Mathematical parameters for quantification of mutational responses in bacteria.

This paper introduces a new parameter, derivable from dose-response data for induced mutagenesis in bacteria, that can be used to quantify mutational responses in short-term tests. We called this parameter the mutational response of the bipartite experimental system (agent plus cells). We defined it as being jointly proportional to the efficiency of the mutagen and the sensitivity of the test. We show how this quantity can be used to rank order chemical carcinogens on the basis of their mutagenicity and to determine the strength of any quantitative correlation that may exist between mutagenicity in bacteria and carcinogenicity in rodents. We find that this particular measure of mutational response for 10 direct-acting monofunctional alkylating agents correlates remarkably well with the rodent carcinogenicity of these chemicals measured in terms of their reciprocal TD50 values.