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Fascinating and painless chemistry lessons Ken Perrott Dec 16

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I had to select this video on the element rutherfordium because of the  New Zealand link of the scientist the element is named after.

It’s an interesting short lesson on rutherfordium and there is more where it came from – in fact one short video lesson for every element in the periodic table! Click on the image below to go to the interactive version of the periodic table.

PeriodicTable

 

You can find out more about the people who produced these videos from this University of Nottingham web site – Periodic Videos

This is a great, painless, way to learn some interesting chemistry.

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Did the Royal Society get it wrong about fluoridation? Ken Perrott Dec 14

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Did the Royal Society of NZ and the Office of the NZ Prime Minister’s Chief Science Advisor make a big mistake in their report Health Effects of Water Fluoridation: a Review of the Scientific Evidence)? Did they misrepresent a scientific paper which reported an effect of fluoride on the IQ of children?

This is what “Connett’s Crowd,” anti-fluoridation activists and propagandists, are saying in their attempts to discredit the review. So, did this review make the mistake its critics claim?

Well, no. It’s just a beat up. But there is a small mistake in the review’s executive summary which the anti-fluoridationists are pouncing on.

The issue

Most critics of community water fluoridation rely heavily on this paper:

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.

This was a metareview of mainly obscure and brief reports (see Quality and selection counts in fluoride research) indicating the possibility the fluoride intake by children living in high fluoride areas of China and Iran may suffer IQ deficits. Choi et al., (2012) used a statistical analysis to determine the possible size of the IQ drop averaged over all the studies. They found a small drop and said:

“The estimated decrease in average IQ associated with fluoride exposure based on our analysis may seem small and may be within the measurement error of IQ testing.”

Their abstract reported the:

“standardized weighted mean difference in IQ score between exposed and reference populations was –0.45 (95% confidence interval: –0.56, –0.35).”

(Their use of “standardised weighted mean difference” was poorly explained and has caused confusion with many readers. See below for a brief explanation of the term).

What did the Royal Society Review say about this?

The review discusses the question of possible neurotoxic effects on page 49-50. Their comment relevant to Choi et al., (2014) appears below (click to enlarge):

review1

And this is what is in the executive summary (click below to enlarge). It makes a very small mistake by referring to “less than one IQ point” when it should have said “less than one standard deviation.”

review2

So, the review reported the Choi et al., (2012) findings accurately but made a small mistake in the executive summary. This is really of no consequence because the overall message of the small size of the estimated IQ drop (described by the authors as “small and may be within the measurement error of IQ testing”) is not really altered.

What do the anti-fluoride critics say?

Such mistakes are inevitable and authors will universally say they usually find them only after publication when no correction is possible. I remember picking up 5 mistakes in one of my papers – mainly incorrect spelling of my own name several times and a mistake in the address of my institution – those were the early days of word processing! Of course no one used my mistakes to cast doubts on the scientific content of the paper.

Still, “Connett’s crowd” have been merciless in their criticism. Here is an example from the big man himself (see Water Fluoridation: The “Healthy” Practice That Has Deceived the World):

Gluckman and Skegg (sic)* mistakenly claim “a shift of less than one IQ point” in the 27 studies reviewed by Choi et al. (2012). What they have done here is to confuse the drop of half of one standard deviation reported by the authors with the actual drop in IQ, which was 6.9 points. Such an elementary mistake would not have been made by Gluckman and Skegg (sic)* if they had actually read the report, instead of relying on what fluoridation propagandists were saying about it.

* Of course Gluckman and Skegg – who Connett calls The ‘Hollow Men’ of New Zealand –  did not author this review.

H.S. Micklem, in the Fluoride Free NZ report on the Royal Society review, snipes:

“It is hard to imagine how this mistake could have been made by anyone who had actually read the papers that are disparaged so casually.”

I guess critics should read carefully before indulging in such snaky comments. All they have demonstrated is that they did not read past the executive summary of the review (and certainly did not read the relevant section in the review). Or, more seriously, that they wish to misrepresent the review by highlighting the mistake and ignoring what the review actually says.

(At Least Kathleen Thiessen was more honest in her comments in the FFNZ report because she did refer to page 49 as well as the mistake. However she still concluded “The RSNZ report is not accurate in its characterization of the Choi et al. (2012) article on effects of fluoride on children’s IQ.”)

Update: One of my commenters, picker22, has brought this to our attention – it puts the mistake mentioend above into context.

“The original press release from Harvard School of Public Health News service made the same error stating that the difference was .5 IQ points. This error on the part of Harvard led to more that a couple of mis-statements by fluoridation advocates in the US.

The current web page notes that the sentence reporting the magnitude of IQ change was “updated” Sept 5, 2012. Sadly, I didn’t copy the original.

http://www.hsph.harvard.edu/news/features/features/fluoride-childrens-health-grandjean-choi.html

Is Choi et al (2012) relevant to fluoridation?

Not really.

The only study specific to community water fluoridation (CWF) the Royal Society review mentions is Broadbent, et al., (2014). Community Water Fluoridation and Intelligence: Prospective Study in New Zealand.

The Choi et al., (2012) paper reviews reports mainly from areas of endemic fluorosis where fluoride intake is much higher than areas using CWF. Subsequently the same authors  made their own measurements in a similar area of China and did not find a significant relationship of drinking water fluoride to IQ (see Choi et al., 2014. Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study).

The did, however, find a relationship of IQ to severe dental fluorosis. I discuss their findings in my article 

What is this “standardised weighted mean difference”

This term caused a lot of confusion with readers and critics. Choi et al., (2012) used this statistical device because they were attempting to estimate the average decrease in  IQ associated with fluoride exposure based on the difference in IQ between children from high fluoride villages and low fluoride villages in a large number of studies. Further, different IQ scales and measurement methods were used in the different studies which had different levels of variation in the data.

They therefore standardised the differences by expressing them as a fraction of the standard deviation for each study. A mean value over all studies was determined, weighting the contribution from each study according to the precision of the IQ measurements.

