Toxicokinetics and biotransformation of p-nitrophenol in red abalone (Haliotis rufescens)

Red abalone (Haliotis rufescens) were exposed to 3.6 microM (0.5 ppm) 14C-labelled p-nitrophenol (PNP) for 24 h, then were allowed to depurate in clean seawater for another 24 h. Absorption, conditional uptake clearance and elimination rate constants were 0.12+/-0.04 h(-1), 3.2+/-1.1 ml g(-1) h(-1) and 0.05+/-0.02 h(-1), respectively. The sigmoidal shape of the PNP uptake curve suggests a biphasic process. A whole-organism total concentration factor (TCF) of 2.37+/-0.07 was determined from equilibrium tissue and water concentrations, with the highest concentration of PNP plus metabolites found in gill tissue (11.8+/-0.2 nmol g(-1), wet weight). Digestive gland, foot muscle and remaining body tissues accumulated 8.8+/-0.9, 7.7+/-0.6 and 7.5+/-0.6 nmol g(-1) radiolabelled residues, respectively. Abalone depurated 91.6% of absorbed PNP within 24 h, of which 87.5+/-3.1% was unmetabolized parent compound, 13.1+/-3.1% was p-nitrophenylsulfate, 0.32+/-0.09% was p-nitroanisole, and 0.14+/-0.07% was p-acetamidophenol.