A new study released Wednesday has shown that too much fluoride in tap water could be harmful, causing cavities rather than preventing them and leading to bone damage and possibly even lower IQ levels.
The report by the National Academy of Sciences found that people exposed to the maximum level of fluoride allowed in tap water may be at greater risk for tooth decay and bone fractures.
It urged the Environmental Protection Agency to reassess the risk posed by high fluoride levels in order to establish new guidelines but did not indicate what the limit should be.
Small amounts of fluoride in water can help prevent tooth decay, but overexposure can produce the opposite effect. Particularly at risk are children and infants, who are exposed to three to four times more fluoride than adults. The study found that in areas where fluoride levels reach the current maximum, 10 percent of children develop severe enamel fluorosis, a discoloration and weakening of tooth enamel.
Excess fluoride often enters water supplies from water run-off and industrial discharges. In many areas, such as Atlanta, the mineral must be added to water supplies to bring levels up high enough to fight tooth decay.
The study did not call into question the safety of adding fluoride to drinking water. Both the American Dental Association and the American Water Works Association rushed to issue statements Wednesday reassuring the public of the safety of low levels of fluoride added to drinking water.
The report taps into long-held concerns among citizens and environmental activists about fluoride use and, more broadly, the government’s commitment to water safety. Tim Kropp, a senior scientist at the Environmental Working Group, said the study was important for shining light on issues of chemicals in drinking water.
“This brings a lot of the questions we have to the floor,” he said. “The bottom line is that the standard the EPA has is, as they say, clearly not protective of all people, especially children.”
The National Academy of Sciences report said the Environmental Protection Agency limit of 4 milligrams per liter may be far too high, but noted that problems associated with fluoride are very minor.
In most of Georgia, the state mandates fluoride levels of 0.8 milligrams per liter, said Brad Addison, a top official of the state Department of Natural Resource’s Environmental Protection Division. Throughout Georgia, he said, most fluoride levels — measured daily — are 2 milligrams per liter or less, which is considered optimal.
The National Research Council report on which the National Academy’s statement was based said more studies are needed to establish a new maximum safe level.
The Environmental Protection Agency said it would give serious consideration to the recommendation.
“Any change in the fluoride standard will be considered after the agency has completed reviewing all the data, of which the NRC report is a signifcant addition,” EPA said.
The Environmental Working Group, a private Washington watchdog agency, said the academy’s statement “puts concerns about the safety of fluoride in tap water squarely in the mainstream of scientific thought.” It said “just one example of the potential health risks from water fluoridation” could be lower IQs.
IQ deficits, it noted, have been associated with dental fluorosis. The Environmental Working Group said the academy’s report noted that evidence is “significant enough to warrant additional research on the effects of fluoride on intelligence.”
Fluoride levels across Georgia are checked daily by local municipalities, Addison said, as required by federal and state environmental agencies. He said there are “smaller communities and private systems in the state” that do not check fluoride levels.
Wednesday’s report prompted dentists and the American Water Works Association to issue statements of their own. The American Dental Association said the new report does not call into question the safety of community water fluoridation. The ADA said it continues to endorse community water fluoridation as a vital public health measure.
The American Water Works Association noted that the fluoride levels studied by the academy were far higher than typical community water levels.
More than 160 million Americans live in communities with artificially fluoridated water, which contains between 0.7 and 1.2 milligrams of fluoride per liter. About 200,000 people in the United States are regularly exposed to water at or exceeding the maximum limit, the academy said.
“The drinking water community is committed to providing high-quality water that maximizes public health protection. … We look forward to working with the EPA and others to review the fluoride standard in light of the NRC report,” wrote Jack Hoffbuhr, executive direector for the Water Works Association.