Category Archives: SciBlogs

Premature births a factor in cognitive deficits observed in areas of endemic fluorosis?

premature

Could the increased incidence of premature births explain cognitive deficits observed in areas of endemic fluorosis? Image credit: New Kids-Center.

Anti-fluoridation activists are soon likely to be promoting a new paper reporting a study which found a relationship between maternal (in utero) exposure to fluoride and cognitive development delay in infants. Of course, they will be unlikely to mention the study occurred in an area of endemic fluorosis where drinking water fluoride concentrations are much higher than used in community water fluoridation (CWF). They are also unlikely to mention the possible role of premature births in cognitive development delay observed in the study.

The paper is:

Valdez Jiménez, L., López Guzmán, O. D., Cervantes Flores, M., Costilla-Salazar, R., Calderón Hernández, J., Alcaraz Contreras, Y., & Rocha-Amador, D. O. (2017). In utero exposure to fluoride and cognitive development delay in infants . Neurotoxicology

Valdez Jiménez et al., (2017) studied 65 mother-baby pairs in an area of endemic fluorosis in Mexico. The mothers had high levels of fluoride in their urine and this was negatively associated with cognitive functions (Mental Development Index – MDI) in the infants.

The concentration of fluoride in the tap water consumed by the mothers ranged from 0.5 to 12.5 mg/l, with about 90% of water samples containing fluoride above the World Health recommended maximum of 1.5 mg/l.

Fluoride in the mothers’ urine was also high – with the mean concentration for all the mothers of 1.9 mg/l  for the 1st trimester, 2.0 mg/l for the 2nd and 2.7 mg/l for the 3rd trimester. Urinary fluoride concentrations as high as 8.2 mg/l were found. This compares with a mean value of F in urine of 0.65 mg/L) for pregnant women residents in areas with low levels of F in drinking water (0.4 to 0.8 mg/l – similar to that recommended in community water fluoridation).

The MDI test used evaluates psychological processes such as attention, memory, sensory processing, exploration and manipulation, and concept formation. This was negatively associated with maternal urine fluoride concentrations – the association explaining about 24% of the variance.

Room of other influences

This data suggests that other confounding factors which weren’t measured could also contribute to the variation of the MDI results, and if such confounders were included in the statistical analysis the contribution from urinary fluoride may be much less than 24%.

However, I am interested in the data for premature births that were, unfortunately, not included in the statistical analysis. The paper reports “33.8% of children were born premature i.e. between weeks 28-36 and had a birth weight lower than 2.5 kg.” This is high for Mexico – as they say:

“The World Health Organization (WHO) in Mexico reported a rate of 7.3 cases per 100 births; compared with 33.8% of cases per 100 births that we observed in our study. We have 26.5% more cases than expected.”

According to their discussion, other researchers have also reported higher premature births in areas of endemic fluorosis, compared with non-endemic areas.

Is premature birth a mechanism explaining cognitive deficits?

This study differs from many others in that fluoride exposure to the pregnant mother, rather than the grown child, was investigated. While the authors tended to concentrate on possible chemical toxicity effects on the cognitive development of the child in utero it is also possible that indirect effects could operate. For example, premature birth and low birth weights could themselves be a factor in child cognitive development.

In fact, a quick glance a the literature indicates this may be the case. For example, Basten at al., (2015) reported that preterm birth was associated with “decreased intelligence, reading, and, in particular, mathematics attainment in middle childhood, as well as decreased educational qualifications in young adulthood.” It was also associated with decreased wealth at 42 years of age.

The influence of endemic fluorosis on premature births and birth weights may not involve fluoride directly. Health problems abound in endemic areas – as well as the obvious dental and skeletal fluorosis complaints also involve muscles, blood vessels, red blood cells, the gastrointestinal mucosa and other soft tissues. It is easy to see such health problems influencing the prevalence of premature births and birth weights.

Not relevant to CWF

Of course, none of this is relevant to community water fluoridation. Such fluoridated areas do not have the health problems of areas with endemic fluorosis where drinking water concentrations are much higher. But, of course, this does not stop opponents of CWF claiming that similar problems occur at the lower concentrations.

In case anyone attempts to use this suggestion as an argument against CWF I should mention the only study I could find that makes the link between CWF and fluoridation. Often cited by anti-fluoride campaigners it is a poster paper:

Hart et al., (2009). Relationship between municipal water fluoridation and preterm birth in Upstate New York.

Presented at an Annual Meeting of the American Public Health Association the study appears not to have been published in a peer-reviewed journal. While the authors claim to have found a small, but statistically significant, increase in premature births in fluoridated areas this could be due to a number of possible confounding factors.With only a brief abstract to go on it is impossible to critically assess the study  – in fact, I suspect the non-publication is probably an indication of poor quality.

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More nails in the coffin of the anti-fluoridation myths around IQ and hypothyroidism

thyroid_fluoride

Large Canadian study finds no effect of fluoridation on thyroid health

A new Canadian study shows no relationship of cognitive deficits or diagnosis of hypothyroidism with fluoride in drinking water. This work is important because it counters the claims made by anti-fluoride campaigners. While the campaigners cite scientific studies to support their claims, those studies are usually very weak, or irrelevant because they involve areas of endemic fluorosis where drinking water fluoride concentrations are much higher than in situations where community water fluoridation (CWF) is used.

The study is reported in:

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

This new study is important as it has the advantages of using a large representative sample of the Canadian population, with extensive data validation and quality control measures. It also uses individual-level estimates of fluoride exposure on the one hand, and thyroid health and cognitive problems on the other.

