Abstract
The mutagenicities of methyl, ethyl, isopropyl, and butyl methanesulfonates and the corresponding alkyl derivatives of N-nitrosoureas were examined using E. coli B Hs30R tester strain deficient in the excision deoxyribonucleic acid-repair system. Their mutagenic capacities were standardized by converting the experimentally obtained mutation frequencies into those per unit of the concentration-time integrated dose with various dimensions, μM·h, mM·h, and M·h. The mutation frequencies under various conceptual exposure conditions were computed by using those at unit integrated dose, on the assumption that the dose-response relation is linear on a log-log scale. The results indicate that the relative mutagenic capacities of these alkylating agents were strongly dependent on the measure (dimensions) of the mutagenic capacities computed in the present study. Consequently, care is necessary in the quantitative evaluation of mutagenicity, especially when the dose-response relation is not linear but exponential.
