Mutt & Jeff by Bud Fisher, June 3, 1942.
In
a classic Mutt & Jeff comic a drunk is crawling around on the
ground under a streetlight, looking for his dropped coin. A cop asks,
“Did you drop it here?” and the drunk replies “No, but the light is
better here!”
Insensitive And Unreliable Measures Of Neurotoxicity
A
just-published Australian study claims to have found no link between
fluoridation and harm to children’s developing brains but didn’t use any
IQ tests [Do 2022].
Instead, it used parent questionnaires of child behaviors which have
been found to be relatively insensitive to detecting harm from fluoride
and other neurotoxic chemicals.
The
study’s lead author, dentist Dr. Loc Do of Queensland University,
Australia, used two parent questionnaires to see if he could detect the
same neurotoxic effects in Australian children that numerous other
studies have found in Canada, Mexico, China, and elsewhere. But those
studies all used standard IQ-type tests. Do’s study instead used a
Strengths and Difficulties Questionnaire (SDQ), which is not a measure
of intelligence or cognitive ability but is “a 25-item brief behavioral
screening tool that measures children’s behaviors, emotions, and
relationships.” For example, it asks parents whether their child can be
described as “Kind”, “Lies”, “Bullied”, “Shares”, “Unhappy”, “Helps”,
“Clingy”, and other items having little relationship to IQ [Ribeiro Santiago 2021].
Furthermore,
one of the two psychologist co-authors with Do published a different
paper just last year that recommended against using the SDQ in
Australian children because of poor validity. Her paper concluded: “In
summary, the presence of a weak and unstable structure … and poor
stability … prevents us from recommending the caregiver-informant SDQ
for children … in Australia.” [Ribeiro Santiago 2021].
Why did Do choose an outcome measure that his own co-author recommended
against using? What’s more, in the only previous fluoride
neurotoxicity study that used the SDQ questionnaire to try to assess
ADHD symptoms, the SDQ hyperactivity subscale found only small or
non-significant associations with fluoride while actual diagnosis of
ADHD was strongly associated with water fluoride concentration and
fluoridation status. Reported ADHD diagnoses were almost 300% greater
amongst adolescents in fluoridated areas compared to non-fluoridated
areas of Canada [Riddell 2019].
The
other parental questionnaire Do used, the Behavior Rating Inventory of
Executive Function (BRIEF), is equally problematic for trying to detect
neurotoxicity. It has never been used to assess fluoride neurotoxicity.
Furthermore, in the only study where BRIEF was compared to typical
IQ-type tests to assess neurotoxicity of a chemical, BRIEF couldn’t
detect any harm [Wright 2006]. In the same study, however, standard IQ-type tests were able to detect neurotoxicity.
Like
the drunk and the Streetlight Effect Fallacy, Do seems to have ignored
the obvious “place” to look for fluoride’s neurotoxicity, which is with
its effect on IQ and cognition. Over 70 studies have used IQ-type tests
and almost all have found adverse effects, including at the same doses
as occur from fluoridated water in Australia [FAN webpage list].
Do’s study is an extreme outlier. Over two dozen of the studies
finding an effect were rated high quality by the US National Toxicology
Program [Neurath 2022].
Instead of looking where he had the best chance of finding an effect,
Do chose questionnaires that asked parents about child behaviors like
“kindness” and “clinginess”.
Having
found no effect using insensitive measures, Do makes the bold claim:
“This finding shows that consuming water with fluoride at levels used
for public supplies in Australia is safe and it supports continuing and
expanding fluoridation programs." This ignores the large number and
higher quality studies showing fluoridation is not safe.
Was Study Designed To Find No Effect?
The
choice of insensitive outcome measures raises the question of whether
the Do study was designed to not find an effect. Furthermore, the
original grant
of almost $1 million was for a study that would assess fluoride’s
effect on “intellectual development” but it appears to have abandoned
this original purpose.
Other Weaknesses: Ecological, Didn’t Account For All Fluoride Sources, Inadequate Control Of Confounders
Do’s
study summary for his grant claimed his study would provide “high
quality evidence” on fluoridation and intellectual development.
However, it has additional important shortcomings compared to recent
studies that found adverse neurotoxic effects. Do’s study, instead of
using an individual-level measure of fluoride exposure, used a
group-level measure (also called an ecological measure), and only tried
to account for fluoride from fluoridated water, rather than all
sources. This is an important weakness compared to the best studies,
which either used the biomarker of urine fluoride concentration which
reflects fluoride exposure from all sources, or used combined estimates
of fluoride intake from drinking water and tea [Goodman 2022, Cantoral 2021, Farmus 2021, Wang 2021, Yu 2021, Zhao 2021, Till 2020, Wang 2019, Green 2019, Riddell 2019, Bashash 2018, Bashash 2017, Valdez-Jimenez 2017].
Tea has been found to be the second largest source of fluoride exposure
after fluoridated water, even in a country with much lower tea
consumption than Australia [Helte 2021].
The inability to account for all sources of fluoride exposure in the Do
study likely further reduced the study’s ability to detect an effect of
fluoride.
Another
weakness of the Do study is its lack of control for potentially
important confounders, which other recent studies did control for,
including: lead, mercury, arsenic, PFOA, parent IQ, HOME score,
gestational age, birth weight, parity, marriage status, smoking, alcohol
use of mother, and Body Mass Index (BMI).
Cites Food & Pharma Industry Front-Group’s Bogus Review
More
evidence of the author’s bias is found in the Do paper introduction
that cites a very biased German review that concludes fluoride has no
association with neurotoxicity [Guth 2020].
This is a favorite review of fluoridation defenders. But the authors
of that review are closely associated with a front-group for food and
pharmaceutical interests that has a history of claiming chemical food
additives, genetically modified foods, and even endocrine disrupting
chemicals are no problem [USRightToKnow 2022, CorporateEuropeObservatory 2012, TestBioTech 2012]. We’ll have more on those authors and their links with industry in a future bulletin.
Do’s Advocacy For Fluoridation Reveals Bias
Finally, the choice to publish Do’s paper in the fluoridation-friendly Journal of Dental Research (JDR)
instead of a journal specializing in neurotoxicity or environmental
health, is further evidence the Do study is biased to avoid finding an
adverse effect that might threaten fluoridation. JDR is
sponsored by the International Association for Dental Research (IADR),
which has had a long-standing official position supporting fluoridation
and claiming it is “safe and effective”. In fact, the latest update of
the IADR Position Statement on fluoridation was written by Dr. Do and
has outdated and misleading information about adverse effects [IADR 2021].
The
Streetlight Effect Fallacy may explain how this Australian study failed
to find harm to the brain from fluoridation, but another proverb
summarizes what appears to be the attitude of the researchers, and of
all fluoridation defenders who are trying to deny the strong scientific
evidence that fluoride harms brains: See no evil, hear no evil, speak no evil... about fluoridation.
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