My View: We should continue to support community water fluoridation
Several high-profile events in recent months raised questions about the safety and effectiveness of community water fluoridation — a public health approach to dental caries prevention that now reaches more than 400 million people worldwide, including nearly three-quarters of the U.S. population served by public water systems. However, the science behind the headlines indicates that community water fluoridation is still a safe, effective and cost-saving measure for reducing the burden of oral disease.
Much attention has been focused on the possible effect of fluoride exposure on children’s IQ, a claim that goes back decades but was highlighted by several recent publications. The National Toxicology Program, a federal interagency program headquartered in the National Institute of Environmental Health Sciences, issued a monograph on fluoride exposure and neurodevelopment1 in August 2024. Two previous iterations of that monograph were heavily criticized by an expert panel from the National Academies of Science, Engineering, and Medicine — the group chosen by NTP to serve as peer reviewers — due to serious flaws in the conduct, analysis and presentation of that review. For the final version of the monograph, NTP bypassed NASEM and chose other reviewers, but the serious limitations remained. Because of NASEM’s criticism, the NTP report excluded a meta-analysis that had been in earlier versions. The authors subsequently had that piece published as a stand-alone paper2 in January, but the NTP monograph and recent paper shared the same fundamental weakness: Of the 72 studies that assessed the association between fluoride exposure and IQ, almost three-fourths of them were judged — even by the authors — to be of low quality and high risk for bias, and almost all of the studies were from areas in countries such as China, India and Iran with very high levels of fluoride — often from coal burning and other pollution sources— and unknown contaminants in the water. A number of additional concerns about the study have been noted in an editorial published in the same journal issue.3 The quality and validity of a systematic review and meta-analysis can be no better than the quality of the studies they include.
Importantly, the NTP monograph and separately published meta-analysis found no significant association between exposure to fluoride at the levels used in community water fluoridation and children’s IQ. A more recent well-conducted prospective cohort study from Australia also found no association between water fluoridation and children’s IQ,4 nor did other recent systematic reviews on IQ and low levels of fluoride exposure.5,6 The level of fluoride used in community water fluoridation simply is not associated with changes in IQ or any other measure of neurodevelopment. The judge in the recent court case brought against the Environmental Protection Agency by an anti-fluoridation group relied heavily on the flawed NTP report, but even in that legal ruling, that judge acknowledged there was no evidence of any harm associated with the levels of fluoride used in community water fluoridation.
Some media reports suggest that community water fluoridation is not as effective at preventing tooth decay as it once was. Such reports mischaracterize the best available evidence, which continues to show a reduction in the rate of new caries lesions, even at a time of widespread use of fluoride toothpaste. Yes, we’re no longer in the days when we saw massive reductions in caries associated with the introduction of community water fluoridation, but that does not mean that water fluoridation is no longer effective. It simply means that the benefits of community water fluoridation are reduced because of the use of fluoride toothpaste and professionally applied fluorides. The 2024 Cochrane systematic review on the effectiveness of water fluoridation7 added just one new study to its 2015 report because its stringent inclusion criteria limited it to prospective cohort studies that were started before the initiation of a new fluoridation program. But even that one recent U.K. study found a reduction in the incidence rate of caries in children that was consistent with other recent studies. Studies from the United States and elsewhere indicate that water fluoridation substantially reduces socioeconomic disparities in caries incidence.
A lower caries incidence rate is still an extremely good investment for communities, with a savings of about $20 in averted treatment for every dollar spent on water fluoridation.8 As an economist once told me, the decision to provide a safe and effective public health measure for a community that not only prevents disease but also saves money is a no-brainer. That is precisely the current situation with community water fluoridation. Recent evidence from Alberta, Canada, Israel and Alaska indicate that discontinuation of community water fluoridation was associated with substantially greater caries prevalence, rates of treatment services and costs of care.9-11
Dentists obviously are focused on improving the oral health of their patients and communities, but I bristle at claims that we care only about teeth. As a dentist, educator, public health researcher, parent and grandparent, I am deeply committed to improving overall health and well-being. If I suspected that community water fluoridation endangered the neurodevelopment of members of my family or others, I would reconsider my decision to strongly support fluoridation. But in my thorough reading and interpretation of the scientific literature, such fear is completely unfounded. We can confidently assure our patients, policymakers and the public that, despite all the recent noise, water fluoridation is still a safe, effective and cost-savings measure.
Dr. Tomar is professor and associate dean for prevention and public health sciences at the University of Illinois Chicago College of Dentistry. He is a member of ADA’s National Fluoridation Advisory Committee.
REFERENCES
1. National Toxicology Program. NTP monograph on the state of the science concerning fluoride exposure and neurodevelopment and cognition: a systematic review. NTP Monogr. 2024(8). doi:10.22427/NTP-MGRAPH-8
2. Taylor KW, Eftim SE, Sibrizzi CA; et al. Fluoride exposure and children’s IQ scores: a systematic review and meta-analysis. JAMA Pediatr. Published online January 6, 2025. doi:10.1001/jamapediatrics.2024.5542
3. Levy SM. Caution needed in interpreting the evidence base on fluoride and IQ. JAMA Pediatr. Published online January 6, 2025. doi:10.1001/ jamapediatrics.2024.5539
4. Do LG, Sawyer A, John Spencer A; et al. Early childhood exposures to fluorides and cognitive neurodevelopment: a population-based longitudinal study. J Dent Res. 2024:220345241299352. doi:10.1177/00220345241299352
5. Kumar JV, Moss ME, Liu H, Fisher-Owens S. Association between low fluoride exposure and children’s intelligence: a meta-analysis relevant to community water fluoridation. Public Health. 2023;219:73-84. doi:10.1016/j. puhe.2023.03.011
6. Miranda GHN, Alvarenga MOP, Ferreira MKM; et al. A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders. Sci Rep. 2021;11(1):22659. doi:10.1038/s41598-021-99688-w
7. Iheozor-Ejiofor Z, Walsh T, Lewis SR; et al. Water fluoridation for the prevention of dental caries. Cochrane Database Syst Rev. 2024;10(10):CD010856. doi:10.1002/14651858. CD010856.pub3
8. O’Connell J, Rockell J, Ouellet J, Tomar SL, Maas W. Costs and savings associated with community water fluoridation in the United States. Health Aff (Millwood). 2016;35(12):2224-2232. doi:10.1377/hlthaff.2016.0881
9. McLaren L, Patterson SK, Faris P; et al. Fluoridation cessation and children’s dental caries: a 7-year follow-up evaluation of grade 2 schoolchildren in Calgary and Edmonton, Canada. Community Dent Oral Epidemiol. 2022;50(5):391- 403. doi:10.1111/cdoe.12685 10. Tobias G, Mordechai F, Tali C; et al. The effect of community water fluoridation cessation on children’s dental health: a national experience. Isr J Health Policy Res. 2022;11(1):4. doi:10.1186/ s13584-022-00514-z
11. Meyer J, Margaritis V, Jacob M. The impact of water fluoridation on Medicaid-eligible children and adolescents in Alaska. J Prev. 2022;43(1):111-123. doi:10.1007/s10935- 021-00656-x
