Concerns About Data and Analyses Used in Assessing Fluoride Exposure and Children’s IQ Scores.

Abstract

Original Investigation

Fluoride Exposure and Children’s IQ Scores. A Systematic Review and Meta-Analysis.
Kyla W. Taylor, PhD; Sorina E. Eftim, PhD; Christopher A. Sibrizzi, MPH; Robyn B. Blain, PhD; Kristen Magnuson, MESM; Pamela A. Hartman, MEM; Andrew A. Rooney, PhD; John R. Bucher, PhD. JAMA Pediatrics. January 6, 2025.

Related Articles

• Comment. Assessing Fluoride Exposure and Children’s IQ Scores.
James W. Antoon, MD, PhD, MPH; Jayanth V. Kumar, DDS, MPH. JAMA Pediatrics.

• Comment. Assessing Fluoride Exposure and Children’s IQ Scores.
Robert C. Speth, PhD. JAMA Pediatrics.

• Response. Concerns About Data and Analyses Used in Assessing Fluoride Exposure and Children’s IQ Scores.
Kyla W. Taylor, Sorina E. Eftim, Andrew A. Rooney. JAMA Pediatrics.

To the Editor

The recent article “Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis”¹ has opened a floodgate of internet chatter regarding the issue of fluoridation of municipal water systems. Much of this chatter comes from opponents to fluoridation of municipal water systems, although 2 editorials accompanying the article by Taylor et al¹ were split regarding concerns about the addition of fluoride to municipal water supplies: Levy² challenged the conclusions of the article, while Lanphear et al³ called for reassessment of the risks and benefits of fluoridation of municipal water supplies. Now that the antifluoridation activist Robert F. Kennedy Jr. is secretary of the Department of Health and Human Services, fluoridation of municipal water systems may soon be prohibited. While fluoride-containing toothpaste provides substantial benefits for preventing tooth decay, many impoverished, underserved populations do not have ready access to fluoridated toothpaste and regular dental care.

One consideration that has not been sufficiently addressed by the analysis by Taylor et al¹ is the linear threshold model of toxicology, also known as no observed adverse effect level (NOAEL). The principle for this toxicological assessment is that very low concentrations of a toxic substance are too low to cause harmful effects, in this case, lowered IQ. Indeed, when considering the hormetic model of toxicology,⁴ exposure to low levels of a toxic substance can have beneficial effects. What is missing from the regression analyses of Taylor et al¹ is a determination of the X intercept; the point where the regression line crosses the x-axis when Y (the toxic response) equals 0. Based on the descriptions of the meta-analyses by Taylor et al,¹ if they had presented a regression line of their combined analyses, it likely would intercept the x-axis in the neighborhood of 1.5 mg/L, about twice the level of fluoride in fluoridated municipal water systems.

A meta-analysis of low- vs high-dose arsenic exposure, regressed across the risk of bladder, lung, and prostate cancers, showed best fits with a “hockey stick” model that mimics the linear threshold model (or “j-shaped” or “linear-quadratic” models that are reminiscent of the hormetic model of toxicology) with very low doses of arsenic reducing the risk of cancer.⁵ Thus, there is a need to include consideration of the linear threshold and/or hormetic toxicology models as well as the socioeconomic factors in support of the benefits of fluoridation of municipal water systems.

Corresponding Author: Robert C. Speth, PhD, Barry and Judy Silverman College of Pharmacy, Nova Southeastern University, 3300 S University Dr, Davie, FL 33328 (rs1251@nova.edu).

Published Online: May 12, 2025. doi:10.1001/jamapediatrics.2025.0929

Conflict of Interest Disclosures: None reported.