Genotoxicity of surface water treated with different disinfectants using in situ plant tests.

Disinfection of surface drinking water, in particular water chlorination, results in many by-products with potential genotoxic and/or carcinogenic activity. In the present study, we evaluated the genotoxicity of surface water after treatment with different disinfectants by means of in situ plant genotoxicity assays (micronucleus and chromosomal aberration tests) which can detect both clastogenic and aneugenic effects. The study was carried out at a pilot plant using lake water after sedimentation and filtration. This water supplied four stainless steel basins: three basins were disinfected with sodium hypochlorite, chlorine dioxide, and peracetic acid and the fourth basin containing untreated lake water was used as a control. Plants were exposed in situ in the basins. The study was carried out using water collected in different seasons over a period of about 1 year in order to assess the treatments in different physical and chemical lake water conditions. The micronucleus test in root cells of Vicia faba (Vicia faba/MCN test) revealed genotoxicity in many samples of disinfected water. The micronucleus test in Tradescantia pollen cells and the chromosome aberration test in root cells of Allium cepa showed genotoxic effects only in some disinfected samples, but also revealed genotoxicity in raw water. The results of the study indicated that the Vicia faba/MCN test was the most sensitive plant assay for disinfected water and that peracetic acid disinfection produced similar or lower genotoxicity than sodium hypochlorite or chlorine dioxide treatment.