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Why I Changed My Mind about
Water Fluoridation
John Colquhoun, D.D.S., Ph.D.
Published in: Perspectives in
Biology and Medicine Volume 41, page 29-44. 1997
Former Advocate
To explain how I came to change my opinion about water
fluoridation, I must go back to when I was an ardent advocate of the
procedure. I now realize that I had learned, in my training in dentistry,
only one side of the scientific controversy over fluoridation. I had been
taught, and believed, that there was really no scientific case against
fluoridation, and that only misinformed lay people and a few crackpot
professionals were foolish enough to oppose it. I recall how, after I had
been elected to a local government in Auckland (New Zealand's largest city,
where I practised dentistry for many years and where I eventually became the
Principal Dental Officer) I had fiercely — and, I now regret, rather
arrogantly — poured scorn on another Council member (a lay person who had
heard and accepted the case against fluoridation) and persuaded the Mayor
and majority of my fellow councillors to agree to fluoridation of our water
supply.
A few years later, when I had become the city's Principal
Dental Officer, I published a paper in the New Zealand Dental Journal that
reported how children's tooth decay had declined in the city following
fluoridation of its water, to which I attributed the decline, pointing out
that the greatest benefit appeared to be in low-income areas [1]. My duties
as a public servant included supervision of the city's school dental
clinics, which were part of a national School Dental Service which provided
regular six-monthly dental treatment, with strictly enforced uniform
diagnostic standards, to almost all (98 percent) school children up to the
age of 12 or 13 years. I thus had access to treatment records, and therefore
tooth decay rates, of virtually all the city's children. In the study I
claimed that such treatment statistics "provide a valid measure of the
dental health of our child population" [1]. That claim was accepted by my
professional colleagues, and the study is cited in the official history of
the New Zealand Dental Association [2].
Information Confided
I was so articulate and successful in my support of water
fluoridation that my public service superiors in our capital city,
Wellington, approached me and asked me to make fluoridation the subject of a
world study tour in 1980 — after which I would become their expert on
fluoridation and lead a campaign to promote fluoridation in those parts of
New Zealand which had resisted having fluoride put into their drinking
water.
Before I left on the tour my superiors confided to me that
they were worried about some new evidence which had become available:
information they had collected on the amount of treatment children were
receiving in our school dental clinics seemed to show that tooth decay was
declining just as much in places in New Zealand where fluoride had not been
added to the water supply. But they felt sure that, when they had collected
more detailed information, on all children (especially the oldest treated,
12-13 year age group) from all fluoridated and all nonfluoridated places [3]
— information which they would start to collect while was I away on my tour
— it would reveal that the teeth were better in the fluoridated places: not
the 50 to 60 percent difference which we had always claimed resulted from
fluoridation, but a significant difference nonetheless. They thought that
the decline in tooth decay in the nonfluoridated places must have resulted
from the use of fluoride toothpastes and fluoride supplements, and from
fluoride applications to the children's teeth in dental clinics, which we
had started at the same time as fluoridation. Being a keen fluoridationist,
I readily accepted their explanation. Previously, of course, we had assured
the public that the only really effective way to reduce tooth decay was to
add fluoride to the water supply.
World Study Tour
My world study tour took me to North America, Britain,
Europe, Asia, and Australia [4]. In the United States I discussed
fluoridation with Ernest Newbrun in San Francisco, Brian Burt in Ann Arbor,
dental scientists and officials like John Small in Bethesda near Washington,
DC, and others at the Centers for Disease Control in Atlanta. I then
proceeded to Britain, where I met Michael Lennon, John Beale, Andrew Rugg-Gunn,
and Neil Jenkins, as well as many other scientists and public health
officials in Britain and Europe. Although I visited only pro-fluoridation
research centers and scientists, I came across the same situation which
concerned my superiors in New Zealand. Tooth decay was declining without
water fluoridation. Again I was assured, however, that more extensive and
thorough surveys would show that fluoridation was the most effective and
efficient way to reduce tooth decay. Such large-scale surveys, on very large
numbers of children, were nearing completion in the United States, and the
authorities conducting them promised to send me the results.
