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Study: Evidence does not support classifying fluoride as cognitive neurodevelopmental hazard

National Academies of Sciences, Engineering, and Medicine reviewed draft monograph that alleges fluoride ‘presumed’ a health hazard

March 10, 2020

By David Burger

 Image of Water Fluoridation

Washington — The National Academies of Sciences, Engineering, and Medicine announced March 5 that it does not find that the National Toxicology Program adequately supported its conclusion that fluoride is “presumed” to be a cognitive neurodevelopmental hazard to humans.

The academies released its 37-page review of the National Toxicology Program’s draft monograph, “Systematic Review of Fluoride Exposure and Neurodevelopmental and Cognitive Health Effects” after months of concern and anticipation from all who are invested in the developing science around water fluoridation.

The ADA’s National Fluoridation Committee, a multidisciplinary team composed of experts from dentistry, academia and research, issued a statement after the review was released: “Based on the major concerns raised by the National Academies of Sciences, Engineering, and Medicine review, it is hoped that the National Toxicology Program will substantially revise their draft monograph and provide an adjusted statement to better reflect the status of current science with respect to the cognitive neurodevelopmental hazard of fluoride to humans.”

The National Toxicology Program, run by the National Institutes of Health, conducted a systematic review to evaluate the evidence that exposure to fluoride could be associated with neurodevelopmental or cognitive effects. The National Academies then assembled a committee to review the monograph, assessing whether the scientific evidence in the monograph supports the NTP’s hazard category conclusions for fluoride in children and adults.

After the draft monograph was first issued, the ADA affirmed its support for the effectiveness and safety of community water fluoridation by sending comments Nov. 19, 2019, to the National Toxicology Program. The Association’s letter, signed by Dr. Chad P. Gehani, ADA president, and Dr. Kathleen T. O’Loughlin, ADA executive director, was sent the same week as similar letters from the American Academy of Pediatric Dentistry and the Association of State and Territorial Dental Directors.

All questioned the validity and methodology of many of the studies included in the review. The National Fluoridation Advisory Committee helped to assess the monograph and its findings.

“Our panel of experts concluded that the available literature is insufficient to establish causation between fluoride exposure as experienced in the United States and neurocognitive development,” wrote Drs. Gehani and O’Loughlin in the November letter. “It found that the literature generally is either lacking, unreliable, inconclusive, conflicting or subject to widespread interpretation. Given the state of the literature, we ask that you revisit the monograph’s draft hazard rating that fluoride is ‘presumed to be a cognitive neurodevelopmental hazard to humans.’”

Drs. Gehani and O’Loughlin also called into question the monograph’s inclusion of studies that used higher-level exposures, above 1.5 parts per million. “It is also critical to the public’s health that you include some type of modifier to distinguish the health benefits of optimally fluoridated drinking water, currently recommended at 0.7 parts per million, from the higher level exposures the monograph addresses,” wrote Drs. Gehani and O’Loughlin.

The ADA letter was accompanied by “Fluoridation Facts,” an Association-published reference on the latest evidence-based information on water fluoridation.

The ADA National Fluoridation Advisory Committee concluded, “The ADA is truly gratified when, in the interest of the public’s health and welfare, communities provide optimally fluoridated water to their residents. The current classification is misleading to the public, could scare them unnecessarily and could ultimately decrease the oral health status of individuals and communities.”

The National Academies’ review committee emphasized its finding does not mean that the National Toxicology Program’s conclusion is incorrect. Rather, further analysis or reanalysis is needed to support conclusions in the monograph, the review committee said. The committee did not conduct its own independent evaluation of the evidence and it did not conduct a data audit.

The report states that the monograph was initiated in part because of a nomination from the Fluoride Action Network — which according to its website “seeks to broaden awareness among citizens, scientists, and policymakers on the toxicity of fluoride compounds” — prompting the National Toxicology Program to conduct its systematic review.

The review committee also recommended that the National Toxicology Program should state clearly that the monograph is not designed to be informative regarding decisions about fluoride concentrations for water fluoridation.

The review of the monograph was sponsored by the National Institute of Environmental Health Sciences. The National Academies are private, nonprofit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology and medicine.

“Fluoridation Facts” is among a number of free ADA resources on community water fluoridation, which the ADA has supported since 1950, according to the publication. Other resources are located online at ADA.org/fluoride.