Uptake, elimination, and metabolism of¹⁴C-picric acid and¹⁴C-picramic acid in the American oyster (Crassostrea virginica)

The uptake, elimination, and metabolism of¹⁴C-picric acid (2,4,6-trinitrophenol) and¹⁴C-picramic acid (2-amino-4,6-dinitrophenol) were determined for the American oyster (Crassostrea virginica). The oyster accumulated statistically significant amounts of picric and picramic acid above two exposure concentrations in a biphasic uptake pattern. The 42-day¹⁴C-accumulation factors (¹⁴C-AF) for American oysters continuously exposed to picric acid concentrations of 0.45 mg/L and 0.05 mg/L were 65.5 and 16.5, respectively. Oysters exposed to 0.24 mg/L and 0.02 mg/L picramic acid had 42-day¹⁴C-AFs of 49.3 and 86.8, respectively. Steady state bioconcentration factors could not be calculated (hence the use of the term¹⁴C-AF), because 1) it is not clear that an equilibrium was reached for either picric or picramic acid uptake during the 42 days of exposure, particularly for the high picric acid and low picramic acid exposure concentrations, and 2) some of the parent compounds were metabolized to other compounds. No statistically significant elimination of picric acid was observed during the 14-day elimination study. Depuration of picramic acid was biphasic. Approximately 40% of the accumulated compound was eliminated by the second day of depuration during the initial phase for both the high and low concentrations of picramic acid, while no elimination occurred during the secondary phase. A small percentage of picric and picramic acid was metabolized by the oyster or its bacterial flora. There was no apparent difference between the concentration of the compounds per gram of tissue in the muscle, gill, mantle, or body mass.