufacturing.
333997................... Scale and balance (except 537 31 163 11 12 11 764
laboratory) manufacturing.
333999................... All other miscellaneous 523 30 159 11 11 11 745
general purpose machinery
manufacturing.
334518................... Watch, clock, and part 514 29 156 10 11 11 732
manufacturing.
335211................... Electric housewares and 523 20 76 7 9 8 643
household fans.
335221................... Household cooking appliance 529 20 77 7 9 8 649
manufacturing.
335222................... Household refrigerator and 1,452 56 210 19 26 21 1,784
home freezer manufacturing.
335224................... Household laundry equipment 1,461 56 212 19 26 21 1,795
manufacturing.
335228................... Other major household 523 20 101 7 11 8 671
appliance manufacturing.
336111................... Automobile manufacturing... 1,309 75 297 25 23 28 1,757
336112................... Light truck and utility 4,789 273 1,085 92 86 102 6,425
vehicle manufacturing.
336120................... Heavy duty truck 1,211 69 275 23 22 26 1,626
manufacturing.
336211................... Motor vehicle body 579 33 137 11 11 12 784
manufacturing.
336212................... Truck trailer manufacturing 525 30 160 11 11 11 748
336213................... Motor home manufacturing... 792 45 181 15 15 17 1,064
336311................... Carburetor, piston, piston 525 30 160 11 11 11 748
ring, and valve
manufacturing.
336312................... Gasoline engine and engine 522 30 120 10 10 11 703
parts manufacturing.
336322................... Other motor vehicle 524 30 121 10 10 11 706
electrical and electronic
equipment manufacturing.
336330................... Motor vehicle steering and 526 30 120 10 10 11 708
suspension components
(except spring)
manufacturing.
336340................... Motor vehicle brake system 527 30 121 10 10 11 710
manufacturing.
336350................... Motor vehicle transmission 528 30 121 10 10 11 710
and power train parts
manufacturing.
336370................... Motor vehicle metal 556 32 169 11 12 12 792
stamping.
336399................... All other motor vehicle 535 30 123 10 10 11 721
parts manufacturing.
336611................... Ship building and repair... 13,685 0 718 692 47 75 15,217
336612................... Boat building.............. 2,831 0 202 149 11 16 3,209
336992................... Military armored vehicle, 624 35 149 12 12 13 845
tank, and tank component
manufacturing.
337215................... Showcase, partition, 527 30 160 11 12 11 751
shelving, and locker
manufacturing.
339114................... Dental equipment and 671 39 145 14 11 15 895
supplies manufacturing.
339116................... Dental laboratories........ 12 7 130 3 44 3 199
339911................... Jewelry (except costume) 120 92 475 33 41 34 795
manufacturing.
339913................... Jewelers' materials and 151 115 596 41 51 43 997
lapidary work
manufacturing.
339914................... Costume jewelry and novelty 87 44 229 16 19 16 412
manufacturing.
339950................... Sign manufacturing......... 465 20 107 7 11 8 618
423840................... Industrial supplies, 313 29 257 10 15 11 636
wholesalers.
482110................... Rail transportation........ ............ ............ ............ ............ ............ ............ ............
621210................... Dental offices............. 3 2 32 1 11 1 50
Total--General Industry and 1,399 93 483 46 46 36 2,103
Maritime.
236100................... Residential Building 264 43 34 37 27 15 419
Construction.
236200................... Nonresidential Building 234 104 67 89 66 14 575
Construction.
237100................... Utility System Construction 978 89 172 78 185 30 1,531
237200................... Land Subdivision........... 104 9 25 8 30 3 180
237300................... Highway, Street, and Bridge 692 109 179 95 227 26 1,329
Construction.
237900................... Other Heavy and Civil 592 60 134 52 175 18 1,032
Engineering Construction.
238100................... Foundation, Structure, and 401 359 113 307 91 49 1,319
Building Exterior
Contractors.
238200................... Building Equipment 156 18 21 16 27 7 244
Contractors.
238300................... Building Finishing 289 24 23 50 27 9 421
Contractors.
238900................... Other Specialty Trade 460 43 65 52 79 30 729
Contractors.
999000................... State and Local Governments 108 16 31 14 43 11 222
[c].
Total--Construction........ 375 132 72 122 71 26 798
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).
Table VIII-29--Average Costs for Very Small Entities (<20 Employees) Affected by the Proposed Silica Standard for General Industry, Maritime, and
Construction
[2009 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Engineering
controls Regulated
NAICS Industry (includes Respirators Exposure Medical Training areas or Total
abrasive monitoring surveillance access
blasting) control
--------------------------------------------------------------------------------------------------------------------------------------------------------
324121................... Asphalt paving mixture and $74 $1 $5 $0 $26 $0 $107
block manufacturing.
324122................... Asphalt shingle and roofing 914 48 476 17 23 18 1,496
materials.
325510................... Paint and coating 0 7 33 3 13 3 58
manufacturing.
327111................... Vitreous china plumbing 851 58 422 21 26 22 1,400
fixtures & bathroom
accessories manufacturing.
327112................... Vitreous china, fine 705 48 349 17 22 18 1,160
earthenware, & other
pottery product
manufacturing.
327113................... Porcelain electrical supply 851 58 422 21 26 22 1,400
mfg.
327121................... Brick and structural clay 2,096 47 277 17 19 17 2,474
mfg.
327122................... Ceramic wall and floor tile 2,385 53 316 19 22 20 2,815
mfg.
327123................... Other structural clay 2,277 51 301 18 21 19 2,687
product mfg.
327124................... Clay refractory 301 21 186 8 20 8 543
manufacturing.
327125................... Nonclay refractory 471 33 291 12 32 12 852
manufacturing.
327211................... Flat glass manufacturing... 842 34 163 12 12 12 1,075
327212................... Other pressed and blown 873 34 164 12 12 12 1,107
glass and glassware
manufacturing.
327213................... Glass container 873 34 164 12 12 12 1,107
manufacturing.
327320................... Ready-mixed concrete 475 127 595 46 37 47 1,328
manufacturing.
327331................... Concrete block and brick 966 74 470 27 44 27 1,608
mfg.
327332................... Concrete pipe mfg.......... 1,046 80 509 29 48 29 1,741
327390................... Other concrete product mfg. 854 65 416 23 39 24 1,422
327991................... Cut stone and stone product 1,158 86 535 31 30 32 1,872
manufacturing.
327992................... Ground or treated mineral 3,564 52 1,280 19 63 19 4,997
and earth manufacturing.
327993................... Mineral wool manufacturing. 823 34 166 12 12 13 1,061
327999................... All other misc. nonmetallic 797 61 388 22 37 22 1,327
mineral product mfg.
331111................... Iron and steel mills....... 517 30 197 11 13 11 777
331112................... Electrometallurgical 0 0 0 0 0 0 0
ferroalloy product
manufacturing.
331210................... Iron and steel pipe and 514 30 196 11 12 11 774
tube manufacturing from
purchased steel.
331221................... Rolled steel shape 514 30 196 11 12 11 774
manufacturing.
331222................... Steel wire drawing......... 514 30 196 11 12 11 774
331314................... Secondary smelting and 514 30 196 11 12 11 774
alloying of aluminum.
331423................... Secondary smelting, 0 0 0 0 0 0 0
refining, and alloying of
copper.
331492................... Secondary smelting, 514 30 196 11 12 11 774
refining, and alloying of
nonferrous metal (except
cu & al).
331511................... Iron foundries............. 1,093 63 416 23 26 23 1,644
331512................... Steel investment foundries. 1,181 68 448 24 28 25 1,774
331513................... Steel foundries (except 1,060 61 404 22 26 22 1,595
investment).
331524................... Aluminum foundries (except 1,425 82 541 29 33 30 2,141
die-casting).
331525................... Copper foundries (except 1,503 86 570 31 35 32 2,257
die-casting).
331528................... Other nonferrous foundries 1,401 80 532 29 33 30 2,104
(except die-casting).
332111................... Iron and steel forging..... 514 30 196 11 12 11 774
332112................... Nonferrous forging......... 514 30 196 11 12 11 774
332115................... Crown and closure 514 30 196 11 12 11 774
manufacturing.
332116................... Metal stamping............. 515 30 196 11 12 11 775
332117................... Powder metallurgy part 514 30 196 11 12 11 774
manufacturing.
332211................... Cutlery and flatware 514 30 196 11 12 11 774
(except precious)
manufacturing.
332212................... Hand and edge tool 514 30 196 11 12 11 774
manufacturing.
332213................... Saw blade and handsaw 514 30 196 11 12 11 774
manufacturing.
332214................... Kitchen utensil, pot, and 0 0 0 0 0 0 0
pan manufacturing.
332323................... Ornamental and 520 20 127 7 12 8 694
architectural metal work.
332439................... Other metal container 524 30 199 11 13 11 788
manufacturing.
332510................... Hardware manufacturing..... 517 30 197 11 13 11 777
332611................... Spring (heavy gauge) 523 30 199 11 13 11 786
manufacturing.
332612................... Spring (light gauge) 514 30 196 11 12 11 774
manufacturing.
332618................... Other fabricated wire 514 30 196 11 12 11 774
product manufacturing.
332710................... Machine shops.............. 515 30 196 11 12 11 774
332812................... Metal coating and allied 519 20 127 7 12 8 694
services.
332911................... Industrial valve 514 30 196 11 12 11 774
manufacturing.
332912................... Fluid power valve and hose 514 30 196 11 12 11 774
fitting manufacturing.
332913................... Plumbing fixture fitting 514 30 196 11 12 11 774
and trim manufacturing.
332919................... Other metal valve and pipe 519 30 198 11 13 11 781
fitting manufacturing.
332991................... Ball and roller bearing 514 30 196 11 12 11 774
manufacturing.
332996................... Fabricated pipe and pipe 514 30 196 11 12 11 774
fitting manufacturing.
332997................... Industrial pattern 514 30 196 11 12 11 774
manufacturing.
332998................... Enameled iron and metal 484 23 153 8 12 9 690
sanitary ware
manufacturing.
332999................... All other miscellaneous 514 30 196 11 12 11 774
fabricated metal product
manufacturing.
333319................... Other commercial and 514 30 196 11 12 11 774
service industry machinery
manufacturing.
333411................... Air purification equipment 514 30 196 11 12 11 774
manufacturing.
333412................... Industrial and commercial 514 30 196 11 12 11 774
fan and blower
manufacturing.
333414................... Heating equipment (except 517 30 197 11 13 11 777
warm air furnaces)
manufacturing.
333511................... Industrial mold 515 30 196 11 12 11 774
manufacturing.
333512................... Machine tool (metal cutting 516 30 196 11 13 11 776
types) manufacturing.
333513................... Machine tool (metal forming 514 30 196 11 12 11 774
types) manufacturing.
333514................... Special die and tool, die 515 30 196 11 12 11 774
set, jig, and fixture
manufacturing.
333515................... Cutting tool and machine 515 30 196 11 12 11 775
tool accessory
manufacturing.
333516................... Rolling mill machinery and 514 30 196 11 12 11 774
equipment manufacturing.
333518................... Other metalworking 514 30 196 11 12 11 774
machinery manufacturing.
333612................... Speed changer, industrial 514 30 196 11 12 11 774
high-speed drive, and gear
manufacturing.
333613................... Mechanical power 514 30 196 11 12 11 774
transmission equipment
manufacturing.
333911................... Pump and pumping equipment 514 30 196 11 12 11 774
manufacturing.
333912................... Air and gas compressor 514 30 196 11 12 11 774
manufacturing.
333991................... Power-driven handtool 514 30 196 11 12 11 774
manufacturing.
333992................... Welding and soldering 514 30 196 11 12 11 774
equipment manufacturing.
333993................... Packaging machinery 514 30 196 11 12 11 774
manufacturing.
333994................... Industrial process furnace 514 30 196 11 12 11 774
and oven manufacturing.
333995................... Fluid power cylinder and 514 30 196 11 12 11 774
actuator manufacturing.
333996................... Fluid power pump and motor 514 30 196 11 12 11 774
manufacturing.
333997................... Scale and balance (except 514 30 196 11 12 11 774
laboratory) manufacturing.
333999................... All other miscellaneous 514 30 196 11 12 11 774
general purpose machinery
manufacturing.
334518................... Watch, clock, and part 514 30 196 11 12 11 774
manufacturing.
335211................... Electric housewares and 0 0 0 0 0 0 0
household fans.
335221................... Household cooking appliance 523 20 127 7 12 8 698
manufacturing.
335222................... Household refrigerator and 0 0 0 0 0 0 0
home freezer manufacturing.
335224................... Household laundry equipment 0 0 0 0 0 0 0
manufacturing.
335228................... Other major household 0 0 0 0 0 0 0
appliance manufacturing.
336111................... Automobile manufacturing... 514 30 196 11 12 11 774
336112................... Light truck and utility 514 30 196 11 12 11 774
vehicle manufacturing.
336120................... Heavy duty truck 514 30 196 11 12 11 774
manufacturing.
336211................... Motor vehicle body 514 30 196 11 12 11 774
manufacturing.
336212................... Truck trailer manufacturing 514 30 196 11 12 11 774
336213................... Motor home manufacturing... 514 30 196 11 12 11 774
336311................... Carburetor, piston, piston 514 30 196 11 12 11 774
ring, and valve
manufacturing.
336312................... Gasoline engine and engine 514 30 196 11 12 11 774
parts manufacturing.
336322................... Other motor vehicle 514 30 196 11 12 11 774
electrical and electronic
equipment manufacturing.
336330................... Motor vehicle steering and 514 30 196 11 12 11 774
suspension components
(except spring)
manufacturing.
336340................... Motor vehicle brake system 514 30 196 11 12 11 774
manufacturing.
336350................... Motor vehicle transmission 514 30 196 11 12 11 774
and power train parts
manufacturing.
336370................... Motor vehicle metal 517 30 197 11 13 11 778
stamping.
336399................... All other motor vehicle 514 30 196 11 12 11 774
parts manufacturing.
336611................... Ship building and repair... 2,820 0 253 151 13 16 3,252
336612................... Boat building.............. 2,816 0 252 151 12 15 3,247
336992................... Military armored vehicle, 0 0 0 0 0 0 0
tank, and tank component
manufacturing.
337215................... Showcase, partition, 514 30 196 11 12 11 774
shelving, and locker
manufacturing.
339114................... Dental equipment and 663 39 180 14 12 14 922
supplies manufacturing.
339116................... Dental laboratories........ 8 5 107 2 32 2 156
339911................... Jewelry (except costume) 45 35 225 13 17 13 348
manufacturing.
339913................... Jewelers' materials and 52 40 256 14 19 15 397
lapidary work
manufacturing.
339914................... Costume jewelry and novelty 50 26 166 9 12 10 274
manufacturing.
339950................... Sign manufacturing......... 459 20 132 7 12 7 639
423840................... Industrial supplies, 262 24 215 9 13 9 531
wholesalers.
482110................... Rail transportation........
621210................... Dental offices............. 3 2 32 1 11 1 49
Total--General Industry and 337 29 205 12 23 11 616
Maritime.
236100................... Residential Building 264 43 42 38 30 15 432
Construction.
236200................... Nonresidential Building 117 52 42 46 37 7 301
Construction.
237100................... Utility System Construction 326 30 71 27 69 10 532
237200................... Land Subdivision........... 104 9 25 8 30 3 180
237300................... Highway, Street, and Bridge 275 44 89 39 102 10 559
Construction.
237900................... Other Heavy and Civil 202 20 57 18 67 6 372
Engineering Construction.
238100................... Foundation, Structure, and 228 204 80 180 58 28 778
Building Exterior
Contractors.
238200................... Building Equipment 156 18 26 16 30 7 253
Contractors.
238300................... Building Finishing 289 24 28 51 30 9 431
Contractors.
238900................... Other Specialty Trade 276 26 49 32 53 18 454
Contractors.
999000................... State and Local Governments N/A N/A N/A N/A N/A N/A N/A
[c].
Total--Construction........ 242 87 56 83 49 17 533
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).
Table VIII-30--Source Information for the Unit Cost Estimates Used in OSHA's Preliminary Cost Analysis for General Industry, Maritime, and Construction
--------------------------------------------------------------------------------------------------------------------------------------------------------
Ventilation Capital cost Annualized
Control \[a]\ Description airflow (cfm) \[b]\ Operating cost capital cost Comment or source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Saw enclosure........................ 8' x 8' x 8' wood/ N/A $487.70 $48.77 $118.95 Fabrication costs
plastic. estimated by ERG,
assuming in-plant
work. Five-year life.
Cab enclosures....................... Enclosed cabs........... N/A 15,164.82 5,307.69 3,698.56 ERG estimate based on
vendor interviews.
LEV for hand held grinders........... Shrouds + vacuum........ N/A 1,671.63 585.07 407.70 Vacuum plus shroud
adapter (http://www.proventilation.com/products/productDetail.asp?id=15 5); 35% for
maintenance and
operating costs.
Upgraded abrasive blast cabinet...... Improved maintenance and N/A 4,666.10 1,000.00 664.35 Assumes add.
purchases for some. maintenance (of up to
$2,000) or new
cabinets ($8,000)
(Norton, 2003).
Improved spray booth for pottery..... Maintenance time & N/A 116.65 114.68 231.33 Annual: $100 materials
materials. plus 4 hours
maintenance time.
Improved LEV for ceramics spray booth Increased air flow; per N/A 3.21 0.88 3.21 25% of installed CFM
cfm. price.
Exhaust for saw, cut stone industry.. Based on saw LEV (e.g., 450 5,774.30 1,577.35 822.13 ERG based on typical
pg. 10-158, 159, 160, saw cfm requirements.
ACGIH, 2001).
LEV for hand chipping in cut stone... Granite cutting and 600 7,699.06 2,103.14 1,096.17 ERG estimate of cfm
finishing; (pg. 10-94, requirements.
ACGIH, 2001).
Exhaust trimming machine............. Based on abrasive cut- 500 6,415.89 1,752.61 913.48 Opening of 2 sq ft
off saw; (pg. 10-134) assumed, with 250 cfm/
(ACGIH, 2001). sq.ft.
Bag opening.......................... Bag opening station; 1,513 19,414.48 5,303.41 2,764.18 3.5' x 1.5' opening;
(pg. 10-19, ACGIH, with ventilated bag
2001). crusher (200 cfm).
Conveyor ventilation................. Conveyor belt 700 8,982.24 2,453.66 1,278.87 Per take-off point, 2'
ventilation; (pg. 10- wide belt.
70, ACGIH, 2001).
Bucket elevator ventilation.......... Bucket elevator 1,600 20,530.84 5,608.36 2,923.13 2' x 3' x 30' casing; 4
ventilation (pg. 10-68; take-offs @250 cfm;
ACGIH, 2001). 100 cfm per sq ft of
cross section.
Bin and hopper ventilation........... Bin and hopper 1,050 13,473.36 3,680.49 1,918.30 350 cfm per ft2; 3'
ventilation (pg. 10-69; belt width.
ACGIH, 2001).
Screen ventilation................... Ventilated screen (pg. 1,200 15,398.13 4,206.27 2,192.35 4' x 6' screen; 50 cfm
10-173, ACGIH, 2001). per ft\2\.
Batch operator workstation........... Bin & hopper ventilation 1,050 13,473.36 3,680.49 1,918.30 ERG estimate of cfm
for unvented mixers requirements.
(pg. 10-69, ACGIH,
2001).
LEV for hand grinding operator Hand grinding bench (pg. 3,750 48,119.16 13,144.60 6,851.09 ERG estimate of cfm
(pottery). 10-135, ACGIH, 2001). requirements.
LEV, mixer and muller hood........... Mixer & muller hood (pg. 1,050 13,473.36 3,680.49 1,918.30 ERG estimate of cfm
10-87, ACGIH, 2001). requirements.
LEV for bag filling stations......... Bag filling station (pg. 1,500 19,247.66 5,257.84 2,740.43 Includes costs for air
10-15, ACGIH, 2001). shower.
Installed manual spray mister........ Manual controls, system N/A 10,207.09 1,020.71 1,453.26 National Environmental
covers 100 ft of Services Company
conveyor. (Kestner, 2003).
Install cleaning hoses, reslope Plumbing for hose N/A 36,412.40 3,258.87 5,184.31 ERG estimate. Includes
floor, drainage. installations, floor cost of water and
resloping and troughs. labor time.
Shakeout conveyor enclosure.......... Ventilated shakeout 10,000 128,317.75 35,052.26 18,269.56 ERG estimate.
conveyor enclosure.
Shakeout side-draft ventilation...... Shakeout double side- 28,800 369,555.11 100,950.52 52,616.33 ERG estimate of cfm
draft table (pg. 10-23, requirements.
ACGIH, 2001).
Shakeout enclosing hood.............. Ventilated enclosing 7,040 90,335.69 24,676.79 12,861.77 ERG estimate of opening
hood (pg. 10-23, ACGIH, size required.
2001); 4' x 4' openings.
Small knockout table................. Portable grinding table 1,350 17,322.90 4,732.06 2,466.39 ERG estimate of opening
pg. 10-136), ACGIH, size required.
2001), 3' x 3' opening.
Large knockout table................. Hand grinding table pg. 4,800 61,592.52 16,825.09 8,769.39 ERG estimate of bench
10-135), ACGIH, 2001), surface area.
4' x 6' surface.
Ventilated abrasive cutoff saw....... Ventilated cut-off saw 1,500 19,247.66 5,257.84 2,740.43 ERG estimate of opening
(pg. 10-134, ACGIH, size required.
2001, 2' x 3' opening.
Hand grinding bench (foundry)........ Bench with LEV (pg. 10- 3,750 48,119.16 13,144.60 6,851.09 ERG estimate of cfm
135, ACGIH, 2001); 3' x requirements; 250 cfm/
5'. sq. ft.
Forming operator bench (pottery)..... Bench with LEV (pg. 10- 1,400 17,964.48 4,907.32 2,557.74 ERG estimate of cfm
149, ACGIH, 2001), 3' x requirements; 125 cfm
4'. per linear foot.
Hand grinding bench (pottery)........ Bench with LEV (pg. 10- 2,400 30,796.26 8,412.54 4,384.69 ERG estimate of cfm
135, ACGIH, 2001); 3' x requirements; 200 cfm/
4'. sq. ft.
Hand tool hardware................... Retrofit suction 200 464.21 701.05 66.09 ERG estimate of cfm
attachment. requirements.
Clean air island..................... Clean air supplied 2,500 32,079.44 8,763.07 4,567.39 ERG estimate of cfm
directly to worker. requirements; 125 cfm/
sq. ft. for 20 square
feet.
Water fed chipping equipment drum Shop-built water feed N/A 116.65 0.00 116.65 ERG estimate. $100 in
cleaning. equipment. annual costs.
Ventilation for drum cleaning........ Ventilation blower and N/A 792.74 198.18 193.34 Electric blower (1,277
ducting. cfm) and 25 ft. of
duct. Northern Safety
Co. (p. 193).
Control room......................... 10' x 10' ventilated 200 19,556.79 701.05 2,784.45 ERG estimate based on
control room with HEPA RSMeans (2003), ACGIH
filter. (2001).
Control room improvement............. Repair and improve N/A 2,240.00 N/A 318.93 ERG estimate. Assumes
control room enclosure. repairs are 20% of new
control room cost.
Improved bag valves.................. Bags with extended N/A 0.01 N/A N/A Cecala et. al., (1986).
polyethylene valve,
incremental cost per
bag.
Dust suppressants.................... Kleen Products 50 lb N/A N/A 634.54 0.00 0.28/lb, 2 lbs/day; 5
poly bag green sweeping minutes/day
compound. (www.fastenal.com).
HEPA vacuum for housekeeping......... NILFISK VT60 wet/dry N/A 3,494.85 511.20 852.36 Nilfisk, HEPA vacuum
hepa vac, 15 gal. (http://www.sylvane.com/nilfisk.html).
HEPA vacuum for housekeeping......... NILFISK, large capacity. N/A 7,699.06 988.90 1,877.73 Nilfisk, HEPA vacuum
(McCarthy, 2003).
Yard dust suppression................ 100 ft, 1" contractor N/A 204.14 0.00 112.91 Contactor hose and
hose and nozzle. nozzle; 2 year life;
(www.pwmall.com).
Wet methods to clean concrete mixing 10 mins per day per N/A 0.00 916.82 0.00 10 mins per day per
equip.. operator. mixer operator.
HEPA vacuum substitute for compressed Incremental time to N/A N/A 494.54 0.00 5 min per day per
air. remove dust by vacuum. affected worker.
Spray system for wet concrete Shop-built sprayer N/A 204.67 20.47 113.20 Assumes $100 in
finishing. system. materials and 4 hours
to fabricate. Also 10%
for maintenance.
Substitute alt., non-silica, blasting Alternative media N/A 0.00 33,646.00 0.00 Based on 212,000 square
media. estimated to cost 22 feet of coverage per
percent more. year per crew.
Abrasive blasting cost per square 125 blasting days per N/A N/A 2.00 N/A ERG estimate based on
foot (dry blasting). year. RSMeans (2009).
Half-mask, non-powered, air-purifying Unit cost includes N/A N/A 570.13 N/A
respirator. expenses for
accessories, training,
fit testing, and
cleaning.
Full-face nonpowered air-purifying Unit cost includes N/A N/A 637.94 N/A
respirator. expenses for
accessories, training,
fit testing, and
cleaning.
Half-face respirator (construction).. Unit cost includes N/A N/A 468.74 N/A
expenses for
accessories, training,
fit testing, and
cleaning.
Industrial Hygiene Fees/personal Consulting IH N/A N/A 500 N/A
breathing zone. technician--rate per
sample. Assumes IH rate
of $500 per day and
samples per day of 2,
6, and 8 for small,
medium, and large
establishments,
respectively.
Exposure assessment lab fees and ........................ N/A N/A 133.38 N/A Lab fees (EMSL
shipping cost. Laboratory, 2000) and
OSHA estimates.
Inflated to 2009
values.
Physical examination by knowledgeable Evaluation and office N/A N/A 100.00 N/A ERG, 2013.
Health Care Practitioner. consultation including
detailed examination.
Chest X-ray.......................... Tri-annual radiologic N/A N/A 79.61 N/A
examination, chest;
stereo, frontal. Costs
include consultation
and written report.
Pulmonary function test.............. Tri-annual spirometry, N/A N/A 54.69 N/A
including graphic
record, total and timed
vital capacity,
expiratory flow rate
measurements(s), and/or
maximal voluntary
ventilation.
Examination by a pulmonary specialist Office consultation and N/A N/A 190.28 N/A
\[c]\. evaluation by a
pulmonary specialist.
Training instructor cost per hour.... ........................ N/A N/A 34.09 N/A Based on supervisor
wage, adjusted for
fringe benefits (BLS,
2008, updated to 2009
dollars).
Training materials for class per Estimated cost of $2 per N/A N/A 2.00 N/A
attendee. worker for the training/
reading materials.
Value of worker time spent in class.. ........................ N/A N/A 17.94 N/A Based on worker wage,
adjusted for fringe
benefits (BLS, 2008,
updated to 2009
dollars).
Cost--disposable particulate 1.00 per respirator per N/A N/A 1.00 N/A Lab Safety Supply,
respirator (N95). day, typical cost for 2010.
N95 disposable
respirator.
Disposable clothing.................. Per suit, daily clothing N/A N/A 5.50 N/A Lab Safety Supply,
costs for 10% of 2010.
workers.
Hazard tape.......................... Per regulated area for N/A N/A 5.80 N/A Lab Safety Supply,
annual set-up (300 ft). 2010.
Warning signs (6 per regulated area). 25.30 per sign.......... N/A N/A 151.80 N/A Lab Safety Supply,
2010.
Wet kit, with water tank............. ........................ N/A 226.73 \[d]\ 0.18 125.40 Contractors Direct
(2009); Berland House
of Tools (2009);
mytoolstore (2009).
Dust shrouds: grinder................ ........................ N/A 97.33 \[d]\ 0.14 97.33 Contractors Direct
(2009); Berland House
of Tools (2009); Dust-
Buddy (2009); Martin
(2008).
Water tank, portable (unspecified ........................ N/A N/A \[e]\ 15.50 N/A RSMeans--based on
capacity). monthly rental cost.
Water tank, small capacity (hand ........................ N/A 73.87 \[d]\ 0.11 79.04 Contractors Direct
pressurized). (2009); mytoolstore
(2009).
Hose (water), 20', 2" diameter...... ........................ N/A N/A \[e]\ 1.65 N/A RSMeans--based on
monthly cost.
Custom water spray nozzle and ........................ N/A 363 \[d]\ 0.54 388.68 New Jersey Laborers'
attachments. Health and Safety Fund
(2007).
Hose (water), 200', 2" diameter..... ........................ N/A N/A \[e]\ 16.45 N/A RSMeans--based on
monthly rental cost.
Vacuum, 10-15 gal with HEPA.......... ........................ N/A 725 \[d]\ 0.56 400.99 ICS (2009); Dust
Collection (2009);
EDCO (2009); CS Unitec
(2009).
Vacuum, large capacity with HEPA..... ........................ N/A 2,108 \[d]\ 1.63 1,165.92 ICS (2009); EDCO
(2009); Aramsco
(2009).
Dust extraction kit (rotary hammers). ........................ N/A 215 \[d]\ 0.30 214.81 Grainger (2009);
mytoolstore (2009);
Toolmart (2009).
Dust control/quarry drill............ ........................ N/A N/A \[e]\ 17.33 N/A RSMeans Heavy
Construction Cost Data
(2008).
Dustless drywall sander.............. ........................ N/A 133 \[d]\ 0.19 133.33 Home Depot (2009); LSS
(2009); Dustless Tech
(2009).
Cab enclosure/w ventilation and air ........................ N/A 13,000 \[d]\ 2.59 1,850.91 Estimates from
conditioning. equipment suppliers
and retrofitters.
Foam dust suppression system......... ........................ N/A 14,550 \[e]\ 162.07 2,071.59 Midyette (2003).
Water tank, engine driven discharge, ........................ N/A N/A \[d]\ 121.50 N/A RSMeans (2008)--based
5000 gal.. on monthly rental
cost.
Tunnel dust suppression system ........................ N/A 7,928 \[e]\ 2.71 1,933.47 Raring (2003).
supplement.
Training instructor cost per hour ........................ N/A N/A 43.12 N/A Based on supervisor
(Construction). wage, adjusted for
fringe benefits (BLS,
2008, updated to 2009
dollars).
Value of worker time spent in class ........................ N/A N/A 22.22 N/A Based on worker wage,
(Construction). adjusted for fringe
benefits (BLS, 2008,
updated to 2009
dollars).
Warning signs (3 per regulated area) 25.30 per sign.......... N/A N/A 75.90 N/A Lab Safety Supply,
(Construction). 2010.
Per-worker costs for written access Weighted average annual 175.56
control plan or regulated area setup cost per worker;
implementation (Construction). Applies to workers with
exposures above the PEL.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\[a]\ For local exhaust ventilation (LEV), maintenance, and conveyor covers, OSHA applied the following estimates:
LEV: capital cost = $12.83 per cfm; operating cost = $3.51 per cfm; annualized capital cost = $1.83 per cfm; based on current energy prices and the
estimates of consultants to ERG (2013).
Maintenance: estimated as 10% of capital cost.
Conveyor Covers: estimated as $17.10 per linear foot for 100 ft. (Landola, 2003); capital cost = $19.95 per linear ft., including all hardware;
annualized capital cost = $2.84 per linear ft.
\[b]\ Adjusted from 2003 price levels using an inflation factor of 1.166, calculated as the ratio of average annual GDP Implicit Price Deflator for 2009
and 2003.
\[c]\ Mean expense per office-based physician visit to a pulmonary specialist for diagnosis and treatment, based on data from the 2004 Medical
Expenditure Panel Survey. Inflated to 2009 dollars using the consumer price inflator for medical services.
Costs for physical exams and tests, chest X-ray, and pulmonary tests are direct medical costs used in bundling services under Medicare (Intellimed
International, 2003). Costs are inflated by 30% to eliminate the effect of Medicare discounts that are unlikely to apply to occupational medicine
environments.
\[d]\ Daily maintenance and operating cost.
\[e]\ Daily equipment costs derived from RS Means (2008) monthly rental rates, which include maintenance and operating costs.
Source: U.S. Dept. of Labor, OSHA, Directorate of Standards and Guidance, Office of Regulatory Analysis, based on ERG (2013).
Federal Rules Which May Duplicate, Overlap, or Conflict With the
Proposed Rule.
OSHA has not identified any other Federal rules which may
duplicate, overlap, or conflict with the proposal, and requests
comments from the public regarding this issue.
1. Alternatives to the Proposed Rule which Accomplish the Stated
Objectives of Applicable Statutes and which Minimize any Significant
Economic Impact of the Proposed Rule on Small Entities
This section first discusses several provisions in the proposed
standard that OSHA has adopted or modified based on comments from small
entity representatives (SERs) during the SBREFA Panel process or on
recommendations made by the SBREFA Panel as potentially alleviating
impacts on small entities. Then, the Agency presents various regulatory
alternatives to the proposed OSHA silica standard.
a. Elements of Proposed Rule To Reduce Impacts on Small Entities
The SBREFA Panel was concerned that changing work conditions in the
construction industry would make it
difficult to apply some of the provisions that OSHA suggested at the
time of the Panel. OSHA has preliminarily decided to change its
approach in this sector. OSHA is proposing two separate standards, one
for general industry and maritime and one for construction. As
described earlier in this preamble, in construction, OSHA has provided
a table--labeled Table 1, Exposure Control Methods for Selected
Construction Operations--that for special operations enables the
employer to implement engineering controls, work practices, and
respiratory protection without the need for exposure assessment. Table
1 in the proposed construction standard presents engineering and work
practice controls and respiratory protection options for special
operations. Where employees perform the special operations listed in
the table and the employer has fully implemented the engineering
controls, work practices, and respiratory protection specified in the
table, the employer is not required to assess the exposure of employees
performing such operations.
As an alternative to the regulated area provision, OSHA is
proposing that employers be permitted the option of establishing
written access control plans that must contain provisions for a
competent person; procedures for notifying employees of the presence of
exposure to respirable crystalline silica and demarcating such areas
from the rest of the workplace; in multi-employer workplaces, the
methods for informing other employers of the presence and location of
areas where silica exposures may exceed the PEL; provisions for
limiting access to areas where silica exposures are likely; and
procedures for providing respiratory protection to employees entering
areas with controlled access. Further discussion on this alternative is
found in the Summary and Explanation for paragraph (e) Regulated Areas
and Access Control.
OSHA believes that, although the estimated per-worker cost for
written access control plans averages somewhat higher than the per-
worker cost for regulated areas ($199.29 per worker for the control
plans vs. $167.65 per worker for the regulated area), access control
plans may be significantly less costly and more protective than
regulated areas in certain work situations.
Some SERs were already applying many of the protective controls and
practices that would be required by the ancillary provisions of the
standard. However, many SERs objected to the provisions regarding
housekeeping, protective clothing, and hygiene facilities. For this
proposed rule, OSHA removed the requirement for hygiene facilities,
which has resulted in the elimination of compliance costs for change
rooms, shower facilities, lunch rooms, and hygiene-specific
housekeeping requirements. OSHA also restricted the provision for
protective clothing (or, alternatively, any other means to remove
excessive silica dust from work clothing) to situations where there is
the potential for employees' work clothing to become grossly
contaminated with finely divided material containing crystalline
silica.
b. Regulatory Alternatives
For the convenience of those persons interested only in OSHA's
regulatory flexibility analysis, this section repeats the discussion of
the various regulatory alternatives to the proposed OSHA silica
standard presented in the Introduction and in Section VIII.H of this
preamble.
Each regulatory alternative presented here is described and
analyzed relative to the proposed rule. Where appropriate, the Agency
notes whether the regulatory alternative, to be a legitimate candidate
for OSHA consideration, requires evidence contrary to the Agency's
findings of significant risk and feasibility. To facilitate comment,
the regulatory alternatives have been organized into four categories:
(1) Alternative PELs to the proposed PEL of 50 [mu]g/m\3\; (2)
regulatory alternatives that affect proposed ancillary provisions; (3)
a regulatory alternative that would modify the proposed methods of
compliance; and (4) regulatory alternatives concerning when different
provisions of the proposed rule would take effect.
Alternative PELs
OSHA is proposing a new PEL for respirable crystalline silica of 50
[mu]g/m\3\ for all industry sectors covered by the rule. OSHA's
proposal 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 of this preamble, 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 current PELs. These
analyses are presented in a background document entitled "Respirable
Crystalline Silica--Health Effects Literature Review and Preliminary
Quantitative Risk Assessment" and are summarized in this preamble in
Section V, Health Effects Summary, and Section VI, Summary of OSHA's
Preliminary Quantitative Risk Assessment, respectively. The available
evidence indicates that employees exposed to respirable crystalline
silica well below the current PELs are 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. As discussed in Section VII, Significance of
Risk, in this preamble, OSHA preliminarily finds that worker exposure
to respirable crystalline silica constitutes a significant risk and
that the proposed 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 proposed rule is presented in the Preliminary
Economic Analysis and Initial Regulatory Flexibility Analysis (PEA),
and is summarized in this section (Section VIII) of this preamble. For
general industry and maritime, OSHA has preliminarily concluded that
the proposed PEL of 50 [mu]g/m\3\ is technologically feasible for all
affected industries. For construction, OSHA has preliminarily
determined that the proposed PEL of 50 [mu]g/m\3\ is feasible in 10 out
of 12 of the affected activities. Thus, OSHA preliminarily concludes
that engineering and work practices will be sufficient to reduce and
maintain silica exposures to the proposed PEL of 50 [mu]g/m\3\ or below
in most operations most of the time in the affected industries. For
those few operations within an industry or activity where the proposed
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
proposed PEL.
OSHA developed quantitative estimates of the compliance costs of
the proposed 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 preliminarily concluded that compliance with the
requirements of the proposed 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 proposed rule. Under Regulatory Alternative 1, the
proposed PEL would be changed from 50 [mu]g/m\3\ to 100 [mu]g/m\3\ for
all industry sectors covered by the rule, and the action level would be
changed from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ (thereby keeping the action
level at one-half of the PEL). Under Regulatory Alternative 2,
the proposed PEL would be lowered from 50 [mu]g/m\3\ to 25 [mu]g/m\3\
for all industry sectors covered by the rule, while the action level
would remain at 25 [mu]g/m\3\ (because of difficulties in accurately
measuring exposure levels below 25 [mu]g/m\3\).
Tables VIII-31A and VIII-31B present, for informational purposes,
the estimated costs, benefits, and net benefits of the proposed rule
under the proposed 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 incremental benefits, and the incremental net
benefits of going from a PEL of 100 [mu]g/m\3\ to the proposed PEL of
50 [mu]g/m\3\ and then of going from the proposed PEL of 50 [mu]g/m\3\
to a PEL of 25 [mu]g/m\3\. Table VIII-31A breaks out costs by provision
and benefits by type of disease and by morbidity/mortality, while Table
VIII-31B breaks out costs and benefits by major industry sector.
[GRAPHIC] [TIFF OMITTED] TP12SE13.018
[GRAPHIC] [TIFF OMITTED] TP12SE13.019
As Tables VIII-31A and VIII-31B show, going from a PEL of 100
[mu]g/m\3\ to a PEL of 50 [mu]g/m\3\ would prevent, annually, an
additional 357 silica-related fatalities and an additional 632 cases of
silicosis. Based on its preliminary findings that the proposed PEL of 50 [mu]g/m\3\
significantly reduces worker risk from silica exposure (as demonstrated
by the number of silica-related fatalities and silicosis cases avoided)
and is both technologically and economically feasible, OSHA cannot
propose a PEL of 100 [mu]g/m\3\ (Regulatory Alternative 1)
without violating its statutory obligations under the OSH Act. However,
the Agency will consider evidence that challenges its preliminary
findings.
As previously noted, Tables VIII-31A and VIII-31B also show the
costs and 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 proposed 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 proposed rule).
As shown in Tables VIII-31A and VIII-31B, going from a PEL of 50
[mu]g/m\3\ to a PEL of 25 [mu]g/m\3\ would prevent, annually, an
additional 335 silica-related fatalities and an additional 186 cases of
silicosis. These estimates support OSHA's preliminarily finding that
there is significant risk remaining at the proposed PEL of 50 [mu]g/
m\3\. However, the Agency has preliminarily determined that a PEL of 25
[mu]g/m\3\ (Regulatory Alternative 2) is not technologically
feasible, and for that reason, cannot propose it without violating its
statutory obligations under the OSH Act.
Regulatory Alternatives That Affect Ancillary Provisions
The proposed rule contains several ancillary provisions (provisions
other the PEL), including requirements for exposure assessment, medical
surveillance, silica training, and regulated areas or access control.
As shown in Table VIII-31A, these ancillary provisions represent
approximately $223 million (or about 34 percent) of the total
annualized costs of the rule of $658 million (using a 7 percent
discount rate). The two most expensive of the ancillary provisions are
the requirements for medical surveillance, with annualized costs of $79
million, and the requirements for exposure monitoring, with annualized
costs of $74 million.
As proposed, the requirements for exposure assessment are triggered
by the action level. As described in the preamble, OSHA has defined the
action level for the proposed standard as an airborne concentration of
respirable crystalline silica of 25 [mu]g/m\3\ calculated as an eight-
hour time-weighted average. In this proposal, as in other standards,
the action level has been set at one-half of the PEL.
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 PEL on days when no exposure measurements are made. Even when all
measurements on a given day may fall below the PEL (but are above the
action level), there is some chance that on another day, when exposures
are not measured, the employee's actual exposure may exceed the PEL.
When exposure measurements are above the action level, the employer
cannot be reasonably confident 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.
The action level is also intended to encourage employers to lower
exposure levels in order to avoid the costs associated with the
exposure assessment provisions. Some employers would be able to reduce
exposures below the action level in all work areas, and other employers
in some work areas. As exposures are lowered, the risk of adverse
health effects among workers decreases.
OSHA's preliminary risk assessment indicates that significant risk
remains at the proposed PEL of 50 [mu]g/m\3\. Where there is continuing
significant risk, the decision in the Asbestos case (Bldg. and
Constr.Trades Dep't, AFL-CIO v. Brock, 838 F.2d 1258, 1274 (D.C. Cir.
1988)) indicated that OSHA should use its legal authority to impose
additional requirements on employers to further reduce risk when those
requirements will result in a greater than de minimis incremental
benefit to workers' health. OSHA's preliminary conclusion is that the
requirements triggered by the action level will result in a very real
and necessary, but non-quantifiable, further reduction in risk beyond
that provided by the PEL alone. OSHA's choice of proposing an action
level for exposure monitoring of one-half of the PEL is based on the
Agency's successful 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).
As specified in the proposed rule, all workers exposed to
respirable crystalline silica above the PEL of 50 [mu]g/m\3\ are
subject to the medical surveillance requirements. This means that the
medical surveillance requirements would apply to 15,172 workers in
general industry and 336,244 workers in construction. OSHA estimates
that 457 possible silicosis cases will be referred to pulmonary
specialists annually as a result of this medical surveillance.
OSHA has preliminarily determined that these ancillary provisions
will: (1) Help to ensure the PEL is not exceeded, and (2) minimize risk
to workers given the very high level of risk remaining at the PEL. OSHA
did not estimate, and the benefits analysis does not include, monetary
benefits resulting from early discovery of illness.
Because medical surveillance and exposure assessment are the two
most costly ancillary provisions in the proposed rule, the Agency has
examined four regulatory alternatives (named Regulatory Alternatives
3, 4, 5, and 6) involving changes
to one or the other of these ancillary provisions. These four
regulatory alternatives are defined below and the incremental cost
impact of each is summarized in Table VIII-32. In addition, OSHA is
including a regulatory alternative (named Regulatory Alternative
7) that would remove all ancillary provisions.
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Under Regulatory Alternative 3, the action level would be
raised from 25 [mu]g/m\3\ to 50 [mu]g/m\3\ while keeping the PEL at 50
[mu]g/m\3\. As a result, exposure monitoring requirements would be
triggered only if workers were exposed above the proposed PEL of 50
[mu]g/m\3\. As shown in Table VIII-32,
Regulatory Option 3 would reduce the annualized cost of the
proposed rule by about $62 million, using a discount rate of either 3
percent or 7 percent.