The standardised weighted mean difference value of 0.45 has meaning because we know it represents less than half of one standard deviation so it gives us an indication of how it compares with measurement error. But a value of 6.9 as used by Paul Connett is meaningless – until we are told the standard deviation. Choi et al. (2012)  did not report a difference of 6.9 implied by Paul Connett who appears to have obtained that value from a response to a letter to the editor where they use a hypothetical example to explain the meaning:

“For commonly used IQ scores with a mean of 100 and an SD of 15, 0.45 SDs is equivalent to 6.75 points (rounded to 7 points).”

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“Do your own research!” Ken Perrott Dec 11

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How many times have I had discussion partners on the internet say to me “Do your own research?”

Inevitably they are pushing some pseudoscientific or anti-scientific conspiracy theory – yet claiming science is their friend!

Here, one of the members of Paul Connett’s Fluoride Action Network team ( Carol Kopf, Media Director who uses the Twitter name @nyscof) tells critics to do their own research – internet research:

And if you type in fluoride adverse effects, you get 270 results

Well, I followed her advice and got this:

Fluoride adverse effects – PubMedScreenshot-fluoride

But unlike Carol Kopf I naturally didn’t stop there – I also typed in “water adverse effects” and got this:

Water adverse effects -PubMed
Screenshot-water

She has a really funny understanding of what the word research means.

Imagine if she followed her implied advice and refused to consume water because of all its adverse effects!

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Cherry-picking and misinformation in Stan Litras’s anti-fluoride article Ken Perrott Dec 08

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This is the second article in a series critiquing contributions to the Fluoride Free NZ report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report.”

My first article Peer review of an anti-fluoride “peer review”  discussed Kathleen Theissen’s contribution. (It also discussed a draft contribution by Chris Neurath which does not appear in the final version).

I will shortly post a 3rd article discussing H. S. Micklem’s contribution.

See The farce of a “sciency” anti-fluoride report for an analysis of the close relationships between the authors and peer reviewers of the Fluoride Free report and anti-fluoride activist groups.


There is a lot in Stan Litras’s article to criticise – there is a lot which is misleading or outright wrong. I hope Stan will seriously consider my criticisms and respond to them, especially where he thinks I am wrong.

My criticisms should also be considered by Bruce Spittle and Hardy Limeback who Fluoride Free NZ listed as “peer reviewers” of Stan’s article. They must bear some responsibility for allowing the article to go ahead without the necessary corrections.

Litras makes many of his criticisms of community water fluoridation (CWF) in passing – without argument or evidence. But he declares:

“My comments will focus on the gross over statement of the purported benefits of fluoridation in our society, New Zealand, 2014.”

So, I will start with the claims he makes on this.

“Overseas studies” – The WHO data

Central to this are Stan’s assertions:

“The “elephant in the room” is that while decay rates fell in areas where fluoridation was implemented, it also fell in areas that weren’t, often at a faster rate. (8)”

And

“Globally, fluoridation is seen to make no difference to reduced decay rates, there being no difference between the few countries which use artificial fluoridation, and those that don’t. (8,7)”

His only evidence for this is a figure prepared by Chris Neurath from the Fluoride Action Network – using data from the World Health Organisation (WHO). Here it is in a slightly simpler version to the one used by Stan.

I am amazed that anti-fluoride propagandists keep using this graphic as “proof” that fluoride is ineffective. But they do – which can only mean they haven’t thought it through.

While the plots do show improvements in oral health for countries independent of fluoridation they say nothing about the effect of fluoride. Simple comparison of countries obscures all sorts of effects such as differences in culture, history, social and political policies, etc. Such plots are also influenced by changes and differences in dental treatment and measurement techniques.

Robyn Whyman in his report Does delayed tooth eruption negate the effect of water fluoridation? exposes the little trick Stan is trying to pull with the WHO data:

“Studies that appropriately compare the effectiveness of water fluoridation do not compare poorly controlled inter-country population samples. They generally compare age, sex, and where possible ethnicity matched groups from similar areas. Inter-country comparisons of health status, including oral health status, are notoriously difficult to interpret for cause and effect, because there are so many environmental, social and contextual differences that need to be considered.”

There are some within country data within the WHO data set Neurath used which can give a better idea of the beneficial effects of fluoridation. This plot shows the results for the WHO data for Ireland. A clear sign that fluoridation plays a beneficial role.

Neurath covered up evidence for the benefits of CWF by simply using the mean of fluoridated and unfluoridated areas for countries like Ireland and New Zealand. Also, the straight lines in Chris Neurath’s plots are a real give away to the poor quality of the data used. Two data points for each country!

New Zealand – Cherry-picking the MoH data

I have criticised Stan’s misrepresentation the Ministry of Health (MoH) data before. At the time he was using and misrepresenting some of my own graphics on his business website. He has since removed the offending article but now he returns with a vengeance – with tables and figures of his own.

This has given him free hand to cherry-pick and misrepresent to his heart’s content.

He claims:

“Ministry of Health figures recorded every year in 5 year olds and year 8s (12-13 year olds) consistently show minimal or no differences between fluoridated and nonfluoridated areas of NZ.”

stan_1

Cherry-picked data from Stan Litras

And he backs this up with a graph.

That looks about right. The data for 2011 shows 59.9% of 5 year olds in fluoridated areas were caries-free while 59.2% were carries free in non-fluoridated areas. No real difference.

But come on! A single data point, one year, one of the age groups for the fluoridated and unfluoridated areas! That is blatantly cherry-picking – as I mentioned in my article Cherry picking fluoridation data. In that I presented all the data for 5 year olds and year 8s, and for the total population and Maori, and for % caries free and decayed, missing and filled teeth (DMFT).

I have reproduced this data here in a simpler form using several figures.

caries-freeConsidering the % caries free data there are several points:

1: These do not “consistently show minimal or no differences between fluoridated and nonfluoridated areas” as Stan claims.

2. They do show a decline in differences between fluoridated and non-fluoridated areas in recent years.

3: This trend is less obvious for Maori but still present.

4: Stan has blatantly cherry-picked the  data points for 5 year-olds in 2011 to give him the least possible difference (see red circle in figure).

dmft

The data for decayed, missing and filled teeth (DMFT) shows similar trends.

Presumably both measures (% caries free and DMFT) are useful indicators of oral health but they probably convey complementary and not exactly the same information.

I discussed features of the graphs and their trends in in my articles Cherry picking fluoridation data and Fluoride debate: Response to Paul’s 5th article where I also discussed limitations in the data.

