The potential fluoridation of the Tantawanglo-Kiah Water System (Candelo, Wolumla, Merimbula, Tura, Pambula, Eden, Kiah) and the Brogo – Bermagui Water System (Quaama, Cobargo, Brogo, Wallaga Lake, Bermagui) has divided the Bega Valley community.
With Bega Valley Shire Council’s decision on whether to fluoridate or not still pending, the way forward seems far from clear.
By the way, the Bega – Tathra Water System has been fluoridated since 1963.
The international anti-fluoride Fluoride Action Network (FAN) challenges the safety of fluoridation despite reassurances from peak health bodies such as the Australian Medical Association and the Australian Dental Association.
FAN cites a series of scientific studies that point to negative health effects related to fluoride. Yet the World Health Organisation cites fluoridation of water as, “the most effective public health measure for the prevention of dental decay.”
The ingredients of this debate are a potent mix of conflicting evidence, with added fear, and a rather large ethical grey area.
It’s murky and hard to navigate.
Yet if you can familiarise yourself with this tricky landscape, you can start to make sense of the different perspectives people have on this issue, and perhaps take some of the fear out of the equation.
It turns out that scientific studies, the foundation stones of public health debate, are not always as rock solid as they seem.
While the fluoride debate touches on personal choice, welfare, and economics; scientific studies are a central part of pro and anti-fluoride argument.
A body of studies has been cited by the Fluoride Action Network pointing to potential effects of fluoride such as reduced IQ in children, obesity, and even cancer.
The Australian Medical Association claims that there is no appreciable link between fluoridation and these side effects.
But with so much at stake, how do you navigate the conflicting “evidence” that we’re finding?
Where better to begin than Google Scholar?! Google’s search engine for published academic studies. What happens when you search for “fluoride and IQ”?
Looking through the studies that have linked fluoride to lower IQ in children, one thing stands out – most studies that popped up didn’t test for other factors that could affect IQ.
Many studies were from China, India, or Mongolia, and compared towns that fluoridated water supplies with those that didn’t.
However, they didn’t check for other differences between the towns – levels of poverty, nutrition, potential lead and arsenic poisoning, all of which can affect the IQ of children.
This is like blaming weight gain on exercise, without considering diet.
These studies simply don’t meet the criteria needed to inform sound decision-making, yet they are published online alongside studies of higher quality.
Twenty low-quality studies that link lower IQ and fluoride, alongside only one quality study that finds no link, can look like strength in numbers and cast the wrong impression.
Assessing evidence doesn’t work like that. It’s not like voting. One study is not necessarily worth the same as another.
The problem is that scientific investigations can be carried out and published (particularly online) by any scientist, from any organisation. Most are carried out with noble intentions, but even noble intentions can be fed by bias – if you’re passionate about a cause, or feel that you’ve found an important link, established scientific practices might fall by the wayside.
Dr Andrew Wakefield’s study linking autism with vaccination is a famous example.
Dr Wakefield and his colleagues felt that they’d found an important link after reviewing the cases of eight people who’d been diagnosed with autism within a month of receiving the Measles Mumps Rubella (MMR) vaccine.
The investigation was found to be riddled with problems; their medical assessments and analysis of results were described as incomplete and biased.
Much of the criticism of Dr Wakefield’s study suggested it ignored statistical significance.
Given that 50,000 children per month were vaccinated with MMR in England at the time, eight presentations of autism were not enough to establish a link.
Statistical significance is needed for a scientific result to have meaning. Where health is concerned, this usually means two things – that a lot of people were tested and the results were strong enough to discount coincidence and other confounding factors, such as nutrition and lead in the IQ example.
Dr Wakefield’s study was discredited, and wide scale, high-quality studies were carried out that found no link between autism and vaccination. But his study was already fuelling the fears of parents across the globe.
When something appears to threaten the health of children, it can achieve notoriety.
It’s important to carefully examine the information you are given or find yourself, but how do you sift through the jargon, the publications, the conflicting evidence?
Putting your fear aside, how do you know what and who to trust?
