No one should worry about fluoridation, despite the alarming headlines stirred up by a new study from Canada, according to Making Sense of Fluoride.
The study, published in the American Medical Association’s paediatric journal, claims to link higher levels of fluoride exposure in pregnant women to lower IQ scores in young children.
‘Experts have been quick to push back over the paper’s shortcomings,’ explains MSoF president Daniel Ryan. ‘In fact, it was accompanied by an extraordinary and unprecedented editor’s note. That suggests that even the journal’s editorial panel struggled with whether or not to publish.’
While some commentators say the study’s methodology is credible, others, including a panel from the UK’s Science Media Centre, found the data simply does not support the contentious conclusions.
MSoF’s science adviser Dr Ken Perrott has examined the paper and says the controversy has been caused by the study authors’ apparent statistical manipulation of the data. He agrees with SMC expert Thom Baguley, Professor of Experimental Psychology, Nottingham Trent University who said the type of analysis the researchers used is ‘frowned upon’ and that their ‘claim that maternal fluoride exposure is associated with a decrease in IQ of children is false.’ Another expert called the findings ‘weak’ and ‘borderline’. Reviewers were troubled, for example, that researchers reported a drop in IQ for boys but not for girls, questioning why gender would affect the results.
Critical commentators say at best the study is interesting but there’s no need for anyone to avoid fluoride, which has a valuable and proven role in preventing tooth decay.
‘We need to see if future research can reach the same conclusion,’ says Mr Ryan. ‘A single study that’s had so much backlash should simply not change anyone’s mind about the benefits and safety of fluoridation.’
‘The science is complex,’ he added. ‘It’s important to have reliable commentators that bring a balanced view to topics that can incite strong reaction.’
This new research confirms the previous findings by Bashash et al. in 2017 and Thomas et al. in 2018; that low levels of fluoride during foetal development will cause cognitive impairment, as well as 52 (out of 60) other human studies have shown a reduction in IQ. There are also over 300 animal studies indicating fluoride’s damage to the brain.
I agree with Peter Griffin that pregnant women should avoid fluoride as a precaution.
“An effect size [of fluoride] which is a on a par with lead.” Dimitri Christakis, editor in chief of JAMA Pediatrics. The Premiere Pediatric Journal in the World. “I would advise them to drink bottled water or filtered water”
“The effect size is really quite large because I think we, you know, you think about it really in terms of not the individual child so much as the shift in the curve. Right. In the shift the curve now being shifted to the left for boys. That’s a real concern, because then you look at the tails and the tails may be quite low.” Frederick Rivera editor JAMA Network, Open Journal “I think that this is a really concerning study to me”.
One can tell a study is suspect when people have to quote vague “authorities,” newspaper reports, podcasts and, even worse, Paul Connett from the Fluoride action Network (FAN), and then obliquely, rather than point to the contents of the paper – the data.
My respect for these “authorities” disappears when I see them citing the best-fit relationship without any indication of how weak that relationship is. In this particular case both relationship being cited are extremely weak, explaining only about 1 of the variance and in predictive terms the relationships are meaningless.
This fact sticks out like a sore thumb to anyone taking the trouble to look at the data presented in the papers. It’s surprising that this needs to be explained to anyone – but id did have to carefully explain it in detail to Bill Osmunson, a former director of FAN.
I am unable to reproduce the figures used here, but anyone interested can refer to my explanation in comments on the relationship to maternal urinary fluoride (MUF) (https://openparachute.wordpress.com/2019/08/22/if-at-first-you-dont-succeed-statistical-manipulation-might-help/#comment-133545) and fluoride intake (https://openparachute.wordpress.com/2019/08/22/if-at-first-you-dont-succeed-statistical-manipulation-might-help/#comment-133546).
“Fluoridation Safety Remains Intact” is misleading because the fluoridating authorities admit that they never did primary safety studies before introducing fluoridation. Even supporters of fluoride admit that fluoridation would never pass a primary safety study – that’s why you’ll never find promoters of fluoridation asking for that type of study to be done.
So safety was never intact in the first place.
Promoters talk “sciency” language but their actions/non-actions actually indicate an avoidance of science.
“misleading because the fluoridating authorities admit that they never did primary safety studies before introducing fluoridation”
There was research done in in the 1940s and ’50s.