Fluoride exposure was measured both by concentration in tap water for selected households and concentration in urine samples from individuals.

Thyroid health

The Canadian study found:

“Fluoride exposure (from urine and tap water) was not associated with impaired thyroid functioning, as measured by self-reported diagnosis of a thyroid condition or abnormal TSH level.”

This contradicts the conclusions from the population-level study of Peckham et al., (2015) which reported that fluoridation was correlated with the prevalence of hypothyroidism. That study is quoted extensively by anti-fluoridation activists but has been roundly criticised because it did not include the influence of confounders – particularly iodine which is known to influence thyroid health.

Barberio (2016) also suggests that the different recommended fluoride concentrations used for CWF in Canada and the UK, and the fact that the Peckham et al (2015) study did not involve individual measures, could also be factors in the different findings.

Cognitive functioning

The Canadian study reported:

“Fluoride exposure (from urine and tap water) was not associated with self-reported diagnosis of a learning disability.”

Barberio (2016) did also investigate a more detailed diagnosis for cognitive problems and found:

“Higher urinary fluoride was associated with having ‘some’ compared to ‘no’ cognitive problems . . . . however, this association:

  • Was weak;

  • Was not dose-response in nature; and

  • Disappeared when the sample was constrained to those for whom we could discern fluoride exposure from drinking water.”

I guess anti-fluoride activists might latch on to this last point regarding urinary fluoride but, at least as far as tap water fluoride is concerned, there was no relationship with learning difficulties.

Conclusion

So – yet another large-scale study contradicts anti-fluoridationist claims. It shows that CWF has no influence on cognitive problems or thyroid health.

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Water fluoridation – what to expect in the near future

drinking-water-glass-wiki

Community water fluoridation (CWF) will persist in science news for the foreseeable future – not for any valid scientific reason but because of reaction to political pressures against it. This is particularly so in New Zealand where our parliament will be discussing legislative changes to fluoridation decision-making this year.

This is not to say that all the relevant news will be political. There is still ongoing research into the efficacy, cost-effectiveness and possible health effects of fluoridation. Although much of this is a response to pressure from opponents of this social health policy.

So what scientific and political news about CWF should we expect to see in the coming years?

The legislation

In the immediate future, this will be dominated by the new parliamentary legislation [Health (Fluoridation of Drinking Water) Amendment Bill– at least in New Zealand. However, US anti-fluoride campaigners are following this legislation very closely, and will probably become involved in submission on it, so I expect this will also get coverage internationally. At least in the alternative health media which has stong links to the US anti-fluoride activist organisation, Fluoride Action Network (FAN), and which routinely carry their press releases.

The NZ Parliamentary Health Committee is currently taking written submissions on the fluoridation bill. The deadline for these is February 2. Readers interested in making their own submission can find some information on the submission process in my article Fluoridation: members of parliament call for submissions from scientific and health experts.

The bill itself simply transfers the decision-making process for fluoridation from local councils to District Health Boards. But most submissions will inevitably be about the science and not the proposed changes to decision-making – and, considering the promise of the local anti-fluoride group to shower the committee with “thousands and thousands of submissions,” will misrepresent that science. I will be interested to see what allowance the committee chairman makes for such irrelevant submissions when it comes to the public hearings, which could begin as early as February.

The bill has support from all the parliamentary parties, except the small NZ First which apparently wants councils to keep responsibility for fluoridation decisions, but wants to make binding referendums obligatory. So, I predict the bill will be passed this year. However, there will probably be attempts at the committee stages to amend it to transfer decision-making to central government, probably the Ministry of Health. Such an amendment appears to be supported by the Labour Party, but not by the National Party.

The “IQ problem” – a current campaign

There will be some news about research on the question of possible cognitive effects of fluoride in drinking water in the next few years. Not because there is any concern about this among health professionals. But because the claim that fluoride causes a drop in IQ is pushed very strongly by anti-fluoride activists. While they have a long list of claimed negative health effects of fluoridation the IQ claim is currently central to their political campaigns.

The campaigners claim scientific support for this claim. But that support comes mainly from a number of poor quality papers outlining research results from areas of endemic fluorosis (where drinking water concentrations of fluoride are much higher than the optimum levels used for CWF), mainly in China. FAN has a lot invested in this claim because it financed the translation of many of these otherwise obscure papers into English.There is general agreement among health specialists that these studies are not relevant to CWF. Investigation of areas where CWF is used, and where natural fluoride levels are similar to those used in CWF have not shown any neurological effects due to fluoride.

There is general agreement among health specialists that these studies are not relevant to CWF. Investigation of areas where CWF is used, and where natural fluoride levels are similar to those used in CWF have not shown any neurological effects due to fluoride.

However, FAN is strongly pushing the idea that cognitive effects of fluoride (rather than very mild dental fluorosis) should be the main criteria used in determining the recommended maximum levels of fluoride in drinking water. They currently have a petition in front of the US Environmental Protection Agency (EPA) promoting this claim. This may make the news in the near future as the EPA must respond this month and the likely rejection of the petition will no doubt cause a flurry of press releases.

Paul Connett, who with other members of his family runs FAN, has also attempted to use the scientific publication path to promote this claim. His arguments and calculations defining an extremely low maximum concentration, are very naive and his draft paper has already been rejected by journals several times. However, he no doubt lives in hope for its eventual acceptance somewhere. If he is successful this will be trumpeted to the high heavens by his supporters because while they describe Paul Connett as the international authority of water fluoridation he actually has no proper scientific publications in that area.

