ERGONOMIC STRESSORS AND UPPER EXTREMITY DISORDERS IN VEHICLE MANUFACTURING - CROSS-SECTIONAL EXPOSURE-RESPONSE TRENDS

Objective-To evaluate the association between upper extremity soft tis sue disorders and exposure to preventable ergonomic stressors in vehic le manufacturing operations. Methods-A cross sectional study was condu cted in one vehicle stamping plant and one engine assembly plant. A st andardised physical examination of the upper extremities was performed on all subjects. An interviewer administered questionnaire obtained d ata on demographics, work history, musculoskeletal symptoms, non-occup ational covariates, and psychophysical (relative intensity) ratings of ergonomic stressors. The primary exposure score was computed by summi ng the responses to the psychophysical exposure items. Multivariate re gression analysis was used to model the prevalence of disorders of the shoulders or upper arms, wrists or hands, and all upper extremity reg ions (each defined both by symptoms and by physical examination plus s ymptoms) as a function of exposure quartile. Results-A total of 1315 w orkers (85% of the target population) was examined. The prevalence of symptom disorders was 22% for the wrists or hands and 15% for the shou lders or upper arms; cases defined on the basis of a physical examinat ion were about 80% as frequent. Disorders of the upper extremities, sh oulders, and wrists or hands all increased markedly with exposure scor e, after adjustment for plant, acute injury, sex, body mass index, sys temic disease, and seniority. Conclusions-Musculoskeletal disorders of the upper extremities were strongly associated with exposure to combi ned ergonomic stressors. The exposure-response trend was very similar for symptom cases and for physical examination cases. It is important to evaluate all dimensions of ergonomic exposure in epidemiological st udies, as exposures often occur in combination in actual workplaces.