Category Archives: science

Facts about fluorosis – not a worry in New Zealand

This sort of serious dental fluorosis does not occur in New Zealand

A recent issue of the Fluoride Exposed Newsletter gives us the facts about dental fluorosis – a subject very often misrepresented by opponents of community water fluoridation.

Fluoride Exposed also explores what U.S. Surgeon Generals have done to promote prevention of both tooth decay and fluorosis in an article on their website, Is fluoride good for your teeth?:


Ever notice how words ending with “-osis” sound a bit scary?  That’s because “-osis” is a suffix (from the Greek) commonly used to describe disorders or abnormal states. Tuberculosis, multiple sclerosis…no fun. Those are serious.

Dental fluorosis is one of those things that sounds scarier than it actually is… at least if you live in a country like the good old U.S. of A., where public health and environmental protection agencies and organizations have made the scary kind of dental fluorosis (severe dental fluorosis) exceedingly rare.

Dental fluorosis is a little like blood pressure.  When it’s low, you’re good – in fact, mild dental fluorosis can protect your teeth from cavities.  Moderate dental fluorosis describes the appearance of tooth enamel when kids get exposed to a bit too much fluoride.  Changes range from barely visible white spots or streaks (in most cases) to white spots that are a cosmetic concern.  Severe forms involve staining and pitting.  These severe forms of fluorosis are super rare in the U.S. – because we have those protections we mentioned. In the States, we make sure fluoride isn’t too low or too high in drinking water.  It’s only in regions such as rural India, China, and the African Rift Valley, where severe dental fluorosis commonly reaches an actual disease state and affects tooth health and function.  But in the U.S., fluorosis is one of those things that’s not as scary as it sounds.

As you may already know, fluoride gets into your tooth enamel during the remineralization process and forms a super compound called fluoroapatite that resists decay.  For this reason, our dentists want us to get fluoride, ideally through drinking water and fluoride toothpaste.  Or if you’re in a community without fluoridated water, there are dental treatments and dietary supplements you can get.

But if a child who’s still developing teeth gets too much fluoride, dental fluorosis can occur while the teeth are still forming under the gums.  Data from the National Health and Nutrition Examination Survey (1999-2004) tells us that less than one-quarter of persons aged 6-49 in the United States had some form of dental fluorosis.

They even made a chart that shows the severity level of those affected:

Note: One interesting factoid: In this study, the rate of fluorosis for teenagers aged 12-15 was forty percent! That’s significantly higher than the rate for all age groups taken together.  It’s a data point we’ll be keeping an eye on in future studies.

According to the American Dental Association (ADA), the mild and moderate forms of dental fluorosis we have in the U.S. do not negatively affect the health of your teeth. It’s actually even correlated with some good things.  For example, rates of dental fluorosis are higher in kids whose teeth are more resistant to tooth decay.  Makes sense, right?

That said, we can make sure a child’s amount of fluoride is “just right” – enough to provide cavity protection, but not enough to cause visible changes in the tooth enamel.
5 ways to prevent kiddos from ingesting too much fluoride:

    1. Don’t give kids fluoride supplements if your drinking water is already at or above the recommended fluoride concentration of 0.7 mg/L.  You can find out if your water system fluoridates and at what level from this cool site from the CDC: https://nccd.cdc.gov/DOH_MWF/Default/Default.aspx.  Or call your water utility provider.
    2. If your drinking water contains greater than 2 mg/L of fluoride, children 8 years and younger should use an alternative source of drinking water.  A little less than 1% of Americans on public water systems have fluoride above this level.
    3. If you have well water, have it tested for fluoride levels, and again, use an alternative source for kids if fluoride is more than 2 mg/L.  Use an alternative source for everyone in the family if it tests at or above 4 mg/L.
    4. Use only a rice-grain-sized amount of fluoride toothpaste to brush kids’ teeth if they’re younger than 3.
    5. For kids who are 3-6 years old, use a pea-size amount of fluoride toothpaste, and supervise these preschool kids when they brush so they don’t swallow too much fluoride toothpaste.

So that’s it! Dental Fluorosis: it’s a scary name, but not a big worry in the U.S.

Whew! One less “-osis” to freak out about!

Subscribe to the Fluoride Exposed newsletter.

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We need more post-publication peer review

We often tout peer review as the reason for accepting the veracity of published scientific studies? But how good is it really? Does it ever match the ideal picture people have of it? And what about peer review before and after publication – are we neglecting these important stages?

