More than a hundred university scientists in Michigan are urging the state's members of Congress to support stricter controls of mercury.
The federal Environmental Protection Agency is ready to phase-in tougher standards on the main source, old coal fired power plants. But some U.S. Senators are trying to block that move.
The scientists say it's well established that mercury is a potent toxin that can impair brain and nervous system development in children and new research suggests it may also affect the heart, lungs and immune system.
Nil Basu, a toxicologist at the University of Michigan, says most people are exposed after consuming contaminated fish.
"We found elevated levels of mercury in all of our lakes, rivers and forests. Mercury is found in all fish, birds and mammals in the state of Michigan," he says.
Basu also says new research suggests it may have more toxic effects than previously thought.
"The more we research mercury, the more we realize that there may actually not be a threshold of harm, meaning that no amount of mercury is safe," he says.
The scientists say the new EPA standards would prevent several hundred deaths and save more than a billion dollars in health costs in Michigan over the next four years.
The main way mercury is released into the air is from burning coal in old power plants and a group of mostly Republican U.S. Senators is moving to block the new EPA standard. They say it's part of a calculated effort to kill affordable energy like coal.
Oklahoma Senator James Inhofe says the costs to control mercury vastly outweigh the benefits and will send the price of electricity skyrocketing.