In a February 7, 2022, letter to Dr. Rick Woychik, current director of the National Toxicology Program (NTP), two officials from the American Dental Association (ADA), Cesar Sabates (president), and Raymond Cohlmia (executive director) said that the ADA:

“is concerned about the National Toxicology Program’s forthcoming state-of-the-science report examining whether there is a causal relationship between fluoride exposure and potential neurodevelopmental and cognitive effects.”

And they should be! The science, including at least four studies funded by U.S. government agencies, overwhelmingly shows that fluoride can lower IQ  (Bashash, 2017, Green, 2019) and increase symptoms of ADHD (Bashash, 2018), when exposed to fluoride during fetal development and when bottle-fed with formula made up with fluoridated water (Till, 2020).

We wholeheartedly agree with the ADA when it asks for “the NTP to base its coming report of fluoride on scientific evidence.” Unfortunately, the Fluoride Action Network and the American Dental Association disagree about what constitutes science.

Perhaps the last genuinely scientific statement from the ADA on the risks posed by fluoridation came in a 1944 editorial in their journal, when they wrote,

 “We do know that the use of drinking water containing as little as 1.2 to 3.0 ppm of fluorine will cause such developmental disturbances in bones as osteoporosis, and we cannot run the risk of producing such systemic disturbances in applying what at present is a doubtful procedure intended to prevent development of dental disfigurement in children. In the light of our present knowledge or lack of knowledge of the chemistry of the subject, the potentialities for harm far outweigh those for good,”
Journal of the American Dental Association, Oct 1, 1944

Such honest concerns about the toxicity of fluoride disappeared in 1950 when the ADA quickly followed the US Public Health Service’s endorsement of water fluoridation. These endorsements were made without any significant study of short- or long- term health effects being published (The Case Against Fluoride, Chelsea Green, 2010). Since then this well-heeled lobbying body has promoted fluoridation and the wide use of fluoride in dental products. For over 70 years it has consistently and vigorously denied any evidence of harm on any tissue except the teeth, where they acknowledge that fluoride causes enamel damage called dental fluorosis.

Now with the scientific demise of its safety claims in sight, this ADA letter to the NTP is a last-ditch effort to use their PR skills to shift the focus from fluoride’s dangers to the infant brain back to the benefits to the teeth.

The ADA’s letter to Dr. Woychik states:

“The Centers for Disease Control and Prevention has hailed community water fluoridation as one of 10 great public health achievements of the 20th century and noted it is an inexpensive way to reduce tooth decay by at least 25% in the population.

It would be a shame to distract from over 75 years of public health success over a simple matter of communicating the science, which is often more nuanced than a sound bite can convey,”

Specifically, the ADA does not want the NTP to draw the obvious conclusions from the science that they are reviewing, namely that a) fluoride is neurotoxic for children and b) it is neurotoxic for both the fetus and infants at the levels used in fluoridation programs.

In their letter to Woychik, they try to muddy the waters by suggesting that a peer review by a panel formed by the National Academies of Science, Engineering and Medicine (NASEM) dismissed such findings, which they did not.

The ADA claims that “NASEM noted that NTP failed to provide adequate scientific evidence for its conclusion” that fluoride is a neurotoxicant. This is incorrect. The NASEM called on the NTP to explain its methodology and findings with greater clarity and transparency (a procedural matter), which is distinct from NASEM stating that the underlying science does not support fluoride being a neurotoxicant (a substantive matter).  Importantly, the NASEM committee explicitly stated they did not independently evaluate the underlying scientific evidence and they were not charged with reaching a conclusion as to the hazard rating the NTP should give to fluoride.

All this pertains to one fact and one fact only, the conclusion by the NTP in both drafts:

“NTP concludes that fluoride is presumed to be a
cognitive neurodevelopmental hazard to humans…”

…and not the science that generated that conclusion. For a careful review of what NASEM actually said about the NTP draft reviews see FAN’s s analysis.

For those who know the track record of the ADA’s promotion of water fluoridation, it is ironic that it is demanding “science” from the NTP. The contrast in scientific integrity between the two bodies could not be more evident. On the one hand, the ADA dismissed the relevance of the most rigorous epidemiological study on fluoride’s impact on the developing brain within a few minutes of its publication in September 2017, erroneously claiming it was not relevant to the USA, whereas on the other hand, the NTP has been meticulously reviewing all the human and animal studies on fluoride’s neurotoxicity for over 5 years.

The lack of scientific integrity with the ADA’s promotion of water fluoridation is nothing new.

Their standard approach for decades has been to find a reason to dismiss any study that reports an inkling of harm from the practice of water fluoridation. They simply work backwards from their “belief system” that fluoridation is “safe and effective” no matter how strong the evidence of harm maybe.

