PBDE through the entire North Sea food web

Content of the study

Polybrominated diphenyl ethers (PBDEs) are an important type of flame retardant. They have been widely used; in cars, furniture, textiles, etc.. PBDEs are very hydrophobic (meaning they rather dissolve in lipids than in water), resistant to degradation and potentially toxic.

Context of the study

This study analyzed PBDE concentrations in animals of different trophic levels, namely, the invertebrate species: sea star, brown shrimp, common whelk and hermit crab, the fish species: herring, withing and cod, the marine mammals: harbour porpoise and harbour seal. All animals were sampled from the North Sea in 1999. The marine mammal samples resulted from by-catch from fisheries, or from strandings.

Main results of the study

The study showed that PBDE concentrations in whiting and cod were much higher in the liver than in the fillet, while for herring and the marine mammals they were almost equally distributed between the liver and fillet (or for marine mammals the liver and the blubber). It is thought that the low fat content of whiting and cod caused the PBDEs to preferentially accumulate in the liver.

The study failed to demonstrate biomagnification of any PBDE between the lowest trophic levels (shrimp, hermit crab, common whelk, starfish) and predatory fish like herring. Even between herring an high carnivorous fish; cod and whiting, no biomagnification effect could be demonstrated. It did however show biomagnification between the 3 fish species and the marine mammals. This result was unexpected since other studies did show biomagnification in the lower trophic levels. A possible explanation for this might be that the lower trophic species are less mobile and were therefore more affected by the high PBDE exposure at several sampling sites.