Hepatic polybrominated diphenyl ether (PBDE) levels in Wisconsin river otters (Lontra canadensis) and Michigan bald eagles (Haliaeetus leucocephalus)

Polybrominated diphenyl ethers (PBDEs) are persistent and toxic flame-retardant chemicals widespread in the Great Lakes ecosystem. These chemicals are now being regulated and phased-out of the region; therefore it remains important to understand the extent of contamination in order to track the efficacy of recent actions. Here, Σ4PBDE congeners (PBDE-47, 99, 100, 153; wet weight basis unless indicated) were determined in liver tissues from Wisconsin river otters (Lontra canadensis; n = 35; 2009-2010) and Michigan bald eagles (Haliaeetus leucocephalus; n = 33; 2009-2011). In otters, Σ4PBDE ranged from 0.5 to 72.9 ng/g, with a mean (± SD) and median (25th-75th percentile inter-quartile range) of 16.3 ± 16.4 ng/g and 11.3 (5.6-18.9) ng/g, respectively. The mean lipid-adjusted Σ4PBDE was 1377 ± 1485 ng/g. In eagles, Σ4PBDE ranged from 0 to 1,538.8 ng/g, with a mean and median of 74.3 ± 266.7 ng/g and 21.2 (5.7-28.9) ng/g, respectively. The mean lipid-adjusted Σ4PBDE was 5274.5 ± 19,896.1 ng/g. In both species, PBDE-47 accounted for > 50% of the Σ4PBDE, followed by PBDE-99 and PBDE-100 (each ~ 17-19% of the total). The PBDE levels reported here in otters are similar to mammalian wildlife elsewhere, though the levels in eagles are among the highest worldwide across studied birds. The findings indicate that apex Great Lakes wildlife remain exposed to appreciable levels of PBDEs and more work is needed to understand whether such exposures are associated with adverse health outcomes.