Under Regulatory Alternative 4, the action level would
remain at 25 [mu]g/m\3\ but medical surveillance would now be triggered
by the action level, not the PEL. As a result, medical surveillance
requirements would be triggered only if workers were exposed at or
above the proposed action level of 25 [mu]g/m\3\. As shown in Table
VIII-32, Regulatory Option 4 would increase the annualized
cost of the proposed rule by about $143 million, using a discount rate
of 3 percent (and by about $169 million, using a discount rate of 7
percent).
Under Regulatory Alternative 5, the only change to the
proposed rule would be to the medical surveillance requirements.
Instead of requiring workers exposed above the PEL to have a medical
check-up every three years, those workers would be required to have a
medical check-up annually. As shown in Table VIII-32, Regulatory Option
5 would increase the annualized cost of the proposed rule by
about $69 million, using a discount rate of 3 percent (and by about $66
million, using a discount rate of 7 percent).
Regulatory Alternative 6 would essentially combine the
modified requirements in Regulatory Alternatives 4 and
5. Under Regulatory Alternative 6, medical
surveillance would be triggered by the action level, not the PEL, and
workers exposed at or above the action level would be required to have
a medical check-up annually rather than triennially. The exposure
monitoring requirements in the proposed rule would not be affected. As
shown in Table VIII-32, Regulatory Option 6 would increase the
annualized cost of the proposed rule by about $342 million, using a
discount rate of either 3 percent or 7 percent.
OSHA is not able to quantify the effects of these preceding four
regulatory alternatives on protecting workers exposed to respirable
crystalline silica at levels at or below the proposed PEL of 50 [mu]g/
m\3\--where significant risk remains. The Agency solicits comment on
the extent to which these regulatory options may improve or reduce the
effectiveness of the proposed rule.
The final regulatory alternative affecting ancillary provisions,
Regulatory Alternative 7, would eliminate all of the ancillary
provisions of the proposed rule, including exposure assessment, medical
surveillance, training, and regulated areas or access control. However,
it should be carefully 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 do monitoring, train workers on the use of controls, and set up
some kind of regulated areas to indicate where respirator use would be
required. It is also likely that employers would increasingly follow
the many recommendations to provide medical surveillance for employees.
OSHA has not attempted to estimate the extent to which the costs of
these activities would be reduced if they were not formally required,
but OSHA welcomes comment on the issue.
As indicated previously, OSHA preliminarily finds that there is
significant risk remaining at the proposed PEL of 50 [mu]g/m\3\.
However, the Agency has also preliminarily determined that 50 [mu]g/
m\3\ is the lowest feasible PEL. Therefore, the Agency believes that it
is necessary to include ancillary provisions in the proposed rule to
further reduce the remaining risk. OSHA anticipates that these
ancillary provisions will reduce the risk beyond the reduction that
will be achieved by a new PEL alone.
OSHA's reasons for including each of the proposed ancillary
provisions are detailed in Section XVI of this preamble, Summary and
Explanation of the Standards. In particular, OSHA believes that
requirements for exposure assessment (or alternately, using specified
exposure control methods for selected construction operations) would
provide a basis for ensuring that appropriate measures are in place to
limit worker exposures. Medical surveillance is particularly important
because individuals exposed above the PEL (which triggers medical
surveillance in the proposed rule) are at significant risk of death and
illness. Medical surveillance would allow for identification of
respirable crystalline silica-related adverse health effects at an
early stage so that appropriate intervention measures can be taken.
OSHA believes that regulated areas and access control are important
because they serve to limit exposure to respirable crystalline silica
to as few employees as possible. Finally, OSHA believes that 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.
OSHA expects that the benefits estimated under the proposed rule
will not be fully achieved if employers do not implement the ancillary
provisions of the proposed rule. For example, OSHA believes that the
effectiveness of the proposed rule depends on regulated areas or access
control to further limit exposures and on medical surveillance to
identify disease cases when they do occur.
Both industry and worker groups have recognized that a
comprehensive standard 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 (ASTM, 2006; 2009; BCTD 2001). Moreover, as mentioned
previously, where there is continuing significant risk, the decision in
the Asbestos case (Bldg. and Constr. Trades Dep't, AFL-CIO v. Brock,
838 F.2d 1258, 1274 (DC Cir. 1988)) indicated that OSHA should use its
legal authority to impose additional requirements on employers to
further reduce risk when those requirements will result in a greater
than de minimis incremental benefit to workers' health. OSHA
preliminarily concludes that the additional requirements in the
ancillary provisions of the proposed standard clearly exceed this
threshold.
A Regulatory Alternative That Modifies the Methods of Compliance
The proposed standard in general industry and maritime would
require 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 would still
be required to implement them to reduce exposure as much as possible,
and to supplement them with a respiratory protection program. Under the
proposed construction standard, employers would be given two options for
compliance. The first option largely follows requirements for the
general industry and maritime proposed standard, while the second
option outlines, in Table 1 (Exposure Control Methods for Selected
Construction Operations) of the proposed rule, specific construction
exposure control methods. Employers choosing to follow OSHA's proposed
control methods would be considered to be in compliance with the
engineering and work practice control requirements of the proposed
standard, and would not be required to conduct certain exposure
monitoring activities.
One regulatory alternative (Regulatory Alternative 8)
involving methods of compliance would be to eliminate Table 1 as a
compliance option in the construction sector. Under this regulatory
alternative, OSHA estimates that there would be no effect on estimated
benefits but that the annualized costs of complying with the proposed
rule (without the benefit of the Table 1 option in construction) would
increase by $175 million, totally in exposure monitoring costs, using a
3 percent discount rate (and by $178 million using a 7 percent discount
rate), so that the total annualized compliance costs for all affected
establishments in construction would increase from $495 to $670 million
using a 3 percent discount rate (and from $511 to $689 million using a
7 percent discount rate).
Regulatory Alternatives That Affect the Timing of the Standard
The proposed rule would become effective 60 days following
publication of the final rule in the Federal Register. Provisions
outlined in the proposed standard would become enforceable 180 days
following the effective date, with the exceptions of engineering
controls and laboratory requirements. The proposed rule would require
engineering controls to be implemented no later than one year after the
effective date, and laboratory requirements would be required to begin
two years after the effective date.
One regulatory alternative (Regulatory Alternative 9)
involving the timing of the standard would arise if, contrary to OSHA's
preliminary findings, a PEL of 50 [micro]g/m\3\ with an action level of
25 [micro]g/m\3\ were found to be technologically and economically
feasible some time in the future (say, in five years), but not feasible
immediately. In that case, OSHA might issue a final rule with a PEL of
50 [micro]g/m\3\ and an action level of 25 [micro]g/m\3\ to take effect
in five years, but at the same time issue an interim PEL of 100
[micro]g/m\3\ and an action level of 50 [micro]g/m\3\ to be in effect
until the final rule becomes feasible. Under this regulatory
alternative, and consistent with the public participation and "look
back" provisions of Executive Order 13563, the Agency could monitor
compliance with the interim standard, review progress toward meeting
the feasibility requirements of the final rule, and evaluate whether
any adjustments to the timing of the final rule would be needed. Under
Regulatory Alternative 9, the estimated costs and benefits
would be somewhere between those estimated for a PEL of 100 [micro]g/
m\3\ with an action level of 50 [micro]g/m\3\ and those estimated for a
PEL of 50 [micro]g/m\3\ with an action level of 25 [micro]g/m\3\, the
exact estimates depending on the length of time until the final rule is
phased in. OSHA emphasizes that this regulatory alternative is contrary
to the Agency's preliminary findings of economic feasibility and, for
the Agency to consider it, would require specific evidence introduced
on the record to show that the proposed rule is not now feasible but
would be feasible in the future.
Although OSHA did not explicitly develop or quantitatively analyze
any other regulatory alternatives involving longer-term or more complex
phase-ins of the standard (possibly involving more delayed
implementation dates for small businesses), OSHA is soliciting comments
on this issue. Such a particularized, multi-year phase-in would have
several advantages, especially from the viewpoint of impacts on small
businesses. First, it would reduce the one-time initial costs of the
standard by spreading them out over time, a particularly useful
mechanism for small businesses that have trouble borrowing large
amounts of capital in a single year. A differential phase-in for
smaller firms would also aid very small firms by allowing them to gain
from the control experience of larger firms. A phase-in would also be
useful in certain industries--such as foundries, for example--by
allowing employers to coordinate their environmental and occupational
safety and health control strategies to minimize potential costs.
However a phase-in would also postpone the benefits of the standard.
As previous discussed in the Introduction and in Section VIII.H of
this preamble, OSHA requests comments on these regulatory alternatives,
including the Agency's choice of regulatory alternatives (and whether
there are other regulatory alternatives the Agency should consider) and
the Agency's analysis of them.
SBREFA Panel
Table VIII-33 lists all of the SBREFA Panel recommendations and
OSHA's responses to these recommendations.
Table VIII-33--SBREFA Panel Recommendations and OSHA Responses
------------------------------------------------------------------------
SBREFA Panel recommendation OSHA response
------------------------------------------------------------------------
The Panel recommended that OSHA give As discussed in Chapter II of
consideration to the alternative of the PEA, Need for Regulation
improved enforcement of and expanded (and summarized in Section
outreach for the existing rule rather VIII.B of this Preamble), OSHA
than a new rule. In addition, the has reviewed existing
Panel recommended that OSHA carefully enforcement and outreach
study the effects of existing programs, as well as other
compliance and outreach efforts, such legal and administrative
as the Special Emphasis Program on remedies, and believes that a
silica, with a view to better standard would be the most
delineating the effects of such effective means to protect
efforts. This examination should workers from exposure to
include (1) a year-by-year analysis of silica.
the extent of noncompliance discovered A review of OSHA's compliance
in OSHA compliance inspections, and assistance efforts and an
(2) the kinds of efforts OSHA made to analysis of compliance with
improve enforcement and outreach. the current PELs for
respirable crystalline silica
are discussed in Section III
of the preamble, Events
Leading to the Proposed
Standard.
(General Industry) The Panel OSHA has reviewed its cost
recommended that OSHA revise its estimates in response to the
economic and regulatory flexibility comments received from the
analyses as appropriate to reflect the SERs and evaluated the
SERs' comments on underestimation of alternative estimates and
costs, and that the Agency compare methodologies suggested by the
OSHA's revised estimates to SERs. In some cases (such as
alternative estimates provided and for exposure monitoring and
methodologies suggested by the SERs. training) OSHA has revised its
For those SER estimates and cost estimates in response to
methodological suggestions that OSHA SER comments. However, OSHA
does not adopt, the Panel recommends has not made all cost changes
that OSHA explain its reasons for suggested by the SERs, but has
preferring an alternative estimate and retained (or simply updated)
solicit comment on the issue. those cost estimates that OSHA
determined reflect sound
methodology and reliable data.
OSHA requests comments on the
Agency's estimated costs and
on the assumptions applied in
the cost analysis, and has
included this topic in Section
I. Issues (See Compliance
Costs) and in Chapter V of the
PEA.
The Panel recommended that, as time OSHA has extensively reviewed
permits, OSHA revise its economic and its costs estimates, changed
regulatory flexibility analyses as many of them in response to
appropriate to reflect the SERs' SER comments, and solicits
comments on underestimation of costs comments on these revised cost
and that the Agency compare the OSHA estimates. A few examples of
revised estimates to alternative OSHA's cost changes are given
estimates provided and methodologies in the responses to specific
suggested by the SERs. For those SER issues below (e.g., exposure
estimates and methodological monitoring, medical exams,
suggestions that OSHA does not adopt, training and familiarization).
the Panel recommends that OSHA explain OSHA requests comments on the
its reasons for preferring an Agency's estimated costs and
alternative estimate and solicit on the assumptions applied in
comment on the issue. the cost analysis, and has
included this topic in Section
I. Issues (See Compliance
Costs) and in Chapter V of the
PEA.
The Panel recommended that prior to The PEA reflects OSHA's
publishing a proposed standard, OSHA judgment on technological
should carefully consider the ability feasibility and includes
of each potentially affected industry responses to specific issues
to meet any proposed PEL for silica, raised by the Panel and SERs.
and that OSHA should recognize, and OSHA solicits comment on the
incorporate in its cost estimates, accuracy and reasonableness of
specific issues or hindrances that these judgments and has
different industries may have in included this topic in Section
implementing effective controls. I. Issues (See Technological
and Economic Feasibility of
the Proposed PEL and
Compliance Costs).
The Panel recommended that OSHA Table 1 in the proposed
carefully review the basis for its standard is designed to
estimated exposure monitoring costs, relieve establishments in
consider the concerns raised by the construction from requirements
SERs, and ensure that its estimates for exposure assessment when
are revised, as appropriate, to fully certain controls are
reflect the costs likely to be established. OSHA developed
incurred by potentially affected cost estimates in the PEA for
establishments. exposure monitoring as a
function of the size of the
establishment. OSHA's cost
estimates now reflect the fact
that smaller entities will
tend to experience larger unit
costs. OSHA estimated higher
exposure monitoring costs for
small entities because an
industrial hygienist could not
take as many samples a day in
a small establishment as in a
large one. OSHA believes that
its unit cost estimates for
exposure monitoring are
realistic but will raise that
as an issue. See Chapter V of
the PEA for details of OSHA's
unit costs for exposure
monitoring in general industry
and maritime.
The Panel recommended that OSHA OSHA's cost estimates for
carefully review the basis for its health screening are a
estimated health screening compliance function of the size of the
costs, consider the concerns raised by establishment. OSHA's cost
the SERs, and ensure that its estimates now reflect the fact
estimates are revised, as appropriate, that smaller entities will
to fully reflect the costs likely to tend to experience larger unit
be incurred by potentially affected costs. OSHA estimated higher
establishments. medical surveillance costs
(than was estimated in the
Preliminary Initial Regulatory
Flexibility Analysis (PIRFA))
for small entities because
smaller establishments would
be more likely to send the
workers off-site for medical
testing. In addition, OSHA
significantly increased the
total costs of exposure
sampling and x-rays in medical
surveillance by assuming no
existing compliance with the
those provisions in the
proposed rule (as compared to
an average of 32.6 percent and
34.8 percent existing
compliance, respectively, in
the PIRFA).
(Construction) The Panel recommended OSHA removed the specific
that OSHA carefully review the basis hygiene provisions in the
for its estimated hygiene compliance proposed rule, which has
costs, consider the concerns raised by resulted in the elimination of
the SERs, and ensure that its compliance costs for changing
estimates are revised, as appropriate, rooms, shower facilities,
to fully reflect the costs likely to lunch rooms, and hygiene-
be incurred by potentially affected specific housekeeping
establishments. requirements. However, OSHA
has retained requirements and
cost estimates for disposable
clothing (in regulated areas)
where there is the potential
for employees' work clothing
to become grossly contaminated
with finely divided material
containing crystalline silica.
The Panel recommended that OSHA Dry sweeping remains a
carefully review the issue of dry prohibited activity in the
sweeping in the analysis, consider the proposed standard and OSHA has
concerns raised by the SERs, and estimated the costs for the
ensure that its estimates are revised, use of wet methods to control
as appropriate, to fully reflect the dust (see Table VIII-30,
costs likely to be incurred by above). OSHA requests comment
potentially affected establishments. on the use of wet methods as a
substitute for dry sweeping
and has included this topic in
Section I. Issues (See
Compliance Costs and
Provisions of the Standards--
Methods of compliance).
The Panel recommended that OSHA One participant in the silica
carefully review the basis for its SBREFA process objected to
training costs, consider the concerns ERG's analytical assumption
raised by the SERs, and ensure that (used in OSHA's Preliminary
its estimates are revised, as Initial Regulatory Flexibility
appropriate, to fully reflect the Analysis) that training is
costs likely to be incurred by needed only for those workers
potentially affected establishments. exposed above the action level
and suggested that training
might be necessary for all at-
risk workers. For the proposed
rule, the scope of this
requirement was revised so
that the provision now would
apply to workers with any
potential occupational
exposure to respirable
crystalline silica; OSHA has
estimated training costs in
the PEA accordingly.
OSHA estimated higher training
costs for small entities
because of smaller-sized
training classes and
significantly increased
training costs by assuming
only half compliance for half
of the affected establishments
(compared to an average of 56
percent existing compliance
for all establishments in the
PIRFA).
(Construction) SERs raised cost issues The cost estimates in the PEA
similar to those in general industry, reflect OSHA's best judgment
but were particularly concerned about and take the much higher labor
the impact in construction, given the turnover rates in construction
high turnover rates in the industry. into account when calculating
The Panel recommended that OSHA costs. For the proposed rule,
carefully review the basis for its OSHA used the most recent BLS
estimated compliance costs, consider turnover rate of 64 percent
the concerns raised by the SERs, and for construction (versus a
ensure that its estimates are revised, turnover rate of 27.2 percent
as appropriate, to fully reflect the for general industry). OSHA
costs likely to be incurred by believes that the estimates in
potentially affected establishments. the PEA capture the effect of
high turnover rates in
construction and solicits
comments on this issue in
Section I. Issues (See
Compliance Costs).
(Construction) The Panel recommended OSHA used the exposure profiles
that OSHA (1) carefully review the to estimate the number of full-
basis for its estimated labor costs, time-equivalent (FTE) workers
and issues related to the use of FTEs in construction who are
in the analysis, (2) consider the exposed above the PEL. This
concerns raised by the SERs, and (3) would be the exposure profile
ensure that its estimates are revised, if all exposed workers worked
as appropriate, to fully reflect the full-time only at the
costs likely to be incurred by specified silica-generating
potentially affected establishments. tasks. In OSHA's analysis, the
actual number of workers
exposed above the PEL is
represented by two to five
times the number of FTE
workers, depending on the
activity. The estimate of the
total number of at-risk
workers takes into account the
fact that most workers,
regardless of construction
occupation, spend some time
working on jobs where no
silica contamination is
present. For the control cost
analysis, however, it matters
only how many worker-days
there are in which exposures
are above the PEL. These are
the worker-days in which
controls are required. The
control costs (as opposed to
the program costs) are
independent of the number of
at-risk workers associated
with these worker-days. OSHA
emphasizes that the use of
FTEs does not "discount" its
estimates of aggregate control
costs.
(Construction) Some SERs requested that A 30-day exemption from the
OSHA apply a 30-day exclusion for requirement to implement
implementing engineering and work engineering and work practice
practice controls, as was reflected in controls was not included in
the draft standard for general the proposed standard for
industry and maritime. construction, and has been
The Panel recommended that OSHA removed from the proposed
consider this change and request standard for general industry.
comment on the appropriateness of OSHA requests comment on a 30-
exempting operations that are day exemption, and has
conducted fewer than 30 days per year included this topic in Section
from the hierarchy requirement. I. Issues (See Provisions of
the Standards--Methods of
compliance).
(Construction) The Panel recommended The proposed prohibition on
that OSHA consider and seek comment on rotation is explained in the
the need to prohibit employee rotation Summary and Explanation for
as a means of complying with the PEL paragraph (f) Methods of
and the likelihood that employees Compliance. OSHA solicits
would be exposed to other serious comment on the prohibition of
hazards if the Agency were to retain employee rotation to achieve
this provision. compliance when exposure
levels exceed the PEL, and has
included this topic in Section
I. Issues (See Provisions of
the Standards--Methods of
compliance).
(Construction) Some SERs questioned the As discussed in the Summary and
scientific and legal basis for the Explanation of paragraph (f)
draft prohibitions on the use of Methods of Compliance, the
compressed air, brushing, and dry prohibition against the use of
sweeping of silica-containing debris. compressed air, brushing, and
Others raised feasibility concerns dry sweeping applies to
such as in instances where water or situations where such
electric power was unavailable or activities could contribute to
where use of wet methods could damage employee exposure that exceeds
construction materials. the PEL. OSHA solicits comment
The Panel recommended that OSHA on this issue, and has
carefully consider the need for and included this topic in Section
feasibility of these prohibitions I. Issues (See Provisions of
given these concerns, and that OSHA the Standards--Methods of
seek comment on the appropriateness of compliance).
such prohibitions.
(Construction) The Panel recommended As described in the Summary and
that OSHA carefully consider whether Explanation for paragraph (e)
regulated area provisions should be Regulated Areas and Access
included in the draft proposed Control, the proposed standard
standard, and, if so, where and how includes a provision for
regulated areas are to be established. implementation of "access
OSHA should also clarify in the control plans" in lieu of
preamble and in its compliance establishing regulated areas.
assistance materials how compliance is Clarification for establishing
expected to be achieved in the various either a regulated area or an
circumstances raised by the SERs. access control plan is
provided in the Summary and
Explanation.
(Construction) The Panel recommended The Summary and Explanation for
that OSHA clarify how the regulated paragraph (e) Regulated Areas
area requirements would apply to multi- and Access Control clarifies
employer worksites in the draft this requirement. OSHA
standard or preamble, and solicit requests comment on this
comments on site control issues. topic, and has included this
topic in Section I. Issues
(See Compliance Costs and
Provisions of the Standards--
Methods of compliance).
(Construction) Many SERs were concerned OSHA has made a preliminary
with the extent to which they felt the determination that compliance
draft proposed standard would require with the proposed PEL can be
the use of respirators in construction achieved in most operations
activities. most of the time through the
The Panel recommended that OSHA use of engineering and work
carefully consider its respiratory practice controls. However, as
protection requirements, the described in the Summary and
respiratory protection requirements in Explanation of paragraphs (f)
Table 1, and the PEL in light of this Methods of Compliance and (g)
concern. Respiratory Protection and in
the Technological Feasibility
chapter of the PEA, use of
respiratory protection will be
required for some operations.
OSHA solicits comment on this
issue in Section I. Issues
(See Technological and
Economic Feasibility of the
Proposed PEL).
(Construction) The Panel recommended OSHA discusses the reliability
that OSHA carefully address the issues of measuring respirable
of reliability of exposure measurement crystalline silica in the
for silica and laboratory Technological Feasibility
requirements. The Panel also chapter of the PEA. An
recommended that OSHA seek approaches exemption for monitoring is
to a construction standard that can also provided where the
mitigate the need for extensive employer uses Table 1. As
exposure monitoring to the extent discussed in the Summary and
possible. Explanation for paragraph (d)
Exposure Assessment, the
proposed standard also allows
a performance option for
exposure assessment that is
expected to reduce the amount
of monitoring needed. OSHA
solicits comment on this topic
in Section I. Issues (See
Provisions of the Standards--
Exposure Assessment).
(Construction) As in general industry, As described in the Summary and
many SERs were concerned about all of Explanation for paragraph (e)
these provisions because, they Regulated Areas and Access
contended, silica is not recognized as Control, OSHA has proposed a
either a take-home or dermal hazard. limited requirement for use of
Further, many said that these protective clothing or other
provisions would be unusually means to remove silica dust
expensive in the context of from contaminated clothing.
construction work. Other SERs pointed This requirement would apply
out that protective clothing could only in regulated areas where
lead to heat stress problems in some there is the potential for
circumstances. work clothing to become
The Panel recommended that OSHA grossly contaminated with
carefully re-examine the need for silica dust. No requirement
these provisions in the construction for hygiene facilities is
industry and solicit comment on this included in the proposed
issue. standard. OSHA solicits
comment regarding appropriate
requirements for use of
protective clothing and
hygiene facilities in Section
I. Issues (See Provisions of
the Standards--Regulated areas
and access control).
(Construction) The Panel recommended The provisions requiring B-
that OSHA explicitly examine the issue readers and pulmonary
of availability of specialists called specialists are discussed in
for by these provisions, and re- the Summary and Explanation of
examine the costs and feasibility of paragraph (n) Medical
such requirements based on their Surveillance, and the numbers
findings with respect to availability, of available specialists are
as needed. reported. OSHA solicits
comment on this issue in
Section I. Issues (See
Provisions of the Standards--
Medical surveillance).
(Construction) The Panel recommended As described in the Summary and
that OSHA carefully consider the need Explanation for paragraph (n)
for pre-placement physicals in Medical Surveillance, an
construction, the possibility of initial examination is
delayed initial screening (so only required within 30 days after
employees who had been on the job a initial assignment to a job
certain number of days would be with exposure above the action
required to have initial screening), level for more than 30 days
and solicit comment on this issue. per year. OSHA solicits
comment on this proposed
requirement in Section I.
Issues (See Provisions of the
Standards--Medical
surveillance).
(Construction) Like the general The proposed standard does not
industry SERs, construction SERs specify wording for labels.
raised the issue that they would OSHA solicits comment on this
prefer a warning label with wording issue in Section I. Issues
similar to that used in asbestos and (See Provisions of the
lead. Standards--Hazard
The Panel recommended that OSHA communication).
consider this suggestion and solicit
comment on it.
(Construction) Some SERs questioned The proposed standard requires
whether hazard communication hazard communication for
requirements made sense on a employees who are potentially
construction site where there are tons exposed to respirable
of silica-containing dirt, bricks, and crystalline silica. Many of
concrete. the proposed requirements are
The Panel recommended OSHA consider how already required by OSHA's
to address this issue in the context Hazard Communication Standard.
of hazard communication. The Agency requests comment on
the proposed requirements in
Section I. Issues (See
Provisions of the Standards--
Hazard communication).
(Construction) The Panel recommended OSHA has reviewed the
that OSHA carefully review the recordkeeping requirements as
recordkeeping requirements with required by the Paperwork
respect to both their utility and Reduction Act. Detailed
burden. analysis of the recordkeeping
requirements can be found in
OSHA's information collection
request submitted to OMB.
The recordkeeping requirements
are discussed in the Summary
and Explanation for paragraph
(j) Recordkeeping. OSHA
solicits comment on these
requirements in Section I.
Issues (See Provisions of the
Standards--Recordkeeping).
The Panel recommended that OSHA, to the OSHA has prepared the PEA using
extent permitted by the availability the most current economic data
of economic data, update economic data available.
to better reflect recent changes in
the economic status of the affected
industries consistent with its
statutory mandate.
SERs in construction, and some in The scope of the proposed
general industry, felt the estimate of standard is discussed in the
affected small entities and employees Summary and Explanation for
did not give adequate consideration to paragraph (a) Scope and
workers who would be subject to Application.
exposure at a site but were not
directly employed by firms engaged in
silica-associated work, such as
employees of other subcontractors at a
construction site, visitors to a
plant, etc.
The Panel recommended that OSHA
carefully examine this issue,
considering both the possible costs
associated with such workers, and ways
of clarifying what workers are covered
by the standard
The Panel recommended that OSHA clarify The relationship between the
in any rulemaking action how its proposed rule and EPA
action is or is not related to requirements is discussed in
designating silica-containing Section XVI, Environmental
materials as hazardous wastes. Impacts.
Some SERs also noted the issue that the Silica wastes are not
use of wet methods in some areas may classified as hazardous.
violate EPA rules with respect to Therefore OSHA believes that
suspended solids in runoff unless the incremental disposal costs
provision is made for recycling or resulting from dust collected
settling the suspended solids out of in vacuums and other sources
the water. are likely to be quite small.
The Panel recommended that OSHA An analysis of wet methods for
investigate this issue, add dust controls suggests that in
appropriate costs if necessary, and most cases the amount of
solicit comment on this issue. slurry discharged are not
sufficient to cause a run off
to storm drains. OSHA solicits
comments on this topic in
Section I. Issues (See
Environmental Impacts).
The Panel recommended that OSHA (1) A review of OSHA's outreach
carefully consider and solicit comment efforts is provided in Section
on the alternative of improved III, Events Leading to the
outreach and support for the existing Proposed Standards. OSHA
standard; (2) examine what has and has solicits comment on this topic
not been accomplished by existing in Section I. Issues (See
outreach and enforcement efforts; and Alternatives/Ways to Simplify
(3) examine and fully discuss the need a New Standard).
for a new standard and if such a
standard can accomplish more than
improved outreach and enforcement.
The Panel recommended, if there is to OSHA has made a preliminary
be a standard for construction, that determination that compliance
OSHA: (1) seek ways to greatly with the proposed PEL can be
simplify the standard and restrict the achieved in most operations
number of persons in respirators; (2) most of the time through the
consider the alternative of a standard use of engineering and work
oriented to engineering controls and practice controls. However, as
work practices in construction; and described in the Summary and
(3) analyze and solicit comment on Explanation of paragraphs (f)
ways to simplify the standard. Methods of Compliance and (g)
Respiratory Protection and in
the Technological Feasibility
chapter of the PEA, use of
respiratory protection will be
required for some operations.
OSHA solicits comment on this
topic in Section I. Issues
(See Technological and
Economic Feasibility of the
Proposed PEL). OSHA also
solicits comment on ways to
simplify the standard in
Section I. Issues (See
Alternatives/Ways to Simplify
a New Standard).
The Panel recommended that, if there is As discussed in the Summary and
to be a standard, OSHA consider and Explanation for paragraph (c)
solicit comment on maintaining the Permissible Exposure Limit
existing PEL. The Panel also (PEL), OSHA has made a
recommends that OSHA examine each of preliminary determination that
the ancillary provisions on a the proposed PEL is necessary
provision-by-provision basis in light to meet the legal requirements
of the comments of the SERs on the to reduce significant risk to
costs and lack of need for some of the extent feasible. Because
these provisions. the proposed PEL is a fixed
value, OSHA also believes it
is easier to understand when
compared to the current PEL.
OSHA solicits comment on the
proposed PEL in Section I.
Issues (See Provisions of the
Standards--PEL and action
level).
(General Industry) The Panel The PEA reflects OSHA's
recommended that OSHA carefully judgment on the technological
examine the technological and economic and economic feasibility of
feasibility of the draft proposed the proposed standard and
standard in light of these SER includes responses to specific
comments. issues raised by the Panel.
OSHA solicits comment on the
accuracy and reasonableness of
these judgments in Section I.
Issues (See Technological and
Economic Feasibility of the
Proposed PEL).
(General Industry) Some SERs were OSHA has proposed to limit the
concerned that the prohibition on dry prohibition on dry sweeping to
sweeping was not feasible or cost situations where this activity
effective in their industries. could contribute to exposure
The Panel recommended that OSHA that exceeds the PEL. The
consider this issue and solicit Agency solicits comment on
comment on the costs and necessity of this topic in Section I.
such a prohibition. Issues (See Provisions of the
Standards--Methods of
compliance).
(General Industry) The Panel Proposed regulated area
recommended that OSHA carefully provisions are explained in
consider whether regulated area the Summary and Explanation
provisions should be included in the for paragraph (e) Regulated
draft proposed standard, and, if so, Areas and Access Control. The
where and how regulated areas are to proposed standard also
be established. OSHA should also includes a provision for
clarify in the preamble and in its implementation of "access
compliance assistance materials how control plans" in lieu of
compliance is expected to be achieved establishing regulated areas.
in the various circumstances raised by Clarification for establishing
the SERs. an access control plan is
provided in the Summary and
Explanation.
(General Industry) The Panel OSHA has made a preliminary
recommended that OSHA carefully determination in the proposed
examine the issues associated with rule that only certain
reliability of monitoring and sampling and analytical
laboratory standards in light of the methods can be used to measure
SER comments, and solicit comment on airborne crystalline silica at
these issues. the proposed PEL. Issues
related to sampling and
analytical methods are
discussed in the Technological
Feasibility section of the
PEA. OSHA solicits comment on
the Agency's preliminary
determination in Section I.
Issues (See Provisions of the
Standards--Exposure
Assessment).
(General Industry) Some SERs preferred The proposed standard provides
the more performance-oriented Option 2 two options for periodic
provision included in the draft exposure assessment; (1) a
exposure assessment requirements, fixed schedule option, and (2)
stating that fixed-frequency exposure a performance option. The
monitoring can be unnecessary and performance option provides
wasteful. However, other SERs employers flexibility in the
expressed concern over whether such a methods used to determine
performance-oriented approach would be employee exposures, but
consistently interpreted by requires employers to
enforcement officers. accurately characterize
The Panel recommended that OSHA employee exposures. The
continue to consider Option 2 but, proposed approach is explained
should OSHA decide to include it in a in the Summary and Explanation
proposed rule, clarify what would for paragraph (d) Exposure
constitute compliance with the Assessment. OSHA solicits
provision. Some SERs were also comments on the proposed
concerned about the wording of the exposure assessment provision
exposure assessment provision. in Section I. Issues (See
Provisions of the Standards--
Exposure Assessment).
(General Industry) Some SERs were also
concerned about the wording of the
exposure assessment provision of the
draft proposed standard. These SERs
felt that the wording could be taken
to mean that an employer needed to
perform initial assessments annually.
The Panel recommended that OSHA clarify The requirement for initial
this issue. exposure assessment is
clarified in the Summary and
Explanation of paragraph (d)
Exposure Assessment. The term
"initial" indicates that
this is the first action
required to assess exposure
and is required only once.
(General Industry) While some SERs As described in the Summary and
currently provide both protective Explanation for paragraph (e)
clothing and hygiene facilities, Regulated Areas and Access
others provide neither. Those SERs Control, OSHA has proposed a
that do not currently provide either limited requirement for use of
felt that these provisions were both protective clothing or other
highly expensive and unnecessary. Some means to remove silica dust
SERs stated that these provisions were from contaminated clothing.
pointless because silica is not a take- This requirement would apply
home hazard or a dermal hazard. Others only in regulated areas where
suggested that such provisions only be there is the potential for
required when the PEL is exceeded. work clothing to become
The Panel recommended that OSHA grossly contaminated with
carefully consider the need for these silica dust. No requirement
provisions, and solicit comment on the for hygiene facilities is
need for these provisions, and how included in the proposed
they might be limited. standard. OSHA solicits
comment regarding appropriate
requirements for use of
protective clothing and
hygiene facilities in Section
I. Issues (See Provisions of
the Standards--Regulated areas
and access control).
(General Industry) The SER comments OSHA has considered these
included several suggestions regarding comments and revised the
the nature and wording of the health proposed standard where
screening requirements. (See, e.g., appropriate. The revisions are
OSHA, 2003, pp. 25-28.). discussed in the Summary and
The Panel recommended that OSHA Explanation of paragraph (n)
consider revising the standard in Medical Surveillance.
light of these comments, as
appropriate.
(General Industry) The Panel The provisions requiring B-
recommended that OSHA explicitly readers and pulmonary
examine and report on the availability specialists are discussed in
of specialists called for by these the Summary and Explanation of
provisions, and re-examine the costs paragraph (n) Medical
and feasibility of such requirements Surveillance, and the numbers
based on their findings with respect of available specialists are
to availability, as needed. reported. OSHA solicits
comment on this topic in
Section I. Issues (See
Provisions of the Standards--
Medical surveillance).
(General Industry) Though the provision OSHA has preliminarily
for hazard communication simply determined to rely on the
repeats such provisions already in provisions of the Hazard
existence, some SERs urged OSHA to use Communication Standard (HCS)
this opportunity to change the in the proposed rule. The HCS
requirement so that warning labels requires labels for mixtures
would only be required of substances that contain more than 0.1% of
that were more than 1% (rather than a carcinogen. OSHA solicits
the current 0.1%) by weight of silica. comment on this topic in
Section I. Issues (See
Provisions of the Standards--
Medical surveillance).
The Panel recommended that OSHA
consider this suggestion and solicit
comment on it.
(General Industry) The Panel The recordkeeping requirements
recommended that OSHA carefully review are discussed in the Summary
the recordkeeping requirements with and Explanation for paragraph
respect to both their utility and (j) Recordkeeping. OSHA
burden. solicits comment on these
requirements in Section I.
Issues (See Provisions of the
Standards--Recordkeeping).
(Construction) The Panel recommended OSHA has made the preliminary
that OSHA continue to evaluate the determination that scope
appropriateness of and consider Option 1 is most appropriate.
modifications to scope Option 2 that OSHA solicits comment on this
can more readily serve to limit the subject in Section I. Issues
scope of the standard. (See Provisions of the
Standards--Scope).
(Construction) Many SERs found the The standard requires a
requirements for a competent person competent person only in
hard to understand. Many SERs took the limited circumstances when an
competent person requirement as employer selects the option to
requiring a person with a high level implement an "access control
of skills, such as the ability to plan" in lieu of establishing
conduct monitoring. Other SERs said a regulated area. Further
this requirement would require clarification is provided in
training a high percentage of their the Summary and Explanation of
employees as competent persons because paragraph (e) Regulated Areas
they typically had many very small and Access Control.
crews at many sites. In general, the
SERs thought this requirement as
written would be difficult to comply
with and costly.
The Panel recommended that OSHA seek
ways to clarify OSHA's intent with
respect to this requirement and more
clearly delineate the responsibilities
of competent persons.
(Construction) Many SERs did not
understand that Table 1 was offered as
an alternative to exposure assessment
and demonstration that the PEL is
being met. Some SERs, however,
understood the approach and felt that
it had merit. These SERs raised
several issues concerning the use of
Table 1, including:.
The Table should be expanded
to include all construction activities
covered by the standard, or the scope
of the standard should be reduced to
only those activities covered by Table
1;.
The control measures endorsed
in Table 1 need to be better
established, as necessary; and.
Table 1 should require less
use of, and possibly no use of,
respirators.
The Panel recommended that OSHA The rationale for the
carefully consider these suggestions, operations and control
expand Table 1, and make other measures to be included in
modifications, as appropriate Table 1 is provided in the
Summary and Explanation for
paragraph (f) Methods of
Compliance. Table 1 includes
some operations for which it
is anticipated that even with
the implementation of control
measures, exposure levels will
routinely exceed the proposed
PEL, and thus reliance on the
use of respiratory protection
is appropriate. Table 1 has
been modified to limit
requirements for respirator
use where operations are
performed for less than 4
hours per day. OSHA solicits
comment on the proposed
requirements in Section I.
Issues (See Provisions of the
Standards--Methods of
compliance).
The Panel recommends that OSHA OSHA significantly expanded its
thoroughly review the economic impacts economic impact and economic
of compliance with a proposed silica feasibility analyses in
standard and develop more detailed Chapter VI of the PEA. As part
feasibility analyses where of the impact analysis, OSHA
appropriate.. added data on normal year-to-
year variations in prices and
profit rates in affected
industries to provide a
context for evaluating
potential price and profit
impacts of the proposed rule.
A section was also added to
estimate the potential
international trade impacts of
the proposed rule. OSHA
solicits comments in Chapter
VI of the PEA on the issues of
the economic impacts and the
economic feasibility of the
proposed rule.
(Construction) The panel recommends OSHA re-examined and updated
that OSHA re-examine its cost its cost estimates for each
estimates for respirators to make sure type of respirator. Unit
that the full cost of putting respirator costs included the
employees in respirators is considered. cost of the respirator itself
and the annualized cost of
respirator use, to include
accessories (e.g., filters),
training, fit testing, and
cleaning. All costs were
updated to 2009 dollars. In
addition, OSHA added a cost
for employers to establish a
respirator program. OSHA
solicits comments on this
issue in Chapter V of the PEA.
(Construction) Some SERs indicated that To reflect the fact that an
the unit costs were underestimated for industrial hygienist could not
monitoring, similar to the general typically take as many samples
industry issues raised previously. In a day in a small establishment
addition, special issues for as in a large one, OSHA
construction were raised (i.e., developed cost estimates for
unpredictability of exposures), exposure monitoring as a
suggesting the rule would be costly, function of the size of the
if not impossible to comply with. establishment. OSHA's cost
The Panel recommends that OSHA estimates therefore now
carefully review the basis for its reflect the fact that smaller
estimated compliance costs, consider entities will tend to
the concerns raised by the SERs, and experience larger unit costs
ensure that its estimates are revised, for exposure monitoring.
as appropriate, to fully reflect the To reflect possible problems of
costs likely to be incurred by unpredictability of exposure
potentially affected establishments. in construction, Table 1 in
the proposed standard has been
designed to allow
establishments in construction
the option, for certain
operations, to implement
engineering controls, work
practices, and respiratory
protection without the need
for exposure assessment.
OSHA has carefully reviewed the
basis for its exposure
monitoring cost estimates and
considered the concerns raised
by the SERs. OSHA solicits
comments on this issue in
Chapter V of the PEA.
(General Industry) The Panel recommends OSHA has conducted a
that OSHA use the best scientific comprehensive review of the
evidence and methods available to scientific evidence from
determine the significance of risks toxicological and
and magnitude of benefits for epidemiological studies on
occupational exposure to silica. The adverse health effects
Panel further recommends that OSHA associated with occupational
evaluate existing state silicosis exposure to respirable
surveillance data to determine whether crystalline silica. This
there are industry-specific review is summarized in
differences in silicosis risks, and Section V of this preamble,
whether or how the draft standard Health Effects Summary, and
should be revised to reflect such estimates of the risks of
differences. developing silica-related
diseases are summarized in
Section VI, Summary of the
Preliminary Quantitative Risk
Assessment. The significance
of these risks is examined in
Section VII, Significance of
Risk. The benefits associated
with the proposed rule are
summarized in Section VIII.G,
Benefits and Net Benefits.
Although OSHA's preliminary
analysis indicates that a
variety of factors may affect
the toxicologic potency of
crystalline silica found in
different work environments,
OSHA has not identified
information that would allow
the Agency to calculate how
these influences may affect
disease risk to workers in any
particular workplace setting.
The SERs, however, also had many OSHA has carefully considered
specific issues concerning what OSHA the Panel recommendations, and
should do if it chooses to go forward the Agency's responses are
with a proposed rule. In order to listed in this table. In
reflect these specific issues, the addition, specific issues
Panel has made many recommendations raised in comments by
concerning issues to be considered if individual SERs are addressed
the Agency goes forward with a rule. throughout the preamble.
The Panel also recommends that OSHA
take great care in reviewing and
considering all comments made by the
SERs.
------------------------------------------------------------------------
IX. OMB Review Under the Paperwork Reduction Act of 1995
A. Overview
The proposed general industry/maritime and construction standards
("the standards") for respirable crystalline silica contain
collection of information (paperwork) requirements that are subject to
review by the Office of Management and Budget (OMB) under the Paperwork
Reduction Act of 1995 (PRA-95), 44 U.S.C. 3501 et seq, and OMB's
regulations at 5 CFR part 1320. PRA-95 defines "collection of
information" to mean, "the obtaining, causing to be obtained,
soliciting, or requiring the disclosure to third parties
or the public, of facts or opinions by or for an agency, regardless of
form or format" (44 U.S.C. 3502(3)(A)). Under PRA-95, a Federal agency
cannot conduct or sponsor a collection of information unless OMB
approves it, and the agency displays a currently valid OMB control
number.
B. Solicitation of Comments
OSHA prepared and submitted an Information Collection Request (ICR)
for the collection of information requirements identified in this NPRM
to OMB for review in accordance with 44 U.S.C. 3507(d). The Agency
solicits comments on the proposed new collection of information
requirements and the estimated burden hours associated with these
requirements, including comments on the following items:
Whether the proposed collection of information
requirements 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 information collection requirements, 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.
C. Proposed Revisions to Information Collection Requirements
As required by 5 CFR 1320.5(a)(1)(iv) and 1320.8(d)(2), the
following paragraphs provide information about this ICR.
1. Title: Respirable Crystalline Silica Standards for General
Industry/Maritime (Sec. 1910.1053) and Construction (Sec. 1926.1053)
2. Description of the ICR: The proposed respirable crystalline
silica standards contain collection of information requirements which
are essential components of the occupational safety and health
standards that will assist both employers and their employees in
identifying exposures to crystalline silica, the medical effects of
such exposures, and means to reduce or eliminate respirable crystalline
silica overexposures.
3. Summary of the Collections of Information:
1910.1053(d) and 1926.1053(d)--Exposure Assessment
Under paragraph (d)(6) of the proposed rule, employers covered by
the general industry/maritime standard must notify each affected
employee within 15 working days of completing an exposure assessment.
In construction, employers must notify each affected employee not more
than 5 working days after completing the exposure assessment. In these
standards, the following provisions require exposure assessment
monitoring: Sec. 1910.1053(d)(1) and Sec. 1926.1053(d)(1), General;
Sec. 1910.1053(d)(2) and Sec. 1926.1053(d)(2), Initial Exposure
Assessment; Sec. 1910.1053(d)(3) and Sec. 1926.1053(d)(3), Periodic
Exposure Assessments; Sec. 1910.1053 (d)(4) and Sec. 1926.1053(d)(4),
Additional Exposure Assessments; and Sec. 1926.1053(d)(8)(ii),
Specific Operations.
Under Sec. 1910.1053(d)(6)(i) and Sec. 1926.1053(d)(6)(i),
employers must either notify each affected employee in writing or post
the monitoring results in an appropriate location accessible to all
affected employees. In addition, paragraph (d)(6)(ii) of Sec.
1910.1053 and Sec. 1926.1053 require that whenever the employer
exceeds the permissible exposure limit (PEL), the written notification
must contain a description of the corrective action(s) the employer is
taking to reduce employee exposures to or below the PEL.
