A US government report expected to spark debate has found that twice the recommended limit of fluoride in drinking water is linked to lower IQs in children.
The report, based on an analysis of previously published research, represents the first time a federal agency has determined, “with moderate confidence,” that there is a link between higher levels of fluoride exposure and lower IQ in children. Although the report was not designed to assess the health effects of fluoride in drinking water alone, it is a striking acknowledgement of a potential neurological risk from elevated levels of fluoride.
According to the U.S. Centers for Disease Control and Prevention (CDC), fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear. The addition of low levels of fluoride to drinking water has long been considered one of the greatest public health achievements of the past century.
“I think this (report) is crucial to our understanding” of this risk, said Ashley Malin, a researcher at the University of Florida who has studied the effect of higher fluoride levels on fetuses. She said it is the most rigorous report of its kind.
The long-awaited report released Wednesday comes from the National Toxicology Program, part of the Department of Health and Human Services. It summarizes a review of Studies conducted in Canada, China, India, Iran, Pakistan and Mexicoand concludes that consumption of water with more than 1.5 milligrams of fluoride per liter is systematically associated with lower IQ in children.
The report did not attempt to quantify exactly how many IQ points might be lost with different levels of fluoride exposure. But some of the studies reviewed in the report suggested that IQ was 2 to 5 points lower in children who had higher exposures.
Since 2015, federal health officials have recommended a fluoridation level of 0.7 milligrams per liter of water. For five decades, the upper recommended range was 1.2. The World Health Organization (WHO) has set a safe limit for fluoride in drinking water at 1.5.
According to the report, about 0.6% of the U.S. population (about 1.9 million people) consume water with natural fluoride levels of 1.5 milligrams or more.
“The findings of this report raise the question of how these people can be protected and what makes the most sense,” Malin said.
The 324-page report does not reach a conclusion about the risks of lower fluoride levels, saying more studies are needed. It also does not explain the possible consequences of high fluoride levels for adults.
The American Dental Association, an advocate of water fluoridation, had criticized earlier versions of the new analysis and Malin’s investigation. On Wednesday afternoon, a spokeswoman for the association responded by email that the organization’s experts were still reviewing the report.
Fluoride is a mineral that occurs naturally in water and soil. About 80 years ago, scientists discovered that people whose supplies had more fluoride naturally also had fewer cavities, which sparked a campaign for more Americans to use fluoride to improve their dental health.
In 1945, Grand Rapids, Michigan, became the first American city to begin adding fluoride to tap water. In 1950, federal officials approved water fluoridation to prevent tooth decay, and continued to promote it even after fluoridated toothpaste brands came on the market several years later. Although fluoride can come from a variety of sources, drinking water is the primary one for Americans, according to researchers.
The authorities reduced recommended fluoride levels in drinking water in 2015 to address a dental disease called fluorosis, which can cause staining of teeth and was becoming more common in American children.
The Environmental Protection Agency, on the other hand, has long maintained a requirement that water systems cannot have more than 4 milligrams of fluoride per liter. This standard is designed to prevent skeletal fluorosis, a disorder that potentially causes bone weakness, stiffness and pain.
But a growing body of research is pointing to a different problem, suggesting a link between higher fluoride levels and brain development. Researchers wondered about the impact on developing fetuses and very young children who might ingest water containing infant formula. Animal studies showed that fluoride could affect the neurochemical function of cells in brain regions responsible for learning, memory, executive function and behavior.
In 2006, the National Research Council, a private nonprofit organization based in Washington, DC, said limited evidence from China pointed to neurological effects in people exposed to high levels of fluoride. It called for further research into the effect of fluoride on intelligence.
After further research continued to raise questions, the National Toxicology Program began work in 2016 on a review of available studies that could provide guidance on whether further measures to limit fluoride were needed.
There were earlier drafts, but the final document has been repeatedly delayed. At one point, a committee of experts said available research did not support the conclusions of an earlier draft.
“Since fluoride is such an important issue for the public and public health officials, it was imperative that we do everything we could to get the studies right,” Rick Woychik, director of the National Toxicology Program, said in a statement.
Malin explained that It makes sense for pregnant women to reduce their fluoride intake.not only through water but also in types of tea. It might also make sense to discuss requiring fluoride content on beverage labels.
