Washington ? Environmental groups are upset about a new federal effort to cut mercury emissions at dozens of cement plants across the country, saying it defies a court order to toughen controls on the highly toxic air pollutant.

The 200-plus cement kilns in the United States are the nation’s second-largest mercury emitters after coal-fired power plants, which are installing pollution-control equipment under state programs required by the Environmental Protection Agency.

James Pew, a lawyer with Earthjustice in Washington, said the mercury standard that the EPA announced Monday applies only to new or modernized cement plants. He said the regulation doesn’t require the owners of existing kilns to retrofit them with scrubbers or other equipment to reduce mercury emissions.

“The EPA decided to allow every cement kiln to continue to emit as much mercury as it likes,” Pew said. “This is part of a long string of agency refusals to obey the law.”

Keith Barnett, an EPA environmental engineer who helped craft the mercury rule, said it satisfies the 1990 amendments to the Clean Air Act, in which Congress listed 189 of the most toxic pollutants and directed the EPA to set limits on them.

“We determined that what cement kilns are currently doing meets the minimum requirements under law,” he said.

Mercury, a heavy metal whose consumption has been linked to memory loss, birth defects and other neurological disorders, enters waterways from rain. Its toxicity is then concentrated by a type of water bacteria. Fish transmit mercury to people, with tuna and other species higher in the food chain carrying higher levels.

At least 40 states have warned residents about eating mercury-laden fish from their lakes, rivers and creeks.