A steady stream of science: 34 studies at a glance

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Each time Australia’s National Health and Medical Research Council reviews the safety and effectiveness of fluoride, highly-biased, poor-quality pro-fluoride studies are encouraged, embraced and promoted, while fluoride-disparaging studies are systematically dismissed. Since the cut-off date of the last fluoride review, more than 180 human studies have been published relating to fluoride’s toxicity. Will all of these studies also be dismissed? We take a quick glance at 34 relevant studies.
“Half a century ago, as a public medical officer and as a family doctor, I published support for fluoridation in my country following the USA example. When challenged, I spent hours studying evidence on both sides and became convinced that I was wrong. Each passing decade has strengthened that view. Public water fluoridation breaks the near-universal toxicological precautionary principle that requires providers to prove medicator safety, not dissenters to prove medicator harm."
Doug N. Everingham, MB, BS
Former Australian Health Minister 1972-1975.
  • To say that NHMRC’s methodology is biased is a gross understatement;
  •  Any medical science, especially fluoride science, will NEVER be a “settled matter”;
  • Since NHMRC’s last review, more than 400 toxicity studies have been published, including 180 human studies. Just a few of these are listed below, including:
  •  11 studies showing neurological damage;
  •  7 studies showing thyroid dysfunction;
  • 4 studies showing kidney damage, linking to diabetes;
  • 2 studies on infant intake and bioaccumulation;
  • 4 studies relating to dental and skeletal fluorosis;
  • 5 general studies and reviews of the toxicity of fluoridation chemicals.
  • How many more studies will it take to end this absurd practice?
The review process

About every seven to ten years, Australia’s National Health and Medical Research Council (NHMRC) undertakes a review of scientific studies conducted on the adverse health effects of the chemicals used for water fluoridation. In July 2017, NHMRC published its latest review titled Information Paper – Water fluoridation: dental and other human health outcomes. This review included studies published within an eight-year period from October 2006 to October 2014. Since that cut-off date, more than 180 human studies and more than 230 animal studies have been published relating to the toxicity of fluoride. Many of these studies continue to emphasise that fluoridation chemicals are not safe for ingestion.

Instead of an objective, independent and professional review process – as any reasonable person would expect – the fluoride reviews are explicitly contrived to achieve a predetermined outcome. They inevitably use terms of reference to limit the evidence, involve unreasonable time constraints, allow no foreign language or animal studies and utilise other ridiculous exclusion criteria including only allowing studies on fluoridated water when most Australians receive fluoride from a variety of sources.

For more details about NHMRC’s extremely poor review methodology, see our article: Can the NHMRC be trusted?

A “settled” matter

While supporters of fluoridation have long claimed the safety of fluoride is a “settled” matter, in 2006, the US National Research Centre (NRC) published a comprehensive 3-year review conducted by a panel of 12 scientists and health professionals, which strongly contradicts this view. In addition to concerns about damage to our teeth and bones, the NRC review team identified a range of other health effects associated with fluoride exposure, including damage to the brain, disruption of the endocrine system (thyroid gland, pineal gland, and glucose metabolism), and bone cancer. They emphasised and urged that further detailed long-term biomonitoring research studies were needed, including analysis of fluoride in blood and urine samples and in particular involving the potential effect on brain and endocrine system (especially thyroid) functioning.

In summary, the Chairman of the NRC Review, Dr John Doull, noted:

“What the committee found is that we’ve gone with the status quo regarding fluoride for many years—for too long, really—and now we need to take a fresh look. In the scientific community, people tend to think this is settled. I mean, when the US surgeon general comes out and says this is one of the 10 greatest achievements of the 20th century, that’s a hard hurdle to get over. But when we looked at the studies that have been done, we found that many of these questions are unsettled and we have much less information than we should, considering how long this [fluoridation] has been going on. I think that’s why fluoridation is still being challenged so many years after it began. In the face of ignorance, controversy is rampant.”
Antithesis of objectivity

In stark contrast, in 2007, despite the clear warnings provided in the NRC review, contractors engaged by NHMRC conducted an automated online search and found 5,415 publications on fluoride toxicology. Given they had just a few weeks to write a report on the potential harms of fluoridation chemicals, they immediately used ludicrous exclusion criteria to reduce this list down to 405 publications after scanning abstracts. From this reduced list they included only 77 read papers in their final report. Despite the small number of papers that were actually read for that review, on 8 August 2013 ABC TV’s science program Catalyst broadcast that the NHMRC 2007 fluoride review had reviewed 5,500 studies.     

