Three Simple Questions

In deciding whether fluoride is an appropriate addition to our local water supply, there are really three questions, and only three, that need to concern us:

  • What benefits accrue from fluoridating public water supplies?

  • What harm can be traced to fluoridation of public water supplies?

  • Do the benefits if any outweigh the harm if any?

Advocates of Fluoridation

According to those favouring fluoridation of public water supplies, fluoride is of immense benefit in preventing tooth decay. Various figures are given, ranging from 20% to 60% reduction in tooth decay compared with areas that are not fluoridated. There are large numbers of research studies published in dental journals which appear to support these figures.

The answer to the second question, again according to advocates of fluoridation, is that there is no harm whatsoever traceable to fluoridated water supplies.

Ray Lonergan is a Whangaparaoa dentist whose advertisements present him as ‘one of the country’s leading dental surgeons’. He "rejects any notion that fluoridated water is unsafe ".

Colgate Palmolive in their information leaflet say: "Of the numerous ills that have been attributed to fluoridation – from cancer in humans to constipation in dogs – none has ever been shown to be valid."

Given the above answers, the third one is obvious: a resounding "Yes" to fluoride.

Opposed to fluoridation

No difference:

Large scale research (for example, figures for all primary age children attending School Dental Clinics over sixty years in New Zealand; studies involving 400,000 children in India, and 26,000 children in Arizona) shows that there is little or no difference in tooth decay rates between fluoridated and non fluoridated areas, except that in areas where nutrition is poor, fluoridated areas have consistently higher decay rates.

Locally, tooth decay rates vary widely from district to district, in both fluoridated areas and non-fluoridated areas. Selective small scale studies can bear out either point of view. Anecdotal evidence is not to be relied on in the case of fluoride.

The big picture says, no difference. According to those opposed to fluoridation of water supplies, fluoridation does not deliver any benefits to teeth.

Optimum concentration

In respect of the second question, we need to consider the recommended fluoride concentration in public water supplies. This is almost universally considered to be one part per million (1 ppm) in temperate climates. (According to Colgate Palmolive, in an information leaflet about fluoridation, this gives optimum benefit with a water intake of 1 litre per person per day. The recommended daily intake of fluoride on this basis would appear to be around 1 mg per day.)

There is no substantive research to back up this figure, and in any case, even if the figure is allowed to have been accurate, it was determined in the mid-1940s. Since then, in New Zealand, public exposure to fluoride has increased dramatically. Consumption of red meat, sea food, tea, coffee, wine, and beer, all rich sources of fluoride, has increased considerably since the relative austerity of the war years.

Fluoridated toothpaste was unknown in the forties. Today in New Zealand it accounts for the vast majority, well over 90%, of toothpaste sales. Toothpaste is typically fluoridated at 2000 ppm. Swallowing 1 ml of fluoridated toothpaste twice a day multiplies by five the recommended intake.

There are typically no warnings on toothpaste tubes in New Zealand about not swallowing toothpaste. Some toothpaste comes in flavours designed to appeal to children. In considering possible harm, then, we cannot consider fluoridated water by itself. We have to consider it in relation to total exposure. If 1ppm in public water supplies was ever an "optimum concentration", it is no longer so.

Demonstrable Harm?

Given that 1 ppm is no longer optimum, can we therefore say that our present greater-than-optimum exposure to fluoride through water, food and toothpaste causes demonstrable harm?

Those opposed to fluoride would say, yes, we can.

Research has demonstrated an incidence of dental fluorosis in children at rates ranging from 25% to 80% where children are exposed to fluoridated water, toothpaste, and sometimes, fluoride supplements. Fluorosis is a discolouration of the teeth that can range from mild (in most cases) through to quite severe with accompanying damage to teeth affected. It is a symptom of overexposure to fluoride.

According to Dept of Health Education and Welfare of the US Food and Drug Administration, Washington D.C., sensitive individuals show signs of fluorosis on a daily intake of 2+mg of fluoride.