Pre-publication peer review

Here I mean the collective process of evaluating ideas and presentations together with scientific colleagues. It’s great when it happens. Ideas flow and the critiques help prevent mistakes from persisting

This happens during discussion of research proposals and of research results. It happens during preparation of presentations.

But, unfortunately, it does not always happen – in fact, I suspect it may be relatively rare. When scientific reforms were introduced into New Zealand almost 30 years ago I noticed some scientific colleagues became less forthcoming about their ideas and research proposals. An air of competition seemed to destroy the previous cooperation.

Maybe things are better now. Hopefully there is less completion between individuals and within groups and institutions – although I imagine the competition between institutions will always be a problem. Quite apart from competing for grants humans simply identify with their own groups and fall victim to the “them vs us” problem.

Publication peer review

There is an impression that publication peer review happens only when the paper is submitted to a journal. But I think some of the best reviewing of a draft paper actually comes from colleagues before submission. That is why I strongly appreciated the institutional requirements I experienced that a draft paper be peer-reviewed within the institution before submission.

Unfortunately, not all institutions require this. I sometimes think many universities which don’t require this are taking “academic freedom” too far.

Perhaps some scientists see this as only landing extra work on them – but surely knocking a paper into better shape before submission is beneficial to both authors (getting a better draft)  and institutes (maintaining a reputation with journals).

Then there is the peer review organised by the journal. Many people think that is the only peer review. Just as well it isn’t because it can be very bad.

I am sure many poor quality papers slip through to be published simply because reviewers do not do a good job or spend insufficient time on that job. Personally, my impression of reviewers and journals drop when I see reviewers comments indicating a lack of attention or responsibility. Even worse, when I have had a paper accepted by an editor saying the reviewers had no comments I seriously questioned the quality of the journal and the advisability of submitting to it in future.

Still, when an author gets conscientious reviewers and comments indicating the paper has been read carefully an author can’t help but be appreciative – even if it means more work knocking the paper into shape.

As a reviewer, I always attempted to do a thorough job – even if it meant producing an over-long and detailed report. I once a received, via an editor, a response from an author I had reviewed expressing appreciation of the detail so I know such attention to detail is worthwhile.

I think most scientific authors will have occasionally faced the problem of brief or perfunctory reviewing of their submitted papers and can, therefore, understand the feelings behind that note.

Post-publication peer review

This is hardly ever considered. Once published the authors move on – their job is done. Readers also tend to be very accepting of published papers – after all peer review means that the paper’s findings must be trustworthy.

But this is obviously not the case. I think the slogan “reader beware” applies just as much to the scientific literature as it does to the news media. The reader should not automatically accept reported findings or conclusions as correct – just because the paper was peer-reviewed. They should do their own due diligence, consider all papers critically and avoid automatic acceptance.

Formal post-publication peer review can occur – but it is not as common as it should be. Some online journals provide space for readers comments. Helpful to the author but not adequate for proper evaluation.

The best post-publication peer review comes from published critiques because they become part of the established literature and available to anyone following up a subject or reviewing a field. Some journals provide space for shorter critiques of this sort – not requiring these authors to present new and original data but simply critique what has been published. Of course, despite the lower requirements such critiques should undergo their own peer review consistent with the policies of the journal.

The ethics of post-publication review

This is sore point for me – having had an editor recently refuse to consider a critique of mine (see Fluoridation not associated with ADHD – a myth put to rest). 

Surely there is a moral obligation for a journal, and its editor, to consider submissions of critiques of paper they have published? This is the obvious place for a critique – and the journal can normally then offer the right of reply to the original authors.  The writer of a critique should not have to search out an alternative journal – especially as the lack of new data or new research in a critique makes its acceptance by an alternative journal problematic. Nor should the original authors be denied an automatic right of reply which can be provided by the original journal.

Authors of a critique can face obstacles like the cost of publication. An original paper may be published in a journal which extracts publication fees from the author. It is the original authors decision whether or not to publish in such journals. But it seems unethical to expect the submitter of a critique to pay such fees. That puts a financial hurdle in the way of proper scientific peer-review. The original authors’ institution may be prepared to cover the cost of publication but institutions are unlikely to financially cover critiques in the same way.

The other obstacle is, of course, the attitude of editors. It is surely just common sense that critiques should undergo the normal peer review but when journals or editors refuse outright to even consider a critique, to not even enable it to undergo peer review, then that is ethically wrong.

