Tag Archives: Fluoride Action Network

Even studies from endemic fluorosis areas show fluoride is not harmful at levels used in fluoridation

Most of the claims made by anti-fluoride propagandists are simply wrong. Image source: Fluoridation and the ‘sciency’ facts of critics

Anti-fluoride propagandists continually cite studies from areas of endemic fluorosis in their arguments against community water fluoridation (CWF). But if they critically looked at the data in those papers they might get a shock. Invariably the published data, even from areas of endemic fluorosis, shows fluoride is safe at the concentrations relevant to CWF.

I have completed a detailed analysis of all the 65 studies the Fluoride Action Network (FAN) lists as evidence that community water fluoridation (CWF) is harmful to child IQ. The full analysis is available for download as the document Analysis of FAN’s 65 brain-fluoride studies.

In this article, I discuss the studies in the FAN’s list (see FLUORIDE & IQ: THE 65 STUDIES”) which report relationships between child IQ and fluoride exposure in areas of endemic fluorosis. There are eleven such studies in the FAN list but only six of them provide sufficient data to enable independent statistical analysis.

While those six studies do show a statically significant (p<0.05) negative relationship of IQ with fluoride intake those results are not relevant to CWF because the fluoride as exposure levels are much higher than ever occurs with CWF.

However, it is possible to investigate if the relationships are significant at lower concentrations more relevant to CWF. I have done this with these six studies and illustrate the result obtained with these graphs below using the data extracted from Xiang et al (2003). (This study is often used by anti-fluoride campaigners).

The red data points in the figures below are for lower concentrations of urinary F or creatinine adjusted urinary F. The range for the red points is still quite a bit larger than urinary F levels measured for children in areas where CWF is used. However, we can see that the relationships at these lower ranges are not statistically significant (results from regression analyses cited in figures).

 

This was also the case with the other studies from FAN’s list which provided sufficient data for regression analyses. I summarise the results obtained for five of these studies in the figure below.

This show that none of the studies found statistically significant relationships with fluoride exposure for the low fluoride concentration relevant to CWF. The situation is basically the same for the sixth study, Mustafa et al (2018), which reports average school subject performances for a range of subjects for children in Khartoum state, Sudan. However, it is hard to know what the safe limit for fluoride exposure is in that climate (for climatic reasons the upper permissible F level in drinking water is set at 0.33 ppm for Khartoum state) and the sample numbers are low. Interested readers should consult my report – Analysis of FAN’s 65 brain-fluoride studies.

Conclusion

Anti-fluoride campaigners often cite FAN’s list (FLUORIDE & IQ: THE 65 STUDIES”) in their attempts to argue that fluoridation is bad for the child’s brain. But in these series of articles Anti-fluoride 65 brain-fluoride studies not evidence against fluoridation, I have shown that their arguments are false.

In Child IQ in countries with endemic fluorosis imply fluoridation is safe I showed that while IQ and other health problems may occur where fluoride exposure is very high in areas of endemic fluorosis the reports themselves implicitly assume that the low fluoride exposure in the “low fluoride” areas is safe. It is the data from these areas, not the “high fluoride” areas, that are relevant to CWF. So despite the heavy use of these articles by FAN and anti-fluoride activists these studies do not prove what they claim. If anything these studies show CWF is safe.

In this article, I considered a few of these studies which included data relevant to low fluoride exposure. When the low fluoride exposure data (relevant to CWF)  from these studies were statistically analysed none of them showed significant relationships of child IQ to fluoride exposure. That confirms the implicit assumption from these studies that there is no negative effect of fluoride exposure on child IQ at these low levels.

Finally, in Canadian studies confirm findings of Broadbent et al (2015) – fluoridation has no effect on child IQ I summarise results from the only three studies where comparisons of IQ for children living in fluoridated and unfluoridated areas are compared. These studies were made in New Zealand and Canada and the results were the same. No statistically significant differences in child IQ were found.

However, the authors of the Canadian studies ignored this result and instead used questionable statistical methods to search for possible relationships between fluoride exposure and child IQ. Most of the relationships they report were not statistically significant but, nevertheless, they and their supporters have simply ignored this and concentrated on the few statically significant relationships.

Anti-fluoride activists currently rely strongly on these studies and heavily promote them. I will discuss these few studies further in my next article.

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Canadian studies confirm findings of Broadbent et al (2015) – fluoridation has no effect on child IQ

Readers may remember the scathing reaction of anti-fluoride campaigners to the paper of Broadbent et al (2015). This was the first paper to compare child and adult IQ levels for people living in fluoridated and unfluoridated areas.

The anti-fluoride campaigners were extremely rude in their reaction – accusing the authors of fraud and claiming the paper was “fatally flawed.” Interestingly, several scientists known for their anti-fluoride bias also launched attacks – but more respectably as letters to the editor of the journal. For example, see articles by Osmunson et al (2016),  Grandjean (2015),; and Menkes et al (2014).

And why? Simply because Broadbent et al (2015) showed there was no difference in IQ of people living in fluoridated areas. That the studies from areas of endemic fluorosis used by anti-fluoride activists to argue at CWF were just not relevant (see Child IQ in countries with endemic fluorosis imply fluoridation is safe).

But isn’t it strange? Two more recent papers (Green et al 2019 & Till et al 2020) have effectively repeated the work of Broadbent et al (2015). They found the same result – no difference in IQ of children living in fluoridated and unfluoridated areas. And simply no reaction, no condemnation from anti-fluoride activists or the anti-fluoride scientists.

No condemnation because these anti-fluoride critics promote these papers for other reasons. But this underlines how biased the critics of the Broadbent et al (2015) paper were.

I have completed a detailed analysis of all the 65 studies the Fluoride Action Network (FAN) lists as evidence that community water fluoridation (CWF) is harmful to child IQ. The full analysis is available for download as the document Analysis of FAN’s 65 brain-fluoride studies.

In this article, I discuss the studies in the FAN’s list (see FLUORIDE & IQ: THE 65 STUDIES”) which compare child IQ in areas of “fluoridated” and “unfluoridated” fluoride in Canada. Only two studies – but I include that of Broadbent et al (2015) (which FAN’s list ignores) for completeness. All three studies found no difference in the IQ of children living in fluoridated and unfluoridated areas.

Comparing IQ of children in fluoridated and unfluoridated areas

The table below summarises the results reported by all three studies – Broadbent et al (2015), Green et al (2019), and Till et al (2020).

Table 1: Results from studies comparing IQ of children and adults from fluoridated and fluoridated areas

Notes:
Data from Green et al (2019) for children whose mothers lived in fluoridated or unfluoridated areas during pregnancy.
Data from Till et al (2020) for children either breastfed of formula-fed as babies while living in fluoridated or unfluoridated areas.

There is absolutely no difference in IQ due to fluoridation. Remember, the standard dedication of the values in the table are about 13 to 16 IQ points.