Lesson from History
I now realize that what my colleagues and I were doing was
what the history of science shows all professionals do when their pet theory
is confronted by disconcerting new evidence: they bend over backwards to
explain away the new evidence. They try very hard to keep their theory
intact — especially so if their own professional reputations depend on
maintaining that theory. (Some time after I graduated in dentistry almost
half a century ago, I also graduated in history studies, my special interest
being the history of science — which may partly explain my re-examination of
the fluoridation theory ahead of many of my fellow dentists.)
So I returned from my study tour reinforced in my
pro-fluoridation beliefs by these reassurances from fluoridationists around
the world. I expounded these beliefs to my superiors, and was duly appointed
chairman of a national "Fluoridation Promotion Committee." I was instructed
to inform the public, and my fellow professionals, that water fluoridation
resulted in better children's teeth, when compared with places with no
fluoridation.
Surprise: Teeth Better Without Fluoridation?
Before complying, I looked at the new dental statistics
that had been collected while I was away for my own Health District,
Auckland. These were for all children attending school dental clinics —
virtually the entire child population of Auckland. To my surprise, they
showed that fewer fillings had been required in the nonfluoridated part of
my district than in the fluoridated part. When I obtained the same
statistics from the districts to the north and south of mine — that is, from
"Greater Auckland," which contains a quarter of New Zealand's population —
the picture was the same: tooth decay had declined, but there was virtually
no difference in tooth decay rates between the fluoridated and non
fluoridated places. In fact, teeth were slightly better in the
nonfluoridated areas. I wondered why I had not been sent the statistics for
the rest of New Zealand. When I requested them, they were sent to me with a
warning that they were not to be made public. Those for 1981 showed that in
most Health Districts the percentage of 12- and 13-year-old children who
were free of tooth decay - that is, had perfect teeth - was greater in the
non-fluoridated part of the district. Eventually the information was
published [4].
Over the next few years these treatment statistics,
collected for all children, showed that, when similar fluoridated and
non-fluoridated areas were compared, child dental health continued to be
slightly better in the non-fluoridated areas [5,6]. My professional
colleagues, still strongly defensive of fluoridation, now claimed that
treatment statistics did not provide a valid measure of child dental health,
thus reversing their previous acceptance of such a measure when it had
appeared to support fluoridation.
I did not carry out the instruction to tell people that
teeth were better in the fluoridated areas. Instead, I wrote to my American
colleagues and asked them for the results of the large-scale surveys they
had carried out there. I did not receive an answer. Some years later, Dr
John Yiamouyiannis obtained the results by then collected by resorting to
the U.S. Freedom of Information Act, which compelled the authorities to
release them. The surveys showed that there is little or no differences in
tooth decay rates between fluoridated and nonfluoridated places throughout
America [7]. Another publication using the same database, apparently
intended to counter that finding, reported that when a more precise
measurement of decay was used, a small benefit from fluoridation was shown
(20 percent fewer decayed tooth surfaces, which is really less than one
cavity per child) [8]. Serious errors in that report, acknowledged but not
corrected, have been pointed out, including a lack of statistical analysis
and a failure to report the percentages of decay-free children in the
fluoridated and nonfluoridated areas [7].
Other large-scale surveys from United States, from
Missouri and Arizona, have since revealed the same picture: no real benefit
to teeth from fluoride in drinking water [9, 10]. For example, Professor
Steelink in Tucson, AZ, obtained information on the dental status of all
schoolchildren – 26,000 of them – as well as information on the fluoride
content of Tucson water [10]. He found: "When we plotted the incidence of
tooth decay versus fluoride content in a child's neighborhood drinking
water, a positive correlation was revealed. In other words, the more
fluoride a child drank, the more cavities appeared in the teeth" [11].
