Objectives The objective of this study was to investigate whether occupational gasoline and/or diesel exhaust exposure contribute to kidney cancer risk.

Methods The National Enhanced Cancer Surveillance System is a population-based case-control study conducted from 1994–1997 in Canada. Incident kidney cancer cases were identified using provincial registries, while the control series were identified through random digit dialling, or provincial datasets. Self-reported questionnaires obtained information on lifetime occupational history and cancer risk factors. Hygienists coded occupational histories for diesel and gasoline exhaust exposures using concentration, frequency, duration and reliability. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals separately by exhaust type. Models were adjusted for age, province, BMI, and cigarette smoking.

Results Complete occupational data were available for 652 cases and 2368 controls. The majority of workers had been exposed to diesel (53%) or gasoline (55%) exhausts, respectively; most exposures were at low concentrations. Workers who had ever been exposed were significantly more likely to have kidney cancer than those who were never exposed (OR diesel: 1.4;1.1–1.6, OR gasoline: 1.7;1.4–2.1). When examining duration of exposure and tertiles of cumulative exposure, diesel and gasoline exposures were both linked to a significantly increased risk of kidney cancer (p<0.05), but no exposure-response pattern was evident. Exposure to gasoline exhaust showed stronger positive relationships with kidney cancer than diesel.

Conclusions This study provides evidence that occupational gasoline and to a lesser extent, diesel exhaust exposure increases the risk of kidney cancer.