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Cassini plunges into Saturn tonight – a grand finale

Starting at 10.31 pm NZ time tonight

Key Events

Sept 15:

10:31a.m. UTC (3:31 am PDT) – Cassini’s final entry into Saturn’s atmosphere begins

10:32 a.m. UTC (3:32 a.m. PDT) – Spacecraft loss of signal comes one minute later

11:55a.m. UTC (4:55 a.m. PDT) – Predicted final loss of signal on Earth

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What’s with the anti-fluoridationist promotion of dental health programmes?

“Healthy Teeth, Happy Smile” leaflet promoting dental health programme in Leicester, UK

Anti-fluoride campaigners often promote dental health programmes which they argue are alternatives to community water fluoridation. But seem not to understand that these programmes usually include fluoride dental treatments.

It’s probably a result of some tactical thinking – “let’s promote a positive message to overcome the publicly perceived negativity associated with our opposition to a social health policy like fluoridation.” In fact, some New Zealand anti-fluoride activists have specifically expressed it this way.

But the sting in the tail of this tactic is their promotion of the idea these programmes are an alternative to community water fluoridation (CWF). In reality, they are not genuine about their positive support of a social health policy – they still want to convey a message of opposition to CWF by pretending these policies are successful alternatives.

These programmes may be successful – but they are not alternatives to CWF.  Health authorities promoting them usually see them as complementary to CWF  – certainly not substitutes or alternatives. In fact, these dental health programmes usually include fluoride varnish treatment for children’s teeth.

An example is the “Healthy Teeth, Happy Smile” programme reported as being very successful in the UK city of Leicester. See  City with worst tooth decay in children sees marked improvement). It aims to improve the dental health of young children and includes exercises like supervised tooth brushing in nurseries and linking families up with dentists. The image above shows the first page of a leaflet about the scheme. Notice that it encourages fluoride varnishing of the teeth of young children and offers this free (the image below shows the relevant detail from the leaflet) and yet Fluoride Free New Zealand, the local anti-fluoride group, is promoting it!

The Leicester City Council in its promotion of the scheme lists the following actions for parents:

  • take your child to see the dentist before they are one and go regularly
  • brush your child’s teeth as soon as the first tooth appears
  • brush at least twice a day
  • don’t rinse after brushing just spit the toothpaste out
  • use a fluoride toothpaste
  • ask your dentist about fluoride varnish
  • limit sugary drinks and snacks to meal times only.

The scheme is based on the Oral Health Promotion Strategy for pre-school children which describes its objectives as:

 Optimising exposure to fluoride
 Gain multi-partnership support in order for everyone to play a role in
improving oral health
 Improve preventive and routine dental attendance
 Improve parental skills on caring for children’s oral health

So hardly an alternative to fluoride or CWF.

I have written about other dental health programme which anti-fluoride activists misleadingly promote as alternatives to CWF before.

For example:

The Nexo programme on Sweden – Fluoridation: Open letter to Democrats for Social Credit;

The Scottish ChildSmile programme – ChildSmile dental health – its pros and cons and ChildSmile – a complement, not an alternative, to fluoridation.

I have also made the point that in New Zealand the different District Health Boards often have dental health programmes which incorporate elements of all the three programmes discussed here. They are not run as alternatives to CWF – although some health boards do put extra resources, such a fluoride tooth varnishing into the non-fluoridated areas. For obvious reasons.

Examples are the Mighty Mouth Dental programme run by Counties Manukau District Health Board and the Healthy Smile, Healthy Child programme run by the Ministry of Health and the New Zealand Dental Association.

Whether or not health authorities choose to give their dental health programmes catchy titles such programmes are important. CWF is not a magic bullet and oral health is also served by complementary programmes like these which incorporate education, early training in the use of toothbrushes, connecting families with dentists and use of fluoride varnishes.

Just don’t be fooled into thinking such programmes are substitutes or alternatives to CWF. Especially don’t be fooled by activists who are not seriously promoting dental health but simply attempting to fool people by pretending such programmes could be used instead of CWF.

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Fluoridation not associated with ADHD – a myth put to rest

Fluoridated water is NOT associated with ADHD: Photo by mtl_moe

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

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

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

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

The Background

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

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

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

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

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

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

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

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

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

Publication problems

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

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

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

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

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

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

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

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

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

The guts of the paper

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

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

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

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

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

Take home message

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

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Are fluoride researchers sacked for their findings?

Dr Phyllis Mullenix – employment terminated because of her fluoride research or other reasons? (Image credit: NYC Coalition Against Artificial Fluoridation)

Heard the one about the scientist who was doing excellent research but was sacked by her Institute because her discoveries shattered the prevailing “scientific orthodoxies?”

Yes, it is a common claim. Often made by activists promoting conspiracy theories.  But it is an easy one to make and it is always worth checking the facts in such cases.

