WASHINGTON U.S. government officials lowered recommended limits for fluoride in water on Friday, saying some children may be getting tooth damage from too much.
Fluoride is added to the water supply in most U.S. communities because it can prevent and repair tooth decay. But health and environment officials said Americans get fluoride in so many sources now, such as toothpaste and mouth rinses, that it makes sense to lower levels.
The Health and Human Services Department lowered its recommended levels to 0.7 milligrams of fluoride per liter of water -- the lower limit of the current recommended range of 0.7 to 1.2 milligrams.
The Environmental Protection Agency said it would review its rules on how high fluoride levels may go. Currently they may go as high as 4 milligrams of fluoride per liter.
Communities add fluoride to water on a voluntary basis. Doctors and dentists recommend it because it can help protect children's teeth that have not yet broken through the gums.
"There are several reasons for this change, including that Americans have access to more sources of fluoride than they did when water fluoridation was first introduced in the United States," the U.S. Centers for Disease Control and Prevention said in a statement.
The EPA did a risk-assessment study on whether some children may now get too much fluoride.
The study concluded that some children under the age of 8 may be overexposed to fluoride at least occasionally because of their high fluid intake compared to their body weight or because of high natural levels of fluoride in their local drinking water.
Too much fluoride can cause a change in the enamel on teeth called dental fluorosis. More than 90 percent of U.S. cases appear as white spots on the tooth but in very severe cases it can pit the enamel.
"Excessive consumption of fluoride over a lifetime may increase the likelihood of bone fractures and may result in effects on bone leading to pain and tenderness, a condition called skeletal fluorosis," the CDC said. "Severe skeletal fluorosis is a rare condition in the United States."
Water in the United States has been fluoridated since 1945 and the CDC says 196 million Americans get "optimally fluoridated community water." Experts estimate it cuts the rate of cavities by 40 percent to 60 percent.
The CDC estimates every $1 invested in fluoridating public water supplies saves $38 in dental treatment costs.
(Reporting by Maggie Fox; Editing by Bill Trott)