Tag Archives: community water fluoridation

No relationship of bone cancer to fluoridation – another new study the anti-fluoride brigade will attempt to ignore

Anti-fluoride activists claim that water fluoridation causes nine cancer proved wrong, yet again. Image credit: Four myths about water fluoridation and why they’re wrong

A new study confirms, yet again, that osteosarcoma, a type of bone cancer, is not associated with community water fluoridation (CWF). This the seventh such study since a 1990 report of an animal study suggested such a link.

The 199o study exposed rats to very high concentrations of fluoride so the results were not relevant to CWF. But, of course, this did not stop anti-fluoride campaigners using the study to argue that CWF causes osteosarcoma.

The citation for this new study is:

Kim, F. M., Hayes, C., Burgard, S. L., Kim, H. D., Hoover, R. N., Osteosarcoma, N., … Couper, D. (2020). A Case-Control Study of Fluoridation and Osteosarcoma. Journal of Dental Research 1.

This was a hospital-based study where patients diagnosed with osteosarcoma were compared with control patients diagnosed with other bone tumours or different conditions. This figure summarises the findings.

The only statistically significant effects show a reduced likelihood of osteosarcoma diagnosis for people living in fluoridated areas – compared with those living in non-fluoridated areas (the red triangles in the figure). These were for people who never drank water and people who had lived in fluoridated areas for 0% to 50% of their lives. It is likely the effects for people who did drink bottles water and those who had lived in fluoridated areas for 50% to 100% or 100% of their lives are not statistically significant because of the smaller numbers involved (The green circles in the figure).

It’s been a bad week for the anti-fluoride crowd – the science keeps proving them wrong. Perhaps that is why they are silent about these new studies.

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New review finds fluoride is not a developmental neurotoxicant at exposure levels relevant to fluoridation

Proper consideration of the best science shows community water fluoridation does not have a negative effect on child IQ. Image credit: Africa Studio / Shutterstock.com

A new extensive review of the scientific literature has concluded that fluoride is not a human developmental neurotoxicant at the current exposure levels in Europe. This is of course just as valid for New Zealand, the USA and other countries which use community water fluoridation (CWF).

Forty-one pages long, it’s a very extensive and detailed review. The full text can be downloaded  and its citation is:

Guth, S., Hüser, S., Roth, A., Degen, G., Diel, P., Edlund, K., … Thomas, H. (2020). Toxicity of fluoride: critical evaluation of evidence for human developmental neurotoxicity in epidemiological studies, animal experiments and in vitro analyses. Archives of Toxicology. 2020 May 8.

The anti-fluoridation crowd won’t be happy with this review. They have tended to have things their own way as they have argued that fluoridation is harmful to child IQ using irrelevant studies from endemic fluorosis areas where people suffer a range of health effect from overexposure to fluoride and other contaminants. Anti-fluoride campaigners have also misrepresented and misused recent studies from areas where fluoride exposure is lower.

So this review is timely because it critically examines all the recent studies and identifies their limitations. It identified 23 relevant epidemiological studies published between January 2012 and August 2019. One of these examined an association between fluoride exposure and school performance. The other 22 examined possible relationships with IQ.

Limitations of fluoride-IQ studies

The authors reported that:

“So far, almost all studies investigating the effect of fluoride intake on intelligence were performed in relatively poor, rural communities, e.g., in China, Iran, and Mongolia, where drinking water may contain comparatively high levels of fluoride (‘exposed population’), whereas the ‘reference populations’ often had access to water that was fluoridated at the recommended level.”

Figure 1: People in endemic fluorosis area sufferer a range of health problems – studies from these areas are not relevant to CWF

This means that anti-fluoride campaigners usually rely on studies which actually show no effect at F intake levels relevant to CWF. They base their arguments on the known negative health effects at high fluoride intake (people in areas of endemic fluorosis suffer a range of health problems) but ignore, or cover-up the fact the data actually does not show any harmful effects at levels similar to that experienced by people in areas of CWF.

Figure 2: Drinking water concentrations reported by Duan et al. (2018) from “high F” and “low F” villages compared with tap water F in areas of CWF

Figure 2 above shows this using data from 26 studies reported in the review of Duan et al. (2018). Here the blue range represents the drinking water concentration range for the control groups where no health problems were reported, or it was assumed none occurred (that is why it was a control group). The green range represents drinking water fluoride concentration common in areas of CWF.

We should be drawing our conclusions about the possible effects of CWF from the blue range of data – not the red range.

Confounding effects

Guth et al (2020) stress that most studies they considered ignored many confounding effects.  For example:

” . .rural regions with unusually high or unusually low fluoride in drinking water may be associated with a less developed health-care system, as well as lower educational and socioeconomic status. Furthermore, in these regions the overall nutritional status and the intake of essential nutrients may be lower and the exposure to environmental contaminants such as lead, cadmium, mercury, or manganese may be higher—factors that are also discussed to have a potential impact on intelligence”

Only two of the studies were from areas using CWF – Broadbent et al (2015) and Green et al (2019) – and their conclusions were different. Guth et al (2020) considered these two studies in detail.

Both studies were limited by the lack of IQ data for mothers – parental IQ is a strong confounder for child IQ studies. But Guth et al (2020) are quite critical of the lack of consideration of confounders in the Green et al (2019) study:

Green et al. (2019) did not consider breastfeeding and low birth weight as possible confounders (both factors significantly associated with IQ in the study of Broadbent); they considered some of the relevant confounders (city, socioeconomic status, maternal education, race/ethnicity, prenatal secondhand smoke exposure), but did not adjust for others (alcohol consumption and further dietary factors, other sources of fluoride exposure, exact age of children at time point of testing). Furthermore, the study (Green et al. 2019) did not include assessment of children’s postnatal fluoride exposure via, e.g., diet, fluoride dentifrice, and/or fluoride tablets, which is considered to be a noteworthy limitation.”

Problems like poor consideration of confounders, contradictory results and the vague results reported by Green et al (2019) (no overall effect of fluoridation on child IQ, a statistically significant relationship of drinking water F concentration with male child IQ but not with female child IQ) caused Guth et al (2020) to conclude:

“The available epidemiological evidence does not provide sufficient arguments to raise concerns with regard to CWF in the range of 0.7–1.0 mg/L, and to justify the conclusion that fluoride is a human developmental neurotoxicant that should be categorized as similarly problematic as lead or methylmercury at current exposure levels.”

To repeat – this review is very detailed and thorough. Unlike the recent review of Grandjean (2019) (Developmental fluoride neurotoxicity: an updated review) which was superficial and somewhat biased (Grandjean is well known for his opposition to CWF) it made a detailed assessment of problems like the poor consideration of confounders or important risk-modifying factors and the concentration on poor quality studies from areas of endemic fluorosis.

Hopefully, policymakers will read this new review and take its conclusions into account.

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Industry-funded translation can introduce bias in selection of studies for scientific review

Image credit: Assessing and addressing bias in systematic reviews

The Fluoride Action Network (FAN), in the last decade, paid for translation of a lot of Chinese-language scientific papers linking high fluoride dietary intake to IQ deficits in children. They, of course, selected papers to fit their own ideologically-motivated bias. This is perfectly understandable for an activist group. But has this caused a bias in available English-language sources on this topic? And does this mean recent scientific reviews of this subject unintentionally suffer from selection bias?

I hadn’t considered this possibility before, but it is an issue raised in the recent US National Academies of Sciences (NAS) peer review of the US National Toxicity Program’s (NTP) review of possible neurotoxic effects of fluoride (see Another embarrassment for anti-fluoride campaigners as neurotoxic claim found not to be justified).

Use of FAN sources introduces biased study selection

The NAS peer reviewers are harshly critical of the NTP draft review. A central concern was the way the NTP evaluated the literature on the subject. The NAS peer reviewers say on page 3 of their report:

“The committee had substantive concerns regarding NTP’s evaluation of the human evidence as noted below. The strategy used for the literature search indicated that NTP used FAN as a source to identify relevant literature. The process by which FAN identified and selected studies is unclear, and that uncertainty raises the question of whether the process could have led to a biased selection of studies. Such a concern raises the need for a formal evaluation of any potential bias that might have been introduced into the literature-search process.”

OK, I am not impressed that the NTP used FAN as a source. FAN is hardly a reliable source and its “study tracker” certainly does not pick up anywhere near the full literature available (see Cherry-picking and ring-fencing the scientific literature). But, at first thought, I imagined that the FAN source simply produced a subset of anything that is picked up using a more reliable source like PubMed to do literature searches.

