Trihalomethanes in drinking water and the risk of death from colon cancer in Taiwan.

The objective of this study was to evaluate whether exposure to disinfection by-products (DBP) is associated with colon cancer. A matched case-control study was used to investigate the relationship between the risk of death attributed to colon cancer and exposure to total trihalomethanes (TTHM) in drinking water in 65 municipalities in Taiwan. All colon cancer deaths of the 65 municipalities from 1997 through 2006 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 cancer 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 (OR) for colon cancer death for those with high TTHM levels in their drinking water were 1.02 (0.87-1.2) and 1.04 (0.89-1.21) compared to the lowest group. The results of the present study show that there was no statistically significant association between TTHM in drinking water at levels in this study and risk of death from colon cancer.