| The Relationship between Early Childhood Blood Lead Levels and Performance on End-of-Grade Tests Marie Lynn Miranda,1 Dohyeong Kim,1 M. Alicia Overstreet Galeano,1 Christopher J. Paul,1 Andrew P. Hull,1 and S. Philip Morgan2 1Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina, USA; 2Sociology Department, Duke University, Durham, North Carolina, USA Abstract
Background: Childhood lead poisoning remains a critical environmental health concern. Low-level lead exposure has been linked to decreased performance on standardized IQ tests for school-aged children. Objective: In this study we sought to determine whether blood lead levels in early childhood are related to educational achievement in early elementary school as measured by performance on end-of-grade (EOG) testing. Methods: Educational testing data for 4th-grade students from the 2000–2004 North Carolina Education Research Data Center were linked to blood lead surveillance data for seven counties in North Carolina and then analyzed using exploratory and multivariate statistical methods. Results: The discernible impact of blood lead levels on EOG testing is demonstrated for early childhood blood lead levels as low as 2 µg/dL. A blood lead level of 5 µg/dL is associated with a decline in EOG reading (and mathematics) scores that is roughly equal to 15% (14%) of the interquartile range, and this impact is very significant in comparison with the effects of covariates typically considered profoundly influential on educational outcomes. Early childhood lead exposures appear to have more impact on performance on the reading than on the mathematics portions of the tests. Conclusions: Our emphasis on population-level analyses of children who are roughly the same age linked to previous (rather than contemporaneous) blood lead levels using achievement (rather than aptitude) outcome complements the important work in this area by previous researchers. Our results suggest that the relationship between blood lead levels and cognitive outcomes are robust across outcome measures and at low levels of lead exposure. Key words: disparities, lead levels, school performance. Environ Health Perspect 115:1242–1247 (2007) . doi:10.1289/ehp.9994 available via http://dx.doi.org/ [Online 27 April 2007]
Address correspondence to M.L. Miranda, Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Levine Science Research Center Room A134, Durham, NC 27708-0328 USA. Telephone: (919) 613-8023. Fax: (919) 684-3227. E-mail: mmiranda@duke.edu We acknowledge key support provided by E. Norman and T. Ward of the North Carolina Childhood Lead Poisoning Prevention Program, E. Glennie of the North Carolina Education Research Data Center, G. Thompson of the Sociology Department at Duke University, and S. Edwards, E. Tassone, and J. Tootoo of the Children’s Environmental Health Initiative at Duke University. This research was made possible by funding from the U.S. Centers for Disease Control and Prevention. The authors declare they have no competing financial interests. Received 14 December 2006 ; accepted 27 April 2007.
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