Bladder cancer in Taiwan: relationship to trihalomethane concentrations present in drinking-water supplies

The objective of this study was to evaluate whether exposure to disinfection by-products (DBP) is associated with bladder cancer. A matched case-control study was used to investigate the relationship between the risk of death from bladder cancer and exposure to total trihalomethanes (TTHM) in drinking water in 65 municipalities in Taiwan. All bladder cancer deaths of the 65 municipalities from 1996 through 2005 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth,and year of death. Each matched control was selected randomly from the set of possible controls for each cancer case. Data on TTHM levels in drinking water in study municipalities were collected from the Taiwan Environmental Protection Administration. The municipality of residence for cancer cases and controls was assumed to be the source of the subject's TTHM exposure via drinking water. The adjusted odds ratios for bladder cancer death for those with high TTHM concentrations in their drinking water were 1.8 (1.18-2.74) and 2.11 (1.43-3.11) compared to the lowest group. The results of this study show that there was a significant positive correlation between the concentration of TTHM in drinking water and risk of death from bladder cancer.