A national panel of scientists reported Wednesday that high levels of naturally occurring fluoride in drinking water are leaving children in some communities at risk of tooth enamel damage and adults prone to weakened bones that could lead to fractures.
The scientists unanimously recommended that the federal limit on fluoride in drinking water be lowered to protect people in communities where high levels leach into the water from natural sources, such as rocks or soil.
Many cities, including Los Angeles and many California communities, that have low levels of naturally occurring fluoride add it to water to protect against tooth decay, but they are unaffected by the new findings because the concentrations of added fluoride are much lower than the federal standard.
At the request of the U.S. Environmental Protection Agency, a panel of the National Academy of Sciences examined the EPA's standard, which allows 4 parts per million of fluoride in drinking water supplies.
About 200,000 Americans have drinking water with fluoride concentrations at or above the EPA's limit, and 1.4 million have water with levels between 2 and 3.9 ppm, including parts of Colorado, West Texas, New Mexico, Indiana and Illinois. No Californians have tap water with fluoride that approaches the amount the scientific panel found unsafe, because state regulations limit the concentration to 2 ppm.
For several decades, many have debated the safety of fluoridating water, but dentists and public health officials support it, saying it strengthens teeth and prevents cavities.
About two-thirds of Americans, or 162 million people, drink from fluoridated water supplies, which contain a fluoride concentration of about 1 ppm, much less than the amount the panel found had adverse health effects.
The panel of the National Research Council reviewed all the scientific evidence about exposure to and effects of fluoride, particularly over the last 12 years. It determined that lowering the EPA's 4-ppm limit would "prevent children from developing severe enamel fluorosis and will reduce the lifetime accumulation of fluoride into bone," which "is likely to put individuals at increased risk of bone fracture."
Dr. John Doull, professor emeritus of pharmacology and toxicology at the University of Kansas Medical Center, who chaired the panel, said the panel was not recommending a specific amount, only that it should "clearly be less than 4."
