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Childhood lead exposure is linked to low test scores for Black students, study finds

Researchers found that lead exposure is associated with cognitive deficits.

A new study led by Duke University found that elevated levels of lead can lead to lower test scores among Black students.

The findings, published Monday in the Proceedings of the National Academy of Sciences (PNAS), are based on surveys of more than 25,000 fourth graders in North Carolina. The data shows that Black students are disproportionately exposed to lead in racially segregated neighborhoods and that these stressors are linked to poor test scores in reading among Black youth relative to their white peers. 

“This is not surprising because lead is a known neurotoxicant,” Mercedes Bravo, the study’s lead author and an assistant research professor of global health at Duke University, told NBC News in an email. “Residing in a racially segregated neighborhood was also associated with lower 4th grade reading test scores among NHB (non-Hispanic Black) children. And, critically, at high levels of segregation, the combined association of these two exposures on test scores was larger than expected.” 

The study builds on prior research that also linked long-term lead exposure to a decline in cognitive abilities. According to the new report, the effects of the toxin can persist until adulthood, affecting intelligence, academic performance and economic stability. The research also indicates that communities experiencing poverty, lack of resources and racial segregation face a heightened risk of lead exposure. 

“This study suggests that the long history of structural racism — which among many other things has produced racially segregated neighborhoods — and environmental injustice (here in the form of lead exposure) can combine to systematically disadvantage specific students and groups of students in the US,” Bravo said. 

She said identifying these problems during childhood is key. 

“Maybe you can do something to help them so that they aren’t actually at risk of dropping out of high school or of not going to college or dropping out of college,” she said. “For 9-year-old kids, this is kind of an early warning … that these kids are at risk.” 

In North Carolina, students are often exposed to lead paint in older homes or through lead pipes and highly polluted areas. In 1978, the Consumer Product Safety Commission prohibited the use of lead-based paint, but homes built before this time may still put children at risk.

Bravo said more research is needed to understand the health impact of racial segregation and redlining, the practice of discriminatory housing and lending. 

“We need to consider things like environmental injustice and structural racism side by side,” she said. “They’re not actually separate because people experience all of these together.” 

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