Category Archives: Health and Medicine

Cochrane fluoridation review. III: Misleading section on dental fluorosis

The Cochrane review did not look at the effect of community water fluoridation (CWF) on dental fluorosis. It simply reviewed data on the prevalence of dental fluorosis at different fluoride drinking water concentrations – up to 7.6 ppm which is well outside the optimum concentration used for CWF.

This is strange for a review specifically about CWF. Strictly speaking, as it stands  this section should have been a separate review on dental fluorosis itself. However, this review did calculate a probable dental fluorosis prevalence at 0.7 ppm (the usual concentration used in CWF) which is misleading because it can be misinterpreted as due completely to CWF when it isn’t. And, of course, anti-fluoridation propagandists have cherry-picked and misinterpreted this.

The forms of dental fluorosis. Questionable, Very Mild and Mild forms are usually considered positively whereas the Moderate and Severe forms are considered negatively. See Water fluoridation and dental fluorosis – debunking some myths

Confusing language

I think is was a serious mistake for the reviewers to include this section in a review on CWF as this can imply the calculated prevalences quoted are caused by CWF. They aren’t.

Strictly, their calculations were reported correctly in the abstract:

“There is a significant association between dental fluorosis (of aesthetic concern or all levels of dental fluorosis) and fluoride level.”

And also in the Plain Language Summary:

“The researchers calculated that, in areas with a fluoride level of 0.7 ppm in the  water, approximately 12% of the people evaluated had fluorosis that could cause concern about their appearance.”

However, in their blog post on the review (see Little contemporary evidence to evaluate effectiveness of fluoride in the water”) they inappropriately claim:

“There is an association between fluoridated water and dental fluorosis.”

Quite wrong – the association was with fluoride concentration (and most studies were of natural fluoride levels) – not with CWF.

They also use the term “water fluoridation” incorrectly in their comment on other possible harm from fluoride:

“Five studies that reported on dental fluorosis also presented data on the association of water fluoridation with skeletal fluorosis (Chen 1993; Jolly 1971; Wang 2012), bone fracture (Alarcon-Herrera 2001), and skeletal maturity (Wenzel 1982), in participants between the ages of six and over 66 years. Four of the studies included a total of 596,410 participants (Alarcon-Herrera 2001; Chen 1993; Wang 2012; Wenzel 1982), and fluoride concentration in all four studies ranged from less than 0.2 ppm to 14 ppm.”

Their use of the term “water fluoridation” to cover natural fluoride concentrations up to 14 ppm is irresponsible and misleading.

What the review did on dental fluorosis

It simply attempted to find a quantitative relationship between “fluoride level” (concentrations of naturally derived fluoride in drinking water) and dental fluorosis prevalence. It did this for all grades of dental fluorosis from “questionable” to “severe” (see figure above for illustrations fo the different grades). It also did this for “dental fluorosis of aesthetic concern” (which they arbitrarily defined as the mild, moderate and severe forms – they acknowledge inclusion of “mild” forms here is debatable). The figure below gives an idea of the data they were working with.

DF-Cochrane

Using this data they produced tables of the probability of any forms of dental fluorosis, and of dental fluorosis of aesthetic concern at fluoride concentrations from 0.1 to 4 ppm. In the figures below I have converted their probability values to a calculated prevalence of dental fluorosis at concentrations up to 0.7 ppm.

DF-1

As you can see from these figures the calculated prevalence of dental fluorosis at “fluoride exposures” less than the 0.7 ppm is only slightly less that at the 0.7 ppm used in CWF. So  it is very misleading to interpret the review’s statement below as indicating anything about CWF:

“The researchers calculated that, in areas with a fluoride level of 0.7 ppm in the  water, approximately 12% of the people evaluated had fluorosis that could cause concern about their appearance.”

Why should the review have considered differences between fluoridated and unfluoridated areas for its conclusions about tooth decay – but ignore the differences between fluoridated and unfluoridated areas in its consideration of dental fluorosis?

Estimating possible effect of CWF on dental fluorosis

In Misrepresentation of the new Cochrane fluoridation review I estimated what the possible effects of CWF is from the calculated probabilities in the Cochrane review. I am surprised the reviewers do not do this themselves as their review was meant to be about CWF and not natural fluoride levels in general.

At 0.7 ppm (the usual concentration for CWF), the calculated prevalence of all forms of dental fluorosis is 40%. But to calculate the prevalence due to CWF we must subtract the prevalence for non-fluoridated water. So dental fluorosis due to CWF would be 40% – 33% = 7 % of people  (using the review’s concentration for non-fluoridated water of 0.4 ppm) or 40% – 30% = 10 % of people (using a more realistic concentration of 0.2 ppm).

Similarly, if we consider only those forms of dental fluorosis the review considers of “aesthetic concern,”  then calculated prevalence due to CWF amounts to only 12% – 10% = 2% of people (using the reviews definition of non-fluoridated) or 12% – 9% = 3%  of people using a more realistic concentration of 0.2 ppm for non-fluoridated.

Defining “dental fluorosis of aesthetic concern”

The milder forms of dental fluorosis are usually judged positive from the point of view of the quality of life. That is why the review also considered dental fluorosis of aesthetic concern – which they define as the severe, moderate and mild forms of dental fluorosis. But, their inclusion of mild forms here is questionable and they acknowledge that:

“Within the context of this review dental fluorosis is referred to as an ’adverse effect’. However, it should be acknowledged that moderate fluorosis may be considered an ’unwanted effect’ rather than an adverse effect. In addition, mild fluorosis may not even be considered an unwanted effect.”

It is not surprising (considering the data in the figures above) that surveys  usually find no changes in the severe and medium forms of dental fluorosis (usually considered of “aesthetic concern”) due to CWF.

I think the Cochrane reviewers were irresponsible to quote calculations which did not include the difference between fluoridated and non-fluoridated areas. This has enabled anti-fluoridation propagandists to use the authority of the Cochrane name to imply, as they often do, that CWF causes a dental fluorosis prevalence of 40%!

Conclusions

The review section on dental fluorosis should not be read as information on the effects of CWF – although the presented data can be used to calculate possible effects. These calculations confirm findings of published surveys that CWF has no effect of the forms of dental fluorosis of aesthetic concern.

However, the conclusions presented in this section of the review are open to misrepresentation and distortion just as they are with the reviews comments on “bias” and poor quality of research (see Cochrane fluoridation review. II: “Biased” and poor quality research) and their selection criteria (see Cochrane fluoridation review. I: Most research ignored). Misrepresentation and distortion of the review are already happening. Anti-fluoridation activists are heavily promoting this review, together with their distortions and misrepresentations, opportunistically using  the Cochrane name to give “authority.”

Sensible readers will not rely on such misrepresentation or brief media reports. Nor will they rely on the Abstract or Plain Language Summary – which have problems. They will read the whole document – critically and intelligently. This is the only way to find out what the true content of this review is.

See also:

Misrepresentation of the new Cochrane fluoridation review
Cochrane fluoridation review. I: Most research ignored
Cochrane fluoridation review. II: “Biased” and poor quality research

Similar articles

Cochrane fluoridation review. II: “Biased” and poor quality research?

Avoid-despair-about-biases

Here again, the language used in the Cochrane review (Water fluoridation for the prevention of dental caries) is very misleading. Especially when cherry-picked and taken out of context. The word “bias” used in the review does not have the meaning an uninformed reader might think.

It does not mean motivated experimental design or selection of data to “prove” a predetermined outcome. Rather it has specific meaning related to common (and usually innocent) problems encountered clinical drug trials. These problems also occur in real-life epidemiological studies and trials of the sort used for evaluating social health measures like community water fluoridation (CWF) but the lack of control in such studies means they are harder to combat.. The Cochrane ideal of randomised double-blinded trials is just not realistic in these situations. As the American Academy of Pediatrics comments in their article on the Cochrane review:

“it would be a logistical nightmare to try creating a public water system that pumps fluoridated water to the first house on the block, delivers non-fluoridated water to the following two houses and then provides fluoridated water to the 4th and final house on that block.”

