title: The role of diet on long-term concentration and pattern trends of brominated and chlorinated contaminants in western Hudson Bay polar bears, 1991-2007.
abstract: Adipose tissue was sampled from the western Hudson Bay (WHB) subpopulation of polar bears at intervals from 1991 to 2007 to examine temporal trends of PCB and OCP levels both on an individual and sum-(∑-)contaminant basis. We also determined levels and temporal trends of emerging polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), polybrominated biphenyls (PBBs) and other current-use brominated flame retardants. Over the 17-year period, ∑DDT (and p,p'-DDE, p,p'-DDD, p,p'-DDT) decreased (-8.4%/year); α-hexachlorocyclohexane (α-HCH) decreased (-11%/year); β-HCH increased (+8.3%/year); and ∑PCB and ∑chlordane (CHL), both contaminants at highest concentrations in all years (>1ppm), showed no distinct trends even when compared to previous data for this subpopulation dating back to 1968. Some of the less persistent PCB congeners decreased significantly (-1.6%/year to -6.3%/year), whereas CB153 levels tended to increase (+3.3%/year). Parent CHLs (c-nonachlor, t-nonachlor) declined, whereas non-monotonic trends were detected for metabolites (heptachlor epoxide, oxychlordane). ∑chlorobenzene, octachlorostyrene, ∑mirex, ∑MeSO(2)-PCB and dieldrin did not significantly change. Increasing ∑PBDE levels (+13%/year) matched increases in the four consistently detected congeners, BDE47, BDE99, BDE100 and BDE153. Although no trend was observed, total-(α)-HBCD was only detected post-2000. Levels of the highest concentration brominated contaminant, BB153, showed no temporal change. As long-term ecosystem changes affecting contaminant levels may also affect contaminant patterns, we examined the influence of year (i.e., aging or "weathering" of the contaminant pattern), dietary tracers (carbon stable isotope ratios, fatty acid patterns) and biological (age/sex) group on congener/metabolite profiles. Patterns of PCBs, CHLs and PBDEs were correlated with dietary tracers and biological group, but only PCB and CHL patterns were correlated with year. DDT patterns were not associated with any explanatory variables, possibly related to local DDT sources. Contaminant pattern trends may be useful in distinguishing the possible role of ecological/diet changes on contaminant burdens from expected dynamics due to atmospheric sources and weathering.
authors.affiliation: Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, Carleton University (Raven Road), Ottawa, Ontario K1A 0H3, Canada. melissaamckinney@gmail.com
authors.forename: Melissa A
authors.initials: MA
authors.lastname: McKinney
authors.forename: Ian
authors.initials: I
authors.lastname: Stirling
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Lunn
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Peacock
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Letcher
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D002170:Canada; D004032:Diet; D004781:Environmental Exposure / Q000032:analysis; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000378:metabolism*; D004787:Environmental Pollution / Q000706:statistics & numerical data; D005260:Female; D005411:Flame Retardants / Q000378:metabolism; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism; D006842:Hydrocarbons, Brominated / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D008297:Male; D010575:Pesticides / Q000378:metabolism; D001503:Ursidae / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D006842:Hydrocarbons, Brominated; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides