A report from the National Toxicology Program (NTP) into fluoride and its possible effect on the IQ of children is sparking debate.

The report released earlier this year concludes that higher levels of fluoride exposure (more than 1.5 mg/L) in drinking water is associated with lower IQ in children.

Fluoride Exposure: Neurodevelopment and Cognition. National Toxicology Program.

NTP Monograph on the State of the Science Concerning Fluoride Exposure and Neurodevelopment and Cognition: A Systematic Review. National Toxicology Program. NTP Monograph 08. August 2024.

“The public should know that the evidence presented in the NTP report is far from conclusive, even at the higher than 1.5 mg/L level of fluoride,” he says. “Government agencies responsible for protecting and promoting the health of the public will continue to review the latest science and make recommendations so that public water sources remain safe.”

Dr. Pollick notes that 1.5 mg/L is the WHO-recommended limit for naturally occurring fluoride in drinking water. “There is conclusive evidence that this is the concentration above which moderate dental fluorosis is likely to develop in children exposed to this level of fluoride in drinking water during the tooth-developing years, up to 9 years of age," he says. "The evidence that more than 1.5 mg/L fluoride in drinking water is associated with lower IQ is not conclusive, but there is a statistical association. Further well-controlled, long-term, prospective community-based research is needed."

What the report says

The NTP is part of the US Department of Health and Human Services. It began its investigation into fluoride and IQ in 2016.

Fluoride Exposure: Neurodevelopment and Cognition. National Toxicology Program.

But fluoride has been the focus of a public health initiative since 1945, and studies have proven it has assisted in the reduction of dental cavities and improving the overall oral health of the public.

Therefore, the NTP conducted an extensive review of published studies up to October 2023 on the association between fluoride exposure and neurodevelopment and cognition. The epidemiological studies included were primarily from outside of the US, including India, Iran, Canada, China, Mexico, and Pakistan. The review of the studies was intended to evaluate the total amount of fluoride exposure from all sources, not just drinking water alone.

Fluoride Exposure: Neurodevelopment and Cognition. National Toxicology Program.

The NTP used four “confidence levels” to indicate the strength of evidence associated with certain health outcomes from an exposure. The levels were high, moderate, low, or very low.

Fluoride Exposure: Neurodevelopment and Cognition. National Toxicology Program.

In its final report, the NTP concluded that there is moderate confidence in evidence that suggests an association between higher levels of fluoride and lower IQ in children.

NTP Monograph on the State of the Science Concerning Fluoride Exposure and Neurodevelopment and Cognition: A Systematic Review. National Toxicology Program. NTP Monograph 08. August 2024.

However, the NTP stated that there was not enough evidence to determine if the level of fluoride in drinking water of 0.7 mg/L (which is currently recommended in the US water supply) has a negative impact on the IQ of children.

Scrutiny of public health practices

“With the overwhelming access to information, and misinformation, online, many tried-and-true practices related to public health and well-being such as vaccines, genetically modified foods, and fluoride, and so many more, are being questioned by well-meaning people,” she tells MDLinx.

But the truth is, these scientific advances have been life saving for billions of people around the globe.

“Many of us who are now parents, myself included, are raising children in a time where we have never had to experience the epidemics of polio, or Haemophilus influenzae type-b meningitis. My children have yet to have a cavity, and instead of focusing on filling cavities, I get to save up for braces and cosmetic dental work. These advances are unique to our generation and due largely in part to these public health practices.”

The ADA’s evaluation of the report found that “the monograph does not provide any new or conclusive evidence that should necessitate any changes in current community water fluoridation practices for public health policy consideration.” The ADA took particular exception to the fact that one of the studies on IQ that the NTP reviewed were conducted in the US but were instead "from areas with high levels of naturally-occurring fluoride in water.”

Anderson O. National Toxicology Program releases fluoride exposure monograph. American Dental Association. August 27, 2024.

Representatives from the American Academy of Family Physicians also endorse fluoridation of community water. “We're very much in favor of fluoridation of public water. This has been a long-term public health measure that's reduced the rate of tooth decay and associated health issues,” Jay W. Lee, MD, MPH, FAAFP, board member of the American Academy of Family Physicians, tells MDLinx.

What can physicians do?

“Once you've shown that ability to be open to the patient’s and family's concerns, [use] your expertise to allay their fears, to talk about the fact that the water supply fluoride levels are less than half of the concentration that was quoted in the report, and that there's been a long history of fluoride in the water and the resulting public health benefits,” he says. “I would argue, as somebody who also has a master's in public health, that this is one of the greatest public health achievements that we've had in the last century, and we shouldn't minimize that, because of the impacts of chronic tooth decay.”