Injection of study bias into English-language scientific literature

But the NAS peer reviewers raise an important problem with reliance on FAN as a source and its effect on the available English-language scientific literature. On page 24 of their report they say:

“. . the process by which FAN identified and selected studies is not clear. FAN identified a number of studies published in Chinese language journals—some of which are not in PubMed or other commonly used databases—and translated them into English. That process might have led to a biased selection of studies and raises the question of whether it is possible that there are a number of other articles in the Chinese literature that FAN did not translate and about which NTP is unaware. NTP should evaluate the potential for any bias that it might have introduced into the literature search process. Possible ways of doing so could include conducting its own searches of the Chinese or other non–English-language literature and conducting subgroup analyses of study quality and results based on the resource used to identify the study (for example, PubMed vs non-PubMed articles). As an initial step in such evaluations, NTP should consider providing empirical information on the pathway by which each of the references was identified. That information would also improve understanding of the sources that NTP used for evidence integration and the conclusions drawn in the monograph.”

In a nutshell, FAN arranged and paid for translation of quite a large number of Chinese papers on this issue (fluoride intake and child IQ deficits). Naturally, they have selected papers supporting their political cause (the abolition of community water fluoridation) and ignored papers which they could not use to that end. It is therefore likely they have introduced into English-language scientific literature a biased selection of Chinese papers because FAN effectively “republished” the translated papers in the journal “Fluoride” – a well-known repository of anti-fluoride material.

Maybe I was wrong to assume anything from FAN would simply be a subset of what is available through more respectable searching sources. But, according to the peer reviewers, some of the translated papers may be picked up when FAN is used as a source of studies but not when PubMed or similar respected sources are used. A warning, though – many of the FAN-promoted translated studies have only been partly translated, maybe only the abstract is available. This is not sufficient for a proper scientific review (see Beware of scientific paper abstracts – read the full text to avoid being fooled).

I am not saying this bias introduction into the English-language scientific literature was intentional, but it is a likely end-result of their actions. Importantly, it is also a likely end-result of funding from big money sources (the “natural”/alternative health industry which funds FAN and similar anti-fluoride and anti-vaccination groups – see Big business funding of anti-science propaganda on health).

So, is this a way that big industry can inject their bias into the available scientific literature? A way to ensure that reviewers will, maybe unintentionally, convey this industry bais into their own summary of scientific findings?

Reviewers should make a critical assessment of studies

The FAN-promoted Chinese studies really do not contribute to any rational discussion of issues with CWF because they were all made in areas of endemic fluorosis. Ironically they often compare child IQ in villages where fluoride intake is high, with that in villages where the fluoride intake is low. It is the low -fluoride villages which are relevant to areas of CWF because their drinking water F concentrations are comparable.

In reality, these Chinese studies could be used to support the idea that CWF is harmless. Even if that is an inherent assumption for low fluoride intake in these studies.

So, perhaps the bias introduced to the literature by translation of the FAN-promoted studies really is of no consequence to the evaluation of CWF. However, consideration of reviews like the recent one by Grandjean (2019) indicates there is a tendency to simply extrapolate from high concentration studies to make unwarranted conclusions about CWF. In this case, the tendency is understandable as Grandjean is well known for his opposition to CWF and is often used by FAN to make press statements raising doubts about this health policy (see Special pleading by Philippe Grandjean on fluorideSome fluoride-IQ researchers seem to be taking in each other’s laundry, and Fluoridation not associated with ADHD – a myth put to rest).

This was also a problem with the draft NTP review which produced the (unwarranted) conclusion “that fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.” The draft did actually mention that the conclusion “is based primarily on higher levels of fluoride exposure (i.e., >1.5 ppm in drinking water” and “effects on cognitive neurodevelopment are inconsistent, and therefore unclear”  for “studies with exposures in ranges typically found in the water distribution systems in the United States (i.e., approximately 0.03 to 1.5 ppm according to NHANES data).” But, of course, it is the unwarranted conclusion that gets promoted.

Conclusions

Reviewers need to be aware of this and other ways activist groups and big business can inject bias into the scientific literature.

This problem underlines the responsibility reviewers have of recognising all possible ways that biased selection of studies they consider can occur. It also means they should make every effort to include negative studies (not supporting the effect they may personally prefer) as well as positive studies. They also need to include all the findings (positive and negative) included in the individual studies they review.

In cases like the FAN-promoted Chinese studies, there is an obligation to at least note the possibility of bias introduced by activists and industry-funded translations. Even better, to ensure that the reviewer undertakes to independently search for all studies on the subject and arrange for translations where necessary.

Above all, reviewers should critically consider the quality of the studies they include in their reviews and not simply rely on their own confirmation bias.

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Biostatistical problems with the Canadian fluoride/IQ study

There are insights in there somewhere. Image Credit: DATA ANALYTICS COMES TO THE LEGAL PROFESSION

There has been widespread scientific criticism of the recently published Canadian fluoride-IQ study of Green et al., (2019). Most recently Dr. René F. Najera (a Doctor of Public Health, an epidemiologist and biostatistician) has critiqued the statistical analysis. He finds a number of faults and concludes by hoping “public health policy is not done based on this paper:”

 “It would be a terrible way to do public health policy. Scientific discovery and established scientific facts are reproducible and verifiable, and they are based on better study designs and stronger statistical outcomes than this. “

Dr. Najera’s critiques the biostatistics is in his article The Hijacking of Fluorine 18.998, Part Three. This follows his previous critique (Part 1 and Part 2) of the epidemiological issues which I reviewed in Fluoridation – A new fight against scientific misinformation.

Dr. Najera starts by stressing the important role of biostatistics in epidemiological studies. After all the planning and measurement:

“.. we hand off the data to biostatisticians, or we do the work with biostatisticians. Doing this assures us that we are measuring our variables correctly and that all associations we see are not due to chance. Or, if chance had something to do with it, we recognize it and minimize the factors that lead to chance being a factor in and of itself.”

I agree completely. In my experience statisticians play a critical role in research and should be involved even at the planning stage. Further, I think the involvement of experienced biostatisticians is invaluable. Too often I see papers where the authors themselves relied on their own naive statistical analyses rather than calling on experience. Perhaps they are being protective of their own confirmation bias.

The specific study Dr. Najera critiques is:

Green, R., Lanphear, B., Hornung, R., Flora, D., Martinez-Mier, E. A., Neufeld, R., … Till, C. (2019). Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada. JAMA Pediatrics, 1–9.

For my other comments on the Candian fluoride/IQ research see:

No comparison group

One problem with this study is that a number of mother-child pairs were excluded and, in the end, the sample used was not representative of the Canadian population. Najera summarises the “main finding of the study as “that children of mothers who ingested fluoride during pregnancy had 4 IQ points lower for each 1 mg of fluoride consumed by the mother:”

“If you’re asking yourself, “Compared to whom?” you are on the right track. There was no comparison group. Women who did not consume tap water or lived outside a water treatment zone were not included, and that’s something I discussed in the previous post. What the authors did was a linear regression based on the data, and not much more.”

In fact, while the sample used was unrepresentative the study did compare the IQs of children whose mothers had lived in fluoridated and nonfluoridated areas. There was no statistically significant difference – an important fact which was not discussed at all in the paper. This table was extracted from the paper’s Table 1.

What about that regression?

While ignoring the mean values for fluoridated and nonfluoridated areas the authors relied on regression analyses to determine an effect.

But if you look at the data  in their Figure 3A reproduced below you can see problems:

“. . . you can see that the average IQ of a child for a mother consuming 1.5 mg of fluoride is about 100. You also see that only ONE point is representing that average. That in itself is a huge problem because the sample size is small, and these individual measurements are influencing the model a lot, specially if their value is extreme. Because we’re dealing with averages, any extreme values will have a disproportionate influence on the average value.”

Several scientific commenters on this paper have noted this problem which is important because it should have been dealt with in the statistical analysis:

“When biostatisticians see these extreme values popping up, we start to think that the sample is not what you would call “normally distributed.” If that is the case, then a linear regression is not exactly what we want to do. We want to do other statistical analyses and present them along with the linear regressions so that we can account for a sample that has a large proportion of extreme values influencing the average. Is that the case with the Green study? I don’t know. I don’t have access to the full dataset. But you can see that there are some extreme values for fluoride consumption and IQ. A child had an IQ of 150, for example. And a mother consumed about 2.5 milligrams of fluoride per liter of beverage. Municipal water systems aim for 0.7 mg per liter in drinking water, making this 2.5 mg/L really high.”

No one suggests such outliers be removed from the analyses (although the authors did remove some). But they “should be looked at closely, through statistical analysis that is not just a linear regression.”

This is frustrating because while the authors did not do this they hint that it was considered (but do not produce results)  when they say:

“Residuals from each model had approximately normal distributions, and their Q-Q plots revealed no extreme outliers. Plots of residuals against fitted values did not suggest any assumption violations and there were no substantial influential observations as measured by Cook distance. Including quadratic or natural-log effects of MUFSG or fluoride intake did not significantly improve the regression models. Thus, we present the more easily interpreted estimates from linear regression models.”

As Dr. Najera comments, this is “.. worrisome because that is all they presented. They didn’t present the results from other models or from their sensitivity analysis.”

Scientific commenters are beginning to demand that the authors make the data available so they can check for themselves. My own testing with the data I extracted from the figure does show that the data is not normally distributed. Transformation produced a normal distribution of the data but the relationship was far weaker than for a straight linear regression. Did the authors reject transformations simply because they  “did not significantly improve the regression models?”