Australian researcher Dr Geoff Pain says; “Australia’s National Health and Medical Research Council states that the only harm arising from water Fluoridation and total dietary fluoride intake is dental fluorosis.”  Dr Pain points out that, in June 2013 the NHMRC reaffirmed its recommendation of fluoride and in doing so dismissed the comprehensive US NRC report which involved the detailed review of thousands of publications and numerous harms caused by fluoride.

In February 2015, immediately after the embargoed release of a scientific study linking fluoridation to hypothyroidism, the NHMRC CEO again reaffirmed its recommendation of fluoridation, even though the NHMRC later claimed to have no knowledge of that study at that time.

NHMRC’s 2017 review is similar to the 2007 review. It began with the initial inclusion of 1,708 peer-reviewed and 66 non-peer-reviewed articles – a total of 1,774. A superficial scan of each study’s abstract or summary resulted in this number rapidly reducing to 199 and then a further harsh filtering process resulted in only 39 articles reaching the final report. In addition, the review process included an initial 379 submissions from the public regarding the toxicity of fluoride. These were also severely filtered down to only TWO papers in the final report. This means from an initial 2,153 studies, only 41 studies were included in the final report.

“A slide, obtained under Freedom of Information (FOI), shows they still found worrying evidence that fluoridation causes increased bone fracture, cancer and “other harm,” says Dr Pain. “A call for public submissions was made in 2014 and the NHMRC received notification from the public of 379 scientific papers on fluoride, considered highly relevant and published since 2006, the arbitrary cut-off date set by NHMRC,” he says.

Dr Pain has published a Quick Guide to Fluoride Harms, available here.

A constant stream of science

From the list of more than 180 human studies conducted since the cut-off date of NHMRC’s last review, we feel that 33 are particularly worthy of mention. These are grouped into major areas of physiology (and are not listed in chronological order):

Neurotoxicity and cognitive development

1. Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada
“Exposure to fluoride during fetal development is associated with lower IQ scores. These findings, which suggest that fluoride is neurotoxic, underscore the need to critically evaluate the practice of water fluoridation.”
JAMA Pediatrics; August 2019.

2. Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6–12 years of age in Mexico
This 12-year, US$3 million, government-funded study showed significant reductions in children’s IQ when their mothers were exposed to fluoride during pregnancy. This carefully-controlled study of Mexican mother-offspring pairs by American and Canadian researchers, mothers were receiving the same fluoride doses as mothers in the US and Australia who live in communities that add fluoride to their water. Environmental Health Perspectives: September 2017. Also see our article: Fluoride and reduced IQ

3. Community water fluoridation and urinary fluoride concentrations in a national sample of pregnant women in Canada
“Canadian pregnant women have double urine fluoride levels in fluoridated vs. non-fluoridated areas. Previous Mexican research links urine fluoride levels in pregnancy to offspring’s lower IQ. The Canadian and Mexican women’s fluoride levels are similar which causes concern.
Environmental Health Perspectives: October 2018

4. Prenatal fluoride exposure and neurobehavior among children 1–3 years of age in Mexico
“Our findings add to our team’s recently published report on prenatal fluoride and cognition at ages 4 and 6–12 years by suggesting that higher in utero exposure to F has an adverse impact on offspring cognitive development that can be detected earlier, in the first three years of life.”
Occupational & Environmental Medicine: March 2018

5. Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico City
“Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention [in offspring]. This is consistent with a growing body of evidence linking neurotoxicity to early-life fluoride exposure.”
Environment International: December 2018

6. Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association
“This study has empirically demonstrated an association between more widespread exposure to fluoridated water and increased ADHD prevalence in U.S. children and adolescents, even after controlling for SES. The findings suggest that fluoridated water may be an environmental risk factor for ADHD. Population studies designed to examine possible mechanisms, patterns and levels of exposure, covariates and moderators of this relationship are warranted.”
Environmental Health: February 2015

7. Environmental chemical exposures and neurodevelopmental impairments in children
“The current approach to regulating a chemical in the U.S. is to restrict its use only after it is shown unequivocally that exposure impairs human health. Unfortunately, even rudimentary toxicological data are available for only a small fraction of the approximately 80,000 chemicals in use, and most of these data pertain to rather health endpoints such as death, cancer, and birth defects rather than subtle alterations in brain development and function. It is our responsibility to future generations to reduce or, when possible, to eliminate the threats that these chemicals pose to their future well-being.”
Pediatric Medicine: November 2018

8. The auditory working memory of 13-15-year-old adolescents using water with varying fluoride concentrations from selected public primary schools in north Kajiado Sub County
“The study may support the hypothesis that excess fluoride in drinking water is neurotoxic.”
American Journal of Medicine and Medical Science: 2018

9. Potential role of fluoride in the etiopathogenesis of Alzheimer’s Disease
“Fluoride is widespread in the environment and it easily crosses the blood-brain barrier. In the brain fluoride affects cellular energy metabolism, synthesis of inflammatory factors, neurotransmitter metabolism, microglial activation, and the expression of proteins involved in neuronal maturation. Finally, and of specific importance to its role in Alzheimer’s disease, studies report fluoride-induced apoptosis and inflammation within the central nervous system. We describe the impact of fluoride-induced oxidative stress and inflammation in the pathogenesis of AD and demonstrate a role for apoptosis in disease progression, as well as a mechanism for its initiation by fluoride. The influence of fluoride on processes of AD initiation and progression is complex and warrants further investigation, especially considering growing environmental fluoride pollution.
International Journal of Molecular Sciences: December2018

10. Influence of acetylcholinesterase inhibitors used in Alzheimer’s Disease treatment on the activity of antioxidant enzymes and the concentration of glutathione in THP-1 macrophages under fluoride-induced oxidative stress
“These observations suggest that the fluoride-induced oxidative stress may suppress the antioxidant action of AChE inhibitors. Our results may have significance in the clinical practice of treatment of AD and other dementia diseases.”
International Journal of Environmental Research and Public Health: December 2018

11. Aluminium and fluoride in drinking water in relation to later dementia risk
“Higher levels of aluminium and fluoride were related to dementia risk in a population of men and women who consumed relatively low drinking-water levels of both.”
The British Journal of Psychiatry: March 2019

Thyroid functioning

12. Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water
“We found that higher levels of fluoride in drinking water provide a useful contribution for predicting prevalence of hypothyroidism. We found that practices located in the West Midlands (a wholly fluoridated area) are nearly twice as likely to report high hypothyroidism prevalence in comparison to Greater Manchester (non-fluoridated area). In many areas of the world, hypothyroidism is a major health concern and in addition to other factors—such as iodine deficiency—fluoride exposure should be considered as a contributing factor. The findings of the study raise particular concerns about the validity of community fluoridation as a safe public health measure.”
Journal of Epidemiology and Community Health: July 2015

13. Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status
“Adults living in Canada who have moderate-to-severe iodine deficiencies and higher levels of urinary fluoride may be at an increased risk for underactive thyroid gland activity.”
“I have grave concerns about the health effects of fluoride exposure. And not just from my study but the other studies that have come out in recent years,” said lead author Ashley Malin.
Environment International: December 2018