I have presented all the results from these papers graphically below. FSIQ is the normal IQ measurement. VIQ (Verbal IQ) and PIQ (Performance IQ) are subsets of FSIQ.

The only statistically significant differences between fluoridated and unfluoridated areas were for VIQ of breastfed babies (VIQ higher for fluoridated areas) and PIQ of formula-fed babies (PIQ lower for fluoridated areas).

Anti-fluoride campaigners and (biased scientists like Grandjean) love the Green et al (2019) and Till et al (2020) papers because they reported (very weak) negative relationships of some child cognitive measures with fluoride intake ( I discuss this in separate articles). This is largely a result of the statistical methods used – particularly resorting to several different cognitive measures and measures of fluoride exposure, as well as the separation of results according to gender. Reminds me of the old saying that one can always get the results one requires by torturing the data hard enough.

I will return to the statistical problems of these and similar papers in a separate article.

Misrepresentation by anti-fluoride activists

Anti-fluoride campaigners have latched on to the two Canadian studies – often making claims that simply are not supported. But always ignoring the data shown above.

For example – this propaganda poster from FAN promoting the Green et al (2019) study.

This completely misrepresents the results of the study. No difference was found in the IQs of children from fluoridated and unfluoridated areas. These people completely ignore that result while placing unwarranted faith in the weak relationships reported elsewhere in that paper. (In fact, Green et al (2019) found a weak significant relationship only for boys – the relationships for all children and for girls were not significant. See my articles about this statistical torture).

And this FAN propaganda poster promoting the Till et al (2020) study.

Again – completely wrong. There was no difference in IQ of formula-fed babies in fluoridated and unfluoridated areas (see Table 1 above). Even worse – FAN is misrepresenting the statistical relationships reported in this paper as there’s was no statistically significant relationship between child IQ and fluoride exposure for formula-fed our breastfed babies once the influence of outliers and/or confounders were considered.

Misrepresentation by anti-fluoride scientists

It is understandable, I guess, that the authors of the two Canadian papers make a lot of the poor statistical relationships they reported and ignored the fact that they did not see any effect of fluoridation. Perhaps they can be excused some bias due to professional ambition. But this underlines why sensible readers should always critically and intelligently read the papers in this controversial area. One should never rely on the public relations claims of authors and their institutes. But it is sad to see how scientific basis and ambitions can lead scientists to support the claims of political activists. or worse, to attack honest scientists who do post-publication peer review of the studies (see for example When scientists get political: Lead fluoride-IQ researcher launches emotional attack on her scientific critics).

I am also very critical of scientific supporters of these studies who have their own anti-fluoride motivations. Philippe Grandjean, for example, was one of the authors very critical of the Broadbent et al (2015) paper and ignored completely the fact that the Green et al (2019) and Till et al (2020) papers report exactly the same result – no effect of fluoridation on child IQ. Grandjean often makes public comments supporting the claims of anti-fluoride campaigners like FAN. He also behaved in a scientifically unethical way when he refused to allow my critique of the flawed paper by Malin & Till (2015) to be published in Environmental Health – the journal he acts as the chief editor of (see Fluoridation not associated with ADHD – a myth put to rest).

I am repeating myself but it is a matter of “reader beware.” Readers should not simply rely on the scientific “standing” of authors who are only human and suffer from the same biases as others. They should read these papers for themselves and make up their own mind about what the data actually says.

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Child IQ in countries with endemic fluorosis imply fluoridation is safe.

Anti-fluoride activists love to point out that people living in endemic fluorosis areas in countries like China suffer all sorts of health problems, including lower IQ. But studies of these areas show no lowering of IQ in the low fluoride areas relevant to community water fluoridation.

I have completed a detailed analysis of all the 65 studies the Fluoride Action Network (FAN) lists as evidence that community water fluoridation (CWF) is harmful to child IQ. The full analysis is available for download as the document Analysis of FAN’s 65 brain-fluoride studies.

In this article, I discuss the studies in the FAN’s list (see FLUORIDE & IQ: THE 65 STUDIES”) which compare child IQ in areas of “low” and “high” fluoride in countries like China, Mexico, Iran, Egypt, and India where fluorosis is endemic. In fact, all these studies either assume or provide evidence that fluoride at the concentrations used for CWF is harmless.

IQ differences for “high” and “low” fluoride areas

FAN was really dredging through very poor research to find these studies. In fact, FAN had to go to the trouble of translating many of these studies because they were obscure and not available in English.

Of their 65 studies, 17  do not provide data for fluoride intake or for drinking water fluoride concentrations. Instead, they simply describe the “high” areas as endemic fluorosis areas or areas where people suffer severe dental or skeletal fluorosis. Several of the studies used “control” groups from areas of “slight” fluorosis or dental fluorosis in contrast to skeletal fluorosis.

Another 29 studies did provide water fluoride concentrations for the “low” fluoride and “high” fluoride areas. This data is useful as it enables us to consider how relevant the results are to CWF. I have summarised the data in Figure 1.

The take-home message from Figure 1 is that while these 29 studies do show a decrease in child IQ in areas of “high” fluoride those areas are not relevant to CWF. In fact, the only relevance to CWF are the areas of “low” fluoride where there is the implicit assumption that child IQ is not affected. We can also assume this is the case for the 17 studies which do not provide details of fluoride exposure.

Figure 1: Comparison of water fluoride levels in “high” and “low” fluoride areas of 29 of the FAN studies and in areas where CWF is used.

So these 46 studies heavily promoted by FAN over recent years do not show any harm from CWF – in fact, all these studies implicitly assume there is no negative effect on child IQ at the “low” fluoride levels studied – and these are the areas most relevant to CWF. A simple consideration of the health problems faced by people living in areas of endemic fluorosis should have made it obvious that the data for high fluoride areas is simply not relevant. Consider these figures from Das et al (2016) – one never sees people like this in areas where CWF is used:

Dental fluorosis case found in the study area (age: 12, sex: male). Das et al (2016)

Skeletal fluorosis case found in the study area (age: 17, sex: male). Das et al (2016)

FAN is simply silly to suggest these studies, and especially the results for the “high” fluoride areas, area at all relevant to CWF.

Mind you, Paul Connett, FAN Director, likes to draw attention to one of these studies where he claims the “high” fluoride area has a drinking- water fluoride concentration of 0.81 mg/L which is similar to that for CWF. He is simply dredging the data (and ignoring all the other studies he cites)  to make this claim. The study he refers to was made in an area of iodine deficiency and is extremely weak – simply and half pages in a Chinese newsletter. Have a look for yourself – Lin et al (1991).

In a future article, I will discuss the studies in FAN’s list which compare IQ for children from fluoridated and unfluoridated areas.

