The rules, under review by the White House Office of Management and Budget, could be released as soon as next week, according to industry sources.

"Toxic mercury emissions from power plant smokestacks put countless infants and children at risk for brain damage," said Linda Greer a health expert at the Natural Resource Defense Council (NRDC) in a teleconference on Thursday. Delaying the program will result in several hundreds of tons of extra mercury emissions, NRDC officials say.

The rules would delay a cap-and-trade system to begin mercury emission reductions by 2018. The original plan, proposed by the Clinton administration, called for the cuts to take effect in 2008.

The EPA could not be immediately reached about the potential effects of the new rules.

One in 12 women of childbearing age have mercury levels in their blood that exceed levels that the EPA says is safe for fetuses, according to the Centers for Disease Control and Prevention.

Mercury emissions, 40 percent of which come from coal burning power plants, have been linked to neurological problems. It can be ingested by nursing babies whose mothers eat contaminated fish.

In 2002, 45 states issued mercury advisories, up from 27 states in 1993, according to Greer. She said 17 states have posted mercury advisories for every body of water inside their borders.

A utility industry spokesman said delaying the cap and trade program allows time for utilities to reduce emissions in a more practical, better way.

"Ninety percent reductions are not possible with today's technology, and they're (NRDC) out to lunch if they think that is a reality," said Frank Maisano, a spokesman for the Electric Reliability Coordinating Council.