Disinfection byproducts potentially responsible for the association between chlorinated drinking water and bladder cancer: A review. (1st October 2019)

• Record Type: Journal Article
• Authors: Diana, Marine; Felipe-Sotelo, Mónica; Bond, Tom
• Is Part Of: Water research. Volume 162(2019)
• Page Start: 492
• Page End: 504
• Publication Date: 2019-10-01
• Subjects: DBPs -- Nitrosamines -- Mutagen X -- Haloquinones -- Haloamines -- Haloamides; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2019.07.014
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Epidemiological studies have consistently associated the consumption of chlorinated drinking water with an enhanced risk of bladder cancer. While this suggests that some disinfection byproducts (DBPs) are bladder carcinogens, causal agents are unknown. This study aims to highlight likely candidates. To achieve this, structures of known and hypothesised DBPs were compared with 76 known bladder carcinogens. The latter are dominated by nitrogenous and aromatic compounds; only 10 are halogenated. Under 10% of the chlorine applied during drinking water treatment is converted into identified halogenated byproducts; most of the chlorine is likely to be consumed during the generation of unidentified non-halogenated oxidation products. Six nitrosamines are among the nine most potent bladder carcinogens, and two of them are known to be DBPs: N-nitrosodiphenylamine and nitrosodibutylamine. However, these and other nitrosamines are formed in insufficiently low concentrations in chlorinated drinking water to account for the observed bladder cancer risk. Furthermore, although not proven bladder carcinogens, certain amines, haloamides, halocyclopentenoic acids, furans and haloquinones are potential candidates. At present, most identified bladder carcinogens are nitrogenous, whereas >90% of natural organic matter is not. Therefore, non-nitrogenous DBPs are likely to contribute to the bladder cancer risk. Given the high proportion of DBPs that remains uncharacterised, it is important that future research prioritises compounds believed to be potent toxicants. Graphical abstract: Image 1 Highlights: Structures of 76 bladder carcinogens were compared to known and putative DBPs. Half of bladder carcinogens are both nitrogenous and aromatic. Most chlorine applied during disinfection may form non-halogenated DBPs. Halocyclopentenoic acids, halofuranones and haloquinones are potent toxicants. Nitrosamines, halonitriles and haloamides are also toxicologically significant.