A bizarre study on the safety of water fluoridation

Summary

Triggered by an exchange with Mel Rader, I studied a New Zealand research paper that was supposed to show that water fluoridation is safe.  I found the paper rather bizarre because not only does the paper use an incomplete analysis which allows safety problems to go undetected; it also cites a second paper by the same research group which explains precisely why the analysis in the first paper is misleading.

So we are in a situation where we are accumulating evidence associating fluoride in drinking water with decreased IQ scores in children, and we are lacking studies that establish a safe level of fluoride exposure with respect to the developing brain.

Motivated by the precautionary approach that scientists advocate for protecting our children's vulnerable brains, the only conclusion I can draw is that now is the time to stop further expansion of water fluoridation and demand the needed safety studies.

Introduction

In March this year, I enjoyed having an exchange with Mel Rader, who is coordinating the campaign for water fluoridation in Portland, and Mel got me interested in a study from 1986 with the title "Exposure to fluoridated public water supplies and child health and behaviour" by Shannon, Fergusson and Horwood.  This study has been cited over the years in support for the safety of water fluoridation, and in our exchange, Mel pointed out:

One good study in epidemiology is worth more than a thousand bad studies, and this study is way better quality than all the Chinese studies that you are bringing up.

The Chinese studies are part of the accumulating evidence that I am concerned about because they show that fluoride in the drinking water is associated with disturbed brain development.  We don't know if the fluoride is the actual cause, and if it is, we don't know if there is a safe limit for fluoride exposure from drinking water for children.

So naturally, I decided to examine what I will call the "Shannon-Fergusson-Horwood safety study" more closely, to see if it held water and could help me to put my concerns to rest.

The study followed children from birth up to the age of seven years in different areas in the urban region of Christchurch, New Zealand.  Some of the areas had water fluoridation and others did not, and the study grouped the children according to how many years they had lived in one of the areas with water fluoridation.

The good news is that the Fergusson safety study does account for a number of possibly confounding variables that are important in IQ studies—such as socioeconomic status—and no significant difference was found in behavior measures.  The study concluded:

The results of this seven year study suggest that there is no evidence to indicate that that exposure to a fluoridated public water supply had any detectable effect on a large range of measures of childhood morbidity or problem behaviour, even when allowances were made for family social background.

Before we assess the safety study further, let us take a break and discuss Reference 6 of the study.

The Fergusson-Horwood dental health study

Reference 6 of the Shannon-Fergusson-Horwood safety study is another study called "Relationships between exposure to additional fluoride, social background and dental health in 7-year-old children", based on the same underlying study of the children in Christchurch, and is written by Fergusson and Horwood.  It illuminates the relationship between fluoride exposure and dental health in the Christchurch children.

Already in the abstract, the authors note the importance of taking the total fluoride exposure into account when analyzing the effects of fluoride:

This analysis showed that the level of exposure to additional fluoride was a complex variable influenced by at least three factors: a) the use of fluoride toothpaste; b) the child's length of residence in a fluoridated area; c) the length of time for which the child had been provided fluoride tablets.

The analysis showed that the important variables with associations to dental health scores are the number of years the children were exposed to fluoridated water,  the number of years the children were given fluoride tablets, and social background.  The longer the children were exposed to fluoride (through water or tablets), the better the dental health scores were.  Additionally, better social background was associated with better teeth.

In addition, the paper found relationships between the use of fluoride tablets and exposure to fluoridated water.  Unsurprisingly, longer time in a water-fluoridated area was associated with shorter time of using fluoride tablets.  I presume that parents in non-water fluoridated areas were recommended to compensate the lack of fluoride in the water by giving their kids fluoride tablets.  The paper expresses this as:

This correlation reflects the fact that as duration of residence in a fluoridated region increased, use of fluoride tablets decreased.

The negative correlation between fluoride exposure from the water and from tablets can be discerned in the paper's Table 1:

In particular, no parents in the study whose children lived in a water-fluoridated area for the whole period gave their children any fluoride tablets.

Another relationship that the paper found was between social background and the usage of fluoride tablets: higher social background was correlated to more years of tablet use.  Perhaps parents with higher social background were more inclined to follow public health recommendations and get fluoride tablets.

Table 1 also gives an indication of the importance of trying to take the total fluoride exposure into account when assessing health effects.  "dmf" score (number of decayed, missing or filled teeth) association was much more pronounced when taking both water and tablet exposure into account, compared to when one was looking only at water fluoridation, for example.  This can be seen by looking at the "Total" row in which tablet exposure is ignored: the dmf scores do not drop as clearly with increased exposure to fluoridated water.

