Tag Archives: SciBlogs

Fluoridation: Newsweek science journalism bottoms out

One of the worst pieces of distortion and misrepresentation of the Cochrane Fluoridation Review is that written by an anti-fluoridation journalist Douglas Main in Newsweek – Fluoridation May Not Prevent Cavities, Scientific Review Shows. It has, of course, been heavily promoted by anti-fluoride activists.

Dr Charles Payet*, a dentist from Charlotte, NC, USA, has debunked this Newsweek article report in his blog article More Bad Journalism on Fluoride which is also a guest blog at Making sense of FluorideOoops, [Newsweek] Did It Again.

Readers should go to these original posts to read the full article.  However, here are a few quotes from important sections:


Cochrane-fluoridation-quote

Yes, Water Fluoridation Has Been Proven Effective

Main starts off with an awful mischaracterization of the Review by stating that “…while using fluoridated toothpaste has been proven to be good for oral health, consuming fluoridated water may have no positive impact.” Let’s take that apart quickly.

First of all, there’s no disagreement that fluoridated toothpaste has been good for oral health. However, to state that consuming fluoridated water may have no impact is to completely ignore all historical evidence as to the dramatic decrease in dental decay once standardized CWF was implemented for the first time in Grand Rapids, Michigan 80 years ago. Not only that, the Cochrane Review directly contradicts Main’s assertion:

“Data suggest that the introduction of water fluoridation resulted in a 35% reduction in [DMF] baby teeth and a 26% reduction in [DMF] permanent teeth. It also increased the percentage of children with no decay by 15%.”

How About the Quality of the Papers Included?

Next up, Main claims that the Review “…winnowed down the collection to only the most comprehensive, well-designed, and reliable papers.” Is that accurate? Sigh……no. No it’s not. Let’s turn back to the Review to see what it says [emphasis mine]:

“For caries data, we included only prospective studies with a concurrent control, comparing at least two populations, one receiving fluoridated water and the other non-fluoridated water, with at least two points in time evaluated. Groups had to be comparable in terms of fluoridated water at baseline. For studies assessing the initiation of water fluoridation the groups had to be from nonfluoridated areas at baseline, with one group subsequently having fluoride added to the water. For studies assessing the cessation of water fluoridation, groups had to be from fluoridated areas at baseline, with one group subsequently having fluoride removed from the water.”

In other words, the Review only selected what are called “prospective” studies. While these are generally considered to be of higher quality better than cross-sectional studies, (performed at one point in time) for identifying causes, they are also much more difficult, and sometimes impossible, to do.  They are especially difficult today for one important reason when it comes to fluoride: because so many communities have already been fluoridated for a long time, it is very difficult to find one or more in which to set up a prospective study today, and the regulatory hurdles in doing so are enormous.

Therefore, it is false to claim that the Review only included the “most comprehensive, well-designed, and reliable papers.” In fact, the Review included one type of study regardless of their quality. Beyond that the Review’s discussion actually noted that more recent cross-sectional studies were often of better quality because computer use enabled better statistical analysis and consideration of confounding factors.


Payet also discusses the Cochrane judgement of study quality which Main and other anti-fluoride propagandists have misrepresented:


The Review judged quality using blinded randomised controlled studies (RCTs) commonly recommended for clinical drug trials as their baseline. However, they acknowledged this criteria is usually impossible to achieve in fluoridation studies because the assignment of subjects into a treated group versus a control group is outside the control of the investigator. Instead, researchers must use observational studies. Dr John Beal noted in his response to the Cochrane Health Group’s blog The value of cross-sectional studies on the dental benefits of water fluoridation – a response from Dr John Beal to the Cochrane Oral Health Group blog, the claim that cross-sectional, observational, studies, which were all excluded, are somehow of lower quality than RCTs, is false because a previous Cochrane Review said they’re similar!

“It is interesting to observe the conclusions of a different Cochrane review published last year (Anglemyer at al) which compared a range of study designs applied in various fields and concluded that, on average, “there is little evidence for significant effect estimate differences between observational studies and RCTs, regardless of specific observational study design”.