The review describes the types of “biases”  considered:

“Assessment of risk of bias in included studies
. . . . . The domains assessed for each included study included: sampling, confounding, blinding of outcome assessment, completeness of outcome data, risk of selective outcome reporting and risk of other potential sources of bias. . . . . .  We had identified the following factors as important confounders for the primary and secondary outcomes: sugar consumption/dietary habits, SES, ethnicity and the use of other fluoride sources.”

Unfortunately, all these sorts of “biases” are inevitable to some extent in the real world. Researchers do not always have the budget to include consideration of all confounders, or the degree of control required. There are inevitable gaps in data when families move or withdraw children from schools. Yet it is real-world studies, not idealised laboratory experiments, that give the data and other evidence reviewers and decision-makers must consider. Humans can’t be treated like experimental rats.

What “biases” did the review find

As far as “caries outcome” is concerned the review reports a  “high risk of bias overall,” but this “bias may occur in either direction.” This indicates there is not a motivated selection of data or experimental design to produce a predetermined result as that would show up as a systematic bias.

The major cause of “bias” arose from lack of control of the confounding issues of “sugar consumption/dietary habits, SES, ethnicity and the use of other fluoride
sources.” These are of course important factors which could influence results. In the real world it is difficult to control of variations in dietary intake, although socioeconomic status (SES) and ethnicity can be included in statistical analyses of data. My impression is that this is usually done in more recent studies (which the Cochrane review team had excluded from their review – see Cochrane fluoridation review. I: Most research ignored).

Most studies were at low risk of “bias” from sampling methods but on “detection bias” the reviewers report:

The majority of the studies did not blind outcome assessors. This is perhaps unsurprising when considering the efforts that may be required to blind assessors for this type of study.”

The qualification here surely indicates the inadequacy of the Cochrane criteria for using word’s like “bias” which are more fitted to clinical drug trials than evaluation of social health policies.

Most studies did not suffer from “incomplete outcome data” where some data is not measured, but some showed the “bias” of “selective reporting” where data sets reported were incomplete. Interestingly the reviewers report one study where:

“the baseline fluoridation status of the children was determined by the location of the school they attended, which may not have taken into account any children attending schools in fluoridated areas who resided outside those areas.”

This must be a common problem researchers face when they do such real-world epidemiological studies.

Inappropriate criteria used to judge quality of research

Given the nature of evaluating a social health policy like community water fluoridation (CWF) I think the criteria used by the review team to judge the quality fo available research was quite wrong. Their criteria were more fitted to judging clinical drug trials and not social health policies. They acknowledge this in their discussion section “Quality of evidence:”

“However, there has been much debate around the appropriateness of GRADE when applied to public health interventions, 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.”

And:

“we accept that the terminology of ’low quality’ for evidence may appear too judgmental. We acknowledge that studies on water fluoridation, as for many public health interventions, are complex to undertake and that researchers are often constrained in their study design by practical considerations. For many public health interventions, the GRADE framework will always result in a rating of low or very low quality. Decision makers need to recognise that for some areas of research, the quality of the evidence will never be ’high’ and that, as for any intervention, the recommendation for its use depends not just upon the quality of the evidence but also on factors such as acceptability and cost-effectiveness (Burford 2012).” My emphasis.

These are important qualifications which, however, did not make it into the review’s Abstract or Plain Language Summary – and certainly not into media reporting. I think the review team was irresponsible to omit such qualifications from their summaries – and many people might suggest they were irresponsible to use such inappropriate criteria for their judgements in the first place.

The scientific literature is not perfect

I keep stressing that readers should always approach scientific reports and papers critically and intelligently. The problems identified by the Cochrane reviewers are inevitable and should always be taken into account by sensible readers. Simple reliance on the abstract of a paper or report often gives a misleading interpretation of the findings. Unfortunately, even unmotivated reporters tend not to read reports in full. Motivated activists will purposely resort to cherry-picking and distortion.

Decision-makers don’t necessarily need perfect scientific papers as they have to consider far more than the abstract conclusion of a scientific paper. There are the democratically expressed views of the electorate and the real situation where social health policies are put into effect. While the Cochrane reviewers expressed “limited confidence” in the size of the effect of CWF on tooth decay. However, policy-makers are more interested in the fact that there is a positive effect on oral health than the possible “theoretical” size of that effect.After all, policy-makers have to also consider the possible role of confounding effects like alternative sources of fluoride, the quality of dental health in the area, socioeconomic status of the population and school health programmes when making decisions about local CWF programmes.

Conclusions

1: The Cochrane reviewers’ use of terms like “bias” and judgment of studies as being of poor quality is inappropriate for evaluation of a social health policy. According to them:

“The main areas of concern were confounding and lack of blind outcome assessment. The evidence was additionally downgraded for indirectness due to the fact that about 71% of the caries studies that evaluated the initiation of water fluoridation were conducted prior to 1975.”

Yet they qualify this by acknowledging such judgement of “bias” and poor quality is inappropriate for a social health policy. And it was their own criteria for rejecting studies that produced a paucity of more recent studies (see Cochrane fluoridation review. I: Most research ignored).

2: These qualifications were not mentioned in the review’s Abstract or Plain Language Summary. I believe this was irresponsible of the authors. especially  given the controversial nature of the subject and the well-understood fact that media reporters rarely read beyond abstracts and summaries.

Such inappropriate and unqualified language provides a godsend to anti-fluoridation propagandists who are already cherry-picking and misrepresenting the review’s main findings.

3: We can remove the inappropriate and judgmental language and still accept that many of the problems identified in the review are inevitable for studies of social health measures. The review actually acknowledges that.

However, the sensible reader of scientific literature is surely aware of these problems. Any research paper must be assessed intelligently and critically – especially regarding the treatment of confounding factors. This is a point I have continually stressed in my posts on this subject.

In my experience, it has been the confirmation bias of anti-fluoride activists which leads them to ignoring such advice. One need only consider their use of studies related to IQ and fluoride in areas of endemic fluorosis, or their recent promotion of poor quality papers claiming a relationship between CWF and Attention-Deficit Hyperactivity Disorder (see ADHD linked to elevation not fluoridation) or hypothyroidism (see Paper claiming water fluoridation linked to hypothyroidism slammed by experts). 

I urge readers to follow this same advice with the Cochrane review. Don’t accept media reports or a limited reading of its Abstract or Plain Language Summary.

Read the whole review – intelligently and sceptically.
See also:

Cochrane fluoridation review. I: Most research ignored
Cochrane fluoridation review. III: Misleading section on dental fluorosis

Similar articles

Cochrane fluoridation review. I: Most research ignored

With the publication of the new Cochrane Fluoridation Review (Water fluoridation for the prevention of dental caries) we have, once again,  both fluoridation supporters and opponents claiming it as evidence for their contradictory positions. They surely both cannot be right.

The reality is that any such review is going to have its own complexities and limitations which allow committed believers on either side to confirm their biases. Unfortunately, this confirmation bias is promoted by inadequate reporting relying on “sound bites” from the executive summary.  Real understanding of the review and its results requires more thoughtful analysis, a reading of the full review and not just media reports and a bit of thinking about its limitations.

The post is the first of three articles looking a bit more deeply at the Cochrane fluoridation review. Here I discuss the strict criteria used by the review team for selecting the studies they considered,  the limitations this has caused for their findings and the misinterpretation of the review results this has produced.

97% of fluoridation research ignored

This seems amazing – why ignore so much of the research? We can understand the need to filter poor research or poorly reported claims. But 97%?

