title: Intellectual impairment in school-age children exposed to manganese from drinking water.
abstract: BACKGROUND
  Manganese is an essential nutrient, but in excess it can be a potent neurotoxicant. Despite the common occurrence of manganese in groundwater, the risks associated with this source of exposure are largely unknown.
  
  
  OBJECTIVE
  Our first aim was to assess the relations between exposure to manganese from drinking water and children's intelligence quotient (IQ). Second, we examined the relations between manganese exposures from water consumption and from the diet with children's hair manganese concentration.
  
  
  METHODS
  This cross-sectional study included 362 children 6-13 years of age living in communities supplied by groundwater. Manganese concentration was measured in home tap water (MnW) and children's hair (MnH). We estimated manganese intake from water ingestion and the diet using a food frequency questionnaire and assessed IQ with the Wechsler Abbreviated Scale of Intelligence.
  
  
  RESULTS
  The median MnW in children's home tap water was 34 µg/L (range, 1-2,700 µg/L). MnH increased with manganese intake from water consumption, but not with dietary manganese intake. Higher MnW and MnH were significantly associated with lower IQ scores. A 10-fold increase in MnW was associated with a decrease of 2.4 IQ points (95% confidence interval: -3.9 to -0.9; p < 0.01), adjusting for maternal intelligence, family income, and other potential confounders. There was a 6.2-point difference in IQ between children in the lowest and highest MnW quintiles. MnW was more strongly associated with Performance IQ than Verbal IQ.
  
  
  CONCLUSIONS
  The findings of this cross-sectional study suggest that exposure to manganese at levels common in groundwater is associated with intellectual impairment in children.
authors.affiliation: Centre for Interdisciplinary Studies in Biology, Health, Society and Environment, Université du Québec à Montréal, Montreal, Québec, Canada. maryse.bouchard@umontreal.ca
authors.forename: Maryse F
authors.initials: MF
authors.lastname: Bouchard
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.forename: Benoit
authors.initials: B
authors.lastname: Barbeau
authors.forename: Melissa
authors.initials: M
authors.lastname: Legrand
authors.forename: Marie-Ève
authors.initials: MÈ
authors.lastname: Brodeur
authors.forename: Thérèse
authors.initials: T
authors.lastname: Bouffard
authors.forename: Elyse
authors.initials: E
authors.lastname: Limoges
authors.forename: David C
authors.initials: DC
authors.lastname: Bellinger
authors.forename: Donna
authors.initials: D
authors.lastname: Mergler
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D004032:Diet / Q000706:statistics & numerical data; D004781:Environmental Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D005260:Female; D006197:Hair / Q000378:metabolism; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D008297:Male; D008345:Manganese / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D013334:Students / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D014881:Water Supply / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D008345:Manganese