By Michelle Dickinson 17/04/2017

Dear Lorraine,

I see that last week you decided to send this message to Green Party MP Julie Anne Genter:

After reading your e-mail I decided to create a flowchart for you to follow for the next time that you decide to interact with another human being.  This should especially be used when communicating with people that you don’t know.  I’ve called it Lorraine’s flow chart as it was written with you in mind, but feel free to share it with others.

Lorriane’s Flow Chart For Future Communications With Other Humans.


Now, in response to the message that you sent I would like to clarify a few things.

You wrote:

“People don’t realise how toxic fluoride is, even at low levels”

As you don’t offer any form of reference to your statement, firstly I don’t know who you mean by people or what you are classing as a low level of fluoride.

Let me offer some scientific evidence.

A recent paper in the American Journal of Public Health titled “Community Water Fluoridation and Intelligence: Prospective Study in New Zealand” the researchers are very clear in their findings.  They conducted a study on a sample of the general population from people born in Dunedin, New Zealand, between April 1, 1972, and March 30, 1973 and followed them for 38 years.  They found “No clear differences in IQ because of fluoride exposure even after adjusting for potential confounding variables, including sex, socioeconomic status, breastfeeding, and birth weight (as well as educational attainment for adult IQ outcomes).

Their peer reviewed conclusion specifically states that:

These findings do not support the assertion that fluoride in the context of community water fluoridation programs is neurotoxic.

Now I used this example because it is an amazing, peer reviewed long term study of the effects of fluoride in a New Zealand context which is where both you, I and Julie Anne live.

In your message you state that “People don’t know how toxic fluoride is”, and you might be right.  So I thought I’d do some calculations so that people could know how toxic fluoride is, because it is toxic if you consume too much of it, but so is vitamin D, calcium even water is toxic, does this mean we need to start warning people about the dangers of drinking water too?

The amount of fluoride in our water supply is adjusted to keep our water supply level to between 0.7 ppm and 1.0 ppm. This is the optimal amount that provides protection against tooth decay and monitored to make sure that the levels stay within that range.  So how much fluoridated water would you have to drink before you die from toxicity?

To help you out, I decided to make some calculations for you by taking a look at your linkedin profile and estimating that you are an adult female weighing around 68kg.

If I am incorrect on your weight, please feel free to correct me and I will re-calculate for you, but based on this I made you a personal fluoride in New Zealand tap water toxicity chart:


Table showing that it would take 1220 glasses of fluoridated tap water to possibly be toxic to Lorraine when considering fluoride toxicity risks

So perhaps your next email about the toxicity of fluoride should be more clear and state that “even at levels of fluoride that are in New Zealand tap water, you would need to drink 1220 glasses of water in a day for it to be possibly toxic”.

But I think you are missing a very important point and perhaps your messages should be less concerned about the levels of fluoride in the water and more concerned about the dangers of water itself!

I looked up the MSDS (materials safety data sheet) for water which states that:

Toxicity to Animals:LD50: [Rat] – Route: oral; Dose: > 90 ml/kg LC50
MSDS sheets are documents that contain information on the potential hazards of chemical products and are documents that scientists like myself must use when completing our health and safety programs for any substance that we use.

From this I calculated your personal water toxicity risk:


Table showing that it would take 24 glasses of fluoridated tap water to possibly be toxic to Lorraine when considering hyperhydration

This means that water is much more toxic that fluoride and if you wanted to give medical and scientific advice to people that you don’t know then you should probably focus on the much higher chance that somebody dies from hyperhydration by drinking 24 glasses of water than the highly achievable 7000 glasses of water needed for fluoride toxicity.

Your next statement says that you think:

“dentists will be extremely embarrassed if it is found that they are wrong”

The thing is, science doesn’t work that way.  We scientists don’t become embarrassed if we are found wrong, we love it.


Let me explain scientific method to you.

Although anybody can do science, professional scientific researchers follow a scientific method which allows them to explain occurrences using a logical, consistent, systematic method of investigation.

