Effects of feeding and temperature on uptake, elimination and metabolism of benzo(a)pyrene in the bluegill sunfish ( Lepomis macrochirus)

Bluegill sunfish ( Lepomis macrochirus) were exposed to [ 14C]benzo(a)pyrene (BaP) in a flow-through system to examine the effects of temperature and feeding regime on BaP uptake and elimination and extent of biotransformation within the fish. The rate of uptake of BaP at 23°C was twice as fast in fish fed during aqueous exposure than in those denied food; however, the rate of elimination of radioactivity was 10 times greater in the fed fish. BaP was rapidly metabolized to polar and nonpolar metabolites, although 40 to 50% of the radioactivity in the fish appears to be covalently bound to cellular constituents. The rate of conversion of BaP to polar metabolites was also accelerated by feeding. Because animals in nature usually have food available, care must be exercised in using, applying, and extrapolating results of laboratory experiments in which food is withheld. Temperature is an environmental variable that had a significant effect on the uptake, elimination, and metabolic fate of organic contaminants. Both BaP uptake (5.8-fold) and 14C elimination rates (3.6-fold) at 13°C were lower than in fed fish exposed at 23°C. The metabolite profiles indicate that biotransformation of BaP is also much slower at the colder temperature.