Mutagenicity testing of extracts from petroleum and coal tar pitches

Dimethylsulfoxide extracts of Ashland-240 petroleum pitch and Barrett M-30 coal tar pitch were tested for mutagenicity using Salmonella histidine reversion assay (Ames test). Four strains of Salmonella were employed. The strains sensitive to frameshift mutations were reverted, with the coal tar pitch indicating a three fold greater mutagenic activity than the petroleum pitch. Metabolic activation with rat liver extracts was required. As a prescreen to aid investigators in ordering their priorities, the short-term tests appear to be a valid approach to testing the large number of hazardous compounds and complex mixtures that man encounters in his environment.