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.
Multiple studies released in August 2009 provide evidence of rising mercury contamination of the environment, fish and people. The evidence that mercury levels have risen in people in the past several years is presented in a report released by UCLA, Assessment of chronic mercury exposure within the U.S. population, National Health and Nutrition Examination Survey, 1999–2006. While inorganic mercury was found in the blood of 2% of women in 1999, it was found in 30% of the women by 2006. Another U.S. study, Mercury in Fish, Bed Sediment, and Water from Streams Across the United States, 1998–2005, found mercury in all the sampled fish, with 27% exceeding levels safe for human consumption. A third study indicates that mercury levels in fish were elevated in pristine forested or woody-wetlands in the eastern and southeastern U.S. Duke University environmental engineers explain this phenomenon in a study of their own: How Mercury Becomes Toxic in the Environment.