Research on neurological effects

We expect some research publications in the next year or so from the current US National Toxicity Program research on claims that fluoride at the concentrations used in drinking water fluoridation could have neurological effects. This research is basically a systematic review – according to the proposal:

an “evaluation of the published literature to determine whether exposure to fluoride is associated with effects on neurodevelopment, specifically learning, memory, and cognition.”

The motivation for this work, apart from the political pressure arising from activist claims, is to attempt to evaluate possible effects at concentration relevant to CWF. (Most published animal and human studies have involved higher concentrations). As the proposal says:

“Previous evaluations have found support for an association between fluoride exposure and impaired cognition; however, many of the studies included exposure to high levels of fluoride. Most of the human evidence was from fluoride-endemic regions having high background levels of fluoride, and the animal studies typically included exposure during development to relatively high concentrations of fluoride (>10 mg/L) in drinking water. Thus, the existing literature is limited in its ability to evaluate potential neurocognitive effects of fluoride in people associated with the current U.S. Public Health Service drinking water guidance (0.7 mg/L).”

I discuss the background to the US National Toxicity Program fluoride research in my article Fluoride and IQ – another study coming up.

Canadian Professor Christine Till will soon start a study looking at cognitive and behavioral factors using a data set for pregnant women exposed to contaminants. She intends to investigate the possibility of relationships with markers for fluoride consumption (see ). Anti-fluoride campaigners hold out great hope for results from this study because Till’s previous research is widely used by them to claim that fluoridation causes increased prevalence of attention-deficit hyperactivity disorder (ADHD). However, that research was flawed because potential confounders were not considered properly. In fact, her reported statistically significant correlations disappears when the confounders are included (see  ADHD linked to elevation not fluoridation).

Problems in areas of endemic fluorosis

Health effects including cognitive deficits: The World Health Organisation recommends that drinking water fluoride concentrations should not be higher than 1.5 mg/L because of negative health effects of high concentrations. Many areas of the world do have high drinking water fluoride concentrations and those areas suffer from endemic fluorosis – dental and skeletal fluorosis. This is, of course, a serious problem and there is a continuous stream of research papers devoted to these areas.

This research is not relevant to CWF (where the optimum concentration of 0.7 mg/L or similar levels is used). But, of course, anti-fluoride campaigners will continue to cite these papers as “evidence” against CWF. We may even see an expert on endemic fluorosis being toured in New Zealand to provide scientific credibility to the anti-fluoride campaign. Dr. Ak.K. Susheela, who works on endemic fluorosis in India and has links with FAN, has been speaking at meetings organised by the anti-fluoride movement in North America and has been suggested as a speaker the local anti-fluoride campaigners should bring to New Zealand.

I expect there will be more papers reporting IQ deficits in areas of endemic fluorosis and these will most probably continue to use a chemical toxicity model to explain their results. I personally am interested in the possibility of researchers considering other models, such as the psychological effects of dental and physical deformities like dental and skeletal fluorosis (see Perrott et al. 2015. Severe dental fluorosis and cognitive deficits). Unlikely, considering how research can get locked into pet paradigms, but one can but hope.

Defluoridation: Another big issue in areas of endemic fluorosis is the need to lower drinking water fluoride concentrations. This if often done by finding alternative sources but there is continuing research on treatment methods to do this.

Again, not relevant to CWF – but I do follow this research and find some of it interesting chemically. Perhaps it reminds me of my own research many years ago.

Conclusions

The controversy around CWF is not going to go away. The opposition is strongly grounded in the “natural”/alternative health industry. It has plenty of financial and ideological resources and its message appeals to a significant minority of the population.

Most of the public interest this year will relate to the new legislation – expect plenty of press releases from the anti-fluoride groups as they organise to make and advertise their submissions, and express their anger at the probably inevitable decision that will go against them.

However, there will be a continuing dribble of research reports of relevance to CWF and to the claims advanced by anti-fluoride campaigners. While it is normal for a social health policy to be continually monitored and its literature reviewed, some of this research is a direct result of concerns raised by campaigners and activists.

Many in the scientific community find this sort of political activity annoying. But it does have its up side. CWF has been one of the most hotly contested social health programmes. Consequently is has received more than its fair share of literature reviews and new research.

And that is a good thing. Anti-fluoride activists often claim there is little research on the health effects of CWF. But that is just not true. Ironically it is the very political activity of such campaigners which has led to CWF being one of the most thoroughly researched social health policy.

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Fluoridation: New scientific review of fluoride and oral health

fluoride-oral-healthWant to get up to date on  research about community water fluoridation (CWF) and the effects of fluoride in dental health in general?

Have a read of this new review. It’s published in a special issue of  Community Dental Health devoted to the WHO approach to the prevention of dental caries through the use of fluoride. And is also deals with possible health effects of fluoridation and fluoride in general.

The Paper is:

O’Mullane et al (2016). Fluoride and Oral Health. Community Dental Health 33, 69–99.

Summary and recommendations

The paper summarises the general conclusions and recommendations about CWF as follows:

1. Community water fluoridation is safe and cost-effective and should be introduced and maintained wherever socially acceptable and feasible.
2. The optimum fluoride concentration will normally be within the range 0.5-1.0 mg/L.
3. The technical operation of water-fluoridation systems should be monitored and recorded regularly.
4. Surveys of dental caries and enamel fluorosis should be conducted periodically. For effective surveillance the World Health Organization suggests that clinical oral health surveys should be conducted regularly every five to six years in the same community or setting.

