Experts differ as study links children’s low IQ with fluoride exposure

A recent study has ignited a debate among experts, with its findings suggesting a potential link between lower IQ scores in children and fluoride exposure.

While the study has raised concerns about the safety of fluoride in drinking water, some scientists are urging caution, emphasising the need for further research and highlighting the crucial role of fluoride in preventing tooth decay.

The study examined the relationship between children’s intelligence quotient (IQ) scores and their exposure to fluoride before or after birth and found a possible link between higher fluoride exposure and lower IQ scores.

The research published by the Journal of the American Medical Association analysed 74 studies.

For water fluoride, it found a link where the level is below 4 miligram (mg) per litre and 2mg per litre, but not below 1.5 mg.

In urine, the children’s low IQ were associated with fluoride at below 4mg per litre, and 1.5 mg.

In studies with lower risk of bias, the link held consistently across all exposure levels for both water and urine fluoride.

In countries with much higher levels of fluoridation, the analysis also found evidence of what scientists call a dose-response relationship, with IQ scores falling in lock step with increasing fluoride exposure.

Other than drinking water, children are exposed to fluoride through many sources such as toothpaste, dental treatments, some mouthwashes, as well as black tea, coffee, and certain foods, such as shrimp and raisins, according to the study.

Some drugs and industrial emissions also contain fluoride. For every one part per million increases in fluoride in urinary samples, which reflect total exposures from water and other sources, IQ points in children decreased by 1.63, according to the analysis.

“There is concern that pregnant women and children are getting fluoride from many sources,” said Kyla Taylor, an epidemiologist and the report’s lead author said in a New York Times report. “Their total fluoride exposure is too high and may affect fetal, infant and child neurodevelopment.”

Taylor said that the analysis was meant to contribute to the understanding of the safe and effective use of fluoride. But she said it did not address the benefits and was not intended to assess “the broader public health implications of water fluoridation in the United States.”

Several scientists, including many dentists, criticized the report, pointing to what they said were methodological flaws and emphasising that the research did not have implications for U.S. drinking water.

The subject is so divisive that JAMA Pediatrics commissioned two editorials with opposing viewpoints to publish alongside the report.

In one, Steven Levy, a public health dentist at the University of Iowa, said that many of the studies included in the analysis were of very low quality. He also warned against concluding that any changes should be made in American fluoridation policies.

“A lay reader or policymaker at a water board in a small community somewhere may see the evidence and think that every way you analyze it, it’s a concern,” Levy said in an interview. “It isn’t as clear-cut as they’re trying to make it.”

Some studies have suggested that dental health has improved not because fluoride was added to water, but because of fluoridated toothpastes and better dental hygiene practices.

Read also: Here are 10 African countries with the lowest IQ in 2024

According to this argument, topical application of fluoride to teeth is effective enough to prevent tooth decay, and ingestion is unnecessary. However other studies have reported increases in cavities after public water fluoridation initiatives ceased in some countries.

Folake Oredugba, professor of Paediatric Dentistry at the Lagos University Teaching Hospital (LUTH) agrees with this argument saying that fluoride protects the teeth from decay.

She said there haven’t been local studies to confirm the position of the new research, noting that the professional bodies that recommend the use of fluoride have not raised concern.

She also believes that the risk of overexposure to fluoride through water is low in Nigeria, considering the significant challenge of many communities lacking access to potable water.

She explained that decay is demineralisation of the tooth structure which breaks it down and leads to cavities.

“We are still encouraging parents to use toothpaste with fluoride. Although there are so many other studies, some countries have stopped using fluoride in their toothpaste. They are saying you cannot force them to use fluoride,” she said.

“But generally, the American Dental Association, American Academy of Pediatric Dentistry, American Academy of Pediatrics, even the Nigerian Association of Pediatric Dentistry, and European Academy of Esthetic Dentistry have all agreed that children should use fluoridated toothpaste.”

She further explained that food items such as tea, fish, oatmeal, and some vegetables contain fluoride.

She said some studies show that in areas where there is a high concentration of fluoride in water, it confers some protection against decay.

She noted that areas such as the middle belt and the northeast have a high concentration of fluoride in water from wells to lakes, and streams.

Currently, the recommended fluoride level in Nigeria for drinking water is 1.5 mg per litre, according to the Nigerian Standards for Drinking Water Quality.