Tag Archives: Perrott

Fluoride Debate: Why I support fluoridation – 2nd response from Connett

This is Paul Connett’s second response to Ken Perrott’s original article – Fluoride debate: Why I support fluoridation In it he is responding to Ken’s article Fluoride Debate: Why I support fluoridation – response to Connett.

 I am going to ignore most of the personal criticisms in Ken’s response to my critique of his opening statement and focus largely on the science and scientific studies in question.

 1. Different interpretations of the Li et al. (2001) paper

I am very familiar with the Li et al. (2001) paper on bone fractures in the elderly in six Chinese villages with fluoride concentrations in well water ranging from about 0.25 to 8 ppm.  In fact, I reviewed a pre-publication copy of this paper sent to me by the lead author as part of my invited peer review of the York Report (McDonagh et a., 2000).

Had Ken taken advantage of my sending him the full pdf text of our book he would have quickly seen that the charge he levels at me of selectively using the Li et al (2001) text on bone fractures from China is grossly inaccurate.

Instead of relying on the misleading commentary of pro-fluoridation activist Kurt Ferre, he could have read Chapter 17 of our book (The Case Against Fluoride, CAF), where we covered both parts of Li’s paper. The part Ken and Ferre cover, shows a U-shaped curve for all fractures combined. This shows a minimum for fracture rate at the village at 1 ppm. It could be argued – as Ken does – that at 1 ppm fluoride may confer some benefit in strengthening of elderly bones after a lifetime of exposure. However, such an argument is somewhat muted by the second part of Li’s paper that deals with hip fractures, which is the most critical bone fracture for elderly people, since about half of the elderly never regain an independent existence after such a fracture. In this part of the study there is no U-shape – i.e. no apparent protection offered by fluoride against hip fracture – and the hip fracture prevalence appears to increase in a linear fashion above 1 ppm (actually maybe from 0.25 ppm).

This systematic increase becomes more apparent when one checks our re-plot of the data– see Figure 17.2 on p.179.


Please note I say replot because the graphs provided by Li et al (2001), including the one used by Ken, are not real plots at all. They are only illustrative. The points on the x-axis neither represent an average of the fluoride concentration in each village nor the estimated dose (mg/day) calculated by the authors, the six data points are simply evenly spaced out to illustrate which village is being represented for the fracture data on the y-axis. In the case of Figure 17.1 it makes little difference when one puts in the average dose in mg/day, but in the case of Figure 17.2 it makes a big difference and shows up this “apparent” linear trend more clearly.

While Ken is correct when he says that the only individual village to show a statistically significant increase in hip fractures is village 6, based on our replot the increases in villages 4 and 5 appear to be “real,” even though they are not statistically significant individually. In fact, the data for the whole set of villages appear consistent with a linear regression. Statistical significance is not the final word on whether a data point or data set is real or not. In our view, a linear increase in fracture rate for villages 3 through 6 (and maybe even villages 1-6) looks a more reasonable interpretation of the data than a threshold (i.e. a sudden tripling of the hip fracture rates) at village 6, the interpretation that Ken prefers.

It is unfortunate that Ken uses an inaccurate commentary from Ferre to mischaracterize what we did here.

2. Other studies of fluoride and the bone

 However, there is a great deal of literature available on fluoride’s impact on the bone (see the references to Chapter 17, CAF). Ken will need more than the Li et al (2001) paper to establish that there is an overall benefit to the elderly bone when people are exposed for a lifetime to an approximate ten-fold increased exposure to fluoride via artificially fluoridated water. This is especially true for people with poor kidney function and high water drinkers (miners in Western Australia drink between 10 and 12 liters of water a day). Can you provide more studies that support the possibility that fluoride protects the elderly bone Ken?

Nor is it just the bones of the elderly that is in question.  I am still waiting to see Ken’s response to the finding in the Schlesinger et al (1956) study of the second fluoridation trial (Newburgh-Kingston, NY, 1945-55) in which they reported a statistically significant increase in the prevalence of cortical bone defects (the ratio was about 2 to 1) in children in the fluoridated community versus the non-fluoridated community. The cortical bone is the outside lamellar structure of the bone whose integrity is important in resisting fractures.  We discuss Schlesinger’s work in CAF (p.96).

I am not aware of any health agency in any fluoridated country comparing fracture rates in children in fluoridated versus non-fluoridated communities or even examining fracture rates in children as a function of the severity of dental fluorosis. Scientists did this in Mexico (Alarcón-Herrera et al., 2001) and found an increase in fractures as the severity of dental fluorosis increased (see P.169, CAF). No attempt has been made to reproduce this result or conduct a similar study in any of the fluoridated countries.

3. Fluoride’s topical action and saliva

 As far as the mechanism of fluoride’s topical mechanism on the teeth is concerned, Ken quotes the CDC from 2001,

” . . drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride  dental products can raise the concentration of fluoride in saliva present in the mouth 100-to 1,000-fold. The concentration returns to previous levels within 1–2 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization.”

I went back to this CDC Oral Health Division statement from 2001 and found the sentences that preceded Ken’s quote most revealing.  These preceding sentences read:

“Saliva is a major carrier of topical fluoride.  The concentration of fluoride in ductal saliva, as it is secreted from salivary glands, is low – approximately 0.016 parts per million (ppm) in areas where drinking water is fluoridated and 0.006 ppm in nonfluoridated areas (27).  This concentration of fluoride is not likely to affect cariogenic activity. However, drinking fluoridated water, brushing with fluoride toothpaste… 

These few sentences further strengthen Ken’s arguments that it is fluoride delivered directly into the mouth that provides the saliva with concentrations, which may or may not do something and not, the meager concentrations reached systemically through the salivary gland, a position I erroneously attributed to him. My apologies.

As the CDC states the concentration of fluoride delivered by the saliva gland “is not likely to affect cariogenic activity.” However, if it is the fluoride levels reached when fluoridated water has entered the mouth that is the key dynamic for fighting tooth decay, then I think this weakens the need to force people to drink fluoridated water. Maybe we should be suggesting that people swish with fluoridated bottled-water and then spit it out! I also have to wonder why we are giving fluoridated water to babies before their teeth have erupted.

Let me ask for the third time how Ken feels about an alternative delivery system for fluoridated water. This would involve using fluoridated bottled-water in one-liter bottles at 0.7 – 1.2 ppm. These could be made freely available in dental offices (supermarkets, pharmacies or clinics). With this approach one could a) use pharmaceutical grade sodium fluoride; b) could control the dose and c) avoid not forcing it on people who don’t want it. Nor does it involve giving up the central paradigm of the fluoridation program.

As far as the rest of the 2001 CDC quote is concerned I think the Oral Health Division is using a slight of hand here by mixing up a discussion of fluoride in food and water with the fluoride in toothpaste. That 100-1000 fold increase might take place when toothpaste containing 1000 or even 1500 ppm is used but is hardly likely with water at 0.7- 1.2 ppm.

I think the CDC put the “cat among the pigeons” among both fluoridation opponents and proponents when it admitted in 1999 that:

“Fluoride’s caries-preventive properties initially were attributed to changes in enamel during tooth development… However, laboratory and epidemiologic research suggest that fluoride prevents dental caries predominantly after eruption of the tooth into the mouth, and its actions primarily are topical…” (CDC, 1999).

It maybe that the CDC Oral Health Division in its 2001 paper was scrambling to salvage some kind of role for fluoridated water, sufficient to justify continuing its long-time support and promotion of the fluoridation program, despite its admission of the predominance of a topical effect.  However, It would have been better if, in 1999, the CDC had changed the focus of its efforts from delivering fluoride systemically to delivering it topically, as well as addressing other key issues of diet, regular brushing and providing early interventions for children of low-income families.

In the latter respect I do not understand why Ken completely ignored the exciting news that I provided from unfluoridated Scotland, where they are having great success with teaching toothbrushing to infants as well providing better diets and earlier interventions.

As far as the mechanisms that Ken offers for a topical benefit derived from fluoridated water directly to the saliva in the mouth (and not via systemic exposure), he discussed “fluoride ions transferring from the water (or food) to saliva (and biofilms on the teeth).”

My experience when drinking water is that it hits the tongue, the back of the top front teeth and the palate before it swiftly goes down the gullet (unless it is deliberately swished). It seems to me that the fluoride ions have little opportunity to form a biofilm on any teeth other than the back of the front teeth. Nor is there much time to mix with the saliva. But this is only conjecture based on simple personal observations on my part and if Ken has a study that shows the level of fluoride in the saliva is dramatically increased immediately after someone has swallowed a glass of water that would be very helpful.

4. The work of Xiang et al (2003) on IQ

Ken suggests that I am “cherry picking” the data by “singly pulling out the Xiang et al. study from 2003.” In actuality, I gave that as a specific example of a human study where effects were found at concentrations very close to the level at which we artificially fluoridate (0.7 to 1.2 ppm). This was in response to Ken’s claim that he was not impressed by all the high concentration animal studies that have found fluoride causes harm. I cited Xiang in the larger context of 37 (out of 46 human studies that have found an association between fluoride exposure and lowered IQ.) These studies come from India, Iran, Mexico and China, with the majority coming from China.  27 of them were reviewed by a Harvard team (Choi et al., 2012). Of these 27 studies 26 found a lowering of IQ (average of 7 IQ points). These results are remarkably consistent even though they have been performed in several different countries and many different parts of China. However, proponents of fluoridation have dismissed them on the basis that in two of these studies the range in the high fluoride village went up to 11.5 ppm.  However, I pointed out that nine of the studies found a lowering of IQ at or less than 3 ppm, which offers no adequate margin of safety for a whole population drinking water in the range 0.7 to 1.2 ppm.  So I wasn’t cherry picking here. We have to see Xiang’s work in the context of all these other studies as well as the other studies that show that fluoride is a neurotoxicant (discussed below). I chose Xiang’s study because it is one of the better studies. It controlled for more potential co-founders than others (including lead and iodine intake). Recently, Xiang has confirmed that as far as arsenic was concerned there were higher levels in the low fluoride village, so clearly arsenic was not a factor in the lower IQs found in the high fluoride village.

Yes, there are weaknesses in many of these IQ studies but the greatest “weakness” is the fact that countries that practice water fluoridation have made virtually no attempt to reproduce them or pursue the matter in any way. That is why, as Ken complains, I have not quoted studies from a wider range of countries: apart from a small early study in NZ (Shannon et al., 1986) and small behavioral study in the US (Warren et al., 1998) there aren’t any. At the very least these studies from China, India, Iran and Mexico represent a serious red flag on this practice and the health agencies in fluoridated countries are ignoring this red flag.

In his further attempt to downplay Xiang’s 2003 study Ken asks

“Why did the authors choose to publish in the journal “Fluoride?” It is certainly not considered of high quality. It is actually rather suspect because of the ideological committment of the editors. This gives the impression that even suspect papers will be published if the story is right.”

I discuss these derogatory comments about Fluoride and its editors, and the double standard that Ken and other proponents of fluoridation exercise on this matter below, here I would like to discuss more about Xiang’s work.

5. Xiang and the journal Environmental Health Perspectives

Xiang almost certainly chose to publish in the journal Fluoride because it has probably given more coverage to the possibility that fluoride affects the brain of animals and lowers IQ in humans than any other journal in the world.

That being said if Ken is going to make judgments based on what journal the article appears in, then he might be interested by the fact that in 2010 Xiang et al submitted an updated version of their work to one of the leading environmental health journals, Environmental Health Perspectives, which is published by the National Institute of Environmental Health Sciences (NIEHS) a division of the National Institute of Health (NIH). After peer review this journal agreed to publish Xiang’s work and posted a pre-publication copy on the internet (see Xiang et al., 2010).

