Occupational exposure to solvents and bladder cancer: A population-based case control study in Nordic countries

The objective of the study was to assess the relationship between exposure to selected solvents and the risk of bladder cancer. This study is based on the Nordic Occupational Cancer (NOCCA) database and comprises 113,343 cases of bladder cancer diagnosed in Finland, Iceland, Norway and Sweden between 1961 and 2005 and 566,715 population controls matched according to country, sex and birth year. Census-based occupational titles of the cases and controls were linked with the job exposure matrix created by the NOCCA project to estimate quantitative cumulative occupational exposures. A conditional logistic regression model was used to estimate hazard ratios (HRs) and their 95% confidence intervals (95% CI). Increased risks were observed for trichloroethylene (HR 1.23, 95% CI 1.12-1.40), toluene (HR 1.20, 95% CI 1.00-1.38), benzene (HR 1.16, 95% CI 1.04-1.31), aromatic hydrocarbon solvents (HR 1.10, 95% CI 0.94-1.30) and aliphatic and alicyclic hydrocarbon solvents (HR 1.08, 95% CI 1.00-1.23) at high exposure level versus no exposure. The highest excess for perchloroethylene was observed at medium exposure level (HR 1.12, 95% CI 1.02-1.23). The study provides evidence of an association of occupational exposure to trichloroethylene, perchloroethylene, aromatic hydrocarbon solvents, benzene and toluene and the risk of bladder cancer.