08/04/2010 01:13 pm ET Updated May 25, 2011

Chemical Contamination in the Arctic: A Growing Threat to Polar Bears, Arctic Wildlife, and Possibly People

Polar bear with cub (Scott Schliebe/USFWS)

When it comes to the Arctic, a lot of attention gets directed towards climate change and oil and gas drilling.  And rightfully so.  Global warming poses an existential threat to the Arctic ecosystem as we know it; oil and gas exploration is a real threat to specific areas.  But one issue that gets comparatively little attention is the growing toll that chemical contamination may be taking on the Arctic’s wildlife, especially polar bears.

Visit NRDCs Switchboard BlogAs I’ve noted before, the Arctic is remarkable contaminated with a host of chemicals, such as organochorines, polybrominated diphenyl ethers (PBDEs) perflourinated compounds (PFCs), and mercury, all of which are produced or discharged during industrial processes and transported over long-distances to the Arctic, where they work their way up the food chain, in increasingly concentrated doses, until they reach top predators such as polar bears.

In a new study, Danish scientists Christian Sonne, provides a in-depth review of the data on these chemicals’ effect on polar bears, bolstered by controlled studies on captive Arctic foxes and sled dogs.  The results are sobering.  According to Sonne:

  • Evidence of “multiple OHC [organohalogenated contaminants] and mercury induced sub-clinical health effects” were found in polar bears.  These included thing such as: thyroid hormone disruptions, disruption of sex steroids, morphological changes in polar bear livers (e.g., lesions), changes to the thyroid and adrenal glands, enlarged clitorises, decreased testes size, and several changes to the immune system.
  • The estimated TEQ (Toxic Equivalency Quantity) exposure for some of the studied chemicals was 32-281 times the World Health Organizations guidelines for human exposure. 
  • PFC concentrations were likely to “exceed population effect threshold levels around year 2012” based, in part, on modeled effects on “reproductive performance.”
  • The theoretical mortality risks to polar bears from changes in organ systems (e.g., chronic renal failure) “may be as high as 38%.”
  • Finally, the combination of impaired immunity from “chemical stress” and decreased fecundity “could result in polar bear population declines.”

As the study notes, what we have here is nothing short of “a large scale experiment of what happens when a chemical cocktail of thousands of toxic contaminants interact in an uncontrolled way.”  One final thought: it’s worth remembering that polar bears aren’t the only top predators in the Arctic.  As Sonne points out, the Inuit people eat many of the same species that polar bears do.