title: Environmental lead exposure and attention deficit/hyperactivity disorder symptom domains in a community sample of South Korean school-age children.
abstract: BACKGROUND
  Low-level environmental exposure to lead has been associated with both reduced intelligence and symptoms of attention deficit/hyperactivity disorder (ADHD). However, few studies have estimated the association of lead and intelligence independent of ADHD, and it is not clear from previous studies whether lead is associated with both inattention and impulsivity ADHD symptoms.
  
  
  OBJECTIVE
  We estimated mutually adjusted associations of environmental lead exposure with both intelligence and ADHD symptoms, and associations between lead and specific ADHD-related domains.
  
  
  METHODS
  Blood lead concentrations were measured in a general population of 1,001 children 8-11 years of age. We used multivariable linear regression models to estimate associations of blood lead concentrations with IQ scores, teacher and parent ratings of ADHD symptoms, and measures of inattention and impulsivity. Models were adjusted for demographic variables and other environmental exposures (blood levels of mercury and manganese, urinary concentrations of cotinine, phthalate metabolites, and bisphenol A).
  
  
  RESULTS
  Associations of blood lead with lower IQ and higher impulsivity were robust to adjustment for a variety of covariates. When adjusted for demographic characteristics, other environmental exposures, and ADHD symptoms or IQ, a 10-fold increase in blood lead concentration was associated with lower Full-Scale IQ (-7.23; 95% CI: -13.39, -1.07) and higher parent- and teacher-rated hyperactivity/impulsivity scores (ADHD Rating Scale, 1.99; 95% CI: 0.17, 3.81 and 3.66; 95% CI: 1.18, 6.13, respectively) and commission errors (Continuous Performance Test, 12.27; 95% CI: -0.08, 24.62). Blood lead was not significantly associated with inattention in adjusted models.
  
  
  CONCLUSIONS
  Low-level lead exposure was adversely associated with intelligence in school-age children independent of ADHD, and environmental lead exposure was selectively associated with impulsivity among the clinical features of ADHD.
authors.affiliation: Division of Child and Adolescent Psychiatry, Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Soon-Beom
authors.initials: SB
authors.lastname: Hong
authors.forename: Mee-Hyang
authors.initials: MH
authors.lastname: Im
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Park
authors.forename: Min-Sup
authors.initials: MS
authors.lastname: Shin
authors.forename: Boong-Nyun
authors.initials: BN
authors.lastname: Kim
authors.forename: Hee-Jeong
authors.initials: HJ
authors.lastname: Yoo
authors.forename: In-Hee
authors.initials: IH
authors.lastname: Cho
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Bhang
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
authors.forename: Soo-Churl
authors.initials: SC
authors.lastname: Cho
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000097:blood / Q000453:epidemiology*; D002648:Child; D003072:Cognition Disorders / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D006801:Humans; D007360:Intelligence / Q000187:drug effects; D007854:Lead / Q000097:blood*; D008297:Male; D056910:Republic of Korea / Q000453:epidemiology
chemical_list: D004785:Environmental Pollutants; D007854:Lead