The Breaking News on Fluoridation and Intelligence Shows Even More Harm. Part 2: An Interview with Paul Connett, Ph.D.

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Note: The views and opinions expressed here are those of the author (s) and contributor (s) and do not necessarily reflect those of the publisher and editors of WholeFoods Magazine. Information in this interview is intended for educational and scientific purposes only. It is not intended as medical or nutritional advice for the treatment or prevention of disease. For medical advice, consult your personal health care practitioner.


In part 1 of this interview (published in the May 2021 issue of WholeFoods Magazine), we discussed the studies showing fluoride is a neurotoxin that lowers human intelligence as measured by Intelligence Quotient (IQ) at the level used in water fluoridation. Findings are based on IQ examinations of 26,142 children (67 studies) and 245 adults (2 studies). The result was an average loss of 7 IQ points, which more than halves the number of very bright children (IQ > 130) and increases by nearly 60% the number of mentally handicapped children (IQ < 70). It has been estimated that a loss of one IQ point represents a loss of $18,000 in lifetime earnings (Bellinger, 2012).

Now a recently published study shows the damage to be worse (Grandjean P, Hu H, Till C, et al. Risk Analysis, June 8, 2021). The study confirms that very low levels of fluoride exposure during pregnancy impairs the brain development of the child, and may be causing more damage than lead, mercury, or arsenic.

Keep in mind: Fluoridation poses risks from womb to tomb. Not only is it linked to damage of the brains of the developing fetus and growing child, it also accumulates in our bones over a lifetime. A recent study from Sweden found an increased risk of hip fractures in post-menopausal women at the same levels of fluoride we have in fluoridated water in the U.S.

Paul Connett, Ph.D., Director of Fluoride Action Network

Let’s chat with Paul Connett, Ph.D., about the importance of this recent study. Dr. Connett is the Director of the Fluoride Action Network (FAN). He is a graduate of Cambridge University and holds a Ph.D. in chemistry from Dartmouth College. From 1983-2006, Dr. Connett taught chemistry at St. Lawrence University in Canton, NY, where he specialized in Environmental Chemistry and Toxicology.

Over the past 36 years, his research on waste management has taken him to 49 states in the U.S., seven provinces in Canada, and 68 other countries, where he has given over 2,500 pro bono public presentations.

In 1996, Dr. Connett was persuaded by his wife Ellen to investigate the controversial practice of water fluoridation. In 2000, he was one of the founders of the Fluoride Action Network and is the organization’s current director. In 2003, he gave an invited presentation to a panel appointed by the U.S. National Research Council, which published a landmark review of fluoride’s toxicity in 2006.

In 2010, with two other authors, James Beck, M.D., Ph.D., and Spedding Micklem, DPhil (Oxon), he published The Case Against Fluoride (Chelsea Green 2010).


Passwater: Dr. Connett, this new study not only provides alarming evidence of fluoridation’s developmental neurotoxicity, it also provides the data needed to counter the claim by fluoridation proponents that there is little evidence to show harm at very low fluoride levels. What is the significance of this new study in this regard?

Connett: This BMD analysis is of critical importance in terms of ending fluoridation worldwide. First, let me explain what a BMD analysis is. It is a methodology approved by the U.S. Environmental Protection Agency (EPA) for performing a risk assessment to determine a safe reference dose (RfD) sufficient to protect everyone from a particular substance once a study (or several studies) have found it causes a harmful effect. BMD stands for Benchmark Dose and that is the lowest dose that causes a “defined” amount of harm (the benchmark). In this case the defined amount of harm is a loss of one IQ point.

This method can only be applied when studies have produced dose-response data. In this case, Grandjean combined the dose response date from both the Mexico City study (Bashash et al, 2017) and the study from Canada (Green et al., 2019). The two combined had 800 paired Mother-infant data pairs for Mother’s exposure to fluoride as measured in their urine, versus the average number of IQ points lost in the offspring. From the linear extrapolation for the whole data base, they were able to predict that a loss of one IQ would occur for a mother’s urinary fluoride level of 0.2 mg/Liter (i.e. 0.2 ppm).

