Health effects workshop summary. [Carcinogenic and mutagenic effects of chlorination of water supplies]

Cancer is a very serious health problem in the United States and a large fraction of human cancer is of environmental origin. The epidemiological data are presented that suggest that some part of environmental cancer is due to substances present in chlorinated water supplies. A number of compounds which are carcinogenic in animal model studies are known to be in chlorinated water supplies. So cancer has been identified as a real and not just potential problem in the chlorination of water supplies. Evidence that chemicals found in chlorinated waters are mutagenic, at least in bacterial test systems, is reviewed. This means they have mutagenic potential in higher organisms, including man, and that increased testing in mammalian test systems needs to be done. The data presented in this symposium on mutagenicity are interesting and important but they still do not provide the information needed to calculate human genetic risk