A debate many thought was quashed years ago is being resurrected among scientists and causing unease among parents: Does fluoride in drinking water pose health risks?
In late March, a National Academy of Sciences panel concluded that the maximum amount allowed by the federal government — 4 milligrams per liter of water — puts children at risk for developing mottled, pitted teeth and can weaken bones over a lifetime, making fractures more likely.
And a journal article scheduled to be published this weekend is expected to link fluoride to a rare bone cancer in boys.
“The thing about fluoride is it’s just a very toxic material,” said Richard Wiles, senior vice president of Environmental Working Group, a Washington, D.C.-based nonprofit research and advocacy organization. “We feel the science is very strong that fluoride is linked to a higher rate of cancer in boys. … It’s a really poor risk-benefit balance, to say the least.”
Such findings worry Dorothea Ratliff of Louisville, who has four sons and two daughters. “Water is essential to life,” she said. “When you think of the risk factors with children, it’s scary.”
But other research has shown no link between cancer and fluoride in water, and many dentists strongly support fluoridation as a safe and effective way to improve dental health, which generally is poor in Kentucky.
“We have been using fluoride for years and years and years. There are always controversies, but in my understanding there is no proof,” said Evlambia Harokopakis-Hajishengallis, an assistant professor of pediatric dentistry at the University of Louisville. “At this point, I wouldn’t panic.”
Only 200,000 people in the United States live in places where fluoride in water meets or exceeds the Environmental Protection Agency’s maximum of 4 milligrams per liter. But drinking water levels in most places, including Kentucky and Indiana, do fall within the range linked to osteosarcoma, a bone cancer that strikes about 400 children nationally each year.
Last fall, state officials wrote that more than nine out of 10 Kentuckians receive “optimally fluoridated water” — 0.9 milligrams per liter — with the remaining residents getting their water from wells, cisterns or springs. In Louisville, the level of fluoride ranged from 0.9 to 1.1 milligrams per liter in 2005, within the “preferred range,” said Barbara Crow, spokeswoman for the Louisville Water Co.
Panel urges lower level
In light of possible health risks, the national science panel has recommended that the maximum allowable fluoride level should be lowered.
Besides what is added during treatment, fluoride occurs in varying amounts in water because of rock and soil formations.
The panel said about 10 percent of children in places with water-fluoride concentrations at or close to 4 milligrams per liter develop severe tooth problems. The panel also cited studies showing a higher risk of bone fracture in people exposed to concentrations of 4 milligrams per liter or higher.
The group’s report did not examine the risks and benefits of the levels typical in fluoridated water, which range from 0.7 to 1.2 milligrams per liter nationally.
The study on osteosarcoma, which did look at fluoride at those levels, is expected to be published in Cancer Causes and Control, the official journal of the Harvard Center for Cancer Prevention.
Harvard officials would not release an advance copy of the article, but a Wall Street Journal story said it will show that boys who drank water with approximately 0.3 to 0.99 milligrams per liter had five times the risk of osteosarcoma as boys drinking nonfluoridated water.
This is not the first study to suggest such a connection. According to the National Cancer Institute, a federal study in 1990 showed an increased number of bone tumors in male rats given water high in fluoride for two years.
And in 2001, a Harvard doctoral student reported in her thesis that boys drinking fluoridated water seem to have a higher risk of bone cancer.
Wiles of the Environmental Working Group said more than half a century of fluoridation, along with wide support by dentists, has “muddied the waters of scientific thought” when it comes to the dangers of fluoride. Although the incidence of osteosarcoma is extremely low, he said, any cases connected to fluoride are unnecessary.
Benefits vs. risks
But others say the benefits of fluoride in tap water still far outweigh the risks.
“I just think it’s good stuff,” said Dr. Lee Mayer, a Louisville dentist. “It’s the best and cheapest public health program imaginable.”
In 1999, the U.S. Centers for Disease Control and Prevention included fluoridation of water on its list of “10 great public health achievements of the 20th century.”
Mayer said he used to work in an Appalachian community without fluoridation and saw “terrible” rates of decay. He said he is suspicious about reports linking fluoride to health risks — although too much of anything is dangerous.
Harokopakis-Hajishengallis agreed that fluoride is safe and effective but said she plans to look at any new science.
Robert Murphy, who oversees Kentucky’s fluoridation program, also said he plans to look at the science and would follow the CDC if it lowered its maximum level from 4 milligrams per liter. But he said people wouldn’t get the same dental benefits if water levels are lowered beyond 0.9 milligrams.
Becky Hall of Jeffersonville Ind., whose daughter was getting a dental checkup at U of L this week, said she is not worried. “If there was something to be concerned about, I would be.”
Ratliff said despite her concerns, she plans to continue giving her family fluoridated tap water and encourage her children to brush their teeth. For her to change, she said, scientists would have to more conclusively prove the danger.
“And they’re still investigating,” she said.