Assessment of the possible mutagenic potential in drinking water samples from areas in SW Greece, using the Ames microsome mutagenicity assay

The mutagenic activity of thirty drinking water samples from 30 small communities in the districts of Achaia and Elia located in SW Greece as well as seven samples from the city of Patras (in the same area with 153 000 inhabitants) were examined during the years 1994-1995. The organic extract from 300-400 L of water was collected from each station and was subjected to the Ames mutagenicity assay using four genetically mutated strains of Salmonella typhimurium (TA97a, TA98, TA100, TA102) with or without metabolic acivation (10% S9). At the same time, several physicochemical characteristics of the samples were measured. Criteria for the mutagenic activity of the water samples were based on the two-fold rule and the significant non-zero slope of the linear dose response curve. In 84% of the samples at least one assay fulfilled both the two-fold rule and the significant slope and could be considered mutagenic. Thirty nine per cent (39%) of the samples were considered to show a strong mutagenic response, as in these samples the simultaneous satisfaction of the two criteria was observed in at least 3 assays out of eight. The mutagenic response was shown to be higher in chlorinated compared to untreated water samples. In the city of Patras, drinking water showed an increased mutagenic potential in comparison to an earlier study, regardless of the disinfecting process (chlorine or chlorine dioxide). The authors discuss the possibility that mutagenic activity was dependent on interaction among various organic compounds, metals and other water constituents.