Comparison of two microbial short-term genotoxicity assays — the Salmonella/mammalian microsome assay and the SOS-chromotest with Escherichia coli PQ37

Abstract

Three short-term assays (the SOS chromotest, the Ames fluctuation test and the newt micronucleus test) were used to evaluate the genotoxicity of seven chemicals (4-nitroquinoline 1-oxide, potassium dichromate, formaldehyde, sodium hypochlorite, benzo[a]pyrene, cyclophosphamide and 2-naphthylamine). In the SOS chromotest, all seven compounds except sodium hypochlorite and cyclophosphamide were found to induce primary DNA damage in E. coli. With the Ames fluctuation test, all seven chemicals except sodium hypochlorite showed mutagenic activity on Salmonella typhimurium TA100, TA102 or TA98. The newt micronucleus assay detected a clastogenic effect of all seven compounds except formaldehyde on the peripheral blood erythrocytes of Pleurodeles waltl larvae.For each compound, the sensitivity of the tests was compared; (1) the SOS chromotest is the least sensitive assay in every case, (2) the Ames fluctuation test is the most sensitive assay for studied chemicals with direct genotoxic effect and (3) the newt micronucleus assay is the most sensitive test for tested compounds with indirect genotoxic activity.The potential contribution of these three tests in the monitoring of water genotoxicity is discussed.