1910.1053(e)(3) and 1926.1053(e)(3)--Written Access Control Plan
The standard provides employers with the option to develop and
implement a written access control plan in lieu of establishing
regulated areas under paragraph (e)(3). Paragraph (e)(3)(ii) sets out
the requirements for a written access control plan. The plan must
contain provisions for a competent person to identify the presence and
location of any areas where respirable crystalline silica exposures
are, or can reasonably be expected to be, in excess of the PEL. It must
describe how the employer will notify employees of the presence and
location of areas where exposures are, or can reasonably be expected to
be, in excess of the PEL, and how the employer will demarcate these
areas from the rest of the workplace. For multi-employer workplaces,
the plan must identify the methods the employers will use to inform
other employers of the presence, and the location, of areas where
respirable crystalline silica exposures may exceed the PEL, and any
precautionary measures the employers need to take to protect employees.
The written plan must contain provisions for restricting access to
these areas to minimize the number of employees exposed, and the level
of employee exposure. The plan also must describe procedures for
providing each employee entering areas where respirable crystalline
silica exposures may exceed the PEL, with an appropriate respirator in
accordance with paragraph (g) of the proposed rule; the employer also
must provide this information to the employee's designated
representative. Additionally, where there is the potential for
employees' work clothing to become grossly contaminated with finely
divided material containing crystalline silica, the plan must include
provisions for the employer to provide either appropriate protective
clothing or other means to remove excessive silica dust from
contaminated clothing, as well as provisions for the removal or
cleaning of such clothing.
The employer must review and evaluate the effectiveness of the
written access control plan at least annually, and update it as
necessary. The written access control plan must be available for
examination and copying, upon request, to employees, their designated
representatives, the Assistant Secretary, and the Director.
1910.1053(f)--Methods of Compliance
Where the employer conducts abrasive blasting operations, paragraph
(f)(2) in the general industry/maritime standard requires the employer
to comply with the requirements of 29 CFR part 1915, subpart I
(Personal Protective Equipment), as applicable. Subpart I contains
several information collection requirements. Under subpart I, when
conducting hazard assessments, the employer must: (1) Select the type
of personal protective equipment (PPE) that will protect the affected
employee from the hazards identified in the occupational hazard
assessment; (2) communicate selection decisions to affected employees;
(3) select PPE that properly fits each affected employee; and (4)
verify that the required occupational hazard assessment has been
performed. Additionally, subpart I requires employers to provide
training and verification of training for each employee required to
wear PPE.
1910.1053(g) and 1926.1053(g)--Respiratory Protection
Paragraph (g) in the standards requires the employer to institute a
respiratory protection program in accordance with 29 CFR 1910.134. The
Respiratory Protection Standard's information collection requirements
provide that employers must: develop a written respirator program;
obtain and maintain employee medical evaluation records; provide the
physician or other licensed health care professional (PLHCP) with
information about the employee's respirator and the conditions under
which the employee will use the respirator; administer fit tests for
employees who will use negative- or positive-pressure, tight-fitting
facepieces; and establish and retain written information regarding
medical evaluations, fit testing, and the respirator program.
1910.1053(h) and 1926.1053(h)--Medical Surveillance
Paragraph (h)(2) in the standards requires employers to make
available to covered employees an initial medical examination within 30
days after initial assignment unless the employee received a medical
examination provided in accordance with the standard within the past
three years. Proposed paragraphs (h)(2)(i)-(vi) specify that the
baseline medical examination provided by the PLHCP must consist of the
following information:
1. 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; history of tuberculosis; and smoking status and 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 Organization International Classification of
Radiographs of Pneumoconioses by a National Institute for Occupational
Safety and Health (NIOSH)-certified "B" reader, or an equivalent
diagnostic study;
4. A pulmonary function test administered by a spirometry
technician with current certification from a NIOSH-approved spirometry
course;
5. Testing for latent tuberculosis infection; and
6. Any other tests deemed appropriate by the PLHCP.
Paragraph (h)(3) in the standards requires periodic medical
examinations administered by a PLHCP, every three years or more
frequently if recommended by the PLHCP, for covered employees,
including medical and work history, physical examination emphasizing
the respiratory system, chest X-rays or equivalent diagnostic study,
pulmonary function tests, and other tests deemed to be appropriate by
the PLHCP.
Paragraph (h)(4) in the standards requires the employer to provide
the examining PLHCP with a copy of the standard. In addition, for each
employee receiving a medical examination, the employer must provide the
PLHCP with the following information: a description of the affected
employee's former, current, and anticipated duties as they relate to
the employee's occupational exposure to respirable crystalline silica;
the employee's former, current, and anticipated levels of occupational
exposure to respirable crystalline silica; a description of any PPE
used or to be used by the employee, including when and for how long the
employee has used that equipment; and information from records of
employment-related medical examinations previously provided to the
affected employee and currently within the control of the employer.
Paragraph (h)(5) in the standards requires the employer to obtain a
written medical opinion from the PLHCP within 30 days of each medical
examination performed on each employee. The employer must provide the
employee with a copy the PLHCPs' written medical opinion within two
weeks of receipt. This written opinion must contain the following
information:
1. A description of the employee's health condition as it relates
to exposure to respirable crystalline silica, including the PLHCP's
opinion as to whether the employee has any detected medical
condition(s) that would place the employee at increased risk of
material impairment to health from exposure to respirable crystalline
silica;
2. Any recommended limitations upon the employee's exposure to
respirable crystalline silica or on the use of PPE such as respirators;
3. A statement that the employee should be examined by an American
Board Certified Specialist in Pulmonary Disease ("pulmonary
specialist") pursuant to paragraph (h)(6) if the "B" reader
classifies the chest X-ray as 1/0 or higher, or if referral to a
pulmonary specialist is otherwise deemed appropriate by the PLHCP; and
4. A statement that the PLHCP 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.
If the PLHCP's written medical opinion indicates that a pulmonary
specialist should examine an employee, paragraph (h)(6) in the
standards requires the employer to make available for the employee a
medical examination by a pulmonary specialist within 30 days after
receiving the PLHCP's written medical opinion. The employer must
provide the examining pulmonary specialist with information specified
by paragraph (h)(4). The employer must obtain a written opinion from
the pulmonary specialist within 30 days of the examination. The written
opinion must be comparable to the written opinion obtained from the
original PLHCP. The pulmonary specialist also must state in the written
opinion that the specialist explained these findings to the employee.
The employer also must provide a copy of the PLHCP's written medical
opinion to the examined employee within two weeks after receiving it.
1910.1053(i) and 1926.1053(i)--Communication of Respirable Crystalline
Silica Hazards to Employees
Paragraph (i)(1) of the standards requires compliance with the
Hazard Communication Standard (29 CFR 1910.1200), and lists cancer,
lung effects, immune system effects, and kidney effects as hazards that
the employer must address in its hazard communication program.
Additionally, employers must ensure that each employee has access to
labels on containers of crystalline silica and safety data sheets.
Under paragraph (i)(2)(ii), the employer must make a copy of this
section readily available without cost to each affected employee.
1910.1053(j) and 1926.1053(j)--Recordkeeping
Paragraph (j)(1)(i) of the standards requires that employers
maintain an accurate record of all employee exposure measurement
results as prescribed in paragraph (d) of these standards. The record
must include the following information: the date of measurement for
each sample taken; the operation monitored; sampling and analytical
methods used; number, duration, and results of samples taken; identity
of the laboratory that performed the analysis; type of PPE, 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 monitored. The employer
must maintain, and make available, employee exposure records in
accordance with 29 CFR 1910.1020.
Paragraph (j)(2)(i) requires the employer to maintain an accurate
record of all objective data relied on to comply
with the proposed requirements of this section. The record must include
the following information: the crystalline silica-containing material
in question; the source of the objective data; the testing protocol and
results of testing; and a description of the process, operation, or
activity, and how the data support the assessment; and other data
relevant to the process, operation, activity, material, or employee
exposures. The employer must maintain, and make available, the
objective data records in accordance with 29 CFR 1910.1020.
Paragraph (j)(3)(i) requires the employer to establish and maintain
an accurate record for each employee covered by medical surveillance
under paragraph (h). The record must include the following information:
the employee's name and social security number; a copy of the PLHCP's
and pulmonary specialist's written opinions; and a copy of the
information provided to the PLHCP and pulmonary specialist as required
by paragraph (h)(4) of the proposed rule. The employer must maintain,
and make available, the medical surveillance records in accordance with
29 CFR 1910.1020.
4. Number of respondents: Employers in general industry, maritime,
or construction that have employees working in jobs affected by
respirable crystalline silica exposure (543,041 businesses).
5. Frequency of responses: Frequency of response varies depending
on the specific collection of information.
6. Number of responses: 4,242,296.
7. Average time per response: Varies from 5 minutes (.08 hour) for
the employer to provide a copy of the written physician's opinion to
the employee, to 8 hours to establish a new respiratory protection
program in large establishments.
8. Estimated total burden hours: 2,585,164.
9. Estimated costs (capital-operation and maintenance):
$273,504,281.
D. Submitting Comments
Members of the public who wish to comment on the paperwork
requirements in this proposal must send their written comments to the
Office of Information and Regulatory Affairs, Attn: OMB Desk Officer
for the Department of Labor, OSHA (RIN-1218 -AB70), Office of
Management and Budget, Room 10235, Washington, DC 20503, Telephone:
202-395-6929/Fax: 202-395-6881 (these are not toll-free numbers),
email: OIRA_submission@omb.eop.gov. The Agency encourages commenters
also to submit their comments on these paperwork requirements to the
rulemaking docket (Docket Number OSHA-2010-0034), along with their
comments on other parts of the proposed rule. For instructions on
submitting these comments to the rulemaking docket, see the sections of
this Federal Register notice titled DATES and ADDRESSES. Comments
submitted in response to this notice are public records; therefore,
OSHA cautions commenters about submitting personal information such as
Social Security numbers and date of birth.
E. Docket and Inquiries
To access the docket to read or download comments and other
materials related to this paperwork determination, including the
complete Information Collection Request (ICR) (containing the
Supporting Statement with attachments describing the paperwork
determinations in detail) use the procedures described under the
section of this notice titled ADDRESSES. You also may obtain an
electronic copy of the complete ICR by visiting the Web page at
http://www.reginfo.gov/public/do/PRAMain,
scroll under "Currently Under
Review" to "Department of Labor (DOL)" to view all of the DOL's
ICRs, including those ICRs submitted for proposed rulemakings. To make
inquiries, or to request other information, contact Mr. Todd Owen,
Directorate of Standards and Guidance, OSHA, Room N-3609, U.S.
Department of Labor, 200 Constitution Avenue NW., Washington, DC 20210;
telephone (202) 693-2222.
OSHA notes that a federal agency cannot conduct or sponsor a
collection of information unless it is approved by OMB under the PRA
and displays a currently valid OMB control number, and the public is
not required to respond to a collection of information unless the
collection of information displays a currently valid OMB control
number. Also, notwithstanding any other provision of law, no person
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.
X. Federalism
The Agency reviewed the proposed crystalline silica rule according
to the Executive Order on Federalism (Executive Order 13132, 64 FR
43255, Aug. 10, 1999), 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. The Executive Order allows
Federal agencies to preempt State law only with the expressed 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 (the
"Act"' or "OSH Act," 29 U.S.C. 667), Congress expressly provides
that States may adopt, with Federal approval, a plan for the
development and enforcement of occupational safety and health
standards; States that obtain Federal approval for such a plan are
referred to as "State-Plan States." (29 U.S.C. 667). 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 requirements for occupational safety and health standards.
While OSHA drafted the proposed rule to protect employees in every
State, Section 18(c)(2) of the OSHA Act permits State-Plan States to
develop and enforce their own standards, provided the requirements in
these standards are at least as safe and healthful as the requirements
specified in the proposed rule if it is promulgated.
In summary, the proposed rule complies with Executive Order 13132.
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 rulemaking does not significantly limit State policy
options.
XI. State-Plan States
When Federal OSHA promulgates a new standard or a more stringent
amendment to an existing standard, the 27 State 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 CFR
1953.5(a).
The State may demonstrate that a standard change is not necessary
because, for example, the State standard is already the same as or at
least as effective as the Federal standard change. 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 makes
a timely demonstration that good cause exists for extending the time
limitation. 29 CFR 1953.5(a).
Of the 27 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. The five
states and territories whose OSHA-approved State plans cover only
public-sector employees are: Connecticut, Illinois, New Jersey, New
York, and the Virgin Islands.
This proposed crystalline silica rule applies to general industry,
construction and maritime, and would impose additional or more
stringent requirements. If adopted as proposed, all State Plan States
would be required to revise their general industry and construction
standards appropriately within six months of Federal promulgation. In
addition, State plans that cover private sector maritime employment
issues and/or have public employees working in the maritime industry
covered by this standard would be required to adopt comparable
provisions to their maritime employment standards within six months of
publication of the final rule.
XII. Unfunded Mandates
Under Section 202 of the Unfunded Mandates Reform Act of 1995
(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 issuing a notice of
proposed rulemaking. OSHA's proposal 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.
(See 29 U.S.C. 652(5).) Under voluntary agreement with OSHA, some
States enforce compliance with their State standards on public sector
entities, and these agreements specify that these State standards must
be equivalent to OSHA standards. The OSH Act also does not cover tribal
governments in the performance of traditional governmental functions,
though it does when tribal governments engage in commercial activity.
However, the proposal would not require tribal governments to expend,
in the aggregate, $100,000,000 or more in any one year for their
commercial activities. Thus, although OSHA may include compliance costs
for affected governmental entities in its analysis of the expected
impacts associated with a proposal, the proposal does not trigger the
requirements of UMRA based on its impact on State, local, or tribal
governments.
Based on the analysis presented in the Preliminary Economic
Analysis (see Section VIII above), OSHA concludes that the proposal
would impose a Federal mandate on the private sector in excess of $100
million in expenditures in any one year. The Preliminary Economic
Analysis constitutes the written statement containing a qualitative and
quantitative assessment of the anticipated costs and benefits required
under Section 202(a) of the UMRA (2 U.S.C. 1532).
XIII. Protecting Children From Environmental Health and Safety Risks
Executive Order 13045 requires that Federal agencies submitting
covered regulatory actions to OMB'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. 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 proposed respirable crystalline silica rule is economically
significant under Executive Order 12866 (see Section VIII of this
preamble). However, after reviewing the proposed respirable crystalline
silica 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 proposed 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 or that employees under 18 years of
age who may be exposed to respirable crystalline silica are
disproportionately affected by such exposure. Based on this preliminary
determination, OSHA believes that the proposed respirable crystalline
silica rule does not constitute a covered regulatory action as defined
by Executive Order 13045. However, if such conditions exist, children
who are exposed to respirable crystalline silica in the workplace would
be better protected from exposure to respirable crystalline silica
under the proposed rule than they are currently.
XIV. Environmental Impacts
OSHA has reviewed the silica proposal 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),
and the Department of Labor's NEPA procedures (29 CFR part 11). Based
on that review, OSHA does not expect that the proposed rule, in and of
itself, would create additional environmental issues. However, as noted
in the SBREFA report (OSHA, 2003, p. 77), some Small Entity
Representatives (SERs) raised the possibility that the use of wet
methods to limit occupational (and environmental) exposures in some
areas may violate EPA rules with respect to suspended solids in runoff
unless provision is made for recycling or settling the suspended solids
out of the water. The SBREFA Panel recommended that OSHA investigate
this issue, add appropriate costs if necessary, and solicit comment on
this issue.
Some large construction projects may already require a permit to
address storm water runoff, independent of any OSHA requirements to
limit worker exposure to silica. These environmental
requirements come from or reference the Clean Water Act of 1987. As
applied to construction activities, EPA requirements generally pertain
to projects of one acre or more and impose the use of Best Management
Practices (BMPs) to minimize the pollution, via water runoff, of storm
water collection systems and surface waters. In some cases, these
requirements are administered by States.
Otherwise, the use of wet methods to control silica dust as
mandated by an OSHA silica standard is not directly addressed by EPA
requirements. Local governments, however, might require compliance with
EPA BMPs when granting construction permits. As an example, the
California Department of Transportation's Construction Site Best
Management Practice (BMP) Field Manual and Troubleshooting Guide
includes the following guidance for paving and grinding operations:
"Do not allow wastes, such as AC [asphalt concrete] pieces, PCC
[Portland concrete cement] grinding residue/slurry, sand/gravel,
exposed aggregate concrete residue, or dig-out materials into storm
drains or receiving waters. Sweep, vacuum, and collect such wastes and
recycle or dispose of properly" (State of California, Department of
Transportation, 2003). Contractors following these BMPs would need to
take steps to prevent water used for dust control from running into
storm drains, drainage ditches, or surface waters. Slurries left on
paved areas would need to be swept or vacuumed to prevent subsequent
runoff during storms.
It should be noted that the objective of these BMPs is a reduction
in the amount of pollutants washed into storm drain systems or surface
waters, rather than reductions in discharges per se. The environmental
concern is that the use of wet methods to control silica dust would,
besides creating silica slurry, facilitate discharges of other
pollutants.
The silica controls costed by OSHA in Chapter VI of the Preliminary
Economic Analysis show six tasks where wet methods are suggested:
stationary masonry saws, hand-held masonry saws, walk-behind and other
large concrete saws, concrete grinding with walk-behind equipment,
asphalt milling, and pavement breaking and other demolition with
jackhammers. A detailed review of the control measures for these
equipment types suggests that only the use of wet methods with pavement
breakers has the potential to directly result in runoff discharges to
storm drains or surface waters. Even then, the water required would
most often not create a runoff potential. The control costs for each of
these jobs contains a productivity impact factor, part of which is
intended to account for extra cleanup time associated with use of wet
methods to control dust, including sweeping or vacuuming of silica
slurry. However, such efforts may be less laborious than having to
clean up free silica dust and may result in a net decrease in silica
(and any other contaminants related to its production) running off into
the water supply. OSHA's estimate of the potential environmental impact
of each of these six equipment types is summarized below:
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. 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 often inside the
structure. Thus, direct discharges to storm drains or surface waters
are unlikely.
Asphalt milling 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 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 filter
it. Because the volume of water is relatively small, the costs for such
barriers are likely insubstantial. However, because this type of runoff
could happen occasionally, OSHA has added costs for barriers in costing
silica controls for this task.
As a result of this review, OSHA has made a determination that the
silica proposal would have little potential impact on air, water, or
soil quality; plant or animal life; the use of land; or aspects of the
external environment. As described above in this section, effective
abatement measures are available where the potential for environmental
impacts exist. Therefore, OSHA preliminarily concludes that the
proposed standard would have no significant environmental impacts.
However, while the Agency does not believe that the proposed rule would
create significant costs, or otherwise pose a significant challenge,
for employers to comply with existing environmental rules, OSHA
welcomes comment on this or any other environmentally related issues,
or potential conflicts with other agency rules.
XV. Public Participation
OSHA encourages members of the public to participate in this
rulemaking by submitting comments on the proposal and by providing oral
testimony and documentary evidence at the informal public hearings that
the Agency will convene after the comment period ends. The Agency
invites interested persons having knowledge of, or experience with,
occupational exposure to silica and the issues raised by the proposed
rule to participate in this process, and welcomes any
pertinent data and information that will provide it with the best
available evidence on which to develop the final regulatory
requirements.
The Agency has scheduled time during the informal rulemaking
hearing in Washington, DC, for participants to testify on the Health
Effects Literature Review and Preliminary Quantitative Risk Assessment
in the presence of peer reviewers. Peer reviewers will subsequently be
able to submit amended final comments to the record. As described in
OSHA's peer review agenda, peer reviewers have reviewed OSHA's draft
Health Effects Literature Review and Preliminary Quantitative Risk
Assessment and have submitted written reports that the Agency has
considered prior to publication of the proposed rule. The open comment
period and informal hearing will provide the public an opportunity to
submit information to the record that it believes will benefit the peer
review, and to testify in the presence of the reviewers. This section
describes the procedures the public must use to submit their comments
to the docket in a timely manner, and to schedule an opportunity to
deliver oral testimony and provide documentary evidence at informal
public hearings on the proposal. Comments, notices of intention to
appear, hearing testimony and documentary evidence will be available
for inspection and copying at the OSHA Docket Office. You also should
read the sections above titled DATES and ADDRESSES for additional
information on submitting comments, documents, the presence of peer
reviewers at the hearings, and requests to the Agency for consideration
in this rulemaking.
Written Comments. OSHA invites interested persons to submit written
data, views, and arguments concerning this proposal. In particular,
OSHA encourages interested persons to comment on the issues raised in
Section I of this preamble. When submitting comments, persons must
follow the procedures specified above in the sections titled DATES and
ADDRESSES. The comments must clearly identify the provision of the
proposal you are addressing, the position taken with respect to each
issue, and the basis for that position. Comments, along with supporting
data and references, received by the end of the specified comment
period will become part of the record and will be available for public
inspection and copying at the OSHA Docket Office as well as online at
www.regulations.gov
(Docket Number OSHA-2010-0034).
Informal Public Hearings. Pursuant to section 6(b)(3) of the Act,
members of the public will have an opportunity to provide oral
testimony concerning the issues raised in this proposal at informal
public hearings. The legislative history of section 6 of the OSH Act,
as well as OSHA's regulation governing public hearings (29 CFR
1911.15), establish the purpose and procedures of informal public
hearings. Although the presiding officer of the hearing is an
administrative law judge (ALJ) and questioning of witnesses is allowed
on crucial issues, the proceeding is largely informal and essentially
legislative in purpose. Therefore, the hearing provides interested
persons with an opportunity to make oral presentations in the absence
of procedural restraints or rigid procedures that could impede or
protract the rulemaking process. The hearing is not an adjudicative
proceeding subject to the technical rules of evidence. Instead, it is
an informal administrative proceeding convened for the purpose of
gathering and clarifying information. The regulations that govern the
hearings and the prehearing guidelines issued for the hearing will
ensure that participants are treated fairly and provided due process.
This approach will facilitate the development of a clear, accurate, and
complete record. Accordingly, application of these rules and guidelines
will be such that questions of relevance, procedure, and participation
generally will be resolved in favor of developing a clear, accurate,
and complete record. Conduct of the hearing will conform to 29 CFR
1911.15. In addition, the Assistant Secretary may, on reasonable
notice, issue additional or alternative procedures to expedite the
proceedings, to provide greater procedural protections to interested
persons or to further any other good cause consistent with applicable
law (29 CFR 1911.4).
Although the ALJ presiding over the hearing makes no decision or
recommendation on the merits of the proposal, the ALJ has the
responsibility and authority necessary to ensure the hearing progresses
at a reasonable pace and in an orderly manner. To ensure that
interested persons receive a full and fair hearing, the ALJ has the
power to regulate the course of the proceedings; dispose of procedural
requests, objections, and comparable matters; confine presentations to
matters pertinent to the issues the proposed rule raises; use
appropriate means to regulate the conduct of persons present at the
hearing; question witnesses and permit others to do so; limit the time
for such questioning; and leave the record open for a reasonable time
after the hearing for the submission of additional data, evidence,
comments and arguments (29 CFR 1911.16).
At the close of the hearing the ALJ will establish a post-hearing
comment period for interested persons who filed a timely notice of
intention to appear at the hearing. During the first part of the post-
hearing period, those persons may submit additional data and
information to OSHA. During the second part they may submit final
briefs, arguments, and summations.
Notice of Intention to Appear to Provide Testimony at the Informal
Public Hearing. Interested persons who intend to provide oral testimony
at the informal public hearing must file a notice of intention to
appear by using the procedures specified above in the sections titled
DATES and ADDRESSES. This notice must provide the following
information:
Name, address, email address, and telephone number of each
individual who will give oral testimony;
Name of the establishment or organization each individual
represents, if any;
Occupational title and position of each individual testifying;
Approximate amount of time required for each individual's
testimony;
If the individual requests to present testimony related to the
Health Effects Literature Review and Preliminary Quantitative Risk
Assessment, the notice should specify if the submitter requests this
testimony be provided in the presence of peer reviewers;
A brief statement of the position each individual will take with
respect to the issues raised by the proposed rule; and
A brief summary of documentary evidence each individual intends to
present.
Participants who need projectors and other special equipment for
their testimony must contact Frank Meilinger at OSHA's Office of
Communications, telephone (202) 693-1999, no later than one week before
the hearing begins.
OSHA emphasizes that the hearings are open to the public; however,
only individuals who file a notice of intention to appear may question
witnesses and participate fully at the hearing. If time permits, and at
the discretion of the ALJ, an individual who did not file a notice of
intention to appear may be allowed to testify at the hearing, but for
no more than 10 minutes.
Hearing testimony and documentary evidence. Individuals who request
more than 10 minutes to present their oral testimony at the hearing or
who will submit documentary evidence at the
hearing must submit (transmit, send, postmark, deliver) the full text
of their testimony and all documentary evidence no later than December
11, 2013.
The Agency will review each submission and determine if the
information it contains warrants the amount of time the individual
requested for the presentation. If OSHA believes the requested time is
excessive, the Agency will allocate an appropriate amount of time for
the presentation. The Agency also may limit to 10 minutes the
presentation of any participant who fails to comply substantially with
these procedural requirements, and may request that the participant
return for questioning at a later time. Before the hearing, OSHA will
notify participants of the time the Agency will allow for their
presentation and, if less than requested, the reasons for its decision.
In addition, before the hearing OSHA will provide the pre-hearing
guidelines and hearing schedule to each participant.
Certification of the hearing record and Agency final determination.
Following the close of the hearing and the post-hearing comment
periods, the ALJ will certify the record to the Assistant Secretary of
Labor for Occupational Safety and Health. The record will consist of
all of the written comments, oral testimony and documentary evidence
received during the proceeding. The ALJ, however, will not make or
recommend any decisions as to the content of the final standard.
Following certification of the record, OSHA will review all the
evidence received into the record and will issue the final rule based
on the record as a whole.
XVI. Summary and Explanation of the Standards
(a) Scope and application
OSHA is proposing to issue one standard addressing respirable
crystalline silica exposure in general industry and maritime and a
separate standard addressing exposure in the construction industry. The
scope provisions are contained in paragraph (a) of the proposed
standards. The proposed standard for the construction industry is
similar to the proposed standard for general industry and maritime, and
the standards are intended to provide equivalent protection for all
workers while accounting for the different work activities, anticipated
exposures, and other conditions in these sectors. The limited
differences between the proposed construction and general industry/
maritime standards exist because OSHA believes, based on the record
developed to date, that certain activities in construction are
different enough to warrant modified requirements.
The proposed standards do not cover the agricultural sector, due to
limited data on exposures and control measures in this 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 workers. Consolidated Appropriations Act, 1976, Public Law 94-439,
90 Stat. 1420, 1421 (1976) (and subsequent appropriations acts).
However, some evidence indicates that certain agricultural operations
may result in exposures to respirable silica in excess of the proposed
PEL. A literature review conducted by Swanepoel et al. (2010)
identified studies that examined respirable quartz exposure and
associated diseases in agricultural settings. Three of the exposure
studies measured respirable quartz in the personal breathing zone of
workers (Popendorf et al. 1982; Archer et al. 2002; Lee et al. 2004).
Popendorf et al. (1982) investigated exposures among citrus, peach, and
grape harvesters; Archer et al. (2002) reported on farmworkers in
eastern North Carolina; and Lee et al. (2004) examined citrus and grape
harvesters in California. Each of these studies identified instances
where exposures exceeded the proposed PEL. In particular, Archer et al.
(2002) reported respirable quartz concentrations as high as 3910 [mu]g/
m\3\ among farmworkers during sweet potato transplanting. Area samples
reported in two other studies support the belief that agricultural
operations can generate high levels of respirable quartz. Gustafsson et
al. (1978) reported average respirable quartz concentrations of 2000
[mu]g/m\3\ in open tractor cabs, while Lawson et al. (1995) reported
respirable quartz concentrations ranging from 20-90 [mu]g/m\3\ during
rice farming operations. Little evidence was reported in the literature
regarding diseases associated with respirable crystalline silica
exposure in agricultural workers (Swanepoel et al., 2010). OSHA is
interested in additional evidence relating to exposures to respirable
crystalline silica that occur in agriculture and to associated control
measures, as well as information related to the development of
respirable crystalline silica-related diseases among workers in the
agricultural sector, and is requesting such information in the
"Issues" section (Section I) of this preamble.
In paragraph (b) (definition of "respirable crystalline silica"),
OSHA proposes to cover quartz, cristobalite, and tridymite under the
standard. The Agency believes the evidence supports this approach. OSHA
currently has different permissible exposure limits (PELs) for
different forms of crystalline silica. The current general industry
PELs for cristobalite and tridymite are one half of the general
industry PEL for quartz. This difference was based on the fact that
early animal studies appeared to suggest that cristobalite and
tridymite were more toxic to the lung than quartz. However, as
discussed in OSHA's Review of Health Effects Literature and summarized
in Section V of this preamble, reviews of more recent studies have led
OSHA to preliminarily conclude that cristobalite and tridymite are
comparable to quartz in their toxicities. Also, a difference in
toxicity between cristobalite and quartz has not been observed in
epidemiologic studies. Exposure to tridymite has not been the subject
of epidemiologic study.
OSHA's preliminary conclusion that quartz, cristobalite, and
tridymite should be addressed under a single standard and subject to
the same PEL is consistent with the recommendation of the National
Institute for Occupational Safety and Health (NIOSH), which has a
single Recommended Exposure Limit (REL) covering all forms of
respirable crystalline silica. In addition, the American Conference of
Governmental Industrial Hygienists (ACGIH) has issued a single
Threshold Limit Value (TLV) for quartz and cristobalite.
In 2003, OSHA presented respirable crystalline silica draft
standards for both general industry and construction to the Small
Business Regulatory Enforcement Fairness Act (SBREFA) review panel. The
general industry scope has remained unchanged, while the SBREFA
construction draft standard included two alternative scope provisions.
The first option, which is included in the proposal, stated that the
rule applied to all construction operations covered by 29 CFR part
1926. The second option was more restrictive, indicating the rule would
apply only to abrasive blasting and other specified operations
(cutting, sanding, drilling, crushing, grinding, milling, sawing,
scabbling, scrapping, mixing, jack hammering, excavating, or disturbing
materials that contain crystalline silica). The SBREFA panel
recommended that OSHA continue to evaluate and consider modifications
to the second option that could serve to limit the scope of the
standard.
OSHA is proposing to cover all occupational exposures to respirable
crystalline silica in construction work, as defined in 29 CFR
1910.12(b) and covered under 29 CFR part 1926, because the Agency wants
to ensure that all activities are covered by the standard if they
involve exposures that present a significant risk to workers. The
second scope option in the SBREFA draft included activities that are
typically associated with higher worker exposures to crystalline
silica, but would not cover all operations that present a significant
risk.
Collectively, the proposed standards apply to occupational exposure
in which respirable crystalline silica is present in an occupationally
related context. Exposure of employees to the ambient environment,
which may contain small concentrations of respirable crystalline silica
unrelated to occupational activities, is not subject to the proposed
standards.
(b) Definitions
"Action level" is defined as an airborne concentration of
respirable crystalline silica of 25 micrograms per cubic meter of air
(25 [mu]g/m\3\) calculated as an eight-hour time-weighted average
(TWA). The action level triggers requirements for periodic exposure
monitoring. In this proposal, as in other standards, the action level
has been set at one-half of the PEL.
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 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.
Previous standards have recognized 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). In brief, OSHA previously
determined (based in part on research conducted by Leidel et al.) 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 (Leidel, et al., 1975).
Therefore, requiring periodic exposure measurements when the action
level is exceeded provides employers with additional assurance that
employees are being protected from exposures above the PEL.
As exposures are lowered, the risk of adverse health effects among
workers decreases. In addition, there is an economic benefit to
employers who reduce exposure levels below the action level: They can
avoid the costs associated with periodic exposure monitoring
requirements. Some employers will be able to reduce exposures below the
action level in all work areas, and other employers in some work areas.
OSHA's preliminary risk assessment indicates that significant risk
remains at the proposed PEL of 50 [mu]g/m\3\. At least one court has
held that OSHA has a duty to impose additional requirements on
employers to eliminate remaining significant risk when those
requirements will afford benefits to workers and are feasible. Building
and Construction Trades Department, AFL-CIO v. Brock, 838 F.2d 1258,
1269 (D.C. Cir 1988). OSHA's preliminary conclusion is that the action
level will result in a very real and necessary further reduction in
risk beyond that provided by the PEL alone. OSHA's decision to propose
an action level of one-half of the PEL is based, in part, on the
Agency's successful 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).
"Competent person" means 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. The competent person
concept has been broadly used in OSHA construction standards,
particularly in safety standards. In OSHA shipyard standards, a defined
role for the competent person focuses on confined space hazards, hot
work, and explosive environments. Competent person requirements also
apply to powder actuated tools. It is not the intent of this proposal
to modify the existing competent person requirements in shipyard
standards.
As explained below in section (e) (Regulated areas and access
control), employers have the option to develop a written access control
plan in lieu of establishing regulated areas to minimize exposures to
employees not directly involved in operations that generate respirable
crystalline silica in excess of the PEL. The access control plan would
require that a competent person identify areas where respirable
crystalline silica exposures are, or can reasonably be expected to be,
in excess of the PEL.
The proposed standard does not specify particular training
requirements for competent persons. Rather, the requirement for a
competent person is performance-based; the competent person must be
capable of effectively performing the duties assigned under the
standard. Therefore, the competent person must have the knowledge and
experience necessary to identify in advance tasks or operations during
which exposures are reasonably expected to exceed the PEL, so that
affected employees can be notified of the presence and location of
areas where such exposures may occur, and the employer can take steps
to limit access to these areas and provide appropriate respiratory
protection.
OSHA included more extensive competent person requirements in both
the draft general industry/maritime and construction standards
presented for review to the Small Business Regulatory Enforcement
Fairness Act (SBREFA) review panel. The SBREFA draft standards included
requirements for a competent person at each worksite to ensure
compliance with the provisions of the standard. Specifically, the
SBREFA draft standards required that the competent person: Evaluate
workplace exposures and the effectiveness of controls, and implement
corrective measures to ensure that employees are not exposed in excess
of the PEL; establish regulated areas wherever the airborne
concentration of respirable crystalline silica exceeds or can
reasonably be expected to exceed the PEL, taking into consideration
factors that could affect exposures such as wind direction, changes in
work processes, and proximity to other workplace operations; and check
the regulated area daily to ensure the boundary is maintained. The
SBREFA draft standards also required the employer to ensure that the
competent person inspect abrasive blasting activities as necessary to
ensure that controls are being properly used and remain effective;
participate in the evaluation of alternative blast media; and
communicate with other employers to inform them of the boundaries of
regulated areas established around abrasive blasting operations.
Many small entity representatives (SERs) from the construction
industry who reviewed the SBREFA draft standard found the requirements
for a competent person hard to understand (OSHA, 2003). Many believed
that the competent person required a high skill level, while others
thought that a large proportion of their employees would
need to be trained. SERs thought that the requirements would be
difficult to comply with and costly. These concerns may have been due
to the specific regulatory language used in the SBREFA draft, rather
than the general concept of competent person requirements. OSHA's
Advisory Committee on Construction Safety and Health recommended that
the Agency retain the requirement and responsibilities for a competent
person in the proposed rule (ACCSH, 2009). The Building and
Construction Trades Department, AFL-CIO has also consistently
recommended including competent person requirements in a proposed
silica standard.
OSHA has proposed limited competent person requirements because the
Agency has preliminarily concluded that the provisions of the proposed
standard will generally be effective without the involvement of an
individual specifically designated as a competent person. For example,
the proposed standard requires that the employer use engineering and
work practice controls to reduce and maintain employee exposure to
respirable crystalline silica to or below the PEL. OSHA believes that
this provision adequately communicates this requirement to employers,
and that an additional requirement for a "competent person" to
evaluate the effectiveness of these controls and implement corrective
measures in this standard is not necessary. However, the Agency is
aware that competent person requirements have been included in other
health and safety standards, and that some parties believe such
requirements would be useful in the silica standard. OSHA is interested
in information and comment on the appropriate role of a competent
person in the respirable crystalline silica standard, and has included
this topic in the "Issues" section (Section I) of this preamble.
"Employee exposure" means exposure to airborne respirable
crystalline silica that would occur if the employee were not using a
respirator. This definition is included to clarify the requirement that
employee exposure be measured as if no respiratory protection were
being worn. It is consistent with OSHA's previous use of the term in
other standards.
"Objective data" means information, such as air monitoring data
from industry-wide surveys or calculations based on the composition or
chemical and physical properties of a substance, demonstrating employee
exposure to respirable crystalline silica associated with a particular
product, material, process, operation, or activity. The data must
reflect workplace conditions closely resembling the processes, types of
material, control methods, work practices, and environmental conditions
in the employer's current operations. Objective data is further
discussed below in section (d) (Exposure Assessment).
"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. This definition is included because the
proposed standard requires that all medical examinations and procedures
be performed by or under the supervision of a PLHCP.
Any PLHCP may perform the medical examinations and procedures
required under the standard when they are licensed, registered, or
certified by state law to do so. The Agency recognizes that this means
that the personnel qualified to provide the required medical
examinations and procedures may vary from state to state, depending on
state licensing or certification laws. This provision of the proposed
rule grants the employer the flexibility to retain the services of a
variety of qualified licensed health care professionals, provided that
these individuals are licensed to perform, or be delegated the
responsibility to perform, the specified service. OSHA believes that
this flexibility will reduce cost and compliance burdens for employers
and increase convenience for employees. The approach taken in this
proposed standard is consistent with the approach OSHA has taken in
other recent standards, such as chromium (VI) (29 CFR 1910.1026),
bloodborne pathogens (29 CFR 1910.1030), and respiratory protection (29
CFR 1910.134).
"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. This definition is consistent with the use of the term in
other standards, including those for chromium (VI) (29 CFR 1910.1026),
1,3-butadiene (29 CFR 1910.1051), and methylene chloride (29 CFR
1910.1052).
"Respirable crystalline silica" means airborne particles that
contain quartz, cristobalite, and/or tridymite and whose measurement is
determined 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 Agency's proposed definition for respirable crystalline silica
seeks to harmonize the Agency's practice with current aerosol science
and the ISO definition of respirable particulate mass. Thus, the
proposed definition would encompass the polymorphs of silica covered
under current OSHA standards and would be consistent with the
international consensus that the ISO definition of respirable
particulate mass represents. The American Conference of Governmental
Industrial Hygienists (ACGIH) and the European Committee for
Standardization (CEN) have adopted the ISO definition of respirable
particulate mass. The National Institute for Occupational Safety and
Health (NIOSH) has also adopted the ISO definition of respirable
particulate mass in its Manual of Sampling and Analytical Methods.
Adoption of this definition by OSHA would allow for workplace sampling
for respirable crystalline silica exposures to be conducted using any
particulate sampling device that conforms to the ISO definition (i.e.,
that collects dust according to the particle collection efficiency
curve specified in the ISO standard). OSHA's current respirable
crystalline silica PELs are measured according to a particle collection
efficiency curve formerly specified by ACGIH, which is now obsolete.
The relationship between the ISO definition of respirable particulate
mass and the ACGIH criteria is discussed in greater detail in the
Technological Feasibility chapter of the Preliminary Economic Analysis,
and is summarized in section VIII of this preamble.
The definitions for "Assistant Secretary," "Director," "High-
efficiency particulate air [HEPA] filter," and "This section" are
consistent with OSHA's previous use of these terms in other health
standards.
(c) Permissible Exposure Limit (PEL)
In paragraph (c), OSHA proposes to set 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, the average exposure to
respirable crystalline silica cannot exceed 50 [mu]g/m\3\. The proposed
PEL is the same for both general industry/maritime \38\ and construction.
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\38\ OSHA regulates silica exposure in three maritime-related
activities: Shipyards (29 CFR 1915.1000, Table Z), Marine Terminals
(29 CFR 1917.1(a)(2)(xiii)), and Longshoring (29 CFR 1918.1(b)(9)).
Marine Terminals and Longshoring incorporate by reference the toxic
and hazardous substance requirements in subpart Z of the general
industry standard, which includes both a particle-counting formula
and a mass formula for the silica PEL (29 CFR 1910.1000, Table Z-3).
Shipyards has its own subpart Z, which uses the particle-counting
formula for the silica PEL. Thus, under the current scheme, Marine
Terminals and Longshoring use two alternative PEL formulas, while
Shipyards uses a single PEL formula. The proposal eliminates this
discrepancy by adopting a single PEL (50 [mu]g/m\3\) for all three
maritime sectors, in addition to construction and general industry.
In this section, the Agency distinguishes between the proposed
maritime PEL (50 [mu]g/m\3\ for all three maritime sectors) and the
current shipyard PEL (the particle-counting formula required for
shipyards and construction).
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OSHA currently expresses the general industry PEL for respirable
crystalline silica in the form of quartz in two ways. The first, which
is based on gravimetric measurement, is derived from the formula (PEL =
(10 mg/m\3\)/(% quartz + 2) as respirable dust). This is approximately
equivalent to 100 [mu]g/m\3\ of respirable crystalline silica. The
current general industry PELs for the polymorphs cristobalite and
tridymite are one-half of the value calculated from this formula, or
approximately 50 [mu]g/m\3\ of respirable crystalline silica. The
proposed PEL is thus approximately equivalent to the current general
industry PELs for cristobalite and tridymite. In cases where exposures
to quartz, cristobalite, and/or tridymite occur at the same time, the
PEL is calculated following the procedure specified in 29 CFR
1910.1000(d)(2) for exposures to mixtures of substances having an
additive effect on the body or target organ system.
The second way OSHA expresses the general industry PEL for
respirable crystalline silica in the form of quartz is based on a now-
obsolete particle count sampling method, and is presented in terms of
millions of particles per cubic foot (mppcf). This PEL is based on the
formula (PELmppcf = 250/(% quartz + 5) as respirable dust).
The current general industry PELs for cristobalite and tridymite are
one-half of the value calculated from this formula. These two parallel
PELs in general industry were originally believed to be equivalent
values (Ayer, 1995). However, as discussed below, the values are now
considered to differ substantially.
The current PEL for crystalline silica in the form of quartz in
construction and shipyards (PELmppcf = 250/(% quartz + 5) as
respirable dust) is expressed only in terms of mppcf. This is the same
formula as the parallel PEL for respirable crystalline silica in the
form of quartz in general industry that is expressed in mppcf. 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 during the codification of these
rules. OSHA's current proposal provides the same PEL for quartz,
cristobalite, and tridymite, in general industry, construction, and
shipyards.
The current PELs in general industry, construction, and shipyards
are 8-hour TWA exposure limits. Both formulas express the PEL in terms
of a permissible level of exposure to respirable dust, rather than a
permissible level of exposure to respirable crystalline silica. The
higher the percentage of crystalline silica in the sample, the lower
the level of respirable dust allowed.
The current PELs for construction and shipyards (and the parallel
PEL presented for general industry) are based on a particle count
method long rendered obsolete by gravimetric respirable mass sampling,
which yields results reported in milligrams or micrograms per cubic
meter of air (mg/m\3\or [mu]g/m\3\). Gravimetric sampling methods are
the only methods currently available to OSHA compliance personnel.
Since the current construction and shipyard PELs are expressed only in
terms of mppcf, the results of the gravimetric sampling must be
converted to an equivalent mppcf value.
In order to determine a formula for converting from mg/m\3\ to
mppcf, OSHA requested assistance from the National Institute for
Occupational Safety and Health (NIOSH). Based on its review of
published studies comparing the particle count and gravimetric methods,
NIOSH recommended a conversion factor of 0.1 mg/m\3\ respirable dust to
1 mppcf. OSHA has determined that this conversion factor should be
applied to silica sampling results used to characterize exposures in
construction and shipyard operations. Appendix E to CPL 03-00-007,
OSHA's National Emphasis Program for Crystalline Silica, illustrates
how the conversion factor is applied to enforce the current PEL for
crystalline silica in the construction and shipyard industries.
Applying the conversion factor to a sample consisting of pure (i.e.,
100%) crystalline silica indicates that the current PEL for
construction and shipyards is approximately equivalent to 250 [mu]g/
m\3\ of respirable crystalline silica.
OSHA's current PELs for respirable crystalline silica are expressed
as respirable dust, or respirable particulate mass. The proposed PEL is
expressed as respirable crystalline silica, or the amount of
crystalline silica that is present as respirable particulate mass.
