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Water Fluoridation - Fluoride in Water


Water Fluoridation


Michael Sellar

Fluorine is the 13th most common element and is widespread in the environment, although this gas only exists as compounds (fluorides) with other elements. The commonest being calcium fluoride.

At the beginning of the 20th century it was noticed that the inhabitants of some areas of the USA had mottled tooth enamel (fluorosis). Investigators discovered high amounts of naturally occurring calcium fluoride in the drinking water. Children in these areas appeared to have less tooth decay and hence the notion got around that fluoride protected children’s teeth. Studies in the USA and other countries including the UK followed. These seemed to confirm the association between fluoride water content and caries reduction.

Fluoride Protects

Fluoride is believed to protect teeth by replacing hydroxyapatite by the more resistant fluorapatite in the growing period up to age 12. Fluoride also has strong antibacterial activity. Theoretically at least, fluoride should offer some protection against tooth decay.

And many studies support this conclusion. For instance, a seven year study published in 1981 examined 5 year olds in 4 urban communities in England. They found an excellent inverse correlation between fluoride content of the water supplies and the incidence of caries.

Or Does It?

Although proponents of fluoridation speak of    volumes of such research over many years, in reality much of it demonstrating a protective effect is weak by today’s standards. The NHS Centre for Reviews and Dissemination, University of York, (NHSCRD) in their systematic review published in 2000 included 214 studies. But they noted that “the quality of studies was low to moderate.” In spite of this they concluded that there was a beneficial reduction in caries.

In 1988, Philip Sutton, a former senior lecturer in Dental Science investigated claims by the proponents of fluoridation that 128 studies confirm caries reduction of 50% - 75%. He found that none of the studies made any attempt to avoid bias, 34 of the studies didn’t exist, 20 were about something else, and 51 were too poor scientifically to consider. Of the 23 that were left, none showed fluoridation to be beneficial in any scientifically acceptable way.

There is also much evidence which negates the positive findings.

A 1982 study covering several countries showed caries reduction of between 17% and over 50% in unfluoridated areas. This was confirmed by the World Health Organisation and the US National Institute for Dental Research in its study of 39,000 children.

In 1948, North Shields, which has little or no naturally occurring fluoride, was compared to South Shields, where the water has a natural fluoride   content of 1.4 parts per million. Dental caries was found to be the same in both towns. All that fluoride did was to delay the onset of caries by several years according to the research.

The discoverer of streptomycin, Professor Albert Schatz agrees that fluoridation simply delays the appearance of caries because it delays the    eruption of teeth. “Fluoridated children develop the same amount of tooth decay...The only difference is that caries start developing approximately 1.2 years later.”

The lowest rates of caries in Canada are to be found in British Columbia where 11% of the population have fluoridated water compared to 40 - 70% in the rest of Canada.

73% of the Republic of Ireland’s population live in fluoridated areas. From 1972 - 1992 the rate of decayed, missing and filled teeth (DMFT) in 12 year olds fell from 5.4 to 1.9. Yet they are only 6th in the European league table. First is unfluoridated Finland (1975-1991 DMFT fell from 7.5 to 1.2). In second place is unfluoridated Denmark (1978-1992 DMFT fell from 6.4 to 1.3).

Some studies show that fluoride causes an increase in decay. An Indian survey of 400,000 children found higher decay in fluoridated areas and a survey of 20,000 Japanese students found higher rates of decay.

In some places fluoridation was practised but then halted. Kuopia in Finland stopped fluoride treatment after 33 years. The result? Over the following  6 year period teeth got better. There was a similar story in two towns in the former East Germany. Because this finding was so unexpected a further survey was carried out in 2 other towns. 3 years after stopping fluoridation DMFT fell by 38.5% in one and 20.6% in the other.

It’s Toxic & Accumulates

Britain and Ireland only allow hexafluorosilicic acid or hexafluorosilicate to be used for water fluoridation. It contains a form of silicon which has been linked to cancer. These fluorosilicates aren’t pure either. They contain a number of contaminants which includes lead, arsenic and mercury. According to toxicologist Professor Phyllis Mullenix, “the ‘fifty years’ of studies about fluoride safety do not exist.”

There is no dispute that fluoride is potentially toxic and that the effect is cumulative. In fact the Journal of the American Dental Association stated back in 1936 that “fluoride at the 1ppm concentration is as toxic as arsenic and lead.” In those days the dental profession were keen to remove fluoride from water. They have since reversed their position, no longer considering it toxic at that level.

In 1942 the editor of the Journal of the American Medical Association described fluorides as “general protoplasmic poisons.” And in 1950 the pharmacists reference book US Dispensary described fluorides as “violent poisons to all living tissue”. As recently as 1984 a toxicology reference book gave fluoride a toxicology rating of 4 (very toxic). They go on: “the fact is that fluoride is more toxic than lead and just slightly less toxic than arsenic.”

