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

Abstract

Uptake rates of total¹⁴C 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 body¹⁴C concentration factors were 15,800, 1,850, and 180 for phenol, 2,4,5-trichlorophenol, andp-nitrophenol exposures, respectively. Only minor amounts of tissue¹⁴C was parent compound after 28 days of exposure in fish exposed to phenol andp-nitrophenol, while 78.6% of the¹⁴C was parent compound in 2,4,5-trichlorophenol exposed fish. Tissue¹⁴C in fish exposed to 2,4,5-trichlorophenol was eliminated at a faster rate than in fish exposed to phenol orp-nitrophenol. Observed mean¹⁴C 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 total¹⁴C for phenol, 2,4,5-trichlorophenol, andp-nitrophenol, respectively, after 28 days of depuration. The percentage of acetone-unextractable¹⁴C increased from the end of uptake to the end of depuration for phenol and 2,4,5-trichlorophenol, and decreased slightly forp-nitrophenol.¹⁴C contribution from polar metabolites increased relative to total¹⁴C during the depuration phase for 2,4,5-trichlorophenol andp-nitrophenol.