Occupational exposure to chemical and petrochemical industries and bladder cancer risk in four western Canadian provinces

Abstract

Occupational factors have been proposed to play a critical role in bladder cancer. This population-based case-control study was conducted to confirm the association between selected occupational and non-occupational risk factors and risk of bladder cancer using data collected from the four western Canadian provinces. Unconditional logistic regression analyses were based on 549 histologically confirmed bladder cancer cases and 1099 controls. Bladder cancer risk was found to increase with increasing pack-years of cigarette smoking with an odds ratio (OR) in the highest quartile of 3.32 (95% confidence interval [CI], 2.28-4.82). A dose-response relationship was demonstrated between bladder cancer and pack-years of smoking (p < 0.0001). A positive trend was observed with coffee consumption in men (p < 0.0001), with the highest risk in the highest category of exposure: drinkers of four cups or more per day had an OR of 1.77 (95% CI 1.11-2.82). Increased bladder cancer risk was associated with self-reported exposure at work to several chemicals: asbestos (OR 1.69 [95% CI 1.07-2.65]); mineral, cutting or lubricating oil (1.64 [95% CI 1.06-2.55]); benzidine (2.20 [95% CI 1.00-4.87]). The population attributable fraction (PAF) estimates were 51% for cigarette smoking, 17% for heavy coffee consumption, 10% for mineral, cutting or lubricating oil exposure, 6% for asbestos exposure, and 1% for benzidine exposure. Although self-reported chemical exposures have important limitations, the findings are suggestive of increased risk for several associations previously reported between chemical agents or industries and risk of bladder cancer.