Yet the US Environmental Protection Agency set the maximum contaminant level for lead at 0.015ppm and for fluoride at 4.0ppm. That’s 266 times higher. Does that make any sense?

More than 100 fatal acute fluoride intoxications were reported between 1935 and 1981.

Fluoride & Cancer

It should come as no surprise that fluoride could have potentially detrimental affects on health. Fluoride has been linked to genetic damage. One study found that just 1ppm inhibited DNA repair and damaged chromosomes. Another found “a highly significant   increase in mutation.” A review of such studies concluded that “the weight of the evidence leads to the conclusion that fluoride exposure results in increased chromosome aberrations”. Some of the studies that produced positive results were at 1-5ppm, levels equivalent to human exposure. However whether fluoride produces chromosome damage in vivo in humans “should be considered unresolved”, they stated.

Fluoride inhibits several enzyme systems. It can combine with catalase for instance, to inhibit its activity. Catalase is an essential part of our antioxidant defence system.

The ten largest fluoridated areas in the USA were compared with the ten largest unfluoridated in the 1970’s. Cancer rates were similar before fluoridation. But after 20 years these areas had a cancer death rate 10% higher.

Other epidemiological analysis in the 1980’s found significant correlation between fluoridated  areas of the USA and cancer incidence. An interesting finding was that women’s hormonal cancers  increased while male hormonal cancers decreased. The authors wondered whether fluoride could act as an environmental hormone. A significant dose response relationship was also found for bone    cancers in male teenagers.

A rodent study found that the more fluoride they ingested the higher the incidence of bone cancers they developed.

Because of these findings Dr Perry Cohn surveyed a number of areas of New Jersey. He found the incidence of bone cancers in boys was up to 4.6 times higher in the fluoridated areas.

Some studies also suggest that fluoride has a causal relationship with respiratory, oral and uterine cancers.  Of course not all studies find fluoride guilty and the NHSCRD found no clear association with any cancer.

Fluoride & The Brain

Fluoride inhibits the brain chemical acetylcholinesterase. In 1995 an animal study demonstrated that fluoride affects the central nervous system.

Chinese scientists showed that children in highly fluoridated areas have a lower IQ than those who are fluoride free.

Fluoride may also affect the brain by combining with aluminium to form aluminium fluoride and may increase the absorption of lead.

It also competes with iodine for absorption and was used to treat an overactive thyroid for many years, often at intakes below 1mg a day.

Fluoride has also been shown to accumulate in the pineal gland to inhibit melatonin production in animals. This causes earlier onset of sexual maturity.

Many mood altering drugs like Prozac (fluoxetine), designed to act on the central nervous system, include fluoride in their chemical makeup.

How Much Do We Ingest?

It is possible that something which is toxic at a high dose could be beneficial at a low dose. The 1ppm level is supposed to give children a protective 1mg a day assuming they drink 1 litre a day. However I don’t see any health warnings on our taps not to drink more than a litre a day, and many commercial drinks and juices use fluoridated water.

The UK Department of Health suggests a safe intake is 3mg a day. The official position of the US National Academy of Sciences is that the “crippling daily dose” is 10mg - 20mg a day over a 10 - 20 year period (remember the effects of fluoride are cumulative). So if we take in just 1mg we shouldn’t suffer with bone disease until we’re at least 100 years old. But do we just ingest 1mg a day?

Apart from water, sources of fluoride include bonemeal, bran, beets, yams, sunflower seeds, whey, milk, cheese, garlic, green vegetables, kelp, gelatin and small fish eaten with bones. Sodium silicofluoride spray (an insecticide) remains in the peel of oranges and many marmalades contain orange peel. The pesticide cryolate, which is over 50% fluorine is used on apples, raisins, lettuce, tomatoes, potatoes, peaches and most berries. Tea can be a major source of fluoride. A cup of tea may contain up to 0.2mg of fluoride, so many adults get a daily dose from 5 cups. Vegetables cooked in fluoridated water averaged 0.4 mg per kg., whereas those cooked in nonfluoridated water averaged only 0.2mg per kg. Then there are
toothpastes, gels, flosses and mouthwashes, Teflon coated cookware (poly-tetra-fluoroethane), cigarettes and some pharmaceuticals.

Early figures calculated intake to be 1.5mg a day. In the 1970’s it was put at 3.0mg. By the 1990’s the US Dept. of Health put the figure for US fluoridated cities at 6.5mg. Current intake is thought to approach 8mg.

Natick in Massachussets fluoridated its water supply in 1998. All water bills carry this message: “we recommend that pregnant women, parents of children under 3 and individuals with known fluoride sensitivity consult with their personal physicians before drinking this water.”

How Much Do We Excrete?

It’s your kidneys’ job to excrete fluoride. Healthy ones will excrete about 50%. But what if it’s not up to par? This is what the Journal of the American Medical Association had to say in 1972: “Children, the elderly and any person with impaired kidney function are in the high risk group for fluoride  poisoning and must be warned to monitor their  fluoride intake. Also at high risk are people with immunodeficiencies, diabetes and heart ailments as well as anyone with calcium, magnesium and vitamin C deficiencies. At the level of 0.4ppm renal impairment has been shown.”