That suggests confirmation bias to me.

Confidence intervals

In their public promotions, the authors and their supporters never mention confidence intervals (CIs)- perhaps because the story does not look so good when they are considered. Most of the media coverage has also ignored these CIs.

A big thing is made for the IQ score of boys dropping by 4.49 points with a 1 mg/L increase in  mother’s urinary fluoride, but:

“Based on this sample, the researchers are 95% confident that the true drop in IQ in the population they’re studying is between 0.6 points and 8.38 points. (That’s what the 95% CI, confidence interval, means.)”

In other words:

“In boys, the change is as tiny as 0.6 and as huge as 8.38 IQ points.”

For girls the change:

“is between -2.51 (a decrease) and 7.36 (an increase). It is because of that last 95% CI that they say that fluoride ingestion is not associated with a drop in IQ in girls. In fact, they can’t even say it’s associated with an increase. It might even be a 0 IQ change in girls.”

Dr. Najera asks:

“Is this conclusive? In my opinion, no. It is not conclusive because that is a huge range for both boys and girls, and the range for girls overlaps 0, meaning that there is a ton of statistical uncertainty here. “

This is why the epidemiological design used by the authors is worrying. For example:

” The whole thing about not including women who did not drink tap water is troubling since we know that certain drinks have higher concentrations of fluoride in them. If they didn’t drink tap water, what are the odds that they drank those higher-fluoride drinks, and what was the effect of that?”

This comes on top of the problems with the regression models used.

Transformation to normalise the data and inclusion of other important facts may have produced a non-significant relationship and there would be no need for this discussion and speculation.

What about those other important factors?

Green et al (2019) included other factors (besides maternal urinary fluoride) in their statistical model. This “adjustment” helps check that the main factor under consideration is still statistically significant when other factors are included. In this case, the coefficient (and CIs) for the linear association for boys was reduced from -5.01  (-9.06 to -0.97) for fluoride alone to -4.49 (-8.38 to -0.60) when other considered factors were included. In this case, the other factors included race/ethnicity, maternal education, “city”, and HOME score (quality of home environment).

Dr. Najera questions the way other factors, or covariates, were selected for inclusion in the final model. He says:

“The authors also did something that is very interesting. They left covariates (the “other” factors) in their model if their p-value was 0.20. A p-value tells you the probability that the results you are observing are by chance. In this case, they allowed variables to stay in their mathematical model if the model said that there was as much as a 1 in 5 chance that the association being seen is due to chance alone. The usual p-value for taking out variables is 0.05, and even that might be a little too liberal.

Not only that, but the more variables you have in your model, the more you mess with the overall p-value of your entire model because you’re going to find a statistically significant association (p-value less than 0.05) if you throw enough variables in there. Could this be a case of P Hacking, where researchers allow more variables into the model to get that desired statistical significance? I hope not.”

Good point. I myself was surprised at the use of such a large p-value for selection. And, although the study treats fluoride as the main factor and inclusion of the other factors reduces the linear coefficient for maternal urinary fluoride, I do wonder why more emphasis was not put on these other factors which may contribute more to the IQ effect than does fluoride.

Perhaps this paper should have concentrated on the relationship of child IQ with race or maternal education rather than with fluoride.

Padding out to overcome the poor explanation of IQ variance

Another point about the inclusion of these covariates. As well as possible improving the statistical significance of the final model they may also make the model look better in terms of the ability to explain the variance in IQ (which is very large – see figure above).

In my first critique of the Green et al (2019) paper (If at first you don’t succeed . . . statistical manipulation might help) I pointed out that the reported relationship for boys, although statistically significant, explained very little of the variance in IQ. I found only 1.3% of the variance was explained – using data I had digitally extracted from the figure. This was based on the R-squared value for the linear regression analysis.

Unfortunately, the authors did not provide information like R-squared values for their regression analysis (poor peer review in my opinion) – that is why I, and others, were forced to extract what data we could from the figures and estimate our own. Later I obtained more information from  Green’s MA thesis describing this work (Prenatal Fluoride Exposure and Neurodevelopmental Outcomes in a National Birth Cohort). Here she reported an R-squared value of 4.7%. Bigger than my 1.3% (my analysis suffered from not having all the data) but still very small. According to Nau’s (2017) discussion of the meaning of R-squared values (What’s a good value for R-squared?), ignoring the coefficient determined by Green et al (2019) (5.01) and relying only on the constant in the relationship would produce a predicted value of IQ almost as good (out by only about 2%).

That is, simply taking the mean IQ value (about 114.1 according to the figure above) for the data would be almost as good as using the relationship for any reasonable maternal urinary fluoride value and OK for practical purposes.

But look at the effect of including other factors in the model. Despite lowering the coefficient of the relationship for fluoide it drastically increases the R-squared value. Green reported a value of 22.0% for her final model. Still not great but a hell of a lot better than 4.7%.

Perhaps the inclusion of so many other factors in a multiple regression makes the final model look much better – and perhaps that perception is unjustly transferred to the relationship with fluoride.

Are other more important factors missed?

Almost certainly – and that could drastically alter to conclusions we draw from this data. The problem is that fluoride can act as a proxy for other factors. City location and size are just one aspect to consider.

In my paper Fluoridation and attention deficit hyperactivity disorder a critique of Malin and Till (2015), I showed inclusion of altitude as a risk-modifying factor completely removed any statistical significance from the relationship between ADHD prevalence and fluoridation – despite the fact Malin & Till (2015) had reported a significant relationship with R-squared values over 30%!

Malin & Till (2015) reported these relationships as statistically significant. However, when altitude was included in the multiple regressions by Perrott (2018) no significant relationships were fluoridation were found.

So you can see the problem. Even though authors may list a number of factors or covariates they “adjusted” for, important risk-modifying factors may well be ignored in such studies. This is not to say that inclusion of them “proves” causation any more than it does for fluoride. But if their inclusion leads to the disappearance of the relationship with fluoride one should no longer claim there is one (reviewers related to the group involved in the Green et al., 2019 study still cite Malin & Till 2015 as if their reported relationship is still valid).

In effect, the authors acknowledge this with their statement:

“Nonetheless, despite our comprehensive array of covariates included, this observational study design could not address the possibility of other unmeasured residual confounding.”

Summary

Dr. Najera summarises his impression of the Green et al (2019) study in these words:

“The big idea of these three blog posts was to point out to you that this study is just the latest study that tries very hard to tie a bad outcome (lower IQ) to fluoride, but it really failed to make that case from the epidemiological and biostatistical approaches that the researcher took, at least in my opinion. Groups were left out that shouldn’t. Outliers were left in without understanding them better. A child with IQ of 150 was left in, along with one mother-child pair of a below-normal IQ and very high fluoride, pulling the averages in their respective directions. The statistical approach was a linear regression that lumped in all of the variables instead of accounting for different levels of those variables in the study group. (A multi-level analysis that allowed for the understanding of the effects of society and environment along with the individual factors would have been great. The lack of normality in the distribution of outcome and exposure variables hint at a different analysis, too.)”

Pretty damning!

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Anti-fluoridationists rejection of IQ studies in fluoridated area.

US anti-fluoride activist Paul Connett claims studies cannot detect an IQ effect from fluoridated water because total fluoride intake is the real problem – but still campaigns against community water fluoridation. Image credit: MSoF “Activist Spouts Nonsense – The Evidence Supports Fluoridation”

This is another article in my critique of the presentation Paul Connett prepared to present to a meeting at Parliament in February.

I deal with his coverage of the studies of IQ effects where community water fluoridation (CWF) is used. There are now actually three such studies (Broadbent et al. 2015, Barberio et al. 2017  and  Aggeborn & Öhman 2016), but Connett pretends there is only one – the Broadbent et al. (2015) New Zealand study.

Maybe because it was the first one to provide evidence challenging his extrapolation of the fluoride/IQ studies (see The 52 IQ studies used by anti-fluoride campaigners) results in areas of endemic fluorosis to areas where CWF is used. It is also the study which seems to have resulted in the most hostility from anti-fluoride campaigners.

So here I will just be sticking with his criticism of the New Zealand study Broadbent et al (2015):

Slide 76 from Paul Connett’s presentation prepared for his February meeting at  parliament buildings

Broadbent’s findings do not “negate all other human studies”

Paul allows emotion to get the better of him as no one is suggesting this at all. The studies Connett refers to are all from areas of endemic fluorosis (see  The 52 IQ studies used by anti-fluoride campaigners), not from areas of CWF.

Broadbent et al (2015) simply concluded that their “findings do not support the assertion that fluoride in the context of CWF programmes is neurotoxic.”  That is a modest statement and Broadbent et al. (2015) simply do not draw any conclusions about the studies Connett relies on. But, of course, Connett is upset because this and similar studies just do not support his attempt to extrapolate results from areas of endemic fluorosis to areas of CWF.

The health problems suffered by people in areas of endemic fluorosis are real and it is right they should be studied and attempts made to alleviate them. But this has absolutely nothing to do with CWF.