Of course, the anti-fluoridation movement is no exception – they claim that a number of “anti-fluoridation scientists” have been sacked for their work. Here I will just look at one of these stories – that of Dr Phyllis Mullenix.

The Mullenix story

A few facts.

Phyllis Mullenix was working for the Forsyth Research Institute in Boston. In her time there, she researched several possible neurotoxicants but made only one study on fluoride which was published in 1995. The paper is:

Mullenix, Phyllis J., DenBesten. Pamela K., Schunior, A., & Kernan, W. J. (1995). Neurotoxicity of sodium fluoride in rats. Neurotoxicology and Teratology, 17(2), 169–177.

This paper has become central to claims made by anti-fluoride campaigners that community water fluoridation lowers IQ in children.

However, this paper is not relevant to community water fluoridation because of the very high concentrations of fluoride used (0, 75, 100, 125 and 175 mg/L in drinking water fed the rats). That such levels are unrealistic was shown by her own report that “the 175 ppm level .  .  . resulted in dehydration and the death of 10 of the exposed animals within 10 days.” Half of the 21 animals exposed died within 10 days!

For comparison, the recommended concentrations for community water fluoridation are usually less than 1 mg/L. But it is interesting that when anti-fluoride campaigners tell Mullenix’s story they rarely mention the concentration she used.

Mullenix did lose her job at Forsyth. A unanimous meeting of senior staff members on April 19, 1994, recommended she not be reappointed to her position. She was a staff associate and employment was usually guaranteed for 12 months at a time. Renewals would have depended on several factors, including the level of funding the employee was able to attract from research grants. Mullenix was informed by letter on May 31, 1994, that the Board of Trustees had approved the recommendation from senior staff members that her appointment would not be renewed.

So, she lost her job – but technically was not sacked – just not reappointed.

Why was her employment not renewed? 

Anti-fluoride campaigners rely on books like “The Fluoride Deception” to support their conspiracy theories

Depends if you believe there was a conspiracy against fluoride research.

Here are some of the conspiracy stories that are floated:

Chris Bryson says in his book The Fluoride Deception:

“PHYLLIS J. MULLENIX. A leading neurotoxicologist hired by the Forsyth Dental Center in Boston to investigate the toxicity of materials used in dentistry. In 1994 after her research indicated that fluoride was neurotoxic, she was fired.”

This claim has been repeatedly presented in articles and submissions by anti-fluoride activists. For example:

She went from being a leading neurotoxicologist at a Harvard affiliated research institute to an industry pariah. This assignment and her findings ruined her career as a grant-funded research scientist.”

Dr Phyllis J Mullenix should be a household name. She was sacked for her work proving Aluminium and Fluoride act synergistically to damage your brain and that of your unborn child.”

Within days of learning that her study was accepted for publication, Dr [Phyllis] Mullenix was fired from the Forsyth Dental Center.  She has received no grants since that time to continue her research.”

Dr Phyllis Mullenix was sacked from the Forsyth Dental Center, where she was head of the toxicology department, for publishing research in Neurotoxicology and Teratology showing that fluoride can adversely affect brain function. She had been warned: “If you publish this information, we won’t get any more grants from NIDR” (from which the institute got most of its money).

And I could go on. And on. There is no shortage of such claims promoted as arguments against community water fluoridation.

But here are some facts.

I have gone to the legal document presented to the US District Court, D, Massachusett on November 13, 1996. These relate to a case brought by Mullenix against Forsyth claiming discrimination and retaliation for her legal actions.

Mullenix’s complaint:

“alleges that Forsyth discriminated against Dr. Mullenix on the basis of her sex, denied her equal pay and one or more promotions and retaliated against her for seeking legal redress during her employment at Forsyth as a Staff Associate from 1982 to 1994.”

The document, Mullenix v. Forsyth Dental Infirmary for Children, is quite long and full of legalese which I would never pretend to understand. But it certainly makes clear that the complaint by Mullenix and the response by Forsyth have nothing to do with fluoride or fluoridation.

Fluoride is mention only a few times:

“Dr. Mullenix asseverates that no one at Forsyth ever questioned the quality of her work or that her fluoride research did not lie within Forsyth’s mission. (Docket Entry # 102, Mullenix Affidavit).”

