Bottled water not affecting tooth decay

By Joe Grossman
UPI Science News
From the Science & Technology Desk

May 30, 2002

Some dentists are concerned that people who drink mostly bottled water and little tap water may not be getting enough fluoride for good dental health, but several authorities told United Press International they are not worried and published literature shows little cause for alarm.

John W. Stamm, who speaks for the American Dental Association on fluoride issues, acknowledged some dentists are concerned. However, relatively few people get their entire fluid supply from bottled water.

"It's very important to realize that there are many sources for body fluids," Stamm told UPI. "The fact that one may be consuming variable amounts of bottled water seems to me to be insufficient reason to be concerned about a fluoride deficient diet."

Stamm is also dean of the School of Dentistry at the University of North Carolina at Chapel Hill.

"There's no such thing as a fluoride-free diet," Stamm added.

When fluoride binds to other minerals in tooth enamel it tends to prevent demineralization and promotes remineralization of the enamel. Fluoride also inhibits the growth of bacteria that cause cavities.

An official statement of the American Dental Association says, "There are no scientific studies to indicate an increase in the tooth decay rate because more people are drinking bottled water. Nonetheless, the ADA wants people to be aware that if they drink bottled water as their primary source of water they could be missing the decay preventive effects of optimally fluoridated water available from their community water source."

The Centers for Disease Control and Prevention in Atlanta reports most bottled water in the U.S. contains less than 0.3 milligrams of fluoride per liter, about 0.3 parts per million. That is only half to one-fourth of what most supporters of fluoridated water consider optimal.

Cor van Loveren, a researcher at the Academic Center of Dentistry in Amsterdam, the Netherlands, told UPI, "We rely on the use of fluoride toothpaste. As far as I know, in those countries with fluoridated water, people also use fluoride toothpaste. Then caries (cavity) prevention will not suffer from the change from tap water to bottled water. In fact, in some countries water fluoridation has been stopped without an increase in caries prevalence."

About 65 percent of Americans live in areas with fluoridated water. In most of those areas, fluoride is added to the water -- it is not naturally occurring.

Many groups in the United States have formed to protest municipal fluoridation of public water supplies. Their central argument is public water should not contain any substance intended to have a medical use.

There also is concern fluoride levels in foods are more than adequate and in some cases relatively high, in part due to the widespread use of fluoride-containing pesticides.

Howard Pollick, vice-chair of the California Fluoridation Task Force, told UPI there were no adequate studies comparing the amount of fluoride a person receives from eating a regular diet and consuming only bottled water, versus eating a regular diet and consuming only tap water. Pollick is a clinical professor in the department of preventive and restorative dental sciences at the University of California at San Francisco.

Many foods contain fluoride if they are manufactured in areas where water has been fluoridated. The National Academy of Sciences report, "Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride," released in 1999, cites something called the "halo" or diffusion effect, in which foods manufactured in areas with fluoridated water are transported throughout the country for sale and consumption.

"Both the inter-community transport of foods and beverages and the use of fluoridated dental products have blurred the historical difference in the prevalence of dental (cavities) between communities with and without water fluoridation," the report states.

The NAS report estimates foods generally have between 0.2 and 0.7 mg of fluoride per liter. Studies in the United States and Canada, cited in the report, show adults in areas where water contains 1 mg of fluoride per liter have daily intakes of 1.4 to 3.4 mg per day. Adults in areas with less than 0.3 mg per liter had intakes of 0.3 to 1 mg per day.

Although there is no standard for a minimum daily dietary requirement of fluoride, the American Dental Association's booklet, "Fluoridation Facts," states a dietary intake of 4 mg per day of fluoride is "adequate" for a person weighing about 160 pounds. The guideline is approximately proportional to weight. However, the "upper tolerable limit" specified by the ADA for the 160-pound person is 10 mg per day.

The recommended level of water fluoridation for those who favor the process is from 0.7 to 1.2 milligrams per liter. Fluorosis, resulting in the discoloration of teeth, begins if water concentrations rise above 1.7 mg per liter.

In spite of a ADA statement that 4 mg of dietary fluoride per day is "adequate," the cover story of the July 2000 Journal of the American Dental Association, titled "The science and practice of caries prevention," pointed out "systemically incorporated fluoride has only a minor role in protecting against dental caries." The benefits are almost all from the direct contact of the tooth with a fluoride containing substance.

Howard Bailit, with the University of Connecticut School of Medicine's department of community medicine and health care, is involved in developing school-based dental disease prevention programs.

Bailit agreed there essentially is no such thing as a fluoride-free diet, but addressed the question of whether or not using fluoridated toothpaste would be enough for someone who consumed no dietary fluoride. "It depends on the individual. For some people it would be enough. For some it's not even close," he said.

Bailit cited genetic predisposition, diet and dental hygiene habits as contributing factors to individualizing a risk assessment and designing a course of preventive measures. "People have different risks for different diseases. You can't apply the same treatment to every person because their risk does differ," Bailet told UPI.

Stephen Kay, speaking for the International Bottled Water Association in Alexandria, Va., told UPI bottled water consumption in the U.S. has a bit more than doubled since 1990. Kay noted some manufacturers are now offering fluoridated bottled water.

 

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