An open letter to Paul Connet and the anti-fluoride movement

Image credit: How to Effectively Share Your Knowledge

Paul Connett and Vyvyan Howard have, through the local Fluoride Free New Zealand activist group, published an open letter addressed to NZ scientists and educators (see An Open Letter To NZ Scientists And Educators). It is strange to encourage scientific exchanges through press releases but if they are seriously interested in an exchange of informed scientific opinion on the research they mention I am all for it.

In fact, I renew my offer to Paul Connett for a new exchange on the new relevant research along the lines of the highly successful scientific exchange we had in 2013/2014 summarised in Conett & Perrott (2014) The Fluoride Debate.

Connett and Howard say they felt “let down” by the reception they received in their 2018 visit. But they should realise this sort of ridicule is inevitable when a supposedly scientific message is promoted by activist fringe groups with known funding by big business (in this case the “natural”/alternative health industry). The science should be treated more respectably and discussed in a proper scientific forum or via a proper scientific exchange rather than political style activist meetings.

It is this sort of respectable, informed and open scientific exchange I am offering to Paul Connett and Vyvyan Hoard.

Connett and Howard argue that there has recently been  “a dramatic change in the quality of these [fluoride] studies.” I agree that new research occurs all the time and there is plenty of scope upgrading of the scientific exchange we had in 2013/2014 to cover that new research. Consideration of the new research requires the objective, critical and intelligent consideration scientists are well used to and this is not helped by activist propaganda meetings. So I encourage Connett and Howard to accept my offer. after all, if they are confident in their own analysis of this research what do they have to lose?

Inaccuracies in “open letter”

One can see an “Open letter” as displaying a willingness to enter into a proper scientific exchange. However, Connett and Vivyan’s open letter includes inaccuracies and misinformation on the new research which simply demonstrates that a one-sided presentation cannot present the research findings properly.

For example, they misrepresent the 2014 New Zealand fluoridation review of Eason et al (2014). Health effects of water fluoridation: A review of the scientific evidence. Even to the extent of mistaking the authors (not Gluckman & Skegg as they claim) and misrepresenting the small mistake made in the summary which was later corrected. That attitude does not bode well for the proper consideration of the research.

Connett and Howard concentrate on new research relating child IQ to fluoride intake but they ignore completely the fact that all the research comparing IQ in fluoridated and unfluoridated areas show absolutely no effect. I have summarised the results for the three papers involve in this table.

Instead, they concentrated on a few extremely weak relationships reported in a few papers. But even here they get this wrong – for example, they say there is “a loss of about 4 IQ points in offspring for a range of 1 mg/liter of fluoride in mother’s urine.” The paper they refer to (Green et al 2019) actually found no statistically significant relationship between child IQ and maternal urinary fluoride for all children considered. The relationship Connett and Howard mention was actually for male children (no relationship for female children or for all children) and was very weak. These sort of weak relationships are commonly found in epidemiological research and are usually meaningless. In this case, Connett and Howard have simply cherry-picked one value and misrepresented it as applying to all children.

Both the Green et al (2019) and Till et al (2020) papers Connett and Howard refer to suffer from selecting a few weak statistically significant relationships and ignoring the larger number of non-significant relationships they found for the data they investigated. Connett and Howard also completely ignored the new studies that don’t fit their claims. For example that of Santa-Marina et al (2019). Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age. which showed an opposite positive relationship of child IQ with maternal urinary fluoride. Similar they ignored the large Swedish study of Aggeborn & Öhman (2020). The Effects of Fluoride in the Drinking Water showing no effect of fluoride on IQ but positive effects on oral health and employment possibilities in later life.

In conclusion, I reiterate that genuine open scientific exchanges do not take place via press release and activist meetings. However, the fact that Connett and Howard have issued an “Open Letter” could be interpreted as inviting others to participate in a proper exchange. I endorse that concept and offer Connett and Howard space for a free and open exchange on the new research at this blog site.

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Anti-fluoride campaigners still rely on irrelevant studies

Despite Paul Connett’s claim that one only has to read four studies, anti-fluoride campaigners waste so much time promoting irrelevant studies to support there claims one could say they end up drowning in their own irrelevance. Image Credit: Ian Mcewan Quotations

Anti-fluoride activists simply can’t help it. They will post on social media citations to anything they think shows that fluoride is harmful – even if the studies are completely irrelevant to community water fluoridation (CWF). This despite Paul Connett, director of the Fluoride Action Network (FAN), claiming “You only have to read four studies…” to come to the conclusion that CWF is bad for your health.

