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Why do polar bears have high amounts of polychlorinated biphenyls - PCBs - in their fat?
Wiki User
∙ 10y ago
Polar bears are the top predator in the Arctic food chain, so they absorb all the toxic contaminants from the lower animals.
Polychlorinated biphenyls (PCBs) were once used as a cooling fluids and insulators in Transformers and electric motors, but were widely contaminating the environment, so in 2004 the international community acted to ban the synthetic chemicals.
PCBs dissolve easily in fat, and the mother bears' milk is rich in fat, so this is how they are passed on to the young cubs.
PCBs interfere with the bears' thyroid hormones, which are essential to control their temperatures In the freezing Arctic conditions.
A study in 2008 showed that amounts of PCBs in Norwegian polar bears have dropped significantly, though they are still at dangerous levels.
Wiki User
∙ 10y ago
Wiki User
∙ 14y agobecause they need fat to keep warm from the cold
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Are there any law that protects the giant otter?
Since 1973 there have laws restricting hunting of polar bears. Some numbers are still authorised in some countries.Since 2004 there are global bans on polychlorinated biphenyls (PCBs), a synthetic chemical that is still weakening polar bears.
Are polar bears desert animals?
a polar bear is not a desert animal it is a polar animal.
To what are polar bears related?
polar bears are related to bears.
Who saves polar bears?
Polar bears do.
How do the male polar bears and female polar bears make baby polar bears?
They reproduce.
Do polar bears grow fast?
POLAR BEARS Polar bears actually grow pretty fast.
Is polar bear a bear?
Polar bears are bears
What tpyes are polar bears?
Polar bears are mammals.
What are the polar bears predotors?
humans are polar bears
What is a group of Bear called?
A sleuth or a sloth of bears
Do you have polar bears?
Polar bears are animals of Arctic regions. The only polar bears here are in the NC Zoo.
What do the polar bears eat in the Antarctic?
There are no polar bears in Antarctica. If there were, they would eat the penguins.
