Evaluation of a First-Order Model for the Prediction of the Bioaccumulation of PCBS and DDT From Sediment Into the Marine Deposit-Feeding Clam Macoma Nasuta

Abstract

Abstract-A first-order model for predicting contaminant bioaccumulation from sediments into benthic invertebrates was validated using a marine deposit-feeding clam, Macoma nasuta, exposed to polychlorobiphenyl (PCB)-spiked and dichlorodiphenyltrichloroethane (DDT)-contaminated sediments. Contaminant uptake and depuration were analyzed following short-term and long-term sediment exposures. Uptake and depuration rates were used to predict steady-state bioaccumulation factors (BAFs) and exposure times needed to attain steady state. These predictions were compared to observed steady-state BAFs. Estimating elimination and uptake rates from depuration and short-term uptake experiments was an accurate means of predicting BAFs for some PCBs (log octanol-water partition coefficient, K ow , Ͻ7) but was not as accurate for predicting DDT BAFs. The exposure time need to attain steady state was poorly predicted by the model. The results demonstrated that a standard 28-d bioaccumulation test estimated steadystate tissue residues within two-fold and was a better predictor than the model for the BAFs of superlipophilic PCBs (log K ow Ͼ7). Differences in contaminant bioavailability were noted between field-contaminated (DDT) and laboratory-spiked (PCB) sediments.

Determining Steady-state Tissue Residues for Invertebrates in Contaminated Sediment

“…Overall, data obtained from this study and the available literature (e.g., Boese et al 1997) indicate that the standard 28-d test duration was inadequate for DDTs to achieve the requirement of at least 80% of the steady state in both N. virens and M. nasuta. Thus, use of SSCFs for 28-d tissue residues for DDTs is recommended.…”

“…Uptake rates for PCB analytes in Macoma nasuta for this study and from spiked sediments in Boese et al (1997) Figure 12. Elimination rates for PCB analytes in Macoma nasuta for this study and from spiked sediments in Boese et al (1997) Tables Table 1. Test conditions for the standard 28-d bioaccumulation tests (USEPA/USACE 1998) and the steady-state tests conducted in this study, modified from Lee et al (1993) Table A4. Sediment chemistry data for polycyclic aromatic hydrocarbons (PAHs) (g/kg)............... 56 Table B1.…”

“…For 2,3,7,8-TCDD, a factor of four has been suggested to adjust 28-d N. virens tissue residues to the steady-state concentration used in risk estimations while a factor of one (i.e., no correction) is used for the clam M. nasuta based on data from Pruell et al (1990). More recent work (e.g., Boese et al 1995Boese et al , 1996Boese et al , 1997 reports a longer time period required for M. nasuta to reach steady state, implying that a correction factor greater than 1 is warranted. This report presents evidence that these correction factors are not necessarily applicable.…”

Bioaccumulation of PCBs in the sea urchin Paracentrotus lividus: seawater and food exposures to a 14C-radiolabelled congener (PCB#153)

“…Information on PCB bioaccumulation in marine benthic organisms is scarce and is generally limited to experiments using laboratory-contaminated sediments as a source of contamination (Meador et al 1995, Boese et al 1997). In addition, few studies have taken into account essential species, upon which depends the ecosystem structure and/or functionning Oregioni 1976, Phillips 1976).…”

Toxicity and bioaccumulation of ethofumesate enantiomers in earthworm Eisenia fetida

“…However, because the concentration in the worm did not reach steady-state, resulting in the uptake data did not fit the nonlinear model, the uptake rate constant was estimated from linear regression of the concentration in the worm on days 0.5, 1, 3, 5, 10 and 14 of uptake (when elimination processes were assumed to be negligible) normalized to the soil concentration on the same day, versus time (SPSS 16.0). This technique has been recommended as an alternative to the nonlinear curve fitting method (Landrum et al, 1992) and used in other studies (Boese et al, 1997).…”