Water fluoridation: Myths and Truths

Introduction

In the United States, as in many other parts of the world, adding fluoride to public drinking water is a long-established public health measure designed to promote oral health. Introduced during the 20th century, community water fluoridation has been shown to significantly reduce tooth decay in children and adults alike (CDC, 2024a). Despite its long history and documented benefits, it remains one of the most misunderstood public health practices. Also, over the years, water fluoridation has been the subject of persistent myths, misinformation, and ongoing scientific discussion about the most appropriate levels of fluoride exposure. More recently, the rapid spread of information, and unfortunately, disinformation, through social media and other online platforms has made it increasingly difficult for the public to distinguish well-supported scientific evidence from misleading claims. In this edition of Lab Notes, we'll take a closer look at some of the most common beliefs surrounding water fluoridation, separating myths from evidence while also acknowledging areas where legitimate scientific research continues. If there are specific questions, claims, or topics related to fluoride that you would like us to explore in a future installment of Lab Notes, we would love to hear from you.

What is fluoride? Why is it used in our water supply?

Fluoride is the naturally occurring ionic form of the element fluorine, one of the chemical elements found on the Periodic Table of Elements developed by Dmitri Mendeleev in the 19th century (Flowers et al., 2019). Fluorine is represented by the symbol F and has an atomic number of 9, meaning that each fluorine atom contains nine protons in its nucleus (Flower et al., 2019). It belongs to the halogen family of elements, a group known for being highly reactive because its members readily combine with other elements to form stable compounds (Flowers et al., 2019).

                    Figure 1. Fluoride, from which fluoride comes from is located in the orange square                                 surrounded a black border.

The outermost shell of a fluorine atom contains seven valence electrons, electrons that participate in chemical bonding (Flowers et al., 2019). Because atoms are generally more stable when this outer shell has 8 electrons, fluorine readily gains one additional electron, forming the negatively charged fluoride ion (F⁻) (Flowers et al., 2019). This ionic form, known simply as fluoride, is the form most commonly found in nature (Flowers et al, 2019).

Because elemental fluorine is extremely reactive, it is rarely found by itself in the environment (Fuge, 2019). Instead, it exists almost exclusively as fluoride bound to other elements, forming naturally occurring minerals such as calcium fluoride and sodium fluoride (Fuge, 2019). These fluoride-containing compounds are present in rocks, soils, groundwater, rivers, and even in small amounts in many foods (Fuge, 2019). In fact, fluoride has always been a natural component of our environment, although the concentration varies depending on local geology and water sources (Fuge, 2019).

In dentistry and public health, fluoride is valued because of the way it interacts with tooth enamel. It strengthens the mineral structure of enamel, making teeth more resistant to acids produced by oral bacteria and reducing the risk of cavities (CDC, 2024d). Decades of research have shown that, when present at appropriate levels, fluoride can help protect teeth throughout life. This is why fluoride is commonly found in toothpaste, mouth rinses, and, in many communities, public drinking water (CDC, 2024d).

Community water fluoridation is the controlled adjustment of the natural fluoride concentration in public drinking water to a level that has been shown to reduce tooth decay while minimizing the risk of unwanted effects (CDC, 2024a). The goal is not to medicate the population, but to provide a safe, cost-effective public health measure that helps prevent dental disease across the entire community (CDC, 2024a). This approach is especially beneficial for individuals who may have limited access to regular dental care, helping to reduce oral health disparities and improve overall dental health (CDC, 2024a). With that background in mind, let's take a closer look at some of the most common myths and misconceptions surrounding community water fluoridation.

Myths vs. Truth

Myth 1: Fluoride is an unnecessary chemical added to poison people.

Truth: Fluoride is not a man-made poison. It is a naturally occurring mineral found in rocks, soil, groundwater, and even many foods (CDC, 2024b). In fact, many water sources naturally contain fluoride, although the amount varies depending on local geology (CDC, 2024b).

At the levels recommended for community water fluoridation, fluoride helps strengthen tooth enamel by promoting remineralization which is the natural repair process that restores minerals lost during everyday acid attacks (Aoun et al., 2018). It also helps reduce damage caused by acids produced by bacteria in the mouth and by acidic foods and beverages (CDC, 2024d). For this reason, major public health organizations have concluded that community water fluoridation is safe and effective when maintained at recommended levels (National Institutes of Health, 2024).

If you are curious about the fluoride concentration in your local drinking water, you can review your community's annual water quality report, also known as a Consumer Confidence Report, which provides information on fluoride and other water quality measurements. Go to EPA CCR website: epa.gov/ccr .

The important principle to remember is that the dose matters. Like many substances, including vitamins, minerals, and even water itself, fluoride is beneficial at appropriate levels but can become harmful if consumed in excessive amounts (Agency for Toxic Substances and Disease Registry, 2014).

 

Myth 2: Fluoride causes widespread toxicity, especially in children.