Connett claims that he has it all sewed up with these four studies from areas where CWF is used or fluoride exposure values are similar to that for CWF. So I thought this would mean activists would give up citing studies from areas of endemic fluorosis where fluoride exposure is much larger. But no – here we go again with FAN returning to the reliance on endemic fluorosis studies with the claim:

“NEW STUDY: Each 1.0 mg/L increment in [urinary fluoride] concentration corresponded with an increase in the prevalence of psychosomatic problems.”

The local fluoride Free NZ activist group (FFNZ) simply repeats the claim. Anti-fluoride activists have a consistent habit of simply repeating these sort of claims, together with citation, without bothering to actually check what the cited papers say or how relevant the study really is to their cause. These activists seem to make a hobby of this – one can see their work every day on Twitter and Facebook. If nothing else one has to admire their dedication to the cause, if not there understanding of what they cite.

In this case, the study is not at all relevant to CWF. Here is its citation.

Wang, A., Duan, L., Huang, H., Ma, J., Zhang, Y., & Ma, Q. (2020). Association between fluoride exposure and behavioural outcomes of school-age children: a pilot study in China. International Journal of Environmental Health Research, 00(00), 1–10.

Briefly, it reports results for a comparison of six behavioural scores for 325 resident school-age children (7–13 years old) living in Tongxu County of Henan Province in China with a measure of fluoride exposure  (urinary fluoride using a single morning collected sample). There was no statistically significant relationship with of five of these behavioural scores (conduct problems, learning problems, Impulsive-hyperactive, anxiety or ADHD index) with urinary fluoride but there was with one – Psychosomatic problems.

It’s a very weak relationship – one has only to look at how the data is scattered in the figures in the paper to see this:

Notice that the urinary fluoride concentration (Fluoride in the graphs) cover a range much higher than is typical for areas where CWF is used – usually much less than 2 mg/L. Not surprising, as it is from an area of endemic fluorosis. Also noticeable is that some of the high fluoride value data points are outliers which of course will influence the statistical analysis.

Not all the data is available but extraction of the data from the figure for Psychosomatic Problems enabled me to check the effect of outliers at high urinary fluoride concentrations. When only the data for urinary fluoride concentrations below 3 mg/L are considered there is no statistically significant relationship. This is even more true when only the data for urinary fluoride concentrations below 2.5 mg/L is considered. And these concentrations are still higher than found for children living in areas where CWF is used.

Conclusions

This study is completely irrelevant to CWF. In fact, if only the low urinary fluoride concentrations more relevant to CWF are considered the study shows absolutely no negative effect of fluoride on child behaviour. If anything, the study actually could be used to support CWF.

But this does not stop anti-fluoride campaigners from promoting the study on social media as if it supported their arguments. I guess the promotion of irrelevant work like this is simply a result of the way they mine citations – promoting anything that could appear to indicate problems with fluoride -even when the studies are completely irrelevant. It’s also a result of the thoughtless way citations are used and studies are promoted by people who don’t understand or even bother to read the studies they cite and promote.

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Anti-fluoridation propaganda now relies on only four studies. 5: Don’t censor yourself

The anti-fluoride movement wants to restrict your reading to “just four studies.” They actively ignore or attempt to discredit other relevant studies. Image credit: Censorship in media.

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).

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

Part 4: Anti-fluoridation propaganda now relies on only four studies. 4: Till et al (2020).

Paul Connett, director of the Fluoride Action Network (FAN), 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.

But he 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.

Oh, but what about Santa-marina et al (2019)

In this article, I discuss a study Connett purposely ignored. The whole anti-fluoride activist movement has avoided discussing this study. It’s citation is:

Santa-Marina, L., Jimenez-Zabala, A., Molinuevo, A., Lopez-Espinosa, M., Villanueva, C., Riano, I., … Ibarluzea, J. (2019). Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age. Environmental Epidemiology, 3.

Of course they ignore it, pretending it doesn’t even exist because it doesn’t confirm their bias!

