Researchers studying polar bears in Greenland have identified plastic pollution as yet another threat to the survival of the species. Already threatened by climate change and shrinking sea ice, the study found that plastic pollution and pesticides are harming the endocrine systems and reproductive systems of these mammals.
Polar bears are classified as “vulnerable” (just one step away from “endangered”) by the International Union for Conservation of Nature (IUCN). Climate change still poses the biggest problem, but there are other factors contributing to declining polar bear numbers.
"The health of the arctic polar bear is being attacked from all fronts, but among many other factors is the exposure to environmental contaminants," said María Jesús Obregón in a press statement. Obregón is one of the authors of a paper on the findings, which is published by the journal Environmental Research. The researchers studied muscle tissues, liver tissue and plasma to identify contaminants and their metabolites.
It’s easy to imagine plastic pollution as bottles, bags and food packaging floating in the water, but most plastic contamination spreads through the ocean as tiny bits. These microplastics come from larger items disintegrating, are shed from synthetic fabrics or come in the form of microbeads used in personal care products. Tiny bits of plastic containing toxic compounds are easily eaten by fish and birds. The toxins bind to fatty tissues and can move up the food web. Because polar bears sit at the top of the food chain, their intake of toxins may be particularly magnified, according to the IUCN. An earlier study found that similar bioaccumulation has caused polar bears to consume high levels of mercury.
The researchers have also created a new tool to help assess polar bear health. The tool uses a survey to address the many factors that impact polar bear health, including access to food, stress, exposure to competitors, diseases, and climate change. Researchers hope the tool will help provide more data that can be used in polar bear conservation efforts.