Worried about fluoride in tap water? Experts answer your questions

Dental experts have praised new plans to add the mineral fluoride to the drinking water of an estimated 1.6 million people living in the North East in the biggest expansion of water fluoridation in the past four decades.

Greenlighted by government ministers as part of the NHS Dental Recovery Plan, the intention is to improve the oral health of some of the most deprived communities in the UK.

David Conway, a professor of dental public health at the University of Glasgow, told The Telegraph that he feels the move is crucial for reducing inequalities in oral health particularly given the current strain on dental surgeries.

There are believed to be around 7.3 million people in the UK who currently live in areas where fluoride is currently added to tap water, but there has been little expansion of the scheme since the 1980s.

 “The state of access to dentistry across the UK is really challenging,” says Conway. “Our response has to not only be about the service, which is obviously a priority to ensure people can access the treatment they urgently need, but to take a bit of a longer-term view and to think about prevention. Fluoride is a key part of the preventive strategy for reducing dental caries, improving oral health, and reducing demand for care.”

 It is a surprisingly emotive topic dividing public opinion – and not all scientists feel so positively about the news. They cite fears that, in reality, water fluoridation will only offer limited benefits to oral health, combined with concerns that in some cases, it may be driving harm.

“I find the whole proposal horrifying,” says Stephen Peckham, a professor of health policy at the University of Kent. “There are increasingly important red flags of adverse effects which cannot simply be dismissed.”  

 So why are dental experts so convinced that fluoride represents the way forward for the health of our teeth, while others like Peckham are concerned?

Why is fluoride being added to the drinking water?

The main rationale behind supplementing drinking water with fluoride is to strengthen the enamel in teeth and provide greater protection against dental caries, one of the oldest and most common diseases found in humans.

 Dental caries is a chronic infectious disease which is driven by tooth-adherent bacteria which take over the oral cavity and metabolise sugar in the diet to produce acid. Over time, this results in a slow demineralisation of the tooth structure, causing pain and decay.

“The primary risk factor for dental caries is the high amounts of sugar in the diet,” says Conway. “Fluoride interrupts that process of demineralisation and encourages strengthening of the enamel surface.”

The prevalence of dental caries in children in the UK has already reduced dramatically over the past 50 years, something which is typically attributed to the introduction of fluoride-containing toothpaste in the early 1970s. In Scotland, all nurseries and primary schools implement a supervised tooth-brushing programme with fluoride-supplemented toothpaste for three–to-five-year-olds.

However, dental experts feel that more still needs to be done to protect those living in areas of lower socioeconomic status, who are more likely to develop dental caries as a consequence of a poorer diet. Statistics from the Oral Health Foundation show that nearly a third of adults in the UK suffer from tooth decay and 74 per cent have needed to have a tooth extracted. Research from the UK government has found that nearly a quarter of five year olds still experience dental caries.

Conway strongly advocates for both the use of fluoride-supplemented toothpaste and water fluoridation schemes as a way of improving oral health. “The optimal level that we would use in drinking water would be one part per million fluoride while for comparison toothpaste strength is 1,450 parts per million fluoride,” he says. “But fluoride alone is not sufficient, controlling sugar intake is also part of the story.”

Why is the government adding more fluoride to our water?  

In 2022, a government report from the Water Fluoridation and Health Monitoring Working Group, on behalf of the Secretary of State for Health and Social Care, analysed the relative health of people living in areas of England with different concentrations of fluoride in their drinking water supply.

The report concluded that five-year-olds in areas with a fluoridation scheme were less likely to experience dental caries, while children and young people were less likely to be admitted to hospital to have teeth removed. Those living in the most deprived parts of the country appeared to benefit the most from a scheme.

It is believed that this report has influenced the current decision to implement water fluoridation in the North East. “Water fluoridation came back on the agenda in 2021,” says Conway. “The four chief medical officers of the UK began making the case that we should be progressing that.”

Should we be concerned about fluoride in our water?

Despite the government report, Peckham is not convinced that water fluoridation would significantly reduce oral health inequalities, and questions whether it is really necessary in addition to existing fluoride-supplemented toothpaste. He points to Scotland, where there is no water fluoridation scheme in place but steady improvements in oral health have been achieved through programmes such as Childsmile in which dentists apply very small amounts of highly concentrated fluoride varnish to the teeth of children.

A 2022 study published by the National Institute for Health and Care Research (NIHR), evaluated a water fluoridation scheme in Cumbria in two cohorts of children, one aged zero to five and another of five to 11-year-olds. While modest benefits were seen in the youngest cohort, it appears to make very little difference in preventing dental caries in the older children.

In January, researchers at the University of Manchester published the largest ever study of the effects of water fluoridation across 6.4 million people in the UK between 2010 and 2020. It concluded that while this had resulted in marginal savings for the NHS, the health benefits would not have been meaningful for individuals. Furthermore, it predicted that future water fluoridation schemes would not be guaranteed to yield cost savings because overall, the teeth of the current generation of children are in better condition than their parents, and they may not need as much dental treatment as they reach adulthood.

“Both of these studies are high quality and have highly respected authors,” says Peckham. “Claims about the enormous benefit of water fluoridation and that it reduces inequalities are not supported by the evidence, and this has been a consistent message from studies since 2000.”

Are there health risks?

Concerns about the potential health risks that might arise from water fluoridation have been raised across the political spectrum, from the Conservative peer Lord Reay to the Green Party.

In a Tweet earlier this week, the United States presidential candidate Robert F Kennedy Jr. branded fluoride a “neurotoxin” and claimed that if he became president, he would order the Centers for Disease Control and Prevention (CDC) public health agency to remove it from drinking water.

Right now, a court case is taking place in San Francisco over whether the US Environmental Protection Agency should ban water fluoridation to protect foetuses and children from the risk of neurodevelopmental problems. While the CDC describes fluoridation, which began in 1946 in the US, as one of the 10 great public health achievements of the 20^th century, studies in lab animals and humans have long hinted that high levels may impact brain development.

“The Environmental Protection Agency has undertaken a detailed review of the neurological impact of fluoride, a draft of which has only come to light due to this ongoing legal case,” says Peckham. “This review, conducted by the federal government’s National Toxicology Program, supports the view that fluoride at levels consumed in water fluoridation schemes, has adverse effects. There are increasingly a number of studies demonstrating reductions in IQ.”

Conway disagrees, arguing that there is no good evidence for any adverse consequences of water fluoridation other than fluorosis, a condition caused by overexposure to fluoride in the early years of life, resulting in white or brown speckles on teeth. “This can be readily treated by dentists,” he says.

However Peckham is also concerned about the impact of water fluoridation on the thyroid. In 2015, he published a study indicating that it could result in an underactive thyroid, and a new study from researchers in Canada which was published in January, also connected fluoride exposure to thyroid problems.

“Water fluoridation is treated as a sacred cow by the dental profession despite the poor evidence and cannot be criticised,” he says. “I can vouch for how powerful a lobby this can be and what pressure can be applied. Any good assessment of the evidence makes it clear that water fluoridation as the answer to children’s dental caries is misplaced. We know that reducing sugar intake is what we really need.”