Tissue distribution of 2,2',4,4'-tetrabromo[14C]diphenyl ether ([14C]-PBDE 47) in pike (Esox lucius) after dietary exposure--a time series study using whole body autoradiography

In the present study, the tissue distribution of [14C]-labelled 2,2',4,4'-tetrabrominated diphenyl ether (PBDE 47) and its possible metabolites was investigated after dietary exposure in pike (Esox lucius) using whole-body autoradiography. The study is a time series with pike examined 9, 18, 36 and 65 days after exposure. PBDE 47 was efficiently absorbed from the food (>90%) and radioactivity remained in the body in considerable amounts even after the longest period examined. The results indicate that PBDE 47 is not rapidly metabolised to hydrophilic, but possible to hydrophobic metabolites and that PBDE 47 and possible hydrophobic metabolites are accumulated in the lipid rich tissues of the pike. Melanin binding of PBDE 47 and possible metabolite(s) is suggested. The levels of PBDE 47 and/or metabolite(s) declines with time in most tissues except for the most lipid rich, where no decline in radioactivity is observed even after the longest period studied. Signs of irreversible incorporation of PBDE 47-derived radioactivity were detected but considered as too uncertain to conclude that covalent binding of PBDE 47-metabolites to macromolecules occurs.