This involves collecting large amounts of data from well thought out experiments and analysing that data to arrive at a well-tested, well documented, theory that is supported by the evidence.  The theory is then subjected to critique by other experts in the field and only if approved by them is it allowed to be published in a peer reviewed journal for others to read and learn from.  We can be wrong, but it’s very difficult to publish wrong data without it being picked up.  Its almost impossible for hundreds of scientists to publish the same wrong data, it’s actually our job as peer reviewers of other peoples science to pick holes in research trying to prove that it is wrong before allowing it to be published.  So there is no embarrassment in science, just a rigorous method that is followed with the goal of proving the science wrong first.

You say that:

More and more research is being conducted into fluoride

You are right, that’s the great thing about science, we continue to research to find out things that we don’t know.  I spent 7 years of my life research fluoride and even back then there had already been a lot of research carried out and we knew then what we know now, that the levels of fluoride in the tap water in New Zealand is not toxic and has show to have positive outcomes on our population including:

  • In children and adolescents, a 40 per cent lower lifetime incidence of dental decay (on average) for those living in areas with water fluoridation.
  • For adults, a 21 per cent reduction in dental decay for those aged 18 to 44 years and a30 per cent reduction for those aged 45+ (as measured by tooth surfaces affected).
  • A 48 per cent reduction in hospital admissions for treatment of tooth decay, for children up the age of four years.

Finally, I took a look at the link that you included which was to a blog site rather than to any peer reviewed scientific article. Carol S. Kopf, the author of the blog  is also the media director for the Fluoride Action network, an international coalition to end water fluoridation and so the blog that you refer to is heavily biased against fluoride.  

The blog post refers to research from Dr A.K. Susheela of India who states that she talked about the results of her studies on women ingesting fluoride at the 27th Conference of the International Society for Fluoride Research, Beijing, China, Oct. 2007. Her study was called: Fluoride Ingestion and Health Hazards with Focus on Anaemia in Pregnancy and low birth weight babies: Guidelines for rectification: Susheela A.K, Mondal NK, Rashmi G, Ganesh Kamala, Bhasin Shammi, Gupta Gunjan.

So I looked everywhere for a peer reviewed conference paper that Dr Susheela would have written up, which is how science that is presented at conferences is assessed to be accurate with good scientific method, however I couldn’t find any.

I did however manage to find one research paper written by Dr Susheela which seems to be connected to this blog statement, in her paper “Effective interventional approach to control anaemia in pregnant women” which she published in the journal Current Science, a science journal from India.  Science journals are ranked using an impact factor which is used to compare different journals within a certain field.  For example the highly regarded The New England journal of medicine has an impact factor of 59.558 and the medical journal The Lancet has an impact factor of 44.002.  For comparison Current Science has an impact factor of 0.83.

The study that the link you provided could loosely be connected to involved only women in India who were already pregnant, medically anemic and showed high levels of fluoride in their blood.

Just to be clear, India is one of several countries known to have dangerously high levels of fluoride in their drinking water with villages like Sogival with groundwater fluoride levels of 4.84 ppm.  Not only is their water naturally high in fluoride, but the women in this study were also eating black rock salt, a type of salt with high levels (157 ppm) of fluoride commonly found in Indian street food and Indian snacks and spices.

The link that you refer to is not a study that links fluoride to miscarriages and stillbirths as you claim, if you actually read the research you would see that its a study on pregnant women in a “developing country” who are already anaemic, ingesting high levels of fluoride and suffering from other risk factors including dietary deficiencies, parasitic infestations, urinary tract infections and malaria.

The paper itself is clear in it’s conclusion and states:

“The first factor (application of intervention) throws up a bit of a confusing result to which we do not have a concrete answer at the moment”

They find no concrete evidence that the very high levels of fluoride are directly correlated to the low birth weight of some of the babies, but as you can see when you read the paper, the women in this study are already unwell when judged by western medicine standards.

Back to your original advice for Julie-Anne, in New Zealand miscarriage affects 1 in every 4 women. Having a miscarriage can be traumatic and many women experience huge grief over their loss, it is a very sensitive subject and very personal to those involved.  If you haven’t had to experience the grief of a miscarriage or the challenges around infertility then please understand that it can involve pain, a sense of loss and a daily struggle to try and remain positive while sometimes feeling like a failure.

