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New EPA data shows surprises for asbestos exposure

by Jeremie Vella Western News
| May 9, 2008 12:00 AM

New data from the Environmental Protection Agency suggests that soil is a prominent source of exposure to vermiculite. Such a conclusion has the potential to reshape how the EPA assesses risk for remediation, as well as definitions for what it considers a “clean site.”

The research surprised many because it suggests that asbestos exposure comes mainly from contaminated soil outside of one’s house. Indeed levels of exposure during indoor activities most likely comes from tracking outdoor vermiculite inside through pathways such as animals or shoes.

The data does not apply to homes where asbestos is disturbed, or not well contained within the walls of the house.

“This is a powerful data set,” said Paul Peronard, On-Site Coordinator for EPA. “It will help us define the first part of endgame,” or how the agency decides that a site is properly cleaned.

The exposure investigation centered around four or five indoor and outdoor activities, ranging from mowing the lawn to watching television. The EPA also selected a variety of sites, including those that were not treated as well as post-remediated properties.

Scenarios were played out by testers at these sites, with air filters located near their chests that collected dirt samples, recreating the breathing experience of typical activities.

Many in the community have questioned how risk is assessed in Libby sites. The EPA believes that this data will go a long way in answering risk assessment questions. For instance, a property where soil is highly contaminated with vermiculite may be preferred over a property where asbestos is well contained within walls.

Another important change is that the EPA now feels it is essential to “chase visible vermiculite.”

Equally encouraging news from the report suggests that walking around Libby exposes one to relatively low amounts of asbestos.

The news is not all good, however. The data demonstrates serious problems for the EPA in determining the success of remediation. The amount of variables, wind direction, soil moisture and vegetation cover for instance, can affect the outcomes of data sampling.

Moreover, the data does not address the amount of background asbestos, or asbestos that occurred naturally before the mine exposed the city to high levels of vermiculite. The U.S. Geological Survey will conduct a study of local areas to try to determine where vermiculite may have been brought in by glaciers or other natural causes.

For more information on the findings, call the EPA Information Office at 293-6194.