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Anti-fluoride 65 brain-fluoride studies not evidence against fluoridation

Activists like ant-fluoride and anti-vaccination propagandists are very selective about the studies they promote. But their bias often means they get even these ones wrong. FAN’s 65 brain-fluoride studies are an example of this. Image credit: Don’t let confirmation bias narrow your perspective

Anti-fluoride and anti-vaccination activists suffer from a common activist fallacy – they believe their own propaganda. They also have a network of “natural”/alternative health industry internet sites and magazines to disseminate these beliefs and propaganda. A glaring example is a smug article, The End of Fluoridation Is in Sight, published on the Mercola.com alternative health, anti-vaccination site.

The uninformed reader looking at these alternative health industry sources might be excused for thinking that community water fluoridation (CWF) is about to end. That the scientific evidence against it is damning. But, of course, those conclusions are wrong – the science supporting CWF remains strong and the few studies activists use to argue against CWF have big flaws.

Actually, the situation is even worse than that. The studies commonly cited by anti-fluoride activists actually support CWF when they are read properly. Activists are unaware of this because they rarely read the studies they cite – most don’t get past the title, let alone the abstract, and certainly don’t bother with the real content. And they never subject these studies to critical analysis.

The Fluoride Action Network (FAN) has collected  together all the studies they argue show CWF is bad for children’s brains in a single list – FLUORIDE & IQ: THE 65 STUDIES.I have completed a detailed analysis of all the 65 studies and my full analysis is available for download as the document Analysis of FAN’s 65 brain-fluoride studies.

In fact, none of these studies in FAN’s list provides any credible evidence that CWF is harmful to child IQ. On the contrary, these studies either assume or provide evidence that fluoride at the concentrations used for CWF is harmless.

I will summarise my findings of these studies in a series of upcoming articles as my health permits (I have just spent a couple of stressful weeks in hospital).

  1. Difference studies – a simple comparison of cognitive measures in people living in “low fluoride and “high fluoride” areas. Forty-six studies made in areas of endemic fluorosis – India, China, Mexico, Iran, and Sudan. All these studies implicitly assume no negative health effects at fluoride concentration relevant to CWF
  2. Three difference studies relevant to CWF where populations in non-fluoridated and fluoridated areas are compared. All these studies show no effect of CWF on child IQ.
  3. Studies which derive relationships of cognitive measurements with fluoride exposure in areas of endemic fluorosis. Six of these studies include enough data for testing if there is a statistically significant effect at concentrations relevant to CWF – there is no effect observed in all these cases.
  4. Three studies deriving relationships for cognitive measurements with fluoride exposure in low fluoride areas where concentrations are relevant to CWF. These controversial studies involve considerable statistical manipulations and activists cherry-pick a few statistically significant relationship but ignore the many more non-significant relationships.

Read my article Analysis of FAN’s 65 brain-fluoride studies if you want the detailed analysis. Otherwise, just follow my summaries in future posts.

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Another study used by anti-fluoride activists actually shows community water fluoridation OK

Another study comparing effect in children from nonendemic areas (Dagang) and endemic fluorosis area (Jinghai) about 80km apart in the Tianjin area of China. Hardly sampling the same population.

Anti-fluoride campaigners still use studies from endemic fluorosis area of China in their campaign against community water fluoridation (CWF). This misrepresents the situation. While the control areas they use (non-endemic fluorosis areas where there are no health effects) are relevant to CWF the data from the endemic fluorosis areas where fluoride intake is high are simply not relevant to CWF.

However, some of these studies provide enough information to enable checking for health effects in the control, non-endemic fluorosis areas. I discuss one of these studies below – Cui et al (2018) – and show it finds no health effects at the low fluoride concentration relevant to CWF. The use of this study in anti-fluoride campaigns is therefore misleading.

I also show how even in his misrepresentation of this study the “Research Director” of the Fluoride Action Network (FAN), Chris Neurath, makes basic mathematical mistakes.

The citation for this study is:

Cui, Y., Zhang, B., Ma, J., Wang, Y., Zhao, L., Hou, C., … Liu, H. (2018). Dopamine receptor D2 gene polymorphism, urine fluoride, and intelligence impairment of children in China: A school-based cross-sectional study. Ecotoxicology and Environmental Safety, 165(August), 270–277.

The study used school children (7 to 12 years old) from the districts of Jinghai and Dagang in Tianjin of China (see map above). The endemic fluorosis area had drinking water fluoride concentrations of 1.52–2.49 mg/L and the nonendemic fluorosis area had drinking water fluoride concentrations of 0.20–1.00 mg/L.

Of course, the results for children in the endemic fluorosis area are simply not relevant to CWF where the drinking water concentrations are usually less than 0.8 mg/L.

ONLY THE DATA FROM THE NON-ENDEMIC FLUOROSIS AREA IS RELEVANT TO CWF.

Child IQ values were compared with urinary fluoride levels and regression analysis used to determine if there was any relationship. The children were also tested for the presence of different genes and each of three different genetic groups was considered separately.

Skewed data

The data from both endemic and non-endemic fluorosis areas were combined. That for urinary F was skewed and had to be transformed to provide the normal data distribution required for linear regression analysis. Consequently, the authors report linear regression results for the relationship of child IQ to the logarithm of urinary F [Log(UF)].

No statistically significant relationships were found for two of the genotypes (designated CC & CT) but there was a significant relationship for the genotype designated TT. Less than 14% of the children had this gene.

Figure from Cui et al (2018) showing a negative relationship of child IQ with the logarithm of urinary fluoride. Equation of fitted line is IQ = 117.48 – 9.75*Log(UF). R-squared = 0.142, p = 0.012. 95% CI for coefficient -17.21,-2.29

So, of course, the anti-fluoride campaigners simply go with the results for the children with the TT gene and ignore the results for the other 86% of children.

Nothing new here – they always ignore results that they can not use in their campaigns to confirm their biased presentations.

Analysis of the data for the low fluoride levels relevant to CWF doesn’t support activist claims

Here I will just consider the data relevant to CWF. After digitally extracting the data from the figures in the paper I restricted linear regression analysis to the children with urinary F values of less than 2 mg/L (which is still rather high for areas where CWF is used). The figure below displays that data, together with the results of linear regression analysis. Untransformed values were used because data for urine fluoride concentrations less than 2 mg/ml is normally distributed.

Linear regression analysis for the relationship of child IQ with urinary F. Children with TT gene about 44% of the sample. Children with CC and CT genes about 86% of the sample.

There were no statistically significant (p < 0.05) relationships, either for the TT variant (red triangle) or for the other variants (open circle) (CC & CT combined in this figure).

So, once again we see that if the appropriate data from these studies are used they confirm that there is no relationship of child IQ with measures of fluoride exposure at concentrations relevant to CWF (see also New study touted by anti-fluoridation campaigners actually indicates fluoridation is safe).

FAN’s “Research Director” makes simplistic mistakes

FAN plans to use studies like Ciu et al (2018) in their upcoming case against the US Environmental Protection Agency. Their aim is to attempt to establish cognitive effects as the main harms from CWF and then use studies like these to argue against CWF. Even though studies like this simply establish that there is no harm from fluoride concentration used for CWF. One hopes that the experts testifying for the EPA show how these studies are misrepresented by FAN.