Well now, isn’t that interesting? The previous Cochrane Review specifically found that the 2 study types yield comparable results in terms of quality, but now this one says the cross-sectional ones aren’t good enough. As usual, Douglas Main ignores the previous one because it hurts his point. Admittedly, it would be nice if the Cochrane Review would apply more consistent standards in the selection and exclusion criteria to avoid confusion.


However, Dr. Payet has some criticisms to make of the Cochrane Review itself. It’s lack of proper qualification has been a godsend for cherry-picking anti-fluoridation propagandists:


Did you notice a certain pattern there? “Our confidence…is limited…” “We did not identify any evidence…” “There is insufficient information…” “The evidence is limited…” How in the world does Douglas Main turn that into “fluoridation doesn’t work!” As the saying goes, “The absence of evidence for something is not the same evidence for the absence of that something.”


Payet drives this point home in his conclusion:


So what’s the real take-home message of this particular Cochrane Review? Here’s all they really said: “Our exclusion criteria meant that only 9 studies were reviewed. Regardless of the quality of other studies done, we ignored them. Based on the extremely small study size and the strict criteria applied, all we can say is that more contemporary RCTs prospective studies are called for, because the ones available are old and might be biased.” That’s it! Main and his interviewees, however, go straight to, “OMG IT DOESN’T WORK WE SHOULD STOP IT NOW!” Perhaps this will make the point more clearly:
What-the-Cochrane-Review-Should-Have-Concluded


*Dr. Charles D. Payet has been a full-time practicing dentist in the city of Charlotte, North Carolina since graduating from the UNC Chapel Hill School of Dentistry in 1998. He blogs on the science and art of dentistry for all ages with a skeptical eye atwww.SmilesbyPayet.com and has recently published several articles on the safety and efficacy of fluoride in community water fluoridation, toothpaste, etc.
Similar articles

The bureaucratic solution to a problem

Sometimes satire is very close to the truth. Take this piece from The Shovel – Liberal Party Commits To Having 50% Women In Seats Shown On Camera By 2025:

parliament-women1-620x399

Tony Abbott says his party is serious about the advancement of women, and has set an ambitious target to have half of all seats shown on TV filled by women within five years.

“We are deeply committed to giving the impression that a high proportion of Liberal MPs are women,” Mr Abbott said.

“These are plum seats – not just any old seats. They’re right behind where the men and Julie Bishop stand when they’re giving a speech, so it’s not just a token gesture”.

He said women had an important role to play in the party. “The party’s women are crucial for the Federal Budget, for example. They’re on screen for the entire length of the budget speech, which is beamed to millions of Australians. They feature on the front page of the nation’s newspapers”.

A Liberal Party spokesperson said there was still work to be done to meet the target. “At the moment women make up 20% of Liberal MPs, and around 45% of those on camera, so we’re not quite there yet”.


So often on issues like these bureaucrats are interested only in appearances – not correcting the problem. This reminds me very much of the approach taken by Human Resources bureaucrats in dealing with the issue of laboratory safety in my earlier life when I was employed. They talked a lot about “signage.” To them the way to resolve (or appear to resolve) a safety issue was to put up a lot of signs!

Similar articles

 

Fluoridation: “Sciencey” sounding claims ruled unacceptable

chesterfield-cigarettes-science-advert

Today, “scientific” claims of advertisers and anti-fluoride propagandists can be just as misleading

Again and again I find myself getting really annoyed at the way science is used opportunistically in advertising. We are continually bombarded with claims that the effectiveness of a product is “scientifically proven.” Or that “scientists tell us” something which supports a product. Then there are those ads where actors dress up in white lab coats and wander around a fictional, but photogenic, laboratory while giving us a fairy tale explanation of the mechanism which makes their product so effective. And this misrepresentation is widespread – involving products from cosmetics and toothpaste to fertilisers.

This advertising exploits the credibility of science and scientists as trustworthy experts. Hence the use of white lab coats and sciencey sounding terminology. Even the citation of scientific literature, studies, and trials – with the full knowledge that the target audience has no way of checking these citations.

Many countries have bodies regulating what advertisers can and can’t claim. In New Zealand we have the Advertising Standards Authority(ASA). Our ASA welcomes complaints about advertising and its rulings can lead to adverts being removed. The complaint procedure is being used by members of the public. In 2014 the ASA received 871 complaints about 672 adverts – up 10% and 12% respectively from 2013.

