Maine and more than a dozen other states are pushing for tougher limits on mercury emissions from power plants during arguments today before a federal appeals court in Washington, D.C.

The states challenged the U.S. Environmental Protection Agency’s rules governing mercury emissions that drift across the country and settle in forests and lakes in the northeast and other parts of the country. Mercury is a neurotoxin that accumulates in the food chain and is the reason Maine has placed a health advisory on eating freshwater fish statewide.

The states are arguing that the EPA rules violate the Clean Air Act because they allow plants to avoid limits by buying emission reduction credits from other plants that reduce emissions below targeted levels. The EPA argues that the rules will reduce mercury pollution overall in a cost-effective way, while the states say the credits allow localized mercury hot spots to develop.

Besides Maine, other states challenging the EPA rules are California, Connecticut, Delaware, Illinois, Massachusetts, Michigan, Minnesota, New Hampshire, New Mexico, New Jersey, New York, Pennsylvania, Rhode Island, Vermont and Wisconsin.