So, rightly, the authors note in the discussion section of the paper (my emphasis):

This 7-yr study serves to illustrate some of the complexities which arise in assessing the exposure of children to additional fluoride.  In particular, for this cohort, additional fluoride was provided by fluoride toothpaste, fluoride tablets and fluoridated water.  While fluoride toothpaste was almost universally used, children had varying exposure times to both fluoridated water and tablets.  A major methodological implication of this result is that exposure to fluoride is a complex variable which requires measurement over a number of sources and time.  Failure to recognise this fact may lead to specious conclusions being draw in cross-sectional studies which examine only a single source of fluoride at a given time.  Typically such analyses are likely to have reduced sensitivity as a result of inaccuracies in the measurement of the sources of fluoride and varying exposure times to these sources.

In short: if you look at only a single source of fluoride, your analysis may fail to show an effect, which may lead to misleading conclusions. It was particularly important to take fluoride exposure through both water and tablets into account, because of the inverse association between the two.  For example, if one only looked at water fluoridation exposure, it could be the case that the total exposure to fluoride was roughly the same regardless of the number of years that the children lived in a water-fluoridated area, because parents compensated with fluoride tablets.

Now, let's turn back to the research group's safety study.

The Shannon-Fergusson-Horwood safety study

The introduction of the safety study gives a hint of a possible reason for its publication:

There is continuing debate about the advantages and liabilities of the fluoridation of public water supplies.  The advantages in terms of reduction of dental caries have been well documented but, on the other hand, the local anti-fluoridation lobby has always raised fears that fluoride may have unforeseen health consequences.

Perhaps the paper was meant to assure the public that there were no reasons to be concerned about adverse effects of water fluoridation.  And we are reassured already in the abstract, which noted:

This study showed no association between exposure to fluoridated water and a large range of measures of child health and behaviour taken during the period from birth to seven years, even when the possible effects of family social background were taken into account statistically.

The details were illustrated in the paper's Table 1, which showed that various health effects were not associated in a statistically significant manner (NS = not significant) with the number of years that the children had been exposed to fluoridated water:

The table shows that none of the adverse health effects that were studied had any association with the exposure time to fluoridated drinking water.

But wait a second—what on earth happened with exposure to additional fluoride?  Where are the fluoride tablets taken into account?

The bizarre truth is that the total exposure is not mentioned at all in the Shannon-Fergusson-Horwood safety study.  Not a single word about tablets.  I found it particularly confusing that only exposure to fluoride through the drinking water was included since two of the authors the same year published a paper where they pointed out that "[f]ailure to recognise this fact may lead to specious conclusions being draw in cross-sectional studies which examine only a single source of fluoride at a given time."

I contacted co-author John Horwood and he was kind enough to explain that the intent was not to estimate total fluoride exposure, but rather the consequences of exposure from the source where there was no individual choice, namely the drinking water.

I found this explanation even more confusing, since I wouldn't expect the human body to be able to distinguish between mandatory and non-mandatory exposure to fluoride when it comes to potential health effects.

So why did the safety study not find any difference in adverse health effects when looking at the number of years the children were exposed to fluoride from the water?  Was it because there are no such effects, or was it because there actually were effects, but the compensation with fluoride tablets made the total exposure to fluoride so similar that those effects could not be detected?

It would be interesting to revisit the original data and see what would come out of it if one attempted to account for total fluoride exposure.

Perhaps the analysis would still show that there were no negative health effects.  Such a result would at least rest on a somewhat stronger foundation than what was presented in the original paper.

But perhaps the analysis would show some less convincing and less desirable results that could have fueled the "anti-fluoridation lobby" in New Zealand back in the 80s.  And perhaps the safety paper would not have been used so much as an argument (for example by the Australian Dental Association in their FAQ) that water fluoridation is safe and "worth more than a thousand bad studies".

In search of a good safety study, showing the safe limit

With the accumulating evidence showing an association between fluoride in the drinking water and decreased IQ test scores, we need to see a good safety study that can show us that it must have been something else behind what looks like disturbed brain development and not fluoride in the drinking water.

Such a study should take the actual fluoride exposure into account, and it should look at the exposure during the first critical months of brain development before the blood-brain barrier is fully developed at six months' age.  Before the blood-brain barrier is in place, fluoride may enter the brain where it potentially could disturb the rapid brain development that is taking place.  The pregnant mother's exposure to fluoride must be estimated, and one must note to what extent the infants were breast fed or formula fed (breast feeding would have eliminated almost all fluoride exposure compared to formula, since the milk-production mechanism actively reduces fluoride transfer from plasma to milk).