However, Xiang was asked to withdraw his article for the technical reason that some of the material had already been published by this team (and that was the Fluoride article from 2003). But the key fact from the point of view of this discussion is that despite Ken’s criticisms Xiang’s work was peer-reviewed by this prestigious journal and was found acceptable for publication.

The update from Xiang was very important for this discussion and it is a pity that this was withheld from the mainstream scientific community.  Xiang found that the lowering of IQ in his study correlated with the fluoride levels in the children’s plasma. This greatly strengthens Xiang’s finding by moving from a population (or ecological) study closer to a study based on individual exposure. Xiang finally published this part of his finding in Fluoride (Xiang et al., 2011).

Despite all of this, Ken considers Xiang’s paper  “a minor piece of evidence” and argues that,

“it should be objectively considered together with all other publications in this area of research. The fact that it is taken in isolation (except for a few other low quality Chinese studies), and nothing of higher quality or from different regions is considered, makes me suspicious. After all, a number of countries with highly qualified scientists (and activists claiming negative effects) have had many years to look at possible health effects from fluoridation. The fact that more credible papers are not produced is hardly good evidence for the claims made by anti-fluoride activists. Why would they rely on low quality research if better research supporting their claims was available?”

First of all, I argue that this study by Xiang is part of a large body of work that indicates that fluoride can damage the brain and I have summarized this large body of work previously  (and it can be found at www.FluorideAlert.org/issues/health/brain )

So when Ken argues that “Papers are selected and then values are pulled out of them to make assertions or claims that really are not warranted – and certainly not by a balanced reading of the literature.”

I must ask Ken what “balanced reading of the literature” on fluoride’s potential to damage the brain are you talking about?  I have cited a large body of work and it almost all goes in one direction: fluoride is a potent neurotoxicant. Can you cite an extensive body of literature Ken that points in the opposite direction?

 6. Fluoridated countries are not doing studies on key health concerns

 Sadly, as I have already indicated the health agencies in those countries that support and promote fluoridation show absolutely no inclination to study their populations with respect to this effect, i.e. lowered IQ.

In fact the scientist who published one of the earliest animals studies on fluoride and animal behavior, Dr. Phyllis Mullenix, was fired after her paper was accepted for publication (Mullenix et al., 1995). Mullenix was the chairperson of the first toxicology department in any dental school in the US. She was hired specifically to look at the neurological effects of the chemicals used in dentistry.  However, when she found changes in animal behavior related to fluoride exposure and published it, she was told that her work was “no longer relevant to dentistry.” I would argue that her work conflicted with dental establishment’s determination to continue the fluoridation program at all costs. The treatment meted out to Mullenix did not go unnoticed by members of the research community, who have treated doing research on fluoride like touching the third rail as far their careers were concerned.

In addition to their lack of interest in pursuing the lowering of IQ, neither health agencies nor those “highly qualified scientists” Ken talks about, have been inclined to fully investigate many other serious concerns such as lowered thyroid function, accumulation in the pineal gland (Luke 1997, 2001), arthritis rates in fluoridated populations, bone fractures in children (discussed above), earlier onset of puberty, behavioral problems in children and the plight of those who claim to be highly sensitive to fluoride’s toxicity.

All these concerns cry out for attention and certainly the attention of those critical of the epidemiology of studies conducted in those countries that are investigating some of these issues because they are legitimately concerned about what naturally fluoridated water is doing to their citizens.  I have expressed my own thoughts on the reason for this lack of attention, but I would be interested in Ken’s thoughts on  this overwhelming lack of scientific interest in investigating fluoridation’s potential health effects in the many years since the US Public Health Service endorsed fluoridation in 1950? Why in fluoridated countries are we getting an endless stream of studies on teeth but virtually none on other tissues in the body?

7. What other authorities are saying about fluoride as a neurotoxicant

Meanwhile, I am not the only scientist who is expressing concerns about fluoride’s neurological affects. According to the report by US National Research Council (NRC, 2006):

“A few epidemiologic studies of Chinese populations have reported IQ deficits in children exposed to fluoride at 2.5 to 4 mg/L in drinking water. Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence.” p.8

(Note from PC: this comment was based on a review of only five of these IQ studies, there have now been 42.)

“On the basis of information largely derived from histological, chemical, and molecular studies, it is apparent that fluorides have the ability to interfere with the functions of the brain and the body by direct and indirect means.” p.222

“histopathological changes similar to those traditionally associated with Alzheimer’s disease in people have been seen in rats chronically exposed to AlF.” p.212

“Fluorides also increase the production of free radicals in the brain through several different biological pathways. These changes have a bearing on the possibility that fluorides act to increase the risk of developing Alzheimer’s disease.” p.222

“More research is needed to clarify fluoride’s biochemical effects onthe brain.” p.222

“The possibility has been raised by the studies conducted in China that fluoride can lower intellectual abilities. Thus, studies of populations exposed to different concentrations of fluoride in drinking water should include measurements of reasoning ability, problem solving, IQ, and short- and long-term memory.” p.223

“Studies of populations exposed to different concentrations of fluoride should be undertaken to evaluate neurochemical changes that may be associated with dementia. Consideration should be given to assessing effects from chronic exposure, effects that might be delayed or occur late-in-life, and individual susceptibility.” p.223

EPA researchers listed fluoride among those chemicals for which there was  substantial evidence of developmental neurotoxicity”  (W. Mundy et al. http://www.epa.gov/ncct/toxcast/files/summit/48P%20Mundy%20TDAS.pdf

The EPA headquarters scientists made this request to the U.S. Senate in 2000 (Hirzy 2000):

“We ask that you order an epidemiology study comparing children with dental fluorosis to those not displaying (fluoride) overdose during growth and development years for behavioral and other disorders.”

And according to Dr. Philippe Grandjean, one of the authors of the Choi et al (2012) study:

“Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain. The effect of each toxicant may seem small, but the combined damage on a population scale can be serious, especially because the brain power of the next generation is crucial to all of us.” (Harvard Press Release)

As such it seems reckless to me – and many others – that we should knowingly increase the whole population’s exposure to this neurotoxicant by putting it into the public water supply.

Meanwhile, according to my son Michael Connett, who is the special project director at FAN, and compiled FAN’s Health Database, research on fluoride and the brain in animals has been rolling in at a steady pace over the past year — with over a dozen new studies, including some at notably low doses. One such study that is worthy to have on the radar is a study on mice by Liu et al, 2013. It reports that exposure to fluoride in drinking water (at 5 and 10 ppm) 4 weeks after weaning not only impaired cognition, but caused “anxiety- and depression-like behavior” as well. Here’s an excerpt from the discussion:

“Almost all existing epidemiological surveys on areas with high-fluoride drinking water have focused on cognition; however, our data suggest the need for a large-scale epidemiological survey to investigate whether drinking water with high levels of fluoride can lead to human emotional behavior changes. In summary, we found developmental fluoride exposure through drinking water 1) caused cognitive impairment and 2) led to anxiety- and depression-like behavior in adult mice. Therefore, consideration should be given to the neurotoxicity of fluoride used to combat dental caries, and attention should be paid to the concentration and dosage of fluoride, especially in young children. Our data suggest that excessive fluoride intake should be avoided to prevent its adverse effects.”

So the weight of evidence that fluoride impacts both the brain of animal and humans keeps piling up. About the only animal study that proponents can produce that has not found an effect is one performed by Whitford et al., 2009, who used behavioral tests on rats.  They found no neurotoxic effects in their study setting. The study is limited because the rats were not dosed in utero or even during earliest post-natal development, but only after they had been weaned, which roughly translates to adolescence in rats.

Even if this had been a strong animal study, it is one of a small minority that found no evidence of neurotoxicity of fluoride.  So, taking the scientific evidence on this topic as a whole, the weight of evidence from both animal and human studies is that fluoride is a developmental neurotoxicant.

8. The journal Fluoride and the ISFR

In his commentary on Xiang’s IQ paper Ken chose to do what a number of proponents of fluoridation do and that is to try and trash the journal Fluoride.  He claims that Fluoride “is certainly not considered of high quality. It is actually rather suspect because of the ideological commitment of the editors.”

Why is it Ken you see proponents’ support of fluoridation as being “scientific” and opponents’ opposition to fluoridation as being “ideological”? Isn’t it possible that opponents of fluoridation are opposed for scientific reasons?

Fluoride is the only journal in the world, which is completely devoted to research on fluoride in many different areas of study (geological, biological, biochemical, toxicological, epidemiological, medical and dental to name a few). To its discredit the US National Institute of Health (NIH) has refused to cover the contents of this journal in PubMed, thus depriving many researchers valuable information on fluoride’s toxicity. This has been particularly true of depriving the mainstream medical community (many of whom use PubMed as their primary research tool) knowing about the extensive database indicating that fluoride is a neurotoxicant. It has done this despite covering the contents of far lesser journals and even trade magazines.

There have been three editors of Fluoride since it began its quarterly publication in 1968: Dr. George Waldbott, Dr. John Colquhoun and Dr. Albert Burgstahler (who passed away a few weeks ago). You would be correct in asserting that each of these editors was opposed to fluoridation, however that opposition was rooted in science not some ill-defined ideology. I think you can get a glimpse of the caliber of both Dr. George Waldbott and Professor Albert Burgstahler in the book they co-authored “Fluoridation: The Great Dilemma.” (Coronado Press, Lawrence, Kansas, 1978).

I met Dr. John Colquhoun (briefly before he died in 1998) and videotaped an interview with him during to trip to NZ.  I count this interview one of the great moments of my scientific career. Never have I been more impressed by someone’s character than I was by John. He had been an avid promoter of fluoridation both as the chief dental officer of Auckland and as a city councilor. When during a world tour in 1980 (he went to Australia, Asia, North America and Europe) he found that talking behind the scenes to leading dental researchers  that they were not finding much of difference between tooth decay in fluoridated and non-fluoridated communities and found the same in “confidential reports” from the NZ dental authorities on his return, he had the enormous courage and scientific integrity to come out publicly against water fluoridation and spent the rest of his life trying to right the wrong he had done. But while he was at the reins he never hesitated to allow pro-fluoridation voices and articles to be published in Fluoride.

I worked with professor Albert Burgstahler for many years and I can vouch for his scientific integrity. In fact for me he represented one of the pinnacles of scientific integrity and that is why FAN named an annual award in his name.

I never met Dr. Waldbott, but I know that his position was that neither the journal nor its supporting organization (the International Society for Fluoride Research, ISFR) should adopt a formal opposition to fluoridation (and its membership included both pro and anti-fluoridation scientists), but to publish as much science as they could on the subject – and as far as water fluoridation was concerned from both sides – and to let the chips fall where they may. He and his successors also believed that if the science was aired fully and openly it would lead most independent scientists to an anti-fluoridation position.

9. The double standard

 Unfortunately, none of the dental journals have adopted the same openness on this issue. By and large they do not entertain any anti-fluoridation editorial or even a review that conflicts with their mantra that fluoridation is “safe and effective.” So I think Ken is exercising a double standard here.

