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Multicenter Study
. 2007 Nov;28(6):1170-7.
doi: 10.1016/j.neuro.2007.07.007. Epub 2007 Jul 25.

Neuropsychological function in children with blood lead levels <10 microg/dL

Pamela J Surkan  1 , Annie Zhang, Felicia Trachtenberg, David B Daniel, Sonja McKinlay, David C Bellinger
Affiliations
Multicenter Study

Neuropsychological function in children with blood lead levels <10 microg/dL

Pamela J Surkan et al. Neurotoxicology. 2007 Nov.

Abstract

Clear adverse effects of blood lead levels >or=10 microg/dL have been documented in children. Given that the majority of US children have levels below 10 microg/dL, clarification of adverse effects below this cutoff value is needed. Our study evaluated the associations between blood lead levels <10 microg/dL and a broad spectrum of children's cognitive abilities. Data were analyzed from 534 children aged 6-10, enrolled in the New England Children's Amalgam Trial (NECAT) from the urban area of Boston, Massachusetts and rural Farmington, Maine. Adjusting for covariates (age, race, socioeconomic status, and primary caregiver IQ), children with 5-10 microg/dL had 5.0 (S.D. 2.3) points lower IQ scores compared to children with blood lead levels of 1-2 microg/dL (p=0.03). Verbal IQ was more negatively affected than performance IQ, with the most prominent decrement occurring in children's vocabulary. Wechsler Individual Achievement Test scores were strongly negatively associated with blood lead levels of 5-10 microg/dL. In adjusted analyses, children with levels of 5-10 microg/dL scored 7.8 (S.D. 2.4) and 6.9 (S.D. 2.2) points lower on reading and math composite scores, respectively, compared to children with levels of 1-2 microg/dL (p<0.01). Finally, levels of 5-10 microg/dL were associated with decreased attention and working memory. Other than associations of lead exposure with achievement, which even persisted after adjustment for child IQ, the most pronounced deficits were in the areas of spatial attention and executive function. Overall, our analyses support prior research that children's blood levels <10 microg/dL are related to compromised cognition and highlight that these may especially be related to academic achievement.

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Figures

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a-d: Relationships between selected neuropsychological tests and blood lead levels adjusted for age, adult IQ, SES, and race
Figures 1
Figures 1
a-d: Relationships between selected neuropsychological tests and blood lead levels adjusted for age, adult IQ, SES, and race
Figures 1
Figures 1
a-d: Relationships between selected neuropsychological tests and blood lead levels adjusted for age, adult IQ, SES, and race
Figures 1
Figures 1
a-d: Relationships between selected neuropsychological tests and blood lead levels adjusted for age, adult IQ, SES, and race
See this image and copyright information in PMC

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