One should also determine what safety factor would be acceptable.  Due to individual variation in exposure to fluoride, it is not enough to learn that "optimal" exposure through food and fluoridated water does not cause detectable brain development disturbance.  Since the brain can only be developed once and any disturbance is irreversible, we need a margin of safety and conduct a study that shows that a significantly higher fluoride exposure than "optimal" is safe.  Such higher fluoride exposure may not be present in the U.S., so we may have to conduct the study abroad.  We need to learn: where is the safe limit for fluoride exposure to our children's developing brains?

Until we have conducted such a study, the prudent thing to do is to heed the precautionary approach that Grandjean and Landrigan motivated in their 2006 Lancet review (my emphasis):

Prevention of neurodevelopmental disorders of chemical origin will need new approaches to control chemical exposures. The vulnerability of the human nervous system and its special susceptibility during early development suggest that protection of the developing brain should be a paramount goal of public health protection. The high level of proof needed for chemical control legislation has resulted in a slow pace of interventions to prevent exposures to lead and other recognised hazards. Instead, exposure limits for chemicals should be set at values that recognise the unique sensitivity of pregnant women and young children, and they should aim at protecting brain development. This precautionary approach, which is now beginning to be used in the EU, would mean that early indications of a potential for a serious toxic effect, such as developmental neurotoxicity, should lead to strict regulation, which could later be relaxed, should subsequent documentation show less harm than anticipated.  As physicians, we should use prudence when counselling our patients, especially pregnant mothers, about avoidance of exposures to chemicals of unknown and untested neurotoxic potential.

Our current situation is that we are accumulating indications that fluoride may disturb brain development, and we have no studies showing where the safe limit is under which there is no harm.  Therefore, according to the precautionary approach, now is the time to stop further expansion of water fluoridation and demand the studies that we need.

The disturbing silence from Upstream Public Health

Lately, I have realized that Portland public-health policy makers are shockingly ignorant about children's unique vulnerabilities to toxic chemicals.

Mel Rader, coordinator of the water fluoridation coalition in Portland has failed to give a satisfactory explanation why he and Upstream Public Health (where he is co-director) are ignoring the accumulating indications that fluoride in the drinking water impairs brain development in children.

Even more disturbing is that Damien Fair, who is chairing the board at Upstream Public health, has not appeared to take the indications seriously.  Damien is a cognitive neuroscientist at OHSU and is listing cognitive brain development as one of his research interests.

According to records from a meeting at the Portland City Council, Damien completely dismissed the Harvard Review, for example by questioning the use of IQ as a measurement method.

Such a treatment is simply not serious, and Damien is ignoring a whole body of research that made us understand the neurotoxic effects of lead paint and leaded gasoline.  Given that Damien is talking about problems within his area of expertise, he should know better.

I am waiting for Damien Fair to publicly give a serious explanation how it comes that water fluoridation does not violate the precautionary approach* that is needed to protect our children's brain development.  Damien needs to address the concerns that senior author of the Harvard Review Philippe Grandjean voiced:

At the same time, many millions of people receive drinking water with fluoride concentrations that are clearly toxic. Benefits and risks, and their dependence on dose and individual susceptibility, need to be carefully evaluated, also in regard to alternative interventions, when relevant.
Chemical brain drain should not be disregarded. The average IQ deficit in children exposed to increased levels of fluoride in drinking water was found to correspond to about 7 points – a sizable difference. To which extent this risk applies to fluoridation in Wichita or Portland or elsewhere is uncertain, but definitely deserves concern.

Is Upstream Public Health in a complete state of denial?  As long as Damien Fair is silent about this issue, I can only assume that something is seriously wrong with Upstream Public Health.

*Here is the precautionary approach explained by Grandjean and Landrigan:

Prevention of neurodevelopmental disorders of chemical origin will need new approaches to control chemical exposures. The vulnerability of the human nervous system and its special susceptibility during early development suggest that protection of the developing brain should be a paramount goal of public health protection. The high level of proof needed for chemical control legislation has resulted in a slow pace of interventions to prevent exposures to lead and other recognised hazards. Instead, exposure limits for chemicals should be set at values that recognise the unique sensitivity of pregnant women and young children, and they should aim at protecting brain development. This precautionary approach, which is now beginning to be used in the EU, would mean that early indications of a potential for a serious toxic effect, such as developmental neurotoxicity, should lead to strict regulation, which could later be relaxed, should subsequent documentation show less harm than anticipated.  As physicians, we should use prudence when counselling our patients, especially pregnant mothers, about avoidance of exposures to chemicals of unknown and untested neurotoxic potential.

The chilling effect of endorsements

The coalition that is promoting water fluoridation in Portland has published a video that I found quite interesting: Portland Fluoride: Facts Vs Fiction.