They reduced the natural levels of fluoride (no more brown staining) but still keep the benefits of fewer cavities. They had test pilots studies that found no issues when fluoride was introduced to areas without fluoride. Of course, these days stricter testing would be used.
https://www.nidcr.nih.gov/health-info/fluoride/the-story-of-fluoridation
https://www.nature.com/articles/4812863
In the 1950s, University of Michigan researchers took the time to examine a long list of health conditions (ranging from acne to cancer) that critics tried to blame on fluoride. The researchers found no solid evidence to back any of these accusations. Have a read here:
https://s3-us-west-2.amazonaws.com/cdhp-fluoridation/CWF+Research/Univ.+of+Mich+(1960)+Appraisal+of+CWF+Objections.pdf
Since then we continue to study and monitor. Here in New Zealand, we have one of the best studies in the world – the Dunedin Multidisciplinary Health & Development Study. This has monitored people 1000+ people since 1972. It has produced 1200+ papers out. One of the things it monitors is fluoride and fluoridation.
https://dunedinstudy.otago.ac.nz/
Anti-fluoride groups spread misinformation about one of the fluoride IQ study papers that were written. But it was a high-quality study and I debunked some of this here:
http://msof.nz/2015/08/dr-connett-distorts-the-dunedin-iq-fluoride-study/
Daniel you haven’t listed one primary safety study where people were subjected to varying levels of fluoride to determine the Lowest Observable Adverse Effect Level (LOAEL) under controlled conditions and then the setting of a safe dose using a margin of safety (usually one order of magnitude). You have only listed a bit about the history of fluoride and observational/population studies. This shows that you don’t have a primary safety study to list otherwise you would have done so. As I said promoters are actually avoiding the definitive testing that would prove or disprove fluoridation safety.
The Dunedin Study is a Cohort study. It has a lot of controls. For example the paper “Community Water Fluoridation and Intelligence: Prospective Study in New Zealand” controlled for childhood factors associated with IQ variation, such as socio-economic status of parents, birthweight and breastfeeding, secondary and tertiary educational achievement and sources of fluoride exposure other than community water fluoridation (CWF). They also controlled for a similar set of confounders to those controlled by Meier et al (2012) in their study of cannabis exposure and IQ, which found that persistent cannabis users show neuropsychological decline.
They re-ran their analysis based on anti-fluoride complaints, taking into account both suburb and distance from the city centre, more details on total fluoride intake, the interaction between breastfeeding (including duration), etc.
Scientists can use the Dunedin study to pick out anything around fluoridation. If anti-fluoride groups don’t think enough papers have been written on the harms, then they can use this study to write more. But they don’t…
The Dunedin study is an observational study. It’s not what I’m looking for I’m afraid.
“It’s not what I’m looking for I’m afraid.”
Why not. What other controls are you looking for?
You ask for studies and I gave you one of the best in the world. Now you are moving the goal post.
As for LOAEL, this isn’t worked out in one study, likely hundreds.
Water is fluoridated at 0.7 mg/liter (ppm=mg/liter). Thus, for every liter of fluoridated water consumed, the “dose” of fluoride intake is 0.7 mg. The average daily water consumption by an adult is 2-3 liters per day. So, let’s go to an extreme and double that to an excessive 6 liters of fluoridated water consumption per day. This translates to 4.2 mg “dose” of fluoride intake per day from the water. The CDC estimates that of the total daily intake, or “dose”, of fluoride from all sources including dental products, 75% is from the water. Thus as 4.2 mg is 75% if the total daily intake from all sources, the total daily intake, or “dose” from all sources would be 5.6 mg for an individual who consumed an excessive 6 liters of fluoridated water per day.
The Institute of Medicine has established that the daily upper limit for fluoride intake from all sources, for adults, before adverse effects will occur, short or long-term, is 10 mg. Thus, even the excessive 6 liter per day consumer of water will still only take in a daily “dose” of fluoride that is slightly more than half the upper limit before adverse effects.
The range of safety between the miniscule few parts per million fluoride that are added to existing fluoride levels in your water, is so wide that “dose” is not an issue. Before the UL of 10 mg could be reached, water toxicity would be the concern, not fluoride.