From other lands — Australia, Britain, Canada, Sri Lanka,
Greece, Malta, Spain, Hungary, and India — a similar situation has been
revealed: either little or no relation between water fluoride and tooth
decay, or a positive one (more fluoride, more decay) [12-17]. For example,
over 30 years Professor Teotia and his team in India have examined the teeth
of some 400,000 children. They found that tooth decay increases as fluoride
intake increases. Tooth decay, they decided, results from a deficiency of
calcium and an excess of fluoride [17].
Cause of Decline in Tooth Decay
At first I thought, with my colleagues, that other uses of
fluoride must have been the main cause of the decline in tooth decay
throughout the western world. But what came to worry me about that argument
was the fact that, in the nonfluoridated part of my city, where decay had
also declined dramatically, very few children used fluoride toothpaste, many
had not received fluoride applications to their teeth, and hardly any had
been given fluoride tablets. So I obtained the national figures on tooth
decay rates of five-year-olds from our dental clinics which had served large
numbers of these children from the 1930s on [18]. They show that tooth decay
had started to decline well before we had started to use fluorides (Fig. 1).
Also, the decline has continued after all children had received fluoride all
their lives, so the continuing decline could not be because of fluoride. The
fewer figures available for older children are consistent with the above
pattern of decline [18]. So fluorides, while possibly contributing, could
not be the main cause of the reduction in tooth decay.
So what did cause this decline, which we find in most
industrialized countries? I do not know the answer for sure, but we do know
that after the second world war there was a rise in the standard of living
of many people. In my country there has been a tremendous increase in the
consumption of fresh fruit and vegetables since the 1930s, assisted by the
introduction of household refrigerators [19]. There has also been an
eightfold increase in the consumption per head of cheese, which we now know
has anti-decay properties [19, 20]. These nutritional changes, accompanied
by a continuing decline in tooth decay, started before the introduction of
fluorides.
The influence of general nutrition in protection against
tooth decay has been well described in the past [21], but is largely ignored
by the fluoride enthusiasts, who insist that fluorides have been the main
contributor to improved dental health. The increase in tooth decay in
third-world countries, much of which has been attributed to worsening
nutrition [22], lends support to the argument that improved nutrition in
developed countries contributed to improved dental health.
Flawed Studies
The studies showing little if any benefit from
fluoridation have been published since 1980. Are there contrary findings?
Yes: many more studies, published in dental professional journals, claim
that there is a benefit to teeth from water fluoride. An example is a recent
study from New Zealand [23], carried out in the southernmost area of the
country [23]. Throughout New Zealand there is a range of tooth decay rates,
from very high to very low, occurring in both fluoridated and nonfluoridated
areas. The same situation exists in other countries.
What the pro-fluoride academics at our dental school did
was to select from that southern area four communities: one nonfluoridated,
two fluoridated, and another which had stopped fluoridation a few years
earlier. Although information on decay rates in all these areas was
available to them, from the school dental service, they chose for their
study the one non-fluoridated community with the highest decay rate and two
fluoridated ones with low decay rates, and compared these with the recently
stopped fluoridated one, which happened to have medium decay rates (both
before and after it had stopped fluoridation). The teeth of randomly
selected samples of children from each community were examined. The chosen
communities, of course, had not been randomly selected. The results, first
published with much publicity in the news media, showed over 50 percent less
tooth decay in the fluoridated communities, with the recently defluoridated
town in a "middle" position (see left side of Fig. 2). When I obtained the
decay rates for all children in all the fluoridated and all the
nonfluoridated areas in that part of New Zealand, as well as the decay rates
for all children in the recently defluoridated town, they revealed that
there are virtually no differences in tooth decay rates related to
fluoridation (see right side of Fig. 2).
When I confronted the authors with this information, they
retorted that the results of their study were consistent with other studies.