And:

“Dr. Mullenix contends that Dr. Taubman “called Dr. Mullenix `hysterical’ because he disagreed with her research.” (Docket Entry # 102, p. 18). Dr. Mullenix recites Dr. Taubman’s alleged statement while explaining what she said to Dr. Hay during a conversation a few days after giving a seminar on fluoride research. According to Dr. Mullenix, Dr. Hay mentioned that “Marty Taubman in particular was very irate about the data that was presented …” and that “Marty Taubman had indicated that I was hysterical in my reporting.” (Docket Entry # 98, Mullenix Deposition).”

It appears Mullenix made the complaint about use of the word “hysterical” together with apparently sexist remarks made by colleagues (relating to clothing and the employment rights of women who had husbands) as evidence of a hostile and sexist work environment.

This document outlines the various complaints made by Mullenix – and clearly, they did not relate to fluoride or, directly, to her findings about fluoride. In fact, it says:

“Dr. Mullenix asserts that the only reason other than gender which explains Forsyth’s actions is that it acted in retaliation for Dr. Mullenix’ seeking legal redress.”

Mullenix took her initial legal action because she had been denied a promotion and subsequently claimed Forsyth had retaliated against her because of her initial threat of legal action if her promotion was declined (it was and she did take legal action) and then the actual legal action.

I have focused on Mullenix’s version here because they do make clear that her fluoride research and findings were not involved in any retaliation by Forsyth. The institute’s version, of course, seeks to justify their actions. While there is some reference to her research interest not coinciding strongly with the Institute’s interests, their evidence relates almost completely to salaries for male and female staff members, the responsibilities of the staff associate position that Mullenix occupied, and the extent of funding Mullenix was able to attract.

I have no idea of the legitimacy of Phyllis Mullenix’s complaints or the legitimacy of Forsyth’s rebuttals. Nor do I know what the final outcome of her legal action was.

Mullenix’s complaints could very likely have been genuine. Even today women do get discriminated against in employment and salaries. Their complaints are often disregarded or treated in a sexist way. “Uppity” women can face retaliation. And things are better now than they were in the 1980s and 1990s. It is very likely Mullenix was granted an out-of-court settlement.

But one thing I am sure of – she was not “sacked’ for her fluoride research or publication of her fluoride paper. Any complaint made by colleagues about that work would have been perfectly normal and expected – and she herself, at the time, did not attribute any retaliatory action to her fluoride research.

So, yet another case where it pays to check the claims made by anti-fluoride activists.

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Fluoridation and cancer

Yes, you have. And one lie is the claim that fluoridation causes cancer. Image credit: Have You Been Lied to About Fluoride?

We all know the phrase “Lies, damned lies, and statistics.” If nothing else, this should warn us not to take on faith arguments which rely on statistical analysis for their credibility. Wikipedia uses this phrase to illustrate the “persuasive power of numbers, particularly the use of statistics to bolster weak arguments.”

Unfortunately, the scientific literature is full of weak arguments bolstered by statistics. It’s another case of “reader beware.” Do the statistical analyses used really support the argument? And how good was the statistical analysis anyway?

Unfortunately, scientific papers with poor or inappropriate statistical analyses often get used to bolster arguments in the political field. Anti-fluoride campaigners do this all the time. I illustrated this for the “fluoridation caused ADHD” argument in my articles ADHD linked to elevation, not fluoridation and ADHD link to fluoridation claim undermined again.

Another paper often used by anti-fluoride campaigners is that of Takahasi et al., (2001). They cite this to support their “fluoridation causes cancer” argument. For example, the prominent anti-fluoride activist Karen Favazza Spencer did this recently in a Facebook post quoting from Tkahashi et al., (2001):

“Cancers of the oral cavity and pharynx, colon and rectum… were positively associated with ‘optimally’ fluoridated drinking water.”

Well, how justified is that quote? How reliable was the statistical analysis used by these authors to arrive at that claim?

Takahashi et al., (2001)

In fact, their statistical analysis was poor. They considered only fluoridation as a factor. When we consider other likely factors the statistical analyses show no significant association between these cancers and fluoridation.

Let’s have a look at the paper and the statistical analysis.

The paper is:

Takahashi, K., Akiniwa, K., & Narita, K. (2001). Regression Analysis of Cancer Rates and Water Fluoride in the USA based Incidence on IACR / IARC ( WHO ) Data ( 1978-1992 ). Journal of Epidemiology, 11(4), 170–179.

Briefly, it searched for possible statistically significant associations between the incidence rates for a whole range of cancers and the extent of fluoridation. It used fluoridation extent and cancer incidence data for three US states and six US cities. Other factors were considered only for lip cancer where sunshine extent was included in the analyses.

I set out to repeat their statistical analysis, including some other relevant factors. However, the data they used for cancer incidence in 1978-1992 is not available on-line. But there are data sets available for more recent years.