Requirements for a CWF programme

But it is interesting to read its conclusions about the requirements for implementation of water fluoridation. This gives us an idea of why some areas do not fluoridate and what the technical and social requirements are for a successful CWF programme. These are the sort of things that district health boards will need to consider under the current legislations being considered by the New Zealand parliament.

Here is their list:

1. A prevalence of dental caries in the community that is high or moderate, or firm indications that the caries level is increasing.
2. Attainment by the country (or area of a country) of a moderate level of economic and technological development.
3. Availability of a municipal water supply reaching a large proportion of homes.
4. Evidence that people drink water from the municipal supply rather than water from individual wells, rainwater tanks or other sources.
5. Availability of the equipment needed in a treatment plant or pumping station.
6. Availability of a reliable supply of a fluoride-containing chemical of acceptable quality.
7. Availability of trained workers in the water treatment plant who are able to maintain the system and keep adequate records.
8. Availability of sufficient funding for initial installation and running costs.

How many people have access to CWF internationally?

The review has an appendix providing data on worldwide totals for populations with artificially and naturally fluoridated water. This is very useful and anti-fluoride campaigners are well-known for misrepresenting this information in their attempts to claim that most countries reject CWF.

Here is the table for artificial CWF programs:

fluoirdation-world

It says in summary:

“The estimated worldwide total of people supplied with artificially fluoridated water as at April 2011 is 369,226,000 in 25 countries, including the United Kingdom, the United States, Canada, Brazil, Chile, Argentina, Peru, Panama, Guyana, Guatemala, Republic of Ireland, Spain, Serbia, Australia, New Zealand, Fiji, Malaysia, Singapore, Vietnam, Brunei, China (Special Administrative Region of Hong Kong), Papua New Guinea, Republic of Korea (South Korea), Israel and Libya.”

Natural fluoridation

The review also summarises data for people receiving fluoride through the natural levels of fluoride in their drinking water:

Natural fluoridation in the 25 countries operating artificial fluoridation schemes

“In the 25 countries with artificially fluoridated water there are an estimated 18,061,000 million people drinking naturally fluoridated water at or around the optimal level. That brings the total in these 25 countries consuming optimally fluoridated water to around 387,287,000 million.”

Other countries with natural fluoridation

“In addition, there are a further 27 countries with naturally fluoridated water supplied to an estimated 239,903,000 million people. However, it should be stressed that, in many instances, the naturally occurring fluoride level is in excess of the optimum – for example, in China, India, Argentina, Tanzania, Zambia and Zimbabwe. Total worldwide population drinking optimally fluoridated water.”

In summary – 437 million have access to fluoridated water

Combining data for artificial and natural fluoridation the review concludes:

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

Conclusion

This review is useful for anyone wanting an up-to-date picture of CWF, possible health effects and other issues.

I recommend that anyone active in the dental health area or who needs to respond to questions about fluoridation from the public have their own copy. they will refer to it again and again.

This link goes straight to the download of the pdf.

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Anti-fluoride IQ claims are false

false-claims
Anti-fluoridation campaigners’ claims that community water fluoridation reduces IQ are simply false. That is the conclusion of  Alex Kasprak – and he says why in his new Snopes.com article (see Fact Check -Fluor-IQ).

These days anti-fluoridation activists use this claim as their main argument – and they often cite scientific articles to back it up. But, Kasprak says, this claim  is based on “either willful or negligent misreading of actual science.” The claim that  studies have “linked” fluoride to reduced intelligence “is a textbook-ready case of bait-and-switch:”

” the topic has surreptitiously been shifted from the act of water fluoridation as a public health measure to the broader concept of fluoride toxicity in children. Many otherwise benign chemicals can also be harmful in high concentrations. Thiocyanate, a chemical found in kale, may kill you at high doses, for example.”

Scale and context

Kasprak critiques the way anti-fluoride campaigners so often use and cite the Choi et al., (2012) study. This was a meta-analysis of 27 mostly poor quality Chinese studies from areas of endemic fluorosis where drinking water fluoride levels are much higher than that used in community water fluoridation.

Citing neuroscientist Steven Novella Kasprak points out:

“There was a lot of variability across the studies, but generally the high fluoride groups were in the 2-10 mg/L range, while the reference low fluoride groups were in the 0.5-1.0 mg/L range […]”

In other words – fluoridated water in the US has the same level of fluoride as the control or low fluoride groups in the China studies reviewed in the recent article, and the negative association with IQ was only found where fluoride levels were much higher – generally above EPA limits.

Note: The optimum level of fluoridated water in the US is 0.7 mg/L.

Anti-fluoride campaigners sometimes concentrate on those studies in the meta-review which did focus on concentrations close to that considered optimum. But:

“Of those eight studies, half of them co-investigated fluoride and iodine together (Lin et al 1991, Xu et al 1994, Yang et al 1994, Hong et al 2001) making it hard or in some cases impossible to separate out the combined effects, and two of those four studies reached conclusions that are counter to the hypothesis that fluoridation levels alone are the main driver of a lower IQ.”

And:

“Two of those eight studies use a control group with fluoride values that are literally the same or higher than the target range of fluoridation efforts in the United States (Xu et al 1994, Hong et al 2001), seemingly ceding the point that those levels do not affect children’s IQ.”

So, as far as scale is concerned, Kasprak concludes:

“Collectively, this demonstrates that most of the IQ variance presented in the Harvard study still stems from exposures to extremely high levels of fluoride that would already be considered dangerous in the US, and those studies finding effects on a smaller scale are not sufficient to demonstrate the effects those groups opposed to fluoridation claim they demonstrate.”