The video features Portland Pediatrician Dr. Phil Wu at Kaiser Permanente, and he debunks false and misleading anti-fluoride claims—according to the description.  Dr. Wu addresses claims made by another pediatrician, Dr. Yolanda Whyte, and I encourage you to watch the video and then read on!

The words of doctors carry extra weight and we put an immense amount of trust in doctors' assessments every time we visit their clinics.  We trust that our doctors are staying up to date with science within their field of expertise in order to offer us the best possible care.

Therefore, I was surprised by Dr. Wu's dismissal of the research that associate fluoride with reductions of children's intelligence.  Let me quote directly from the video, starting at 3 minutes and 4 seconds:

Dr. Whyte says:

My concern is based in part in a large body of research finding that modestly elevated levels of fluoride can reduce a child's intelligence.

Dr. Wu responds:

This may be the most serious misrepresentation of all.  This article, often cited by anti-fluoride activists, reviewed studies from China, Mongolia and Iran, including water samples in which the natural fluoride levels were 400 to 1200 percent higher than the recommended level for fluoridating water in the U.S.  The Harvard researchers who examined these fluoride IQ studies took the unusual step of publicly distancing themselves from the claims that anti-fluoride groups were making about these studies.

The video then shows the following quote:

Harvard scientists: Data on fluoride, IQ not applicable in U.S.
"These results do not allow us to make any judgment regarding
possible levels of risk at levels
of exposure typical for
water fluoridation in the U.S.,"

 A quick Google search shows that the quote stems from a news article in The Wichita Eagle.  This article is often cited by water fluoridation proponents, to the point that Philippe Grandjean, senior author of the Harvard study, took the unusual step to write on his blog about the misrepresentations from The Eagle.

On his blog, Dr. Grandjean spells out something that I think should be hard to miss for anyone who has read and understood the Harvard study:

Chemical brain drain should not be disregarded. The average IQ deficit in children exposed to increased levels of fluoride in drinking water was found to correspond to about 7 points – a sizable difference. To which extent this risk applies to fluoridation in Wichita or Portland or elsewhere is uncertain, but definitely deserves concern.

Now, I can understand that laymen who were concerned about the reports around fluoride and IQ would put their concerns to rest after seeing the Wichita Eagle statements.

But I would expect something different from a pediatrician who speaks out publicly on the issue of fluoride safety than simply dismissing a potential neurotoxic hazard to our children by referring to newspapers in Kansas.  That shows a complete lack of diligence and is unprofessional beyond comprehension.  In particular since Dr. Wu noted that it was an "unusual step" for the authors of the IQ study to publicly distance themselves.  Think about it for a second.  Why would the Harvard researchers attempt to publicly correct misrepresentations of their research by using a Kansas newspaper?  The obvious step for Dr. Wu would have been to contact the authors directly to confirm the newspaper claims.

Dr. Wu was one of the experts responsible for the presentation before the Portland City Council in September 2012, and a week later the Council decided that water fluoridation was safe and effective and approved an implementation plan that will affect 900,000 people in an around Portland.

I am wondering to what extent the Council based their decision on rumours in newspapers instead of current research.  The thought is chilling.

My interpretation of slide 44 in the presentation is that the use of fluoridated water in infant formula is endorsed by the American Academy of Pediatrics and the Oregon Pediatric Society (where Dr. Wu is on the board of directors).  This ought to show an overwhelming assurance that fluoridated water is safe for our children, but from what I have seen in Dr. Wu's video, I am left with zero confidence in any of their endorsements regarding fluoride in the drinking water.

From now on, I believe in policy making based on evidence rather than endorsement.

I am looking forward to seeing statements from Dr. Wu, the American Academy of Pediatrics, and the Oregon Pediatric Society where they specifically address the results from Dr. Grandjean, and explain why we do not need to establish a safe limit for fluoride in drinking water which would guarantee that our children do not suffer from chemical brain drain.

At least until then, it would be completely irresponsible to support further expansion of community water fluoridation.  And until then, my motto will be:

An apple a day keeps the doctor away.

Take your doctor's words with a grain of salt.

Why the Portland water fluoridation initiative keeps me awake at night

Since August 2012, I have been trying to get answers to my questions regarding community water fluoridation.  That's when I read in the Oregonian that there was a coalition who was pushing for adding fluoride to Portland's drinking water in order to reduce tooth decay.

I had questions related to safety (especially dental fluorosis and the potential link between fluoride and decreased IQ) and tried to engage people involved in the initiative in a dialogue to get some answers, without much luck.

So I was delighted when I finally found a forum where devoted dental health professionals like Kurt L Ferré would listen to my concerns.  In a thread on the coalition Healthy Kids Healthy Portland's Facebook site, I was able to explain in detail why it is relevant to establish a safe level of fluoride in drinking water with respect to children's IQ, and why there are important lessons to be learned from our history with lead poisoning in the U.S.

