Utah has become the first US state to ban fluoride from all public drinking water, backing controversial plans from Robert F Kennedy Jr. 

The law was signed Thursday by Governor Spencer Cox and will go into effect May 7 for all public drinking water systems. 

Fluoride was added to US water in 1940s after scientists found that people with higher levels of the mineral had fewer cavities. 

According to the latest CDC data, nearly half of Utah residents with public water access drink fluoridated water, while half does not.

Gov Cox said Thursday that between those two groups, ‘you think you would see drastically different outcomes. We haven’t.’

Health Secretary RFK Jr has also long called for the mineral to be stripped from America’s water supply, claiming it causes bone cancer, IQ loss, and neurodevelopmental disorders like autism. 

Last year, Florida became the first state to recommend removing fluoride from water systems over Kennedy’s claims. 

The research on fluoride’s potential health effects is mixed, and many experts have claimed the evidence is unclear and the dental benefits of fluoride outweight potential risks. 

Utah has become the first state to ban fluoride from public water systems beginning May 7. Department of Health and Human Services Secretary Robert F Kennedy Jr (pictured here) is one of the main opponents of the mineral, arguing it can cause IQ loss, cancer, and neurodevelopmental disorders like autism (file photo)

Fluoride was added to US water in 1940s after scientists found that people with higher levels of the mineral had fewer cavities. Nearly half of Utah’s residents with public water access drink fluoridated water (stock image)

Fluoride makes teeth more resistant to substances that can wear down enamel – like citrus, sugary foods and carbonated beverages – which thin and weaken teeth and make them more sensitive. 

This, in turn, prevents cavities and other dental infections. 

And roughly 72 percent of Americans that use public water supplies drink water with fluoride added to it.  

Since national fluoridation came around, rates of dental problems in children have declined, and the program is praised by dentists.

For nearly as long though, critics have been raising concerns about the safety of fluoride.

In a November post on X, RFK Jr said: ‘Fluoride is an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders, and thyroid disease.’

Dr Paul Offit, a physician in the Division of Infectious Diseases at Children’s Hospital of Philadelphia, told NPR that Kennedy’s claims are misleading.

Dr Offit said: ‘Fluoride has been well tested. It clearly and definitively decreases cavities, and is not associated with any clear evidence of the chronic diseases mentioned in that tweet’.

Fluoride is the active ingredient in most toothpastes, and 13million children participate in fluoride mouth rinse programs, which has students rinse their mouths with a sodium fluoride mouth wash during the school day, according to the NIH.

In 2015, the US Department of Health and Human Services Agency reviewed the levels of fluoride added to water and decided to standardize the national recommendation.

Older recommendations had allowed different concentrations based on the local air temperature, but the 2015 update set the limit at 0.7 mg of fluoride per liter of water.

This re-evaluation didn’t come about because of concerns about health impacts, however, but instead it was meant to address concerns that higher levels of fluoride could cause white patches to develop on teeth.

But critics point to other countries that have eliminated the substance from their water supply.

Germany, the Netherlands and Sweden have discontinued fluoride plans in favor of other national dental programs. They have not banned fluoride outright, and in Germany, there is a history of adding fluoride to salt.

Opponents of fluoridation note that adding it to water might have been necessary for people in the 1900s who didn’t have access to fluoride in dental products, but that in the modern world, people get enough fluoride already – and excess exposure could be detrimental

This map, from 2020, shows fluoride levels in untreated groundwater supplies. Areas marked with a yellow or red dot have more than twice the level of fluoride in groundwater than recommended

The above shows the most recently known levels of fluoride in US county water systems

Most recently, in the US, a study from the National Toxicology Program found there was a link between high levels of fluoride exposure and lower IQ.

The levels of fluoride they included in the study were two times higher than the federal limit for drinking water.

The authors wrote this didn’t prove definitively that fluoride causes lower IQ, and noted their study just establishes a pattern between the two.

The authors said: ‘Many substances are healthy and beneficial when taken in small doses but may cause harm at high doses. More research is needed to better understand if there are health risks associated with low fluoride exposures.’

Dr Scott Tomar, a public health dentist and oral epidemiologist at the University of Illinois Chicago, told The New York Times the Utah law and other potential bans could lead to more dental problems throughout the country, especially in poorer areas.

He said: ‘The benefits of community water fluoridation are most pronounced in low income communities — communities that often have the least access to dental care and to other sources of fluoride.’