Toxicity and genotoxicity studies of surface and waste water samples using a bacterial SOS/umu test and mammalian MTT and comet assay

Surface and waste waters are complex mixtures that may contain thousands of different pollutants of different origins (industrial, agricultural and domestic). Many of them show toxic and/or genotoxic effects and are therefore potentially hazardous for humans and the environment. It is extremely difficult to quantify the risk associated with xenobiotics in environmental samples because they usually occur in concentrations too low to allow chemical analytical determination. Additionally, single and combined biological effects of most of the micropollutants are not known. The best approach to evaluate potential toxic/genotoxic risks of such mixtures is to use biological test systems with living cells or organisms that give a global response to the pool of micropollutants present in the sample. In this study we evaluated the cytotoxic/genotoxic potential of 51 different water samples (river, potable, well, lake, and waste waters) potentially contaminated with pharmaceutical and personal care products (PPCP). The samples were evaluated for their genotoxic potential with the bacterial SOS/umu test with Salmonella typhimurium TA1535/pSK1002 and for their cytotoxic potential with mammalian cell based MTT assay with human hepatoma (HepG2) cells. Genotoxicity of seven selected samples was further tested with the comet assay with metabolically competent HepG2 cells. The results from the present study confirmed that biological tests are indispensable for the reliable assessment of cytotoxic and genotoxic potential of surface and waste waters. There is also a need for chemical analytical characterisation of cytotoxic/genotoxic samples in order to identify and quantify the compounds responsible for the cytotoxicity/genotoxicity.