M3 AM Ecological Risk Assessment (Part 1)
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 3

(ZWI-1117-773778) Mink and PCDD/Fs in the Tittabawassee River basin.

Zwiernik, Matthew¹, Moore, Jeremy¹, Tazelaar, Dustin¹, Kay, Denise², Hamman, David¹, Blankenship, Alan ², Giesy, John¹, ¹ National Food Safety and Toxicology Center, Center for Integrative Toxicology,Zoology Department, Michigan State University, East Lansing, MI, United States² Entrix, Inc, Okemos, MI, United States

ABSTRACT- The Tittabawassee River, located in central Michigan, USA, contains polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the sediments, floodplain soils, and biota downstream of the city of Midland. Mink (Mustela vision) as top predators and year round residence of the river basin have a high potential for exposure. Their sensitivity to adverse effects from this class of compounds makes them of special concern. An ongoing risk of harm evaluation for these animals utilizes a multiple line of evidence approach. Measurement endpoints include dietary and tissue based exposure assessments as well as population health criteria including population demographics, nutritional state and reproductive potential. Concentrations of seventeen 2,3,7,8 PCDD and PCDF congeners were measured in dietary items including composite samples of forage fish, and crayfish, as well as individual small mammals, all collected from multiple locations within the floodplain both upstream and downstream of Midland. Total 2,3,7,8-PCDD/DF concentrations of reference area dietary items ranged from 4.06 to 5.06 ng/kg wet weight (n=2), 2.15 to 2.39 ng/kg ww (n=2) and 1.48 to 530 (n=34) ng/kg ww respectively while target area dietary items exhibited total PCDD/DF concentrations ranging from 200 to 610 ng/kg ww (n=5). 86.3 to 1280 ng/kg ww (n=8) and 10.6 to 12700 (n=136) respectively. Additionally, 32 adult mink have been sampled from the site including 18 reference and 14 target area mink. All female mink of reproductive age presented placental scaring regardless of location. Mink mean body weights for both males and females were slightly greater for target area mink, 917.06 g and 517.38 g respectively vs. 871.55 and 482.29 for reference area mink. Overall nutritional state followed this same pattern with target mink receiving slightly higher scores ranging from good to excellent. Additional data will include brain to liver weight relationships and a dietary exposure assessment based on both a literature and site-specific dietary composition.

Key words: Mink, PCDD/DFs, Tittabawassee River, Furans