As Table 7 below shows, Santa-marina et al (2019) reported statistically significant POSITIVE relationships of child cognitive measures with drinking water-fluoride. The red triangle indicates the relationship was statistically significant and the bars represent the 95% confidence interval

Table 7: Relationships of cognitive measures with exposure to fluoride for children reported by Santa-marina et al (2019)

I have already commented on the likelihood that this study suffers from many of the same weaknesses as the other studies discussed in this series – the four studies Paul Connett is actively promoting. The large confidence intervals indicate that the reported relationships will explain only a small percentage of the variance in cognitive measurements.

But, the point is this is another study that has as much right to be considered as the ones used by Connett. And there are others. Connett and other anti-fluoride campaigners purposely exclude studies they cannot use to support their anti-fluoride bias. Studies like those of Broadbent et al (2015), Aggeborn & Öhman (2016), Barberio et al (2017) and Perrott (2018).

The important thing is that the results reported in all the four studies promoted by Connett are contradictory. They lack consistency. Different measures of cognitive ability and fluoride exposure are required to find significant relationships. All the reported associations are weak and there are many statically non-significant associations Connett, and the authors themselves, just don’t discuss.

The critical and intelligent reader needs to take these factors into account instead of cherry-picking results which fit their agenda.

One does not make changes to health policy based on such weak evidence.

Taking in each other’s laundry

Tomorrow I will discuss the links between the four papers Connett is promoting to show that they are not independent. These authors also tend to act as journal reviewers for each other’s papers. To a large extent, the researchers involved are taking in each other’s laundry. See Anti-fluoridation propaganda now relies on only four studies. 6: Incestuous relationship of these studies.

See also:

• The anti-fluoride brigade won’t be erecting billboards about this study
• What are the recent fluoride-IQ studies really saying about community water fluoridation?
• Anti-fluoridationists put faith in new “strong” studies to provide evidence missing in draft NTP review

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Anti-fluoridation propaganda now relies on only four studies. 4: Till et al (2020)

Paul Connet, head of the anti-fluoride propaganda group, Fluoride Action Network, claims that the IQ of children bottle-fed in fluoridated areas drops by 9 points. But he misrepresented the research. There is no observable effect.

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).

Part 3: Anti-fluoridation propaganda now relies on only four studies. 3: Riddell 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 fourth study Connett recommends. It’s citation is:

Till, C., Green, R., Flora, D., Hornung, R., Martinez-mier, E. A., Blazer, M., … Lanphear, B. (2020). Fluoride exposure from infant formula and child IQ in a Canadian birth cohort. Environment International, 134(September 2019), 105315.

Till et al (2020)

Finally, according to Connett:

“The fourth* came in 2020, when it was reported that children who were bottle-fed in fluoridated communities in Canada lost up to 9 IQ points compared to those in non-fluoridated communities.”

This claim is just not true as Table 5 below shows. There is no significant difference in IQ (FSIQ) of children, who had been bottle-fed as babies, between fluoridated (mean IQ 106.1) and unfluoridated (mean IQ 106.8) areas. The only difference Till et al (2020) saw between fluoridated and unfluoridated areas was a significant increase of verbal IQ (VIQ – a subset of FSIQ) for breastfed children in fluoridated areas compared with non-fluoridated areas, and a significant decrease in performance IQ (PIQ a subset of FSIQ) for formula-fed babies in fluoridated areas compared with non-fluoridated areas.

Table 5. Influence of fluoridation on the IQ, VIQ and PIQ of children breastfed or formula-fed as babies found by Till et al (2020)(* indicates statistically significant difference)

Connett appears to have not read the Till et al (2020) paper, or misunderstood it. Perhaps his misunderstanding is derived from the relationships of cognitive measurements with drinking water F – although the relationships are not statistically significant for IQ (FSIQ) (see Table 6 below).

Then perhaps he is grasping at the straws offered by separating the IQ measurements into subsets – VIQ and PIQ. There were no significant relationships for VIQ but there are for the relationships of PIQ to drinking water F for both breastfed and formula-fed children. In fact a decrease of almost 8 PIQ points per 0.5 mg/L water fluoride concentration increase (which the authors argue is the increase seen with fluoridation).