“Fatally flawed” charge is itself fatally flawed

Again, Paul has allowed emotions to get the upper hand. It is possible, and necessary, to critique published papers – but critiques should be evidence-based and realistic. Paul’s “fatally flawed” charge (slides 77 & 78) simply displays how much this paper has put his nose out of joint.

But let’s look at the specific “flaws” Paul (and other critics associated with the Fluoride Action Network) claim.

The two villages mindset: Paul alleges that the Broadbent et al (2015) study “essentially compared two groups.” He is stuck in the mindset of most of his 52  studies from areas of endemic fluorosis (see  Fluoride & IQ: The 52 Studies). The mindset of simply comparing the IQ levels of children in a village suffering endemic fluorosis with the IQ levels of children in a village not suffering endemic fluorosis. This simple approach can identify statistically significant differences between the villages but provides little information on causes. For example, most of these studies used drinking water fluoride as a parameter but there could be a whole range of other causes related to health problems of fluorosis.

Professor Richie Poulton, current Director of the Dunedin Multidisciplinary Health and Development Research Unit

In contrast, Broadbent et al. (2015) used “General Linear models to assess the association between CWF and IQ in childhood and adulthood, after adjusting for potential confounders.” The statistical analysis involved includes accounting for a range of possible risk-modifying factors besides CWF., This was possible because the study was part of the Dunedin Multidisciplinary Health and Development Study. This is a highly reputable long-running cohort study of 1037 people born in 1972/1973 with information covering many areas.

The fluoride tablets argument: Connett and other critics always raise this issue – the fact that “In New Zealand during the 1970s, when the study children were young, F supplements were often prescribed to those living in unfluoridated areas.” Often they will go further to claim that all the children in the unfluoridated area of this study were receiving fluoride tablets – something they have no way of knowing.

But the fact remains that fluoride tablets were included in the statistical analysis. No statistically significant effect was seen for them.  Overlap of use of fluoride tablets with residence in fluoridated or unfluoridated areas will have occurred and their influence would be reflected in the results found. Presumably, the effect would be to increase the confidence intervals. As the critics, Menkes et al. (2014), say “comparing groups with overlapping exposure thus compromises the study’s statistical power to determine the single effect of CWF.”  I agree. But this does not negate the findings which are reported with the appropriate confidence intervals (see below).

The point is that the simplistic argument that effects of fluoride tablets were ignored is just not correct. Their effect is reflected in the results obtained.

Potential confounders: Many poor quality studies have ignored possible confounders, or considered only a few. This is a general problem with these sort of studies – and even when attempts are made to include all that the researchers consider important a critic can always claim there may be others – especially if they do not like the results. Claims of failing to consider confounders can often be simply the last resort of armchair critics.

In this case, there is no actual reported association to be confounded (unlike my identification of this problem with the Malin & Till 2015 ADHD study – see Perrott 2017). However, Osmunson et al. (2016) specifically raised possibilities of confounding by lead, manganese, mother’s IQ and rural vs urban residence. Mekes et al. (2014) also raised the rural vs urban issue as well as a possible effect from breastfeeding reducing fluoride intake by children in fluoridated areas.  In their response, Broadbent et al (2015b & 2016) reported that a check showed no significant effect of lead or distance from the city centre and pointed out that manganese levels were too low to have an effect. Broadbent et al (2015b) also reported no significant breastfeeding-fluoride interaction occurred.

Numbers involved: Connett claims the study was fatally flawed because “it had very few controls: 991 lived in the fluoridated area, and only 99 in non-fluoridated” (Slide 77). But the numbers are simply given by the longer term Dunedin study themselves – they weren’t chosen by Broadbent and his co-workers. That is the real world and is hardly a “fatal flaw.”

The 95% confidence intervals

Yes, statisticians always love to work with the large numbers but in the real world, we take what we have. Smaller numbers mean less statistical confidence in the result – but given that Broadbent et al (2015) provides the results, together with confidence intervals, it is silly to describe this as fatally flawed. These were the results given in the paper for the parameter estimate of the factors of interest:

Factor Parameter estimate 95% Confidence interval p-value
Area of residence -0.01 -3.22 to 3.20 .996
Fluoride toothpaste use 0.70 -1.03 to 2.43 .428
Fluoride tablets 1.55 -0.38 to 3.49 .116

Connett did not refer to the confidence intervals reported by Broadbent et al (2015). However, Grandjean and Choi (2015) did describe them as “wide” – probably because they were attempting to excuse the extrapolation of “fluoride as a potential neurotoxic hazard” from areas of endemic fluorosis to CWF.

The argument over confidence intervals can amount to straw clutching – a “yes but” argument which says “the effect is still there but is small and your study was not large enough to find it.” That argument can be never ending but it is worth noting that Aggeborn & Öhman (2016) made a similar comment about wide confidence intervals for all fluoride/IQ studies, including that of Broadbent et al. (2015).  Aggeborn & Öhman (2016) had a very large sample (almost 82,000 were involved in the cognitive ability comparisons) and reported confidence intervals of -0.18 to 1.03 IQ points (compared with -3.22 to 3.20 IQ points reported by Broadbent et al 2015). Based on this they commented, “we are confident to claim that we have estimated a zero-effect on cognitive ability.”

The “yes but” argument about confidence intervals may mean one is simply expressing faith in an effect so small as to be meaningless.

Total fluoride exposure should have been used: Connett says (slide 77) “Broadbent et al did not use the proper measure of fluoride exposure. They should have used total F exposure.  Instead, they used only exposure from fluoridated water.” Osmunson et al. (2016) make a similar point, claiming that the study should not have considered drinking water fluoride concentration but total fluoride intake. They go so far as to claim “the question is not whether CWF reduces IQ, but whether or not total fluoride intake reduces IQ.”

This smacks of goalpost moving – especially as the argument has specifically been about drinking water fluoride and most of the studies they rely on from areas of endemic fluorosis specifically used that parameter.

In their response to this criticism Broadbent et al (2016) calculated estimates for total daily fluoride intake and used them in their analysis which “resulted in no meaningful change of significance, effect size, or direction in our original findings.”

It’s interesting to note that Connett and his co-workers appear to miss completely the point about “wide” confidence intervals made by Grandjean and Choi (2015). Instead, they have elevated their argument to the claim that fluoride intake is almost the same in both fluoridated and unfluoridated areas so that any study will not be able to detect a difference in IQ. Essentially they are claiming that we are all going to suffer IQ deficits whether we live in fluoridated or unfluoridated areas.

This is the central argument of their paper – Hirzy et al (2016). However, the whole argument relies on their own estimates of dietary intakes – a clear example where motivated analysts will make the assumptions that fit and support their own arguments. This argument also fails to explain why the Dunedin study found lower tooth decay in fluoridated areas.

Last time I checked the anti-fluoride campaigners, including Connett, were still focusing on CWF – fluoride in drinking water. One would think if they really believed their criticism that they would have given up that campaign and instead devoted their energies to the total fluoride intake alone.

Conclusions

All studies have limitations and of course, Broadbent et al. (2015) is no exception. However, the specific criticisms made by Connett and his fellow critics do not stand up to scrutiny. Most have been responded to and shown wrong – mind you this does not stop these critics from continuing to repeat them and disregard the responses.

I believe the relatively wide confidence intervals could be a valid criticism – although it does suggest a critic who is arguing for very small effects. A critic who may always find the confidence intervals still exclude their very small effect – no matter how large the study is.

In effect, the narrow confidence intervals reported by Aggeborn & Öhman (2016) should put that argument to rest for any rational person.

References

Aggeborn, L., & Öhman, M. (2016). The Effects of Fluoride In The Drinking Water

Barberio, A. M., Quiñonez, C., Hosein, F. S., & McLaren, L. (2017). Fluoride exposure and reported learning disability diagnosis among Canadian children: Implications for community water fluoridation. Can J Public Health, 108(3),

Broadbent, J. M., Thomson, W. M., Ramrakha, S., Moffitt, T. E., Zeng, J., Foster Page, L. A., & Poulton, R. (2015). Community Water Fluoridation and Intelligence: Prospective Study in New Zealand. American Journal of Public Health, 105(1), 72–76.

Broadbent, J. M., Thomson, W. M., Moffitt, T., Poulton, R., & Poulton, R. (2015b). Health effects of water fluoridation: a response to the letter by Menkes et al. NZMJ, 128(1410), 73–74.

Broadbent, J. M., Thomson, W. M., Moffitt, T. E., & Poulton, R. (2016). BROADBENT ET AL. RESPOND. American Journal of Public Health, 106(2), 213–214. https://doi.org/10.2105/AJPH.2015.302918

Grandjean, P., Choi, A. (2015). Letter: Community Water Fluoridation and Intelligence. Am J Pub Health, 105(4).

Hirzy, J. W., Connett, P., Xiang, Q., Spittle, B. J., & Kennedy, D. C. (2016). Developmental neurotoxicity of fluoride: a quantitative risk analysis towards establishing a safe daily dose of fluoride for children. Fluoride, 49(December), 379–400.

