27 August 2014 

Dr Paul Connett of the Fluoride Action Network, gives his abbreviated critique of the report prepared on behalf of the Royal Society of New Zealand and the Prime Minister’s Chief Science Advisor.

The report can be read here:

Fluoridation Review titled Health effects of water fluoridation: A review of the scientific evidence.


Hand picked governmental review panels

In the book The Case Against Fluoride (Chelsea Green, 2010) my co-authors and I tried to explain how and why the practice of water fluoridation has been pursued so vigorously for so many years, despite the science that indicates that it is neither effective nor safe. The “how’s” are much easier to explain (see chapters 22-25) than the “why’s” (see chapter 26). One of the how’s is the self-serving governmental reviews which we describe in chapter 24. We lead of that chapter with a quote from the book Fluoride Wars (2009), which is otherwise slanted toward fluoridation. The authors, Alan Freeze and Jay Lehr, conceded one very important point about the promotion of fluoridation. They write:

The Anti-fluoride forces have always claimed that the many government-sponsored review panels set up over the years to assess the costs and benefits of fluoridation were stacked in favor of fluoridation. A review of the membership of the various panels confirms this charge. The expert committees that put together reports by the American Association for the Advancement of Science in 1941, 1944 and 1954; the National Academy of Sciences in 1951, 1971, 1977 and 1993; the World Health Organization in 1958 and 1970; and the U.S. Public Health Service in 1991 are rife with the names of well-known medical and dental researchers who actively campaigned on behalf of fluoridation or whose research was held in high regard in the pro-fluoridation movement. Membership was interlocking and incestuous.

Nothing has changed. Time and time again when this practice is under political or scientific threat pro-fluoridation governments hand pick panels (usually containing a mix of government employees and scientists who are known to be pro-fluoridation) to “review” the literature and thence deliver a rubber-stamp for government policy. In chapter 24 we discuss three recent examples of this 1) The Irish Fluoridation Forum (2002); 2) Health Canada’s selection of 6 experts to review the literature in 2007 (four of which were pro-fluoridation dentists) and 3) the Australian National Health and Medical Research Council of 2007 (NHMRC, 2007).

As Mark Twain observed “history may not repeat itself but it sure does rhyme!”

The latest NZ Whitewash review

This review titled the Health Effects of Water Fluoridation: a Review of the Scientific Evidence, commissioned by the Prime Minister’s Chief Science Advisor Sir Peter Gluckman and the Royal Society of New Zealand’s president Sir David Skegg, was released on August 22, 2014.

A press report can be viewed here: Fluoride Safe and Effective Expert Review 

As far as the science is concerned this is a classic case of inaccurate, selective, slanted and superficial use of the literature and later I will give one very clear example to illustrate that. But first here is what Mary Byrne, who heads up Fluoride Free NZ says about the politics of this review: Fluoridation review ‘Dirty Science’ – Fluoride Free NZ  

Political science not physical science

The following passage from the NZ review will serve to illustrate the shoddy scientific analysis they provide. In a section titled “Effects on IQ” they write:

Recently there have been a number of reports from China and other areas where fluoride levels in groundwater are naturally very high, that have claimed an association between high water fluoride levels and minimally reduced intelligence (measured as IQ) in children.

In addition to the fact that the fluoride exposures in these studies were many (up to 20) times higher than any that are experienced in New Zealand or other CWF communities, the studies also mostly failed to consider other factors that might influence IQ, including exposures to arsenic, iodine deficiency, socioeconomic status, or the nutritional status of the children. Further, the claimed shift of less than one IQ point suggests that this is likely to be a measurement or statistical artifact of no functional significance. A recently published study in New Zealand followed a group of people born in the early 1970s and measured childhood IQ at the ages of 7, 9, 11 and 13 years, and adult IQ at the age of 38 years. Early-life exposure to fluoride from a variety of sources was recorded, and adjustments were made for factors potentially influencing IQ. This extensive study revealed no evidence that exposure to water fluoridation in New Zealand affects neurological development or IQ.

We conclude that on the available evidence there is no appreciable effect on cognition arising from CWF.

