article_snippet: The pollutants, known as perfluoroalkly compounds, accumulate in specific areas of polar bears' brains over years of eating contaminated food.
article_snippet: The chemicals get into the oceans from run-off from landfill and gradually filter up through the food chain, buidling up in the largest predators.
article_snippet: Organohalogens contain at least one halogen such as fluorine or chlorine, and are used as solvents and pesticides, as well as in the making of dyes and drugs.
article_snippet: PCBs were used to make paints and rubber goods in the 1930s, but were banned in 2001 after scientists discovered scientists can cause cancer.
article_snippet: The researchers from Aarhus University in Denmark warn that the presence of such chemicals, which tend to accumulate over time in the bodies of top predators from the prey
article_snippet: Researchers found that in particular perfluorooctane sulfonate (PFOS), which is as a strain repellent treatment for fabrics, and perfluorinated carboxylic acid, which are used to make non-stick coatings, were associated with changes to key neurotransmitters in the bear's brains.
article_snippet: Perfluorooctane sulfonate (PFOS), the chemical structure of which is shown above, was widely used as a stain repellent and protector for fabrics but has been found to accumulate within the bodies of top marine predators . '
highlights_snippet: Researchers at University of Copenhagen found perfluoroalkyl pollutants accumulated in the animals' brains .
  