NEW YORK - More than half a million U.S. children are now believed to have lead poisoning, roughly twice the previous high estimate, health officials reported Thursday.
The increase is the result of the government last year lowering the threshold for lead poisoning, so now more children are considered at risk.
Too much lead can harm developing brains and can mean lower IQs. Lead poisoning has declined significantly as lead was removed from paint and gasoline and other sources in the U.S.
The new number translates to about 1 in 38 young children. That estimate suggests a need for more testing and preventive measures, some experts said, but budget cuts last year eliminated federal grant funding for such programs.
Those cuts represent "an abandonment of children," said David Rosner, a Columbia University public health historian who writes books about lead poisoning.
"We've been acting like the problem was solved," he added.
Lead can harm a child's brain, kidneys and other organs. High levels in the blood can cause coma, convulsions and death. Lower levels can reduce intelligence, impair hearing and behavior, and cause other problems.
Most cases of lead poisoning are handled by tracking and removing the lead source, and monitoring the children to make sure lead levels stay down. A special treatment to remove lead and other heavy metals is used only for extreme cases.
Often, children who get lead poisoning live in old homes that are dilapidated or under renovation. They pick up paint chips or dust and put them in their mouths. Other sources include soil contaminated by old leaded gasoline, dust from industrial worksites and tainted drinking water.
Lead has been banned in household paint since 1978 and was gone from gasoline by the late 1980s.
After lowering the standard, the Centers for Disease Control and Prevention looked at old blood tests from 1,653 children under 6 to determine how many would have lead poisoning under the new definition.
About 3 percent of them - or about 50 kids - had blood lead levels higher than the new threshold of 5 micrograms of lead per deciliter of blood. Using that result, CDC officials calculated that an estimated 535,000 young children have lead poisoning.
A year ago, when the threshold was 10 micrograms, experts estimated that somewhere between 77,000 and 255,000 young kids had high levels of lead.
These estimates have focused on children younger than 6, who have been considered most at risk of neurological problems.
The new CDC study found lead counts were higher in poor or African-American children, said the CDC's Mary Jean Brown, an author of the study. Those kids are more likely to live in old housing or in neighborhoods with greater exposure to lead, she added.
The good news: Even with the lower threshold, lead poisoning appears to still be declining. Years ago, some local health departments began tracking the number of kids with blood levels at 5 or greater, and they say those numbers have been dropping steadily.
However, it's likely that many children with lead poisoning have not been diagnosed. In the CDC study, elevated lead levels were discovered for a third of the children only when they were tested by researchers.
"When you look for it, you find it," Columbia's Rosner said.
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