The initiator tRNA acceptance assay as a short-term test for carcinogens. 2. Results with ten compounds selected by the International Programme on Chemical Safety for the evaluation of short-term tests for carcinogens.

Eight carcinogenic and two non-carcinogenic compounds that are difficult to detect by short-term tests (acrylonitrile, benzene, benzoin, caprolactam, diethylhexylphtalate, diethylstilbestrol, hexamethylphosphoramide, phenobarbital, safrole and o-toluidine) were tested independently in Prague and in Heidelberg by the newly developed initiator tRNA acceptance assay. Seven out of eight tested carcinogens gave a positive response in this assay, only safrole showed a false negativity in both laboratories. Both non-carcinogenic compounds, benzoin and caprolactam, exhibited no activity. An absolute qualitative agreement was found with all compounds tested between the results of both laboratories. With the exception only of phenobarbital (intermediate activity in Prague and low in Heidelberg) the quantitative results obtained in both laboratories were comparable. The initiator tRNA acceptance assay thus appears to be a reliable short-term test for carcinogenicity with good reproducibility.