I should also point out that there have been several occasions where dental journals have gone out of their way to publish papers that have provided an “ideological” as opposed to a “scientific” support for one side of a controversial matter. Take the example of osteosarcoma. In 1991, shortly after the 1990 NTP animal study had found an association in male rats between fluoride exposure and osteosarcoma, the Journal of the American Dental Association (JADA) rushed to give prominence (i.e. the front cover was devoted to it) to an article, in which the authors clearly reveal their bias in favor of fluoridation. In this very small epidemiological study they proposed that far from causing osteosarcoma fluoride was actually protective against it (see P.187 in The Case Against Fluoride, CAF).

I think the following comments reveal a greater sensitivity to the need to protect the fluoridation program than protecting a few young boys from a life threatening disease:

“An incorrect inference implicating systemic fluoride carcinogenicity and its removal from our water systems would be detrimental to the oral health of most Americans, particularly those who cannot afford to pay for increasingly expensive restorative dental care . . .Because of its strengthening action, fluoride has been widely accepted as the responsible agent for the dramatic declines in the tooth decay rates of U.S. children and adolescents . . . A disruption in the delivery of fluoride through municipal water systems would increase decay rates over time . . . Linking of fluoride ingestion and cancer initiation could result in a large-scale defluoridation of municipal water systems under the Delaney clause. (McGuire et al., 1991, quoted on p. 187, CAF).

In my view the commentary (above) plus the JADA editors’ choice to give it this article full-front page coverage is an example of “ideology” not science at work.  The authors and the journal both had a need to protect the fluoridation program at all costs – even if it meant downplaying the concerns about the fate of the young boys in question. I will pick up the osteosarcoma story again in a later submission.

10. A request to Ken

 Finally, Ken I think it would save us all a lot of time if – putting the rhetoric and your general disdain for the opponents of fluoridation to one side – you would be kind enough to list the primary studies that you have read that have most convinced you that fluoridation is both safe for the bottle-fed baby and for the adult over lifelong exposure.


 Alarcón-Herrera et al., 2001. “Well Water Fluoride, Dental Fluorosis, Bone Fractures in the Guadiana Valley of Mexico,” Fluoride 34, no. 2 (2001): 139–49


CDC, 1999. Centers for Disease Control and Prevention, “Achievements in Public Health, 1900–1999: Fluoridation of Drinking Water to Prevent Dental Caries,” Mortality and Morbidity Weekly Review 48, no. 41 (October 22, 1999): 933–40, http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4841a1.htm

CDC, 2001. Centers for Disease Control and Prevention, “Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States,” Morbidity and Mortality Weekly Report 50, no. RR14 (August 17, 2001): 1–42, http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5014a1.htm

Choi AL, Sun G, Zhang Y, Grandjean P. 2012. Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Environ Health Perspect 120:1362–1368.

Connett, P., Beck, J and Micklem HS. The Case Against Fluoride. Chelsea Green, White River Junction, Vermont, 2010.

Harvard School of Public Health. (2012). Impact of fluoride on neurological development in children. July 25. Available online at: http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/

Hirzy, 2000. Statement of Dr. J. William Hirzy, National Treasury Employees Union Chapter 280 before the Subcommittee on Wildlife,

Fisheries and Drinking Water, United States Senate. June 29, 2000.

Li, Y et al., 2001. “Effect of Long-Term Exposure to Fluoride in

Drinking Water on Risks of Bone Fractures,” Journal of Bone and Mineral Research 16, no. 5 (2001): 932–39.

Liu F. et al., 2013 (online) (hard copy 2014). “Fluoride exposure during development affects both cognition and emotion in mice.” Physiology & Behavior 124 (2014) 1–7.

Luke, J, 1997, “The Effect of Fluoride on the Physiology of the Pineal Gland,” PhD thesis, University of Surrey, Guildford, UK, 1997. Excerpts at http://fluoridealert.org/studies/luke-1997/ and a complete copy of Dr. Luke’s dissertation can be downloaded at http://www.fluoridealert.org/wp-content/uploads/luke-1997.pdf  (with the author’s permission).

Luke, J, 2001.  “Fluoride Deposition in the Aged Human Pineal Gland,” Caries Research 35, no. 2 (2001): 125–28.

McDonagh et al., 2000. “Systematic Review of Water Fluoridation,” British Medical Journal 321, no. 7265 (2000): 855–59, http://www.bmj.com/cgi/content/full/321/7265/855  Note: The full report that this paper summarizes is commonly known as the York Review and is accessible at http://fluoridealert.org/re/york.review.2000.pdf

McGuire et al, 1991. “Is There a Link between Fluoridated Water and Osteosarcoma?” Journal of the American Dental Association 122, no. 4 (1991): 38–45.

Mullenix, PJ et al., 1995. “Neurotoxicity of Sodium Fluoride in Rats,” Neurotoxicology and Teratology 17, no. 2 (1995): 169–77.

Morgan, L. et al. 1998, “Investigation of the Possible Associations between Fluorosis, Fluoride Exposure, and Childhood Behavior Problems,” Pediatric Dentistry 20, no. 4 (1998): 244–52.

NRC, 2006. Fluoride in Drinking Water: A Scientific Review of EPA’s Standards (2006) http://www.nap.edu/catalog.php?record_id=11571

NTP, 1990. National Toxicology Program, “NTP Technical Report on the Toxicology and Carcinogenesis Studies of Sodium Fluoride (CAS no. 7682-49-4) in F344/N Rats and B6C3F1 (Drinking Water Studies),” Technical Report 393, NIH publ. no. 91-2848, National Institutes of Health, Public Health Service, U.S. Department of Health and Human Services, Research Triangle Park, NC, 1990.

E. R. Schlesinger, D. E. Overton, H. C. Chase, and K. T. Cantwell, “Newburgh-Kingston Caries-Fluorine Study XIII. Pediatric Findings After Ten Years,” Journal of the American Dental Association 52, no. 3 (1956): 296–306.

Shannon, FT et al., 1986.  “Exposure to Fluoridated Water Supplies and Child Behaviour,” New Zealand Medical Journal 99, no. 803 (1986):416–18.

Waldbott, GL,  Burgstahler,AW  and H. L. McKinney, Fluoridation: The Great Dilemma (Lawrence, Kansas: Coronado Press, 1978).

Whitford, GM et al. 2009. “Appetitive-based Learning in Rats: Lack of Effect of Chronic Exposure to Fluoride,” Neurotoxicology and Teratology 31, no. 4 (2009): 210–15.

Q. Xiang, Y. Liang, L. Chen, et al., “Effect of Fluoride in Drinking Water on Children’s Intelligence,” Fluoride 36, no. 2 (2003): 84–94, http://www.fluorideresearch.org/362/files/FJ2003_v36_n2_p84-94.pdf

Q. Xiang, Y. Liang, M. Zhou, and H. Zang, “Blood Lead of Children in Wamiao-Xinhuai Intelligence Study” (letter), Fluoride 36, no. 3 (2003):198–99, http://www.fluorideresearch.org/363/files/FJ2003_v36_n3_p198-199.pdf

Xiang, Q. et al., 2010. “Serum Fluoride Level and Children’s Intelligence Quotient in Two Villages in China.” Environmental Health Perspectives. EHPonline.org

Xiang, Q. et al. 2011. “Analysis of children’s serum fluoride in relation to intelligence scores in a high and low fluoride village in China.” http://www.fluorideresearch.org/444/files/FJ2011_v44_n4_p191-194_sfs.pdf

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride Debate: Why I support fluoridation – response to Connett

This is Ken Perrott’s response to Paul Connett’s first criticisms of Ken’s article Fluoride debate: Why I support fluoridation – Response from Connett.

For Ken Perrott’s original article see – Fluoride debate: Why I support fluoridation.

First this issue of science and citations? Yes, my last article was general and concentrated on the philosophy of science and social aspects – both of which are important to me and central to why I support fluoridation.  But Paul seems not to have appreciated or understood my first section on scientific aspects so I will develop part of that, the nature of fluorine in apatites, further here. I will throw in a few citations just to keep Paul and my other critics happy (more on the use of citations later).

Apatites contain structural fluoride

I briefly referred to the nature of apatites and the occurrence of fluoride as a natural constituent. Paul seems not to get this as he again refers to fluoride as something external, and not a natural, normal, part of apatites. He is mistaken in his belief that I claim “that fluoride is needed to react with our bio-apatites and make them stronger, less soluble and in the case of teeth less vulnerable to tooth decay.” (My stress).

I don’t claim that at all. I argue that apatites, including bioapatites, are not pure end members such as hydroxylapatite, but naturally (and normally) contain species like F and carbonate as part of their structure. isomorphous substitution of these species for phosphate and oxygen occur during formation of the apatite compounds. This isomorphous substitution of F for O strengthens the apatite and lowers it’s solubility compared with the hydroxylapatite end member. Carbonate substitution for phosphate can have an opposite effect – things are never simple so there is a balancing act which makes isomorphous substitution of fluoride even more important. The bioapatites in our body contain both F and carbonate as normal, natural components (see figure below). The  incorporation of ions like fluoride into bioapatites can change their solubility product by several orders of magnitude according to Driessens (1973). Planer at al (1975) attributes the improved stability of bone to “the isomorphous substitution of fluoride in the apatite structure.”

(None of this denies the the negative effects of excessive fluoride intake on our bones and teeth).


This is why Wopemka and Pasteris (2005) argue “the apatite phase in bone should not be called hydroxylapatite.” This is also the reason why there are “limitations to the use of the stoichiometric mineral hydroxylapatite as a mineral model for the inorganic phase in bone.” I second this and find unfortunate the simplification we often see in more general texts where bioapatites are discussed as if they were the end members hydroxylapatite or fluorapatite rather than an intermediate hydroxyl-carbonate-fluoroapatite of somewhat variable composition.

The fluoride we ingest is involved in the formation of bioapatites right from the beginning. This is why we see increased risks of weakened bones and teeth when dietary fluoride intake is insufficient. It can also be lost from actively growing bones and other bioapatites when fluoride intake is reduced. See Kurland et al (2007) for an example of the reverse of fluorosis (probably caused by surreptitious ingestion of toothpaste) once fluoride inputs had been reduced.

Understanding the complex nature of bioapatites and the effect of composition on structure and strength is important to appreciating the role of ingested fluoride on producing healthy bones and teeth. Unfortunately this aspect is often neglected, or purposely overlooked or hidden, when attention is concentrated on the mechanism of surface reactions of fluoride with existing teeth in inhibiting tooth decay.

However, some researchers are stressing that the beneficial effect of fluoride arises from effects of ingested, or systemic, fluoride on pre-eruptive teeth as well as surface reactions on existing teeth. Newbrun (2004), for example, stressed in a review of the systemic role of fluoride and fluoridation on oral health:

“The role of systemic fluoride in caries prevention is neither “minimal” nor “of borderline significance.” On the contrary, it is a major factor in preventing pit and fissure caries, the most common site of tooth decay. Maximal caries-preventive effects of water fluoridation are achieved by exposure to optimal fluoride levels both pre- and posteruptively.”

I will now discuss those surface reactions.

Topical confusion once again

Having dealt with this issue twice now (admittedly only briefly) I am surprised Paul could interpret my understanding of the beneficial role of fluoride on teeth as requiring:

“the need to put fluoride in the drinking water so after passing through the whole body it ends up in our saliva and that this is the delivery system which reduces tooth decay.”

I have never claimed that at all. Still, local anti-fluoride activists accuse me of this despite my many specific refutations. Paul’s characterisation of the “topical mechanism” is common among such activists and, as I said in a previous article, an example of a bait and switch fallacy.

Earlier this year I wrote about the so-called “topical” mechanism and the way it was being misrepresented by anti-fluoride activists in two articles – Fluoridation – topical confusion and Topical confusion persists. I will just repeat myself a bit here to clarify.

