A small increase in fluoride exposure during pregnancy can double the risk of neurobehavioral issues in young children
Pregnant women who drink fluoridated water are exposing their babies to a significantly increased risk of serious neurobehavioral issues in childhood, according to a new study.
Just under 75% of the US population receives a fluoridated water supply at a targeted concentration of 0.7 milligrams per liter.
The new research, published in JAMA Network Open, found that this targeted concentration is enough to increase the risk of neurobehavioral issues in children at age three, and that a 0.68 milligram per liter increase in fluoride exposure could double the risk of a child displaying such issues.
Animal studies have consistently shown that high levels of fluoride exposure cause serious changes to neurobiochemical changes, and that fluoride can cross the placental barrier between a mother and her child.
But recent human studies from Mexico and Canada have suggested that even low levels of exposure during pregnancy could be linked to lower IQ, reduced cognitive function and increased symptoms of ADHD.
The new study took 229 mother-child pairs from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) cohort, which consists of mainly Hispanic women living in urban Los Angeles, California. The participants were recruited during prenatal care visits between 2015 and 2020.
The researchers took single spot urine samples from the mothers during their third trimester of pregnancy (weeks 29 to 40). The samples were analyzed for urinary fluoride levels, as an index of total fluoride intake. The median urinary fluoride concentration among the mothers was 0.76 milligrams per liter.
When the children reached the age of three years, their mothers completed the Preschool Child Behavior Checklist (CBCL), a commonly used measure of children’s cognitive development and behaviour. The CBCL includes 99 items that assess a range of behavioral and emotional problems, from depression and withdrawal to attention problems and aggression, and diagnosable conditions like ADHD and autism-spectrum disorders.
A key finding of the study was that a 0.68 milligram per liter increase in maternal urinary fluoride levels during pregnancy was associated with nearly double the odds of the child scoring in the borderline clinical or clinical range for total neurobehavioral problems.
As well as being associated with an overall increase in the risk of neurobehavioral problems, higher fluoride exposure was also associated with specific issues. A 0.68 milligram per liter increase was associated with a 13.54% increase in scores for emotionally reactive behaviors, for example, and a 19.60% increase in somatic complaints.
There was also an 11.29% increase in anxiety problems and an 18.53% increase in autism-spectrum problems.
“Women with higher fluoride exposure levels in their bodies during pregnancy tended to rate their 3-year-old children higher on overall neurobehavioral problems and internalizing symptoms, including emotional reactivity, anxiety and somatic complaints,” said Tracy Bastain, an associate professor at the University of Southern California and senior author of the study.
“I think this is important evidence, given that it’s the first U.S.-based study and findings are quite consistent with the other studies published in North America with comparable fluoride exposure levels,” added the study’s lead investigator Ashley Malin.
“Conducting a nationwide U.S. study on this topic would be important, but I think the findings of the current study and recent studies from Canada and Mexico suggest that there is a real concern here.”
