Intellectual Impairment in School-Age Children Exposed to Manganese from Drinking Water

Abstract

BackgroundManganese 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.ObjectivesOur 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.MethodsThis 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.ResultsThe 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.ConclusionsThe findings of this cross-sectional study suggest that exposure to manganese at levels common in groundwater is associated with intellectual impairment in children.

Prenatal exposure to manganese in South African coastal communities

“…For example, studies in Bangladesh suggest that ingesting high doses of Mn in drinking water is associated with neurotoxic effects in children, interfering with their intellectual function, as well as causing infant mortality 24,25 . Similar studies have shown that drinking water containing much lower concentrations of Mn than those found in Bangladesh also caused intellectual impairment in school children 26 . The environmental exposure to Mn from industrial and mining sources, and negative cognitive performance of children were also reported 27,28 .…”

Contribution of metals to brain MR signal intensity: review articles

“…Intravenous administration or inhalation of manganese causes manganese deposition in the brain, but the oral intake of manganese rarely results in manganese deposition. Intellectual impairment in children after excess oral intake of manganese has been reported, albeit without histological proof [30]. Most orally ingested manganese does not remain in the human body, due to several mechanisms.…”

Are Environmental Contaminants Responsible for ‘Globesity’?

“…Mercury poisoning is manifested by irritability, poor concentration, memory deficiencies, anxiety, and depression [58][59]. Moreover, lead and manganese have also induced cognitive and behavioral deficits in different population groups with higher exposure levels [60][61][62][63]. These metals can differ in their neurological effects, but they both disrupt presynaptic neurotransmission [64].…”