The US Center for Disease Control describes this “topical” or surface mechanism in its  report Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States:

” . . drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride  dental products can raise the concentration of fluoride in saliva present in the mouth 100-to 1,000-fold. The concentration returns to previous levels within 1–2 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization.”

So let us be clear, they are referring (in the case of fluoridated water) to fluoride ions transferring from the water (or food) to saliva (and biofilms on the teeth). There is no assumption that the salivary fluoride must come only from ingested fluoride after “passing through the whole body.” The latter, of course happens, but contributes a smaller amount. There are literature reports that this lower concentration can also contribute to the “topical” mechanism – but I am not myself advocating that as necessary.

The diagram below portrays this – the fluoride is going directly from the drink and food into the saliva:

Tooth decay occurs because when the pH at the tooth surface is lowered (this happens when bacteria decompose sugars and other carbohydrates) some of the calcium and phosphate in the bioapatite at the tooth surface dissolves – mineralisation. With time the pH increases and the reaction is reversed – calcium and phosphate ions at the tooth surface reform as a solid hydroxylapatite surface phase (remineralisation). The acidity (or pH) is an important factor in the dissolution and prtecipitation fo apatites.

When fluoride is present at the tooth surface a fluorohydroxyapatite is formed in the surface phase. This is “harder” – it doesn’t dissolve as readily. Consequently the incorporation of fluoride into the tooth surface reduces mineralisation – and enhances remineralisation. It inhibits tooth decay.

Fluoride in fluoridated water and food does this very effectively. Because we drink and eat often, dietary forms of fluoride help to maintain a useful concentration of saliva fluoride over time.

Topical application methods (toothpastes and dentrifices) are a supplement to fluoridated water and dietary fluoride, but not a substitute – partly because they are not applied as often (if at all). However, dentrifices and dentist’s fluoride treatments may cause formation of CaF2 globules on the tooth surface (because of the high F concentration) which then slowly release their F over time to maintain saliva concentrations at an appropriate level (see the  review article Mechanisms of Action of Fluoride for Caries Control by Buzalaf, Pessan, Honório, and ten Cate JM (2011)).

The “topical” or surface mechanism which operates with fluoridated water is effective because it is regular (much more regular that topical application methods) and this helps maintain fluoride concentrations in saliva and tooth biofilms are effective levels.

Incidentally, this is also a reason water fluoridation is an effective social health policy.  It means that the whole population can and does access the “topical mechanism” without thinking about it (as is required with toothpaste, mouth rinse and dentist fluoride treatments).

In summary, science supports both a systemic and a surface (“topical”) role for the beneficial effects of fluoridated water.

Benefits for bones

Paul asks for “scientific evidence that interaction [of fluroide] with the bones is beneficial.” As I described above that question actually misrepresents the situation. It is not the interaction with bones that is important but incorporation into bones during their formation and growth. Fluoride does not have to “react with our bioapatites,” as Paul puts it. The fluoride is a component of the bioapatites – See first figure above.

There are numbers of scientific papers that can be cited to show a beneficial role for fluoride in bones. I will just refer here to  Li et al (2001) (full text here) because it does offer a useful graphic demonstration of that beneficial effect – in this case of the overall incidence of bone fractures. Figure 2 from this paper shows that the incidence of fractures is lowest at concentrations similar to that used for water fluoridation, with increased incidence at both lower and higher concentrations.

Incidentally, one of our commenters Kurt Ferre draws attention to the fact Paul Connett is aware of this paper – at least he referred to it in his 50 reasons to oppose fluoridation where Paul notes:

” One very important study in China, which examined hip fractures in six Chinese villages, found what appears to be a dose-related increase in hip fracture as the concentration of fluoride rose from 1 ppm to 8 ppm (Li 2001) offering little comfort to those who drink a lot of fluoridated water. “

Actually the study did not show what Paul claims –  “a dose-related increase in hip fracture as the concentration of fluoride rose from 1 ppm to 8 ppm.” The particular data relates to overall fractures, and not hip fractures. And rather than demonstrating “a dose-related increase” it just shows a significant increase  in the 4.32 – 7.97 ppm group when compared with the 1.00 a 1.06 ppm group.

But really he should have mentioned the significant increased incidence of fractures in the 0.25 – 0.34 ppm group (to the same incidence as at 8 ppm) as this is consistent with a beneficial role for fluoride at around 1 ppm.  It demonstrates the negative effects of deficient intake of fluoride.

This brings us to the next issue – the selective approach to scientific literature and use of citations.

Approaching the literature – purposely or objectively

One thing that sticks out like a sore thumb when Paul and other opponents of fluoridation cite research papers is the predominance of studies from China and India. And the journal Fluoride, which is not considered a high quality journal by the scientific community, is often cited.

Just on the possibility of chance we might expect a better representation of countries of origin of the research, and of journals. I believe this demonstrates a selective approach to the literature.

If you wish to promote a pet theory or way-out idea it is possible to find a “scientific” citation to support it. All you need is Google and a fair bit of confirmation bias. The latter is a normal problem for all of us – if we have a stong committment to an idea we can usually find some handy citations to support it (and ignore those that don’t). On top of that we can interpret those papers (or more likely just their titles or abstracts – who bothers to read the full text?) to fit in with our ideas.

It is just so easy to make any argument look “sciency” using citations these days. And who bothers checking them? A good proportion of readers seem to be convinced just by the presence of citations. (Or unimpressed by the lack of them – Paul described my last article as “very, very short on science”  because “surprisingly you gave no scientific citations at all.”)

So citations do get thrown around a lot in this discussion – often in a meaningless and thoughtless way. As for their interpretation – in my articles Fluoridation – are we dumping toxic metals into our water supplies? and Fluoridation – it does reduce tooth decay I give examples from the local anti-fluoride activist web site FANNZ where cited sources are claimed to say the opposite of what they do say! (It always pays to check citations from ideologically motivated sources like this – I certainly do now).

Fortunately working scientists usually have the discipline of peer review and continual critique of their findings and idea by their scientific community. This encourages an ethos of objectivity and consideration of all the relevant literature – not just the cherry-picked stuff. Yes, this is difficult and never works perfectly but that discipline certainly helps.

An honest approach requires one to approach the scientific literature more objectively and intelligently than anti-fluoridation activists (or activists in general) do. A conscientious approach requires that readers critically assess studies, recognise problems and realise the need to get an overall picture – not a selected one.

I wont deal with the IQ issue, and attempts of fluoridation opponents to implicate fluoride in the “dumbing down” of the population, at this stage because Paul has indicated he will be covering it in a future article. But here are a few comments on the paper of  Xiang et al (2003) which illustrates how Paul places a lot of confidence in a cherry-picked citation.

  1. Why did the authors choose to publish in the journal “Fluoride?” It is certainly not considered of high quality. It is actually rather suspect because of the ideological committment of the editors. This gives the impression that even suspect papers will be published if the story is right. My point is that if I had some credible findings in fluoride chemistry and wished to present a paper to the scientific community for their consideration Fluoride is the last journal I would choose.
  2. If I was reviewing this paper for publication I would certainly call on the assistance of a skilled statistician as reviewer and would probably recommend changes as a result. I would ask the authors to clarify their figure 1 and its interpretation as well as explaining the meaning and significance of their “BMC” and “BMCL” and an estimation of the errors in their valaues.
  3. Xiang’s paper is a minor piece of evidence – surely it should be objectively considered together with all other publications in this area of research. The fact that it is taken in isolation (except for a few other low quality Chinese studies), and nothing of higher quality or from different regions is considered, makes me suspicious. After all, a number of countries with highly qualified scientists (and activists claiming negative effects) have had many years to look at possible health effects from fluoridation. The fact that more credible papers are not produced is hardly good evidence for the claims made bo anti-fluoride activists. Why would they rely on low quality research if better research supporting their claims was available?

Yet Paul uses Xiang’s paper to authoritatively claim it had “found a threshold at 1.9 ppm for this effect.” (What effect he refers to is unclear.) How reliable is that figure of 1.9 ppm (actually 1.85 or 2.32 ppm F in the paper) –  considering the huge variation in the data points of the Figure 1? (Unfortunately the paper is not a lot of use in explaining that figure – reviewers should have paid more attention.)

This is the problem. Papers are selected and then values are pulled out of them to make assertions or claims that really are not warranted – and certainly not by a balanced reading of the literature.

Disadvantaged children

Having experienced the reality of social disadvantage I am still cynical of many people who claim sympathy. Too often as a child I was blamed for problems I had no control over or told things would be OK when I knew they wouldn’t. My experience showed me that most of those social workers, teachers and health practitioners just had no concept of the reality of my position. How could they – unless they had experienced it themselves.

Things are probably a lot better today – but I am still cynical of many of these assertions.

I feel the same cynicism and helplessness when opponents of fluoridation like Paul Connett  agree on “the need to help disadvantaged children” – and then follow that declaration with arguments about hypothetical situations showing absolutely no idea of the reality of life for disadvantaged children.

Paul suggests my advocacy of fluoridation policies will trap families. “What for example are parents in low-income families supposed to do if they don’t want their children to drink fluoridated water?” – he asks. Well, if he really cared – what about the children suffering horribly from toothache whose parents really don’t have the luxury, the interest or feelings of choice, to think about the details of the water supply they use? It is the plight of those children which sparks my empathy.

Sure, there are a few disadvantaged or low-income families who face decisions involving priority of freedom of choice over social policy. The Catholic families who must find resources to send their children to fee-charging Catholic  schools and not  secular public schools. Or the  religious fundamentalists who refuse to use public hospitals. These people do find the resources if their specific minority freedom of choice issue is really important enough to them. We don’t deny the advantages of secular schools and public hospitals to the rest of society just because of the ideological foibles of a small minority.

The resources required to avoid a public water supply are much smaller and should not be used as an argument to deny the advantages of a social health policy to the rest of society.

Yes, children from disadvantaged backgrounds may well have problems with bad nutrition as well as poor oral health. So let us help them. Let us not deny them the beneficial effects of a well established beneficial social oral health policy on the pretence that it might enhance issues related to poor nutrition. Let’s not even  worry about such a cynical diversion – why not do something about that poor nutrition instead?

I find the idea of refusing a beneficial social health policy to children because somebody has it in their head that it might enhance the problems of poor nutrition very cynical and anti-human. It shows a complete lack of empathy for socially and economically disadvantaged families and their children. It is an argument for standing by and doing nothing. And I am not impressed by Paul’s reliance on reports from India where  high natural levels of fluoride do present problems – a situation very different to those in New Zealand and the US considering the fluoridation issue.

Sorry if I come across harshly on this issue – it is important to me, raises strong feelings in me  and I have seen too many examples of false concern and complete lack of empathy to suppress those feelings. I just think people who raise hypothetical “freedom of choice” issues to oppose beneficial social health policies really have no idea of what it is like for disadvantaged children and their families – or any empathy for their situation.

Nature and focus of debate

I think Paul and I have different concepts of what an exchange of scientific opinion should be like. We discussed this in our initial negotiations and our different approaches were obviously not resolved.

Paul expressed a wish that our exchange be focused on his own arguments, and indeed be limited to, and focused on, the issues raised in his book. I rejected this, arguing this was a discussion between equals. We each have our own points to make, our own data, experience and arguments, and we should do so. Anyway this is a public exchange with involvement of readers who are following the articles and commenting on the issues raised. We are really both aiming our arguments at our readers, not each other.

