The National Toxicology Program of the National Institutes of Health (NIH) conducted a systematic review of the potential neurological effects of fluoride and found that higher fluoride exposures are consistently associated with lower IQ in children.
In short:
- Nineteen “high-quality” studies on fluoride exposure and IQ in children were conducted in 5 countries (Canada, China, Mexico, India and Iran); of these, 18 found that higher fluoride levels were associated with a lower IQ, as did 46 of 53 “low-quality” studies.
- These associations are mainly – but not exclusively – seen at exposure levels above the World Health Organization’s upper limit for fluoride in drinking water (1.5 mg/L).
- There was not adequate evidence to evaluate the associations in adults.
Key quote:
“This Monograph and Addendum do not assess benefits of the use of fluorides in oral health or provide a risk/benefit analysis.”
Why this matters:
The fluoridation of water is a hotly debated topic. The two Canadian studies examined here covered 10 cities, some with fluoridated drinking water near the levels recommended by the U.S. Public Health Service (0.7mg/L), some at lower levels, and some without fluoridated water. Though one evaluated prenatal exposure and the other postnatal exposure, both found evidence of lower IQ in children exposed to higher fluoride levels during development. In the U.S., about 3.5 million people are served by community water systems with naturally-occurring fluoride above 1.1mg/L, putting them at potential risk. These scientific findings are complicated, and should be considered in the context of fluoride levels (both natural and added), the timing of exposure (prenatal, postnatal, childhood, adult), the route of exposure (drinking water, diet, etc.), and the potential risks and benefits of fluoridation. The risk of low level fluoride exposure is still uncertain.
Related EHN coverage:
More resources:
- WATCH: Fluoride, Neurodevelopment, and Cognition: A National Toxicology Program Monograph webinar, sponsored by the EDC Strategies Partnership and scheduled for Dec. 3, 2024 (a recording will be available following the webinar).
National Toxicology Program (NTP), NTP Monograph on the State of the Science Concerning Fluoride Exposure and Neurodevelopment and Cognition: A Systematic Review, NTP monograph (8), 2024.
Original article online at: https://www.ehn.org/ntp-flouride-study-2670163133.html