The Use Of Vicia Faba Micronucleus Test And Comet Assay To Monitor The Genotoxicity From Drinking Water

Objective:There are many kinds of chemical contaminants in the drinking water and conventional physical and chemical tests can not fully reflect the health risks of complex mixture exposure. Nowadays, to evaluate genotoxic risk from exposure to drinking water, the concentration is usually the first step in the protocol of bioassays. Plants are unique in their ability to serve as in situ monitor for environmental genotoxicants. The objective of the present study was to investigate the genotoxicity of drinking water disinfection by-products (DBPs) and drinking water samples (raw water, finished water and tap water) collected from a water plant in Wuhan by using Vicia faba MN test and comet assay, and finnaly to explore the feasibility of the two bioassays for in sute monitoring of the genotoxicity from drinking water.Methods:1. The Vicia faba MN test and comet assay were used to assess the genotoxicity of eight representative DBPs, and the genotoxic data obtained in this study were compared with the results from previous genotoxic studies, the maximal DBP occurrence data and WHO guidelines for drinking water quality.2. The raw water, finished water and tap water were collected from a water plant in Wuhan once a month for six months. The genotoxicity of water samples were tested using the two bioassays mentioned above along with some physical and chemical tests. The genotoxic results from raw water, finished water and tap water were compared and the relationship between the genotoxic results and the physical and chemical results were analyzed.Results:1. All eight DBPs showed significant genotoxic effects in Vicia faba comet assay, but only five of them were found genotoxic in Vicia faba MN test. The minimal effective concentrations were ten or one hundred times lower in the Vicia faba comet assay than that in the Vicia faba MN test.2. For five HAAs, the minimal effective genotoxic concentrations in Vicia faba comet assay were lower than in other test systems. For three HANs, the minimum positive concentrations in this assay were closed to that in comet assay using HeLa S3 cells.3. No statistically significant increase in the MN frequencies for dinking water samples was found using Vicia faba MN test in a period of six months monitoring. Finished water (Aug) and raw water (Oct) showed statistically significant increase of genotoxicity in Vicia faba comet assay compared with negative control.4. There was no relationship between the genotoxic results and the physical and chemical results.Conclusion:1. The Vicia faba comet assay has relatively high sensitivity in the testing of the geontoxicity from drinking water DBPs.2. The assay of biologic toxicity is an important part in the monitoring of drinking water quality and can not be replaced by physical or chemical tests.3. Further data are needed to determine whether the Vicia faba comet assay can be applied in the drinking water genotoxicity monitoring.