The first exposure assessment of legacy and unrestricted brominated flame retardants in predatory birds of Pakistan.

The exposure to legacy polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs) and unrestricted 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), bis (2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEH-TEBP) and 2-ethylhexyl-2,3,4,5-tetrabromo-benzoate (EH-TBB) was examined in tail feathers of 76 birds belonging to ten predatory species inhabiting Pakistan. In addition, different feather types of six individuals of Black kite (Milvus migrans) were compared for their brominated flame retardant (BFR) levels. Black kite was found to be the most contaminated species with a median (minimum-maximum) tail feather concentration of 2.4 (0.70-7.5) ng g-1 dw for ∑PBDEs, 1.5 (0.5-8.1) ng g-1 dw for ∑HBCDDs and 0.10 ( 0.05 for both). Similarly, no significant concentration differences were observed among different feather types (all P > 0.05) suggesting their similar exposure. While variables such as species, trophic guild and δ15N values were evaluated as major predictors for BFR accumulation in the studied species, we predict that combined effects of just mentioned factors may govern the intra- and interspecific differences in BFR contamination profiles. We urge for further investigation of BFR exposure and potential toxicological effects in predatory birds from Asia with a more extensive sample size per species and location.