Journal Article

Prenatal Methylmercury, Postnatal Lead Exposure, and Evidence of Attention Deficit/Hyperactivity Disorder among Inuit Children in Arctic Québec

Muckle, Gina, Plusquellec, Pierrich, Forget-Dubois, Nadine, Ayotte, Pierre, Dewailly, Éric, Jacobson, Sandra W., Boucher, Olivier, Jacobson, Joseph L.

2012

Overview

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. Objectives: 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.

• Publisher: National Institute of Environmental Health Sciences,US Department of Health and Human Services
• Subject: Adolescent / Age / Arctic Regions - epidemiology / Attention Deficit and Disruptive Behavior Disorders - chemically induced / Attention Deficit and Disruptive Behavior Disorders - epidemiology / Attention Deficit and Disruptive Behavior Disorders - ethnology / Attention Deficit Disorder with Hyperactivity - chemically induced / Attention Deficit Disorder with Hyperactivity - ethnology / Attention Deficit Disorder with Hyperactivity - etiology / Attention deficit hyperactivity disorder / Biological and medical sciences / Blood / Chemical and industrial products toxicology. Toxic occupational diseases / Chemical hazards / Child / Child Behavior / Child behavior disorders / Child Behavior Disorders - chemically induced / Child Behavior Disorders - epidemiology / Child Behavior Disorders - ethnology / Children / Children's Health / Chromatography, Gas / Classrooms / Conduct Disorder - chemically induced / Conduct Disorder - epidemiology / Conduct Disorder - ethnology / Contaminants / Cord blood / Diseases / Disorders / Environment. Living conditions / Environmental Exposure / Environmental Monitoring / Environmental Pollutants - blood / Environmental Pollutants - toxicity / Exposure / Female / Fetal Blood - chemistry / Health aspects / Humans / Infant, Newborn / Inuit / Lead / Lead (metal) / Lead - blood / Lead - toxicity / Longitudinal Studies / Male / Mass Spectrometry / Medical sciences / Mercury / Metals and various inorganic compounds / Methylmercury / Methylmercury Compounds - blood / Methylmercury Compounds - toxicity / PCB / Polychlorinated biphenyls / Polychlorinated Biphenyls - blood / Polychlorinated Biphenyls - toxicity / Pregnancy / Prenatal Exposure Delayed Effects - chemically induced / Prenatal Exposure Delayed Effects - epidemiology / Prenatal Exposure Delayed Effects - ethnology / Prospective Studies / Public health. Hygiene / Public health. Hygiene-occupational medicine / Quebec - epidemiology / Risk factors / School age children / Spectrophotometry, Atomic / Teachers / Toxicology