Yet, that is what the review reports – and summarises in their Figure 1:

Cochrane-1

The high exclusion rate was caused by the review teams decision to only consider studies which conformed to strict criteria:

“For caries data, we included only prospective studies with a concurrent control, comparing at least two populations, one receiving fluoridated water and the other non-fluoridated water, with at least two points in time evaluated. Groups had to be comparable in terms of fluoridated water at baseline. For studies assessing the initiation of water fluoridation the groups had to be from nonfluoridated areas at baseline, with one group subsequently having fluoride added to the water. For studies assessing the cessation of water fluoridation, groups had to be from fluoridated areas at baseline, with one group subsequently having fluoride removed from the water.
For the purposes of this review, water with a fluoride concentration of 0.4 parts per million (ppm) or less (arbitrary cut-off defined a priori) was classified as non-fluoridated.”

This criteria requiring measurements at several time periods and the inclusion of data from before the commencement of fluoridation was probably the main reason for excluding studies. In the review’s Table “Characteristics of excluded studies” the most often mentioned reason was “Evaluated caries in a single time point cross-sectional study.”

OK, you can sort of see the logic behind these strict criteria:

“The cross-sectional studies, whilst able to provide information on whether water fluoridation is associated with a reduction in disparities, are not able to address the question of whether water fluoridation results in a reduction in disparities in caries levels.”

But this inevitably resulted on consideration of only a small part of the available research:

“155 studies (162 publications) met the inclusion criteria for the review. However, only 107 studies (15 caries studies; 92 studies reporting data on either all fluorosis severities or fluorosis of aesthetic concern) presented sufficient data for inclusion in the quantitative syntheses.”

Inability to comment does not mean no effect

Exclusion of so many important studies meant the review was unable to come to any conclusions about important aspects like the effect of community water fluoridation (CWF) on socioeconomic difference in tooth decay,  the effect of stopping CWF programmes on later tooth decay and the effectiveness of CWF in reducing adult tooth decay.   Yet, in the review’s discussion they did make note of research which did draw some conclusions in these areas – research they refused to consider. (And it is rather ironic that one of the review’s authors, Helen V. Worthington, has co-authored several papers which conclude that CWF does reduce socioeconomic differences in dental health).

Of course, anti-fluoride propagandists have chosen to misrepresent the review – reporting its inability to draw conclusion on these questions as evidence that CWF does not influence socioeconomic differences, is not effective for adults and tooth decay does not increase when CWF is stopped!  (See Misrepresentation of the new Cochrane fluoridation review). Clear misrepresentation – but helped by the combination of exclusion of most research and the  vague language used in the review summary.

And you do sort of wonder at ignoring so much evidence when considering issues related to community health. Was Cochrane throwing away the baby with the bathwater?

Confirmation fluoridation is effective

The strict exclusion criteria enabled the review team to winnow studies down to a small number which could be analysed quantitatively. They were able to confirm from analysis of 9 studies that CWF:

“resulted in a 35% reduction in decayed, missing or filled baby teeth, and 26% reduction in decayed, missing and filled permanent teeth.”

But the strict exclusion criteria, specifically rejection of cross-sectional studies, is still a fly in the ointment. Recent studies of situations where fluoridation has been in operation for a long time did not fall within the strict selection criteria because pre-fluoridation data would not realistically be available in most cases. The review consequently did not consider properly the recent evidence – 71% of the research considered occurred before 1975!

The review, therefore, raised the issue of how applicable their findings are to the current situation in developed countries because of improved dental care and use of fluoridated toothpaste. A reasonable proviso which could have been discussed properly using the research they had excluded. But again a proviso which enables misrepresentation by anti-fluoride propagandists who imply that their findings are irrelevant to our current situation.

The review authors acknowledge that exclusion of such data presents a problem for their conclusions:

“In the past 20 years, the majority of research evaluating the effectiveness of water fluoridation for the prevention of dental caries has been undertaken using cross-sectional studies with concurrent control, with improved statistical handling of confounding factors (Rugg-Gunn 2012). We acknowledge that there may be concerns regarding the exclusion of these studies from the current review. A previous review of these cross-sectional studies has shown a smaller measured effect in studies post-1990 than was seen in earlier studies, although the effect remains significant. It is suggested that this reduction in size of effect may be due to the diffusion effect (Rugg-Gunn 2012); this is likely to only occur in areas where a high proportion of the population already receive fluoridated water.”

Of course, the review team was correct to raise the question of the possible reduced efficacy of CWF in modern developed societies. But doesn’t that suggest they should not have used such restrictive criteria in selecting studies to consider? And isn’t it irresponsible to leave the impression that CWF is no longer effective when they excluded the studies which could have provided better answers?

Conclusion

The Cochrane fluoridation review suffers from the fact that only 3% of available studies were considered. The restrictive selection criteria enable quantitative estimates showing  CWF is effective for children but excluded the possibility of answering questions related to the effectiveness for adults, the ability of CWF to reduce socioeconomic differences in oral health,  the effect of stopping fluoridation on later tooth decay and whether improved availability of dental treatments and use of fluoridated toothpaste has reduced the efficacy of CWF in modern developed societies.

The language of the review report itself encourages misinterpretation – and this is even worse in their blog post about the review – Little contemporary evidence to evaluate effectiveness of fluoride in the water.” Here they repeatedly refer to lack of evidence but only explain this is due to their exclusion of such evidence in a few places. What is the uninformed reader, who does not bother to read the full document, make of points in the summary such as:

  • “There is insufficient evidence to determine the effect of water fluoridation on disparities in caries levels across socio-economic status
  • There is insufficient evidence to determine the effect of water fluoridation on caries levels in adults
  • There is insufficient evidence to determine the effect of removing water fluoridation programmes from areas where they already exist”

Finally, anti-fluoride propagandists are motivated enough to misrepresent the findings in any fluoridation review or other documents. The very restricted selection criteria used by the Cochrane review and the language of its summary and news reporting of the review is a bit of a godsend to such propagandists.

Expect to see a lot of cherry-picked quotes from the Cochrane review. Twisted to turn the lack of evidence of effects (due to the exclusion of studies) into evidence for no effect.


My next article on the Cochrane review deals with its discussion of “bias” and poor quality in the studies it considered. See Cochrane fluoridation review. II: “Biased” and poor quality research.

See also:
Misrepresentation of the new Cochrane fluoridation review
Cochrane fluoridation review. II: “Biased” and poor quality research
Cochrane fluoridation review. III: Misleading section on dental fluorosis

Similar articles

Misrepresentation of the new Cochrane fluoridation review

A new fluoridation review was published this week – Water fluoridation for the prevention of dental caries from the Cochrane Oral Health Group. It’s main message is:

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

So, of course, we now have to put up with anti-fluoridation propagandists as they scurry to misrepresent the review’s findings.

I have written before about how Stan Litras, a New Zealand anti-fluoride propagandist,  indulges in cherry-picking, misinformation and outright distortion  of the science (see for example  Cherry-picking and misinformation in Stan Litras’s anti-fluoride article). Well, he has been at it again – this time putting his talents for misrepresentation to use on the new Cochrane Review.

Stan has issued a press release, using his astroturf vanity project (Fluoridation Network for Dentists) – Gold Standard Fluoride Review Contradicts NZ Advice. He claims that the new review’s:

“findings are completely at odds with last year’s Royal Society review, which our government refers to as justification for promoting fluoridation.”

In fact just not true!

Let’s compare his claims with what the Cochrane review actually reported.

Adult benefits

Stan claims the review “finds the science does not support claims that water fluoridation is of any benefit to adults.” Of course, Stan is implying that the review investigated the situation for adults and found no benefit.

Completely wrong.

The review says:

“No studies met the review’s inclusion criteria that investigated the effectiveness of water fluoridation for preventing tooth decay in adults, rather than children.”

And later:

“Only one of these studies examined the effect of water fluoridation on adults (Pot 1974); the reported outcome for this study was the percentage of participants with dentures. There are no data to determine the effect of water fluoridation on caries levels in adults.”