Malin, A. J., & Till, C. (2015). Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association. Environmental Health, 14.

Menkes, D. B., Thiessen, K., & Williams, J. (2014). Health effects of water fluoridation — how “ effectively settled ” is the science? NZ Med J, 127(1407), 84–86.

Osmunson, B., Limeback, H., & Neurath, C. (2016). Study incapable of detecting IQ loss from fluoride. American Journal of Public Health, 106(2), 212–2013.

Perrott, K. W. (2017). Fluoridation and attention deficit hyperactivity disorder – a critique of Malin and Till ( 2015 ). Br Dent J.

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Fluoridation means money in the pocket

Local researchers recently presented data showing that the ordinary person, and not the taxation financed health system, is the main financial beneficiary of community water fluoridation.

Their research confirmed that community water fluoridation in New Zealand is highly cost-effective for all but the smallest communities. This study updates previous evaluations by including data for adults – previous studies were limited to children. It also corrected for under-estimation of averted dental restoration costs in a previous study.

The authors also make the point that an update is necessary because:

“Sound public health practice requires periodic re-evaluation of interventions’ benefits and costs.”

The results are reported in the paper:

Moore, D., Poynton, M., Broadbent, J. M., & Thomson, W. M. (2017). The costs and benefits of water fluoridation in NZ. BMC Oral Health, 17(1), 134.

Community size

As with previous studies, the results confirmed that fluoridation is not cost effective for very small communities because of the capital cost of fluoridation plants and the use of sodium fluoride instead of fluorosilicic acid as the fluoridating chemical in small plants. However:

“For ‘minor’ through to ‘large’ plants, there is a net cost saving. For a ‘large’ plant supplying 50,000 people, the cost offsets are over 20 times the cost of fluoridation. The break-even point appears to be reached by ‘minor’ plants supplying a population over 500.”

National net savings from universal fluoridation

The authours estimated the national costs and saving from averted ental costs over a 20 year period. If all New Zealand reticulated water supplies serving populations greater than 500 were fluoridated costs over 20 years would amount to$177 million while the cost offset due to averted dental treatment costs would be $1578 million.

The national 20-year net saving due to such universal community water fluoridation in NZ would amount to $1401 million.

That is a nine times pay-off!

Individuals save more than the state

I hadn’t thought of this before but the data enables separate estimates of savings to the state from universal CWF through reduced costs to the health budget, and to the individual citizen through their reduced costs for private dental treatment.

In fact, the major benefit is to the individual rather than the health budget.  National savings over 20 years for reduction of private dental care expenditure would be $1428 million – 10 times the savings to the national health budget.

Perhaps this helps people understand that they, personally, have something to gain fiancially from community water fluoridation

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Fluoridation not associated with ADHD – a myth put to rest

Fluoridated water is NOT associated with ADHD: Photo by mtl_moe

The myth of community water fluoridation causing attention deficit hyperactivity disorder (ADHD) is just not supported by the data. I show this in a new paper accepted for publication in the British Dental Journal. This should remove any validity for the claims about ADHD by anti-fluoride campaigners.

Mind you, I do not expect them to stop making those claims.

The citation for this new paper is (will be):

Perrott, K. W. (2017). Fluoridation and attention hyperactivity disorder – a critique of Malin and Till. British Dental Journal. In press.

The Background

The fluoridation causes ADHD myth was initially started by the publication of Malin & Till’s paper in 2015:

Malin, A. J., & Till, C. (2015). Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association. Environmental Health, 14.

It was quickly taken up and promoted by anti-fluoride campaigners – becoming one of their most cited papers when claiming harmful psychological effects from fluoridation. Part of the reason for its popularity is that it is the only published paper reporting an association between community water fluoridation (CWF) incidence and the prevalence of a psychological deficit. All other reports on this used by anti-fluoride campaigners are based on studies made in high fluoride regions like China where fluorosis is endemic. Those studies are just not relevant to CWF.

While many critics rejected Malin & Till’s conclusions on the simple basis that correlation does not mean causation I decided to look a bit deeper and test their statistical analyses. This was easy because they used published US data for each US state and such data is available for many factors.

I posted my original findings in the article ADHD linked to elevation not fluoridation. This showed that a number of factors were independently associated with ADHD prevalence (eg., home ownership, poverty, educational attainment, personal income, and % of the population older than 65) and these associations were just as significant statistically as the associaiton reported by Malin & Till.

However, multiple regression of possible modifying factors showed no statistically significant of ADHD prevalence with CWF incidence when mean state elevation was includedd.

The importance of elevation was confirmed by Huber et al. (2015):

Huber, R. S., Kim, T.-S., Kim, N., Kuykendall, M. D., Sherwood, S. N., Renshaw, P. F., & Kondo, D. G. (2015). Association Between Altitude and Regional Variation of ADHD in Youth. Journal of Attention Disorders.

Huber et al., (2015) did not include CWF incidence in their analyses. I have done this with the new paper in the British Dental Journal.

Publication problems

I firmly believe that scientific journals, like  Environmental Health which published the Malin & Till paper, have an ethical obligation to accept critiques of papers they publish (subject to peer review of course). Similarly, it is appropriate that any critique of a published paper is made in the journal where it was originally published. Implicit in this arrangement, of course, is that the authors of the original paper get the chance to respond to any critique and that the response be published by the original journal.

Unfortunately, this was not possible for this paper because the Chief Editor of  Environmental Health,  Prof Philippe Grandjeansimply refused to allow this critique to be considered for publication. No question of any peer reviuew. In his rejection he wrote:

“Although our journal does not currently have a time limit for submission of comments on articles published in EH, we are concerned that your response appears a very long time after the publication of the article that you criticize. During that period, new evidence has been published, and you cite some of it. There are additional studies that would also have to be taken into regard in a comprehensive comment, as would usually be the case after two years. In addition, the way the letter is written makes us believe that the letter is part of a controversy, and our journal is certainly not the appropriate forum for a dispute on fluoride policies.”

My response pointed out the reasons for the time gap (problems related to the journals large publication fee), that no other critique of the Malin & Till paper had yet been published and that any perceived polemics in the draft should normally be attended to by reviewers. This was ignored by Grandjean.

While Grandjean’s rejection astounded me – something I thought editors would consider unethical – it was perhaps understandable. Grandjean is directly involved as an author of several papers that activists use to criticise community water fluoridation. Examples are:

Grandjean is part of the research group that has published data on IQ deficits in areas of endemic fluorosis – studies central to the anti-fluoride activist claims that CWF damages IQ.  He has also often appears in news reports supporting research findings that are apparently critical of CWF so has an anti-fluoridation public standing.

In my posts Poor peer-review – a case study and Poor peer review – and its consequences I showed how the peer review of the original Malin & Till paper was one-sided and inadequate. I also provided a diagram (see below) showing the relationship of Grandjean as Chief Editor of the Journal, and the reviewers as proponents of chemical toxicity mechanisms of IQ deficits.

So, I guess a lesson learned. But the unethical nature of Grandjean’s response did surprise me.

I then submitted to paper to the British Dental Journal. It was peer-reviewed, revised and here we are.

The guts of the paper

This basically repeated the contents of my article ADHD linked to elevation not fluoridation. However, I tried to use Malin &Till’s paper as an example of problems in ecological or correlation studies. In particular the inadequate consideration of possible risk-modifying factors. Malin & Till clearly had a bias against CWF which they confirmed by limiting the choice of covariates that might show them wrong. I agree that a geographic factor like altitude may not have been obvious to them but their discussion showed a bias towards chemical toxicity mechanisms – even though other social factors are often considered to be implicated in ADHD prevalence.

Unfortunately, Malin & Till’s paper is not an isolated example. Another obvious example of confirmation bias is that of Peckham et al., (2015). They reported an association of hypothyroidism with fluoridation but did not include the most obvious example of iodine deficiency as a risk-modifying factor in their statistical analysis

Of course, anti-fluoride campaigners latched on to the papers of Peckham et al., (2015) and Malin & Till (2015) to “prove” fluoridation was harmful. I guess such biased use of the scientific literature simply to be expected from political activists.

However,  I also believe the scientific literature contains many other examples where inadequate statistical analyses in ecological studies have been used to argue for associations which may not be real. Such papers are easily adopted by activists who are arguing for or against specific social policies or social attitudes. For example, online articles about religion will sometimes refer to published correlations of religosity with IQ, educational level or scoio-economic status. Commenters simply select the studies which confirm the bias they are arguing for.

These sort of ecological or corellations studies can be useful for developing hypotheses for future study but it is wrong to use them to support an argument and worse as “proof” of an argument.

Take home message

  1. There is no statistically significant association of CWF with ADHD prevalence. Malin & Till’s study was flawed by lack of consideration of other possible risk-modifying factors;
  2. Be very wary of ecological or correlation studies.Correlation is not evidence for causation and many of these sudues iognore other possible important risk-modifying factors.