That BMD is very low in the context of the average maternal urinary levels measured in pregnant women in fluoridated communities in the San Francisco Bay area and pregnant women from all parts of Canada, which range from 0.8 to 1 ppm. Since the relationship between urinary fluoride levels and IQ loss is a linear one (i.e. if the fluoride urinary level doubles the IQ loss would be doubled), this means that the projected average IQ loss for children born to pregnant women drinking fluoridated water is 4 to 5 IQ points. That is an extraordinary finding, and according to Grandjean, it means that in the USA today fluoride is causing a greater loss of IQ points than lead, arsenic or mercury, as far as the whole population of children is concerned. This does not mean that fluoride (atom for atom) is more brain damaging than these other substances, but rather that millions more children are being exposed to fluoride. We do not deliberately add lead, arsenic, or mercury to the drinking water!

Thus, this throws out of the window the claims that fluoridation promoters have been making ever since the early Chinese studies were published in the 1990s, that fluoride only lowers IQ at much higher doses than experienced in fluoridated communities. This is simply not true. IQ is being lowered at water concentrations far less than the 0.7 ppm used in water fluoridation.

Passwater: Can this additional information be included in the suit in Federal Court against the Environmental Protection Agency?

Connett: Most certainly. In fact, the judge has been waiting for this paper to be published. Dr. Grandjean was an expert witness in the case (heard in June, 2020) and presented a preliminary BMD analysis then. The judge is also waiting for the final version of the NTP’s review of fluoride’s neurotoxicity, and that is expected to be published before the end of this year. When both documents are available, the judge is indicating that he wishes to hear experts from both sides give their opinions on their significance. Then he is expected to give a ruling on our case.

Passwater: What is the importance of Dr. Grandjean using a Benchmark Dose methodology for his risk assessment?

Connett: The defendant in our federal lawsuit under TSCA is the EPA. Therefore, it is highly significant that Grandjean has used the EPA’s own preferred risk assessment methodology to demonstrate that fluoridation is unsafe as far protecting the brain of the fetus is concerned. The EPA lawyers cannot argue that he has used an unusual method.

Passwater: How does the EPA normally go from a Benchmark dose to a Safe Reference dose (RfD)?

Connett: The Benchmark dose is the best estimate of the dose that causes the defined harm (a loss of one IQ point) in a relatively small (800) number of children in the two studies considered. The RfD is determined by dividing the BMD by a safety factor sufficient to protect the most vulnerable child in a large population—in this case all the children being born today in the USA. The default value for this safety factor is usually set no lower than 10, and thus the safe reference dose for fluoride to protect the most vulnerable child from a loss of one IQ point would be 0.02 mg/liter (0.2 mg/liter divided by 10) for the level of fluoride in mother’s urine.

Passwater: Does the study suggest that any urine fluoride concentration above 0.02 mg/L would be unacceptable and “unsafe”? 

Connett: The answer is yes. The Centers for Disease Control (CDC) recommend communities fluoridate their water at 0.7 ppm to help reduce tooth decay. 0.7 ppm is 35-times higher than this estimated safe reference dose of 0.02 ppm (as measured in pregnant women’s urine).

However, for this the CDC only considered the harm to the dental enamel called dental fluorosis. It is now clear that dental fluorosis is not the most appropriate, the most sensitive, or most important end point of fluoride’s toxicity. For the developing fetus and infant, the brain is more sensitive to fluoride’s toxicity than the developing tooth. The big difference between these two endpoints is that dental fluorosis is more visible to the naked eye. Finding damage to the brain had to wait a very long time. It took over 60 years before the U.S. government funded these important IQ studies (Bashash, 2017 & 2018; and Green, 2019) and the infant study (Till, 2020).

Passwater: Grassroots actions helped ban lead-based paints and leaded gasoline. What can our readers do to help bring attention to how fluoridation is harming the brains of our children?

Connett: May I make 3 suggestions?

  1. Review our webpage regularly ( to get themselves fully informed on this issue.
  2. Hope and pray that there is no political interference in the NTP’s review of fluoride’s neurotoxicity.
  3. Write to their Congressional representatives and ask them to hold a hearing in whicH
    1. Scientists who have done this important work on fluoride and the brain can explain their findings;
    2. The CDC be questioned on why they continue to spend millions of taxpayers’ money promoting this practice and why they are not issuing warnings to pregnant women to avoid all sources of fluoride and not advising bottle-feeding parents to avoid using fluoridated water to make up baby formula.

See the recommendation by Lanphear, Till, and Birnbaum at Please also see the letter FAN and over 100 professionals have sent to Dr. Rochelle Walensky, the new head of the CDC:

Passwater: Thank you for your relentless efforts to protect our children. Hopefully science will prevail over dogma.