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Few health issues are accepted as uncritically, at least in United States, as the addition of fluoride to drinking water. While there was initially intense opposition and vigorous debate on the issue, the concern and the debate died down over time to such an extent that the US Centers for Disease Control, in 1999, proclaimed water fluoridation one of the ten great Public Health Achievements of the 20th century.

Water fluoridation became accepted to the extent that to question it was no longer merely an academic position but risked branding oneself as a scientific illiterate or Luddite quack. This wide-spread acceptance occurred, however, even as more and more evidence began to accumulate that adding fluoride to the water supply indeed has serious, far-ranging and significant health risks.

If we take a deep breath and step back for a moment we can begin by considering whether having a clean, pure and safe water supply is important to health? Well, certainly the answer is yes, and lack of potable water is one the most significant health concerns the world over. We also know that the addition of trace contaminants, whether organic such as bacteria or viruses, or inorganic contaminants can have a deleterious effect on water's safety. It is common knowledge that the element lead when it leaches, in minute quantities, from lead lined pipes may over a period of years or decades cause chronic lead poisoning, "plumbism" as it is called. One scientist went so far as to speculate in a 1983 submission to the New England Journal of Medicine, that chronic lead poisoning, with its effects of diminished intelligence and behavioral lability contributed to the fall of the Roman Empire as the disease disproportionately affected the aristocracy and leadership class. While I can't say I agree with this author's position I would say that the purposeful addition of an element to the water supply for health purposes would need to be accompanied by overwhelming and long term evidence of benefit. Indeed, the conservative and common sense position would be to refrain from altering the water supply while purposefully adding fluoride, despite its wide spread acceptance, should be seen as the radical and avant garde position. When one considers that the purported health benefit, a reduction in the number of dental caries, is not a health issue that seems at all unmanageable or for that matter of even great concern in countries and locales where the water supply is not adulterated with fluoride, just how much safety and efficacy data would be enough to address the potential risk, and more importantly where is this data? Fluorine itself is the most reactive element on the periodic table, there is no reason whatsoever to a-priori suspect that adding the sodium salt of this element to the water supply would be beneficial to health. So what data do we have on this issue?

Fortunately for us, most of the "heavy lifting" has been done on this already in the form of a thorough and well written review of the health effects of water fluoridation compiled by the National Academy of Sciences (NAS) and released in 2006. The report runs some 500 pages so it is not practical to review it all in one post, however, it is available for free on-line and in its entirety here, for anyone to follow along.

I want to skip ahead to chapter 7 on the neurotoxicy and neurobehavioral effects of water fluoridation in part because this is one area that has at this point both a great deal of published (and some unpublished research) on the topic. The NAS reviewers consider numerous human studies from China. The study they judged as having the strongest design was one looking at 512 children living in two different villages with different natural levels of fluoride in the water. The high fluoride village had an average water fluoride level of 2.46 mg/L and the low concentration village 0.36 mg/L. As an aside it is probably worth noting here that while water fluoridation generally aims for around 1 mg/L the US Environmental Protection Agency considers 4 mg/L as the threshold level for any negative health effects, I.e. anything under 4 mg/L is considered safe. In fact the NAS review was performed to make recommendations on this level and their recommendation is the EPA level needs to be lowered. Getting back to the study. The two villages were otherwise similar in the other variables tracked by the study, for instance, education level, socioeconomic status, iodine and creatinine levels, levels of lead in the blood. They also noted that neither village had significant exposure to industrial air pollution so the differences in fluoride exposure were the result of the fluoride in each villages' drinking water. While being blinded to where the children came from, an IQ test was administered to the two groups of children. The children from the high fluoride village had an average measured IQ of 92.2, the low fluoride village 100.4, a difference of 8.2 IQ points between the two villages. The researchers also found what is described as a "dose-response effect" which also strengthens the findings of the study. A dose-response effect means that as you increase the dose you see an increased magnitude of effect (i.e if you see 1 mg moderate effect, 2 mg no effect, 3 mg big effect. There is not a dose response and it is harder to be sure what the drug is doing even though the 3 mg group showed a big effect). So in this study as urinary fluoride levels were increased, there was a parallel decrease in IQ and on average, the people with greatest fluoride exposure suffered the greatest effects on intelligence.