Dan, the University of Calgary’s O’Brien Institute for Public Health, agrees with those opposed to fluoridation that the Dunedin study is weak and has a “lack of statistical power to make definitive conclusions”. If you consider this study to be “one of the best studies in the world” then you are misguided and an outlier.
“A later prospective study of a birth cohort in Dunedin, New Zealand found no association between fluoride exposure and IQ measurements performed repeatedly during childhood and at age 38. The cohort study design of this study, published in 2015, is stronger than prior study designs. However, there were also some important limitations to this study, including the fact that there were only a small number of control subjects (one-tenth the number of subjects exposed to fluoridated water), and as a result, a lack of statistical power to make definitive conclusions. Also, various forms of oral fluoride supplements were in use in New Zealand in the 1970s, and it is likely that controls received fluoride from non-water sources – a factor that could bias the study toward finding no association.”
https://obrieniph.ucalgary.ca
Getting a large group of anti-fluoride scientists to provide feedback don’t fill me with confidence that they won’t be biased. I told Broadbent he should make a complaint about that exact point you wrote and get them to fix it.
“If you consider this study to be “one of the best studies in the world” then you are misguided and an outlier.”
The Dunedain study is one of the best in the world. What other cohort studies monitor people for over 40 years, with so many controls, and has had 1200+ papers written? But I think you’re confusing the study with the Broadbent et al. (2014) paper.
But let us look at what others say about the Broadbent et al. (2014) paper.
The 2015 ‘Health effects of water fluoridation‘ review by the Health Research Board said of the study
“…the current review identified one original paper in a non-endemic area (New Zealand) that aimed to clarify the relationship between CWF and IQ by Broadbent et al. This is a high-quality prospective cohort study of a general population sample…”.
The NHMRC 2017 review, “Water fluoridation: dental and other human health outcomes” had this to say:
“One study was a high quality prospective cohort study, with a low risk of bias.This study took account of known confounding factors including sex, socio-economic status, breastfeeding, childhood maltreatment, perinatal insults, birth weight and educational achievement. The fluoride levels in this study were similar to current Australian levels and the study was done in a country with similar socio-economic and healthcare system characteristics (New Zealand). This study found that there was no significant difference in IQ scores at ages 7-13 years and 38 years between those exposed to water fluoridation and those that are not.”
The Royal Society 2014 review, “Health effects of water fluoridation: A review of the scientific evidence” said:
“A recently published study in New Zealand followed a group of people born in the early 1970s and measured childhood IQ at the ages of 7, 9, 11 and 13 years, and adult IQ at the age of 38 years. Early-life exposure to fluoride from a variety of sources was recorded, and adjustments were made for factors potentially influencing IQ. This extensive study revealed no evidence that exposure to water fluoridation in New Zealand affects neurological development or IQ.”
I could probably find a lot more examples but hopefully you see my point that it’s silly to call my words an “an outlier”.
“However, there were also some important limitations to this study, including the fact that there were only a small number of control subjects (one-tenth the number of subjects exposed to fluoridated water), and as a result, a lack of statistical power to make definitive conclusions”
If you read my article I discuss this point:
“The number of study members who had never resided in a fluoridated area was 99, and the number who had, was 891, but this does not indicate a low ability to detect an effect. There is no such thing as no fluoride exposure; that is, fluoride is naturally present in both soil and water. The study had more than enough power to conduct analyses that distinguished between high and low fluoride exposure, and to model the relation with IQ.”
“Also, various forms of oral fluoride supplements were in use in New Zealand in the 1970s, and it is likely that controls received fluoride from non-water sources – a factor that could bias the study toward finding no association”
Again I discuss this point and showed the graph:
“This was controlled for, and no significant differences in IQ were found. Those with high total fluoride intake had slightly higher IQs than those with low total fluoride intake”
“Scientists can use the Dunedin study to pick out anything around fluoridation. If anti-fluoride groups don’t think enough papers have been written on the harms, then they can use this study to write more. But they don’t…”
Dan – the Dunedin study is flawed. Highly reputable public health organisations (not Anti-Fluoride groups) concluded it lacks statistical power to make definitive conclusions.
Why do you not believe a pro-fluoride public health organisation?
