After a 6-year long systematic review of fluoride’s impact on the developing brain, a court order has led to the National Toxicology Program (NTP) making public their finalized report that was blocked by
US Department of Health and Human Services (HHS) leadership and
concealed from the public for the past 10 months. The NTP reported 52 of
55 studies found decreases in child IQ associated with increase in
fluoride, a remarkable 95% consistency. The NTP’s report says:
“Our
meta-analysis confirms results of previous meta-analyses and extends
them by including newer, more precise studies with individual-level
exposure measures. The data support a consistent inverse association
between fluoride exposure and children's IQ.”
A
meta-analysis is when information from all the relevant studies are
combined to get a fuller and unbiased overall picture, rather than just
looking at individual studies in isolation.
The NTP’s meta-analysis also put the magnitude of harm into perspective:
"[R]esearch
on other neurotoxicants has shown that subtle shifts in IQ at the
population level can have a profound
impact on the number of people who
fall within the high and low ranges of the population's IQ distribution.
For example, a 5-point decrease in a population's IQ would nearly
double the number of people classified as intellectually disabled.”
So,
while an average drop of 5 IQ points in a population might sound small
it is huge from a public health perspective. Furthermore, the NTP
acknowledged there was the potential for some people to be more
susceptible than average [use NTP quote], so those people could lose
much more than 5 IQ points. Those susceptible individuals could lose 10,
15, 20 or more IQ points which would likely cause profound lifetime
negative consequences.
The
five independent peer-reviewers of the NTP report all voted to accept
the review’s main conclusion and lauded the report. Their comments
include: “what you have done is state-of-the-art”; “the analysis itself
is excellent, and you thoroughly addressed comments”; “Well done!”;
“Findings… were interpreted objectively”.
The newly released documents include comments from the NTP’s own experts confirming that the report’s conclusion that fluoride can lower IQ does
apply to communities with water fluoridation programs. NTP report says
the evidence is not just in those who drink water with higher fluoride
concentrations exceeding the World Health Organization (WHO) recommended
maximum level of 1.5 mg/L. Furthermore, the WHO guideline was set in
1984 to protect against more severe forms of dental fluorosis and
neurotoxicity was never considered. Few neurotoxicity studies even
existed in 1984.
In
numerous responses to comments by reviewers of the report, the NTP made
clear that they had found evidence that exposures of at least some
people in areas with fluoridated water at 0.7 mg/L were associated with
lower child IQ.
For example, when an unnamed government fluoridation proponent claimed:
"The
data do not support the assertion of an effect below 1.5 mg/L…all
conclusory statements in this document should be explicit that any
findings from the included studies only apply to water fluoride
concentrations above 1.5 mg/L."
The NTP responded:
"We do not agree with this comment…our
assessment considers fluoride exposures from all sources, not just
water…because fluoride is also found in certain foods, dental products,
some pharmaceuticals, and other sources… Even in the optimally
fluoridated cities…individual exposure levels…suggest widely varying
total exposures from water combined with fluoride from other sources."
Additional NTP responses about the review’s relevance to water fluoridation programs:
"We
have no basis on which to state that our findings are not relevant to
some children or pregnant people in the United States."
"Several
of the highest quality studies showing lower IQs in children were done
in optimally fluoridated (0.7 mg/L) areas…many urinary fluoride
measurements exceed those that would be expected from consuming water
that contains fluoride at 1.5 mg/L."
The
NTP also responded to commenters asking whether their meta-analysis had
identified any safe exposure threshold, below which there would be no
loss of IQ.
The
NTP responded that they found “no obvious threshold” for either total
fluoride exposure or water fluoride exposure, referring to a graph in
the meta-analysis (NTP’s eFigure 17 reproduced below) showing that as
water fluoride concentration increased from 0.0 to 1.5 mg/L there was a
steep drop in IQ of about 7 points (expressed as “standardized mean
difference” units in the graphs). An external peer-reviewer commented on
the size of the IQ loss: “Wow … that is substantial … That’s a big
deal.” {p 1060}
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