Relationship of plasma lipids, thyroid hormones and vitamin A with environmental contaminants measured in bald eagles in British Columbia and Southern California

Bald eagles (Haliaeetus leucocephalus) are considered an appropriate indicator species to monitor ecosystem contamination. In this study, bald eagles nestlings were used to 1) investigate the importance of analyzing and controlling for plasma lipid levels when interpreting contaminant levels; 2) determine the relationship between contaminants and thyroid hormones as well as vitamin A; and 3) examine spatial and temporal trends of organochlorines and polybrominated diphenyl ethers in British Columbia and southern California. No significant relationships were found between contaminants and lipid levels. Nevertheless, significant differences between sites for both p,p'-Dichlorodiphenyldichloroethylene (p,p'-DDE) and polychlorinated biphenyls (PCBs) were detected. Only p,p'-DDE and PCB levels showed a negative correlation with thyroid hormones. No significant relationships were found between contaminants and vitamin A. In British Columbia, trans-Nonachlor and PCB levels significantly decreased between 1993 and 2003, but Hexachlorobenzene (HCB) and p,p'-DDE have not.