We need to appreciate this is just normal school clinic data, without technique standardisation for those making the measurements or proper recording of place of residence. The latter effect probably shows up more strongly after 2004 when a “hub and spoke” dental clinics system was introduced further confusing proper records of likely fluoride intake. One school dental clinic could serve a number of areas – both fluoridated and non-fluoridated. This mixing is a likely explanation for the apparent decline of the effectiveness of fluoridation after 2006.

So, yes, the MoH data is not straightforward. But this means it should be considered sensibly, taking into account its limitations and the social factors involved.  Instead, Stan has leapt in – found the data points which best fit his own biases and then tried to claim those data  are representative when they aren’t.

Stan presented another self-prepared graphic using data for the 4 different regions for 5 year olds (see his page 27). He appears not to have used the correct data – at least for the Northern and Southern regions.  My own graphic for this shows differences to his. (Of course, the mistake may be mine – if Stan can show I am wrong I will happily delete this part from my critique).

region-correct

Again, that data should also not just be considered at face value – or selected to confirm a bias. It has limitations. For example in this case there were only 55 children in the fluoridated Southern region compared with 7568 in the non-fluoridated area. A footnote on the data sheet says:

“2. Excludes Southern DHB because data were not reported for 1 Jan-20 Feb 2012, and fluoridation status was not captured for most children throughout 2012, due to transition to a new data system. “

Proper consideration of such data must take these sort of limitations into account. But of course all Stan Litras did was select data to support his assertions and ignore the rest. Any limitations in the data did not concern him.

Lifetime benefit

Stan has a thing about the “lifetime benefits,” or lack of benefits, of CWF. Most studies of CWF have used data for children – data for adults is less common but there is still research literature on this available.

But all Stan did on this was to cherry-pick a graphic (Figure 53) from the NZ Oral Health Survey showing no significant change in DMFT for 65-74 year olds between the years 1976, 1988 and 2009. He then claims:

“Data from the NZOHS 2010 do not support statements of a lifetime benefit, indicating that the action of fluoride is simply to delay the decay. (13)”

But he has had to work hard to avoid other data like that in Figure 49 below which do show a significant improvement in the number of retained teeth of that age group. The Oral Health Survey report itself says:

“In dentate adults aged 65–74 years, the mean number fell from 17.1 to 12.1 missing teeth per person on average from 1976 to 2009.”

mising-teeth

Again, instead of cherry-picking, searching for an image to fit his story, Stan should have considered the data and figures critically and intelligently. Perhaps the DMFT data does not show what he claims because more teeth have been retained in recent years. The decline in missing teeth could have been balanced by increases in fillings due to increase in remaining teeth. The lack of a significant difference in DMFT actually suggests the opposite to what he claims.

Litras also misrepresent the York review on the question of benefits from CWF for adults. He says:

“The York Review found there was no weight of evidence to support benefit in adults or in low SES groups, or increase of decay in cessation studies. (7)”

Just not true. The York report says:

“One study (Pot, 1974) found the proportion of adults with false teeth to be statistically significantly greater in the control (low-fluoride) area compared with the fluoridated area.”

Sheiham and James (2014) stressed that a proper assessment of oral health problems should include data for adults as well as children. Recent research is starting to take up this issue. For example O′Sullivan and O′Connell (2014) recently showed that water fluoridation provides a net health gain for older Irish adults.

Systemic vs topical

Stan promotes the common mythology of the anti-fluoridation propagandist that any mechanism for a beneficial effect of fluoride in restricting tooth decay is purely “topical.” He claims:

“It has been widely accepted since the 1990s that any effect on tooth decay from swallowing fluoride is insignificant or non-existent. To quote: CDC 1999: “the effect of Fluoride is topical “ (5); J Featherstone 1999: “the systemic effect is, unfortunately, insignificant” (6).”

Let’s consider what the sources Stan cites actually do say. I will quote from the 2001 edition of Stan’s citation 5 which he (partly) cites on page 36:

“Fluoride works to control early dental caries in several ways. Fluoride concentrated in plaque and saliva inhibits the demineralization of sound enamel and enhances the remineralization (i.e., recovery) of demineralized enamel (12,13 ). As cariogenic bacteria metabolize carbohydrates and produce acid, fluoride is released from dental plaque in response to lowered pH at the tooth-plaque interface (14 ). The released fluoride and the fluoride present in saliva are then taken up, along with calcium and phosphate, by demineralized enamel to establish an improved enamel crystal structure. This improved
structure is more acid resistant and contains more fluoride and less carbonate (12,15–19 ) (Figure 1). Fluoride is more readily taken up by demineralized enamel than by sound enamel (20 ). Cycles of demineralization and remineralization continue throughout the lifetime of the tooth.”

topical-mechanism

And

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

(Note: Stan simply quotes the first part of this statement (in red) in his article (page 36) and completely omits the second part (in black) – presumably because he wants to deny a role for fluoridated water in influencing the saliva fluoride concentrations. This cherry-picking of the CDC statement is typical for anti-fluoride propagandists – see Fluoridation – topical confusion).

There is an attempt to confuse a “topical” or “surface” mechanism with a “topical” application (eg toothpaste or dental treatments). However, fluoride is transferred to saliva from food and drink during ingestion so that ingested fluoride also contributes to the “topical” or “surface” mechanism.

However Stan wants to deny a “topical” role for ingested fluoride and claims (page 36):

“The required elevation of baseline levels only occurs after using fluoridated toothpaste or mouth rinse, a concentration of 1,000 ppm or more instead of 1 ppm from water.(24)”

His citation 24 is to Bruun (1984) and he misrepresents that paper which actually said:

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

Systemic role.

Featherstone does say:

“Fluoride works primarily via topical mechanisms which include (1) inhibition of demineralization at the crystal surfaces inside the tooth, (2) enhancement of remineralization at the crystal surfaces (the resulting remineralized layer is very resistant to acid attack), and (3) inhibition of bacterial enzymes. Fluoride in drinking water and in fluoride-containing products reduces tooth decay via these mechanisms. Low but slightly elevated levels of fluoride in saliva and plaque provided from these sources help prevent and reverse caries by inhibiting demineralization and enhancing remineralization. The level of fluoride incorporated into dental mineral by systemic ingestion is insufficient to play a significant role in caries prevention. The effect of systemically ingested fluoride on caries is minimal.”

