A dentist's perspective on common claims about fluoride

There have been so many claims recently made by politicians and so called “experts” relative to fluoridated water. Here, I address what I believe are the four most trendy and controversial claims. Again, these are just my thoughts backed by the literature.

The decision to add fluoride to drinking water was based on scientific research conducted in the early 20th century, showing significantly lower rates of tooth decay in areas with naturally high fluoride levels in drinking water. In 1945, Grand Rapids, Michigan, became the first US city to fluoridate its water as part of a public health initiative aimed at reducing dental cavities. The ADA and CDC endorse water fluoridation as a safe and effective public health measure for reducing cavities across all age groups.¹

Claim: Fluoride in water is inefficient at preventing tooth decay because it enters the bloodstream.

While fluoride does enter the bloodstream, the primary benefits of water fluoridation for dental health are topical rather than systemic. Numerous studies have shown that low levels of fluoride, such as those used in water fluoridation (typically 0.7 parts per million in the US), help prevent tooth decay by remineralizing tooth enamel and making it more resistant to acids produced by bacteria. A meta-analysis of studies published by the Cochrane Oral Health Group concluded that water fluoridation results in a significant reduction in tooth decay in children and adults.2

Claim: Fluoride lowers IQ and causes bone cancer, arthritis, bone fractures, thyroid injuries, and calcifies the pineal gland.

This claim includes several alleged health risks, which I will address individually:

• IQ and neurological effects: Some studies, especially those conducted in regions with very high natural fluoride levels (often 2–10 mg/L; well above the level used in water fluoridation), have suggested an association between high fluoride exposure and lower IQ in children. However, a 2021 report by the National Academies of Sciences concluded that at the levels used for water fluoridation in the US, there is insufficient evidence to suggest a link between fluoride and adverse neurological effects in children.³
• Bone cancer: Studies have examined the potential link between fluoride and bone cancer (such as osteosarcoma), with most finding no clear association. The most notable article is a 2011 study from Harvard University, and several other peer-reviewed studies in the journal Cancer Causes & Control found no evidence that fluoridated water increases the risk of bone cancer.⁴
• Bone fractures and arthritis: The relationship between fluoride and bone health is complex, but studies show that at fluoridation levels used in drinking water, fluoride does not increase the risk of bone fractures or arthritis. The CDC states that levels in fluoridated drinking water are safe and do not cause skeletal fluorosis, a condition that can weaken bones but only occurs at much higher fluoride levels.⁵
• Thyroid injury: High levels of fluoride may impact thyroid function, particularly if iodine deficiency is also present. However, levels used in community water fluoridation have not been shown to adversely affect thyroid health. A review published in the British Dental Journal found no evidence linking typical fluoride exposure from drinking water to thyroid dysfunction.⁶
• Pineal gland calcification: Claims about fluoride and pineal gland calcification are largely speculative. The pineal gland naturally calcifies with age, and there is no evidence that low levels of fluoride, such as those in drinking water, contribute significantly to this process or affect brain function. According to the WHO, current research does not support a direct link between fluoridated water and pineal gland calcification.⁷

Claim: Water fluoridation was part of a conspiracy to “zap the vigor of the American people.”

This one is comical. The theory that fluoride was added to the water supply to reduce vigor is a common but unsubstantiated conspiracy theory not backed by any notable research.

The decision to add fluoride to drinking water was based on scientific research conducted in the early 20th century showing significantly lower rates of tooth decay in areas with naturally high fluoride levels in drinking water. Since 1945, the ADA and CDC have endorsed water fluoridation as a safe and effective public-health measure for reducing cavities across all age groups.⁸

Claim: Removing fluoride from water would improve Americans’ health.

My main issue here is that this claim overlooks the widespread public-health benefits associated with water fluoridation. The CDC has called water fluoridation one of the top 10 public health achievements of the 20th century because of its role in reducing tooth decay by an estimated 25% in both children and adults.⁹ Studies have shown that communities that cease water fluoridation experience a rise in dental cavities. For example, a 2018 study published in Community Dentistry and Oral Epidemiology found an increase in tooth decay in children in Calgary, Canada, following the city’s decision to stop water fluoridation.¹⁰

Final thoughts

The arguments against water fluoridation presented in all four of these claims are largely unsupported by past/current scientific evidence. Low levels of fluoride in drinking water have been shown to provide significant public-health benefits, particularly in reducing dental cavities.

Studies consistently indicate that these levels do not pose a risk to IQ, increase cancer risk, or cause adverse effects on bones, thyroid function, or the pineal gland. Based on extensive research, leading health organizations such as the CDC, WHO, ADA, and American Academy of Pediatrics continue to support water fluoridation as a safe, efficient, and cost-effective public-health measure. Ultimately, you do not need fluoride in your drinking water, but if consumed, it is perfectly safe.

Editor's note: This article originally appeared in DE Weekend, the newsletter that will elevate your Sunday mornings with practical and innovative practice management and clinical content from experts across the field. Subscribe here.

References

1. Timeline for Community Water Fluoridation. Centers for Disease Control and Prevention. https://www.cdc.gov/fluoridation/timeline-for-community-water-fluoridation/index.html.
2. Iheozor-Ejiofor Z, Worthington HV, Walsh T, et al. Water fluoridation for the prevention of dental caries. Cochrane Database Syst Rev. 2015;2015(6):CD010856. Published 2015 Jun 18. doi:10.1002/14651858.CD010856.pub2
3. National Research Council. 2006. Fluoride in Drinking Water: A Scientific Review of EPA's Standards. Washington, DC: The National Academies Press. https://doi.org/10.17226/11571
4. Kim FM, Hayes C, Williams PL, et al. An assessment of bone fluoride and osteosarcoma. J Dent Res. 2011;90(10):1171-1176. doi:10.1177/0022034511418828
5. Community water fluoridation frequently asked questions. Centers for Disease Control and Prevention. May 15, 2024. https://www.cdc.gov/fluoridation/index.html
6. Foley, M. Fluoridation and hypothyroidism–a commentary on Peckham et al. Br Dent J.219, 429–431 (2015). https://doi.org/10.1038/sj.bdj.2015.841
7. Fluoride in drinking water. Background document for development of WHO guidelines for drinking-water quality. World Health Organization. 2004. https://www.who.int/docs/default-source/wash-documents/wash-chemicals/fluoride-background-document.pdf
8. Fluoridation facts. American Dental Association. https://ebusiness.ada.org/Assets/Docs/S795.pdf
9. Centers for Disease Control and Prevention. "Ten Great Public Health Achievements -- United States, 1900-1999." Morbidity and Mortality Weekly Report, vol. 48, no. 12, 1999.
10. McLaren L, Singhal S. Does cessation of community water fluoridation lead to an increase in tooth decay? A systematic review of published studies. J Epidemiol Community Health. 2016;70:934-940.