It’s killed some children slowly. It’s sent others into convulsions. But in Chicago, in the first decade of this century, a new study finds, the effects of childhood lead poisoning were more subtle—though perhaps equally as devastating. Research published in April by Environmental Health finds that even limited lead exposure in childhood is linked with dramatically lower third-grade test scores, in math as well as reading.
The researchers, mostly Chicago-based public health scientists, looked at a particularly large sample size of Chicago children—58,650—born in the Windy City between 1994 and 1998. First, they used a database of these children’s medical records, with a particular focus on the lead levels in their blood. Then the researchers compared those blood levels with those same students’ performances on third-grade standardized tests, taken in Chicago public schools between 2003 and 2006.
Even after adjusting for poverty, race, gender, and the education levels of each child’s mother, a strong link between lead in the blood and academic performance emerged: The presence of just 5 to 9 micrograms of lead per deciliter of blood (μg/dL, the standard measure for blood-lead levels) elevated the risk of failing math and reading standard tests by 32 percent. The researchers estimated that a full 13 percent of failing test numbers in reading and 14.8 percent of failing test numbers in math were due to the effects of lead. This is particularly notable because the Centers for Disease Control only recently halved the bolo levels required for medical intervention in children—from 10 μg/dL prior to 2012, to 5 μg/dL today.
"When you think about how many kids in the [Chicago public] school system are just barely passing with regards to meeting the standards, absolutely [lead poisoning] makes a big difference," the study’s lead author told the Chicago Reader in 2012, before the results were published. "It impacts a huge number of kids."
The real tragedy in lead poisoning is this: It has disproportionately affected the underserved. This is, of course, partly why the wide-ranging effects of childhood exposure lead poisoning—which has been linked not only to lower test scores, but brain damage and increased violence and aggression in adulthood—has seen less public attention than it deserves.
In the 1970s, as the lead industry continued to fight against federal rules banning lead paint in homes even after public health officials in Baltimore, New York, and Chicago had clamped down on its use, it laid the blame for the substance’s effects at the feet of minority parents. As the historian David Rosner wrote for The Atlantic:
The lead industry even sought to place the blame for lead poisoning epidemic on parents and children, claiming that the problem was not with the lead paint but with the "uneducable Negro and Puerto Rican" parents who "failed" to stop children from placing their fingers and toys in their mouths. Children poisoned by lead, the industry claimed, had a disease that led them to suck on "unnatural objects" and thereby get poisoned.
Even after Congress stepped in to ban lead-based paint—commonly used in homes, on furniture, and yes, on toys—its legacy has echoed even into the 2000s, as the Chicago study shows. A May investigation by the Chicago Tribune also discovered that in some of the city’s predominantly African-American neighborhoods, “ravaged by extreme poverty, chronic violence and struggling schools,” children 5 years old and under are harmed by lead at rates up to six times the city average. The problem? Some of Chicago’s aging housing stock still contains lead paint, or the soils around it have absorbed the substance—where it’s stayed for years. Yet since 2010, the Tribune reports, the city has cut its funding for anti-lead programs in half.
"Lead clearly is part of the cycle of deprivation," the sociologist Robert Sampson, who often writes about segregation in Chicago’s poorest neighborhoods, told the Tribune. "When a neighborhood faces multiple disadvantages, the outcomes for children are worse."