1. OSHA Publication 3123, "Ergonomics Program Management Guidelines For Meatpacking Plants", 1991.

2. Cumulative Trauma disorders: A Manual For Musculoskeletal Disease of the Upper Limbs. Edited by Vern Putz-Anderson, Taylor and Francis, 1988.

3. Bureau of Labor Statistics, Log and Summary of Occupational Illnesses and Injuries, OSHA Form 200.

4. OSHA Instruction CPL 2.78, "Regional Ergonomics Program", 1987.

5. OSHA Fact Sheet Number 89-09, "Back Injuries-Nation's Number One Workplace Safety Problem."

6. The NIOSH "Work Practices Guide for Manual Lifting" (NTS PB 821-789-48), 1981.

7. OSHA Instruction CPL 2-2.20B: OSHA Technical Manual, Chapter 5, "Back Disorders and Injuries", 1990.

8. Boston Regional Instruction, CPL 2.11 "Guidelines and Compliance Procedures to Evaluate and Achieve Reduction of Back Injuries", 1990.

9. Eastman Kodak Company, Human Factors Section. Ergonomic Design for People at Work. Volume 1: Workplace, Equipment, and Environmental Design and Information Transfer. Belmont, California: Lifetime Learning Publications, 1983. (page 340)

10. Chaffin, D. B. and Andersson, G. B., Occupational Biomechanics, Second Edition. John Wiley and Sons, Inc., New York, 1991.

11. OSHA Instruction CPL 2.98, "Guidelines for Case File Documentation for use with Videotapes and Audiotapes", 1993.

12. Boston Regional Instruction CPL 2.13, "Ergonomic Inspection Instruction", 1993.

13. Waters, T.R., Putz-Anderson, V., and Garg, A., Applications Manual for the Revised NIOSH Lifting Equation, (in press), 1993.

1. Calculation of Incidence Rates.

The incidence rate of lifting related injuries include the number of cases that come into existence during a specified time period, usually one year, for a specified population (i.e., entire plant, one department, jobs with similar exposures, similar tasks, etc.). Injuries include incidents that are related to specific events, such as lifting a 50 pound sack of dog food. Although, there is evidence that injuries related to lifting are actually related to cumulative trauma, this directive will utilize the OSHA 200 reporting guidelines with respect to back injuries.

According to the BLS recordkeeping requirements, injuries are recordable only when they require medical treatment, or involve loss of consciousness, restricted work or motion, or a job transfer. The reaggravation of a previous injury almost always results from some new incident involving the employee (such as slip, twist, trip, extended reach, etc.). Consequently, when work related, these new incidents should be recorded as new cases. Examples of lifting related injuries include any sprains (ligament damage that occurs at a joint such as the shoulder or knee), strains (muscle and/or tendon injury), neural and/or neuromuscular related injuries (sciatica, thoracic outlet syndrome), and/or bone related injuries (a "herniated disc," fractured vertebra). Injuries associated with lifting can occur anywhere in the body, including the lower extremities, upper extremities, the back and the abdominal region. When feasible, Medical Records, first reports of injury, and employee/employer interviews shall be used to validate that the injury is related to a workplace exposure.

a. Incidence rates for lifting related injuries shall be calculated for each year during the past five years (or less if the company or process is less than five years old). The information shall be used to analyze the trend of the incidence and severity of back injuries prior to performing an analysis of the workplace hazards and prior to consulting with the Regional Ergonomist.

b. The minimum information required for calculating incidence and severity rates shall be:

(1) Total number of new incidences (cases)
(2) The date each incidence (case) was reported
(3) The department (or specific job) of the worker
(4) The number of workers in the same risk group for which the incidence rate will be calculated.
(5) The number of workers in the entire facility
(6) The number of days of restricted work activity
(7) The number of days away from work

c. An incidence rate shall be calculated for the entire facility. This number may be higher than the Lost Workdays Incident Rate (LWDI) that is required on the OSHA 1A form, since lifting injuries without lost days will be included in the calculation. An incident rate shall also be calculated for specific groups of workers when all ergonomic stressors (weights, heights of lifts, frequency of lifts, hand-load coupling, temperature, and material lifted) within each group are similar.

d. The formula used to calculate incidence rate (IR) is described in the book, Cumulative Trauma Disorders: A Manual for Musculoskeletal Disorders of the Upper Limbs, located in each area office. For convenience, the formula is provide below:

                          # back related injuries per hour x 200,000 Hrs
                    IR = ------------------------------------------------
                          Total hours worked per year
                          

The total hours represent the total number of hours worked by employees in a general or specific group.

