Increased Fluoride Exposure During Pregnancy Associated With Neurobehavioral Issues in Infants

The benefits and risks of fluorine have been a popular subject of debate in the scientific community for many years. In a new study, researchers from the University of Florida investigate the link between fluoride exposure in pregnancy and neurobehavioral issues in infants. The paper was published in JAMA Network Open.

Outweighing the benefits

Fluoride is a naturally occurring mineral commonly found in many foods and dietary supplements. The mineral is known for its ability to prevent and reverse the progression of tooth decay. Most fluoride consumption comes from fluorinated water or food prepared using such water. Nearly three-quarters of the US population has access to fluoridated tap water, although the benefits of this are often under scrutiny.

Recent studies from Canada and Mexico have identified an association between higher prenatal fluoride exposure and poorer neurobehavior development, however, it was not clear whether their results could be generalized to a US population. This latest study is believed to be the first US-based study to examine associations of prenatal fluoride exposure with parent-reported child neurobehavioral issues.

“There is no known benefit of fluoride consumption to the developing fetus, but we do know that there is possibly a risk to their developing brain,” said [RLS1] lead author Ashley Malin, an assistant professor in the Department of Epidemiology at the University of Florida Health.

Maternal fluoride exposure may impact neurodevelopment

The study analyzed data from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) study, looking at 229 mother-child pairs. Urine samples were collected from the participants during their third trimester of pregnancy to assess their individual fluoride exposure. When the child reached three years old, the mothers completed the Preschool Child Behavior Checklist, which looks at a child's behavior and emotions. They investigated symptoms of anxiety, difficulty regulating emotions and other concerns, such as stomach aches and headaches.

When combined with disinfecting agents, fluoride can cause lead to leach from lead-bearing water pipes. With this in mind, the researchers also conducted various additional analyses to ensure any neurobehavioral issues observed were not caused by lead.

“We found that each 0.68 milligram per liter increase in fluoride levels in the pregnant women’s urine was associated with nearly double the odds of children scoring in the clinical or borderline clinical range for neurobehavioral problems at age 3, based on their mother’s reporting,” said Malin.

Women with higher fluoride exposure levels during pregnancy also tended to rate their children higher on scoring scales related to autism spectrum disorder symptoms.

The fluoride levels identified in the study were typical of what would be expected in people living in communities with fluoridated water, however, the researchers noted they do not know whether their results are generalizable to other US populations.

There may be limitations

The authors hope their findings could lead to a change in policies for recommendations of fluoride consumption during pregnancy.

“I think this is important evidence, given that it’s the first US-based study and findings are quite consistent with the other studies published in North America with comparable fluoride exposure levels,” said Malin.

Professor Loc Do, a professor of dental public health in the School of Dentistry at the University of Queensland commented on the limitations of the study: “Exposure to fluoride in this study was measured by spot urinary fluoride analysis, which is highly variable within a person even during a day. Even 24-hour urinary fluoride measurement (a much more reliable exposure measurement) cannot measure chronic fluoride exposure in individuals.”

“The sample was very small (only 229), and not adequate to balance expected measurement errors. Even a few individuals with biased measurements could completely alter the overall findings,” added Do.

Professor Oliver Jones, a professor of chemistry at RMIT University also commented on the study: “If fluoride really did cause problems with brain development in children, we would expect to see this effect consistently worldwide, but we don’t. In fact, at least two recent studies found that maternal fluoride levels were actually associated with better cognitive scores in children.

Reference: Malin AJ, Eckel SP, Hu H, et al. Maternal urinary fluoride and child neurobehavior at age 36 months. JAMA Netw Open. 2024. doi: 10.1001/jamanetworkopen.2024.11987

This article is a rework of a press release issued by the University of Florida. Material has been edited for length and content.