Is It Time to Rethink Fluoride in Drinking Water?

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Key Takeaways

• For the first time, an extensive government report acknowledged that high levels of fluoride exposure may harm neurological development and cognitive health in kids.

• It concluded with “moderate confidence” that fluoride exposure at twice the level recommended in drinking water is associated with lower IQ in children.

• The report has stirred debate, with some experts urging a reevaluation of water fluoridation policies, while dental health organizations continue to support its benefits for tooth decay prevention.

For more than 75 years, water systems in the U.S. have added fluoride to reduce tooth decay that comes with the wear and tear of daily use. The Centers for Disease Control and Prevention (CDC) considers community water fluoridation to be “one of the 10 great public health achievements of the 20th century.”

However, in late August, the government published a report acknowledging for the first time that high levels of fluoride exposure may harm kids’ neurological development and cognitive health.

In a 324-page report that took nearly a decade to finalize, the National Institutes of Health’s National Toxicology Program (NTP) concluded with “moderate confidence” that high levels of fluoride exposure are associated with lower IQ in children.

Importantly, the report doesn’t evaluate the effect of fluoride in drinking water alone. Researchers reviewed over 500 study results, mostly focusing on fluoride levels above 1.5 parts per million—double the concentration recommended for U.S. drinking water. Less than 1% of people drink water with levels of fluoride that high.

The report has stirred controversy. Dental health organizations question the report’s methods and say the findings could be misinterpreted to stoke fears about fluoride exposure. Meanwhile, some toxicology experts say the evidence is strong enough that regulators should rethink fluoridation guidelines, which haven't been updated in decades.

“It’s so important to get this right. At a minimum, we’ve got to pause and say, ‘We’re taking this science seriously because our job is to protect the public.’ It’s not to protect our reputation. It’s not to put our heads in the sand and say we’ve always known fluoride is safe,” said Bruce Lanphear, MD, MPH, a professor of health sciences at Simon Fraser University in British Columbia. “If we address it urgently, we have a chance of reducing harm if it is, in fact, a toxic chemical. And we have a chance of not losing any more trust in public health.”

Related: Why Is There Fluoride in Toothpaste?

Why Is Fluoride Added to Water Supply?

Fluorides are compounds that contain both fluorine and another element, like a metal. They occur naturally in the environment and in some foods, like tea and shellfish. Nearly all water contains fluoride, though the amount present depends on the source.

In the early 1900s, scientists noticed that some communities of people in Colorado had permanent brown and white splotches on their teeth. They discovered that high levels of fluoride in drinking water were to blame for those stains, called fluorosis. As it turned out, the people with fluoride-stained teeth were also surprisingly resistant to tooth decay.

Public water systems across the country have since adjusted the naturally occurring fluoride levels in drinking water to the concentration believed to prevent tooth decay without causing fluorosis.

Some studies indicate that fluoride protects teeth through topical application rather than through systemic exposure. In other words, scrubbing your teeth with fluoridated toothpaste is one of the most effective ways to prevent tooth decay. When you drink fortified water, the fluoride you drink is secreted in the saliva in your mouth, where some of it lands on your teeth to protect them.

Drinking water may not be the most efficient way to get the protective effects of fluoride. Still, the American Dental Association has “unreservedly” advocated for community water fluoridation since 1950. The organization says that fluoridating water helps improve dental health in communities without access to routine dental care and is “the most significant strategy employed to reduce disparities in tooth decay.”

“Today, even with widespread availability of fluoride toothpaste, studies show community water fluoridation continues to be effective in reducing tooth decay by about 25% in children and adults,” the American Dental Association said in an email.

What Does the New Report Say?

In 2006, the National Research Council evaluated the fluoride standards set by the Environmental Protection Agency and found a link between consuming high levels of fluoride and adverse brain effects. In the following years, researchers probed that link further.

In 2016, the NTP published a systematic review of the data on fluoride exposure’s impact on learning and memory in animal studies. The review found low to moderate evidence of a connection.

This latest report incorporated data from human studies. The authors said that not enough high-quality studies have yet been conducted in adults to draw conclusions about the cognitive effects of fluoride exposure in adults.

More studies are available for children. Eight out of nine high-quality studies found that fluoride exposure negatively affected neurodevelopmental or cognitive outcomes in children. The working group also considered 72 studies that analyzed how fluoride exposure related to children’s IQs. Of the 19 studies that were deemed to be high quality, 18 found that higher fluoride exposure led to a decrease in IQ.