I do not think either of us should require that the other has one arm tied behind their back in entering an exchange like this. I certainly could not, in good faith, enter into such an “exchange” or “debate.”

Paul was kind enough to send me an electronic copy of his book – I thank him for this. I may review the book (which was highly recommended to me by a few local anti-fluoride activists) when I can find time. The book has also been useful for me in making specific criticisms of his arguments. But at no time have I agreed to limit my part of the exchange to the book.

I can appreciate Paul is proud of his book and therefore wishes to promote it. I can also understand why local opponents of fluoridation also promote the book. But he cannot legitimately demand that my part of the exchange be limited in the way he suggests. It is not my job to sell his book.

A general comment on the use of books in science. Books rarely get the degree of peer review of journal articles, can often be dominated by authors’ biases or hobby horses, and are generally somewhat dated in their content. Hence researchers prefer citing research papers to books. Again, while it is understandable Paul should promote his book to health authorities and experts in NZ, surely he can appreciate that researchers  might not give it the same authority they give research papers. Or have the same high opinion of the books the authors’ naturally have.

In fact, along these lines, I understand that local researchers suggested that Paul submit his work on fluoride, or the reviews of others’ research, to a reputable journal for peer review and publication. I understand he has not responded positively to that suggestion yet.

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride debate: Why I support fluoridation – Response from Connett

This is Paul Connett’s response to Ken Perrott’s article – Fluoride debate: Why I support fluoridation.

I think your opening statement certainly gives us a perspective from where you are coming on this issue Ken and that is helpful.

I am very glad that you put “having an open mind” and “relying on science” as your key tools for resolving controversial issues like fluoridation. I believe that once you have got over some negative impressions that you have had with some people opposed to fluoridation, that you will find that having an open mind and relying on the best science will inevitably lead you to rejecting fluoridation and to see it as the misguided practice it is. But we shall see.

As far as the case you present I find it very, very short on science. Basically you argue that fluoride is needed to react with our bio-apatites and make them stronger, less soluble and in the case of teeth less vulnerable to tooth decay. You offer no scientific evidence that interaction with the bones is beneficial and can be achieved without damage to the bone or the connective tissue.

Your case as far as the teeth are concerned seems to boil down to the need to put fluoride in the drinking water so after passing through the whole body it ends up in our saliva and that this is the delivery system which reduces tooth decay. Two questions: 1) Why do you feel that this is more rational and suitable than treating the tooth enamel more directly with topical treatments like fluoridated toothpaste?  2) If you reject topical treatment for some reason and you insist the fluoride must be swallowed to be effective why don’t you use a more appropriate way of delivering fluoridated water, i.e. in one liter bottles at 1 ppm and prepared with pharmaceutical grade sodium fluoride?

I asked this latter question at the end of section 1A but in your response you did not answer. So may I ask it again?  Would not this delivery system provide, 1) a better control of the dose, 2) a far better control over the purity of the chemical used and 3) would not force this human treatment on people who don’t want it. Nor would it involve giving up on the central dogma of water fluoridation. Surely this would be a win-win situation for everyone?

On the ethical front, you stress the need to help disadvantaged children. No argument there from me. But what if your chosen method actually further disadvantages these children and their families? What for example are parents in low-income families supposed to do if they don’t want their children to drink fluoridated water? Haven’t you trapped these families with this policy? Moreover, are you not aware of the extensive literature from India that fluoride’s toxic effects are more serious for people with poor nutrition (low protein, low vitamins and low calcium – see the early work from Pandit et al., 1940 and the more recent animal studies from Chinoy, NJ – see the FAN bibliography for full citations, http://fluoridealert.org/researchers/fan-bibliography/)? Aren’t children in disadvantaged communities more likely to have poor nutrition?

Scotland, which has no fluoridation, has found a simple and cost-effective alternative way of fighting tooth decay as this recent BBC Scotland report indicates ( http://fluoridealert.org/news/nursery-toothbrushing-saves-6m-in-dental-costs/):

 “A scheme to encourage nursery children to brush their teeth has saved more than £6m in dental costs, according to a new study.

Childsmile involves staff at all Scottish nurseries offering free supervised toothbrushing every day.

Glasgow researchers found that the scheme had reduced the cost of treating dental disease in five-year-olds by more than half between 2001 and 2010.

The programme was launched in 2001 and costs about £1.8m a year.

It emphasises the importance of toothbrushing and helps parents establish a healthy diet from the earliest stage.

A number of nurseries and schools in targeted areas also provide fluoride varnish and toothbrushing in primary one and two.

An evaluation, funded by the Scottish government and carried out by Glasgow University, found that fewer children needed dental extractions, fillings or general anaesthetics as a result of the programme.

‘Less toothache’

There was also said to be a drop in the number of children needing hospital treatment for dental problems, freeing up operating theatres.

Public Health Minister Michael Matheson said: “This is an amazing achievement and shows just how much can be saved from a very simple health intervention.

“This has seen less tooth decay in children which means less toothache, fewer sleepless nights and less time off school.

“By this simple measure, NHS costs associated with the dental disease of five-year-old children have decreased dramatically.

“More children can just be treated routinely in the dental chair because they need less invasive treatments, so fewer fillings and fewer extractions, and many more children with much better oral health than we have seen in many years.”

For the second time you state your concerns about, “Unwarranted extrapolation from studies done at high concentration” which you say are “a dime a dozen and worthless in this debate.”

Last time you brought this up I responded by showing that several human IQ studies were not done at high concentrations. For example, in nine of the 27 IQ studies  reviewed by Choi et al (2012), the high fluoride village was at 3 ppm or less. I also went into more detail on the study by Xiang et al. (2003a,b) who found a threshold at 1.9 ppm for this effect.

In my discussion on this point I stressed the difference between concentration and dose and the need to consider a margin of safety calculation to protect for the full range of expected sensitivity or vulnerability in a large population when extrapolating from a small human study of a fairly homogeneous population. Thus extrapolating from Xiang’s study we find that there is absolutely no margin of safety to protect either for the range of exposure to fluoride in an American or NZ population or for the full range of sensitivity expected in any large heterogeneous population. This latter calculation is particularly important for your major concern – disadvantaged children – because that is almost certainly where you will find the most vulnerable in this regard.

When we embarked on this exercise I thought that this was going to be an exchange between yourself and me, but I am finding that you do not want to restrict yourself to my arguments but want to argue against all the arguments thrown at you by people opposed to fluoridation. That has a place of course but it was not what I was expecting. In my view it serves to distract and muddy the waters.

I wish you had taken a more disciplined approach and focused entirely on the arguments I have put forward. In this respect it is unfortunate that when you were educating yourself on this issue you did not take advantage of reading the book I co-authored with two other scientists, James Beck, MD, PhD and Spedding Micklem, DPhil (Oxon). There we spelled out the case in a cool, calm and collected way with every argument backed up with citations to the scientific literature. As you know – but your readers may not – I sent you a pdf copy of this text. By so doing, I had hoped that we could keep this debate tightly focused; that I could defend my own arguments (and there is plenty enough of those) and not have to keep considering those of others.

Your readers might also not know that shortly after this book was published (Oct 2010) I was invited in early 2011 to meet with staff of the Ministry of Health in Wellington. About 20 people were there from the Ministry and some of their advisers. I carefully went through the arguments in the book and asked them at the end of my presentation to provide a written response to the book showing where I was wrong and providing the science that supported their critique. I added that if they could not do this with all the resources and personnel at their disposal then they should not continue to promote this practice. After nearly 3 years I still have not received that written critique.  Meanwhile, personnel from this Ministry, including the Minister himself, continue to promote the practice and even accuse opponents of distorting the scientific arguments – with no specific examples to which someone like myself could respond.

Blanket condemnation of opponents gets us nowhere. Nor does it help to keep knocking down straw dummies. The debate will only be seriously engaged when the proponents begin to put forward and defend the studies that have convinced them that fluoridation is both effective and safe – and safe for everyone. This is what opponents like myself have done. This was what I was expecting from you Ken when you got the opportunity to put forward your case. Surprisingly, you gave no scientific citations at all.  Hopefully, these will come later.

Rather than take up any more space at this point I will wait for part 2 of your case, where I hope you will present some science to support this practice.

While you are doing this I will prepare my response to your response to my section 1A.


Choi et al., 2012. Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Environ Health Perspect 120:1362–1368.

Pandit et al., 1940, Endemic Fluorosis in South India, Indian Journal of Medical Research 28, no. 2: 533–58.

Q. Xiang, Y. Liang, L. Chen, et al., “Effect of Fluoride in Drinking Water on Children’s Intelligence,” Fluoride 36, no. 2 (2003): 84–94, http://www.fluorideresearch.org/362/files/FJ2003_v36_n2_p84-94.pdf .

Q. Xiang, Y. Liang, M. Zhou, and H. Zang, “Blood Lead of Children in Wamiao-Xinhuai Intelligence Study” (letter), Fluoride 36, no. 3 (2003):198–99, http://www.fluorideresearch.org/363/files/FJ2003_v36_n3_p198-199.pdf .

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride debate: Why I support fluoridation

So far, our exchange has only covered some arguments against fluoridation and responses to those arguments. Some readers feel we should have started with me advancing the arguments for fluoridation. For example one commenter, Alison, said

“readers haven’t had the opportunity to see the basic arguments favoring fluoridation as you see them. . . . we are genuinely perplexed about why this practice has continued and honestly and sincerely trying to further or understanding.”

Paul Connett made a similar remark in his last article:

“promoters of fluoridation should not be surprised that some people are trying to come up with a rational explanation for why certain governments are behaving  so irrationally promoting this practice.”

I can’t understand why anyone should be perplexed or think fluoridation is irrational. But I am happy to give my reasons for supporting fluoridation – but remember it is a personal perspective as I can’t speak for everyone who supports it. My perspective derives from several issues that are important to me – the science, defence of science against anti-science elements, social concerns and the provisional nature of knowledge.

Scientific acceptance of fluoridation

We have many advantages in New Zealand, despite our social, economic and political problems. The climate, our scenery, our people (who are generally open-minded, liberal and accepting), agriculture and food. But our agriculture and food, and the rest that depends on these, has only really been possible because of the application of science to solve problems with the land we inherited.


New Zealand agriculture dependent on science and correction of deficient micro-elements. Phot credit: Farm Forestry NZ

New Zealanders accept the need to correct nutrient and micro-element deficiencies because we realise their importance to our place in the world. The correction of cobalt deficiencies in our central volcanic region of the North Island/Te Ika-a-Māui had huge economic returns. We also took steps to correct other important deficiencies like molybdenum, copper and selenium. Discovery of the role of fluoride in oral health, and that we had a deficiency which needed correction, was hardly a surprise to us. Nor did most of us find the solution unusual.

In the mid 1960s I worked at Soil Bureau, DSIR, outside Wellington, and remember some of the early discussions around fluoridation – there was some debate then about the possible role of the micro-element molybdenum, rather that fluoride, in limiting tooth decay. Later my research developed further into the nature of phosphate and it’s reactions in soil and the fluoride story really made sense. I became aware that the primary minerals of phosphate in soils were apatites which had fluoride as a natural constituent. This small amount of fluoride imparted important properties to the apatites – lowering their solubility and increasing their hardness which helped prevent weathering losses.

So it is understandable I could see how fluoride improved oral health (bones and teeth are bioapatites). In my research reading I also found many dental research papers were very useful. Looking back I can, for example, remember the discovery like of the role of fluoride in inhibiting dissolution of apatites by a surface reaction in partly acidulated rock phosphate fertilisers. This  parallels similar discoveries about the role of surface reactions of fluoride in saliva inhibiting tooth mineralisation and reducing tooth decay.