Table 6: Relationships of cognitive measures with exposure to fluoride for children breastfed or formula-fed as babies reported by Till et al (2020)

This study has all the hallmarks of a desperate search for significant relations by using other measures of cognitive ability and fluoride exposure when the main relationship (that of FSIQ and CWF) proves not to be statistically significant. This approach, which statisticans are critical of, is common with most of the studies Connett relies on for his current claims.

There is also the problem that the authors in  their abstract, and of course the anti-fluoride activists promoting the paper, basically ignore most of the relationships because they are not statistically significant and report only the significant ones – and even then often incorrectly (as does Connett who uses the term IQ inappropriately).

Connett is wrong. His claim that “bottle-fed in fluoridated communities in Canada lost up to 9 IQ points compared to those in non-fluoridated communities” is just plain wrong. In fact, the mean IQ values for bottle-fed children in fluoridated areas of Canada was 106.1 and in non-fluoridated areas was 106.8 according to this study.

Tomorrow I will discuss other studies Connett purposely ignores and attempts to cover up because he cannot construe them as supporting his anti-fluoride narrative – see Anti-fluoridation propaganda now relies on only four studies. 5: Don’t censor yourself.

See also:

• Beware of scientific paper abstracts – read the full text to avoid being fooled
• Anti-fluoride propagandists appear not to read the articles they promote
• Bottle fed infants: fluoridated water not a problem
• What are the recent fluoride-IQ studies really saying about community water fluoridation?
• Anti-fluoridationists put faith in new “strong” studies to provide evidence missing in draft NTP review

Similar articles

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:

• ADHD and fluoride – wishful thinking supported by statistical manipulation?
• Statistical manipulation to get publishable results
• Anti-fluoridationists put faith in new “strong” studies to provide evidence missing in draft NTP review
• What are the recent fluoride-IQ studies really saying about community water fluoridation?

Similar articles

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:

• Experts complain to funding body about quality of fluoride-IQ research
• Biostatistical problems with the Canadian fluoride/IQ study
• More expert comments on the Canadian fluoride-IQ paper
• Anti-fluoridationists put faith in new “strong” studies to provide evidence missing in draft NTP review
• Fluoridation science and political advocacy – who is fooling who?
• Scientific integrity requires critical investigation – not blind acceptance
• Fluoridation – A new fight against scientific misinformation
• Politics of science – making a silk purse out of a sow’s ear
• If at first you don’t succeed . . . statistical manipulation might help

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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:

• Fluoride, pregnancy and the IQ of offspring
• Maternal urinary fluoride/IQ study – an update
• A conference paper on the maternal prenatal urinary fluoride/child IQ study has problems
• A more convincing take on prenatal maternal dietary effects on child IQ
• What are the recent fluoride-IQ studies really saying about community water fluoridation?
• What do these mother-child studies really say about fluoridation?

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Fluoridation: “debating” the science?

How the anti-fluoride activist envisages their debate challenge – their hero standing up against the might of the health authorities. Image credit: From the Coliseum to the Cage

New Zealand last week saw another “debate challenge” from anti-fluoride activists. But are their regular challenges serious? And do gladiatorial “debates” before partisan audiences have any value in science anyway?

These people often back away when their bluff is called. Their challenges have more to do with political tactics than any elaboration or clarification of the science. They appeal to the macho and combative attitudes of the intended audience.

One thing for sure, such “debates” do not advance scientific knowledge one iota – nor are they meant to.

The anti-fluoride hero is always victorious in the eyes of the partisan and faithful audience. Image credit: The Real Lives of the Gladiators of Rome – The Unfathomable Sport of Life and Death

Three Wise Men – the anti-fluoride activists Paul Connett, Declan Waugh and Vivyian Howard – visited New Zealand last week. Fluoride Free NZ (FFNZ) advertised these activists as “international experts . . .  “sharing the latest research.” Of course, the implications that these activists actually do any original research on fluoridation or what they were sharing was their own research were completely false.

 

This was just another one of those annual visits from Paul Connett (head of the US Fluoride Action Network) and his mates with the aim of misrepresenting and distorting the science so as to promote the political campaigns of the local anti-fluoridation brigade.