The Society for Science Based Healthcare publicises the complaint procedure and has made many complaints itself on products like homoeopathic treatments and magnetic mattress underlays. One of their members, Mark Honeychurch, created a tool for accessing information from the ASA complaint database which provides useful information.

It turns out that one of the most complained about organisations is Fluoride Free NZ (FFNZ) – a group campaigning against community water fluoridation. It ranks 13th in  the  organisations having the most successful complaints made against them.

Bottom-organisations-FFNZ-full-screen

The data also shows that a relatively high proportion of those complaints against FFNZ have been successful. That tells me that the complainants have been able to present good arguments to support their complaints.

Anti-fluoride campaigners are well known to claim scientific support for their case. But analysis of their claims shows them to be based on misrepresentations and distortion of the science. They are a classic example of advertisers who opportunistically, but dishonestly, use science to promote their products.

I think the misrepresentation and distortion of science are widespread in advertising and the propaganda from activist groups like FFNZ. At times, the problem seems so immense it seems impossible to counter it. So it is great to see groups like The Society for Science Based Healthcare, and the many people making similar complaints, having this sort of success.

On the other hand, perhaps consumers are developing a healthy scepticism about advertising claims. That is also a good thing, as long as that scepticism doesn’t lead to denigration of the authority of science as the best way of understanding the world and testing claims.

That would be throwing out the baby with the bath water.

See alsoFluoride Free NZ ranks 13th worst NZ organisation by ASA complaints

Similar articles

Comparing the Cochrane and NZ Fluoridation Reviews

Sci Rev

New Zealand policy makers and health professionals should be wary about much of the current media comments on the Cochrane Fluoridation Review (Iheozor-Ejiofor 2015). Anti-fluoridation campaigners are misrepresenting it and distorting its findings. They are using cherry-picked quotes to make claims about the review which are just not true.

Some are even claiming (wrongly) that the Cochrane review findings conflict with this in the NZ Fluoridation Review (Eason et al., 2014). Or that, simply because it was published a few months after the NZ Review it somehow makes the NZ Review obsolete.

Review findings agree

Nothing could be further from the truth. The findings in the Cochrane Review do not conflict with those in the NZ  Review. And, because the Cochrane Review is much more limited than the NZ Review, policy makers and health professionals should not consider that as the only document required for their reading.

In particular, the Cochrane Review considered only questions of community water fluoridation (CWF) efficacy. It did not consider aspects related to health concerns which, of course, are always in the front of the minds of policy makers and health professionals.

I have done a side-by-side comparison of the two reviews and summarise their findings below

CWF efficacy

The Cochrane reviewers produced a quantitative estimate for the effect of CWF on dental decay, but only for children and used only studies satisfying their strict selection criteria (see Cochrane fluoridation review. I: Most research ignored). This unfortunately excluded more recent high-quality cross-sectional studies.

The NZ Reviewers did not produce an overall quantitative estimate but made more general conclusions.

