Category Archives: Health and Medicine

The distrust of science – a task for science communication

Michael Foley

Michael Foley, a Senior Lecturer in Public health dentistry at The University of Queensland has an interesting  article in The Conversation* – ‘Holistic’ dentistry: more poppycock than panacea?

He declares that “all dentists should be practicing holistic medicine.” After all, the World health Organisation’s definition of health (“a complete state of physical, mental and social well-being, and not merely the absence of disease or infirmity”) “sits very well with the concept of holistic dentistry”

But, as Foley says, dentists “should all be practising evidence-based dentistry, too.”

And there is the problem. A perfectly legitimate term has been hijacked in an effort to misinform possible clients. An internet search shows most Australian holistic dentists also endorse and encourage alternative therapies like:

homeopathy, naturopathy, Bach flower essences, acupuncture, traditional Chinese medicine, chiropractic, ayurvedic medicine, osteopathy, kinesiology, crystals, aromatherapy, reiki, vibrational healing, Buteyko and esoteric chakra-puncture.”

As he says, despite  his belief that “Most holistic dental practices will provide a wonderfully caring and nurturing environment for patients .. . . a patient-dentist relationship must also be based on trust and professionalism.”

The placebo effect is not enough and reliance on it could even be dangerous.

But alternative health practices like this do have a market – and for some people their appeal lies with their distrust of science.

Distrust of science and the power of consensus

Sander van der Linden and Stephan Lewandowsky discuss this distrust and how to combat it in a recent scientific American article – How to Combat Distrust of Science.

They centre their argument around the issue of climate science, but I think they are also relevant to alternative health and the distrust of health experts common in our society.

On the one hand they attribute difference in the acceptance of science to the way that people interpret the same information very differently.

“As psychologists, we are more than familiar with the finding that our brains selectively attend to, process and recall information. One consequence of this is “confirmation bias,” a strong tendency to automatically favor information that supports our prior expectations. When we consider issues that we feel strongly about (e.g., global warming), confirmation bias reaches a new height: it transitions into “motivated reasoning.” Motivated reasoning is the additional tendency to defensively reject information that contradicts deeply held worldviews and opinions. One example of this is the “motivated rejection of science”; if you are personally convinced that global warming is a hoax, you are likely to reject any scientific information to the contrary – regardless of its accuracy.”

A message for science communicators

That is an argument which could suggest that science communicators are “just blowing in the wind.”

On the other hand the authors argue that “expert consensus” can counter this.

“Our research shows that highlighting how many experts agree on a controversial issue has a far-reaching psychological influence. In particular, it has the surprising ability to “neutralize” polarizing worldviews and can lead to greater science acceptance.”

In their work they found that if people had been exposed to background material containing the message “97% of climate scientists have concluded that human-caused climate change is happening” they actually increased their estimate of scientific support for human-caused climate change by about 13% (and 20% in some cases). In later work they found a causal link between highlighting expert consensus and increased science acceptance.

This suggests to me that many people may take up an essentially anti-science stance because they are just unaware of the facts of consensus, or are under the illusion that scientific dissent is greater than the objective facts show.

I see that as a positive message. We often concentrate on the anti-science position of ideologically motivated people and forget that the majority are probably misinformed – both about the science and the degree of expert consensus. It is this majority, rather than the ideologically motivated science distrusters, who science communicators need to target.

Are we biologically wired to accept consensus?

The authors suggest there are good biological reasons for the positive effect of consensus information and the negative effect of dissent information on the acceptance of science.

“One feature that clearly distinguishes “consensus” from other types of information is its normative nature. That is, consensus is a powerful descriptive social fact: it tells us about the number of people who agree on important issues (i.e., the norm within a community). Humans evolved living in social groups and much psychological researchhas shown that people are particularly receptive to social information. Indeed, consensus decision-making is widespread in human and non-human animals. Because decision-strategies that require widespread agreement lie at the very basis of the evolution of human cooperation, people may be biologically wired to pay attention to consensus-data.”

That is also sensible:

” Imagine reading a road sign that informs you that 97% of engineers have concluded that the bridge in front of you is unsafe to cross. You would likely base your decision to cross or avoid that bridge on the expert consensus, irrespective of your personal convictions. Few people would get out of their car and spend the rest of the afternoon personally assessing the structural condition of the bridge (even if you were an expert).”

And practical:

” it makes perfect sense for people to use expert consensus as a decision-heuristic to guide their beliefs and behavior. Society has evolved to a point where we routinely defer to others for advice—from our family doctors to car mechanics; we rely on experts to keep our lives safe and productive. Most of us are constrained by limited time and resources and reliance on consensus efficiently reduces the cost of individual learning.”

The message, then, is:

“A recent study showed that people are more likely to cling onto their personal ideologies in the absence of “facts.” This suggests that in order to increase acceptance of science, we need more “facts.” We agree but suggest that this is particularly true for an underleveraged but psychologically powerful type of fact — expert consensus.”

The “merchants of doubt”

The ideologically and commercially motivated opponents of science recognise this – hence their attempts to sow doubt on the scientific consensus.

They will promote the message that there is no consensus. Or that the very fact of a consensus is somehow a “proof” the science is wrong because scientific understanding will change in the future (the Galileo gambit – see The Galileo fallacy and denigration of scientific consensus).

