Thursday, September 23, 2010

Children’s Cognitive Abilities Negatively Affected by Manganese in Drinking Water

Photo taken from Biliuti, 2010

An essential nutrient involved in human metabolism, Manganese has been shown to negatively affect intellectual abilities in school aged children, in a recent study regarding manganese concentrations in tap water. A team of researchers from the University of Montreal, the University of Quebec, and the Polytechnic School of Montreal were able to show a correlation between higher levels of manganese in drinking water supplied by groundwater, and lower Intelligent Quotient (IQ) scores in children. The group’s findings were published in the journal Environmental Health Perspectives ( under the title “Intellectual Impairment in School-Age Children Exposed to Manganese from Drinking Water”; this will be henceforth referred to as the primary source. The online news website Softpedia ( recently published an article about this study’s findings entitled “Manganese Drinking Water Affects Children’s Intellectual Abilities” which will be simply called the secondary source from this point.

The goal of both sources is to relay the results from the study to the reader so that they can understand what was done in the experiment and the implications the results have on current understanding and policies regarding the issue of water quality. In my opinion both sources were successful in this objective, however they varied in amount of information given regarding both how the experiment was conducted and the presentation of the actual results obtained.

Details regarding the method in which the experiment was carried out are important because they give the reader context when looking at the results. The secondary source provides a very brief summary of the overall process the researchers used to collect their data stating:

“Each child had the concentration of manganese in tap water from their home measured, as well as magnesium, copper, zinc, lead, arsenic, iron and calcium. After estimating the overall amount of manganese from tap water and food (from a questionnaire), scientists tested each child for motor skills, cognition and behaviour.” (Biliuti 2010)

This brief description covers the majority of the important points regarding the methods used concisely; however it fails to mention one of the key parts of the experiment which was the testing of the children’s hair for traces of manganese. These tests and the results that came from them was a major component in the analysis of the effect manganese had on the child and also helped the researchers to determine that it was the manganese is the child’s drinking water that was affecting their IQ test results and not manganese intake from their diet. In the primary source this relationship was clearly outlined:

“Children’s MnH increased with MnW and estimated manganese intake from water consumption (Figure 1a), but not from the estimated dietary manganese intake (Figure 1b)….Estimated dietary manganese intake was not significantly associated with IQ scores in unadjusted or adjusted analyses (results not shown). Table 3 presents unadjusted and adjusted changes in IQ scores for a 10-fold increase in exposure level for 3 exposure indicators: MnW, estimated manganese intake from water consumption, and MnH.”(Bouchard et al. 2010)

Based solely on the information given in the secondary source, the reader may have their own doubts about the testing techniques and could think that these alarming results could just be due to a fluke in data collection. The primary source goes into great detail about how each specific test was done including: how a gradient of manganese concentration was studied (by testing multiple municipalities), which test was used to test the children’s IQ (Wechsler Abbreviated Scale of Intelligence), and how accurate water samples were collected. The secondary sources states that the researchers accounted for such covariates as family income and maternal intelligence; however it does not delve any deeper into the matter. Whereas the primary source gives a detailed description of what statistical analyses were used to account for this variables. The secondary source only gives the skeleton of what was done in this study.

Along with the simplification of the experiment process, comes the simplification of results obtained. The secondary source does not skew the final results, and even uses a quotation from the lead author of the primary source Maryse Bouchard about the conclusions drawn. However it leaves out information about the trends and relations between such things as manganese concentrations in water, diet, and hair samples, as well as water consumption and other external variables. The primary source includes a complete analysis of all the data, giving a better understanding of the implications of this study in regards to public policy, and furthers our understanding of how manganese is digested and processed in the bodies of children. This abundance of information may be confusing to readers who are not accustomed to reading scientific papers, and therefore not all readers would be able to grasp all the information presented in the primary source. As aforementioned the secondary source did not over exaggerate any results, it simply did not go very in-depth in describing everything that the research team discovered during their work.

Although the secondary source does not provide nearly as much information as the primary source, all in all it was a fine news article about the study. Many members of the general public would have trouble reading and fully understanding a scientific paper, and would not want to siphon through thirty pages of academic gargle. Brief news articles that sum up the main points of scientific reports provide the public with the information that concerns them and affects their daily lives. The primary source provides the necessary statistics for other scientists and public policy makers to review, the secondary source alerts the public of the issue and how they are being affected by the tap water being provided for them. This allows everyone needed to invoke change for the better to be informed, ensuring that something is done to prevent further damage from manganese in drinking water.

Photo taken from Bouchard et al. 2010.

Erica Gilbeault-Ryan, ID: 0720310


Biliuti, Smaranda. "Manganese in Drinking Water Affects Children's Intellectual Abilities." September 20th, 2010: Web. 22 Sep 2010.>

Bouchard, Maryse. "Intellectual Impairment in School-Age Children Exposed to Manganese from Drinking Water." Environmental Health Perspectives (2010): Web. 23 Sep 2010.>

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