Exhibit 1: Triggers for NIOSH Evaluations

Manufacturing Work Setting
A plumbing-ware manufacturing company asked NIOSH to assist in an ergonomics evaluation of their production operations after an OSHA inspection found a high number of back injuries at the facility relative to the rates at other manufacturing plants in the same industrial classification. This industry as a whole had the tenth highest OSHA reportable incidence rate in the United States for 1986. The work areas where most back injuries had occurred were identified by the plant's safety director, and the jobs believed most stressful to the workers' backs became the main targets of the evaluation that ensued [HETA 88–237–L1960].

Office Work Setting
NIOSH received a request from a local union representing office and professional employees of a health insurance company to evaluate potential hazards from the use of video display terminals (VDTs) in data entry operations. Numerous, wide-ranging symptomatic complaints had been voiced by the terminal operators, including headaches, general malaise, eyestrain and other visual problems, back pain, and stiffness and soreness in the neck and shoulder areas and upper extremities. A questionnaire used for data gathering during the evaluation verified more complaints of this nature among VDT users than nonusers, and environmental and workstation measurements suggested that certain ergonomic factors contributed to these differences [HETA 79–060–843].

Service Work Setting
The owner and employees of a preschool day care center asked NIOSH to identify possible causes of musculoskeletal problems, chiefly back pain and lower extremity (knee) pain and discomfort, reported by the teachers and aides at the school. Subsequent data collected on symptomatic complaints and observations and analyses of work activities indicated that factors such as frequent lifting of infants and sustained periods of kneeling, stooping, squatting, and trunk bending were responsible for the problems [HETA 93–0995–242].

Exhibit 2: Worker Involvement

NIOSH was asked to evaluate musculoskeletal pain and discomfort in the upper neck and shoulder areas as well as the lower back, buttocks, and legs of cashiers. The pain was thought to result from operating registers at express checkout counters in a supermarket. In analyzing workstation design and job task factors that could account for the above problems, the investigators interviewed a number of cashiers. The cashiers related their musculoskeletal complaints specifically to certain design characteristics of the checkout counters. They indicated that

• the far corner of the checkout counter required extended reaching for items, resulting in excessive trunk flexion and bending,
  
  
• the register keyboard height and distance induced static stress and shoulder flexion, and
  
  
• other tasks performed at the workstations required constant twisting because of the layout.

At a meeting with management and workers, initial interventions that gave priority to these problematic factors were agreed upon. A barrier was placed at the far corner of each checkout counter to reduce the extended reaching and bending for groceries, and height-adjustable keyboards were installed to relieve the static stress and shoulder flexion. Reductions in the number of symptoms associated with these active areas of the intervention were found following the implementation of these measures [HETA 88–345–2031; Orgel et al. 1992].

Exhibit 3: A Joint Labor-Management Committee Approach

The ergonomics committee at a plant that manufactured pistons and piston sleeves asked NIOSH to conduct an ergonomics evaluation to further their efforts at reducing cases of musculoskeletal disorders. This committee had been formed as a result of contract negotiations with the local union and in recognition of excessive cases of musculoskeletal disorders and increased production demands. The committee consisted of one hourly and one salaried person from each of six plant departments, one industrial engineer, three manufacturing engineers, three department superintendents, and one secretary, who provided input on office ergonomics. The plant manager chaired the committee, which met for 1 to 2 hours each month. Education and training in ergonomics were provided through viewing videotapes and reading literature received from the State safety councils. Selected workers in the plant workforce also viewed this material.

The committee focused on problem areas identified through examining safety logs, talking with the equipment operators, and observing job operations. Linkages between injury patterns, operator reports, and observations served to target major problem areas for priority attention. In one instance, a cluster of upper-limb problems was reported by the milling machine operators who had to open and close the machine doors manually for each piston sleeve being milled. The committee decided to install automatic door openers and closers. Workers suggested these and other ergonomic solutions to apparent problems, and the controls were fabricated in the plant's maintenance department. However, because of their limitations in addressing the less obvious ergonomic problems, the committee asked for NIOSH assistance.