They will promote the message that the experts are frauds (eg Climategate) “shills” – in the pay of political or economic forces – Big Pharma, the fertiliser industry in the case of fluoridation, etc. Ironic, really, because these very anti-science propagandists are often themselves supported and/or financed by energy companies (in the case of climate change deniers) and “natural”/alternative health big business in the case of anti-fluoridation and anti-vaccination activists

So, perhaps another task for science communicators. propaganda claiming scientific fraud, unethical scientific funding, etc., needs to be countered. But also the public needs to be made aware of the commercial and ideological motivations of those who attempt to misrepresent the science and the expert consensus.


* The conversation has some excellent articles. But Christopher Pyne in his article Government funding for The Conversation website to be axed, reveals that government funding for it is to be stopped.

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Poor peer review – and its consequences

peer-review-diagram

See below for citations used

The diagram above displays links between the journal, editors and reviewers in the case of the paper Malin & Till (2015). I discussed these links before in Poor peer-review – a case study  but thought a diagram merited a separate post. “A picture is worth a thousand words,” they say.Unfortunately, I suspect, such incestuous arrangements around

Unfortunately, I suspect, such incestuous arrangements around the publication of a scientific paper is probably not too unusual. I guess it is human nature for authors to choose a journal which might be sympathetic (or biased) towards their ideas. In this case, the journal and its editors clearly have an orientation towards chemical toxicity hypotheses. The journal even allows authors to suggest possible referees. So again it is only human nature for the authors to suggest referees they consider sympathetic. Or perhaps it is only human nature for Grandjean or Bellinger to suggest referees they know are sympathetic to their own chemical toxicity hypotheses.

Human nature – but certainly not in the best interests of science – or the best outcome for the paper. The authors could have suggested at least some referees with experience in the field of attention deficit hyperactivity disorder (ADHD). And the editors could have done the same. This way they could have produced a better outcome – proper revision of the paper to consider other factors besides chemical toxicity. Or even the withdrawal of the paper itself once everyone realised that their fluoride toxicity hypothesis didn’t stand up to proper testing.

Just imagine if referees like the seven authors of Huber et al (2015) had been considered. I discussed their paper in ADHD link to fluoridation claim undermined again. It considered the same ADHD data as Malin & Till (2015) but found other, non-chemical factors, were implicated. In particular they found a correlation with altitude.  If a referee of the Malin & Till (2015) paper had suggested they consider factors like altitude the Malin & Till (2015) may never have seen the light of day. It would have, at least, been heavily modified.

And we would not have anti-fluoride activists and “natural”/alternative health web pages and magazines promoting the myth that community water fluoridation causes ADHD.

Similar articles

Choi, A. L., Sun, G., Zhang, Y., & Grandjean, P. (2012). Developmental fluoride neurotoxicity: A systematic review and meta-analysis. Environmental Health Perspectives, 120(10), 1362–1368.

Choi, A. L., Zhang, Y., Sun, G., Bellinger, D., Wang, K., Yang, X. J., … Grandjean, P. (2015). Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Neurotoxicology and Teratology, 47, 96–101.

Grandjean, P., & Landrigan, P. J. (2014). Neurobehavioural effects of developmental toxicity. Lancet Neurol, 13(March), 330–338.

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.

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.

 

Connett fiddles the data on fluoride

I am always suspicious when activists present simple figures to confirm their bias and fool their audience. I think anti-fluoride activists do this a lot. Here is an example in Paul Connett’s presentation to the recent Sydney anti-fluoride conference.

Connett uses data from Xiang et al (2003) and some of Xiang’s other papers and presentation to push his claim that fluoridation is bad for your IQ. Apparently he and Bill Hirzy (currently described as Fluoride Action Networks “chemist in residence”) are working on a paper attempting to justify a case that the maximum permissible level of fluoride in drinking water should be reduced to practically zero! They use a simplification of data from Xiang’s paper for this.

Xiang-2003

First of all the figure shows what Xiang’s data is like. It compares IQ with urine fluoride concentration – unfortunately he did not give a similar figure for fluoride concentration in drinking water. However, this is well correlated with urine fluoride.

There is certainly a lot of scatter, but Xiang (2003) reports a “Pearson correlation coefficient of 0.174, p=0.003.” So a statistically significant relationship (helped by having a large number of samples) but it still only explains about 3% of the variance!

This is important because, although Xiang did consider some confounding factors he could well have missed a factor which explains more of the variance which, when considered, may make the relationship with serum fluoride concentration non-significant. For example, I would be interested to see a statistical analysis which included incidence of moderate and severe dental fluorosis as this may be more important than the drinking water fluoride concentration itself).

Connett-sydneyBut have a look at how Paul Connett present this data (or the equivalent data for drinking water fluoride concentration) in his Sydney anti-fluoride conference presentation.

The “trick” has been to divide the data into “categories” based on inclusion in a separate water fluoride concentration ranges and then presenting only the averages within each category. I can see the point of sometimes using such categories, but this figure conveys a very misleading message.

The Sydney audience could have been excused for thinking that Xiang’s data showed a very strong connection between IQ and drinking water fluoride – a relationship explaining almost all the variance. Completely misleading as this relationship probably only explains only about 3% of the variance in the original data.

Paul Connett and William Hirzy are currently campaigning to make IQ the key factor for determining the maximum permissible levels of fluoride in drinking water. They might confuse a few politicians with these sort of distortions but hopefully the real decision-makers will be awake to such tricks.It really is

It really is a matter of “the reader beware.” Never take on trust what these political activists are saying. Always go to the original sources and consider them critically and intelligently.

