ore children across the US would likely be diagnosed with high lead levels under recommended guidelines approved this week by a federal advisory panel.
The panel voted to lower by 30 percent, to 3.5 micrograms of lead per deciliter of blood, the threshold at which a child is considered to have elevated lead. It’s a sign of increased awareness and concern about how harmful even low levels of lead can be for growing kids. And it could allow public health agencies to identify more sources of lead contamination.
The “reference level,” as it’s called, is currently set at 5 micrograms of lead per deciliter of blood for children under age six. When pediatricians detect lead at this level, they’re generally expected to initiate a conversation with parents about potential sources of lead and to report the finding to state health departments.
The Centers for Disease Control and Prevention will review the suggested change, made by one of its boards of scientists and other experts, before making a final decision later this year, agency spokeswoman Bernadette Burden said. Agencies tend to follow the advice of such panels.
The new recommendation comes months after lead contamination in the drinking water in Flint, Mich., sparked national outrage about potential long-term damage to the community’s children. The state found 114 children in Flint to have elevated blood-lead levels in 2015, according to a tally provided to STAT last year, but many more might have fallen into that category under the proposed new threshold.
The proposal to lower the threshold “reflects our knowledge about the harms of lead. It is also reflects the significant decrease in blood lead levels in the country over the past five decades,” said Dr. Alex Kemper, a pediatrician at Duke University School of Medicine who was not involved in the new proposal.
In the 1970s, the average American child had a blood lead level more than four times the proposed new threshold.
Today, the CDC and the Environmental Protection Agency agree that there is no level of lead that has been proven safe for kids. Elevated blood-lead levels in children have been shown to cause long-term developmental delays and cognitive problems, but the research is not clear on how much lead is required to cause serious and lasting damage.
Exposure can be mitigated by interventions in nutrition and other social services. But it’s not clear how helpful lowering the threshold would be for lead-exposed kids. The proposal does not call for follow-up interventions for kids with at least 3.5 micrograms or their parents.
That reflects a key potential challenge if the new threshold is turned into policy, because “clinical interventions have not shown an important impact for children whose blood lead levels are around 5 micrograms per deciliter,” Kemper said.
Kim Dietrich, a professor of environmental health at the University of Cincinnati who has long worked with lead-poisoned children, was the only board member of the CDC advisory panel who abstained from voting in favor of the proposal this week.
He told STAT he was not convinced that there is evidence of damaging neurodevelopmental effects for kids at 3.5 micrograms and is concerned that the technology pediatricians now use to measure blood lead levels is not sensitive enough to capture levels that low.
“I could not see how lowering this to 3.5 [micrograms] could be easily translated to important changes in public health and clinical practice. We’re not even doing a very good job at 10 [micrograms],” said Dietrich, who emphasized that he was speaking for himself rather than his panel or the CDC.