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Community Water Fluoridation and IQSeptember 2011

Those opposed to fluoridation continue to compile studies reportedly supporting the theorythat fluoridation causes lower IQ in children.1 The studies often cited are from China, Indiaand Mexico where conditions are not similar to those in the US. The vast majority has neverbeen published in peer-reviewed, English language journals. Those opposed to fluoridationin the U.S. paid to have the foreign studies which supported their antifluoridation positiontranslated from Chinese to English. The quality of these studies does not stand up toscientific scrutiny. Promotion of these papers only clouds the issues and plants fear in theminds of the public.

In the report on fluoride in drinking water issued by the National Research Council in 2006,

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the expert committee commented that the significance of the Chinese studies they reviewedwas uncertain. Most of the papers were brief reports and omitted important proceduraldetailsMost of the studies did not indicate whether the IQ tests were administered in ablinded manner. Some of the effects noted in the studies could have been due to stressinduced by the testing conditions. Without detailed information about the testing conditionsand the tests themselves, the committee was unable to assess the strength of the studies.

In England in 2009, the South Central Strategic Health Authority requested an independentcritical appraisal of 19 papers and one abstract that reported an association betweenfluoride in drinking water and IQ in countries outside England. Bazian, Ltd., an independentcompany that provides evidence-based support for healthcare decisions completed the

appraisal

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and noted that the study design and methods used by many of the researchershad serious limitations. The researchers also exhibited a lack of a thorough consideration ofconfounding factors as a source of bias in the results. From these studies alone, it wasuncertain how fluoride was responsible for any impairment in intellectual development.Significant differences were noted between conditions in the communities studied andconditions in England. For example, some studies noted high levels of naturally occurringfluoride in drinking water and exposure to fluoride from other sources including the practiceof burning high fluoride coal to heat poorly ventilated homes in China. Additionally, in manycases, there were stark differences in socioeconomic characteristics.

At the request of the European Commission, the Scientific Committee on Health andEnvironmental Risks (SCHER) conducted a critical review of any new evidence on the

hazard profile, health effects, and human exposure to fluoride and the fluoridating agents ofdrinking water. Their report of May 20114 reviewed animal and human studies finding thereis not enough evidence to conclude that fluoride in drinking water at concentrationspermitted in the EU may impair the IQ of children. SCHER also agrees that a biologicalplausibility for the link between fluoridated water and IQ has not been established.

It is important to make decisions about community water fluoridation based on the bestscience available.

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References

1. Fluoride Action Network Fluoride. Effects on IQ. Accessed athttp://www.fluoridealert.org/iq-studies.html

2. Committee on Fluoride in Drinking Water, National Research Council. Fluoride inDrinking Water: A Scientific Review of EPAs Standards. National Academies Press.2006. Accessed at http://www.nap.edu/catalog.php?record_id=11571

3. Bazian Ltd. Independent critical appraisal of selected studies reporting anassociation between fluoride in drinking water and IQ. A report for South CentralStrategic Health Authority. February 11, 2009. Accessed athttp://www.whatdotheyknow.com/request/53552/response/144904/attach/2/DE578275%20Bazian%20report.pdf

4. European Commission, the Scientific Committee on Health and Environmental Risks(SCHER). Critical review of any new evidence on the hazard profile, health effects,

and human exposure to fluoride and the fluoridating agents of drinking water 16May 2011. Accessed athttp://ec.europa.eu/health/scientific_committees/environmental_risks/docs/scher_o_139.pdf