Organohalogen contaminants and reproductive hormones in incubating glaucous gulls (Larus hyperboreus) from the Norwegian Arctic

Organohalogen contaminants detected globally in avian wildlife, including populations from the Arctic, have been related to various reproductive hormone potencies, and altered hormonal balance and functions. Besides legacy organochlorine (OC) substances, that is, polychlorinated biphenyls (PCBs) and OC pesticides and by-products, endocrine-disruptive properties have been defined for chemicals of new and emerging environmental concern, such as polybrominated diphenyl ethers (PBDEs) and metabolically derived products like methylsulfonyl (MeSO2)- and hydroxyl (OH)-PCBs. We investigated the relationships between plasma concentrations of selected legacy OCs, PBDEs, and MeSO2- and OH-PCB metabolites and the circulating reproductive hormones testosterone (T), 17 beta-estradiol (E-2), and progesterone (P-4) in incubating male and female glaucous gulls (Larus hyperboreus) from the Norwegian Arctic. Principal component and regression analyses demonstrated that P-4 levels in male glaucous gulls were associated positively with variations of sum (Sigma) PCB, dichloro-diphenyl-trichloroethane (Sigma DDT), chlordane (Sigma CHL), and Sigma PBDE concentrations, which were the most recalcitrant organohalogens determined in glaucous gulls. No such relationship was found for female glaucous gulls as well as between concentrations of any of the selected organohalogens and levels of T for both sexes. The E-2 was not detected in any plasma samples. Present results were highly suggestive that exposure to high organohlogen concentrations in glaucous gulls, particularly the most persistent compound classes, may have the potential to interfere with steroidogenesis and impinge on circulating P-4 homeostasis. Because significant effects were found in males exclusively, it cannot be completely ruled out that male glaucous gulls are more sensitive than females to organohalogen-mediated alteration of P-4 synthesis and breakdown.