14. Fluoride-induced developmental disorders and iodine deficiency disorders as examples of developmental disorders due to disturbed thyroid hormone metabolism
“Both exposure to fluoride and iodine deficiency during early development can lead to disturbed thyroid hormone metabolism and produce the same spectrum of developmental disorders including short stature, bone deformities, cognitive impairment, delayed dental eruption, and dental fluorosis.”
Fluoride Research:  October-December 2018

15. Fluoride thyroid hormone derangements and its correlation with tooth eruption pattern among the pediatric population from endemic and non-endemic fluorosis areas
“Positive correlation exists between fluorosis and thyroid functional.”
The Journal of Contemporary Dental Practice: December 2018

16. A systematic analysis on possibility of water fluoridation causing hypothyroidism
“The present systematic review suggests a positive correlation between excess fluoride and hypothyroidism. This calls the need for further well-controlled studies in this otherwise emerging alarming issue.”
Indian Journal of Dental Research: June 2018

17. Impact of drinking water fluoride on human thyroid hormones: A case-control study
“The major finding of this study is that TSH values are higher with a higher fluoride concentration in the drinking water, even for generally low fluoride concentrations. This is seen both in cases of untreated hypothyroidism and in controls. Controls, with normal thyroid function, also have higher TSH values with higher fluoride concentrations, even though their TSH values are still within the normal range. TSH values are higher (in both cases and controls) with higher levels of water consumption. This is consistent with an association between increased fluoride intake (due to increased water consumption) and increased TSH. It was found that F impacts human thyroid hormones, especially TSH and T3 even in the standard concentration of less than 0.5 mg/L.
Scientific Reports: February 2018

18. Dental fluorosis, nutritional status, kidney damage, and thyroid function along with bone metabolic indicators in school-going children living in fluoride-affected hilly areas of Doda district, Jammu and Kashmir, India
“There was a significant decrease in thyroid-stimulating hormone (TSH) in the affected area school children compared to control. In conclusion, fluorotic area school children were more affected with dental fluorosis, kidney damage, along and some bone indicators as compared to control school children.”
Environmental Monitoring and Assessment: November 2017

Kidney disease and diabetes

19. Exploring the role of excess fluoride in chronic kidney disease: A review
“This review proposes that there is a direct correlation between Chronic Kidney Disease (CKD) and the consumption of excess amounts of fluoride. Studies particularly show immediate adverse effects on the tubular area of human and animal kidneys leading to CKD due to the consumption of excess fluoride. Therefore, it is very important to conduct more investigations on toxicity studies of excess fluoride on the human kidney, including experiments using human kidney enzymes, to study more in depth the impact of excess fluoride on the human kidney. Further, the interference of excess fluoride on collagen synthesis in human body and its effect on human kidney should also be further investigated.”
Human & Experimental Toxicology: November 2018

20. Evaluation of vascular and kidney injury biomarkers in Mexican children exposed to inorganic fluoride
“…these results suggest that F exposure is related to early vascular alterations, which may increase the susceptibility of cardiovascular diseases in adult life.”
Environmental Research: February 2019

21. Evaluation of kidney injury biomarkers in an adult Mexican population environmentally exposed to fluoride and low arsenic levels
“F exposure was related to the urinary excretion of early kidney injury biomarkers, supporting the hypothesis of the nephrotoxic role of F exposure. Fluoride could be considered an environmental kidney toxicant.”
Toxicology and Applied Pharmacology: August 2018

22. Transcriptome analysis supports viral infection and fluoride toxicity as contributors to chronic kidney disease of unknown etiology (CKDu) in Sri Lanka
“Based on the molecular pathway analysis in CKDu patients and review of literature, viral infections and fluoride toxicity appear to be contributing to the molecular mechanisms underlying Chronic Kidney Disease.”
International Urology and Nephrology: September 2018

Infant intake and accumulation

23. Fluoride Intake of Infants from Formula
“Significantly more infants, particularly those under six months old, will exceed the UL [Upper Limit] when consuming formula reconstituted with 0.7 ppm [fluoridated] water, increasing their risk of developing dental fluorosis.”
Journal of Clinical Pediatric Dentistry: October 2018