How elderly are the elderly? The US Agency for Toxic Substances and Disease Registry reiterated the above statement in 1993 and added: “People over the age of 50 often have decreased fluoride renal clearance.”

Fluoride Harms Children

A 5 year study of children under 6 in the USA between 1989 and 1994 found that several hundred children were treated at health care facilities each year because of ingestion of toxic amounts of home-use dental fluoride products i.e. toothpastes, rinses and gels. The frequently cited dose was 5mg per kilogram bodyweight. Outcomes were “generally not serious.”

And what about bathtime? Shampoos, bubble baths and soaps contain sodium lauryl sulphate. It is used by drug companies to increase the absorption of medications that act on the skin. Fluoride can also be absorbed through the skin. Added to bath water absorption is increased by 9%!

One of the objectives of fluoridation is to even out inequalities in health. But it’s possible that the poorest children will be affected the worst.

The work of Professor Schatz in Chile showed that the more malnourished a child, the more susceptible they were to fluoride toxicity. He believed that high levels of infant mortality there was linked to fluoride ingestion. As a result of his work fluoridation was stopped in that country although it was later reinstated.

A diet rich in vitamins and minerals will  decrease the intestinal absorption of fluoride. One study found that poorer children had 2.3 times as much dental fluorosis as children from higher income families.

Back in 1952 the Journal of the American  Dental Association said that “malnourished infants and children, especially if deficient in calcium intake, may suffer from the effects of water containing  fluorine while healthy children would remain unaffected.” This was reaffirmed by Professor Massler of the University of Illinois College of Dentistry in 2000 who said that “lower levels of fluoride ingestion...may not be safe for malnourished infants and children.”

Have poorer children been helped by fluoride? Liverpool has more than twice the number of underprivileged children that Gateshead. Yet the rate of dental decay for 5 year olds is the same in each city. What’s more, Gateshead is fluoridated and Liverpool isn’t!

Who Wants Mottled Teeth?

Those in favour of fluoridation do not deny this negative effect. This was reaffirmed by the NHSCRD: “there is a dose response relationship between water fluoride level and the prevalence of fluorosis. Fluorosis appears to occur frequently (48%) at fluoride levels typically used in artificial fluoridation schemes (1ppm). The proportion of fluorosis that is ethically concerning is lower (12½%).”

Is this a minor cosmetic issue or does it indicate toxicity? Surely the latter since fluoride also accumulates in the bones and suggests enzyme/protein damage . If I were a child I certainly wouldn’t consider permanently stained teeth as just a cosmetic issue.

Fluoride & Bones

Studies published in the 1960’s showed that incidence of osteoporosis was substantially higher in areas where the drinking water contained low levels of fluoride. Another did not support this finding but found that higher levels of fluoride than were added to the water supply were protective. Fluoride is  believed to stimulate bone formation in combination with calcium and vitamin D. It does this by entering into the collaganous matrix of bone to form large hydroxyapatite crystals which are more resistant to osteoclastic attack. However with skeletal fluorosis the bones may become brittle and more fragile.

Fluoride also seems to be a potent stimulator of osteoblastic bone formation to increase spinal bone mass. However clinical trials have proved disappointing. Vertebral bone densities increased without any decrease in fracture rates and there was an  increase in non-vertebral fractures. Even so, many European countries use slow release sodium fluoride as a therapy for osteoporosis.


Only 5 countries in the world fluoridate their water supply to any great degree. Only 2% of the population of Western Europe drink it, and most of those are in England. All supportive studies are either poor or moderate. If the benefits are so obvious why do so few countries utilise it?

When the idea was first muted, intakes of fluoride were low. But today we can ingest it from a variety of dental sources, pesticide residues, commercial products and drugs.

Even if fluoride does protect children’s teeth, we don’t need any more than is already in our environment. Dental decay has been falling without the ‘benefit’ of fluoride. Children don’t get decayed teeth because of a shortage of fluoride, but because of nutrition and lifestyle factors. It’s these that need to be addressed. Fluoride ingested by the poorest children will just increase their risk of toxicity.

No doctor would prescribe a drug without a consideration of dosage. And yet when it comes to fluoride, the sky’s the limit, even though fluoride is a known toxin and it accumulates in the body; even though a large percentage of the population will have difficulty excreting it because of health problems or their age.

How do you limit intake to 1mg? Are the Water Police going to raid our homes for the ‘crime’ of drinking more than 1 litre of water a day?

With increasing life expectancy, how many  people are going to spend the last decades of their life with bone disease thanks to the accumulation of fluoride over their lifetime?

In short, there is no scientific, medical, ethical or moral case for water fluoridation.

This article was first published in Enzyme Digest No. 64 Spring 2004

Any health and medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.