Killer whales top toxic charts in Arctic
Killer whales have overtaken polar bears to take the dubious honour of becoming the most toxic mammal in the Arctic.According to a study commissioned by the WWF, with their mixed diet and covering long distances pods of orcas are picking up more contaminants than any other species in the Arctic circle.
Due to prevalent water and air currents many contaminants accumulate in the frozen north and ecologists consider the findings in the Arctic and early warning system for the rest of planet.
Hans Wolkers, a toxicologist with the Norwegian Polar Institute working for the WWF, has been testing samples of blubber taken from the orcas for toxicity.
"I took away ten samples for testing and the results were shocking," he said.
"All ten showed consistently high levels of toxins. You name it, the whales had it - PCBs, pesticides and at least one type of brominated flame retardant. They are the most toxic mammal in the Arctic."
Wolkers' research shows that orcas outstrip the polar bear in terms of pesticides and one type of brominated flame retardant, in addition to the high levels of the toxic, persistent chemicals PCBs (polychlorinated biphenyls).
According to scientist, the appearance of a brominated flame retardant, a type of chemical found in every day articles such as computers, is particularly worrying because unlike PCBs and the most harmful pesticides, most are not currently banned.
Part of the problem for the whales is their position at the top of the food chain, and their broad diet that takes in fish, squid, mammals such as walruses and sea lions, sharks and even other whales.
This means they take in toxins that have built up in all manner of life.
"Killer whales are particularly vulnerable to contaminants because they feed at the top of the food chain and accumulate contaminates from the species they prey on," said Brettania Walker, a toxics officer with WWF's Arctic Programme.
"These contaminants accumulate in their blubber over time. As killer whales can live up to 40 years, this means they can have very high contaminant levels in their tissues."
The WWF claims the findings of the new research demonstrate more than ever the need for tighter regulation of toxic chemicals under the European REACH programme.
Walker said: "This new killer whale research underlines the need for all hazardous chemicals to be replaced with safer alternatives when they are available."
By Sam Bond
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