Truth: At the recommended concentration for community water fluoridation in the United States (approximately 0.7 mg/L), fluoride has not been shown to cause systemic toxicity in the general population (CDC, 2024a). Like many naturally occurring substances, fluoride can become harmful when exposure is much higher than recommended (Agency for Toxic Substances and Disease Registry, 2014). Long-term excessive intake may lead to dental fluorosis, a condition that affects the appearance of developing teeth, while extremely high exposures over many years can contribute to skeletal fluorosis, a rare disorder affecting bones (Cleveland Clinic, 2022).

Public water systems routinely monitor fluoride concentrations to ensure they remain within established safety guidelines (CDC, 2024c). If fluoride levels exceed regulatory limits, corrective measures are taken before the water reaches consumers.

Myth 3: Fluoride lowers IQ in everyone.

Truth: This claim often arises from studies that have been misunderstood or taken out of context.

Some scientific studies have reported associations between very high fluoride exposure, typically in regions where naturally occurring fluoride concentrations greatly exceed recommended drinking water standards and certain neurodevelopmental outcomes . These studies are important because they help scientists better understand the effects of excessive fluoride exposure (Zohoori et al., 2025). However, these findings should not be confused with community water fluoridation programs, where fluoride concentrations are carefully maintained at much lower, regulated levels. The current scientific consensus is that there is no convincing evidence that drinking water fluoridated at recommended levels reduces IQ in the general population (National Toxicology Program, 2025). Researchers continue to study fluoride exposure, as they do with many environmental chemicals, but the evidence supporting the safety of optimally fluoridated drinking water remains strong (National Toxicology Program, 2025).

Myth 4: Fluoridation is no longer necessary because we have fluoride toothpaste.

Truth: Fluoride toothpaste has dramatically improved oral health, but it has not eliminated tooth decay or the inequalities that exist in access to dental care. Community water fluoridation provides a consistent level of protection for everyone who drinks the water, regardless of age, income, or access to dental services (Zohoori et al., 2025). This is particularly important for children, older adults, and communities where regular dental care may be difficult to obtain. Water fluoridation is not a substitute for brushing, flossing, or visiting the dentist (Anderson, 2025). Instead, it works alongside these healthy habits as one component of a comprehensive approach to preventing tooth decay (Zohoori et al., 2025).

Myth 5: Fluoride has no real benefit and is outdated science.

Truth: The effectiveness of fluoride in preventing tooth decay has been studied for more than 75 years (CDC, 2024b). Numerous epidemiological studies have consistently shown lower rates of dental caries in communities with appropriately fluoridated drinking water compared with communities that do not fluoridate their water (Nascimento et al., 2025). Although dentistry has advanced considerably over the past several decades, tooth decay remains one of the most common chronic diseases worldwide. Community water fluoridation continues to be recognized as one of the most cost-effective public health strategies for reducing cavities and improving oral health across entire populations (CDC, 2024b). As science continues to evolve, and recommendations are updated as new evidence becomes available. At present, however, the best available evidence supports the conclusion that community water fluoridation, when maintained at recommended levels, remains a safe and effective way to help prevent tooth decay (CDC, 2024b).

What You Should Know

Community water fluoridation is not a perfect public health intervention, nor is it free from scientific discussion or controversy. Like many topics in public health, researchers continue to ask important questions as new evidence becomes available. Today, the conversation is less about whether fluoride helps prevent tooth decay, that benefit is well established, and more about how to optimize its use.

Current research focuses on questions such as: What is the ideal level of fluoride in drinking water? How should we account for fluoride from multiple sources, including toothpaste, mouth rinses, foods, and beverages? And how do we maximize the benefits while minimizing the risk of excessive exposure?

To answer these questions, scientists rely on one of the most fundamental principles in pharmacology and toxicology: the dose-response relationship. This principle reminds us that virtually every substance can be either beneficial or harmful depending on the amount of exposure. The same concept applies to fluoride. Understanding dose and exposure helps explain why fluoride can protect teeth at recommended levels while excessive amounts may increase the risk of unwanted effects.

Rather than viewing fluoride as simply "safe" or "dangerous," it is more helpful to think about it in terms of exposure, dose, and context. This evidence-based approach allows us to separate legitimate scientific questions from misinformation and oversimplified claims that often circulate online.

Conclusion

Community water fluoridation is best understood as a population-level strategy for preventing tooth decay. When fluoride concentrations are carefully maintained within recommended guidelines, it provides a safe, effective, and affordable way to improve oral health across entire communities. The strongest claims, whether portraying fluoride as completely harmless under all circumstances or as inherently dangerous, often overlook the complexity of the science. As with many public health interventions, the best answers are found not at the extremes but through careful evaluation of the available evidence, thoughtful risk-benefit analysis, and an understanding of dose-response relationships. Scientific research on fluoride continues, and recommendations may evolve as new evidence emerges. Based on the current body of evidence, however, community water fluoridation remains one of the most effective and cost-efficient public health measures for reducing tooth decay and improving oral health in the United States and many other parts of the world.

