The SOS Chromotest, a colorimetric assay based on the primary cellular responses to genotoxic agents.

The SOS Chromotest is a quantitative bacterial colorimetric assay for genotoxins. Substantial validation is now available. We describe the tester strain as well as results of validation studies. Comparison of the results with those obtained in the Mutatest (the Ames test) showed that most (90 percent) of the mutagenic compounds were also SOS inducers. For these compounds, a quantitative correlation was observed between the mutagenic potency and the SOS-inducing potency (SOSIP). The present data indicate that the SOS Chromotest has many practical advantages and may be used as a primary screening tool or as part of a battery of short-term tests for carcinogens. Theoretical considerations on the relation between the SOSIP and the mutagenic potency are briefly discussed.