I 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.
Other articles on fluoridation