As far as context is concerned none of these 27 studies were relevant to community water fluoridation:

“Literally none of the studies involved tested populations of individuals exposed to drinking water that was artificially supplemented with fluoride as a public health measure. Instead, all of the studies come from China or Iran, both of which have areas of naturally occurring (endemic) high fluoride pockets of groundwater.

That means that studies utilized in its analysis are wholly irrelevant to the question that advocates claim they are answering. This is significant, as the use of these very specific studies introduces a veritable Homerian epic of confounding details, some of which came up in our analysis of the eight low-level fluoride studies discussed above. Among the most pressing of these are a lack of information on other confounding variables and the quality of the studies they utilized. These issues are noted by the authors of the Harvard study themselves”

The authors of the Choi et al (2012) meta-review also:

“explicitly state that the results cannot be used to estimate the possible limits of fluoride exposure with respect to developmental damage, due to lack of data – ‘Our review cannot be used to derive an exposure limit, because the actual exposures of the individual children are not known.'”

Other mechanisms

Kasprek disagrees with the unsubstantiated claim of Choi et al., (2012) that other neurotoxicants are unlikely to be present in the groundwater of the studied areas. Rightly so because all those studies suffer from insufficient consideration of confounding factors. As Choi et al., (2012) said: “Most reports were fairly brief and complete information on covariates was not available.” 

In fact, statistical analysis of the data in one of the better papers the anti-fluoride campaigners rely on shows that fluoride can explain only about 3% of the measured variance in IQ. It is extremely likely that inclusion of sensible confounders in the statistical analysis would have shown any relationship of IQ with fluoride is not statistically signficant (see Connett misrepresents the fluoride and IQ data yet again).

Kasprek briefly considered arsenic as a possible confounder but with subjects like cognitive ability or IQ there are many other physical and social factors that could be imnportant.contaminants. Parental income and education as well as the psychological consequences of deformities resulting from dental and skeletal fluorosis. I discussed this last aspect in my peer-reviewed article Perrott (2015), Severe dental fluorosis and cognitive deficits and my post- Severe dental fluorosis the real cause of IQ deficits?

Fallacy of publication journal

I think Kasprek’s argument about the journal used for publishing some of these papers is fallacious:”

“Finally, four of these eight papers (Yang et al 1994, Lu et al 2000, Hong et al 2001, Xiang et al 2003a) are either published (or republished) in the allegedly peer-reviewed journal Fluoride, a publication of the “International Society for Fluoride Research Inc.” — an anti-fluoridation group whose editor-in-chief is a psychiatrist in private practice, with no academic background on the topic of fluoride toxicity.”

I am very much opposed to using the place of publication as an argument against the scientific veracity of a paper. True, Fluoride is a very poor quality journal. True, is has an ant-fluoride agenda. And true, it shows no evidence of proper peer review. However, it is disingenuous to use these facts to argue against the scientific content of these papers. Critique of the papers should rest on an analysis of their scientific content – not the place of publication.

This lazy approach is doubly worse because it carries the implication that if these papers had been published in a reputable journal with good peer review then that would be sufficient to guarantee the veracity of the science. It is not.

On the fluoride issue, there are plenty of examples of papers involving poor science that are published in reputable journals. I have discussed some of these in my articles – for example ADHD linked to elevation not fluoridationAnti-fluoride hypothyroidism paper slammed yet againPoor peer review – and its consequencesDoes community water fluoridation reduce diabetes prevalence?, The Harvard study and the Lancet paperControversial IQ study hammered in The Lancet and Repeating bad science on fluoride.

The lazy judgmentalism based on place of publication, and not content, is particularly relevant at the moment with the public concern about “false news” and efforts to introduce mechanisms of “fact checking.” Some people are advocating reliance on websites like Snopes.com – yet this site can be blatantly biased on political matters. And its bias can rest on the lazy approach of condemning a news article by its place of publication.

[A recent example was a Snopes.com article which cast aspersions on an independent journalist, Eva Bartlett, because – “She is also a contributor at RT, a news site funded by the Russian government.” OK, you may not see how lazy that argument is but try replacing the words RT and Russian by “Al Jazeera” and Qatar” or “BBC” and “British.” And, I also think describing the fact that Bartlett had been interviewed by an RT reporter, and participated in a debate aired by RT, as being a “contributor” shows a bias]

The good science

Despite delving into the details of the poor quality papers the anti-fluoride IQ argument relies on Kasprak is quite right to stress:

“This should not function as a distraction from the larger point that studying naturally occurring pockets of high fluoride and the assessing the risks of supplementing public drinking water in an effort to have it reach a concentration of 0.7 mg/L are two completely different beasts.”

So, my other criticism of Kasprak’s article is that he could have said more about the studies which are relevant to community water fluoridation.  He does briefly refer to the New Zealand study of Broadbent et al (2014) in a quote from  Ireland’s Health Research Board:

“There was only one study carried out in a non-endemic or CWF [community water fluoridation] area that examined fluoride and IQ. This was a prospective cohort study (whose design is appropriate to infer causality) in New Zealand. The study concluded that there was no evidence of a detrimental effect on IQ as a result of exposure to CWF.”

However, he missed the 2016 study of  Aggeborn & Öhman (perhaps it was too recent for him) which I discussed in my article Large Swedish study finds no effect of fluoride on IQ. The results of this study were so precise and the sample numbers used are so large it should be seriously considered by anyone looking at this issue.

