We report on the identity, characterization, and spatial trends of several brominated flame retardants and hydroxylated (OH-) and methoxylated (MeO-) organohalogen contaminants in bald eagle (Haliaeetus leucocephalus) nestling plasma collected from sites along the west coast of North America. Samples were from four southwestern British Columbia (BC) locations, a reference site in northern BC (Fort St. James; FSJ), and from Santa Catalina Island, CA (SCI), an area of high DDT and PCB contamination. Mean concentrations of sigma polybrominated diphenyl ether (sigma PBDE (8 congeners monitored); 1.78-8.49 ng/g), sigma OH-polychlorinated biphenyl (sigma OH-PCB (30 congeners monitored); 0.44-0.87 ng/g), and sigma OH-PBDE (14 congeners monitored; 0.31-0.92 ng/g) were similar in eaglets from southwestern BC yet lower than for SCl and significantly higher than for FSJ. Dominant PBDE congeners were BDE47, BDE99, and BDE100, but SCl eaglets also contained low levels of higher brominated congeners. 4-OH-CB187 and 4'-OH-CB202 accounted for 65-100% of sigma OH-PCB in all BC eaglets, with 4'-OH-CB202 as well as 3'-OH-CB138 and 4-OH-CB146 dominating in SCl eaglets. Ostensibly of biogenic origin, 6'-OH-BDE49 and 6-OH-BDE47 were found in BC nestlings. Only 4'-OH-BDE49 (2.10 ng/g) was found in SCl eaglets. MeO-PBDEs and total hexabromocyclododecane (HBCD) were not found in any birds, but the polybrominated biphenyl BB101 was detected in southwestern BC samples. This study demonstrates that west coast North American bald eagles contain previously unreported organohalogens, which have the potential to impact the health and survival of these raptors.

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Polyhalogenated aromatic hydrocarbons are global contaminants that are often considered to be endocrine disruptors and include 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDE), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). The present study examined these compounds and their hydroxylated metabolites or analogues and relationships with circulating thyroid hormones and retinols in plasma from nestling and adult bald eagles in British Columbia, Canada, and California, USA. We also compared our results with published data. Thyroxine (T4) decreased with summation operatorPCB and CB153 in nestling bald eagles, which was congruent with results from nine of 14 other published avian laboratory and field studies. Free thyroid hormone levels also decreased with CB-153 and hydroxylated PCBs (OH-PCBs). Retinol increased with CB118 and CB180 in nestling eagles, decreased with OH-PCBs in a subset of nestlings, and decreased in 7 of 12 PCB published studies. Thyroxine decreased with p,p'-DDE for nestlings and with data reported in one of five other published studies. In our samples, plasma retinol, triiodothyronine (T3), and T4 were independent of summation operatorPBDEs, whereas summation operatorOH-PBDEs were weakly but significantly correlated with increases in T3 and retinol. Adult bald eagles showed no relationship between contaminants and thyroid hormones, which is consistent with other studies of long-lived birds, perhaps because adult birds have time to adjust to contaminant levels. Measurement of circulating thyroid hormones appears to be a more useful biomarker than retinols, given the more consistent response of T4 to PCBs here and reported in the literature. We conclude that current environmental exposures to PCBs in British Columbia and in southern California are associated with significant decreases in T4, suggesting a potential negative effect on the endocrine system of nestling bald eagles.

Patterns and trends of chlorinated hydrocarbons were assessed in bald eagle nestling plasma from sites along the west coast of North America. Eagle plasma was sampled from four areas in southwestern British Columbia (BC), a reference site in northern BC, and from Santa Catalina Island, off the coast of California. Sites were chosen to reflect variation in contaminant exposure due to differing recent and/or historic anthropogenic activities. Santa Catalina Island had significantly greater mean concentrations of p,p'-DDE, 41.3 microg/kg wet weight (ww), than other sites, and Nanaimo/Crofton, BC had the greatest mean concentration of total PCBs, 28.9 microg/kg ww. Contaminant levels measured in 2003 in BC were compared to levels measured in 1993; over that ten year span, concentrations and patterns of chlorinated hydrocarbons have not significantly changed. There were no significant differences in levels of p,p'-DDE or hexachlorobenzene between 1993 and 2003, but significant decreases were found for trans-nonachlor and PCBs at BC sites. Levels of total PCBs and trans-nonachlor in the central Fraser Valley and Nanaimo/Crofton area have significantly decreased. Mean concentrations of p,p'-DDE measured in bald eagle nestling plasma samples in 2003 exceeded published criteria for effects on bald eagle reproduction at Santa Catalina Island and Barkley Sound, more than 30 years since heavy usage restrictions were imposed.

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