Mutagenicity and genotoxicity of water treated for human consumption induced by chlorination by-products.

Water used for human consumption may contain mutagens and carcinogens generated during the disinfection process with chlorine. In the study described in this article, the mutagenicity and genotoxicity of water samples taken from the San Cristobal treatment plant in Medellin, Colombia, were evaluated. Short-term mutagenic and genotoxic assays using the Ames test and comet assay, respectively, were employed to examine the genotoxic activity of the extracts of these water samples. Two samples were taken before and after the chlorination process. The treated water samples without chlorination did not show mutagenic effects using the Ames test, while the chlorinated samples produced mutagenic activity in both strains. A dose-response relationship for the comet assay was obtained only in the chlorinated samples. MX (3-chloro-4-[dichloromethyl]-5-hydroxy-2[5H]-furanone), E-MX ([E]-2-chloro-3-[dichloromethyl]-4-oxobutenoic acid), and some trihalomethanes were detected at low concentrations. These concentrations were enough, however, to cause detectable mutagenic and genotoxic activity in the extracts of chlorinated water samples.