Anti-fluoride campaign puts all its eggs in the IQ basket

New Zealanders are rather tired of this sort of activism but the visit does represent an escalation. This year Three Wise Men, a few years back Two Wise men (Paul Connett and  Bill Hirzy) and before that just one wise man (Paul Connett). Is this a sign of increasing desperation as New Zealand moves ever so slowly to handing over decisions on community water fluoridation to District Health Boards? Or is it a sign of increased funding of the Fluoride Action Network and associated activist groups by the “natural”/alternative health industry? After all, it must cost a bit to send three spokespersons around the globe for just two meetings.

One thing I take from this activity is that the anti-fluoride movement has decided to put all its eggs in one basket – the IQ story. They won’t stop blaming fluoridation for all the ills of the world – from obesity to gender confusion. But they are deliberately making a determined effort to bring their IQ story onto centre stage.

The real experts and all the research indicate the main possible negative health effect which must be considered when planning introduction of fluoridation is mild forms of dental fluorosis. In contrast, anti-fluoride activists in the USA and NZ are attempting to present the main health effect that must be considered is a claimed decline in IQ.

The FFNZ advert shows this is the message the Three Wise Men were promoting in New Zealand. But the “latest research” they were “sharing” was not theirs but that of Basash et al., (2016). Or, rather, they were sharing a misrepresentaion and distortion of that research to fit their scarmongering claims.

I won’t repeat my analysis of the Bashash et al., (2016) paper and its misrepresentation here – readers can refer back to my articles:

• Fluoride, pregnancy and the IQ of offspring, 
• Maternal urinary fluoride/IQ study – an update, 
• Maternal urinary fluoride/IQ study – an update, 
• Maternal urinary fluoride/IQ study – an update, 
• Paul Connett’s misrepresentation of maternal F exposure study debunked,
• Mary Byrne’s criticism is misplaced and avoids the real issues, and
• A conference paper on the maternal neonatal urinary fluoride/child IQ study has problems

A draft of my article critiquing the Bashash et al., (2016) paper, “Predictive accuracy of a model for child IQ based on maternal prenatal urinary fluoride concentration.” is also available online.

The predictable debate challenge

No visit by Paul Connett would be complete without a challenge to debate the science with him. He is frustrated with the fact that his audiences are almost completely faithful anti-fluoride activists. The academics, experts and health authorities did not turn up to his meeting at Otago University so he claims “they don’t feel any obligation whatsoever to debate the science” and ”to simply ignore us is unacceptable” (see Anti-fluoride campaigner invites university debate).

Similarly, he blamed others and claimed his anti-fluoride message was being ignored when only three MPs turned up for his meeting at the NZ Parliament Building last February. That was disingenuous as he had been given plenty of time for a presentation to the Health Committee during the consultations on the Fluoridation Bill last year. And MPs are regularly bombarded with huge amounts of propaganda from anti-fluoride activists. Obviously, MPs feel so inundated with such propaganda that they see no need to attend yet another meeting to hear the same old message.

Connett’s challenges to “debate the science” in front of a partisan audience have more to do with political propaganda and enthusing activists than with science. He knows scientific knowledge does not progress by holding gladiatorial circuses. It progresses by long, careful and detailed research, publication and peer review.

Neither of these Three Wise Men has performed any original research on community water fluoridation but they can still make their input via the peer review process – which include post-publication peer review via critiques of published papers.

To be fair, Connett and other members of the Fluoride Action network have occasionally presented such critiques. Two examples come to mind – the studies of  McLaren et al., (2016) and of Broadbent et al., (2015). These were critiqued in responses published in these same journals by a number of opponents of fluoridation. The original authors responded in the same journals. Arguments and extra data were presented in the responses and the science is better off for those critiques.

But science does not gain one iota from Connett’s attacks on the New Zealander Broadbent and other researchers in the media or in his meetings with the faithful. Such attacks and macho comments, often bordering on ad hominem, only discredit the attacker. They are not the way to discuss science and yet Paul Connett and his supporters challenge genuine scientists to participate in such “debates’ which are nothing more than testostorone-laden slanging matches.

A farcical example of a debate challenge

This time around I got personally involved because I called the bluff of activists making yet another debate challenge. It came out of an online discussion where I was attempting to correct some mistaken claims made by anti-fluoride activists. Here is the challenge:

Screenshot of my invite – just as well a have this as this Facebook page subsequently deleted the invitation and all comments I had made. I am officially a nonperson there.

