Evaluation of the relationship between PAH content and mutagenic activity of fumes from roofing and paving asphalts and coal tar pitch.

Fume condensates from asphalt and coal tar pitch were evaluated to determine if polycyclic aromatic hydrocarbon (PAH) composition, crude oil source, or temperature at which the fume was generated correlated with mutagenic activity. The fume condensates were tested for mutagenic activity using a modified Ames Test. Benzo[a]pyrene (BP) and other PAHs were detected in all samples. The concentration of BP in coal tar pitch was 18,100 ppm while the concentration in asphalt was less than 6 ppm. Coal tar fumes contained between two and three orders of magnitude more BP, as well as other PAH species, than asphalt fumes. Coal tar fume condensates were also approximately 100 times more mutagenic than those of asphalt. Generation temperature, crude oil source, and/or process conditions affected the PAH concentrations but not the mutagenicity in roofing asphalt fume condensates. With paving asphalt fumes, PAH content and mutagenicity varied with crude oil source but not with processing conditions; due to limited data, it was not possible to determine the effect of generation temperature. Coal tar pitch fumes generated at 316 degrees C contained significantly higher concentrations of PAHs than those generated at 232 degrees C and the mutagenic activity generally paralleled the PAH content. A subset of the paving asphalts demonstrated good correlation between mutagenicity and three- to seven-ring PAH content. These results indicate that asphalt fumes are far less mutagenic than coal tar fumes. Asphalt fumes differ in their ability to induce mutagenic activity, and, most likely, in their potential carcinogenicity.