POP particles stick to vegetation and microorganisms that animals eat, or are ingested directly. Then the chemicals stay in the food chain and build up as one creature devours another.
Dirty Dozen Pollutants Ride Again
In the case of sharks near Svalbard, scientists suggested that the predators were more contaminated because they ate more seals than other Greenland shark populations. The seals contained higher levels of POPs than other prey, because the POPs in each fish the seals ate subsequently became trapped in the seals' fat. When the sharks ate the seals, the POPs continued to build up.
Previous research on Greenland sharks from near Iceland and the Davis Strait in Canada found lower levels of POPs, likely because these sharks ate fewer seals.
Polar Bears Dining on Strange, Toxic Seals
Liver samples from the Svalbard seal-eating sharks revealed lower than normal levels of Vitamin A and higher levels of Vitamin E, which may have been a biological defense reaction to the POPs.
"We can conclude that the contaminants lead to reduced levels of vitamin A and increased levels of vitamin E in the sharks around Svalbard, but we don't know if this affects their health or reproduction," study co-author Bjørn Munro Jenssen of the Norwegian University of Science and Technology said in a press release. "We would have to study the species for many years.