The Cochrane reviewers just did not have any suitable studies fitting their strict criteria for analysis so they could draw no conclusion on this specific question. However, in the review’s discussion they do mention a comprehensive systematic review (Griffin et al., 2007) which attributed a 34.6% reduction of tooth decay in adults to community water fluoridation. The corresponding figure for studies published after 1970 was 27.2%

Social inequalities

Stan implies the review found that fluoridation did not “reduce social” inequalities.

Completely wrong again.

The review was not able to draw any conclusion related to social inequalities because it just did not have that information. it says:

“There was insufficient information available to find out whether the introduction of a water fluoridation programme changed existing differences in tooth decay across socioeconomic groups.”

The review team did find 3 studies reporting effects of water fluoridation on disparities in caries across social class. However, there were problems with all 3 studies meaning the data was not suitable for further analysis and this  prevented them drawing any conclusions.

Benefits when toothpaste used

Stan claims, or at least strongly implies,  the review indicates that community water fluoridation does not “provide additional benefits over and above topically applied fluoride (such as in toothpaste).”

Again, completely wrong.

The review specifically says:

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

It goes on to say:

“However, since 1975 the use of toothpastes with fluoride and other preventive measures such as fluoride varnish have become widespread in many
communities around the world. The applicability of the results to current lifestyles is unclear.”

So, it raises the possibility that the current efficacy of community water fluoridation in industrialised countries could be lower. However, they could not draw a conclusion on this because only 30% of the included studies took place after 1975.

The review team did attempt to look at factors such as sources of fluoride “(potential confounders of relevance to this review include sugar consumption/dietary habits, SES, ethnicity and the use of other fluoride sources)” but found this not to be possible:

“However, due to the small number of studies and lack of clarity in the reporting within the caries studies, we did not undertake these sub-group analyses.”

Stopping fluoridation

Stan claims (or at least strongly implies) the review shows claims “that tooth decay increases in communities when fluoridation is stopped” are incorrect.

Wrong again.

The review says:

“There was insufficient information available to understand the effect of stopping water fluoridation programmes on tooth decay.”

And:

“No studies that met the inclusion criteria reported on change in dmft or proportion of caries-free children (deciduous/permanent dentition) following the cessation of water fluoridation.”

The only study the review discussed was that of Maupome et al., (2001). This paper is often quoted by anti-fluoridation propagandists but those authors themselves commented on the difficulty of drawing conclusions from their data:

“Our results suggest a complicated pattern of disease following cessation of fluoridation. Multiple sources of fluoride besides water fluoridation have made it more difficult to detect changes in the epidemiological profile of a population with generally low caries experience, and living in an affluent setting with widely accessible dental services.”

Dental fluorosis

Stan claims the review “found that 40% of children in fluoridated areas have dental fluorosis.” However, the review does not compare the prevalence of dental fluorosis in fluoridated areas and unfluoridated areas. It simply draws conclusions about the likely prevalence of dental fluorosis at different fluoride intakes. This lack of comparison is unfortunate, although the omission may be due to the lack of suitable studies that survived their strict criteria.

So Stan’s claim is misleading because, without considering dental fluorosis in the non-fluoridated, areas it is not possible to attribute any responsibility to community water fluoridation. He has simply taken the reported estimate of dental fluorosis for a fluoride intake of 0.7 ppm (the concentration in fluoridated drinking water in NZ) without taking into account the prevalence of dental fluorosis in unfluoridated areas. Very misleading!

The review does, however, calculate estimates of dental fluorosis for different drinking water concentrations and we can draw some proper conclusions from these.

Total dental fluorosis. The review defines this as all the forms of dental fluorosis according to the Dean Index – from questionable to serious. (See Water fluoridation and dental fluorosis – debunking some myths for a discussion of the different forms of dental fluorosis). The graph below shows the reviews findings for the effect of fluoride exposure (drinking water fluoride concentration) on any dental fluorosis.

DF-2True, at 0.7 ppm (the usual concentration for CWF, this shows an estimated prevalence of 40%. But we can calculate the increase due to CWF by subtracting the prevalence for non-fluoridated water. So dental fluorosis due to CWF would be 40% – 33% = 7 % of people  (using the review’s concentration for non-fluoridated water of 0.4 ppm) or 40% – 30% = 10 % of people (using a more realistic concentration of 0.2 ppm).

So Stan is quite wrong to imply CWF causes a total dental fluorosis in 40% of people – it is only 10% or less. However, even that figure is misleading.

Most dental fluorosis is not of aesthetic concern – in fact, the milder forms are often viewed positively from the point of view of the quality of life. So the review also considers dental fluorosis of aesthetic concern – which they define as the serious, moderate and mild forms of dental fluorosis (their inclusion of mild forms here is questionable). The graph below illustrates their findings for these forms of dental fluorosis.
DF-1

So, if we consider only those forms of dental fluorosis the review considers of aesthetic concern  then calculated prevalence due to CWF amount to only 12% – 10% = 2% of people (using the reviews definition of non-fluoridated) or 12% – 9% = 3%  of people using a more realistic concentration of 0.2 ppm for non-fluoridated.

This is a huge difference to the 40% claimed by Stan.

The review acknowledges that their inclusion of mild forms of dental fluorosis in their definition of dental fluorosis of aesthetic concern is questionable, saying “mild fluorosis may not even be considered an unwanted effect.” Most studies do not consider the mild forms undesirable. It is likely that most of the increase in “dental fluorosis of aesthetic concern” arising from community water fluoridation occurs in the mild forms.  So my suggestion of a 2 or 3% increase in “dental fluorosis of aesthetic concern” will be an overestimation.

It is unsurprising, then, that some cross-sectional studies do not detect any increase in undesirable dental fluorosis attributed to community water fluoridation. The figure below illustrates an example reported in the New Zealand in the 2009 New Zealand Oral health Survey (see Our Oral Health).

Conclusions

Once again this anti-fluoridation propagandist has been caught misrepresenting the scientific literature on this issue. And his misleading press release is being touted as gospel truth by anti-fluoridation groups in NZ and the USA.

It is pathetic such people have to resort to misrepresentation in this way. Surely it is a sign of desperation to use statements that no conclusions were possible on specific details (adult benefits, social inequalities, influence of toothpaste, and what happens when fluoridation is stopped) because no studies fitted the selection criteria as “evidence” that there is no effect.

References

Griffin SO, Regnier E, Griffin PM, Huntley V. (2007). Effectiveness
of fluoride in preventing caries in adults. Journal of Dental
Research 2007;86(5):410–5.

Iheozor-Ejiofor, Z., Worthington, HV., Walsh, T., O’Malley, L., Clarkson, JE., Macey, R., Alam, R., Tugwell, P., Welch, V., Glenny, A. (2015). Water fluoridation for the prevention of dental caries (Review). The Cochrane Library, (6).

Maupomé, G., Clark, D. C., Levy, S. M., & Berkowitz, J. (2001). Patterns of dental caries following the cessation of water fluoridation. Community Dentistry and Oral Epidemiology, 29(1), 37–47.

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Misrepresenting the York fluoride review

I have noticed a few “Letters to the Editor” and social media comments lately misrepresenting the “York review” on fluoridation so looked into the background of some of these claims.

The “York review” (McDonagh, et al., 2000) is one of the earliest authoritative and comprehensive reviews of the scientific literature related to fluoridation and resulted from a request by the UK Department of Health for:

“a systematic review of the evidence for the safety and effectiveness of water fluoridation based on the currently available evidence from population-based studies.”

As a systematic review it is a valuable resource for decision-makers so this review – together with later and more comprehensive reviews – is usually accepted as one of the most reliable sources of evidence for local bodies considering fluoridation  issues. However, this very authority leads to its misrepresentation by activists.