Cochrane Review

NZ Fluoridation Review

Efficacy of CWF
“Data suggest that the introduction of water fluoridation resulted in a 35% reduction in decayed, missing or filled baby teeth and a 26% reduction in decayed, missing or filled permanent teeth. It also increased the percentage of children with no decay by 15%. These results indicate that water fluoridation is effective at reducing levels of tooth decay in both children’s baby and permanent teeth”. “Analysis of evidence from a large number of epidemiological studies and thorough systematic reviews has confirmed a beneficial effect of CWF on oral health throughout the lifespan. This includes relatively recent studies in the context of the overall reduced burden of caries that has resulted from the widespread use of topical fluoride products (e.g. toothpastes,  mouth rinses, and fluoride varnishes).”
Adult caries
No conclusions because of study selection limitations. “Although most studies of the effects of CWF have focused on benefits in children, caries
experience continues to accumulate with age, and CWF has also been found to help reduce the extent and severity of dental decay in adults, particularly with prolonged exposure. The long history of CWF around the world now means that many adults in late life have experienced a lifetime of fluoridation. The benefits for adult dental health include lower levels of root caries, and better tooth retention into old age.”
Socio-economic effects
No conclusions because of study selection limitations. “The burden of tooth decay is highest among the most deprived socioeconomic groups, and this is the segment of the population for which the benefits of CWF appear to be greatest. CWF appears to be most cost-effective in those communities that are most in need of improved oral health. In New Zealand, these include communities of low socioeconomic status, and those with a high proportion of children or Māori. A number of studies have suggested that the benefits of CWF are greatest among the most deprived socioeconomic groups, although the magnitude of the difference is uncertain.”
Effect of stopping fluoridation
No conclusions because of study selection limitations. “Stopping CWF leads to ~17% increase in caries experience”  cited from US Task Force on Community Preventive Services
Influence of fluoridated toothpaste, etc.
No conclusions because of study selection limitations. The beneficial effect of CWF on oral health is still shown in relatively recent studies illustrating the overall reduced burden of caries that has resulted from the widespread use of topical fluoride products (e.g. toothpastes,  mouth rinses, and fluoride varnishes). “In New Zealand, significant differences in decay rates between fluoridated and non-fluoridated communities continue to exist, despite the fact that the majority of people use fluoride toothpastes.”

Health issues related to CWF

Dental fluorosis is generally considered the only negative health results of CWF. Both Reviews did consider dental fluorosis, although the Cochrane review did not specifically compare fluoridated and unfluoridated areas – which is necessary to determine the effect of fluoridation on dental fluorosis prevalence. See Cochrane fluoridation review. III: Misleading section on dental fluorosis for a discussion of this and an estimate fo the effect of CWF on dental fluorosis calculated using the Cochrane data.

The Cochrane review did not consider any other health effects.

Cochrane Review

NZ Fluoridation Review

Dental Fluorosis
Only calculated effect of fluoride intake in dental fluorosis. The effect of CWF itself was not considered. However, this can be estimated by subtracting prevalence for unfluoridated region. These estimates indicate that dental fluorosis levels of aesthetic concern are similar in fluoridated and unfluoridated areas (see Cochrane fluoridation review. III: Misleading section on dental fluorosis).
.
“The prevalence of fluorosis of aesthetic concern is minimal in New Zealand, and is
not different between fluoridated and non-fluoridated communities, confirming that a substantial proportion of the risk is attributable to the intake of fluoride from sources other
than water (most notably, the swallowing of high-fluoride toothpaste by young children).
The current fluoridation levels therefore appear to be appropriate. It is important, however, that the chosen limit continues to protect the majority of high-exposure individuals.”
IQ effects
Not considered “We conclude that on the available evidence there is no appreciable effect on cognition arising from CWF.”
Cancer
Not considered “We conclude that on the available evidence there is no appreciable risk of cancer arising from CWF.”
Kidney
Not considered “Studies and systematic reviews have found no evidence that consumption of optimally fluoridated drinking water increases the risk of developing kidney disease. However, individuals with impaired kidney function experience higher/more prolonged fluoride exposure after
ingestion because of reduced urinary fluoride excretion, and those with end stage kidney
disease may be at greater risk of fluorosis.”

Conclusions

The Cochrane review is far more limited in its coverage than the NZ Fluoridation Review. It did not consider possible health effects (apart from dental fluorosis) which is an important aspect of the fluoridation controversy for health professionals and policy makers.

The two Reviews agree that CWF is effective for children, but the NZ Review also considered effectiveness for adults, the reduction of socioeconomic differences in oral health and effects of stopping fluoridation on tooth decay. It also considered more recent research than the Cochrane review, so was able to discuss possible reduction in the efficacy of CWF due to the use of fluoridated toothpaste in recent years.

The Cochrane review does not make the NZ Fluoridation  Review obsolete at all. Nor do its conclusions conflict with those of the New Zealand Review.

Policy makers and health professionals should pay attention to both reviews in making judgements of CWF efficacy, but will need to use the NZ Review for their judgements on possible health effects.

