"The recommendation was based on a growing number of scientific studies showing that even low blood lead levels can cause lifelong health effects," the CDC said, in adopting the recommendation of an advisory committee. "Today, CDC is officially announcing our agreement with that recommendation."

The new "reference value" for lead poisoning was based on the population of U.S. children aged 1 to 5 years whose blood lead levels are in the highest 2.5 percent of children tested, the agency said.

About 450,000 U.S. children aged 1 to 5 have blood lead levels above the new standard, up from 250,000 with lead levels greater than 10 micrograms per deciliter of blood under the previous threshold, according to the CDC.

High levels of lead in a child's blood can cause coma, convulsions and death, and even low levels can cause decreased intelligence and impaired hearing, the agency said.

The leading sources of lead exposure to U.S. children are lead-based paint, which was banned for use in housing in 1978, and lead-contaminated dust, the CDC said.

Despite the new guidelines, the CDC has no money to pay for expanded programs to fight lead poisoning, Christopher Portier, director of the CDC's National Center for Environmental Health, told Reuters.

In the 2012 fiscal year, Congress cut funding for the CDC's Childhood Lead Poisoning Prevention Program to $2 million from $29.2 million, he said. But the agency can still work with public health departments, schools and other partners to help combat lead poisoning, Portier said.

"Parents can act without the CDC being there," Portier said, suggesting they could contact local health departments for testing of paint and dust to detect high lead levels.

The CDC also recommends parents regularly wash children's hands and toys, and wet-mop floors and windowsills, in addition to preventing children from playing in bare soil.

(Editing By Cynthia Johnston and Peter Cooney)

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