The amount of fluoride allowed in drinking water by the U.S. Environmental Protection Agency could harm young children by pitting their teeth and stripping off the protective enamel, the National Academy of Sciences concluded in a report sponsored by the EPA.
The report called on the EPA to lower the maximum allowable levels of fluoride, which could particularly affect water systems that rely upon wells, where naturally occurring fluoride can be present.
Most public water systems, including large systems in the Lowcountry, treat water so that it has a low level of fluoride considered beneficial for preventing cavities.
The EPA’s response to the National Academy of Sciences report could narrow the gap between the amount of fluoride considered beneficial in public water and the amount considered harmful. The report didn’t suggest what maximum fluoride level would be appropriate.
At about 1 part per million of fluoride, which is roughly one drop in a 40-gallon drum, fluoride has been found to prevent cavities. Twice as much, however, is known to permanently stain or damage teeth, and four times as much can harm bones, conditions known as fluorosis.
Coastal South Carolina is one area in the United States where groundwater often contains significant levels of fluoride. When the EPA set a fluoride limit of 4 parts per million in 1987, more than 60 South Carolina water systems exceeded the limit. Communities stretching from Sullivan’s Island to Jamestown faced state consent orders to reduce the fluoride in their water systems. Young children east of the Cooper River and in the Summerville area were at risk of having their teeth stained or damaged by the fluoride level.
Today there is just one system in South Carolina exceeding the 4 ppm standard, according to the state Department of Health and Environmental Control.
It’s the Strawberry Mobile Home Park in Berkeley County, which is in the process of connecting to the Berkeley County water system.
“Where we’re seeing elevated levels are in private wells, primarily along the coast,” said Thomas Berry, a DHEC spokesman.
Charles Poole, an author of the National Academy of Sciences study and an associate professor in the School of Public Health at the University of North Carolina, said roughly one child in 10 would be expected to get severe enamel fluorosis in areas where fluoride concentrations are around 4 ppm. To nearly eliminate severe fluorosis, the EPA would need a standard below 2 ppm, Poole said.
“A little bit below 2, there’s only an occasional case,” he said. “Above that it rises fairly sharply.”
Of the 673 water systems in South Carolina, just nine fall between the 2 and 4 ppm level. They are mostly small systems in the Lowcountry.
Edisto Beach is the largest of the nine, with about 6,000 customers, and Georgetown County Water and Sewer District’s Carver’s Bay service area has the highest fluoride level, at 3.1 ppm.
The directors of the Edisto and Georgetown systems could not be reached for comment Thursday.
The national Centers for Disease Control has long warned that children younger than 9 should not have, as their primary drinking source, any water containing more than 2 ppm of fluoride. At those concentrations, about 15 percent of children could get discolored teeth from mild fluorosis, while smaller numbers could be more seriously affected, according to the CDC and EPA.
The EPA requires water systems to notify customers when fluoride exceeds the 2 ppm level, but does not require enforcement action unless the level hits 4 ppm, because the agency has considered enamel fluorosis to be a cosmetic problem, rather than a health risk. The National Academy of Sciences study calls on the EPA to consider severe enamel fluorosis a health problem.
One of the eight water systems in South Carolina above the 2 ppm level is Minnie Hughes Elementary School in Hollywood. The school, which has it’s own well, is just above the 2 ppm level, according to DHEC, which Poole did not find alarming.
“Even with 60 years of accumulated research, we can’t say with certainty that you’ll be at increased risk at 2.1 ppm, but not at 1.9,” Poole said. “Health science is intrinsically more fuzzy than that.”