In the case of the landmark Bashash mother-offspring study (Bashash, 2017) mentioned above, the ADA’s claim that it was not relevant to the USA was based on the fact that Mexico does not fluoridate its water. This is what the ADA issued in its press release, distributed within a few minutes of the publication of the Bashash study:

“…the findings are not applicable to the U.S. …because it is unknown how the subjects of the study ingested the fluoride – whether through salt, water, or both – no conclusions can be drawn regarding the effects of community water fluoridation in the U.S..” – ADA News Release 9/19/17

This is a not a science-based conclusion. The relationship between mothers’ exposure and lowered IQ in their offspring in this study was based on mothers’ urinary fluoride levels which is independent of its source (whether it be in salt, food, water, or dentifrice). Thus, this study can be used to compare IQ loss related to fluoride exposure in any country or community in which urinary fluoride levels are measured. Indeed, within a year of the Bashash-2017 study being published, a Canadian study (Till, 2018, funded by the National Institute of Environmental Health Sciences (NIEHS)) found that the average urinary fluoride levels in pregnant women in fluoridated communities in Canada were almost identical to the levels in the Bashash-2017 study (0.91 versus 0.87 ppm). A year later another NIEHS-funded mother-offspring study essentially replicated the Bashash findings in Canadian cities (Green et al., 2019).

In short, the ADA does not specialize in science but in propaganda. Its inaccurate and misleading pronouncements are made in order to protect the practice of fluoridation it has advocated for seven decades.

Meanwhile, the scientific evidence that the NTP has collected is damning as far as water fluoridation is concerned and the ADA knows it.

In its draft review, of the over 150 human studies on fluoride and cognition it reviewed, the NTP identified 29 high quality (which they define as “low risk of bias”) human IQ studies of which 27 found a lowering of IQ associated with fluoride exposure and only two that did not. Moreover, of these 27 studies 18 were performed at fluoride water levels at, or less than, 1.5 ppm and of these 13 were conducted at 0.7 ppm or equivalent exposures. This data has been summarized graphically by FAN in Figure 1.

Figure 1: FAN’s summary of the data from the studies ranked of High Quality by the NTP in their draft review (NTP, 2021). This is based upon a poster (Neurath et al.) presented to the ISEE conference in 2021.

Currently the USA recommends fluoridation at 0.7 ppm. 1.5 ppm is relevant because you need a margin of safety of at least 2 to protect all children drinking water at 0.7 ppm. Even that is not sufficiently protective. Normally, the EPA uses a margin of safety factor of 10 to account for the full range of sensitivity in a large population to any toxic substance.

We believe that the task of the NTP is to make these findings clear and visible. Traditionally the NTP does not perform risk assessments. However, this data will clearly make it easy for the appropriate agency to do one.


For any rational, independent observer the weight of evidence is clearly in favor of ending the practice of water fluoridation forthwith, since strong evidence of harm in high quality U.S. government-funded (and other) studies has found harm to the developing brain at the very levels at which water is fluoridated.

Unfortunately, the ADA is so biased in this matter that they are willing to use their lobbying power to continue this outdated and dangerous practice, regardless of the costs to the mental development of the nation’s children.

FAN has a clear scientific interest in this issue. We have investigated the issue of fluoride’s neurotoxicity for over 20 years. In 2016, our findings prompted us to a) petition the EPA under TSCA to ban the deliberate addition of fluoride to the drinking water (our case is currently in Federal court) and b) request that the NTP review this literature.

Our concerns about fluoride’s toxicity and our opposition to water fluoridation has always been science-based and we wish to see the best science prevail, wherever that takes us.  In this respect, the NTP’s mission of assessing fluoride’s neurotoxicity should be blind to any perceived benefits fluoride may have for teeth.

However, beyond FAN’s concerns about fluoridation, we believe that it is in the national interest that the NTP be seen by the public to be upholding the highest scientific standards in their reviews.  In our view it is absolutely essential that the NTP uphold its scientific integrity in this matter and publish its report without bending to any special interests to change or modify its findings no matter how powerful those special interests might be whether it be from die-hard supporters of fluoridation at the ADA, the Centers for Disease Control and Prevention (CDC) or the National Institute for Dental and Craniofacial Research (NIDCR).

We dread the time that the country is doomed to steer its way through scientific controversies without the rudder of honest science. The NTP should be that rudder in issues of toxicology. In our view, if the NTP succumbs to such pressures it removes any rational foundation for its existence.

Paul Connett, PhD
Fluoride Action Network

PS – Later today we will be issuing a press release on this issue which will include a link to a letter from Paul Connett to Dr. Roy Woychik. We will make these available to our readers on Wednesday.

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