The cocarcinogenic and tumor promoting activities of asphalt fume fractions were compared with those of benzo(a)pyrene (50328) (BaP) in male C3H/HeH-mice, and an attempt was made to evaluate the direct tumorigenic activity of the fractions singly and in a variety of combinations. The tumorigenic responses to neat asphalt fumes were studied in male C3H/HeJ-mice and Sencar-mice. Type-III roofing asphalt was heated at 316 degrees-C and the fume condensates collected and fractionated, and then applied dermally to mice twice a week for up to 24 months. Condensed neat asphalt fumes produced similar and statistically significant increased tumor yields of papillomas and carcinomas in both strains as compared to respective vehicle controls. Recombination of all fractions resulted in a tumor response similar to neat asphalt fumes. Among individual fractions, fraction-C, which included cycloalkenones and/or alkadienones, alkylated phenylethanones, dihydrofuranones, dihydroindenones, isobenzofuranones, hydroxybenzenethiols, pyrenes and/or fluoranthenes, chrysenes, and tricarbocyclic fused ring thiophenes was the most potent, followed by fraction-B, which included alkylated benzothiophenes, dibenzonaphthothiophenes and/or naphthothiophenes, anthracenes and/or phenanthrenes, fluorenes, pyrenes and/or fluoranthenes, benzofurans and dibenzofurans and fluorenones. The other single fractions did not possess significant tumorigenic activity. Raw unheated asphalt produced a few tumors in C3H-mice, but no tumors were noted when raw asphalt was heated to 316 degrees and applied, with the fumes permitted to escape. The hypothesis that cocarcinogens and/or tumor promoters are responsible for at least a portion of the carcinogenic activity of roofing asphalt fume condensate in mice was not confirmed by the data in this report. Based on the data available from this bioassay it appears that the tumorigenic activity of the neat asphalt fume condensate was primarily due to two fractions, and no evidence was found for cocarcinogenicity or tumor promotion activity for selected fractions.