Respirable particulate mass refers to airborne particulate matter that
is capable of entering the gas-exchange region of the lung, where
crystalline silica particles cause pathological damage. Only very small
particles (particles of about 10 [mu]g/m or less) are able to penetrate
into the gas-exchange region of the lung. As particle size decreases,
the relative proportion of particles that is expected to reach the gas-
exchange region of the lung increases.
Under the proposed definition of respirable crystalline silica in
paragraph (b), respirable crystalline silica means airborne particles
that contain quartz, cristobalite, and tridymite and 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. This definition
of respirable particulate mass is intended to correspond with airborne
particulate matter that is capable of entering the gas-exchange region
of the lung. It provides a formula for determining the respirable
fraction based on the aerodynamic diameter of the particles, and
represents an international consensus that has been adopted by the
American Conference of Governmental Industrial Hygienists (ACGIH) and
the European Committee for Standardization (CEN). The ISO definition is
also used by the National Institute for Occupational Safety and Health
(NIOSH) in its Manual of Sampling and Analytical Methods. The ISO
definition of respirable particulate mass is discussed in greater
detail in the Technological Feasibility chapter of the Preliminary
Economic Analysis.
OSHA currently has a PEL for exposure to total quartz dust (PEL =
(30 mg/m\3\)/(% quartz + 2) as total dust) in general industry. As with
the PEL for respirable dust, the PELs for cristobalite and tridymite
are one-half of the value calculated from this formula. The Agency does
not have a PEL for exposure to total quartz dust for construction or
shipyards. OSHA proposes to delete the PELs for exposure to total
crystalline silica dust, because the Review of Health Effects
Literature and Preliminary Quantitative Risk Assessment clearly relates
development of crystalline silica-related disease to respirable, rather than total,
dust exposure. This view is consistent with ACGIH, which no longer has
a TLV 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.
OSHA proposes a new PEL of 50 [mu]g/m\3\ because the Agency has
preliminarily determined that occupational exposure to respirable
crystalline silica at the current PEL results in a significant risk of
material health impairment among exposed workers, and that compliance
with the proposed standard will substantially reduce that risk. OSHA's
Preliminary Quantitative Risk Assessment, summarized in Section VI of
this preamble, indicates that a 45-year exposure to respirable
crystalline silica at the current general industry PEL would lead to
between 13 and 60 excess deaths from lung cancer, 9 deaths from
silicosis, 83 deaths from all forms of non-malignant respiratory
disease (including silicosis), and 39 deaths from renal disease per
1000 workers. Exposures at the current construction and shipyard PEL
would result in even higher levels of risk. As discussed in Section VII
of this preamble, 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 believes that lowering the PEL to 50
[mu]g/m\3\ would reduce the lifetime excess risk of death per 1000
workers to between 6 and 26 deaths from lung cancer, 7 deaths from
silicosis, 43 deaths from all forms of non-malignant respiratory
disease (including silicosis), and 32 deaths from renal disease.
OSHA considers the level of risk remaining at the proposed PEL to
be significant. However, the proposed PEL is set at the lowest level
that the Agency believes to be technologically feasible. As discussed
in the Technological Feasibility chapter of the Preliminary Economic
Analysis and summarized in section VIII of this preamble, OSHA's
analysis indicates that exposures at the proposed PEL can be measured
with a reasonable degree of precision and accuracy. In addition, the
analysis presented in the Technological Feasibility chapter of the
Preliminary Economic Analysis makes clear that many industries and
operations could not achieve an alternative PEL of 25 [mu]g/m\3\ with
engineering and work practice controls alone. As guided by the 1988
"Asbestos" decision (Bldg & Constr. Trades Dep't v. Brock, 838 F.2d
1258, 1266 (DC Cir. 1988)), OSHA is proposing additional requirements
to further reduce the remaining risk. OSHA anticipates that the
ancillary provisions in the proposed standard, including requirements
for regulated areas and medical surveillance, will further reduce the
risk beyond the reduction that would be achieved by the proposed PEL
alone. OSHA also believes that a new PEL, expressed as a gravimetric
measurement of respirable crystalline silica, will improve compliance
because the PEL is simple and relatively easy to understand. In
comparison, the existing PELs require application of a formula to
account for the crystalline silica content of the dust sampled and, in
the case of the construction and shipyard PELs, a conversion of mppcf
to mg/m\3\ as well.
OSHA believes that it is appropriate to establish a single PEL that
applies to respirable quartz, cristobalite, and tridymite. As explained
in the Review of Health Effects Literature and Preliminary Quantitative
Risk Assessment (see sections V and VI of this preamble for summaries),
research indicates that certain physical factors may affect the
toxicologic potency of crystalline silica. These factors include
particle surface characteristics, the age of fractured surfaces of the
crystal particle, the presence of impurities on particle surfaces, and
coating of the particle. These factors may vary among different
workplace settings, suggesting that the risk to workers exposed to a
given level of respirable crystalline silica may not be equivalent in
different work environments. The Agency's Quantitative Risk Assessment,
summarized in section VI of this preamble, relies on studies involving
a range of work environments; from study to study, workers' exposures
to respirable crystalline silica varied in terms of particle age,
surface impurities, and particle coatings. While the risk estimates
that OSHA derived using data from different work environments are
somewhat dissimilar, and these differences may be due in part to
variations in particle toxicity, all of OSHA's risk estimates indicate
significant risk above the proposed PEL of 50 [mu]g/m\3\. Thus, while
the available evidence is not sufficient to establish precise
quantitative differences in risk based on these physical factors, the
Agency's findings of significant risk are representative of a wide
range of workplaces reflecting differences in the form of silica
present, surface properties, and impurities. OSHA is therefore
proposing a single PEL for respirable quartz, cristobalite, and
tridymite.
OSHA currently has separate entries in 29 CFR 1910.1000 Table Z-1
for cristobalite, quartz, tripoli (as quartz), and tridymite. The
proposal would present a single entry for crystalline silica, as
respirable dust, with a cross reference to the new standard. As
discussed above, the proposed PEL applies to quartz, cristobalite, and
tridymite. Tripoli, which is extremely fine-grained crystalline silica,
is covered under the proposed PEL as quartz. Comparable revisions would
be made to 29 CFR 1915.1000 Table Z and 29 CFR 1926.55 Appendix A.
(d) Exposure Assessment
Paragraph (d) of the proposed standard 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).
As a general matter, monitoring of 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 level 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, the
availability of exposure data enables PLHCPs performing medical
examinations to be informed of the extent of occupational exposures.
Paragraph (d)(1) contains proposed general requirements for
exposure assessment. The general requirements for assessing exposure to
respirable crystalline silica in the proposed standard are similar to the
requirements contained in previous OSHA substance-specific health
standards. Except as provided for in the construction standard under
paragraph (d)(8), paragraph (d)(1)(i) requires each employer to assess
the exposure of any employees who are exposed, or may reasonably be
expected to be exposed, to respirable crystalline silica at or above
the action level. Under paragraph (d)(1)(ii), monitoring to determine
employee exposures must represent the employee's time-weighted average
exposure to airborne respirable crystalline silica over an 8-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.
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, as set out in
proposed paragraph (d)(1)(iii), monitoring of "representative"
employees is sufficient. Representative exposure sampling is permitted
when a number of employees perform essentially the same job on the same
shift and under the same conditions. For employees engaged in similar
work, it may be sufficient to monitor a fraction of these employees in
order to obtain data that are "representative" of the remaining
employees. Under the proposed standard, a representative sample must
include employee(s) reasonably expected to have the highest exposures.
For example, this may involve monitoring the exposure of the employee
closest to an exposure source. This exposure result may then be
attributed to the remaining employees in the group.
Representative exposure monitoring must include at least 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 either a
single sample characteristic of the entire shift or consecutive samples
taken over the length of the shift. In many cases, full-shift samples
on two or more days may be necessary to adequately characterize
exposure and obtain results that are representative of employees with
the highest exposure for each job classification. 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.
Paragraph (d)(2)(i) of the proposed standard requires employers to
conduct an initial exposure assessment by performing initial monitoring
of any employees who are exposed, or may reasonably be expected to be
exposed, to respirable crystalline silica at or above the action level.
Further obligations under the standard are based on the results of this
initial assessment. These may include obligations for periodic
monitoring, establishment of regulated areas, implementation of control
measures, and provision of medical surveillance.
The proposed standard, paragraph (d)(2)(ii), provides two
exceptions to the requirement to conduct initial exposure monitoring.
First, under paragraph (d)(2)(ii)(A), employers may rely on existing
monitoring data to satisfy the requirement for an initial exposure
assessment if employee exposures have been monitored within 12 months
prior to the effective date of the standard under conditions that
closely resemble those currently prevailing, and if that monitoring was
conducted using one of the sampling and analytical methods specified in
paragraph (d)(5)(i). This provision is intended to make it clear that
employers who have recently performed appropriate employee monitoring
will not be required to conduct additional monitoring to satisfy the
requirement for "initial" monitoring. OSHA anticipates that this
provision will reduce the compliance burden on employers who have
already assessed exposure levels, since "initial" monitoring would
not be required. The Agency believes the use of data obtained no more
than 12 months prior to the effective date is appropriate, since
samples taken more than 12 months before the effective date may not
adequately represent current workplace conditions. The 12 month limit
is consistent with the methylene chloride standard, 29 CFR 1910.1052.
Second, to meet the requirement for an initial exposure assessment,
the employer may, under paragraph (d)(2)(ii)(B), use objective data
that demonstrate that respirable crystalline silica will not be
released in airborne concentrations at or above the action level under
any expected conditions of processing, use, or handling. Objective data
must demonstrate that the work operation or the product may not
reasonably be foreseen to release respirable crystalline silica in
concentrations at or above the action level under any expected
conditions of use. OSHA has allowed employers to use objective data in
lieu of initial monitoring in other standards, such as formaldehyde (29
CFR 1910.1048) and asbestos (29 CFR 1910.1001). Any existing air
monitoring data or objective data used in lieu of conducting initial
monitoring must be maintained in accordance with the recordkeeping
requirements in paragraph (j) of this standard.
Paragraph (d)(3) of the proposed standard requires the employer to
assess employee exposure to respirable crystalline silica on a periodic
basis for employees exposed at or above the action level. 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. If the initial
monitoring indicates employee exposure are at or above the action
level, then the employer has the choice of following either a fixed
schedule option or a performance option for periodic exposure
assessments.
The fixed schedule option in paragraph (d)(3)(i) specifies the
frequency of monitoring based on the results of the initial and
subsequent monitoring. If the initial monitoring indicates employee
exposures to be at or above the action level but at or below the PEL,
the employer must perform periodic monitoring at least every six
months. If the initial or subsequent monitoring reveals employee
exposures to be above the PEL, the employer must repeat monitoring at
least every three months. If periodic monitoring results indicate that
employee exposures have fallen below the action level, and those
results are confirmed 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
unless, under paragraph (d)(4), changes in the workplace result in new
or additional exposures.
OSHA recognizes that exposures in the workplace may fluctuate.
Periodic monitoring provides the employer with assurance that employees
are not experiencing exposures that are higher than expected and
require the use of additional control measures. 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 believes that when
initial monitoring results equal or exceed the action level, but are at
or below the PEL, employers should 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. If
the employer installs or upgrades controls, periodic monitoring will
demonstrate whether or not controls are working properly. 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
believes that the proposed frequencies of six months for subsequent
periodic monitoring for exposures at or above the action level but at
or below the PEL, and three months for exposures above the PEL, provide
intervals that are both practical for employers and protective for
employees. This belief is supported by OSHA's experience with
comparable monitoring intervals in other standards, including those for
cadmium (29 CFR 1910.1027), methylenedianiline (29 CFR 1910.1050),
methylene chloride (29 CFR 1910.1052), and formaldehyde (29 CFR
1910.1048).
OSHA recognizes that monitoring can be a time-consuming, expensive
endeavor and therefore offers employers the incentive of discontinuing
monitoring for employees whose sampling results indicate exposures are
below the action level. Periodic monitoring for a specific worker or
representative group of workers can be discontinued when at least two
consecutive measurements taken at least seven days apart are below the
action level, because this indicates a low probability that under the
prevailing conditions exposure levels exceed the PEL. Therefore the
final rule provides an incentive for employers to control their
employees' exposures to respirable crystalline silica to below the
action level to minimize their exposure monitoring obligations while
maximizing the protection of employees' health.
The performance option described in paragraph (d)(3)(ii) of the
proposed standard provides employers flexibility to assess 8-hour TWA
exposures 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 operations are of short duration or performed under varying
environmental conditions. The performance option is intended to allow
employers flexibility in performing periodic exposure assessments.
Where the employer elects this option, the employer must conduct the
exposure assessment prior to the time the work operation commences, and
must demonstrate that employee exposures have been accurately
characterized.
Previous OSHA substance-specific health standards have usually
allowed employers to use objective data to characterize employee
exposures, but have generally limited its use to demonstrating that
exposures would be below the action level (e.g., cadmium, 29 CFR
1910.1027(d)(2)(iii)). In this instance, OSHA proposes to allow
reliance on the use of objective data for periodic exposure
assessments, even where exposures may exceed the action level or PEL.
However, the burden is on the employer to show that the exposure
assessment is sufficient to accurately characterize employee exposures
to respirable crystalline silica. For example, where an employer has a
substantial body of data (from previous monitoring, industry-wide
surveys, or other sources) indicating that worker exposures in a given
operation exceed the PEL, but do not exceed 10 times the PEL under any
expected conditions, the employer may choose to rely on that data to
determine his or her compliance obligations (e.g., implementation of
feasible engineering and work practice controls, respiratory
protection, medical surveillance). OSHA's intent is to allow employers
flexibility in methods used to assess employee exposures to respirable
crystalline silica, but to ensure that the methods used are accurate in
characterizing employee exposures. Any objective data relied upon must
be maintained and made available in accordance with the recordkeeping
requirements in paragraph (j)(2) of the proposed standard.
Under paragraph (d)(4), the employer is required to reevaluate
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. For
example, if an employer has conducted monitoring during an operation
while using local exhaust ventilation, and the flow rate of the
ventilation system is decreased, then additional monitoring would be
necessary to assess employee exposures under the modified conditions.
In addition, there may be other situations which can result in new or
additional exposures to respirable crystalline silica which are unique
to an employee's work situation. For instance, a worker may move from
an open, outdoor location to an enclosed or confined space. Even though
the task performed and materials used may remain constant, the changed
environment could reasonably be expected to result in higher exposures
to respirable crystalline silica. In order to cover those special
situations, OSHA requires the employer to conduct an additional
exposure assessment whenever a change may result in new or additional
exposures at or above the action level. This reevaluation is 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. On the other
hand, additional monitoring is not required simply because a change has
been made, if the change is not reasonably expected to result in new or
additional exposures to respirable crystalline silica at or above the
action level.
Paragraph (d)(5) of the proposed standard contains specifications
for the methods to be used for sampling and analysis of respirable
crystalline silica samples. OSHA has typically included specifications
for the accuracy of exposure monitoring methods in substance specific
standards, but not the specific analytical methods to be used or the
qualifications of the laboratory that analyzes the samples. The
proposed standard includes details regarding the specific sampling and
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 the Technological Feasibility section of the Preliminary
Economic Analysis, the Agency has preliminarily determined that these
provisions are needed to ensure that monitoring can be relied upon to
accurately measure employee exposures.
Under proposed paragraph (d)(5)(i), 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 in
environments subject to the Agency's jurisdiction. 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 standard, the standard requires that air
samples are to be analyzed only at accredited laboratories that meet
six requirements listed in paragraphs (d)(5)(ii)(A-F). The requirements
were developed based on procedures implemented at laboratories that
have achieved acceptable levels of accuracy and precision during a
study of inter-laboratory variability. An employer who engages an
independent laboratory to analyze respirable crystalline silica samples
could 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.
Paragraph (d)(5)(ii)(A) 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.
Paragraphs (d)(5)(ii)(B)-(F) contain additional requirements for
laboratories that have been demonstrated to improve accuracy and
reliability through inter-laboratory comparisons. The laboratory must
participate in a round robin testing program with at least two other
independent laboratories at least every six months. An example of a
testing program that satisfies this requirement, as it is currently
implemented, is the program established by AIHA Proficiency Analytical
Testing Programs, LLC. 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. The laboratory must have an internal quality control (QC)
program that evaluates analytical uncertainty and provides employers
with estimates of sampling and analytical error. 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. 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. 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.
Under paragraph (d)(6) of the proposed rule, employers covered by
the general industry standard must notify each affected employee within
15 working days of completing an exposure assessment. Notification is
required whenever an exposure assessment has been conducted regardless
of whether or not employee exposure exceeds the action level or PEL. In
construction, employers must notify each affected employee not more
than five working days after the exposure assessment has been
completed. A shorter time period for notification is provided in
construction in recognition of the often short duration of operations
and employment in particular locations in this sector. The time allowed
for notification is consistent with the harmonized notification times
established for certain health standards applicable to general industry
and construction in Phase II of OSHA's Standards Improvement Project.
70 FR 1112; January 5, 2005. Where the employer follows the scheduled
monitoring option provided for in paragraph (d)(3)(i), the 15 (or five)
day period for notification commences when monitoring results are
received by the employer. For employers following the performance-
oriented option under paragraph (d)(3)(ii), the period commences when
the employer makes a determination of the exposure levels and the need
for corresponding control measures (i.e., prior to the time the work
operation commences, and whenever exposures are re-evaluated).
The notification requirements in this provision apply to all
employees for which an exposure assessment has been conducted, either
individually or as part of a representative monitoring strategy. It
includes employees who were subject to personal monitoring, as well as
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. The employer shall either notify each affected
employee in writing or post the monitoring results in an appropriate
location accessible to all affected employees. In addition, paragraph
(d)(6)(ii) 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. 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).
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: "Workers provided the
necessary hazard information will more fully participate in, and
support, the protective measures instituted in their workplaces." 59
FR 6126, 6127; Feb. 9, 1994. 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.
Paragraph (d)(7) 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 fixed schedule option or the
performance option. When observation of monitoring requires entry into
an area where the use of protective clothing or equipment is required,
the employer must provide the observer with that protective clothing or
equipment, 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).
Table 1 in paragraph (f) of the proposed construction standard
lists exposure control methods for selected construction operations. As
discussed with regard to paragraph (f), OSHA has preliminarily
determined that the engineering controls, work practices, and
respiratory protection specified for each operation in Table 1
represent appropriate and effective controls for those operations.
Therefore, paragraph (d)(8) of the proposed construction standard makes
an exception to the general requirement for exposure assessment where
employees perform operations in Table 1 and the employer has fully
implemented the controls specified for that operation. This relieves
the employer of the burden of performing exposure monitoring in these
situations.
Where the employer elects to implement the control measures
specified in Table 1 for a given construction operation, paragraph
(d)(8)(ii) requires that the employer presume that each employee
performing an operation listed in Table 1 that requires a respirator is
exposed above the PEL, unless the employer can demonstrate otherwise in
accordance with paragraph (d) of the proposed rule. So, for example, if
an employer elects to implement the controls specified in Table 1 for a
given construction operation that requires a respirator and does not
conduct an exposure assessment to demonstrate that exposures are below
the PEL, the employer would be required to provide each employee
performing that operation for 30 or more days per year with medical
surveillance in accordance with paragraph (h) of the proposed rule.
(e) Regulated Areas and Access Control
Under paragraph (e)(1) in the standards, employers have two options
wherever an employee's exposure to airborne concentrations of
respirable silica is, or can reasonably be expected to be, in excess of
the PEL: (1) the establishment of regulated areas in accordance with
paragraph (e)(2); or (2) the implementation of a written access control
plan in accordance with paragraph (e)(3).
The purpose of a regulated area is to ensure that the employer
makes employees aware of the presence of respirable crystalline silica
at levels above the PEL, and to limit exposure to as few employees as
possible. The establishment of a regulated area is an effective means
of minimizing exposure to employees not directly involved in operations
that generate respirable crystalline silica and limiting the risk of
exposure to a substance known to cause adverse health effects. Because
of the potentially serious results of exposure and the need for persons
entering the area to be properly protected, the number of persons given
access to the area should be limited to those employees needed to
perform the job. Limiting access to regulated areas also has the
benefit of reducing the employer's obligation to implement other
provisions of this proposed standard to as few employees as possible.
Under paragraph (e)(2)(ii), regulated areas are to be demarcated
from the rest of the workplace in any manner that adequately
establishes and alerts employees to the boundary of the regulated area,
and minimizes the number of employees exposed to respirable crystalline
silica within the regulated area. OSHA has not specified how employers
are to demarcate regulated areas. Signs, barricades, lines, or textured
flooring may each be effective means of demarcating the boundaries of
regulated areas. Permitting employers to choose how best to identify
and limit access to regulated areas is consistent with OSHA's belief
that employers are in the best position to make such determinations,
based on their knowledge of the specific conditions of their
workplaces. Whatever methods are chosen to establish a regulated area,
the demarcation must effectively warn employees not to enter the area
unless they are authorized, and then only if they are using the proper
personal protective equipment. Allowing employers to demarcate and
limit access to the regulated areas as they choose is consistent with
recent OSHA substance-specific health standards, such as chromium (VI)
(29 CFR 1910.1026) and 1,3-butadiene (29 CFR 1910.1051).
Paragraph (e)(2)(iii) describes who may enter regulated areas. In
both standards, access to regulated areas is restricted to persons
required by their job duties to be present in the area, as authorized
by the employer. In addition, designated employee representatives
exercising the right to observe monitoring procedures are allowed to
enter regulated areas. For example, employees in some workplaces may
designate a union representative to observe monitoring; this person
would be allowed to enter the regulated area. Persons authorized under
the OSH Act, such as OSHA compliance officers, are also allowed access
to regulated areas.
Under paragraph (e)(2)(iv), employers must provide each employee
and designated representative who enters a regulated area with an
appropriate respirator in accordance with paragraph (g), and require
that the employee or designated representative uses the respirator
while in the regulated area. 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 is 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 believes this proposed requirement is simple to administer
and enforce, protective of employee health, and consistent with general
practice in management of regulated areas.
OSHA has proposed a requirement for use of protective clothing or
other measures to limit contamination of clothing for employees working
in regulated areas. Paragraph (e)(2)(v) requires that, where there is
the potential for employees' work clothing to become grossly
contaminated with finely divided material containing crystalline
silica, the employer must either provide appropriate
protective clothing such as coveralls or
similar full-bodied clothing, or else provide a means to remove
excessive silica dust from contaminated clothing when exiting the
regulated area. This provision is intended to limit additional
respirable crystalline exposures to employees in regulated areas that
could result from disturbing the dust that has accumulated on their
clothing. It is also intended to protect employees in adjacent areas
from exposures that could occur if employees with grossly contaminated
clothing were to carry crystalline silica dust to other areas of the
workplace. The purpose of this provision is not, however, to protect
employees from dermal exposure to crystalline silica, as discussed
further below.
In paragraph (e)(2)(v)(A), the proposal refers to "finely divided
materials." When using this term, the proposed standard refers to
particles with very small diameters (i.e., <= 10 [mu]m) such that, once
airborne, the particles would be considered respirable dust. "Gross
contamination" refers to a substantial accumulation of dust on
clothing worn by an employee working in a regulated area such that
movement by the individual results in the release of dust from the
clothing. The provision is not intended to cover any contamination of
clothing, but rather those limited circumstances where significant
quantities of dust are deposited on workers' clothing. Where such
conditions exist, OSHA anticipates that the dust present on workers'
clothing or the release of dust from the clothing would be plainly
visible.
Under paragraphs (e)(2)(v)(A)(1)-(2), the employer would have the
option of providing either appropriate protective clothing, such as
coveralls that can be removed upon exiting the regulated area, or any
other means of removing excessive silica dust from contaminated
clothing that minimizes employee exposure to respirable crystalline
silica. The employer may choose the approach that works best in the
circumstances found in a particular workplace. The employer may choose,
for example, to provide HEPA vacuums for removal of dust from clothing.
It should be noted, however, that paragraph (f)(3)(ii)
(paragraph(f)(4)(ii) of the standard for construction) prohibits 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 employee exposure to respirable crystalline silica
that exceeds the PEL. Paragraph (e)(2)(v) requires contaminated
clothing to be either cleaned or removed upon exiting the regulated
area, in order to ensure that other areas of the workplace do not
become contaminated. Cleaning or removal of contaminated clothing must
take place prior to removal of respiratory protection in order to
ensure that any exposure to dust released from contaminated clothing is
minimized.
In other substance-specific chemical standards, OSHA has typically
included requirements for provision of protective clothing, as well as
associated provisions addressing removal, storage, cleaning, and
replacement of protective clothing. The proposed provisions for this
respirable crystalline standard are more limited than other OSHA
standards, in that the requirements only apply in regulated areas, and
then only when there is the potential for clothing to become grossly
contaminated. The employer is also given the option of providing other
means to remove dust from contaminated clothing, an alternative not
generally available in other OSHA standards. OSHA has proposed these
more limited provisions because the Agency has made a preliminary
determination that the proposed provisions will serve to reduce
employee exposures, and that additional requirements for protective
clothing are not reasonably necessary and appropriate.
Most other chemicals regulated under OSHA substance-specific
standards either have direct dermal effects or can contribute to
overall exposures through dermal absorption. OSHA is not aware of any
evidence that dermal exposure is a concern for respirable crystalline
silica. Moreover, dusts containing crystalline silica are ubiquitous in
many of the work environments covered by this proposed standard.
Therefore, the proposed silica standard focuses on those situations
where contamination of clothing has the potential to contribute
significantly to employee inhalation exposures. OSHA recognizes that
the ASTM standards addressing occupational exposure to respirable
crystalline silica do not include requirements for protective clothing.
However, the Agency believes that the proposed provisions will serve to
limit employee exposures in those situations where contamination of
clothing contributes to inhalation exposures. OSHA also notes that the
Agency's Advisory Committee on Construction Safety and Health
recommended that OSHA maintain the language on protective clothing that
was included in the draft provided for review under the Small Business
Regulatory Enforcement Fairness Act (SBREFA). The SBREFA draft language
would have required protective clothing or a means to vacuum
contaminated clothing for all employees exposed above the PEL. The
Agency seeks comment on the proposed provisions for protective clothing
and has included this topic in the "Issues" section of this preamble.
OSHA's standard addressing sanitation in general industry (29 CFR
1910.141) requires that whenever employees are required by a particular
standard to wear protective clothing because of the possibility of
contamination with toxic materials, change rooms equipped with storage
facilities for street clothes and separate storage facilities for
protective clothing shall be provided (29 CFR 1910.141(e)). The
sanitation standard also includes provisions for lavatories with
running water (29 CFR 1910.141(d)(2)), and prohibits storage or
consumption of food or beverages in any area exposed to a toxic
material (29 CFR 1910.141(g)(2)). Similar provisions are in place for
construction (29 CFR 1926.51). OSHA expects that employers will comply
with the provisions of the sanitation standard when required. Thus, no
additional requirements for hygiene practices are included in the
proposed silica standards.
The proposed standard provides two options for employers to choose
between for minimizing exposure to employees not directly involved in
operations that generate respirable crystalline silica. The
establishment of regulated areas under paragraph (e)(2), as described
above, is the first option for exposure control in workplaces, and when
fully implemented will satisfy this requirement. However, OSHA
recognizes that establishing regulated areas in some workplaces can be
difficult. For example, in the SBREFA review process, the question was
raised as to how a regulated area could be established for a highway
project, where the source of exposure could be constantly moving. Some
activities covered by the general industry/maritime standard may
present similar difficulties, such as hydraulic fracturing operations
where exposures may occur over a large area. In recognition of the
practical problems that may be encountered in such circumstances, the
proposed standard includes an option in paragraph (e)(3) for
establishing and implementing a written access control plan in lieu of
a regulated area.
Paragraph (e)(3)(ii) in the standard sets out the requirements for
a written access control plan. The plan must contain provisions for a
competent person to identify the presence and location of any areas
where respirable crystalline silica exposures are, or can
reasonably be expected to be, in excess of the PEL. It must describe
how employees will be notified of the presence and location of areas
where exposures are, or can reasonably be expected to be, in excess of
the PEL, and how these areas will be demarcated from the rest of the
workplace. For multi-employer workplaces, the plan must identify the
methods that will be used to inform other employers of the presence and
the location of areas where respirable crystalline silica exposures
are, or can reasonably be expected to be, in excess of the PEL, and any
precautionary measures that need to be taken to protect employees. The
written plan must contain provisions for limiting access to these
areas, in order to minimize the number of employees exposed and the
level of employee exposure. The plan must also describe procedures for
providing each employee working in areas where respirable crystalline
silica exposures are, or can reasonably be expected to be, in excess of
the PEL with an appropriate respirator in accordance with paragraph (g)
of this section. Where there is the potential for employees' work
clothing to become grossly contaminated with finely divided material
containing crystalline silica, the access control plan must include
provisions for the employer to provide either appropriate protective
clothing, or a means to remove excessive silica dust from contaminated
clothing that minimizes employee exposure to respirable crystalline
silica. The access control plan must also include provisions for
removal or cleaning of such clothing.
The employer must review and evaluate the effectiveness of the
written access control plan at least annually and update it as
necessary. The written access control plan must be available for
examination and copying, upon request, to employees, their designated
representatives, the Assistant Secretary and the Director.
The intent of the provision for establishing written access control
plans in lieu of regulated areas is to provide employers with
flexibility to adapt to the particular circumstances of their worksites
while maintaining equivalent protection for employees. The Agency seeks
comment on this proposed approach and has included this topic in the
"Issues" section of this preamble.
(f) Methods of Compliance
Paragraph (f)(1) of the proposed rule establishes a hierarchy of
controls which employers must use to reduce and maintain exposures to
respirable crystalline silica to or below the permissible exposure
limit (PEL). The proposed 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 proposed rule.
OSHA proposes to require primary reliance on engineering controls and
work practices because reliance on these methods is consistent with
good industrial hygiene practice, with the Agency's experience in
ensuring that workers have a healthy workplace, and with the Agency's
traditional adherence to a hierarchy of preferred controls.
OSHA requires adherence to this hierarchy of controls in a number
of current standards, including the Air Contaminants (29 CFR 1910.1000)
and Respiratory Protection (29 CFR 1910.134) standards, as well as
previous substance-specific standards. The Agency's adherence to the
hierarchy of controls has been successfully upheld by the courts (see
AFL-CIO v. Marshall, 617 F.2d 636 (D.C. Cir. 1979) (cotton dust
standard); United Steelworkers v. Marshall, 647 F.2d 1189 (DC Cir.
1980), cert. denied, 453 U.S. 913 (1981) (lead standard); ASARCO v.
OSHA, 746 F.2d 483 (9th Cir. 1984) (arsenic standard); Am. Iron & Steel
v. OSHA, 182 F.3d 1261 (11th Cir. 1999) (respiratory protection
standard); Pub. Citizen v. U.S. Dep't of Labor, 557 F.3d 165 (3rd Cir.
2009) (hexavalent chromium standard)).
The Agency understands 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 workers; (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, especially at construction sites, who are not
directly involved in the task that is generating the dust, and may not
be wearing respirators.
Respirators are another important means of protecting workers 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 worker'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 the workplace as a whole, 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
considers 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 odor 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 workers 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.
These concerns about the burdens placed on workers by the use of
respirators were acknowledged in OSHA's revision of its Respiratory
Protection standard, and are the basis for the requirement 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 (63 FR 1152, Jan. 8,
1998). Although experience in industry shows that most healthy workers
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.
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 workers and can cause
workers to refrain from wearing the respirator, thereby rendering it
ineffective.
While OSHA acknowledges that certain types of respirators may
lessen problems associated with breathing resistance and skin
discomfort, OSHA does not believe that respirators 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. OSHA has evaluated the level of protection offered by
different types of respirators in the Agency's Assigned Protection
Factors rulemaking (68 FR 34036, June 6, 2003). 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 workers 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 that may be lighter
and easier to use when compared with full-facepiece respirators.
In summary, engineering and work practice controls are capable of
reducing or eliminating a hazard from the workplace; respirators
protect only the employees who are wearing them. In addition, the
effectiveness of respiratory protection always depends on the actions
of employees, while the efficacy of engineering controls is generally
independent of the individual. OSHA believes that engineering controls
offer more reliable and consistent protection to a greater number of
workers, and are therefore preferable to respiratory protection.
Engineering controls. The engineering controls presented in this
proposal can be grouped into these main 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. 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.
The technological feasibility study (PEA, Chapter 4) indicates that
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. If substitutes for crystalline silica are being used in any
operation not considered in the feasibility study, OSHA is requesting
relevant information that contains data supporting the effectiveness,
in reducing exposure to crystalline silica, of substitutes currently
being used.
Before replacing a toxic material with a substitute, it is
important that employers evaluate the toxicity of the substitute
materials relative to the toxicity of the original material. Substitute
materials that pose significant new or additional risks to workers are
not a desirable means of control. Additionally, employers must comply
with Section 5(a)(1) of the OSH Act, which prohibits occupational
exposure to "recognized hazards that are causing or are likely to
cause death or serious physical harm." 29 U.S.C. 654(a)(1). Employers
must also comply with applicable standards. 29 U.S.C. 654(a)(2). For
example, with respect to chemical hazards, OSHA's Hazard Communication
standard imposes specific requirements for employee training, material
safety data sheets, and labeling. 29 CFR 1910.1200.
While the Agency's technological feasibility analysis includes
information about materials that some employers use as alternatives to
silica or silica-containing materials, the Agency recognizes that these
substitute materials may present health risks. OSHA does not intend to
imply that any particular material is an appropriate or safe substitute
for silica. Isolation. Isolation, by means of a process enclosure, is
another effective engineering control employed to reduce exposures to
crystalline silica. It refers to a physical barrier normally
surrounding the source of exposure and installed 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 workers who are not directly involved in dust-
generating operations.
Due to the shift from manually operated to automated processes,
enclosures have become more practicable. For example, forming line
operators in structural clay products manufacturing can use automation
for transfer of materials, allowing conveyors and milling areas to be
enclosed (OSHA SEP Inspection Report 300523396). Another example can be
observed in automated refractory demolition and installation methods. A
"pusher" system installed in coreless induction furnaces allows
refractory linings to be automatically pressed out by push plates
installed in furnace bottoms. A representative of Foundry Products
Supplier B (2000a) estimated that total worker exposure using a pusher
system would be roughly half that of traditional
chipping refractory removal methods and possibly as much as 80 percent
less if an enclosure (tarp) was used over the end of the furnace from
which the lining is extruded. At a pottery facility, the exposure for a
material handler monitoring automated equipment that is adding silica-
containing raw materials to a mixer was about 66 percent lower than the
exposure of a material handler manually adding the material to the
mixer (OSHA SEP Inspection Report 300384435). At a structural clay
industry facility inspected by OSHA, an 86-percent reduction in
respirable quartz exposure readings occurred after management installed
an enclosed, automated sand transfer system, despite not having
optimally sealed components (PEA, Chapter 4).
Workers can also be isolated from a hazardous source when they
operate heavy machinery equipped with enclosed cabs. In such cases, a
cab that is well sealed and equipped with ventilation and a high-
efficiency particulate air (HEPA) filter can minimize the potential for
exposure from the dust created outside the cab.
MSHA (1997) recommended the following controls to maximize the
effectiveness of an enclosed cab: keeping the cab interior's horizontal
and vertical surfaces and areas clean and free of debris; inspecting
door seals and closing mechanisms to ensure they work properly;
ensuring that seals around windows, power line entries, and joints in
the walls and floors of the cab are tightly sealed; ensuring that air
conditioners are designed so that air comes in from the outdoors to
create positive pressure and passes first through a pre-filter (those
with an American Society of Heating, Refrigeration and Air-Conditioning
Engineers efficiency rating of 90 percent are common) and then through
a HEPA filter; and ensuring that HEPA filters are changed when they
reach the manufacturer's final resistance value (MSHA, 1997).
Tractors, front-end loaders, and other mobile material-handling
equipment equipped with properly enclosed, sealed, and ventilated
operator cabs (i.e., no leaks, positive pressure, and effective air
filtration) can substantially reduce silica exposures associated with
the use of such equipment. 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 96 percent when cabs are clean,
sealed, and have a functionally adequate filtration and pressurization
system. Gravimetric sampling instruments found an average cab
efficiency of about 93 percent when comparing dust levels outside and
inside the cab (Cecala et al., 2005). Similarly, NIOSH investigators
reported respirable dust exposure reductions of 97 and 98 percent,
respectively, inside the cabin of a modified railroad ballast dumper in
the railroad transportation industry (NIOSH HHE 92-0311, 2001). Other
researchers have reported particle reductions inside the operator cab
greater than 90 percent (Hall et al., 2002).
The Agency recognizes that although enclosed cabs have been proven
to be an effective control method, they do not control exposures at the
source. In many circumstances, machine operators work alongside
employees who are outside the enclosed cabs and are not protected by
them. As such, OSHA expects employers to apply all other feasible
controls to protect those employees.
In certain situations, a process enclosure can enhance the benefits
of other control methods when used simultaneously, such as when an
enclosure is equipped with local exhaust ventilation (LEV). When the
enclosure contains the crystalline-silica-containing dust cloud, the
ventilation system is able to remove that contaminant in a more
effective and timely fashion, as opposed to having it dissipate out of
the ventilation system's exhaust range where there is no enclosure.
In the asphalt roofing manufacturing industry, the capture of
process emissions (including dust) at the coater station is best
achieved by using LEV in conjunction with an enclosure. When using a
full enclosure with LEV, NIOSH recommends several practices that
improve the capture efficiency of the ventilation system. OSHA believes
these recommendations are beneficial whenever this control method is
used in a production line. The recommendations are: (1) When process
enclosures are used, the number and size of openings in the enclosure
must be minimized to prevent a reduction in the capture efficiency of
the ventilation system; (2) all doors should be adequately sealed and
closed during operation of the line; (3) the size of the opening where
the product enters and leaves the process equipment should be minimized
to ensure an inward flow of air by the negative pressure within the
enclosure; and (4) negative pressure must be maintained inside the
enclosure to prevent leakage of process emissions into the workplace.
In the foundry industry, shakeout operators are responsible for
monitoring equipment that separates the casting being produced from the
molding material. This process generally involves shaking the casting,
which creates dust exposure associated with respirable crystalline
silica levels above the PEL. OSHA has determined that employers using
this process should enclose the shakeout operations, and the most
effective method to reduce exposure is installing efficient ventilation
(PEA, Chapter 4).
Another example occurs in the masonry industry, when stationary
saws are placed inside ventilated enclosures, and the set-up permits
the operator to stand outside the enclosure. A 78-percent reduction in
respirable quartz exposure was observed (from 354 [mu]g/m\3\ to 78
[mu]g/m\3\) when workers used a site-built ventilated booth outdoors as
opposed to cutting with no booth (ERG-C, 2008).
Ventilation. 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: 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 Hexavalent Chromium Rule,
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.
The use of effective exhaust ventilation in controlling worker
exposures to crystalline silica can be illustrated by an example in the
mineral processing industry. Here, the highest exposure levels obtained
by OSHA were associated with bag dumping and disposal operations at a
pottery clay manufacturing company (OSHA SEP Inspection Report
116178096). After the facility installed ventilated bag disposal
hoppers, HEPA filters, and an enhanced LEV system, the exposure of the
production workers was reduced by about 80 percent (from 221 [mu]g/m\3\
to 44 [mu]g/m\3\). A Canadian study of a rock-crushing plant also shows
the effectiveness of LEV systems (Grenier, 1987); the plant, originally
equipped with a general exhaust ventilation system with fabric dust
collectors, processed rock containing as much as 60 percent crystalline
silica. Operation of the LEV system was associated with reductions of
respirable crystalline silica levels ranging from 20 to 79 percent.
LEV can be adapted to diverse sources of emissions. For workers who
empty bags or mix powders that contain crystalline silica material, a
portable exhaust trunk positioned near the bag-dumping hopper can
capture a portion of the dust released during that activity. Additional
crystalline silica exposure can occur when workers compress empty bags,
an activity that can also be performed with LEV control (PEA, Chapter
4).
LEV can also be applied to operations involving portable tools. The
benefits of tool-mounted LEV systems for controlling crystalline silica
have been demonstrated by two NIOSH evaluations. In one evaluation,
NIOSH tested two tool-mounted LEV shrouds for hand-held pneumatic
chipping equipment (impact drills): one custom built, the other a
commercially available model. Comparing multiple short-term exposure
samples, NIOSH found that the shrouds reduced personal breathing zone
(PBZ) respirable dust by 48 to 60 percent (NIOSH, 2003-EPHB 282-11a).
In a separate evaluation, NIOSH collected short-term PBZ samples while
workers used 25- or 30-pound jackhammers to chip concrete from inside
concrete mixer truck drums. During 90- to 120-minute periods of active
chipping, mean respirable silica levels decreased by 69 percent when
the workers used a tool-mounted LEV shroud in these enclosed spaces
(NIOSH, 2001-EPHB 247-19).
In the railroad transportation industry, dust control kits that
incorporate LEV are designed to reduce the amount of ballast dust
released by activities of heavy equipment during maintenance. These
kits can be used with brooming equipment (mechanical sweepers) and
present an alternative to relying on cab modification. Workers that
operate brooming equipment have the greatest potential for elevated
exposures among workers in this industry, and the Agency believes that
kits would be a better control measure than cab modification because
they reduce exposures at the source. Unfortunately, information
regarding the effectiveness of these kits in reducing worker exposure
to crystalline silica is not available from the manufacturer. OSHA is
therefore requesting any relevant information that would aid the Agency
in determining the potential impact of dust control kits in the
railroad transportation industry (HTT, 2003; ERG-GI, 2008).
Based on the information presented in OSHA's technological
feasibility analysis, many exposures in the workplace have occurred, in
part, due to faulty ventilation systems and improper work practices
that minimize their efficiency. In many cases, exposures can be reduced
with the proper use and maintenance of ventilation systems (PEA,
Chapter 4).
Dust suppression. 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 (Smandych
et al., 1998). Dust suppression can be accomplished by one of three
systems: (1) wet dust suppression, in which a liquid or foam is applied
to the surface of the dust-generating material; (2) airborne capture,
in which moisture is dispensed into a dust cloud, collides with
particles, and causes them to drop from the air; and (3) 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 encountered during the
technological feasibility review correspond to wet methods (PEA,
Chapter 4). 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.
In its analysis of technological feasibility, OSHA demonstrated
that wet methods are effective in a wide variety of operations. For
example, respirable quartz exposures for masonry cutters using
stationary saws were substantially lower when wet cutting was performed
instead of dry cutting (mean levels of 42 [mu]g/m\3\ versus 345 [mu]g/
m\3\). Also, the exposure level for fabricators in the stone and stone
products industry, who produce finished stone products from slabs, can
be reduced substantially by applying wet method controls. Simcox et al.
(1999) shows that exposures of fabricators at granite-handling
facilities were reduced by 88 percent (490 [mu]g/m\3\ to 60 [mu]g/m\3\)
when all dry-grinding tools used on granite were either replaced or
modified to be water-fed.
Regarding the application of wet methods to operations involving
portable equipment, recent studies show that using wet methods to
control respirable dust released during chipping with hand-held
equipment can reduce worker exposure substantially. NIOSH (2003-EPHB
282-11a) investigated a water-spray dust control used by construction
workers breaking concrete with 60- and 90-pound jackhammers. A spray
nozzle was fitted to the body of the chipping tool, and a fine mist was
directed at the breaking point. Compared with uncontrolled pavement
breaking, PBZ respirable dust concentrations were between 72 and 90
percent lower when the water spray was used. Williams and Sam (1999)
also reported that a water-spray nozzle mounted on a hand-held
pneumatic chipper decreased respirable dust by approximately 70 percent
in the worker's breathing zone.
Washing aggregate also reduces the amount of fine particulate
matter generated during subsequent use or handling. Burgess (1995)
reports that the use of washed sand, from which a substantial portion
of the fine particles have been removed, results in respirable
crystalline silica exposures that are generally lower than when sand is
not pre-washed. Plinke et al. (1992) also report that increasing
moisture content decreases the amount of dust generated and state that
it is often most efficient to apply water sprays to material before it
reaches a transfer point so that the dust has time to absorb water
before being disturbed.
For the railroad transportation industry, OSHA is recommending that
ballast be washed before it is loaded into hopper cars. Ballast wetted
at the supplier's site might dry prior to reaching the dumping site
(NIOSH HETA-92-0311, 2001). In this circumstance, applying an
additional layer of blanketing foam or other sealing chemical
suppressant on top of the rail car can reduce water evaporation and
provide an additional type of dust suppression (ECS, 2007). Work
practice controls. Work practice controls systematically modify how
workers perform an operation, and often involve workers' 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. For work practice controls to be most
effective, it is essential that workers and supervisors are 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 workers.
