Levels and effects of persistent organic pollutants (POPs) in seabirds. Retinoids and a-tocopherol - potential biomarkers of POPs in birds?
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- Institutt for biologi 
In the present thesis, levels of polychlorinated biphenyls (PCBs), some chosen organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) were analyzed by gas chromatography in the yolk sac of newly hatched chicks of European shag (Phalacrocorax aristotelis), kittiwake (Rissa tridactyla), Brünnich’s guillemot (Uria lomvia) and common eider (Somateria mollissima) from the Norwegian coast and Svalbard. Levels of vitamin A (retinol), retinyl palmitate and vitamin E (α-tocopherol) were measured in plasma and liver of the hatchlings using high-performance liquid chromatography (HPLC). Using statistics, possible significant relationships between levels of the persistent organic pollutants (POPs) and vitamin levels were examined. Hence, the study aimed to elucidate retinoids and tocopherol as potential biomarkers of POP exposure. An exposure study on domestic duck (Anas platyrhynchos) eggs was also conducted to assess the effects of 2,2’,4,4’,5-pentabromodiphenyl ether (PBDE-99) on vitamin levels under controlled laboratory conditions. There were significant differences in POP levels between the bird species included in the present study. In general, kittiwake hatchlings had higher levels of POPs than the other species, followed by shag, Brünnich’s guillemot and common eider hatchlings. Levels of organochlorine compounds in the hatchlings seemed to be higher than reported in sea bird eggs from the Canadian Arctic but lower than reported in eggs of other seabirds from the Netherlands, the Baltic, the Great Lakes and Japan. In contrast to this, the levels of PBDEs and HBCD seemed to be high in some of the species (kittiwakes, shags) relative to a European scale. Negative relationships were revealed between POPs and morphology in Brünnich’s guillemot hatchlings, indicating that this species may be more responsive with respect to effects of POPs on morphological variables than the other species included in the present study. The importance of considering possible confounding impacts of lipid content when studying effects of POPs on morphological variables was emphasized in shag hatchlings. The study revealed negative correlations between POPs and liver tocopherol levels in domestic duck and shag hatchlings. In Brünnich’s guillemot hatchlings, liver tocopherol levels also were negatively associated with POPs, but the relationships were less strong when the effect of body mass on tocopherol levels was accounted for. In kittiwake and common eider hatchlings, however, there seemed to be a positive influence by POPs on tocopherol levels. Thus, the results should encourage further research on the effects of POPs on tocopherol levels (including oxidized forms of the vitamin). In shag hatchlings, negative relationships between POPs and plasma retinol levels were observed, in line with several previous studies on birds. Since retinol was not influenced in any other species included in the study, tocopherol levels might be more responsive than retinol levels to POP exposure. Additional studies should, however, be conducted before certain conclusions are drawn. Concerning the work needed for further development of vitamins as biomarkers of POP, effort should be done to characterize confounding factors, such as diet and condition of the avian mothers. Although there was no obvious link between the observed responses of vitamins to POP exposure and effects at higher biological levels (i.e. reproduction disturbances, population decline), the relevance of vitamins as potential biomarkers of POP exposure should not be repelled.
Has partsMurvoll, K.M.; Jenssen, B.M.; Skaare, J.U.. Effects of Pentabrominated Diphenyl Ether (Pbde-99) on Vitamin Status in Domestic Duck (Anas Platyrhynchos) hatchlings. Journal of Toxicology and Environmental Health Part A. 68(7): 515-533, 2005.
Murvoll, K.M.; Skaare, J.U.; Anderssen, E; Jenssen, B.M.. Exposure and effects of persistent organic pollutants in European shag (Phalacrocorax aristotelis) hatchlings from the coast of Norway. Environmental Toxicology and Chemistry. 25(1): 190-198, 2006.