Unfortunately, the dialogue came to an abrupt ending when all my comments in the thread suddenly were removed.  I was tremendously disappointed.

Fortunately, I had saved the thread on my computer, and I am sharing the part from where I joined the thread below.  If you are interested in stuff like the Null Hypothesis, the importance of population-based studies, what impact a small shift of the Bell curve can have, or just want to see how emotional the discussion about water fluoridation can get, read on!

The Facebook thread

[...]
 

Healthy Kids Healthy Portland
No. Fluoride occurs naturally because of mineral deposits. The fluoridation process is not shown to have negative environmental consequences, as evidenced by the 65 years of its use around the US.

Feb 7 at 9:55pm · Like

Alex Garcia
Uranium naturally occurs and it has polluted our country in the evidence of the last 65 years.

Feb 7 at 10:28pm · Like

Kåre Hultén
Nice non sequitur, Alex.

Feb 7 at 11:08pm · Like

Nate Osborne
It takes two to Tango

Feb 8 at 8:47am · Like

Magnus Carlsson
Kåre Hultén, I think Alex has a point though. The fact that a mineral is naturally occurring and has been used for 65 years does not imply that its use is a safe practise. A relevant parallel is the use of lead in gasoline and paint, a practice that it took decades after evidence showed up before U.S. policy finally caught up. Many European countries had banned lead paint 50 years earlier. We still have not established a safe limit for fluoride in water with respect to children's IQ, have we? http://www.jci.org/articles/view/28232

Feb 8 at 11:31am · Like · Edit

Kåre Hultén
Nice attempt at character assassination of fluoride, Magnus. Especially since lead is a harmful toxin, with NO health benefits WHATSOEVER.
Furthermore, lead has never been a nutrient, nor has it ever been used as a public health measure to treat disease, and, therefore, associating lead with fluoride is just a thinly veiled attempt at poisoning the well and strawmanning.

 By the same line of reasoning, fluoride would have to be removed from toothpaste, mouth rinse, bottled mineral water, tea (I could go on). Last I checked, fluoride was a selling point in dental care products.

And like so many times before, you’re JAQ-ing off with your last question: “We still have not established a safe limit for fluoride in water with respect to children's IQ, have we?”.
As far as I know, Magnus, you haven’t demanded the removal of all naturally occurring fluoride from the Bull Run water supply.

Clearly, you have spent a great deal of time studying water fluoridation. But, for someone who claims to be undecided, you seem remarkably inept at finding pro fluoride articles (not that there’s any shortage of them!). Your ineptitude is only balanced by your keen aptitude in finding, and clinging on to, anti fluoride material.
And you cling to the Harvard IQ-study like shipwrecked cling to the floating remains of a sunken ship. A study where the authors themselves, specifically and unequivocally, state that their Chinese meta analysis cannot reasonably be used against the public health fluoridation programs in the US.

I don’t pretend to know everything about fluoride. That’s why I ask healthcare professionals, with relevant fields of expertise, when forming an opinion.

Maybe you should do the same?

ETA: I’m sorry if his comes off as hard and uncompromising, but Magnus and I go way back. I just find his debating style disingenuous and unpalatable, and, for the sake of our friendship, I’ve asked him not to discuss this directly with me, but he keeps calling me out. I guess I now know what that friendship was worth…

Feb 8 at 7:45pm · Like · 1

Healthy Kids Healthy Portland
We agree that lead and uranium are non-sequitors from the actual issue at hand. We also want to foster respectful dialogue here. Surely we can all agree on that?

Feb 8 at 7:52pm · Like · 1

Magnus Carlsson
Kåre Hultén - I am so sorry that I haven't clearly expressed to you last week that I indeed find the idea of water fluoridation questionable, after I started studying the research last summer. I am also truly sad that I have to let you down - I am not asking you any more questions privately, but I cannot stay away from public discussions in the matter. I am concerned about the safety of the practice, and I get more and more frustrated over how difficult it is to openly discuss fluoride safety research with people who propose water fluoridation.

This is why I may sound like a broken record when I keep referring to the Harvard IQ study. My conclusion after reading the study is that neurotoxicity of fluoride should be better researched, and I was intrigued when Healthy Kids Healthy Portland mentioned much higher quality studies that show no relationship between optimal fluoridation and any neurological changes. I keep asking for the references to these studies which could help put the matter to rest, but I get no response.

