Study Against Fluoride in Tap Water Refuted by New Analysis

A new analysis published in the Journal of Community Dentistry & Oral Epidemiology has found that a 2019 study that purported fluoridated tap water negatively impacted children’s IQ scores is incorrect. This 2019 study, originally published in the Journal of the American Medical Association (JAMA) Pediatrics, is considered “unacceptable for legal and policy purposes,” according to a press release from the American Fluoridation Society.

The Canadian study examined data from the Maternal-Infant Research on Environmental Chemicals (MIREC) database, comparing IQ scores in fluoridated and non-fluoridated cities across Canada. Per the new analysis, these data are unreliable based on the methodology of the research. The original study took estimated fluoride levels of pregnant women by using spot urine sample during their pregnancies, and spot samples cannot be admissible in measuring fluoride exposure. Moreover, IQ scores across the aforementioned Canadian cities were similar or identical in most cases, per the analysis.

Additionally, the IQ tests that were administered were different in each city.

The analysis concludes, “Because the MIREC database offers neither valid data on maternal or fetal fluoride exposure, nor reliable measures of the IQ of the resulting children, the database cannot be used to make claims that fluoride exposure affects IQ.”

“This analysis is huge. It means that 7 Canadian studies that stand on the MIREC database have come tumbling down like a house of cards,” President of the American Fluoridation Society said in the press release. “It’s important that we hold all research to high standards.”

As tooth decay remains the most chronic disease for both children and adults, the authors of the analysis as well as the American Fluoridation Society call on JAMA Pediatrics to retract the initial study. In 2023, a systematic review found that 29 out of 30 fluoride-IQ studies were at a moderate to high risk of bias, per the press release, while the singular low risk study found that there was no link between fluoride and IQ scores.

To read more about fluoridation or the analysis, please visit the American Fluoridation Society’s website here.