Genotoxicity of drinking waters.

Drinking waters in many countries have been shown to contain non-volatile polar mutagenic compounds as well as trihalomethanes. Their nature is uncertain, but one compound, a chlorinated furanone (3-chloro-4-(dichloro-methyl)-5-hydroxy-2(5H)-furanone;MX) seems to be responsible for one third to over one half of the mutagenicity. Its concentration seems to correlate rather well also with the total bacterial mutagenicity. Animal toxicity studies are being used to evaluate the possible carcinogenicity risk of this compound as a first stage in complete risk assessment of the whole complex mixture. Epidemiological risk assessment is also possible, since mutagenicity values can be predicted on the basis of organic material in the raw water and the amount of chlorine used. This information has been collected in Finland retrospectively from waterworks, and will be correlated with the Finnish Cancer Registry data.