Advances in research on carcinogenic and genotoxic by-products of chlorine disinfection: chlorinated hydroxyfuranones and chlorinated acetic acids.

The introduction of chlorination of public drinking water in the early 1900's was a major factor in the fight against waterborne disease. In the 1970's it was discovered that chlorine reacted with naturally occurring organic constituents, particularly in surface water, to yield small quantities of chlorinated by-products such as chloroform for which regulations were subsequently developed. Since then there has been shown to be a substantial number of other by-products some in concentrations of a few nanograms/l and others similar concentrations to the THM. Of particular note are the potent bacterial mutagen MX and the chlorinated acetic acids. Current research into the significance of these for man is described and the key issues for risk assessment are identified.