From Medscape Medical News
January 10, 2011 — Two federal agencies have announced that they are taking new measures to reduce levels of fluoride in drinking water because Americans increasingly encounter the mineral from other sources, such as fluoridated toothpaste.
The overriding goal of the US Department of Health and Human Services (HHS) and the Environmental Protection Agency (EPA) is to reverse a slow rise in fluorosis, which leads to cracks in the enamel and discoloration of the teeth. In extreme cases, it also may adversely affect bone, increasing fracture risk.
At the same time, federal health officials affirmed the value and safety of adding fluoride to drinking water to prevent tooth decay.
"The Centers for Disease Control and Prevention...has named community water fluoridation as 1 of the 10 top public health achievements of the 20th century," said Howard Koh, MD, MPH, assistant secretary for health at HHS in a press conference January 7.
"It still remains a cost-effective method of delivering fluoride to all members of a community to prevent and control tooth decay and improve oral health."
This stance immediately drew fire from fluoridation opponents, who claim the mineral is a public health threat.
HHS proposes to lower its recommended optimal level for community water fluoridation from a range of 0.7 to 1.2 mg/L to the single figure at the lower end — 0.7 mg/L. Local municipalities that opt to fluoridate their water supplies stay within this range, with the average concentration being 0.8 mg/L, Cynthia Dougherty, director of the Office of Ground water and Drinking Water at the EPA, said at the news conference.
Meanwhile, the EPA will consider whether it should lower its current maximum allowable level of fluoride, now set at 4 mg/L. The agency is following the recommendation of the National Academies of Science, which in 2006 called for an updated assessment of the mineral's effect on teeth and bone that accounts for all sources of exposure.
Too Much Fluoride Can Damage Bones
The HHS and EPA fluoride levels serve 2 different purposes. The recommended HHS concentration refers to a fluoride level high enough to effectively reduce the incidence of tooth decay, while minimizing the rate of fluorosis. The EPA standard of 4 mg/L, which is the law, as opposed to a recommendation, is the maximum concentration of fluoride that is considered safe.
State regulations on fluoride levels must be as strict as the EPA's, although states are free to set the bar lower, and some have done so, said Jim Taft, executive director of a group called the Association of State Drinking Water Administrators, in an interview with Medscape Medical News.
HHS and EPA are revisiting the subject of fluoride concentration levels in water because sources of fluoride exposure have become more plentiful. For starters, almost all water contains naturally occurring fluoride, but US communities also began adding the mineral to their water supplies more than 60 years ago to prevent tooth decay. As a result, Americans took in fluoride not only from drinking water but also from foods and beverages prepared with fluoridated water. Since the early 1960s, fluoride also has found its way into consumer dental products such as toothpaste and mouthwash, as well as professionally applied dental varnishes and gels.
More fluoride exposure has been accompanied by higher rates of dental fluorosis. In about 92% of cases, the condition is mild, appearing as white spots on the teeth, according to HHS.
In severe but rare cases, fluorosis can leave the teeth pitted. Children aged 8 years and younger are at greatest risk for fluorosis and possible pitting because fluoride adversely affects their teeth while they are still forming.
In addition, excessive fluoride consumption during a lifetime may lead to skeletal fluorosis, which may increase the likelihood of bone pain, tenderness, and fracture, as well as disrupt endocrine and neurological processes.
By lowering the recommended optimal level of fluoride in drinking water to 0.7 mg/L, HHS hopes to compensate for increased fluoride exposure elsewhere. In addition, studies show that although tooth decay gradually declines as fluoride concentrations approach 0.7 mg/L, there is little change in tooth decay between that level and 1.2 mg/L.
The proposed recommendation will soon be published in the Federal Register. HHS will accept comments from the public for 30 days. It expects to issue a final recommendation for community water fluoridation by this spring.
Fluoridation Opponents Not Impressed
The move by HSS to lower fluoride levels in drinking water met with kudos from the American Dental Association.
"This is a superb example of a government agency fulfilling its mission to protect and enhance the health of the American people," said American Dental Association President Raymond Gist, DDS. "The recommended levels for optimal fluoridation may be reduced, but the health benefits of fluoridation remain."
Opponents of fluoridated water, in contrast, were not impressed.
"[The federal government is] trying to keep the issue focused on teeth, when the science is becoming clearer and clearer that fluoride damages other tissues," said Paul Connett, PhD, executive director of the Fluoride Action Network based in Canton, New York. His group asserts that health risks associated with low to moderate doses of fluoride include joint pain, skin rash, reduced thyroid activity, bone cancer, and even IQ deficits. A recent study published in a peer-reviewed journal of the federal National Institute of Environmental Health Sciences suggests such a link between fluoride and intelligence.
Dr. Connett, a professor emeritus of environmental chemistry at St. Lawrence University in Canton, told Medscape Medical News that the United States should stop fluoridating water and instead address the root causes of tooth decay — poverty and poor diet.
"There is no difference in dental caries between fluoridated and nonfluoridated countries, fluoridated and nonfluoridated states, and fluoridated and nonfluoridated cities," added Dr. Connett.