Browsing by Author "Zephyr, Dominique"

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    Racial residential segregation shapes the relationship between early childhood lead exposure and fourth-grade standardized test scores
    (National Academy of Sciences, 2022) Bravo, Mercedes A.; Zephyr, Dominique; Kowal, Daniel; Ensor, Katherine; Miranda, Marie Lynn
    Racial/ethnic disparities in academic performance may result from a confluence of adverse exposures that arise from structural racism and accrue to specific subpopulations. This study investigates childhood lead exposure, racial residential segregation, and early educational outcomes. Geocoded North Carolina birth data is linked to blood lead surveillance data and fourth-grade standardized test scores (n = 25,699). We constructed a census tract-level measure of racial isolation (RI) of the non-Hispanic Black (NHB) population. We fit generalized additive models of reading and mathematics test scores regressed on individual-level blood lead level (BLL) and neighborhood RI of NHB (RINHB). Models included an interaction term between BLL and RINHB. BLL and RINHB were associated with lower reading scores; among NHB children, an interaction was observed between BLL and RINHB. Reading scores for NHB children with BLLs of 1 to 3 µg/dL were similar across the range of RINHB values. For NHB children with BLLs of 4 µg/dL, reading scores were similar to those of NHB children with BLLs of 1 to 3 µg/dL at lower RINHB values (less racial isolation/segregation). At higher RINHB levels (greater racial isolation/segregation), children with BLLs of 4 µg/dL had lower reading scores than children with BLLs of 1 to 3 µg/dL. This pattern becomes more marked at higher BLLs. Higher BLL was associated with lower mathematics test scores among NHB and non-Hispanic White (NHW) children, but there was no evidence of an interaction. In conclusion, NHB children with high BLLs residing in high RINHB neighborhoods had worse reading scores.
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    Spatial Variability in Relationships between Early Childhood Lead Exposure and Standardized Test Scores in Fourth Grade North Carolina Public School Students (2013–2016)
    (National Institute of Environmental Health Sciences, National Institutes of Health, 2024) Bravo, Mercedes A.; Kowal, Daniel R.; Zephyr, Dominique; Feldman, Joseph; Ensor, Katherine; Miranda, Marie Lynn
    Background:Exposure to lead during childhood is detrimental to children’s health. The extent to which the association between lead exposure and elementary school academic outcomes varies across geography is not known.Objective:Estimate associations between blood lead levels (BLLs) and fourth grade standardized test scores in reading and mathematics in North Carolina using models that allow associations between BLL and test scores to vary spatially across communities.Methods:We link geocoded, individual-level, standardized test score data for North Carolina public school students in fourth grade (2013–2016) with detailed birth records and blood lead testing data retrieved from the North Carolina childhood blood lead state registry on samples typically collected at 1–6 y of age. BLLs were categorized as: 1μ⁢g/dL (reference), 2μ⁢g/dL, 3–4μ⁢g/dL and ≥5μ⁢g/dL. We then fit spatially varying coefficient models that incorporate information sharing (smoothness), across neighboring communities via a Gaussian Markov random field to provide a global estimate of the association between BLL and test scores, as well as census tract–specific estimates (i.e., spatial coefficients). Models adjusted for maternal- and child-level covariates and were fit separately for reading and math.Results:The average BLL across the 91,706 individuals in the analysis dataset was 2.84μ⁢g/dL. Individuals were distributed across 2,002 (out of 2,195) census tracts in North Carolina. In models adjusting for child sex, birth weight percentile for gestational age, and Medicaid participation as well as maternal race/ethnicity, educational attainment, marital status, and tobacco use, BLLs of 2μ⁢g/dL, 3–4μ⁢g/dL and ≥5μ⁢g/dL were associated with overall lower reading test scores of −0.28 [95% confidence interval (CI): −0.43, −0.12], −0.53 (−0.69, −0.38), and −0.79 (−0.99, −0.604), respectively. For BLLs of 1μ⁢g/dL, 2μ⁢g/dL, 3–4μ⁢g/dL and ≥5μ⁢g/dL, spatial coefficients—that is, tract-specific adjustments in reading test score relative to the “global” coefficient—ranged from −9.70 to 2.52, −3.19 to 3.90, −11.14 to 7.85, and −4.73 to 4.33, respectively. Results for mathematics were similar to those for reading.Conclusion:The association between lead exposure and reading and mathematics test scores exhibits considerable heterogeneity across North Carolina communities. These results emphasize the need for prevention and mitigation efforts with respect to lead exposures everywhere, with special attention to locations where the cognitive impact is elevated. https://doi.org/10.1289/EHP13898