So the efficacy of fluoridation as a social health measure was a no-brainer as far as I was concerned. But about 10 years ago I had a sort of road to Damascus moment about the political issues when working on a research project involving fluorosilicic acid. My analysis of this material (the same used in New Zealand for water fluoridation) revealed the concentrations of contaminants like arsenic were very low – contrasting sharply with the claims of activists campaigning against fluoridation (whose story I had sort of accepted till then). That left me with a healthy respect for evidence, and a corresponding suspicion of ideologically motivated activists, in these sort of public debates involving scientific issues.

Defence of science

I guess most scientific researchers have, at some stage, to meet the activity of anti-science sympathisers and activists. Evolutionary  biologists have a permanent battle defending their science against creationists. There has been huge political pressure imposed on climate scientists. Surprisingly, even scientific researchers in agriculture periodically face this problem. Quacks selling snake oil seem to be able to find a market with farmers selling alternative fertilisers, etc., just as they can on health issues. Ideology also intrudes, with debates over organic farming and use of chemicals in agriculture.

Often these conflicts are not simply black and white. The last two examples are complex. There is a role for organic farming and there is certainly need to lower chemical inputs into agriculture. These issues get sensibly debated and have there own scientific support. But agricultural scientists have often had to face the problem of more highly motivated and ideologically driven detractors with more extreme views.

These anti-science people and groups can often be very effective politically and will skilfully use the mass media and the new social media – blogs, Twitter and Facebook. Very few scientists have experience with, or a liking for, this form of public relations and easily lose such media debates. Scientists don’t willingly get their hands dirty in such public relations battles. It is interesting to speculate why – but that is a subject for another time. One barrier I was aware of during my career was the limits and control placed on individual researchers by their institution. Institutional politics often over-ride the freedom of researchers to defend their work and take part in social debates about it. institutions encourage scientists to keep their heads down when attacked and not retaliate. The institutional fear of such social engagement possibly results form fears of legal action.

I am now retired and this has at least one advantage – freedom from institutional constraints. Mind you, if a retired scientist is involved with paid consulting, advocacy or lobbying, then they have another form of constraint  which is probably more direct and rigid than that imposed by a research institute. Because consulting, advocacy and lobbying usually need prior committment to an idea, product or policy  – payment is made for endorsement or justification and not research.

In my case I have not had to rely on such extra income so have had the freedom to explore my interests, and express my opinion without censorship or control. I have enjoyed the freedom to read and  research ideas and to follow my nose in a way intensive paid research does not allow because it is so focused.

Inevitably I have been attracted to some of the more controversial areas – controversial politically, not necessarily  scientifically. Such as the religion-science conflict, evolution, climate change and, more recently, fluoridation. I have participated in on-line debates on these issues, and about 7 years ago started this blog. None of this would have been possible while I was employed, or if I had got into paid consulting or advocacy during my retirement.

Despite my interest in the chemistry around the fluoridation issue I did not get involved in any public discussion until earlier this year. My city, Hamilton, held a referendum in 2006 which overwhelmingly supported fluoridation. I was aware  the issue was coming up again and assumed we would have another referendum this year. That was OK by me – but, like many Hamiltonians, I was shocked to hear in June that the local council had decided to stop fluoridation without a referendum. Yes, they held hearings beforehand and had last year reversed their decision to send the issue to referendum again – but most citizens were just not aware of this going on. Many of us felt it was done behind our backs.

In New Zealand decisions on fluoridation are left to local councils –  because they are the ones managing the treatment plants. Most councils really don’t feel they should be making those decisions – that this should be the responsibility of central government and health ministries. However, that is the way it is.

While other decisions on water treatment don’t go to referendum, or get decided by councils, fluoridation attracts controversy – there have been regular campaigns by activists opposing fluoridation. I don’t think citizens think councils should make decisions about health and science – that is not their job. Councils should instead reflect the views of the community on such issues. Personally, I think if a community opposes fluoridation that should be enough. While I accept that the person in the street does not understand the science (why should they) and may be prone to chemophobia or misinformation, if they are so inclined it should not be imposed.

In the end sensible citizens will take advice on such issues from scientific and health experts – not local council politicians.

So I guess my interest in the political issue was sparked off by what I saw as a violation of democratic rights. As I reacted and started to comment on line and write to councillors about the injustice I became more and more aware of just how badly the science around this issue was being distorted by anti-fluoride campaigners. So, we had a repeat of the evolution and climate change debates. There was a battle about the science behind fluoridation and I had to get involved.

As with these other issues a strong motivation for me is the integrity of science. The need to challenge and expose distortions about the science. But fluoridation is also an ethical and social health issue which raises a human rights motivation for me. In particular I find some of the hostility towards fluoridation repugnant because it demonstrates a complete lack of understanding of what life is like for the economically and socially disadvantaged in our society. In fact, it often demonstrates a complete lack of empathy for their situation.

Social concerns

This not the place for discussing the details (and that is very difficult anyway) but I come from a socially deprived  background and have some understanding of what it is like for people caught in such social and economic traps. I believe more people are actually in that situation than political activists, or politicians in general, realise. Partly because socially and economically disadvantaged people are usually incapable of advocating for their interests, and partly because the rest of society prefers to turn a blind eye, or to otherwise deny the problem.

But these problems exist, and they affect all of us. If a section of society cannot reach its potential for social, economic and psychological reasons that affects us all. It often means more people dependent on state social and financial help. Fewer people getting the education and becoming the experts needed to make our society better. These problems increase the health costs which end up being pad by us all through our taxes.

Social health policies, like fluoridation, are actually very cost-effective. They help reduce what the whole of society must pay in their absence. Probably more important from my perspective, they are humanitarian. They help rescue children and adults from otherwise hopeless situations.

Poor oral health is a huge burden for the individual. Toothache is unbearable for children, who do not have the power to ease their situation. In later life the inevitable cosmetic consequences affect the individual socially. Destroying their confidence, inhibiting their employment and other social opportunities.

Believe me, I am just as big an advocate for personal freedom of choice as the next person. But in the real world this needs to be balanced against social good. To dogmatically stress one at the cost of the other is just political extremism. And this is rejected by most people in today’s democratic, empathetic and pluralistic society. Most people accept that social health programmes benefit the whole of society, financially and ethically.

Provisional nature of knowledge

I have not dealt here with any of the many arguments used against fluoridation. This was meant to be a positive article, dealing with the argument for this practice. I expect it will bring out many of the arguments against fluoridation in the comments and response and I can respond to them then.

I don’t wish to ignore the criticisms of fluoridation – far from it. But I do want to make my own judgements on them intelligently and critically. I think that is the correct scientific approach. And my own experience has taught me that criticisms can be wrong, ideologically  motivated or just plain untrue. The example of the claimed contaminants in hydrofluoric acid illustrates this.

I also recognise that humans are not really a rational species, more a rationalising one. Confirmation bias is a natural result of the very human activity of pattern seeking. We are all prone to logical fallacies, selective viewing, and biased interpretation. Scientists are no exception, but at least the scientific ethos  of demanding evidence, checking ideas against reality and submitting conclusions and theories to the critique of ones peers help to to reduce (but not eliminate the problems),

Ideology and strong convictions get in the way of intelligent and critical assessments. Personally I think this problem is rife among anti-fluoride activists. They are a socially and ideologically diverse group but philosophies of alternative health, alternative medicine and treatments, opposition to establishment ideas for its own sake, conspiracy theories of one sort or another and a long-term component of extreme right-wing politics are all present. In saying that I am not denying the many honest and sensible people who may have concerns about fluoridation for one reason or another. Hopefully it is the latter group which will engage in discussion here.

I am definitely ready to honestly assess the criticisms and arguments made by opponents of fluoridation – especially if presented in good faith and a non-hostile way. One thing that a career in scientific research teaches is that we are often wrong. Discovery is about making mistakes, discovering one has been wrong, seeking further evidence and adjusting one’s ideas and theories. I can recall situations where experimental results have proven me wrong and I felt enthused because that mistake, and my discovery of it, opened things up to new discoveries. In effect, whether we personally intend it or not, scientists do experiments with the express purpose of proving themselves wrong. After all, the best experimental evidence one can offer for a dearly loved theory is one that would test it properly and show it wrong if that is the case.

That is why I have chosen the name Open Parachute (“your mind doesn’t work if it is closed”) for the blog and adopted the slogan – “if you have not changed your mind in the last few years – check your pulse, you may not be alive.”

I am certainly open to changing my mind about fluoridation. But that change will need evidence, good evidence. And honest, intelligent interpretation of that evidence.

So criticise what I have written here. Present your arguments against fluoridation. But please do so in good faith. I am not going to be convinced by name calling or hostility. Unwarranted extrapolation from studies done at high concentration are a dime a dozen and worthless in this debate. And misrepresentation of the literature is counter-productive because I do like to check. I have seen too many examples of distorted interpretation and misinformation to take such assurances on trust any more.

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride debate – I get email

address-angry-customer-email-200x200From time to time I get personal email from readers who are upset by articles. I don’t know why they bother – surely it would be more effective to put their arguments in the comments section which are read by others and have more effect. I am certainly not going to get into one-to-one discussions with such correspondents.

As you might expect, emails from irate opponents of fluoridation are not a novelty. However, this one I received today from Bill illustrates some illusions about the debate that need correcting.

Dear Ken,

Paul has a PhD in chemistry but you appear to think he has just been released from a home for mentally disturbed people. The fact that you reference Slott shows clearly that your mental faculties need a bit of repair work. Slott would not recognise a rational argument if it jumped up and bit him! I have met Paul a few times in the last couple of decades and have no doubts about his rationality. No doubt, from your perspective, that makes my mental apparatus a wee bit suspect by your standards. The longer you carry on this very lop sided discussion with your doubtful arguments, the more anti-fluoride people will disregard your types of arguments.

Read the evidence! There is plenty of it and the scientific literature does not support your position.

Best Wishes


 So Bill, here are a few points.

  1: Why this obsession with mental issues? No, I do not think Paul “has just been released from a home for mentally disturbed people.” Whatever gave you that idea? I certainly wouldn’t be participating in a public exchange with someone I thought has such mental issues. And you are the one raising questions about your own “mental apparatus” – not me.

2: Apparently my use of links to information passed on by Steve Slott is “clear” evidence my own mental facilities need repair! Well that is a very crude attempt to divert attention away from the information contained in those links, isn’t it? Steve appears to be a mine of information on this issue and I think many readers appreciate this.

3: Paul’s PhD in chemistry is of course relevant to our exchange. So is my PhD in chemistry. We do in fact have similar academic qualifications and research background. We are both since retired. Consequently this is an exchange between equals – at least in an approximate sense.

4: Yes there is plenty of scientific literature on this subject and plenty of evidence to consider. You may have noticed that in fact we are referring to this literature and evidence.

5: You claim the literature does not supports my position. Well you are entitled to your view but it would be nice of you to back it up with some sort of evidence. What about you contributing to the ongoing discussion with some comments where you can lay out your arguments with the supporting evidence? Like other people here are doing. It is proving to be a very worthwhile exercise and I am certainly learning from many of the comments.

Bill, you seem to want us to stop this exchange of views and information on the fluoridation issue. I can assure you I see no reason to stop. I enjoy these sort of exchanges and I think the information coming out of it could be useful to others.

