Scientists contest determination that Lincoln County residents are safe

The Environmental Protection Agency’s toxicity value for Libby Amphibole asbestos has drawn both criticism and praise.

W.R. Grace & Co., which owned and operated the vermiculite mine near Libby until its closure in 1990, challenged the agency’s determination of what constitutes an adverse health impact.

Representatives for W.R. Grace declined to comment, although the company paid for a study that argued against the use of pleural plaques as a risk factor. The study was presented to the EPA on Oct. 31, 2014 in anticipation of the release of final toxicity values and human health risk assessment for Libby Amphibole asbestos.

“The presence of pleural plaques indicates that an individual was likely exposed to asbestos and is therefore at risk for asbestos-related disease. Because pleural plaques do not cause lung function decrements themselves, the exposure level at which they occur should not be used to define the level of asbestos likely to cause adverse health effects,” according to the W.R. Grace-funded study.

On the other hand, Terry Trent, a biologist who has researched asbestos since 1996, said the agency’s determination that Libby is safe is based on misleading data.

“There is no safe when it comes to amphibole asbestos, far less so considering EPA’s measuring paradigm of calm ambient air, which is irrelevant to personal exposures,” Trent said.

Trent’s concern is rooted in the measurement of ambient air, which the EPA has declared to be 100,000 times cleaner than it was in 1975. Ambient air measurements, though, do not take into account exposure that occurs when vermiculite is stirred up and released into the air through activities such as home remodeling, tilling and gardening and in cases such as a fire in a contaminated building.

Dr. Brad Black of Libby’s Center for Asbestos-Related Diseases said he believes the EPA correctly assessed the risks of human exposure.

“You apply the best science you have at the time,” he said. “And in this case they did such a good job. They went through a rigorous process and the end result is good science.”

Pleural plaques are scar tissues that build up around the lungs and in the chest cavity. While Gradient challenged the assertion that this build-up of tissue is harmful, Dr. Black disagrees.

“When I left training in 1974, basically pleural plaques told you that you were exposed, you had an exposure to asbestos, but it was not thought to have any significant health implications,” Black said. “But, in Libby, pleural plaques have become an indicator that you got exposed enough that you are at risk for very advanced and life-taking disease. We’ve watched people go from pleural plaques to death in six years. They are a disease. They’re associated with significant breathing problems.”

Professor Arthur Langer, Director of the Environmental Sciences Laboratory at the Brooklyn College of the City University of New York, offered this: “The central issue to the Libby problem is safety. Is 90 fibers per cubic meter of air safe for humans?’ How do you define safe? Absolute safety is absolutely unobtainable.”

EPA scientists agree that there is still risk associated with certain types of activities. Logging activities near the old mine site pose a risk of exposure to contaminated air, as does burning wood harvested near the site. Demolition and construction activities in homes with vermiculite insulation in the attics and walls are also considered to pose hazards above the agency’s target safety standard.

Some concern also was raised by the inclusion of non-scientific agencies in the process. Part of EPA’s standard review process is to distribute the draft report to every government agency and allow comment.

Agency senior toxicologists defended the toxicity assessment and the process.

“This document has received numerous internal and external reviews,” EPA toxicologist Deborah McKean said.

EPA toxicologist David Berry added, “Science governs the science of the report. While we do represent everyone who is a stakeholder and we want to receive and address all of the comments, it doesn’t impact the science.”

In addition to public comment and interagency review, the document was also submitted to an independent Science Advisory Board. That board is comprised of 21 scientists and experts, none of whom are employed by the EPA or the federal government.

The board completed their review of the draft toxicity report in January 2013 and issued this response: “The SAB finds the EPA’s draft assessment to be comprehensive and generally clear, logical and well-written.”

The board further defended the use of pleural plaques as an adverse health impact.

“Localized pleural thickening is an appropriate health endpoint for the derivation of the inhalation reference concentration. It is an irreversible structural, pathological alteration of the pleura and is generally associated with reduced lung function.”