Evaluation of the Genotoxic and Mutagenic Potential of River Challawa Impacted by Industrial Effluents Using Ames and Comet Assays

Several potential genotoxins found in water samples arise from anthropogenic activities which poses serious environmental concerns worldwide. The use of toxicity tests to evaluate the quality of streams add value by providing site-specific toxicological data. The objective of this study was to evaluate the genotoxic potential industrial effluents from the Challawa Industrial Area released into the river as a point source. This study aimed to identify the extent of industrial effluent’s mutagenicity and genotoxicity to Salmonella typhimurium strains and freshwater mussels using two assays, the Ames test, and the comet assay respectively. Water and mussel samples were collected from four (4) sampling sites along River Challawa on the basis of the different activities taking place. The Ames test without metabolic activation using Salmonella typhimurium TA98 and TA100 strains showed site-specific mutagenicity in the water samples tested. Hemolymph was extracted from freshwater mussels and used to assess DNA alterations using comet assay. Significant levels of tail DNA percentages as a result of migration of damaged DNA in hemocytes of freshwater mussels were observed. Genotoxic assessment of the water in freshwater mussels using comet assay also revealed mild DNA damages. Similarly, significant levels of SOD, CAT and GSH were recorded which indicates antioxidant response as a result of heavy metal exposure. These results indicate that mussels stimulated the increase in antioxidant enzyme activities as an adaptive response to oxidative damage by metals. The findings therefore showed that a combination of physicochemical analysis along with the toxicity assessment (using bioassays) at genetic levels would provide valuable and more realistic information about the toxicity of chemical pollutants present in the water samples.