A federal study released in February found dangerously high levels of 70 contaminants in forests in the western United States. The contaminants including pesticides and mercury were found in snow, air and water in more than 20 national parks and monuments. The six year study was conducted by the National Park Service, the U.S. Environmental Protection Agency (EPA) and several other federal agencies and was the first to measure the levels of man-made toxic substances in parks. Scientists were surprised by the results. Sequoia and Kings Canyon in California was among the worst locations for the levels of contamination. Yosemite was reviewed with less rigor but contaminants were found there as well. Mercury from coal-fired power plants, PBS from industrial activity and banned insecticides such as DDT were among the most alarming contaminants discovered in the parks. The effects of these substances are magnified the higher up the food chain they travel, adding to scientists concern. Fish from a number of parks, including Daniel in Alaska, were found to have levels of these substances higher than the allowable threshold for human consumption set by the EPA. In Glacier National Park the contamination caused male fish to develop female sex organs. Researchers suggest limiting emissions from coal-powered plants and placing tighter regulations on the use of pesticides to combat the problem, though they noted some of the pollution may be coming from overseas, putting it beyond the U.S. governments control.