ADA calls for major revisions to NTP fluoride monograph

Association leaders question methods, messaging, transparency

The ADA sent five recommendations for the National Toxicology Program’s third draft report on a systematic review exploring a possible relationship between fluoride exposure and neurodevelopmental and cognitive health.

The recommendations were sent in an April 28 letter to Kathleen M. Gray, Ph.D., chair of the NTP Board of Scientific Counselors. The ADA’s comments, submitted in response to the NTP’s notice in the Federal Register March 31, were sent in advance of the Board of Scientific Counselors meeting on May 4.

The systematic review, which has been in progress for several years, is intended to summarize the literature about a possible relationship between fluoride exposure and neurodevelopmental and cognitive health. The original report has been revised several times, a common practice for peer-reviewed papers.

“We urge the BSC to adopt the following recommendations to improve the report’s scientific integrity, clarity, transparency, and timeliness — and to support the lay public’s scientific literacy and that of local elected officials who determine community water fluoridation policies,” said the letter signed by ADA President George R. Shepley, D.D.S. and Executive Director Raymond A. Cohlmia, D.D.S. The letter also included several attachments outlining the reasons behind the five recommendations.

The ADA recommended that:

• NTP should complete the full course of peer review with its original independent peer review panel, the National Academies of Sciences, Engineering, and Medicine. NASEM is the acknowledged gold standard for peer review.
• NTP should update and publish its meta-analysis of epidemiological studies, but only after it completes a peer review by NASEM or has been accepted for publication in a reputable journal, as the BSC Working Group recommended.
• NTP should provide clear context for statements about low-level fluoride exposures, as NASEM recommended.
• NTP should include a stand-alone disclaimer indicating that the report should not be construed as an indictment of low-level fluoride exposures, as NASEM recommended.
• NTP should revise its risk of bias rating for several studies, based on NASEM’s concerns and an ADA analysis.

Earlier drafts contained a hazard assessment stating fluoride is “presumed to be a cognitive neurodevelopmental hazard to humans,” regardless of exposure level. The hazard assessment was later removed after NASEM reported in its second review, “[T]he monograph falls short of providing a clear and convincing argument that supports its assessment.”

The ADA emphasized the need for a disclaimer about the report’s treatment of low-level fluoride exposures, including concentrations recommended for community water fluoridation.

“[NTP’s] examination of the literature on low-level fluoride exposures did not validate the hypothesis that consistent exposure to low levels of fluoride (<1.5 mg/L) poses a risk to neurodevelopmental and cognitive health,” Drs. Shepley and Cohlmia wrote. “Additional research may inform that point.”

The BSC has scheduled a May 4 virtual meeting to discuss whether NTP adequately addressed outside questions and criticisms of its methods, conclusions, clarity, and transparency.