Selection of genotoxicity tests for risk assessment of effluents

Genotoxicity is one of the parameters within the whole effluent environment al risk procedure, an effect-based procedure developed in the Netherlands t o supplement classical substance-specific risk assessment of effluents. To implement the genotoxicity parameter, one or more tests have to be selected for routine use on effluents, This paper deals with problems and considera tions encountered during selection of genotoxicity tests. Tests were judged on: relevance, validation, detected genotoxic lesions, quantitative sensit ivity, convenience, and cost-efficiency. Based on criterion detected genoto xic lesions and on criteria convenience and cost-efficiency, it is recommen ded to use at least a bacterial test which makes use of detection of the SO S pathway which is induced upon the occurrence of DNA damage. The criterion quantitative sensitivity is used in a laboratory study on effluent samples to select the most appropriate bacterial SOS pathway test. The range of de tected genotoxic endpoints can be expanded by also including a more expensi ve test that detects clastogenesis and/or aneuploidy, In that case it seems wise first to establish the added value of such a test for the risk assess ment of effluents, before deciding on further use. Furthermore, it is concl uded that the presently available information on relevance and validation i s of limited use for test selection. Finally, recommendations are made on t est protocols and on pretreatment of effluent samples to optimize genotoxic ity tests for effluent samples. Recommendations include data analysis, dete ction of the interference of cytotoxicity, extraction, the use of S9, conce ntration procedures, and filtration. (C) 2000 by John Wiley & Sons, Inc.