Literature review of meta-analyses and pooled analyses of disinfection by-products in drinking water and cancer and reproductive health outcomes

Disinfection of drinking water has led to major improvements in public health in developed countries since its introduction in the first half of the 20th century. Chlorination disinfection by-products (DBPs) are formed when water is chlorinated and organic matter in the water reacts with chlorine. A number of meta-analyses and pooled analyses of exposure to DBPs and various health outcomes have been published and here we review these studies to provide an overall overview of the evidence of disinfection by-products and health effects. This review showed that various meta-analyses and pooled analyses have found statistically significant excess risk for some indicator of exposure to chlorinated water or trihalomethanes and bladder and colorectal cancer, small for gestational age, still birth, all congenital anomalies combined and ventricular septal defects, but no statistical significant excess risk for many other congenital anomalies. The excess risk was generally small, but robust, with little sensitivity to the results of individual studies or evidence of publication bias.