New research suggests that endocrine disrupting chemicals (EDCs) could have a detrimental effect on the mating habits of polar bears.

© BJ Kirschhoffer/Polar Bears International

1/28/2015 5:17:50 PM

Industrial Chemicals Reduce Bone Density in Polar Bears

Could the chemicals we release into the ecosystem be responsible for reduced bone density in polar bears? New research from Aarhus University in Denmark suggests that endocrine disrupting chemicals (EDCs) could have a detrimental effect on the mating habits of polar bears and, as such, on their population.

Specifically, the research shows that, among certain populations, weakness of the baculum, or penis bone, of the bears could lead to reproductive issues and ultimately an increased risk of the species' decline in numbers. 

The authors of the study wrote, "... reductions in penile BMD (bone mineral density) could lead to increased risk of species extinction because of mating and subsequent fertilization failure as a result of weak penile bones and risk of fractures."

But that's not the whole story.

"This is one facet of much larger threats to polar bears," said PBI Senior Director of Conservation Geoff York. "The toxicology studies from Aarhus University have been critical to our broader understanding of the physiologic impacts of contaminants exposure to marine mammals. This paper is the latest in that string of bad news."

York went on to say that there is a minor upside. PCB (polychlorinated biphenyl) accumulations vary considerably across the Arctic, with a peak in the North Atlantic. Also PCB use, and its release into the environment, was banned in 2001; its presence in the ecosystem will gradually decline.

"This new finding is likely impacting bears in a small area, northeast Greenland and possibly the Barents Sea-at least at present," York said. "The downside is that there are a host of other endocrine-disrupting chemicals still in use today and very limited research on either environmental accumulation or health impacts. 

York said increased monitoring is needed range-wide on both toxins and disease. Research should also include anticipated changes driven by a warming planet.

"The elephant in the room for polar bears, and many other species, is still climate change," York said.

Global warming is the primary threat to polar bears. It is expected to trigger a host of cascading effects from habitat alteration, habitat loss, range shifts, and ultimately declining population numbers.

"Toxins like endocrine-disrupting PCBs, along with disease, are two potentially significant wild cards in the climate puzzle. Historically, neither has been a significant threat to polar bears, but that could all change abruptly. New findings such as this are critical to expanding our understanding of both the potential risks and drivers. The same effort is needed on disease vectors," York said.

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