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Local anti-fluoride activists tell porkies yet again

FFNZ confuses lack of low fluoride studies on rats with human studies

Well, I suppose that’s not news. A bit surprising, though, because they are claiming the absence of research on fluoridation and IQ – which sort of conflicts with the previous attempts to actually condemn and misrepresent the actual research on fluoridation and IQ.

Fluoride Free NZ’s (FFNZ) face book page is claiming:

Would you be interested to know that no studies have been conducted on fluoridated water at 0.7ppm to determine whether there is IQ reduction? The National Toxicology Program are currently completing research to fill this gap. You would have thought that they would have done this in the 1950s before starting the fluoridation program wouldn’t you?

There have actually been three recent studies from three different countries which have specifically investigated the claim of an effect of fluoridation on IQ – and, unsurprisingly, all threes studies showed there was no effect.

Here are those studies:

New Zealand

Broadbent, J. M., Thomson, W. M., Ramrakha, S., Moffitt, T. E., Zeng, J., Foster Page, L. A., & Poulton, R. (2014). Community Water Fluoridation and Intelligence: Prospective Study in New Zealand. American Journal of Public Health, 105(1), 72–76.

In fact, anti-fluoride activists in the US, as well as New Zealand, have campaigned against this study. Their major criticism is that the study also included the effect of fluoride tablet use. They argue that this makes the unfluoridated control group useless because many participants will have consumed fluoride tablets. However, they ignore the fact that the statistical analysis corrected for this but still found no statistically significant difference in IQ of children and adults from fluoridated and unfluoridated areas.

Sweden

Other critics of the Broadbent et al. (2014) study have raised the issue of experimental power because of the numbers of people in the study. This could be a valid issue as it would determine the minimum effect size capable of being detected. Aggeborn & Öhman (2016) made that criticism of Broadbent et al., (2016) and all other fluoride-IQ studies. Their study is reported at:

Aggeborn L, Öhman M. (2016) The Effects of Fluoride in the Drinking Water. 2016.

Aggeborn & Öhman (2016) used much larger sample size than any of the other studies – over 81,000 observations compared with around 1000 or less for the commonly cited studies. It was also made on continually varying fluoride concentrations using the natural fluoride levels in Swedish drinking waters (the concentrations are similar to those in fluoridated communities), rather than the less effective approach of simply comparing two villages or fluoridated and unfluoridated regions. The confidence intervals were much smaller than those of other cited fluoride-IQ studies. This makes their conclusion that there was no effect of fluoride on cognitive measurements much more definitive. Incidentally, their study also indicated no effect of fluoride on the diagnosis of ADHD or muscular and skeleton diseases.

Canada

Another recent fluoridation-IQ study is that of Barbario (2016) made in Canada:

Barberio, AM. (2016). A Canadian Population-based Study of the Relationship between Fluoride Exposure and Indicators of Cognitive and Thyroid Functioning; Implications for Community Water Fluoridation. M. Sc. Thesis; Community Health Sciences, University of Calgary.

This study also had a large sample size – over 2,500 observations. This reported no statistically significant relationship of cognitive deficits to water fluoride.

Incidentally, Barberio (2016) also found there was no evidence of any relationship between fluoride exposure and thyroid functioning. That puts another pet claim of anti-fluoride campaigners to rest.

Animal studies

So much for NZFF’s claim that “no studies have been conducted on fluoridated water at 0.7ppm to determine whether there is IQ reduction.” But, just a minute, they are quoting the National Toxicology Program (NTP):

“No studies evaluated developmental exposure to fluoride at levels as low as 0.7 parts per million, the recommended level for community water fluoridation in the United States. Additional research is needed.”

But they omit the next sentence from the quote:

“NTP is conducting laboratory studies in rodents to fill data gaps identified in the systematic review of the animal studies.”

The NTP is discussing the research with animals, mainly rats, where effects of fluoride on the cognitive behaviour of the test animals have been reported but the fluoride concentrations are very high. And NTP’s assessment base on the review of the literature found only “a low to moderate level of evidence that the studies support adverse effects on learning and memory in animals exposed to fluoride in the diet or drinking water.” Hence the need for more research.

As part of the NTP’s research, which is currently underway, there are plans to extend studies to low fluoride concentrations more typical of that used in community water fluoridation.

The high concentrations used in animal studies is a major flaw in the anti-fluoride activist use of them to oppose community water fluoridation. For example, Mullinex et al (1995) (very commonly cited by anti-fluoride campaigners) fed test animals drinking water with up to 125 mg/L of fluoride (concentrations near 0.8 mg/L of fluoride are used in community water fluoridation).

While it is unlikely that the NTP research will find any significant effects of fluoride on the cognitive behaviour of rats at the low concentrations used in community water fluoridation the anti-fluoride campaigners have their fingers (and probably toes as well) crossed.

NTP will begin publishing the results of their new research next year (see Fluoride and IQ – another study coming up).

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Fluoridation: Open letter to Democrats for Social Credit

The only New Zealand political party opposing community water fluoridation relies on false information

The only political party in New Zealand campaigning against community water fluoridation is the Democrats for Social Credit. It is a minor party, nor represented in Parliament and of little influence. However, it does have connections with Fluoride Free NZ, the main anti-fluoride activist group, and its members have imposed anti-fluoridation policies on some groups they belong to. Two examples are Grey Power and the Hamilton Residents & Ratepayers Association – both of which presented anti-fluoride submissions to the recent parliamentary health committee hearings.

I wish to promote an open discussion with the Democrats for Social Credit about their anti-fluoridation policy so have sent them this Open Letter. If they are open to a good-faith discussion I am happy to provide space on this blog for an exchange of views on their policy.


David Trantor, Health Spokesperson for Democrats for Social Credit

Dear David Tranter,
Health Spokesman,
Democrats for Social Credit

You wrote an open letter to the Minister of Health critiquing the government’s policy on community water fluoridation (CWF) and posing some questions about dental health programmes, documented evidence relating to CWF and human rights aspects you consider relevant.

Here I take issue with some of your claims – particularly about dental health in Denmark and the scientific evidence supporting CWF. I believe the evidence does not support the anti-fluoridation policy of your party and your party should reconsider that policy.

If you believe my arguments here are mistaken or otherwise wish to defend the current anti-fluoride policy of your party I am open to a good-faith exchange of opinions and offer you the right of reply and the opportunity for a further discussion on this blog.

Natural fluoridation in Denmark

You point to the good dental health in Denmark and assert “they have never fluoridated their water.” This is true – but you ignore the fact that much of the Danish population benefits from natural levels of fluoride in their drinking water.

Unlike New Zealand parts of Denmark have drinking water fluoride concentrations similar to the optimum concentrations recommended for CWF. Map 1 from Kirkeskov et al., (2010) shows the distribution of different drinking water fluoride concentration ranges.  Map 2 shows the population distribution. We can see a significant fraction of the Danish population does have access to drinking water containing fluoride.

Map 1: Distribution of natural drinking water fluoride concentrations in Denmark. The town of Nexo is on the Baltic island of Bornholm – shown in the top left-hand rectangle.

Map 2: Population distribution in Denmark.

These natural levels of drinking water fluoride are beneficial to oral health in Denmark. Here is some data from Kirkeskov et al., (2010) illustrating this. The following graph compares the dental decay (numbers with more than 2 decayed, missing or filled teeth surfaces – dmfs) at various drinking water fluoride concentrations for 5 year-olds born in 1989 and 1999.

As we can see, the extent of decay declines with fluoride concentration.

There is a similar pattern for 15-year-olds born in 1979 and 1989. This figure shows the relative numbers with more than 2 decayed missing or filled teeth surfaces, DMFS, for 15-year-olds.

And the same pattern for 15-year-olds with more than 6 decayed, missing or filled tooth surfaces.

Danish dental health programmes

You refer to a “Nexux” programme and argue that this could be an alternative to CWF in New Zealand.

I think you are referring to the programme run in Nexo – a town on the east coast of the Baltic island of Bornholm, Denmark. It is a successful local dental health programme, but only one of several in Denmark. Nexo was in an area of very low socio-economic status and introduced a dental programme at the end of 1987 aimed at improving the dental health fo children.  Ekstrand & Christiansen, (2005) give this description of the programme:

“Since 1992, the program has been offered to children from the age of 8 months. It is based on three closely interrelated principles applied according to the individual child’s needs: (1) education of parents, children and adolescents in understanding dental caries as a localized disease, (2) intensive training in home-based plaque control and (3) early professional, non-operative intervention, including professional plaque removal, local application of 2% NaF and application of sealants. In the period when the children have erupting permanent first or second molars, the parents and children are instructed in using a tooth brushing technique specially designed for erupting molar teeth.”

As you can see it is a rather intensive programme and is not a Denmark-wide programme. It has been successful in Nexo, where 15-year-olds had DMFS (decayed, missing and filled tooth surfaces) values in 1986 (before introduction of the programme)  slightly higher than the Danish average. The equivalent values of DMFS for Nexo were the third lowest for all municipalities in 1993 and the lowest in 1999 (Ekstrand & Christiansen, 2005).