The number 200,000 represents 100 full time workers so the resulting incidence rate is interpreted as the number of incidents per 100 workers. This normalization of the data allows for the comparison of incidence rates between different sized groups. If it is not possible to obtain the actual number of hours worked, then a denominator of (the number of full-time workers X 2000) may be used to calculate the incidence rate. Note that the injuries do not have to involve lost workdays to be included in the formula.

e. Incidence rates for the entire facility will be compared with the incidence rate for a specific group of interest, unless the group of interest represents a majority of the entire facility. In the latter case, refer to section F. 1. f. A hazard that could cause serious physical harm may exist if the incidence rate for the specific group of interest is significantly higher than the incidence rate for the entire facility. The calculation and comparison of incidence rates may also be used to determine which tasks, jobs or departments have the greatest risk for the development or musculoskeletal injuries related to manual material handling.

f. Additional factors, such as those listed below, will have to be considered in order to substantiate the evidence of employee harm where the number of workers in a facility or a specific group is small. The Regional Ergonomist can assist with the epidemiology (the study of disease) in these cases.

Additional factors that shall be used to document that employees were exposed to serious physical harm include severity, trend, employee transfer requests and employee turnover rates. Severity and trend are discussed below.

(1) Severity

Severity is a statistic that aids in the description of the seriousness of the hazard for a facility or a specific group of workers. Severity (S) can be calculated as follows:

                          Number of lost workdays X 200,000
                     S = -----------------------------------
                          Number of employees X 2,000
                          

If available, the actual number of hours worked by employees may be used in lieu of (Number of employees X 2,000) in the equation above.

Comparisons may be made with the severity rate for injuries for a specific industry (data may be available from the BLS through the Regional Ergonomist) or comparisons may be made internally. For example, an internal comparison could be made between the severity rate for a specific department and the severity rate for the entire facility.

Severity statistics attempt to describe the seriousness of the injuries that have occurred. They may be used to substantiate medical mismanagement since the longer symptoms remain unreported, the more severe they may become. In one case, a CSHO utilized the increasing trend in severity rates of night bakers to substantiate workers' comments that symptoms were not reported when they first occurred.

(2) Trend

Trend is used to look at the pattern of risk over time. Five years will be used to identify trends of incidence and severity, when the records exist.

A gradual increase in the incidence rate over five years and/or a more marked increase in the incidence rate as a result of changes to equipment and/or processes may indicate that a hazard exists. This information may also be used to show, that with reasonable diligence, the employer should have known that a hazard existed. Please be aware that increased employees's awareness of hazards may increase the incidence rate of injuries over time. However, it is expected that the severity rate should decrease in a relative manner because symptoms are reported and responded to at their onset, before they become severe. For example, a warehouse selector may incur "a sharp pain" in his/her lower back, but does not report the pain until it is so severe that several lost workdays are incurred. Sharp increases in incidence rates may also follow the termination of games such as "safety bingo" or other systems that discourage the reporting of injuries.

2. Surveying the workers

a. All workers at a facility should be surveyed by the CSHO to determine if the incidence reported on the OSHA 200 log represents the actual incidence of lifting related injuries and illnesses. In the event that the number of employees is too large to allow for interviews, questionnaires may be completed independently by the employees. In such cases, individual envelopes should be offered to employees to ensure confidentiality. Once completed, surveys can be mailed directly to the area office or picked up at a predetermined location on a specific date by the CSHO. These methods of surveying are referred to as active surveillance. Active surveillance also includes physical examination performed by a health care professional. In cases where the employer fails to recognize that the exposures and health outcomes are work related, it will be necessary to request assistance from the Regional Ergonomist for active surveillance. Under a planned agreement with physicians from Yale's, Harvard University's and The University of Massachusetts at Worcester's Occupational Medicine Residency Programs, this assistance will be available upon request for certain area offices.

The literacy of workers should be taken into consideration during active surveillance. In any case, interviewers will show impartiality to avoid "interviewer bias"; questions shall not be "leading." For example, a question such as, "Doesn't your back hurt from all of that lifting?" should be avoided. All questions should be standardized such as those in Appendix A. In general, at least 75 percent of the population under study should be interviewed so that the sample is representative of the study population. Failure to do so, in small cases, may invalidate the results of the worker surveys. However, random sampling may be used for large populations. The Regional Ergonomist is available to provide area offices with assistance in making this statistical determination.

b. Appendix A provides a sample of a valid symptom survey. OSHA publication 3123, "Ergonomic Program Management Guidelines for Meatpacking Plants," page 16 and 17, also provides an example of a valid symptom survey. Either may be used, however page 17 of OSHA publication 3123 must be replicated for each area where symptoms exist (i.e., one for the shoulder, one for the back, etc.). Failure to do this invalidates the survey.

3. Videotaping

a. All work that is analyzed for ergonomic stressors will be videotaped.

b. A written narrative will accompany the video with the following information provided:

(1) The weights of materials handled. This information is usually available from the employer via scheduling forms, manifests or inventory schedules.

(2) A rough sketch of the facility and process flow. This is usually available from an industrial engineer or production manager.

(3) The scheduling of tasks, (ie., variable, constant, rotation, full time, part time, etc.).

(4) The dimensions of the materials handled and the location of handles or cut-outs that provide for handling of the material.

(5) The heights of applicable work surfaces and reach distances.

(6) The names of tasks, jobs and departments in the order that they appear on the video.

