A PHARMACOKINETIC ANALYSIS OF THE UPTAKE OF POLYCHLORINATED BIPHENYLS (PCBs) BY GOLDEN SHINERS

Abstract

A 96-h, static, nonconstant exposure design was used to assess pharrnacokinetic parameters and to identify the rate-limiting process in polychlorinated biphenyl (PCB) uptake by golden shiners (Notemigonus crysoleucus). Fish were exposed individually to I4C-labeled PCBs corresponding to Aroclor 1254 (A1254). After various intervals (2-96 h), fish and water were analyzed for total radioactivity. Uptake of PCBs and decline of the external water concentration were both rapid. A clearance constant-based one-compartment model was used to represent the fish. Model-based equations for PCB concentrations in the fish and in the water were fitted simultaneously to the observed data with the PCNONLINO computer program. The absorption clearance constant was 30.8 m1.h-l .g-' fish, which identified gill blood flow as the uptake rate-controlling process. The model-predicted apparent volume of distribution, V,, and bioconcentration factor, Kb, were 5,280 ml/g fish and 9,059 ml water per gram fish, respectively. The model-predicted elimination rate constant, k,, was 5.84 x h-', corresponding to a t,,? of 4.9 d.

Sensitivity Limits and Ec50 Values of the Vibrio Fischeri Test for Organic Micropollutants in Natural and Spiked Extracts From Sediments

“…Nyholm et al applied the same nonlinear regression model to tests with Scenedesmus subspicatus and Selenastrum capricornutum, measuring the growth inibition toxicity due to K 2 Cr 2 O 7 . Sigmoid curves have often been applied to interprete results of experiments measuring uptake of organic compounds by organisms [29][30][31][32][33][34].…”

Sensitivity limits and EC50 values of the Vibrio fischeri test for organic micropollutants in natural and spiked extracts from sediments

“…Nyholm et al applied the same nonlinear regression model to tests with Scenedesmus subspicatus and Selenastrum capricornutum , measuring the growth inibition toxicity due to K 2 Cr 2 O 7 . Sigmoid curves have often been applied to interprete results of experiments measuring uptake of organic compounds by organisms [29–34].…”

Dynamics of Chlordane Under Nonconstant Exposure Conditions: A Numerical Bioaccumulation Model

“…In natural systems, however, the aqueous concentration may significantly and continuously change over time through dynamic processes of volatilization, sedimentation, and biochemical degradation, such that the steady-state equilibrium conditions are rarely established (Newman and Jogue, 1996). Even in dynamic exposure experiments, it is a constraint to maintain constant aqueous concentrations of chemicals in these systems (Karara and McFarland, 1992). Bioaccumulation itself can also cause significant changes of aqueous concentrations not accounted for in constant concentration models.…”