Key Takeaways

·       Fluoride occurs naturally. It is found in rocks, soil, groundwater, and many foods.

·       Dose matters. Fluoride is beneficial at recommended levels but excessive exposure over long periods can increase the risk of adverse effects.

·       Community water fluoridation in the United States is recommended at approximately 0.7 mg/L, a level that maximizes protection against tooth decay while minimizing the risk of dental fluorosis.

·       Fluoride is eliminated from the body relatively quickly. The circulating fluoride in blood has a biological half-life of approximately 3–7 hours, and about half of the absorbed fluoride is excreted in urine within 24 hours. Most of the remainder is incorporated into bones and teeth, where it can remain for years as part of normal bone remodeling.

·       Dental fluorosis is primarily associated with excessive fluoride exposure during tooth development in early childhood and is usually mild at current recommended fluoride levels.

·       Skeletal fluorosis is a rare condition that develops only after prolonged exposure to fluoride concentrations that are substantially higher than those used in community water fluoridation.

·       The science continues to evolve. Researchers continue to study fluoride exposure, but the current evidence supports the safety and effectiveness of community water fluoridation when maintained at recommended levels.

 

References

Agency for Toxic Substances and Disease Registry. (2014, May 6). Fluorides, Hydrogen Fluoride, and Fluorine | Public Health Statement | ATSDR. Wwwn.Cdc.Gov. https://wwwn.cdc.gov/TSP/PHS/PHS.aspx?phsid=210&toxid=38

Anderson, O. (2025). You Ask, We Answer: Is water fluoridation effective in helping to prevent tooth decay? [Review of You Ask, We Answer: Is water fluoridation effective in helping to prevent tooth decay?]. Https://Adanews.Ada.Org/. https://adanews.ada.org/ada-news/2025/october/you-ask-we-answer-is-water-fluoridation-effective-in-helping-to-prevent-tooth-decay/

Aoun, A., Darwiche, F., Hayek, S. Al, & Doumit, J. (2018). The Fluoride Debate: The Pros and Cons of Fluoridation. Preventive Nutrition and Food Science, 23(3), 171–180. https://doi.org/10.3746/pnf.2018.23.3.171

CDC. (2024a, May 15). About Community Water Fluoridation. CDC. https://www.cdc.gov/fluoridation/about/index.html

CDC. (2024b, May 23). Community Water Fluoridation Frequently Asked Questions. Community Water Fluoridation. https://www.cdc.gov/fluoridation/faq/index.html

CDC. (2024c, May 23). Water Fluoridation Data and Statistics. Community Water Fluoridation. https://www.cdc.gov/fluoridation/php/statistics/index.html

CDC. (2024d, May 9). About Fluoride. Oral Health. https://www.cdc.gov/oral-health/prevention/about-fluoride.html

Cleveland Clinic. (2022, June 8). Fluorosis: What It Is, Causes & Treatment. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/23227-fluorosis

Flowers, P., Bott, S., Carpenetti, D., Eklund, A., El-Giar, E., Frantz, D., Hooker, P., Kaminski, G., Look, J., Martinez, C., Milliken, T., Moravec, V., Powell, J. D, Sorensen, T., Soult, A., Theopold, K., Langley, R., Robinson, W. R., & Blaser, M. (2019). Chemistry 2e. Openstax, Xanedu. https://openstax.org/details/books/chemistry-2e

Fuge, R. (2019). Fluorine in the environment, a review of its sources and geochemistry [Review of Fluorine in the environment, a review of its sources and geochemistry]. Applied Geochemistry, 100(100), 393–406. https://doi.org/10.1016/j.apgeochem.2018.12.016

Nascimento, C. F. D., L.A.D.S. Gindri, Oliveira, M. N. de, L.R. Paranhos, & Hugo, F. N. (2025). Water Fluoridation and Dental Caries Prevention Globally: A Systematic Review and Meta-Analysis [Review of Water Fluoridation and Dental Caries Prevention Globally: A Systematic Review and Meta-Analysis]. JDR Clinical & Translational Research, 11(2). https://doi.org/10.1177/23800844251342804

National Institutes of Health. (2024). Community Water Fluoridation [Review of Community Water Fluoridation]. Nih.Gov. https://www.nidcr.nih.gov/health-info/fluoride/community-water-fluoridation

National Toxicology Program. (2025, April 23). Fluoride Exposure: Neurodevelopment and Cognition [Review of Fluoride Exposure: Neurodevelopment and Cognition]. United States Department of Health and Human Services. https://ntp.niehs.nih.gov/research/assessments/noncancer/completed/fluoride

Zohoori, F. V., Kumah, E. A., Kronic, J., Drinnan, M., & Morris, A. J. (2025). Public health impacts of water fluorides: Current evidence from a rapid systematic review [Review of Public health impacts of water fluorides: Current evidence from a rapid systematic review]. Advances in Nutrition, 16(12), 100547. https://doi.org/10.1016/j.advnut.2025.100547