Posted by & filed under General Psychology, Human Development, Intelligence, Neuroscience, Research Methods, Stress Coping - Health.

Description: You have certainly heard about people described as anti-vaxers, people wo do not want their children vaccinated against diseases link the measles, mumps and rhubella because they believe there is scientific evidence that immunizations cause autism (despite the fact that the evidence is conclusive that there is no such effect and that the dangers of exposure to diseases that have been close to controlled by vaccination high). Well put that aside for now and consider something g you may not be as aware of – fluoridation. Fluoride is present naturally in some water supplies and it was discovered than when it was present, children who drank the water had far fewer cavities than did children who drank un-fluoridated water. After much research which confirmed the dental health advantages of fluoride and showed no consistent detrimental effects many municipalities added fluoride to their drinking water. And what was the public’s reaction to this? Well, the vast majority enjoyed fewer child cavities and otherwise did not give it a second thought. For some, however, like anti-vaxers, this was a dangerous threat that needed to be stopped. So, recently, years later, a study is published in the Journal of the American Medical Asosiciation (that means BIG deal research) which reported that prenatal exposure to fluoride may (or may not, depending on how you measure it) lead to lower preschool IQ scores. What should we do? Well if you are one who has always worried about fluoride then you may not need to read the article to decide that it suggests that “claims that thousands of studies show fluoridation is safe are not true. In fact, public health has been negligent about examining the health of people living in fluoridated communities.” One study! Well you can stop reading now or you can decide that, in the words of Seth Meyers “Its time for a closer look.”  If, like me, you put at least as much (actually a little more) faith in the scientific perspectives of late night talk show hosts as you do in those of anti-vaxers and anti-fluoridationists then have a read through the article linked below which provide a VERY useful critical review.

Source: Fluoride won’t make you dumber, but the ‘debate’ about its safety might, Andre Picard, The Globe and Mail.

Date: August 23, 2019

Photo Credit: Alastair Pike, The Globe and Mail

 Article Link:

Ok, so what do you think about fluoridation now? Something that is, hopefully, part of any introductory psychology course section on research methodology is the notion that studie4s need to be well designed, that causal statements need to be made carefully and sparingly and that the findings of single studies are rarely, if ever, definitive enough to support suggestions regarding public (health) policy. If and when you see studies like this one written about in the news media or waved about by special interest groups, I hope you read them as carefully and as critically as the author of the above linked article did. Oh, and, IQ tests of 4-year-olds do not typically produce stable results.

Questions for Discussion:

  1. Based on the research article discussed in the linked article does fluoride effect intelligence?
  2. What are some of the issues relating to the discussed research that could (should) limit the interpretive weight we place on it?
  3. If someone was reading the research article discussed above and was not aware of any of the other research on fluoridation what advice would you give them?

References (Read Further):

Bellinger, D. C. (2019). Is Fluoride Potentially Neurotoxic?. JAMA pediatrics.

Green, R., Lanphear, B., Hornung, R., Flora, D., Martinez-Mier, E. A., Neufeld, R., … & Till, C. (2019). Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA pediatrics.

Christakis, D. A. (2019). Decision to Publish Study on Maternal Fluoride Exposure During Pregnancy. JAMA pediatrics.

Sanders, A. E., Grider, W. B., Maas, W. R., Curiel, J. A., & Slade, G. D. (2019). Association Between Water Fluoridation and Income-Related Dental Caries of US Children and Adolescents. JAMA pediatrics, 173(3), 288-290.

Green, R., Lanphear, B., Hornung, R., Flora, D., Martinez-Mier, E. A., Neufeld, R., … & Till, C. (2019). Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA pediatrics.

Xiang, Q., Liang, Y., Chen, L., Wang, C., Chen, B., Chen, X., … & Shanghai, P. R. (2003). Effect of fluoride in drinking water on children’s intelligence. Fluoride, 36(2), 84-94.

Zhao, L. B., Liang, G. H., Zhang, D. N., & Wu, X. R. (1996). Effect of a high fluoride water supply on children’s intelligence. Fluoride, 29(4), 190-192.

One Response to “Psychological Research and Public Policy: A Study of Fluoridation and IQ”

  1. Christine Massey, M.Sc.

    We now have 5 studies linking prenatal fluoride exposure to reduced cognitive function in human offspring. Three of them involved exposures that are common in U.S. and Canadian fluoridated communities and were government-funded:

    Over 400 studies have now found fluoride to be neurotoxic:

    I live in Ontario, Canada and have sent formal freedom of information requests to a number of Ontario and Alberta institutions including the Ontario Ministry of Health and Long Term Care, Public Health Ontario, the Alberta Ministry of Health and the City of Calgary. None have been able to supply or cite even one primary, peer-reviewed study indicating that fluoride exposure (at any level) during pregnancy is actually safe with respect to childhood IQ (or ADHD):

    So my question is this: what evidence are you relying on when implying that water fluoridation is actually safe for babies in the womb, with respect to childhood IQ or ADHD symptoms?

    Thanks in advance. I’m looking forward to your response,

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