Genotoxicity of the Yamuna River water at Okhla (Delhi), India

Water samples from the Yamuna River at Okhla (Delhi), India, were concentrated using XAD resins (XAD-4 and XAD-8) and liquid-liquid extraction procedures. Gas chromatographic analysis of liquid-liquid extracted water samples revealed the presence of the pesticides DDT, BHC, dieldrin, endosulfan, aldrin, 2,4-D, dimethoate, methyl parathion, and malathion at concentrations of 14, 25, 2.1, 114, 0.9, 0.6, 0.9, 1.7, and 1.9 ng/L, respectively. The genotoxicity of the extracted water samples was evaluated with the Ames Salmonella/mammalian microsome test, DNA repair-defective mutants, and bacteriophage lambda systems. The results of the Salmonella test demonstrated that the XAD-concentrated water samples had maximum mutagenicity with the TA98 strain both with and without metabolic activation. However, the liquid-liquid-extracted water samples were also found to be mutagenic with one or more of the Ames tester strains, but to a lesser extent as compared with XAD extracts. The damage brought about in the DNA repair-defective mutants in the presence of XAD-concentrated water samples was found to be markedly high as compared with that liquid-liquid-extracted water samples at the dose level of 20 mu l/mL culture. All mutants invariably exhibited significant declines in their colony-forming units as compared with their isogenic wild-type counterparts. Survival decreased by 86.3 and 75.5% in the polA(-) strain after 6 h of treatment with XAD-concentrated and liquid-liquid-extracted water samples, respectively. A significant decrease was also observed in the survival of bacteriophage lambda when treated with the test samples. Mutagenic responses of the liquid-liquid-extracted water samples may not necessarily reflect the mutagenicity of existing pesticides in the test water, because some other organic pollutants might accompany the pesticides in the extract. (c) 2004 Elsevier Inc. All rights reserved.