In fact, the CDC considers water fluoridation one of the greatest public health achievements in the 20th century. Yet controversy continues regarding the long-term health effects -- and potential risks -- of fluoride consumption.
Years of research by myriad public health agencies -- including the U.S. Food and Drug Administration, CDC, American Dental Association, World Health Organization, and National Cancer Institute -- and nonpartisan groups such as the Pew Research Center have demonstrated that fluoridation is a safe and effective way to prevent caries, especially among children and underserved populations who have limited access to dental care.
A 1991 report by the U.S. Public Health Service (PHS) regarding fluoride's benefits and risks concluded:
Extensive studies over the past 50 years have established that individuals whose drinking water is fluoridated show a reduction in dental caries. Although the comparative degree of measurable benefit has been reduced recently as other fluoride sources have become available in nonfluoride areas, the benefits of water fluoridation are still clearly evident.
More recently, the U.S. surgeon general's 2000 report on oral health in America noted that, "Community water fluoridation is safe and effective in preventing dental caries in both children and adults. Water fluoridation benefits all residents served by community water supplies regardless of their social or economic status."
That same year, the Texas Legislature commissioned a report from the state's oral health program to investigate the safety and economic viability of water fluoridation. That report also confirmed the proven health benefits gained from drinking water with optimal levels of fluoridation. In addition, experts determined a savings of $24 per child in Medicaid expenditures because of the cavities that were averted by drinking fluoridated water, the study concluded.
A study released by the Pew Research Center in February 2010 also dismissed concerns about fluoride's dangers.
"The vast majority of scientific research has not supported these claims, however, and six
decades of study have shown community water fluoridation to be a safe, efficient and effective way to prevent decay," the report concluded.
Many towns, states still resistant
Yet despite the scientific evidence supporting fluoridation's salutary effects, many groups and individuals remain strongly opposed to fluoridated water. They claim that it can lead to increased risk of bone fractures, decreased thyroid function, lowered IQ, arthritic-like conditions, dental fluorosis, and osteosarcoma. They also argue that too much fluoride is already ingested, noting that it's often naturally occurring in water supplies and is added to toothpaste, mouthwash, and many bottled beverages.
Armed with these concerns, cities and towns across the U.S. continue to fight against fluoridating their water supplies, citing issues of personal liberty as well as potential health risks. (Currently, 12 states and the District of Columbia have mandatory fluoridation laws.) The California community of Watsonville, which had fought against fluoridating its water supply for nearly a decade, finally approved it last month after state health officials threatened fines for failing to comply with a state law requiring it.
Meanwhile, voters in several Massachusetts communities have repeatedly thwarted bids to put fluoride in their water, with opponents arguing that fluoride use should be voluntary, not mandated by the government. And similar debates are taking place in other states, including Louisiana, New Jersey, Mississippi, Nevada, New York, and Alaska.
“If people don't have the money to do proper oral hygiene care, then this is a way to at least get fluoride for free.”
— Bob Macdonald, Florida Dental
While fluoridation opponents say that toothpaste and mouthwashes already provide more effective topical application of fluoride, health officials assert that water fluoridation supplies a last-ditch safety net for people who don't practice good oral hygiene. Children in underserved populations and immigrants typically have higher caries rates, studies show, and a 2001 CDC report noted that fluoride use is especially important for children during the time of anterior tooth enamel development (younger than 6 years old).
A 2002 review by the Task Force on Community Preventive Services found that water fluoridation reduces tooth decay by 30% to 50% in children and adolescents.
Similarly, a 2008 study in Advances in Dental Research (July 2008, Vol. 20:7, pp. 8-12) concluded that "fluoridation was the most cost-effective means of reducing tooth decay in children." The author noted that reductions in decay attributable to water fluoridation were almost the same as those obtained with sealants, but at a much lower cost.
Bob Macdonald, director of dental care and health for the Florida Dental Association, told DrBicuspid.com that fluoridation guarantees some protection against caries for those without access to dental care. "If people don't have the money to do proper oral hygiene care -- including brushing, flossing, and seeing a dentist twice a year -- then this is a way to at least get fluoride for free," he said.
