Multi-bioassay approach for assessing the potency of complex mixtures of polycyclic aromatic hydrocarbons

The chick embryotoxicity screening test (CHEST) and the Salmonella/microsom e bioassay were used to evaluate embryotoxic and mutagenic endpoints from c rude coal tar (CT) and its fractionated polycyclic aromatic hydrocarbon (PA H) mixtures (designated as A, B, C, D and E). In the CHEST assay, CT and PA H mixtures were injected into the egg yolk. A dose-dependent increase in em bryo mortality was observed for all fractions. The E fraction resulted in 4 7% embryo mortality at a dose of 0.125 mg/kg and was more toxic than CT. At a dose of 1 mg/kg, 85-100% embryonic deaths occurred in fractions C and D and these two fractions were more potent than fractions A and B. The main v isual toxic manifestations were liver lesions, discoloration of the liver, and edema. Both CT and fractionated PAH mixtures were also tested in the Sa lmonella/microsome plate incorporation assay with Salmonella typhimurium st rain TA98 and were evaluated with and without metabolic activation at five dose levels. In the presence of S9, the CT and fractions C, D and E induced a dose-dependent positive response. Results from the Salmonella/microsome assay were in good agreement with findings from the CHEST assay suggesting that these two bioassays in combination may facilitate the rapid detection and ranking of complex PAH mixtures. (C) 1999 Elsevier Science Ltd. All rig hts reserved.