Metals and Organohalogen Contaminants in Bald Eagles (Haliaeetus leucocephalus) from Ontario, 1991-2008.

Arch Environ Contam Toxicol. 2017 Nov 21. doi: 10.1007/s00244-017-0479-5. [Epub ahead of print] Martin PA1, Hughes KD2, Campbell GD3, Shutt JL4. Author information 1 Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, ON, L7S 1A1, Canada. pamela.martin2@canada.ca. 2 Broadwing Biological Consulting, 1944 Parkside Drive, Pickering, ON, L1V 3N5, Canada. 3 Canadian Wildlife Health Cooperative, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada. 4 Environment and Climate Change Canada, 335 River Road, Ottawa, ON, K1V 1C7, Canada. Abstract We examined the degree of exposure of lead (Pb), mercury (Hg), and several organohalogen contaminants and its potential impact on survival of bald eagles in Ontario from 1991 to 2008. Overall, results for 43 dead or dying bald eagles collected in the province indicate that 23% (10/43) of birds died of Pb poisoning and 9% (4/43) died of suspected Hg poisoning. Pb poisoning was diagnosed based on exceedances of toxicity thresholds in liver and kidney and supported by clinical observations, necropsy results, and histology findings when available. Evidence for Hg poisoning in eagles was limited; however, Hg concentrations exceeded the toxicity threshold in kidney. Pb concentrations ranged widely in liver and kidney. Total Hg concentrations were relatively higher in kidney compared with liver and were significantly correlated with selenium (Se) concentrations in both tissues. Concentrations of p,p'-DDE and sum PCBs in livers of 12 bald eagles collected from 2001 to 2004 were likely below concentrations associated with adverse effects. Hepatic concentrations of total polybrominated diphenyl ethers were generally higher in birds collected from southern Ontario compared with northern Ontario. Potential impacts of exposure to these flame retardants and others are not known. Elevated metal exposure appears to influence survivorship and may affect the recovery of bald eagles in the province, particularly in southern Ontario and along the Great Lakes where a disproportionate number of poisoned eagles were collected. Increased efforts are needed to identify sources of exposure and develop measures to reduce metal exposure in this top predator. PMID: 29164278 DOI: 10.1007/s00244-017-0479-5