One thing that I wanted to point out with my reference to the lead article is that we *might* have a situation where water fluoridation is beneficial for dental health, but also results in a some non-obvious negative neurological impact. For lead, it was very tricky to establish its negative impact on children's IQ and turn the evidence into policy changes. The responsible thing to do in the case of water fluoridation is to find out the answer now, either by digging up the missing piece of research, or by conducting it.

So I would like to respectfully disagree that lead is a non sequitur in this discussion. Since we are already quoting the authors of the Harvard IQ study from sources outside the actual paper, let me finish with another one: “Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain,” Grandjean says. “The effect of each toxicant may seem small, but the combined damage on a population scale can be serious, especially because the brain power of the next generation is crucial to all of us.” http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/

Feb 8 at 11:10pm · Like · Edit

Healthy Kids Healthy Portland
First off: That study was not funded by Harvard. It was a project of several doctors who attended Harvard. The methodology they used is questionable, and they have publicly denounced the use of that study in discussion of fluoridation: http://kansas.com/2012/09/11/2485561/harvard-scientists-data-on-fluoride.html

Harvard scientists: Data on fluoride, IQ not applicable in U.S. | Wichita Eagle

kansas.com

Feb 8 at 11:13pm · Edited · Like

Magnus Carlsson
Healthy Kids Healthy Portland - thank you for providing the link to the article. I don't understand why the study cannot be used in a discussion about fluoridation and its underlying research or lack thereof. To quote the article:

'Two of the scientists who compiled the Harvard study on fluoride said it really doesn’t address the safety of fluoridation levels typical of American drinking water.

“These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S.,” the researchers said in an e-mail response to questions from The Eagle. “On the other hand, neither can it be concluded that no risk is present.”

The researchers noted that the fluoride levels they studied were much higher than what is found in fluoridated water in the United States and recommended “further research to clarify what role fluoride exposure levels may play in possible adverse effects on brain development, so that future risk assessments can properly take into regard this possible hazard.”'

Feb 8 at 11:26pm · Like · Edit

Healthy Kids Healthy Portland
The study they conducted was on children being exposed to much-higher-than-optimal fluoride content in water. We support the optimal fluoridation of Portland's water to 0.7ppm.

Feb 8 at 11:30pm · Like

Magnus Carlsson
Thank you for your response. Can you also provide the reference to the higher quality studies that show no relationship between optimal fluoridation and any neurological changes, that you referred to earlier?

Feb 9 at 12:06am · Like · Edit

Healthy Kids Healthy Portland
The 2006 NRE study on the EPA's drinking water standards for fluoride is where the recommendation of 0.7 - 1.2ppm comes from . http://www.nap.edu/catalog.php?record_id=11571

Fluoride in Drinking Water: A Scientific Review of EPA's Standards

nap.edu

Feb 9 at 12:11am · Like

Healthy Kids Healthy Portland
Here's the CDC statement on that report: http://sboh.wa.gov/Meetings/2010/06-09/docs/Tab16i-Fluoridation_CDC_Statement.pdf

Feb 9 at 12:11am · Like

Magnus Carlsson
Thanks again, Healthy Kids Healthy Portland, I really appreciate that you take the time!

I must have have misunderstood your earlier comments when you talked about the mixed quality of the Chinese IQ studies that the Harvard meta-analysis covered. You were referring to a much higher quality study of optimal fluoridation and neurological changes. However, the 2006 review of EPA' standards does not provide any such study in itself, it is a review of the scientific basis for EPA's maximum-contaminant-level goal (MCLG) of 4 mg/L. (The review's main conclusion was that the MCLG should be lowered, since its current level does not protect children against severe dental fluorosis, and is not likely to protect against bone fractures, page 3.)

The review's findings regarding fluoride's neurotoxicity is in alignment with the Harvard IQ study: there is a number of Chinese studies of quality that it found difficult to assess, but they are consistent in that they correlate fluoride exposure with IQ deficits (page 8 ). Just like the Harvard study, the NRC review finds that there is ground for additional research on the effects of fluoride on intelligence.

This brings me back to what I was asking for before: I think the responsible action now is to demand high quality studies that establish a safe limit for fluoride in drinking water, so that we know it doesn't impact children's IQ.

Feb 9 at 11:31am · Edited · Like · Edit

Magnus Carlsson
Kåre Hultén brought up some more interesting questions when I made my controversial parallel to the history of lead. Let me try to rephrase them, and please correct me if I am wrong.

As Kåre mentioned, we are already exposed to fluoride from the Bull Run, mineral water, tea, dental care products, and so on. The implicit question is: if we now find out (Heaven forbid) that fluoride has neurotoxic effects, shall we just stop drinking and eating? How could it be possible in the first place, that we have a toxin everywhere?

