Monitoring of Genotoxicity in Drinking Water Using in vitro Comet Assay and Ames Test

A screening strategy for evaluation of genotoxic potential of drinking water has been proposed in the present work. Genotoxicity assays with tap water collected at three different sampling points in Ljubljana drinking water region are presented here. In vitro alkaline version of the comet assay was performed with human HepG2 and Caco2 cell lines and protozoa (Tetrahymena thermophila) cells. Parallel genotoxicity evaluation on the same samples was carried out by the Ames test (with/without exogenous metabolic activation) using Salmonella typhimurium TA97a, TA100 and TA1535 strains. Nonconcentrated and concentrated water samples were tested in both bioassays, and chemical analyses were performed to check the contents of pesticides and nitrates. There was no indication of genotoxic activity in any of the drinking water samples according to the Ames test. The results of the comet assays showed differences and possible genotoxic potential among the water samples tested on different cell types, which were, however, statistically not significant, except in two cases. Statistical analyses showed the comet assay was more sensitive than the Ames test for genotoxicity detection in drinking water samples.