FAN has provided a presentation by their “Research Director,” Chris Nerath, which they claim summarises their arguments. It’s a “pretty” PowerPoint presentation (FAN describes it as “powerful“) and may fool some people, but it just does not stand up to scientific scrutiny.

Quite apart for the misrepresentation of these scientific studies, and use of studies like Cui et al (2018) which are not relevant to CWF, Neurath simply makes basic scientific mistakes.

For example, in his slide 33, he claims that Cui et al (2018) showed a 10 point IQ loss for a 1 mg/L increase in urinary F. But that is simply not true – his mistake is that he ignored the fact that the linear relationship reported by Cui et al 2018) [IQ = 117.48 – 9.75*Log(UF)] is based on log values of urinary F where the value of the coefficient is -9.75. In other words, the 10 point loss is for an increase of urinary by a log value of 1 is equivalent to an increase from a concentration of 1 mg/L [Log(1) = 0] to a urinary F concentration of 10 mg/L ([log(10)=1].

Slide 33 from the presentation by Chris Neurath, FAN’s “Research Director” displaying an embarrassing mathematical mistake.

Let’s do the correct calculation for him. The Cui et al (2018) relationship shows an IQ value 117.48 for a urinary F concentration of 1 mg/L [Log(1)=0] and 114.55 for a urinary F concentration of 2 mg/L [Log(2)=0.301]. So the loss is only 2.9 IQ points.

Neurath thinks it sounds much better for his case to say a loss of 10 IQ points but all he has done is shown either he did not read Cui et al (2018) properly or does not understand a simple mathematical relationship.

However, I should stress Neurath’s argument is irrelevant to CWF, as well as being mathematically wrong because its analysis includes data from endemic fluorosis areas. In fact, there is no statistically significant relationship between child IQ and urinary fluoride either for the overall group or for the separate genetic groups considered.

“Safety threshold”

The graph in Neurath’s slide is adapted from Cui et al (2018) which made an attempt to determine a “safety threshold of urine fluoride levels for IQ
impairment” for the children with the TT gene. They defined this “safety threshold” as the urinary fluoride value corresponding to the mean IQ for the group. This seems arbitrary to me and the authors make no attempt to justify the definition.

They then divided the data into quintiles according to urinary fluoride values. Quintile 4 was the first quintile where the mean IQ value is below the mean IQ for the whole group so they assumed to mean log(UF) for that quintile to represent the “safety threshold.”

It all seems quite hairy to me – but I suppose the method produces a few data points which Neurath was able to plot on a graph and make to appear impressive. But look at the spread of the data (Neurath does not show this) in the graph below where the bars represent the spread of data for each quintile and the dotted line is the mean IQ value for the group. The spread is hardly surprising – the overall data is very scattered and only about 9 data points were used for each quintile.

I frankly think this method of determining a “safety threshold” is meaningless. We could do exactly the same with the data where urinary fluoride is less than 2 mg/L – much more relevant to CWF. This is the result – using quartiles of about 8 data points each.

Quite meaningless.

There are many other misrepresentations and mistakes in Chris Neurath’s Powerpoint presentation and I may return to some of them later. However, let’s hope the court recognises these and rejects FAN’s attempts.

Conclusion

Anti-fluoride activists continually use studies from areas of endemic fluorosis in their campaigns against CWF. However, when the actual data relevant to community water in these studies are considered they usually show no health effect.  There is no doubt that people living in endemic fluorosis areas suffer a range of health problems. But where these studies provide complete data they almost always could be used to support CWF.

Activists like FAN and their “Research Director” simply clutch on to any study they can finds which appears to show harmful effects of fluoride and ignore the fact that they are hardly ever relevant to the fluoride concentration used in CWF. They cherry-pick and ignore, or cover-up, any information not supporting their bias.

This approach is hardly scientific. It is not objective and never undertakes a critical review of the studies used. These activist display a thoughtless approach to scientific research when they opportunistically use scientific studies like this. Their approach is unthinking and it is hardly surprising that they make simple mathematical and statistical errors like the one described here and made by Paul Connett recently (see and Author confirms anti-fluoridation activist misrepresentation of her work).

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Anti-fluoridation propaganda now relies on only four studies. 3: Riddell et al (2019)

Connett promotes Riddell et al (2019) as one of the only four studies one needs to read about fluoridation. But he misunderstands and misrepresents the findings of this study. Image credit: Fluoride Action Network – with my addition.

For earlier articles in this series see:

Part 1: Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018).

Part 2: Anti-fluoridation propaganda now relies on only four studies. 2: Green et al (2019).

Paul Connett, director of the Fluoride Action Network (FAN), now claims “You only have to read four studies…” to come to the conclusion that community water fluoridation (CWF) is bad for your health. As I said in the first article in this series that is simply bad science. One should not ignore all the other relevant studies – and anyway, these four studies do not say what Connett claims.

In this article, I discuss the third study Connett recommends. It’s citation is:

Riddell, J. K., Malin, A., Flora, D., McCague, H., & Till, C. (2019). Association of water fluoride and urinary fluoride concentrations with Attention Deficit Hyperactivity Disorder in Canadian Youth. Submitted to Environment International, 133(May), 105190.

Riddell et al (2019)

Connett switches his attention from IQ to ADHD saying:

 “The third came in 2019 and found a staggering 284% increase in the prevalence of ADHD among children in fluoridated communities in Canada compared to non-fluoridated ones.”

This is just so wrong – Connett has misinterpreted the findings in this paper and completely covered up the fact that the results were dependent on age. He may well be “staggered” but he has made a bad mistake.

The results reported in Riddell et al (2019) are a mixed bag and somewhat confused – see Table 4. They could not find any significant effect of urinary F (UF) on the diagnosis of ADHD – a result that disappointed them as they understood UF to be the most reliable measure of fluoride exposure. They did find a significant effect of CWF status on ADHD diagnosis (increase odds of diagnosis) but only for older children. There was also a significant effect for water-F.

Table 4: Results of logical regression of ADHD diagnosis against measures of fluoride exposure obtained by Riddell et al (2019). Red tringel indicates significant effect.

But Connett confused himself when attempting to interpret Riddell’s results for the effect of CWF – probably because he did not understand the difference between linear and logical regressions. Riddell et al (2019) did not use data for ADHD prevalence (as Connett implied) so could not produce a relationship of prevalence to CWF. Their data was binary – ADHD diagnosis vs no ADHD diagnosis – and they determined the chance of an ADHD diagnosis in fluoridated compared with unfluoridated areas. Here is how they describe that result:

“Specifically, at the 75th percentile of age (14 years old), the predicted odds of an ADHD diagnosis was 2.8 times greater among youth in a fluoridated region compared with youth in a non-fluoridated region (aOR=2.84, 95% CI: 1.40, 5.76, p < .01), whereas among youth at the 25th percentile of age (9 years old), the predicted odds of an ADHD diagnosis was similar across CWF status (aOR=0.91, 95% CI: 0.41, 1.99, p=.81; Table 4).”