“A later prospective study of a birth cohort in Dunedin, New Zealand found no association between fluoride exposure and IQ measurements performed repeatedly during childhood and at age 38. The cohort study design of this study, published in 2015, is stronger than prior study designs. However, there were also some important limitations to this study, including the fact that there were only a small number of control subjects (one-tenth the number of subjects exposed to fluoridated water), and as a result, a lack of statistical power to make definitive conclusions. Also, various forms of oral fluoride supplements were in use in New Zealand in the 1970s, and it is likely that controls received fluoride from non-water sources – a factor that could bias the study toward finding no association.”
https://obrieniph.ucalgary.ca
Corrected your points above.
Dan, okay, I see what you are trying to do. You are trying to misrepresent the Dunedin ‘data’ with the flawed Broadbent study. So you should be more specific because it deliberately misrepresents the Broadbent study which, is a deeply flawed piece of work despite using the Dunedin study data which would appear strong. Surely, even you can see the difference.
I think you’ll find the O’Brien Institute were able to include Bashash et al. 2017 in their analysis and also were aware of Green et al. 2019. The Royal Society 2014 review and the NHMRC 2017 paper did not.
Really, you should be moving on from the outdated Gluckman/Skegg paper – it was completed 5 years ago this August, Dan.
“You are trying to misrepresent the Dunedin ‘data’ with the flawed Broadbent study”
No, I was clear above with what I said to Gus. I don’t see how I misrepresent either.
“deeply flawed piece of work”
Yet I just showed you systematic reviews that it was high-quality paper. Everything that has been said against it has been debunked. Unless you have some new reasons?
“Really, you should be moving on from the outdated Gluckman/Skegg paper”
My point was to show it wasn’t “an outlier” like you said. Nothing more.
But I know how much you love the review… 🙂
“in their analysis”
This was neither a meta-analysis nor a systematic review. This was a report for the City Council of Calgary. Yes, they pointed out possible problems with new studies. These studies will be covered in future meta-analysis or systematic reviews.
This is a problem with the FFNZ organisation. They jump on the latest paper, spread all this news about it. Don’t care about the quality, or if can be repeatable, or the evidence on the whole. Once it’s covered in a new systematic review and shown the evidence, on the whole, is not an issue, they then jump onto the next study. But I guess the tactic does work for the layperson who doesn’t know better.
Dan, are you saying that the O’Brien Institute is Anti-Fluoride?
“Getting a large group of anti-fluoride scientists to provide feedback don’t fill me with confidence that they won’t be biased. I told Broadbent he should make a complaint about that exact point you wrote and get them to fix it.”
This is interesting because if any scientist dears to threaten your pro-fluoride view then they are immediately considered Anti-Fluoride.
“Dan, are you saying that the O’Brien Institute is Anti-Fluoride?”
No.
“This is interesting because if any scientist dears to threaten your pro-fluoride view then they are immediately considered Anti-Fluoride.”
No, it’s all about balance. I already backed up my reason, the report said misinformation about Broadbent et al. (2014).
The report also didn’t mention conflict of interests but it does say “Dr. Paul Connett, Executive Director of the Fluoride Action Network, a U.S.-based group that is passionately opposed to Community Water Fluoridation”.
Dan the Institute of Medicine hasn’t done the primary clinical safety study with LOAEL determination otherwise that would be easily referenced. One of the fundamentals of toxicology is that the dose makes the poison. To say that dose is irrelevant is breaking one of the fundamentals of toxicology. You need to prove what you are saying. Quoting the Institute Medicine who can’t provide the primary clinical safety and LOAEL determination means there’s no paper trail to the evidence I’m afraid. Side effects are well documented even at so-called low doses.
http://fluoridealert.org/studies/hypersensitivity01/
“otherwise that would be easily referenced”
I found it easily enough.
Have a read of “Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride”.
https://www.ncbi.nlm.nih.gov/pubmed/23115811
You can read about how NOAEL applies to NZ here:
http://www.moh.govt.nz/NoteBook/nbbooks.nsf/0/C99892B48B828265CC257E4900805786/$file/Newly%20Proposed%20US%20EPA%20Guidelines%202011.pdf
“One of the fundamentals of toxicology is that the dose makes the poison. To say that dose is irrelevant is breaking one of the fundamentals of toxicology”
I understand the dose makes the poison. You are misrepresenting my point. I didn’t say it was irrelevant, I said the “dose” is not an issue because before the UL of 10 mg could be reached, water toxicity would be the concern, not the fluoride.
