Pollutants weaken polar bears in East Greenland: researchers
"Shrinking balls and degraded bones" linked to pesticides, flame retardants
COPENHAGEN — Persistent organic pollutants used in industry are changing the genitals and bones of polar bears in East Greenland, says a Danish wildlife veterinarian and toxicologist.
“Shrinking balls and degraded bones,” linked to the presence of pesticides and flame retardants in the Arctic, are likely to affect the animals’ fertility and reproductive success, said Christian Sonne at last week’s conference on Arctic climate change and pollution in Copenhagen.
These impacts from POPs are “not just” affecting polar bears, said Sonne who works at the National Environmental Research Institute of Denmark.
People and other animals in Canada’s Arctic may also be at risk of similar effects from these pollutants, although the toxic “cocktail” becomes somewhat lower as you head west from Greenland across the Arctic region, he said.
Polar bears from East Greenland are among the most polluted species in the Arctic because their diet depends on contaminant-loaded blubber from ringed and bearded seals.
Add a warming climate to this mix, and the combined effect may be disastrous to the survival of the species.
Sonne’s latest research shows East Greenland polar bear bones are getting weaker.
For his study he looked at a wide sample of polar bears from 1983 to 2001 and then went to museums to analyze samples from polar bears captured as far back as 120 years ago.
Bone weakness reveals the amount stress that an organism experiences, Sonne said.
In East Greenland, that stress can be related to contaminants, temperature, precipitation, and decreasing sea ice.
These all influence health, he said.
Sonne’s study established a link between bone density and the presence of polychlorinated biphenyls (PCBs), chemicals used in industry.
Because polar bears are highly adapted to their Arctic environment, they’re also highly vulnerable to environmental changes.
This makes them an “excellent global thermometer” for showing environmental changes, he said.
The bone density decrease was severe in some of the adult male polar bears he studied. In fact, their bones were in such bad shape that those polar bears could develop chronic osteoporosis, which leads to bone fractures and deformities, he said.
Sonne, who has also studied genitals from East Greenland polar bears, continues to find links between the presence of the pollutants and the size of polar bear testes.
Sonne and his colleagues say the higher the level of the pesticide chlordane found in bears, the smaller the size and the weight of their testicles and penis bones.
As a result, there’s “a reduction in quality and quantity of semen.”
Ovary size and weight in female bears also decreases as contaminant levels rise, Sonne has found.
The presence of flame retardants also may be linked to bone strength and sexual organs, particularly in cubs.
The sum of these impacts can affect polar bear fertility and reproduction, he said.
Sonne’s latest research shows that sled dogs are also damaged by contaminants from a diet heavy in marine mammal blubber, because it appears to weaken their immune system.
This would make the dogs more susceptible to infectious disease.