Some 75% of the Florida's water supplies are fluoridated, one of the highest rates in the U.S., he noted. "It's a benchmark for optimal oral healthcare," he said.
And a number of studies have shown that fluoridation saves money both for people and public health programs.
Colorado's fluoridation program was associated with an annual saving of $148.9 million in 2003, or an average of approximately $61 per person, according to a study by the New York Department of Health (Public Health Reports, September/October 2010, Vol. 125:5, pp. 647-654). Similar results have also been observed in New Zealand. The impact of fluoridation on the cost of publicly financed treatment programs has also been reported in Texas and Louisiana, the study found.
The cost of a carious surface saved because of community water fluoridation ranged from $11 to $17 in 1999, according to the CDC's 2001 study.
Potential health risks?
But in an interview with DrBicuspid.com, Carol Kopf, media director for the Fluoride Action Network (FAN), called fluoride a "waste product of phosphate fertilizer" and contended that there is no benefit to fluoridating water supplies. "It exposes the entire population to fluoride's adverse effect without any benefits," she said.
For example, Kopf noted, the National Kidney Foundation (NKF) changed its supportive stance of fluoride in 2008, recommending that patients with chronic kidney disease should monitor their intake of the mineral. In addition, she maintains that there is already excessive fluoride ingestion.
Fluorosis is a legitimate -- but not life-threatening -- concern. In 2006, the ADA issued an interim guide advising parents not to reconstitute infant formula with fluoridated water because of the risk of causing enamel fluorosis -- a position reiterated last year in a systematic review in the Journal of the American Dental Association (July 2009, Vol. 140:7, pp. 841-854).
But even in its most severe form, enamel fluorosis is considered a cosmetic effect, not an adverse functional effect, according to the CDC. Moderate and severe forms of enamel fluorosis occurred even among children living in areas with low fluoride concentrations in the drinking water, the CDC claims.
But, according to Kopf, studies by the CDC and other health organizations that extol fluoride's benefits in caries prevention are biased, the result of "cherry-picking information that appears to show fluoride reduces tooth decay."
"I think they're [the CDC and other groups] hired to promote fluoridation," she said. "I don't think they're making objective opinions."
Kopf thinks topically applied fluoride may have some use, but said even that presents a danger. "It's bad for the gums because it gets into the bloodstream, and scientific literature shows fluoride even in small doses can be harmful to the thyroid gland, especially for people low in iodine," she said.
But overall, she firmly believes that excessive exposure to fluoride can cause problems. "Too much is a bad thing," said Kopf, who notes that she has a bachelor's degree in biology and a master's in science.
“The benefits are minimal at best, and the risks are significant.”
— J. William Hirzy, Ph.D., former EPA
She is not alone in her concerns. Bill Osmunson, D.D.S., M.P.H., a general practitioner with offices in Lake Oswego, OR, and Bellevue, WA, told DrBicuspid.com that he promoted water fluoridation for 25 years. But he now says that it is highly toxic, causes serious dental and medical problems, and is unethical and illegal.
"It's no longer effective in reducing dental decay because we're getting huge amounts of fluoride from many different sources," he explained. "And when you get too much, you see an increase in dental problems, including enamel fluorosis, fractured teeth, and fluoride bombs."
Dr. Osmunson listed many conditions that he says are aggravated by fluoride ingestion: rheumatoid and osteoarthritic-like pain, bone cancer, bone fracture, thyroid reduction, kidney damage, reproductive problems, lower IQ, increased mental retardation, allergy problems, and gastrointestinal disorders.
While a 1990 study by the National Toxicology Program (NTP), part of the National Institute of Environmental Health Sciences, showed an increased number of osteosarcomas in male rats given water high in fluoride for two years, other studies in humans and animals have not shown an association between fluoridated water and cancer.
For example, in 1993, the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council (NRC), part of the National Academy of Sciences, conducted an extensive literature review concerning the association between fluoridated drinking water and increased cancer risk (Health Effects of Ingested Fluoride, Washington, DC: National Academy Press, 1993). The review included data from more than 50 human epidemiological studies and six animal studies. The group concluded that none of the data demonstrated an association between fluoridated drinking water and cancer.
