Non-malignant mortality among Norwegian silicon carbide smelter workers.

Abstract

To investigate associations between exposures in the silicon carbide (SiC) industry and mortality from non-malignant diseases. Mortality among 2562 men, working in one of three silicon carbide smelters was investigated, giving 52,618 person-years of follow up from 1962 to 1996. Dose-response relations were investigated by internal comparisons using Poisson regression and by stratified standardised mortality ratio (SMR) analyses. Mortality from all causes was significantly raised compared with the Norwegian mortalities among men, SMR=1.12, (95% confidence interval (95% CI) 1.05 to 1.20). An excess mortality from asthma, emphysema, and chronic bronchitis combined was found, SMR=2.21 (95% CI 1.61 to 2.95), increasing from 1.05 in the unexposed category to 2.64 (95% CI 1.44 to 4.43) in the upper category of exposure to total dust. The Poisson regression analysis confirmed the results from the stratified SMR analyses, and suggested that smoking did not act as a confounder. No association was found for circulatory mortality. There was an increased mortality from asthma, emphysema, and chronic bronchitis combined among SiC workers exposed to dust.