Nor was this study an isolated or exceptional finding. A second study looked at 118 children in, again, two different villages with high (3.15 mg/L) and low (0.37 mg/L) fluoride exposure levels, the average respective IQ levels: 92.3 and 103.1. A third study looking at 160 children, high exposure village 4.12 mg/L, average measured IQ 97.7, low exposure village 0.91 mg/L average measured IQ 105.2. Note that all of the high fluoride levels in these studies were below, or nearly below, the 4 mg/L level which the EPA currently declares safe.

If this is not enough for you, the Fluoride Action Network looked at two reviews from 2008 of studies investigating fluoride and intelligence. The overwhelming majority of these studies found an association between fluoride and intelligence with some 23 human studies now reporting an association between high fluoride exposure and reduced IQ. Finally effects on intelligence are just one of many deleterious health effects from fluoride exposure. We covered about 4 or 5 pages of this 500 page report. The next pages deal with neurobehavioral changes, seen with fluoride exposure. If you look at the studies we just talked about in one the researcher notes the disproportionate presence of enamel fluorosis and skeletal fluorosis in the high fluoride cohort. Two more well categorized diseases seen with fluoride exposure.

Will talk in a later post about ways to avoid fluoride, while some exposure is unavoidable, I would just say for now, you might try reading the warning label that is present on every tube of fluoridated toothpaste.

However, considering what we know just from the studies regarding fluoride and intelligence, would you now consider water fluoridation worth the risk? As in many public health areas, Europe is ahead of us here in the United States on this issue. The majority of Europe soundly rejected water fluoridation precisely on the basis of health risks. Last I checked they aren't suffering from a devastating or uncontrolled epidemic of dental caries. I guess the Europeans are just smarter than us.

We will look now into a second disturbing finding from water fluoridation, namely its effect on behavior. Probably the most appropriate starting point for this discussion is the work of Harvard trained toxicologist Dr. Phyllis Mullenix. In the late 1980s and early 1990s Dr. Mullenix was head of the Department of Toxicology at the prestigious Forsyth Dental Research Institute. Actually, in part because of her pioneering work in using computers and pattern recognition to quantify the study of animal behavior she had been invited by the head of Forsyth to start-up the toxicology program there with a mission of looking at the toxicity of products widely used in dentistry. Much to her surprise, one of the first substances she was asked to investigate was fluoride.

Some five years would pass from her starting the toxicology department to getting around to looking at fluoride. As Dr. Mullenix has repeatedly pointed out, initially it would never have crossed her mind to even bother to investigate the toxicity of fluoride and when asked to do so she was initially uninterested in the project, hoping to get through it so as to move on to more interesting projects. As she described the situation in an interview,
Initially, the fluoride study sparked little interest, and in fact we were quite anxious to move on to something academically more exciting. Using an animal model developed for the study of dental fluorosis, we expected rats drinking fluoride-treated water would behave the same as matching controls. They did not. The scientific literature led us to believe that rats would easily tolerate 175 ppm fluoride in their drinking water. They did not. Reports in the literature indicated that fluoride would not cross the blood brain barrier. But it did. Prenatal exposure to fluoride was not supposed to permanently alter behavioral outcome. It did. Like walking into quicksand, our confidence that brain function was impervious to fluoride was sinking.
As a quick aside here, because of differences in the way rats and humans metabolize fluoride the 175 ppm in the rat's drinking water leads to a fluoride blood level that humans would see with a much lower level of fluoride in the water, a level still greater than what water fluoridation alone would produce but not out of the ball park for comparison to what humans may be exposed to. So what exactly were the findings that so caught the researcher's attention? As she details in a different interview,
The study basically found three things. First of all, that if you put sodium fluoride in the drinking water of young animals, that with time - meaning a period of weeks in a rat's lifetime - they would develop changes in their behavioral patterns. And that pattern change was a hypoactivity pattern. They became slower, 'couch potatoes' if you like. But it was definitely a hypoactivity pattern. .... I also found that if I started the exposure at a little later age, I would get the same pattern, but I would get it at a blood level of fluoride that was lower, even, than the young animals. So it suggested that, in particular females, that the older animal was more susceptible to this fluoride in the drinking water. ... we also did a prenatal study. Because I wanted to see if I could do one specific exposure in the prenatal situation giving a subcu[taneous] shot of sodium fluoride at a specific age where a certain part of the brain is developing, if the fetuses of this mother, when they grew up, if they had any type of permanent behavioral damage. And we gave the subcu[taneous] injections to the mother, we gave no other fluoride exposure, and when those pups were born and when they grew up and we tested them, they had a permanent change. And their pattern was this very distinct changes that are compatible with hyperactivity.
So when there was in-utero exposure she found it predisposed the children to hyperactivity, while exposure at later ages turned the rats into "couch potatoes" compared to the the control rats, and this effect was seen at decreasing dosages with increasing age. Along with finding these behavioral changes, Dr. Mullenix also through postmortem autopsy documented that fluoride was crossing the blood brain barrier and accumulating in brain tissue. "Just the fact that we could (find) any level of fluoride at all, when we weren't expecting the brain to accumulate any fluoride, was a very big surprise and very, very disturbing to some people, of all things, that fluoride was accumulating in the brain."

