From the Guidelines
The current scientific evidence does not support a causal link between fluoride at levels used in community water fluoridation and either lower IQ or autism, as the majority of well-designed studies examining fluoride at these regulated levels have not found significant negative impacts on neurological development or autism rates. While some studies have suggested associations between very high fluoride exposure and cognitive effects, these typically involve concentrations much higher than those used in public water systems, as noted in a meta-analysis that found greater exposure to high levels of fluoride in water was significantly associated with reduced levels of intelligence in children 1. In the context of community water fluoridation, the levels of fluoride used are carefully determined to prevent tooth decay while minimizing any potential risks. The benefits of fluoride for dental health are well-established, reducing cavities by about 25% in both children and adults.
Some key points to consider include:
- The fluoridation of drinking water aims to bring fluoride levels up to a range preventing or minimizing tooth decay by 26-44% in children, teenagers, and adults 1.
- Fluoride can be safely provided in nutritional intakes up to 4 mg/day in men and 3 mg/day in women, with some studies suggesting beneficial effects on bones and teeth at doses of up to about 3 mg/day 1.
- Health organizations worldwide, after reviewing the totality of evidence, continue to support water fluoridation as a safe and effective public health measure, although some controversy exists due to methodological limitations in certain studies, including inadequate control for confounding factors.
It is essential to note that the evidence from older studies, such as those from 2001, may not be as relevant to current practices and guidelines, as they may not reflect the most up-to-date research and recommendations 1. If you have specific concerns about fluoride exposure, discussing them with a healthcare provider who can consider your individual circumstances is recommended.
From the Research
Association between Fluoride and IQ or Autism
- The relationship between fluoride exposure and IQ or autism is a topic of ongoing research and debate.
- A study published in 2020 2 found that while some epidemiological studies suggest an association between high fluoride exposure and reduced intelligence, the evidence from animal experiments and in vitro analyses does not support the notion that fluoride is a human developmental neurotoxicant at current exposure levels.
- Another study published in 2025 3 found that fluoride exposure in childhood was associated with a slightly increased risk of autism spectrum disorder (ASD), attention deficit-hyperactivity disorder (ADHD), intellectual disability (ID), and specific delays in development (SDD).
- However, it is essential to note that the evidence on this topic is not yet conclusive, and more research is needed to fully understand the potential effects of fluoride on IQ and autism.
Fluoride Exposure and Neurodevelopmental Disorders
- The study published in 2025 3 found that fluoride exposure in the year of birth was associated with a slightly increased risk of ASD, ADHD, ID, and SDD.
- The same study found that children who were fluoride-exposed during the first 10 years of life were at significantly greater risk for ASD, ID, and SDD compared to unexposed children.
- However, the study also found that fluoride exposure was associated with a slightly reduced risk of tooth decay, highlighting the need for a balanced approach to fluoride use and exposure.
Limitations and Future Research
- The current evidence on the relationship between fluoride and IQ or autism is limited by the quality of the studies and the potential for confounding factors.
- Further research is needed to fully understand the potential effects of fluoride on IQ and autism, including studies that control for confounding factors and use robust methodologies.
- The study published in 2020 2 highlights the importance of considering the margin of exposure between no observed adverse effect levels in animal studies and current adequate intake levels in humans when evaluating the potential risks of fluoride exposure.