Hair Manganese and Hyperactive Behaviors: Pilot Study of School-Age Children Exposed through Tap Water

Abstract

BackgroundNeurotoxic effects are known to occur with inhalation of manganese particulates, but very few data are available on exposure to Mn in water. We undertook a pilot study in a community in Québec (Canada) where naturally occurring high Mn levels were present in the public water system. Our objective was to test the hypothesis that greater exposure to Mn via drinking water would be reflected in higher Mn content in hair which, in turn, would be associated with increased level of hyperactive behaviors.MethodsForty-six children participated in the study, 24 boys and 22 girls, 6–15 years of age (median, 11 years). Their homes received water from one of two wells (W) with different Mn concentrations: W1: mean 610 μg/L; W2: mean 160 μg/L. The Revised Conners’ Rating Scale for parents (CPRS-R) and for teachers (CTRS-R) were administered, providing T-scores on the following subscales: Oppositional, Hyperactivity, Cognitive Problems/Inattention, and ADHD Index.ResultsChildren whose houses were supplied by W1 had higher hair Mn (MnH) than those supplied by W2 (mean 6.2 ± 4.7 μg/g vs. 3.3 ± 3.0 μg/g, p = 0.025). MnH was significantly associated with T-scores on the CTRS-R Oppositional (p = 0.020) and Hyperactivity (p = 0.002) subscales, after adjustment for age, sex, and income. All children with Oppositional and Hyperactivity T-scores ≥ 65 had MnH > 3.0 μg/g.ConclusionsThe findings of this pilot study are sufficiently compelling to warrant more extensive investigations into the risks of Mn exposure in drinking water.

Manganese Toxicity Upon Overexposure: a Decade in Review

“…High levels of Mn in drinking water in Canada have been found to lead to significantly higher levels of Mn in hair samples in school-age children. The increased hair Mn concentrations are significantly associated with increased hyperactive behaviors [49], impaired cognitive development [47], and a decrease in IQ points [50]. In Italy, school-age children living near a ferroalloy plant have been found to have significant impairment of motor coordination, hand dexterity, and odor identification after exposure to excess levels of Mn in soils [51].…”

Neurobehavioural effects of developmental toxicity

“…39 A study in Quebec, Canada, showed a strong correlation between manganese concentrations in hair and hyperactivity. 40 School-aged children living near manganese mining and processing facilities have shown associations between airborne manganese concentrations and diminished intellectual function 41 and with impaired motor skills and reduced olfactory function. 42 These results are supported by experimental findings in mice.…”

Subacute manganese exposure in rats is a neurochemical model of early manganese toxicity

“…Data from rodent studies generally offer conflicting reports on how Mn exposure affects neurochemistry and motor function. A general consensus regarding the effects of Mn on motor function is that hyperactivity is observed early in Mn toxicity in the young or after low cumulative doses, in both human and animal studies (Bouchard et al, 2007; Nachtman et al, 1986), and as the disease progresses and cumulative dose levels increase, patients and animals both tend to become hypoactive (Oszlanczi et al, 2010; Torrente et al, 2005). …”