Fluoride sensitivity – all in the mind?

anecI have had a few letters from anti-fluoridation activists lately assuring me they have symptoms of fluoride sensitivity, or hypersensitivity. The local campaigners have even produced a video of one of their members discussing his own symptoms (see Gus Hastie on fluoride hypersensitivity).

Now, I never want to be in the position of ignoring people’s symptoms, but really – self-diagnosis is always dangerous. What they attribute to fluoride sensitivity may turn out to be something far more serious. People should always check out their health problems with a qualified professional.

Like all claims based on anecdotal evidence fluoride sensitivity and hypersensitivity could be nothing more than an attempt to produce damning evidence against fluoridation – without actually having any evidence. I have had an upset stomach and headaches for a few months – ever since fluoridation was stopped! I would be a fool to just assume this was due to lack of fluoride, wouldn’t I?

Perhaps health authorities could have taken advantage of the Hamilton City Council’s decision to stop fluoridation to carry out a social experiment – to check if people’s claimed symptoms of fluoride sensitivity actually coincided with fluoridation, or its absence.

The Finnish experiment

Well, I found out recently the experiment has already been done. Fluoridation was stopped in the Finnish town of Kuopio at the end of 1992. (see Lamberg et al. Symptoms experienced during periods of actual and supposed water fluoridation.)

The public had been well informed of the change, but what they did not know is that fluoridation was actually stopped a month earlier than planned. The public were surveyed about their symptoms using questionnaires in the month of November (when water was till fluoridated and citizens believed it was), December (when water was no longer fluoridated but citizens believed it was) and March (when the water was no longer fluoridated and citizens knew that it wasn’t).

The graph below shows the percentage of respondents to the surveys reporting symptoms at the three times. Data is the average of the 5 most often reported symptoms (joint and muscular pain, headaches, skin itching and skin dryness).


These results do suggest that the prevalence of symptoms is more connected with the psychological and not the actual physical effects of exposure to fluoridated water.

Not surprisingly the mean number of symptoms reported was lower among those who supported fluoridation than among those who opposed it. A similar relationship occurred with people reporting that they could taste the fluoride in the water – both in November (when the water was fluoridated) and in December (when it wasn’t). The numbers reporting the taste dropped to nearly zero in March when they knew fluoridation had stopped.

One should always be suspicious of anecdotal evidence – no matter how passionately advocates of a particular cause use it.

Thanks to Ian at Making Sense of Fluoride for drawing my attention to this research.

See also:

New Zealanders for Fluoridation

Other articles on fluoridation

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14 responses to “Fluoride sensitivity – all in the mind?

  1. You say, ” I have had a few letters from anti-fluoridation activists lately assuring me they have symptoms of fluoride deficiency.

    With the greatest of respect, I would put this claim into the 100% BS file… THINK!!!! before you rush to print.



  2. Flattering to see you are such an avid reader of this blog Ron. Must have read this one very quick before my editing had finished. Still, it is wise of you to keep informed on this issue.


  3. Michal Denny

    I wonder if these people who think they have fluoride hypersensitivity have heard of the nocebo effect. Our Changing World on Radio NZ had a really interesting interview on it a few weeks ago (Thurs 8th Aug). The Finnish data would certainly support this.

    Radio New Zealnd : Our Changing World.
    In experimental studies, the power of suggestion is influencing people’s reactions to sound associated with wind turbines. http://www.radionz.co.nz/audio/player/2564966


  4. Check a variety of Material Safety Data Sheets for fluoridating agents. Some note some symptoms persisting long after fluoride exposure.


  5. Alias, I suggest you also check he safety data sheets for chlorine, soda ash, aluminium sulphate and all he other chemicals used in water treatment. In fact, check the source water used for Hamilton – the arsenic concentrations are 3 times the maximum recommended levels.

