title: Low-level environmental lead exposure in childhood and adult intellectual function: a follow-up study.
abstract: BACKGROUND
  Early life lead exposure might be a risk factor for neurocognitive impairment in adulthood.
  
  
  OBJECTIVE
  We sought to assess the relationship between early life environmental lead exposure and intellectual function in adulthood. We also attempted to identify which time period blood-lead concentrations are most predictive of adult outcome.
  
  
  METHODS
  We recruited adults in the Boston area who had participated as newborns and young children in a prospective cohort study that examined the relationship between lead exposure and childhood intellectual function. IQ was measured using the Wechsler Abbreviated Scale of Intelligence (WASI). The association between lead concentrations and IQ scores was examined using linear regression.
  
  
  RESULTS
  Forty-three adults participated in neuropsychological testing. Childhood blood-lead concentration (mean of the blood-lead concentrations at ages 4 and 10 years) had the strongest relationship with Full-Scale IQ (β = -1.89 ± 0.70, p = 0.01). Full-scale IQ was also significantly related to blood-lead concentration at age 6 months (β = -1.66 ± 0.75, p = 0.03), 4 years (β = -0.90 ± 0.41, p = 0.03) and 10 years (β = -1.95 ± 0.80, p = 0.02). Adjusting for maternal IQ altered the significance of the regression coefficient.
  
  
  CONCLUSIONS
  Our study suggests that lead exposure in childhood predicts intellectual functioning in young adulthood. Our results also suggest that school-age lead exposure may represent a period of increased susceptibility. Given the small sample size, however, the potentially confounding effects of maternal IQ cannot be excluded and should be evaluated in a larger study.
authors: Department of Neurology, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA, USA. maitreyi.mazumdar@childrens.harvard.edu
authors: Maitreyi
authors: M
authors: Mazumdar
authors: David C
authors: DC
authors: Bellinger
authors: Matthew
authors: M
authors: Gregas
authors: Kathleen
authors: K
authors: Abanilla
authors: Janine
authors: J
authors: Bacic
authors: Herbert L
authors: HL
authors: Needleman
mesh_terms: D000328:Adult; D001900:Boston / Q000453:epidemiology; D003071:Cognition / Q000187:drug effects*; D015331:Cohort Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D007854:Lead / Q000097:blood / Q000633:toxicity*; D016014:Linear Models; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D014888:Wechsler Scales / Q000706:statistics & numerical data*
chemical_list: D007854:Lead