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The evaluation of exposure for distal upper extremity musculoskeletal stressors has generally focused on determining the presence of one or more generic risk factors.(1-4) Only a few studies have attempted to quantify their intensity or examine their interactions.(5-12) As a result, exposure assessment related to the identification of distal upper extremity hazards is usually subjective and often lacks standardization.
There are several circumstances where a more standardized methodology would be helpful. For example, decisions on the work-relatedness of a disease should be based on exposure assessment arising from job analysis rather than on someone's subjective opinion.(13) Similarly, a conclusion regarding the presence of a hazardous exposure should rely on results of a job analysis.
OPTIONS FOR DETERMINING SAFE VERSUS HAZARDOUS JOBS
The terms "safe" and "hazardous" describe jobs. Hazardous jobs expose workers to one or more musculoskeletal stressors of sufficient intensity, frequency, and/or duration so that the workers are at increased risk for musculoskeletal disorders. "Safe" implies that the job is not hazardous--e.g., exposed workers are not at increased risk. "Safe" does not imply no exposure. At present, there are four options to determine whether a job is safe or hazardous. These are (1) professional opinion based on subjective judgment and past experience; (2) determination of some physiological, biomechanical, or psychophysical critical threshold response (e.g., disc compressive force for low-back pain);(14) (3) epidemiological data that associates job, task, and/or individual variables with some manifestation of increased risk of a disorder; or (4) some combination of these three (e.g., the revised National Institute for Occupational Safety and Health [NIOSH] equation for manual handling tasks).(15)
Professional judgment from highly qualified job analysts is very desirable and probably cannot be replaced by any model; however, it is subjective and can be influenced by personal bias. Since a large number of people with varying educational and background experiences (ergonomists, industrial hygienists, safety professionals, physicians, nurses, physical therapists, occupational therapists, etc.) are called on to determine whether a job is safe or hazardous, differences of opinion are expected. Some may call a job extremely hazardous while others call it totally safe. Since the exposure assessment process is entirely subjective, there is no objective means of resolving these differences of opinion.
As far as distal upper extremity disorders are concerned,...