Importantly, the report doesn’t question the dental health benefits of fluoride exposure, nor does it explain the possible reasons why high levels of the mineral may be neurotoxic.

It also doesn’t provide information about the number of IQ points that are lost by the increase in fluoridation exposure—only that the difference is significant.

Is Fluoride Really Neurotoxic?

Philippe Grandjean, MD, DMSc, a professor of environmental medicine at the University of Southern Denmark, authored several of the studies that the NTP used in its report, including a 2012 meta-analysis that was one of the first to garner U.S. attention on the neurotoxicity of fluoride.

“[The NTP report] has been reviewed more than any other public document I know of, and the science is top class. However, the problem is that the conclusions are very weak,” Grandjean said.

He said that if fluoride was added to water through industry, rather than for public health, the agency might have been more inclined to issue a strong warning against exposure to the mineral.

“With lead, mercury, and dioxin, the evidence is just as compelling as in regard to fluoride, but these conclusions are soft. And that is surprising, because, as a researcher, I would say, ‘My God, this is compelling evidence,’” Grandjean said.

He said that recent research indicates that the loss of an IQ point in children starts to happen at exposures as low as 0.3 milligrams per liter, far below the 1.5-milligram-per-liter threshold the NTP used in its report.

Lanphear said scientists aren’t exactly sure why fluoride is neurotoxic, but evidence from animal studies suggests it has to do with the way the mineral messes with thyroid hormones. Two human studies, including one that Lanphear is involved with, show that women who ingested higher levels of fluoride in their water were at an increased risk of developing hypothyroidism.

Thyroid hormones are important for the normal development of the brain, which suggests developing fetuses and young children are especially vulnerable to the adverse effects of high fluoride exposure.

Lanphear said that the choice to add a compound like fluoride to water should require “extraordinary evidence” that doing so is safe and effective.

“When you have the lead industry poisoning people and misrepresenting the data, we’ve come to expect that. We should not expect that, or accept it, from public health agencies. This report demands the public health agencies and the dental organizations to pause and say, ‘it’s time for us to revisit this,’” Lanphear said.

After the report was published, leading public health organizations, including the American Pediatric Association and the American Dental Health Association, published statements affirming their support for water fluoridation.

“Decades of research and practical experience indicate that fluoride is safe and beneficial to oral health,” Linda Edgar, DDS, president of the American Dental Association, said in a statement.

The American Academy of Pediatrics highlighted some limitations of the study. For one, the organization pointed out that IQ can be a flawed unit of measurement for cognitive abilities, which often fails to account for socioeconomic, physical, familial, cultural, genetic, and other factors.

IQ has long been used as a measurement to understand the neurological effects of environmental toxins, including lead and arsenic.

Related: CDC Strengthens Lead Poisoning Prevention in Children With New Standards

Can You Limit Fluoride Exposure But Still Protect Your Teeth?

Without fluoride, you’re at higher risk for tooth decay, which can lead to other, more systemic problems. But if you’re concerned about getting too much fluoride, there are some steps you can take.

You can check your water intake using the CDC’s “My Water’s Fluoride” page. If you live in a place with fluoride levels near 1.5 milligrams per liter, you may consider using a water filter to remove some of the fluoride.

To avoid overexposure to fluoride, children younger than 3 years old should use a rice-sized dab of toothpaste, and children 3 to 6 years old should use a pea-sized amount, according to the CDC. Young children should also be encouraged not to swallow it.

Lanphear said the U.S. public should weigh the costs and benefits of fluoride exposure, such as the risk of one’s child losing a couple of IQ points to prevent some level of tooth decay. Besides, there may be other, more beneficial steps the government could take to protect Americans’ teeth, he added.

“Why are we focused so single-mindedly on policies on water fluoridation? Why aren’t we providing free dental care for children? Why aren’t we targeting sugar consumption? Why aren’t we regulating the marketing of sugary beverages and cereals to children?” Lanphear said. “We need to think about what’s in the best interest of children of pregnant women.”

What This Means For You

Fluoridated water has been used for decades to reduce tooth decay, but a new report suggests that high levels of fluoride exposure might impact children's cognitive development. Although most U.S. water contains fluoride at safe levels, it's important to monitor exposure, especially for children. If you're concerned, check your local water supply's fluoride levels and consider using a filter.

Read the original article on Verywell Health.