LIBBY — Frustration boiled over Tuesday at a meeting in Libby where federal scientists were long on technical explanations but short on answers about how toxic Libby’s unique form of asbestos really is.

“What is a safe dose for Libby?” Lerah Parker asked. “I want to know when it’s safe to bring my family back to our property.”

Ten years ago Parker and her husband, Mel, were forced off their land — the former vermiculite screening plant for W.R. Grace & Co. — and had to close down a thriving nursery business. To a large extent they’ve been in limbo ever since.

The Parkers’ property was cleaned and now is known by the U.S. Environmental Protection Agency as Operable Unit 2. Libby’s Superfund site is so big it has been broken down into eight units.

Proposed remedial-action plans for the first two units, the former screening plant and export plants, are in the public-comment phase until Dec. 16, after which the EPA is expected to issue a Record of Decision on the properties.

Once a Record of Decision is issued, “it doesn’t mean the EPA walks away from the property,” assured Helen Dawson, EPA chief of the Superfund science policy branch.

It didn’t make the Parkers feel any better when David Berry, an EPA toxicologist, admitted he doesn’t know yet what a “safe dose” is for their property.

Berry was on hand to explain the federal agency’s risk-assessment process for the Libby Superfund site. Risk assessments have been completed for Operable Units 1 and 2, but assessments for other portions of the Superfund site continue. They include the city of Libby, the vermiculite mine site, the former Stimson lumber mill, railroad and highway corridors and the Troy community.

The federal government mobilizes cleanup efforts once the risk assessment shows one death per 10,000 people, Berry explained.

But Gordon Sullivan, a Libby writer and former technical adviser for the Libby cleanup project, pointed out that the Libby area, which has a population of roughly 10,000 people, has had 31 deaths just from asbestos-related mesothelioma, a tumor-causing cancer.

“We’ve based the cleanup strategy on an analytical strategy that doesn’t work,” Sullivan told the scientists. “We’ve tried to wrap our arms around this and have stylized our lives around information you give us.”

Risk assessments for Libby amphibole asbestos — a more deadly needle-sharp fiber than the less-toxic chrysotile asbestos — are based largely on old science that determines the level of asbestos with polarized light microscopy, EPA officials admitted.

Toxicology assessments are based on 1985 data from studies on lesser toxic asbestos, not Libby asbestos. And epidemiology and toxicology studies of Libby asbestos are a minimum of five years away from being completed.

“We’d like to have better information about Libby amphibole,” Dawson said.

If studies show that Libby asbestos is more potent, it may identify new or additional areas for cleanup, she added.

Libby City Council member D.C. Orr assured Dawson, “I think you’ll find Libby amphibole is more potent,” but Dawson stressed that “as a scientist we have to have the data to prove that.”

Sullivan said after the meeting that he believes the EPA “doesn’t want to know what’s in the soil,” otherwise the agency would use information from peer-reviewed research completed in 2003 by Drs. D.W. Berman and K.S. Crump. Their study established exposure benchmarks for mesothelioma and lung cancer based on asbestos epidemiologic studies.

“They’ve taken that report and put it aside and won’t recognize it,” Sullivan said. “The question now becomes if we’re going to use the best available science.”

 Features editor Lynnette Hintze may be reached at 758-4421 or by e-mail at lhintze@dailyinterlake.com