Dan, I’m just going to pick you up on a point you made above. You said, “Water is fluoridated at 0.7 mg/liter (ppm=mg/liter). Thus, for every liter of fluoridated water consumed, the “dose” of fluoride intake is 0.7 mg.” In fact, in New Zealand we fluoridate in a range between 0.7 – 1ppm (mid point of 0.85ppm). This is important because Green et al. was based on fluoridated water in Canada which has a target of 0.7ppm only.
The basic issues are this: 1. Proven, robust studies on the dangers of mass medication of water supplies with fluoride have been done and have shown that there is substantial danger from carrying on with this infringement on the basic human rights of all people. 2. The government, regardless of evidence, is not listening and is most certainly not employing the Precautionary Principle. To that extent they are not representing the New Zealand public or safeguarding them from potential harm. 3. The government are working hand-in-hand with societies that are sponsored by chemical corporations keen to increase their already substantial revenues.They are serving other masters. 4.Enforced mass medication of a water supply is an infringement on our basic human rights. It is completely unacceptable to do this at great expense to ratepayers and to millions of New Zealanders who do not want this enforced medication and exposes millions to unnecessary risk.. 5. Children get bad teeth through bad diet, too much sugar and not employing basic dental hygiene. Scotland has eradicated most of its problem through a simple programme, CHILDSMILE, issuing each child with toothpaste and a toothbrush and briefly teaching them how to brush their teeth at school. Their dental caries have plummeted without adding a mandatory toxic product like fluoride to their water supplies. Why? Because they addressed the basic cause of the problem rather than adding yet another poison to be taken systemically for young bodies to absorb, to their detriment. 6. NZ needs to learn to stop polluting and poisoning our water. Address the problem! Don’t create a “solution” to the problem that causes another problem.
All criticisms that have been levelled at the Green study, can be levelled at the Broadbent study as well as a whole lot more. I was going to point them all out but, really, it is obvious to anyone who is willing to look at this honestly. If all Dan can do is cite studies back in the 40s and 50s as if they constitute some sort of safety study is absurd and then Broadbent, then he doesn’t really have an argument and is just digging his heels in because either he is too embarrassed to admit he is wrong, or he is so absolutely brainwashed he can’t see it. What this thread shows us is that the likes of Ryan and Perrott will never accept that fluoridation may be causing harm no matter how much science is thrown at them. .
By the way Dan, early studies found problems. “There was an observation in the Kingston-Newburgh (Ast et al, 1956) study that was considered spurious and has never been followed up. There was a 13.5% incidence of cortical defects in bone in the fluoridated community but only 7.5% in the non-fluoridated community… Caffey (1955) noted that the age, sex, and anatomical distribution of these bone defects are `strikingly’ similar to that of osteogenic sarcoma. While progression of cortical defects to malignancies has not been observed clinically, it would be important to have direct evidence that osteogenic sarcoma rates in males under 30 have not increased with fluoridation”
Also “when children were examined in the Newburgh-Kingston study in 1955 (ten years after fluoridation was begun) they found that the girls in fluoridated Newburgh reached menstruation five months earlier, on average, than the girls in non-fluoridated Kingston.
Dan none of the links you posted list any clinical safety testing to determine the LOAEL. I’m after actual testing, fully cited – not lots of discussion. Where and when did they do the tests? Also where is the testing to show that 10mg per day is the upper limit that you refer to? Would you support a clinical safety study whereby patients are given 10mg per day of fluoride?
Feltman and Kosel reported side-effects at just 1mg per day! (SOURCE: Feltman R, Kosel G. (1961). Prenatal and postnatal ingestion of fluorides – Fourteen years of investigation – Final report. Journal of Dental Medicine 16: 190-99.
maryhobbwrites – You say:
“Scotland has eradicated most of its problem through a simple programme, CHILDSMILE, issuing each child with toothpaste and a toothbrush and briefly teaching them how to brush their teeth at school. ”
Of course, no one programme, eradicates a problem but the Childsmile programme (considered by expert to be complimentary to community water fluoridation rather than a substitute for it) is a set of separate programmes , Some of which are already used in New Zealand. Others could perhaps be used if found suitable.