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ADHD link to fluoridation claim undermined again

Recently I suggested that Attention Deficit Hyperactivity Disorder (ADHD) was better correlated with elevation than with community water fluoridation (see ADHD linked to elevation not fluoridation). I criticised the study of Malin and Till (2015) for limiting their investigation to a chemical toxicity hypothesis and pointed out that once confounding factors like elevation are included their reported relationship between ADHD and community water fluoridation (CWF) disappears.

Seems I am not the only one to notice this. A new paper reports that same relationship:

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.

They used data sets for the prevalence of ADHD in 2007 and 2010 in US states and found a negative relationship with average state elevation. Their correlation coefficients (R 2 = .38, p < .001; R 2 = .31, p < .001 respectively) are similar to the one I found.

This paper effectively supports my earlier conclusion:

“I do not think Malin and Till (2015) are justified in drawing the conclusion that CWF influences ADHD. Their mistaken conclusion has arisen from their limited choice of data considered for the exploratory analysis. That in itself seems to have resulted from a bias inherent in their hypothesis that “fluoride is a widespread neurotoxin.”

I was not advancing an alternative hypothesis but Huber et al., (2015) did suggest the hypothesis:

“As decreased dopamine (DA) activity has been reported with ADHD and hypoxia has shown to be associated with increased DA, we hypothesized that states at higher altitudes would have lower rates of ADHD.”

But the important lesson is once factors like elevation are taken into account there is no statistically significant relationship with CWF. The Malin & Till (2015) paper currently heavily promoted by anti-fluoride propagandists is flawed.

See alsoRates of ADHD appear to decrease at higher altitudes

 Similar articles

Commercial and ideological support of anti-fluoride activity

Fluoride Free NZ (FFNZ) promotes a list of “NZ Health Professionals who are calling for an end to fluoridation.” I am generally cynical about such endorsement lists, but the details in this list do give a picture of the commercial and ideological alignment of the FFNZ supporters and activists. So I did my own analysis, dividing the list into those described as “Science and Environmental PhD Professionals”, “NZ Dentists, “NZ Doctors” and Alternative health professionals (Chiropractors, naturopaths, Homeopaths, etc.). Of course, this is approximate as, for example, some listed as doctors may have specialised in one or another alternative fields. The pie chart below shows the distribution of FFNZ supporters among these groups. Clearly with such a large proportion of supporters coming from alternative health fields this above distribution is not representative of professionals in general, let alone health professionals. However, anyone who has looked at the anti-fluoride movement or debated with anti-fluoride activists would not be surprised as “natural”/alternative health arguments and sources are frequently used. I wonder, though, to what extent local body councillors are aware of this commercial and ideological orientation when considering submissions they get on the fluoridation issue. I suspect they aren’t. Yet groups like FFNZ engineer these submissions from their supporters – often providing templates for individuals to sign – and usually dominate the submission process. Personally I think this is a defect in our system of representative democracy – councils should actually insist on declarations of conflict of interest, details of employment and commercial interests from submitters. Their failure to do this explains how some local bodies, like the Hamilton City Council, have unwittingly been captured by ideological and commercial interests from the “natural”/alternative health industry during such submission processes.

Financial links

Declaration of conflicts of interest and details of employment, etc., may to some extent help identify big business interests financing this sort of submission in future. At the moment, we are largely left to speculate. However, there are financial data available showing the money trail involved in at least one anti-fluoride campaign – the High Court case against  the South Taranaki District Council aiming for a judicial review of a decision to fluoridate water supplies in Patea and Waverley (see Who is funding anti-fluoridation High Court action? and Corporate backers of anti-fluoride movement lose in NZ High Court). This action was taken by New Health NZ – an incorporated body set up by the NZ Health Trust – In November 2013. Statements of financial performance of these two organisations are available online and show the following movements of large amounts of money during the year to March 2014. NZHT As the NZ health Trust is a lobby group for the “natural”/alternative health industry the grants it receives must come out of the profits of this industry which is actually a big business in New Zealand. Although the financial statements do not identify sources and recipients the $100,00 grant to New Health NZ clearly came from its parent body and is included in their declared $125,ooo grants and donations. The $95,156 paid out by New Health NZ in professional and consulting fees would have covered the costs involved in their High Court action. So this is a clear example of pretty direct funding of anti-fluoride activity (the High Court action) by corporate interests – the “natural”/alternative health industry. But none of the reporting of this High Court action identified the commercial interests involved. Readers were given the impression that New Health NZ was just another one of these anti-fluoride activist groups and possibly assumed funds for the legal action came from donations. Again, this is a flaw in our representative democratic system. There should be more transparency of financial links. Corporate interests should be able to hide behind astroturf organisations and the dishonesty that their actions are the result of concerned citizens and not the ideological and commercial interests of big business. Similar articles

Is comfirmation bias essential to anti-fluoride “research?”

Anti-fluoride propagandists like Declan Waugh and Paul Connett avidly scan the scientific literature looking for anything they can present as evidence for harmful effects of community water fluoridation (CWF). Sometimes they will even do their own “research”  using published and on-line health data looking for any correlations with CWF, or even just with fluoride levels in drinking water.

Several years ago an activist going under the nom de plume “Fugio” posted images showing correlations of mental retardation, adult tooth loss and ADHD with the incidence of CWF in the US. These images are simply the result of “research” driven by confirmation bias and data dredging.They prove nothing. Correlation is not proof of a cause. And no effort was made to see if other factors could give better correlations.

