Mortality and cancer incidence in aluminum reduction plant workers

An historical cohort study was conducted among 4,213 men who worked for 5 or more years at a Soderberg aluminum reduction plant in British Columbia (BC), Canada. Standardized mortality and incidence ratios were used to compare the mortality and cancer incidence of the cohort with that of the BC population and to examine risk by cumulative exposure to coal-tar pitch volatiles (CTPV) and electromagnetic fields. Significantly elevated rates were observed for bladder cancer incidence (standardized incidence ratio [SIR] = 1.69) and brain cancer mortality (standardized mortality ratio = 2.17). The risk of bladder cancer was strongly related to cumulative exposure to CTPV (P less than .01). The risk for non-Hodgkin's lymphoma also increased with increasing exposure (P less than .05), although the overall rate was similar to that of the general population (SIR = 1.06). The lung cancer rate was as expected (SIR = 0.97), but showed a weak association with CTPV exposure that was not statistically significant. No individual cause of death or incident cancer site was related to exposure to electromagnetic fields. Analysis of the joint effect of smoking and CTPV exposure on lung and bladder cancer showed the exposure response relationships to be independent of smoking.