This article offered new explanations to how Polar Bears have adapted to such harsh enviornments, how far they explore the icy terrain, and how they survive long periods of time without food.  Malcolm Ramsey and Sean Farley, the two leading researchers for the study, have collected data on more than 2,000 polar bears.  Today, between 25,000 and 40,000 polar bears roam the icy plains.
    The most threatening thing for polar bears, the researchers have found, is the toxic contaminents found in the animal's fat and milk.  Ramsey tests the bears twice each spring for these contaminents.
    A pregnant female can increase her body fat 50 percent or more.  They build a 5 inch layer of fat around their legs and rump.  This is to provide fro a rise of metabolism when food is scarce.  Polar bears fast for a period of eight months.

Nicklin, Flip.  "Polar Bears".  National Geographic.  January, 1998.