SOS INDUCTION IN ESCHERICHIA-COLI AND SALMONELLA MUTAGENICITY - A COMPARISON USING 330 COMPOUNDS

To examine the concordance of two microbial genotoxicity short-term as says, 330 experimental results for the SOS chromotest using tester str ain Escherichia call PQ37 were compared with the results of the Salmon ella/mammalian microsome mutagenicity assay with Salmonella typhimuriu m TA97, TA98, TA100, TA102, TA104, TA1535, TA1537 and/or TA1538. With respect to qualitative features, the concordance between SOS chromotes t and Salmonella mutagenicity test results was 86.4% (sensitivity, 78. 6%; specificity, 100%; chi(2) = 188.6). None of the non-mutagens (N = 120) were able to induce the SOS system. Additionally, 45 of the 210 S . typhimurium mutagens (21.5%) did not induce the SOS repair system. O n closer examination, the majority of these 45 compounds (84%) were mu tagens with activities between 0.001 and 10 rev/nmol. Even though the experimental protocols of both systems were not standardized, the corr elation coefficient for the experimental results of the two test syste ms was 0.7 for the 330 chemicals. Except for aliphatic epoxides (r = 0 .47), the mutagenicity/SOS induction correlations for congeneric data sets (polycyclic aromatic hydrocarbons, nitroarenes, nitroarenofurans, mycotoxins) were even better (r = 0.72-0.95). Additionally, computer automated structure evaluation (CASE) analyses of the nature of the st ructural determinants associated with each endpoint indicate extensive homologies. The data can be taken to indicate that the two phenomena reflect common mechanisms of action.