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This article is part of the supplement: Environmental contaminants and animal health. Proceedings of the 26th Symposium of the Nordic Committee for Veterinary Scientific Cooperation (NKVet)

Open Access Meeting abstract

Two decades of biomonitoring polar bear health in Greenland: a review

Christian Sonne1*, Robert J Letcher2, Thea Ø Bechshøft1, Frank F Rigét1, Derek CG Muir3, Pall S Leifsson4, Erik W Born5, Lars Hyldstrup6, Niladri Basu7, Maja Kirkegaard8 and Rune Dietz1

  • * Corresponding author: Christian Sonne csh@dmu.dk

Author Affiliations

1 Department of Bioscience, Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark

2 Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, K1A 0H3, Canada

3 Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington, Ontario, L7R 4A6, Canada

4 Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Bülowsvej 17, DK-1870 Frederiksberg, Denmark

5 Greenland Institute of Natural Resources, PO Box 570, DK-3900 Nuuk, Greenland, Denmark

6 University Hospital of Hvidovre, Kettegaards Allé 30, DK-2650 Hvidovre, Denmark

7 Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA

8 Danish Agency for Science, Technology and Innovation Bredgade 40 DK-1260 Copenhagen K, Denmark

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Acta Veterinaria Scandinavica 2012, 54(Suppl 1):S15  doi:10.1186/1751-0147-54-S1-S15

Published: 24 February 2012

Abstract

We present an overview of studies of anthropogenic pollutants in East Greenland polar bears over the period of 1999-2011. East Greenland polar bears are among the most polluted species, not just in the Arctic but globally, and represent an excellent biomonitoring species for levels and effects of global pollution in an apex predator. Therefore, an international multidisciplinary team joined to monitor and assess the patterns and concentrations of contaminants and their potential negative impact on polar bears. The review showed that East Greenland polar bears are exposed to a mix of chlorinated, brominated and fluorinated organic compounds as well as mercury which are all known to have endocrine, immune and organ-system toxic properties. For example, the concentrations of PCBs (polychlorinated biphenyls) in blubber ranged approximately 800-21,000 ng/g lw while mercury concentrations in liver and kidney ranged 0.1-50 μg/g ww. Regarding health endpoints, bone density seemed to decrease as a function of time and OHC (organohalogen compound) concentrations and further T-score for adult males indicated risk for osteoporosis. .The size of sexual organs decreased with increasing OHC concentrations. In the lower brain stem, mercury-associated decreases in NMDA-receptor levels and DNA-methylation was found The present review indicated that age was one of the major drivers for liver and renal lesions, although contaminants and infectious diseases may also play a role. Lesions in thyroid glands were most likely a result of infectious and genetic factors and probably, together with endocrine disrupting chemical (EDCs), the reason for disturbances/fluctuations in blood plasma thyroid hormone concentrations. Except for bone density reductions and neurological measures, all findings were supported by case-control studies of Greenland sledge dogs exposed long-term orally to similar combinations of contaminant concentrations. The studies of sledge dogs also indicated that the mixture of contaminants and fatty acids in the blubber of prey similar to that of polar bears induces cellular as well as humoral immune toxic changes. These controlled studies using model species for polar bears indicate that the correlative findings between health endpoint and contaminants in polar bears could be a cause-and-effect relationship. Physiologically based pharmacokinetic (PBPK) modelling showed that the risk quotients were ≥1 for ΣPCB, dieldrin and PFOS, which indicate an increased risk of prenatally reproductive pathology. In conclusion polar bears are susceptible to long-range transported chemicals that may have various adverse effects on multiple organ systems such as the reproductive and immune system.