The current maximum level of fluoride that EPA allows in U.S. drinking water—4 mg/L or 4 ppm—harms teeth and bones, says a report from the National Research Council released on March 22. About 200,000 people in the U.S. consume water with naturally occurring fluoride levels of 4 mg/L or higher.

On average, about 10% of children exposed to the maximum contaminant level develop severe dental fluorosis, a permanent condition characterized by discoloration and pitting of the teeth, explains John Doull, professor emeritus of pharmacology and toxicology at the University of Kansas Medical Center and chair of the committee that wrote the report. Children who drink water that meets EPA’s secondary standard of 2 mg/L are at risk of a less severe form of dental fluorosis, involving only discoloration of the teeth, he says.

In addition, “a population with lifetime exposure to fluoride in water at concentrations of 4 mg/L or higher is likely to experience more bone fractures than groups exposed to 1 mg/L,” Doull says. “Our committee unanimously concluded that EPA should lower the maximum contaminant level goal for fluoride in drinking water.”

The report discusses a number of other adverse health effects that may be associated with excessive fluoride exposure but comes to no definitive conclusions. For example, it says that lifetime exposure to fluoride at 4 mg/L can lead to bone fluoride levels associated with the most severe stages of skeletal fluorosis, a painful disease that resembles arthritis. The report also describes studies that find IQ deficits in children in high-fluoride areas. More research is needed, however, to determine if fluoride is indeed causing skeletal fluorosis or lower intelligence, the report says.

The NRC committee did not specifically examine the health risks or possible benefits of water artificially fluoridated at 0.7 to 1.2 mg/L and consumed by more than 160 million Americans.

EPA should use the information in the report to do a new risk assessment and set new fluoride standards, says committee member Charles Poole, associate professor of epidemiology at the University of North Carolina’s School of Public Health.

Also on March 22, the Environmental Working Group released a study on infants’ exposure to fluoride. In 1997, the Institute of Medicine set a safe upper limit of 0.7 mg of fluoride per day for children under six months of age. EWG found that in 25 of the 28 largest cities in the U.S., at least 15% of formula-fed infants are exposed to excessive levels of fluoride, mostly from tap water used to make infant formula. For example, 61% of the formula-fed babies in Boston ingest too much fluoride. “Communities should move to reduce the fluoride concentration in drinking water to a level that will protect infants,” says EWG Senior Vice President Richard Wiles.

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