Ecotoxicological studies using modified ames bioassay

Health and environmental risk assessment of river and wastewaters based on single chemicals is limited by the number of chemicals that can be identified and to those chemicals for which toxicity and mutagenicity data exist. In this study Salmonella/microsome mutagenicity assay was evaluated as a potentially useful biomonitoring system for river water and wastewater. Standard assay was modified to allow testing of up to 2.5 ml of nonconcentrated water sample and by introducing 90 minutes of preincubation. Mutagenic activity of nonconcentrated samples was compared to the mutagenic activity of XAD-2 extracts of the same samples. Eighteen river water samples, two wastewater samples and one sample of water leaking from municipal waste dump were tested. Mutagenicity was detected in three nonconcentrated river water samples, both nonconcentrated wastewater samples and in the sample of the water leaking from the municipal waste dump. The mutagenic profiles of nonconcentrated samples were different from the mutagenic profiles of the XAD-2 extracts. The modified method was sensitive enough to detect mutagens present in more polluted river water (class IV), in wastewaters and in water leaking from the municipal dump. For the assessment of the impact of the mutagenic river and wastewaters on the environment, calculations from the results of nonconcentrated samples should be used as it seems that calculations from the results of the extracts are leading to the underestimation of mutagenic potency. Mutagenic profiles of the extracts are a useful guide for further chemical and biological analysis to trace the sources of the mutagens and to introduce measures to reduce them. Copyright (C) 1996 IAWQ.