Things became truly bizarre when Dr. Mullenix began to present her findings. She started, after a request from the Forsyth center director, with a presentation to the National Institute of Dental Research a part of the NIH in Bethesda, Maryland. There she found the walls plastered with posters on the "miracle of fluoride" along with mocking descriptions of the "anti-fluoridationists". She gave the lecture to a packed room which also had a disproportionate number of public affairs people present. Despite a very hostile reception, the head of the National Institute of Dental Research followed up with a letter thanking her for the presentation, saying it needed to be looked into further and offering a number of tips for how to apply for future grant monies. She also presented her findings to the scientists at Forsyth and her results were met with, as she described it, "horror". She was told her results had to be in error and she should not publish them. She agreed that there needed to be further study but did not back away from her intent to publish. A short time later, NIH funded a televised conference for Dr. Mullenix to present her findings, within weeks of this event she was fired from Forsyth. Despite attempts at interference she did manage to get her results published in the medical literature after extensive peer review. She would never again be awarded grant money to look into fluoride toxicity.

In later years, Dr. Mullenix came to find out that her boss, Dr Jack Hein the director of Forsyth, was previously head of dental research at Colgate and was the individual primarily responsible for fluoridating toothpaste. He was a protege of a Dr. Harold Hodge, a professor emeritus at Forsyth and widely considered the foremost expert on fluoride. In a plot twist worthy of an X-Files episode, it turns out that Harold Hodge had previously worked on the Manhattan Project. Fluorine, in the form of Uranium hexafluoride, it turns out, is necessary for the enrichment of uranium for use in nuclear power or weapons. Amazingly, nearly a half century earlier Dr. Hodge had found that exposure to fluoride was causing lethargy, confusion and drowsiness in workers exposed in the Manhattan Project. At the time he specifically requested money to do studies in rats to confirm and detail the effects. All of this background was unknown to Dr. Mullenix. It seems likely that Drs. Hein and Hodge wanted an answer to the possible behavioral impacts of fluoride and when the results came back positive and Dr. Mullenix was determined to make public the findings, she was set up as the "fall guy" for the research.

One may argue with the significance of Dr. Mullenix's work, however, again it is important to keep in mind the risk/benefit scenario. Fluoride is not being used to treat a deadly disease or serious cancer. Instead, the United States is one of a minority of countries which adulterates its water supply with fluoride in the ostensible hope of decreasing dental caries. Is it worth the risk? As we will talk about later, even the efficacy of fluoride in preventing cavities is now being quite widely questioned. Of course, Dr Mullenix was studying sodium fluoride. On the other hand, only ten percent of the fluoride added to our water supply is medical grade sodium fluoride. The remainder is industrial waste, (see also here) specifically silicofluorides scrubbed from the smokestacks of phosphate fertilizer plants. There have been to my knowledge no concerning toxicity studies, in fact no toxicity studies of any sort, for these silicofluorides. Maybe that strengthens the position of those wanting to fluoridate the water supply. There have however been some studies of the results of exposure to these silicoflourides.

