NEW YORK — More than half a million US children are now believed to have lead poisoning, about twice the previous high estimate, health officials reported Thursday.
The rise 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 a lower IQ. Lead poisoning used to be a much larger concern in the United States, but has declined significantly as lead was removed from paint, gasoline, and other sources.
The new number translates to about 1 in 38 young children. That estimate suggests a need for more testing and preventive measures, some specialists 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 on 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 .
Most cases of lead poisoning are handled by tracking and removing the source, and monitoring the children to make sure lead levels stay down.
Often, children who get lead poisoning live in old houses. They pick up and eat paint chips. Children have also picked up lead poisoning from soil contaminated by old leaded gasoline, from dust tracked in from industrial worksites, from tainted drinking water.
Lead has been banned in household paint since 1978 and was gone from gasoline by the late 1980s.