Secondly, research in India on more than 400,000 children has shown that in the absence of adequate calcium in the diet, fluoride acts to leach out calcium from the body, and actually increases the rate of tooth decay. This has been replicated in other studies elsewhere, notably a survey of 26000 school children in Tucson, Arizona, which linked fluoride intake directly to number of cavities.

Chinese studies on parallel communities have linked incidence of dental fluorosis with lower mean IQ, providing support for Phyllis Mullenix' earlier research demonstrating that normally fluoridated public water disrupted learning behaviour in rats.


Much of the research indicating areas of potential harm from fluoride is obtained from studies of rat populations. While rats do not model human response exactly, there are enough similarities to make them by far the most favoured laboratory test animal for all sorts of research attempting to predict human response.

Typically, fluoride studies on rats expose them to fluoride as drinking water at 1 ppm, and refer them to control groups of rats whose drinking water is distilled, but are otherwise treated exactly the same.

Two separate studies showed that rats fed fluoridated drinking water suffered considerably impaired immune systems.

One of the studies, using AlF3 (aluminium fluoride) as a fluoride source, demonstrated that fluoride in combination with low concentrations of aluminium bypassed normal cell barriers, and permitted aluminium to be deposited in rat brain tissue in patterns remarkably similar to those found in old people who have died of Alzheimer's Disease. (In addition, those fed fluoride as NaFl (sodium fluoride) - with no aluminium - also showed raised brain levels of aluminium compared to a control group, and researchers conjectured that the fluoridated water increased the rate at which aluminium incidentally present in other foodstuffs was taken up and absorbed by brain tissue.)

As aluminium compounds are also used in water purification to settle out fine solids, there is concern that aluminium residue in the water or elsewhere may combine with fluoride and lead to a higher incidence of Alzheimer's Disease among humans. The jury is still out.

Another study demonstrated that in rat populations fed fluoride as drinking water at 1 ppm, young male rats developed a rare bone cancer significantly more often than those fed distilled water. In the USA, this pattern has shown up in young male human beings where the water is fluoridated, but not in unfluoridated areas.

No definite link has been established, but testosterone is involved in the development of bones in males, but not in females, and fluoride has been shown to interfere with testosterone. More work to do yet.

Downs Syndrome A 1956-63 study found a link between fluoridated water supplies and Downs Syndrome (Mongolism). This study was followed by others which contradicted it, and its findings were disregarded.

The study was revisited this year with more sophisticated statistical techniques. While the mother's age was still the most significant factor in Downs Syndrome births over all, younger mothers (those under 30 years old) in fluoridated areas demonstrated a significantly higher incidence of Downs Syndrome births than those in non-fluoridated areas.

The difference was considered enough to amount to several thousand extra Downs Syndrome births per year around the world in fluoridated areas.

Brittle Bones

About 50% of ingested fluoride remains in the body. A number of studies in recent years suggest that populations exposed to fluoride over a long period have a higher incidence of hip and other fracture rates. Fluoride hardens bones, but it also makes them more brittle.

None of the above requires more than an exposure to fluoridated water at "optimum" concentration of 1 ppm, perhaps in association with exposure to fluoride as toothpaste, as supplements, and as foods rich in fluoride; perhaps in conjunction with poor nutrition.

For those opposed to fluoridation, there is ample evidence to answer the second question. Certainly, harm can attach to the consumption of fluoridated water. The only question is how much damage is necessary to human beings before authorities take notice.

And once again, the answer to the third question follows automatically. No benefit. Strong evidence of harm and/or likely harm. No, the benefit does not outweigh the harm. We don't want it in our water. At all.

You choose…


Fluoride Home Page

The Politics of Fluoride

Fluoride: The Article

Because we can... An(other) Unfortunate Experiment

The Science of Fluoride

Three Questions

Concentration, Dose and Dosage

Fluoride and the Law

1964 Revisited

Privy Council Decision