FAN activist Kopf pointed out that the NTP study found "equivocal evidence" linking fluoride and cancer in rats, but the researchers determined the connection was "not conclusive." They concluded that osteosarcomas of bone were observed in one of 50 male rats who were given fluoride in megadoses of 100 parts per million (ppm) while none were seen in the control or 25 ppm dose groups. There was no evidence of carcinogenic activity of fluoride in male or female mice receiving fluoride at concentrations of 25, 100, or 175 ppm in drinking water for two years, the researchers found.
Dr. Osmunson concluded that fluoridating water supplies should be stopped. "It's a crime because it's illegal and causes people to die," he said.
He pointed to criticism by former EPA chemists J. William Hirzy, Ph.D., and William Marcus, Ph.D., as evidence that some scientists have expressed concerns about fluoride's health effects.
Hirzy, a former senior vice president for the EPA Headquarters Union, called fluoridation "an unreasonable risk" during testimony before a U.S. Senate subcommittee in 2000. "The toxicity of fluoride is so great and the purported benefits associated with it are so small -- if there are any at all -- that requiring every man, woman, and child in America to ingest it borders on criminal behavior on the part of governments," he stated.
"The benefits are minimal at best, and the risks are significant," Hirzy, now a resident chemist at the American University's College of Arts and Sciences in Washington, DC, told DrBicuspid.com. He believes fluoride has adverse effects on bones, the brain, teeth, and the thyroid.
Marcus, who is now retired, also dismissed fluoride's salutary effects. "It has no benefits that will help the human body," he told DrBicuspid.com. "It's a hell of a good rat poison, and it's approved for that. It's fantastic for chemical processes."
Both Hirzy and Marcus cited a 2006 report by the Committee on Fluoride in Drinking Water, convened by the NRC. "After reviewing research on various health effects from exposure to fluoride, including studies conducted in the last 10 years, this report concludes that EPA's drinking water standard for fluoride does not protect against adverse health effects," the report stated.
In 1986, the EPA established a maximum allowable concentration for fluoride in drinking water of 4 milligrams per liter (mg/L), a guideline designed to prevent the public from being exposed to harmful levels of fluoride, according to the NRC report. Just over 200,000 Americans live in communities where fluoride levels in drinking water are 4 mg/L or higher. Children in those communities are at risk of developing severe tooth enamel fluorosis, the report stated. The report also concluded that people who drink water containing 4 mg/L or more of fluoride over a lifetime are likely to have an increased risk for bone fractures.
Benefits outweigh risks
At least one U.S. regulatory agency does acknowledge that too much fluoride can have potential negative side-effects. The FDA requires warnings on toothpaste cautioning parents about using it for children younger than 6 years of age, advising them to contact a poison control center if young children accidentally swallow more than the amount used for brushing.
Recommended fluoride level
The optimal fluoride level recommended by the U.S. Public Health Service is 0.7 to 1.2 parts per million (ppm) for the prevention of tooth decay.
But Kathryn Meier, PharmD, a toxicology specialist with the California Poison Control System and a clinical professor of pharmacy at the University of California, San Francisco School of Pharmacy, told DrBicuspid.com that it's almost impossible for children or adults to ingest a fatal amount of fluoridated toothpaste.
"When you look at toothpaste exposure where parents find a toddler with it in their mouths, rarely do they develop any poisoning symptoms," she said. Most toothpaste has about 1 mg of fluoride in each gram of toothpaste, Meier noted, and to reach the minimum dose that would cause stomach upset in a toddler would mean the child would have to ingest about 30 to 45 grams of toothpaste.
"Children often taste it but rarely eat enough to develop even mild stomach upset," Meier pointed out.
Calls from worried parents are common, she said, but noted, "What you'll notice is there are never any deaths from toothpaste."
Macdonald of the Florida Dental Association echoed her sentiment. "Show me how many people have died," he responded regarding claims of fluoride's harmful effects.
"It all comes down to dose," Meier said. "You'd need to ingest over 500 grams or 16 ounces of 1% fluoride toothpaste for it to be fatal. You can die from too much of anything, including water."
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