On Tuesday, November 6th, the National Academies of Sciences (NAS) held a meeting at their offices in Washington, D.C., to share the preliminary findings of the National Toxicology Program’s (NTP) draft review on fluoride’s neurotoxicity with reporters and the public. In short, the NTP concluded that after 70 years of adding fluoridation chemicals to the public’s drinking water, “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.”
The Fluoride Action Network (FAN) sent two representatives to attend and present at the meeting, including our Research Director, Chris Neurath, and Senior Advisor, Bill Hirzy, PhD. Bloomberg Environment published an article covering the event, including quotes from Neurath. Also noteworthy in this article, are the quotes from the Science Policy Director of the American Association for Dental Research, who defends fluoridation and expresses concern that if the NTP language isn’t watered down, the public’s knowledge of fluoride’s neurotoxicity could cause communities to end the practice.
The next step in the process is for an ad hoc committee of the NAS to conduct a peer review of the NTP’s draft.
Below are excerpts from Chris Neurath’s presentation at yesterday’s NAS meeting.
Fluoride Action Network
Excerpts from Chris Neurath’s Presentation
at the National Academies of Sciences
The Fluoride Action Network nominated fluoride for review by the NTP more than 4 years ago, and although it has taken a long time, we feel the NTP has carefully weighed the evidence to reach their conclusion that fluoride is a presumed neurotoxin in humans.
The systematic literature search, extraction of data, and risk of bias scoring are excellent. NTP found 149 human studies and 339 animal studies many of which they scored as relatively low risk of bias. There are few neurotoxins with so much supporting evidence. However, we found the NTP monograph consistently downgraded the evidence of neurotoxicity at each step of their assessment:
- First, the scope of the review focused largely on learning and memory outcomes and gave little weight to other types of neurotoxicity.
- The scope of the review also downgraded studies in humans and animals that were at exposure levels higher than 1.5 mg/L in drinking water or its equivalent. This goes against basic principles in toxicology. Animal and human studies are often at exposures higher than in the general population, yet can be validly extrapolated to lower levels.
- The NTP equivocates on whether fluoride is a “presumed” neurotoxin at exposures below 1.5 mg/L.
- If NTP had followed their own pre-specified methodology, they should have concluded that fluoride is not just “presumed” but a “known” neurotoxin at exposures below 1.5 mg/L.
- That is because the human studies with exposures below 1.5 mg/L are actually the strongest studies.
- Indeed, NTP has identified 20 high quality, low risk of bias, human studies as shown in their Figure A1-01. Of these 20 studies, only 1 did not find a statistically significant adverse effect. Nine are at exposures below 1.5 and six are at exposures below 0.7 mg/L. There is remarkable consistency amongst these studies, and the effect magnitudes are large, with many finding average IQ losses of 4 or more points. NTP’s claim that the evidence from these low exposure studies is “inconsistent” is plainly wrong.
As if these 20 studies were not enough, there are now two new high quality studies. These new studies are so strong, and relevant, that we believe it is essential to consider them in your peer-review.
Two new papers
The first of the papers was published just 2 weeks ago and comes from the same Canadian group that produced the Green 2019 paper published in JAMA Pediatrics. It found a strong association between fluoride exposure and diagnoses of ADHD in a Canadian sample that is representative of the entire country. The sample is from a survey that is Canada’s equivalent to NHANES in the US. Adolescents living in fluoridated places had a 3-fold greater odds of being diagnosed with ADHD as those in non-fluoridated areas. This finding suggests that fluoridated water may cause the majority of all ADHD cases.
The second “bombshell” study, which has been accepted for publication and was presented at a recent conference, is from the same Canadian group. It used their mother-child cohort to examine the effect on IQ of early infant exposure to fluoride, which is dominated by infant formula made up with fluoridated tap water. They found that for every 1 mg/L increase in tap water fluoride there was a 9 IQ point decrease in the formula-fed infants but almost no decrease in exclusively breastfed infants. Breastmilk is highly protective against fluoride exposure to the baby because concentrations of fluoride in breastmilk are at least 100 times lower than in formula made from fluoridated water.
The magnitude of the effects in these two studies are enormous.
Analogy to Pb debate of 1990s
The NTP’s downgrading of the evidence of fluoride neurotoxicity, and vocal criticisms of each new study are reminiscent of the debate about whether “low-level” lead was neurotoxic in the 1990s, when Herbert Needleman was criticized and personally attacked because his work challenged the safety of lead industry products. It took more than two decades, until 2012, for the NTP to issue a monograph concluding that “low-level” lead was indeed neurotoxic. Millions of children suffered loss of IQ and behavioral problems during those two decades of official indecision.
The science right now for fluoride neurotoxicity at exposure levels experienced by hundreds of millions of Americans is as strong as it was for lead back in 1990.
Needleman did his own systematic review and meta-analysis in 1990 and found only 12 qualified human studies. Yet he concluded that these 12 studies provided strong evidence that Pb was neurotoxic at “low-levels” and he has been proven correct.
The Fluoride Action Network does not pretend to reach the stature of Herbert Needleman in the field of environmental public health, but we urge each of you on this committee to aspire to that stature and integrity when assessing the evidence for fluoride neurotoxicity.