MAC: Mines and Communities

The dangers of manganese

Published by MAC on 2010-10-04
Source: Toronto Sun (2010-09-20)

Children's IQs under threat

Yet another material enters the lexicon of toxic metals and minerals - including mercury, lead and asbestos - that threaten human health, in particular that of children.

Recent findings by the University of Quebec show that excess amounts of manganese, contained in drinking water, can severe reduce a child's Intelligence Quotient (IQ) - even though the levels are below current official limits.

The study apparently does not link  manganese poisoning to releases of the metal from mines into adjacent water bodies.

Yet, as pointed out on this website, there are several recent examples of such occurrences:

See: Gabonese NGO decries effects of mining - pointing to the toxicity created by Comilog's manganese mining in Gabon.

Also: Rio Tinto sued for pollution at "best practice" mine - which refers to the excessive levels of manganese in the Flambeau river watershed, following Rio Tinto's closure of its eponymous mine.

Water containing manganese could lower child's IQ: Study

QMI Agency in Toronto Sun

20 September 2010

Well water with high levels of manganese could lower a child's IQ, a new study from Quebec researchers says.

Looking at 362 Quebec children between the ages of six and 13 who were living in homes supplied by groundwater, researchers found the intelligence quotient (IQ) of children who drank water that contained higher amounts of manganese were six points below children whose water contained little or no manganese.

"This is a very marked effect; few environmental contaminants have shown such a strong correlation with intellectual ability," study co-author Donna Mergler said in a release.

Lead author Maryse Bouchard of the University of Montreal added, "We found significant deficits in the intelligence quotient (IQ) of children exposed to higher concentration of manganese in drinking water. Yet, manganese concentrations were well below current guidelines."

Manganese is commonly found in groundwater, including public and private wells. Health Canada says on its website that it is present in more than 100 "common salts and mineral complexes" found in rocks, soils and and on the floors of lakes and oceans.

"The greatest source of this exposure is from food. Intake from food is substantially higher than intake from drinking water, even in areas where the manganese content of water is high," Health Canada said online.

Health Canada also says manganese is an essential element, and among other things, is used by the body to metabolize carbohydrates. A manganese deficiency in animals has led to the central nervous system not functioning properly. Humans who haven't had enough manganese have developed dermatitis and high blood cholesterol.

While considered one of the least toxic elements, Health Canada said in extreme cases it can lead to "neurological manifestations" and some studies have reported a link to the male reproductive system problems and birth defects.

The study, which appeared Monday in the journal Environmental Health Perspectives, reported the amount of manganese in food "showed no relationship to the children's IQ."

The study said some municipalities where the study was conducted have already installed a filtration system that removes manganese from the water. The authors also said using home filtering pitchers that contain a mixture of resins and activated carbon can reduce the concentration of manganese by 60% to 100%.


Excess manganese stunts child intellect: study

AFP

20 September 2010

MONTREAL - Excess amounts of manganese -- a hard, brittle metal found in some drinking water around the world -- may have adverse effects on children's smarts, Canadian scientists said Monday.

A team of researchers at the University of Quebec in Montreal discovered that children exposed to high concentrations of manganese in drinking water performed worse on tests of intellectual functioning than children with lower exposures.

The results, published in the scientific journal Environmental Health Perspectives, prompted the researchers to urge a review of national and international guidelines for safe levels of manganese in drinking water, and home use of water filtering pitchers to reduce concentrations where it is high.

The study examined 362 children between the ages of six and 13, living in Quebec homes supplied by groundwater. For each child, the researchers measured the concentration of manganese in tap water from their home, as well as iron, copper, lead, zinc, arsenic, magnesium and calcium.

The amount of manganese from both tap water and food was estimated from a questionnaire. Finally, each child was assessed with a battery of tests assessing cognition, motor skills and behavior.

"We found significant deficits in the intelligence quotient (IQ) of children exposed to higher concentration of manganese in drinking water. Yet, manganese concentrations were well below current guidelines," said lead author Maryse Bouchard.

The average IQ of children whose tap water contained the highest manganese concentrations was six points below children whose water contained little or no manganese. Presence of manganese in food had no impact.

"This is a very marked effect," said study co-author Donna Mergler. "Few environmental contaminants have shown such a strong correlation with intellectual ability."

Manganese is naturally occurring in soil and air, and in certain conditions is present in groundwater in naturally high levels. It is also used in stainless steel, alkaline batteries, unleaded gasoline and coins.

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