Fluoride is added to drinking water in many countries to prevent cavities, but new research suggests even low exposure may impact children’s cognitive abilities.
A study in Bangladesh tracked 500 mothers and their children, linking higher fluoride levels to reduced cognitive performance, particularly in verbal reasoning and sensory processing. While fluoride in toothpaste is generally safe, its presence in water may pose risks. Scientists stress the need for further research to reassess fluoride safety limits in drinking water and other sources.
Fluoride in Drinking Water: A Common but Controversial Practice
Fluoride naturally occurs in drinking water as fluoride ions, but its concentration is usually low in public water supplies. In some countries, including the United States, Canada, Chile, Australia, and Ireland, fluoride is intentionally added to municipal water at approximately 0.7 mg per liter to help prevent tooth decay.
“Given the concern about health risks, the addition of fluoride to drinking water is controversial and has been widely debated in the USA and Canada,” says Maria Kippler, associate professor at the Institute of Environmental Medicine, Karolinska Institutet. “Our results support the hypothesis that even relatively low concentrations of fluoride can impact children’s early development.”
Tracking Fluoride Exposure in Mothers and Children
To better understand fluoride’s impact on cognitive development, researchers studied 500 mothers and their children in rural Bangladesh, where naturally occurring fluoride is present in drinking water at levels similar to those found in other parts of the world.
Psychologists assessed the children’s cognitive abilities at ages five and ten using established tests. Fluoride exposure was determined by analyzing fluoride concentrations in urine samples from both mothers and children. These measurements provided insight into overall exposure from multiple sources, including drinking water, food, and dental products.
“I’d like to stress that dental care products such as toothpaste are not normally a significant source of exposure since they are not intended for ingestion,” says Dr. Kippler. “Fluoride in toothpaste is important for prevention of caries, but it’s important to encourage small children not to swallow the toothpaste during brushing.”
Higher Fluoride, Lower Cognitive Abilities
The median concentration of fluoride in the urine of the pregnant Bangladeshi women was 0.63 mg/L. Increasing concentrations of fluoride in pregnant women could be linked to decreasing cognitive abilities in their children at five and ten years of age.
Children who had more than 0.72 mg/L fluoride in their urine by the age of ten also had lower cognitive abilities than children with less fluoride in their urine, with the most pronounced associations for verbal reasoning skills and the ability to interpret and process sensory input. The exposures that were associated with impaired cognitive development are lower than those obtained at the existing WHO and EU threshold for fluoride in drinking water, which is 1.5 mg/L.
The researchers found no statistically significant link between fluoride concentrations in the urine of the five-year-olds and their cognitive abilities.
“This may be due to the shorter exposure time,” Dr. Kippler speculates, “but also to the fact that urinary fluoride concentrations aren’t as reliable in younger children owing to greater variations in how much fluoride is taken up and stored in the body, particularly in the bones.”
The Need for More Research
Since it was an observational study, no firm conclusions can be drawn about causalities. It is therefore important to assess the overall results of several similar longitudinal studies, according to the researchers. They will now investigate the associations in other populations and establish experimental models to determine the possible molecular mechanisms driving it.
“There is a need for more research to create a robust basis for reviewing fluoride health risks and thresholds for drinking water, foods, and dental care products, especially for children,” she continues. “Even small changes in cognition at a population level can have serious public health consequences.”
Reference: “Prenatal and childhood exposure to fluoride and cognitive development: findings from the longitudinal MINIMat cohort in rural Bangladesh” by Taranbir Singh, Klara Gustin, Syed Moshfiqur Rahman, Shamima Shiraji, Fahmida Tofail, Marie Vahter, Mariza Kampouri and Maria Kippler, 5 March 2025, Environmental Health Perspectives.
DOI: 10.1289/EHP14534
The study was mainly financed by national grants from the Swedish Research Council and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning. The researchers have declared no conflicts of interest.
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14 Comments
Fluoride is most likely a neurotoxin. I suspect that this Assay, IQ, has a low sensitivity and specificity. What other things does it do over a life time. It’s sort of like sun exposure. Tests may show that a lot of it causes sun burn but even low levels over a lifetime can cause skin cancer, you don’t have to get a sunburn.
More research is obviously needed. My two boys grew up drinking water from a deep well, no fluoride. They’re both brilliant engineers, one has a Masters from Ga Tech, where he graduated with highest honors and a Masters, the other has a PhD in Chemical engineering. Their teeth are fine, not a lot of cavities.
Mom does have a MD, and I have a MD, PhD so they were taught at home in addition to excellent private schools.
You, of all people, should recognize that what you have provided is called anecdotal evidence. The Scientific Method requires double-blind experiments of a large number of people to have any statistical significance.
Anecdotal evidence from enough people may well trigger scientific research. Keep carping!
Is this reliable? Are there even universities in Bangladesh to conduct research?
Apparently this was funded by Swedish organizations, and carried out by the Institute of Environmental Medicine, Karolinska Institutet in Sweden.
“Is Fluoride Lowering Children’s IQ?”
Implicit in the question is that it might be happening. However, the well known ‘Flynn Effect’ suggests that the worldwide IQ was increasing during the time that fluoridation was being introduced and spreading, particularly in advanced countries. While Copilot (LLM) suggests that there is evidence of recent declines, it doesn’t mention fluoridation as one of the possible contributors. Therefore, the researchers may be observing a spurious correlation. The researchers responsibly note, “Since it was an observational study, no firm conclusions can be drawn about causalities.”
What is troubling is that the mean IQ is supposed to be 100, yet Copilot claims that the mean is currently about one standard deviation below that, forecasting it to drop even more by 2100.
Go tell copilot about it. If you can’t think for your self, leave us out of your feebleminded ruminations.
There is a difference between “thinking” and gathering facts. Only the feeble-minded don’t understand that. If you have a citation that you can provide that contradicts Copilot’s summary, please provide it instead of resorting to insults.
Well after 80 years, someone finally decided to look into this. Not impressed.
MORE Excuses For TERRIBLE, IDIOT, LAZY PARENTS! And That’s ALL THE PARENTS NOW! LOL!
Let’s GROW UP!
I think bad chemicals and bad parenting are equally to blame.
The most satisfactory way of keeping teeth in good order is to avoid junk food, sweet fizzy drinks, sweets and overmuch sugar in one’s diet and simply brush them effectively twice a day. Good bones? Eat a decent diet and drink an adequate amount of milk each day as then your children won’t develop rickets. That could be mere anecdotal evidence, but free school milk and the former British ration diet between 1939 and 1954 built a healthy generation of people, unlike today’s obese mob.
Don’t chew betel nut; anecdotal evidence, that stains teeth black and can cause mouth cancer.
A small sample size in Bangladesh, the city with the worst average air quality in the entire world. I’m sure air pollution has nothing to do with the results, eh?
This study is dubious at best.
Fluoridation, Mandrake…