title: Lead, mercury, and cadmium exposure and attention deficit hyperactivity disorder in children.
abstract: BACKGROUND
  There is limited research examining the relationship between lead (Pb) exposure and medically diagnosed attention deficit hyperactivity disorder (ADHD) in children. The role of mercury (Hg) and cadmium (Cd) exposures in ADHD development is even less clear.
  
  
  OBJECTIVE
  To examine the relationship between Pb, Hg, and Cd and ADHD in children living inside and outside a Lead Investigation Area (LIA) of a former lead refinery in Omaha, NE.
  
  
  METHODS
  We carried out a case-control study with 71 currently medically diagnosed ADHD cases and 58 controls from a psychiatric clinic and a pediatric clinic inside and outside of the LIA. The participants were matched on age group (5-8, 9-12 years), sex, race (African American or Caucasians and others), and location (inside or outside LIA). We measured whole blood Pb, total Hg, and Cd using inductively coupled plasma mass spectrometry.
  
  
  RESULTS
  Inside the LIA, the 27 cases had blood Pb geometric mean (GM) 1.89 µg/dL and the 41 controls had 1.51 µg/dL. Outside the LIA, the 44 cases had blood Pb GM 1.02 µg/dL while the 17 controls had 0.97 µg/dL. After adjustment for matching variables and maternal smoking, socioeconomic status, and environmental tobacco exposure, each natural log unit blood Pb had an odds ratio of 2.52 with 95% confidence interval of 1.07-5.92. Stratification by the LIA indicated similar point estimate but wider CIs. No associations were observed for Hg or Cd.
  
  
  CONCLUSIONS
  Postnatal Pb exposure may be associated with higher risk of clinical ADHD, but not the postnatal exposure to Hg or Cd.
authors.affiliation: Division of Epidemiology and Biostatistics, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
authors.forename: Stephani
authors.initials: S
authors.lastname: Kim
authors.forename: Monica
authors.initials: M
authors.lastname: Arora
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernandez
authors.forename: Julio
authors.initials: J
authors.lastname: Landero
authors.forename: Joseph
authors.initials: J
authors.lastname: Caruso
authors.forename: Aimin
authors.initials: A
authors.lastname: Chen
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000139:chemically induced*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D000075322:Heavy Metal Poisoning; D006801:Humans; D016015:Logistic Models; D008297:Male; D019216:Metals, Heavy / Q000009:adverse effects*; D011041:Poisoning / Q000150:complications*
chemical_list: D019216:Metals, Heavy
keywords: ADHD; APA; ASARCO; ATSDR; Agency for Toxic Substances and Disease Registry; American Psychiatric Association; American Smelting and Refining Company; Attention deficit hyperactivity disorder; BLL; CDC; CHEER; CI; Cadmium; Case-control study; Cd; Centers for Disease Control and Prevention; Children′s Health and Environment Research; DDW; DSM-IV; Diagnostic and Statistical Manual of Mental Disorders, 4th Edition; EPA; ETS; Environmental Protection Agency; Environmental Tobacco Smoke; GM; Heavy metals; Hg; ICP-MS; LIA; LOD; Lead; Lead Investigation Area; Mercury; NE; NHANES; NPL; National Health and Nutrition Examination Survey; National Priorities List; Nebraska; OR; Pb; SES; SRM; attention deficit hyperactivity disorder; blood lead level; cadmium; confidence interval; double deionized water; geometric mean; inductively coupled plasma mass spectrometry; lead; limit of detection; mercury; odds ratio; parts per billion; ppb; socioeconomic status; standard reference material
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