New research suggests that daily exposure to fluoride may affect cognitive development in children.

A new study by the Karolinska Institutet in Sweden provides evidence that exposure to fluoride during pregnancy or toddlers may impair cognitive development in children, even at previously considered safe levels.

The study, published on March 5 in the journal Environmental Health, was accompanied by 500 mothers in rural Bangladesh over a decade, tracking their exposure to naturally occurring fluorides and measuring cognitive abilities at ages 5 and 10 in children.

“Our results support the hypothesis that even relatively low concentrations of fluoride fluoride can affect early childhood development,” said Maria Kippler, the Karolinska Institutet and author of the study.

The study was conducted in Bangladesh and the findings raised questions about global fluoride exposure, including areas where it is often added to public drinking water to prevent tooth decay.

Research reveals cognitive impacts at multiple life stages

The researchers found that higher exposure to fluoride during pregnancy was associated with lower cognitive scores in children aged 5 to 10 years. Similarly, at the age of 10, children with higher contemporary fluoride exposure showed a decrease in cognitive ability, although this effect only occurs above certain concentration thresholds.

The group used urine samples to measure fluoride exposure and found that children of pregnant women with higher urine levels (median: 0.63 mg/L) performed poorly in cognitive testing, especially in the areas of perceptual reasoning and speech skills. The association has been persistent after considering a variety of factors including socioeconomic status, maternal education and family environment.

For children, the findings showed that fluoride exposure at 10 years of age (median: 0.66 mg/L) was associated with a lower cognitive score when concentrations exceeded 0.72 mg/L. At a young age, the relationship is not very clear, which may be due to changes in the physical process of children growing and retaining fluoride.

“In young children, more than half of the fluoride intake can be retained in the bones,” the researchers noted. He explained why measuring exposure in young children is more complicated.

Balancing dental benefits with potential risks

This study has increased the increasing attention to the potential neurotoxicity of fluoride. While decades of research support the role of fluoride in preventing dental caries, this study highlights possible tradeoffs that may require careful consideration.

In parts of North America, including the United States and Canada, fluoride is usually added to municipal water supply at a level of about 0.7 mg per liter. Some European countries have adopted a more cautious attitude, and many have chosen to oppose water fluorination.

“The addition of fluoride in drinking water is controversial, and has been widely debated in the United States and Canada,” Dr. Kippler noted.

Researchers stress that toothpaste products such as toothpaste usually contain higher fluoride concentrations and are not an important issue when used as directed.

“I want to emphasize that dental care products such as toothpaste are often not important sources of contact because they are not intended to be consumed,” Dr. Kippler said. “The fluoride in toothpaste is important for preventing dental caries, but it is important to encourage children not to swallow toothpaste during brushing.”

Impact on water safety standards

The study found adverse reactions at levels below current regulatory thresholds. The World Health Organization recommends that the upper limit of fluoride in drinking water is 1.5 mg/L, but this study shows that the impact on children’s cognitive development may occur at lower concentrations.

In the Bangladesh cohort, the fluoride concentration (median: 0.20 mg/L) of drinking water was associated with moderate urine levels, indicating that water is likely to be a significant source of exposure. These levels are comparable to the non-fluorinated zones in North America, with natural fluoride levels typically ranging from 0.04-0.20 mg/l.

This study enhances similar findings from studies conducted in Mexico and Canada, where fluoride exposure during pregnancy is also associated with cognitive effects in children.

Looking to the future

The researchers acknowledged their research limitations, including relying on a single point of urine sample at each evaluation point. They are now working to study these associations in other populations and build experimental models to identify possible biological mechanisms.

“More research is necessary to create a strong foundation for reviewing fluoride health risks and thresholds for drinking water, food and dental care products, especially for children,” Dr. Kippler noted. “Even small changes in cognitive aspects at the demographic level can have serious public health consequences.”

Compared with many previous studies that reported gender differences in fluoride effects, some of which indicated stronger effects in boys and other girls, this study found no consistent pattern of differential effects between genders.

This research was mainly funded by grants from the Swedish Research Council and Swedish Environmental, Agricultural Sciences and Space Planning. Researchers declared no conflicts of interest.

Note: This article reports a peer-reviewed observational study. Although these findings suggest an association between fluoride exposure and cognitive effects, they do not establish direct causal relationships. Public health decisions regarding fluoride should consider overall evidence of benefits and potential risks.