Various factors—ocean currents, atmospheric patterns, climate conditions—coincide to make the Arctic a sink for long-range pollution. As a result, scientists have been keeping a close eye on wildlife in the region to identify which species are at most risk from chemical contaminants.

In general, species that occupy the tops of the food chains often exhibit the greatest concentrations of contaminants in their bodies. As food moves up the food chain, contaminants are stored in increasing concentrations in each animals' body.

Scientists have now found that of all Arctic animals, orcas (Orcinus orca) have been exposed to the greatest amount of contamination. Tests have shown that their tissues contain pesticides, flame retardants and PCBs, some of which have been banned from use for many years.

Find out more:

• Chemicals Threaten Arctic Wildlife (A&W Article)
• Norwegian Killer Whales Most Toxic Mammals in Arctic (WWF)
• Toxic Chemicals (WWF)
• Arctic Orcas Highly Contaminated (BBC News)
• Killing Killer Whales with Toxics (WWF Radio)