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride debate Part 1a – response to Connet’s response: Perrott

This is Ken Perrott’s response to Paul Connett’s article Fluoride debate Part 1a – response: Connett

I think Paul’s response illustrates some of the problems in discussions of the fluoridation issue. He shows a selective approach to data, indulges in unwarranted extrapolation from research and misinterprets scientific knowledge to fit his own agenda. In the interests of maintaining interest by avoiding repetition, I will just select a few of the more obvious examples in my response.

It is pointless to continue debating definitions of fluoride as a medicine – as I have said the argument is largely semantic. people who wish to pursue the argument should do so in a court of law.

Irish oral health data.

Paul dismisses the data I presented showing the difference between fluoridated and unfluoridated areas in Ireland because he “would not exclude the researcher’s bias influencing the result!” That is an incredible statement  because the source of the Irish data in my plot was exactly the same as that used in the plot of Cheng et al (2007) which Paul and many other campaigners against fluoridation constantly use to argue that fluoride does not contribute to the observed improvement of dental health!

In the figure below I have added the data for Ireland from Cheng et al’s diagram to illustrate this. Cheng et al used the mean WHO values for Ireland (the dotted line), (and only two data points for each country) while I simply used the data for both people from fluoridated and unfluoridated areas.


I am not impressed by Paul’s contradictory attitudes to the same data set. It displays a biased attitude driven by his wish to conclude that fluoridation has not had a beneficial effect on oral health.

I am also amazed that Paul should argue that with the Irish data it “would have been more impressive and more appropriate to have compared the health status of” the Republic of Ireland and Northern Ireland.

Surely comparison of the data from unfluoridated and fluoridated areas  within a country introduces far fewer confounding factors than comparison of data for separate countries. History, culture,  ethnic differences, differences in dental practice and assessments, and many other factors would contribute.

Paul shows some awareness of the problem of confounding factors when he refers to the noise in a large data set specifically in referring to Cheng et al’s original plots. Yet he seems to want to increase this noise, the influence of confounding factors, in the case of Ireland and rejects an example where confounding factors have been reduced. He then implies that it is the researchers who are “biased!”

The idea that somehow inter-country comparisons should have less noise than comparisons made within a country seems so obviously wrong to me I was pleased to find I am not the only person who sees this problem. Robyn Whyman in his report Does delayed tooth eruption negate the effect of water fluoridation? puts it well:

“Studies that appropriately compare the effectiveness of water fluoridation do not compare poorly controlled inter-country population samples. They generally compare age, sex, and where possible ethnicity matched groups from similar areas. Inter-country comparisons of health status, including oral health status, are notoriously difficult to interpret for cause and effect, because there are so many environmental, social and contextual differences that need to be considered.”

Contamination  of fluorosilicic acid

Here Paul handed over to William Hirzy who rejected the data I presented for Hamilton city, NZ, as atypical – because the arsenic (As) concentration was so low.

See my article Anti-fluoridation study flawed – petition rejected for some background to Hirzy, his paper and the petition he organised. One of our commentors, Steve Slott, has brought to my attention that Hirzy is a “long time avowed antifluoridationist and is employed by Connett as the paid lobbyist for Connett’s antifluoridationist group, FAN.”

In the table below I include data from 2 other certificates of analysis – in these cases Australian produced material. I also include my own data from a batch I analysed about 10 years ago when I was researching the chemical. This suggests the Hamilton sample is not that atypical, for our region anyway.

Concentrations (ppm) of contaminants in several different batches of fluorosilicic acid

Toxic Element Impurity
 Hamilton City** Incitec 08  Incitec 09 Own
Sb 40 <0.09 <2 <2
As 132 0.4 2.2 <2 2
Cd 40 0.11 <2 <1 <1
Cr 660 0.8 <2 <2 5
Hg 26 <0.05 <1 <0.1
Ni 264 <1 <2 <1
Pb 132 0.8 <2 <2 0.3

As you can see all the samples have a very low As concentration. Much lower than required by regulations for such materials used in water treatment. These samples do have a lot less As contamination than the ones Hirzy used in his study (typical value of 30 ppm). Maybe this represents the choice of samples in both cases, or maybe there are more sources of fluorosilicic acid in the US and some products have higher contamination of As. The fact that there are fewer plants producing fluorosilicic acid in New Zealand and Australia could be a reason for the apparently higher quality here.

I  have no way of assessing the range of As contamination in US sourced samples so don’t know how representative Hirzy’s choices are. The NSF analyses water treatment chemicals and state in their last  Fact Sheet on Fluoridation Products (2013) that only 43% of the fluoridation chemicals would have produced a detectable amount of As in the finished water (actually, because of the standard methods required – detectable in water at 10 times its maximum use level). The bar graph below shows the amounts of As measured in surveyed samples as a percentage of the USEPA regulated maximum contaminant level (MCL).


Similarly, Brown et al. (2004) (Trace contaminants in water treatment chemicals: sources and fate, American Water Works Association Journal. 96: 12, 111-125) identified the coagulation chemicals used in water treatment as far more likely to introduce contaminants than the fluoridation chemicals.

Hirzy may object because the NSF measured contaminants in terms of the finished water concentrations and not that in the concentrated chemicals. The finished water concentrations were then compared  to the regulated MCL. But that will simply reflect his objection to the current MCL values.

This raises an interesting issue and identifies a problem with Hirzy’s approach in his campaign to substitute pharmaceutical  grade NaF for fluorosilicic acid in water treatment. If the real issue for Hirzy was the As concentration he should instead have campaigned to lower the currently accepted regulations for level of contamination in fluoridation chemicals. Surely that would have satisfied his concern about the role of As in cancers – and possibly been more acceptable to authorities. If the current approved levels are too high let’s get them lowered – whatever chemical is used.

It is also interesting that the fluorosilicic acid used in Hamilton contained As contamination similar to those of the pharmaceutical grade NaF Hirzy used (typical value 0.76 ppm). He should be happy to advocate the use of material with our levels of purity in the US if his only concern is the As levels.

Perhaps we should be selling our fluorosilicic acid to the US if they cannot produce material to such standards.

Hirzy’s bandwagon is the possibility of cancers resulting from As in fluoridation chemicals. I appreciate where he is coming from and have no wish to debate that issue – it is outside my area of expertise. I can only comment that in our own situation (Hamilton City, NZ) the Waikato River source  water has about 3 times the recommended maximum concentration of As for human consumption (see Hamilton – the water is the problem, not the fluoride!). This is reduced by about 80% during treatment but still remains a bigger source of As contamination than the fluoridation chemicals – by several orders of magnitude. it would be very silly to be concerned with contamination of the fluoridation chemicals and ignore the natural contamination of the source water.

Hirzy’s political activism

Finally Hirzy’s activist bias concerns me in that it could interfere with proper assessment of the risks. It certainly makes it difficult not to be suspicious about his claims. Out of hand he rejects the NSF conclusions as “a meaningless attempt at reassuring the public.” He also similarly rejects the conclusions of the  NZ Water and Wastes Association as being “without merit.” This is derogatory to honest and active scientific and technical workers who have made the analyses, assessed the risks and drawn conclusions. Question the regulations if you must (and no regulations are permanent) but please do that using evidence, not by “poisoning the well” with such claims. Play the ball, not the man. Hirzy would object to his own work being flippantly rejected in such a way.

His use of the silly conspiracy theory that fluoridation is a way of disposing of industrial waste also raises questions of his credibility. And he is biased to claim that regulations have no “real value” because they were violated by one treatment plant!

Normal role of F in bioapatites

Paul seems to reject the concept that F is a normal constituent of apatites, including bioapatites. He argues that it is possible to have bones and teeth without fluoride. and says “that at the same level that fluorides interact with bioapatites it damages those bioapatites.”

But in the real, natural world, and not the extreme conditions of the laboratory, absolutely “pure” minerals don’t exist. Isomorphous substitution is normal and ubiquitous. Apatites only exist as end members like hydroxyapatite in unusual or laboratory situations. Fluoride and carbonate are very commonly incorporated into bioapatite by isomorphous substitution – as are some common cations.

In reality no bones or teeth are “fluoride free.” Which is just as well because they would have higher solubility and reduced strength and hardness. Sure, this might mean that it is normal for a proportion of people to have teeth with “questionable” or “very mild” forms of fluorosis. But that is a cosmetic issue (if at all noticeable) and does no harm. It has probably been a simple fact about our teeth through our whole evolution.

For the vast majority of people who have dental fluorosis (recognised by a professional) it is usually classified as “questionable” or “mild.” Real health concerns should only be raised for severe dental fluorosis. Yet anti-fluoride activists lump all those grades together and pretend that dental fluorosis is a much bigger problem than it really is.

“Topical” mechanism

We will deal with the mechanism of the beneficial role of fluoride on teeth in later articles so I will just respond briefly to Paul’s brief reference to the issue in his last article here. He claims the US Centers for Disease Control and Prevention (CDC) agrees “that the predominant benefit as far as protecting teeth is concerned is topical (rather than systemic).” (Actually, he says “concedes” and not “agrees” but this word is ideologically loaded). That is correct as far as it goes but we should remember that this is referring to existing teeth – ingested fluoride still has a beneficial role with bones and pre-erupted teeth. The word “predominant” is important. So I can’t help recognise the bait and switch tactic when, in his book, he drops the word “predominant” in his chapter summary and he says:

“For many years, fluoride was believed to act systemically to prevent caries— tooth decay—by being incorporated into the enamel of the developing teeth. However, it is now known to act topically—that is, at the surface of the tooth. Thus, the main reason for ingesting fluoride has disappeared . . .”

Again and again I find anti-fluoride people using this tactic to deny any mechanism but “topical.” They thereby purposely deny any of the known beneficial effects of ingested fluoride.

This bait and switch tactic is compounded by another bait and switch where the “topical” – referring to the reactions occurring at the tooth surface because of fluoride in saliva and biofilms – becomes a new “topical” – referring only to methods of application such as toothpaste and dentrifices. This tactic enables them to deny the beneficial roles of fluoride transferred from water to saliva during drinking, as well as that ingested.

Anti-fluoride activists pushed this misrepresentation hard during recent hearings on fluoridation at the Hamilton City Council in NZ. It had its effect when the Council took on itself to issue a leaflet giving oral health advice. This repeated the “topical” misinformation. Health and dental experts were publicly very critical of the leaflet and Hamiltonians felt embarrassed by the Council’s hubris.

Fluoridated toothpaste only complements, does not substitute for, this regular “top up” of saliva F during drinking and eating.

Perhaps we should be referring to “surface” mechanisms rather than “topical” ones as the latter is so easily seen as applying only to application methods.

Extrapolation from high concentration animal studies

I think Paul’s confidence in unsupported extrapolation from higher concentration animal studies is very cavalier.  Paul claims:

“in the case of fluoride it is well know. That you have to give 5 to 10 times as much fluoride to rats to reach the same plasma level as you need in humans.”

He doesn’t support this with a citation – but I suspect that would only be to a similar assertion in Fluoride Alert or a sister web site, with no, or poor, literature reference.

The US National Research Council report Fluoride in Drinking Water – A Scientific Review of EPA’s Standards discussed the contradictory data used for attempting to show a ratio between humans and rats for blood plasma levels and concluded:

“Dunipace et al. (1995) concluded that rats require about five times greater water concentrations than humans to reach the same plasma concentration. That factor appears uncertain, in part because the ratio can change with age or length of exposure. In addition, this approach compares water concentrations, not dose. Plasma levels can also vary considerably both between people and in the same person over time (Ekstrand 1978).”

