Several studies suggest that farmers may be at increased risk of
prostate cancer. The present analysis, based on a large population-based case-control study conducted among men in the Montreal area in the early 1980's, aim at identifying occupational chemicals which may be responsible for such increases. The original study enrolled 449
prostate cancer cases, nearly 4,000 patients with other
cancers, as well as 533 population controls. Subjects were interviewed about their occupation histories, and a team of industrial hygienists assigned their past exposures using a checklist of some 300 chemicals. The present analysis was restricted to a study base of men who had worked as farmers earlier in their lives. There were a total of 49 men with
prostate cancers, 127 with other
cancers and 56 population controls. We created a pool of 183 controls combining the patients with
cancers at sites other than the prostate and the population controls. We then estimated the odds ratio for
prostate cancer associated with exposure to each of 10
agricultural chemicals, i.e., pesticides,
arsenic compounds,
acetic acid,
gasoline engine emissions, diesel engine emissions,
polycyclic aromatic hydrocarbons from
petroleum, lubricating
oils and greases,
alkanes with >or=18 carbons,
solvents, and mononuclear
aromatic hydrocarbons. Based on a model adjusting for age, ethnicity, education, and respondent status, there was evidence of a two-fold excess risk of
prostate cancer among farmers with substantial exposure to pesticides [odds ratio (OR)=2.3, 95% confidence interval (CI) 1.1-5.1], as compared to unexposed farmers. There was some suggestion, based on few subjects, of increased risks among farmers ever exposed to diesel engine emissions (OR=5.7, 95% CI 1.2-26.5). The results for pesticides are particularly noteworthy in the light of findings from previous studies. Suggestions of trends for elevated risks were noted with other
agricultural chemicals, but these are largely novel and need further confirmation in larger samples.