I go through Fugio’s examples below – partly because I noticed one of their images surfacing recently on an anti-fluoridation Facebook page as “proof” that CWF causes tooth loss. But also because they are just more examples of the type of limited exploratory analysis used in two recently published papers – Peckham et al., (2015) (discussed in my article Paper claiming water fluoridation linked to hypothyroidism slammed by experts) and Malin and Till (2015) (discussed in my articles More poor-quality research promoted by anti-fluoride activistsADHD linked to elevation not fluoridation and Poor peer-review – a case study).

ADHD

This figure is essentially the same as that reported by Malin & Till (2015). In fact, I wonder if Fugio (who posted December 2012) is the unattributed source of Malin & Till’s hypothesis. Fugio chose the ADHD data for 2007 and fluoridation data for 2006 whereas Malin and Till (2015) concentrated mainly on fluoridation data for 1992 which had the highest correlation with ADHD figures.

I won’t discuss this further here – my earlier article ADHD linked to elevation not fluoridation shows there are a number of other factors which correlate with ADHD prevalence just as well or better than CWF incidence does and should have at least been considered as confounding if not the main factors. I found a model using mean elevation, home ownership and poverty only (no CWF included) explained about 48% of the variation whereas their model using CWF and mean income explained only 22-31% of the variation. And when these confounder factors were considered the correlation of ADHD with CWF was not statistically significant.

In other words we could do a far better job of predicting ADHD prevalence without involving CWF.

Water Fluoridation and Adult Tooth Loss

Fugio posted a figure showing a correlation of adult tooth loss with CWF incidence in 2008. It was statistically significant explaining 11% of the variation. But quite a few other factors display better correlations with adult tooth loss. For example, the data for smoking by itself explains 66% of the variation (see figures below).

Teeth-smoke

Checking out correlations with a range of factors I found a model involving only smoking and longitude  explaining  about 74% of the variation. The contribution from CWF was not significant statistically – it added nothing to this model.

Water Fluoridation and Mental Retardation

Fugio found a better relationship between CWF in 1992 and mental retardation in 1993 – a correlation explaining 19% of the variation. Apparently the concept of “mental retardation” was later abandoned as there do not appear to be any more recent statistics.

But again, if Fugio had not stopped there he/she would have found a number of other factors with better correlations. I give an example in the figure where state educational level (% Bachelors Degree in 1993) explained 50% if the variation. This correlation is negative as we might expect.

mental

 Again I used multiple regression analysis to derive a model involving educational level (% with Bachelors degree in 1993), poverty in 1993 and mean state elevation which explained 69% of the variation. No statistically significant contribution from CWF occurred.

Conclusions

I am not suggesting here that the factors I identified have a causal effect. Simply that they give better correlations  than CWF. These and similar confounding factors should have been considered by Fugio and Malin and Till (2015).

My purpose is to show that this sort of exploratory analysis of easily available data can easily produce results for anti-fluoride activists who are searching for some “sciency” looking arguments to back up  their position. Provided they don’t look too deeply, stop while they are ahead and refuse to consider the influence of other factors.

Unfortunately poor peer review by some journals is allowing publication of work that is no better than this. Peckham et al (2015) did nothing to check out other factors except gender in their correlations of hypothyroidism with CWF. The glaring omission was of course dietary iodine which is known to have a causative link with hypothyroidism. (I could not find US data for hypothyroidism so was unable to check out Peckham et al’s hypothesis for the US.) Malin and Till (2015) included only socioeconomic status (as indicated by income) in their analysis despite the fact that ADHD is known to be related to a number of factors like smoking and alcohol intake.

As I keep saying, when it comes to understanding the scientific literature it really is a matter of “reader beware.” It’s easy to find papers supporting one’s pet obsession if you are not critical and sensible with your literature searches. And it is important not to take at face value the claims of activists who clearly rely on confirmation bias when they explore the literature.

IQ not influenced by water fluoridation

That is what the US data for average state IQ and percent water fluoridation tells us.

I thought I would check out the US IQ and fluoridation data for each state after reading Malin and Till (2015). That paper compared the prevalence of ADHD by state with the percent fluoridation in each state. There are problems with the paper (see ADHD linked to elevation not fluoridation and Poor peer-review – a case study) but what is good for the goose is good for the gander. How do the corresponding statistics for IQ compare?

IQ data for US states are not readily available but I managed to find a data set of IQ estimates by state in 2000 based on Scholastic Aptitude Test scores. The correlation of these average IQ scores with water fluoridation (1992) is not at all significant statistically. The slope of the trend line in the plot below is not significantly different to zero (-0.04 to +0.01 at the 95% confidence level as represented by the dashed lines).

fl-IQ

This lack of correlation is not at all surprising. After all, the only published study to compare IQ and community water fluoridation (CWF) is that of Broadbent et al., (2014)  – they also did not find any statistically signficant relationship.

So what are the anti-fluoride propagandists on about?

They do not rely on studies involving CWF but instead claim support in studies from areas where fluorosis due to excess fluoride is endemic – eg Choi et al., (2012). These and similar studies have reported a correlation of IQ with drinking water fluoride- but there are 2 problems:

  1. Very little was done in these studies to consider confounding factors. There is the possibility that inclusion of these confounding factors in correlations would show that fluoride does not make a statistically signficant contribution to IQ changes.
  2. Generally the authors have assumed a chemical toxicity explanation without any real justification. The data can be explained by other mechanisms such as the influence of the disfiguring effect of severe dental fluorosis on quality of life and learning (Perrott, 2015). In the few cases where data for severe dental fluorosis was included its relationship with IQ is statistically significant (eg Choi et al., 2015) (see Severe dental fluorosis the real cause of IQ deficits?). Severe dental fluorosis is not a problem in areas where CWF is used.