So there was no “staggering 284% increase in the prevalence of ADHD among children in fluoridated communities .  .” Just that the chance, or predicted odds, of an ADHD diagnosis was 2.84 times greater for 14-year-old youth in fluoridated areas (but the same for 9-year-olds). The odds ratio of 2.84 is still relatively small (see Rules of thumb on magnitudes of effect sizes). And Connett ignored the fact this result was age-specific.

They also report results for the hyperactivity/inattention subscale score from the Strengths and Difficulties Questionnaire (SDQ h/i). Again, no significant effect of UF but significant effects of CWF and water-F for older children. I won’t comment on this further because the data reported in the paper is confused – probably because of a mistake in the paper’s Table 4. I have emailed Julia Riddell about this problem but not yet had a reply.

Connett’s claim of a “284% increase in the prevalence of ADHD” due to fluoridation is simply wrong and demonstrated he did not understand the statistical analysis used in this paper. 

Tomorrow I will discuss the fourth study Connett now relies on – Till et al (2020) – see Anti-fluoridation propaganda now relies on only four studies. 4: Till et al (2020).

See also:

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Anti-fluoridation propaganda now relies on only four studies. 2: Green et al (2019)

Paul Connett is putting all his eggs in one basket. He says “you only have to read four studies” to find community after fluoridation harmful. Image credit: Fluoride Action Network newsletter.

For part 1 of this series see Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018).

Paul Connett, director of the Fluoride Action Network (FAN), now claims “You only have to read four studies…” to come to the conclusion that community water fluoridation (CWF) is bad for your health. As I said in the first article in this series that is simply bad science. One should not ignore all the other relevant studies – and anyway, these four studies do not say what Connett claims.

In this article, I discuss the second study Connett recommends. It’s citation 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.

Green at al (2019)

According to Connett:

“The second* came in 2019 when a study published in JAMA Pediatrics essentially replicated the Mexico City finding in Canadian communities.”

Table 2 summarises the results obtained by Green et al (2019). Let’s compare them with the results found by Bashash et al (2018) as presented in the first article in this series – Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018).

Table 2: Summary of results from Green et al (2019). Red triangles indicate a statistically significant relationship.

Note: See Table 1 for an explanation  of symbols and bars

No, Green et al (2019) did not “replicate” the findings of Bashash et al (2017) – although Connett may be using the word “essentially” to cover up his over-confidence in the claim.

Unlike Bashash et al (2017), Green et al (2019) did not find a statistically significant relationship of child IQ (FSIQ) with MUF. However, when they separated the children by sex the relationship was significantly negative for males (positive, but not statistically significant, for females). They also reported statistically significant relationships of IQ with maternal F intake estimated using an unvalidated subjective method, but not with drinking water F.

When the IQ (FSIQ) was separated into subsets no significant relationship was found for verbal IQ (VIQ) but there was a significant relationship with MUF of performance (PIQ) for boys. There was also a significant relationship of PIQ with drinking water F. So quite a mixed bag – and perhaps indicating that separating the data into different groups based on sex and using different cognitive measures can tweak out significant relationships. But it reminds me of the old saying that one can get the answer one wants if the data is tortured enough.

As for the statistically significant relationships reported by Green et al (2019) – none of them are at all “strong” as can be seen in these figures taken from the paper:

Antifluoride campaigners use of this paper in their propaganda relies on a very weak relationship which, according to Green (2018) explains only 4.7% of the variance in IQ, and required separation of children by sex to get statistical significance.

Polishing data and ignoring non-significant relationships

A concern I have about this study is the differences in the findings reported in the original MA thesis of Green (2018) and the final paper of Green et al (2019). For example, the thesis reported an adjusted association of FSIQ with fluoride intake (B = -3.82, 95% CI: -7.65 to 0.02, p = .05) which she describes as having “just missed significance” while the final paper reports this association as significant (B = -3.66, 95% CI: -7.16 to -0.15, p = 0.04). What was done to move this association into statistical significance?

I am also concerned that not all the non-significant associations recorded in the thesis are reported in the final paper. For example, Green (2018) reported that neither VIQ or PIQ was significantly associated with fluoride intake and VIQ was not significantly associated with water fluoride concentration and these facts were not reported in Green at al (2019). On the other hand, the significant relationship of PIQ with water fluoride concentration was reported in the final paper.

Selectively reporting results of statistical analyses like this gives a false impression of how important the results may be in practice. Sure, I can understand why authors will bias their presentation in this way but a good peer review should identify this bias and insist on the presentation of complete results.

Oh, and the overall comparison of child IQ from areas of residence of their mothers during pregnancy did not show any statistically significant difference due to fluoridation in Green et al (2019) – see Table 3.

Table 3: Comparison of cognitive scores obtained by Green et al (2019) for children of mothers living in fluoridated and unfluoridated areas during pregnancy

Connett is wrong to claim that the Green et al (2019) study “replicated” the Bashash et al (2017). It didn’t by a long shot. The study itself is also very weak, it has several faults and has been widely criticised in the scientific community.

Tomorrow I will discuss the third study Connett now relies on – Riddell et al (2019) – see Anti-fluoridation propaganda now relies on only four studies. 3: Riddell et al (2019).

See also:

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Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018)

This is the advice from the very top of the anti-fluoride movement – Paul Connett, director of the Fluoride Action Network (FAN). Don’t worry about reading  up on all the scientific information “You only have to read four studies…”

Of course – that is bad science. To ignore all the other information and rely just on four studies. But it is also bad science as those specific studies were chosen by Paul Connett because he believes they confirm his bias that community water fluoridation (CWF) is bad for you (they don’t actually). He consistently ignores studies which contradict his bais. But it is also bad science because these studies are weak and their results contradictory. Connett is simply into confirmation bias. He uses misrepresentation and mistaken interpretation of these studies to support his claims.

Connett acknowledges problems with high fluoride studies

Connett admits in his Fluoride Action Network (FAN) Bulletin from March 24, 2020:  “You only have to read four studies…” that “Many of the earlier studies were in places with elevated natural fluoride levels.” Yes – they are overwhelmingly from areas of endemic fluorosis, mainly in China, where health problems are very common and obvious. They have no relevance to community water fluoridation (CWF) – but this did not stop Connett, FAN and the whole anti-fluoride movement using them in their propaganda opposing a safe, effective and economic health policy known to reduce child tooth decay.

Then he goes on to claim:

“There is now very strong evidence that fluoride damages both the fetal and infant brain at the levels used in artificially fluoridated areas.”

“You only have to read four studies to realize that deliberately adding fluoride to drinking water unnecessarily endangers children’s brains.”

