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

Red abalone (Haliotis rufescens) were exposed to 3.6 μM (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