A cohort study of Parkinson's disease and other neurodegenerative disorders in Danish welders.

Abstract

We sought to evaluate rates of hospitalizations for neurodegenerative disorders in a cohort of Danish metal manufacturing employees. A retrospective cohort study was conducted from 1977 to 2002 among 27,839 male Danish metal-manufacturing employees, with 9,817 of those employed in departments engaged in mild or stainless-steel welding and 6,163 welders. The standardized hospitalization ratio and 95% confidence intervals (CI) for Parkinson's disease were 0.9 (CI = 0.7-1.2) for men in steel-manufacturing companies, 1.0 (CI = 0.7-1.5) for men in welding departments, and 0.9 (CI = 0.4-1.5) for welders. Observed numbers for other neurological conditions were small and not above population expectations. Analyses for time period worked, age, and duration of welding were unremarkable. This relatively large cohort study with long-term follow-up provides no support for the hypothesis that rates of hospitalization for Parkinson's disease or other neurological conditions are elevated under the exposure circumstances of these Danish workers.