The Genotoxicity Monitoring and Risk Assessment of Water Environment in a Region
|School||Chinese Academy of Environmental Science|
|Keywords||Genotoxicity Micronucleus test Micronucleus rate Shallow groundwater Water Environment Cancer risk Gene mutation test Water samples genotoxicity Chromosomal aberrations micronucleus Deep groundwater Mutagenicity Comet Assay Genetic Toxicology Mutagenic activity Micronucleus Toxicity testing Mutagenicity mutagenic|
Object:To provide scientific basis for evaluating the genotoxicity and carcinogenic risk of a river basin through the micronucleus test and SOS/umu test.Method:In the selected study area, we collected7surface water samples and41shallow groundwater samples in9selected townships along the river in2011. And7surface water samples,44shallow groundwater samples and7deep groundwater in7selected townships in2012Two liters water was collected for each sample, then concentrated by HLB Solid phase extraction column, eluted with acetone and dissolved in DMSO to50μL. Human peripheral blood lymphocyte micronucleus test (cytokinesis block method) and SOS/umu test were employed to measure the genotoxicities of water samples. To characterized the genotoxicity and carcinogenetics, the rate of micronucleus(MN%o) and PI value were used for micronucleus test, and the IU of β-Galactosidase activity, the genotoxicity strength R-value, TEQ4-NQO Value and carcinogenic risk for the SOS/umu test.Results:The results showed that both surface water and shallow groundwater in the study area showed genotoxicity to a certain dgree, the specific results are as followings:(1) The rate of MN‰and PI value were22.3‰±2.81‰and4.36±0.41for surface water, respectively, in2011, which indicated severe water pollution. MN‰for shallow groundwater was9.6‰±3.56‰and PI value was2.04±0.33, which suggested that there was light pollution. For the shallow groundwater near the riverbank, the rate of MN‰and PI value were11.9‰±2.74‰and2.63±0.13, respectively, which was as1.46times and1.45times high as those for the samples far away from the riverbank, respectively.(2) The rate of MN‰and PI value were19.3‰±1.9‰and4.01±0.41for surface water in the study area respectively, in2012, which indicated severe water pollution. Fr the shallow groundwater, MN‰was9.0‰±2.43‰and PI value was2.01±0.59, which suggested that there was light water pollution. MN‰and PI value were4.4‰±0.45‰and1.21±0.32for deep groundwater, respectively, which showed no pollution roughly. For the shallow groundwater near the riverbank, the rate of MN‰was9.8‰±2.45‰, which was as1.25times and2.28times high as those for samples far away from riverbank and deep water samples, respectively. And PI value was2.63±0.13, which was0.30times and1.28times higher than those for samples far away from riverbank and deep water samples respectively.(3) Without in vitro metabolic activation system, the results of SOS/umutest showed that IU and R value of surface water samples in the study area in2011was367.08±93.89and2.69±0.69, which indicated positive response. IU and R value of shallow groundwater was243.24±61.97and1.52±0.40, which presented negative response. For shallow groundwater, the samples with positive results accounted for20%. For the shallow groundwater near the riverbank, IU and R value were262.55±107.07and1.81±0.51, respectively, which were as1.3times and1.4times as high those for samples far away from riverbank.(4) The TEQ4-NQO value of surface water samples and shallow groundwater were0.410±0.185and0.054±0.033, respectively. For the shallow groundwater near the riverbank, the TEQ4-NQO value was0.049±0.036, which was1.0times higher than those for the samples far away from the riverbank which TEQ4-NQO value was0.025±0.023. The cancer risk level of surface water samples and shallow groundwater were3.62E-06±1.32E-06and3.99E-07±3.93E-07, respectively. For the shallow groundwater near the riverbank, the cancer risk level was3.54E-07±1.28E-07, which was0.4times as high as those for the samples far away from the riverbank.(5) The results of micronucleus test and SOS/mu test showed the very strong positive corelationship. For the shallow groundwater in2011, the correlation coefficient of the PI value calculated from micronucleus test and R value from SOS/umu was0.855, and0.938of the PI value from micronucleus test and TEQ4-NQO value from SOS/umu.Conclusion:The water environment in study region was polluted relatively serious, and slightly higher than the results of other reported region. The genotoxicity and caner risk level of surface water was higher than the shallow groundwater, and significantly higher than deep water. The genotoxicity and cancer risk of shallow groundwater presented a downward trend with increasing distance from the riverbank. The cancer risk for the water samples in study region was in a safe level, however, the water quality and safety should be of concerning. The results of Micronucleus assay in human peripheral blood lymphocytes(Cytokinesis Block Micronuleus,CBMN) and SOS/umu test were in High consistent, which indicated either can be selected for the follow-up work of detecting the genotoxicity in study region, we recommended SOS/umu test.