Work practice controls can enhance the effects of engineering
controls. For example, to ensure that LEV is working effectively, a
worker would position it so that it captures the full range of dust
created, thus minimizing silica exposures.
A good example of adequate work practice controls can be found in
ready-mixed concrete operations. Exposure data available to OSHA
indicate that all truck drivers or other workers who remove residual
concrete inside ready-mixed truck mixer drums have silica exposures
greater than the proposed PEL, with some exposures approaching 10,000
[mu]g/m\3\. The Agency recommends wet methods and ventilation as
appropriate engineering controls and also gives priority to performing
a particular work practice that can reduce exposures. Specifically,
this work practice involves the timely rinsing of drum mixers. One
report (Williams and Sam, 1999) concluded that heavy build-up of
concrete inside truck mixer drums results in higher concentrations of
worker exposure to crystalline silica during cleaning because a greater
amount of time is required to remove the build-up. Rinsing the drum
with water immediately after each load helps minimize build-up and the
resulting dust exposure. The same cleaning methods are used, such as
water pressure and scraping, independently of how often rinsing is
performed. However, by rinsing the tanks with more frequency, the
employer is modifying the nature of the cleaning operation because less
concrete will be present, and thus less respirable dust created, during
each cleaning.
Another example of good work practices can be observed in the
porcelain enameling industry. One facility stated that porcelain
applicators can ensure that they are making optimal use of LEV by
avoiding positioning themselves between the enamel spray and the
ventilation system. For large items, workers can use a turntable
support to rotate the item so that it can be sprayed on all sides while
the worker maintains the spray direction pointing into the ventilated
booth (Porcelain Industries, 2004a).
Combined control methods. Exposure documentation obtained by the
Agency demonstrates that for many operations, a combination of
engineering and work practice controls reduces silica exposure levels
more effectively than a single control method. The following examples
represent preliminary feasibility conclusions for several industries.
In the dental equipment and supplies industry, OSHA has found that
employers can limit the exposure of most workers to 50 [mu]g/m\3\ or
less by implementing a combination of engineering controls, including
improving ventilation systems (at bag-dumping stations, weighing and
mixing equipment, and packaging machinery) and designing workstations
to minimize spills, and encouraging work practices that maximize the
effect of engineering controls. One facility that implemented these
controls reduced median exposure levels by 80 percent, from 160 [mu]g/
m\3\ to 32 [mu]g/m\3\ (OSHA SEP Inspection Report 122252281).
Based on the exposure profile for the rock and concrete drilling
industry, construction sites have already achieved compliance with the
proposed PEL for about half of the workers operating drilling rigs
through a combination of controls, including wet dust suppression
methods, shrouds, and hoods connected to dust extraction equipment, and
management of dust collection dump points (PEA, Chapter 4).
An example from a routine cupola relining in the ferrous foundry
industry also demonstrates the benefit of a combination of controls.
Samples taken before and after additional controls were installed
reflect a 90-percent reduction of the median worker exposures (OSHA SEP
Inspection Report 122209679). The modifications included using
refractory material with reduced silica and greater moisture content,
improving equipment and materials to reduce malfunction and task
duration, wetting refractory material before removal, and assigning a
consistent team of trained workers to the task.
Burmeister (2001) also reported on the benefits of multiple
controls on another refractory relining activity. Initially, a full-
shift crystalline silica result of 2.74 times the current calculated
PEL was obtained while a worker chipped away the old refractory lining
and then mixed the replacement refractory material. The foundry
responded by holding a training meeting and seeking worker input on
abatement actions, implementing a water control system to reduce dust
generated during the pneumatic chipping process, purchasing chisel
retainers that eliminated the need for workers to reach into the ladle
during chipping, and purchasing a vacuum to remove dust and chipped
material from the ladle. With these changes in place, a consultant
found that exposure was reduced to 87 percent of the calculated PEL,
representing a 70-percent reduction in worker exposure.
These examples illustrate the importance and value of maintaining
an effective set of engineering controls alongside work practice
controls to optimize silica exposure reduction. The proposed
requirements 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 has explicit requirements for
methods of compliance. These requirements 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. OSHA has elected to propose a performance standard for
general industry in which particular engineering and work practice
controls are not specified. Instead, the standard requires that
employers use engineering and work practice controls to achieve the
PEL. In this case the use of properly designed, maintained, and
regularly inspected engineering controls is implied by the ongoing
ability of the employer to achieve the PEL. The national consensus
standard for construction (ASTM E 2625-09) includes task-based control
strategies for situations where exposures are known from empirical
data. This approach is consistent with the alternative approach for
construction operations in paragraph (f)(2) described below.
Paragraph (f)(2) of the proposed rule provides an alternative
approach to achieve compliance with paragraph (f), Methods of
Compliance, for construction operations. Under this paragraph,
employers that implement the specific engineering controls, work
practices, and, if required, respiratory protection described in Table
1 (please refer to paragraph (f) of the proposed rule) are considered
to be in compliance with the requirements for engineering and work
practice controls in paragraph (f)(1) of the proposed rule. An
advantage of complying with Table 1 is that the employer need not make
a determination of the hierarchy of controls, because the table
incorporates that determination for each job operation listed.
Furthermore, proposed paragraph (d)(8)(i) specifies that if an employer
chooses to follow Table 1, the employer need not conduct exposure
assessments required by paragraph (d) of the proposed rule. Rather, for
those operations in Table 1 where respirator use is required, proposed
paragraph (d)(8)(ii) requires employers to presume that workers engaged
in those operations are exposed above the PEL; in those cases, the
employer would be required to comply with all provisions of the standard that apply to
exposures above the PEL except for monitoring. For instance, when Table
1 requires workers to use respirators, the employer relying on Table 1
must: establish a regulated area or access control plan pursuant to
proposed paragraph (e); comply with the cleaning methods provisions in
proposed paragraph (f)(4); comply with the prohibition of employee
rotation as specified in proposed paragraph (f)(5); establish a
respiratory protection program pursuant to proposed paragraph (g)(2);
and provide medical surveillance pursuant to paragraph (h) if workers
are exposed for 30 or more days per year.
Table 1 was developed using recommendations made by small entity
representatives through the Small Business Regulatory Enforcement
Fairness Act (SBREFA) process. The SBREFA panel asked OSHA to develop a
provision that detailed what specific controls to use for each
construction operation covered by the rule in order to achieve
compliance with paragraph (f)(1). Additionally, the Advisory Committee
for Construction Safety and Health (ACCSH) has recommended that OSHA
proceed with the development of Table 1. The table provides a list of
13 construction operations that expose workers to respirable
crystalline silica as well as control strategies (engineering controls,
work practices, and respirators) that reduce those exposures.
In developing control strategies for each of the 13 construction
operations in Table 1, OSHA relied upon information from a variety of
sources including scientific literature, NIOSH reports, OSHA site
visits, and compliance case files (SEP reports). For several of the
listed operations and controls, the Agency requests additional
information from the public that will allow the Agency to determine
whether the operations, corresponding control strategies, and
conditions of use should be modified or removed from Table 1. OSHA also
requests comment on the degree of specificity used for engineering and
work practice controls for tasks identified in Table 1, including
maintenance requirements.
Table 1 implements a novel approach for OSHA. The Agency believes
that the table will provide significant benefits to workers and
employers by ensuring that workers are adequately protected, providing
specific approaches for complying with paragraph (f) requirements, and
reducing the monitoring and sampling burden.
The table divides operations according to duration into "less than
or equal to" four-hours-per-day tasks and "greater than" four-hours-
per-day tasks. The Agency recognizes that some activities do not last a
full work shift, and often some activities are performed for half-
shifts or less. The duration of a task influences the extent of worker
exposure and the selection of appropriate control strategies. OSHA
followed its hierarchy of controls to develop these control strategies.
Respiratory protection has been included in Table 1 for operations in
which the specified engineering and work practice controls may not
maintain worker exposures at or below the proposed PEL for all workers
and at all times. Employers who comply with Table 1 need not assess
employee exposures as otherwise required under paragraph (f), and
workers in these circumstances will not have the benefit of
conventional exposure data to characterize their exposures. Because, in
the absence of an exposure assessment, employers will not be able to
confirm that exposures are below the PEL, or identify circumstances in
which exposures may exceed the PEL, the Agency is proposing to require
respiratory protection in situations where overexposures may occur even
with the implementation of engineering and work practice controls. The
Agency is requesting comments regarding the appropriateness of the use
and selection of respirators in several operations.
If an employer anticipates that a worker will perform a single
operation listed in Table 1 for four hours or less during a single
shift, then the employer must ensure that the worker uses whichever
respirator is specified in the "<=4 hr/day" column in the table. For
example, if an employer anticipates that a worker will operate a
stationary masonry saw for four hours or less, and the worker does not
perform any other operation listed in Table 1, the worker would not be
required to use respiratory protection because there is no respirator
requirement for that entry in the table.
If an employer anticipates that a worker will perform a single
operation listed in Table 1 for more than four hours, then the employer
must ensure that the worker uses the respirator specified in the ">4
hr/day" column in Table 1 for the entire duration of the operation.
For example, if an employer anticipates that a worker will operate a
stationary masonry saw for more than four hours, and the worker does
not perform any other operation listed in Table 1, the worker would be
required to wear a half-mask respirator for the entire duration of the
operation (refer to Table 1).
Additionally, for workers who engage in two or more discrete
operations from Table 1 for a total of more than four hours during a
single work shift, employers that rely on Table 1 must provide, for the
entire duration of each operation performed, the respirator specified
in the ">4 hr/day" column for that operation, even if the duration of
that operation is less than four hours. If no respirator is specified
for an operation in the ">4 hr/day" column, then respirator use would
not be required for that part of a worker's shift.
For example, if a worker is using a stationary masonry saw for
three hours and engages in tuckpointing for two hours in the same the
shift, the employer would be required to ensure that the worker uses a
half-mask respirator for the three hours engaged in sawing, and a
tight-fitting, full-face PAPR for the two hours engaged in tuckpointing
work. In other words, if a worker uses a stationary saw and engages in
a tuckpointing operation for a total of more than four hours in a
single work shift, the worker would be required to use a half-mask
respirator for the entire time he or she operates the stationary saw
and a tight-fitting, full-face PAPR for the tuckpointing work,
regardless of how long each task is performed.
The following paragraphs describe the engineering controls, work
practices and respirators selected for each of the operations listed in
Table 1. In addition, the Agency describes the information that it has
relied upon to develop the control strategies.
For most control strategies in the table, OSHA is proposing to
require additional specifications to ensure that the strategies are
effective. The most frequently required additional specifications are:
Changing water frequently when using water delivery
systems, to avoid silt build-up in the water and prevent wet slurry
from accumulating and drying. This prevents silica from becoming
airborne when the water becomes aerosolized by the rotation of
equipment or when the water dries and leaves residual respirable
silica-containing dust.
Operating equipment such that no visible dust is emitted
from the process. Visible dust may be an indication that the controls
are not operating effectively. The absence of visible dust does not
necessarily indicate that workers are protected, but visible dust is a
clear indication of a potential problem.
Providing sufficient ventilation to prevent build-up of
visible airborne dust when working indoors or in enclosed spaces.
Stagnant air in an enclosed environment may increase worker exposures.
Ensuring that saw blades and abrasive discs are not
excessively worn. Excessive wear tends to increase respirable silica
emissions and worker exposures.
Using dust collectors according to manufacturers'
specifications. Manufacturer specifications are often based on
operation-specific designs.
Use of stationary masonry saws. For workers operating stationary
masonry saws, OSHA is proposing to require that the saws be equipped
with an integrated water delivery system that is operated and
maintained to minimize dust emissions. The exposure profile created for
this operation shows that cutting with wet methods offers a clear
reduction to exposures, as opposed to dry cutting with no controls or
with a mix of administrative or other engineering controls. The Agency
obtained 12 samples for workers dry cutting with no engineering
controls, 9 samples for workers dry cutting with a mix of controls, and
7 samples for workers operating the saws with water at the point of
operation. The mean, median, and range values were all lower for
workers using wet methods:
Median of 33 [mu]g/m\3\ (a 34-percent reduction from dry
cutting and 63-percent reduction from dry cutting with some controls).
Mean of 42 [mu]g/m\3\ (an 88-percent reduction from dry
cutting and 80-percent reduction from dry cutting with some controls).
A maximum value of 93 [mu]g/m\3\, as opposed to a maximum
value of 2,005 [mu]g/m\3\ for dry cutting, and 824 [mu]g/m\3\ for dry
cutting with some controls.
The Agency concludes, based on this information and the analysis
discussed in the exposure profile for this operation (PEA, Chapter 4),
that the water delivery system specified in Table 1 consistently
reduces worker exposures to or below the proposed PEL when the saws are
used for four hours or less. As a result, respiratory protection is not
included in the control strategy for these operations. OSHA believes
that, even when workers operate stationary masonry saws for eight
hours, wet methods will reduce 8-hour exposures to or below the
proposed PEL most of time, as described in Chapter 4 of the PEA.
However, the maximum TWA value measured for a stationary masonry saw
operator is 93 [mu]g/m\3\, equivalent to a 4-hr exposure of 47 [mu]g/
m\3\ (see Chapter 4 of the PEA). Thus, when workers perform this
operation for more than four hours, silica exposures may occasionally
exceed the PEL. Because, in the absence of an exposure assessment,
employers will not be able to confirm that exposures are below the PEL,
or identify circumstances in which exposures may exceed the PEL, the
proposed rule requires that employers provide half-mask respirators to
workers who use stationary masonry saws for more than four hours.
Use of hand-operated grinders. The table provides employers with
two different control strategies.
Option 1: Use water-fed grinders that continuously feed water to
the cutting surface, operated and maintained to minimize dust
emissions. For operations lasting less than four hours, OSHA is
proposing that respirators will not be required. For operations lasting
four hours or more, OSHA is proposing the use of half-mask respirators
to ensure workers are protected.
For its technological feasibility analysis, OSHA did not obtain any
sample results where wet grinding occurred. Information available to
the Agency suggests that overexposures still occur when using wet
methods and that there are additional challenges such as limited
applications. OSHA has decided to include this control strategy based
on the use of water systems on similar tools used in the cut stone and
stone products manufacturing industry that have shown a reduction of
exposures to well below 100 [micro]g/m\3\ (OSHA 3362-05). The Agency
believes that similar reductions can be achieved for grinding
operations because the amount of respirable dust produced in these
operations is comparable. Based on this inference, OSHA believes that
wet methods alone will provide sufficient protection for shifts lasting
four hours or less, and is proposing to require the use of half-mask
respirators with an APF of 10 for shifts lasting more than four hours.
The Agency requests comments and additional information regarding
wet grinding and the adequacy of this control strategy.
Option 2: Use hand-operated grinders with commercially available
shrouds and dust collection systems operated and maintained to minimize
dust emission. The dust collector must be equipped with a HEPA filter
and must operate at 25 cubic feet per minute (cfm) or greater airflow
per inch of blade diameter. OSHA is proposing to require the use of
half-mask respirators at all times, for outdoor and indoor operations
alike, to ensure workers are protected.
OSHA's exposure profile for this operation contains 13 samples
associated with the use of LEV. Two of these samples are associated
with outdoor activities (40 [micro]g/m\3\ and 53 [micro]g/m\3\), and 11
samples are associated with indoor work (a range of 12 [micro]g/m\3\ to
208 [micro]g/m\3\). Overall, exposure samples show that outdoor
exposures are lower than indoor exposures. The mean, median, and range
values for these operations are:
Median of 47 [mu]g/m\3\ for outdoor operations with LEV,
and 107 [mu]g/m\3\ for indoor operations with LEV.
Mean of 46 [mu]g/m\3\ for outdoor operations with LEV, and
96 [mu]g/m\3\ for indoor operations with LEV.
A maximum value of 53 [mu]g/m\3\ for outdoor operations
with LEV, and 208 [mu]g/m\3\ for indoor operations with LEV.
These values suggest that workers would sometimes achieve levels
below the proposed PEL with LEV. However, the Agency recognizes that
elevated exposures occur even with the use of LEV in these operations
based on the fact that 8 out of 13 samples collected exceed the
proposed PEL, with 6 samples ranging from 100 [mu]g/m\3\ to 250 [mu]g/
m\3\. Based on this information, OSHA is proposing that employers apply
the engineering control specified and equip workers with half-mask
respirators at all times. It is important to note that OSHA has
preliminarily concluded that the LEV control outlined in the table will
not reduce and maintain exposures to the proposed PEL for all workers.
However, these controls will reduce exposures within the APF of 10
offered by half-mask respirators. The Agency seeks additional
information to confirm that the control strategy (including the use of
half-mask respirators) listed in the table will reduce workers'
exposure to or below the PEL.
Tuckpointing. OSHA is proposing to require employers to equip
grinding tools with commercially available shrouds and dust collection
systems, operated and maintained to minimize dust emissions. The
grinder must be operated flush against the working surface, with
grinding operations performed against the natural rotation of the blade
(i.e., mortar debris must be directed into the exhaust). Employers
would be required to use vacuums that provide at least 80 cubic feet
per minute (cfm) to 85 cfm airflow through the shroud and include
filters that are at least 99 percent efficient.
Recent dust control efforts for tuckpointing have focused on using
a dust collection hood, or shroud, which encloses most of the grinding
blade. It is used with a vacuum cleaner system that exhausts air from
these hood systems and collects dust and debris. These shroud and
vacuum combinations capture substantial amounts of debris, but air
monitoring results summarized in OSHA's exposure profile for this
operation show that even with this control in place, silica exposures
often continue to exceed 100 [mu]g/m\3\, with many of the results
exceeding 250 [mu]g/m\3\.
The highest exposure obtained for outdoor work with LEV (6,196
[micro]g/m\3\), and many other exposures, suggest that there are
circumstances in which the protection factor offered by a PAPR will be
needed to reduce worker exposure to below 50 [micro]g/m\3\. OSHA is
aware that some exposures may be effectively controlled with the LEV
system and a respirator with an APF of 10, but is proposing to require
the use of the LEV system with respirators that provide an APF of 50 to
ensure that the control strategy protects those workers with extremely
elevated exposures. Based on this information, OSHA estimates that a
substantial percentage of the worker population will need respiratory
protection in the form of a powered air-purifying respirator (PAPR)
with a loose-fitting helmet or a negative-pressure full-facepiece
respirator regardless of task duration.
Furthermore, OSHA is stressing the importance of sufficient air
circulation in enclosed or indoor environments to maximize the effect
of the control strategy outlined. Elevated results are reported for
tuckpointers in operations performed in areas with limited air
circulation (including indoors). As such, the Agency is proposing to
require employers to provide for ventilation to prevent the
accumulation of airborne dust during operations performed in enclosed
spaces, in addition to requiring equipment to be operated so that no
visible dust is emitted from the process.
Use of jackhammers and other impact drillers. The table provides
employers with two different control strategies.
Option 1: Apply a continuous stream or spray of water at the point
of operation.
Results in OSHA's exposure profile show that the wet methods
attempted in the five samples obtained were not effective at all in
reducing exposures; in fact, the statistical values are higher than
those under baseline conditions. Based on the best available
information, OSHA believes that no single wet method was applied
effectively and consistently throughout these operations, and the data
obtained for wet methods is reflective of that inconsistency (ERG-C,
2008; PEA, Chapter 4). The three highest results for the samples
corresponding to wet methods show respirable dust levels higher than
the mean respirable dust value for comparable uncontrolled operations,
indicating that the wet method control was not applied effectively, as
it was not reducing total respirable dust levels.
Conversely, however, OSHA has obtained information from individual
employers, NIOSH, and an informal consortium of New Jersey
organizations interested in controlling silica during road construction
activities that have all tested wet dust suppression methods with
chipping and breaking equipment. The results of these tests indicate
that wet dust suppression is effective in reducing respirable
crystalline silica exposures.
The Agency obtained a reading for a jackhammer operator breaking
concrete outdoors, where a continuous stream of water was directed at
the breaking point. When compared with the median value in the exposure
profile for outdoor and uncontrolled operations, the result represents
a 77-percent exposure reduction in respirable quartz (OSHA SEP
Inspection Report 106719750).
NIOSH provided similar findings when it completed several studies
evaluating water spray devices to suppress dust created while workers
used chipping and breaking equipment. Compared with concentrations
during uncontrolled pavement breaking, respirable dust results were
between 72 and 90 percent lower when the water spray was used (NIOSH
EPHB-282-11a, 2003). A follow-up NIOSH study reported a similar 77-
percent reduction in silica concentration during 60-minute trials with
a solid cone nozzle producing water mist (NIOSH EPHB-282-11c-2, 2004).
Two other findings also show that water spray systems are effective
in reducing respirable dust concentrations. Williams and Sam (1999)
evaluated a shop-built water spray system attached to a hand-held
pneumatic chipper used by a worker removing hardened concrete from
inside a mixing truck drum. Although this task is not typically
performed by construction workers, it represents a worst-case
environment (in a confined space or indoors) for construction concrete
chipping and breaking jobs. Water spray decreased respirable dust by
about 70 percent in the worker's breathing zone, again showing that a
water spray system offers substantial reduction in silica-containing
dust generated.
Additionally, the New Jersey Laborers Health and Safety Fund,
NIOSH, and the New Jersey Department of Health and Senior Services have
collaborated in publishing simple instructions for developing spray
equipment for jackhammers. A design tested in New Jersey involving a
double water spray--one on each side of the breaker blade--reduced peak
dust concentrations by approximately 90 percent compared with the peak
concentration measured for uncontrolled breaking (Hoffer, 2007; NIOSH
2008-127, 2008; NJDHSS, no date).
OSHA believes that, even when workers perform impact drilling for
eight hours, wet methods will reduce TWA exposures to or below the
proposed PEL most of time, as described in Chapter 4 of the PEA.
However, when workers perform this operation for more than four hours,
silica exposures may occasionally exceed the PEL. Because, in the
absence of an exposure assessment, employers will not be able to
confirm that exposures are below the PEL, or identify circumstances in
which exposures may exceed the PEL, the proposed rule requires that
employers provide respiratory protection to workers who perform impact
drilling for more than four hours.
OSHA notes that applying the lowest exposure reduction of the
values reported in the studies would reduce the highest range of
exposures to within an APF of 10 provided by a half-mask respirator
and, thus, consistently and adequately protect workers for a full
shift. Additionally, for impact drilling operations lasting four hours
or less, OSHA is proposing to allow workers to use water delivery
systems without the use of respiratory protection, as the Agency
believes that this dust suppression method alone will provide
consistent, sufficient protection. OSHA is requesting comments and
additional information that address the appropriateness of this control
strategy.
It is important to mention that the highest exposures in the
profile were obtained during indoor work, with a maximum value of 3,059
[mu]g/m\3\. OSHA believes that these elevated results are in part due
to poor air circulation in enclosed environments. The Agency believes
that it is particularly important to ensure adequate air circulation
during indoor work, so that airborne dust does not accumulate and
contribute to higher exposures. As such, the proposed Table 1 includes
a specification that directs employers to provide adequate ventilation
during indoor work so as to prevent build-up of visible airborne dust.
Option 2: Use tool-mounted shroud and HEPA-filtered dust collection
system, operated and maintained to minimize dust emissions.
Based on available information, LEV systems are also able to
effectively reduce respirable airborne silica dust. NIOSH tested two
tool-mounted LEV shrouds during work with chipping hammers intended for
chipping vertical concrete surfaces. Comparing multiple
short-term samples, NIOSH found that the shrouds reduced respirable
dust by 48 to 60 percent (Echt et al., 2003; NIOSH EPHB 282-11a, 2003).
In a separate evaluation, NIOSH showed that this type of LEV system
controls dust equally well for smaller chipping equipment. Mean silica
levels decreased 69 percent when the workers used a tool-mounted LEV
shroud in enclosed spaces (NIOSH EPHB 247-19, 2001). In this study, a
combination of LEV and general exhaust ventilation provided additional
dust control, resulting in a 78 percent decrease in silica readings.
This finding further supports OSHA's proposal to ensure that additional
ventilation is provided during indoor work to prevent the accumulation
of airborne dust.
OSHA believes that, even when workers perform impact drilling for
eight hours, these controls will reduce TWA exposures to or below the
proposed PEL most of time, as described in Chapter 4 of the PEA.
However, when workers perform this operation for more than four hours,
silica exposures may occasionally exceed the PEL. Because, in the
absence of an exposure assessment, employers will not be able to
confirm that exposures are below the PEL, or identify circumstances in
which exposures may exceed the PEL, the proposed rule requires that
employers provide respiratory protection to workers who perform impact
drilling for more than four hours. OSHA believes that that LEV systems
will reduce the highest range of airborne respirable silica
concentrations (in the exposure profile) to within an APF provided by a
half-mask respirator for operations lasting a full shift. For
operations lasting four hours or less, OSHA is proposing to allow
workers to use the shroud and HEPA vacuum system without respirators,
as the Agency believes that this control alone will provide consistent,
sufficient protection. The highest exposure values were obtained during
indoor work, and the Agency is proposing that employers provide
appropriate air circulation in order to maximize the effectiveness of
the proposed control strategy.
Use of rotary hammers or drills (except overhead use). Table 1
requires that drills be equipped with a hood or cowl and a HEPA-
filtered dust collector, operated and maintained to minimize dust
emissions. The proposed control strategy also directs employers to
eliminate blowing or dry sweeping drilling debris from working
surfaces.
Of the 14 respirable quartz readings summarized in the exposure
profile for this operation, seven represent hole drilling indoors under
uncontrolled conditions. The highest reading obtained for workers in
this job category, 286 [mu]g/m\3\, was recorded for a worker drilling
holes with a \3/4\-inch bit in the floor of a concrete parking garage
where air circulation was poor (Lofgren, 1993). The other seven
results, most of which were collected during outdoor drilling of brick
and rock, are also spread over a wide range but tend to be lower than
(less than half) the indoor values, with a maximum of 130 [mu]g/m\3\
(NIOSH HETA-2003-0275-2926).
Shepherd et al. (2009) found that compared with uncontrolled
drilling, using dust collection cowls connected to portable vacuums
reduced silica exposures by 91 to 98 percent. The researchers tested
four commercially available combinations of two cowls and two vacuums
indoors. Although investigators note that results might vary for
different drill types and drill bit sizes, OSHA estimates that the
proposed control strategy will consistently maintain exposures below
the proposed PEL even during periods of intense drilling. OSHA is
proposing that employers ensure that dust collectors are used according
to manufacturer's specifications in order to maximize dust reduction,
and that the vacuums used are appropriate for the nature of the task to
provide the adequate suction rate.
Based on the percent reductions documented in the Shepherd study,
using a drill equipped with a hood or cowl and a HEPA-filtered dust
collector reduces the highest exposure reading in the profile to levels
below the proposed PEL. As such, OSHA anticipates that this control
strategy alone will reduce or maintain exposures below 50 [mu]g/m\3\
for workers using rotary hammers or drills for durations up to 8 hours
(excluding overhead work).
Hallin (1983) indicates a greater potential for overexposure during
overhead drilling. A test run reported that drilling for 120 minutes
into a concrete ceiling with a percussion drill and a hammer drill gave
respirable quartz concentrations of 1,740 [mu]g/m\3\ and 720 [mu]g/
m\3\, respectively. The percussion drill was later fitted with a dust
collector, and a 180-minute test run produced a value of 80 [mu]g/m\3\.
This type of drilling was not addressed in the Shepherd report;
therefore, OSHA cannot confirm that using the cowl and dust collector
would sufficiently protect workers. The Agency has no additional
information that would indicate that exposures resulting from overhead
work might be consistently reduced below the proposed PEL. Based on
these factors, OSHA is proposing to exclude this particular task from
Table 1. Furthermore, the Agency concurs with the recommendation made
by Hallin (1983) that overhead drilling is ergonomically stressful and
should not be performed consistently for a full shift.
Use of vehicle-mounted earth-drilling rigs for rock and concrete.
Although the equipment used for each type of drilling varies, OSHA has
addressed workers using drilling rigs of all types for rock, earth, and
concrete together in the same section of the technological feasibility
analysis. This is because the worker activities have much in common and
the general methods of silica control are also similar. Specifically,
these workers control the vehicle-mounted or rig-based drills from more
than an arm's length from the drill bit(s). They also perform certain
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.
When drilling rock, workers typically use rigs that are vertically
oriented and equipped to produce a deep hole through the addition of
bit extensions. This operation generally involves the drilling of one
hole for an extended period of time, with minimal interruption. In
contrast, when drilling concrete, workers often use rigs that consist
of an array of one or many drills fixed to the maneuverable arm of a
construction vehicle or purpose-built mobile machine, which permits the
operator to produce a series of precisely spaced mid-size holes. This
process requires operators to frequently start and stop the drilling
process.
Based on these differences, OSHA is proposing to require separate
additional specifications for rock drilling and concrete drilling, with
both types of drilling using LEV at the point of operation and water to
suppress dust from the dust collector exhaust. The Agency estimates
that these control strategies will protect workers from overexposures,
as consistent use of dust extraction shrouds or hoods reduces worker
exposures at both rock and concrete drilling sites. The control
strategies for rock drilling and concrete drilling are discussed below.
OHSA recognizes that enclosed cabs are available for concrete and
rock drilling rigs, and operators who work in enclosed cabs will
experience exposure reductions (ERG-C, 2008). OSHA is proposing that
respirators will not be required for these operators, regardless of
length of shift. Although cabs benefit operators while in the cab, they
do not affect workers' exposure during positioning or hole-tending
activities. To effectively control exposures of all
workers involved in the operation, employers must apply the engineering
controls outlined in Table 1 to manage exposure sources.
In order for the cabs to work optimally, OSHA is proposing that
cabs have the following characteristics: (1) Air conditioning and
positive pressure is maintained at all times, (2) incoming air is
filtered through a pre-filter and a HEPA filter, (3) the cab interior
is maintained as free as practicable from settled dust, and (4) door
seals and closing mechanisms are working properly. 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.
OSHA believes that the cab specifications outlined will promote proper
air filtration and cab integrity. Rock drilling. The control strategy
for this operation specifies the use of a dust collection system around
the drill bits as well as a water spray to wet the exhaust, operated
and maintained to minimize dust emissions. Respiratory protection will
not be required unless work is being performed under the shroud at the
point of operation.
Modern shroud designs, which are commercially available, have been
shown to consistently achieve respirable dust reductions (Reed et al.,
2008; Drilling Rig Manufacturer A, 2009). Moreover, NIOSH has
quantified reductions in dust emissions associated with LEV used with a
dowel drilling machine. For these concrete drilling rigs, NIOSH found
that close-capture dust collection hoods reduced respirable dust
concentrations by 89 percent compared with drilling without the hoods.
OSHA believes that similar reductions are achievable on rock drilling
machines equipped with dust collection systems, as the quantity of
airborne dust generated is comparable for both types of drilling.
Additionally, OSHA believes it is important for employers to use
dust collectors in accordance with manufacturer specifications. NIOSH
has shown that dust collector efficiency is improved when workers use
an appropriate suction rate, maintain the shroud in good condition, and
keep the shroud positioned to fully enclose the bit as it enters the
hole. The Agency is also proposing to include a visible dust
specification, which employers can use as a tool to identify potential
problems with controls.
Due to the nature of rock drilling, workers often have to work
under the shroud to clear tailings and dust from in or around the hole.
When this work is performed, workers do not receive the same amount of
protection from the control system, and they have to work closer to the
point of dust generation. As such, OSHA believes that workers will
experience higher exposures. In order to ensure that workers are
adequately protected, OSHA is proposing that employers ensure that
workers use half-mask respirators when working under shrouds at the
point of operation. The Agency is seeking comments and additional
information that address the appropriateness of this specification.
The Agency is also proposing to require employers to use a water
delivery system to suppress dust emanating from the dust collector
exhaust. Research shows that in the vicinity of a rock-drilling rig,
dust collector dumping operations are the largest single contributor of
airborne respirable particulates. Maksimovic and Page has shown that in
rock-drilling rigs, this source contributed 38 percent of the
respirable dust emissions, while the deck shroud contributed 24 percent
(reported in Reed et al., 2008). NIOSH reports that modifications
(involving water delivery systems) to dust collector discharge areas
have reduced exposures from this source by 63 to 89 percent, which
means that overall airborne particles can be reduced by at least 24
percent.
For example, a result of 54 [micro]g/m\3\ was obtained for a worker
who operated a rig equipped with a vacuum dust collection system. This
overexposure resulted from the lack of dust suppression while dust was
being dumped from the second filter of the collector--not from the
actual drilling operation. Information from the inspection shows that
the collector had two filters, and water was used to suppress dust from
dumping operations from the first filter only (OSHA SEP Inspection
Report 300340908). OSHA believes that adding a water delivery system to
suppress dust from the discharge at the second filter would have
resulted in a lower exposure. This result indicates that the control
strategy outlined, when applied effectively, will adequately protect
workers during a full work shift without requiring respirators.
Concrete drilling. The control strategy for this operation
specifies the use of a dust collection system around the drill bits as
well as a low-flow water spray to wet the exhaust, operated and
maintained to minimize dust emissions.
NIOSH has recommended several modifications to typical concrete
drilling rig dust collection equipment (NIOSH EPHB 334-11a, 2008). OSHA
anticipates that these upgrades will help ensure that optimal dust
collection efficiency is maintained over time. As such, the Agency is
proposing to require these additional specifications:
Using smooth ducts and maintaining a duct transport velocity
of 4,000 feet per minute to prevent duct clogging
Providing duct clean-out points to aid in duct maintenance and
prevent clogging, and
Installing pressure gauges across dust collection filters so
the operator can clean or change the filter at an appropriate time
Furthermore, Minnich 2009 demonstrated that a dust plume originated
from the point of operation after a worker activated a drill and LEV
system simultaneously. OSHA believes that the overall collection
efficiency would be improved by activating the exhaust suction prior to
initiating drilling and deactivating it after the drill bit stops
rotating, and is proposing to require that employers operate their LEV
systems in this manner.
Similar to rock drilling, OSHA believes it is important for
employers to use dust collectors in accordance with manufacturer
specifications based on the NIOSH findings described in the rock
drilling section. The Agency is also proposing to include a visible
dust specification for concrete drilling, as it will help employers
identify potential problems with controls.
While the available data do not specifically characterize the
effects of controls for concrete drilling rigs in all circumstances,
the Agency has substantial data on the effectiveness of controls in
rock drilling, and based on the similarities of these operations (refer
to PEA, Chapter 4). OSHA estimates that these controls provide similar
protection in concrete drilling and are able to reduce and maintain
exposures to the proposed PEL most of the time. Implementing the
additional specifications listed in Table 1 will also provide
protection. However, OSHA cannot rule out the possibility that silica
exposures will occasionally exceed the PEL, when workers perform this
operation outside of an enclosed cab for more than four hours. Because,
in the absence of an exposure assessment, employers will not be able to
confirm that exposures are below the PEL, or identify circumstances in
which exposures may exceed the PEL, the proposed rule requires that
employers provide half-mask respirators to workers who perform concrete
drilling outside of an enclosed cab for more than four hours.
OSHA seeks additional data to describe the efficacy of the controls
described above in reducing exposures for workers who operate concrete
drilling rigs. Additionally, the Agency is requesting comments and
additional information regarding the adequacy of the control strategy
described in Table 1.
Use of drivable milling machines. Table 1 proposes that employers
use water-fed systems that deliver water continuously at the cut point
to suppress dust, operated and maintained to minimize dust emissions.
The table also includes a visible dust provision, which helps employers
identify potential problems with the control strategy. The Agency is
proposing that no respiratory protection will be required for shifts
lasting four hours or less, and that half-mask respirators be used for
operations lasting more than four hours.
Some machines are equipped with water delivery systems that are
specifically designed to suppress dust. However, water is more
generally applied to the cutting drum of milling machines to prevent
mechanical overheating. OSHA believes that improved water delivery
systems will help reduce exposures for the worker population that
remains overexposed. For example, a study conducted in the Netherlands
with a novel dust emission suppression system shows the potential
impact of a water-delivery system (combined with an additive) as a
control strategy. Compared with a standard milling machine that uses
cooling water only on the blade, the use of an aerosolized water and
foam dust suppression system reduced the mean exposure for drivers and
tenders by about 95 and 98 percent, respectively (Van Rooij and
Klaasse, 2007). The same study also reported results for the use of
aerosolized water without the additive. Aerosolized water alone
provided a substantial benefit, reducing the mean exposure for drivers
and tenders by about 88 and 84 percent, respectively.
Based on the exposure profile, OSHA anticipates that the vast
majority of workers already experience exposure levels below the
proposed PEL for operations lasting four hours or less. With water
delivery systems designed specifically to suppress dust, the Agency
expects that workers will be consistently protected against respirable
crystalline silica exposures. With this control strategy in place, OSHA
believes that respirators will not be necessary for operations lasting
four hours or less.
OSHA believes that, even when workers operate drivable milling
machines for eight hours, water delivery systems will reduce TWA
exposures to or below the proposed PEL most of time, as described in
Chapter 4 of the PEA. However, OSHA cannot rule out the possibility
that silica exposures will occasionally exceed the PEL under certain
circumstances, when workers operate these machines for more than four
hours. Because, in the absence of an exposure assessment, employers
will not be able to confirm that exposures are below the PEL, or
identify circumstances in which exposures may exceed the PEL, the
proposed rule requires that employers provide respiratory protection to
workers who operate drivable milling machines for more than four hours.
Based on the range of exposures in the exposure profile (see
Chapter 4 of the PEA), OSHA anticipates that properly designed water
delivery systems to suppress dust and half-mask respirators will
provide sufficient protection (the highest exposure measured for any
worker is 340 [mu]g/m\3\, with no dust suppression controls in place).
As such, the Agency believes that using wet methods and half-mask
respirators is a control strategy that consistently protects workers
for operations lasting more than four hours.
Walking behind milling machines. For walk-behind milling machines,
Table 1 provides workers with two options for controlling exposures to
crystalline silica.
The first option directs employers to use water-fed equipment that
continuously feeds water to the cutting surface to suppress dust,
operated and maintained to minimize dust emissions.
The exposure profile for this operation contains six samples, with
the highest exposure being the only one above the proposed PEL. The two
lowest exposures in the profile (both are 12 [mu]g/m\3\) were obtained
for workers that used water-fed machines (ERG-C, 2008), indicating that
the wet method effectively controls silica exposure.
If the highest exposure in the profile is weighted for four hours,
the adjusted exposure is less than the proposed PEL. Thus, OSHA
anticipates that for operations lasting four hours or less, workers
will be consistently protected by wet methods.
OSHA believes that, even when workers operate walk-behind milling
machines for eight hours, water delivery systems will reduce TWA
exposures to or below the proposed PEL most of time, as described in
Chapter 4 of the PEA. However, when workers operate these machines for
more than four hours, silica exposures may occasionally exceed the PEL
under certain circumstances. Because, in the absence of an exposure
assessment, employers will not be able to confirm that exposures are
below the PEL, or identify circumstances in which exposures may exceed
the PEL, the proposed rule requires that employers provide respiratory
protection to workers who operate walk-behind milling machines for more
than four hours. The Agency believes the use of a half-mask respirator
will ensure consistent worker protection.
The second option is to use tools equipped with commercially
available shrouds and dust collection systems, which are operated and
maintained to minimize dust emissions. The dust collector must be
equipped with a HEPA filter and must operate at an adequate airflow to
minimize airborne visible dust. Additionally, the dust collector must
be used in accordance with manufacturer specifications including the
airflow rate.
To date OSHA has not been able to quantify the effectiveness of
currently available LEV in controlling respirable quartz levels
associated with walk-behind milling operations; however, OSHA believes
that evidence from similar construction tasks supports its value for
workers performing milling. OSHA believes that the LEV dust control
option will work at least as effectively for milling machines as for
tuckpointing grinders. Although the tuckpointers using LEV still
experienced a geometric mean result of 60 [mu]g/m\3\, walk-behind
milling machine operators have the advantages of lower uncontrolled
exposure levels, greater distance between the tool and their breathing
zone, and equipment that is self-supporting (the milling drum enclosure
more easily kept sealed against the floor), rather than hand-held.
Therefore, an LEV system with an appropriately sized vacuum will
similarly reduce most walk-behind milling machine operator exposures.
Based on the exposure samples analyzed, OSHA estimates that most
workers already have exposures under the proposed PEL for operations
lasting four hours or less, and is not proposing to require respirator
use.
For operations lasting more than four hours, the Agency believes
that at most the workers will be protected by using LEV alone, as
described Chapter 4 of the PEA. However, the Agency cannot rule out the
possibility that workers who operate these machines for more than four
hours will occasionally receive exposures that exceed the PEL, under
certain circumstances. Because, in the
absence of an exposure assessment, employers will not be able to
confirm that exposures are below the PEL, or identify circumstances in
which exposures may exceed the PEL, the proposed rule requires that
employers provide half-mask respirators to workers who operate drivable
milling machines for more than four hours.
Use of hand-held masonry saws. Table 1 provides employers with two
different control strategies. Along with the engineering controls
listed in Table 1, OSHA is proposing the additional specifications that
will aid employers in using the engineering controls optimally.
Prevent wet slurry from accumulating and drying. The
accumulation and drying of wet slurry can lead to settled dust that is
easily resuspended and can contribute to worker exposures.
Ensure that the equipment is operated such that no visible
dust is emitted from the process. When controls are functioning
properly, visible dust should not be observed. This specification will
help employers identify potential problems with the control strategy.
When working indoors, provide sufficient ventilation to
prevent build-up of visible airborne dust. Proper airflow prevents air
from becoming stagnant and dilutes the levels of respirable crystalline
silica.
Use dust collectors in accordance with manufacturer
specifications. Selecting the correct system and flow rates will
consistently reduce exposure.
Option 1: Employers use a water-fed system that delivers water
continuously at the cut point, operated and maintained to minimize dust
emissions.
The exposure profile for outdoor cutting with wet methods shows
that for shift lasting four hours or less, workers consistently
experience exposure below the proposed PEL. The Agency believes that
wet methods alone will provide protection and is proposing to require
that employers apply the wet method control without the use of
respiratory protection.
OSHA believes that, even when workers operate hand-held masonry
saws outdoors for eight hours, wet methods will reduce TWA exposures to
or below the proposed PEL most of time, as described in Chapter 4 of
the PEA. However, on the basis of the two highest sample results in the
exposure profile (see Chapter 4 of the PEA), the Agency believes that
silica exposures may occasionally exceed the PEL under certain
circumstances, when workers perform these operations outdoors for more
than four hours. Because, in the absence of an exposure assessment,
employers will not be able to confirm that exposures are below the PEL,
or identify circumstances in which exposures may exceed the PEL, the
proposed rule requires that employers provide half-mask respirators to
workers who operate hand-held masonry saws outdoors for more than four
hours.
Similarly, the highest readings in the exposure profile for
operations using wet methods indoors suggest that silica exposures may
sometimes exceed the PEL even for workers who perform these activities
for less than four hours. Therefore, the Agency is proposing to require
the use of a half-mask respirator with an APF of 10 for workers who
operate hand-held masonry saws indoors or within a partially sheltered
area, regardless of task duration.
Option 2: Use a saw equipped with a local exhaust dust collection
system, operated and maintained to minimize dust emissions.
While the exposure profile does not contain any samples for work
involving hand-held masonry saws conducted with LEV in place, several
studies have shown the general effectiveness of LEV to reduce silica
concentrations. Meeker et al. (2009) shows that LEV can reduce
respirable silica exposures to levels near 100 [mu]g/m\3\ during short-
term periods of active cutting outdoors. Since most workers cut
intermittently even during times of active cutting (e.g., 10 or 20
seconds using the saw followed by a longer period--up to several
minutes--of measuring and moving materials or equipment), 8-hour TWA
values are likely to be considerably lower (Flanagan et al., 2001).
However, OSHA has not been able to confirm that LEV methods offer the
same degree of exposure reduction to workers currently experiencing
more modest, but still elevated, exposures.
Thus, the Agency cannot rule out the possibility that silica
exposures will sometimes exceed the PEL, even when workers perform
these operations for less than four hours. Because, in the absence of
an exposure assessment, employers will not be able to confirm that
exposures are below the PEL, or identify circumstances in which
exposures may exceed the PEL, the proposed rule requires that employers
provide half-mask respirators to workers who use LEV to control
exposures while operating hand-held masonry saws outdoors.
