A federal report this week linked high levels of fluoride in other countries to lower IQs in children, adding new evidence in the long-simmering debate over adding fluoride to public drinking water systems.
The report from the U.S. Department of Health and Human Services’ National Toxicity Program concluded with “moderate confidence” that a collection of non-U.S. studies associated higher levels of fluoride with lower IQ in children. The report evaluated a collection of previous studies completed on populations in Canada, China, India, Iran, Pakistan and Mexico.
The review examined total fluoride exposure from all sources, so it did not solely measure health effects of drinking fluoridated water. But experts say it will likely generate debate among anti-fluoride groups who are pushing for ballot measures and other actions to ban public water fluoridation in local communities.
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The Centers for Disease Control and Prevention named public water fluoridation as one of the top 10 public health achievements of the 20th Century. The practice of adding small amounts of fluoride to public drinking water to strengthen teeth is endorsed by the American Dental Association and the American Academy of Pediatrics. The organizations point to research that found fluoridated water reduces tooth decay by 25% in children and adults.
“Decades of research and practical experience indicate that fluoride is safe and beneficial to oral health,” said Linda Edgar, president of the American Dental Association.
How much fluoride is safe?
Drinking water with more than 1.5 milligrams of fluoride per liter was “consistently associated with lower IQ in children,” the report said. It did not say how much IQ might be lowered in children who drink water with fluoride levels that exceed that amount. The report also did not say whether adults could be affected by high levels of fluoride.
The U.S. Public Health Service recommends public water systems contain a fluoride level of .7 milligrams per liter of water. The World Health Organization’s recommended limit for fluoride in drinking water in 1.5 milligrams per liter.
What do the experts say?
ADA representatives said the vast majority of Americans should not be alarmed by the report. Federal public health agencies recommend public water systems be calibrated to less than half the fluoride levels which this research links to lower IQ in children.
“For the average person, there is no concern based upon the findings from this review,” said Howard Pollick, a professor at the University of California, San Francisco.
But Pollick, a fluoride expert with the ADA, said he is concerned about a small percentage of Americans who live in communities served by water systems that contain too much fluoride.
As of 2020, about 1.9 million Americans received drinking water from a community water system with fluoride levels of at least 1.5 milligrams per liter, according to the Centers for Disease Control and Prevention. By that measure, the report suggest children in those communities might be at risk.
The Environmental Protection Agency recommends families with young children don’t drink water from community systems with fluoride levels that exceed 2 milligrams per liter. The EPA standard is meant to protect kids from severe dental fluorosis, which can weaken or discolor teeth. Water providers are required to notify people in communities where fluoride levels exceed the threshold.
“The question now is whether (the EPA’s threshold) should perhaps be lowered to 1.5,” Pollick said.
Could this spur more communities to ditch fluoridated water?
Groups that have long been critical of potential developmental and cognitive effects of public water fluoridation cheered the report.
David Kennedy, a retired dentist and treasurer of the Preventative Dental Health Association, said the report shows too much fluoride can be harmful to children’s development.
“It does not belong in our food, our water or our toothpaste,” Kennedy said.
Fluoride Action Network, which seeks to end water fluoridation, said the number of Americans served by community water systems with fluoridated water dropped from 74.6% in 2012 to 72.7% in 2020. More than 1,400 communities stopped adding fluoridation chemicals to their water systems from 2010 through 2020, the network said.
Pollick said he is worried city councils and other local elected leaders might face pressure from constituents. He noted the report does not prove fluoride causes lower IQ levels, and he noted the report authors had “moderate confidence” in the evidence.
“Whenever there’s a report that comes out like this, we understand that people may get concerned,” Pollick said.
