title: Prenatal methylmercury, postnatal lead exposure, and evidence of attention deficit/hyperactivity disorder among Inuit children in Arctic Québec.
abstract: BACKGROUND
  Prenatal exposure to methylmercury (MeHg) and polychlorinated biphenyls (PCBs) has been associated with impaired performance on attention tasks in previous studies, but the extent to which these cognitive deficits translate into behavioral problems in the classroom and attention deficit/hyperactivity disorder (ADHD) remains unknown. By contrast, lead (Pb) exposure in childhood has been associated with ADHD and disruptive behaviors in several studies.
  
  
  OBJECTIVE
  In this study we examined the relation of developmental exposure to MeHg, PCBs, and Pb to behavioral problems at school age in Inuit children exposed through their traditional diet.
  
  
  METHODS
  In a prospective longitudinal study conducted in the Canadian Arctic, exposure to contaminants was measured at birth and at school age. An assessment of child behavior (n = 279; mean age = 11.3 years) was obtained from the child's classroom teacher on the Teacher Report Form (TRF) from the Child Behavior Checklist, and the Disruptive Behavior Disorders Rating Scale (DBD).
  
  
  RESULTS
  Cord blood mercury concentrations were associated with higher TRF symptom scores for attention problems and DBD scores consistent with ADHD. Current blood Pb concentrations were associated with higher TRF symptom scores for externalizing problems and with symptoms of ADHD (hyperactive-impulsive type) based on the DBD.
  
  
  CONCLUSIONS
  To our knowledge, this study is the first to identify an association between prenatal MeHg and ADHD symptomatology in childhood and the first to replicate previously reported associations between low-level childhood Pb exposure and ADHD in a population exposed to Pb primarily from dietary sources.
authors.affiliation: Centre de Recherche du Centre hospitalier universitaire de Québec, Québec, Québec, Canada.
authors.forename: Olivier
authors.initials: O
authors.lastname: Boucher
authors.forename: Sandra W
authors.initials: SW
authors.lastname: Jacobson
authors.forename: Pierrich
authors.initials: P
authors.lastname: Plusquellec
authors.forename: Eric
authors.initials: E
authors.lastname: Dewailly
authors.forename: Pierre
authors.initials: P
authors.lastname: Ayotte
authors.forename: Nadine
authors.initials: N
authors.lastname: Forget-Dubois
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Jacobson
authors.forename: Gina
authors.initials: G
authors.lastname: Muckle
mesh_terms: D000293:Adolescent; D001110:Arctic Regions / Q000453:epidemiology; D001289:Attention Deficit Disorder with Hyperactivity / Q000139:chemically induced / Q000208:ethnology / Q000209:etiology; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000139:chemically induced* / Q000453:epidemiology / Q000208:ethnology; D002648:Child; D002652:Child Behavior; D002653:Child Behavior Disorders / Q000139:chemically induced* / Q000453:epidemiology / Q000208:ethnology; D002849:Chromatography, Gas; D019955:Conduct Disorder / Q000139:chemically induced / Q000453:epidemiology / Q000208:ethnology; D004781:Environmental Exposure; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000097:blood / Q000633:toxicity*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D004930:Inuit; D007854:Lead / Q000097:blood / Q000633:toxicity*; D008137:Longitudinal Studies; D008297:Male; D013058:Mass Spectrometry; D008767:Methylmercury Compounds / Q000097:blood / Q000633:toxicity*; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced / Q000453:epidemiology / Q000208:ethnology; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D013054:Spectrophotometry, Atomic
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D007854:Lead; D011078:Polychlorinated Biphenyls