A joint scientific effort by the National Environmental Research Institute in Denmark, the Geological Survey of Canada, and Environment Canada, answers the question of how much mercury concentrations in the Arctic is natural and how much is man-made. Through the tests of Arctic marine wildlife teeth, hair and feathers, and comparisons with historical samples, they found that mercury levels rose in the mid-19th century and accelerated in the 20th century. The sharp increase corresponds to the industrial revolution. Although there is no major mercury source in the region, mercury pollution is brought to the area through the atmosphere, ocean currents, and rivers. The study found that the average man-made contribution to current mercury concentrations is 92.4%. The significant increase in mercury concentrations in marine foodwebs in the Arctic have reached dangerous levels where negative biological consequences are expected. People living in these areas and eating at the top of this food chain may see neurological development disorders in their children.