pH-sensitive mutagenic activity in ozone-treated 1,2-dimethylhydrazine in the Salmonella/microsome assay.

Treatment with ozone inactivates the mutagenicity of many carcinogens in aqueous solution. The colon carcinogen, 1,2-dimethylhydrazine (DMH) has been reported an exception; ozone treatment converts dimethylhydrazine from a non-mutagen into a mutagen. In the Salmonella/microsome assay, the mutagenicity of ozone-treated dimethylhydrazine was dependent on pH. The ozonation product was a strong mutagen in acidic solution but was not mutagenic in basic solution. The mutagenicity of the acidic ozonation product was inactivated by raising the pH of the solution. Unlike untreated dimethylhydrazine, its ozonation product in basic solution was not converted to a mutagen in this ozone-low pH system.