The Impact of Low-Level Lead Toxicity on School Performance among Hispanic Subgroups in the Chicago Public Schools.

Michael Blackowicz,Anne Evens,Daniel Hryhorczuk,Dan Lewis,Kristin Rankin,Bruce Lanphear,Danish Haider

doi:10.3390/ijerph13080774

Abstract

Background: Environmental lead exposure detrimentally affects children’s educational performance, even at very low blood lead levels (BLLs). Among children in Chicago Public Schools (CPS), the severity of the effects of BLL on reading and math vary by racial subgroup (White vs. Hispanic vs. non-Hispanic Black). We investigated the impact of BLL on standardized test performance by Hispanic subgroup (Mexican, Puerto Rican, and Other Hispanic). Methods: We examined 12,319 Hispanic children born in Chicago between 1994 and 1998 who were tested for BLL between birth and 2006 and enrolled in the 3rd grade at a CPS school between 2003 and 2006. We linked the Chicago birth registry, the Chicago Blood Lead Registry, and 3rd grade Illinois Standard Achievement Test (ISAT) scores to examine associations between BLL and school performance. Primary analyses were restricted to children with BLL below 10 µg/dL (0.483 µmol/L). Results: BLLs below 10 µg/dL (0.483 µmol/L) were inversely associated with reading and math scores in all Hispanic subgroups. Adjusted Relative Risks (RRadj) and 95% confidence intervals (CI) for reading and math failure were 1.34 (95% CI = 1.25, 1.63) and 1.53 (95% CI = 1.32, 1.78), respectively, per each additional 5 µg/dL of lead exposure for Hispanic children; RRadj did not differ across subgroups. We estimate that 7.0% (95% CI = 1.8, 11.9) of reading and 13.6% (95% CI = 7.7, 19.2) of math failure among Hispanic children can be attributed to exposure to BLLs of 5–9 µg/dL (0.242 to 0.435 µmol/L) vs. 0–4 µg/dL (0–0.193 µmol/L). The RRadj of math failure for each 5 µg/dL (0.242 µmol/L) increase in BLL was notably (p = 0.074) stronger among black Puerto Rican children (RRadj = 5.14; 95% CI = 1.65–15.94) compared to white Puerto Rican children (RRadj = 1.50; 95% CI = 1.12–2.02). Conclusions: Early childhood lead exposure is associated with poorer achievement on standardized reading and math tests in the 3rd grade for Mexican, Puerto Rican, and Other Hispanic children enrolled in Chicago Public Schools. While we did not see interactions between BLL and ISAT performance by Hispanic subgroup, the stronger association between BLL and math failure for Black Puerto Rican children is intriguing and warrants further study.

Highlights

Hispanic children in the United States have historically been at greater risk of elevated blood lead levels (BLLs) than non-Hispanic whites, though at lower risk than non-Hispanic blacks [1,2,3]
We previously examined the effect of BLLs on the performance of 58,560 children enrolled in the 3rd grade at Chicago Public Schools (CPS) between 2003 and 2006 on the Illinois Standard
The interaction term (BLL*Hispanic subclass) was not included in either model, since the addition of the interaction term into the model did not significantly improve model fit (p > 0.05). a For All Hispanic Children, the model includes blood lead level, gender, mother’s education, low-income, preterm birth, small for gestational age (SGA), child’s age at time of BLL, Illinois Standard Achievement Test (ISAT) vs. Iowa, and Hispanic subgroup

Summary

Introduction

Hispanic children in the United States have historically been at greater risk of elevated blood lead levels (BLLs) than non-Hispanic whites, though at lower risk than non-Hispanic blacks [1,2,3]. Examination Survey (NHANES), the geometric mean BLLs of Mexican and non-Hispanic white children ages 1–5 years converged at 1.3 μg/dL (0.063 μmol/L), while non-Hispanic black children were significantly higher at 1.8 μg/dL (0.087 μmol/L) [3] Despite these improvements, even very low levels of lead can cause intellectual and behavioral deficits in children, including a worsening in school performance [7,8,9,10,11,12,13]. We previously examined the effect of BLLs on the performance of 58,560 children enrolled in the 3rd grade at Chicago Public Schools (CPS) between 2003 and 2006 on the Illinois Standard. Primary analyses were restricted to children with BLL below 10 μg/dL (0.483 μmol/L)

Methods

Results

Discussion

Conclusion