But something you completely ignore is that Childsmile involves twice yearly fluoride varnishes to young children’s teeth. These work by releasing fluoride over time so have a similar effect to fluoridated water and that fluoride is, of course, ingested in the end, as is fluoride in water.
Kane, you and your mates in FFNZ keep describing the Dunedin study as “flawed” but are completely unable to say what the flaws are. Sample sizes and different treatments are not flaws, they are simply the realities of real populations.
Like any study, factors like sample size and treatments have an influence on the size of any difference that can be detected – that is also an inevitable result of using a real population. That is indicated by results of a statistical analysis – it is not a f”law.” So reporting a zero effect really refers to a minimum effect that can be detected in the particular situation. Even Paul Connett realises that and has expressed the opinion that it would be impossible to detect an IQ difference between fluoridated and unfluoridated populations because the effect is too small to be seen in the inevitable noise.
Of course, Connett changes his tune when he sees a study like Green et al which he can use to confirm his bias. But even that study was unable to detect a statistically significant difference in the mean IQ for children whose mothers lived in fluoridated and fluoridated areas. Green et al reported the values in their Table 1 but strangely did not discuss them.
You of course could say that the Green et al study was flawed – but in doing so you are simply expressing your bias – your faith that there is an IQ effect. but in the process you acknowledge the effect is so small it could not be detected by Green or Broadbent. The more sensible person can see that any claimed effect is just to small to be worth considering.
Gus, the only thing Feltman & Kosel wrote in the paper you cite is:
“One percent or our cases presented evidence of undesirable side effects from fluoride therapy.”
No data was presented to elucidate what was meant by this. The tablets were of different compositions and subjects may have been referring to their taste.
So this is not a study of side effects and the fact that anti-fluoride activists keep citing this paper (which for most people is very difficult to find) and pout so much reliance on this vague statement just indicates how weak their claims of harm are.
There is international consensus that the Dunedin study lacks the statistical power to show that fluoride does not lower IQ. For that reason it is a weak study.
I see you have not agreed with me that Dan was wrong about the level we currently fluoridate at in NZ. Except that is for Auckland where the Council ignored the incorrect advice from the MoH and followed FFNZ advice to lower the level. It seems a difficult thing for your small group to admit they are wrong.
Kane, good to see you have given up using the word “flawed.” But you do realise that when you say “lacks the statistical power to show that fluoride does not lower IQ” then you are required to state what the limit of detection is? Do you know what IQ difference the Dunedin study was capable of showing? Have you looked at the statistical analysis?
Or do you agree with Connett’s claim (made in Hirzy et al 2018) that it is impossible to detect an IQ difference in fluoridation studies because of this detection limit? (That his while he strongly believes there is an IQ difference he admits it is too small to detect inn thew data).
Really if you cannot say what IQ difference the study could detect then you are simply talking off the top of your head (or from another party of your body).
Green et al. (2019) also could not find a statistically significant difference in child IQs for mothers from fluoridated areas – are you going to say that the Green et al study “lacks the statistical power to show that fluoride does not lower IQ.”
The mean IQ values for nonfluoridated and fluoridated areas were 108.1 and 108.2 for all children, 106.3 and 104.8 for boys and 109.9 and 111.5 for girls (See Green et al’s Table 1 or my article If at first you don’t succeed . . . statistical manipulation might help (https://openparachute.wordpress.com/2019/08/22/if-at-first-you-dont-succeed-statistical-manipulation-might-help/)
None of those difference have statistical significance despite the several hundred sample pairs used.
Kane, I realise you will not be able to answer my question about the statistical power of the Dunedin study so let me quote you Aggeborn & Öhman (2016) who compared the statistical power of a number of fluoride/IQ studies. they reported that the Bropadbent et al (2015) study reported 95% confidence intervals of “(-3.49–3.20) for those between 7 and 13 years old and between (0.02–5.98) for those at age 38.”
So, the chance of actual IQ differences being outside those ranges is only 5%.
