As if melting ice in Polar bears' Arctic habitat was not enough, Norwegian scientists have found that organic pollutants such as pesticide residues are disrupting their thyroid and endocrine systems, adding a further threat to the species' survival.
As if melting ice in Polar bears' Arctic habitat was not enough, Norwegian scientists have found that organic pollutants such as pesticide residues are disrupting their thyroid and endocrine systems, adding a further threat to the species' survival.
Greenland's polar bears have a thyroid problem. Their endocrine systems, too, are being disrupted.
In both cases the culprit agency is environmental pollution by a range of long-lived industrial chemicals and pesticides.
This is the conclusion of a new paper by Kristin Møller Gabrielsen of the Norwegian University of Science and Technology in Trondheim and colleagues in the journal Environmental Research.
The scientists examined the liver, muscle and kidney tissues taken from seven polar bears killed by Inuit hunters in East Greenland in 2011 and analysed the effect of more than 50 contaminants in plasma samples from Ursus maritimus.
Their aim was to see what effect organohalogen compounds could have on the bears' thyroid systems, which are physiologically essential for growth, development, reproduction, stress response, tissue repair, metabolism and thermoregulation (an animal's ability to keep its body temperature within limits).
High concentrations of contaminants
Thyroid disruption at any stage of life can be damaging to all mammals and their chances of reproductive success, but thyroid regulation is vital in the earlier stages of life.
But the researchers found high concentrations of plastic pollution and pesticide contamination in the creatures' tissues, many of which could affect the hormonal systems.
"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 Maria Jesus Obregon, of the Biomedical Research Institute in Madrid, one of the authors.
"A wide variety of organochlorine compounds and pesticides have an effect on the thyroid hormones in plasma, tissues and deiodinase enzymes, which are in charge of stabilising the thyroid hormones in tissues."
As a marine mammal, the bear is exposed to a huge range of pollutants delivered by modern industry, transport and commerce. Many persistent pollutants are concentrated as they move up the food chain making high level predators like large cetaceans and polar bears most vulnerable to their impacts.
Continue reading at ENN affiliate, The Ecologist.
Polar bear image via Shutterstock.
