Correlation of mutagenic and dermal carcinogenic activities of mineral oils with polycyclic aromatic compound content

Mutagenicity, polynuclear aromatic compound content, and skin carcinogenicity were compared for a series of complex oil mixtures derived from the refining and processing of petroleum. Mutagenicity in a modified Ames Salmonella assay showed an excellent correlation with carcinogenicity, as determined in a mouse skin-painting bioassay, for oil samples with median boiling points (defined as the temperature at which 50%/volume of an oil sample is recovered as condensate during distillation--50% recovered) above approximately 500 degrees F. A significant correlation was also observed between the 3-7 ring polycyclic aromatic compound (PAC) content and both mutagenic and carcinogenic potencies for samples ranging from those with median (50% recovered) boiling points above approximately 500 degrees F to those with initial boiling points of approximately 1070 degrees F. These results show that both PAC content and mutagenicity are predictive of dermal carcinogenic activity and indicate that PAC components are largely if not entirely responsible for both the carcinogenic and mutagenic activities.