Association Between Lead Poisoning and Academic Performance of Third-Grade Children in Milwaukee

Lead-poisoned children with blood lead levels (BLL) of > 5 μg/dL among those tested in Milwaukee, Wisconsin, increased from 8.6% to 10.4% between 2014 and 2016. We examined the association between lead poisoning and academic performance of third-grade children in Milwaukee.

Data from Milwaukee Public Schools, birth certificates, and the City of Milwaukee Health Department on third-grade students from 2010 through 2015 were analyzed. The outcome was academic performance measured as standardized math and reading scores. The key independent variable was elevated BLL ≥ 5 μg/dL. Standardized reading and math test scores were modeled using mixed effects linear regression, including a school-specific random intercept and repeated effects for school trimesters using an autoregressive correlation structure of first order. The association of reading scores with lead exposure was explored after adjusting for school year, trimester, child, and maternal characteristics.

Of 18,213 children with available lead testing data, the median maximum BLL was 4.0 μg/dL (interquartile range 34.0-6.1). Nearly 60% (58.3%) had maximum BLLs <  5 μg/dL, 27.7% had maximum BLLs of 5-9 μg/dL, 11.0% had maximum BLLs of 10-19 μg/dL, and 3.0% had maximum BLL ≥20 μg/dL. After controlling for potential confounders, children with BLLs ≥20 μg/dL, 10-19 μg/dL, and 5-9 μg/dL, respectively, had lower standardized math and reading scores when compared to children with BLLs <5 μg/dL at P  < 0.001.

Even at low levels, childhood lead poisoning persists in Milwaukee and is associated with lower third-grade academic performance in standardized reading and math tests. Parent education, childhood lead testing, and home lead abatement are critical strategies to improve children's educational performance.