MATHEMATICAL PARAMETERS FOR QUANTIFICATION OF MUTATIONAL RESPONSES INBACTERIA

This paper introduces a new parameter, derivable from dose-response da ta for induced mutagenesis in bacteria, that can be used to quantify m utational responses in short-term tests. We called this parameter the mutational response of the bipartite experimental system (agent plus c ells). We define it as being jointly proportional to the efficiency of the mutagen and the sensitivity of the test. We show how this quantit y can be used to rank order chemical carcinogens on the basis of their mutagenicity and to determine the strength of any quantitative correl ation that may exist between mutagenicity in bacteria and carcinogenic ity in rodents. We find that this particular measure of mutational res ponse for 10 direct-acting monofunctional alkylating agents correlates remarkably well with the rodent carcinogenicity of these chemicals me asured in terms of their reciprocal TD50 values.