Broadbent, like all scientists, will acknowledge the limitations imposed by sample numbers etc., on the ability to detect such small differences. But Aggeborn & Öhman (2016) themselves could not find an IQ difference due to fluoride and reported confidence intervals of “(-1.8560–0.5546) for the specifications without covariates or fixed effects and (-0.1776–1.0311) for the specifications with all covariates and fixed effects, when fluoride is increased by 1 mg/l.”
So you and Connett are getting pretty desperate to continue arguing that the studies (Broadbent et al., Green et al., and Aggeborn & Öhman) simply lack the statistical power to detect the minuscule IQ differences you happen to believe in.
I should note that many of these studies do have the statistical power to detect other differences like effects on dental health and quality of life. Aggeborn & Öhman (2016), for example, report in their abstract:
“Taking all together, we investigate and confirm the long-established positive relationship between fluoride and dental health. Second, we find precisely estimated zero-effects on cognitive ability, non-cognitive ability and math test scores for fluoride levels in Swedish drinking water. Third, we find that fluoride improves later labor market outcomes, which indicates that good dental health is a positive factor on the labor market.”
Ken you said “The tablets were of different compositions and subjects may have been referring to their taste.”
Here is the actual truth :- Feltman & Kosel 1961 – Dental Digest:
“One percent of our cases reacted adversely to the fluoride. By the use of placebos, it was definitely established that the fluoride and not the binder was the causative agent. These reactions, occurring in gravid women and in children of all ages in the study group affected the dermatologic, gastro-intestinal and neurological systems. Eczema, atopic dermatitis, urticaria, epigastric distress, emesis, and headache have all occurred with the use of fluoride and disappeared upon the use of placebo tablets, only to recur when the fluoride tablet was, unknowingly to the patient, given again. When adverse reactions occur, the therapy can be readily discontinued and the patient or parent advised of the fact that sensitivity exists and the element is to be avoided as much as possible.”
SOURCE: Feltman R, Kosel G. (1961). Prenatal and postnatal ingestion of fluorides – Fourteen years of investigation – Final report. Journal of Dental Medicine 16: 190-99.
Yes, Gus, your quote is from Feltman & Kosel (1961) but I repeat “No data was presented to elucidate what was meant by this.” It is not clear if the authors speculating or acknowledging outside research – nothing is cited. But clearly the research did not involve investigation of any of those factors and no data is presented for the speculation.
The paper reports data on fluoride levels in blood and placental tissue and cord (Figs I & II, Table 1, 2 & 3) and dental health of the children (tooth decay data in Tables 4A, 4B and 5. They also included data on dental health from other studies.
Their summary includes the comments:
“Data is presented showing that fluoride ingested by gravid women enters the maternal circulation, is stored in the placenta and passes through the placental barrier to enter the fetal blood supply.
Evidence is presented that fluoride in the fetal blood supply affects the developing teeth to make them more resistant to dental caries.
No unusual effects have been observed on the blood pictures of children who ingested fluoride.”
There is no data on the speculated side effects so the paper is of no value in any discussion of such side effects. It says a lot when anti-fluoride activists have to use a speculative statement completely devoid of any data to support their claims. (While at the same time being silent about the paper reporting beneficial effects of fluoride supplements on dental health).
Gus, this is a poor quality paper (although we should perhaps make allowance for its age). it is not readily available either. I am surprised you cannot find anything more substantial or modern to support you claims.
Mary, you say:
“All criticisms that have been levelled at the Green study, can be levelled at the Broadbent study as well as a whole lot more. I was going to point them all out but, really, it is obvious to anyone who is willing to look at this honestly.”
I am disappointed you refuse to “point out” the criticisms you have of these two papers. Progress in science is driven by such critiques and always look forward to them.
I have discussed above “limitations” with the Broadbent paper – simple detection sensitivity which Broadbent himself acknowledges. (The study of Aggeborn & Öhman (2016) has far more sensitivity than any so far reported studies in this area because of the much larger sample size used and but still could not show a IQ effect) But I am far more concerned with the limitations in the Green et al paper because of its refusal to supply important statistical analysis results.
For example:
1: Their Table 1 lists the IQ of children for mothers from fluoridated and unfluoridated areas. The values are not different, statistically. Useful information – but the authors do not comment on that data in their discussion at all. I think that is dishonest.