There is some debate over the role of systemic fluoride exuded by salivary glands. Many feel the concentration is too low – but because its effect is also determined by the presence of calcium, phosphate, organic species and pH it is best not to be dogmatic about this. It is, anyway, difficult to separate salivary fluoride derived from transfer from food and beverage in the oral cavity from that exuded by the salivary glands from systemic sources.

Stan is determined to deny a role for systemic fluoride during tooth development asserting:

“the erroneous theory that fluoride incorporated into children’s developing tooth enamel would make teeth more resistant to decay.”

While often neglected because of the concentration on surface mechanisms with existing teeth the theory that fluoride is incorporated into the developing teeth of children and confers a degree of protection is far from erroneous.

Newbrun (2004), for example, stressed in a review of the systemic role of fluoride and fluoridation on oral health:

“The role of systemic fluoride in caries prevention is neither “minimal” nor “of borderline significance.” On the contrary, it is a major factor in preventing pit and fissure caries, the most common site of tooth decay. Maximal caries-preventive effects of water fluoridation are achieved by exposure to optimal fluoride levels both pre- and posteruptively.”

Cho et al (2014) presented data showing that children exposed to CWF during teeth development retained an advantage over those never exposed to it even after fluoridation ceased.

Let’s stop confusing the issue. Systemic fluoride may not play a role with existing teeth but it does during tooth development – even if the relative contributions of systemic fluoride and “topical” or surface fluoride to lasting oral health are difficult to determine.

Tooth eruption delays

Stan resorts to special pleading when he claims with reference to NZ MoH data:

“Small apparent differences could be accounted for by other factors such as delayed eruption of teeth in fluoridated communities, therefore less time in the mouth exposed to plaque acids, ethnic distribution and urban/rural differences.”

He relies on the “York review” (McDonagh et al., 2000) to back up his “delayed tooth eruption” excuse:

“Importantly, the York Review noted that the variation of tooth eruption times between fluoridated and unfluoridated areas was not taken into account. (7)”

But that review actually said on this subject:

“It has been suggested that fluoridation may delay the eruption of teeth and thus caries incidence could be delayed as teeth would be exposed to decay for a shorter period of time. Only one study compared the number of erupted teeth per child. The difference was very small and in opposite directions in the two age groups examined, however no measure of the statistical significance of these differences was provided. Only one of the studies attempted to control for confounding factors using multivariate analysis (Maupomé 2000).”

Robyn Whyman has gone into this claim in more detail in his report Does delayed tooth eruption negate the effect of water fluoridation?Here he critiques Paul Connett’s reliance on this excuse and concludes from his review of the literature:

“The studies and reports cited by Professor Connett to try and validate an argument for delayed tooth eruption either do not make the claims he suggests, or do not have direct relevance to trying to assess the issue. The claimed association is at odds with the published literature which indicates minimal variation in eruption time of permanent teeth by exposure to fluoride. A rational explanation exists for the minimal variations that have been reported based on the relationship between fluoride exposure, caries experience in the primary teeth and emergence timing for the permanent teeth.”

The “delayed tooth eruption” excuse is nothing more than special pleading and straw clutching.

Socio-economic factors

Stan again misrepresented the York review regarding socio-economic effects on oral health and the effectiveness of CWF when he claimed “there was no weight of evidence to support benefit in adults or in low SES groups.” The York review actually said:

“Studies should also consider changes in social class structure over time. Only one included study addressed the positive effects of fluoridation in the adult population. Assessment of the long-term benefits of water fluoridation is needed.”

And

“Within the UK there is a strong social gradient associated with the prevalence of dental caries. This is found both in adults and in children. Those who are more deprived have significantly greater levels of disease. There is also geographical variation with the northwest of England, Scotland and Northern Ireland most severely affected. (Pitts, 1998; Kelly, 2000)”

There have been a range of studies internationally showing that fluoridation can aid in reducing differences in oral health due to socio-economic effects. See for example Cho, et al., (2014).

What happens when fluoridation is stopped

Stan briefly refers to this issue, citing (as anti-fluoridation activists always do) Künzel and·Fischer (2000). I will simply refer him, and interested readers to my article What happens when fluoridation is stopped? This boils down to the need to read the scientific literature properly as usually the anti-fluoridation activists ignore the details referring to fluoride treatments and procedures which replaced CWF.

There are a number of other points mentioned briefly by Stan Litras which could be discussed but this article is already too long so I will leave that to the comments section.

Conclusions

Stan Litras has simply indulged in blatant cherry-picking of data, and misrepresentation of the literature, in his critique of the recent review Health Effects of Water Fluoridation: a Review of the Scientific Evidence produced by the Royal Society of NZ together with the Office of the Prime Minister’s Chief Science Advisor. Perhaps we shouldn’t expect better from a political activist in the anti-fluoride movement but he, and Fluoride Free NZ, attempt to present this, and other articles in the collection, as objective and scientifically credible. It is neither – such cherry-picking and misrepresentation violates any scientific ethics and needs to be exposed for what it is. The Fluoride Free NZ claimed “peer reviewers,” Bruce Spittle and Hardy Limeback, must share responsibility because, by their endorsement, they signal their approval of such behaviour.

Note

I offered Stan Litras a right of reply to this post, or even an ongoing exchange with him along the lines of my debate with Paul Connett. He replied:

“I look forward to your comments on my review, as a lay person, but I cannot engage in a serious dialogue with someone who is not a peer with the same level of knowledge as myself in the dental field. “

Hopefully this means he will at least comment here, take issue with me where he thinks I am wrong and correct me where I am mistaken. I also hope than Bruce Spittle and Hardy Limeback will also take advantage of their right to comment here.

References

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

Centers for Disease Control and Prevention. (2001). Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States (Vol. 50, p. 50).

Cho, H.-J., Jin, B.-H., Park, D.-Y., Jung, S.-H., Lee, H.-S., Paik, D.-I., & Bae, K.-H. (2014). Systemic effect of water fluoridation on dental caries prevalence. Community Dentistry and Oral Epidemiology.