While OSHA does not have exposure data to specifically describe
indoor operations using LEV controls, Thorpe et al. (1999) and Meeker
et al. (2009) reported exposure reductions by 88 to 93 percent for
outdoor operation. OSHA believes that these exposure reductions would
be similar in indoor operations because there is no added general
ventilation in these environments such as natural air circulation
outdoors and airborne dust tends to become more stagnant indoors. Given
the very high uncontrolled exposures documented in the Chapter 4 of the
PEA, even the projected exposure reduction from LEV does not rule out
the possibility that exposures above 500 [mu]g/m\3\ will occasionally
occur under certain circumstances. Because, in the absence of an
exposure assessment, employers will not be able to confirm that
exposures are below the PEL, or identify circumstances in which
exposures may exceed the PEL, the proposed rule requires that employers
provide full face-piece respirators to workers who operate hand-held
masonry saws indoors or in partially enclosed areas, regardless of task
duration.
Use of portable walk-behind or drivable masonry saws. Table 1
directs employers to use a water-fed system that delivers water
continuously at the cut point, operated and maintained to minimize dust
emissions with the following specifications:
Prevent wet slurry from accumulating and drying. The
accumulation and drying of wet slurry can lead to settled dust that is
easily resuspended and can contribute to worker exposures.
Ensure that the equipment is operated such that no visible
dust is emitted from the process. When controls are functioning
properly, visible dust should not be observed. This specification will
help employers identify potential problems with the control strategy.
When working indoors, provide sufficient ventilation to
prevent build-up of visible airborne dust. Proper airflow prevents air
from becoming stagnant and dilutes the levels of respirable crystalline
silica.
The exposure profile for this operation shows that of the 12
respirable silica results associated with wet-cutting concrete outdoors
using walk-behind saws, only 1 measurement exceeded the proposed PEL,
while 8 were less than the LOD. These results suggest that for outdoor
operations, water-fed walk-behind saws provide adequate protection for
workers.
Based on this information, OSHA believes that by using the wet
method controls as specified, workers will be provided with consistent,
adequate protection and is proposing to not require the use of a
respirator when working outdoors.
Flanagan et al. (2001) reported higher 8-hour TWA respirable silica
levels for operators and their assistants who used water-fed walk-
behind saws indoors for most of their shift (the worst-case conditions
resulted in four 8-hour TWA values between 130 [mu]g/m\3\ and 710
[mu]g/m\3\). The author noted that factors such as inadequate
ventilation or poor wet vacuum capture efficiency contributed to the
higher indoor respirable silica levels.
By applying the additional specifications and engineering controls
outlined in Table 1, OSHA believes that indoor exposures will be
reduced to levels where respiratory protection with an APF of 10 will
provide adequate protection. OSHA is proposing to require the use of a
half-mask respirator for tasks of all duration when working indoors or
in partially shielded areas.
Rock crushing. Table 1 provides employers with two control
strategies to protect employees not working in enclosed cabs. Both
options (described below) require the use of half-mask respirators
regardless of task duration.
For equipment operators working within an enclosed cab, OSHA is
proposing that cabs have the following characteristics: (1) air
conditioning and positive pressure is maintained at all times, (2)
incoming air is filtered through a pre-filter and a HEPA filter, (3)
the cab is maintained as free as practicable from settled dust, and (4)
door seals and closing mechanisms are working properly. 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. OSHA believes that the cab specifications outlined
will promote proper air filtration and cab integrity. OSHA is proposing
that operators who work in enclosed cabs meeting these specifications
will not be required to wear respirators.
OSHA is also proposing an additional specification, which requires
that dust control equipment be operated such that no visible dust is
emitted from the process. When controls are functioning properly
visible dust should not be observed, and this specification will help
employers identify potential problems with the control strategy.
Option 1: Use wet methods or dust suppressants.
Based on available information, OSHA believes that water or other
dust suppression is used during rock crushing activities but that the
application may be either inconsistent or inefficient (ERG-C, 2008).
However, the Agency has obtained other information that shows that dust
suppression systems have been effective in reducing exposures. For
example, a silica result of 54 [mu]g/m\3\ was obtained for the operator
of a stationary crusher at a concrete recycling facility using fine
mist water spray (ERG-concr-crush-A, 2001). It is important to note
that this machine operator spent much of the shift in a poorly sealed
booth directly over the crusher, but left the booth frequently to tend
to other activities. Due to the lack of information regarding the
workshift, OSHA cannot asses the full extent of the impact that water
dust control had on the worker exposure.
Gottesfeld et al. (2008) summarized a study conducted in India at
several rock crushing facilities. The study demonstrates that after
water spray installation, 70 percent of the breathing zone and area
results were less than 50 [mu]g/m\3\, and just one result exceeded 250
[mu]g/m\3\. In contrast, before the water mist system was added, all
results exceeded 50 [mu]g/m\3\, and 60 percent were greater than 250
[mu]g/m\3\, a condition similar to those in OSHA's exposure profile for
workers associated with rock crushing machines. OSHA acknowledges that
worksites may different in the United States, but believes that similar
exposure reductions can be achieved with rock crushers in the U.S.
Wet dust suppression options that can offer a substantial benefit
include water expanded into foam, steam, compressed water fog, and
wetting agents (surfactants added to water to reduce surface tension)
(ERG-C, 2008). OSHA believes that when used properly and consistently,
these dust suppressants could reduce silica concentrations at least as
effectively as and more consistently than directional water mist spray
alone, achieving exposure reductions of 70- to 90-percent.
OSHA acknowledges that available data is inadequate to indicate
whether water mist or other dust suppressants alone are sufficient to
reduce these workers' silica exposures below 50 [mu]g/m\3\. However,
based on the best available information, OSHA estimates that by
consistently using properly directed water mist spray (or other dust
suppression methods), the vast majority of rock crushers can achieve
consistent results in a range that is compatible with use of a half-
mask respirator with an APF of 10.
Option 2: Use local exhaust ventilation systems at feed hoppers and
along conveyor belts, operated and maintained to minimize dust
emissions.
Information available to OSHA indicates that LEV is capable of
reducing silica concentrations. For example, Ellis Drewitt (1997)
reported a reading of 300 [mu]g/m\3\ for a worker in Australia using a
dust extraction system (when compared to the uncontrolled mean of 798
[mu]g/m\3\ in the exposure profile).
Another international report from Iran describes a site where
workers used rock crushers with LEV (Bahrami et al., 2008). The report
demonstrated that LEV systems were associated with a marked decrease in
respirable dust. Among 20 personal silica samples for process workers
and hopper-filling workers associated with rock crushers after LEV was
installed, the mean PBZ respirable quartz results were 190 [mu]g/m\3\
to 400 [mu]g/m\3\, respectively. It is important to note that the bulk
samples of this rock contained 85 to 97 percent quartz. The Agency
believes that these levels would likely have been lower if the rock had
not been nearly pure silica. If the respirable dust sample had
contained the more typical 12 percent silica on the filter, OSHA
estimates that the corresponding airborne silica concentrations would
have been 92 [mu]g/m\3\ to 178 [mu]g/m\3\. The Agency recognizes that
exposures may be higher than this estimate, but does not possess
additional information that more clearly characterizes worker exposures
with the implementation of LEV controls.
As such, OSHA believes that a fully functioning LEV system can
control exposures for most workers to within the protection factor
offered by a half-mask respirator. OSHA is aware of the difficulties
present in applying LEV to rock crushing operations, and is requesting
additional information addressing the appropriateness and
practicability of this control strategy.
Drywall finishing (with silica-containing material). The main
source of exposure for drywall finishing operations occurs when dust is
generated while sanding dried, silica-containing joint compound (ERG-C,
2008). Fourteen of the 15 samples collected for the exposure profile
for this operation show exposures below the proposed PEL, with 7
samples below the LOD. The one overexposure, 72 [mu]g/m\3\, was
obtained for a worker performing overhead sanding (NIOSH HETA 94-0078-
2660, 1997). Table 1 provides employers with two control strategies;
neither option requires the use of respirators.
Option 1: Use pole sander or hand sander equipped with a dust
collection system, operated and maintained to minimize dust emissions.
Use dust collectors according to manufacturer specifications.
NIOSH tested the effectiveness of five off-the-shelf ventilated
sanding systems during drywall finishing: three designed to control
dust during pole sanding, and two to control dust during hand sanding.
Total dust area sample results revealed that all five systems were
effective for reducing total airborne dust by at least 80 percent,
ranging up to 97 percent (NIOSH ECTB-208-11a, 1995). This effectiveness
was confirmed in a study by Young-Corbett and Nussbaum (2009a), which
found that using a ventilated sander during drywall sanding reduced
respirable dust in the PBZ by 88 percent compared with a block sander
(no controls).
Silica exposures were not measured explicitly in these studies, but
OSHA estimates that based on the reported total dust reductions, even
the highest exposure in the profile can be reduced to levels below the
proposed PEL. The Agency reasonably estimates that this control
strategy will adequately protect workers without the need for
respirators.
Although ventilated sanders are the most effective exposure control
option for silica-containing joint compound, and they offer indirect
benefits to workers and managers (NIOSH Appl. Occup. Environ. Hyg. 15,
2000), there are many perceived barriers to their adoption in the
workplace (NIOSH ECTB-208-11a, 1995; Young-Corbett and Nussbaum,
2009b). Hence, Option 2 is provided to employers as a way to comply
with paragraph (f)(1) of the proposed rule.
Option 2: Use wet methods to smooth or sand the drywall seam.
Young-Corbett and Nussbaum (2009a) found that a wet sponge sander
reduces respirable dust in the PBZ by 60 percent compared with a block
sander (no controls). Other wet methods include wiping a clean, damp
sponge over the still-damp joint compound to smooth the seam and
rinsing the sponge in a bucket of water as it becomes loaded with
compound, or wetting dried joint compound with a spray bottle and
sanding with sandpaper (NIOSH ECTB-208-11a, 1995).
Again, silica exposures were not explicitly measured in the Young-
Corbett and Nussbaum study. Based on the reported respirable dust
reduction, however, OSHA estimates that even the highest exposure in
the profile can be reduced and maintained below the proposed PEL. As
such, the Agency believes that using wet methods will offer adequate
protection without requiring respirators.
Use of heavy equipment during earthmoving. The exposure profile for
this operation ranges from 11 [micro]g/m\3\ to 170 [micro]g/m\3\, with
about 13 percent of the values exceeding the proposed PEL. Table 1
provides for the option of operating equipment from enclosed cabs to
control exposures. It specifies that workers operate equipment from
within enclosed cabs that have the following characteristics:
Air conditioning with positive pressure maintained at all
times;
Incoming air filtered through a pre-filter and a HEPA
filter;
Having the cab be as free as practicable from settled
dust; and
Door seals and closing mechanisms that are working
properly.
Based on published research, ERG-C (2008) found that effective
enclosed cabs generally have these four characteristics, and extensive
literature suggests that the exposure reductions can range from 80 to
more than 90 percent in this industry (Rappaport et al., 2003; Pannel
and Grogin, 2000; Cecala et al., 2005; NIOSH 528, 2007).
The exposure profile shows that of the 19 results for which the
status of the cab was established, 17 were for unenclosed cabs. Both of
the operations involving enclosed cabs had exposures of about 12
[micro]g/m\3\, while operations involving several of the unenclosed
cabs were associated with worker exposures greater than 50 [micro]g/
m\3\ and up to 87 [micro]g/m\3\. This information allows OSHA to
determine that operators using enclosed cabs as proposed by this option
will effectively protect workers. Respiratory protection will not be
needed.
Concerning abrasive blasting operations, paragraph (f)(2) of the
general industry/maritime proposed rule and paragraph (f)(3) of the
construction proposed rule direct employers to comply with the
requirements of 29 CFR 1910.94 (Ventilation), and for shipyard
employment 29 CFR 1915.34 (Mechanical Paint Removers) and 29 CFR part
1915, subpart I (Personal protective equipment). These standards apply
to abrasive blasting operations that involve crystalline silica-
containing blasting agents or substrates. Employers should consult
these other standards to ensure that they comply with personal
protective equipment, ventilation, and other operation-specific safety
requirements.
OSHA is aware of current and past efforts of domestic and
international entities to ban silica sand as an abrasive blasting
agent. Given the best available information to date, the Agency does
not believe that banning silica sand is the most appropriate course of
action, as OSHA has concerns about potential harmful exposures to other
substances that the alternatives might introduce in a workplace.
Further toxicity data are necessary before the Agency can reach any
conclusions about the hazards of these substitutes relative to the
hazards of silica. The following paragraphs provide further information
regarding abrasive blasting agents.
The annual use of silica sand for abrasive blasting operations has
decreased from about 1.5 million tons in 1996 to 0.5 million tons in
2007, which roughly represents a 67-percent reduction (Greskevitch and
Symlal, 2009)). 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.
A NIOSH study compared the short-term pulmonary toxicity of several
abrasive blasting agents (NIOSH, Blasting Abrasives: Health Hazard
Comparison, 2001). 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-lung effects.
Hubbs et al. (2005) mention that of the nine alternatives to silica
sand, NIOSH has identified five of them-coal slag, steel grit, specular
hematite, garnet, and crushed glass-for further testing to determine
the relative potential of these agents to induce lung fibrosis in rats
exposed to whole-body inhalation. These abrasive materials were
selected for study based on high production, number of workers exposed,
short-term intratracheal instillation \39\ relative toxicity studies,
and inadequacy of available current data (Hubbs et al., 2005). The
National Toxicology Program is performing long-term (39 weeks), in
vivo, toxicity studies of these abrasive blasting agents.
---------------------------------------------------------------------------
\39\ Intratracheal instillation is an alternative to inhalation
exposure studies. Test material is delivered in a bolus aqueous
solution to the lung through a syringe and ball-tipped needle into
the tracheal (Phalen, 1984).
---------------------------------------------------------------------------
Additionally, another NIOSH study (KTA-Tator, 1998) monitored
exposures to several OSHA-regulated toxic substances that were created
by the use of silica sand and substitute abrasive blasting materials.
The study showed that several substitutes create exposures or potential
exposures to various OSHA-regulated substances. The study showed
exposures or potential exposures to: (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, the Agency 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 to use
substitutes like steel grit and steel shot.
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 1 percent quartz according to its
manufacturer, resulted in a respirable quartz level of 1,580 [micro]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 (NIOSH, 1993b). This
example emphasizes the impact of control methods in specific working
environments. In order to reduce elevated exposures closer to the PEL
in situations like these, employers should examine the full spectrum of
available controls, and how these controls perform in specific working
conditions. Employers may find, for example, that they would have to
provide supplementary respiratory protection to adequately protect
workers that perform abrasive blasting in areas where the accumulation
of dust remains stagnant (e.g. confined spaces) in a worker's personal
breathing zone and overwhelms exhaust ventilation systems. Other
engineering controls the same employer may consider would be wet and/or
automated blasting.
Paragraph (f)(4) of the construction proposed rule, and Paragraph
(f)(3) of the general industry/maritime proposed rule specify that
accumulations of crystalline silica in the work place are to be cleaned
by HEPA-filter vacuums or wet methods. This section also prohibits the
use of compressed air, dry sweeping, and dry brushing to clean clothing
or surfaces contaminated with crystalline silica. These requirements
are being proposed to help regulate the amount of crystalline silica
that becomes airborne, thus providing effective control of worker
exposure. The requirements of paragraph (f)(4) are consistent with
general industry standards for hazardous substances, such as cadmium
and asbestos, which specify that work surfaces be cleaned wherever
possible by vacuuming with a HEPA-filtered vacuum. Much documentation
shows that moving from compressed air blowing and dry sweeping to HEPA-
filtered vacuums and the application of wet methods effectively reduces
worker exposures during cleaning activities (PEA, Chapter 4).
A study of Finnish construction workers compared the respirable
crystalline silica levels during dry sweeping or 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. In the asphalt roofing
industry, NIOSH and OSHA both recommended vacuuming with HEPA-filtered
vacuums as a method to minimize exposure. In five Health Hazard
Evaluations at asphalt roofing manufacturing facilities, NIOSH
recommended vacuuming as opposed to compressed air for cleaning dust
out of equipment (ERG-GI, 2008).
OSHA's technological feasibility analysis points to numerous other
instances where cleaning methods are of particular importance in
reducing worker exposures. In the rock and concrete drilling industry,
OSHA recommends that workers use HEPA-filtered vacuums instead of
compressed air to clean holes in order to reduce-or even eliminate-
substantial exposure during hole-tending activities. In the porcelain
enameling industry, a facility has used a vacuum fitted with a HEPA
filter for all cleaning. To minimize generating airborne dust, workers
avoid dry sweeping and only shovel or scrape materials that are damp
(Porcelain Industries, 2004a; 2004b).
For millers using portable or mobile equipment, Echt et al. (2002)
reported that cleanup is critical for engineering controls to work most
effectively for walk-behind milling machines. The study reported that
airborne dust increased when a scabbler passed over previously milled
areas. It was recommended that debris be cleaned using a HEPA-filtered
vacuum prior to making a second pass over an area. This step enhanced
LEV capability and prevented debris from being re-suspended.
Several facilities have adopted the recommended cleaning methods as
part as an overall effort to reduce exposures. For example, in the
jewelry and dental laboratories industries, additional controls to
reduce exposures below the proposed PEL include LEV, wet methods,
substitution, isolation, work practices, and improved housekeeping such
as the use of a HEPA-filtered vacuum for cleaning operations. These
examples again also show the value of applying a combination of
controls to reduce exposures below the PEL.
Paragraph (f)(5) of the construction proposed rule, and Paragraph
(f)(4) of the general industry/maritime proposed rule specify that the
employer must not rotate workers to different jobs to achieve
compliance with the PEL. OSHA proposes this prohibition because silica
is a carcinogen, and the Agency assumes that any level of exposure to a
carcinogen places a worker at risk. With worker rotation, the
population of exposed workers increases.
This provision is not a general prohibition of worker rotation
wherever workers are exposed to crystalline silica. It is only intended
to restrict its use as a compliance method for the proposed PEL; worker
rotation may be used as deemed appropriate by the employer in
activities such as to provide cross-training and to allow workers to
alternate physically demanding operations with less arduous ones. This
same provision was used for the asbestos (29 CFR 1910.1001 and 29 CFR
1926.1101), hexavalent chromium (29 CR 1910.1026), butadiene (29 CFR
1910.1051), methylene chloride (29 CFR 1910.1052), cadmium (29 CFR
1910.1027 and 29 CFR 1926.1127), and methylenedianiline (29 CFR
1926.60) OSHA standards.
(g) Respiratory Protection
During situations where employee exposure to respirable crystalline
silica is expected to be above the PEL, paragraph (g) requires the
employer to protect employees' health through the use of respirators.
Specifically, in areas where exposures exceed the PEL, respirators are
required during the installation and implementation of engineering and
work practice controls; during work operations where engineering and
work practice controls are not feasible; when all feasible engineering
and work practice controls have been implemented but are not
sufficient to reduce exposure to or below the PEL; and during periods
when any employee is in a regulated area or an area for which an access
control plan indicates that use of respirators is necessary.
These limitations on the required use of respirators 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, discussed above in section (f) (Methods of
compliance), that respirators are inherently less reliable than
engineering and work practice controls in reducing employee exposure to
respirable crystalline silica. OSHA has therefore proposed to allow
reliance on respirators only in certain designated situations.
Proposed paragraph (g)(1)(i) requires the use of respirators in
areas where exposures exceed the PEL during periods when engineering
and/or work practice controls are being installed or implemented. OSHA
recognizes that respirators may be essential to achieve the PEL under
these circumstances. During these times, employees would have to use
respirators for temporary protection until the hierarchy of controls
has been implemented.
OSHA anticipates that engineering controls will be in place by the
start-up date specified in paragraph (k)(2)(ii) of the construction and
the general industry/maritime proposed standards. 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 crystalline silica after the effective date
as defined by paragraph (k)(1). 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, employers must provide
their employees with respiratory protection and require its use.
Proposed paragraph (g)(1)(ii) requires respiratory protection in
areas where exposures exceed the PEL during work operations 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. In situations where
respirators are used as the sole form of protection to achieve
compliance with the PEL, the employer will be required to demonstrate
that engineering and work practice controls are not feasible.
Proposed paragraph (g)(1)(iii) requires the use of respirators for
supplemental protection in circumstances where feasible engineering and
work practice controls alone cannot reduce exposure levels to or below
the PEL. Examples include some tuckpointing, jackhammering, and
abrasive blasting operations. The employer must always install and
implement engineering and work practice controls whenever they are
feasible, even if these controls alone cannot reduce employee exposures
to or below the PEL. Whenever respirators are used as supplemental
protection to achieve compliance with the PEL, the burden is on the
employer to demonstrate that engineering and work practice controls
alone are insufficient to achieve the PEL.
Under proposed paragraph (g)(1)(iv), employers have to provide
respiratory protection during periods when any employee is in a
regulated area. Proposed paragraph (e) in the general industry/maritime
standard and proposed paragraph (e)(2) in the construction standard
would require 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 has included the provision requiring
respirator use in regulated areas in the proposed rule 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 believes
that this provision is necessary and appropriate because it would have
the effect of limiting unnecessary exposures to employees who enter
regulated areas, even if they are only in a regulated area for a short
period of time.
Proposed paragraph (e)(3) gives the employer the option of
developing an access control plan as a means of minimizing exposures to
employees not directly involved in operations that generate respirable
crystalline silica. This written access control plan would serve as an
alternative to setting up regulated areas under paragraph (e)(2). An
access control plan must include procedures for providing and requiring
the use of respiratory protection in areas where exposures can
reasonably be expected to exceed the PEL. Proposed paragraph (g)(1)(v)
of the construction standard requires the use of respiratory protection
when specified by the access control plan.
Proposed paragraph (g)(2) requires the employer to implement a
comprehensive respiratory protection program in accordance with the
Agency's respiratory protection standard (29 CFR 1910.134) whenever
respirators are used to comply with the requirements of the respirable
crystalline silica standard. The respiratory protection program is
designed to ensure that respirators are properly used in the workplace
and are effective in protecting workers. 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 maintaining respirators; 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.
In 2006, OSHA revised the respiratory protection standard (29 CFR
1910.134) to include assigned protection factors (71 FR 50122, Aug. 24,
2006). Assigned protection factor means the workplace level of
respiratory protection that a respirator or class of respirators is
expected to provide to employees when the employer implements a
respiratory protection program under 29 CFR 1910.134. The revised
standard includes a table (Table 1--Assigned Protection Factors) that
employers must use to select sufficiently protective respirators for
employees who may be exposed to respirable crystalline silica.
Proposed paragraph (g)(3) for the construction standard indicates
that, for the operations listed in Table 1 in paragraph (f) of the
construction standard, if the employer fully implements the engineering
controls, work practices, and respiratory protection described in Table
1, the employer shall be considered to be in compliance with the
requirements for selection of respirators in 29 CFR 1910.134 paragraph
(d). Paragraph (d) of 29 CFR 1910.134 requires the employer to evaluate
respiratory hazards in the workplace, identify relevant workplace and
user factors, and base respirator selection on these factors. There is
no need for the employer to complete this process when following Table
1, because Table 1 specifies the type of respirator required for a
particular operation.
(h) Medical Surveillance
In paragraph (h)(1)(i), OSHA proposes to require that each employer
covered by this rule make medical surveillance available at no cost,
and at a reasonable time and place, for all employees who are
occupationally exposed to respirable crystalline silica above the PEL
for 30 or more days per year.
There is a general consensus that medical surveillance is necessary
for employees exposed to respirable crystalline silica. Medical
surveillance for workers exposed to respirable crystalline silica is
included in standards developed by ASTM International (ASTM, 2006;
2009) as well as in guidance or recommendations developed by the
American College of Occupational and Environmental Medicine (ACOEM,
2006), the Building and Construction Trades Department, AFL-CIO (BCTD,
2001), the Industrial Minerals Association/Mine Safety and Health
Administration (IMA/MSHA, 2008), National Industrial Sand Association
(NISA, 2010), and the World Health Organization (WHO, 1996). Although
the specific recommendations made by these organizations differ in
certain respects, they are consistent in indicating that regular
medical examinations are appropriate for workers with substantial
exposures to respirable crystalline silica.
The purposes of medical surveillance for respirable crystalline
silica include the following: to determine, where reasonably possible,
if an individual can be exposed to respirable crystalline silica in his
or her workplace without experiencing adverse health effects; to
identify respirable crystalline silica-related adverse health effects
so that appropriate intervention measures can be taken; and to
determine the employee's fitness to use personal protective equipment
such as respirators. The proposal is consistent with Section 6(b)(7) of
the 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 workers is adversely
affected by exposure to the hazard addressed by the standard. Other
OSHA health standards, such as chromium (VI) (29 CFR 1910.1026),
methylene chloride (29 CFR 1910.1052), and cadmium (29 CFR 1910.1027),
also include medical surveillance requirements.
The proposed standard is intended to encourage participation by
requiring that medical examinations be made available by the employer
without cost to employees (also required by Section 6(b)(7) of the
Act), and at a reasonable time and place. If participation requires
travel away from the worksite, the employer is required to bear the
cost. Employees must be paid for time spent taking medical
examinations, including travel time.
OSHA is proposing that medical surveillance be made available to
employees exposed to respirable crystalline silica above the PEL for 30
or more days a year. In contrast, the ASTM standards (Section 4.6.1)
require medical surveillance for workers with actual or anticipated
exposures to respirable crystalline silica at concentrations that
exceed the occupational exposure limit for 120 or more days a year
(ASTM, 2006; 2009). The OSHA proposal for medical surveillance of
employees exposed to respirable crystalline silica above the PEL for 30
or more days per year is more comprehensive than the ASTM
recommendation. Both the OSHA proposal and the ASTM standard use
exposure above the occupational exposure limit as the trigger for
medical surveillance. However, the OSHA proposal is more protective
than the ASTM standard because it calls for medical surveillance of
workers exposed for a shorter duration of time.
OSHA believes that the proposed cutoffs, based both on exposure
level and on the number of days per year that an employee is exposed to
respirable crystalline silica, are a reasonable and administratively
convenient basis for providing medical surveillance benefits to
respirable crystalline silica-exposed workers. With the exception of
the asbestos standard (29 CFR 1910.1001), which doesn't specify an
action level, medical surveillance in OSHA standards such as chromium
(VI) (29 CFR 1910.1026), methylene chloride (29 CFR 1910.1052), and
cadmium (29 CFR 1910.1027) is triggered by exposure at or above action
level. However, OSHA notes that employees exposed at or below the PEL,
or exposed above the PEL for only a few days in a year, will be at
lower risk of developing respirable crystalline silica-related disease
than employees who are exposed above the PEL for 30 or more days per
year. Medical surveillance triggered by exposures above the PEL covers
employees who face the highest risk of developing disease related to
respirable crystalline silica exposure. OSHA estimates that
approximately 351,000 employees would be exposed above the proposed PEL
for more than 30 days per year, and therefore require medical
surveillance under the proposed standard. For comparison, OSHA
estimates approximately 1,026,000 employees would be exposed above the
proposed action level of 25 ug/[micro]\3\ but at or below the proposed
PEL, a difference of 675,000 employees. The total number of medical
exams required, which takes into account turnover in the work force,
would be similarly affected. For example, in the first year following
promulgation, approximately 454,000 exams would be required under the
proposed standard. If medical surveillance was triggered at the action
level rather than the PEL, over 1,280,000 exams would be required.
Under the proposed standard, periodic medical exams would be required
on a triennial basis, increasing over time the total number of medical
exams. Thus, requiring medical surveillance only for employees exposed
above the proposed PEL reduces the burden on employers and focuses
resources on the employees at highest risk. OSHA solicits comments on
the approporate trigger for medical surveillance in the issues section
of the NPRM.
Paragraph (h)(1)(ii) of the proposal requires that the medical
examinations made available under the rule be performed by a physician
or other licensed health care professional (PLHCP). The term "PLHCP,"
as discussed further in section (b) (Definitions), above, refers to
individuals whose legal scope of practice allows them to provide, or be
delegated responsibility to provide, some or all of the health care
services required by the medical surveillance provisions. The
determination of who qualifies as a PLHCP is thus determined on a
state-by-state basis. OSHA considers it appropriate to allow any
professional to perform medical examinations and procedures made
available under the standard when they are licensed by state law to do
so. This provision provides flexibility to the employer, and reduces
cost and compliance burdens. The proposed requirement is consistent
with the approach of 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).
The proposed standard also specifies how frequently medical
examinations are to be offered to those employees covered by the
medical surveillance program. Under paragraph (h)(2), employers are
required to make available to covered employees an initial (baseline)
examination within 30 days after initial assignment unless the employee
has received a medical examination provided in accordance with the
standard within the past three years. The proposed requirement that a
medical examination be offered at the time of initial assignment is
intended to determine if an individual will be able to work in the job
involving respirable crystalline silica exposure without adverse
effects. It also serves the useful function of establishing a health
baseline for future reference. Where an examination that complies with
the requirements of the standard has been provided in the past three
years, that previous examination would serve these purposes, and an
additional examination would not be needed. For example, some employees
may work short-term jobs associated with construction projects and
other activities of limited duration. In these circumstances, an
employee may work for several different employers over the course of a
three-year period. In such cases, each employer who hires the employee
within three years of the employee's last medical examination would not
have to make available an initial medical examination, but could rely
on a written medical opinion from an examination provided in the past
three years, if the examination complied with the requirements of the
standard.
Proposed paragraphs (h)(2)(i)-(vi) specify that the baseline
medical examination provided by the PLHCP must consist of: medical and
work history; physical examination with special emphasis on the
respiratory system; chest X-ray or equivalent diagnostic study;
pulmonary function test; latent tuberculosis test; and other tests
deemed appropriate by the PLHCP. Special emphasis is placed on the
portions of the medical and work history focusing on exposure to
respirable-crystalline silica or other agents affecting the respiratory
system, history of respiratory system dysfunction (including signs and
symptoms such as shortness of breath, coughing, and wheezing), history
of tuberculosis, and smoking.
Medical and work histories are required because they are an
efficient and inexpensive means for collecting information that can aid
in identifying individuals who are at risk because of hazardous
exposures (ACOEM, 2006; WHO, 1996). Information on present and past
work exposures, medical illnesses, and symptoms can lead to the
detection of diseases at early stages when preventive measures can be
taken. Recording of symptoms is important because, in some cases,
symptoms indicating onset of disease can occur in the absence of
abnormal laboratory test findings.
The physical exam focuses on the respiratory system, which is known
to be susceptible to respirable crystalline silica toxicity. Aspects of
the physical exam, such as visual inspection, palpation, tapping, and
listening with a stethoscope, would allow the PLHCP to detect
abnormalities in chest shape or lung sounds that are associated with
compromised lung function (WHO, 1996; IMA/MSHA, 2008; NISA, 2010;
ACOEM, 2006). The ASTM standards do not specifically address a physical
exam as part of medical surveillance, but physical exams are included
in other recommendations (IMA/MSHA, 2008; NISA, 2010; ACOEM, 2006;
BCTD, 2001). OSHA's proposal for a physical exam provides for a more
comprehensive medical evaluation than that required by the ASTM
standards.
OSHA proposes that an X-ray or an equivalent diagnostic study be
made available at the first medical examination. An initial chest X-
ray, although not useful for preventing silicosis, can be useful for
diagnosing silicosis, for detecting mycobacterial disease, and for
detecting large opacities associated with cancer (IMA/MSHA 2008). It
also provides baseline data upon which to assess any subsequent
changes. X-rays are the standard medical test to diagnose respirable
crystalline silica-related lung diseases. However, the proposal allows
for an equivalent diagnostic study in place of the chest X-ray. This is
intended to allow for use of technologically advanced imaging
techniques in place of conventional X-rays.
An example of a diagnostic study that is equivalent to an X-ray is
a digital chest radiograph. Medical imaging is currently in the process
of transitioning from conventional film-based radiography to digital
radiography systems. Digital imaging systems offer a number of
advantages over conventional film-based X-rays, including 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 (Attfield and Weissman, 2009).
The proposed standard calls for an X-ray size of no less than 14 x
17 inches and no more than 16 x17 inches at full inspiration, which is
consistent with the X-ray film size required in NIOSH specifications
for medical examination of underground coal miners (42 CFR part 37).
The proposed standard also specifies interpretation and classification
of X-rays according to the International Labour Organization (ILO)
International Classification of Radiographs of Pneumoconioses by a
NIOSH-certified "B" reader. The ILO recently made standard digital
radiographic images available and has published guidelines on the
interpretation and classification of digital radiographic images (ILO
2011). Therefore, digital radiographic images can now be evaluated
according to the same ILO guidelines as X-ray films and are considered
equivalent diagnostic tests. The ILO guidelines require that digital
images be displayed on a medical-grade flat-panel monitor designed for
diagnostic radiology. ILO specifications for those monitors include a
minimal diagonal display of 21 inches per image, a maximum to minimum
luminance ratio of at least 50, a maximum luminance of no less than 250
candelas per square meter, a pixel pitch not to exceed 210 [micro]m,
and a resolution no less than 2.5 line-pairs per millimeter. NIOSH
(2011) has published guidelines for conducting digital radiography and
displaying digital radiographic images in a manner that will allow for
classification according to ILO guidelines. Hard copies printed from
digital images are not recommended for classification because they give
the appearance of more opacities compared to films or digital images
(Franzblau et al., 2009).
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 (NISA, 2010; WHO, 1996;
IMA/MSHA, 2008). The procedure involves scoring opacities according to
shape, size, location, and profusion. Opacities are first classified as
either small or large, with small opacities representing simple
silicosis and large opacities representing complicated silicosis. The
best indicator of silicosis severity is profusion, which is the B
reader's assessment of the amount of small opacities seen in the lung
fields (NISA, 2010; IMA/MSHA, 2008). Using a standard set of ILO X-ray
films or digital radiographic images, the B reader compares the
workers' X-rays or digital radiographic images with the ILO films or
digital radiographic images and rates the profusion of small opacities.
The numbers 0, 1, 2, or 3 are used to indicate increasing amounts of
small opacities. A 12-point profusion scale is employed, in which the B
reader gives a first choice and then a second choice profusion rating.
A NIOSH-certified B reader is a physician who has demonstrated
competency in the ILO classification system by passing proficiency and
periodic recertification examinations (NIOSH, 2011a). The NIOSH
certification procedures were designed to improve the proficiency of X-
ray and digital radiographic image readers and minimize variability of
readings. Standardized procedures for the evaluation of X-ray films and
digital images by certified, qualified individuals is warranted by the
prevalence and seriousness of silicosis. As of February 12, 2013, there
were 242 certified B readers in the United States.
Other radiological test methods that may be useful are computed
tomography (CT) or high resolution computed tomography (HRCT) scans.
Two older studies reported that CT or HRCT scans were not more
sensitive than X-rays for detecting silicosis but were more sensitive
than X-rays at distinguishing between early and advanced stages of
silicosis (B[eacute]gin et al., 1987a; Talini et al., 1995). More
recent studies and reviews reported that CT or HRCT may be superior to
chest X-ray in the early detection of silicosis and the identification
of progressive massive fibrosis (PMF) (Sun et al., 2008; Lopes et al.,
2008; Blum et al., 2008). However, the value of CT or HRCT scans should
be balanced with risks and disadvantages of those methods, which
include higher radiation doses (WHO, 1996).
CT or HRCT scans could be considered "equivalent diagnostic
studies" under paragraph (h)(2)(iii) of the proposed standard.
However, standardized methods for interpreting and reporting the
results of CT or HRCT scans are not currently available. The Agency
seeks comment on whether CT and HRCT scans should be considered
"equivalent diagnostic studies" under the standard, and has included
this topic in the "Issues" section of this preamble.
Paragraph (h)(2)(iv) of the proposed OSHA standard calls for
spirometry testing (forced vital capacity [FVC], forced expiratory
volume at one second [FEV1], and FEV1/FVC ratio)
by a spirometry technician with current certification from a NIOSH-
approved spirometry course as part of the baseline medical examination.
Pulmonary function tests, such as spirometry, are optional under the
ASTM standards (ASTM, 2006; 2009). ASTM (2006, 2009) and others point
to a lack of evidence that routine spirometry testing is useful for
detecting early stages of respirable crystalline silica-related
disease. They indicate that most abnormalities detected by spirometry
screening are not related to respirable crystalline silica-related
diseases but rather to factors such as smoking and non-occupationally
related diseases. There are also a number of obstacles to widespread
use of spirometry including inadequate training of medical personnel,
technical problems with some spirometers, and lack of standardization
for testing methodologies and procedures (ACOEM, 2011; IMA/MSHA, 2008;
ATS/ERS, 2005; NISA, 2010). However, ACOEM, (2011), IMA/MSHA (2008),
American Thoracic Society/European Respiratory Society (ATS/ERS, 2005),
and NISA (2010) go on to note that properly conducted spirometry is
considered a useful part of respiratory medical surveillance programs.
Because quality lung function tests are useful for obtaining
information about the employee's lung capacity and respiratory flow
rate, OSHA proposes to require spirometry as part of the baseline
medical examination. Information provided by spirometry is useful for
determining baseline lung function status upon which to assess any
subsequent lung function changes and for evaluating any loss of lung
function. This information may also be useful in assessing the health
of employees who wear respirators. The proposed requirement is
consistent with the approach of other OSHA standards, such as those for
asbestos (29 CFR 1910.1001) and cadmium (29 CFR 1910.1027).
Because it is imperative that spirometry be conducted according to
strict standards for quality control and for results to be consistently
interpreted, OSHA proposes that spirometry be administered by a
spirometry technician with current certification from a NIOSH-approved
spirometry course. The NIOSH-approved spirometry training is based upon
procedures and interpretation standards developed by the ATS/ERS and
European Respiratory Society and addresses topics such as instrument
calibration, testing performance, data quality, and interpretation of
results (NIOSH, 2011b). Requiring spirometry technicians to have
current certification from a NIOSH-approved spirometry course will
improve their proficiency in generating quality results that are
consistently interpreted. Similar recommendations are included in the
ASTM standards (Section 4.6.5.4) (ASTM 2006; 2009).
In paragraph (h)(2)(v), OSHA proposes testing for latent
tuberculosis infection at the baseline medical examination. In
contrast, the ASTM standards (Section 4.6.5.3) recommend tuberculosis
testing only when an X-ray shows evidence of silicosis (ASTM, 2006;
2009). NISA (2010) recommends baseline tuberculosis testing and
periodic testing in workers who have chest X-ray readings of 1/0 or
higher or more than 25 years of exposure to respirable crystalline
silica. OSHA believes that a general requirement for testing during the
initial medical examination will serve to protect workers exposed to
respirable crystalline silica by identifying latent tuberculosis
infection so it can be treated before active (infectious) tuberculosis
develops.
In 2008, there were almost 13,000 new cases of active tuberculosis
in the U.S. Although incidence of tuberculosis continues to decrease in
the U.S., the ultimate goal of tuberculosis control and prevention in
the U.S. is the elimination of tuberculosis (CDC, 2009). Active
tuberculosis cases are prevented by identifying and treating those with
latent tuberculosis disease.
As described in OSHA's Health Effects analysis and summarized in
Section V of this preamble, the risk of developing active tuberculosis
infection is higher in individuals with silicosis than those without
silicosis (Balmes, 1990; Cowie, 1994; Hnizdo and Murray, 1998;
Kleinschmidt and Churchyard, 1997; Murray et al., 1996). Moreover,
there is evidence that exposure to silica increases the risk for
pulmonary tuberculosis, independent of the presence of silicosis
(Cowie, 1994; Hnizdo and Murray, 1998; teWaterNaude et al., 2006). OSHA
therefore preliminarily concludes that it is in the best interest of
both the employer and the affected worker to identify latent
tuberculosis prior to silica exposure. The increased risk of developing
active pulmonary tuberculosis places not only the worker, but also his
or her co-workers and family members at increased risk of acquiring
this potentially fatal infectious disease. Early treatment of latent
disease would eliminate this risk. Testing for latent tuberculosis
infection will identify cases of this disease and alert affected
workers, so that the necessary treatment can be obtained from their
local public health department or other health care provider. OSHA's
proposed requirement is consistent with the recommendations of ACOEM
(2006), which recommends tuberculosis screening for all silica-exposed
workers. The Centers for Disease Control and Prevention recommends that
tuberculosis testing target populations who are at the highest risk of
developing the disease, including those with silicosis (CDC, 2000). The
Agency seeks comment on its preliminary determination that all workers
receiving an initial medical exam should receive testing for latent
tuberculosis infection, and has included this topic in the "Issues"
section of this preamble.
Paragraph (h)(2)(vi) of the proposal 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 (IMA/MSHA, 2008). For example, the PLHCP
may decide that additional tests are needed to address abnormal
findings in a pulmonary function test. OSHA believes that the PLHCP is
in the best position to decide if any additional medical tests are
necessary for each individual examined. Where additional tests are
deemed appropriate by the PLHCP, the proposed standard would require
that they be made available.
In paragraph (h)(3)(i), OSHA proposes periodic examinations
including medical and work history, physical examination emphasizing
the respiratory system, chest X-rays and pulmonary function tests, and
other tests deemed to be appropriate by the PLHCP. The examinations
would be required every three years under paragraph (h)(3) of this
proposal, unless the PLHCP recommends that they be made available more
frequently. The specific requirements for the examinations and the
value of the examinations for screening workers exposed to respirable
crystalline silica were addressed above. The proposed requirement for
examinations every three years is consistent with the ASTM standards
(Section 4.6.5), which recommend that medical surveillance be conducted
no less than every three years (ASTM, 2006; 2009). Other standards
recommend periodic evaluations at intervals ranging from two to five
years, depending on duration of exposure (IMA/MSHA, 2008; NISA, 2010;
ACOEM, 2006; BCTD, 2001).
The main goal of periodic medical surveillance for workers is to
detect adverse health effects at an early and potentially reversible
stage. Based on the Agency's experience, OSHA believes that
surveillance every three years would strike a reasonable balance
between the need to diagnose health effects at an early stage and the
limited number of cases likely to be identified through surveillance.
The proposed requirement that employers offer a chest X-ray or an
equivalent diagnostic test as part of the periodic medical examination
conducted every three years is an important aspect of early disease
detection. As indicated above, X-rays are appropriate tools for
detecting and monitoring the progression of silicosis, possible
complications such as mycobacterial disease, and large opacities
related to cancer (IMA/MSHA 2008). Detection of simple silicosis by
periodic X-ray could allow for implementation of exposure reduction
methods that are likely to decrease the risk of disease progression
(ACOEM, 2006). X-rays would also allow the detection of treatable
conditions, such as mycobacterial infections (ACOEM, 2006).
X-rays conducted every three years as part of the triennial medical
examinations are appropriate considering the long latency period of
most respirable crystalline silica-related diseases. The proposed
three-year frequency for chest X-rays represents a simplified approach
that balances a reasonable time frame for detecting disease and
administrative convenience. Under paragraph (h)(3)(ii) of the proposed
standard, the PLHCP can request X-rays more frequently. The proposed
frequency is consistent with the ASTM standards, as well as ACOEM
recommendations (ASTM, 2006; 2009; ACOEM, 2006). Other groups recommend
X-rays at intervals ranging from every two to five years, depending on
exposure duration (IMA/MSHA, 2008; NISA, 2010; WHO, 1996). OSHA is
interested in comments on the proposed X-ray frequency and has raised
this topic in the "Issues" section of this preamble.
Proposed paragraph (h)(3) also requires that spirometry (FVC,
FEV1, and FEV1/FVC ratio) be offered by a
spirometry technician with current certification from a NIOSH-approved
spirometry course, as part of the medical examination conducted every
three years. As noted above, spirometry is optional in the ASTM
standards (ASTM, 2006; 2009). However, OSHA believes that periodic
spirometry is a potentially valuable tool for detecting respirable
crystalline silica-related disease and monitoring the health of exposed
workers.
Periodic spirometry that adheres to strict quality standards is
useful for monitoring progressive lung function changes to identify
individual workers or groups of workers with abnormal lung function
changes. Quality longitudinal spirometry testing that compares workers'
lung function to their baseline levels is useful for detecting
excessive declines in lung function that could lead to severe
impairment over time. For example, recent studies have shown that
excessive decline in lung function can be an early warning sign for
risk of COPD development (Wang et al., 2009). Identifying workers who
are at risk of developing severe decrements in lung function would
allow for interventions to prevent further progression of disease. OSHA
is proposing a medical examination including a lung function test every
three years because exposure to respirable crystalline silica does not
usually cause severe declines in lung function over short time periods.
