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

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, C6C15 chain lengths) and sulfonates (C4, C6, C8, and C10 chain lengths) as well as selected precursors including perfluorooctane sulfonamide. On a wet-weight basis, bloodbrain 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 58ng/g wet weight, and perfluorotridecanoic acid, ranging from 43 to 49ng/g wet weight. However, PFOS and the longer-chain PFCAs (C10C15) were significantly (p<0.002) positively correlated with lipid content for all brain regions. Lipid-normalized PFOS and PFCA (C10C15) 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, 392g) was estimated to be 46 mu g. The present study demonstrates that both PFCAs and perfluoroalkyl sulfonates cross the bloodbrain barrier in polar bears and that wet-weight concentrations are brain regionspecific. Environ. Toxicol. Chem. 2013;32:713722. (c) 2012 SETAC