| Summary: | Studies on glaucous gulls (Larus hyperboreus) breeding in the Barents Sea have reported that high blood levels of halogenated organic contaminants in this species might cause reproductive, behavioral, and developmental stress. However, potential endocrine system modulation caused by contaminant exposure has yet not been reported in this Arctic apical predator. In this present study we aimed to investigate whether the current levels of a selection of organochlorines (OCs) were associated with altered circulating levels of thyroid hormones (THs) in free-ranging adult glaucous gulls breeding at Bear Island in the Barents Sea. Blood concentrations of 14 polychlorinated biphenyls, hexachlorobenzene (HCB), oxychlordane, and p,p´-dichlorodiphenyldichloroethylene (p,p´-DDE) were quantified, in addition to free and total thyroxine (T 4) and triiodothyronine (T 3), in plasma of 66 glaucous gulls in the spring of 2001. Negative correlations were found between plasma levels of T 4 and T 4:T 3 ratio, and blood levels of OCs in male glaucous gulls. Despite their relatively low contribution to the total OC fraction, HCB and oxychlordane were the most prominent compounds in terms of their negative effect on the variation of the T 4:T 3 ratio. Moreover, lower T 4 levels and T 4:T 3 ratios were measured in glaucous gulls breeding in a colony exposed to high levels of OCs, compared with a less exposed colony. Levels of T 3 were elevated in the high-OC–exposed colony. This may indicate that the glaucous gull is susceptible to changes to TH homeostasis mediated by exposure to halogenated organic contaminants. Key words: Arctic, contaminant, endocrine disruption, glaucous gull, organochlorine, T 3, T 4, thyroid hormone. Environ Health Perspect 112:532–537 (2004). doi:10.1289/ehp.6756 available via
|
|---|