Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018)

This is the advice from the very top of the anti-fluoride movement – Paul Connett, director of the Fluoride Action Network (FAN). Don’t worry about reading  up on all the scientific information “You only have to read four studies…”

Of course – that is bad science. To ignore all the other information and rely just on four studies. But it is also bad science as those specific studies were chosen by Paul Connett because he believes they confirm his bias that community water fluoridation (CWF) is bad for you (they don’t actually). He consistently ignores studies which contradict his bais. But it is also bad science because these studies are weak and their results contradictory. Connett is simply into confirmation bias. He uses misrepresentation and mistaken interpretation of these studies to support his claims.

Connett acknowledges problems with high fluoride studies

Connett admits in his Fluoride Action Network (FAN) Bulletin from March 24, 2020:  “You only have to read four studies…” that “Many of the earlier studies were in places with elevated natural fluoride levels.” Yes – they are overwhelmingly from areas of endemic fluorosis, mainly in China, where health problems are very common and obvious. They have no relevance to community water fluoridation (CWF) – but this did not stop Connett, FAN and the whole anti-fluoride movement using them in their propaganda opposing a safe, effective and economic health policy known to reduce child tooth decay.

Then he goes on to claim:

“There is now very strong evidence that fluoride damages both the fetal and infant brain at the levels used in artificially fluoridated areas.”

“You only have to read four studies to realize that deliberately adding fluoride to drinking water unnecessarily endangers children’s brains.”

Let’s be scientific about it and have an objective and critical look at the specific studies Connett now relies on. I will discuss each of these four studies in separate articles. Here is my critique of the first one – Bashash et al (2017)

Bashash et al (2017)

The citation for this paper is:

Bashash, M., Thomas, D., Hu, H., Martinez-mier, E. A., Sanchez, B. N., Basu, N., … Hernández-avila, M. (2017). Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6 – 12 Years of Age in Mexico. Environmental Health Perspectives, 125(9).

Connett says:

“The first* came in Sept 2017 with a groundbreaking study from Mexico City. This study found a strong association between the amount of fluoride women were exposed to during pregnancy and lowered IQ in their offspring.”

Don’t take Connett’s word for this – read the paper and actually look at and consider the data.

Table 1 illustrates results from Bashash et al (2018) and from Thomas (2014) and Thomas et al (2013, 2014 & 2018): These all used the same or similar data from the ELEMENT database. The red triangles represent statistically significant relationships. All other relationships are not statistically significant.

Table 1: Summary of data from papers using the Mexican ELEMENT database. Red triangles indicate a statistically significant relationship.

Note: The coefficients were obtained from linear regression of full-scale child intelligence quotient (IQ), general cognitive index for the child (GCI) or mental development index of the child (MDI) against urinary fluoride for the child (UF) or prenatal urinary fluoride for the mother (MUF), adjusted in some cases using urine specific gravity (MUFsg) or urine creatinine concentrations (MUFcr). Bars represent the 95% confidence intervals of coefficients of the change of cognitive measure with an increase in fluoride measure. The red triangles represent statistically significant relationships. All other relationships are not statistically significant.

No relationship of child IQ with child urinary F:

Connett does not mention that there is no significant relationship of child IQ with fluoride exposure as measured by the child urinary F (UFsg) and he is also silent about the Thomas (2014) thesis which also showed no relationship of child MDI with child UF – although when Thomas (2014) separated data by sex she found a statistically significant positive relationship of IQ with UF for males.

Relationships with maternal prenatal urinary F – but very weak:

Yes, there are significant relationships of child IQ (6 – 12-year-olds) or child GCI (4-year-olds) with MUF – but contrary to Connett’s claim these relationships are far from “strong.” (Thomas did not find a significant relationship of MDI with  MUF for children of ages 1 to 3  but reported – in a conference poster paper Thomas et al 2018 – a statistically significant relationship for MUF corrected using creatinine concentrations – see  A conference paper on the maternal prenatal urinary fluoride/child IQ study has problems).