Here I use the cancer incidence data for 1993-1997 taken from the WHO, International Agency for Research on Cancer publication Cancer Incidence in Five Continents Vol. VIIIThis lists cancer incidence for 58 body sites but I restricted my analysis to eight of the body sites for which Takahashi et al., (2001) reported significant associations with fluoridation.

Are any of these cancers significantly associated with the extent of fluoridation?

Well, yes, two are at the 5% level (p < 0.05) – cancers of the rectum and bladder. The table lists values for the probability p value produced by linear regressions. The p values for cancers at all the body sites considered is also significant – but only for females.

Cancer site p – Male p – Female
Lip 0.750 0.825
Oesophagus 0.427 0.285
Colon 0.090 0.146
Rectum 0.037* 0.048*
Bone 0.784 0.147
Prostate 0.639
Bladder 0.015* 0.031*
Thyroid 0.806 0.519
All sites 0.250 0.020*

Takahashi et al., (2001) found significant associations for rectum and bladder. But also for Colon, bone (male), oesophagus (female), prostate (male) and lip. This difference is not too surprising as I used a different, more recent, data set. Also, correlations do not mean causation, they can occur by chance (1 in 20 samples) and other factors are more than likely involved (see below).

Another difference is that I used simple linear regressions. Takahashi et al., (2001) transformed both fluoridation extent and cancer incidence to logarithms but their explanation for this is inadequate.  Such transformations are not normally applied unless there is evidence that a relationship is nonlinear.  Takahashi et al., (2001) did not give any evidence for this and there was no evidence for it in the data set I used.  Neither was there any evidence of patterns in the residual values from the regression analysis – another sign that simple linear regression was valid.

What about the influence of other factors?

One of the biggest complaints I have about the use of regression analysis in studies like this is that very often other factors are ignored. Takahashi et al., (2001) considered only sun shine extent – and then only for lip cancer.

I think the restriction to consideration of only fluoridation is naive. In fact, probably indicating a bias and a desire to confirm it. It is extremely unlikely that all, or even most, of the specific cancers considered have a single cause – fluoride. And it is unlikely that a single factor would explain all the variability in the cancer incidence data.

Also, fluoride could be acting as a proxy for more relevant factors. The ADHD relationship with the extent of fluoridation is an example. In my paper Attention deficit hyperactivity disorder prevalence associated with altitude but not exposure to fluoridated water*, I showed that fluoridation extent is significantly correlated with mean altitude. When altitude was included in a multiple regression there was no significant association of ADHD with fluoridation.  This suggests that, in fact, the fluoridation data was really a proxy for something else – in this case, altitude – which Huber et al (2015) reported is associated with ADHD prevalence.

I am not intending here to narrow down the most likely factors which are associated with cancer at all these body sites. I simply want to check how significant any association with fluoridation is when other possible factors are included.

Geographic factors are worth considering – not because they necessarily have a direct influence. But because they may act as proxies from environmental, population density and industrial concentration factors which could be important. So I included data for mean elevation, mean latitude and mean longitude together with the extent of fluoridation in multiple regressions of the eight cancers above as well as for all the body sites data.

Using adjusted R square values to test for a fluoridation contribution

Rather than attempting to identify significant correlations with different factors for different cancers, I used the method of judging what effect inclusion of fluoridation extent had on the explanatory power of regression models which included the geographic factors. Jim Frost describes this approach in his article Multiple Regression Analysis: Use Adjusted R-Squared and Predicted R-Squared to Include the Correct Number of Variables

Briefly, he describes problems with the R squared value:

“Every time you add a predictor to a model, the R-squared increases, even if due to chance alone. It never decreases. Consequently, a model with more terms may appear to have a better fit simply because it has more terms.”

Include more factors and you could simply be modelling random noise in the data.But the adjusted R-squared  overcomes this because it adjusts for the number of predictors in a model:

“The adjusted R-squared increases only if the new term improves the model more than would be expected by chance. It decreases when a predictor improves the model by less than expected by chance. The adjusted R-squared can be negative, but it’s usually not.  It is always lower than the R-squared.”

These examples below of multiple regression output including fluoridation and excluding fluoridation in the models illustrate where adjusted R square values are reported:

The table below lists the adjusted R square values for multiple regressions:

  • +Fl included fluoridation extent, mean elevation, mean latitude and mean longitude, and
  • -F included only mean elevation, mean latitude and mean longitude.