Elements of the Nexo programme will be used in other parts of Denmark, and in other countries. Especially where school-based programmes exist.

Incidentally, Map 1 indicates the concentration of natural fluoride in the drinking water on the island where Nexo is situated is similar to that recommended for community water fluoridation. Ekstrand et al., (2005) reports that the fluoride concentration in the Nexo drinking water is 0.8 mg/L.

Nexo is a complement to, not a substitute for, CWF

Each country and region adopt health programmes appropriate to their circumstance. In New Zealand, we have programmes which include some aspect of the Nexo programme or similar programmes like the ChildSmile programme in Scotland (see ChildSmile dental health – its pros and cons and ChildSmile – a complement, not an alternative, to fluoridation). For example the use of fluoride varnish treatments, especially in non-fluoridated areas.

New Zealand can learn from the experience of other countries and in practice, we may introduce some aspects of other programmes. But blanket transfer of full programmes is rare.

The important aspect, though, is none of these programmes is considered an alternative to fluoridation. They are considered as complementary to CWF, and not substitutes for CWF.  The Danish Dental Association has supported fluoridation for areas of low natural fluoride concentrations. Similarly, the British Dental Association in Scotland supports both ChildSmile and CWF and has publicly called for communities to move towards introducing water fluoridation.

In fact, we can consider that the programme used in Nexo (where the drinking water contains fluoride at 0.8 mg/L) actually complements the effect of natural community water fluoridation.

“Documented evidence”

You ask the Minister:

“Why do you ignore all the documented evidence against fluoridation instead of applying positive dental health policies such as the Denmark example?”

The “Denmark example” is dealt with above and it is not what you suggest. Similarly, I suggest the “documented evidence” you refer to really doesn’t give the viable argument “against fluoridation” you imply.

Unfortunately, you do not present any of this “documented evidence” for discussion. Perhaps, if you respond positively to my suggestion of a right of reply and an ongoing discussion, you can give this evidence.

“Informed consent”

You refer to the “H&D Commissioner’s Code of Rights” asserting that:

“no-one can be medicated without giving their informed consent” and “people have the right to give – or refuse – their INFORMED consent when fluoridation is applied to public water supplies?”

Well, I am all for people being properly informed and providing consent to the treatments used for their water supply. I see this as a democratic issue and I support democracy.

But you destroy your argument by suggesting fluoridation is a “medication” when it clearly is not – either legally or rationally. The legal argument was surely settled by the High Court decision in 2014 (see Corporate backers of anti-fluoride movement lose in NZ High Court) where Justice Rodney Hansen concluded:

“[80] In my view, fluoridation cannot be relevantly distinguished from the addition of chlorine or any other substance for the purpose of disinfecting drinking water, a process which itself may lead to the addition of contaminants as the water standards themselves assume. Both processes involve adding a chemical compound to the water. Both are undertaken for the prevention of disease. It is not material that one works by adding something to the water while the other achieves its purpose by taking unwanted organisms out.

[81] The addition of iodine to salt, folic acid to bread and the pasteurisation of milk are, in my view, equivalent interventions made to achieve public health benefits by means which could not be achieved nearly as effectively by medicating the populace individually. . . . All are intended to improve the health of the populace. But they do not, in my view, constitute medical treatment for the purpose of s 11″ [the relevant section of the NZBORA].”

Is scientific knowledge  really “one-sided” propaganda

You also weaken your argument by claiming:

“the one-sided propaganda used to support fluoridation is not informing people”

Describing objective scientific research and findings as “one-sided” simply displays your own bias – and willingness to discredit or ignore the science. Again, you do not give specific examples of the science you consider “one-sided propaganda” – hopefully, you will do so if you take up my offer of a right of reply and a continued discussion.

Democratic rights

You assert:

“when fluoridation is forced upon people it is nothing less than mass medication concerning which people have no opportunity to give – or refuse – their consent.”

The common anti-fluoride claim that people are having fluoridated water forced upon them always raises the picture in my mind of a person being held down and water being forced down their throat as in force-feeding.

Of course, that is ridiculous – for a number of reasons.

  • In New Zealand, there has usually been a democratic public consultation of some sort before the introduction of CWF – or even after its introduction. Local bodies have surveyed residents or used referenda. They have also used a consultation procedure relying on submissions from the public.The opportunity “to give – or refuse – their consent” has in most cases been far greater than for most decisions made by our representatives in this democracy of ours. Some voters find it annoying when asked for such consent (preferring their representatives decide) but I firmly believe it important to include the public in controversial decisions – even where the controversy results from scaremongering rather than facts (as it does with CWF).
  • There are alternatives for the minority. This means that democratic decisions made by a community can actually be a win-win situation. The majority get the social policy they want and have voted for. the minority have access to alternatives. In fact, most anti-fluoride activists already use alternatives – they filter their tap water or source a different supply. Some cities already provide “fluoride-free” water sources to help this. Sometimes I think the real motivation of these ideologically driven activists is to deny this social health policy to others rather than any real concern they have for their own access to water.
  • Some activists will acknowledge there is no evidence of any harmful side effects from CWF but invoke a “precautionary principle” to argue against it. They should be mollified by the fact that CWF is one of the most extensively researched topics. In a sense, we must thank the ideologically and commercially motivated anti-fluoride campaigners for this. Their activity is rarely successful in preventing CWF or fooling most of the public. But it does mean that researcher keep an eye on the arguments and are continually checking them out.

Conclusion

David, I believe you are mistaken, or misinformed, about the dental health programmes in Denmark. You ignore completely the availability of effective natural levels of fluoride in much of Denmark’s drinking water and seem unaware of the nature of the Nexo programme or its limited area of operation.

Expert opinion considers programmes like Nexo and the Scottish ChildSmile are effective complements to CWF – not substitutes for, or alternatives to, CWF. I support our health officials considering use of similar programmes in New Zealand but it is misleading for the Democrats for Social Credit to advocate for such programmes simply as a way of preventing or opposing CWF – which is  an effective, beneficial and safe social health measure.

I appreciate you may not accept my arguments or the facts I have presented here. If that is the case I urge you to accept my offer of a right of reply and ongoing good-faith discussion and am happy to help this by making space available on this blog.

I look forward to your response.

References

Ekstrand, K. R., & Christiansen, M. E. C. (2005). Outcomes of a non-operative caries treatment programme for children and adolescents. Caries Research, 39(6), 455–467.

Kirkeskov, L., Kristiansen, E., Bøggild, H., Von Platen-Hallermund, F., Sckerl, H., Carlsen, A., … Poulsen, S. (2010). The association between fluoride in drinking water and dental caries in Danish children. Linking data from health registers, environmental registers and administrative registers. Community Dentistry and Oral Epidemiology, 38(3), 206–212.

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Debunking anti-fluoridationist’s remaining 12 reasons for opposing fluoridation

New Zealand anti-fluoride campaigners have whittled their list of objections to community water fluoridation (CWF) down to 12 reasons. Maybe that’s progress – they used to tout a list of 50 reasons!

Let’s go through that list one by one and see if any stand up. I am responding here to each reason given in the Fluoride Free New Zealand’s (FFNZ) document Top 12 Reasons why Fluoridation Should End.

You can download a printable version of my responses.


1: Fluoride works by a surface reaction with existing teeth but research shows that it has a beneficial systemic effect with developing teeth.

The document asserts that “Fluoride promoters now claim that if there is any benefit from fluoride it is from contact with the surface of the tooth” and cite as their authority a High Court judge (incidentally, from a ruling that went against anti-fluoride campaigners). A High Court Judge is hardly an authority on scientific matters

Yes, the surface or “topical” action at the tooth surface is understood to be the predominant mechanism for existing teeth. The US Center for Disease Control illustrates this in its figure from the document Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States).

But, I pointed out in my article Cherry-picking and misinformation in Stan Litras’s anti-fluoride article, research also suggests fluoride is incorporated into the developing teeth of children and this helps provide protection.

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.”

Cho et al (2014) presented data showing that children exposed to CWF during teeth development retained an advantage over those never exposed to it. Systemic fluoride may not play a role with existing teeth but it does during tooth development – even if it is difficult to determine the relative contributions of systemic fluoride and “topical” or surface fluoride to lasting oral health.

2: Too much fluoride causes dental fluorosis but this is not relevant to CWF.

Some children from both fluoridated and non-fluoridated areas do exhibit dental fluorosis. This is thought to be due to excessive consumption of fluoridated toothpaste and one important factor used in determining the optimum concentration of fluoride used in CWF is to prevent the development of dental fluorosis.

Anti-fluoride propagandists usually cite horrific figures for dental fluorosis because they incorporate all forms of dental fluorosis, from the mildest to the most severe, into their figures. For example, they will cite Ministry of Health Oral Health Survey data to claim that New Zealanders have a prevalence of 45% dental fluorosis caused by fluoridation. In fact, the dental fluorosis of concern (the severe and moderate forms) is very rare and the NZ Oral Health survey (from which this data is taken) showed no difference between fluoridated and unfluoridated areas.