A game of chicken followed where I attempted to get Fluoride Free NZ (FFNZ) and Paul Connett to formally stand behind the challenge. Chicken because I recognised it was a game. I had a scientific exchange (“debate”) with Paul four years ago – I think it was useful and I believe this is how good faith scientific discussions should take place (see Connett & Perrott, 2014: The Fluoride Debate for the full exchange). But Paul had made clear to me some time ago that he wanted no further contact with me.

Sure enough, FFNZ very quickly retreated from the possibility they had offered of a one on one debate. I emailed FFNZ:

“I think a one on one exchange would be best and as Paul and I have similar expertise he would be the logical discussion partner.”

Their response:

“No we will only agree to two on two.”

Paul confirmed that he would not debate one on one with me. I accepted a two on two “debate” but pointed out it was their responsibility, not mine, to organise the speakers. If they were not prepared to do that I suggested a two on one “debate” (especially as being the only speaker on one side this would give me extra presentation time) but made clear that I would effectively ignore Vyvyan Howard because our expertise did not cross over. (Vivyan agree with me that as he is a pathologist “you are correct that a direct discussion between us would be unbalanced.”)

I also made clear I would not tolerate any attempt to use that format to argue that I was isolated and could not find anyone else in New Zealand to support my arguments (an implication Paul made in our email exchange, and, of course, a claim being parroted by his supporters on social media).

Paul then formally withdrew. A pity as I love Wellington and was looking forward to a visit at someone else’s cost.

So a farce, But wait. there is more. The Facebook page, Rethink Fluoride, deleted their invitation to this “debate.” They then followed by deleting all my comments on their posts. Rather ironic as I had a few days before congratulated them by allowing open comments, and in particular allowing scientific comments – something all other anti-fluoride Facebook pages refused to allow.

Conclusion

Debate challenges by anti-fluoride activists are never genuine. They do not wish to discuss the science – they are simply using the challenges to enthuse their true-believing supporters. It is a form of attack on genuine researchers and health experts.

There is a time and place for good faith scientific exchange – post-publication peer review, for example, can give a genuine avenue for any real critiques to appear and be considered. Testosterone-laden gladiatorial debates before partisan audiences do not.

Anti-fluoride activists are disingenuously using these “debate challenges” to imply that experts and researchers have no confidence in their science and are afraid. It’s simply a macho tactic which often descends into ad hominem attacks.

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Anti-fluoridationist Paul Connett misrepresents NZ data

Slide 110 from Paul Connett’s presentation prepared for his planned meeting at Parliament Buildings last February

Here is another post in my series critiquing a PowerPoint presentation of Paul Connett – a leading US anti-fluoridation activist.

Paul prepared this for a meeting in New Zealand Parliament buildings last February. Although only three MPs turned up his presentation is important as it summarises almost all the arguments used by anti-fluoridation activists.

Connett claims NZ data shows fluoridation ineffective

Connett argues the evidence community water fluoridation (CWF) is effective in reducing tooth decay is weak. He covers this in slides 96-110 but in this post I will deal only with the New Zealand evidence he uses (slides 108-110).  Paul’s presentation can be downloaded for those wishing to look at it in detail – see Prof Paul Connett Power Point Presentation to Parliament 22nd Feb 2018.

The total New Zealand evidence Connett presents for this is a graphic obtained from his NZ offsiders, Fluoride Free NZ (FFNZ):

We know how unreliable FFNZ is as a source and the data is obviously cherry-picked. But what is the truth? What do the NZ School Dental statistics really say about the oral health of children in NZ?

I have covered this before – FFNZ misrepresentation of the MoH data is an annual event occurring each time the Ministry of Health adds its annual summary of the data to their web pages.

For a change, here is a breakdown and discussion of the 2016 data prepared by Environmental Health Indicators NZ in association with Massey University:

“Children in fluoridated areas generally have better oral health”

“Children living in communities with fluoridated drinking-water generally had better oral health than children living in non-fluoridated communities.

In 2016, around 60 percent of 5-year-olds were caries-free in their primary teeth. Rates were similar in fluoridated communities (60 percent) and non-fluoridated communities (60 percent) (Figure 1).

More Māori and Pacific Island 5-year-olds were caries-free in fluoridated communities than in non-fluoridated communities in 2016. The largest difference can be seen for Māori children.