NIOSH recommended specific control measures on the basis of its investigators' observations and acknowledged the need for more on-site training of workers in recognizing ergonomic hazards and risks of musculoskeletal injury in their jobs. In light of the plant safety data and observations of job operations, guidance was offered to create a more proactive effort in preventing WMSDs. A limitation of the committee approach used in this plant was that most of the input came from management. Their preoccupation with production demands could override the time and effort needed to resolve job tasks presenting risks of WMSDs. On the other hand, the committee benefited from their increased knowledge and experience in dealing with ergonomic hazards. One result was that decisions about future procurements of machines and proposed changes in manufacturing processes were to include ergonomic considerations [HETA 94–0040–2496].

Exhibit 4: A Work Group Approach

In 1992, NIOSH commissioned three case studies to demonstrate the efficacy of using "ergonomics teams" in addressing hazards in meat packing plants. The studies, conducted at three different sites, depicted a variety of contexts and opportunities for observing the merits of this form of worker involvement. The studies showed the following:

• Sustained participatory efforts in ergonomics problem solving require strong in-house direction and support plus significant staff expertise in both team building and ergonomics. In one of the three cases in which the effort was largely driven by an outside investigator, there were indications the program would not be sustained.
  
  
• Accomplishments, in terms of number of tasks or jobs analyzed and solutions offered and implemented, were most apparent in those cases showing significant training efforts in both team building (group techniques in task analyses, interpersonal processes, developing consensus) and ergonomics (defining risk factors related to musculoskeletal disorders and techniques for job analyses). The case indicating the least progress had limited formal training in ergonomics and used the team simply to brainstorm possible solutions to problems without much other background preparation.
  
  
• Most team progress was evident if teams were kept small and included production workers engaged in the jobs under study, area supervisors, and maintenance and engineering staff who could effect proposed job improvements. In two cases, higher personnel served on second-level groups providing oversight to the team activities and approval of actions as needed.
  
  
• Team members in the three case studies shared information (injury and production data) bearing on job problems. In addition, reports about the teams' objectives, progress, and accomplishments were circulated to keep the plant workforce informed. Problem-solving goals, as established by the teams, took more time than anticipated to attain. More realistic goals may need to be set [Gjessing et al. 1994].

Note: In two of the three plants in which these case studies were conducted, worker members were chosen by the unions to serve on the work team. The formation of these teams did not violate the existing collective bargaining process.

Exhibit 5: An Individual Input Approach

NIOSH sponsored a study at a major hospital site in which a plan was followed based on employee hazard recognition and problem solving. A special committee was developed to encourage workers to report unsafe conditions and to make suggestions for corrective measures. The committee provided prompt feedback about actions taken through the hospital-wide posting of bulletins on progress, as well as other forms of publicity.

Measurements taken before and 12 months after the program was implemented showed a 33% increase in the number of hazards reported by workers, with a corresponding drop in injury rates of 25%. These rates suggested an increased safety consciousness among the workers and a consequent reduction in injuries. Relevant to the subject of ergonomics were results found in comparing the content of the hazard reports with the actual agent or injury data. Workers tended to detect more physical hazards (slip and trip hazards, struck by or against hazards) than were accounted for in terms of actual injury, but they clearly underestimated those involving overexertion, such as in patient lifting or other procedural-type situations. These data suggested the need for more worker training devoted to these kinds of concerns [Lin and Cohen 1983].

Exhibit 6: Team Training in Ergonomic Problem Solving

University investigators, in partnership with NIOSH, undertook a case study of an ergonomics team approach in implementing control measures to reduce WMSDs at a meat packing plant. In all, five joint management-labor teams representing different departments, each consisting of 7 to 9 members, were formed. Team-building training consisted of sessions designed to enhance the members' abilities to work together. Team-building activities included

• defining a team,
• determining the goals of an ergonomics team,
• establishing group meeting rules and team roles,
• reviewing guidelines for effective group discussion and constructive feedback, and
• practicing brainstorming exercises and techniques for consensus building.

