Environmental contaminants threaten the health of polar bears

28 May 2010, Biodiversity and Land Use, NERI

A cocktail of industrial chemicals damages the bones and organs of polar bears, their immune system and their reproduction. However, the extent of the detrimental effects remains unknown, concludes senior scientist Christian Sonne, National Environmental Research Institute (NERI), Aarhus University, having conducted the first overall review of the last 10 years’ research into the impact of pollution on the health of polar bears.

Christian Sonne’s review has just been published in the scientific journal “Environmental International” and includes his and his colleagues’ widely published research within the area. NERI and the Greenland Institute of Natural Resources are responsible for the research in Greenland. Additional cooperation exists with colleagues in Denmark, Norway, USA and Canada.

Industrial chemicals such as brominated flame retardants, PCB and polyfluorinated substances that are used in several everyday products and as softeners and for surface treatment are transported with heavy metals, including mercury, with air and sea currents and in sea mammals to the Arctic from the industrial part of the world.

In the Arctic the contaminants enter the marine food chain and are accumulated in the fat tissue of seals and small whales, prey animals of the polar bear. And, next, in the polar bears themselves.

In his review Christian Sonne concludes that these environmental contaminants result in a number of so-called subclinical diseases in the animals.

“These are diseases that are not immediately lethal, but which may lead to the development of more chronic diseases and which at some level or other will impact the immune and reproduction systems of the animals,” he says.

So far, Christian Sonne has analysed tissue and bone (skull) samples from approx. 100 out of 200 East-Greenland polar bears shot by hunters in the Scoresbysund-area.

Together with the Greenland Institute of Natural Resources NERI has since 1983 co-operated with hunters harvesting polar bears at a sustainable level of 1-2% annually of the total East-Greenland population of ca. 2,000-3,000 animals.

High-quality collection of tissue and skulls

“Our co-operation with the hunters has resulted in a unique high-quality collection of tissue and skulls, and the East-Greenland polar bear project is among the hitherto largest investigations elucidating pollution and health effects on the organ systems of wild mammals,” says Christian Sonne.

Monitoring and observations of polar bears have also comprised the Svalbard population, and Christian Sonne and his colleagues have in the past undertaken controlled experiments on the impact of environmental contaminants on farmed polar foxes and Greenland sledge dogs. Both species are at the top end of the Arctic food chains.

The animals were divided into two groups, one was fed with food containing environmentally hazardous substances, the other acted as control.

The experiments documented that the group of animals impacted by hazardous substances via their food suffered damage to their health.

"For polar bears it cannot be concluded that there is a cause and effect relative to environmental contaminants and state of health, but the experiments with polar foxes and sledge dogs support the theory that there may be such a connection,” states Christian Sonne, who emphasises the importance of understanding that all the organs and systems of the polar bear function in harmony.

Contact

Senior scientist Christian Sonne, NERI, tel. +45 4630 1954, csh@dmu.dk

Health effects from long-range transported contaminants in Arctic top predators: An integrated review based on studies of polar bears and relevant model species. Sonne, C. 2010. Environment International. Elsevier - p. 31.

Links:

Environment International (subscription necessary)

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