Disinfection By-Products: Formation and Occurrence in Drinking Water⋆⋆This article has been reviewed in accordance with the US EPA's peer and administrative review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the US EPA.

Abstract

Drinking water disinfection by-products (DBPs) are an unintended consequence of using chemical disinfectants to kill harmful pathogens in water. DBPs are formed by the reaction of disinfectants with naturally occurring organic matter, bromide, and iodide. Potential health risks of DBPs include bladder cancer and reproductive and developmental effects. This article provides a comprehensive review and listing of DBPs that have been reported for the four major disinfectants: chlorine, chloramines, ozone, and chorine dioxide (and their combinations). The occurrence and formation of the regulated DBPs are discussed, as well as many other classes of unregulated DBP including halonitromethanes, iodo-acids and other unregulated haloacids, iodo-trihalomethanes and other unregulated halomethanes, MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) and brominated MX compounds (BMXs), halonitriles, haloamides, haloaldehydes, haloketones, oxyhalides (including chlorate and iodate), N-nitrosodimethylamine (NDMA) and other nitrosamines, and nonhalogenated aldehydes, ketones, and carboxylic acids. Issues regarding increased formation of several classes of DBPs with alternative disinfectants (ozone and chloramines) are discussed, along with the importance of other routes of exposure beyond ingestion (including bathing, showering, and swimming). In addition to the formation of traditional DBPs from natural organic matter, ‘contaminant DBPs’ that are formed by the reaction of disinfectants with anthropogenic contaminants are also discussed.