EPA report labels cleanup as success

The United States Environmental Protection Agency on Friday released the final Site-Wide Human Health Risk Assessment for the Libby Asbestos Superfund Site, declaring the environment around Libby and Troy safe from excessive exposure to asbestos.

“EPA completed its rigorous scientific review of toxicity values and a draft risk assessment in December 2014,” wrote Stan Christensen in a Nov. 20 press release. “Comments received during a public comment period for a proposed cleanup decision did not change the agency’s ultimate conclusion: it is possible to live and work in Libby and Troy without excessive exposure to asbestos.”

The agency report analyzed several specific exposure risk scenarios for human health risks, including ambient air, soil and duff disturbances, indoor air exposure, disturbance of wood-related materials and fire-related activity exposure scenarios.

According to the report, the presence of asbestos measured in the ambient air of Libby, Troy and the mine site is much lower than in previous years.

“Current ambient air concentrations at the site are greatly improved relative to historical conditions and are consistent with asbestos levels that have been measured in ambient air in Eureka and Helena, as well as across the country,” the report read. “Data from the recent ambient air monitoring studies at the site were used to calculate exposure point concentrations for use in evaluating potential exposures to Libby amphibole asbestos in ambient air... These results indicate that exposures to Libby amphibole asbestos in ambient air are not likely to be of concern to individuals at the site and are not likely to contribute significantly to cumulative risks.”

The agency also concluded there is relatively low risk for exposure as a result of soil and duff disturbances.

“EPA has conducted several investigations at the site to characterize Libby amphibole asbestos in soil from areas that are thought to be representative of ‘background’ conditions, meaning that the soils are not expected to be affected by anthropogenic releases from vermiculite mining and processing activities,” the report read. “Libby amphibole asbestos structures have been consistently detected in background soils within the Kootenai Valley. However, potential exposures and risks from Libby amphibole asbestos in background soil are likely to be low.”

The report acknowledged the potential risk of exposure from the disturbance of indoor air, especially in properties in a pre-cleanup status and during tradesperson activities, such as remodeling and construction-based activities. The report indicated that exposures inside properties deemed to require cleanup but which have not been cleaned up for both residential and work-related activities.

“These results indicate that local tradesperson exposures have the potential to be significant and result in risks above a level of concern if appropriate personal protective measures are not employed to mitigate exposures during active disturbances of indoor source materials,” the report read. “There is the potential for tradesperson exposures to occur, even for properties that have had an interior removal or where no interior removal has been deemed necessary, if source materials have been left in place.”

The long-term status of properties on which source materials were left in place has been a topic of discussion among officials and community residents as the agency works to finalize the Record of Decision and make determinations about the long-term institutional controls to be left in place to manage potential exposure scenarios following the end of the active remediation phase of the project.

The agency has determined that some levels of Libby amphibole asbestos will be left behind, both in soil and in the interiors of some structures, if it was deemed to be contained or sealed behind existing walls and ceilings or in concentrations of less than trace on less than 25 percent of the outside property. The report confirms disturbing those areas, as well as disturbing areas on which cleanups were necessary but not undertaken due to a lack of owner permission, can create potentially dangerous exposure scenarios.

Agency project manager Rebecca Thomas characterized the report as good news for the people of south Lincoln County, saying it provides scientific evidence that the cleanups performed in the area have been protective of public and environmental health. 

“This is a great milestone for the project, the risk assessment shows cleanups done to date are protective and paves the way to select a remedy, still anticipated for December 2015,” she said. “Cleanups are protective and EPA continues to encourage property owners to participate in the project.  While the mine site is on a separate track, the risk assessment will also be used to support the Remedial Investigation for the mine.”