Consistent with the approaches advocated by experts in team building, the training emphasis throughout was about the way to develop task-oriented skills and positive, interpersonal processes. Forms for documenting team members' responsibilities, records of meetings and actions taken, and other handouts served to reinforce these points.

The ergonomics training given to the teams included using videotaped instruction and practice in job analysis techniques to identify and prioritize jobs needing intervention. The video analysis used a rating technique to determine the extent of hand, wrist, arm, and shoulder movements, as well as the positions of the backs and necks of workers while they performed tasks in their departments. Job analyses used OSHA log entries, observations of job tasks, and worker input about ways to ease the difficulty of those job operations presenting the most stressful problems [Gjessing et al. 1994].

Exhibit 7: Reviewing OSHA Logs

NIOSH was asked to conduct a health hazard evaluation at a plant that fabricates wheels for trucks and busses. Major plant processes involved forming steel stock into the rims and center cores of the wheels, welding them together, and finishing and painting the welded product which was then crated for shipment. One objective of the evaluation was to verify the company's concerns about musculoskeletal problems that seemed related to operations in assembly and disc forming work. NIOSH reviewed the company's OSHA log entries for injuries and illnesses for the past 2 years and found about half (291 of a total of 588 entries) were cases of strains and sprains, carpal tunnel syndrome, tendinitis, bursitis, and other musculoskeletal problems. The musculoskeletal injury rate for the plant was 26.1 injuries per 100 employees. This rate exceeded the expected rate of 10.6 injuries per 100 employees based on the Bureau of Labor Statistics' reports that were then available for the motor vehicle parts industry. Back injury (primarily low back strain) constituted the largest proportion of injuries in the strain and sprain category; the total plant rate for back disorders was 11.3 injuries per 100 workers per year which was 5 times the rate for the industrial workforce as a whole. The rate of back disorders was highest in the Assembly Department (23.7 injuries per 100 workers per year) followed by the Disc Forming Department (20.0 injuries per 100 workers per year). Consequently, job tasks in these two departments became the primary targets for analyzing and controlling risk factors (predominantly repeated, heavy lifting) that could account for the observed musculoskeletal problems [HETA 88-277-2069].

Exhibit 8: Using OSHA Logs and Worker Interviews

On the recommendation of a State occupational safety and health agency and on the basis of their inspection of certain work conditions, the management of a window manufacturing plant asked NIOSH to evaluate the risk of carpal tunnel syndrome among workers engaged in assembling window units. As part of a medical evaluation, NIOSH investigators reviewed OSHA Form 200 logs and pertinent company medical records and held confidential interviews with workers doing the assembly work. Questions asked during the interviews sought information about the symptoms workers experienced since beginning work at the plant, including the date of onset, location, type, severity and timing (during day or night, steady or intermittent), duration, medical and surgical treatment, past medical history, most difficult job tasks, and hobbies. They also asked for suggestions for changes in assembly procedures or tools used to alleviate apparent problems. The following case definition of work-related carpal tunnel syndrome was adopted in assessing these data:

• During the interview, the worker reported pain, numbness, or tingling affecting the median nerve distribution of the hand(s).
  
  
• Symptoms lasted at least 1 week or occurred on multiple occasions.
  
  
• Symptoms were severe enough to waken the person from sleep.
  
  
• Evidence existed of work relatedness in that the symptoms began after starting work at a job involving recognized risk factors for carpal tunnel syndrome (e.g., repetitive hand movements, excessive force, awkward hand positions, pinch grips, etc.).

A medically confirmed case of probable work-related carpal tunnel syndrome was said to exist if the above criteria were met, and the employee had sought medical care and was diagnosed as having carpal tunnel syndrome. Medical records were reviewed to confirm the diagnosis.

