SKIN CARCINOGENICITY OF CONDENSED ASPHALT ROOFING FUMES AND THEIR FRACTIONS FOLLOWING DERMAL APPLICATION TO MICE

Condensed roofing asphalt fumes, generated at 316 degrees C, were coll ected by cold trap condensation and fractionated by preparative high p erformance liquid chromatography. Chemical classes in each of the frac tions (A-E) were identified by gas chromatography/mass spectroscopy. T he fractions, various combinations of fractions, the raw and heated as phalt, the neat asphalt fume and the reconstituted asphalt were tested for carcinogenicity, and three fractions were tested for cocarcinogen icity and tumor promotion with benzo[a]pyrene (BaP). The skin applicat ion carcinogenesis bioassay was conducted by twice weekly application of test materials in 0.05 ml of acetone/cyclohexane (1:1) for 104 week s to 40 groups of male C3H/HeJ mice (30/group). Fractions were applied at a mass in proportion to their amount in the neat asphalt fumes. In addition, the neat asphalt fume was tested on Sencar mice to determin e if this strain was more susceptible to the carcinogenic effects of t he fumes. Condensed neat asphalt fumes produced similar and statistica lly significant increased tumor yields of papillomas and carcinomas in both strains as compared to respective vehicle controls. Recombinatio n of all fractions resulted in a tumor response similar to neat asphal t fumes. Among individual fractions, C was most potent, followed by B. The other single fractions were without significant tumorigenic activ ity. Combinations containing fractions B and C were most active among the mixtures that were assayed and no evidence of enhancement of tumor igenesis in the mixtures was found. No significant cocarcinogenic or t umor promoting activity was observed with fractions A, D, or E and BaP . Raw unheated asphalt produced a few tumors in C3H mice, but no tumor s were seen when raw asphalt heated to 316 degrees C, with the fumes p ermitted to escape, was applied. (C) 1997 Elsevier Science Ireland Ltd .