In June 2019, Michigan’s Attorney General dismissed all criminal cases connected to the Flint water crisis. This crisis, which hit the headline news in early 2016, exposed as many as 8,000 children under age six to extreme lead levels in drinking water. Many Americans were left wondering: What effect would this have on the community, and how could it have been prevented?
Flint’s lead crisis is not an isolated incident, as children in communities across the nation are regularly exposed to lead contamination at varying levels. For example, lead-based paint found in older homes can cause lead poisoning if ingested through paint chips or inhaled in dust. Scientists have shown that such exposure under age five causes cognitive impairment and IQ loss. Given the well-established association between IQ and educational achievement, one wonders: How do changes in risks of lead exposure affect population-level education outcomes? And what can policy do to interrupt this link?
Are lead removal programs effective?
The Department of Housing and Urban Development (HUD) has led the charge in remediation of housing with lead-based paint risks. Between 1993 and 2016, HUD under the Lead Hazard Control Grant program spent around $2 billion to remove lead risks from targeted housing. In a recent study funded by the William T. Grant Foundation and Russell Sage Foundation, published in the Journal of Population Economics, we assessed the short-term effects of this program on childhood lead poisoning, and the long-term effects on educational achievement.
In particular, we use the different timing of these grants to study what happens when entire birth cohorts of children experience lowered risks of lead exposure in their homes. For each birth cohort, in each U.S. county, we tracked children’s blood-lead levels in early childhood, and their subsequent test scores in elementary and middle school grades (collected from the Stanford Education Data Archive).
Figure 1. The Geography of Lead Risk: Percentage of Housing Built Before 1940*
Note: Older housing is much more likely to contain lead (88% of houses built before 1940 contain lead-based paint), making the age of housing structures a useful proxy measure for lead-exposure risk.
Our findings are stark, illustrating the potential of these kinds of programs to address educational achievement gaps. Each one percentage-point drop in childhood lead poisoning led to a population average gain of one-tenth of a grade level in math, and one-third of a grade level in reading scores. This same drop in childhood lead poisoning also affected the distribution of educational outcomes across groups—narrowing the gap between White and Hispanic students in both reading and math, although not the gap between White and Black students. We hypothesize that larger benefits appear in the Hispanic population compared to the White population because Hispanic children are more likely to live in older housing containing lead.
As part of our analysis, we split U.S. counties into those that received a lead-hazard-control grant in 2003 (“treatment” counties) and those that never received such a grant (“control” counties) and compared cohort trends across the two groups. Figure 2 below traces the percentage of children under five who have elevated blood lead levels (defined as >10 micrograms per deciliter), by birth year. For children born before 2003, lead poisoning prevalence looked quite similar across the treatment and control counties. For children born after 2003, those in counties that were conducting lead abatement activities showed significant reductions in lead poisoning when compared to the control group. In other words: The intervention worked.
Figure 2. Lead Poisoning Trends After 2003 HUD Lead Abatement Efforts*
Note: “Treatment” counties received a lead-hazard-control grant in 2003, and “control” counties never received a grant. Each data point represents the percent of all tested children born in the specified year in those counties with elevated blood lead levels (>10 micrograms per deciliter).
How does this relate to educational achievement?
To determine whether these results connected to eventual education outcomes, we tracked the same birth cohorts of children in treatment and control counties through elementary and middle-school grades. Seen in Figure 3 below, the same birth cohorts of children who benefitted from lead remediation in housing and had lower lead poisoning rates also performed better on standardized reading tests. For example, children born in treatment counties in 2007 (four years after HUD activities began) had test scores 0.1 standard deviations higher than children in control counties in the same year. This translates into one-third of the average growth in reading performance that students gain from one grade level to the next. And test scores rose over two times more for Hispanic children than it did for white children.
Figure 3. Reading Score Trends After 2003 HUD Lead Abatement Efforts*
Note: “Treatment” counties received a lead-hazard-control grant in 2003, and “control” counties never received a grant. Each data point represents average reading test scores, as standard deviations from the national average, among all children born in the specified year in those counties.
HUD certainly did not design this lead-hazard-control program with the intent to improve children’s test scores or to shrink ethnic achievement gaps. Yet that is what happened. And this story is perhaps symbolic of the broader potential of cross-sector policymaking. For example, schools are largely tasked with closing achievement gaps, such as the reading proficiency rate of Hispanic students, which in fourth grade is roughly half that of White students. Educators, however, face a difficult challenge in closing gaps already apparent when students enter school. Our study shows that an early intervention in an entirely separate domain—such as housing or environmental health—can make a difference.
Another argument for accelerating lead-abatement activities is that the long-term benefits would easily dwarf the costs. Whereas other programs such as early-childhood education or health care require constant financial reinvestment, removing lead-based paint from housing (though an expensive undertaking) would benefit every child who ever lives in that house.
Future directions for cross-sector policy research
While our study highlights the promise of lead remediation activities for closing the educational achievement gap, many other questions remain. Philanthropic organizations (such as the William T. Grant Foundation) increasingly look towards cross-sector approaches to addressing inequality in youth outcomes by race, ethnicity, economic standing, language minority status or immigrant origins. In this vein, future research could explore: What new policy strategies might address health inequities—given the limited progress over the past quarter century—and, in doing so, also reduce disparities in educational achievement? How do different types of public institutions across domains such as education, health, social welfare, and justice interact to shape youth outcomes? And how do the sources and mechanisms underlying educational inequality differ across diverse communities? Matching population-level data on youth inequality, such as that from the publicly-available Stanford Education Data Archive, with other administrative or spatial data may hold the key to answering these questions.
*See: L.C. Sorensen, Fox, A.M., Jung H., Martin, E.G. (2019). Lead exposure and academic achievement: Evidence from childhood lead poisoning prevention efforts. Journal of Population Economics 32:179-218.
