Petroleum distillates suppress in vitro metabolic activation: higher [S-9] required in the Salmonella/microsome mutagenicity assay.
To determine if standard conditions used in the Salmonella/mammalian microsome mutagenicity assay could reliably screen complex petroleum samples, two high-boiling (700-1,070 degrees F) distillates and their separated aromatic fractions were tested. The initial mutagenic activities were inconsistent with the samples' known polyaromatic hydrocarbon (PAH) contents and observed potencies in a dermal carcinogenesis bioassay. A significant mutagenic response was observed only at S-9 concentrations 5 to 10 times higher than those used in the standard assay, supporting the use of elevated levels of S-9 in the Salmonella/microsome assay to assess the carcinogenic potential of petroleum-derived materials. All four samples masked the expected mutagenic activity of added PAHs (benzo[a]pyrene and perylene). Data suggested that petroleum distillates suppress the functional efficacy of the S-9; possible mechanisms are discussed.
D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity; D001711:Biotransformation / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects*; D009152:Mutagenicity Tests / Q000379:methods*; D010569:Perylene / Q000633:toxicity; D010578:Petroleum / Q000633:toxicity*; D051381:Rats; D012486:Salmonella typhimurium / Q000187:drug effects
D010578:Petroleum; D001564:Benzo(a)pyrene; D010569:Perylene