References

New Zealand Fluoridation Review:
Eason, C., & Elwood, JM. Seymour, Thomson, WM. Wilson, N. Prendergast, K. (2014). Health effects of water fluoridation : A review of the scientific evidence

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

Similar articles

Scaremongering and chemophobia

This poster/internet meme is making the rounds at the moment. A “true believer” asked for my comments on it as he seemed to think its arguments amounted to “gospel truth.”

misleading poster

So here are some comments:

“Natural” vs “man-made”

They are comparing  crystals found in nature with a processed chemical here. But if CaF2 (the ore fluorite) was meant be used for water treatment it would have to be processed to remove impurities (the natural ore is far from pure). The most effective way of removing contaminants is conversion to hydrofluoric acid and precipitation of calcium fluoride (CaF2). Ending up with a “man-made” product!

Some anti-fluoride campaigners seem to argue that fluoridation would be OK if the fluoridating agent used was CaF2. The contaminants present and need for purification are only two of the flaws in their argument. The low solubility of CaF2 is another flaw.

Incidentally, fluorosilicic acid is effectively purified in its manufacture because of the differing melting and boiling points of heavy metal fluorides and silicon tetrafluoride.

“Safe to hold” vs corrosive

True, concentrated fluorosilicic acid is much more corrosive than CaF2. But so what – this is an issue for those manufacturing, transporting and handling the source material. It is not an issue for consumers as drinking water does not contain either CaF2 or fluorosilicic acid.

By the way, the material safety data sheet for CaF2 says this:

“Potential Acute Health Effects: Hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Corrosive to eyes and skin. The amount of tissue damage depends on length of contact. Eye contact can result in corneal damage or blindness. Skin contact can produce inflammation and blistering. Inhalation of dust will produce irritation to gastro-intestinal or respiratory tract, characterized by burning, sneezing and coughing. Severe over-exposure can produce lung damage, choking, unconsciousness or death.”

And:

“Precautions: Keep locked up.. Keep container dry. Do not ingest. Do not breathe dust. Never add water to this product. Wear suitable protective clothing. In case of insufficient ventilation, wear suitable respiratory equipment. If ingested, seek medical advice immediately and show the container or the label. Avoid contact with skin and eyes.”

So the advice to those manufacturing, handling and transporting CaF2 is that it is not safe to hold  with bare hands!

Sparingly soluble in water

This is one of the disadvantages of CaF2 as a fluoridating agent as a saturated solution has a fluoride concentration of about 7.5 ppm. Just imagine the size of the container required to hold the quantities of CaF2 solution required for addition to a reservoir!

The high concentration of fluoride in liquid fluorosilicic acid (and the fact that it rapidly decomposes to produce the hydrated fluoride anion on dilution with water) provides a big advantage to it as a fluoridating agent.

Fluoride toxicity reduced by calcium

Yes, high concentrations of fluoride are toxic – although the concentration in community fluoridated water (CWF) (0.7 ppm) is quite safe. The toxicity of ingested fluoride at high concentrations can be reduced by the presence of calcium – because of the low solubility of CaF2.

But let’s be realistic, in the absence of other factors the addition of the appropriate amount of calcium would reduce the fluoride concentration to about 8 ppm. Far higher than the regulated maximum for CWF.

As for some other speculated protective action the calcium in CaF2 could provide – the calcium concentration in a saturated CaF2 solution is only about 7.5 ppm – and at the fluoride concentration used for fluoridated water CaF2 would support a calcium concentration of about 0.8 ppm. Any calcium from added calcium fluoride would be irrelevant compared with the natural calcium concentrations in drinking water. The graph compares these figures for several treatment stations in New Zealand –  see Calcium fluoride and the “soft” water anti-fluoridation myth for further information.

“Man-made waste product”

I have discussed the “man-made” fallacy above. Anti-fluoride campaigners love to describe fluorosilicic acid as a “waste product.”  But Wikipedia defines a waste product as:

“unwanted or unusable materials. Waste is any substance which is discarded after primary use, or it is worthless, defective and of no use”

By definition, then, the fluorosilicic acid used in CWF is not a waste product. It would be if it were disposed of without use – then so is food.

Anti-fluoride campaigners also seem to think that a by-product is somehow evil. This is because most fluorosilicic acid is produced as a by-product of phosphate ore processing. But, come on. Surely production and use of by-products is a desirable feature in judging the conservation aspects of a manufacturing process. And would phosphate chemicals be somehow evil if they were produced as a by-product of fluoride chemical manufacturer from phosphate ores?