It might not be that bad for grown-ups. But the brain is extra sensitive to neurotoxins during its initial critical development. When it comes to fluoride in the drinking water, there is an important subgroup: infants who are given formula instead of breast milk. By adjusting the drinking water to optimal fluoride levels, we have a 600% increase in the amount of fluoride these infants get exposed to through the water (I believe Bull Run today has 0.1 mg/L, perhaps someone can confirm, and we are targeting 0.7 mg/L). We don't know whether or not that increase has any effect on children's IQ.

The 0.7 mg/L exposure that formula-fed infants receive should also be compared with the 2-8 microgram/L that breast-fed infants receive, a difference in orders of magnitude. There is an active plasma-milk barrier that keeps fluoride several times lower in the mother's milk compared to the mother's blood. In the paper below, it was suggested that the newborn is actively protected against fluoride exposure from the breast milk. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1506856/

No evidence of transfer of fluoride from plasma to breast milk.

ncbi.nlm.nih.gov

Feb 9 at 4:49pm · Like · Edit

Healthy Kids Healthy Portland
Infants growing up currently in Vancouver and Beaverton, where the water is fluoridated, do not show any evidence of problems with fluoride intake. According to this study, fluoride is known to cross the placenta because it is a vital mineral nutrient in the development of milk teeth. http://www.ncbi.nlm.nih.gov/pubmed/2182701

[The passage of fluorid... [J Gynecol Obstet Biol Reprod (Paris). 1990] - PubMed - NCBI

ncbi.nlm.nih.gov

Feb 9 at 7:06pm · Like

Magnus Carlsson
Thank you for the link, it sounds interesting! Regarding infants in our fluoridated areas: without proper case studies we cannot know if IQ is affected.

Feb 9 at 7:20pm · Like · Edit

Healthy Kids Healthy Portland
This is a misleading claim, Magnus. The 2006 NRC report exhaustively looked into the total effects of fluoride on human health and found no reason to be concerned for IQ.

Feb 9 at 7:33pm · Like

Magnus Carlsson
I am sorry if I come across as misleading! Let me quote from Page 8 of the 2006 NRC report I was referring to before:

"A few epidemiologic studies of Chinese populations have reported IQ deficits in children exposed to fluoride at 2.5 to 4 mg/L in drinking water. Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence."

Can you point me to specific pages in the report that can help me understand that it found no reason to be concerned for IQ?

I am sorry for bringing up the 2012 Harvard IQ meta-analysis once again, but it reports on Page 16:

"Although the studies were generally of insufficient quality, the consistency of their findings adds support to existing evidence of fluoride-associated cognitive deficits, and suggests that potential developmental neurotoxicity of fluoride should be a high research priority."

It is the collection of evidence together with the lack of high-quality IQ studies that I am concerned about. Please help me understand what you find misleading in my line of reasoning, because I find this important. Thank you!

Feb 9 at 8:09pm · Like · Edit

Kurt L Ferré
Magnus, you are using the typical ploy of the anti-fluoride activists: that being the use of the Null Hypothesis.

Null hypothesis - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Null_hypothesis "The null hypothesis can never be proven. Data, such as the results of an observation or experiment, can only reject or fail to reject a null hypothesis. For example, if comparison of two groups (for example, comparing subjects treated with a medication with untreated subjects) reveals no statistically significant difference between the two, it does not prove that there really is no difference; it only shows that the results were not sufficient to reject the null hypothesis."

Feb 10 at 2:00am · Like

Kurt L Ferré
Magnus, you seem to want 100% certainty of fluoridation. What I can tell you is that since the beginning of fluoridation over 68 years ago, the average IQ in the United States has risen 15 points. Let's look at some of the fine educational institutions in the United States: Harvard, Columbia, Georgetown, Duke, U. of Michigan, U. of Chicago, Stanford, UC-Berkeley, U. of Washington, and closer to home, Oregon State, Willamette University, and Pacific University (to name just a few) are all located in a long-standing fluoridated community. Prove to me Magnus, that any of the professors, their families, the citizens in those communities, have any IQ deficiencies. I can tell you that so many of my friends who were born and raised with fluoridation just shake their heads in disbelief that reduced IQ has become the "allegation du jour" of the anti-fluoride activists.

Feb 10 at 2:08am · Like · 1

Magnus Carlsson
Kurt, I truly appreciate that you take your time to listen to my concerns, and I am delighted that you also brought this discussion straight to the core of the issue!

Many people and organizations who support water fluoridation start off by presenting it as being safe, and it is not uncommon for us to see the wording that water fluoridation has been "proven safe". Such wordings push the buttons of all anti-fluoride activists of course, and are easily understood as "water fluoridation is 100% safe", and prompts questions like "show us the proof then that it is 100% safe!" That's how we get to the dead end of the null hypothesis.