I am suspicious of attempts to use comparison of blood plasma F levels for such justifications because of the huge range and variability of these levels. This sort of speculation seems to fuel the frequent use of the word “might” in Paul’s article (and attempts to convert such logical possibilities to realities) and in the end leads to the speculation being present as a fact (Paul’s “well-known” and the simple FANNZ declaration).

But Paul at least refers to one study on rats using drinking water with F concentrations closer to those of fluoridated water – Varner et al (1998). Unfortunately I could not get the full text of this paper and the link Paul provides to http://www.fluoride-journal.com does not allow access to mere mortals like me. In my search I was amazed how links promising full text of papers like this often just take one back to Fluoride Alert and their in-house interpretation.

The abstract mentions changes in cerebrovascular and neuronal integrity for AlF3, and to a smaller extent for NaF. As I can’t access the discussion to understand he possible significance of these small changes I won’t comment further on this.

Why do countries not fluoridate

Paul describes my consideration of the various reasons behind the decisions of countries not to fluoridate their community water supplies as “more like self-serving political spin than reality!” That is rather harsh – considering he then goes on to claim only 2 main reasons – freedom of choice and health concerns. Using his own article as a reference!

No, I won’t respond by selecting personal statement from citizens of the non-fluoridated countries as he asks. But here is an outline of the situation with fluoridation throughout the world taken from a recent issue of the newsletter of the New Zealand National Fluoride Information Service. It gives a pretty detailed picture:

Countries with widespread water fluoridation programmes include Australia, the United States of America, Canada, the United Kingdom, Ireland, Spain, Israel, Brazil, Brunei, Chile, Argentina, Colombia, Hong Kong, South Korea, Singapore and Malaysia. Countries with limited water fluoridation programmes include Vietnam, Fiji, Papua New Guinea, and South Korea.

Several countries are unable to introduce water fluoridation programmes due to technical, financial or sociocultural reasons. As an alternative, both salt and milk have been found to be reliable and convenient vehicles for increasing fluoride intake to an optimal level for hard to reach and low socio-economic communities. Studies have found them to be as effective as community water fluoridation schemes.

Some European, Latin American, and Caribbean countries, including France, Switzerland, Germany, Costa rica, Colombia and Jamaica currently use fluoridated salt schemes. Mexico and most Latin American and Caribbean countries (apart from Argentina, Brazil, Chile and French Guyana) have or have had salt fluoridation programmes.

A smaller number of countries currently have fluoridated milk programmes, including Bulgaria, Chile, China, Peru, Russia, Thailand and the United Kingdom

Some country regions have optimal amounts of naturally occurring fluoride which provides good protection for oral health. examples of countries supplied with naturally fluoridated water at or around the optimum level needed to prevent dental decay include the United Kingdom (estimated 329,000 people), United States of America (estimated 10,078,000 people) Canada (estimated 300,000 people) and Australia (estimated 144,000 people).

It is estimated that 39.5 million people around the world have access to naturally fluoridated water at the optimal level although variations from one community to another over time make it difficult to calculate an accurate total.

Reasons for not fluoridating water supplies and/or using alternative ways of overcoming fluoride deficiencies are simply not restricted to attitudes towards freedom of choice and health concerns, although they may have been deciding factors for a few countries. This is another instance where opponents of fluoridation are making widespread simplistic claims (like Europe bans use of fluorosilicic acid) based on only a few facts, and ignoring (or hiding) the details.

We should also remember that despite different decisions by governments and local authorities about implementation of fluoridation all the reputable national and international health bodies do accept the scientific consensus of the beneficial role of fluoride in oral health. It is this endorsement which is more relevant to us than the specific technical, political or social  decisions made in other countries.

Political activism

I am glad Paul rejects extremism among anti-fluoride activists. However this does not seem to stop him cooperating with extreme conspiracy theorists like Alex Jones and Vinny Eastwood to produce videos. (Have a look at Cyber bullying of sciencewhich includes a recent video of Eastwood’s attacking scientists and science, to get an idea of how silly these people can be). People do notice such associations and draw their own conclusions. Paul appears to give some justification of “the more nutty conspiracy theories espoused by some opponents of fluoridation.” He says “promoters of fluoridation should not be surprised that some people are trying to come up with a rational explanation for why certain governments are behaving so irrationally promoting this practice.” Well that is his perspective and it is a minority one. I certainly don’t accept such justifications because I, and many others, have no trouble understanding the decisions to fluoridate.

Misrepresentation of the facts is a real problem among activists of all persuasions. That is understandable because ideological and political convictions and motivations can distract even the most honest people. Paul presents an example of an image that illustrates this for some supporters of fluoridation.

This image seemed to create a lot of controversy among local Facebook pages and I got the blame because it was posted on this blog. I have been assuring complainants that it is not my image and I do not support its implied message. It seems to have been taken from a document prepared under the Queensland Health logo. I cannot find a source and no-one seems to be able to give a citation. It is not on the Queensland Health web site. All Internet references seem to be in documents and sites of fluoridation opponents – indicating that it has backfired as a propaganda exercise for fluoridation. I gather it may have been prepared to send to selected Australian members of parliament at some stage.

Paul has sent me a copy of the document which interested readers can download.

But here is the trouble for those living in glasshouses who wish to throw stones. This sort of misrepresentation is probably more common among opponents of fluoridation. The figure below, for example, is from a document of the “Queenslanders for Safe Water” website which ironically included and criticised the Queensland Health photos! (Thanks to commenter Steve Slott for the link). It uses photos of extreme skeletal and dental fluorosis to argue against fluoridation.

This, and the Queensland Health photos, are extreme exaggerations used to promote a message. Reasonable people should condemn that tactic. But isn’t this, in essence, the same tactic used by Paul and other opponents of fluoridation when they extrapolate from animal studies at high concentrations, characterise the relatively common very mild and “questionable” cosmetic fluorosis as if it were severe, use the “topical” mechanism to argue that fluoridated water has no influence, wildly exaggerate the concentration of toxic contaminants in fluoridation chemicals, persistently and inappropriately describes fluoride a poison and a neurotoxin, misrepresent the reasons why some countries do not fluoridate their water supplies and deny data illustrating a beneficial effect of fluoride on oral health as “biased?”

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Fluoride debate – some housekeeping

debate-2Image credit: J. P. Greene’s Blog

I am just dealing here with housekeeping issues that are coming up in this debate. Hopefully this will involve less distraction than if we deal with them in the exchange itself.

Some of these issues are arising from my moderation of comments so I want to clarify a few guidelines. Paul has also raised some other issues.

Moderation of comments

The fluoridation issue seems to bring out the worst manners in many internet commenters. Both Paul and I want to limit the bad effects abusive and harassing comments have on discussion.

The moderating software does automatically stop comments with excessive links – and I certainly will not approve comments which link just for the sake of it, or do so thoughtlessly. However, if you wish to refer to a publication or post please give a link. I can easily approve comments with justifiable links.

Citations are another example where links are useful. It is important that when people give a citation or reference they should at least give details which enable readers to check them out. Comments which simply give authors’ names without details will likely not be approved.

I find information in comments that is backed up by proper citations or references is very useful so want to encourage the practice.

Finally, copy and paste is a big problem with commenters on the fluoridation issue. Large pieces of text from Fluoride Alert or other web pages, or from on-line books or PDFs seem to commonly be presented as comments. I find such copy and past offensive – it indicates the commenter has refused to do the work necessary to explain in their own words, maybe hasn’t even read and understood the original. Yet they expect readers to spend time on it!

Such lengthy copypasta will not be approved. (Don’t let that stop you using reasonable and genuine quoting of referenced sources though).

By the way, only 2 comments have been held up in moderation or spam for being abusive and just a few more for not providing citations or reference details. So we don’t yet have a big problem. Still, it is early days.

Scope of debate

Paul has asked me to limit my part of the exchange “to addressing my [Paul’s] arguments without going into the opinions and arguments of others, especially the more extreme views.” I find that strange and am certainly not going to limit myself this way.

We each have our own information to convey and arguments to make. That is normal in an exchange like this and Paul has certainly not limited himself only to my opinions and arguments. How could he – after all he wrote the first article in the exchange. He has certainly critically commented on what he sees as distortions or mistakes made by supporters of fluoridation (such as his comments on Queensland Health). That doesn’t worry me and I don’t think he should be concerned when I make similar criticisms – or take them personally.

I agree it is wrong to attribute the views of others, especially extreme views, to one’s discussion partner and certainly have no intention of doing so. Nor do I think I have done that yet. I have been careful to specify when any of my criticisms apply to Paul, for example in my comment on his use of appeal to authority in his first article.


Paul has objected to the use of the term “anti-fluoridationist” and wants me not to use it. He finds it offensive – “It makes opposition to fluoridation sound like some mental disease! “

Hmm. The word never struck me that way, but I guess out of respect for his feelings I should look for alternatives – at least when referring to Paul. I realise the everyone has their foibles, and I prefer to label myself as “pro-science” and not “pro-fluoridation” – but then that seems to upset people who aoppose fluoridation! You just can’t win.

What do people think. Have terms like anti- and pro-fluoridation become offensive to them? If so what do you suggest? Perhaps we have sensitivities around fluoride similar to those around climate change and it’s denial.

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

The fluoride debate – introduction


Some readers will be aware I have discussed with Paul Connett, author of the book The Case against Fluoride, the possibility of some sort of “debate” between us on the fluoridation issue. We have now agreed to run a series of articles on this blog in a rough sort of debate format.

I think most scientists are scathing about the gladiatorial style of debate – it is a sport and not a scientific exploration. It also encourages an adversarial approach, relying on personalities and oratorical skill and not evidence and reasoned consideration.

However, challenges to debate are common with controversial issues. The Christian apologists demanding their critics debate William Lane Craig (who, of course, is a skilled debater) is an obvious example. And, within the fluoridation controversy, anti-fluoridationists will sometimes demand that supporters of fluoridation debate Paul Connett – often seeing this is the final argument – “put up or shut up.”

Usually I call the bluff with such people – and they tend to disappear. But local conspiracy theorist Vinny Eastwood seems to have more influence in the anti-fluoride movement and when I accepted his challenge he did contact Paul Connett. So we ended up discussing possible places and formats for a “debate” during his visit to New Zealand next year.

During our discussions Paul suggested that an internet debate might be a practical way of carrying it out. I agreed.

So here we are.


The “debate”-discussion will be on this blog – Open Parachute. It will run as a series of pairs of articles – Paul Connett’s specific argument first with my response second. Posted the same day, or within a few days of each other.

Each of us will respond to the other’s claims and rebuttals and to extra information (as well as any relevant input from commenters)  by adding updates to the original article.

Paul’s proposal is that the series include five pairs of articles – which seems like a convenient size for such an internet discussion.  But let’s see how the cookie crumbles.

Comment moderation

As always, I encourage comments. However, both Paul and I feel that that comments in this discussion should be strongly moderated. Internet discussions are well-known for flame wars, personal abuse, harassment and offensive input. In my opinion the fluoridation debate seems to be very bad for such behaviour.

So I have introduced comment moderation. Initially all commenters will find their first comment moderated. If this does not weed out trouble makers I will resort to moderation for all comments by specific offenders – or even moderation of all comments by everyone.

It is important to keep this discussion civil and informative.

Let’s be clear – this discussion is not about “winners” and “losers.” It is about discussion of the science. Hopefully this format will encourage good faith discussion and intelligent participation from commenters.

The series of discussion exchanges starts tomorrow. Anyone wanting to follow the debate and/or check back over previous articles in the denate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page