    Finally, can you not see that such after data sheets are only of relevance to people handling or transporting the concentrated chemicals. In the case of the fluorosilicates these chemicals don’t even exist in the finished water.

    The issue of safety data sheets for the cox erratic chemicals is naively irrelevant and anti-fluoridations should blush at the cynical lies they tell about them.


  6. “A material safety data sheet (MSDS), safety data sheet (SDS), or product safety data sheet (PSDS) is an important component of product stewardship and occupational safety and health. It is intended to provide workers and emergency personnel with procedures for handling or working with that substance in a safe manner, and includes information such as physical data (melting point, boiling point, flash point, etc.), toxicity, health effects, first aid, reactivity, storage, disposal, protective equipment, and spill-handling procedures. (…)
    An SDS for a substance is not primarily intended for use by the general consumer, focusing instead on the hazards of working with the material in an occupational setting.”


  7. I was waiting for someone to come up with the comparison with wind turbine syndrome.

    Unfortunately this is well documented, and really not that hard to see why having a 400ft industrial wind turbine next to your house might actually cause some health issues.

    I really don’t have any info on Flouride, but given the corruption apparent in the renewables industries, I feel little reason to trust any of these so called scientists.


  8. Yes, Andy, we know you are anti-science. No need to spell it out. You prefer to create your own reality.


  9. Fuck off Ken


  10. Ken, you wouldn’t get what science is even if I rolled it up I to a small ball and inserted it deep into your colon with a pair of forceps.


  11. Andy, did you listen to the Radio NZ interview? The point is the University of Auckland study was a double blind study and showed that people reported symptoms even when they weren’t being exposed to the sound BUT they thought they were. A classic nocebo effect


  12. Once it’s in the water it gets in everything. Wine, juice, beer, soda, vegetables, grains, etc. Here’s a list from the USDA. Most of the world has stopped fluoridating. Only about 70 percent of the United States is still being poisoned by the fluoride in the water. All sides agree to the fact that healthy kidneys can eliminate only about 50% of daily fluoride intake. The rest gets absorbed in calcified tissues, like bones and teeth. The National Academy Of Sciences (NAS) stated in 1977 that, for the average individual, a retention of 2mg/day would result in crippling skeletal fluorosis after 40 years. Dr. Arvid Caarlson, 2000 Nobel prize in medicine winner says, “In Sweden, water fluoridation, to my knowledge, is no longer advocated by anybody. In Sweden, the emphasis nowadays is to keep the environment as clean as possible with regard to pharmacologically active and, thus, potentially toxic substances.” “I am opposed to fluoridation because of the overwhelming evidence that fluoridation is not only potentially harmful but has already caused considerable, well-documented harm.” Albert Schatz, Ph.D., biochemistry, world-renowned discoverer of streptomycin (Oct., 1999) Poison should not be added to the water and I shouldn’t have to pay thousands for a reverse osmosis filter to take it out of my water. I don’t want to water my garden with it or bathe in it either. from the USDA http://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/Fluoride/F02.pdf Only a small margin separates supposedly beneficial fluoride levels from amounts that are known to cause adverse effects. Dr. James Patrick, a former antibiotics research scientist at the National Institutes of Health, describes the predicament: “[There is] a very low margin of safety involved in fluoridating water. A concentration of about 1 ppm is recommended…in several countries, severe fluorosis has been documented from water supplies containing only 2 or 3 ppm. In the development of drugs…we generally insist on a therapeutic index (margin of safety) of the order of 100; a therapeutic index of 2 or 3 is totally unacceptable, yet that is what has been proposed for public water supplies…”


  13. John, you have just repeated a list of myths you have presented elesewhere – and you obviously have no intention of listening to any single response.

    However, this article is about the way anti-fluoridationists spins stories about fluoride sensitivity.

    Such stories are not suppoorted by any evidence.

    Care to comment on that?


  14. Pingback: Declan Waugh continues his distortion of Finnish fluoride research | Open Parachute

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