Abstract
INTRODUCTION: Musculoskeletal disorders are known to result from physical demands at the workplace. Identification of risks specific to particular trades may encourage work modification to prevent new onset conditions. METHODS: In a Canadian cohort study of male and female welders and electrical workers, we collected self-reports of low-back pain, shoulder pain, and symptoms suggestive of vibration white finger (VWF) at each 6-monthly contact for up to 5 yr. Physician records of back and shoulder/joint disorders and Raynaud's syndrome were extracted from the Alberta administrative health database (AHDB). At each contact, participants completed questions on ergonomic work factors. We computed cumulative hours exposed for 6 factors: whole-body vibration, hand-arm vibration, manipulating heavy objects, working at or above shoulder height, working while crouching or kneeling, and work in cold environments. The relation of current and log cumulative exposures to health outcomes was identified by proportional hazards regression, adjusting for sex, age, body mass index, smoking, anxiety, and depression. RESULTS: Of 1,885 workers recruited January 2011 to September 2017, 872 welders and 812 electrical workers recorded symptoms and workplace demands on at least one occasion, with 693 welders and 567 electrical workers matched to the AHDB. In final models, whole-body vibration was related overall to each self-reported health outcome with backpain risk most in evidence for male welders (HR = 1.10 log increase/h of exposure: 95% CI, 1.05 to 1.15, P < 0.001). Working in a crouching position and in cold temperatures also contributed to back pain in welders. Cumulative hours working at or above shoulder height increased welders' risk of shoulder pain (HR = 1.07 log increase/h of exposure: 95% CI, 1.03 to 1.11, P = 0.001). Working at or above shoulder height was related to both back and shoulder pain in the electrical trades, where cumulative exposure to hand-arm vibration was an additional factor for shoulder pain (HR = 1.06 log increase/h of exposure: 95% CI, 1.01 to 1.10, P = 0.007). Manipulating heavy loads was a further risk factor for back and shoulder pain for women in electrical work. There were only 3 incident cases of Raynaud's syndrome in physician records: symptoms suggestive of VWF related strongly to work in cold environments but not to hand-arm vibration. Physician records of back pain did not reflect specific workplace demands, but physician records of shoulder/joint conditions were greater, overall, in those with longer exposure to whole-body vibration and to current hand-arm vibration in electrical workers. CONCLUSION: Vibration, a well-recognized hazard, was a risk factor for all outcomes but with whole-body vibration more evidently a risk for welders and hand-arm vibration for electrical workers. The final models of risk factors differed importantly between the two trades, suggesting specific targets for intervention.