Cho, H.-J., Lee, H.-S., Paik, D.-I., & Bae, K.-H. (2014). Association of dental caries with socioeconomic status in relation to different water fluoridation levels. Community Dentistry and Oral Epidemiology.

Fluoride Free New Zealand. (2014). Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report.

Künzel, W.;·Fischer, T. (2000). Caries Prevalence after Cessation of Water Fluoridation in La Salud, Cuba. Caries Res, 34, 20–25. Retrieved from http://www.karger.com/Article/Fulltext/16565

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

Ministry of Health. (2010). Our Oral Health Key findings of the 2009 New Zealand Oral Health Survey. Wellington, Ministry of Health.

Ministry of Health (2014) Age 5 and Year 8 oral health data from the Community Oral Health Service. http://www.health.govt.nz/nz-health-statistics/health-statistics-and-data-sets/oral-health-data-and-stats/age-5-and-year-8-oral-health-data-community-oral-health-service.

National Fluoridation Information Service (2011): Does Delayed Tooth
Eruption Negate The Effect of Water Fluoridation? National Fluoridation Information Service Advisory June 2011, Wellington, New Zealand.

O′Sullivan, V., & O′Connell, B. C. (2014). Water fluoridation, dentition status and bone health of older people in Ireland. Community Dentistry and Oral Epidemiology.

Sheiham, A., & James, W. P. T. (2014). A reappraisal of the quantitative relationship between sugar intake and dental caries: the need for new criteria for developing goals for sugar intake. BMC Public Health, 14(1), 863.

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Today’s fantasy, tomorrow’s possibility Ken Perrott Dec 04

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If you haven’t watch it yet this video, Wanderers,  is a must. And it is well worth watching full screen. It’s a science-inspired short film imagining human exploration of our solar system.

The voice-over is very recognisable – Carl Sagan reading from Pale Blue Dot.

This is what Phil Plait said about the film:

“This is one of the most wondrous and moving paeans to space exploration I have ever seen. The words of Sagan are magnificent, of course. And the effects are stunning, photo-realistic, and very compelling.

But take a moment and let this sink in: Nearly every location depicted in this video is real. These aren’t just fanciful places made up in the head of a special-effects artist; those are worlds in our solar system that actually exist. And many were based on images taken through telescopes, or probes that have physically visited these distant locales.

Sunset on Mars. The weird ridge wrapped around Saturn’s moon Iapetus. The ice fields of Jupiter’s moon Europa. Even those cliff divers? Yup: That’s Uranus’ moon Miranda, with the highest cliffs known in the solar system.

Every time the scene changed in the video, my jaw dropped a little further and my brain soared to a new height. Nothing in there is impossible; no faster than light travel, no wormholes. Even the space elevator shown towering over Mars and the huge cylindrical rotating colony in space (did you notice the Red Sea in it?) are problems in engineering, not physics. We can build them.”

All this is fantasy today but realistically possible in the not too distant future.

Thanks to: This Is A Majestic Vision Of Humans Embracing Our Exotic Solar System.

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The farce of a “sciency” anti-fluoride report Ken Perrott Dec 03

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F network

Click for a larger image

I came up with the image above after a quick glance at a “report” promoted by the local Fluoride Free groups and Paul Connett’s Fluoride Alert organisation. (Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report). It illustrates the incestuous network of authors and “peer reviewers” involved in producing the “report.” I have also illustrated connections of these people to a number of anti fluoride organisations and 2 publications.

The first column lists the authors in red, and their claimed peer reviewers in green. The third column lists the anti-fluoride organisations and several publications these people are connected to.

The middle column lists some other people who are also connected to these organisations and publications. I have already reviewed Kathleen Theissen’s article (see Peer review of an anti-fluoride “peer review”) and will get around to reviewing the other 2 articles (by H.S. Miclen and Stan Litras) later.

Meanwhile, lets just consider the connections between these authors, “peer reviewers” and anti-fluoride organisations.

Taking in each other’s laundry

Most of these names are familiar to anyone who has followed the anti-fluoride movement. That fact in itself shows how this report can in no way be seen as “expert,” “independent” or at all credible. Some details on the illustrated people, organisations and publications.

NRC Review minority: There were several disagreements on the 12 member panel which produce the 2006 NRC report “Fluoride in drinking water. A scientific review of EPA’s standards” because 3 members were anti-fluoride. They were Robert Issacson, Hardy Limeback and Kathleen Theissen. Hardy Limeback is involved in several anti-fluoride activist groups.

Kathleen Theissen appears not to be organisationally involved but regularly makes anti-fluoridation submissions when the issue is debated.

UPDATE: Steve Slott has reminded me of this example of Theissen’s lack of credibility as a peer reviewer of fluoridation-related papers:

“In July 2013, Douglas Main, that freelance reporter and bastion of “objectivity”, interviewed Thiessen to get her opinion on Hirzy’s study on which he based his petition to the EPA.

From the article:

“Experts not involved with Hirzy’s study agreed with its findings.”

“I think this is a reasonable study, and that they haven’t inflated anything,” said Kathleen Thiessen, a senior scientist at SENES Oak Ridge Inc., a health and environmental risk assessment company.”

When the EPA reviewers looked at Hirzy’s study they found that he had made a 70-fold miscalculation in his study. When corrected for that error, the EPA reviewers found that Hirzy’s data actually demonstrated the exact opposite of what he had concluded.

Seems Thiessen either didn’t bother to read Hirzy”s study prior to commenting on it, or she overlooked his glaring error, too.”

Fluoride/ISFR: The International Society for Fluoride Reasearch (ISFR) publishes the journal Fluoride and organises regular conferences. They provide an avenue for authors to publish anti-fluoride articles, and generally poor quality research from areas where endemic fluorosis is common which may not be acceptable in the normal scientific journal.

The Society is based in New Zealand and is registered here as a charity. Bruce Spittle is the treasurer and journal managing editor.

FTRC/Second look: The anti-fluoride organisation and web site Second Look as set up the Fluoride Toxicity Research Collaborative (FTRC). It appears to be a weak attempt to provide a front “scientific institute” for anti-fluoride activists who want to present themselves as scientific experts.

This reminds me of the creationist Biologic Institute set up by the intelligent design creationists at the Discovery Institute. Actually, the Intelligent Design “pretend” scientific journal Bio-complexity also reminds me of the anti-fluoride journal Fluoride.

