PM11 Wildlife Ecotoxicology
Exhibit Hall
8:00 AM - Monday
(PM200) Altered Thyroid Status and Vitamin A Levels in Mink (Mustela vison) Exposed to a Commercial PBDE Mixture.
Martin, P1, Mayne, G.1, Bursian, S.2, Palace, V.3, Tomy, G.3, 1 Canadian Wildlife Service, Environment Canada, Burlington, Ontario, Canada2 Department of Animal Science, Michican State University, East Lansing, Michigan, United States3 Department of Fisheries and Oceans, Winnipeg, Manitoba, Canada
ABSTRACT- Polybrominated diphenyl ethers (PBDEs) are persistent, bioaccumulative organohalogen compounds that are known to disrupt endocrine function in various vertebrate species. The present study was undertaken to investigate the effects of dietary exposure to a commercial PBDE mixture on thyroid function and vitamin A levels in ranch mink. Four groups of 10 male mink were given either 0, 1, 5, or 10 ppm PBDE mixture in their daily diet for 11 weeks, starting at weaning. Plasma thyroxine (T4), and 3,5,3-triiodothyronine (T3) concentrations were measured, and histomorphometric and histopathologic evaluations were performed on thyroid gland sections. Vitamin A concentrations (retinol and 3,4-dehydroretinol) and retinyl esters in blood plasma, liver and kidney samples were measured to assess vitamin A status. Mink exposed to 5 ppm PBDE had significantly greater thyroid to body mass ratios and a greater incidence of hyperplastic follicles relative to controls. Mink from all PBDE exposure groups had significantly higher thyroid follicular epithelial cell heights relative to control mink. Exposure to the highest PBDE doses caused significant reductions in plasma T4 concentrations relative to mink exposed to the lowest dose, and plasma T3 concentrations were reduced in a dose-dependent manner. Body mass decreased significantly in mink exposed to 5 ppm and 10 ppm PBDE relative to controls and groups of exposed mink had significantly greater liver to body mass ratios. Data on contaminant concentrations in liver samples, vitamin A levels and hepatic 5-monodeiodinase activity are pending analysis. Our results corroborate other findings with vertebrates, indicating thyroid modulation is associated with exposure to polybrominated diphenyl ethers.
Key words: mink, PBDE, thyroid, retinol