A recent study analyzing 74 research papers from ten different countries has revealed a link between higher fluoride exposure and lower IQ scores in children, with the impact varying depending on the level of exposure. The study, which was published in JAMA Pediatrics, examined data from over 20,000 children across different continents.
This research adds to the ongoing discussions surrounding fluoride levels in drinking water. In the United States, where no similar IQ studies have been conducted, more than 2.9 million individuals receive water from systems that have natural fluoride levels exceeding international guidelines.
The study discovered that for every 1-milligram per liter increase in urinary fluoride, children’s IQ scores dropped by 1.63 points. This association remained significant even after adjusting for study quality and other variables.
The majority of the studies analyzed were from China (45 studies), with additional data from Canada, Denmark, India, Iran, Mexico, New Zealand, Pakistan, Spain, and Taiwan. The research covered areas with naturally occurring high fluoride levels as well as regions with water fluoridation programs.
The results highlight the importance of monitoring areas with elevated natural fluoride levels. Currently, the U.S. Environmental Protection Agency has set an enforceable standard of 4.0 mg/L and a recommended standard of 2.0 mg/L for fluoride in drinking water, while the World Health Organization recommends a level of 1.5 mg/L.
Although adverse associations were observed at levels below 2.0 mg/L when measuring fluoride in urine, which includes exposure from various sources like water, food, and dental products, the link between water fluoride levels and IQ scores became less clear below 1.5 mg/L.
There are significant disparities in fluoride exposure in the United States, particularly affecting Hispanic and Latino communities. The U.S. Geological Survey estimates that 172,000 Americans use domestic wells with fluoride levels exceeding the EPA’s highest standard, and 522,000 individuals use wells with levels higher than the recommended standard.
The CDC recommends that parents of children under 8 years old and parents of bottle-fed infants seek alternative water sources if their drinking water contains more than 2 mg/L of fluoride, primarily to prevent dental fluorosis rather than cognitive effects.
While the study did not focus on the broader public health implications of water fluoridation in the U.S., the findings could inform future assessments of fluoride exposure risks. This research is the most comprehensive analysis to date on fluoride’s potential cognitive impacts, but the authors stress the need for more studies, especially at lower exposure levels. There were no U.S.-based studies included, and data on American fluoride exposure levels are limited.
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