Uptake, elimination, and metabolism of three phenols by fathead minnows

Uptake rates of total 14C in fathead minnows (Pimephales promelas) exposed to sublethal concentrations of radiolabeled test compounds followed the order: phenol > 2,4,5-trichlorophenol > p-nitrophenol. Mean whole body 14C concentration factors were 15,800, 1,850, and 180 for phenol, 2,4,5-trichlorophenol, and p-nitrophenol exposures, respectively. Only minor amounts of tissue 14C was parent compound after 28 days of exposure in fish exposed to phenol and p-nitrophenol, while 78.6% of the 14C was parent compound in 2,4,5-trichlorophenol exposed fish. Tissue 14C in fish exposed to 2,4,5-trichlorophenol was eliminated at a faster rate than in fish exposed to phenol or p-nitrophenol. Observed mean 14C depuration half-lives for lower and higher exposures combined were 387, 150, and 12 hours for phenol, p-nitrophenol, and 2,4,5-trichlorophenol, respectively. Parent compound comprised 1.5, 2.7, and 0.7% of total 14C for phenol, 2,4,5-trichlorophenol, and p-nitrophenol, respectively, after 28 days of depuration. The percentage of acetone-unextractable 14C increased from the end of uptake to the end of depuration for phenol and 2,4,5-trichlorophenol, and decreased slightly for p-nitrophenol. 14C contribution from polar metabolites increased relative to total 14C during the depuration phase for 2,4,5-trichlorophenol and p-nitrophenol.