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News — A federal judge’s order that the U.S. Environmental Protection Agency take action regarding the level of fluoride allowed in public water supplies is the latest news to create confusion about the safety of fluoridated water. Experts, including those at (TUSDM), say rigorous scientific investigation has shown no risk from the current regulations. 

“[The current level] has been found in multiple studies to be safe,” said , Delta Dental of Massachusetts Professor of Public Health and Community Service at TUSDM, and chair of the school’s Department of Public Health and Community Service. The data examined by the court, Zavras said, looked at fluoride levels several times higher than those authorized by the EPA. 

The September 24 ruling was in response to a lawsuit brought by anti-fluoridation advocates and hinged on a recent report from the U.S. Department of Health and Human Services (HHS) that said high levels of fluoride in drinking water were associated with lower I.Q. in children. 

“The secret to understanding the court’s decision is the quality of the evidence and the reliance of the plaintiffs on regulatory technicalities,” Zavras said, adding that the fluoride levels examined in the HHS report were from geographic locations with excessive naturally occurring fluoride. Other studies cited in the lawsuit, Zavras said, were misleading, “allowing miscalculations of risk.” 

Current federal standards set the limit for fluoride in community water supplies at 0.7 milligrams per liter (0.7mg/L). The level at which fluoride consumption is considered unsafe is 4 mg/L, about six times higher than the recommended amount.

“The ruling forces the EPA to look at the issue,” Zavras said. It does not mandate the EPA set new fluoride levels, or order an end to fluoridation, he added. The , the American Academy of Pediatric Dentistry, and the continue to support use of fluoride at the present levels. 

Fluoride has been added to many—but not all—community water supplies in the U.S. for more than 70 years as a public health measure to curb rates of cavities, particularly in children. The practice has been considered a notable public health success story; today, it’s estimated that fluoridated water reduces cavity risk for both children and adults by 25%, even after accounting for the benefit of toothpastes and mouth rinses.

One step in the process of developing cavities is “demineralization,” in which teeth are robbed of the minerals they need to remain strong, and become vulnerable to decay. Prolonged demineralization causes enamel, the hard white outer covering of the tooth, to break down. Fluoride is incorporated into teeth threatened by demineralization, in effect repairing them and keeping cavities at bay.

“Many generations, hundreds of millions of people, have grown up drinking fluoridated water, and there is no evidence that today’s generation has lower I.Q. levels than generations in the past that didn’t have fluoride,” Zavras said. “At the same time, there’s no evidence that I.Q. levels are lower in the U.S. and Canada than in corresponding countries that don’t have fluoride.”

Significantly elevated levels of fluoride in drinking water—most often found in areas with naturally occurring high fluoride levels in soil—do pose documented risks. These include dental fluorosis, which results in discolored or pitted teeth, or skeletal fluorosis, a rare condition with symptoms that include joint pain and stiffness.

“Here is where I must introduce the concept of moderation,” Zavras said. “It’s not unique to fluoride. Consuming too many vitamins in large amounts is toxic. The point here is using the right amount.”