Risk of Lung Cancer Associated with Six Types of Chlorinated Solvents: Results from Two Case-Control Studies in Montreal, Canada
Methods: Two case-control studies of occupation and lung cancer were conducted in Montreal, including 2,016 cases and 2,001 population controls. Occupational exposure to a host of agents was evaluated using a combination of subject-reported job history and expert assessment. We examined associations between lung cancer among men and six specific chlorinated solvents and two chemical families (chlorinated alkanes and alkenes). Odds ratios were calculated using unconditional multivariate logistic analysis. Results: Pooling the two studies, there was an increased risk of lung cancer associated with occupational exposure to carbon tetrachloride (OR=2.5, 95% CI: 1.1-5.7) and perchloroethylene (OR=2.4, 95% CI: 0.8-7.7). There were no other chlorinated solvents that exhibited both statistically significant associations and indications of dose-response. Risk estimations appeared to be higher among non-smokers. Subgroup analyses indicated possible differences by histologic subtype. Conclusions: Exposure to perchloroethylene and carbon tetrachloride may increase the risk of lung cancer. Results for other solvents were equivocal.