Intellectual impairment in school-age children exposed to manganese from drinking water.
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.
Bouchard
Maryse F
MF
Centre for Interdisciplinary Studies in Biology, Health, Society and Environment, Université du Québec à Montréal, Montreal, Québec, Canada. maryse.bouchard@umontreal.ca
Sauvé
Sébastien
S
Barbeau
Benoit
B
Legrand
Melissa
M
Brodeur
Marie-Ève
MÈ
Bouffard
Thérèse
T
Limoges
Elyse
E
Bellinger
David C
DC
Mergler
Donna
D
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
D014874:Water Pollutants, Chemical; D008345:Manganese