In closing, I’d like to leave you with a quote that a colleague of mine has on her office wall that I love and hope you might too:

“We’re all smart. Distinguish yourself by being kind”

0 Responses to “An open letter on fluoride, science and kindness”

  • Thanks for listening to non-scientists. But I am not sure if you will get very far trying to convince them to believe that peer review is always convincing.
    For a day or two more you may be able to access “The Truth about Vaccines” series where a number of pediatricians and others discuss what must be lacks in science.

    I am glad for your encouragement in developing challenges. There is some material here in my fluoridation bill submission which may prove to be more than coincidences if other readers can work on it.

    Having lived in non-fluoridated Manchester you may be interested to note my reference to improvements in their football successes a few years after Birmingham area became fluoridated.
    If I might expand on that:
    Using the Manchester United vs Birmingham City football results – 106 games starting 19th century I have given Manchester United 1 for a win 0 for a draw and -1 for a loss.
    Starting from 1979, 8 years after fluoridation stated in Birmingham City, Manchester United had no more losses against them. I assert that Birmingham City players were harmed by fluoridation.
    Using 0 for the years up to 1978 and 1 for the years from then on I have used Vassarstats to do a rank correlation.
    Results n=106, Rs=0.3041, t=3.26,
    p (two tailed) = 0.001506.

    Correlation is not causation, however in this case the chance is 15 parts per 10,000 that it is only chance that fluoridation after a short delay “explains” over 9% of the results.

    Then Aston Villa having the same water supply as Birmingham
    Aston Villa football club: record v Manchester United

    This time I put the fluoridated and non-fluoridated teams in the opposite order.
    Rs = -0.2375 or over 5.6 % “cause” by fluoridation.
    p= 0.0011

    As for more on the birth subject I note that in the USA when I neglect Hawaii and the top 10 states for African Americans (Actually 19.91% or above).

    Then correlating preterm births against fluoridation extent I calculate using rank correlation from Vassarstats

    number of states 40

    correlation 0.3628 or fluoridation “explaining” 13% of preterm births.

    t value 2.4
    p 0.021.

    Some more football material:
    Petone has always been an unfluoridated area of the Wellington region.
    Wellington’s top rugby players compete for the Jubilee Cup since 1929. Up
    until 1966 Petone won 23% of years. Then the rest of Wellington region but
    not Petone was fluoridated. Even though more teams came on the scene, from
    then on non-fluoridated Petone nearly doubled wins to 43%. of years. That is
    until Petone College closed and children had to cross the Hutt River and go to
    school in the fluoridated area. Petone club then dropped out of the Jubilee
    Cup to a lower grade.
    Timaru was fluoridated from 1973 to 1985, South Canterbury produced no
    more All Blacks after 1972 having produced 22 before that. It also dropped
    out of Division 1 rugby.

    I don’t feel the case for fluoridation safety to be quite trustworthy.

    • ^Can’t decide if this is clever humour, or a concerning display mental illness…

  • Ashton, hardly a winning reply. Is it intended to scare off actual answers?

    Sorry if I confused which Manchester university. (Manchester in USA is fluoridated.) I note the USA Manchester University offers a degree in pharmacogenomics, about getting medication or treatment better related to a patient’s genetic make up.
    I brought up in my submission the COMT gene variants and possible varied response to fluoride, study of which could be developed – thanks for being able to write on blogs like this and spread ideas. That leads on to the MAOA gene variants discussed 14th June last year when TV1 played a Dunedin Study episode which dealt the forms of the MAOA gene. 30% of people have the weak form and it is claimed they can become antisocial if maltreated up to age 11. Professor James Fallon who found 7 convicted murderers in his father’s family tree got his own brain scanned and it showed the problem pattern. But his mother had treated him well and his energy chanelled him to be a professor. I think additive effects MAOA – COMT need studying I imagine top rugby players need controlled aggression?

    With fluoridation there is the actually recognised need to vary the level in water for all people depending on the temperature and consequent water consumption. So a range of levels are in the “optimum” recommendation. (See WHO.) Though as far as I can see water supply authorities do not seem to interpret the levels that way. Sports players of course consume more water.

    • Hi Brian – no, I was genuinely confused.

      The idea of using football teams as a device is brilliant! It almost completely masked the lack of logic (why would football teams be so symptomatic? Do they really consume more water? Was the composition of the teams considered – as players were bought and sold, how did Manchester engineer it so that they only got players from fluoride-free cities? What of Manchester City as a team – were the derby games consistently a draw?).

