The International Agency for Research on Cancer classified diesel exhaust as a carcinogen and gasoline exhaust as a possible carcinogen based on evidence for lung cancer. There is limited evidence to support an association with bladder cancer.
To investigate the association between occupational exposure to diesel and gasoline engine emissions and bladder cancer in Canadian men.
Men diagnosed with bladder cancer cases (N=670) and age frequency matched controls (N=1642) were assembled from the population-based case-control component of the National Enhanced Cancer Surveillance System. Information on lifetime occupational history and possible cancer risk factors for 8 Canadian provinces was collected from 1994 to 1997. Concentration and frequency of exposures to diesel and gasoline engine emissions, and a measure of the reliability of exposure assessment was assigned to each job using a job-exposure matrix that was supplemented by expert review. Logistic regression was used to calculate odds ratios and 95% confidence intervals adjusted for other bladder cancer risk factors.
Relative to unexposed men, exposure to high concentrations of diesel was associated with an increased risk of bladder cancer (OR = 1.87, 1.01 – 3.47). Duration of employment of up to six years (OR = 4.61, 1.33 – 16.04) and 20 or more years (OR = 2.50, 1.02 – 6.14) in occupations with exposure to high concentrations of diesel was also associated with bladder cancer (ptrend=0.05) relative to those who were unexposed. Exposure to gasoline engine emissions was not related to bladder cancer. We found that the effect of exposure to diesel was independent of the effect of cigarette smoking on bladder cancer.
These results support the hypothesis that exposures to high concentrations of diesel engine emissions increase the risk of bladder cancer. In contrast our analysis does not support an increased risk of bladder cancer from occupational exposure to gasoline engine emissions.