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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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