Toxicity of “co-contaminants”

I discussed the problem of contaminants in “natural” CaF2 above and added that contaminants in the fluorosilicic acid used for CWF are very low.

But don’t take my word for it. Water treatment chemicals are regulated and the fluorosilicic acid used for CWF must pass rigid tests for the presence of contaminants. The regulations provide for maximum concentrations of contaminants and where a certificate of analysis shows these are exceeded the material is rejected by water treatment plants.

I discussed this in my article Fluoridation – are we dumping toxic metals into our water supplies? where I debunked this claim made by Fluoride Free NZ. I also provided some data on the chemical analysis of fluorosilicic acid samples. In the article Fluoridation: emotionally misrepresenting contamination I compare the real concentration of contaminants recorded in certificates of analysis with the regulated limits. It turns out that the fluorosilicic acid manufactured in Australia and New Zealand is very low in such contaminants – see figure below.

Of course – some opponents like to claim that any amount of contaminants is too much, despite the regulations. Well, if they want to pursue that argument then they must look at all sources of contamination. In many cases, they will find that there is a larger amount of contamination coming from the original water source, natural contamination, than from the water treatment chemicals

I showed this in the article Fluoridation: putting chemical contamination in context where I compared the amount of arsenic from different sources  in the Hamilton City water supply. The figure below from that article shows that natural levels of arsenic in the water source (the Waikato River) are much higher than the recommended levels for drinking water. Even after treatment (which reduces the arsenic levels to below the recommended maximum) the contribution of arsenic from this natural source is still much greater than the calculated contribution from the fluoridating agent used.

Conclusion

This bit of anti-fluoride propaganda is just another example of scaremongering relying on chemophobia and lack of information, even ignorance.

Similar articles

Talk of “mini ice age” bunkum

Grand_Solar_Min_500

The global mean temperature difference is shown for the time period 1900 to 2100 for the IPCC A2 emissions scenario (relative to zero for the average temperature during the years 1961 to 1990). The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the Maunder Minimum, and the black line shows observed temperatures from the NASA GISS dataset through 2010. Adapted from Feulner & Rahmstorf (2010). Credit: Skeptical science

Irresponsible and misleading reporting of scientific issues always annoys me. But I have been particularly annoyed with the recent headlines of the sort Now it looks like we’re in for an ice-age.” Here reporters have taken it on themselves to naively extrapolate research on the modelling of solar cycles to predictions about climate. Without considering any of the whole complex of inputs into climate change.

I would have thought  with all the controversy, and political and scientific discussion, about climate change over the last few years, that even the most junior reporter would recognise this complexity. That they would not make such naive extrapolations. And, particularly, they would completely ignore the role of the major recent inputs into climate change – anthropogenic atmospheric carbon dioxide.

The research sparking the media reports was published last year –  Sheperd et al., (2014). Prediction of Solar Activity from Solar Background Magnetic Field Variations in Cycles 21-23. This paper does not talk about climate – in fact, it doesn’t even include the word temperature. Nor did the Royal Astronomical Society press release referring to this modelling work (see Irregular heartbeat of the Sun driven by double dynamo).

Yet the  media article linked above claims the researchers say “fluid movements within the Sun will converge in such a way that temperatures will fall dramatically in the 2030s.”

Of course, if the solar model reported in this paper is accepted by other researchers it will be used in  modelling of future climate change. But we can get an idea of the likely effect of including this solar model from what  such modelling has shown in the past (see What is causing warming of the earth?)

Better still – the figure above is from Skeptical Science – using data from Feulner & Rahmstorf (2010). This shows the predicted future temperature of the earth modelled using current solar levels and the grand solar minimum of the sort predicted by Sheperd et al., (2014).

So much for the claim we are headed fo a “mini-ice age.”

See also:

A grand solar minimum would barely make a dent in human-caused global warming
Media Reports The World Will Enter A ‘Mini Ice Age’ In The 2030s. The Reverse Is True.
No, Earth is not heading toward a ‘mini ice age’
The ‘mini Ice Age’ media sensation – and the reality

Similar articles

Fluoridation: Beliefs about safety and benefits

Most people in the US believe  community water fluoridation (CWF) is safe and beneficial. Mork & Griffin (2015) report these  findings from a 2009 health survey in a new paper:

Mork, N., & Griffin, S. (2015). Perceived safety and benefit of community water fluoridation: 2009 HealthStyles survey. Journal of Public Health Dentistry.