Let’s be scientific about it and have an objective and critical look at the specific studies Connett now relies on. I will discuss each of these four studies in separate articles. Here is my critique of the first one – Bashash et al (2017)

Bashash et al (2017)

The citation for this paper is:

Bashash, M., Thomas, D., Hu, H., Martinez-mier, E. A., Sanchez, B. N., Basu, N., … Hernández-avila, M. (2017). Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6 – 12 Years of Age in Mexico. Environmental Health Perspectives, 125(9).

Connett says:

“The first* came in Sept 2017 with a groundbreaking study from Mexico City. This study found a strong association between the amount of fluoride women were exposed to during pregnancy and lowered IQ in their offspring.”

Don’t take Connett’s word for this – read the paper and actually look at and consider the data.

Table 1 illustrates results from Bashash et al (2018) and from Thomas (2014) and Thomas et al (2013, 2014 & 2018): These all used the same or similar data from the ELEMENT database. The red triangles represent statistically significant relationships. All other relationships are not statistically significant.

Table 1: Summary of data from papers using the Mexican ELEMENT database. Red triangles indicate a statistically significant relationship.

Note: The coefficients were obtained from linear regression of full-scale child intelligence quotient (IQ), general cognitive index for the child (GCI) or mental development index of the child (MDI) against urinary fluoride for the child (UF) or prenatal urinary fluoride for the mother (MUF), adjusted in some cases using urine specific gravity (MUFsg) or urine creatinine concentrations (MUFcr). Bars represent the 95% confidence intervals of coefficients of the change of cognitive measure with an increase in fluoride measure. The red triangles represent statistically significant relationships. All other relationships are not statistically significant.

No relationship of child IQ with child urinary F:

Connett does not mention that there is no significant relationship of child IQ with fluoride exposure as measured by the child urinary F (UFsg) and he is also silent about the Thomas (2014) thesis which also showed no relationship of child MDI with child UF – although when Thomas (2014) separated data by sex she found a statistically significant positive relationship of IQ with UF for males.

Relationships with maternal prenatal urinary F – but very weak:

Yes, there are significant relationships of child IQ (6 – 12-year-olds) or child GCI (4-year-olds) with MUF – but contrary to Connett’s claim these relationships are far from “strong.” (Thomas did not find a significant relationship of MDI with  MUF for children of ages 1 to 3  but reported – in a conference poster paper Thomas et al 2018 – a statistically significant relationship for MUF corrected using creatinine concentrations – see  A conference paper on the maternal prenatal urinary fluoride/child IQ study has problems).

These figures from Bashash et al (2017) illustrate how scattered the data is:

While statistically significant the reported relationships are extremely weak – explaining only about 3.6% of the variance in IQ and 3.3% of the variance in GCI (see Maternal urinary fluoride/IQ study – an update). The large standard error of the regressions (9.8 for IQ and 12.9 for GCI) also indicate that the estimates of IQ change (-5.0) and GCI change (-6.3) for an increase of MUF of 1 mg/L  have no predictive value (see Maternal urinary fluoride/IQ study – an update).

Connett is very wrong to claim that “This study found a strong association . . .” It simply didn’t.

Tomorrow I will discuss the second study Connett now relies on – Green et al (2019) – see Anti-fluoridation propaganda now relies on only four studies. 2: Green et al (2019).

See also:

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EPA comprehensively debunks anti-fluoride claims of a fluoride-IQ effect

FAN propaganda video promoting their petition to the EPA to stop community water fluoridation

The US environmental Protection Agency (EPA) has denied an anti-fluoride petition to ban community water fluoridation. The document outlining its reasons for declining the petition is valuable because it considers all the arguments and evidence presented in the petition and comprehensively shows them to be misleading or even false.

This is a humiliating defeat for the petitioners – the US  Fluoride Action Network (FAN), Food & Water Watch, Organic Consumers Association, American Academy of Environmental Medicine, International Academy of Oral Medicine and Toxicology and Moms Against Fluoridation. FAN, and in particular Michael Connett, had put a lot of work into their petition. The petition is a 76-page document, heavily referenced and, importantly, presenting all the best arguments that FAN could find. FAN did not keep any of their powder dry.

Of course, FAN and their associated international groups, Facebook pages and websites heavily promoted this petition. They had high hopes – Paul Connett himself has argued that their evidence would bring about the complete demise of community water fluoridation within a few years. The local Fluoride Free NZ issued a press release with the heading EPA Petition Could Spell End of Fluoridation claiming “FAN’s assessment provides unequivocal proof that current allowable levels of fluoride are not protective for all members of the population from damage to the brain.” Mary Byrne, their spokesperson asserted:

“Fluoridation belongs to a by-gone era and far too much is now known about adverse health effects for any further consideration on fluoridation to be seriously considered.”

Many anti-fluoridation submissions to the Parliament Health Committee considering changes to fluoridation legislation in New Zealand have relied strongly on the FAN petition – presenting it as the best thing since sliced bread.

Serious consideration

The EPA did give the petitioners arguments serious consideration – as we should expect from such an authoritative organisation. The petition was not rejected out of hand – the EPA’s 50-page document eexaminesthem in detail.

This is what makes the EPA document so available – it considers all the FAN arguments, the scientific papers presented and the evidence claimed. It shows how many of these papers and claimed evidence are misrepresented by the petitioners. It points to the limitations of the studies FAN relies on. It shows how FAN has not even established a case for reconsideration of recommended safe levels for fluoride and explains that the methodology used by FAN, and the recent publication by FAN staff (Herzy et al., 2016 – see Debunking a “classic” fluoride-IQ paper by leading anti-fluoride propagandists), is not valid.

The documents overall assessment of the petition’s arguments is damning:

“The petition has not set forth a scientifically defensible basis to conclude that any persons have suffered neurotoxic harm as a result of exposure to fluoride in the U.S. through the purposeful addition of fluoridation chemicals to drinking water or otherwise from fluoride exposure in the U.S. Still less has the petition set forth a scientifically defensible basis to estimate an aggregate loss of IQ points in the U.S, attributable to this use of fluoridation chemicals. As noted previously, EPA has determined the petition did not establish that fluoridation chemicals present an unreasonable risk of injury to health or the environment, arising from these chemical substances’ use to fluoridate drinking water “

Some specific rejections

The petition argued about 12 points and the EPA responded to all of them. Here are a few extracts.

The central claim of the anti-fluoride petitioners is that  Fluoride is neurotoxic at levels relevant to U.S. population. It cited human studies to support this but the EPA document responded by pointing out “the petition ignores a number of basic data quality issues associated with the human studies it relies upon.”

