THE positive effects of fluoride on dental health were first noted in Colorado Springs in the early 1900s.
Frederick McKay, a young dentist, noted that those who lived there had very low rates of tooth decay, although they did have higher rates of a condition called fluorosis, characterised by a brown staining of their teeth.
Analysis of the local water supply showed that fluoride levels there exceeded 2mg per litre, a relatively high concentration compared to other areas. However, the observed resistance to tooth decay got dentists wondering whether it would be possible to harness the positive effects of fluoride (reduced decay) without incurring the brown discolouration effect, by simply adding fluoride to the water supply in concentrations less than 2mg/l.
Subsequent analyses clearly showed that addition of fluoride to drinking water at 1 mg/l achieved just that, and, based on this evidence, several countries including Ireland moved to fluoridate water on a statutory basis.
Fluoridation was not initially welcomed in Ireland. One woman, Gladys Ryan, took her case to the High Court and then to the Supreme Court. In a lengthy case, the legislation for fluoridation which had originally been signed into law in Dec 1960 finally came into effect on Jul 15, 1964 when the case was dismissed.
The nationwide implementation of fluoridation in the years that followed heralded a dramatic improvement in the dental health of the population, a benefit which persists today. Studies showed reduced rates of tooth decay among people in the Republic of Ireland compared to those in the North where fluoridation was not introduced. However, despite clear evidence of its benefits, controversy continues.
It has been claimed that people exposed to fluoride in their drinking water are at greater risk of osteoporosis and cancer. Neither of these claims stand up to scrutiny. In fact, the literature shows that there’s absolutely no increased risk of either osteoporotic bone change or cancer at water fluoridation levels less than 2 mg/l.
To put this in context, Ireland fluoridates its water at a level of 0.7mg/l. The only adverse effect of fluoridation at this level is mild dental fluorosis, which occurs with greater frequency in children living in fluoridated water areas, including Ireland. While this may be a cosmetic concern, most research shows that it is not “aesthetically objectionable” and is harmless to the structural integrity of the teeth.
The most recent controversy concerned a suggested increased risk of fluorosis among infants fed formula — milk made with fluoridated tap water. Again, even if this did occur, there is no robust evidence that it would have any long-term adverse effect on the child’s dental or general health.
It’s important that these unsubstantiated adverse effects are discussed in the correct context. While most of us think about dental health as a purely aesthetic issue, this is far from the truth.
Dental decay and tooth loss are associated with significantly increased risk of death after surgery, as the exposed gums create a potential entry route for serious infection. I, like many clinicians, am in the unfortunate position of experiencing this first hand, having had post-surgical patients in my care die of such infections.
While those who assert the supposed “hazards” of water fluoridation are entitled to their opinion, the facts speak for themselves. The data shows us that water fluoridation has yielded considerable public health benefits, and that it does not present any danger to human health.
* Dr Daniel McCartney, Lecturer in Human Nutrition & Dietetics at DIT
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