Water fluoridation is widely recognized as one of the great public health achievements of the 20th century, as it significantly reduced tooth decay. However, there is growing debate among scientists that fluoride may be linked to lower IQ scores in children.
A comprehensive federal analysis of past study scores published this week in JAMA Pediatrics added to these concerns. It found a significant inverse correlation between children's exposure levels and cognitive function.
Researchers working at the National Institute of Environmental Health Sciences concluded that higher exposure to fluoride is associated with lower IQ scores.
None of the studies included in the analysis were conducted in the United States, where recommended levels of fluoridation in drinking water are very low. At this amount, the evidence was too limited to draw definitive conclusions.
Observational studies cannot prove cause and effect. But in countries with higher levels of fluoridation, the analysis also found evidence of what scientists call a dose-response relationship, with IQ scores declining in tandem with increased exposure to fluoride.
Children are exposed to fluoride through a variety of sources other than drinking water, including toothpaste, dental treatments, mouthwash, tea, coffee, and certain foods such as shrimp and raisins. Some chemicals and industrial emissions also contain fluoride.
The analysis found that for every millionth increase in fluoride in a urine sample, which reflects total exposure from water and other sources, a child's IQ points decreased by 1.63.
Kyla Taylor, an epidemiologist at the institute and lead author of the report, said: “There is concern that pregnant women and children are ingesting fluoride through a variety of routes, and that total fluoride exposure “There are so many that it can affect fetuses, infants and children.” Neurodevelopment. ”
Dr Taylor said this analysis aimed to contribute to the understanding of the safe and effective use of fluoride. But she said it did not mention benefits and was not intended to assess the “broad public health impacts of water fluoridation in the United States.”
Several scientists, including many dentists, criticized the report, citing methodological flaws and stressing that the study had no impact on U.S. drinking water.
Because this subject is so divisive, JAMA Pediatrics commissioned two editorials with opposing viewpoints to run alongside the report.
In one article, Dr. Stephen M. 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 cautioned against concluding that any changes should be made to U.S. fluoridation policy.
“A lay reader or policy maker in some small community water utility might look at the evidence and think that's a concern no matter how you analyze it,” Dr. Levy said in an interview. spoke. “It's not as clear-cut as they're trying to be.”
In some ways, the report's findings echo statements made by President-elect Donald J. Trump's pick for Secretary of Health and Human Services, Robert F. Kennedy Jr. He questions the safety of fluoride and said one of the Trump administration's first actions will be to recommend that water systems remove fluoride.
Fluoridation has been frequently criticized since it began in many American communities in the 1950s. However, it was initially ignored because opposition was strongest among people with extremist and fringe views and right-wing groups such as the John Birch Society, which called fluoridation a communist conspiracy. .
That is changing. Last September, U.S. District Judge Edward Chen in San Francisco ordered the Environmental Protection Agency to issue a lawsuit against the Environmental Protection Agency, citing research suggesting that high concentrations of fluoride may pose a risk to children's intellectual development. Ordered stricter regulations on fluoride in water.
In a second editorial published alongside the new study, public health expert Dr. Bruce P. Lanphear notes that in 1944 the editors of the Journal of the American Dental Association expressed concerns about the addition of fluoride. , which he called: “highly toxic substances” into drinking water. He writes, “The potential for harm far outweighs the potential for good.”
Some studies suggest that improved dental health is not due to the addition of fluoride to the water, but rather to fluoridated toothpaste and better dental hygiene habits. (In some countries, fluoride is added to salt.)
According to this claim, applying fluoride topically to the teeth is enough to prevent cavities and there is no need to ingest it.
However, other studies have reported that tooth decay increased after public water fluoridation efforts were halted in some countries.
Currently, the recommended fluoride level in the United States is 0.7 ppm, and this study found that, based solely on fluoride levels in water, there was a statistically significant inverse relationship between fluoride levels and IQ scores below 1.5 ppm. No correlation was found. However, approximately 3 million Americans still drink water with fluoride levels above 1.5 ppm from wells and some community water systems.
Linda Birnbaum, former director of the National Institute of Environmental Health Sciences, called for more research into the potential effects of fluoride levels below 1.5 ppm.
However, she stressed that research does show that certain amounts of fluoride can damage the developing brain. “The answer is obvious: yes,” Dr. Birnbaum says.
To protect especially vulnerable fetuses and infants, she urges parents to avoid drinking fluoridated water during pregnancy and to use fluoride-free bottled water when making infant formula. I advised.
“My recommendation is that pregnant women and infants should not be exposed to excess fluoride,” said Dr. Birnbaum, who is not an author of the new analysis.
Very little fluoride is transferred through breast milk, so breastfeeding women don't need to worry, she added.
“The more we study many chemicals, especially those that affect IQ, like lead, the more we find that there really is no safe level,” Dr. Birnbaum said.
Some 74 studies from 10 countries were examined, including China, Mexico, Canada, India and Denmark. Dr. Lanphear pointed out that a consistent association between fluoride and IQ was found in very different populations.
He asked the U.S. Public Health Service to form a committee to seriously consider both issues, which would likely not include researchers who have studied the topic in the past and who could take a new look at the topic. I asked. Whether fluoride is neurotoxic and whether it is as beneficial to oral health as it is believed.
“If that doesn't happen quickly, I'm concerned, and rightly so, that there will be a growing distrust of public health institutions among the public,” he said.
