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

Abstract

BACKGROUND:Neurotoxic 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. METHODS:

Identification of a gain-of-function mutation in a Golgi P-type ATPase that enhances Mn 2+ efflux and protects against toxicity

“…The cytotoxic effects of Mn 2+ result in the development of manganism, a Parkinson-like neurodegeneration syndrome, in adults and cognitive and behavioral defects in children (12)(13)(14). Thus, identifying mechanisms that reduce cytosolic Mn 2+ levels during elevated exposure is of high clinical significance.…”

Review of current evidence on the impact of pesticides, polychlorinated biphenyls and selected metals on attention deficit / hyperactivity disorder in children

“…A case-control study by Farias et al [63] found that chil dren with ADHD of both the inattentive and ADHDcombined types had higher serum manganese levels com pared with the controls, however the study did not control for potential confounders. Also, the study performed in Quebec reported a significant association between higher manganese levels in hair and drinking water and hyperactive behaviors in school children after controlling for sex, age and income [59].…”

“…Manganese (Mn) is a naturally occurring element that constitutes approximately 0.1% of the Earth's crust, and low levels of Mn in water, food, and air are ubiquitous [59]. Several authors have hypothesized that excessive amount of Mn could have detrimental effects on children's behavior patterns [59].…”

“…Several authors have hypothesized that excessive amount of Mn could have detrimental effects on children's behavior patterns [59]. High exposure to airborne Mn has been associated with neurotoxic effects, with the worst cases displaying the extrapyramidal syndrome (manganism), characterized by gait dysfunction with a propensity to fall backward, postu ral instability, bradykinesia, rigidity, micrographia, masked facies, speech disturbances, and muscle trem ors [60].…”

“…Lower levels of exposure may produce neurobe havioral deficits involving motor and cognitive functions, as well as psychological perturbations [61,62]. So far, only two studies have been carried out to exam ine the association between exposure to Mn and ADHD or ADHD-like symptoms and both suggested the presence of such relationship [63,59] (Table 5). A case-control study by Farias et al [63] found that chil dren with ADHD of both the inattentive and ADHDcombined types had higher serum manganese levels com pared with the controls, however the study did not control for potential confounders.…”