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(P856) PCB Dietary Exposures and Body Burdens in Passerines at the Kalamazoo River Superfund Site, Michigan.
Neigh, Arianne1, MacCarroll, Monica*,1, Zwiernik, Matthew1, Park, Cyrus1, Bradley, Patrick1, Hoon, Dong1, Adams, Ray2, Strause, Karl1, Pastva, Stephanie1, Giesy, John1, 1 Michigan State University, E. Lansing, MI, U.S.A2 Kalamazoo Nature Center, Kalamazoo, MI, U.S.A
ABSTRACT- Tree swallows have traditionally been used as receptors in PCB risk assessment studies. An important componant in understanding and evaluating receptor enpoints is to identify the primary PCB exposure pathway, which for tree swallows is through the diet. The tree swallow (Tachycineta bicolor) eggs, nestlings, and boluses from two sites on the Kalamazoo River were sampled and analyzed for PCBs in order to assess the level of exposure through the diet among passerine populations. Nest boxes were monitored at a control site upstream of point source pollution and at an impoundment within the area identified as the Kalamazoo River Area of Concern. Eggs were sampled at 10-12d post-laying, while tree swallow nestlings were sampled at 12d post hatch. Stomach contents were examined to determine prey items to the level of order. Bolus samples were also examined to verify dietary composition. The tree swallow diet at the control site was identified through bolus sampling and found to contain 62.16% diptera, 26.49% hemiptera, 3.78% odonata, 3.24% arachinid, 1.62% hymenoptera, 1.08% each of coleoptera and mollusca, 0.54% orthopera, and 0.54% unknown. Tree swallow stomach contents showed a much broader range of orders with the majority being represented by stones (21.92%), hymenoptera (15.07%), and coleoptera (13.70%). A large portion of unidentified matter (13.70%) appeared to be soft portions of insects. After digestion, dipterans and other prey items composed mainly of soft tissue are not likely to be identifiable, so there may be a disproportionate representation of orders with keratinized parts. The control site had a much greater variety of prey items, but this may be attributed to the difference in sample size between the two sites (n=5 at the study site and n=19 at the control site). The study site contained 33.33% diptera, 22.22% stones, and 22.22% coleoptera. Using stomach analysis in conjuction with bolus sampling gives the best overview of avian diets, although opportunistic feeding of insects is most likely the cause of the variation in diet between the two research sites. Currently, the analysis of PCB concentrations in orders represented in the diet are being prepared. Dietary exposures based on total PCBs and TEQs will be derived for nestlings and related to concentrations in the eggs and nestling tissues.
Key words: PCBs, tree swallow, dietary composition, exposure assessment
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