And of course it is true that many similar studies have been published in
the dental professional literature. It is easy to see how the consistent
results are obtained: an appropriate selection of the communities being
compared. There is another factor: most pro-fluoridation studies (including
this New Zealand one) were not "blind" — that is, the examiners knew which
children received fluoride and which did not. Diagnosis of tooth decay is a
very subjective exercise, and most of the examiners were keen
fluoridationists, so it is easy to see how their bias could affect their
results. It is just not possible to find a blind fluoridation study in which
the fluoridated and nonfluoridated populations were similar and chosen
randomly.
Early Flawed Studies
One of the early fluoridation studies listed in the
textbooks is a New Zealand one, the "Hastings Fluoridation Experiment" (the
term "experiment" was later dropped because the locals objected to being
experimented on) [24]. I obtained the Health Department's fluoridation files
under my own country's "Official Information" legislation. They revealed how
a fluoridation trial can, in effect, be rigged [25]. The school dentists in
the area of the experiment were instructed to change their method of
diagnosing tooth decay, so that they recorded much less decay after
fluoridation began. Before the experiment they had filled (and classified as
"decayed") teeth with any small catch on the surface, before it had
penetrated the outer enamel layer. After the experiment began, they filled
(and classified as "decayed") only teeth with cavities which penetrated the
outer enamel layer. It is easy to see why a sudden drop in the numbers of
"decayed and filled" teeth occurred. This change in method of diagnosis was
not reported in any of the published accounts of the experiment.
Another city, Napier, which was not fluoridated but had
otherwise identical drinking water, was at first included in the experiment
as an "ideal control" — to show how tooth decay did not decline the same as
in fluoridated Hastings. But when tooth decay actually declined more in the
non-fluoridated control city than in the fluoridated one, in spite of the
instructions to find fewer cavities in the fluoridated one, the control was
dropped and the experiment proceeded with no control. (The claimed excuse
was that a previously unknown trace element, molybdenum, had been discovered
in some of the soil of the control city, making tooth decay levels there
unusually low [26], but this excuse is not supported by available
information, from the files or elsewhere, on decay levels throughout New
Zealand).
The initial sudden decline in tooth decay in the
fluoridated city, plus the continuing decline which we now know was
occurring everywhere else in New Zealand, were claimed to prove the success
of fluoridation. These revelations from government files were published in
the international environmental journal, The Ecologist, and presented in
1987 at the 56th Congress of the Australian and New Zealand Association for
the Advancement of Science [27].
When I re-examined the classic fluoridation studies, which
had been presented to me in the text books during my training, I found, as
others had before me, that they also contained serious flaws [28-30]. The
earliest set, which purported to show an inverse relationship between tooth
decay prevalence and naturally occurring water fluoride concentrations, are
flawed mainly by their nonrandom methods of selecting data. The later set,
the "fluoridation trials" at Newburgh, Grand Rapids, Evanston, and
Brantford, display inadequate baselines, negligible statistical analysis,
and especially a failure to recognize large variations in tooth decay
prevalence in the control communities. We really cannot know whether or not
some of the tooth decay reductions reported in those early studies were due
to water fluoride.
I do not believe that the selection and bias that
apparently occurred was necessarily deliberate. Enthusiasts for a theory can
fool themselves very often, and persuade themselves and others that their
activities are genuinely scientific. I am also aware that, after 50 years of
widespread acceptance and endorsement of fluoridation, many scholars
(including the reviewers of this essay) may find it difficult to accept the
claim that the original fluoridation studies were invalid. That is why some
of us, who have reached that conclusion, have submitted an invitation to
examine and discuss new and old evidence "in the hope that at least some
kind of scholarly debate will ensue" [31].
However, whether or not the early studies were valid, new
evidence strongly indicates that water fluoridation today is of little if
any value. Moreover, it is now widely conceded that the main action of
fluoride on teeth is a topical one (at the surface of the teeth), not a
systemic one as previously thought, so that there is negligible benefit from
swallowing fluoride [32].