We are used to activists misrepresenting the evidence contained in such reviews, but I want to comment on the way anti-fluoride propagandists attempt to present the review authors as supporting anti-fluoride positions. In particular, the way they use quotes from anti-fluoride people who have some tenuous connection to the review. These quotes are presented as authoritative, consistent with the reviews findings and with the implications the people quoted were authors  or members of the York Fluoride Systematic Review Team – when they were not.

Review Team & Advisory Panel

The York Fluoride Systematic Review Team were the authors of the report. These authors and affiliation are:

  • Jos Kleijnen, NHS Centre for Reviews and Dissemination, York, UK
  • Marian McDonagh, NHS Centre for Reviews and Dissemination, York, UK
  • Kate Misso, NHS Centre for Reviews and Dissemination, York, UK
  • Penny Whiting, NHS Centre for Reviews and Dissemination, York, UK
  • Paul Wilson, NHS Centre for Reviews and Dissemination, York, UK
  • Ivor Chestnutt, Dental Public Health Unit, Cardiff, Wales, UK
  • Jan Cooper, Dental School, University of Wales College of Medicine, Cardiff, Wales, UK
  • Elizabeth Treasure, Dental School, University of Wales College of
    Medicine, Cardiff, Wales, UK

However, an advisory board was also appointed. This included representatives from “both sides of the fluoridation debate” as well as including neutral people. According to Richards et al., (2002):

“Although the advisory panel and review team agreed the results of the review, agreement was not reached about the conclusions or, more importantly, the implications of the review.”

Hardly surprising given the differing views on the issue. This article adds:

“Parties on each side of the controversy were reluctant to abandon their previous positions and endorse the review result whole-heartedly.”

The Systematic Review Advisory Panel members were:

  • Chair: Trevor Sheldon, York Health Policy Group, University of York, York, UK
  • Earl Baldwin of Bewdley, House of Lords, London, UK
  • Iain Chalmers, UK Cochrane Centre, Oxford, UK
  • Sheila Gibson, Glasgow Homeopathic Hospital, Glasgow, Scotland, UK
  • Sarah Gorin, Help for Health Trust, Winchester, UK
  • Mike Lennon, Chairman of the British Fluoridation Society, Department of Clinical Dental Sciences, University of
    Liverpool School of Dentistry, Liverpool, UK
  • Peter Mansfield, Director of Templegarth Trust, Louth, UK
  • John Murray, Dean of Dentistry, University of Newcastle, Newcastle
    upon Tyne, UK
  • Jerry Read, Department of Health, London, UK
  • Derek Richards, Centre for Evidence-Based Dentistry, Oxford, UK
  • George Davey Smith, Department of Social Medicine, University of Bristol, Bristol, UK
  • Pamela Taylor, Water UK, London, UK

Readers will see the mixed nature of this group so won’t be surprised there were fixed views which prevented their endorsement of the review findings and conclusions.

Opportunist quoting of minority views

Anti-fluoridation propagandists have made much of quotes from 2 advisory panel members – people who were not authors of the review and could not represent the review itself.

york_chairman_quote

Out of context quote from anti-fluoride site No Fluoride.

Professor Trevor Sheldon has made a statement emphasising the provisional nature of the reviews findings, commenting on the poor quality of much of the research of health aspects and stressing the limitations of the review and need for further work. His statement recognised  that fluoridation is effective at reducing tooth decay The quality of research on health effects has also improved in recent years. However, anti-fluoride people use the quote in attempts to undermine research showing the efficacy of fluoridation and the lack of harmful effects. It is more correct to say, as Newton et al., (2015) did recently:

“In general, the literature suggesting adverse health effects of fluoridation is characterised by poor-quality studies that do not adequately adjust for potential confounding variables.”

Please note, Sheldon was a member of the Advisory panel and not an author of the review.

Another quote which has been rehashed recently by activists is from Advisory panel member Peter Mansfield:

“No physician in his right senses would prescribe for a person he has never met, whose medical history he does not know, a substance which is intended to create bodily change, with the advice, ‘Take as much as you like, but you will take it for the rest of your life because some children suffer from tooth decay.’”

Users of the quote imply he was an author of the review report – for example “Mansfield took part in the University of York (in York, England) review of public water fluoridation in 2000.” He did not. He was merely a member of the Advisory Panel representing the views of anti-fluoridationists. Have a search for him on the internet (he is the Director of Templegarth Trust, Louth, UK) to get a picture of his alternative health views.

Conclusions

In  their article about the York Review Richards et al., (2002) indicate that this early review identified problems with review processes and existing knowledge which future work would overcome:

“Future research can be more efficient and sharply focused as a result of open reviews of this kind. A consensus on future research priorities was one result of this review. The eventual findings of future work are more likely to be debated rationally and achieve wide consensus than if the review had not taken place.”

Anti-fluoride propagandists are simply taking advantage of those early issues, and dishonestly implying that they out-of-context quotes they use were made by authors of the York review when they weren’t.

References

McDonagh, M. S., Whiting, P. F., Wilson, P. M., Sutton, a J., Chestnutt, I., Cooper, J., … Kleijnen, J. (2000). Systematic review of water fluoridation. BMJ (Clinical Research Ed.), 321(7265), 855–9.

McDonagh, M., Whiting, P., Bradley, M., Cooper, J., Sutton, A., & Chestnutt, I. (2000). A Systematic Review of Public Water Fluoridation. 258 pp. Full report.

Newton, J. N., Young, N., Verne, J., & Morris, J. (2015). Water fluoridation and hypothyroidism: results of this study need much more cautious interpretation. Journal of Epidemiology and Community Health, 69(7), 617–8. http://doi.org/10.1136/jech-2015-205917

Richards, D., Mansfield, P., & Kleijnen, J. (2002). Systematic review in scientific controversy: the example of water fluoridation, an open access reviewEvidence-Based Dentistry, 3, 32–34.

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Fluoridation: Misrepresenting the “saliva theory”

I sometimes wonder if anti-fluoridation propagandists are trying to extend their “freedom of choice” argument to the scientific facts themselves. Perhaps this is how they justify to themselves their frequent cherry-picking and misrepresentation of research.

A current example is Fluoride Free NZ’s (FFNZ) misrepresentation of the mode of action of fluoride in protecting existing teeth in Saliva Theory Critique. Nothing new here – it’s a rehash of an older article of theirs which I critiqued 2 years ago in Fluoridation – topical confusion. But it still contains the same misinformation.

Selective quoting

Again FFNZ  misrepresents the advice of the Center For Disease Control (CDC) by selective quoting. Here is the relevant section of the document (CDC, 2001. Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States). The FFNZ article quoted only the 2 sentences in red!:

“Saliva is a major carrier of topical fluoride. The concentration of fluoride in ductal saliva, as it is secreted from salivary glands, is low — approximately 0.016 parts per million (ppm) in areas where drinking water is fluoridated and 0.006 ppm in nonfluoridated areas (27 ). This concentration of fluoride is not likely to affect cariogenic activity. However, drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride dental products can raise the concentration of fluoride in saliva present in the mouth 100-to 1,000-fold. The concentration returns to previous levels within 1–2 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization (28 ).”

Their misrepresentation claims (in their words) “The CDC acknowledges that fluoridated water has no cariostatic effect” because of the low concentration of fluoride in secreted saliva. However, the full quote shows that the CDC advised that “saliva is a major carrier of topical fluoride” and that “drinking fluoridated water” is one way of increasing saliva fluoride concentration sufficiently so that “saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization.”

FFNZ purposely confuses the issue by ignoring the direct transfer of fluoride from water and food to saliva, dental plaque and biological tissue in the oral cavity. These act as reservoirs which can top-up the fluoride concentration at the tooth surface and help prevent demineralisation (responsible for tooth decay in acid conditions) and remineralisation.

“Topical” role of fluoride at tooth surface

This figure from the CDC document cited above provides a simple illustration of the way that fluoride, from fluoridated water, helps prevent tooth decay with existing teeth.

