The Environmental Protection Agency has failed to protect children from rat poison exposure, a federal judge ruled yesterday, suggesting chemical manufacturers should add a bittering agent to keep children from ingesting their products.

Ruling in favor of two advocacy groups -- West Harlem Environmental Action and the Natural Resources Defense Council -- U.S. District Judge Jed Rakoff wrote that the agency failed to justify its 2001 agreement with pest control companies, which dropped two provisions from a 1998 rule requiring them to include a bittering agent and an indicator dye.

"In short, the EPA lacked even the proverbial 'scintilla of evidence' justifying its reversal of the requirement it had imposed, after extensive study, only a few years before," Rakoff wrote.

The battle over how to regulate rat poison started in August 1998 when the Clinton administration approved its use as long as manufacturers added a bittering agent and a dye that made it more obvious if a child ingested the poison. Three years later, Bush administration officials rescinded the requirements, on the grounds that they would make the poison less attractive to rats and could damage household property.

Rat poison accidents are on the rise, according to U.S. poison-control centers, and they disproportionately involve African American and Latino children. According to the EPA, 57 percent of children hospitalized in New York state for ingesting rodenticide from 1990 to 1997 were black, while only 16 percent of the state's population is African American. Twenty-six percent were Latino, although Latinos make up just 12 percent of the state's overall population.

"This is a big victory for children's health and environmental justice," said Aaron Colangelo, a lawyer for the Natural Resources Defense Council. "Parents now will be able to protect their kids and deal with rodent problems at the same time. There's no reason why any of our kids should be accidentally poisoned because it's relatively easy to protect them."

Millions of pounds of rat poison, often in the form of pellets that children sometimes mistake for candy, are applied nationwide each year in public housing, public schools and city parks.

Rakoff instructed the EPA to reconsider the rule. Spokeswoman Eryn Witcher said the agency "will be looking at the court's decision and determining what steps need to be taken to address the issue."

Bob Rosenberg, senior vice president of the National Pest Management Association, said he was confident the EPA would decide after a full review to "come to the same conclusion" it reached in 2001 on how best to prevent the spread of disease.

"Rats and mice don't like to eat pellets with bittering agents any more than people do," Rosenberg said. "I'm not too concerned EPA's going to come to a different decision. If they do, unfortunately, consumers will be losers. They're going to have products that are less effective."

Colangelo, however, said the agency would have to find an equally effective safety measure if it decides not to require a bittering agent. "They're going to have to do something significant to protect kids," he said.