The metabolic fate of benzo[a]pyrene in rats after inhalation.

Male Fischer-344 rats were exposed by inhalation to [3H]benzo[a]pyrene (BP) aerosols (100 micrograms/l; activity mass aerodynamic diameter, 1-2 microns) for 30 min. The concentration of organic-soluble, water-soluble and covalently-bound radioactivity was determined in rat lung, liver and kidney at 0.5, 6 and 24 h after exposure. The total amount of [3H] BP decreased rapidly in the lung as a function of time after exposure. At 0.5 h after exposure, the organic-soluble radioactivity accounted for approx. 70% of the total radioactivity in the lung. The organic-soluble radioactivity in the liver and kidney was 24% and 21%, respectively, at 0.5 h after exposure. The organic-soluble radioactivity decreased in the lung to approx. 10% of the total radioactivity by 1 day after exposure; the percent of total lung radioactivity bound to tissue at this time was 80%. Thin-layer chromatography (TLC) of extracts indicated that the organic-soluble radioactivity in the lung at 0.5 h after exposure was comprised primarily of BP, 3-OH-BP, 9-OH-BP and quinones of BP. In contrast, the organic-soluble radioactivity in the liver and kidney at 0.5 h after exposure were primarily polar metabolites, dihydrodiols, and BP. In all organs TLC profiles of the organic-soluble fraction at 6 h and 24 h after exposure were not significantly different from the 0.5 h organic soluble profiles except for the lower amount of BP.