The FTRC lists the following staff:

  • Russell Blaylock, M.D., FTRC Medical Director
  • Hardy Limeback, Ph.D., D.D.S, FTRC Principle Investigator
  • Phyllis J. Mullenix, PhD., FTRC Research Program Director
  • Aliss Terpstra, RNCP, FTRC Research Coordinator

So far they claim to have sponsored (financed?) 2 research papers only by Phyllis Mullinex. Have a read of them and make up your own mind about their quality.

Case Against Fluoride: This is Paul Connett’s book The Case against Fluoride: How Hazardous Waste Ended Up in Our Drinking Water and the Bad Science and Powerful Politics That Keep It There. It is usually treated as a holy scripture in the anti-fluoridation movement. His co-authors were H. S. Micklen and James Beck.

Connett is very proud of this book and relies on it to support his claim to be a “world expert” on fluoridation.

Fluorine in Medicine: This is the sole scientific paper that Paul Connett can claim authorship (actually co-authorship) to:

Strunecká, A. ., & Patočka, J.; Connett, P. (2004). Fluorine in medicine. Journal of Applied Biomedicine, 2, 141–150.

The senior author Anna Strunecká is also part of the anti-fluoride network illustrated above. I am personally very suspicious of the quality of the journal which published this paper – anti-fluoride people have a history of placing poor quality papers in suspect journals purely to attain some sort of scientific credibility. DonQuixoteJune2011

FIND: The Fluoride Information Network for Dentists is one of the local Fluoride Free’s astroturf organisations claiming about 8 members but only Stan Litras is active. Stan uses his FIND hat for his anti-fluoride press releases – such as the one promoting the “report” considered here.

NZ Tour of Don Quixote & Sancho Panza: Sorry, can’t help thinking of these two when the upcoming NZ tour of Paul Connett and Bill Hirzy is mentioned. They do seem to be charging local fluoridation windmills with meetings in Taupo and Auckland.

William Hirzy: He is Paul Connett’s wingman on the Don Quixote & Sancho Panza Tour. Unlike Paul’s sole co-authorship he actually has 2 published scientific papers related to fluoridation where he appears as senior author. (See Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis and Corrigendum to “Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis” [Environ. Sci. Policy 29 (2013) 81–86]“)

The “credibility” of his “expertise” on the subject is shown by the fact his second paper was necessary to correct the huge arithmetic mistake he made in the first paper!

Perhaps you can see why the Connett/Hirzy act brings Done Quixote and Sancho Panza to my mind.

Conclusion

The “report” is discredited even before addressing the arguments presented – simply because of the well-known anti-fluoride stance of all the authors and “peer-reviewers.” The diagrammatic network shows just how incestuous the “report” is. It is simply an attempt to put a “sciency” face on their political stand and their attack on the Royal Society Review.

As a scientific presentation it is a farce.

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November ’14 – NZ blogs sitemeter ranking Ken Perrott Dec 01

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pageview-visit-unique-blog-post

Image Credit: THE DIFFERENCE BETWEEN PAGEVIEWS & VISITOR


PLEASE NOTE: Sitemeter is still playing up but far fewer blogs are effected. It was still impossible to get the stats for a the blogs that I list below. Maybe more bloggers will shift to StatCounter or other counter.

No stats could be found for these blogs:

Works in progress This Mum Rocks
Weakly Whirled News Science Behind the Curtain
Two Minutes Sport Grumpollie
Wysiwygpurple’s Blog Louis’ Outlook
Stats Chat A conservative perspective
Webweaver’s world The Meaning of Trees

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

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for November 2014. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

