Neuropsychological function in children with blood lead levels <10 microg/dL.
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.
Surkan
Pamela J
PJ
Department of Environmental Health, Harvard School of Public Health, Landmark Building, 4th Floor, 401 Park Drive, Boston, MA 02115, USA.
Zhang
Annie
A
Trachtenberg
Felicia
F
Daniel
David B
DB
McKinlay
Sonja
S
Bellinger
David C
DC
D001288:Attention / Q000187:drug effects; D001900:Boston; D002648:Child; D003071:Cognition / Q000187:drug effects*; D003430:Cross-Sectional Studies; D003723:Dental Amalgam / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004522:Educational Status; D005260:Female; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D007361:Intelligence Tests; D007807:Language Tests; D007854:Lead / Q000009:adverse effects* / Q000097:blood*; D008281:Maine; D008297:Male; D008568:Memory / Q000187:drug effects; D009483:Neuropsychological Tests; D012423:Rural Health; D014504:Urban Health; D014705:Verbal Behavior / Q000187:drug effects
D007854:Lead; D003723:Dental Amalgam