Lead exposure has long been linked to poor educational outcomes.
A new study suggests residential segregation makes the situation worse, possibly contributing to educational achievement gaps in cities like Milwaukee.
A researcher at Duke University looked at the test scores of more than 25,000 North Carolina fourth-graders and found lead-poisoned children with low academic test scores perform even worse if they live in a highly segregated area.
Lead is a neurotoxin that is especially harmful to developing brains, causing IQ deficits, calcium deficiencies, behavioral problems and poor impulse control, among other problems.
The study found an association between high levels of “racial isolation,” or segregation, and lower reading test scores for Black children.
“We found a significant interaction,” said Mercedes Bravo, an assistant research professor at Duke who studies how environmental conditions impact health.
“It meant if you’re exposed to both lead and high levels of segregation, the impact of test scores is worse compared to exposure to those individual factors alone,” she said.
Black children who had low lead levels and lived in highly segregated neighborhoods scored relatively similar to Black children who had low lead levels and lived in very integrated neighborhoods.
However, Black children who had high lead levels and lived in very segregated neighborhoods had significantly lower reading test scores when compared to Black children who had high lead levels and lived in very integrated neighborhoods.
This study’s findings were associative, not causal, meaning it did not draw a direct link between segregation, lead and lower educational test scores, Bravo said. But her research provides more evidence that inequities in lead poisoning rates are, at least partially, a function of classicism and racism.
“It means kids are worse because those multiple exposures augment the effect of another exposure,” she explained.
Her work has particular significance for Milwaukee.
Although all parts of the city contain aging housing stock associated with lead hazards, the highest concentrations of lead-poisoned children were clustered in the near north side, which is home to majority Black residents, according to aggregate data from 2017-2020 from Wisconsin Environmental Public Health Tracker.
Those racial disparities are a reflection of disinvestment, said Ruth Ann Norton, president and chief executive of the Green & Healthy Homes Initiative and one of the architects behind the Maryland Lead Law.
“You’re fighting a (housing) age issue there, but it’s not as prevalent as where you have disinvestment with no maintenance happening,” she said.
The Milwaukee region also is among the most segregated in the country.
A dissimilarity index is a figure used to identify racial segregation; anything above 60 is considered very high. Federal Reserve Economic Data for 2020 puts Milwaukee County’s dissimilarity index at 61. A 2020 study from Marc Levine, founding director of the University of Wisconsin-Milwaukee’s Center for Economic Development, noted the Milwaukee metro’s dissimilarity index has remained high — hovering at or aound 80 — since the 1970s.
A separate study released in the spring determined the schools of metro Milwaukee were the most segregated schools in the country.
Milwaukee Public Schools have persistent disparities in suspensions and expulsions between Black and white students, extreme Black-White segregation levels in the schools and lower standardized test scores among Black students have plagued the school system.
And this year, the state reported the widest math and reading proficiency gaps between Black and white students in the country.
White fourth graders in Wisconsin scored 37% higher than Black students in math and 22% higher in reading, on the U.S. Department of Education’s National Assessment of Educational Progress.
Bravo’s research suggests reductions in residential segregation could help reduce the impact of lead on poor test scores.
Need resources about lead?
Visit this general guide about lead
Read the Q&A of Dr. Veneshia McKinney-Whitson