There is no need to consider confounding factors for the correction in the above figure as CWF does not explain any of the variation in IQ. But I did find statistically significant relationship for IQ with a number of factors. The plots below show the data for premature births in 1990-1991 and average percent poverty in 2002-2004.  These correlations by themselves explain 50 and 63% of the variation in IQ. Combined they explain 69% of the variation.

prem-pov

The percentage of CWF in each state explains none of the variation.

It would be more rational for those concerned about CWF to get active on issues related to poverty and premature births.

The community water fluoridation issue is a dead duck as far as IQ is concerned.

Similar articles

Poor peer-review – a case study

daigram

“Peer-review” status is often used to endorse scientific papers cherry-picked because they support a bias.

Many scientists are not impressed with the peer-review processes scientific journals use. Like democracy, this peer-review is better than all the available alternatives but it certainly doesn’t guarantee published scientific papers are problem-free.

Sure, peer-reviewed sources are better than others which have no quality control. But it is still a matter of “customer beware.” The intelligent users of scientific literature must do their own filtering – make their own critical judgements of the likely reliability of reported scientific findings.

Despite this people often use the “peer-reviewed” description to endorse published finding (especially if they confirm their own biases) without any critical assessment. This happens a lot in on-line debates of “controversial” issues.

Here I will go through the details of peer-review of a recently published paper which anti-fluoride activists are endorsing and promoting, but others are critcising. The paper is:

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.

I have discussed this paper in recent posts (see More poor-quality research promoted by anti-fluoride activists and ADHD linked to elevation not fluoridation). The journal, Environmental Health, has a transparent peer-review process which provides access to the names and reports of the reviewers. This reveals problems with the review process in this case. Below I discuss the responsibility of the authors, reviewers and the journal for the problems with this paper and its reported findings.

Authors’ responsibilities

The authors are clearly committed to a pet theory that fluoride is a neurotoxicant which could contribute to ADHD prevalence. Nothing wrong with that – we all feel committed to our hypotheses. We wouldn’t be human if we didn’t. But the best way to produce evidence for a hypothesis is to test it in a way that could prove it wrong.

In this case the authors found a correlation between ADHD prevalence in US states and the amount of community water fluoridation in each state. Trouble is, one can find just as good a correlation, or even a better correlation, with many other criteria for which state prevalence statistics are available. I listed a few in  ADHD linked to elevation not fluoridation. Some of these factors are also correlated with community water fluoridation suggesting the correlation reported by Malin and Till (2015) may be deceptive.

A proper test of the fluoridation hypothesis would include considering the effect of including such confounders together with fluoridation in their statistical analysis. Malin and Till (2015) did include one other criteria – the median household income for 1992 – but did not include any others. I find this surprising because they acknowledged ADHD results from interaction of genetic and environmental factors. While fluoridation is not usually considered a relevant factor things like smoking and premature births are and there is conflicting evidence about the role of economic factors like poverty and income.

In my article  ADHD linked to elevation not fluoridation I showed ADHD prevalence is better explained by a few of these factors without any input from water fluoridation.

I can’t help feeling the limited consideration of confounding factors results from a desire to protect the fluoridation hypothesis and therefore not test it properly.

Reviewers responsibilities

Again, such a desire is only human. But reviewers should have picked this up during their own considerations.

Interestingly, only one of the two reviewers raised possibility other confounders – specifically lead levels. This is of course valid as lead is a recognised neurotoxicant – but why did none of the reviewers question why other factors like smoking, premature births and social or regional factors were not considered?

I believe that is because both reviewers had research interests directed at chemical toxicity and not ADHD or similar mental characteristics. A matter of someone with a hammer only seeing nails.

The reviewers and their research interests are:
Marc Weisskopf whose reviews are available here and here.

“Some examples of my current work are exploring how exposure to, e.g., lead, manganese, and air pollution affect cognitive function and psychiatric symptoms; how exposure to Agent Orange and other herbicides used in Vietnam relate to the development of PD; and how formaldehyde and lead exposure relate to the development of ALS.”

Anna Choi whose review is here.

“Dr Choi’s research focuses on the effects of environmental exposures on health outcomes. She has been studying the birth cohorts in the Faroe Islands where exposures to environmental chemicals including mercury, PCBs, and PFCs are increased due to traditional marine diets. In addition, she also studies the effects of the contaminants on cardiovascular function and type 2 diabetes among the Faroese septuagenarians. She is also actively involved in the research on the impact of nutrients as possible negative confounders that may have caused an underestimation of methylmercury toxicity. Dr Choi’s other research interests include studying the adverse effects of fluoride exposure in children.”

Why were reviewers with a wider research experience not chosen? This journal allows authors to propose suitable reviewers themselves. Or the reviewers may have been chose by the associate editor handling this paper – Prof David Bellinger. His research focuses on the neurotoxicity of metabolic and chemical insults in children. So again it may just be the blinkered view of someone whose research background stressed the role of neurotoxicants rather than other factors likely to influence ADHD prevalence.

