Fluoride Action Network

The Fluoride IQ studies

There are now 76 out of 85 IQ studies reporting lowered IQ from exposure to elevated levels of fluoride. Since 2017 we learned that the fluoride level of 0.7 mg/L, the "optimal" level used in U.S. and Canadian drinking water fluoridation projects, can create neurodevelopmental harm to the fetus, bottle-fed infant, and child. The fetus and bottle-fed infant were never considered in any risk assessment for water fluoridation by any regulatory agency in any fluoridating country.

The Fluoride IQ Studies

Fluoride’s ability to damage the brain is one of the most active areas of fluoride research today. Over 600 studies have found that fluoride can damage the brain.

• From 1989 to 2022, a total of 85 studies have investigated the relationship between fluoride and human intelligence.

76 studies have reported that elevated fluoride exposure is associated with reduced IQ in humans.

The 76 studies are based on IQ/cognitive examinations of 27,719 children (73 studies) and 689 adults (3 studies).

Note: The IQ study #67 by Xu 2020 was retracted by the publisher on Nov 8, 2022. We have adjusted the number of each study to reflect that change. On Nov 9, 2022, another IQ study by Saeed et al. was published, for a total of 76 studies.

The 9 studies that did not find an association between fluoride and IQ included 4,363 children and 1,037 adults.

  A little History on the Brain and Fluoride is a brief summary from when fluoride’s effects on the brain were first recorded to the present.

The Mother-Offspring fluoride studies provide compelling evidence that fluoride exposure during the prenatal and postnatal stages of life has the potential to cause neurodevelopmental harm. The level of fluoride exposure in three of these studies is the same level of exposure found in fluoridated communities.

Neurodevelopment is a term referring to the brain’s development of neurological pathways that influence performance or functioning (e.g., intellectual functioning, reading ability, social skills, memory, attention or focus skills).1


Quick Facts About the 75 Studies as of May 2022:

Location of Studies:

China (46), India (14), Iran (4), Mexico (4), Canada (3), Egypt (1), Kenya (1), Pakistan (1), Sudan (1), and Indonesia (1).

Sources of Fluoride Exposure in the 74 Studies:

• 66 studies, drinking water;
• 9 studies, coal burning;
• 1 study, fluoridated salt (Cantoral 2021).


The 2006 National Research Council’s (NRC) chapter 7 on fluoride’s neurotoxicity.

This surprisingly thorough report presents a chapter on fluoride’s neurotoxicity. The report identified 4 Chinese fluoride IQ studies. Of interest is that all 4 studies were published in the journal Fluoride and that PubMed, the major search engine for scientific abstracts, has never indexed this publication. PubMed is comes under the National Institutes of Health.

Note: The Fluoride Action Network has translated the overwhelming majority of the IQ studies published in Chinese. The Fluoride journal has published many FAN translations, while it has also published many studies submitted directly to them, including the 4 studies cited above. See the studies FAN translated.


See also

Human studies on Fluoride’s Neurotoxicity


1. Definition from https://www.bcpn.org/what-is-neurodevelopment-.html

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