Fluoride in drinking water — credited with dramatically cutting cavities and tooth decay — may now be too much of a good thing. Getting too much of it causes spots on some kids’ teeth.
That led the federal government Friday to lower its recommended level of fluoride in the municipal water systems.
The U.S. Department of Health and Human Services on Friday announced a proposed reduction in the recommended fluoride level to 0.7 milligrams per liter of water in communities that add it — the first such change in nearly 50 years.
In 1945, Grand Rapids was the first city in the world to flouridate its water supply, and even has a downtown sculpture commemorating that event. Today, most public drinking water is fluoridated, especially in larger cities. An estimated 64 percent of Americans drink fluoridated water.
The standard since 1962 has been a range of 0.7 to 1.2 milligrams per liter. The Environmental Protection Agency also will review whether the maximum cutoff of 4 milligrams per liter is too high.
The proposal to recalibrate the ratio of fluoride to drinking water to the lower end of the current recommended range is based on an increase in dental fluorosis over the last 20 years, said Dr. William G. Kohn, director of the division of oral health at the Centers for Disease Control and Prevention.
The American Dental Association says the proper amount of fluoride helps prevent and control tooth decay, and that some exposure to infants’ developing teeth also plays a long-term role in prevention.
But fluoride intake above the recommended level for a child’s age creates a risk for enamel fluorosis. In most cases, fluorosis appears as barely noticeable white lines or streaks on tooth enamel and does not affect the function of the teeth.
If it’s severe enough, it can cause mottling, a brown-yellow blotchiness on the teeth. It is not reversible, but there are treatments that can improve appearance.
Fluoride has always been a controversial additive, and some have long advocated that fluoride be completely removed from municipal water supplies. But dentists, including the Michigan Academy of Pediatric Dentistry, usually support its addition to water supplies.
Grandville dentist Josh Smith said he and his partner see “a fair amount” of flourosis in their dental patients — the faint, tell-tale white lines on teeth that indicate someone has gotten too much fluoride.
“I think (fluoride) is good for the community, but I do worry that maybe we’re getting overexposed to it,” said Smith, a dentist at Northway Family Dentistry. “There’s no doubt it’s done good things, but at some point you want to look at whether it’s too much of a good thing.”
About 2 out of 5 adolescents have tooth streaking or spottiness because of too much fluoride, a government study found recently. In some extreme cases, teeth can even be pitted by the mineral — though many cases are so mild only dentists notice it.
Fluoride is a mineral that exists naturally in water and soil. About 70 years ago, scientists discovered that people whose supplies naturally had more fluoride also had fewer cavities. Some locales have naturally occurring fluoridation levels above 1.2.
Water from Lake Michigan has a natural fluoride level that generally varies from 0.1 to 0.2 parts per million.
Fluoride is added in the treatment process in Grand Rapids to bring the level up to 1.0 parts per million. The city of Wyoming offices were closed Friday, but a 2008 water quality report indicated that fluoride levels were 1.4 parts per million. Wyoming supplies the city of Grandville and parts of Park Township, Olive, Blendon, Holland, Georgetown, Gaines and Byron townships and parts of Kentwood.
Joellen Thompson, Grand Rapids water system manager, said Friday’s announcement “may bring about some more discussions between us and the MDNRE.” The state agency regulates city water treatment processes, she said, “and if we change any of our parameters, we need their approval.”
Opponents of fluoridation have said the chemical can be toxic, and some evidence shows it might cause weak bones and other problems. Malfunctioning fluoridation systems in some cities have poisoned residents, they contend.
In March 2006 the National Academy of Sciences released a report recommending that the EPA lower its maximum standard for fluoride in drinking water to below 4 milligrams. The report warned severe fluorosis could occur at 2 milligrams. Also, a majority of the report’s authors said a lifetime of drinking water with fluoride at 4 milligrams or higher could raise the risk of broken bones.
Late last year, lawyers threatened legal action if the EPA did not lower its ceiling on fluoride. They represented the Fluoride Action Network, Beyond Pesticides, and Environmental Working Group, which still recommends tap water over bottled water.