Researchers who spent three years testing yellow perch and loons across the Northeast have identified five areas where mercury emissions from coal-fired power plants and other sources accumulated to levels considered unsafe for animals and for humans.
The findings were published in the January issue of the scientific journal BioScience and presented publicly by the lead authors.
One hot spot cited in the study spans the upper Androscoggin River and Kennebec River watersheds in western Maine.
A lead author of the report, David Evers, is executive director of the BioDiversity Research Institute in Gorham. The study was coordinated and financed in part by the Hubbard Brook Research Foundation, a nonprofit forest research organization based in New Hampshire.
Evers said the research demonstrates a need for ongoing monitoring to protect people from exposure to mercury, which is toxic to the nervous system.
Maine and 43 other states already warn residents, especially children and pregnant women, to limit their consumption of fish caught in inland rivers and lakes.
"We found fish in remote areas of Maine with mercury levels four times higher than the (federal) human health criterion," Evers said. "We believe people need to know where these highly polluted lakes exist so that they can take appropriate precautions when choosing where to fish and whether or not to consume that fish."
Evers and the other authors said the study raises concerns about the U.S. Environmental Protection Agency's plans for a "cap-and-trade system" to reduce mercury emissions. The system would let power companies decide if they want to clean up their emissions or pay another to cut back its pollution. Critics fear the system would let older, dirtier plants keep pumping mercury into the environment.
The EPA issued a formal response to the study.
"Under the Bush Administration, the U.S. is the first nation in the world to regulate mercury emissions from coal-fired power plants," the agency said. It projects an 80 percent reduction in mercury deposition across the Northeast.
The EPA, while not promising it will monitor fish or loons, said it is working to establish a nationwide network of atmospheric mercury monitoring sites to estimate how much mercury is settling onto the ground or into waterways.
Maine's congressional delegation has been united in favor of more aggressive cutbacks in mercury emissions.
Aides for Sen. Susan Collins, R-Maine, and Rep. Tom Allen, D-Maine, said both will keep pushing for Congress to write tougher mercury restrictions. Both also now plan to submit new legislation calling for monitoring of mercury in the environment.
Collins issued a statement saying the study makes it clear that the EPA should not rely only on computer models to protect people from the risks. "I have long-argued that EPA used faulty science in order to justify an insufficient mercury rule, and these studies prove it," said Collins, who is calling for a 90 percent reduction in mercury emissions.
Scott Segal, a lawyer for the electricity industry, said a 90 percent cut is not feasible without switching from coal to an energy source such as natural gas, which is far more expensive.
Segal also said the latest research should prompt support for the EPA cap-and-trade program, not criticism of it, because it will encourage the dirtiest plants to clean up fastest.
"Only a cap-and-trade program ensures faster reductions at the higher emissions," Segal said. "If you have a high-emitting plant, you have an economic incentive to improve faster."