The journal’s responsibility

I noticed that one of the two chief editors (who have final say over acceptance of submitted papers) of this journal is Prof Philippe Grandjean. He himself has been actively promoting the idea that fluoride is a neurotoxicant purely on the evidence of the metareview of Choi et al (2012). Yes he is a coauthor of that review and Choi is one of the reviewers of the Malin and Till paper. The review of Choi et al (2012) related to areas of mainly China where fluoride concentrations are higher than used in community water fluoridation. Areas where endemic fluorosis is common.

I have to wonder if Grandjean’s well-known position on fluoride and community water fluoridation was a consideration in choosing this journal for publication.

Others have commented that the journal Environmental Health is considered low-quality based on its low impact factor. I do not know the area well enough to pass judgement myself. However, I notice that the journal charges authors for publishing their paper (£1290/$2020/€1645 for each article accepted for publication.) This sort of charge, associated with poor quality peer-review makes me suspicious. I have commented on these sort of journal before in my post Peer review, shonky journals and misrepresenting fluoride science.

Conclusions

This is one example of peer-review and paper acceptance which brings into question the idea of using  publication and peer-review as endorsement of a study’s   quality. I am sure this is not an isolated case. Even with the best of intentions journal editors and reviewers are limited by their own areas of expertise. Journal publication and peer-review is a far from perfect process – even if it is preferable to current alternatives.

Unfortunately activists will promote poor quality studies like this by blindly using the study’s peer-review status.

The intelligent reader should beware of such blind endorsements. Knowing the human foibles which exist in the research and publication processes such a reader will consider the contents of the paper and not rely on peer-review status. They will consider the evidence and conclusions critically. And if they don’t have enough background to make their own critical assessment they will consider the views of others with the required expertise and not blindly accepting what political activists tell them.

Footnote

Just came across this article referring to peer-review problems in journals published by BioMed Central – Major publisher retracts 43 scientific papers amid wider fake peer-review scandal.

BioMed Central publishes the Journal Environmental Health discussed in this post. I am not suggesting this paper was part of the peer-review racket discussed in the article. But the news item does highlight the point I am making that intelligent readers need to consider published scientific papers carefully and critically and not blindly rely on “peer-review” endorsement.

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ADHD linked to elevation not fluoridation

Attention-Deficit Hyperactivity Disorder (ADHD) is more likely linked to residential altitude than community water fluoridation (CWF). This finding calls into question a recent paper claiming ADHD is linked to CWF. A paper that is being heavily promoted on social media at the moment by anti-fluoridation groups.

I discussed problems with that paper, (Malin & Till, 2015) in my article More poor-quality research promoted by anti-fluoride activists. Now I have taken my critique further by making my own exploratory investigation of likely influences on the prevalence of ADHD in US states using the approach of Malin & Till,(2015). Except I did not limit my investigation to CWF  data but also included state prevalence data for other likely influences on mental health.

ADHD linked to elevation

Elevation One of the best correlations with ADHD state prevalence I found was with elevation data for each state. It’s a negative correlation – the higher you go the lower the prevalence of ADHD This figure shows the correlation of ADHD state prevalence in 2011 with mean elevation for the 51 states. It is statistically significant with a correlation coefficient (r) of -0.5 and significance (p) of 0.00.

Fluoridation-2010For comparison, the similar correlation of ADHD state prevalence in 2011 with prevalence of CWF in 2010, while significant, has a correlation coefficient of +0.32 and significance of 0.02. However, the correlation with CWF is not significant in a multiple regression with elevation – see below.

Other factors worth considering

My exploratory statistical analysis showed a number of other factors significantly linked to ADHD with correlations similar to, or higher than, CWF. Images for the data and a table of correlation coefficients and their significance are shown below.

The correaltion of ADHD state prevalence in 2011 with home ownership and % living in poverty are better than with CWF. These correlations are positive – the prevalence increases with % home ownership and % of people living in poverty. I guess it is hardly surprising that mental health problems would increase with the amount of poverty. But perhaps in the US home ownership is also not conducive to mental health?

Home-Poverty

The correlations of ADHD state prevalence with educational attainment (Bachelors degree) 2009 and Per Capita personal income 2010 were similar to that with CWF. These correlations are negative – I guess its easy to understand that higher incomes and better education is conducive to better mental health (lower prevalence of ADHD).

Education-Income

over-65

The correlation of ADHD state prevalence with the proportion of the sate’s population older than 65 was also similar to that for CWF. The correlation is positive and one can only speculate on reasons for the increase of ADHD prevalence as the proportion of older people increases.

The table below summarises correlation coefficients (r) and statistical significance (p) for the figures above.

Correlation of ADHD state prevalence with a range of factors

State data Correlation coefficient (r) Statistical significance (p)
Mean elevation -0.50 0.009
CWF 2010 % +0.32 0.022
Home ownersip % +0.38 0.005
Poverty % +0.37 0.007
Education (% Bachelor’s degree) -0.35 0.011
Per capita income ($) -0.32 0.022
Age over 65 % +0.30 0.031

Multiple regressions

CWF in 2010 is correlated with mean elevation – correlation coefficient r=-0.43 and significance p=0.002 – suggesting these are not independent variables. (CWF in 1992 was similarly highly correlated with mean elevation.) Perhaps Malin and Till (2015) only found a correlation of ADHD with CWF because they are both related to mean elevation.

Multiple regression analysis suggests this is the case. The statisitically significant factors were mean elevation (p=0.001), home ownership (p=0.000) and poverty (p=0.005). The contribution of CWF in 2010 was not statistically significant in this multiple regression (p=0.587) as were most of the other factors I considered.