3: Fluoride is not a neurotoxin (or neurotoxicant) at concentrations used in CWF.

Sure, animals studies show effects at high concentrations and there are studies of possible negative cognitive effects from areas of endemic fluorosis where drinking water concentrations of fluoride are relatively high. However, studies from areas where CWF is used (Broadbent et al, 2014) or natural levels of fluoride in drinking water are similar (see More nails in the coffin of the anti-fluoridation myths around IQ and hypothyroidism) do not show any negative effect on cognitive ability. In fact, the research suggests that fluoride may actually improve cognitive ability and improve chances of employment and income in adults (see the last link).

The Lancet article cited by FFNZ did not classify fluoride as a “neurotoxin” and the only discussion of fluoride in that article related to the poor quality studies from areas of endemic fluorosis referred to above. Scientific journals publish research findings and reviews – they don’t pass regulations or get into classifications.

4: FFNZ’s reference to dose is simply an attempt to claim evidence from high concentrations studies is relevant to CWF. It isn’t.

All the research indicates that the optimum recommended concentrations used in CWF are high enough to help reduce tooth decay but low enough to have no negative health effects. Only very mild dental fluorosis. which is often judged positively by teenagers and parents, is a possible result of such low concentrations.

The US National Toxicology Review referred to will simply extend previous reviews of animal studies to include human studies. This research programme also plans to include some animal studies using low fluoride concentrations – precisely because most former studies have used high concentrations unrepresentative of CWF.

The fact that new research like this commonly occurs is a good thing as it helps guarantee that social health measures like CWF are safe and they provide confidence to the public that there is continuous monitoring that would pick up any formerly unseen problems.

5: Skeletal and dental fluorosis occurs in parts of the world with high drinking water fluoride concentration but this is not relevant to CWF

The World Health Organisation recommends that drinking water fluoride concentrations should be in the range  0.5 – 1.5 mg/l. High enough to support dental health but low enough to prevent skeletal fluorosis or dental fluorosis of any concern.

Anti-fluoride campaigners commonly refer to the negative health effects in areas of endemic fluorosis (eg., China, India, and Senegal) where drinking water fluoride concentrations are much higher than used for CWF. But those facts are completely irrelevant to the situation in countries like New Zealand. And they are irrelevant to CWF which uses much lower drinking water concentrations.

6: There is no credible evidence to suggest that fluoride is an endocrine disruptor at concentrations used for CWF

A number of animal and human studies have produced conflicting results for endocrine effects of fluoride. These studies suffer from the use of high or unspecified fluoride concentrations. Effects have sometimes been seen for human in areas of endemic fluorosis. Studies have often been confused because of confounding effects due to iodine deficiency (known to cause thyroid problems), calcium and water hardness.

This means that it is easy to cherry-pick individual studies to support claims of harm from fluoride but these are usually for areas of high fluoride concentration or the studies are flawed by the problem of confounding effects.

The authoritative 2014 New Zealand Fluoridation Review (Eason et al. Health effects of water fluoridation: A review of the scientific evidence) considered “alleged effects of CWF on health outcomes  . . . including effects on reproduction, endocrine function, cardiovascular and renal effects, and effects on the immune system. “ It concluded:

“The most reliable and valid evidence to date for all of these effects indicates that fluoride in levels used for CWF does not pose appreciable risks of harm to human health.”

7: Bottle-fed babies do not receive harmful amounts of fluoride.

The FFNZ claim they do is a common anti-fluoride misrepresentation of the health recommendations concerning CWF and bottle-fed babies. These recommendations advise that use of fluoridated water to reconstitute baby formula is not harmful. They simply suggest that parents who are concerned should occasionally use non-fluoridated water for that reconstitution – a peace of mind thing.

For example, the American Dental Association advises:

“Yes, it is safe to use fluoridated water to mix infant formula. If your baby is primarily fed infant formula, using fluoridated water might increase the chance for mild enamel fluorosis, but enamel fluorosis does not affect the health of your child or the health of your child’s teeth. ”

Where parents want to reduce the risk of dental fluorosis they:

“can use powdered or liquid concentrate formula mixed with water that either is fluoride-free or has low concentrations of fluoride.”

Arguments based on low concentrations in human breast milk simply rely on the naturalistic fallacy – the claim that something is good or right because it is natural (or bad or wrong because it is unnatural). There are common concerns about deficient levels of some beneficial elements in human breast milk and recommendations for using supplements. See, for example, Iron and fluoride in human milk.

8: Fluoridation chemicals are not contaminant-laden waste products.

For example, fluorosilicic acid, the most commonly used fluoridation chemical in New Zealand, is a by-product of the fertiliser industry. When used for water treatment it must pass rigorous restrictions on contaminant levels. Certificates of analysis are required.

contaminants-hfa

With these regulations and checks for water treatment chemicals, the concentration of any contaminant introduced into tap water by their use is much lower than the concentration of those contaminants already naturally present in the source water used. See Chemophobic scaremongering: Much ado about absolutely nothing for data based on a typical certificate of analysis for fluorosilicic acid and the natural concentrations of contaminants for the source water used by Hamilton City. The concentration of contaminants introduced into drinking water is well under 1% of the levels already naturally present in the water source (see graph).

9: Fluoridation is not a medicine and it does not violate human basic rights.

That was determined in High Court rulings – cases brought by anti-fluoride campaigners financed by the “natural”/alternative health industry. All appeals so far against those rulings have been rejected.

10:   Community water fluoridation is not suitable or necessary for many countries

A claim that only 5% of the world uses community water fluoridation is not relevant. Consider that just over 10% of the world do not have access to safe clean water so their people have more pressing concerns that water fluoridation. Many countries like China, India, and parts of North Africa use drinking water with fluoride concentrations that are excessive – fluoride removal or searches for alternative sources are their priority.

Even many developed countries or regions do not have reticulation systems which enable cost-effective fluoridation. This may be the case in Christchurch where the use of a number of bores may mean fluoridation of much of the city is not cost-effective.

Many countries already have natural concentrations of fluoride in their drinking water that are near optimum – making any supplementation unnecessary.

A recent review (O’Mullane et al., 2016) summarised the numbers of people around the world with access to beneficial levels of fluoride in their drinking water:

“General estimates for the number of people around the world whose water supplies contain naturally fluoridated water at the optimum level for oral health are around 50 million. This means that, when the numbers of people with artificially (369.2 million) and naturally fluoridated water supplies (50 million) at the optimum level are added together, the total is around 437.2 million.”

11: The effectiveness of community water fluoridation in reducing tooth decay is well established.

This fact is very often misrepresented by anti-fluoride campaigners. For example, in the FFNZ document, a recent New Zealand study is cited to argue that “there is no difference in decay rates between non-Māori children in fluoridated and non-fluoridated areas.” In fact, the authors of that study warned that the data for “non-Māori” children were misleading because it included data for Pacific Island children who have generally poorer dental health than other ethnic groups and are concentrated in fluoridated regions, thus distorting the data for non-Maori. When the data for all ethnic groups are considered separately it clearly shows the beneficial effects of community water fluoridation. This figure shows the non-Māori data corrected by removing the data for Pacific Island children. iut confirms that there is a difference in decay rates between fluoridated and non-fluoridated area.

Comparison of data for “other” (non-Māori/non-Pacifica) children in fluoridated (F) and unfluoridated (UF) areas. 5-year-old New Zealand children. dmft = decayed, missing and filled teeth.

FFNZ claims about the Cochrane Review and data from the District Health Boards and Ministry of Health are also incorrect. While the Cochrane Review did specifically exclude most recent studies because of its selection criteria it still concluded:

“Data suggest that the introduction of water fluoridation resulted in a 35% reduction in decayed, missing or filled baby teeth and a 26% reduction in decayed, missing or filled permanent teeth. It also increased the percentage of children with no decay by 15%. These results indicate that water fluoridation is effective at reducing levels of tooth decay in both children’s baby and permanent teeth.”

12: Community water fluoridation is only one part of successful dental health policies

These included regular fluoride varnishes, regular dental examinations, registering children into dental programmes, education measures such as guided toothbrushing, presenting children with toothpaste and toothbrushes, the involvement of parents in dental health and plaque checking and in dental health programmes generally. Health professionals see all these elements, including water fluoridation, as complementary. There is absolutely no suggestion that community water fluoridation means no other social dental health programme is used. However, in areas where community water fluoridation is not available health professionals will often introduce extra measures, such as wider use of fluoride dental varnishes, to help protect child dental health.

FFNZ misleads when it claims other aspects of a dental health programme can simply be substituted for water fluoridation. All parts of these programmes are complementary, one cannot normally be substituted for another.

Conclusions

So, none of the 12 reasons given by FFNZ for their opposition to CWF stand up to critical scrutiny.

Having whittled their original list down from 50 to only 12 reasons perhaps they should bite the bullet, face the facts, and continue whittling it down to zero.

That would then conform to the scientific information available.

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