New Study on Arctic Polar Bear Health and PCBs – Norway

We all know that the Arctic sea ice has been receding, and is projected, according to many sources, to continue this trend into the foreseeable future.   This phenomenon has the potential to decrease the habitable land that polar bears require for denning, along with the ground from which they are able to hunt.  There is, however, some good news that has surfaced as a result of one study put together by 5 scientists, headed by J. Bytingsvik of the Norwegian University of Science and Technology in Trondheim (NTNU), Norway.  The study looked at the prevalence of PCBs in the polar bears of Svalbard, Norway.

Above Polychlorinated Biphenyls (PCBs)

Contaminants have been accumulating in the Arctic for a long time and eventually make their way into the bodies of various Arctic animals.  PCBs are no exception as they have made their way up to the Arctic through various air streams.  These compounds are reported to have the ability to travel for days before they are broken down by sunlight, or come down to the earth’s surface by way of rain or snow.

From the US Environmental Protection Agency,

PCBs were domestically manufactured from 1929 until their manufacture was banned in the United States in 1979 and throughout the world as per the 2004 Stockholm Convention on Persistent Organic Pollutants.  PCBs have been shown to cause cancer in animals.  PCBs have also been shown to cause a number of serious non-cancerous health effects in animals, including effects on the immune system, reproductive system, nervous system, endocrine system, and other health effects.  Due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications.

Bytingsvik’s Study (link at bottom)

The study, available as of January, of 2012 from the NTNU website looks at the plasma concentrations and prevalence of PCBs and hydroxylated PCB-metabolites (OH-PCBs) in mother polar bears and their 4 month old cubs from Svalbard, Norway.  In a nutshell, the study compared the concentrations of PCBs in these bears between the sampling years of 1997/1998, and 2008.  The study also looked at the propensity of mothers to transfer these compounds to their cubs through milk, and while still in the womb.

From Bytingsvik’s publication,

Plasma levels of PCBs and OH-PCBs in polar bears mothers and their suckling cubs were found to be significantly lower in 2008 when compared with results from 1997/1998.

She did however find that,

the levels of PCBs and OH-PCBs in cubs from 2008 were still above levels associated with health effects in humans and wildlife.

Studies have also been done in the past on the human ramifications of PCB exposure specific to our developmental stages.

Human infants that have been exposed to PCBs and OH-PCBs prenatally have shown lower birth weights, smaller head circumferences and alterations to thyroid hormone homeostasis.  Exposed children have also been shown to alter neural development, cognitive, motor, and learning abilities.

All in all, it shows that the global effort to reduce PCB pollutants has had a significant effect.  This is one matter that should lead the way for more positive-outcome thinking as it pertains to our global efforts to reduce the prevalence of harmful contaminants.

Sources

  • PCBs and OH-PCBs in polar bear mother–cub pairs: A comparative study based on plasma levels in 1998 and 2008 – 21/Jan/2012 – http://www.ntnu.edu/documents/139226/8932977/Bytingsviketal.pdf
  • Stockhold Convention – http://chm.pops.int/Home/tabid/2121/mctl/ViewDetails/EventModID/871/EventID/230/xmid/6921/Default.aspx
  • U.S. Environmental Protection Agency – Polychlorinated Biphenyls (PCBs) – Basic Information – http://www.epa.gov/osw/hazard/tsd/pcbs/pubs/about.htm
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