Malin and Till (2015) use the CWF for 1992 in most of their comparisons. My analysis shows this has a better correlation with ADHD prevalence in 2011 than CWF for any other year (r=0.45 cf 0.32 for CWF in 2010). It seems strange to use 20 year old data in  a model predicting ADHD prevalence for 2011 so I used more recent data for my exploratory analysis. However, in a multiple regression the contribution from CWF in 1992 was still not statistically significant (p= 0.158).

Conclusion

We should be careful of conclusions arising from such exploratory investigations. Firstly the obvious – correlation is not causation. But secondly the choice of data  is crucial.

Malin and Till (2015) chose to consider CWF prevalence as the main factor influencing ADHD prevalence. They did also include socioeconomic status (SES) as a secondary factor.  However, my analysis shows a number of other factors which could equally be considered. And when they are considered in multiple regressions the contribution from CWF is not statistically significant.

modelThe model used by Malin and Till (2015) using CWF in 1992 and SES in 1992 explained only 31% of the variance of ADHD prevalence in 2011. The corresponding firgures for ADHD prevalence in 2003 and 2007 were 24% and 22%.) But using a model for the influence of mean elevation, home ownership and poverty only (no CWF included) I was able to predict the state prevalence of ADHD in 2011 as shown in this figure. This accounts for 48% of the variance and has a significance of p= 0.000. Perhaps further exploration of the available data could produce an even better model but the key point here is that CWF does not contribute anything once mean elevation is included.

I do not think Malin and Till (2015) are justified in drawing the conclusion that CWF influences ADHD. Their mistaken conclusion has arisen from their limited choice of data considered for the exploratory analysis. That in itself seems to have resulted from a bias inherent in their hypothesis that “fluoride is a widespread neurotoxin.”

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More poor-quality research promoted by anti-fluoride activists

Anti-fluoridation propagandists must think all their Christmases have come at once. They at last have a “peer-reviewed” scientific paper they can claim supports their position. What’s more, it is the second such paper to appear in the last month.

But they really are resorting to arguments of quantity (2 papers) over quality. This new paper claiming a link between community water fluoridation (CWF) and Attention-Deficit Hyperactivity Disorder (ADHD) is of just as poor quality as the earlier one claiming a link with hypothyroidism. Both papers are speculative, ignore other relevant factors, and “prove” nothing.

I discussed the hypothyroidism paper in the article Paper claiming water fluoridation linked to hypothyroidism slammed by experts. The new ADHD paper is:

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.

Here are my thoughts on this paper.

Exploratory investigation – correlation not causation

The authors have simply taken existing online data and searched for a statistically signficant relationship. They have explored the limited data sets used – not attempted to prove an effect. After all, correlation does not prove causation – the graph below shows an example of how correlation can often produce meaningless results.

The data sets Malin and Till (2015) used are both from the USA Centers fo disease Control (CDC).

  1. State-based attention-deficit hyperactivity disorder (ADHD) prevalence (Visser et al., 2014);
  2. Numbers of people receiving fluoridated water from public water supplies in each state obtained from the CDC.

Note, they did not use data for individual children exhibiting symptoms of ADHD  determined by  a health professional. The data was from random surveys “in which parents were contacted via telephone and asked about the emotional and physical well-being of a randomly selected child from their household.” Similarly they did not use data for dietary intake of fluoride by individual children but used “the percentage of the U.S. population on public water systems that receives optimally fluoridated drinking water.”

They have assumed these data are reliable proxies for occurrence of ADHD and fluoride dietary intake. But the data could represent other factors as well.

For example, parental reporting of ADHD could differ from state to state because of differences in parental educational levels and ideological attitudes. People in  different sates may not have the same level of knowledge, awareness or acceptance of such behaviours. Malin and Till themselves acknowledge ADHD reporting is higher for parents with a high school education than for parents who did not graduate high school (Visser (2014). Parental education levels are likely to vary from state to state.

The availability of CWF can be dependent on the size of urban areas for both technical reasons and because of  recognised willingness for innovation from large and high status city leaders (Crain, 1996) so that the state prevalence used could be acting as a proxy for the distribution of urban areas of different sizes, and the relative urban/rural distributions in different sates. A correlation may indicate nothing more than a relationship between city sizes and parental education.

The authors themselves warn their study has limitations, saying it is:

“an ecological design that broadly categorized fluoride exposure as exposed versus non-exposed rather than collecting information related to concentration of fluoride and patterns and frequency of exposure or outcome at the individual level. Future research could explore the relationship between exposure to fluoridated water and the occurrence of ADHD at the individual level.”

And, again, we should always keep in mind that correlation does not prove causation.

The starting hypothesis

Inevitably any serious exploratory investigation should start with a working hypothesis. As psychologists the authors are presumably interested in ADHD and its causes. But why investigate state prevalence of CWF instead of any of the other factors indicated in this condition. In fact they list a range of candidates from arsenic and lead to food additives and food colouring. Granted, they saw CWF as a field ripe for plucking as they say fluoride “has received virtually no attention in the ADHD literature.” But I would have expected them to at least include these other known factors as confounders in their study.

