Abstract-The dietary uptake of 12 halogenated diaromatic compounds was studied using northern pike (Esox lucius L.) fed with rainbow trout (Oncorhynchus mykiss (Walbaum)). Before the trout were fed to the pike, they had been injected with a cocktail of five polychlorinated biphenyls, four polychlorinated naphthalenes, and three polybrominated diphenyl ethers, dissolved in rainbow trout lipid. The reported uptake efficiencies (E) were in the range 35 to 90% and differ in some respect from earlier studies. The E-values for those substances with effective cross sections (ECS) Ͼ9.5 Å were considerably higher than expected if the membrane permeation at dietary uptake was restricted as proposed previously in the literature. There was no hydrophobicity dependency of the total dietary uptake efficiency as suggested by an earlier proposed empirical model. The difference between the results presented here and earlier studies is likely to depend on cotransport with lipids and/or proteins through a mediated, possibly active uptake of hydrophobic organic compounds (HOC) in the gastrointestinal tract enabled by the actual exposure method. For the proposed mediated/active uptake of HOCs, the uptake efficiency varied with molecular weight and was greatest for a molecular weight of approximately 450.

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Baltic Sea blue mussels, Mytilus edulis, were exposed to polybrominated diphenyl ethers (PBDEs, IUPAC congeners 47, 99, and 153) and polychlorinated biphenyls (PCBs, congeners 31, 52, 77, 118, and 153) in a flow-through experimental setup for 44 d. After the exposure phase, the mussels were allowed to depurate in natural brackish water for 26 d. After analyses, uptake clearance rate coefficients (k u ), depuration rate coefficients (k d ), and bioaccumulation factors (BAF) were calculated. A rapid uptake of all PBDEs and PCBs was observed, especially for PBDE congeners 47 and 99 (k u 120 and 170 L/day/g dry weight, respectively). The depuration rate decreased with increasing hydrophobicity as expected for the PCBs, but for the PBDEs, depuration rate coefficients appeared to be of the same magnitude for all three congeners independently of log K ow . The BAFs obtained for PBDE 47 and PBDE 99 (1.3 ϫ 10 6 and 1.4 ϫ 10 6 ml/g dry weight, respectively) were higher than for all other substances in the study, severalfold higher than for PCBs of similar hydrophobicity. The presented data indicate that the bioaccumulation potential of PBDEs, extensively used as flame retardants, is similar or higher than that of PCBs for filter feeding organisms such as blue mussels.

The dietary uptake of 12 halogenated diaromatic compounds was studied using northern pike (Esox lucius L.) fed with rainbow trout (Oncorhynchus mykiss (Walbaum)). Before the trout were fed to the pike, they had been injected with a cocktail of five polychlorinated biphenyls, four polychlorinated naphthalenes, and three polybrominated diphenyl ethers, dissolved in rainbow trout lipid. The reported uptake efficiencies (E) were in the range 35 to 90% and differ in some respect from earlier studies. The E-values for those substances with effective cross sections (ECS) Ͼ9.5 Å were considerably higher than expected if the membrane permeation at dietary uptake was restricted as proposed previously in the literature. There was no hydrophobicity dependency of the total dietary uptake efficiency as suggested by an earlier proposed empirical model. The difference between the results presented here and earlier studies is likely to depend on cotransport with lipids and/or proteins through a mediated, possibly active uptake of hydrophobic organic compounds (HOC) in the gastrointestinal tract enabled by the actual exposure method. For the proposed mediated/active uptake of HOCs, the uptake efficiency varied with molecular weight and was greatest for a molecular weight of approximately 450.