In the Ames test, with the exception of the p-toluenesulfonic acid ethyl and iso-butyl esters, all compounds came out positive in Salmonella strain TA100. Methanesulfonic iso-propyl, sec-butyl and benzenesulfonic acid iso-propyl ester also showed mutagenic potential in strain TA98. In general, differences between results seen in Ames tests performed with or without metabolic activation were rather small.
In L5178Y mouse lymphoma cells, benzenesulfonic acid n- and iso-butyl ester and p-toluenesulfonic acid iso-butyl ester did not increase the number of cells containing micronuclei. The other esters were positive in this micronucleus test; however, methanesulfonic acid iso-butyl ester was found to be only weakly positive at excessively cytotoxic concentrations. These compounds were generally found to be more potent with regard to micronucleus induction when tested without metabolic activation (20 h treatment).
In conclusion, the iso-propyl esters of the three sulfonic acids under study were found to be the strongest mutagens, either when tested in the Ames test or the micronucleus assay, whereas p-toluenesulfonic acid iso-butyl ester was the only compound shown to be devoid of a genotoxic potential in both tests.