With water fluoridation of drinking water under the spotlight in the US, we look at why some countries choose not to add the mineral to supplies while others have repealed the practice.

Opposition to fluoride is spreading. The mineral was there, in the recent "Make America Healthy Again" report on childhood disease, among a long list of factors blamed for a crisis of chronic disease afflicting children in the United States.

Wellness influencer Calley Means, who is now an adviser to the US government, has called drinking water fluoridation an "attack on lower income kids" and suggested that parents should throw out their children's toothpaste if they find it contains fluoride. His views on fluoride appear to align with those of Robert F Kennedy Jr, the US Health and Human Services Secretary. His sister, Casey Means, is also Donald Trump's nominee to serve as the US Surgeon General.

Yet, ever since scientists noticed that people had lower rates of tooth decay in areas with naturally higher levels of fluoride in the water, in some areas it has been added to drinking water in an effort to improve dental health.

At the end of March 2025, however, Utah became the first US state to ban the use of fluoride in the public water supply. In early May, Florida Governor Ron DeSantis signed a bill into law that bans "certain additives" in the water system, which would include fluoride – ending a practice that dates back to 1949 in the state. And in April, Kennedy Jr announced that he would direct the US Centers for Disease Control and Prevention to recommend against fluoridating water and the Environmental Protection Agency is holding an urgent review of the scientific evidence on any potential health risks of adding fluoride to water.

Many scientists consider community water fluoridation to be a public health victory – one that has resulted in lower rates of dental decay and better oral health overall for millions of people worldwide. Some recent reviews of the evidence have suggested that the beneficial effects may not be as pronounced as they were 50 years ago before fluoride in toothpaste was widely available – although they still find a benefit. A 2016 review of fluoridation in Australia, for example, found that water fluoridation reduced dental decay in children's first teeth by about 35%, while a 2022 health monitoring report for England also found that it reduced tooth decay in 3-year-olds by 35%. This effect is greatest for children living in more deprived areas, who may have less access to dental care or even to regular tooth-brushing with fluoride at all.

First introduced in the city of Grand Rapids in the US state of Michigan in 1945, community water fluoridation today is practised in about 25 countries, including parts of the UK, Spain, Ireland, Singapore, Malaysia and Brazil. In total, fluoridated drinking water reaches more than 400 million people worldwide.

In the US, approximately 63% of the population – 209 million people – receive fluoridated water. For nearly 12 million of those people, the mineral is not added, but occurs naturally in the water supply.

One argument put forward against fluoridation is that some studies have linked fluoride exposure to slightly lower average IQ scores in children, as outlined in a 2025 meta-analysis – a type of study that combines the results of several other studies – of the research. Detailed reviews of the evidence, however, have concluded that this association occurs when the levels of fluoride are twice the recommended limit in the US and scientists have found significant methodological and statistical issues with the 2025 meta-analysis.

Those opposed to artificial drinking water fluoridation also

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