Comparing the adjusted R square values for +Fl and -Fl tells us about the effect of including fluoridation extent on the models:

  • Where the value for +Fl is larger than for -F then the extent of fluoridation improves to model more than would be expected by chance.
  •  Where the value of +Fl is smaller than for -F then the extent of fluoridation improves to model less than would be expected by chance.

Male

Female

Cancer site + Fl – Fl + Fl – Fl
Lip 0.170 0.242 0.685 0.649
Oesophagus 0.809 0.842 0.558 0.612
Colon 0.842 0.771 0.681 0.659
Rectum 0.357 0.455 0.616 0.692
Bone 0.451 0.527 0.625 0.700
Prostate -0.350 0.130
Bladder 0.860 0.863 0.530 0.606
Thyroid 0.434 0.544 0.801 0.824
All sites 0.622 0.676 0.846 0.865

The table shows that adjusted R square values are greater (red) when fluoridation extent is not included in the regression model for all cancer sites except the colon and female lip. That indicates that these cancers are not associated with fluoridation extent. That the simple regression results alone  for fluoridation extent in the case of rectum and bladder cancer (and all sites female cancer) are misleading.

The colon and female lip cancer are exceptions – but the fact no significant association was found for fluoridation extent alone (first table) suggests something more complex is occurring here. It could be that the selected geographic factors have very little role in these cancers and inclusion of more relevant factors is needed.

Conclusion

The associations of fluoridation extent with various cancers reported by Takahashi et al., (2001) disappear when we consider other more relevant factors. Therefore, the use of this study by anti-fluoride campaigners to claim fluoridation is responsible for cancer is misleading. Not that I expect, from their past record, they will stop doing this.

More generally this is yet another example showing that readers should beware of putting too much faith in simple statistical analyses reported in scientific papers – even those published in respectable journals. It is just too easy to use statistical analysis to confirm a bias.

We should all keep in mind the phrase  “Lies, damned lies, and statistics” and treat such reports critically. If possibly checking out the extent to which other factors have been considered. Even where significant correlations are reported we should check how useful such correlations are at explaining the variations in the data.


*The full text of this paper is not yet available as it is undergoing journal peer review. However, the full text of CRITIQUE OF A RISK ANALYSIS AIMED AT ESTABLISHING A SAFE DAILY DOSE OF FLUORIDE FOR CHILDREN, the first draft from which this paper was taken, is available.

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Local anti-fluoride activists tell porkies yet again

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

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

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

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

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

Here are those studies:

New Zealand

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

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

Sweden

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

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

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

Canada

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

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

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

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

Animal studies

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

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

But they omit the next sentence from the quote:

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

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

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

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

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

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

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Don’t rely on sources – follow the evidence

CNN pushes this mantra but many believe they promote fake news

When scientists evaluate published research we are more interested in evidence than in conclusions. In fact, the same evidence may lead scientific readers to different conclusions. That’s not surprising as in the real world no research project is able to consider all the theoretically possible evidence. Readers may, in fact, have other evidence. Or they may detect faults in authors’ interpretations.

I think this is a good thing. Considering the evidence allows competent critiques to be made and encourages knowledge to advance.

However, it annoys me that when we move outside the scientific environment we have to deal with situations where evidence may rarely be considered. People indulge in debating conclusions often with no regard to evidence. In fact, debaters seem to rely more on the real or perceived authority of their sources to support or discredit an argument, than on the evidence.

That’s just lazy. Source authority proves nothing and I would like to think that my discussion partners are capable of coming to a more reasonable position when they are forced to actually consider the evidence.

Both sides are guilty

Unfortunately, both supporters and opponents of a scientific viewpoint or consensus fall into this trap. Take the “fluoridation debate.” It annoys me that some supporters of the scientific viewpoint will respond to an opponent by disparaging their sources. The fact that the opponent is citing the activist Fluoride Action Network, the “Fluoride” journal or one of the shonky pay-to-publish journals where anti-fluoride activists sometimes get published does not, in itself, discredit their argument. On the other hand, if the actual evidence involved in those reports were discussed it might just be possible for the faulty conclusions to be exposed.

On the other hand, how often have I heard opponents of community water fluoridation reject the authority of scientific journals or published research because the workers were paid by the government (we must all get a wage from somewhere) or the journal or conference received industry sponsorship? I am not at all impressed by the refusal to consider the real evidence implied by falling back on disparaging sources.

The other tactic of supporting a claim by pointing to the high authority of the source is also repugnant. Even researchers and journals we generally consider “reputable” can still publish flawed work and even rubbish.

