A case?control study of occupational risk factors for bladder cancer in Canada

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Abstract
Objective: To investigate occupational risk factors for bladder cancer in seven Canadian provinces. Methods: We analysed a population-based case–control dataset of 887 individuals with incident, histologically confirmed bladder cancer between 1994 and 1997. Controls (2847) frequency matched for age and gender were surveyed in 1996. Questionnaires were returned by about 60% of subjects. Odds ratios (ORs) for occupations and self-reported exposures were adjusted for province, age, race, smoking, and several dietary factors, using unconditional logistic regression. Results: Statistically significant increased risks were observed among men employed as hairdressers (OR=3.42; 1.09–10.8), primary metal workers (OR = 2.40; 1.29–4.50), miners (OR = 1.94; 1.18–3.17), and automechanics (OR = 1.69; 1.02–2.82). Primary metal workers and automechanics showed evidence of an employment duration–response trend. Modest elevated risks that were not significant were also observed for male government inspectors, printers, firefighters, general labourers, and welders. A duration–response trend was evident for government inspectors and general labourers. For females, significant elevations were observed among lumber processors (OR = 8.78; 1.28–60.1), general labourers (OR = 2.18; 1.05–4.52), nurses (OR = 1.54; 1.03–2.31), and general clerks (OR = 1.48; 1.01–2.17). The latter showed a positive duration–response trend. Conclusions: This study found a statistically significant excess risk of bladder cancer, with a duration–response trend, among male primary metal workers and automechanics, and female office workers engaged in general clerical duties.