Pennsylvania and 10 other states have sued the U.S. Environmental Protection Agency for adopting a federal rule to control mercury emissions from electric power plants that they say will not protect human health.

The state Department of Environmental Protection also will recommend new mercury controls for Pennsylvania's 70 coal-burning facilities that are tougher than the federal rule adopted in March.

The lawsuit, filed yesterday in the U.S. Court of Appeals for the District of Columbia, challenges the EPA's decision to establish a cap-and-trade program to control toxic mercury emissions that will cut emissions at some, but not all, coal-fired power plants to achieve reductions of up to 70 percent by 2018.

The federal rule changed the designation of mercury to a nonhazardous substance, backed away from a 90 percent emissions reduction goal, and could create "hot-spots" of mercury contamination around power plants that choose to trade for mercury credits rather than cap their emissions, the lawsuit says.

Three of the 13 biggest mercury emitters are coal-burning power plants in Western Pennsylvania.

"The administration's mercury proposal is insufficiently protective of public health," said DEP Secretary Kathleen McGinty. "EPA was right in 2000 in recognizing mercury as a hazardous air pollutant that needs to be regulated strictly. They are wrong now in changing course."

Coal-fired power plants are the largest source of mercury emissions, generating 48 tons annually nationwide. They have been exempt from mercury controls adopted in 1990 Clean Air Act amendments.

The EPA finalized the new, industry-backed rule in March.

Eryn Witcher, EPA press secretary, said the federal rule will effectively reduce emissions of mercury from power plants and the agency will "vigorously defend the Clean Air Mercury Rule against any challenge."

Utility industry groups charged the states are trying to "gum up" implementation of the rule, saying the EPA has "ample legal authority and scientific justification" to establish the cap-and-trade rule.

"Reasonable people can disagree over the best way to achieve environmental goals," said Dan Riedinger, a spokesman for Edison Electric Institute, a utility trade association. "But suing to block this rule altogether can only undermine, not augment, the 70 percent mercury emission cuts the EPA has set in motion."

The DEP also responded positively yesterday to an August petition by 50 state and national environmental, labor, public health, sporting and faith-based organizations calling for a tougher rule on mercury emissions than the national standard. New Jersey, Massachusetts, Connecticut and Wisconsin have already passed such rules.

"We believe any new power plants should face the most stringent regulations for mercury," said Kurt Knaus, a DEP spokesman. "And we want to encourage existing facilities to repower with new technologies that will make them cleaner."

But several of the 50 petitioners were critical of the DEP's 13-page response, saying the department did not endorse the goal of 90 percent mercury emissions reduction that is achievable with new technologies and that is part of New Jersey's tougher emissions law.

"We're pleased that the DEP opened the door to a new state rule but disappointed that the state will wait for an extended additional time to deal with this critical public health problem," said John Hanger, president and chief executive officer of Citizens for Pennsylvania's Future, one of the lead petitioners.

"Given the DEP's initial weak response to the petition, it is even more critical that Pennsylvanians contact the governor's office and call for a strong rule to cut mercury pollution," said Nathan Wilcox, of PennEnvironment, a petitioner that will conduct door-to-door canvassing on the mercury issue this summer in Pittsburgh, Philadelphia and Allentown.

Knaus said that the DEP is still reviewing the New Jersey rule and some parts of it could become part of the Pennsylvania rule. He added that Pennsylvania's regulation of more than 70 major mercury sources will necessarily be more complex than New Jersey's rule regulating five.

Hanger said that's not necessarily so.

"I think the DEP could have gone further in its response by offering regulatory specifics we could comment on," Hanger said. "The 90 percent reductions are feasible and there's nothing about Pennsylvania power plants that distinguish them operationally from New Jersey power plants. Suggesting otherwise is a red herring."

Contaminated fish are the primary route by which humans are exposed to mercury, a toxic, persistent, pollutant that is released into the air when coal is burned. It falls to the ground and into water where it accumulates in the food chain. High mercury exposure can cause attention and language deficits, memory loss, and impaired visual and motor functions.

The petitioners have 30 days to respond to the DEP, and the department will then have six months to prepare and submit a rule to the state Environmental Quality Board for approval.

That process is expected to take 18 months to run its course, but disposition of the 11-state federal lawsuit could take even longer.