It should be incredibly embarrassing for the Royal Society of New Zealand to have its name associated with such an inaccurate and biased summary of the literature on fluoride’s impact on children’s intellectual development.


1) Gluckman and Skegg claim “a shift of less than one IQ point” in the 27 studies reviewed by Choi et al (2012). In reality, the average lowering of IQ was 6.9 IQ points and that is NOT “of no functional significance.” Gluckman and Skegg’s mistake here is huge. A downward shift of 5 IQ points (or more) in a large population would more than double the number of persons who are mentally handicapped (with IQs less than 70) and more than halve the number of very bright persons or geniuses (persons with IQs over 130).


2) Gluckman and Skegg claim that, “fluoride exposures in these studies were many (up to 20) times higher than any that are experienced in New Zealand or other CWF communities.” There are several problems with this statement.


A) By using the word “exposures” they are blurring the distinction between concentration and dose. Two populations drinking water with different fluoride concentrations can overlap in the doses received by individuals. For example, high water drinkers of water at 1 ppm could get a higher dose than low-water drinkers at 4 ppm.


B)   The use of the phrase “up to 20 times” higher is deceptive since only two out of the 27 studies had the “high-fluoride” village concentrations going up to 11.5 ppm.


Moreover, when harm is found toxicologists and regulators do not normally focus on the highest level but the lowest level where harm occurs. They try to identify a Lowest Observable Adverse Effect Level (LOAEL) and even a No Observable Adverse Effect level (NOAEL).  Thus more relevant to NZ (and other countries with water fluoridation programs in the range of 0.6 to 1.2 ppm) is the fact that 8 of the reviewed studies had concentrations in the “high-fluoride” village (where IQ was lowered) of less than 3 ppm. Thus a significant number of these studies indicate that there is no adequate margin of safety to protect all children drinking fluoridated water in NZ or other fluoridated countries.


I should add that in one study the authors sub-divided the children in the high-fluoride village into 5 groups with increasing fluoride concentrations in their well water from 0.75 to 4.3 ppm. They found that as the fluoride concentration increased a) their mean IQ of the sub-group was lowered and b) the percentage of children with an IQ less than 80 increased. The lowest level at which an IQ lowering occurred was 1.26 ppm (Xiang, et al., 2003).


C)   This lack of an adequate margin of safety gets worse when one notes that Gluckman and Skegg are also ignoring other sources of fluoride, which could make it worse for NZ children. For example, rural Chinese children are less likely to use fluoridated toothpaste and a higher percentage would be breast-fed not bottle-fed. In these two respects NZ children would be getting more fluoride from these sources than the Chinese children.


3) Gluckman and Skegg claim that of the 27 studies most “failed to consider other factors that might influence IQ, including exposures to arsenic, iodine deficiency, socioeconomic status, or the nutritional status of the children.”


However, the fact that many of the studies did not control for all of these factors does not obviate the need to look for the studies that did. For example, Xiang et al. (2003 a,b) controlled for lead, iodine and more recently arsenic and his work needs to be studied very carefully not simply dismissed because of other weaker studies.


Gluckman and Skegg are also demonstrating a double standard here because the study they offer as evidence of no lowering of IQ (Broadbent et al, 2014) also failed to control for some for these same key variables. In fact, the Broadbent study is a very weak study since they have virtually no children in the control group i.e. they had virtually no children that were neither exposed to fluoridated water nor fluoride supplements.


4) Gluckman and Skegg do a very poor job of reviewing all the other voluminous evidence that fluoride is a potent neurotoxin. So while perhaps none of these individual IQ studies is conclusive, the overall consistency of the results is remarkable considering they were done by different research teams in different countries, and over a very wide geographical area in China. The results are also consistent with many other animal and human studies. For example, there have been 19 animal studies that have shown that animals perform less well in learning and memory experiments when exposed to fluoride. It is the weight of evidence on fluoride’s neurotoxicity that should make responsible scientists and health officials much more cautious than Gluckman and Skegg. 


Compare the Gluckman – Skegg review with other International Reviews completed on fluoridation. Read a summary of the York Report with a letter from Prof Trevor Sheldon explaining how “The review did not show water fluoridation to be safe”.