The Escherichia coli WP2/WP100 rec assay for detection of potential chemical carcinogens

46 chemicals of various classes and structures, including 30 known animal carcinogens, were evaluated for genotoxic effects using the Escherichia coli rec assay with strains WP2 (wild-type) and WP100 (uvrA- recA-) in qualitative and quantitative spot tests and in quantitative suspension tests. The rec assay detected 17 of 30 known carcinogens as genotoxic agents, including mitomycin C and diethylnitrosamine, both negative in the Salmonella/Ames test as utilized in these studies. The rec assay in conjunction with the Salmonella/Ames test detected 20 of 30 known carcinogens as genotoxic agents. Azo/aminoazo carcinogens showed little gentoxicity, and the aromatic amine 2-acetylaminofluorene was non-genotoxic in the rec assay. The rec assay was more effective than pol tests with E. coli strains W3110/p3478 and strains WP2/WP67. Effectiveness of the rec assay was related to the DNA repair-defective nature of the uvrA- recA- genotype of strain WP100.