Subscribe to NZ Blog Rankings

Subscribe to NZ blog rankings by Email

Find out how to get Subscription & email updates

Rank Blog Visits/month Page Views/month
1 Whale oil beef hooked 1776421 2981810
2 Kiwiblog 301119 522519
3 The Standard 194646 431100
4 The Daily Blog 160716 259736
5 Transport Blog 151471 155907
6 Liturgy 40475 58099
7 The Dim-Post 38134 51999
8 Throng New Zealand 33246 62749
9 NewZeal 27100 33823
10 No Right Turn 25643 34423
11 Sciblogs 22322 28420
12 On the Left 18739 30009
13 13th Floor 17506 23535
14 No Minister 17445 24253
15 Music of sound 15324 19297
16 Fields of Blood 15213 20774
17 Liberation 14899 21413
18 Homepaddock 13286 18159
19 Imperator Fish 11941 15946
20 Hot Topic 11591 18483
21 Aotearoa: A wider perspective 11496 14717
22 The REAL Steve Gray 10007 13610
23 Offsetting Behaviour 9526 13741
24 Tikorangi: The Jury Garden 9149 12217
25 TVHE 9139 9889
26 MandM 8997 10544
27 Open Parachute 8816 11653
28 Keith Johnson Wellington NZ 8542 8828
29 Bill Bennett 8136 11253
30 Talking Auckland 7738 10323
31 Autism & Oughtisms 6768 6837
32 Right Reason 6711 9694
33 Super Rugby Tips 6660 8198
34 Matte Shot 6481 13941
35 Dark Brightness 5870 5915
36 Lindsay Mitchell 5851 7475
37 Mousehouse 5547 9136
38 Chris no-frills 5459 7198
39 New Zealand Conservative 4566 5110
40 Reading the maps 4500 5965
41 Cycling in Christchurch 4379 5929
42 Anglican down under 4230 5481
43 Ultimate Student 3781 5171
44 Vomkrieg 3599 5004
45 Lance Wiggs 3296 4014
46 In the back of the net 3152 4997
47 Save our Schools NZ 3108 3801
48 Scepticon 3062 3436
49 Home education Foundation 2937 3875
50 Kiwi Cakes 2936 3935
51 Waiology 2855 3421
52 Quote Unquote 2696 3056
53 Open Parachute @ SciBlogs 2401 2700
54 Rodney’s Aviation Ramblings 2376 3114
55 OracleNZ by Francisco Munoz Alvarez 2364 2589
56 Windy Hilltops 2244 3413
57 Woodleigh Nursery 2239 4313
58 The Beehive Mandate 2173 3324
59 Otagosh 1957 3166
60 Canterbury Atheists 1902 2265
61 Social Media & the 2014 Election 1860 2415
62 Scotty Donaldson 1575 2485
63 Man of Errors 1539 1761
64 Off the couch 1473 2174
65 Pdubyah – a life just as ordinary 1451 2213
66 The Woolshed Wargamer 1410 2250
67 Keeping Stock 1342 1616
68 Eye on the ICR 1299 1932
69 ROI Marketing 1266 1785
70 Derek’s blog 1264 2017
71 Blessed Economist 1232 1553
72 Life Behind the IRon Drape 1214 2376
73 Undeniably Atheist 1210 1422
74 Put ‘em all on an island 1185 1431
75 Michael Jeans 1146 1633
76 Socialist Aotearoa 1137 1348
77 PM of NZ 1085 1289
78 misc.ience @ Sciblogs 1070 1201
79 ICT Teaching and Learning  1063 1466
80 Life is not a race to be finished first 1055 1448
81 james lin’s blog 1021 1031
82 From the Earth’s End 1000 1355
83 Code for Life 989 1184
84 Notes from the bartender 986 1127
85 roarprawn 906 1154
86 One Furious Llama 897 1141
87 AmeriNZ 889 1150
88 Stratford Aerodrome 872 1242
89 A communist at large 817 1108
90 Room One @ Auroa School 810 2220
91 Life of Andrew 755 841
92 A Bee of a Certain Age 748 913
92 Media Sport and Other Rantings 748 831
94 Episto 741 1268
95 Polit Ecol 684 814
96 Ideologically impure 666 758
97 Islamnz.com 625 992
98 Show your workings 624 863
99 Tales from a Caffeinated Weka 602 832
100 Sustain:if:able Kiwi 572 858
101 Artichoke 548 739
102 Kidney Punch  532 577
103 Brennan McDonald 510 619
104 Perissodactyla 506 712
105 Halfdone 503 600
106 Goings on at the Madbush Farm 492 603
107 Brad Heap 480 623
108 sticK 467 566
109 The IT Countrey Justice 465 552
110 Tararua District Library 460 573
111 My thinks 453 519
112 White & Black 452 573
112 Teaching the Teacher 452 573
114 Hitting Metal With A Hammer 439 573
115 Riddled 436 811
116 Room 5 @ Melville Intermediate School 420 660
116 Taradale Blog# 420 720
118 Cut your hair 407 416
118 Quietly in the backgroud 407 620
120 True Paradigm 405 560
121 Skeptiocon @ Sciblogs 392 439
122 Creative Voice# 390 480
123 Kutarere’s Blog  377 469
124 Webweaver’s world 373 407
125 Jo Blogs 371 613
126 Glennis’s Blog Page# 360 510
127 Software development and stuff 346 377
128 Get Out Gertrude! 340 417
129 The Little Waaagh! That Could 330 373
129 The Gentically Insane 330 390
131 Capitalism is bad 321 377
132 Stitchbird 318 595
133 eyeCONTACT 316 445
134 Tauranga Blog 312 335
135 ElephaNZa  309 313
136 Ruggerblogger 306 448
137 Dad4justice 305 323
138 AnneKcam
300 570
139 Samuel Dennis 298 330
140 Cimba7200’s thoughts 297 378
141 Glenview 9 294 335
142 Family integrity 290 359
143 Exile in New zealand 288 352
144 The Genetically Insane 286 344
145 goNZo Freakpower Brains Trust 280 305
146 Spatula Forum 274 306
147 Science in a van 270 352
148 kiwiincanberra 269 330
148 Wokarella 269 330
150 Upstage 255 471
151 The Fundy Post 253 310
152 $100 Dialysis 229 300
153 Four seasons in one 220 247
154 Anne Free Spirit 210 720
155 SmallTorque 209 289
155 Unity Blog 209 282
157 Helen Heath 207 212
158 Kiwidollar.com 204 241
159 Write to travel 196 250
160 MartinIsti Blog 189 286
161 Nelsonian’s life 180 360
161 Mountains of Our Minds# 180 210
163 Prior Knowledge  171 188
164 ZNO 162 199
165 Toni Twiss 155 156
166 Aphrodite rises 153 232
167 Rest Area 300m 150 186
168 UpsideBackwards 149 159
169 Crime Watch 148 212
170 High voltage learning during the Christchurch earthquakes 142 230
171 Canvassing for opinion 132 148
172 Dragonsinger 131 155
172 jo russ photo diary 131 170
174 At home with Rose 128 149
175 Looking in the square 121 142
176 kiwi simplexity 120 136
176 King’s High School Library 120 150
176 Manaia Kindergarten 120 240
179 The Well read Kitty 115 141
180 You’re Underthinking 106 139
181 Springston School Library Blog 98 130
182 Creative Collision 97 99
183 Lost Soul 96 100
184 Pointless and adsurb 92 106
185 Korero Pt England 90 90
185 Moving the crowd 90 90
185 John Macilree’s Weblog# 90 90
188 No Mum is an Island 86 171
188 John Macilree’s Blog 86 93
190 Millenium X 85 114
191 Sam Books and Thoughts 81 104
191 Politicalisation 81 83
193 Carolyn’s blog 79 103
194 Journey to a mini me 77 94
195 Shelly van Soest Artist 68 73
196 Sharlene says 64 95
197 Pt England Scribes 60 60
197 Digital learning 60 60
197 Virtual North 60 150
197 The Catalyst 60 90
197 Room 24, 2012 60 90
197 Nine Inch Nails 60 120
197 James McKerrow – Surveyor 1834-1919# 60 90
204 Something Interesting to read 58 63
205 New Zealand Indian Fine Arts Society 52 58
206 NZ First Youth 49 69
206 Whitireia Journalism School 49 55
208 Nathanael Baker 48 57
208 University of Otago, Law Library Blog 48 65
208 Social Policy Bonds Blog 48 68
211 Frontlawn 46 54
211 The First Fifteen @ TIS 46 58
213 Ellie Great 44 48
214 Oracle of Okarito 40 46
215 Busy Peas 37 48
216 TimG_Oz Blog 32 42
217 The Secret Life of Russ  30 33
217 ICTPD 30 30
217 Sleeping with books 30 30
217 Kiwi Chronicles 30 30
217 Making IT Happen 30 60
217 But Now 30 30
217 Football Tragic NZ 30 30
217 Anticipating future impacts 30 30
217 The Official Ebenezer Teichelmann Blog# 30 60
226 KJT 29 32
227 SageNZ 25 25
228 New Zealand female Firefighter calendar 23 24
229 Kiwiaventuras 21 23
230 Mad Young Thing 19 25
230 Einstein Music Journal# 19 26
232 round design 17 20
233 Palmerston North.ifo 15 17
234 Blair for Mayor 14 17
234 LoveColour Blog 14 19
234 TraLIS blog 14 18
237 A developing Geneticist 12 18
237 Moments of Whimsy 12 12
237 ah! New Year’s Resolution 12 12
237 ZL2UCX’s Blog 12 12
241 Here I stand 10 10
241 Augmented Ether 10 12
241 global village governance 10 11
241 amiria [blog] 10 26
241 SilverSpikes Photography  10 12
246 Relatively science 9 12
246 Porirua EMO 9 10
248 Think Beyond 8 9
248 Discovery Time 8 10
248 DMP Lead Free 8 8
248 Robtuckerpix’s Blog  8 12
252 ObservatioNZ 7 8
252 In this moment 7 8
254 Scott & Sarah Kennedy 6 6
255 Liminal Spaces 5 10
256 Uncensored 4 5
256 Moderation Blog 4 4
256 Rambling Reflections 4 4
256 Born on State Highway 1 4 4
256 Unknown Future 4 4
256 Yea or Nay 4 4
256 Fuller’s watch# 4 5
263 Tangled up in purple 3 7
264 Xenolexicon 2 2
264 Bob McKerrow – Wayfarer 2 2
264 pasture Harmonies 2 2
264 Roger Nome’s progressive Politics 2 2
268 Earth is my favourite planet 1 1