I think the answer lies with their biased reading of the literature. They start with the claim that fluoride is a “widespread environmental neurotoxin,”  but only really cite Grandjean and Landrigan (2014) and the closely-related meta-analysis of Choi et al., (2012) to support this claim. I have discussed those papers and their problems in  Repeating bad science on fluoride and Controversial IQ study hammered in The Lancet. A major problem with that work is it involved areas of endemic fluorosis where fluoride intake is high so it is not directly relevant to CW. In fact, the authors’ bias is indicated by the fact they did not cite Broadbent et al., (2014) which showed no neurotoxic effects of CWF. Broadbent et al.’s paper is directly relevant to CWF – Choi et al.’s is not. (I discussed the differences as indicated by dental fluorosis data in my article Water fluoridation and dental fluorosis – debunking some myths

I feel this omission indicates that the authors resort to the special pleading of anti-fluoride activists in the citations they used for justifying their starting hypothesis. The also rely on studies of rats fed very high levels of fluoride, such as that of  Mullenix et al., (1995), and then use her weak argument to claim relevance to CWF by comparing  rat blood plasma F levels to those for humans ingesting high levels of fluoride. (See my article Peer review of an anti-fluoride “peer review” for a discussion on this). Similarly, although acknowledging the high F intake levels of most of the studies reviewed by Choi et al., (2012), they excuse this by referring to the one study with low levels (0.88 mg/L) – ignoring the fact this was a one and a half page article in a newsletter describing measurements in an iodine deficient area. In this study (Lin, et al., 1991) children from low iodine areas were compared with a group from another area that had received iodine supplementation. About 15% of the children suffered mental retardation, 69% of these exhibited subclinical endemic cretinism. The effect of iodine supplementation was clear, the effect of fluoride not so clear. (See Peer review of an anti-fluoride “peer review” for further discussion of this).

So, I think the justification for their starting hypothesis is hardly objective

“Natural” vs “artificial” fluoride

Despite  problems with justification for their hypothesis they did find a significant positive relationship between the US state prevalence of parent-reported ADHD in children and the state proportion of water supplies with optimum levels of fluoride. Again, not a proof of their hypothesis, but interesting data to consider nonetheless. They found inclusion of socio-economic status data improved the relationship but did not consider other relevant confounding factors like parental education and exposure to relevant chemicals.

In contrast, the relationship they found between ADHD prevalence and natural fluoride prevalence (at optimum level or above) was negative and statistically signficant. This actually conflicts with their starting hypothesis of chemical neurotoxicity based on the work of Choi et al., (2014) and Grandjean and Landrigen (2014). While they concede the data really doesn’t allow a conclusion they suggest it could result from the ADHD effect being specific to “fluoridation chemicals” and not fluoride itself.

This leads them to suggest a theoretical “pathway” for CWF contributing to ADHD – the corrosion of lead-bearing plumbing by fluorosilicic acid. Trouble is this ignores the well established fact that fluorosilicates used in CWF decompose to form silica and the hydrated fluoride anion when diluted in water. Malin and Till seem oblivious to work showing this and rely instead on citation of the poor quality work of Masters and Coplan to support this “pathway.” Another example of their citation bias.

But their proposal does raise an important question. Given that lead is one suggested cause of ADHD why did they not concentrate their exploratory analysis of data for lead intake by children in different states, rather than CWF prevalence? Or at least include lead levels as confounders in their statistical analysis.

The thyroid story again

Their second suggested “pathway” is via suppression of thyroid gland activity by fluoride. But, again, this hypothesis does raise the question of other causes, in particular iodine deficiency. (See my discussion of Peckham’s paper – Paper claiming water fluoridation linked to hypothyroidism slammed by experts – for more on this). If this was part of their starting hypothesis then why not consider data for state prevalence of iodine deficient diets of children? Or or include this as a confounder in the analysis?

I find it interesting that despite declaring a starting hypothesis based on the chemical toxicity claims of Choi et al., (2012) and Grandjean and Landrigen (2014), Malin and Till have not proposed any theoretical “pathway” involving direct neurotoxicity of fluoride itself to explain their result. This makes their unwillingness to consider other relevant confounding factors even more obvious.

Conclusions

As I wrote above correlation is not causation  and this study does not “prove” anything. The observed “link”could represent a number of other relationships which are not directly associated with CWF. The analysis also suffers from a lack of consideration of obvious confounding factors.

I believe this is the sort of problem that arises when researchers have a committment to a starting hypothesis and peer review systems are inadequate. Such studies are a problems when published because ideologically motivated activists love to cherry-pick them to claim “scientific support” for their cause. This is not helped when the researchers themselves climb on the activist bandwagon and attempt to claim more for their findings that is really justified.

I think Malin and Till have done this with the press release from their department – Fluoride in tap water associated with ADHD in children, researchers find. It is one thing to say:

“Our findings showed that artificial fluoridation prevalence in 1992 predicted ADHD prevalence in 2003, 2007 and 2011 among children and adolescents in the United States, and that was after controlling for median household income.”

But the careful claim their “findings showed” a “prediction” is far too easily seen as proof in the mind of the lay-reader. Worse, they draw unwarranted conclusions from their limited work:

“As citizens of Toronto, living in an artificially fluoridated community, I think we need to ask ourselves whether this is still a worthwhile practice.”

One can only pose such questions in the context of an objective assessment of their own work together with other research of possible harmful and beneficial effects of CWF. I think their biased choice of citations in this paper shows they are not capable of doing this.

On the other hand reviews such as the recent NZ Fluoridation Review, Health effects of water fluoridation : A review of the scientific evidence, have done this. Community leaders should be going to such sources for their information and not rely on cherry-picked poor quality studies like Malin and Till (2015) which will be promoted to them by anti-fluoride propagandists and activists.

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