How Lead Exposure Holds Latino Children Back in School

In the 2012-2013 school year, Latino third graders in Rhode Island scored an average of 40 points (out of 80) on the NECAP reading test, compared to 48 for non-Latino white students.^(b) While the gap has been narrowing – from 11 points in the 2005 school year to 8 points in 2012 – it remains large. Math test scores show a similar pattern. 

Education experts in Rhode Island and across the country have been working to understand the factors that affect the Latino achievement gap and identify possible interventions to reduce it. Research indicates that, nationally, the higher share of English language learners among the Latino student population (35% versus 9% of non-Latino white fourth graders) and the greater share of Latino children living in poverty (as measured by their eligibility for free and reduced-cost school lunches) accounts for nearly half of the achievement gap.² The same forces are likely at play in Rhode Island. For example, when only students eligible for free or reduced-price lunches are compared, the gap in NECAP test scores between white and Latino children in Rhode Island falls from 8 to 5 points.  

Latino children in Rhode Island have higher blood lead levels than non-Latino white children, although, as with test scores, the gap has narrowed in recent years. The disparity in lead levels was 1.3 mg/dL in the 2005-2006 school year. It had fallen by nearly half, to 0.7 mg/dL, by the 2012-2013 school year. 

During the period when the disparity in lead levels between Latino and non-Latino white children in Rhode Island was narrowing, the educational achievement gap between the two groups was also shrinking. Our research analyzes whether there is a relationship between these two phenomena.

Text Box 1 Data Used in This Research

The Impact of Lead on Academic Performance

Prior research in Rhode Island found an inverse relationship between the blood lead levels of Providence children in preschool and their school readiness test scores in kindergarten, which are a predictor of later school performance.⁵ Among children with low lead levels (below 5 mg/dL), 68% scored above the school-readiness benchmark. Meanwhile, only 62% of children with moderate lead levels (between 5 and 9 mg/dL) and 49% of those with high lead levels (10 mg/dL or more) exceeded the benchmark. Our analysis of the relationship between early childhood lead levels and later educational outcomes, such as third-grade reading performance, suggests that this strong negative relationship persists. 

The Push to Reduce Lead Exposure

The negative health effects of lead ingestion have been known for hundreds of years, but until the mid-twentieth century, health officials considered only severe cases of lead poisoning to be harmful. This changed in the 1960s, when medical professionals recognized that less acute lead exposure also had harmful effects and began characterizing lead poisoning as epidemic.⁶

Since the U.S. Surgeon General named lead poisoning a national health problem in 1970, American children’s exposure to lead has declined dramatically, due largely to major regulatory changes eliminating lead from gasoline and household paint.^(c) The use of lead in household paint was reduced significantly after World War II (though not in response to any regulatory change) and, in 1978, federal law mandated that all household paint be completely de-leaded. Gasoline was de-leaded more gradually over time, with large reductions in the late 1970s and additional reductions thereafter. By 1996, gasoline was completely lead-free.⁶

These changes have been credited with drastically reducing lead concentrations in the air, which have declined 99% since 1980. The share of preschool-age American children with elevated lead levels has also declined, especially among the historically high-risk groups of poor and minority (African American and Latino) children.⁷

Despite these dramatic reductions in the presence of lead in the environment, it remains a significant public health concern due to residual lead in soil and old paint. Disadvantaged children are more likely to be exposed to this lead for two main reasons. First, they are more likely to live in substandard housing built before 1978 or even before World War II, when the lead concentration in paint was considerably higher. A second major source of lead among disadvantaged children is their proximity to high-traffic roadways where residual lead from gasoline emissions is found in higher concentrations in the soil.⁹ 

The increased exposure of disadvantaged children to these two sources of environmental lead is driven in part by historical patterns of residential segregation by income, race, and ethnicity that continue to exist in Rhode Island and across the country. Both African American and Latino children are significantly more likely to live in the state’s four major cities – Providence, Central Falls, Pawtucket and Woonsocket – which also boast the greatest share of old housing stock and the highest density of roads and traffic.^(d)

Understanding the Connection Between Lead and Test Scores

Understanding the relationship between lead levels and test scores is challenging. Children with elevated lead levels tend to be disadvantaged in other ways as well – they are more likely to come from single-parent, lower-income families in high-poverty neighborhoods. All these factors are independently associated with lower test scores, making it difficult to isolate the effects of elevated lead levels. Another issue is collecting accurate data on children’s exposure to lead. Fortunately, Rhode Island is very advanced in its lead testing policies, screening the overwhelming majority of children in the state multiple times.^(e)

Rhode Island has a unique set of policies that help us overcome these research challenges. Beginning in the late 1990s, the state required landlords to conduct lead testing and remediation on their rental properties and obtain certificates verifying homes as lead-safe in order to rent them. Our analysis finds that the certificate programs contributed to the reduction in lead levels among Rhode Island’s children during the early 2000s.^(f) The programs were particularly effective at reducing lead exposure among Latino and African American children, who are concentrated in the four core cities specifically targeted by the programs.

During the period covered in our dataset, only a portion of the rental homes in Rhode Island received certificates. Because the certificate programs affected some homes but not others, we are able to compare the test scores of children who come from similar socioeconomic and family backgrounds, but differ only in their exposure to lead, depending on whether or not their home was affected by the programs. By controlling for other factors that can play a role in educational achievement, like race, ethnicity, and income, we can isolate the impact of lead exposure on test scores.

Text Box 2. Rhode Island’s Programs to Promote Lead-Safe Housing

The Effects of Lead on Children in Rhode Island

Our analysis found that for each 1-mg/dL decrease in blood lead levels in children, test scores increase by roughly ½ to ¾ of a point. Based on this finding, we calculate that the 1.9-mg/dL drop in lead levels among Latino children from 2005 to 2012 resulted in a 1.5-point increase in test scores. This means that the decrease in lead levels accounts for roughly 30% of the 5-point increase in test scores witnessed among Latino children in the state over this period.

Looking at the gap between Latino and white children, the disparity in lead levels between these two groups shrank by about 1 mg/dL (from 1.25 to 0.25 mg/dL) from 2005 to 2012, while the gap in test scores narrowed by about 2 points (from 11 to 9). Based on our estimates, the shrinking disparity in lead levels explains 25% of the decline in the educational achievement gap witnessed over this period.

Looking Beyond Lead

In addition to continuing current efforts to ensure all Rhode Island homes are lead-safe, including fully implementing the state’s lead certificate programs, public health leaders and policymakers might consider other ways to make children’s home lives healthier in order to improve both child health and educational outcomes. While childhood lead exposure is now approaching very low levels thanks to effective state and national policies, other known toxic substances in the environment are not being measured or monitored on a regular basis.^(g) Hard metals such as mercury and cadmium, as well as various pesticides, are known to negatively affect children’s cognitive and motor development, but we do not know to what extent these toxins are affecting children in Rhode Island.

The reduction of lead in this country has largely been a success story, and likely contributed to narrowing the educational achievement gap between minority and white students. Future efforts to reduce disparities in child health and educational outcomes could benefit from considering the full range of environmental factors that may affect a child’s development. There may be other toxins holding back children’s educational success in ways we are not even aware of.