The proposed frequency is consistent with ACOEM (2006) and BCTD (2001),
which recommend lung function testing every two to three years. WHO
(1996) and NISA (2010) recommend annual pulmonary function testing, but
WHO (1996) states that if this is not feasible, it can be conducted at
the same frequency as chest X-rays (every two to five years). Paragraph
(h)(3) of the proposed standard gives the PLHCP the authority to
request lung function testing more frequently. The PLHCP might
recommend such a test because of age, tenure, exposure level, or
abnormal results. The Agency seeks comment on the proposed frequency of
pulmonary function testing and has raised this topic in the "Issues"
section of this preamble.
Paragraph (h)(4) of the proposed standard would require the
employer to ensure the examining PLHCP has a copy of the standard, and
to provide the following information to the PLHCP: a description of the
affected 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
personal protective equipment used or to be used by the employee,
including when and for how long the employee has used that equipment;
and information from records of employment-related medical examinations
previously provided to the affected employee and currently within the
control of the employer. Making this information available to the PLHCP
will aid in the evaluation of the employee's health in relation to
assigned duties and fitness to use personal protective equipment, when
necessary. The results of exposure monitoring are part of the
information that would be supplied to the PLHCP responsible for medical
surveillance. These results contribute valuable information to assist
the PLHCP in determining if an employee is likely to be at risk of
harmful effects from respirable crystalline silica exposure. A well-
documented exposure history also assists the PLHCP in determining if a
condition (e.g., compromised pulmonary function) may be related to
respirable crystalline silica exposure. Where the employer does not
have information directly indicating an employee's exposure (e.g.,
where the employer uses Table 1 in the proposed
construction standard and does not perform exposure monitoring), an
indication of the presumed exposure associated with the operation
(i.e., at or above the action level, above the PEL) would fulfill this
requirement.
Proposed paragraph (h)(5)(i) requires that the employer obtain a
written medical opinion from the PLHCP within 30 days of each medical
examination. The purpose of this requirement is to provide the employer
with a medical basis to aid in the determination of placement of
employees and to assess the employee's ability to use protective
clothing and equipment. OSHA believes the 30-day period will provide
the PLHCP sufficient time to receive and consider the results of any
tests included in the examination, and allow the employer to take any
necessary protective measures in a timely manner. The proposed
requirement that the opinion be in written form is intended to ensure
that employers and employees receive the benefit of this information.
Paragraphs (h)(5)(i)(A)-(D) of the proposal specify what must be
included in the PLHCP's opinion. The standard first proposes that the
PLHCP's written medical opinion describe 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. The standard also proposes that the PLHCP's written
medical opinion include recommended limitations for the employee's
exposure to respirable crystalline silica or use of personal protective
equipment such as respirators. These proposed requirements are
consistent with the overall goals of medical surveillance: to determine
if an individual can be exposed to respirable crystalline silica
present in his or her workplace without experiencing adverse health
effects, to identify respirable crystalline silica-related adverse
health effects so that appropriate intervention measures can be taken,
and to determine the employee's fitness to use personal protective
equipment such as respirators.
Paragraph (h)(5)(i)(C) proposes that the PLHCP must include in the
written medical opinion a statement that the employee should be
examined by a pulmonary specialist if the X-ray is classified as 1/0 or
higher by the "B" reader, or if referral to a pulmonary specialist is
otherwise deemed appropriate by the PLHCP. As described above,
paragraph (h)(2)(iii) of the proposed standard requires that X-rays be
interpreted according to the ILO Classification of Radiographs of
Pneumoconioses. The ASTM standards recommend that workers with
profusion opacities greater than 1/1 (profusion similar to that shown
on a standard category 1 radiograph) be evaluated at a frequency
determined by a physician qualified in pulmonary disease (Section
4.7.1) and receive annual counseling by a physician or other person
knowledgeable in occupational safety and health (Section 4.7.2) (ASTM,
2006; 2009). The proposed OSHA standard addresses pneumoconiosis at an
earlier stage than the ASTM standards, thus allowing for intervention
at an earlier indication of possibly abnormal findings.
Paragraph (h)(5)(i)(D) of the proposal would require that the PLHCP
include in the written medical opinion a statement that the PLHCP has
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. Under this provision, OSHA
anticipates that the employee will be informed directly by the PLHCP of
all results of his or her medical examination, including conditions of
nonoccupational origin. Direct consultation between the PLHCP and
employee ensures that the employee will receive all information about
health status, including non-occupationally related conditions, that
are not communicated to the employer.
Under proposed paragraph (h)(5)(ii), the employer must ensure that
the PLHCP does not include findings unrelated to crystalline silica
exposure in the written opinion provided to the employer or otherwise
reveal such findings to the employer. OSHA has proposed this provision
to ensure confidentiality of medical information and to reassure
employees participating in medical surveillance that they will not be
penalized or embarrassed as a result of the employer obtaining
information about them not directly pertinent to occupational exposure
to respirable crystalline silica. Paragraph (h)(5)(iii) of the proposed
standard requires the employer to provide a copy of the PLHCP's written
opinion to the employee within two weeks after the employer receives
it, to ensure that the employee has been informed of the results of the
examination in a timely manner.
OSHA is aware of concerns that the written medical opinion may
divulge confidential information regarding an employee's medical
condition, or may otherwise divulge information that may adversely
affect an individual's employment status. The Building and Construction
Trades Department, AFL-CIO has expressed the view that, except in
limited circumstances, any decision to disclose medical information to
an employer should be left to the employee (BCTD, 2009). OSHA respects
concerns for medical privacy and is aware of how disclosure of medical
information could potentially impact workers. The proposed requirements
are intended to balance employee privacy with employers' need for
information to assess possible health effects or risks related to
respirable crystalline silica exposure by employees. OSHA seeks comment
on the proposed requirement for the employer to obtain a written
medical opinion, and has raised this topic in the "Issues" section of
this preamble.
Proposed paragraph (h)(6)(i) requires that an examination by a
pulmonary specialist be offered when indicated in the PLHCP's written
opinion. This requirement is intended to ensure that individuals with
abnormal findings are seen by a professional with expertise in
respiratory disease who can provide not only expert medical judgment,
but also counseling regarding work practices and personal habits that
could affect these individuals' respiratory health. In this respect the
proposed provision is conceptually consistent with the provision in the
ASTM standards (4.7.2) for counseling by a physician or other person
qualified in occupational safety and health. Data presented by the
American Board of Internal Medicine (ABIM) indicate that as of February
5, 2013, 13,138 physicians in the United States had valid certificates
in pulmonary disease (ABIM, 2013). ABIM does not report how many of
these physicians are currently practicing. However, ABIM does report
that 4,378 new certificates in pulmonary disease were issued in the
period from 2001-20010 (ABIM, 2012). Because physicians are likely to
practice in the field for some time after receiving their
certification, this figure indicates that a substantial number of
pulmonary specialists are available to perform examinations required
under the proposed standard.
Paragraph (h)(6)(i) further proposes that these additional
examinations by pulmonary specialists must be made available within 30
days following receipt of the PLHCP's recommendation that examination
by such a specialist is indicated. OSHA proposes, under paragraph
(h)(6)(ii), that the employer provide the pulmonary specialist with the
same information that is provided to the original PLHCP (i.e., a copy
of the standard; a description of the affected 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 personal protective equipment used or to be
used by the employee, including when and for how long the employee has
used that equipment; and information from records of employment-related
medical examinations previously provided to the affected employee,
currently within the control of the employer). The reasons why the
pulmonary specialist should receive this information are the same as
those for the PLHCP and were addressed above.
Proposed paragraph (h)(6)(iii) requires the employer to obtain a
written medical opinion from the pulmonary specialist comparable to the
written opinion obtained from the original PLHCP, including a
description of the employee's health condition as it relates to
respirable crystalline silica exposure, the pulmonary specialist's
opinion as to whether the employee would be placed at increased risk of
material health impairment as a result of exposure to respirable
crystalline silica, and any recommended limitations on the employee's
exposure to respirable crystalline silica or use of personal protective
equipment. The pulmonary specialist would also need to state in the
written opinion that these findings were explained to the employee. The
reasons why the pulmonary specialist should provide this information to
the employer are the same as those for the PLHCP and were addressed
above.
Some OSHA health standards contain a provision for medical removal
protection (MRP). MRP typically requires that the employer 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 total normal earnings, as well as all other
employee rights and benefits, of the removed employee. However, MRP is
not intended to serve as a workers' compensation system. The primary
reason MRP was included in previous standards was to encourage employee
participation in medical surveillance. By protecting employees who are
removed on a temporary basis from economic loss, this potential
disincentive to participating in medical surveillance is alleviated.
Previous standards also included MRP requirements to prevent the onset
of disease and to detect and minimize the extent of existing disease.
For example, OSHA's cadmium standard (29 CFR 1910.1026) provides for
MRP based on criteria such as biological monitoring results and
evidence of cadmium-related disease. Removal from exposure can allow
for biological monitoring results to return to acceptable levels, or
for improvement in the employee's health condition.
OSHA has made a preliminary determination that MRP is not
reasonably necessary or appropriate for respirable crystalline silica-
related health effects. Thus, the proposed rule does not include a
provision for MRP. The Agency believes that respirable crystalline
silica-related health effects (e.g., silicosis) are generally chronic
conditions that are not remedied by temporary removal from exposure.
Since situations where temporary removal would be appropriate are not
anticipated to occur, OSHA does not believe that MRP is necessary. The
Agency seeks comment on this preliminary determination, and has
included this topic in the "Issues" section of this preamble.
(i) Communication of Respirable Crystalline Silica Hazards to Employees
The proposed standard includes requirements intended to ensure that
the dangers of respirable crystalline silica exposure are communicated
to employees by means of labels, safety data sheets, and employee
information and training. OSHA believes that it 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. As part of an overall hazard
communication program, training serves to explain and reinforce the
information presented on labels and in safety data sheets. 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.
OSHA has proposed to revise its existing hazard communication
standard (HCS) (29 CFR 1910.1200) to conform with the United Nations'
Globally Harmonized System of Classification and Labelling of Chemicals
(GHS), Revision 3. (See 74 FR 50280, Sept. 30, 2009.) The hazard
communication requirements of the proposed crystalline silica rule are
designed to be consistent with the revised HCS, while including
additional specific requirements needed to protect employees exposed to
respirable crystalline silica. OSHA intends for the requirements of the
respirable crystalline silica rule to conform with the final hazard
communication standard. The proposed requirements are also consistent
with the worker training and education provisions of ASTM
International's standards addressing control of occupational exposure
to respirable crystalline silica (Section 4.8 in both E 1132-06 and E
2625-09) (ASTM, 2006; 2009).
In the HCS rulemaking, OSHA proposed to revise substance-specific
health standards by referencing the HCS requirements for labels, safety
data sheets, and training and by identifying the hazards that need to
be addressed in the employer's written hazard communication program.
Accordingly, proposed paragraph (i)(1) of the silica rule requires
compliance with the HCS requirements and lists cancer, lung effects,
immune system effects, and kidney effects as hazards that need to be
addressed in the employer's hazard communication program. These are the
health effects that OSHA has preliminarily determined to be associated
with respirable crystalline silica exposure.
Proposed paragraph (i)(2)(i) requires the employer to ensure that
each affected employee can demonstrate knowledge of the specified
training elements (discussed below). When using the term "affected
employee" in this context, OSHA is referring to any employee who may
be exposed to respirable crystalline silica under normal conditions of
use or in a foreseeable emergency. Employee knowledge of the specified
training elements could be determined through methods such as
discussion of the required training subjects, written tests, or oral
quizzes. In order 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. 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.
Proposed paragraphs (i)(2)(i)(A) and (B), which require training on
specific operations in the workplace that could result in respirable
crystalline silica exposure and specific procedures the employer has
implemented to protect employees from exposure to respirable
crystalline silica, closely parallel the HCS. OSHA has included these
elements in the proposed respirable crystalline silica rule to ensure
that both employers and employees understand the sources of potential
silica exposure and control measures used to reduce exposure. Workers
have a particularly important role in controlling silica exposures
because work practices often play a crucial role in controlling
exposures, and engineering controls frequently require action on the
part of workers to function effectively. For example, stationary
masonry saws using wet methods to control dust may require adjustment
of the nozzle and the water flow rate to ensure that an adequate volume
of water reaches the cutting area. Water filters may need to be rinsed
or replaced at regular intervals, and basin water may need to be
replaced on a regular basis to prevent clogging of the nozzles.
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. When tuckpointing, for instance, workers should ensure that
the shroud surrounding the grinding wheel remains flush against the
working surface 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. Workers' implementation of work practices such as
these is often necessary to ensure that they are adequately protected,
and OSHA has preliminarily concluded that the importance of recognizing
potential exposures and understanding appropriate work practices merits
including these provisions in the proposed silica rule.
Proposed paragraph (i)(2)(i)(C) requires training on the contents
of the respirable crystalline silica rule, and proposed paragraph
(i)(2)(ii) requires that the employer make a copy of the standard
readily available to employees without cost. OSHA believes that it is
important for employees to be familiar with and have access to the
proposed respirable crystalline silica standard and the employer's
obligations to comply with it.
Proposed paragraph (i)(2)(i)(D) requires employers to provide
training to workers on the purpose and description of the medical
surveillance program found at paragraph (h) of the proposed silica
rule. Such training should cover the signs and symptoms of respirable
crystalline silica-related adverse health effects including cancer,
lung effects, immune system effects, and kidney effects. This
information will help to ensure that employees are able to effectively
participate in medical surveillance, which is discussed above in
section (h) (Medical surveillance).
OSHA intends for the training requirements under the proposed
silica standard, like those in the hazard communication standard, to be
performance-oriented. The Agency has therefore written proposed section
(i) in terms of objectives, which are 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 standard also lists the subjects, which are in addition to
or reiterate those covered by the HCS, that must be addressed in
training, but not the specific ways in which the training is to be
accomplished. OSHA believes 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. 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 in each specific workplace.
In order for the training to be effective, the employer must ensure
that it is provided in a manner that the employee is able to
understand. OSHA has consistently required that employee training
required by OSHA standards be presented in a manner that employees can
understand. This position was recently reiterated in a memorandum to
OSHA Regional Administrators from Assistant Secretary David Michaels
(OSHA, 2010). Employees have varying educational levels, literacy, and
language skills, and the training must be presented in a language, or
languages, and at a level of understanding that accounts for these
differences in order to meet the proposed requirement in paragraph
(i)(2) that individuals being trained understand the specified
elements. This may mean, for example, providing materials, instruction,
or assistance in Spanish rather than English if the workers being
trained are Spanish-speaking and do not understand English. The
employer is not required to provide training in the employee's
preferred language if the employee understands both languages; as long
as the employee is able to understand the material in the language
used, the intent of the proposed standard would be met.
The frequency of training under the proposed standard is determined
by the needs of the workplace. At the time of initial assignment to a
position involving exposure to respirable crystalline silica, each
employee needs to be trained sufficiently to understand the specified
training elements. Additional training may be needed periodically to
refresh and reinforce the memories of employees who have previously
been trained or to ensure that employees are informed of new
developments in the workplace that may result in new or additional
exposures to respirable crystalline silica. Additional training might
also be necessary after new engineering controls are installed to
ensure that employees are able to properly use the new controls and
implement work practices relating to those controls. Further, employees
might need additional training in the use of new personal protective
equipment. Such training would ensure that employees are able to
actively participate in protecting themselves under the conditions
found in the workplace, even if those conditions change.
(j) Recordkeeping
Paragraph (j) of the proposed standard requires employers to
maintain air monitoring data, objective data, and medical surveillance
records. The recordkeeping requirements are proposed in accordance with
section 8(c) of the 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 Act or for developing
information regarding the causes and prevention of occupational
accidents and illnesses.
Proposed paragraph (j)(1)(i) requires employers to keep accurate
records of all air monitoring results used or relied on to assess
employee exposure to respirable crystalline silica. Paragraph
(j)(1)(ii) requires that such records include the following
information: the date of measurement for each sample taken; the
operation 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. These requirements are generally consistent with those found in other OSHA standards, such
as methylene chloride (29 CFR 1910.1052) and chromium (VI) (29 CFR
1910.1026). OSHA has proposed an additional requirement in this
rulemaking--recording the identity of the laboratory that performed the
analysis of exposure measurements--because of the importance of
ensuring that laboratories performing analyses of respirable
crystalline silica samples conform with the requirements specified in
paragraph (d)(5) of the proposed rule.
Proposed paragraph (j)(2)(i) requires employers who rely on
objective data, pursuant to proposed paragraph (d)(2)(ii)(B) or
(d)(3)(ii), to keep accurate records of the objective data. Objective
data means information, such as air monitoring data from industry-wide
surveys or calculations based on the composition or chemical and
physical properties of a substance, demonstrating employee exposure to
respirable crystalline silica associated with a particular product,
material, process, operation, or activity.
Proposed paragraph (j)(2)(ii) 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, operation, or activity involved and how the
data support the assessment; and other data relevant to the process,
operation, activity, material, or employee exposures. Since objective
data may be used to exempt the employer from provisions of the proposal
or provide a basis for selection of respirators, it is critical that
the use of objective data be carefully documented. Reliance on
objective data is intended to provide the same degree of assurance that
employee exposures have been correctly characterized as air monitoring
would. The records should demonstrate a reasonable basis for the
conclusions drawn from the objective data.
Proposed paragraph (j)(3)(i) requires the employer to establish and
maintain an accurate record for each employee subject to medical
surveillance under paragraph (h) of the proposed standard. Paragraph
(j)(3)(ii) lists the categories of information that an employer would
be required to record: the name and social security number of the
employee; a copy of the PLHCP's and pulmonary specialist's written
opinions about the employee; and a copy of the information provided to
the PLHCPs and pulmonary specialists as required by proposed paragraph
(h)(4). The information provided to the PLHCPs and pulmonary
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 (see paragraph (h)(4)).
OSHA believes 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. Employee
access to medical surveillance records helps protect employees because
such records contribute to the evaluation of employees' health and
enable employees and their health care providers to make informed
health care decisions. These records are especially important when an
employee's medical conditions place him or her at increased risk of
health impairment from further exposure to respirable crystalline
silica. Furthermore, the employer could evaluate medical surveillance
data for indications that workplace conditions are associated with
increased risk of illness and take corrective actions. Finally, 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.
Proposed paragraphs (j)(1)(iii), (j)(2)(iii), and (j)(3)(iii)
require employers to maintain and provide access to air monitoring,
objective data, and medical surveillance records, respectively, in
accordance with OSHA's standard addressing access to employee exposure
and medical records (29 CFR 1910.1020). That standard, specifically 29
CFR 1910.1020(d), requires employers to ensure the preservation and
retention of exposure and medical records. Air monitoring data and
objective data are considered employee exposure records that must be
maintained for at least 30 years in accordance with 29 CFR
1910.1020(d)(1)(ii). 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).
The maintenance and access provisions incorporated from 29 CFR
1910.1020 ensure that records are available to employees so that they
may examine the employer's exposure assessments and assure themselves
that they are being adequately protected. Moreover, compliance with the
requirement to maintain records of exposure data will enable the
employer to show, at least for the duration of the retention-of-records
period, that the exposure assessment was accurate and conducted in an
appropriate manner. The lengthy record retention period is necessitated
in this case by the long latency period commonly associated with
silica-related diseases. Furthermore, determining causality of disease
in employees is assisted by, and in some cases requires, examining
present and past exposure data as well as the results of present and
past medical examinations.
(k) Dates
Under paragraph (k)(1) of the proposed standard, the final
crystalline silica rule becomes effective 60 days after its publication
in the Federal Register. This period is intended to allow affected
employers the opportunity to familiarize themselves with the standard.
Under paragraph (k)(2)(i), employer obligations to comply with most
requirements of the final rule begin 180 days after the effective date
(240 days after publication of the final rule). This additional time
period after the effective date is designed to allow employers to
complete initial exposure assessments, establish regulated areas or
access control plans, provide initial medical examinations, and comply
with other provisions of the rule.
Paragraph (k)(2)(ii) allows additional time for employers to
implement the engineering controls required under paragraph (f) of the
proposed rule. Engineering controls need to be in place within one year
after the effective date. This is to allow affected employers
sufficient time to design, obtain, and install the necessary control
equipment. During the period before engineering controls are
implemented, employers must provide respiratory protection to employees
under proposed paragraph (g)(1)(i).
Paragraph (k)(2)(iii) specifies that the laboratory requirements in
paragraph (d)(5)(ii) of this section commence two years after the
effective date. OSHA recognizes that the requirements for monitoring in
the proposed rule will increase the demand for analysis of respirable
crystalline silica samples. A two year start-up period is proposed to
allow time for laboratories to achieve compliance with the proposed
requirements, particularly with regard to requirements for
accreditation and round robin testing.
OSHA solicits comment on the adequacy of these proposed start-up
dates. OSHA would like to ensure that engineering controls and medical
surveillance are implemented as quickly as possible, while also
ensuring that employers have sufficient time to complete these processes. OSHA is
also interested in ensuring that laboratories comply with the
requirements of the standard as quickly as possible, while also
ensuring that sufficient laboratory capacity is available to meet the
needs of employers. In addition, the Agency is interested in mitigating
impacts on firms complying with the rule, and seeks comment on
approaches that would phase in requirements of the rule based on
industry, employer size, or other factors. The Agency has included
these topics in the "Issues" section of this preamble.
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List of Subjects in 29 CFR Parts 1910, 1915, and 1926
Cancer, Chemicals, Cristobalite, Crystalline silica, Hazardous
substances, Health, Occupational safety and health, Quartz, Reporting
and recordkeeping requirements, Silica, Tridymite.
XVIII. 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 proposed 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.
333); section 41 of the Longshore and Harbor Worker's Compensation Act
(33 U.S.C. 941); Secretary of Labor's Order No. 4-2010 (75 FR 55355,
September 10, 2010); and 29 CFR part 1911.
Signed at Washington, DC, on August 23, 2013.
David Michaels,
Assistant Secretary of Labor for Occupational Safety and Health.
Amendments to Standards
For the reasons set forth in the preamble, OSHA proposes to amend
chapter XVII of title 29, parts 1910, 1915, and 1926, of the Code of
Federal Regulations 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. 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 31159), or 4-2010 (75 FR 55355), 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.
0
2. In Sec. 1910.1000, Table Z-1--Limits for Air Contaminants, remove
"Silica, crystalline cristobalite, respirable dust", "Silica,
crystalline quartz, respirable dust", "Silica, crystalline tripoli
(as quartz), respirable dust", and "Silica, crystalline tridymite,
respirable dust"; and add "Silica, crystalline, respirable dust; see
1910.1053" in alphabetical order, to read as follows:
Sec. 1910.1000 Air contaminants.
* * * * *
Table Z-1--Limits for Air Contaminants
----------------------------------------------------------------------------------------------------------------
Substance CAS No. (c) ppm \(a)\ \1\ mg/m3(b)1 Skin designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust;
see 1910.1053..........................
* * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * *
0
3. In Sec. 1910.1000, Table Z-3--Mineral Dusts, the entry "Silica:"
is revised to read as follows:
Sec. 1910.1000 Air contaminants.
* * * * *
Table Z-3--Mineral Dusts
----------------------------------------------------------------------------------------------------------------
Substance mppcf \a\ mg/m\3\
----------------------------------------------------------------------------------------------------------------
Silica:
Amorphous, including natural diatomaceous earth......................... 20 80 mg/m\3\
-----------------
%SiO2
* * * * * * *
----------------------------------------------------------------------------------------------------------------
0
4. A new Sec. 1910.1053 is added, to read as follows:
Sec. 1910.1053 Respirable crystalline silica.
(a) Scope and application. (1) This section applies to all
occupational exposures to respirable crystalline silica, except:
(2) Construction work as defined in 29 CFR 1910.12(b) and covered
under 29 CFR part 1926; and
(3) Agricultural operations covered under 29 CFR part 1928.
(b) Definitions. For the purposes of this section the following
definitions apply:
Action level means a concentration of airborne respirable
crystalline silica of 25 micrograms per cubic meter of air (25 [mu]g/
m\3\), calculated as an 8-hour time-weighted average (TWA).
Assistant Secretary means the Assistant Secretary of Labor for
Occupational Safety and Health, U.S. Department of Labor, or designee.
Competent person means 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.
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 or
chemical and physical properties of a substance demonstrating employee
exposure to respirable crystalline silica associated with a particular
product or material or a specific process, operation, or activity. The
data must reflect workplace conditions closely resembling 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.
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 airborne particles that contain
quartz, cristobalite, and/or tridymite and whose measurement is
determined 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.
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. (i) Each employer covered by
this section shall assess the exposure of employees who are or may
reasonably be expected to be exposed to respirable crystalline silica
at or above the action level.
(ii) The employer shall determine employee exposures from breathing
zone air samples that reflect the 8-hour TWA exposure of each employee.
(iii) The employer shall determine 8-hour TWA exposures on the
basis of one or more 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 shall sample the
employee(s) who are expected to have the highest exposure to respirable
crystalline silica.
(2) Initial exposure assessment. (i) Except as provided for in
paragraph (d)(2)(ii) of this section, each employer shall perform
initial monitoring of employees who are, or may reasonably be expected
to be, exposed to airborne concentrations of respirable crystalline
silica at or above the action level.
(ii) The employer may rely on existing data to satisfy this initial
monitoring requirement where the employer:
(A) Has monitored employee exposures after [INSERT DATE 12 MONTHS
PRIOR TO EFFECTIVE DATE OF FINAL RULE] under conditions that closely
resemble those currently prevailing, provided that such monitoring
satisfies the requirements of paragraph (d)(5)(i) of this section with
respect to analytical methods employed; or
(B) Has objective data that demonstrate that respirable crystalline
silica is not capable of being released in airborne concentrations at
or above the action level under any expected conditions of processing,
use, or handling.
(3) Periodic exposure assessments. 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. If initial monitoring indicates that
employee exposures are at or above the action level, the employer shall
assess employee exposures to respirable crystalline silica either under
the fixed schedule prescribed in paragraph (d)(3)(i) of this section or
in accordance with the performance-based requirement prescribed in
paragraph (d)(3)(ii) of this section.
(i) Fixed schedule option. (A) Where 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.
(B) Where initial or subsequent exposure monitoring reveals that
employee exposures are above the PEL, the employer shall repeat such
monitoring at least every three months.
(C) 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 for that employee, except as otherwise provided
in paragraph (d)(4) 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.
(4) Additional exposure assessments. The employer shall conduct
additional exposure assessments as required under paragraph (d)(3) of
this section 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.
(5) Method of sample analysis. (i) The employer shall ensure that
all samples taken to satisfy the monitoring requirements of paragraph
(d) of this section are 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.
(ii) The employer shall ensure that samples are analyzed by a
laboratory that:
(A) 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;
(B) Participates in round robin testing with at least two other
independent laboratories at least every six months;
(C) Uses the most current National Institute of Standards and
Technology (NIST) or NIST traceable standards for instrument
calibration or instrument calibration verification;
(D) Implements an internal quality control (QC) program that
evaluates analytical uncertainty and provides employers with estimates
of sampling and analytical error;
(E) 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;
(F) 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:
(1) Each day that samples are analyzed, performs instrument
calibration checks with standards that bracket the sample
concentrations;
(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
(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.
(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 the 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, 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 and access control. (1) General. 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, each employer shall establish and implement either a
regulated area in accordance with paragraph (e)(2) of this section or
an access control plan in accordance with paragraph (e)(3) of this
section.
(2) Regulated areas option. (i) 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.
(ii) Demarcation. The employer shall demarcate regulated areas from
the rest of the workplace in any manner that adequately establishes and
alerts employees to the boundaries of the area and minimizes the number
of employees exposed to respirable crystalline silica within the
regulated area.
(iii) 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.
(iv) 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.
(v) Protective work clothing in regulated areas. (A) Where there is
the potential for employees' work clothing to become grossly
contaminated with finely divided material containing crystalline
silica, the employer shall provide either of the following:
(1) Appropriate protective clothing such as coveralls or similar
full-bodied clothing; or
(2) Any other means to remove excessive silica dust from
contaminated clothing that minimizes employee exposure to respirable
crystalline silica.
(B) The employer shall ensure that such clothing is removed or
cleaned upon exiting the regulated area and before respiratory
protection is removed.
(3) Written access control plan option. (i) The employer shall
establish and implement a written access control plan.
(ii) The written access control plan shall contain at least the
following elements:
(A) Provisions for a competent person to identify the presence and
location of any areas where respirable crystalline silica exposures
are, or can reasonably be expected to be, in excess of the PEL;
(B) Procedures for notifying employees of the presence and location
of areas identified pursuant to paragraph (e)(3)(ii)(A) of this
section, and for demarcating such areas from the rest of the workplace
where appropriate;
(C) For multi-employer workplaces, the methods the employer covered
by this section will use to inform other employer(s) of the presence
and location of areas where respirable crystalline silica exposures may
exceed the PEL, and any precautionary measures that need to be taken to
protect employees;
(D) Provisions for limiting access to areas where respirable
crystalline silica exposures may exceed the PEL to effectively minimize
the number of employees exposed and the level of employee exposure;
(E) Procedures for providing each employee and their designated
representative entering an area where respirable crystalline silica
exposures may exceed the PEL with an appropriate respirator in
accordance with paragraph (g) of this section, and requiring each
employee and their designated representative to use the respirator
while in the area; and
(F) Where there is the potential for employees' work clothing to
become grossly contaminated with finely divided material containing
crystalline silica:
(1) Provisions for the employer to provide either appropriate
protective clothing such as coveralls or similar full-bodied clothing,
or any other means to remove excessive silica dust from contaminated
clothing that minimizes employee exposure to respirable crystalline
silica; and
(2) Provisions for the removal or cleaning of such clothing.
(iii) The employer shall review and evaluate the effectiveness of
the written access control plan at least annually and update it as
necessary.
(iv) The employer shall make the written access control plan
available for examination and copying, upon request, to employees,
their designated representatives, the Assistant Secretary and the
Director.
(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) Abrasive blasting. In addition to the requirements of paragraph
(f)(1) of this section, the employer shall comply with the requirements
of 29 CFR 1910.94 (Ventilation), 29 CFR 1915.34 (Mechanical paint
removers), and 29 CFR part 1915, subpart I (Personal Protective
Equipment), as applicable, where abrasive blasting operations are
conducted using crystalline silica-containing blasting agents, or where
abrasive blasting operations are conducted on substrates that contain
crystalline silica.
(3) Cleaning methods. (i) The employer shall ensure that
accumulations of crystalline silica are cleaned by HEPA-filter
vacuuming or wet methods where such accumulations could, if disturbed,
contribute to employee exposure to respirable crystalline silica that
exceeds the PEL.
(ii) 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.
(4) Prohibition of rotation. The employer shall not rotate
employees to different jobs to achieve compliance with the PEL.
(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 work operations for
which engineering and work practice controls are not feasible;
(iii) During work operations 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
pursuant to paragraph (e) of this section.
(v) During periods when the employee is in an area where respirator
use is required under an access control plan pursuant to paragraph
(e)(3) of this section.
(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) 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 above the PEL 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 (posterior/anterior view; no less than 14 x 17
inches and no more than 16 x 17 inches at full inspiration),
interpreted and classified according to the International Labour
Organization (ILO) International Classification of Radiographs of
Pneumoconioses by a NIOSH-certified "B" reader, or an equivalent
diagnostic study;
(iv) A pulmonary function test to include forced vital capacity
(FVC) and forced expiratory volume at one second (FEV1) and
FEV1/FVC ratio, administered by a spirometry technician with
current certification 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) (except paragraph (h)(2)(v)) of this section 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 affected 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 that equipment; and
(iv) Information from records of employment-related medical
examinations previously provided to the affected employee and currently
within the control of the employer.
(5) PLHCP's written medical opinion. (i) The employer shall obtain
a written medical opinion from the PLHCP within 30 days of each medical
examination performed on each employee. The written opinion shall
contain:
(A) A description of the employee's health condition as it relates
to exposure to respirable crystalline silica, including the PLHCP's
opinion as to whether the employee has any detected medical
condition(s) that would place the employee at increased risk of
material impairment to health from exposure to respirable crystalline
silica;
(B) Any recommended limitations upon the employee's exposure to
respirable crystalline silica or upon the use of personal protective
equipment such as respirators;
(C) A statement that the employee should be examined by an American
Board Certified Specialist in Pulmonary Disease ("pulmonary
specialist") pursuant to paragraph (h)(6) 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 pulmonary specialist is
otherwise deemed appropriate by the PLHCP; and
(D) A statement that the PLHCP has 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.
(ii) The employer shall ensure that the PLHCP does not reveal to
the employer specific findings or diagnoses unrelated to occupational
exposure to respirable crystalline silica.
(iii) The employer shall provide a copy of the PLHCP's written
medical opinion to the examined employee within two weeks after
receiving it.
(6) Additional examinations. (i) If the PLHCP's written medical
opinion indicates that an employee should be examined by a pulmonary
specialist, the employer shall make available a medical examination by
a pulmonary specialist within 30 days after receiving the PLHCP's
written medical opinion.
(ii) The employer shall ensure that the examining pulmonary
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 obtain a written medical opinion from the
pulmonary specialist that meets the requirements of paragraph (h)(5)
(except paragraph (h)(5)(i)(C)) 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 affected employee can demonstrate knowledge of at
least the following:
(A) Specific operations in the workplace that could result in
exposure to respirable crystalline silica, especially operations where
exposure may exceed the PEL;
(B) Specific procedures the employer has implemented to protect
employees from exposure to respirable crystalline silica, including
appropriate work practices and use of personal protective equipment
such as respirators and protective clothing;
(C) The contents of this section; and
(D) 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 affected employee.
(j) Recordkeeping. (1) Air monitoring data. (i) The employer shall
maintain an accurate record of all exposure measurement results used or
relied on to characterize 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 operation 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 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, operation, or activity and how
the data support the assessment; and
(E) Other data relevant to the process, operation, activity,
material, or employee exposures.
(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 establish 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 PLHCP's and pulmonary specialist's written
opinions; and
(C) A copy of the information provided to the PLHCPs and pulmonary
specialists as required by paragraph (h)(4) of this section.
(iii) The employer shall ensure that medical records are maintained
and made available in accordance with 29 CFR 1910.1020.
(k) Dates. (1) Effective date. This section shall become effective
November 12, 2013
(2) Start-up dates. (i) All obligations of this section, except
engineering controls required by paragraph (f) of this section and
laboratory requirements in paragraph (d)(5)(ii) of this section,
commence 180 days after the effective date.
(ii) Engineering controls required by paragraph (f) of this section
shall be implemented no later than one year after the effective date.
(iii) Laboratory requirements in paragraph (d)(5)(ii) of this
section commence two years after the effective date.
Appendix A to Sec. 1910.1053--Medical Surveillance Guidelines (Non-
Mandatory)
Introduction
The purpose of this non-mandatory Appendix is to provide helpful
information about complying with the medical surveillance provisions
of the Respirable Crystalline Silica standard, as well as to provide
other helpful recommendations and information. Medical screening and
surveillance allow for early identification of exposure-related
health effects in individual workers and groups of workers,
respectively, so that actions can be taken to both avoid further
exposure and prevent adverse health outcomes. Silica-related
diseases can be fatal, encompass a variety of target organs, and may
have public health consequences. Thus, medical surveillance of
silica-exposed workers requires involvement of clinicians with
thorough knowledge of silica-related health effects and a public
health perspective.
This Appendix is divided into four sections. Section I reviews
silica-related diseases, appropriate medical responses, and public
health responses. Section II outlines
the components of the medical surveillance program for workers
exposed to silica. Section III describes the roles and
responsibilities of the clinician implementing the program and of
other medical specialists and public health providers. Section IV
provides additional resources.
I. Recognition of Silica-Related Diseases
Overview. 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 a number of
adverse health effects. Exposure to respirable crystalline silica
can occur in foundries, industries that have 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
tuckpointing.
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.
A. 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 as follows:
1. Symptoms--shortness of breath and cough, although workers 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
mycobacterium tuberculosis infection (TB) or lung cancer. Workers
with these symptoms should immediately receive further evaluation
and treatment.
2. Physical Examination--may be normal or disclose dry rales or
rhonchi on lung auscultation.
3. Spirometry--may be normal or may show only mild restriction
or obstruction.
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" are seen.
5. Clinical Course--chronic silicosis in most cases is a slowly
progressive disease.
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. Additionally, a case of acute or
accelerated silicosis indicates a significant breakdown in
prevention. Urgent communication with the employer is warranted to
review exposure levels and protect other workers.
B. Accelerated Silicosis. Accelerated silicosis occurs within 2-
10 years of exposure and results from high levels of exposure to
respirable crystalline silica. The clinical presentation of
accelerated silicosis is as follows:
1. Symptoms--shortness of breath, cough, and sometimes sputum
production. Workers with accelerated silicosis are at high risk of
tuberculosis, atypical mycobacterial infections, and fungal
superinfections. Constitutional symptoms, such as fever, weight
loss, hemoptysis, and fatigue, may herald one of these infections or
the onset of lung cancer.
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
disease.
3. Spirometry--restriction or mixed restriction/obstruction.
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.
5. Clinical Course--accelerated silicosis has a rapid, severe
course. Referral to a physician who is American Board of Medical
Specialties (ABMS)-Certified in Pulmonary Medicine should be made
whenever the diagnosis of accelerated silicosis is being considered.
Referral to the appropriate specialist should be made if signs or
symptoms of tuberculosis, other silica-related infections, or lung
cancer are observed. As noted above, the clinician should also alert
the employer of the need for immediate review of exposure controls
in the worksite in order to protect other workers.
C. Acute Silicosis. Acute silicosis is a rare disease caused by
inhalation of very 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, 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. Symptoms--sudden, progressive, and severe shortness of
breath. Constitutional symptoms are frequently present and include
weight loss, fatigue, productive cough, hemoptysis, and pleuritic
chest pain.
2. Physical Examination--dyspnea at rest, cyanosis, decreased
breath sounds, inspiratory rales, clubbing of the digits, and fever.
3. Spirometry--restriction or mixed restriction/obstruction.
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.
5. Clinical Course--workers with acute silicosis are at high
risk of tuberculosis, atypical mycobaterial infections, and fungal
superinfections. Because this disease is immediately life-
threatening and indicates a profoundly high level of exposure, it
constitutes an immediate medical and public health emergency. The
worker must be urgently referred to a physician ABMS-certified in
Pulmonary Medicine. As noted above, the clinician should also alert
the employer of the need for immediate exposure controls in the
worksite in order to protect other workers.
During medical surveillance examinations, clinicians should be
alert for other silica-related health outcomes as described below.
D. Chronic Obstructive Pulmonary Disease (COPD). COPD, including
chronic bronchitis and emphysema, has also been documented in
silica-exposed workers, including those who do not develop
silicosis. Periodic spirometry tests are performed to evaluate each
worker for progressive changes consistent with the development of
COPD. Additionally, collective spirometry data for groups of workers
should be evaluated for declines in lung function, thereby providing
a mechanism to detect insufficient silica control measures for
groups of workers.
E. 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. Early studies noted an
association between workers with silicosis and serologic markers for
autoimmune diseases, including antinuclear antibodies, rheumatoid
factor, and immune complexes (Jalloul and Banks, 2007).
F. Tuberculosis (TB). Silica-exposed workers with latent TB are
3-30 times more likely to develop active pulmonary TB infection
(ATS, 1997; Rees, 2007). Although 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 silica
exposure, greater profusion of radiographic abnormalities, or a
diagnosis of silicosis. Demographic characteristics are known to be
associated with increased rates of latent TB infection. The
clinician should review the latest CDC information on TB incidence
rates and high risk populations. Additionally, silica-exposed
workers are at increased risk for contracting atypical mycobacterial
infections, including Mycobacterium avium-intracellulare and
Mycobacterium kansaii.
G. Lung Cancer. The International Agency for Research on Cancer
(IARC, 1997) classified silica as Group I (carcinogenic to humans).
Additionally, several studies have indicated that the combined
effect of exposure to respirable crystalline silica and smoking was
greater than additive (Brown, 2009).
II. Medical Surveillance
Clinicians who manage silica medical surveillance programs
should have a thorough understanding of the many silica-related
diseases and health effects outlined in Section I of this Appendix.
At each clinical encounter, the clinician should consider silica-
related health outcomes, with particular vigilance for acute and
accelerated silicosis. The following guidance includes components of
the medical surveillance examination that are required under the
Respirable Crystalline Silica standard, noted below in italics.
A. History. A complete work and medical history must be
performed on the initial examination and every three years
thereafter. Some of the information for this history must also be
provided by the employer to the clinician. A detailed history is
particularly important in the initial evaluation. Include the
following components in this history:
1. Previous and Current Employment
a. Past, current, and anticipated exposures to respirable
crystalline silica or other toxic substances
b. Exposure to dust and other agents affecting the respiratory
system
c. Past, current, and anticipated work duties relating to
exposures to respirable crystalline silica
d. Personal protective equipment used, including respirators
e. Previous medical surveillance
2. Medical History
a. All past and current medical conditions
b. Review of symptoms, with particular attention to respiratory
symptoms
c. History of TB infection and/or positive test for latent TB
d. History of other respiratory system dysfunction such as
obstructive pulmonary disease or lung cancer
e. History of kidney disease, connective tissue disease, and
other immune disease/suppression
f. Medications and allergies
g. Smoking status and history
f. Previous surgeries and hospitalizations
B. Physical Examination. A physical examination must be
performed on the initial examination and every three years
thereafter. The physical examination must emphasize the respiratory
system and should include an examination of the cardiac system and
an extremity examination for clubbing, cyanosis, or edema.
C. Tuberculosis (TB) Testing. Baseline testing for latent or
active tuberculosis must be done on initial examination. Current CDC
guidelines (www.cdc.gov) 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 clinicians. Individuals with a
positive TST result and those with uncertain test results should be
referred to a local public health specialist. Clinicians may use
alternative TB tests, such as interferon-[gamma] release assays
(IGRAs), if sensitivity and specificity are comparable to TST
(Mazurek et al, 2010). Current CDC guidelines for acceptable tests
for latent TB infection should be reviewed. Clinicians may perform
periodic (e.g., annual) TB testing as appropriate, based on
individual risk factors. The diagnosis of silicosis or exposure to
silica for 25 years or more are indications for annual TB testing
(ATS, 1997). Current CDC guidance on risk factors for TB should be
reviewed periodically (www.cdc.gov). Workers who develop active
pulmonary TB should be referred to the local public health
department. Workers who have evidence of latent TB infection may be
referred to the local public health department for evaluation and
treatment.
D. Spirometry. Spirometry must be performed on the initial
examination and every three years thereafter. Spirometry provides
information about individual respiratory status, tracks an
individual's respiratory status over time, and is a valuable
surveillance tool to track individual and group respiratory
function. However, attention should be paid to quality control
(ACOEM 2011; ATS/ERS Task Force 2005). Abnormal spirometry results
warrant further clinical evaluation and possible work restrictions
and/or treatment.
E. Radiography. A chest roentgenogram, or an equivalent
diagnostic study, must be performed on the initial examination and
every three years thereafter. Chest radiography is necessary to
diagnose silicosis, monitor the progression of silicosis, and
identify associated conditions such as TB. An International Labor
Organization (ILO) reading must be performed by a NIOSH-certified
"B" reader. If the B reading indicates small opacities in a
profusion of 1/0 or higher, the worker must be referred to a
physician who is certified by ABMS in pulmonary medicine. Medical
imaging is currently in the process of transitioning from
conventional film-based radiography to digital radiography systems.
Until the ILO endorses the use of digital standards, conventional
chest radiographs are needed for classification using the ILO
system. Current ILO guidance on radiography for pneumoconioses and
B-reading should be reviewed periodically on the ILO (www.ilo.org)
or NIOSH (www.cdc.gov/NIOSH) Web sites.
F. Other Testing. It may be appropriate to include additional
testing in a medical surveillance program such as baseline renal
function tests (e.g., serum creatinine and urinalysis) and annual
TST testing for silica-exposed workers.
III. Roles and Responsibilities
A. The Physician or other Licensed Health Care Professional
(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
is determined by each State. Those licensed for independent practice
may include physicians, nurse practitioners, or physician
assistants, depending on the State. A medical surveillance program
for workers exposed to silica should be directed by a health care
professional licensed for independent practice. Health care
professionals who provide clinical services for a silica medical
surveillance program should have a thorough knowledge of the many
silica-related diseases and health effects. Primary care
practitioners who suspect a diagnosis of silicosis, advanced COPD,
or other respiratory conditions causing impairment should promptly
refer the affected individuals to a physician who is certified by
ABMS in pulmonary medicine.