A review of OSHA Form 200 logs from over a 3-year period indicated no hand/wrist disorder entries the first year, two entries for hand/wrist pain in the second year, and nine entries for either hand/wrist pain or carpal tunnel syndrome in the third year. As the size of the assembly workforce over the 3-year period remained the same (27 to 28 workers), these data suggested a worsening problem. The medical interviews of all 28 assembly workers indicated five confirmed cases of carpal tunnel syndrome (three surgically treated at the time of the evaluation) and five other possible carpal tunnel syndrome cases. Other health effects included numbness in the ulnar nerve (three workers), ganglionic cysts (two workers), tendinitis (three workers), elbow pain (one worker), neck pain (one worker), and shoulder pain (one worker).

The ensuing ergonomics evaluation of assembly work tasks revealed repetitive hand/wrist manipulations (8 of 12 job tasks requiring 20,000+ movements per shift) with varying degrees of force and bent wrist positions—all risk factors commonly associated with carpal tunnel syndrome. The pressure to increase production and working with defective materials which necessitate using added force to assemble parts were believed to worsen the problem [HETA 88-361-2091].

Exhibit 9: Symptom Surveys

NIOSH was asked to evaluate the incidence of upper limb disorders among workers engaged in sewing tasks at a uniform manufacturing company. The request was prompted by employee complaints that included aching, numbness, clumsiness, and swelling of the wrists and hands. OSHA log data were nonexistent in this plant at the time of this 1983 investigation. A medical questionnaire was specially designed to gather data on upper limb symptoms, with particular emphasis on hand/wrist problems. Sections of the questionnaire covered the usual background information (age, sex, occupational history), the present job at the plant, the nature of hand motions (lifting and lowering, pushing and pulling, twisting and turning, screwing, bending and rotating wrists, pinching and grasping with fingers), pain and discomfort areas (neck, shoulders, arms, elbows), the nature of symptoms in hands or wrists (swelling, stiffness, cramping burning, tingling), the time of onset (late night awakenings), and any difficulties with hands and fingers in some everyday tasks (e.g., buttoning shirt, turning key in lock or doorknob, holding tools) plus medical history asking about any injury, surgery, or pre-existing diagnostic problem (e.g., arthritis) that could account for apparent problems. A section of the questionnaire also included a picture of both surfaces of the right and left hands with the instruction to shade in those areas where most of the discomfort or difficulty occurs. A total of 64 of 90 sewing machine operators completed this form. Neck, shoulder, and arm pain were commonly reported by these operators, with the symptom reports rarely dropping below 36% and ranging as high as 80%. The most numerous hand/wrist symptoms were numbness, cramping, and tingling sensations (varying from 43% to 60%). Despite the frequent occurrence among sewers of symptoms suggestive of upper limb musculoskeletal disorders, jobs rated high and low in ergonomic risk factors showed only small differences in the rate of the symptoms reported. Possible reasons for the lack of differentiation are given in the report [HETA 83–205–1702].

Exhibit 10: Use of Diagnostic Tests

In response to a union request, NIOSH conducted a study to evaluate whether cashiers in a major supermarket chain were developing upper extremity musculoskeletal disorders because of their jobs. The evaluation had two major components.

• The first component compared the rate of upper extremity musculoskeletal disorders in the cashiers with the rate in other supermarket workers. For this purpose, physical exams were given to both groups of workers, including range of motion, limb bending, and stretching tests. The workers rated the pain experienced for the maneuvers. Positive responses on these tests for a particular part of the body, together with questionnaire data indicating recurring or prolonged discomfort in the same area (which began after starting work at the supermarket) were defined as a WMSD. To ensure objectivity, these determinations were made by a physician who had no prior knowledge of either the existing disease state or the job titles of the workers.
  
  
• The second component consisted of direct observation and a videotape analysis of the cashier's job, measuring the number of items processed, the number of scans, and the number of keyboard entries required of the cashier. These data were used to gauge task repetitiveness, posture factors, the force required, and efficiency of movement for different checkout counter designs.

The study results indicated that the cashiers had a higher rate of upper extremity disorders than other supermarket workers for all parts of the upper body and that those cashiers with longer employment or who spent more hours per week in checkout tasks showed more evidence of such problems. Further analyses in this study sought to isolate certain checkout counter design features, tasks, and work practices as possible stress factors in light of the pattern of musculoskeletal problems noted [HETA 88–344–2092].