      The added touch with the statistics – lots of single and double ended p tests etc etc etc, and a nod to correlation vs causation – wow! I was nearly blinded by your expertise.

      Until we got the the bit “Correlation is not causation, however in this case the chance is 15 parts per 10,000 that it is only chance that fluoridation after a short delay “explains” over 9% of the results.”

      Brilliance. Without reference to ANY other factor that might confound the hypothesis!

      It has to be satire.

      Moderators – feel free to remove this post if it offends. Mea culpa.

      • Ashton note “explains” in inverted commas. It is a common use of the word, isn’t it, for statistical connection and does not mean actual causation? So there is no satire.

        I gave a number of apparent connections also without calculating correlations – like All Black births. The idea is to keep all those matters in mind.

        Your suggestions re where players in a team come from does not work for the lack of All Black captain births after fluoridation in Auckland, our largest city, in 1966.

        Fluoridation is one possible factor in all the matters, therefore ought to be considered with an open mind. It is possible to think up other reasons for all the matters such as for the preterm births matter I have added, and it quite possible that all the alternative explanations are correct. However in science the simpler explanation should always be given attention.

        If fluoridation adds to preterm births then does it add to stress on a pregnancy/foetus that may have some effect on it even if the birth is not preterm? Could that be a connection for All Black captain births which much more frequently come from parents living in non-fluoridated areas.?

        Ken brings up other factors such as altitude which tends to be connected to fluoridation then does a multiple regression and does not get p<0.05 for fluoridation so claims there to be no significant result shown. That is not however the same as proving there to be no connection which I maintain requires a correlation close to zero associated with a p<0.05.

        When combining variables when the correlations are fairly low then it takes more variables before a low p and therefore a conclusion can be drawn. If that not be taken into account I maintain a paper looks more like part of a sales campaign.masquerading as science.

        Of course other things can cause effects and it is necessary to try to control them, I maintain, by more means than just in the multiple regression. Such as reduced vitamin D that African Americans get from sunlight compared to fairer-skinned peoples. So choose similar groups between states if comparing states.

        You may have looked at the Lin FF paper and understood their claim of a reaction between fluoride (at levels relevant to fluoridation) low iodine intake and lower IQ. All Black captains have to be quite clever. Maybe iodine from iodised salt is sufficient for the average but what about for the exceptional.

  • Great article, MIchelle.

    I would add that the “authority” cited by Carol Kopf is also connected to Paul Connett’s Fluoride Action Network (FAN). The conference Dr Susheela submitted her cited paper at is one organised by the International Society for Fluoride Research which is active in anti-fluoridation propaganda and has links to FAN. It publishes the journal Fluoride – a poor quality journal presenting itself as scientific (and Edited by Bruce Spittle in NZ). I submitted a critique of one of FAN’s articles to that journal recently and it was rejected – after a farcical attempt at “peer review.” First time in a long career in research where I have published many papers. Bit of an honour actually to be rejected by a crappy journal like this.

    Never mind, my paper has now been submitted to a proper journal and is undergoing what I hope is a more sensible review process.

    Finally, Dr Susheela has recently been aprticpating in an anti-lfuoide nspeaking camapoing in North America. She has doen the same in Australia and I would nto be surpised ot see her do the same here. So she is hardly an objective authority – at leas on community nwater fluodiation as he expertise is on fluorosis in areas of endemci fluorosis where dietary itnake of fluodie is much higher..

  • Ashton Dempsey asks: “why would football teams be so symptomatic? Do they really consume more water?”

    Not sure if you are asking why or proclaiming there to be no reason.

    Take a look at success of 3 rugby teams from varying temperature areas in New Zealand the the Super Rugby competition

    In the first column I have the tally of the points won by the Auckland, Canterbury and Otago-based Super 12 rugby teams, less the points again st them.

    In the second column is the population of the province.

    The third column gives won – lost points per 10,000 population.

    Unfluoridated Canterbury is far ahead.

    Fluoridated, but cool climate Otago in southerly NZ is in the middle and hot fluoridated Auckland in hotter northerly NZ is very behind.

    696— 1377000– 5 Auckland (Blues)
    2141— 600100– 36 Canterbury (Crusaders)
    518 –=- 219200– 24 Otago (Highlanders)