Harm from Fluoridation
The other kind of evidence which changed my mind was that
of harm from fluoridation. We had always assured the public that there was
absolutely no possibility of any harm. We admitted that a small percentage
of children would have a slight mottling of their teeth, caused by the
fluoride, but this disturbance in the formation of tooth enamel would, we
asserted, be very mild and was nothing to worry about. It was, we asserted,
not really a sign of toxicity (which was how the early literature on
clinical effects of fluoride had described it) but was only at most a
slight, purely cosmetic change, and no threat to health. In fact, we claimed
that only an expert could ever detect it.
Harm to Teeth
So it came as a shock to me when I discovered that in my
own fluoridated city some children had teeth like those in Fig. 3. This kind
of mottling answered the description of dental fluorosis (bilateral diffuse
opacities along the growth lines of the enamel). Some of the children with
these teeth had used fluoride toothpaste and swallowed much of it. But I
could not find children with this kind of fluorosis in the nonfluoridated
parts of my Health District, except in children who had been given fluoride
tablets at the recommended dose of that time.
I published my findings: 25 percent of children had dental
fluorosis in fluoridated Auckland and around 3 percent had the severer
(discolored or pitted) degree of the condition [33]. At first the
authorities vigorously denied that fluoride was causing this unsightly
mottling. However, the following year another Auckland study, intended to
discount my finding, reported almost identical prevalences and severity, and
recommended lowering the water fluoride level to below 1 ppm [34]. Others in
New Zealand and the United States have reported similar findings. All these
studies were reviewed in the journal of the International Society for
Fluoride Research [35]. The same unhappy result of systemic administration
of fluoride has been reported in children who received fluoride supplements
[36]. As a result, in New Zealand as elsewhere, the doses of fluoride
tablets were drastically reduced, and parents were warned to reduce the
amount of fluoride toothpaste used by their children, and to caution them
not swallow any. Fluoridationists would not at first admit that fluoridated
water contributed to the unsightly mottling — though later, in some
countries including New Zealand, they also recommended lowering the level of
fluoride in the water. They still insist that the benefit to teeth outweighs
any harm.
Weakened Bones
Common sense should tell us that if a poison circulating
in a child's body can damage the tooth-forming cells, then other harm also
is likely. We had always admitted that fluoride in excess can damage bones,
as well as teeth.
By 1983 I was thoroughly convinced that fluoridation
caused more harm than good. I expressed the opinion that some of these
children with dental fluorosis could, just possibly, have also suffered harm
to their bones [Letter to Auckland Regional Authority, January 1984]. This
opinion brought scorn and derision: there was absolutely no evidence, my
dental colleagues asserted, of any other harm from low levels of fluoride
intake, other than mottling of the teeth.
Six years later, the first study reporting an association
between fluoridated water and hip fractures in the elderly was published
[37]. It was a large-scale one. Computerization has made possible the
accumulation of vast data banks of information on various diseases. Hip
fracture rates have increased dramatically, independently of the increasing
age of populations. Seven other studies have now reported this association
between low water fluoride levels and hip fractures [38-44]. Have there been
contrary findings? Yes; but most of the studies claiming no association are
of small numbers of cases, over short periods of time, which one would not
expect to show any association [45, 46]. Another, comparing a fluoridated
and a nonfluoridated Canadian community, also found an association in males
but not in females, which hardly proves there is no difference in all cases
[47]. Our fluoridationists claim that the studies which do show such an
association are only epidemiological ones, not clinical ones, and so are not
conclusive evidence.
But in addition to these epidemiological studies, clinical
trials have demonstrated that when fluoride was used in an attempt to treat
osteoporosis (in the belief it strengthened bones), it actually caused more
hip fractures [48-52]. That is, when fluoride accumulates in bones, it
weakens them. We have always known that only around half of any fluoride we
swallow is excreted in our urine; the rest accumulates in our bones [53,
54]. But we believed that the accumulation would be insignificant at the low
fluoride levels of fluoridated water. However, researchers in Finland during
the 1980s reported that people who lived 10 years or more in that country's
one fluoridated city, Kuopio, had accumulated extremely high levels of
fluoride in their bones — thousands of parts per million — especially
osteoporosis sufferers and people with impaired kidney function [55, 56].
