Written by Hannah Harp
Spoon Feed
A negative correlation was found between fluoride exposure and children’s IQ. However, there is no significant correlation at the current EPA-recommended levels of community water fluoridation.
The tooth, the whole tooth, and nothing but the tooth
Fluoride supplementation has been shown to be a cost-effective way to prevent dental caries. However, community water fluoridation has become a hot topic we covered recently, because animal studies suggested fluoride’s potential neurotoxic effects. There have been multiple systematic reviews on this topic, but this review boasts very detailed subgroup analyses that add some more nuance to its results. This systematic review and meta-analysis examined the association between fluoride exposure and children’s IQ. A total of 74 studies (64 cross-sectional, 10 cohort) were analyzed. The pooled standardized mean difference (SMD) for fluoride exposure and IQ was -0.45 (95%CI, -0.57 to -0.33; p < .001). Individual-level urinary fluoride analyses showed a 1.63-point IQ decrease per 1 mg/L increase in fluoride concentration (95%CI, -2.33 to -0.93; p < .001). Results suggest a dose-response relationship, particularly above 1.5 mg/L. Many of the limitations of this study were mitigated by subgroup analysis, including the fact that most included studies were rated high risk of bias. All included studies are international studies (mostly from China), and there has never been such a study published in the US. The biggest caveat around this analysis for me is that there is no significant correlation detected at less than 1.5mg/L – EPA recommends 0.7mg/L for community water supply fluoridation, and ADA recommends a range of 0.7mg/L-1.2mg/L.
How will this change my practice?
There are areas where groundwater naturally contains a lot of fluoride, so perhaps a word of caution if you live in such a place. My city’s water supply has a fluoride level of 0.7ppm, and my most-used ICD-10 code is K02.9 (dental caries), so I won’t stop recommending fluoridated drinking water and toothpaste just yet.
Source
Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis. JAMA Pediatr. 2025 Mar 1;179(3):282-292. doi: 10.1001/jamapediatrics.2024.5542. PMID: 39761023