A central problem is the lack of  consideration of other factors possibly involved in influencing IQ – confounders:

“The petition . . .  does not properly account for the relatively poor quality of the exposure and effects data in the cited human studies (e.g., it appears to give all studies equivalent weight, regardless of their quality). When an association is suggested between an exposure and a disease outcome, the studies need to be assessed to determine whether the effect is truly because of exposure or if alternate explanations are possible. The way to do that is to adjust for potential confounders, such as diet, behavior, and socioeconomic status, in order to appropriately assess the real relationship between the exposures to a specific substance and health effects. In other words, when these confounding factors are potentially present, but not recognized or controlled for, it is not possible to attribute effects to the contaminant of concern (fluoride) as opposed to other factors or exposures. The evidence presented did not enable EPA to determine whether various confounding factors (e.g., nutritional deficiencies) were indeed placing particular subpopulations at a “heightened risk of fluoride .”

The issue of confounders is central to the petitioners claim that recent epidemiological studies corroborate neurotoxic risk in Western populations. The petition cites two studies from Western populations to attempt to corroborate the assertion that exposure to fluoridated water presents unreasonable risks for neurotoxicity. I have discussed these in previous posts – Peckham et al (2015) which claim to show that hypothyroidism is related to fluoridation and Malin & Till (2015) which demonstrated a relationship of ADHD prevalence to extent of fluoridation.

The EPA response says of the Peckham et al (2015) paper that:

“Adjustment for some confounders was considered, including sex and age, but other potential confounders (such as iodine intake) were not assessed. Fluoride from other sources and other factors associated with hypothyroidism were not assessed in this study.”

Iodine deficiency is a well-known factor in hypothyroidism.

The EPA response was relatively kind in its comment on the Malin & Till study:

“Although it is possible that there may be biological plausibility for the hypothesis that water fluoridation may be associated with ADHD, this single epidemiological study is not sufficient to “corroborate” neurotoxic health effects, as stated in the petition. More study would be needed to develop a body of information adequate.”

I showed in my article ADHD linked to elevation not fluoridation that once factors like elevation, poverty, and house ownership were included there was no statically significant relationship between ADHD prevalence and the extent of fluoridation in Malin & Till’s data. That is a clear example how conclusions based on correlations can be completely wrong when confounders are not properly considered.

The petitioners fell back onto their claim that neurotoxic risks of fluoride are supported by animal and cell studies – a common anti-fluoride tactic. However, the EPA document responded by pointing out that the petitioners had misrepresented such studies. It pointed out that these studies had been recently reviewed by the US National Toxicity Program (NTP) and the petitioner’s misrepresentation of the studies:

“do not change EPA’s agreement with the conclusions of the NTP report that their “[r]esults show low-to-moderate level-of-evidence in developmental and adult exposure studies for a pattern of findings suggestive of an effect on learning and memory.”

The petitioners claim susceptible subpopulations at heightened risk from CWF is a common claim of anti-fluoride propagandists. The EPA found this argument unconvincing:

“The data and information provided in the petition do not support the claims that “nutritional status, age, genetics and disease are known to influence an individual’s susceptibility to chronic fluoride toxicity.”

The petition argued there were no established benefits of CWF to public health. The EPA responded by outlining some of the evidence for CWF benefiting oral health and responded to the petitioners claims with:

EPA does not believe that the petition has presented a well-founded basis to doubt the health benefits of fluoridating drinking water.

Despite not showing that community water fluoridation is linked to IQ losses the petitioners asked that because fluoridation covers a large population any harm would affect a large number of people so drinkign water fluoridation should be stopped on those grounds alone. Incidentally, Hirzy et al (2016) promised a future paper where they estimate economic losses to the USA because of fluoridation. I guess they will just ignore the Swedish work that actually shows drinking water fluoride levels are positively related to increased income and chances of employment (see Large Swedish study finds no effect of fluoride on IQ).

The EPA response to this argument:

As noted previously, EPA has determined the petition did not establish that fluoridation chemicals present an unreasonable risk of injury to health or the environment, arising from these chemical substances’ use to fluoridate drinking water. The fact that a purported risk relates to a large population is not a basis to relax otherwise applicable scientific standards in evaluating the evidence of that purported risk.

I like that bit about “relaxing scientific standards.” Doesn’t it just describe the whole approach of the anti-fluoride propagandists to the science?

What now?

According to the rejection letter the Petitioners, the Fluoride Action Network and their ideological mates can appeal the declining of their petition:

“by commencing a civil action in a U.S. district court to compel initiation of the requested rulemaking proceeding within 60 days of the date of this denial letter.”

The letter was dated February 17 – so they have until mid-April to get this underway. Michael Connett – who did the heavy lifting in the preparation of this 76-page petition – is an attorney so may be more capable with such legal action than he appears to be with the scientific arguments.

fluoride-theology

At the moment anti-fluoride propagandists appear more concerned with the theological questions related to leprechauns than they are with the EPA’s rejection of their petition.

At the moment the anti-fluoride groups, including those in New Zealand, are silent. It’s as if they did not receive their rejection letter almost 10 days ago. Perhaps they are busy debating their possibilities – and the public stance on this rejection they will eventually have to take.

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Anti-fluoridationist’s flawed attacks on Calgary study

antiscience-logic-web

Image credit: Why I will no longer approve anti-fluoride dishonesty – New Anthropocene

The anti-fluoride propagandists are at it again – attacking a recently published scientific paper because the reported data does not fit with their own agenda.

The are attacking this paper:

McLaren L, Patterson S, Thawer S, Faris P, McNeil D, Potestio M, Shwart L. (2016) Measuring the short-term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices. Community Dent Oral Epidemiol 2016.

The Fluoride Action Network (FAN) claims the study is “fatally flawed” and that “key data [was] omitted.” The local FAN organisation – Fluoride Free New Zealand (FFNZ) has gone further claiming the study is “basically a fraud.”

Serious (even slanderous) accusations – let’s see if those charges hold up.

What did the study find?

The paper reports changes in dental caries levels of grade 2 children in Alberta, Canada between 2005/2005 and 2013/2014. Two cities were chosen – Calgary (which stopped fluoridation in May 2011 – after having been fluoridated since 1991) and Edmonton where fluoridation started in 1967 and is still in place. This enabled an assessment of the effect of fluoridation cessation on the dental health of children in Calgary.

Dental caries actually increased in both cities but the data shows a larger increase in dental caries where fluoridation had been stopped (Calgary) than where it continued (Edmonton).

mean-defs

defs = decayed, extracted (due to caries) filled primary tooth surfaces.

The change in Calgary (3.8) is greater than for Edmonton (2.1) and the difference is statistically significant.

The above graphic is for all tooth surfaces – similar results were obtained with smooth surfaces only – Calgary change = 2.9 and Edmonton change = 1.6.

Important features of study

There are several important features of the paper and the data reported:

1: Whereas previous cessation studies had used tooth-level data this study used tooth surface-level data. The authors had previously reported tooth level data which showed similar results.

The WHO prefers and recommends tooth surface-level data to evaluate an intervention such as starting or stopping fluoridation because of its greater sensitivity. The study authors used  tooth surface-level data and focused on smooth tooth surfaces which are most likely influenced by fluoride in this age group.