2: Questions have been raised about the way the authors subdivided the data after the event. However, I am also concerned that the data for boys is not normally distributed so does not really satisfy the requirements for the linear regression used. This is perhaps a qualitative judgment, but one they hint at in their descriptions. They decided not to transform the data – perhaps they should have but I suspect this would have revealed there was no statistically significant relationship.
3: More importantly the relationship they report for boys is extremely weak – explaining only 1.3% of the data. It has absolutely no predictive power so their talk of a specific IQ drop with an increase in MUF is completely meaningless – it refers only to the best-fit line explaining a tiny proportion of the data and is not relevant to the data as a whole. This is immediately obvious to anyone who actually looks at the data presented in their figures.
4: I think it is dishonest for authors to report only meaningless p-values from their statistical analyses and not report the other important factors like the R-squared value. I can understand that the authors may not have wished to bring attention to how meaningless their relationship was but their omission should not have been allowed by the journal or reviewers (perhaps this gives us an idea of what the arguments in the editorial board about this paper involved).
5: I say dishonest rather than neglectful because these authors knew what they were doing. Till was involved with this paper and the Malin & Till (2015) ADHD paper. In that paper they had no hesitancy of reporting their relationships explained 22 – 34% of the ADHD variance (they reported R-squared values) but refused to report the same figures in the Green paper. Presumably because an R-squared value indicating only 1.3% explanation of IQ variance would expose how weak the relationship really is.
Ken valid scientific data never goes out of date. I can’t find a more modern study because as far as I’m aware one hasn’t been done. That’s because of what I call “science avoidance” by promoters. It doesn’t make sense to say there is no data.This is not an observational study. I think you are confused. It’s interesting that you are happy to selectively quote from the study but not happy with the part that discusses side effects. That’s a double standard. I don’t think you can get more definitive than verifying side effects with placebo testing. There is certainly no “speculation” as you put it. Ironically you are speculating.
Do you think reported side effects should be investigated and how do you propose to do that?
The method Feltman and Kosel used is one possible option. What do you think?
How would you design side effect testing Ken?
Ken, as stated previously, I agree with ardent Pro-Fluoridationist, Peter Griffin, that pregnant woman should avoid fluoridated water as a precaution.
At least that pro-fluoride fanatic has got some sense of honesty, even if it was only on that point.
Kane that is a complete cop out on the questions I posed you. Complete.
I take this as an indication that not only have you backed away from claiming flaws” in the Dunedin research, its an admission you actually don’t understand that and similar research. You are not capable of considering the actual data and you simply search for statements from “authority” figures. Even someone like Peter who has clearly not even looked at the data.
Gus, you say “valid scientific data never goes out of date.” But that is not the issue. There was absolutley no data in the Feltman & Kosel paper on side effects. It’s a matter of no data, nit goiung out of date.
I made it quite clear that I did not think the paper was very good. Yes, it included data on tooth decay and some blood and tissue concentrations but very few conclusions can be drawn form them – and the authors were careful not to do so but did not do further testing to enable conclusions.When I have attempted to published unfinished research like that reviewers have told me to go back and do the experiments – which I have.
You say “I don’t think you can get more definitive than verifying side effects with placebo testing. There is certainly no “speculation” as you put it.” But there was absolutely no data reported for side effects – the statement was purely speculative (and I can only think based on their reading of the literature – they certainly did not present data).
You say:
“Do you think reported side effects should be investigated and how do you propose to do that?” – Yes of course. I myself don’t propose to do anything – its not my job. But researcher have been doing it. You might not like the results because they do not confirm you bias, but the research still exists.
“The method Feltman and Kosel used is one possible option. What do you think?” No they did not use an option to look at side effects. They did not include any methodology to do so or any results. Absolutely no data.
“How would you design side effect testing Ken?” I would design experiments to produce objective data. its not hard to do for a genuine researcher. I, for example, discuss one piece of published research on fluoridation side effects in my article “Fluoride sensitivity – all in the mind?” (https://openparachute.wordpress.com/2013/08/18/fluoride-sensitivity-all-in-the-mind/)
The Dunedin study is fundamentally flawed Ken.
Kane, yet you cannot state a single flaw. Perhaps the fundamental flaw lies with you.