24. Fluoride retention in infants living in fluoridated and non-fluoridated areas: effects of weaning
“A relatively large proportion of fluoride intake is retained in the body in weaned infants.”
British Journal of Nutrition: January 2019

Dental and skeletal fluorosis

25. Dental Fluorosis Trends in US Oral Health Surveys: 1986 to 2012
“Large increases in severity and prevalence were found in the 2011–2012 NHANES as compared with the previous surveys, for all sociodemographic categories. For ages 12 to 15 y—an age range displaying fluorosis most clearly—total prevalence increased from 22% to 41% to 65% in the 1986–1987, 1999–2004, and 2011–2012 surveys, respectively. The rate of combined moderate and severe degrees increased the most, from 1.2% to 3.7% to 30.4%.”
Sage Journals: March 2019

26. Ossification of posterior longitudinal ligament and fluorosis.
“Fluorosis is associated with a higher incidence of OPLL” [a spinal cord disease]
Neurology India: September 2018

27. Clinical observation of 5 cases of diabetes insipidus complicated with skeletal fluorosis
“Long-term high intake of fluoride can cause skeletal fluorosis in patients with diabetes insipidus” 
Zhongguo Gu Shang: July 2017

28. A comparison of dental fluorosis in adult populations with and without lifetime exposure to water fluoridation
“Fluorosis is more common in adults with lifetime exposure to water fluoridation than those with no exposure”
Community Dentistry & Oral Epidemiology: September 2018


29. Fluorosis is linked to Anemia
“We report here a simple, easy-to-practice treatment procedure for anaemia, by focusing on withdrawal of fluoride consumption and promotion of nutrients through diet. The approach to improve nutrient intake as supplementation of iron and folic acid or iron tonic does not yield beneficial results. The reason being highly destructive F enters the body through food, water, habit forming substances and dental products destroys the lining of the intestine and prevents absorption of nutrients.”
Current Science: 2018


30. Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health.
In this review, the author examines the molecular mechanisms by which fluoride inhibits the “sodium iodide symporter” (NIS) a specific cell protein that facilitates active iodide transport in the thyroid gland and various other glands in the human body. By inhibiting NIS expression and functionality, this in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. 
International Journal of Environmental Research and Public Health; 26 March 2019.

31. The pathogenesis of endemic fluorosis: Research progress in
the last 5 years
“In the past 5 years, many researchers have conducted in‐depth studies
into the pathogenesis of endemic fluorosis. Research in the areas of fluoride‐induced
stress pathways, signalling pathways and apoptosis has provided further extensive
knowledge at the molecular and genetic level. In this article, we summarize the main
Journal of Cellular and Molecular Medicine – Wiley online Library; February 2019.

32. Water Fluoridation: A Critical Review of the Physiological Effects of Ingested Fluoride as a Public Health Intervention.
“A change in the ideological approach to fluoride use for dental caries prevention is essential in the global public health community. An important change would be for the World Health Organization to repudiate its assertion that fluoride is an essential nutrient or trace element, or that artificial water fluoridation is a useful public health strategy.”
The Scientific World Journal; February 2014.

33. Blood is thicker than water: Flaws in a National Toxicology Program study
“This review identifies ten significant flaws in the design of an animal experiment conducted by the U.S. National Toxicology Program as part of that investigation into the neurotoxic impact of systemic prenatal and postnatal fluoride exposure. The authors hypothesize that organizational bias can and does compromise the integrity of fluoride research.”
ScienceDirect: December 2018

34. The Fluoride Debate: The Pros and Cons of Fluoridation
“Concurrently, recent opposition has been growing worldwide against fluoridation, emphasizing the potential and serious risk of toxicity. Since the fluoride benefit is mainly topical, perhaps it is better to deliver fluoride directly to the tooth instead of ingesting it.”
Preventative Nutritional Food Science: September 2018