Celebrating 70 years of water fluoridation

Adding fluoride to tap water to prevent tooth decay is one of our greatest public health achievements, and it is important that we continue to promote and expand coverage to improve oral health.

Today marks the 70^th anniversary of the commencement of water fluoridation in Australia at the small town of Beaconsfield in the northeast of Tasmania. From humble beginnings, this public health measure to adjust the naturally occurring amount of fluoride in the drinking water supply has been instrumental in improving oral health across Australia. 

The impetus for water fluoridation came in part from an understanding of the poor oral health of military recruits during World War Two, and the discovery of the preventive benefits of fluoride in the USA in the 1940s. Following the successful implementation in Beaconsfield, water fluoridation spread to Hobart (1964), Canberra (1964), Sydney (1968), Perth (1968), Adelaide (1971), Darwin (1972) and Melbourne (1977). Brisbane notably delayed the introduction of water fluoridation until 2008, and Queensland continues to have poor coverage. 

The evidence overwhelmingly supports water fluoridation as being a safe, effective and ethical way to help reduce tooth decay across the population, and importantly helps to tackle socioeconomic inequalities in oral health. One of the main benefits of water fluoridation is that it is extremely cost-effective - for every dollar spent on water fluoridation, the health system saves between $7 and $18 in avoided dental treatment costs for dental caries, amounting to $1 billion in avoided health care and related costs over the past 25 years in Victoria alone. Australia’s National Oral Health Plan 2015-24 has an ambitious goal to extend access to the benefits of water fluoridation to communities with populations greater than 1000. However, recent research in Victoria highlighted that one third of these regional and rural communities did not have access to fluoridated drinking water, and this is true for many regional communities around Australia. 

Indeed, tooth decay remains one of the most prevalent health problems and the leading cause of preventable hospitalisation in Australian children. One in three children suffer from tooth decay by the age of 5-6 years, and it is not uncommon for thousands of young children to have teeth extracted as a result of decay. These problems are exacerbated in rural areas that often do not have access to water fluoridation and where there are generally fewer dental practitioners impacting on the ability to deliver preventive care. 

Water fluoridation myths and conspiracies (and why they are wrong). 

Despite evidence over more than 70 years demonstrating both the safety and effectiveness of water fluoridation, many myths and conspiracies persist, hampering efforts to expand coverage in areas of need. It’s important that we continue to combat this misinformation to ensure that Australians continue to benefit from this important public health measure. 

Fluoride isn’t natural 

Fluoride is found in all natural water supplies at some concentration. This is because fluoride (usually in the form of calcium fluoride) is a naturally occurring substance found in many rocks which then leaches into ground and surface water. Ocean water contains fluoride at around 1 part per million, about the same as levels of fluoridated drinking water in Australia (which is why sharks have such great teeth). 

The natural level of fluoride in the water varies depending on the type of water and the type of rocks and minerals it’s in contact with. There are many places in Australia where fluoride occurs naturally in the water supply at optimum levels to maintain good dental health – places like Portland and Port Fairy in Victoria have naturally occurring fluoride in their water at a level optimal for dental health. 

The three main fluoride compounds generally used to fluoridate water are: sodium fluoride, hydrofluorosilicic acid (hexafluorosilicic acid) and sodium silicofluoride. All these fully mix (dissociate) in water, resulting in the availability of fluoride ions to prevent tooth decay. Regardless of original source (whether it is natural or artificial), the end result is the same – fluoride ions in the water. 

Water fluoridated doesn’t prevent tooth decay 

Study after study dating back to the 1940s continues to demonstrate that water fluoridation prevents tooth decay. The initial discovery came about when dental researchers were trying to figure out why some towns had much lower levels of tooth decay than others, and they were able to measure differences in the fluoride levels of the drinking water. 

Following this exciting discovery, a study commenced that involved the artificial fluoridation of water supplies in one community, and comparing the tooth decay rates to a neighbouring community with no fluoride. The study had to be discontinued after six years because the benefits to the children in the fluoridated community were so obvious it was deemed unethical to not provide the benefits to all the children, and so the control community water supply was also fluoridated. 

The National Health and Medical Research Council (NHMRC) published an extensive update of the evidence on the impact of fluoridated water on human health in 2017. This showed that children and teenagers who had lived in areas with water fluoridation had 26-44% fewer teeth or surfaces affected by decay, and adults had 27% less tooth decay. My own research* showed a consistent 23-25% reduction in tooth decay in a subset of young Australian adults in 1996, 2002/3 and 2008. Of course there are a multitude of factors likely to influence the impact across populations, including diet, access to dental care, and the amount of tap water people drink. But the evidence is pretty clear that water fluoridation works. 

Water fluoridation causes cancer 

Cancer, Down syndrome, cognitive problems, lowered intelligence, hip fracture, chronic kidney disease, kidney stones, hardening of the arteries, high blood pressure, low birth weight, premature death from any cause, musculoskeletal pain, osteoporosis, skeletal fluorosis (extra bone fluoride), thyroid problems. You name a health problem, and chances are there will be someone claiming that it is caused by water fluoridation. 

Again, the evidence is pretty clear – the NHMRC found there was no reliable evidence to suggest water fluoridation at current levels in Australia of 0.6-1.1 parts per million was associated with any of those problems. 

The studies that claim to show adverse health effects are generally in areas where there are high levels of fluoride occurring naturally in the water supply – generally more than 2-10 parts per million or more (up to 10 times levels found in Australian water). These studies often have methodological issues, with small sample sizes and lack of controlling for other factors that may be associated with adverse health outcomes. 

There is one adverse outcome associated with fluoridated water – dental fluorosis, or the hypomineralisation of the tooth enamel. This is caused by the ingestion of too much fluoride (from any source) whilst teeth are forming during early childhood, and is most often linked to excessive swallowing of toothpaste. When dental fluorosis occurs, it is mostly very mild or mild, and does not affect the either the function or appearance of the teeth. Moderate dental fluorosis is very uncommon, and tends to include brown patches on the tooth surface. Severe dental fluorosis is rare in Australia. 

Adding fluoride to tap water to prevent tooth decay is one of our greatest public health achievements, and it is important that governments continue to promote and expand coverage to improve oral health. 

* Not a Google search but real research. I conducted 3 large studies investigating association between water fluoridation and dental caries in Australian Army recruits between 1996 and 2008.