Forty years ago, the typical American child under 5 had a blood-lead level of 15 micrograms per deciliter. That was considered healthy.
Today, children with a third that much lead in their blood are considered in danger — as in Flint, Mich., where public health officials are grappling with the fallout from contaminated water that has left dozens of kids with elevated blood-lead levels.
The contrast shows just how much progress we’ve made in understanding the dangers of lead exposure and in driving down blood-lead levels.
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But Flint’s crisis also illustrates how far we have yet to go.
Before the 1980s, the blood-lead levels we’re seeing now in Flint would have been considered pretty good, certainly better than the norm. When Dr. Philip Landrigan was doing his residency at Boston Children’s Hospital in the late 1960s, any blood lead level below 40 micrograms per deciliter was considered normal, he said.
But growing awareness of the dangers led to federal laws, enacted in the 1970s, to gradually eliminate leaded gasoline and paint. That shift was stunningly successful: the most recent data, from a 2011-2012 government survey, pegged the nation’s average blood-lead level for all age groups at or below 1 microgram per deciliter, down from nearly 13 in the late 1970s.
The dramatic reduction of lead from the environment has been credited for increasing IQ levels, boosting economic productivity, and slashing the crime rate. It’s “one of the great public health success stories,” said Dr. Alex Kemper, a pediatrician at Duke University School of Medicine.
But we’ve also come to understand just how harmful it is for developing children to be exposed to even low levels of lead, which can lower IQ, delay language development, cause hyperactivity and behavior problems, and induce other health issues over a lifetime. (Our understanding of the effects of low lead exposure on adults is less complete.)
Now, public health researchers agree that any lead in children is a danger. STAT talked to experts who called for prevention and treatment efforts to be concentrated in four key areas:
Focus on the black and poor children who are disproportionately affected
A good deal of the outrage over Flint — where the majority of the population is black and poor — has been driven by the sense that it wouldn’t have been allowed to happen in a wealthy white suburb.
Those demographic factors aren’t unique to Flint: Being black or poor makes children disproportionately likely to be exposed to lead. The most recent federal data, from surveys conducted between 2009 and 2012, shows that black children are nearly twice as likely as white children to have elevated blood-lead levels. Children living in poverty are four times more likely than their wealthier peers.
The challenge of reducing these disparities is closely linked to another problem: all the concentrated lead in the places where these children live and play.
Fix lead-laden old buildings in inner cities
As sources of exposure go, the corrosive water that degraded Flint’s pipes so badly that lead leached into the city’s drinking water is pretty unusual.
The leading cause of lead poisoning for children is lead paint and the contaminated dust from that paint in old buildings. A federal survey conducted a decade ago found that a third of homes across the country had lead-based paint somewhere in the building, with particularly high rates in the creaky old houses in the Northeast and the Midwest. Ongoing efforts to eliminate all that paint and dust are halting, and cost billions of dollars.
Another vexing issue: traces of leaded gasoline in the soil, particularly in urban areas. It isn’t being systematically studied or addressed.
Find better ways to help lead-exposed kids
We don’t have effective medical therapies for children, like those in Flint, who have been exposed to enough lead to cause serious neurological harm — but not enough to call for the use of powerful drugs deployed in acute poisoning cases.
“The treatment options aren’t good,” said Landrigan, who’s been studying lead exposure for decades as a pediatrician and epidemiologist at Mount Sinai Hospital.
Of the 114 Flint children under 6 with blood-lead levels deemed to be elevated in testing last year, four-fifths were between 5 and 10 micrograms per deciliter, according to data from the state of Michigan. The state didn’t immediately provide a distribution of the blood-lead levels of the 21 kids found to be over 10 micrograms per deciliter.
Children with blood-lead levels in the range of 5 to 40 or so micrograms per deciliter typically get “treated” with social services, educational support, and dietary changes to boost their intake of iron and calcium, which compete with lead for absorption at the same receptor sites. Increasing access to these interventions can help lead-exposed children catch up with their peers, but they’re not exactly medicine.
None of the experts interviewed by STAT could name anyone working on a new pharmaceutical approach for lead poisoning or exposure. One reason? Restoring brain function is extremely challenging.
“There’s a general sense that people aren’t working very hard on it because they don’t see any end in sight,” Landrigan said. “The biology gets in the way here.”
Another reason: “A lot of us that have been involved in lead research over the years are a little resistant to the idea of a pill to cure lead poisoning, because environmental management policies can be used to prevent this totally preventable disease,” said Kim Dietrich, a professor of environmental health at the University of Cincinnati.
Warn people against inappropriate therapies
As residents of Flint cope with the fallout, there’s likely to be no shortage of outsiders coming in to peddle would-be remedies. That worries Dietrich, who’s been watching with alarm as a growing industry, outside the medical mainstream, aims to broaden use of chelation therapy, a powerful class of drugs that cleans lead and other heavy metals out of the body.
To be sure, chelation therapy is an effective and widely used treatment for people who get exposed to very high levels of lead (typically 45 micrograms per deciliter for children).
But when blood-lead levels are significantly lower, as in Flint, these drugs haven’t been proven to help. Dietrich led a study from 1994 to 2003 that showed chelation therapy didn’t boost cognition or improve behavior for children with blood-lead levels below 45 micrograms per deciliter.
And the treatment can increase a patient’s risk for kidney damage and other serious side effects.
“My concern is that some of the patients in the Flint area … will be lured into getting chelation therapy where it’s not indicated and may actually have adverse strong effects as a result of these strong drugs,” Dietrich said.