Copyright 2010 Inside Washington Publishers. Reprinted with permission.

Under pressure to make a decision about safe levels of exposure to a flouride-based pesticide, EPA and other agencies are planning comprehensive action to address the risks of a mineral that has long been added to drinking water to improve dental hygiene but which critics fear poses high risks of bone disease.

Lawyers for the Fluoride Action Network, Beyond Pesticides, and Environmental Working Group said in a Nov. 15 letter that they will sue if EPA does not act within 30 days on their years-long request to stay a rule setting safety tolerances for residues of two fluorinated pesticides, sulfuryl fluoride and fluoride anion, on food. “Based on this unfortunate history, my clients’ patience has come to an end . . . EPA’s failure to make . . . a decision will result in our seeking relief in federal court,” the letter says.

The groups’ threat comes after the agency missed its Nov. 4 deadline to respond to the groups’ long-standing request to stay Bush-era rules that set tolerances for the two fluorinated pesticides, sulfuryl fluoride and fluoride anion.

The agency appears to be moving closer to making a decision on the pesticides’ tolerances, having met with representatives of Dow AgroSciences, the registrant, on Nov. 18 and Dec. 1. According to an EPA summary of the Nov. 18, meeting, company representatives presented the agency with new data that could help the agency “evaluate toxicity levels as it would pertain to residues on fumigated commodities, exposure of re-entry and determination of the appropriate . . . safety factor in the tolerance assessment.” Relevant documents are available on

Dow is the registrant for the two pesticides, one of which, sulfuryl fluoride, EPA approved in 2004 for conditional use as a fumigant on a wide variety of foods as an alternative to the ozone-depleting methyl bromide. A spokesman with Dow did not return a request for comment by press time.

In a Sept. 23 letter to the environmentalists’ attorney, Owens said he would be able to provide a “definite and concrete” plan for EPA action, vowing to revise a completed risk assessment for the tolerance decision by Nov. 4.

But after the deadline passed without EPA taking action, the lawyers sent the Nov. 15 letter that they can no longer accept EPA assurances for action.

But EPA is still crafting its response to the groups’ push for action on the tolerance despite promising earlier this year that it would address the issue by Nov. 4 as part of a coordinated interagency effort to address the minerals’ risks, according to a July 20 letter from EPA toxics chief Steve Owens to lawyers for the environmentalists.

“Your demand for action has received the highest attention within the Agency. The Administrator herself has recognized the importance of the fluoride issue and is interested in resolving your objections in the context of working simultaneously with our federal partners to develop a coordinated approach for determining safe levels of fluoride,” Owens said.

The informed source said that EPA was considering taking action to address fluoride risks in what would be a “global decision,” indicating it would impact multiple federal agencies. But Owens noted that despite Administrator Lisa Jackson’s interest in addressing the issue, she had been pulled away by competing priorities, such as the Gulf oil spill.

Owens said the agency is coordinating with other federal agencies, including the Department of Health and Human Services (HHS) to assess both “potential toxicities and benefits.”

The agency is re-examining the risks associated with fluoride, a naturally occurring mineral widely used at low doses in dental treatments and in public water systems to prevent tooth decay. The re-evaluation is partially in response to a 2006 National Research Council (NRC) report recommending that EPA strengthen its current drinking water protection goal, known as a maximum contaminant level goal, (MCLG) of 4 milligrams of fluoride per liter (mg/L) of drinking water to protect against adverse health effects.

In response to the NRC recommendations and other recent data on fluoride, EPA met with HHS several times last summer to share preliminary findings on safe levels of fluoride and sources of potential exposure, an agency source says. EPA has also recently completed a new draft risk assessment of fluoride and revised its reference dose (RfD), or estimate of the daily amount of a chemical a human being could ingest over a lifetime without significant adverse effects, but an informed source says the agency has cited difficulty in reaching a unified solution with other agencies.

Senior EPA and HHS officials took up the fluoride evaluation last June, and discussed both the potential toxicities and benefits of the mineral, the EPA source says, building on a body of work that EPA began several years ago following the NRC recommendations.

The inter-agency discussions included topics such as how EPA should do the risk assessment, potential adverse health endpoints, how to adjust a fluoride RfD, how to accurately address fluoride exposures for vulnerable populations, and uncertainties involved in characterizing fluoride risk.

The NRC report concluded that three adverse health effects warranted consideration in developing regulatory standards for high levels of fluoride in drinking water — severe enamel fluorosis, potential risk for bone fractures and the more severe forms of skeletal fluorosis after lifetime exposure. — Bridget DiCosmo