Brain region distribution and patterns of bioaccumulative perfluoroalkyl carboxylates and sulfonates in East Greenland polar bears (Ursus maritimus)

Authors

  • Alana K. Greaves,

    1. Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, and National Wildlife Research Centre and Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
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  • Robert J. Letcher,

    Corresponding author
    1. Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, and National Wildlife Research Centre and Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
    • Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, and National Wildlife Research Centre and Department of Chemistry, Carleton University, Ottawa, Ontario, Canada.
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  • Christian Sonne,

    1. Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, Denmark
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  • Rune Dietz

    1. Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, Denmark
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Abstract

The present study investigated the comparative accumulation of perfluoroalkyl acids (PFAAs) in eight brain regions of polar bears (Ursus maritimus, n = 19) collected in 2006 from Scoresby Sound, East Greenland. The PFAAs studied were perfluoroalkyl carboxylates (PFCAs, C6–C15 chain lengths) and sulfonates (C4, C6, C8, and C10 chain lengths) as well as selected precursors including perfluorooctane sulfonamide. On a wet-weight basis, blood–brain barrier transport of PFAAs occurred for all brain regions, although inner regions of the brain closer to incoming blood flow (pons/medulla, thalamus, and hypothalamus) contained consistently higher PFAA concentrations compared to outer brain regions (cerebellum, striatum, and frontal, occipital, and temporal cortices). For pons/medulla, thalamus, and hypothalamus, the most concentrated PFAAs were perfluorooctane sulfonate (PFOS), ranging from 47 to 58 ng/g wet weight, and perfluorotridecanoic acid, ranging from 43 to 49 ng/g wet weight. However, PFOS and the longer-chain PFCAs (C10–C15) were significantly (p < 0.002) positively correlated with lipid content for all brain regions. Lipid-normalized PFOS and PFCA (C10–C15) concentrations were not significantly (p > 0.05) different among brain regions. The burden of the sum of PFCAs, perfluoroalkyl sulfonates, and perfluorooctane sulfonamide in the brain (average mass, 392 g) was estimated to be 46 µg. The present study demonstrates that both PFCAs and perfluoroalkyl sulfonates cross the blood–brain barrier in polar bears and that wet-weight concentrations are brain region–specific. Environ. Toxicol. Chem. 2013;32:713–722. © 2012 SETAC

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