Long-term follow-up study of mortality and the incidence of cancer in a cohort of workers at a primary aluminum smelter in Sweden

Abstract

Previous studies on mortality and the incidence of cancer among workers at primary aluminum smelters have produced conclusive results indicating an elevated risk of bladder cancer. An increased risk of lung cancer has also been reported several times. The objective of this study was to examine mortality and the incidence of cancer at a Swedish aluminum smelter when different neighboring reference populations were used to evaluate any relationships to the length of employment. A historical cohort--comprised of 2264 male nonoffice workers employed from 1942 on and tracked up to the year 2000--was examined. With the use of three reference populations for mortality and four for cancer incidence, standardized mortality and incidence ratios were calculated, together with hazard ratios derived from Cox regression models. This study showed an excess risk of mortality due to chronic obstructive lung disease, mental disorders, and diseases of the digestive system among the short-term workers. An elevated risk of cancer was found for the lungs, central nervous system, and esophagus. The highest lung cancer risk was observed for the workers employed for > or = 10 years in the factory when they were compared with the reference group from northern Sweden (standardized incidence ratio 1.99, 95% confidence ratio 1.21-3.07). The results support previous studies that demonstrated an excess risk of lung cancer, but, in contrast to the results of most studies, cancer of the central nervous system was also elevated. This study did not, however, verify an association between this type of exposure and cancer of the urinary organs.