(7) Any other relevant information pertaining to the inspection

The narrative may be recorded directly onto the video provided that the surrounding noise level allows for conversation with another person approximately four feet away. This rule of thumb will assure that your voice is audible on the video.

c. The OSHA Technical Manual, Boston Regional Instruction 2.13, dated January 3, 1993, and OSHA Instruction CPL 2.98, dated October 12, 1993, provide guidelines for video taping.

(1) In order to videotape for a "Peak Performance System" evaluation (a combination of biomechanic and kinematic methods of analysis), additional constraints exist. A description of the Peak Performance System, which can be used to evaluate biomechanical stressors across time, is provided in Appendix B. In addition, a short video tape on the use of the Peak Performance system has been provided to each area office. The Regional Ergonomist will provide assistance with the use of the peak performance analysis.

4. Checklists for OSHA investigations involving hazards associated with lifting.

a. Data from the technical manual, the Regional Ergonomist and other sources may be used to construct a checklist for the inspection. Checklists may be different for various industries. For example, adequate staffing for the performance of safe lifts, assists and transfers may be of concern in extended healthcare facilities, whereas the appropriate placement of product may be of greater concern in a food warehouse. The Regional Ergonomist can provide assistance with the construction of a checklist. An example of checklists that might be used to gain specific information such as the estimation of physical exertion during specific tasks, are provided in Appendix C.

5. Citation language and requests for assistance from the Regional Ergonomist

a. Information from the OSHA Technical Manual, the Regional Ergonomist and other sources will be used to construct a 5 (a)(1) letter and/or citation, when warranted. Model lifting citation language is offered in CPL 2.11, dated May 22, 1990, "Guidance for Compliance Procedures to Achieve Reduction of Back Injuries."

b. In all cases, a full size, VHS videotape with the approximate length of the tape noted and the statistics explained above will be submitted to the Regional Ergonomist when technical assistance is needed and before a citation is issued. Ergonomic inspections that result in a letter of significant findings do not require review by the Regional Ergonomist, although assistance is available upon request.

never-----seldom-----sometimes-----frequently-----always

* The compressive force placed on the spinal column of the low back (L5/S1 disc).

* The anterior/posterior shear force placed on the spinal column of the low back (L5/S1 disc).

* The moments (torques) placed on the elbow, shoulder, and hip joints.

* The percentage of maximum voluntary torque generated at the elbow, shoulder, and hip joints for the below average, average, and strongest male or female workers.

* The severity and relative duration (percentage of total task time) of back flexion, shoulder flexion/abduction, and wrist deviation.

* The calculated ergonomic stressors are estimates based on assumptions regarding weight distribution, the force on the hands, the location of joint centers, and muscle activation/orientation. The more assumptions that are required to perform a particular analysis, the greater the potential error in the accuracy of the calculations.

* Because the system relies on two-dimensional analysis, the tasks evaluated must be symmetric (the right and left sides of the worker must be mirror images of one another). The system becomes ineffective as a tool of analysis when the subject performs asymmetric activities which are more realistic and more frequently found in occupational settings. (An example of asymmetry would be a task where a person uses one arm and not the other.)

* To use the system properly, the CSHO must adhere to the following guidelines: (1) The camera must be stationary at all times; (2) The subject must be video taped at an angle that captures their entire upper body either in profile, a full frontal view, or a full posterior view; (3) Anobject of known length must be in the same field of view as the worker (In warehouse situations, a pallet may suffice since its length can be measured once and assumed the same for all other pallets); (4) A stationary point must be in the field of view all times; (5) The weight and gender of the operator must be recorded.

* The biomechanical modeling utilized in this system is adequate for simple handling tasks such as lifting, lowering, pushing, and pulling. However, for faster and more biomechanically complex tasks such as electronic assembly work and typing), the system would prove ineffective as a tool of ergonomic analysis.

* Physiological Evidence - the estimated metabolic energy expenditure required on the part of the worker to perform the task. These estimates should be compared to recommended guidelines set forth by the National Institute of Occupational Safety and Health as well as the American Industrial Hygiene Association.

* Psychophysical Evidence - the subjective estimate of the maximum weight or force the worker feels he or she can safely handle given the type of exertion, the frequency of the exertion, and the physical parameters of the job. This evaluation is accomplished by comparing the actual weights handled by the worker to data tables containing the maximum weights acceptable to industrial populations. "Acceptable" in this context, is defined as the maximum load a worker feels they can handle without straining, becoming unusually tired, weakened, overheated, or out of breath. In addition, psychophysical scales such as those provided in Appendix C may be used.

* Epidemiological Evidence - the evidence found in the OSHA 200 and 101 forms of an employer that documents the prevalence of musculoskeletal injuries' and illnesses in the workplace and directly associates these injuries and illnesses to the task which is being evaluated. The job turn-over rate and employee interviews should be taken into consideration as well.

* These criteria may be used to base conclusions on facts; and only then can recommendations be made on conclusions.