Bioaccumulation of Highly Hydrophobic Chemicals by Lumbriculus variegatus.

Bioaccumulation of highly hydrophobic chemicals (log KOW > 8) from contaminated sediments by Lumbriculus variegatus has been studied for relatively few chemicals, and the measured and model predicted biota-sediment accumulation factors (BSAFs) can differ by orders of magnitude. In the current study, sediment bioaccumulation tests with L. variegatus were performed on sediments dosed with chemicals having a wide range of predicted n-octanol/water partition coefficients (KOW; 106-1018), including some higher than most highly hydrophobic chemicals studied to date. The highly hydrophobic chemicals had biphasic elimination kinetics with compartments A and B having fast and slow elimination kinetics, respectively, and for compartment B, elimination followed first-order kinetics. For compartment A with fast elimination kinetics, the mechanism and its kinetic-order could not be determined. Steady-state BSAFs (kg organic carbon/kg lipid) of 0.015, 0.024, and 0.022 were derived for tetradecachloro-p-terphenyl, tetradecachloro-m-terphenyl, and octadecachloro-p-quaterphenyl, respectively. The high uncertainty in predicted KOWs for highly hydrophobic chemicals limited the comparison and evaluation of predicted BSAFs from the Arnot-Gobas food web model and BSAFs measured in this study. The results of this study point to the need to perform dietary assimilation efficiency studies with highly hydrophobic compounds to resolve uncertainties surrounding the estimation of their KOW and the need to understand mechanism and models for the biphasic elimination kinetics.