One of the most common arguments used by anti-fluoride campaigners is that the highly respectable, authoritative journal “The Lancent” has “officially” declared fluoride to be a “neurotoxin.” This is wrong on so many counts. The Lancet publishes research papers. It is not in the business of making official declarations on toxic compounds. The paper referred to did not describe fluoride as a “neurotoxin” – that word is inappropriate for describing a chemical of inorganic origin. The work cited in that paper was from areas of endemic fluorosis mainly in China and is not relevant to community water fluoridation. And the paper itself was not justified in making the limited conclusions it did on such poor evidence. I have discussed the paper more fully in Repeating bad science on fluoride.

The odds are, of course, that those activists citing this paper in such a manner have not actually read the paper – a common problem with people who rely on the authority of their sources rather than evidence. In fact, they are probably not at all interested in the details in most cases.

My point is reliance on authority is not a valid supporting argument any more than disparaging a source is a valid opposing argument. We should always follow the evidence – and rely on that evidence for our arguments in such discussions.

The political arena

This problem is even worse in the political sphere where so often we actually do not have evidence to fall back on. In fact, this situation seems to have got a lot worse of late where, for one reason or another, facts and evidence seem to be the last thing in the minds of “reporters” – or at least those who are continually telling us what we should think.

Unfortunately, discussion of political issues often leads people to claim they are using what they think as “reliable sources” or disparaging an opponent’s argument by claiming they are using “unreliable sources.” In fact, people who should know better, seem to often support their claims against any criticism by claiming it came from a “reliable source” or “authoritative source.” And these people who should know better will often resort to “attacking the messenger.” Criticising or rejecting information because it was reported by what they consider an “unreliable source.” The facts or evidence seem to be forgotten.

This can get pretty silly. I once had to confront the argument of a discussion partner who rejected the video recording of a statement made by a spokesperson for the US Department of State because it was part of a piece of RT news coverage! Especially silly as the video recording was probably an official one made by staff of the Department of State.

How often do we see people promoting partisan claims about the political hysteria in the US or the war in Syria by using sources like the Washington Post, New York Times, CNN or Al-Jazeera? Sources they claim are “reliable?” In my article  I described how the New Zealand Ministry’s of Foreign Affairs and Internal Affairs carried out “due diligence” on the White Helmets organisation they were planning to give money to by referring simply to a report from Al-Jazeera. No attempt to dig deeper, to evaluate the veracity of the Al-Jazeera reports or to follow-up other sources critical of the White Helmets. Yet Al-Jazeera has a reputation for supporting “rebels”/”terrorists” in Syria. It is shocking that a New Zealand ministry was not prepared to make a more sensible judgment.

On the other hand, how often do we see people disparaging information or claims about the current US political hysteria or the war in Syria which with they disagree because it was reported by Sputnik, RT or one of a host of other “alternative” news sources?

Both sides of a political argument now denigrate the sources used by the other side as promoting “fake news.” And, to an extent, each side is probably right as every news sources these days has its own point of view – its own bias.

Reader beware – use a range of sources

Unfortunately, many readers seem more interested in confirming their own biases than dealing with real facts or evidence. Understandably these people will select the news source that suits them. That’s OK if you simply want to follow the “party line.” But it is lazy because it avoids any intelligent or critical analysis.

It is incumbent on the rest of us who are more interested in real facts and in drawing more credible conclusions to make an effort to consult a range of news sources and to critically analyse the claims, opinions and information we get from them. I believe that in today’s world there is no such thing as an authoritative or reliable source when it comes to political information. All the media – the “established mainstream media” as well as the “alternative media” are equally capable of publishing and promoting fake news.

We need to be aware of this, be prepared to use a variety of sources to avoid the “party line” problem, and critically analyse what we read so we can separate facts from opinions and unsubstantiated claims.

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Darwin, sexual selection and Putin

Credit: RussiaFeed.

Must edge my way back in into blogging after a period of mourning. So here is something provocative.

Perhaps President Putin is “making Russia great again” in a way we haven’t thought of. Via Darwinian sexual selection?

If this song is anything to go by maybe Putin as a role model will lead to improvement in the Russian gene pool if women start preferring men with his moral and lifestyle characteristics.

Or perhaps his influence will operate more quickly by encouraging Russian men to smarten themselves up if they want to find a partner?

Is this yet another positive influence Putin has had on Russian life after the disastrous experiences of the criminal anarchy of the 1990s?

Or is it a sign that Putin has finally decided to run in next March’s Russian Presidential elections and this is his first campaign song?

Whatever – it’s a welcome (and tuneful) change from the usual demonisation of the man we get from our mainstream media. (And I expect to get from commenters here).

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