I am not asking for 100% safety, and there are no studies that talk about 0% or 100%, but instead we talk about confidence intervals and statistical significance. Why am I so focused on safety anyways? Since I grew up in Sweden where water fluoridation is illegal, I found the practice foreign when I heard about the Portland plans in August last year. I have attempted to review the current research about fluoride safety, and by the way, Kurt, you have been helpful in increasing my understanding about fluorosilicates, for example. I still have some remaining questions that keep me awake at night though.

The rise of IQ test scores over the years brings up a number of interesting questions. Out of many influential factors, the one particularly relevant here is children's exposure to toxic chemicals. Again, I must recommend Bellinger & Bellinger's paper about childhood lead poisoning, because it explains so well what I am trying to get across. And since I broke the rules and mentioned the L-word, I will try to explain carefully why the paper is relevant, so that it doesn't come across as another strawman argument.

According to the paper, one of the factors that slowed down the efforts to eliminate lead poisoning was a prevailing focus on patients instead of populations. If an individual showed no symptoms, it was assumed that he or she was not lead poisoned. Then, in the early 1970s, population-based studies showed that there was something called "subclinical lead poisoning". The lesson is that it is impossible to examine a person (professor or not) and learn if this person's mental function has been affected by a small amount of lead poisoning. What if fluoride in the water would happen to have a similar effect on mental function? We would not be able to tell by looking at individuals.

What population-based studies showed was that if a large number of children were exposed to lead, the IQ distribution of the population was shifted down. When you shift a Bell curve slightly like this (I am going with the same example of 5 IQ points as the article), nothing dramatically happens with the population around the average, and the shift could easily be dismissed as noise. But look what happens closer to the tails: we get double the number of children with IQ under 70, and we cut the number of kids above 130 in half. The best that could be said about this situation is that it guarantees jobs for teachers in special education.

But as I said, Bellinger & Bellinger really explains this much better, so if you have not read their paper yet, please do!

What is then the connection with fluoride? I would hate to learn down the road that fluoride also has a negative impact on IQ, but I cannot rule it out because I am missing a crucial piece of research.

This is why I found it relevant to quote one of the authors of the Harvard study earlier in this thread. Grandjean really captures the essence of the connection that I now have tried to make with Bellinger & Bellinger's paper, so please allow me to repeat the quote: “Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain,” Grandjean says. “The effect of each toxicant may seem small, but the combined damage on a population scale can be serious, especially because the brain power of the next generation is crucial to all of us.”

Kurt, I see an underlying question in your comment: how could water fluoridation possibly be bringing IQ down when we have rolled out fluoridation in the U.S. over the last 68 years, yet at the same time we have seen IQ test scores increase? We simply don't know today what the IQ would have been without fluoridation. Even higher, perhaps? The same? Or lower? There are so many factors involved, and fluoride may or may not be one of them.

Now I hope that I have explained a bit clearer why I find the IQ studies so disturbing.

To summarize:

1. We are seeing an increasing number of foreign studies of uncertain quality that show a correlation between fluoride in drinking water and decreased IQ; the 2006 NRC review suggested that this connection should be further researched, and the Harvard IQ meta-analysis showed that the correlation was statistically significant, and the authors suggest that further studies should be a research priority.

2. I am asking for a high-quality case study that properly handles confounding factors and that can answer: is there a statistical significance between fluoride in drinking water and IQ test score? If there is - can we establish a safe limit?

Please point out if I am missing something in my line of reasoning, because that might help me sleep at night. Thank you!
http://www.jci.org/articles/view/28232

JCI - Childhood lead poisoning: the torturous path from science to policy

jci.org

Yesterday at 9:05am · Like · Edit

Magnus Carlsson

Healthy Kids Healthy Portland, you write that "According to this study, fluoride is known to cross the placenta because it is a vital mineral nutrient in the development of milk teeth." That is a remarkable conclusion. I was not able to find this conclusion in the abstract of the study, and I currently have no access to the full paper. Can you confirm that the full paper contains the claim that fluoride is a vital mineral nutrient in the development of milk teeth? Thank you!
2 minutes ago · Like · Edit 

Final words

Within ten minutes or so after my last post, all my comments were removed from the thread.

If you can point out what I am missing in my reasoning, please let me know!

If you can help me get in touch with professionals in public health in other ways, that would be fantastic.

Please consider sharing this message, because I think the open questions around water fluoridation safety are hugely important.

Update

I just came across a fresh post called Fluoridated Water and brains.  Read it, it is by Philippe Grandjean, and it appears that the Wichita Eagle did not check the facts with the authors.