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Editor's Note
August 19, 2019

Decision to Publish Study on Maternal Fluoride Exposure During Pregnancy

Author Affiliations
  • 1University of Washington, Seattle
  • 2Seattle Children’s Research Institute, Seattle, Washington
  • 3Editor, JAMA Pediatrics
JAMA Pediatr. 2019;173(10):948. doi:10.1001/jamapediatrics.2019.3120

The decision to publish this article was not easy.1 Given the nature of the findings and their potential implications, we subjected it to additional scrutiny for its methods and the presentation of its findings. The mission of the journal is to ensure that child health is optimized by bringing the best available evidence to the fore. Publishing it serves as testament to the fact that JAMA Pediatrics is committed to disseminating the best science based entirely on the rigor of the methods and the soundness of the hypotheses tested, regardless of how contentious the results may be. That said, scientific inquiry is an iterative process. It is rare that a single study provides definitive evidence. This study is neither the first, nor will it be the last, to test the association between prenatal fluoride exposure and cognitive development. We hope that purveyors and consumers of these findings are mindful of that as the implications of this study are debated in the public arena.

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4 Comments for this article
This Should Not Have Been Published
Julian Poulton-King | Monash Health
I can see multiple red flags that lead me to believe this should not have been published without further exploration. There is no proposed mechanism explaining why there would be a gendered effect on IQ. This is frequently a sign that further data collection and analysis is necessary. Such a weak study design with such a low number of participants comparing two variables at two distant time points is tenuous at best, especially considering the fluoride concentration in the supply or urine fluoride concentration led to inconsistent IQ differences across genders.

The number of statistical controls placed does
not account for many confounding factors, e.g. drinking bottled water, among many others. The comparison of 3-4 IQ points difference comparing the highest fluoride concentration group with the lowest concentration does not establish a dose-response of any sort. Yet another red flag.

If I had a study with 500 participants that showed using heavy bandaid use at a one-time point that only affected one gender was connected to basically negligible cancer at some distant point. I wouldn't be publishing it knowing it may lead to real harm with parents not using bandaids leading to infections. I would scrutinize my data, find other data to perform a retrospective analysis of this proposed effect and look at the numerous studies that don't appear to show such a connection and explain why they may have missed this effect. None of this has been done. I am very disappointed in JAMA Pediatrics.
ingesting Fluoride
Jacqueline Theriault | Clean Water Silicon Valley
On Nov 22, 2016, a coalition including FAN, Food & Water Watch, Organic Consumers Association, American Academy of Environmental Medicine, International Academy of Oral Medicine and Toxicology, Moms Against Fluoridation, and several individual mothers, filed a petition calling on the EPA to ban the deliberate addition of fluoridating chemicals to the drinking water under provisions in the Toxic Substances Control Act (TSCA).

This lawsuit is based on a large body of human, animal, and cellular research, which shows that fluoride is neurotoxic at doses within the range now seen in fluoridated communities. The judge of the U.S.
District Court for the Northern District of California has just announced that the trial will begin on February 3, 2020.

As many independent scientists now recognize, fluoride is a neurotoxin. The question, therefore, is not if fluoride damages the brain, but at what dose. This Federal Lawsuit against the EPA will allow the court to determine based on over 2800 studies (suppressed by EPA and CDC) showing the dangers of ingesting fluoride.
Premature adjudication
Jorge Sallent, M. D. | Retired Pediatric Pulmonologist
This will feed the pack of personal injury attorneys. We’ll soon see gullible sentimental juries and judges conclusively promulgating a cause-effect relationship between any fluoride exposure and any intellectual/cognitive variance in children. Perhaps even adults. Our society is excessively celebratory of tort events fueled by the greed of lawyers eager to collect a high monetary percent of fellow humans misery. Best not to nurture that behaviour.
Could We Please Have More Biomarkers?
Ray Grogan, BS genetics | Prophy Research Corporation
“Pits and fissures” can be easily measured at this age and the difference was huge in one study .

Enamel SEM’s are trickier, but clearly show a physical difference .

Caries – To me it seemed the authors strained to not say that Grade I evidence shows that “… Caries activity was very low in both study groups: 92% of children remained caries-free in the treatment group [1mg F in pregnancy and .25 mg F at birth] and 91% remained caries-free in the placebo group [.25 mg F at birth]. …” .

More outcomes.

Age of
tooth eruption is easy to track. There is a little evidence that prenatal fluoride slows it down .
Age of menarche is the easiest way to measure overall speed of development.
IQ vs age / cortical thickness is not easy to measure, but given the importance of these IQ findings it is worthwhile. Slowing down IQ development seems to make a profound difference .

And one more covariate:

Iodine, more than any other known nutrient, affects IQ and in modern busy families it is easy to get food from either restaurants or factories, neither of which use iodized salt. The wiki says that when iodized salt was introduced in 1924, “there was a gradual increase in average intelligence of 1 standard deviation, 15 points, in iodine-deficient areas and 3.5 points nationally.”

About the best we have is a comment by Feltman (J Dent Med 1961 16(4):190-198) about teeth in his prenatal fluoride group. He found "a delay in the eruption of the teeth, in some cases by as much as a year from the accepted eruption dates". And there is a good review of fluoridated water having a moderate effect on slowing down eruption. See Kunzel, 1976. Caries Res 10:96. Tooth eruption / development / maturity is, of course, tied to overall development – here is a good report tying tooth eruption to the onset of menstruation and the stopping of height growth in the leg bones (Lewis, A.B. and Garn, S.M. (1960) The relationship between tooth formation and other maturational factors. The Angle Orthodontist, 30, 70-77.)

“The top scoring children had a delayed but extended cortical growth spurt, the researchers report in the 30 March Nature. In these children, who scored above 120 on the IQ tests, the cortex started out relatively thin. Then it grew rapidly, peaking in thickness around age 11 before falling off. In children with average IQ scores (around 100) cortical thickness peaked between 7 and 8 years of age. By early adulthood, the cortex was similar in thickness in the superior and average IQ children, however, suggesting that the key difference is the time course of development, not the final result, Shaw says. "The regions where the differences [in development] were most striking were in prefrontal cortex, which is interesting because that's the seat of the most complex and uniquely human activities like planning and abstract thought," he adds.” ( https://www.sciencemag.org/news/2006/03/brain-development-linked-iq)


Glenn FB, Glenn WD, Duncan RC. Prenatal fluoride tablet supplementation and improved molar occlusal morphology: part V. ASDC Journal of Dentistry for Children 1984;51:19-23. https://www.ncbi.nlm.nih.gov/pubmed/6583215 

LeGeros RZ, Glenn FB, Lee DD, Glenn WD. Some Physico-chemical properties of deciduous enamel of children with and without pre-natal fluoride supplementation (PNF). Journal of Dental Research 1985; 64(3):465-469.

Leverett DH, Adair SM, Vaughn BW, Proskin HM, Moss ME. Randomized clinical trial of the effect of prenatal fluoride supplements in preventing dental caries. Caries Research 1997; 31:174-179. https://www.karger.com/Article/Abstract/262394