Genotoxicity Detection in Drinking Water by Ames Test, Zimmermann Test and Comet Assay

Barbara Lah,a Brigita Žinko,a Tatjana Tišler,b and Romana Marinšek Logara*
a Biotechnical Faculty, Zootechnical Department, University of Ljubljana, Groblje 3, 1230 Domžale. E-mail:
National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana

Drinking water of good quality is the primary requirement from public health point of view. Over past two decades, many studies have reported the presence of various hazardous compounds in drinking water that may cause long-term health effects, e.g. gastrointestinal and urinary tract cancers. Sources of drinking water contamination are industrial and agricultural activities, disinfection by-products and transportation. Monitoring of drinking water in Slovenia is based on regular physico-chemical and microbiological assays according to European Community legislation. Since physico-chemical analyses do not provide enough information about biological effects of pollutants, we are studying the possibilities of including biological tests into drinking water monitoring. In the present work we tested three genotoxicity assays with water collected at three different sampling points in Ljubljana drinking water region. The Ames test was performed with and without metabolic activation using bacterium Salmonella typhimurium TA97a, TA100 and TA1535 strains. The same samples were tested with the yeast Saccharomyces cerevisiae strain D7, with and without metabolic activation in Zimmermann test. Parallel genotoxicity evaluation on the samples was carried out as alkaline version of the comet assay performed with human HepG2 cell line. Original and concentrated water samples were tested in all bioassays following the chemical analyses for pesticides and nitrate. There was no indication of genotoxic activity in any of drinking water samples according to Ames and Zimmermann test. On the contrary, the results of the comet assay revealed low genotoxicity in most of the drinking water samples. As only the Comet assay proved to be sensitive enough to detect genotoxicity, we propose to include it in regular biomonitoring of drinking water.  

Key words: drinking water, physico-chemical analyses, in vitro genotoxicity bioassays