Dr Will Grant of the Australian National University’s Centre for the Public Awareness of Science says that it’s almost impossible for one person to do this alone.
“While I’d love to say that I have the capacity to truthfully assess the veracity and rigour of all research that’s available online, I simply don’t have that capacity. In fact, no one does,” he says.
“Instead we’re all forced to use the decision-making heuristics we’ve always used, typically though not exclusively, trusting a variety of voices in our networks that know better.”
Dr Grant says that we rely on institutions to process this information for us.
“But if I’m a person who doesn’t trust these institutions – and the number of people who don’t trust the central institutions of society is growing globally – then I’m going to trust other things,” he says.
Other things might include organisations like FAN, who question the reliability of institutionalised knowledge.
The FAN website claims it, “develops and maintains the world’s most comprehensive online database on fluoride compounds.”
Despite making this claim, they don’t give you a comprehensive review of the quality of materials in their database.
The Australian Government’s National Medical Health Research Council (NHMRC), is a not-for-profit research organisation that draws on the expertise of people tied to the University of Melbourne, Royal North Shore Hospital, The Cancer Council, Alfred Hospital, and Monash University, among other organisations.
The NHMRC has released a Health Effects of Fluoridation Evidence Evaluation Report through its Clinical Trials Centre at the University of Sydney which provides an analysis of fluoride research from the last decade.
It’s worth a read for two reasons.
Firstly, it assesses the quality of studies looking into the effects of fluoridation on dental caries (decay) and other symptoms from 2006-2015, and walks through them bit by bit, weighing up their value without apparent bias.
Secondly, its conclusions reflect the “greyness” of this debate. The NHMRC says the evidence appears to indicate that Australian water fluoridation standards are safe, while also suggesting there are gaps in the research.
The recommended level of fluoridation is shown to give a 35% reduction in dental caries. This is a significant number, as it means that more than a third of dental decay can be prevented by adding fluoride to a water supply.
This has knock-on effects for the rest of a person’s health and reduces financial pressure on individuals and the economy by cutting down on visits to the dentist.
The report also shows that recommended fluoride levels can increase the incidence of tooth discolouration due to fluorosis (a chronic condition caused by excessive intake of fluoride compounds, seen as mottling of the teeth) by around 12%.
The NHRMC document also gives many of the scientific reports presented in this debate a confidence grading.
The low overall confidence grading of the reports that raise concerns about cancer and IQ perhaps take some fear out of the equation, as the ratings are low enough to discount many of the studies altogether.
The presence of studies of higher quality (ie more thorough and more reliable) have tipped the balance of evidence away from such matters of concern.
However, if the NHRMC also suggests there are gaps in the research, why can’t we just test for the negative health effects that fuel much of the fear in a robust credible way?
In Australia, people are exposed to fluoride in a number of ways, including in toothpaste and tea, and it naturally occurs in the environment around us. This means that a person’s previous exposure to fluoride is very difficult to determine. To find a bunch of people who have never been exposed to fluoride as a control group, and then to test the effects of drinking fluoridated water on them, is extremely challenging.
And as the studies linking fluoride and IQ in China, India, and Mongolia show us, these studies are problematic because there are so many other factors that can contribute to influence a person’s health.
Finding the fluoride link is not easy.
The NHMRC review gives us an indication of which way the evidence is swinging – and it’s telling us that fluoridation of our water supply will give us healthier teeth and that the only side effect of significant concern is discolouration caused by fluorosis.
It also tells us that other side effects are most likely not going to happen at Australian levels of fluoridation.
Our personal views on fluoridation are important and varied and can’t be discounted.
But it is important that we are able to critically assess the information that is given to us. If we can’t do this on our own, we can at least have a look at how others have reviewed it and make sure that we’re satisfied with how they’ve done it, which perhaps takes some of the fear out of the equation.
*Kate Burke is completing her Masters in Science Communication through the Australian National University
*Above is an edited article that originally appeared on Raisin – stories of regional science and innovation
*Ian Campbell founder of About Regional is part-time media officer for Bega Valley Shire Council