Gary R. Blackburn

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.

Processes for Reducing the Mutagenicity of Refinery Streams and Coal Tars via °C3-Alkylation

Abstract Processes for reducing the mutagenicity of refinery streams and coal tars containing polynuclear aromatic compounds (PAC) are described. The investigation was based on the supposition that the reduced mutagenic activity of some refinery streams (relative to cracked stocks and coal tars) was related to the degree of alkylation of the PAC stream components. Much of the development work was carried out using benzo[a]pyrene (BaP) as a model surrogate for the PAC responsible for the mutagenic potency of refinery streams and coal tars. Using Friedel-Crafts procedures, the mutagenic activity of a number of refinery streams and coal tar products was significantly reduced or completely eliminated when reacted with a C3-, C4-, or C5-alkylating agent. Recent work has turned toward adapting the laboratory-based chemistry to refinery-based chemistry using heterogeneous catalysis (acid clay/pillared catalysts/zeolites).