1. The PLHCP is responsible for providing the employer with a
written medical opinion within 30 days of an employee medical
examination. The written opinion must include the following
information:
a. A description of the employee's health condition as it
relates to exposure to respirable crystalline silica, including the
PLHCP's opinion as to whether the employee has any detected medical
condition(s) that would place the employee at increased risk of
material impairment to health from further exposure to respirable
crystalline silica. The employer should be notified if a health
condition likely to have been caused by recent occupational exposure
has been detected. Medical diagnoses and conditions that are not
related to silica exposure must not be disclosed to the employer.
Latent TB infection is not caused by silica exposure and must not be
disclosed to the employer. All cases of active pulmonary TB should
be referred to the Public Health Department.
b. Any recommended limitations upon the employee's exposure to
respirable crystalline silica or upon the use of personal protective
equipment such as respirators. Again, medical diagnoses not directly
related to silica exposure must not be disclosed to the employer.
Guidelines regarding ethics and confidentiality are available from
professional practice organizations such as the American College of
Occupational and Environmental Medicine.
c. A statement that the employee should be examined by a
physician who is certified by ABMS in pulmonary medicine, where such
a referral is necessary. Referral to a pulmonary specialist is
required for a chest X-ray B reading indicating small opacities in a
profusion of 1/0 or higher, or if referral to a pulmonary specialist
is otherwise deemed appropriate. A referral to the Public Health
Department should not be disclosed to the employer. If necessary, a
public health professional will contact the employer to discuss
work-related conditions and/or to perform additional medical
evaluations.
d. A statement that the clinician has explained the results of
the medical examination to the employee, 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.
2. State Reporting Requirements. Health care providers should be
aware that some States require them to report cases of silicosis to
the State Department of Health or to the State Department of the
Environment.
B. Medical Specialists. The Silica standard requires that all
workers with chest X-ray B readings of 1/0 or higher be referred to
an American Board Certified Specialist in Pulmonary Disease. The
employer must obtain a written opinion from the specialist that
includes the same required information as outlined above under
IIIA1a, b, and d. Employers should receive any information
concerning evidence of silica-related risk in their workplace (e.g.,
evidence of accelerated or acute silicosis tied to recent
exposures), so that the employer can investigate and implement
corrective measures if necessary. The employer must receive any
information about an examined employee concerning work restrictions,
including restrictions related to use of protective clothing or
equipment. Employers must not receive other medical diagnoses or
confidential health information.
C. Public Health Providers. Clinicians should refer latent and
active TB cases to their local Public Health Department. In addition
to diagnosis and treatment of individual cases, public health
providers promptly evaluate other potentially affected persons,
including coworkers. Because silica-exposed workers are at increased
risk of progression from latent to active TB, treatment of latent
infection is recommended. The diagnosis of TB, acute or accelerated
silicosis, or other silica-related diseases and infections should
serve as sentinel findings. In addition to the local and state
health departments, the National Institute of Occupational Safety
and Health (NIOSH) can provide assistance upon request through their
Health Hazard Evaluation program.
IV. Resources and References
American College of Occupational and Environmental Medicine (ACOEM),
Position Statement. Medical Surveillance of Workers Exposed to
Crystalline Silica. 06/27/2005.
ACOEM, Position Statement. Spirometry in the Occupational Health
Setting. 04/05/2010.
American Thoracic Society (ATS): Medical Section of the American
Lung Association. Adverse Effects of Crystalline Silica Exposure. Am
J Respir Crit Care Med. Vol. 155. pp 761-765, 1997.
Brown T. Silica Exposure, Smoking, Silicosis and Lung Cancer--
Complex Interactions. Occupational Medicine. 2009 59(2):89-95.
Center for Disease Control and Prevention (CDC). Guide for Primary
Health Care Providers: Targeted Tuberculin Testing and Treatment of
Latent Tuberculosis Infection. 2005.
Centers for Disease Control and Prevention. Screening for
Tuberculosis and Tuberculosis Infection in High-Risk Populations.
Recommendations of the Advisory Council for Elimination of
Tuberculosis. MMWR 1995; 44(RR-11):18-34.
International Agency for Research on Cancer (IARC) Working Group on
the Evaluation of Carcinogenic Risks to Humans. Silica, Some
Silicates, Coal Dust and Para-aramid Fibrils. Lyon, France. 1997.
Jalloul AS, Banks DE. The Health Effects of Silica Exposure. In: Rom
WN and Markowitz SB (Eds). Environmental and Occupational Medicine,
4th edition. Lippincott, Williams and Wilkins, Philadelphia. 2007.
pp.365-387.
Mazurek GH, Jereb J, Vernon A et al. Updated Guidelines for Using
Interferon Gamma Release Assays to Detect Mycobacterium tuberculosis
Infection--United States, 2010. Morbidity and Mortality Weekly
Report (MMWR), 6/25/10; 59(RR05):1-25.
Miller MR et al. Standardisation of spirometry from SERIES "ATS/ERS
TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING" Edited by V.
Brusasco, R. Crapo and G. Viegi. Eur Respir J 2005; 26:319-338.
National Institute of Occupational Safety and Health (NIOSH) B
reader Program. Access online for more information on interpretation
of X-rays for silicosis and a list of certified B-readers. http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html.
NIOSH Hazard Review: Health Effects of Occupational Exposure to
Respirable Crystalline Silica; Department of Health and Human
Services, CDC, NIOSH, April 2002.
Occupational Health Program for Exposure to Crystalline Silica in
the Industrial Sand Industry. National Industrial Sand Association,
2nd ed. 2010.
Rees D, Murray J. Silica, silicosis and tuberculosis. Int J Tuberc
Lung Dis 11(5):474-484.
Screening and Surveillance of workers exposed to mineral dust;
Gregory R. Wagner, Director, Division of Respiratory Diseases,
NIOSH, Morgantown, WV, U.S.A.; WHO, Geneva 1996.
PART 1915--OCCUPATIONAL SAFETY AND HEALTH FOR SHIPYARD EMPLOYMENT
0
5. The authority citation for 29 CFR 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. 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), or 4-2010 (75 FR 55355),
as applicable; 29 CFR part 1911.
Section 1915.120 and 1915.152 of 29 CFR also issued under 29 CFR
part 1911.
0
6. In Sec. 1915.1000, Table Z--Shipyards:
0
a. remove "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. add "Silica, crystalline, respirable dust; see 1910.1053" in
alphabetical order; and
0
c. revise the entry "SILICA:" under "Mineral Dusts", to read as
follows:
Sec. 1915.1000 Air contaminants.
* * * * *
Table Z--Shipyards
----------------------------------------------------------------------------------------------------------------
Substance CAS No.\d\ ppm \a\ * mg/m \3\ \b\ * Skin designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust; ................ ................ ................ ................
See 1910.1053..........................
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Mineral Dusts
------------------------------------------------------------------------
Substance mppcf \(j)\
------------------------------------------------------------------------
SILICA:
Amorphous, including natural diatomaceous earth... 20
------------------------------------------------------------------------
* * * * *
PART 1926--SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION
0
7. The authority citation for 29 CFR part 1926 is revised to read as
follows:
Authority: Section 3704 of the Contract Work Hours and Safety
Standards Act (40 U.S.C. 3701 et seq.); 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. 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 31159), or 4-2010 (75 FR
55355), as applicable; and 29 CFR part 1911.
0
8. In Appendix A to Sec. 1926.55:
0
a. Remove "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. add "Silica, crystalline, respirable dust; see 1926.1053" in
alphabetical order; and
0
c. revise the entry "SILICA:" under "Mineral Dusts", to 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
----------------------------------------------------------------------------------------------------------------
Substance CAS No.\d\ ppm \a\ mg/m\3 b\ Skin designation
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Silica, crystalline, respirable dust; ................ ................ ................ ................
see 1926.1053..........................
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Mineral Dusts
------------------------------------------------------------------------
Substance mppcf \(j)\
------------------------------------------------------------------------
SILICA:
Amorphous, including natural diatomaceous earth... 20
------------------------------------------------------------------------
* * * * *
0
9. Add a new Sec. 1926.1053, to read as follows:
Sec. 1926.1053 Respirable crystalline silica.
(a) Scope and application. (1) This section applies to all
occupational exposures to respirable crystalline silica in construction
work as defined in 29 CFR 1910.12(b) and covered under 29 CFR part
1926.
(b) Definitions. For the purposes of this section the following
definitions apply:
Action level means a concentration of airborne respirable
crystalline silica of 25 micrograms per cubic meter of air (25 [mu]g/
m\3\), calculated as an 8-hour time-weighted average (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 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.
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 or
chemical and physical properties of a substance demonstrating employee
exposure to respirable crystalline silica associated with a particular
product or material or a specific process, operation, or activity. The
data must reflect workplace conditions closely resembling 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.
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 airborne particles that contain
quartz, cristobalite, and/or tridymite and whose measurement is
determined 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.
This section means this respirable crystalline silica standard, 29
CFR 1926.1053.
(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. (i) Except as provided for in
paragraph (d)(8) of this section, each employer covered by this section
shall assess the exposure of employees who are or may reasonably be
expected to be exposed to respirable crystalline silica at or above the
action level.
(ii) The employer shall determine employee exposures from breathing
zone air samples that reflect the 8-hour TWA exposure of each employee.
(iii) The employer shall determine 8-hour TWA exposures on the
basis of one or more 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 shall sample the
employee(s) who are expected to have the highest exposure to respirable
crystalline silica.
(2) Initial exposure assessment. (i) Except as provided for in
paragraph (d)(2)(ii) of this section, each employer shall perform
initial monitoring of employees who are, or may reasonably be expected
to be, exposed to airborne concentrations of respirable crystalline
silica at or above the action level.
(ii) The employer may rely on existing data to satisfy this initial
monitoring requirement where the employer:
(A) Has monitored employee exposures after [INSERT DATE 12 MONTHS
PRIOR TO EFFECTIVE DATE OF FINAL RULE] under conditions that closely
resemble those currently prevailing, provided that such monitoring
satisfies the requirements of paragraph (d)(5)(i) of this section with
respect to analytical methods employed; or
(B) Has objective data that demonstrate that respirable crystalline
silica is not capable of being released in airborne concentrations at
or above the action level under any expected conditions of processing,
use, or handling.
(3) Periodic exposure assessments. 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. If initial monitoring indicates that
employee exposures are at or above the action level, the employer shall
repeat air monitoring to assess employee exposures to respirable
crystalline silica either under the fixed schedule prescribed in
paragraph (d)(3)(i) of this section or in accordance with the
performance-based requirement prescribed in paragraph (d)(3)(ii) of
this section.
(i) Fixed schedule option. (A) Where 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.
(B) Where initial or subsequent exposure monitoring reveals that
employee exposures are above the PEL, the employer shall repeat such
monitoring at least every three months.
(C) 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 for that employee, except as otherwise provided
in paragraph (d)(4) 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.
(4) Additional exposure assessments. The employer shall conduct
additional exposure assessments as required under paragraph (d)(3) of
this section 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.
(5) Method of sample analysis. (i) The employer shall ensure that
all samples taken to satisfy the monitoring requirements of paragraph
(d) of this section are 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.
(ii) The employer shall ensure that samples are analyzed by a
laboratory that:
(A) 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;
(B) Participates in round robin testing with at least two other
independent laboratories at least every six months;
(C) Uses the most current National Institute of Standards and
Technology (NIST) or NIST traceable standards for instrument
calibration or instrument calibration verification;
(D) Implements an internal quality control (QC) program that
evaluates analytical uncertainty and provides employers with estimates
of sampling and analytical error;
(E) 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;
(F) 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:
(1) Each day that samples are analyzed, performs instrument
calibration checks with standards that bracket the sample
concentrations;
(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
(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.
(6) Employee notification of assessment results. (i) Within five
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 the 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, 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.
(8) Specific operations. (i) Where employees perform operations
listed in Table 1 in paragraph (f) of this section and the employer has
fully implemented the engineering controls, work practices, and
respiratory protection specified in Table 1 for that operation, the
employer is not required to assess the exposure of employees performing
such operations.
(ii) For the purposes of complying with all other requirements of
this section, the employer must presume that each employee performing
an operation listed in Table 1 that requires a respirator is exposed
above the PEL, unless the employer can demonstrate otherwise in
accordance with the exposure assessment requirements of paragraph (d)
of this section.
(e) Regulated areas and access control. (1) General. 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, each employer shall establish and implement either a
regulated area in accordance with paragraph (e)(2) of this section or
an access control plan in accordance with paragraph (e)(3) of this
section.
(2) Regulated areas option. (i) 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.
(ii) Demarcation. The employer shall demarcate regulated areas from
the rest of the workplace in any manner that
adequately establishes and alerts employees to the boundaries of the
area and minimizes the number of employees exposed to respirable
crystalline silica within the regulated area.
(iii) 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.
(iv) 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.
(v) Protective work clothing in regulated areas. (A) Where there is
the potential for employees' work clothing to become grossly
contaminated with finely divided material containing crystalline
silica, the employer shall provide either of the following:
(1) Appropriate protective clothing such as coveralls or similar
full-bodied clothing; or
(2) Any other means to remove excessive silica dust from
contaminated clothing that minimizes employee exposure to respirable
crystalline silica.
(B) The employer shall ensure that such clothing is removed or
cleaned upon exiting the regulated area and before respiratory
protection is removed.
(3) Written access control plan option. (i) The employer shall
establish and implement a written access control plan.
(ii) The written access control plan shall contain at least the
following elements:
(A) Provisions for a competent person to identify the presence and
location of any areas where respirable crystalline silica exposures
are, or can reasonably be expected to be, in excess of the PEL;
(B) Procedures for notifying employees of the presence and location
of areas identified pursuant to paragraph (e)(3)(ii)(A) of this
section, and for demarcating such areas from the rest of the workplace
where appropriate;
(C) For multi-employer workplaces, the methods the employer covered
by this section will use to inform other employer(s) of the presence
and location of areas where respirable crystalline silica exposures may
exceed the PEL, and any precautionary measures that need to be taken to
protect employees;
(D) Provisions for limiting access to areas where respirable
crystalline silica exposures may exceed the PEL to effectively minimize
the number of employees exposed and the level of employee exposure;
(E) Procedures for providing each employee and their designated
representative entering an area where respirable crystalline silica
exposures may exceed the PEL with an appropriate respirator in
accordance with paragraph (g) of this section, and requiring each
employee and their designated representative to use the respirator
while in the area; and
(F) Where there is the potential for employees' work clothing to
become grossly contaminated with finely divided material containing
crystalline silica:
(1) Provisions for the employer to provide either appropriate
protective clothing such as coveralls or similar full-bodied clothing,
or any other means to remove excessive silica dust from contaminated
clothing that minimizes employee exposure to respirable crystalline
silica; and
(2) Provisions for the removal or cleaning of such clothing.
(iii) The employer shall review and evaluate the effectiveness of
the written access control plan at least annually and update it as
necessary.
(iv) The employer shall make the written access control plan
available for examination and copying, upon request, to employees,
their designated representatives, the Assistant Secretary and the
Director.
(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) Specific operations. For the operations listed in Table 1, if
the employer fully implements the engineering controls, work practices,
and respiratory protection described in Table 1, the employer shall be
considered to be in compliance with paragraph (f)(1) of this section.
(NOTE: The employer must comply with all other obligations of this
section, including the PEL specified in paragraph (c) of this section.)
Table 1--Exposure Control Methods for Selected Construction Operations
----------------------------------------------------------------------------------------------------------------
Required air-purifying respirator (minimum
Engineering and work assigned protection factor)
Operation practice control methods -----------------------------------------------
<= 4 hr/day > 4 hr/day
----------------------------------------------------------------------------------------------------------------
Using Stationary Masonry Saws...... Use saw equipped with None.................. Half-Mask (10).
integrated water delivery
system.
Note: Additional
specifications:.
Change water
frequently to avoid silt
build-up in water.
Prevent wet slurry
from accumulating and
drying.
Operate equipment
such that no visible dust
is emitted from the
process.
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust..
Ensure saw blade
is not excessively worn.
----------------------------------------------------------------------------------------------------------------
Using Hand-Operated Grinders....... Use water-fed grinder that None.................. Half-Mask (10).
continuously feeds water
to the cutting surface.
OR.........................
Use grinder equipped with Half-Mask (10)........ Half-Mask (10).
commercially available
shroud and dust collection
system, operated and
maintained to minimize
dust emissions. Collector
must be equipped with a
HEPA filter and must
operate at 25 cubic feet
per minute (cfm) or
greater airflow per inch
of blade diameter.
Note: Additional
specifications (wherever
applicable):
Prevent wet slurry
from accumulating and
drying..
Operate equipment
such that no visible dust
is emitted from the
process..
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust..
----------------------------------------------------------------------------------------------------------------
Tuckpointing....................... Use grinder equipped with Powered air-purifying Powered air-purifying
commercially available respirator (PAPR) respirator (PAPR)
shroud and dust collection with loose-fitting with loose-fitting
system. Grinder must be helmet or negative helmet or negative
operated flush against the pressure full pressure full
working surface and work facepiece (25). facepiece (25).
must be performed against
the natural rotation of
the blade (i.e., mortar
debris must be directed
into the exhaust). Use
vacuums that provide at
least 80 cfm airflow
through the shroud and
include filters at least
99 percent efficient.
Note: Additional
specifications:.
Operate equipment
such that no visible dust
is emitted from the
process..
When working in
enclosed spaces, provide
sufficient ventilation to
prevent build-up of
visible airborne dust.
----------------------------------------------------------------------------------------------------------------
Using Jackhammers and Other Impact Apply a continuous stream None.................. Half-Mask (10).
Drillers. or spray of water at the
point of impact.
OR.........................
Use tool-mounted shroud and None.................. Half-Mask (10).
HEPA-filtered dust
collection system.
Note: Additional
specifications:
Operate equipment
such that no visible dust
is emitted from the
process..
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust..
----------------------------------------------------------------------------------------------------------------
Using Rotary Hammers or Drills Use drill equipped with None.................. None.
(except overhead). hood or cowl and HEPA-
filtered dust collector.
Eliminate blowing or dry
sweeping drilling debris
from working surface.
Note: Additional
specifications:.
Operate equipment
such that no visible dust
is emitted from the
process.
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust.
Use dust collector
in accordance with
manufacturer
specifications.
----------------------------------------------------------------------------------------------------------------
Operating Vehicle-Mounted Drilling Use dust collection system None.................. None.
Rigs for Rock. around drill bit and
provide a low-flow water
spray to wet the dust
discharged from the dust
collector.
Note: Additional
specifications:
Operate equipment
such that no visible dust
is emitted from the
process.
Half-mask
respirator is to be used
when working under the
shroud.
Use dust collector
in accordance with
manufacturer
specifications.
For equipment operator None.................. None.
working within an enclosed
cab having the following
characteristics:
Cab is air
conditioned and positive
pressure is maintained.
Incoming air is
filtered through a
prefilter and HEPA filter.
Cab is maintained
as free as practicable
from settled dust.
Door seals and
closing mechanisms are
working properly.
----------------------------------------------------------------------------------------------------------------
Operating Vehicle-Mounted Drilling Use dust collection system None.................. Half-Mask (10).
Rigs for Concrete. around drill bit and
provide a low-flow water
spray to wet the dust
discharged from the dust
collector.
Note: Additional
specifications:.
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.
Operate equipment
such that no visible dust
is emitted from the
process.
Use dust collector
in accordance with
manufacturer
specifications.
For equipment operator None.................. None.
working within an enclosed
cab having the following
characteristics:
Cab is air
conditioned and positive
pressure is maintained..
Incoming air is
filtered through a
prefilter and HEPA filter.
Cab is maintained
as free as practicable
from settled dust.
Door seals and
closing mechanisms are
working properly.
----------------------------------------------------------------------------------------------------------------
Milling For drivable milling
machines:.
Use water-fed system None.................. Half-Mask (10).
that delivers water
continuously at the cut
point to suppress dust.
Note: Additional
specifications:
Operate equipment
such that no visible dust
is emitted from the drum
box and conveyor areas.
For walk-behind milling
tools:
Use water-fed equipment None.................. Half-Mask (10).
that continuously feeds
water to the cutting
surface.
OR......................
Use tool equipped with None.................. Half-Mask (10).
commercially available
shroud and dust
collection system.
Collector must be
equipped with a HEPA
filter and must operate
at an adequate airflow
to minimize airborne
visible dust.
Note: Additional
specifications:
Use dust collector
in accordance with
manufacturer
specifications including
airflow rate.
----------------------------------------------------------------------------------------------------------------
Using Handheld Masonry Saws........ Use water-fed system that
delivers water
continuously at the cut
point.
Used outdoors........... None.................. Half-Mask (10).
Used indoors or within Half-Mask (10)........ Half-Mask (10).
partially sheltered
area.
OR
Use saw equipped with local
exhaust dust collection
system.
Used outdoors........... Half-Mask (10)........ Half-Mask (10).
Used indoors or within Full Facepiece (50)... Full Facepiece (50).
partially sheltered
area.
Note: Additional
specifications:
Prevent wet slurry
from accumulating and
drying.
Operate equipment
such that no visible dust
is emitted from the
process..
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust..
Use dust collector
in accordance with
manufacturer
specifications..
----------------------------------------------------------------------------------------------------------------
Using Portable Walk-Behind or Use water-fed system that
Drivable Masonry Saws. delivers water
continuously at the cut
point.
Used outdoors........... None.................. None.
Used indoors or within Half-Mask (10)........ Half-Mask (10).
partially sheltered
area.
Note: Additional
specifications:
Prevent wet slurry
from accumulating and
drying.
Operate equipment
such that no visible dust
is emitted from the
process.
When working
indoors, provide
sufficient ventilation to
prevent build-up of
visible airborne dust.
----------------------------------------------------------------------------------------------------------------
Rock Crushing...................... Use wet methods or dust Half-Mask (10)........ Half-Mask (10).
suppressants.
OR.........................
Use local exhaust Half-Mask (10)........ Half-Mask (10).
ventilation systems at
feed hoppers and along
conveyor belts.
Note: Additional
specifications:
Operate equipment
such that no visible dust
is emitted from the
process.
For equipment operator None.................. None.
working within an enclosed
cab having the following
characteristics:
Cab is air
conditioned and positive
pressure is maintained;
Incoming air is
filtered through a
prefilter and HEPA filter;
Cab is maintained
as free as practicable
from settled dust; and
Door seals and
closing mechanisms are
working properly.
----------------------------------------------------------------------------------------------------------------
Drywall Finishing (with silica- Use pole sander or hand None.................. None.
containing material). sander equipped with a
dust collection system.
Use dust collector in
accordance with
manufacturer
specifications.
OR.........................
Use wet methods to smooth None.................. None.
or sand the drywall seam.
----------------------------------------------------------------------------------------------------------------
Use of Heavy Equipment During Operate equipment from None.................. None.
Earthmoving. within an enclosed cab
having the following
characteristics:
Cab is air
conditioned and positive
pressure is maintained;.
Incoming air is
filtered through a
prefilter and HEPA filter;.
Cab is maintained
as free as practicable
from settled dust; and.
Door seals and
closing mechanisms are
working properly..
----------------------------------------------------------------------------------------------------------------
Note 1: For the purposes of complying with all other requirements of this section, the employer must presume
that each employee performing an operation listed in Table 1 that requires a respirator is exposed above the
PEL.
Note 2: Where an employee performs more than one operation during the course of a day, and the total duration of
all operations combined is > 4 hr/day, the required air-purifying respirator for each operation is the
respirator specified for > 4 hr/day. If the total duration of all operations combined is <= 4 hr/day, the
required air-purifying respirator for each operation is the respirator specified for <= 4 hr/day.
(3) Abrasive blasting. In addition to the requirements of paragraph
(f)(1) of this section, the employer shall comply with the requirements
of 29 CFR 1926.57 (Ventilation) where abrasive blasting operations are
conducted using crystalline silica-containing blasting agents, or where
abrasive blasting operations are conducted on substrates that contain
crystalline silica.
(4) Cleaning methods. (i) The employer shall ensure that
accumulations of crystalline silica are cleaned by HEPA-filter
vacuuming or wet methods where such accumulations could, if disturbed,
contribute to employee exposure to respirable crystalline silica that
exceeds the PEL.
(ii) 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.
(5) Prohibition of rotation. The employer shall not rotate
employees to different jobs to achieve compliance with the PEL.
(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 work operations for
which engineering and work practice controls are not feasible;
(iii) During work operations 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;
(iv) During periods when the employee is in a regulated area; and
(v) During periods when the employee is in an area where respirator
use is required under an access control plan pursuant to paragraph
(e)(3) of this section.
(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) Specific operations. For the operations listed in Table 1 in
paragraph (f) of this section, if the employer fully implements the
engineering controls, work practices, and respiratory protection
described in Table 1, the employer shall be considered to be in
compliance with the requirements for selection of respirators in 29 CFR
1910.134 paragraph (d).
(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 occupationally
exposed to respirable crystalline silica above the PEL 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 (posterior/anterior view; no less than 14 x 17
inches and no more than 16 x 17 inches at full inspiration),
interpreted and classified according to the International Labour
Organization (ILO) International Classification of Radiographs of
Pneumoconioses by a NIOSH-certified "B" reader, or an equivalent
diagnostic study;
(iv) A pulmonary function test to include forced vital capacity
(FVC) and forced expiratory volume at one second (FEV1) and
FEV1/FVC ratio, administered by a spirometry technician with
current certification 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) (except paragraph (h)(2)(v)) of this section 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 affected 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 that equipment; and
(iv) Information from records of employment-related medical
examinations previously provided to the affected employee and currently
within the control of the employer.
(5) PLHCP's written medical opinion. (i) The employer shall obtain
a written medical opinion from the PLHCP within 30 days of each medical
examination performed on each employee. The written opinion shall
contain:
(A) A description of the employee's health condition as it relates
to exposure to respirable crystalline silica, including the PLHCP's
opinion as to whether the employee has any detected medical
condition(s) that would place the employee at increased risk of
material impairment to health from exposure to respirable crystalline
silica;
(B) Any recommended limitations upon the employee's exposure to
respirable crystalline silica or upon the use of personal protective
equipment such as respirators;
(C) A statement that the employee should be examined by an American
Board Certified Specialist in Pulmonary Disease ("pulmonary
specialist") pursuant to paragraph (h)(6) 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 pulmonary specialist is
otherwise deemed appropriate by the PLHCP; and
(D) A statement that the PLHCP has 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.
(ii) The employer shall ensure that the PLHCP does not reveal to
the employer specific findings or diagnoses unrelated to occupational
exposure to respirable crystalline silica.
(iii) The employer shall provide a copy of the PLHCP's written
medical opinion to the examined employee within two weeks after
receiving it.
(6) Additional examinations. (i) If the PLHCP's written medical
opinion indicates that an employee should be examined by a pulmonary
specialist, the employer shall make available a medical examination by
a pulmonary specialist within 30 days after receiving the PLHCP's
written medical opinion.
(ii) The employer shall ensure that the examining pulmonary
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 obtain a written medical opinion from the
pulmonary specialist that meets the requirements of paragraph (h)(5)
(except paragraph (h)(5)(i)(C)) 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 affected employee can demonstrate knowledge of at
least the following:
(A) Specific operations in the workplace that could result in
exposure to respirable crystalline silica, especially operations where exposure may exceed the PEL;
(B) Specific procedures the employer has implemented to protect
employees from exposure to respirable crystalline silica, including
appropriate work practices and use of personal protective equipment
such as respirators and protective clothing;
(C) The contents of this section; and
(D) 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 affected employee.
(j) Recordkeeping. (1) Air monitoring data. (i) The employer shall
maintain an accurate record of all exposure measurement results used or
relied on to characterize 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 operation 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 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, operation, or activity and how
the data support the assessment; and
(E) Other data relevant to the process, operation, activity,
material, or employee exposures.
(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 establish 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 PLHCP's and pulmonary specialist's written
opinions; and
(C) A copy of the information provided to the PLHCPs and pulmonary
specialists as required by paragraph (h)(4) of this section.
(iii) The employer shall ensure that medical records are maintained
and made available in accordance with 29 CFR 1910.1020.
(k) Dates. (1) Effective date. This section shall become effective
[INSERT DATE 60 DAYS AFTER PUBLICATION OF FINAL RULE IN THE Federal
Register].
(2) Start-up dates. (i) All obligations of this section, except
engineering controls required by paragraph (f) of this section and
laboratory requirements in paragraph (d)(5)(ii) of this section,
commence 180 days after the effective date.
(ii) Engineering controls required by paragraph (f) of this section
shall be implemented no later than one year after the effective date.
(iii) Laboratory requirements in paragraph (d)(5)(ii) of this
section commence two years after the effective date.
Appendix A to Sec. 1926.1053--Medical Surveillance Guidelines (Non-
Mandatory) Introduction
The purpose of this non-mandatory Appendix is to provide helpful
information about complying with the medical surveillance provisions
of the Respirable Crystalline Silica standard, as well as to provide
other helpful recommendations and information. Medical screening and
surveillance allow for early identification of exposure-related
health effects in individual workers and groups of workers,
respectively, so that actions can be taken to both avoid further
exposure and prevent adverse health outcomes. Silica-related
diseases can be fatal, encompass a variety of target organs, and may
have public health consequences. Thus, medical surveillance of
silica-exposed workers requires involvement of clinicians with
thorough knowledge of silica-related health effects and a public
health perspective.
This Appendix is divided into four sections. Section I reviews
silica-related diseases, appropriate medical responses, and public
health responses. Section II outlines the components of the medical
surveillance program for workers exposed to silica. Section III
describes the roles and responsibilities of the clinician
implementing the program and of other medical specialists and public
health providers. Section IV provides additional resources.
I. Recognition of Silica-Related Diseases
Overview. 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 a number of
adverse health effects. Exposure to respirable crystalline silica
can occur in foundries, industries that have 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
tuckpointing.
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.
A. 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 as follows:
1. Symptoms--Shortness of breath and cough, although workers 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
mycobacterium tuberculosis infection (TB) or lung cancer. Workers
with these symptoms should immediately receive further evaluation
and treatment.
2. Physical Examination--may be normal or disclose dry rales or
rhonchi on lung auscultation.
3. Spirometry--may be normal or may show only mild restriction
or obstruction.
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" are seen.
5. Clinical Course--chronic silicosis in most cases is a slowly
progressive disease.
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. Additionally, a case of acute or
accelerated silicosis indicates a significant breakdown in
prevention. Urgent communication with the employer is warranted to
review exposure levels and protect other workers.
B. Accelerated Silicosis. Accelerated silicosis occurs within 2-
10 years of exposure and results from high levels of exposure to
respirable crystalline silica. The clinical presentation of accelerated silicosis is as follows:
1. Symptoms--shortness of breath, cough, and sometimes sputum
production. Workers with accelerated silicosis are at high risk of
tuberculosis, atypical mycobacterial infections, and fungal
superinfections. Constitutional symptoms, such as fever, weight
loss, hemoptysis, and fatigue, may herald one of these infections or
the onset of lung cancer.
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
disease.
3. Spirometry--restriction or mixed restriction/obstruction.
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.
5. Clinical Course--accelerated silicosis has a rapid, severe
course. Referral to a physician who is American Board of Medical
Specialties (ABMS)-Certified in Pulmonary Medicine should be made
whenever the diagnosis of accelerated silicosis is being considered.
Referral to the appropriate specialist should be made if signs or
symptoms of tuberculosis, other silica-related infections, or lung
cancer are observed. As noted above, the clinician should also alert
the employer of the need for immediate review of exposure controls
in the worksite in order to protect other workers.
C. Acute Silicosis. Acute silicosis is a rare disease caused by
inhalation of very 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, 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. Symptoms--sudden, progressive, and severe shortness of
breath. Constitutional symptoms are frequently present and include
weight loss, fatigue, productive cough, hemoptysis, and pleuritic
chest pain.
2. Physical Examination--dyspnea at rest, cyanosis, decreased
breath sounds, inspiratory rales, clubbing of the digits, and fever.
3. Spirometry--restriction or mixed restriction/obstruction.
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.
5. Clinical Course--workers with acute silicosis are at high
risk of tuberculosis, atypical myco-baterial infections, and fungal
superinfections. Because this disease is immediately life-
threatening and indicates a profoundly high level of exposure, it
constitutes an immediate medical and public health emergency. The
worker must be urgently referred to a physician ABMS-certified in
Pulmonary Medicine. As noted above, the clinician should also alert
the employer of the need for immediate exposure controls in the
worksite in order to protect other workers.
During medical surveillance examinations, clinicians should be
alert for other silica-related health outcomes as described below.
D. Chronic Obstructive Pulmonary Disease (COPD). COPD, including
chronic bronchitis and emphysema, has also been documented in
silica-exposed workers, including those who do not develop
silicosis. Periodic spirometry tests are performed to evaluate each
worker for progressive changes consistent with the development of
COPD. Additionally, collective spirometry data for groups of workers
should be evaluated for declines in lung function, thereby providing
a mechanism to detect insufficient silica control measures for
groups of workers.
E. 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. Early studies noted an
association between workers with silicosis and serologic markers for
autoimmune diseases, including antinuclear antibodies, rheumatoid
factor, and immune complexes (Jalloul and Banks, 2007).
F. Tuberculosis (TB). Silica-exposed workers with latent TB are
3-30 times more likely to develop active pulmonary TB infection
(ATS, 1997; Rees, 2007). Although 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 silica
exposure, greater profusion of radiographic abnormalities, or a
diagnosis of silicosis. Demographic characteristics are known to be
associated with increased rates of latent TB infection. The
clinician should review the latest CDC information on TB incidence
rates and high risk populations. Additionally, silica-exposed
workers are at increased risk for contracting atypical mycobacterial
infections, including Mycobacterium avium-intracellulare and
Mycobacterium kansaii.
G. Lung Cancer. The International Agency for Research on Cancer
(IARC, 1997) classified silica as Group I (carcinogenic to humans).
Additionally, several studies have indicated that the combined
effect of exposure to respirable crystalline silica and smoking was
greater than additive (Brown, 2009).
II. Medical Surveillance
Clinicians who manage silica medical surveillance programs
should have a thorough understanding of the many silica-related
diseases and health effects outlined in Section I of this Appendix.
At each clinical encounter, the clinician should consider silica-
related health outcomes, with particular vigilance for acute and
accelerated silicosis. The following guidance includes components of
the medical surveillance examination that are required under the
Respirable Crystalline Silica standard, noted below in italics.
A. History. A complete work and medical history must be
performed on the initial examination and every three years
thereafter. Some of the information for this history must also be
provided by the employer to the clinician. A detailed history is
particularly important in the initial evaluation. Include the
following components in this history:
1. Previous and Current Employment
a. Past, current, and anticipated exposures to respirable
crystalline silica or other toxic substances
b. Exposure to dust and other agents affecting the respiratory
system
c. Past, current, and anticipated work duties relating to
exposures to respirable crystalline silica
d. Personal protective equipment used, including respirators
e. Previous medical surveillance
2. Medical History
a. All past and current medical conditions
b. Review of symptoms, with particular attention to respiratory
symptoms
c. History of TB infection and/or positive test for latent TB
d. History of other respiratory system dysfunction such as
obstructive pulmonary disease or lung cancer
e. History of kidney disease, connective tissue disease, and
other immune disease/suppression
f. Medications and allergies
g. Smoking status and history
f. Previous surgeries and hospitalizations
B. Physical Examination. A physical examination must be
performed on the initial examination and every three years
thereafter. The physical examination must emphasize the respiratory
system and should include an examination of the cardiac system and
an extremity examination for clubbing, cyanosis, or edema.
C. Tuberculosis (TB) Testing. Baseline testing for latent or
active tuberculosis must be done on initial examination. Current CDC
guidelines (www.cdc.gov) 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 clinicians. Individuals with a
positive TST result and those with uncertain test results should be
referred to a local public health specialist. Clinicians may use
alternative TB tests, such as interferon-[gamma] release assays
(IGRAs), if sensitivity and specificity are comparable to TST
(Mazurek et al, 2010). Current CDC guidelines for acceptable tests
for latent TB infection should be reviewed. Clinicians may perform
periodic (e.g., annual) TB testing as appropriate, based on
individual risk factors. The diagnosis of silicosis or exposure to
silica for 25 years or more are indications for annual TB testing
(ATS, 1997). Current CDC guidance on risk factors for TB should be
reviewed periodically (www.cdc.gov). Workers who develop active
pulmonary TB should be referred to the local public health
department. Workers who have evidence of latent TB infection may be
referred to the local public health department for evaluation and
treatment.
D. Spirometry. Spirometry must be performed on the initial
examination and every three years thereafter. Spirometry provides
information about individual
respiratory status, tracks an individual's respiratory status over
time, and is a valuable surveillance tool to track individual and
group respiratory function. However, attention should be paid to
quality control (ACOEM 2011; ATS/ERS Task Force 2005). Abnormal
spirometry results warrant further clinical evaluation and possible
work restrictions and/or treatment.
E. Radiography. A chest roentgenogram, or an equivalent
diagnostic study, must be performed on the initial examination and
every three years thereafter. Chest radiography is necessary to
diagnose silicosis, monitor the progression of silicosis, and
identify associated conditions such as TB. An International Labor
Organization (ILO) reading must be performed by a NIOSH-certified
"B" reader. If the B reading indicates small opacities in a
profusion of 1/0 or higher, the worker must be referred to a
physician who is certified by ABMS in pulmonary medicine. Medical
imaging is currently in the process of transitioning from
conventional film-based radiography to digital radiography systems.
Until the ILO endorses the use of digital standards, conventional
chest radiographs are needed for classification using the ILO
system. Current ILO guidance on radiography for pneumoconioses and
B-reading should be reviewed periodically on the ILO (www.ilo.org)
or NIOSH (www.cdc.gov/NIOSH) Web sites.
F. Other Testing. It may be appropriate to include additional
testing in a medical surveillance program such as baseline renal
function tests (e.g., serum creatinine and urinalysis) and annual
TST testing for silica-exposed workers.
III. Roles and Responsibilities
A. The Physician or other Licensed Health Care Professional
(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
is determined by each State. Those licensed for independent practice
may include physicians, nurse practitioners, or physician
assistants, depending on the State. A medical surveillance program
for workers exposed to silica should be directed by a health care
professional licensed for independent practice. Health care
professionals who provide clinical services for a silica medical
surveillance program should have a thorough knowledge of the many
silica-related diseases and health effects. Primary care
practitioners who suspect a diagnosis of silicosis, advanced COPD,
or other respiratory conditions causing impairment should promptly
refer the affected individuals to a physician who is certified by
ABMS in pulmonary medicine.
1. The PLHCP is responsible for providing the employer with a
written medical opinion within 30 days of an employee medical
examination. The written opinion must include the following
information:
a. A description of the employee's health condition as it
relates to exposure to respirable crystalline silica, including the
PLHCP's opinion as to whether the employee has any detected medical
condition(s) that would place the employee at increased risk of
material impairment to health from further exposure to respirable
crystalline silica. The employer should be notified if a health
condition likely to have been caused by recent occupational exposure
has been detected. Medical diagnoses and conditions that are not
related to silica exposure must not be disclosed to the employer.
Latent TB infection is not caused by silica exposure and must not be
disclosed to the employer. All cases of active pulmonary TB should
be referred to the Public Health Department.
b. Any recommended limitations upon the employee's exposure to
respirable crystalline silica or upon the use of personal protective
equipment such as respirators. Again, medical diagnoses not directly
related to silica exposure must not be disclosed to the employer.
Guidelines regarding ethics and confidentiality are available from
professional practice organizations such as the American College of
Occupational and Environmental Medicine.
c. A statement that the employee should be examined by a
physician who is certified by ABMS in pulmonary medicine, where such
a referral is necessary. Referral to a pulmonary specialist is
required for a chest X-ray B reading indicating small opacities in a
profusion of 1/0 or higher, or if referral to a pulmonary specialist
is otherwise deemed appropriate. A referral to the Public Health
Department should not be disclosed to the employer. If necessary, a
public health professional will contact the employer to discuss
work-related conditions and/or to perform additional medical
evaluations.
d. A statement that the clinician has explained the results of
the medical examination to the employee, 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.
2. State Reporting Requirements. Health care providers should be
aware that some States require them to report cases of silicosis to
the State Department of Health or to the State Department of the
Environment.
B. Medical Specialists. The Silica standard requires that all
workers with chest X-ray B readings of 1/0 or higher be referred to
an American Board Certified Specialist in Pulmonary Disease. The
employer must obtain a written opinion from the specialist that
includes the same required information as outlined above under
IIIA1a, b, and d. Employers should receive any information
concerning evidence of silica-related risk in their workplace (e.g.,
evidence of accelerated or acute silicosis tied to recent
exposures), so that the employer can investigate and implement
corrective measures if necessary. The employer must receive any
information about an examined employee concerning work restrictions,
including restrictions related to use of protective clothing or
equipment. Employers must not receive other medical diagnoses or
confidential health information.
C. Public Health Providers. Clinicians should refer latent and
active TB cases to their local Public Health Department. In addition
to diagnosis and treatment of individual cases, public health
providers promptly evaluate other potentially affected persons,
including coworkers. Because silica-exposed workers are at increased
risk of progression from latent to active TB, treatment of latent
infection is recommended. The diagnosis of TB, acute or accelerated
silicosis, or other silica-related diseases and infections should
serve as sentinel findings. In addition to the local and state
health departments, the National Institute of Occupational Safety
and Health (NIOSH) can provide assistance upon request through their
Health Hazard Evaluation program.
IV. Resources and References
American College of Occupational and Environmental Medicine (ACOEM),
Position Statement. Medical Surveillance of Workers Exposed to
Crystalline Silica. 06/27/2005.
ACOEM, Position Statement. Spirometry in the Occupational Health
Setting. 04/05/2011.
American Thoracic Society (ATS): Medical Section of the American
Lung Association. Adverse Effects of Crystalline Silica Exposure. Am
J Respir Crit Care Med Vol 155. pp 761-765, 1997.
Brown T. Silica Exposure, Smoking, Silicosis and Lung Cancer--
Complex Interactions. Occupational Medicine. 2009 59(2):89-95.
Center for Disease Control and Prevention (CDC). Guide for Primary
Health Care Providers: Targeted Tuberculin Testing and Treatment of
Latent Tuberculosis Infection. 2005.
Centers for Disease Control and Prevention. Screening for
Tuberculosis and Tuberculosis Infection in High-Risk Populations.
Recommendations of the Advisory Council for Elimination of
Tuberculosis. MMWR 1995; 44(RR-11): 18-34.
International Agency for Research on Cancer (IARC) Working Group on
the Evaluation of Carcinogenic Risks to Humans. Silica, Some
Silicates, Coal Dust and Para-aramid Fibrils. Lyon, France. 1997.
Jalloul AS, Banks DE. The Health Effects of Silica Exposure. In: Rom
WN and Markowitz SB (Eds). Environmental and Occupational Medicine,
4th edition. Lippincott, Williams and Wilkins, Philadelphia. 2007.
pp 365-387.
Mazurek GH, Jereb J, Vernon A et al. Updated Guidelines for Using
Interferon Gamma Release Assays to Detect Mycobacterium tuberculosis
Infection--United States, 2010. Morbidity and Mortality Weekly
Report (MMWR), 6/25/10; 59(RR05):1-25.
Miller MR et al, Standardisation of spirometry from SERIES "ATS/ERS
TASK FORCE: STANDARDISATION OF LUNG FUNCTION TESTING" Edited by V
Brusasco, R Crapo and G Viegi. Eur Respir J 2005; 26:319-338.
National Institute of Occupational Safety and Health (NIOSH) B
reader Program. Access online for more information on interpretation
of X-rays for silicosis and a list of certified B-readers.
http://www.cdc.gov/niosh/topics/chestradiography/breader-info.html
NIOSH Hazard Review: Health Effects of Occupational Exposure to
Respirable Crystalline Silica; Department of Health and Human
Services, CDC, NIOSH, April 2002.
Occupational Health Program for Exposure to Crystalline Silica in
the Industrial Sand Industry. National Industrial Sand Association,
2nd ed. 2010.
Rees D, Murray J. Silica, silicosis and tuberculosis. Int J Tuberc
Lung Dis 11(5):474-484.
Screening and Surveillance of workers exposed to mineral dust;
Gregory R Wagner, Director, Division of Respiratory Diseases, NIOSH,
Morgantown, WV, U.S.A.; WHO, Geneva 1996.
[FR Doc. 2013-20997 Filed 9-11-13; 8:45 a.m.]
BILLING CODE 4510-26-P