Conclusion

Kasprak’s article is useful in exposing the false claim of activists that fluoride lowers IQ – especially when used in arguments against community water fluoridation. But he could have said more – and he could have avoided the fallacious argument based on place of publication which is so easily reversed to support poor quality science in reputable journals.

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December ’16 – NZ blogs sitemeter ranking

happy-new-year2017-13

Image Credit: Happy New year Images

There are about 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters. Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for December 2016. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers. Meanwhile, I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

Subscribe to NZ Blog Rankings Subscribe to NZ blog rankings by Email Find out how to get Subscription & email updates Continue reading

Large Swedish study finds no effect of fluoride on IQ

sweden-f

Fluoride levels in Swedish drinking water (mg/L). Variation between municipalities. Source: Aggeborn & Öhman (2016)

A significant new Swedish study shows fluoride in drinking water, at the concentrations used for community water fluoridation, has no effect on IQ or other measures of cognitive ability. Similarly, it has no effect on diagnosis or prescription of medicines for ADHD, depression, psychiatric illnesses, neurological illnesses or muscular or musculoskeletal diseases.

On the other hand, the study showed positive effects of fluoride on income and employment status – most probably because better dental health is beneficial in the labour market.

This work is reported in:

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

The study covers most of the health effects that anti-fluoride campaigners complain about. It really should put all these complaints to rest as the quality of this new study is much better than anything the campaigners rely on for the following reasons:

  • It involved a much large sample. Over 700,000 individuals were involved. The numbers included in specific measurements varied but they were much greater than those used in the studies cited by anti-fluoride campaigners. For example, almost 82,000 were involved in the cognitive ability comparisons – compared with a few hundred at the most in the comparable studies cited by anti-fluoride campaigners.
  • Estimates of effects were much more precise (as expected with large numbers of subjects) than for previous studies. The effect of fluoride on cognitive ability was always close to zero and for practical purposes was zero.
  • Statistical analyses were based on continuously varying fluoride levels – a much better approach than the simple comparison of data for low and high fluoride villages used in the studies cited by anti-fluoride campaigners.

Sweden is an ideal country for studying effects of fluoride at these low concentrations. It does not have artificial water fluoridation but its drinking water contains naturally occurring fluoride. The fluoride concentration in drinking water depends on the geology of the region so different Swedish communities consume water with different fluoride concentrations.

This graphic from the paper shows the number of people drinking water with various concentrations of fluoride. Note – the steps are 0.1 mg/L and although concentrations above 2.0 mg/L occur they are relatively rare. Sweden makes no attempt to remove excess fluoride until the concentrations exceed 1.5 mg/L – the maximum recommended by the World Health Organisation. For comparison, the recommended optimum concentration in  New Zealand is 0.7 mg/L.

sweden-f-01

Histogram of numbers people drinking water containing naturally occurring fluoride at different concentrations. Source: Aggeborn & Öhman (2016)

Effects of fluoride on dental health

The Swedish data showed positive effects of fluoride on oral health. For example, the share of dentists visits “decreased by approximately 6.6 percentage points if fluoride is increased by 1 mg/l. This should be considered as a large effect.” Tooth repairs are closely related to fluoride. “If fluoride would increase with 1 mg/l, the share of 20-year-olds that had a tooth repaired would be decreased approximately 3.4 percentage points considering the 2013 sample. Again, this effect is large, especially for this cohort.”

Cognitive ability

Relevant data was used from national education tests and psychological tests during the years of the Swedish military conscription. The statistical analysis produced estimates which were all very small and often not statistically significant. The estimates were sometimes negative and sometimes positive. For example, an estimate including covariates showed that “cognitive ability is increased by 0.045 Stanine points [equivalent to about 0.3 IQ points] if fluoride is increased by 1 mg/l (a large increase in fluoride). This should be considered as a zero-effect on cognitive ability.”

Other possible health effects

The authors considered the effects of fluoride on the prescription of medicines for ADHD, depression, and psychoses. They also looked at psychiatric and neurological diagnoses from outpatient and inpatient registers, as well as diagnoses of muscular and skeletal diseases. Anti-fluoride campaigners often claim fluoride has a harmful effect on these health problems.

The was no effect of fluoride on the possibilities of being prescribed any of these medicines.  For example “the probability of receiving ADHD medicines is decreased by 0.2 percentage points if fluoride is increased by 1 mg/l. In economic terms, this effect is a zero-effect.”

It was the same for all the diagnoses considered –  “The estimated effects are small and often statistically insignificant.”

According to the authors:

“In conclusion, we do not find that fluoride has any effects on these health outcomes. This further strengthens our argument that fluoride does not have any negative effects for levels below 1.5 mg/l on human capital development or health outcomes related to human capital development. It is also interesting that we do not find any effects on diagnoses for muscular and skeleton diseases, which has been a question also discussed in connection to fluoride.”

Annual income and employment status

The lack of any effect of fluoride on IQ and other psychological and non-psychological estimates suggest that fluoride would have no effect on long-term outcomes like income and employment status. However, the authors suggested that it could have a positive influence on these outcomes because of better dental health.

And this was the case. Estimates of the effect of fluoride on income were always positive and usually statistically significant. The authors estimated that “income increases by 4.2 percent if fluoride increases by 1 mg/l. This is not a negligible effect and the estimate should be considered as economically significant.”

Similarly for employment status. “If fluoride is increased by 1 mg/l, then the probability that the person is employed is increased by 2 percentage points. This result thus point in the same direction as the results for log income where both these results are significant in economic terms.”

