Higher Fluoride Exposure Linked to Reduced IQ in Children, Finds JAMA study
Recent research findings show that a higher amount of exposure to fluoride corresponds with decreased IQ in children according to an all-encompassing systematic review and meta-analysis. This study was conducted by Steven M. Levy which was published in the journal of JAMA Pediatrics. While fluoride has long been used to prevent dental cavities, growing concerns about total fluoride exposure from multiple sources including drinking water, toothpaste, and foods have highlighted potential neurodevelopmental risks.
This review and meta-analysis considered 74 epidemiological studies: 64 cross-sectional and 10 prospective cohort studies. In these, 52 studies were considered at high risk of bias, while 22 studies had a low risk of bias. Group-level fluoride exposure measurements were included in the analysis from 59 studies and individual-level measurements from 13 studies. Data were considered for 20,932 children; most of these focused on fluoride in drinking water, urine, or dental fluorosis.
Key Results
A significant inverse correlation between fluoride exposure and the IQ of children was found based on 59 studies that report group-level data for fluoride exposure. The SMD pooled is −0.45 (95% CI, −0.57 to −0.33; p< 0.001).
On a standard scale with a mean of 100, this SMD translates approximately into a reduction of 7 IQ points.
Minimal data and lack of assurance were observed in the dose-response relationship at fluoride levels below 1.5 mg/L in drinking water.
Exposure to fluoride came through intake from drinking water, water containing foods and beverages, toothpaste, floss, and mouthwash that raised concerns of cumulative fluoride load, especially for the pregnant females and children.
The WHO sets the limit of fluoride concentration in drinking water at 1.5 mg/L, but the EPA accepts up to 4 mg/L. The U.S. Public Health Service recommends a concentration of 0.7 mg/L for community water fluoridation. Still, water systems in the U.S. that service over 2.9 million people have levels of fluoride at or above 1.5 mg/L and may endanger the developing child's nervous system.
The study shows a clear negative association between fluoride exposure and the IQ of children, especially at higher exposure levels. Even though these results highlight the possible neurodevelopmental risks associated with excessive fluoride ingestion, more work is required to establish its safety at lower concentrations that are used in CWF. These results suggest a careful review of fluoride regulations to balance benefits to dental health with potential neurodevelopmental risks.
Reference:
Levy SM. Caution Needed in Interpreting the Evidence Base on Fluoride and IQ. JAMA Pediatr. Published online January 06, 2025. doi:10.1001/jamapediatrics.2024.5539