Most earlier fluoridation cessation studies had used less sensitive tooth-level data so this study was a definite improvement

2: A comparison (or “control”) city was used – Edmonton. Many previous cessation studies suffered from not using a comparison community. Interpretation is more difficult without some sort of “control” as changes due to other factors may be important. Factors like different assessment personnel, changes in diet (eg sugar consumption or bottled water), changes in dental health care, etc. It is difficult to take account of all factors but the inclusion of a similar comparison community helps reduce their effects on the results.

Again, this study was a definite improvement over previous cessation studies which had not used a comparison community.

3: Pre-cessation data were collected several years before cessation. The authors list this as a limitation, saying:

“it would have been preferable to have data collected closer to the year of cessation.”

However, this being the real world, the study used the only tooth surface-level data available for Calgary and Edmonton. There was absolutely no question of data being omitted (or “fraud”) that the anti-fluoride campaigners allege.

So how has FAN supported their charges?

Well, basically by retreating from (or ignoring) the advantages of this study – use of tooth surface-level data and use of a comparison community.

1: They use the limitation that the pre-cessation tooth surface-level data was collected several years before cessation to resort to more recent 2009/2010 data. But, importantly, that data is not tooth surface-level and it is for only one city – Calgary! 

So, they claim, the researchers “omitted key data” – the 2009/2010 data – pretending the researchers had  “hidden” it. But that data was not surface-level data. And, far from “hiding,” it the same research group specifically used this tooth-level data in an accompanying  paper:

McLaren L, McNeil D, Potestio M, Patterson S, Thawer S, Faris P, Congshi S,  Shwart L. (2016). Equity in children’ s dental caries before and after cessation of community water fluoridation: differential impact by dental insurance status and geographic material deprivation. International Journal for Equity in Health 15: 24

2: They ignore completely the importance of using a comparison community. Sure, they might claim that no survey was taken in Edmonton in 2009/2010. But they have thrown the baby out with the bath water in their attempt to discredit the research. They have fallen back on the limitation of so many fluoridation cessation studies which rely on cross-sectional measurements at different times without using a control. Worse still, they do this despite the tooth surface-level data for Edmonton showing an increase in dental caries even though there had been no cessation of fluoridation! They are willingly falling into the trap of ignoring all the other factors which could influence the results.

3: The FAN press release attempts to discredit the researchers saying:

“The lead author of the study, Lindsay McLaren, is not an independent scientist on the fluoridation controversy.”

This “damning by association” of researchers with their institutions, the fact that they receive a wage from their employers and that they write articles about their scientific results (which do not support the claims of the anti-fluoridation lobby) is really disingenuous. It’s a way of discrediting any scientist who produces results an anti-science group does not like. (Anti-science groups often use this argument – for example, anti-fluoride activists haver told me I am not “independent” because I once worked as a scientific researcher and,  therefore, cannot be trusted!).

Ironically, they are hanging themselves with their own rope on this one. Their press release makes mileage by quoting an assessment from an “independent” scientist Dr Trevor Sheldon. I checked with Sheldon and he confirmed that he:

“was invited to comment on this by Fluoride Action Network.  I did not have much time to do this but agreed to do so and received no incentive or reward.”

Now, doesn’t that admission  compromise Sheldon as an “independent” commentator? He immediately responds to a request from an activist political organisation, a group funded by the “natural”/alternative health industry – without any qualms! That confirms in my mind the links and political sympathies Sheldon has with FAN that I have long suspected.

It is perfectly normal (and healthy) for credible scientists to disagree with published papers and there are publication mechanisms to do this effectively. For example “letters to the editor” or comments in the specific journal – or even alternative journals. The fact Sheldon chose an almost immediate critique in the newsletter of a political activist group confirms to me that he is not “independent” on this subject and that he, in effect, belongs to the stable of “tame” anti-fluoride scientists FAN makes regular use of in their press releases. People like Bill Hirzy, Kathleen Theissen, Bill Osmunson, Hardy Limeback, etc.

Some other critical details

FAN relied on Sheldon’s evaluation for their main criticism but there are other details in that evaluation which I can comment on.

1: Sheldon would have preferred “a randomised controlled trial where areas are randomly allocated to start/cease water fluoridation.”

Yes, that would have been nice wouldn’t it.But the fact this has never been done – and Sheldon himself has never initiated such a trial – rather indicates how impossible such a trial is. The Cochrane review of community water fluoridation, which anti-fluoride campaigners love to misrepresent, commented on the silliness of such complaints:

But the fact this has never been done – and Sheldon himself (and similar anti-fluoride critics) has never initiated such a trial – rather indicates how impossible such a trial is. The Cochrane review of community water fluoridation, which anti-fluoride campaigners love to misrepresent, commented on the silliness of such complaints:

“particularly for research questions where evidence from randomised controlled trials is never going to be available due to the unfeasibility of conducting such trials. Community water fluoridation is one such area.”

2: He attempts to  extrapolate from tooth-level data to “fill in the gaps” in the tooth surface-level data. This highly speculative analysis allows him to conclude that most of the increase in dental caries shown by children in Calgary occurred before the cessation of fluoridation.

He accuses the researchers of making a “heroic assumption” but it seems to me the assumptions involved in his extrapolation are worse than “heroic.” Yet  the analysis enables him to make conclusions which seem to be derived more from confirmation bias than from intelligent analysis of the data. Especially as he ignored any data from Edmonton.

3:  He comments on problems resulting from population movements, confounding factors, assessment methods and staff differences, sample size differences, etc. But these are common problems when attempting to make sense of existing data. Importantly, these problems and worse, plague the cessation studies that anti-fluoride campaigners continually quote to support their claims that community water fluoridation is ineffective.

Summary

The Calgary/Edmonton study does not have the limitations of most fluoridation cessation studies – in particular, a comparison community was used and the more sensitive and appropriate tooth surface-level data was used rather than tooth-level data. The period between the first assessment and cessation is an admitted limitation but certainly does not indicate the omission of data or hiding data as anti-fluoridationists are claiming. There was just no intermediate data available.

The resort to speculative extrapolation of tooth-level data for only Calgary is disingenuous as it ignores the low sensitivity of that data and the influence of other factors compensated for by the use of Edmonton as a comparison community.

Anti-fluoridation campaigners often make ready use of older cessation studies which showed no effect – despite the obvious limitation. In particular, they often use studies where no comparison community was included and ignore completely the other factors involved such as changes in dental health provisions or social health policies such as replacing fluoridation with mouth rinse campaigns.

It is, therefore, ironic for them to come out fighting in an attempt to discredit a study which has fewer limitations than the ones they rely on. Worse, to accuse researchers of purposely omitting data – or even of scientific fraud.

The real reason for these attacks on honest researchers is that the data just does not fit the anti-fluoridation agenda and therefore, in their eyes, must be discredited.

Oh, and beware of such activists using the word “independent’ to describe a researcher. It inevitably indicates someone with allegiances to their campaign. Someone who can be relied on to give the appropriate quote to be used in their press releases.

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