Even this shows that the mechanism is far from simple as the process is influenced by the concentration of phosphate and calcium in saliva, as well as fluoride. I would add that organic material, such as proteins, will also influence the mechanism. Then there is a process of transfer of fluoride, and other ions, to saliva from reservoirs like plaque, the tongue and other biological tissues which are known to store fluoride. For example, Vogel (2011) states:

“Current models for increasing the anti-caries effects of fluoride (F) agents emphasize the importance of maintaining a cariostatic concentration of F in oral fluids. The concentration of F in oral fluids is maintained by the release of this ion from bioavailable reservoirs on the teeth, oral mucosa and – most importantly, because of its association with the caries process – dental plaque.
Oral F reservoirs appear to be of two types: (1) mineral reservoirs, in particular calcium fluoride or phosphate contaminated ‘calcium-fluoride-like’ deposits; (2) biological reservoirs, in particular (with regard to dental plaque) F held to bacteria or bacterial fragments via calcium-fluoride bonds.”

Confusing the concentration issue

The FFNZ article attempts to confuse the issue again by citing 5 studies they claim “show that fluoridated water is too low in fluoride to provide any topical benefit.” But, of course, a more honest approach to the scientific literature is to consider all studies (not just the ones confirming one’s bias) and check relevant experimental details.

The studies they cite were not aimed at determining a minimum concentration for the surface reaction at the tooth surface. They were laboratory studies, using bovine dental material, usually not taking into account the role of other ions like calcium and phosphate. Several were studying fluoride/sucrose solutions.

In contrast, the review by Buzalaf (2011), Mechanisms of Action of Fluoride for
Caries Control  found:

“very low fluoride concentrations (sub- ppm range) in solution are already able to substantially inhibit acid dissolution of tooth minerals [23, 27].”

This was confirmed in the review of Ten Cate & Featherstone (1991). They cited studies showing inhibition of demineralisation at fluoride concentrations as low as 0.2 ppm and 0.025 ppm (Margolis et al., 1986). They also mention the higher fluoride concentrations required when ions like calcium and phosphate are omitted.

Demonstrated inhibition of demineralisation at such low fluoride concentration when the other relevant minerals are present does raise the possibility that fluoride in secreted saliva may still play a role, despite the view expressed in the CDC document cited above. However, let’s stress here, one does not have to take sides on that particular debate to recognise that the saliva fluoride concentration resulting from transfer from food and fluoridated water in the oral cavity is high enough to play a protective role against tooth decay. Bruun & Thylstrup (1984), who reported the low concentrations cited by the CDC, concluded that:

“direct contact of the oral cavity with F in the drinking water is the most likely source of the elevated whole saliva fluoride and that the increased availability of fluoride in the oral fluids has an important relationship to the reduced caries progression observed in fluoridated areas.”

So, again, the real world is not as simple as suggested by those who seek only to confirm their biases.

References

Bruun, C., & Thylstrup, A. (1984). Fluoride in Whole Saliva and Dental Caries Experience in Areas with High or Low Concentrations of Fluoride in the Drinking Water. Caries Research, 18(5), 450–456.

Buzalaf M.A.R., · Pessan J.P., · Honório H.M., & ten Cate J.M, (2011). Mechanisms of Action of Fluoride for Caries Control. In Buzalaf MAR (ed): Fluoride and the Oral Environment. Monogr Oral Sci. Basel, Karger, 2011, vol 22, pp 97–114

Center for Disease Control, 2001. Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States).

Margolis, H. C., Moreno, E. C., & Murphy, B. J. (1986). Effect of Low Levels of Fluoride in Solution on Enamel Demineralization in vitro. Journal of Dental Research, 65(1), 23–29.

Ten Cate, J. M.; Featherstone, J. D. B. (1991). Mechanistic Aspects of the Interactions Between Fluoride and Dental Enamel. Critical Reviews in Oral Biology and Medicine, 2(2), :283–296.

Vogel, G. L., (2011). Oral Fluoride Reservoirs and the Prevention of
Dental Caries. In Buzalaf MAR (ed): Fluoride and the Oral Environment.
Monogr Oral Sci. Basel, Karger, 2011, vol 22, pp 146–157

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Fluoridation and horses – another myth

Readers following the fluoridation issue have probably come across claims fluoridated water can poison horses. This is just another case of scaremongering by anti-fluoride propagandists – but what is it based on?

The claims go back to Cathy Justus, a horse owner from Pagosa Springs, Colorado. She lost eight horses and four dogs and blames it on their consumption of fluoridated water – which she describes as a “virulent cumulative toxin.” She also claims to “have the sad distinction of owning the first horses to ever be diagnosed with “chronic fluoride poisoning” from artificially fluoridated municipal water.”

Of course, her claim to owning the first horses diagnosed with poisoning by fluoridated water sets off alarm bells straight away. What happened to all the other horses which have consumed fluoridated water? And how could her diagnosis be so different?

What to the experts say?

According to Associate Professor Cynthia Gaskill, toxicology section chief at the Veterinary Diagnostic Laboratory at the University of Kentucky (see Expert discusses fluoridated water and horses in Horsetalk.co.nz):

“A casual internet search of this topic can uncover alarming reports purporting fluoride poisoning in horses from fluoridated municipal water.

“These reports typically are published in non-peer reviewed sources and are missing important information necessary to confirm the diagnosis, to rule out exposure to other fluoride sources, and to eliminate other potential causes.

“A careful review of the peer-reviewed literature in reputable scientific journals showed no published reports documenting fluoride poisoning in horses due to ingestion of fluoridated public water.”

An expert with the Sonoma County Horse Council, Ted S Stashak, concluded in his article The Effects of Artificial Fluoridation of Water (AFW) on Horses:

“Evidence to date indicates that F concentrations allowable in US public water systems are well tolerated by horses and do not cause fluorosis. Supporting this, is a fact that many horses nationwide drink AFW as their major source of water and fluorosis is a  very rarely reported condition.”

Why is Cathy Justus so convinced?

It doesn’t take much background reading to see Cathy Justus may be suffering a bit of confirmation bias. In a long letter to the Baltimore Post Express in 2012 she describes her own beliefs and the symptoms of her animals (see Poisoned Horses: Fluoride debate continues). Have a read of at least some of it and you will get the idea.

Cathy is a dyed in the wool anti-fluoride propagandist. Her letter is full of all the “arguments” and relies on the usual anti-fluoride bibles like The case Against Fluoride, The Fluoride Deception, etc. The letter’s tone is typical of someone with these extreme views. So it comes as no surprise to find she is also Fluoride Action Network’s (FAN) National Spokesperson against Fluoride Poisoning in Animals.

She is convinced that her  animals’ problems were caused by fluoridated water (as are all the health problems humans currently have) and, in her own mind, that this is not observed by other horse owners just indicates their ignorance and brainwashing.

But wait, there’s more

Cath Justus searched around until she found a veterinary expert who agreed with her bias – in this case, Dr. Lennart Krook, Professor Emeritus, Cornell University. So this whole incident got into the “peer-reviewed” (?), “scientific” (?) literature. To be exact, 2 papers and an editorial in the journal Fluoride – which she describes as the “fluoride bible.” You can check them yourself:

  • Krook, L. P., & Justus, C. (2006). Fluoride poisoning of horses from artificially fluoridated drinking water. Fluoride, 39(March), 3–10.
  • Justus, C., & Krook, L. P. (2006). Allergy in horses from artificially fluoridated water. Fluoride, 39(June), 89–94.
  • Sauerheber, R. (2013). Racehorse breakdowns and artificially fluoridated water in Los Angeles. Fluoride, 46(December), 182–191.

