Fluoridation of drinking water is a public health success story – why does the debate continue?

The addition of fluoride to drinking water has improved dental health worldwide for over 70 years but is still hindered by misinformation; let’s look at the evidence.

In the recent past, it was not uncommon for people to lose the majority, or even all, of their adult teeth before reaching old age. Today, many of us can expect to keep our teeth for life, with most cavities hopefully being relatively minor and easily treated. This change in dental fortunes is, in no small part, due to the addition of fluoride to drinking water (or to milk or salt in many European and South American countries).

Despite decades of evidence of its safe use, many still oppose fluoridation. For example, the United States’ incoming “health czar,” Robert F Kennedy Jr, has called for its removal from drinking water. Conversely, the Australian Medical Association Queensland recently urged Queensland councils to reintroduce fluoride to water supplies amid the rising incidence of oral disease.

What is fluoride and how does it help our teeth?

Fluoride is a natural substance found in rocks, water sources, soils and plants. In our mouths, it helps prevent cavities by reacting with hydroxyapatite, a component of tooth enamel, to form fluorapatite. This is far more resistant to decay, making teeth more resistant to acids from bacteria in your mouth.

The story of water fluoridation is one of determination. In 1901, a dentist called Frederick McKay started a practice in Colorado Springs, USA. He noticed that children in the area had brown stains on their teeth, which today we would recognise as dental fluorosis. He also noticed that teeth affected by this condition generally had less decay. McKay and others worked for decades to understand the cause, which was eventually traced to higher levels of fluoride in the local water. In 1945, Grand Rapids, Michigan, became the first city in the world to fluoridate its drinking water. The cavity rate among children born in the town after fluoridation dropped by more than 60%.

The first place to fluoridate water in Australia was Beaconsfield, Tasmania, in 1953, closely followed by Yass, NSW, in 1956. Today, around 90% of Australians can access fluoridated water at levels of between 0.6 to 1.1 mg/L. This is estimated to have reduced tooth decay in Australia by 26–44%.

There are, however, different policies in different states and territories. About 28% of Queenslanders do not have fluoridated water, for example, and the majority of those who do are in the urban southeast of the state. This uneven distribution originates from a 2012 decision by the Queensland state government to transfer responsibility for water fluoridation to local authorities; a decision that many would like to see reversed.

The benefits of fluoridation

Besides reducing the pain and stress of dental decay, fluoridation also makes sound economic sense. Research from the USA showed that for every US$ spent on fluoridation, communities save about US$20 in dental treatment costs due to fewer fillings, extractions and emergency visits.

Fluoridation is also a simple and socially equitable approach since you don’t have to go to the dentist or take a pill to get the benefit; all you need to do is drink water. This is especially beneficial to disadvantaged or remote communities who may not have access to regular dental care. Even in the big cities, many people can’t afford regular check-ups, and dentistry isn’t included in Medicare.

The concerns

There has always been opposition to fluoridation. Some feel it is government overreach since we can’t easily avoid drinking tap water.

Many critics cite a 2019 study that claimed fluoride affected children’s IQs. However, just because something is published does not mean it is good science. The research was widely criticised at the time. A 2024 paper also detailed serious weaknesses in the study design.

Multiple reviews of high quality studies from many different countries have found no evidence of harm. One study followed people over 30 years, testing their IQs at various ages, and found no link between fluoride levels and IQ scores.

The dose makes the poison

It’s not unreasonable to want to know what’s in our drinking water  and to ensure it is safe. But discussions about toxicity are meaningless without context.

Yes, excessive fluoride intake can have harmful effects, such as weakened bones (skeletal fluorosis). But the key word is “excessive”.

Anything can be toxic if the dose is high enough – even water. The amount of fluoride needed to cause skeletal fluorosis is orders of magnitude higher than what you get in drinking water.

One might ask, why not avoid the risk just to be safe? But, as several recent cases demonstrate, this argument ignores the risks of not fluoridating water.

The introduction of nationwide water fluoridation in Israel in 2002 significantly reduced children’s dental issues. When fluoridation was discontinued in 2014, dental problems increased again – despite the government introducing free dental care for children in 2010.

The Canadian city of Calgary removed fluoride from drinking water in 2011. Seven to eight years later, dental cavities in children were significantly higher in Calgary than in nearby Edmonton, where fluoride was not removed.

In 2015, Buffalo, New York, removed fluoride from its water supply. Dental problems increased so much that parents sued the city for harming their children.

Conclusion

Governments are not perfect, but why would they add something to the water if they believed it to be harmful? It would not benefit them, and they drink the same water.

Dentists are also accused of somehow being in with “big fluoride”. But dentists make their money from fixing your teeth. Fluoride reduces cavities, so if dentists just wanted money, they would surely be keen to remove fluoride from water – not add it.

While science can only inform rather than drive policy, we should consider if health authorities are keen to damage our health for some unknown reason. Or are they simply in favour of a way to improve public health with decades of evidence of safe use?

Professor Oliver AH Jones is a professor of chemistry at RMIT University in Melbourne and an internationally recognised expert in analytical and environmental chemistry.

The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.  

The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated. 

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