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In 1999 Professor Roger Masters published the results of a study of 280,000 children in Massachusetts exposed through the water supply to silicoflourides and found that, in addition to whatever damage was being done by fluoride, they also had higher average blood levels of lead than similar children in areas with a clean water supply. It would seem that the silicoflourides scrubbed as industrial waste from the smoke stacks of phosphate producing plants have different health effects than naturally occurring fluoride. As Dr Master's commented,
Data from numerous studies show that, taking economic, social and racial factors into account, where silicofluorides are used, children absorb more lead from the environment, and there are higher rates of diseases and behavioral problems associated with lead poisoning (including hyperactivity, substance abuse, and violent crime)
The findings of Dr. Roger were confirmed in a more recent 2007 study by Coplan et al which found that fluoridated communities had about twice as many children on average with blood levels of lead above the toxic level of 10 micrograms/dL as compared to similar non-fluoridated communities.

A doctoral thesis by Johannes Westendorf from 1975 provides some insight into the differences between silicofluorides and sodium fluoride. Unlike sodium fluoride, he found that silicofluorides did not dissociate completely into their constituent ions in water. This issue has been hotly contested by scientists on both sides of the debate. The proposed mechanism for decreasing dental caries depends upon fluoride dissociating into ionic form, while non dissociated silicofluoride might be expected to have a different toxicity profile than ionized silicofluorides. Westendorf did find that, when compared on a molar basis, silicofluorides are some six times more potent than sodium fluoride in inhibiting the enzyme acetylcholinesterase. The rather conservative National Association of Science (NAS) reviewers in their discussion of this finding note that, "At high concentrations, agents with this capability (acetylcholinseterase inhibition) are frequently used in insecticides and nerve gases". The NAS review goes on to discuss that decreasing acetylcholinesterase enzyme function might be associated with dementia and decreases in cognitive function. If there is a silver lining to these findings, it is that intelligence and mental function are not static values, therefore if one is no longer exposed to a substance like fluoride which interferes with acetylcholinesterase enzyme function one might hope that both IQ and mental functioning would return to their normal healthy levels.

It has been speculated for some time that aluminum may play a role in the development of Alzheimer's dementia. For instance, it has been known for some time that aluminum is neurotoxic, while pathological examination of the neurofibrillary tangles that are characteristic of Alzheimer's disease show the core of the tangles to contain aluminum. Finally, a number of population based studies have found an association between development of Alzheimer's disease and environmental exposure to aluminum. In this light, a number of animal studies which have looked at the administration of sodium fluoride combined with aluminum and found that fluoride appears to potentate aluminum toxicity, either because the aluminum fluoride complexes are themselves more toxic or because fluoride allows aluminum to more easily pass through the blood brain barrier, are worrisome. Varner et al note that the pathological changes seen in rats given fluoroaluminum closely resemble those of Alzheimer's dementia. The studies by Varner at al were concerning enough that both the Environmental Protection Agency and the National Institute of Environmental Health Sciences called for further research to be performed in this area. It does not help matters that aluminum, like fluoride, is often added to treated water supplies to improve appearance. This is not mentioning the widespread adoption of aluminum drinking cans. I hate to imagine what a six pack of bud light(TM) made with fluoridated water and packaged in aluminum cans does to cognition.

One might wish to downplay the significance of these animal studies or their findings despite the highly credentialed researchers involved and the very orthodox approach to the research and the review process before publication of the research. And yes, the findings may lead to a dead-end, it is at least possible that fluoride, silicofluorides and aluminum may play no role in cognition, contribute to the epidemic of Alzheimer's disease facing the world or cause any other health problems. I would only ask an even more basic question, in light of what is published in the peer reviewed medical literature, do you think the EPA and other regulatory agencies have any responsibility to do any toxicity studies whatsoever on the silicofluorides scrapped off the smokestacks of Florida phosphate plants seeing as we currently put these industrial waste derived silicofluorides in our water supply?

Well, we are about half way through this subject, and still have only scratched the surface. As you might gather from the NAS review, fluoride also has known effects on the skeletal system, the reproductive system, the endocrine system and others. Moreover, aside from causing the disease of dental fluorosis there are serious questions as to whether fluoride has any effect in reducing rates of dental carries. In future installments we will look into these issues as well as the question of how to decrease your exposure to fluoride.
"We would not purposely add arsenic to the water supply. And we would not purposely add lead. But we do add fluoride. The fact is that fluoride is more toxic than lead and just slightly less toxic than arsenic."Dr. John Ambiance