These figures from Bashash et al (2017) illustrate how scattered the data is:

While statistically significant the reported relationships are extremely weak – explaining only about 3.6% of the variance in IQ and 3.3% of the variance in GCI (see Maternal urinary fluoride/IQ study – an update). The large standard error of the regressions (9.8 for IQ and 12.9 for GCI) also indicate that the estimates of IQ change (-5.0) and GCI change (-6.3) for an increase of MUF of 1 mg/L  have no predictive value (see Maternal urinary fluoride/IQ study – an update).

Connett is very wrong to claim that “This study found a strong association . . .” It simply didn’t.

Tomorrow I will discuss the second study Connett now relies on – Green et al (2019) – see Anti-fluoridation propaganda now relies on only four studies. 2: Green et al (2019).

See also:

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7 responses to “Anti-fluoridation propaganda now relies on only four studies. 1: Bashash et al (2018)

  1. Robert Yeahright

    Here’s the problem with this study, who funded it, I noticed you can see all the details at a government website. The second problem I have is that I don’t care or trust government research. Third- Is it is a well known fact that fluoride is poisonous , why isn’t brushing our teeth with it enough ? now we have to ingest for the health of our teeth ? How could you possibly regulate the amount of fluoride we consume when you’ve put it in our drinking water? You could written this article about lead instead of fluoride and I’m still not going to believe the results of this test because logic overrides blind ignorance. Everybody knows that scientist do not get funding if their test results don’t fulfill the agenda of our government and not everybody is that naive or gullible

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  2. I am not clear what your point is Robert. Are you critical of the Bashash et al (2018) paper or are you’d defending it? And if so why?

    Are you critical of Paul Connett’s claims or are you defending them? And if so why?

    Or did you not read the article?

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  3. this did not stop Connett, FAN and the whole anti-fluoride movement using them in their propaganda opposing a safe, effective and economic health policy known to reduce child tooth decay.

    But, Ken, we have this great product called toothpaste which is safe and effective and doesn’t need to be swallowed to prevent tooth decay. You might have heard of it. We don’t need to add fluoridation to our water. Surely if I want to drink unfluoridated water, I should be permitted to do so.

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  4. Ross,

    “Surely if I want to drink unfluoridated water, I should be permitted to do so.”

    Within NZ, you are. Many communities don’t have CWF, and some that do also provide barely used publicly accessed fluoride free taps.

    And you can always purchase fluoride free water if it bugs you that much. Although if wanting to stay fluoride-free I’d stay away from water sourced from Tongariro, because it’s the only place in NZ where farmers are advised to watch out for fluoride poisoning in their stock.

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  5. And you can always purchase fluoride free water if it bugs you that much.

    Ah yes, the temerity of people wanting to drink unfluoridated water! We should be hung, drawn and quoted.

    Oh I do drink unfluoridated water. Then I throw the plastic bottles into the landfill.

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  6. Ross, of course, we don’t need to add F to water. We don’t need to brush our teeth either. And we can drink water,, fluoridated or unfluoridated, to our heart’s content We are free autonomous humans.

    But you seem to have not read my article. I am not talking about “needs” or human desires – I am talking about science and how it has been misrepresented by Paul Connett.

    Why do you not address that – the contents of my articles in this series, instead of attempting irrelevant diversions?

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  7. Ah, the hypocrisy of the anti-fluoride nutter – and I find, in my experience, this seems to be inevitable.

    They go around saying things like “Surely if I want to drink unfluoridated water, I should be permitted to do so.” They pretend that somehow something is being forced on them.

    But dig deeper, ask them if they take steps to get unfluoridated water (and some of them are so dishonest there refuse to answer) and you find out “Oh I do drink unfluoridated water.”

    In other words, it’s not about their desire to have access to unfluoridated water – like any adult they have already taken steps to get that water.

    It’s about their desire to prevent others from having what they wish.

    I always find this disgusting.

    Ross, no one imposes anything on you – stop trying to impose your desires on others.

    And be a man – confront the science. Engage with my articles in this series. Connett is disgusting in his attempts to prevent people from understanding the science.

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