Creationist ‘audits’ science museum Ken Perrott Nov 27

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Imagine you are 10 years old and your crazy aunt is taking you out for a treat.

A crazy aunt can be fun. Problem is this aunt is also a creationist and she is taking you to the local natural history museum.

Well it never happened to me (not that I didn’t have a crazy aunt) but I imagine this is what it would be like.

The museum is the Chicago Field Museum of Natural History – looks great.

Thanks to: Christian Fundamentalist Goes To Science Museum To ‘Audit’ Its Liberal Bias, Makes Ass Of Self VIDEO.

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“Real” experts’ on climate change? Really? Ken Perrott Nov 26

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The Heartland Institute has produced a new propaganda poster on climate change. Here it is:

heritage poster

And this is what they say about it:

This poster presents clear and undeniable evidence that the debate is not over. Looking out from this poster are 58 real experts on the causes and consequences of climate change. Each of them refutes the existence of a “consensus of scientists” on the size of the human impact on climate, or whether it merits immediate action. Many of these experts say the threat is grossly exaggerated, often to advance a political agenda.

So they have raked up 58 “experts” – and how do they define “real experts?

Apparently their criteria is that they have spoken at one of the Heartland Institute’s climate denial conferences!

Sure they claim of these “real experts:”

“They include current and former professors of climatology, geology, environmental science, physics, and economics at leading universities around the world.”

But I have had a quick glance at the poster and at least 30 of these “real experts” really don’t have training or qualification in a field connected with climate. They include:

  • Journalists like James Delingpole and Christopher Booker.
  • Climate denial activists like Barry Brill, Christopher Monkton, Steve Gorham, Tom Harris and Joanne Nova.
  • Right wing “think tank” executives and fellows like Robert J. Bradley Jr., E. Calvin Betsner, Dennis Avery,Ron Arnold, Paul Driessen, Myron Ebell, Indur Golklany,  David W. Greutzer, Marlo Lewis, Marita Noon and James, M. Taylor.
  • Politicians like Vaclav Klaus, George Christenen and Roger Helmer.

There are also a few meteorologists (mainly weather forecasters), astronauts and economists.

Followers of the climate change debate will also be familiar with the remaining few on these who do have academic qualifications in relevant fields – and maybe some publications. They are the usual contrarians and mavericks who seem to bast in the glory of the promotion they get from climate change deniers.

“Real expert” – come off it.

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Water fluoridation and dental fluorosis – debunking some myths Ken Perrott Nov 24

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Dental fluorosis is really the only “negative” side effect of community water fluoridation (CWF). It occurs in non-fluoridated as well as fluoridated areas but is often a little more common in the fluoridated areas.

However, there is a lot of rubbish about dental fluorosis spouted by anti-fluoride propagandists. It is worth putting dental fluorosis into its proper context and debunking some of the misinformation they promote.

Here are some facts.

1: Diagnosis of dental fluorosis involves grading teeth into 6 levels:

  1. No dental fluorosis
  2. Questionable
  3. Very mild
  4. Mild
  5. Moderate
  6. Severe.

Here are some photos of the different grades

2: The moderate/severe grades are rare in areas considered for CWF and fluoridation does not increase prevalence of those grades of dental fluorosis. However, those more severe forms are more common in areas where dental fluorosis is endemic like parts of China, India and north Africa.

Dental and skeletal fluorosis is a real problem in these endemic areas, but it is not a problem in the areas where CWF is used.

The figure below contrasts data for prevalence of dental fluorosis in NZ and the USA where CWF is common with data for an area of endemic fluorosis in China.

DF-grades-graph

3: The first 4 grades (none – mild) are judged purely “cosmetic. In fact children and parents often judge the grades questionable – mild more highly than none. Research finds these milder forms of dental fluorosis often improve dental health related quality of life (Do and Spencer, 2007; Chankanka et al., 2010; Peres et al., 2009; Biazevic et al., 2008; Büchel et al., 2011; Michel-Crosato et al., 2005).

In contrast research shows that the moderate/severe grades of dental fluorosis have a negative impact on health-related quality of life(Chankanka et al., 2010; Do and Spencer, 2007; Chikte et al., 2001).

4: Anti-fluoride propagandists often lump all grades together – presenting dental fluorosis as always bad. It also enables them to produce high figures to inflate the apparent problem. That is deceptive.

5: Anti-fluoride propagandists often use data from countries like India and China where fluorosis is endemic in their arguments against CWF. The figure above shows this is also deceptive.

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