As you might expect from that journal these papers are of poor quality – and, in particular, they present no evidence for the firm beliefs that fluoridated water was the cause of the problems described. Or their equally strong assertions that there is no possibility that feed contamination or other usual causes were absent. As Stashak says, these papers:

“are missing important information necessary to confirm that AFW alone was the cause for the signs of chronic fluorosis in these horses.”

A strongly held, motivated, anecdotal opinion is not evidence and would not be accepted as such by any self-respecting scientific journal. For the life of me, I cannot see how anyone could claim such papers are “peer-reviewed.”

All three authors are organisationally connected with the anti-fluoridation movement. Jutsus through here FAN position.  Krook through his membership of the anti-fluoride group Second Look‘s Advisory Board and his membership of the Editorial Board of Fluoride since 1990 and Associate Editor since 2003 (as described in his 2010 obituary of Fluoride).  Saueheber is part of James Deal’s (Attorney Deal) anti-fluoride Fluoride Class Action group.

Conclusion

This is just another example of the way anti-fluoride propagandists attempt to convert their biases into “facts.” They have produced multiple articles in the friendly “natural”/alternative health media, and even a video, to support this particular claim. Their tame “scientific” journal, Fluoride, has been dragged in to give academic credibility – and it is unlikely any reputable journal could have been used for this, given the lack of evidence.

In a rather pathetic footnote, Richard D Sauerheber, author of the editorial referred to, gives his institutional affiliation as University of California, San Diego, La Jolla, CA 92037, USA. He also did this in his one other published paper referred to in my post Calcium fluoride and the “soft” water anti-fluoridation myth. In our discussion there he admitted he does not work at that institution, although he did study there many years ago. This is the first time I have come across an author using their university of study as an institutional affiliation in this way. It is deceptive and aimed purely at attempting to claim credibility to himself and any article where he does this. I would be interested to know what officials at that university think of this practice.

 

Fake weight-loss study example of wider problem

bad science

Click on image to enlarge

Another interesting article in the Conversation – Trolling our confirmation bias: one bite and we’re easily sucked in by Will Grant. It underlines a point  I have often made – that the sensible reader must approach the scientific literature intelligently and critically.
Grant describes a “scientific” prank which fooled many news outlets who reported the “scientific finding”, and, therefore, many readers.

“Last week science journalist John Bohannon revealed that the whole study was an elaborate prank, a piece of terrible science he and documentary film makers Peter Onneken and Diana Löbl – with general practitioner Gunter Frank and financial analyst Alex Droste-Haars – had set up to reveal the corruption at the heart of the “diet research-media complex”.”

The first trick

This was more than just planting a fictitious “science” story:

“To begin the study they recruited a tiny sample of 15 people willing to go on a diet for three weeks. They divided the sample into three groups: one followed a low carbohydrate diet; another followed that diet but also got a 42 gram bar of chocolate every day; and finally the control group were asked to make no changes to their regular diet.

Throughout the experiment the researchers measured the participants in 18 different ways, including their weight, cholesterol, sodium, blood protein levels, their sleep quality and their general well being.”

So – that was the first trick. “Measuring such a tiny sample in so many ways means you’re almost bound to find something vaguely reportable.” As Bohannon explained:

“Think of the measurements as lottery tickets. Each one has a small chance of paying off in the form of a “significant” result that we can spin a story around and sell to the media. The more tickets you buy, the more likely you are to win. We didn’t know exactly what would pan out — the headline could have been that chocolate improves sleep or lowers blood pressure — but we knew our chances of getting at least one “statistically significant” result were pretty good.”

Publication

Now to get credibility they needed to publish in a scientific journal:

“But again, Bohannon chose the path that led away from truth, picking a journal from his extensive list of open access academic journals (more on this below). Although the journal, (International Archives of Medicine), looks somewhat like a real academic journal, there was no peer review. It was accepted within 24 hours, and published two weeks later.”

Now for the publicity

Bohannon then whipped up a press release to bait the media :

“The key, Bohannon stated, was to “exploit journalists’ incredible laziness” – to write the press release so that reporters had the story laid out on a plate for them, as it were. As he later wrote, he “felt a queazy mixture of pride and disgust as our lure zinged out into the world”. And a great many swallowed it whole.

Headlines around the world screamed Has the world gone coco? Eating chocolate can help you LOSE weight, Need a ‘sweeter’ way to lose weight? Eat chocolates! and, perhaps more boringly, Study: Chocolate helps weight loss.”

We should be concerned at the way the news media and reporters handle such matters:

“None did the due diligence — such as looking at the journal, looking for details about the number of study participants, or even looking for the institute Bohannon claimed to work for (which exists only as a website) — that was necessary to find out if the study was legitimate.”

This criticism, unfortunately, applies to almost anything in our news media. it really is a matter of “reader beware.”

Grant summarises the process that leads to such devious “science’ stories in the media:

  • we’ve got researchers around the world who have taken to heart the dictum that the quantity of research outputs is more important than the quality
  • we’ve got journal publishers at the high quality end that care about media impact more than facts
  • we’ve got journal publishers at the no-quality end who exploit the desperation of researchers by offering the semblance of publication for a modest sum
  • we’ve got media outlets pushing their journalists ever harder to fill our eyeballs with clickbaity and sharebaity content, regardless of truth
  • and we’ve got us: simple creatures prone to click, read and share the things that appeal to our already existing biases and baser selves.

 Problem wider than the diet industry

Bohannon gives his prank as an example of a “diet research-media complex . . that’s almost rotten to the core.” I agree readers should be far more sceptical of such diet-related science stories. But the problem is far wider than that industry. I think is particularly relevant to any area where people are ideologically motivated, or their feelings of inadequacy or danger, can be manipulated.

Take, for example, the anti-fluoride movement. I have given many examples on this blog of science being misrepresented, or poor quality science being published and promoted by this movement. There are examples of anti-fluoride scientists doing poor quality research – often relying on “statistical fairy tales. Examples of using shonky journals to get poor quality work published. But also examples of such work making its way through inadequate journal peer-review processes.

These anti-fluoride researchers, and their allied activist groups, commonly use press releases to promote their shonky findings.  Social media like Facebook and Twitter are roped in to spread the message even more widely.

There is also a link with big business interests – in this case an active anti-fluoride “natural” health business-research-media complex.

So readers beware – there are people, businesses and ideological interests out there attempting to fool you. And they are not averse to using shonky or false science, biased press releases and lazy journalists to do this.

 See also: A rough guide to spotting bad science from Compound Interest (Click to enlarge).

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Calcium fluoride and the “soft” water anti-fluoridation myth

hogwash1Concepts of “natural” and “unnatural” or “artificial” ( or even “industrial”) fluoride often come up in the fluoride debates. Some fluoridation opponents claim “natural” calcium fluoride is quite safe, maybe even necessary for the body, but “artificial fluorides” are toxic. For example, a recent commenter stated:

“I understand that the addition of calcium fluoride to our water supply could be a safe alternative as its use in the small quantities needed would not be harmful. It is not very reactive, but has the desired effect on teeth.”

One of the arguments used is that the presence of calcium is what makes calcium fluoride (CaF2) good, whereas its supposed absence with “artificial” or “industrial” fluorides makes these bad. Anti-fluoride campaigner Eron Brokovich put it this way in here recent “open letter” to the US Institute of Medicine / National Academy of Sciences:

“The 2013 study of chemist Dr. Richard Sauerheber examined the differences between aturally occurring Calcium Fluoride and the highly toxic Industrial Fluoride used in water supplies. Dr. Sauerheber confirmed that the calcium in CaF(sic) makes the fluoride much less absorbable by the human body and therefore less toxic when ingested in that form, whereas the industrial fluoride is . . .  highly absorbable . . .”

