By Timothy Hyland
For more than six decades, cities and municipalities across the United States and Canada have been adding fluoride to public water systems with the worthwhile aim of improving dental health and preventing cavities.
But now, a new study suggests these efforts may be having unintended negative consequences.
The study, led by researchers from the University of Toronto and York University, examined the health histories of 213 mothers and children over the course of 11 years and found a notable link between higher levels of fluoride among pregnant women and babies who ultimately develop symptoms of attention-deficit/hyperactivity disorder (ADHD), including cognitive problems and inattentiveness.
ADHD is the most commonly diagnosed childhood mental health disorder. It affects approximately five percent of American children, according to the Centers for Disease Control, although some estimates range higher.
"The current findings provide further evidence suggesting neurotoxicity of early-life exposure to fluoride," the authors wrote. Their results were reported in the journal Environmental International.
Their work comes on the heels of other recent studies that have raised alarms regarding fluoride exposure – including possible links to lower IQs and higher rates of ADHD.
A 2015 study from York University – including members of the current research team – found that states with higher rates of fluoridation "tended to have a greater proportion of children and adolescents who received ADHD diagnoses."
A 2012 study from the Harvard School of Public Health and China Medical University concluded that children in China who had been exposed to higher fluoride levels showed poorer performance on IQ tests than other children. The authors of this piece recommended that further research be used to "clarify what role fluoride levels may play" in brain development. They also noted that while their judgments at the time did not allow them to make any final or definitive judgment on the risks of fluoride, they could also not say that "no risk is present."
This most recent work, building on those and other studies, looked specifically at the possible links between prenatal fluoride exposure and inattentive or hyperactive behaviors.
All of the women/children pairs in the study were from Mexico City, and all were recruited via the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) projects. Additional research support was provided by teams from the National Institute of Public Health of Mexico, University of Michigan, Indiana University, the University of Washington, and Harvard School of Public Health.
The research team analyzed urine samples from the mothers during their pregnancies, and also from the children when they were between the ages of six and 12. The children were then asked to complete a number of tests, and the researchers compared fluoride levels against each subject's test performance.
In the end, the team said the results showed that "children with elevated prenatal exposure to fluoride were more likely to show symptoms of ADHD," and that the high exposure was also "more strongly associated with inattentive behaviors and cognitive problems." The team did note they did not see a similar link to hyperactivity.
In a statement, study co-author Dr. Christine Till of York University – who also co-authored the 2015 study – noted that the symptoms of ADHD can prove problematic for sufferers well into adulthood. She said continued research into the link is essential.
“If we can understand the reasons behind this association, we can then begin to develop preventive strategies to mitigate the risk,” she said.
Author: Contributing writer Timothy Hyland has more than 20 years’ experience as a writer, reporter, and editor. His work has also appeared in Fast Company, Roll Call, Philadelphia Business Journal, and the Washington Times.
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