Further analysis indicated “that when dental repairs increases by 1 percentage point, income decreases by 2 percent on the same aggregate level. This effect is clearly economically significant. This indicates that fluoride improves labor market outcomes through better dental health.”

Conclusions

This is an important study. It involved large numbers of people, estimated outcomes were far more precise than in previous studies, it used continuously varying concentrations of fluoride instead of simply comparing high fluoride and low fluoride villages, and it considered possible long-term outcomes like income and employment chances.

The advantages of this study compared with the generally poor quality studies cited by anti-fluoride campaigners should put to rest arguments used by those campaigners. In particular, it should make the current campaigns relying on to IQ and cognitive effects irrelevant.

The authors comment that their data shows there is no need to consider negative health effects on consideration of the cost-effectiveness of community water fluoridation. I wonder if, in fact, these results will encourage policy makers to consider the cost benefits of improved income and employment chances in future calculations of the cost-effectiveness of fluoridation programmes.

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Fluoridation: New research confirms it is cost effective – yet again

Cyber-The-Vote-Cost-Benefit-Analysis-1

Yet again a cost-benefit analysis shows community water fluoridation to save far more than it costs.

A new study has found, once again, that community water fluoridation (CWF) saves more than it costs. Carrying on from the previous most comprehensive study in 2001 this new study is based on updated costs of CWF and the averted lifetime costs of dental treatment in the United States.

It estimates savings from averted tooth decay in 2013  as a result of CWF to be about $32 per capita. The estimated costs of CWF in 2013 was $324 million. The net saving (savings minus costs) from CWF was estimated to be $6,469 million.

The estimated return on investment (annual net saving/annual costs), averaged across all sizes of water systems, was 20.

The study is published in this paper:

O’Connell, J., Rockell, J., Ouellet, J., Tomar, S. L., & Maas, W. (2016). Costs And Savings Associated With Community Water Fluoridation In The United States. Health Affairs, 35(12), 2224–2232.

These figures strongly show that further savings could be achieved by extending CWF in the USA. the authors say:

“During 2013 more than seventy-eight million people had access to a public water system that served 1,000 or more people that did not fluoridate the water. Our findings suggest that if those water systems had implemented fluoridation, an additional $2.5 billion might have been saved as a result of reductions in caries.”

This study found large saving from CWF despite using a lower estimate of tooth decay present when  there is no fluoridation than used by some other studies. The present study relied on estimations of decayed and filled teeth, rather than the more sensitive measure of decay and filled tooth surfaces.

The authors also investigated the robustness of their conclusion by estimating the return on investment for different figures of reduced tooth decay due to CWF. This varied from 16.5 when CWF effectiveness was assumed to be 20% (less effective than the estimated 25%) to 23.7 when  CWF was assumed to be 30% (more effective than the estimated 25%).

Of course, anti-fluoridation propagandists will rubbish this study – just as they have every other study which does not support their message. And their message will be the same they have used to attack every other high-quality cost-effectiveness study of CWF. They will claim it is biased because it does not include consideration of adverse effects of CWF. In particular, costs related to dental fluorosis.

In recent years their argument relies strongly on the flawed work of Ko & Thiessen (2014) – A critique of recent economic evaluations of community water fluoridation. This is flawed because it includes the cost of treatment fo moderate and severe forms of dental fluorosis.  This is despite acknowledging in their discussion that CWF is not responsible for any moderate or severe forms of dental fluorosis. I have discussed this further in Alternative reality of anti-fluoride “science”.

Mind you, I still expect anti-fluoride commenters here to the Ko and Thiessen study at me.

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Fluoridation: members of parliament call from submissions from scientific and health experts

The new community water fluoridation legislation is now on the way in the New Zealand parliament. The Health (Fluoridation of Drinking Water) Amendment Bill was introduced on Tuesday and the parliamentary health committee has invited submissions.

It’s worth watching the videos of the twelve speakers in the first reading. These give an idea of how the legislation will be received by the different political parties. They also give an impression that members of our parliament are well aware of the tactics of the anti-fluoride pressure groups – they fully expect to be inundated with irrelevant and pseudoscientific submissions. But they are also aware that the science currently finds community water fluoridation to be both effective and safe.

After watching the debate these are my initial conclusions:

  1. The bill has almost unanimous support. Only New Zealand First voted against it.
  2. Many of the speakers see the legislation as only a little better than the current situation. The describe it as a half-way house – kicking the can down the road. District Health Boards (DHBs) will be subjected to the same uninformed or misleading pressure that the councils are at present. The government should have gone the whole hog and handed over responsibility for fluoridation decision to the Ministry of Health.
  3. All the speakers declared their support for the science that shows community water fluoridation effective and safe. Most showed they are aware of, and accept, the New Zealand Fluoridation review commissioned by the Royal Society of New Zealand and the Office of the Prime Minister’s Chief Science Advisor.
  4. None of the speakers showed any support for the arguments or activities of anti-fluoridation campaigners. In fact, there were many derogatory comments made about tin foil hats, etc.
  5. New Zealand First is opposed because they prefer that communities make fluoridation decisions by referenda and are calling for these referenda to be binding. They criticised those councils like Whakatane and Hamilton that had ignored the wishes of the community.

Health Committee calling for submissions

The Parliamentary health select committee has called for submissions on the bill. Written submission will be accepted until February 2, 2017.

Information on making a submission is available on the Health (Fluoridation of Drinking Water) Amendment Bill website. And you can make your submissions online.