5-year-olds had on average 1.8 decayed, missing or filled primary teeth in 2016. Children living in fluoridated communities had less decayed, missing or filled teeth than children living in non-fluoridated communities (Figure 2).

This difference is particular large for Māori children. 5-year old Māori children had on average 2.5 decayed, missing or filled teeth in fluoridated communities compared to 3.3 decayed, missing or filled teeth in non-fluoridated communities in 2016.”

I am unable to embed the Environmental Health Indicators NZ graphs, but they are essentially the same I presented in my article Anti-fluoridationists misrepresent New Zealand dental data – an annual event so I reproduce that section of the article below:

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What does the new data really say?

Let’s look at a summary of the data – for 5-year-olds and year 8 children – and for the different ethnic groups listed – Māori, Pacific Island and “other”(mainly Pakeha and Asian).  You can download the spreadsheets contain the data from the MoH web page – Age 5 and Year 8 oral health data from the Community Oral Health Service. We will look at the % of these children that a free from caries as well as the mean decayed, missing and filled teeth (dmft and DMFT) for each group.

5-year-olds

Notice the FFNZ cherry picking? Yes, the “Total” figures show very little difference but if they had dared look at different ethnic groups their argument would not have looked so great. Fluoridation appears to be associated with an improvement of dental health from about 6% (for “Other”) to 23% (for Māori)

Year 8 children

You can see why  FFNZ chose the 5-year-olds instead of year 8 children. Even the misleading data for the “Total” group suggests an almost 20% improvement of dental health in fluoridated areas.  Fluoridation appears to be associated with an improvement of dental health from about 18% (for “Other”) to 30% (for Māori).

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What’s the problem with the 2009 Oral Health Survey?

Anti-fluoride activists love to hate this survey because it concluded:

“Overall, children and adults living in fluoridated areas had significantly lower lifetime experience of dental decay (ie, lower dmft/DMFT) than those in non-fluoridated areas. There was a very low overall prevalence of moderate fluorosis (about 2%; no severe fluorosis was found), and no significant difference in the prevalence of moderate fluorosis (or any of the milder.

“These findings support international evidence that water fluoridation has oral health benefits for both adults and children. In addition, these findings should provide reassurance that moderate fluorosis is very rare in New Zealand, and that the prevalence of any level of fluorosis was not significantly different for people living in fluoridated and non-fluoridated areas.”

Yes, it covers only the period up to 2008 and it would be good to get more recent high-quality data from a similar study.

But Connett’s accusation of “cherry-picked data” is simply wrong – and dishonest. In fact, scientific principles were used to obtain a representative sample for the survey – recognising that oral health is strongly influenced by ethnic, regional and fluoridation differences.

The methods used are explained in 22 pages of the report –  MoH. (2010). Our Oral Health Key findings of the 2009 New Zealand Oral Health Survey. 

In contrast, the annual School Dental Data is simply a record of overall findings. There is no attempt to standardise diagnostic and reporting methods to the standard of the Oral Health Survey or scientific studies.

But, of course, it provides a lot of data which can be cherry-picked to support a specific argument or confirm a bias. FFNSZ and Paul Connett have ignored all the known ethnic, social and regional differences in their cherry-picking. Consequently, their reported “findings” do not have credibility.

Conclusion

I think it is somewhat disrespectful of Paul Connett to include such a shonky bit of misrepresentation in a presentation prepared for members of parliament. It is also disrespectful in that he relies on his scientific qualifications, his Ph. D. to give “respectability” to a scientific argument which is so easily shown to be false.

Surely our members of parliament deserve something better than this.

Although, even with members of parliament, I guess the old adage “reader (or listener) beware” applies. Sensible MPs will not accept such assurances at face value and will seek out adive=ce on such matters from their officials and experts.

I guess we should feel pretty confident that most of our MPs are sensible in this repect. The fact they did not turn up to a meeting to hear someone well-known for misrepresenting the science is telling – and this despite the fact that anti-fluoride activists were exerting strong pressure on MPs to attend.

Politicians have experienced, and learned from, excessive lobbying, pressuring and untruthful submissions precisely because of their targeting by anti-science activist groups like FFNZ. They know this is why local councils wanted the central government to take over fluoridation decisions.

I suspect our parliamentary politicians are a little more mature than our local body politicians and now  treat such organised campaigns like water off a duck’s back.

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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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