Congener-specific bioaccumulation of PCBs in different water bird species

The bioaccumulation behaviour of single PCB congeners in three trophic levels of a food chain in an aquatic ecosystem was studied. Congener-specific biotransfer factors were calculated comparing PCB concentrations in tissues of 4 water bird species with the contents measured in their food source. The coplanar PCBs were of particular interest. The maximum concentrations of individual PCB congeners detected in mussels, fish and birds were 0.5, 4, and 26 μg/g extractable lipids, respectively. In general, the mussel-feeding tufted ducks showed lower PCB levels than the fish-feeding bird species. The biotransfer factors were highest for the non-ortho chloro-substituted coplanar PCB congeners from lake trout to grey herons (3 to 15, depending on the congener). If the TCDD toxic equivalency (TEq) concept based on mammalian toxicity data is used for the toxicological assessment the detected PCB levels are in the range where effects on the reproductive impairment of theses bird species could result. However, no indication for such effects could be observed. This suggests that species-specific TEF values are required.