The sad photos of polar bears swimming with no solid ice in sight are unsurprising images in 2015; however, the challenges of polar bear survival extend beyond the visually obvious. Chemical pollutants are also harming arctic wildlife.
To understand the situation in the arctic better, research focuses on chemicals which are highly persistent in the environment. This means that the chemical lasts for a long time without easily being degraded by biological, chemical, physical, or light reactions. Chemical traits such as highly stable intramolecular bonds lead to chemical persistence.
Organic pollutants are frequently found in the Arctic or Antarctic because these are major sink regions in global geochemical processes. For example, refrigerators’ coolants called chloroflurocarbons (CFCs) have been found in the Antarctic. These compounds accumulate over the winter season and move up from the troposphere to the stratosphere. In the spring, they decompose ozone due to the increase in solar exposure. This process has led to the formation of the ozone hole. More recently, a similar phenomenon has been recorded in the Arctic.
Not only are well known anthropogenic substances found in the Polar Regions, emerging contaminants are now requiring research and attention. An example of an emerging contaminant of interest in the Arctic is perfluoroctane sulfonate (PFOS). Chemicals have different mechanisms for entering environmental systems. PFOS can be released into the environment directly or form by reactions where precursors are degraded. Two reaction processes of note are atmospheric oxidation and biotransformation.
Biotransformation is a reaction where a chemical is altered within the body.
The concentration of contaminants in wildlife could come from a number of sources such as absorption, bioamplification or biomagnification (see figure below). When studying PFOS in wildlife, researchers are interested in metabolism of the chemical and its precursors. In polar bears, it has been found that precursors to PFOS can accumulate and biotransform.
With all this said, why should we care about PFOS? In order to determine the effect of PFOS, we should consider a number of factors such as the quantity released into the atmosphere, toxicity, bioavailibility etc. This information package logically presents the highlights these factors.
Polar bears which are accumulating PFOS from biotransformation could be at a high risk of disease and chronic toxicity. However, the specific effects remain unknown. Thus, extrapolation of these ideas suggests that the Arctic ecosystem could be affected directly or indirectly by PFOS.
If polar bears do not tug at your heart strings, this data further discusses the wide exposure of PFOS in human studies and carcinogenic studies in rats demonstrating concern for the hazards of this chemical. Moreover, reviewing the Materials Safety Data Sheet (MSDS) confirms these suspicions. Acute toxicity is the primary concern when handling the material. However, some information appears unknown while other sections dismiss potential hazards mentioned, such as the “environmental precautions” section. Thus, more research into PFOS and its effect in the environment should transpire to have more conclusive direction forward.
Feature image from: http://www.zmescience.com/ecology/
Read the primary research paper here: Chemosphere, 2014, DOI: 10.1016/j.chemosphere.2014.04.022
Letcher, R.J., Chu, S., McKinney, M.A., Tomy, G.T., Sonne, C., Dietz, R. (2014) Comparative hepatic in vitro depletion and metabolite formation of major perfluoroctane sulfonate precursors in arctic polar bear, beluga whale, and ringed seal. Chemosphere.
Adelle has received her B.Sc. in Integrated Science with Biochemistry. Through her studies, she gained a reputation as an ideas person, an encourager to her peers, and a hard worker. She aims to continue exploring, innovating, and inventing at every opportunity that arises.