An Oak Ridge-based scientist told a community group Tuesday that she believes the Environmental Protection Agency regulations concerning the maximum allowable concentration of fluoride in drinking water, far higher than found in local water supplies, do not include an adequate safety margin.

Kathleen Thiessen, senior scientist with SENES, Oak Ridge Inc., Center for Risk Analysis, spoke at a meeting of Citizens for Blount County’s Future. She served on a committee that produced the National Research Council’s 2006 review, “Fluoride in Drinking Water: A Scientific Review of EPA’s Standards.”

The committee recommended that the EPA lower its established maximum concentration of 4 milligrams per liter (mg/L) allowed in drinking water. This guideline is the maximum allowable concentrations in drinking water intended to prevent toxic or other adverse effects that could result from exposure to fluoride; however, this is meant to protect people from levels of fluoride far higher than what is recommended by the U.S. Public Health Service for the public fluoridation of drinking water — between 0.7 to 1.2 mg/L.

“It is higher than anybody fluoridates to,” Thiessen said.

The city of Maryville, which has fluoridated its water since 1959, maintains levels below the current PHS guidelines. “We are allowed to put in between .5 to max of .90 milligrams per liter,” spokeswoman Pam Arnett said. “We tend to average .7.”

The city of Alcoa maintains fluoride levels at about .7 or .8 mg/L.

South Blount County Utility District Manager Henry Durant said his utility fluoridates water at .6 mg/L.

Still, Thiessen does not believe there is an adequate safety margin built into the EPA guidelines. “We’ve said that 4 milliliters per liter is not safe,” she said. ”Between not safe and recommenced is approximately a factor of four.”

In the risk management field, an acceptable margin of safety is a factor of 10 or 100, she said.

“If EPA were to set it according to the way that EPA usually sets these things, the maximum level would be zero,” she said.

No benefits

Thiessen’s interpretation of available data is that fluoride does not provide benefits against cavities. “The data do not support the benefits as we were told by the (Centers for Disease Control),” she said.

According to the EPA, exposure to excessive consumption of fluoride over a lifetime may lead to increased likelihood of bone fractures in adults, and may result in effects on bone leading to pain and tenderness. Children age 8 and younger exposed to excessive amounts of fluoride have an increased chance of developing pits in the tooth enamel along with a range of cosmetic effects to teeth. According to the 2006 report: “Lowering the (maximum) will prevent children from developing severe enamel fluorosis and will reduce the lifetime accumulation of fluoride into bone that the majority of the committee concludes is likely to put individuals at increased risk of bone fracture and possibly skeletal fluorosis, which are particular concerns for subpopulations that are prone to accumulating fluoride in their bones.”

The prevalence of severe enamel fluorosis is very low (near zero) at fluoride concentrations below 2 mg/L, according to the report.

The study did not examine benefits or risks of fluoridation at levels in keeping with the Health and Human Services guidelines.

“We did not specifically evaluate the levels for fluoridation, but we certainly did use them when estimating exposures,” she said. “There is relevance.”

According to the EPA, in 2006, there were about 200,000 Americans living in communities where fluoride levels in drinking water were 4 mg/L or higher. A majority of the report’s authoring committee concluded that people who drink water containing 4 mg/L or more of fluoride over a lifetime are likely at increased risk for bone fractures.

Enamel fluorosis can range from mild discoloration of the tooth surface to severe staining and pitting.

Utility voting

CBCF member Linda King said her group is trying to educate people about fluoride concerns, which is especially important given that SBCUD is allowing its customers to vote on whether to continue water fluoridation. SBCUD has sent out postcards so each account gets one vote. Customers will have through May to return those. The return date deadline will be June 15.

The accounting firm, Ingram, Overholt, and Bean, will tabulate the results and forward them to the utility’s Board of Commissioners, which is expected to vote on the issue during its July meeting.

The addition of fluoride to the water supply has been the subject of local controversy since the SBCUD board originally voted not to fluoridate the water when the district opened its new plant in July 2004.

In 2008, however, the board voted to begin fluoridation at the request of then-Blount County Mayor Jerry Cunningham. Fluoridation ultimately began that May.