Birds as indicators of contaminants in the Great Lakes - Egg Contaminants

Tree swallows, Tachycineta bicolor, were sampled across the Great Lakes basin in 2010-2015 to provide a system-wide assessment of current exposure to organic contaminants. These results provide information identified as critical by land managers and regulators to assess the �Bird or Animal Deformity or Reproductive Problems� Beneficial Use Impairment. Eggs were collected from 69 sites across all five Great Lakes, including 27 Areas of Concern (AOCs), some with multiple sites, and ten sites not listed as an AOC. Concentrations of organic contaminants in eggs were quantified and compared to background and reproductive effect thresholds. Approximately one-third of the AOCs had geometric mean concentrations of total polychlorinated biphenyls (PCBs) at or below background exposure (0.34 g/g wet wt.). Exposure to polybrominated diphenyl ethers (PBDEs) was minimal, and only three of 27 AOCs and 1 non-AOC had geometric mean concentrations that exceeded background for tree swallows (96 ng/g wet wt.). Concentrations of both PCBs and PBDEs were 10 � 20 times below the lower limit for hatching effects. In contrast, geometric mean concentrations of dioxin and furan toxic equivalents (TEQs) at Saginaw River and Bay AOC and Midland, MI, a non-AOC site, exceeded the lower limit for hatching effects (181 pg/g dioxin/furan TEQs). The rest of the sites, except for Cuyahoga River, OH, had geometric mean concentrations of dioxin and furan TEQs below background levels (87 pg/g dioxin/furan TEQs). Other organic contaminants, including p,p'-dichlorodiphenyl-dichloroethylene (DDE), mirex, heptachlor, and chlordane, were at or below background concentrations.