Their analysis of the survey data, which had 4,556 respondents, indicated that:

“perceived CWF safety and benefits increased with CWF knowledge, perceived vaccine safety, and income.”

I summarise the reported results in  the following graphs.

Perceived safety

Most (55.3%) of the surveyed people agreed or strongly agreed that CWF is safe. Only 13.2% disagreed or strongly disagreed it was safe and 31.5 % were neutral on the question.

CWF-safe

Effect of information on CWF

However, the proportion of people believing CWF is safe was much higher in the group which had knowledge about CWF – about 70%. On the other hand, 41.3% of people with no knowledge about CWF still believed it to be safe.

CWF-inform

Unsurprisingly, the survey showed that almost half of people who claim childhood vaccination is unsafe also claim CWF is unsafe.

Perceived benefits of CWF

About 73% of the respondents believed that CWF had some benefit (57.3%) or great benefit (15.5%). Only 27% reported that CWF had no benefit.

CWF-benefits

Regression analysis of the survey data showed that perceived CWF safety and benefits increased with CWF knowledge, perceived vaccine safety and income.

Conclusions

These figures suggest that the recent prediction by Paul Connett, Executive Director of the Fluoride Action Network (FAN), that CWF in the US would disappear within 18 months is delusional. He appears to be carried away by FAN’s occasional victories in stopping or preventing fluoridation in local communities. He should take more notice of the overall figures which show increases in coverage of CWF in the USA in recent years.

However, there is still a sizable minority who believe CWF is harmful or has no benefit. Given that slightly over 40% of respondents in this survey reported they had no knowledge about CWF this provides scope for the misinformation and scientific distortions of anti-fluoride activists to have an effect.  There is still a need for oral health professionals, and supporters of evidence-based health policy, to campaign for CWF and counter the misinformation opponents promote.

The authors of this study concluded:

“Although only a minority of the US population perceived CWF as unsafe or providing no benefit to health, perceptions regarding CWF varied by knowledge of CWF and socio-demographic factors. Oral health promotion activities should consider these differing perceptions of CWF among groups to tailor oral health messaging appropriately.”

Similar articles

 

Climate change: Our time really is running out

This video features Professor Peter Wadhams, leading Arctic scientist Cambridge University, interviewed by Judy Sole, the University of Earth. It is very topical and very important.

Professor Wadhams argues that politicians are dragging their feet on the climate change issue. The approach of trying to limit CO2 emissions just won’t work. We have to put serious money into research methods of removing CO2 from the atmosphere and countering methane emissions from seabed permafrost.

He discusses the radical reduction of arctic ice due to global warming and warns that this is leading to release of methane gas from underwater seabed permafrost and this could have relatively rapid effects on global warming.

via Our time is running out – The Arctic sea ice is going! – YouTube.

Thanks to Richard for bringing my attention to this video.

Similar articles

Cochrane fluoridation review. III: Misleading section on dental fluorosis

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

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

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

Confusing language

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

Strictly, their calculations were reported correctly in the abstract:

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

And also in the Plain Language Summary:

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

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

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

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

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

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

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

What the review did on dental fluorosis

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

DF-Cochrane

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

DF-1

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

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

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

Estimating possible effect of CWF on dental fluorosis

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

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

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

Defining “dental fluorosis of aesthetic concern”

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

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

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

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

Conclusions

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

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

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

See also:

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

Similar articles

June ’15 – NZ blogs sitemeter ranking

comments


Big problems with Sitemeter

The problems with SiteMeter are even worse this month. No data could be obtained for about 50 blogs using SiteMeter. People have also reported strange results. So if you wish to query the information in the table I suggest you check out the data in the SiteMeter pages.

If you are using SiteMeter, and especially if you find you page isn’t included this month, I suggest you consider transferring to a more reliable counter like StatCounter. Have a look at the NZ Blog Rankings FAQs if you need help with this.


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 June 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers. Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

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