After this research was published, Finland stopped fluoridation altogether.
But that information has been ignored by our fluoridationists.
Bone Cancer?
An association with hip fracture is not the only evidence
of harm to bones from fluoridation. Five years ago, animal experiments were
reported of a fluoride-related incidence of a rare bone cancer, called
osteosarcoma, in young male rats [57]. Why only the male animals got the
bone cancer is not certain, but another study has reported that fluoride at
very low levels can interfere with the male hormone, testosterone [58]. That
hormone is involved in bone growth in males but not in females.
This finding was dismissed by fluoridation promoters as
only "equivocal evidence," unlikely to be important for humans. But it has
now been found that the same rare bone cancer has increased dramatically in
young human males — teenage boys aged 9 to 19 — in the fluoridated areas of
America but not in the nonfluoridated areas [59]. The New Jersey Department
of Health reported osteosarcoma rates were three to seven times higher in
its fluoridated areas than in its nonfluoridated areas [60].
Once again, our fluoridationists are claiming that this
evidence does not "conclusively" demonstrate that fluoride caused the
cancers, and they cite small-scale studies indicating no association. One
study claimed that fluoride might even be protective against osteosarcoma
[61]; yet it included only 42 males in its 130 cases, which meant the cases
were not typical of the disease, because osteosarcoma is routinely found to
be more common in males. Also, the case-control method used was quite
inappropriate, being based on an assumption that if ingested fluoride was
the cause, osteosarcoma victims would require higher fluoride exposure than
those without the disease. The possibility that such victims might be more
susceptible to equal fluoride exposures was ignored. All these
counter-claims have been subjected to critical scrutiny which suggests they
are flawed [62, 63]. Nonetheless, the pro-fluoride lobbyists continue to
insist that water fluoridation should continue because, in their view, the
benefits to teeth outweigh the possibility of harm. Many dispute that
assessment.
Other Evidence of Harm
There is much more evidence that tooth mottling is not the
only harm caused by fluoridated water. Polish researchers, using a new
computerized method of X-ray diagnosis, reported that boys with dental
fluorosis also exhibit bone structure disturbances [64]. Even more chilling
is the evidence from China that children with dental fluorosis have on
average lower intelligence scores [65, 66]. This finding is supported by a
recently published animal experiment in America, which showed that fluoride
also accumulated in certain areas of the brain, affecting behavior and the
ability to learn [67].
Endorsements Not Universal
Concerning the oft-repeated observation that fluoridation
has enjoyed overwhelming scientific endorsement, one should remember that
even strongly supported theories have eventually been revised or replaced.
From the outset, distinguished and reputable scientists opposed
fluoridation, in spite of considerable intimidation and pressure [68, 69].
Most of the world has rejected fluoridation. Only America
where it originated, and countries under strong American influence persist
in the practice. Denmark banned fluoridation when its National Agency for
Environmental Protection, after consulting the widest possible range of
scientific sources, pointed out that the long-term effects of low fluoride
intakes on certain groups in the population (for example, persons with
reduced kidney function), were insufficiently known [70]. Sweden also
rejected fluoridation on the recommendation of a special Fluoride
Commission, which included among its reasons that: "The combined and
long-term environmental effects of fluoride are insufficiently known" [71].
Holland banned fluoridation after a group of medical practitioners presented
evidence that it caused reversible neuromuscular and gastrointestinal harm
to some individuals in the population [72].
Environmental scientists, as well as many others, tend to
doubt fluoridation. In the United States, scientists employed by the
Environmental Protection Agency have publicly disavowed support for their
employer's pro-fluoridation policies [73]. The orthodox medical
establishment, rather weak or even ignorant on environmental issues, persist
in their support, as do most dentists, who tend to be almost fanatical about
the subject. In English- speaking countries, unfortunately, the medical
profession and its allied pharmaceutical lobby (the people who sell
fluoride) seem to have more political influence than environmentalists.
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