You can also give notice that you wish to make an oral submission to the Health Committee.

Possible issues of contention

From what speakers in the debate had to say I do not think the anti-fluoride lobby will get much sympathy. MPs are expecting the usual deluge of submissions from them but know from experience how worthless they will be.

However, several MPs stressed they did welcome submissions and particularly encouraged submissions from scientific and health experts. The Royal Society of NZ and the Prime Minster’s Chief Scientific advisor may be specifically invited to make submissions.

The bill is not really about the science, however, and MPs expect that the real content – the processes for making fluoridation decisions and the body responsible for these, should be thoroughly discussed.

I expect there will be a strong push to strengthen the bill by moving responsibility to central government, the Ministry of Health, as MPs still see problems with DHB responsibility.

The issue of community consultation should also come up – particularly as New Zealand First is promoting the idea of binding referenda in communities. As it stands the bill does not define how consultation should occur so this may well be made more specific.

The Green Party seems keen to introduce mechanisms for better informing of the public about the science behind fluoridation. They are conscious that the anti-fluoride groups are fear-mongering on this issue and feel that this can be countered by better information. If this is discussed in depth in the hearings there may well be some interest in defining more specifically how government updates its understanding of the research on fluoridation and how they disseminate new research results to the public.

A role for you, the reader

Well, the process is underway. If you have views or concerns on the bill or on the decision processes involved with fluoridation now is the time to put pen to paper, punch away on your computer keyboard, or prepare for making an oral submission to the health committee. If you want advice on how to do this have a read of Making a Submission to a Parliamentary Select Committee and the linked documents.

Remember, written submissions are accepted until February 2, 2017, and we would expect the Health committee hearings to start soon after that.

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Leader of flawed fluoridation study gets money for another go

christine-till

Professor Christine Till has been given a $300,000 grant to test for harmful effects of fluoride.

Malin and Till (2015) published research indicating a relationship between fluoridation and Attention Deficit Hyperactivity Disorder (ADHD). However, that study was flawed because it omitted important confounders. When these are included the relationship disappears.

I analysed that study in my article ADHD linked to elevation not fluoridation where I showed the relationship of ADHD to elevation was much more important than fluoridation. Huber at al., (2015) published work confirming the relationship of ADHD with elevation. So, obviously, elevation is an important confounder and  Malin and Till (2015) did not consider it in their study.

My own analysis indicated that there were a number of other confounders which are related to ADHD – with correlations similar to (eg., educational attainment, proportion of the sate’s population older than 65  and Per Capita personal income) or better (mean state elevation, home ownership and % living in poverty ) than that for fluoridation. That rings alarm bells – why consider only one factor (fluoridation) if there are other factors which appear equally or more important? Isn’t that confirmation bias? (I concede that Malin and Till did include a socioeconomic measure in their statistical analysis – but this was clearly not enough).

I tested the relative importance of the different facts using multiple regression and – sure enough – found that once a few important confounders were included water fluoridation could not explain any of the variance in ADHD! The statistically significant factors were mean elevation, home ownership, and poverty. The contribution of fluoridation was not statistically significant in this multiple regression.

A model including mean state elevation, home ownership and poverty explains about 45% of the variance in ADHD – much better than fluoridation could (Malin and Till explained 27 -32% for the fluoridation data).

Now, I read that Professor Till has been given research finds to have another go and possible harmful effects of fluoride. (see York professor leads study that could help answer fluoride safety questions). She plans to look at data from a Canadian investigation of pregnant women exposed to  contaminants. She says:

“Our study employs a prospective design that includes biomarkers of exposure to fluoride, detailed assessment of potential confounders, a comparison group, and the use of sensitive cognitive and behavioural measures that have been collected in one of the world’s most comprehensively characterized national pregnancy cohorts (MIREC).”

Now, I am pleased she aspires to a “detailed assessment of potential confounders” but wonder how detailed this will be after the problems with the Malin and Till (2015) study.

I have not yet seen any published response to the Malin and Till paper – maybe the cost of publication (US$2020) that journal is discouraging critics. It certainly discouraged me (I do not have institutional support for publication costs). Nevertheless, I hope professor Till has been acquainted with some of the criticism of that paper so that she can pay more attention to important confounders in the coming work

We can draw a few lessons from this.

Be careful of published statistical relationships

These days it is so easy to hunt down data and do this sort of exploratory statistical searching for significant relationships. But a statistically significant relationship is not evidence of a real cause. For example, there is a strong relationship between the sales of organic produce and prevalence of autism – but I have yet to hear anyone seriously suggest the relationship is at all causal.

But the scientific literature is still full of such studies – and I guess the motivated author can easily find arguments and other data in the literature that they, at least, feel convincing enough to justify publication.

Refereeing of scientific papers is, on the whole, abysmal

All authors have a pretty good idea of which journals, and reviewers, will be friendlier to their work – and which would be antagonistic. It is only natural tosubmitt to the friendlier journal.

Unfortunately, the Malin and Till paper was submitted to a journal with editors known to be friendly to a chemical toxicity model of cognitive deficits. Further, it turns out that the reviewers chosen for the paper were also supportive of such an approach.

While one reviewer did suggest including lead as a possible confounder (again showing a chemical toxicity bias) none of them suggested consideration of other confounders more likely to be connected with ADHD.

I discussed the editorial and reviewer problems of the Malin and Till paper in . (The journal, Environmental Health, has a transparent peer-review process which provides access to the names and reports of the reviewers.)

Again – another example of readers beware – even readers of scientific papers in credible journals.

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