Sauerheber’s paper (which Brockovich relies on as “evidence”) is a meandering and naive anti-fluoridation rant, published in a shonky journal. But anti-fluoridation propagandists treat “peer-reviewed friendly papers like this as pure gold, so they do tend to rely on them. But don’t take my word for this – here is the citation for anyone wanting to check out the paper

Sauerheber, R. (2013). Physiologic conditions affect toxicity of ingested industrial fluoride. Journal of Environmental and Public Health, 2013,

Sauerheber’s (and therefore Brockovich’s) argument is that calcium in CaF2 reduces assimilation of fluoride into the body and, therefore, renders it non-toxic. He says, for example:

“Natural mineral fluorides are not absorbed well when ingested because of the natural metal cations that accompany fluoride. Having no biologic similarity at all with natural fluoride  minerals, industrial manufactured fluoride compounds have cations that replaced those in the natural mineral. . . . . Free fluoride ion in some water supplies as a contaminant is naturally present
from natural fluoride minerals that exhibit low solubility. The equilibrium double-arrow natural partial dissolution of the insoluble solid into some waters is given by:

CaF2(s) ↔ Ca2+(aq) + 2F(aq).

Industrial fluorides stripped of natural mineral cations lack antidote calcium and are fully assimilated from artificially treated water with insufficient calcium.”

And:

“Fluoride minerals are not neurotoxins, because fluoride is not absorbed from ingested minerals. Free fluoride ion in drinking water can be so classified, but industrial fluoride sources are assimilated more readily than fluoride from hard water or from natural calcium fluoride.”

So, “natural” fluoride, CaF2, is good because the calcium present stops it getting into your blood stream. But “industrial” fluoride is bad because it has no calcium present to inhibit assimilation.

True, the most commonly used fluoridating chemicals are fluorosilicic acid, sodium fluosilicate or sodium fluoride. These do not contain calcium. But wait a minute! These chemicals are drastically diluted in the water supply which already contains calcium from natural sources, and sometimes from water treatment chemicals like lime.

Sauerheber sort of hints at this in his reference to “hard water.” Water “hardness” refers to its mineral content and is usually expressed as the calcium, or calcium carbonate, concentration. It is a common measure of water quality so data is readily available from water treatment plants. In the graph below I compare the calcium concentration from some typical New Zealand water treatment plants with the calcium concentration of a saturated CaF2 solution and the theoretical calcium concentration of “pure” water fluoridated with CaF2 to produce a fluoride concentration of 0.75 ppm (mg/L).

hardness

Notes:

  • The majority of NZ waters are considered “soft” with a hardness of 30 ppm (expressed as Ca) or less. I have used this for the NZ maximum.
  • The Te Marua, Wainuiomata and Waterloo treatment plants are in the Wellington region. The Hamilton treatment plant is in Hamilton city.
  • CaF2 is only slightly soluble so a saturated solution  contains approximately 7.5 ppm Ca and 7.5 ppm F, depending on pH and temperature.

Conclusion

All this talk about “natural” CaF2 somehow being “safe” because it contains calcium, whereas the fluoridation chemicals used do not contain calcium, is hogwash There is plenty of calcium even in “soft” drinking water – far more calcium that could be derived from “natural” CaF2 if it were used to produce the optimum concntration fo fluoride used in community water fluoridation.

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Connett & Hirzy do a shonky risk assesment for fluoride

Paul Connett, executive director of the Fluoridation Action Network (FAN), told me, during our fluoride debate, that he was writing a scientific paper defining a lower safety limit for fluoride than currently accepted. Nothing has been published yet – although a recent FAN newsletter did refer to a risk assessment paper by him and Bill Hirzy currently under review. I look forward to reading this paper, but I am not holding my breath as neither author has an impressive publication record.

Connett described his risk assessment for fluoride in the debate (see Fluoride debate: Paul Connett’s Closing statement) and he and Hirzy have also made comments on this lately. They are rejecting the current risk assessment, based on the incidence of severe dental fluorosis, and using the incidence of IQ deficits instead. To this end, they are heavily promoting the work of Choi et al., (2012) and Xiang et al., (2003) (which reported IQ deficits in areas where fluorosis is endemic). They are also attempting to rubbish published research (such as Broadbent et al., 2014) which show no significant IQ deficits at fluoride concentrations used in community water fluoridation.

Connett and Hirzy have also organised campaigns to congressional representatives in their effort to force a downward revision of the Environmental Protection Agency’s (EPA) standards for fluoridation.

Connett’s approach is a desk study – these guys are not going  to dirty their hands by doing their own research to get useful data. They are taking a value which they claim represent the lowest concentration of fluoride in drinking water below which no IQ deficit was found. They then apply “safety factors” to effectively conclude the only safe concentration is zero (see Scientist says EPA safe water fluoride levels must be zero)!

I will be a bit surprised if they manage to squeeze their paper though a decent review process because their approach is shonky. Look at the way they use the data from Xiang et al., (2003). (I have used the presentations by Connett and Hirzy at last February’s Sydney anti-fluoride conference as sources here). As I pointed out in Connett fiddles the data on fluoride, this data actually does not show a strong relationship between IQ and fluoride. The figure (from Xiang et al., 2003) shows the relationship between IQ and urinary fluoride and, in this case, the fluoride explains only about 3% of the variance in IQ.

Despite being statistically significant (p=0.003) this is certainly not evidence for a causative relationship. Clearly other, unconsidered, factors contribute to the variance and if these were considered the relationship with fluoride may be non-significant.

(Readers may notice the figure uses data for urinary not drinking water fluoride. Unfortunately, Xiang did not give a similar figure for fluoride concentration in drinking water. I have contacted him requesting the similar data for drinking water but so far have not had a meaningful response. Xiang did report drinking water fluoride is well correlated with urine fluoride so the above figure probably gives a good idea of the variability in drinking water fluoride as well).

Connett and Hirzy effectively ignore the high variability in the data and rely on a trick to get this  second graph. By splitting the concentration range into groups and taking the mean IQ for each group they make the situation look a lot more respectable. Who would guess from this trick that fluoride only explained about 3% of the IQ variance?

Connett illustrates his next step with this slide.

Sydney-Feb-21-key-step

He then claims that IQ deficits occur at a fluoride concentration of 1.26 ppm – he appears to have simply subtracted the value of one standard deviation from the mean of the lowest concentration group associated with a significantly different mean IQ to that of Xiang’s “control” group – Xinhaui village. That is strange because surely the first figure indicates  that low IQ values occur even for children with very low urinary fluoride, and most probably drinking water fluoride.

Connett then uses a safety factor of 10 (“to account for the wide range of sensitivity expected for any toxic substance in a large population”). Of course, this produces a maximum “safe” concentration of 0.13 ppm – which rules out all fluoridated water – and most natural water sources!

Sydney Feb 21 B Australia,  2015Connett goes on to promise his offsider, Bill Hirzy, will elaborate on the method they issued. Hirzy’s presentation did mention fluoride intake from other sources besides water. He then presents his conclusion on what the “safe daily dose” is fluoride – but no explanation of why! All the preceding slides in his presentation where self-justifying descriptions of his qualifications, employment history and how great his organisation, FAN, is.

IQ-Risk-Assessment-02.26.15

Conclusions

Connett and Hirzy are claiming IQ deficits are more important than dental fluorosis for setting of maximum fluoridation levels in drinking water. They are campaigning to get this accepted by legislators and the EPA.

Connett has been promising publication in a scientific journal for several years and recently implied that a paper is under review. If their publication efforts are successful a more critical assessment of their approach will be possible.

Available information indicates Connett and Hirzy have no original data but are relying on data from a study of children in an area of endemic fluorosis in China. They are refusing to accept published information from areas where community water fluoridation exists.

Their analysis also appears to rely on a tricky processing of the data to obscure the fact that fluoride probably only explains about 3% of the variance in IQ measured by the Chinese researchers! Legislators and policy makers would be foolish indeed to make changes to fluoridation standards on the basis of such data and poor analysis.

I could, of course, be wrong so eagerly await the Connett & Hirzy (2016?) paper.

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