Respiratory Ill-Health and Welding Exposures: A Canadian Cohort Study.

Introduction: Respiratory ill-health in welders is well documented but without a clear indication of exposures responsible.

Methods: In a Canadian cohort study of welders and electrical workers, we collected self-reports of asthma/wheeze and rhinitis at each 6-monthly contact for up to 5 years. Physician diagnoses of asthma and chronic obstructive pulmonary disease (COPD/bronchitis) were extracted from the Alberta administrative health database (AHDB). Welders provided task-specific information at each contact. Estimates were derived for cumulative exposure to particulates, chromium, and nickel. Factors associated with time to first and recurrent events were identified by proportional hazards regression, adjusting for sex, age, and smoking.

Results: Of 1001 welders and 884 workers in electrical trades recruited, 1338 in Alberta were matched to the AHDB. Welders were more at risk of physician-diagnosed COPD/bronchitis than those in the electrical trades (HR for first report = 1.87; 95% CI = 1.27-2.77) but not of asthma. Times to first self-report of asthma/wheezing (HR = 1.58; 95% CI = 1.23-2.04) and rhinitis (HR = 1.29; 95%CI = 1.11-1.49) were shorter in welders. Among welders, time to physician-diagnosed asthma was weakly related to cumulative nickel exposure (mg/m_h/100) (HR = 1.08; 95% CI = 1.00-1.17). COPD/bronchitis was related to cumulative exposure to total dust (g/m_h) (HR = 1.01; 95% CI = 1.00-1.03) and to chromium (mg/m_h/100) (HR = 1.14; 95% CI = 1.04-1.26). The risk of both asthma and COPD/bronchitis reduced with time using local exhaust ventilation. Self-reported rhinitis increased with cumulative nickel exposure (HR = 1.00; 95% CI = 1.00-1.01).

Conclusions: Welders were at increased risk of COPD/bronchitis, with risk related to cumulative dust and chromium exposure. Nickel exposure increased the risk of asthma and rhinitis.