The U.S. Centers for Disease Control and Prevention has updated its blood lead reference value – the level at which children ages 1-5 are considered to have high exposure to lead.
Since 2012, this threshold had been set at 5 micrograms of lead per deciliter of blood; children at or above this level represented the top 2.5% with the highest blood lead levels in the nation. In response to recent federal health surveys, the CDC has updated that number to 3.5 micrograms per deciliter.
I have studied urban lead poisoning in children; here's what this means for public health.
Will this change affect how doctors detect and treat childhood lead poisoning?
The CDC periodically reviews national data on blood lead levels in children. This new lower value is the average blood lead level exceeded by 2.5% of children tested.
Many clinics have an on-site screening device that use electrochemical detection to quickly test blood from a fingertip prick. If children test positive, doctors refer them to have a larger blood sample drawn and analyzed. The clinical test is fast, cheap and relatively painless, but the venous blood draw is the gold standard.
On-site clinical devices typically can detect lead at concentrations as low as 3.2 micrograms per deciliter, so the new CDC guidance means that nearly all children who show positive results at the screening level will be referred for follow-up testing.
This will roughly double the number of children classified as at highest risk.
Larger numbers of children means that many states will have trouble affording testing and follow-up care unless Congress increases federal support for programs to prevent and treat lead poisoning.
How are children commonly exposed to lead?
The most pervasive source is soil and dust generated from soil. Thanks to many years of emissions from degraded lead-based paint, leaded gasoline and industrial sources, typical urban soils have lead concentrations that range from benign to toxic. Children are exposed when they touch or play in contaminated dirt or inhale the dust.
The U.S. Environmental Protection Agency's limit for lead in soils in public play areas is 400 parts per million. That's significantly higher than typical background levels, which are roughly 20 to 50 parts per million.
It's not unusual to find urban soils with much higher levels.
The most lead-contaminated neighborhoods are often the poorest and home to the highest percentage of nonwhite children.
Lead-based paint is also a major exposure risk, particularly in poorly maintained buildings. Lead paint tastes sweet, so children sometimes chew on paint chips or painted wood.
Lead water pipes are a third source, although less common. Many cities and towns have lead service lines. If their water is treated properly, a protective plaque forms on the inside of pipes and seals their lead content away from the water.
But some cities have changed their water sources or treatment processes in ways that stripped out the protective plaque and carried lead to household taps. These water crises disproportionately affected communities of color.
How does exposure affect children's health?
Historically, public health interventions focused on acutely poisoned children who exhibited issues such as attention deficit, memory lapses, agitation and even tremors. As blood lead levels decreased, these obvious clinical presentations declined.
What we see now are more subtle neurocognitive deficits, which scientists and medical experts measure through neurological and behavioral testing.
These types of tests show that a blood lead level even lower than the new standard still affects performance. This research is the basis for statements from scholars and the CDC that there is no safe blood lead level in children.
What's the trend for childhood lead poisoning in the U.S.?
It has been falling since most major environmental sources of lead were eliminated starting in the 1970s. Recent analyses show that the median blood lead level for all U.S. children between ages 1 and 5 is about 0.7 microgram per deciliter today, compared with 15 micrograms per deciliter in the late 1970s.
But Black children and children living in poverty have an average blood lead level 13% higher than this national average, which means that many are at risk.
For example, in a 2019 study, I worked with colleagues at Notre Dame to analyze blood lead levels of more than 18,000 children in St. Joseph County. In some neighborhoods, more than 30% of children had a blood lead level higher than 5 micrograms per deciliter, and more than 65% of the census tracts had an average blood lead level over that safety limit.
We also found there was no systematic, risk-informed approach to testing. In areas that had the highest potential risks based on poverty levels, fewer than 6% of eligible children had lead test results reported to the county health department – the same rate as in other, wealthier census tracts.
Without more screening, and more work to eliminate lead exposure in the communities most at risk, this problem won't be solved for a long time.
Gabriel Filippelli is the chancellor's professor of earth sciences and director of the Center for Urban Health at IUPUI.
The city of Fort Wayne's Office of Housing & Neighborhood Services offers a Lead Paint Remediation Program to help protect children from the dangers of lead poisoning.
City residents should call 260-427-8585 to see whether they qualify for the program.
Funding from the U.S. Department of Housing & Urban Development allows the city to remediate lead paint in about 140 Fort Wayne homes. Property owners may qualify for the program if:
• The home was built prior to 1978 (the year lead paint was banned for use in homes);
• A child or children younger than 6 reside in or regularly visit the home (expectant mothers also qualify);
• The parent or guardian is willing to have the child's blood tested for lead; and
• The household income of the occupants is less than $57,500 for a family of four or $46,000 for a family of two.
Funding is limited, so property owners are accepted on a first-qualified, first-served basis.