Libby Amphibole asbestos


IRIS Toxicological Review of Libby Amphibole Asbestos (Interagency Science Discussion Draft)

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On August 25, 2011, the draft assessment of Libby Amphibole asbestos was released for external peer review and public comment. The draft assessment was revised based on peer review comments from EPA’s Science Advisory Board (SAB) and public comments. The revised draft was reviewed (Step 6 of the IRIS process) internally by EPA and by other federal agencies and the Executive Office of the President before final public release. Based on the IRIS process, all written comments on IRIS assessments submitted by other federal agencies and the Executive Office of the President are made publicly available. Accordingly, interagency comments with EPA’s response and the interagency science discussion drafts of the IRIS Toxicological Review and IRIS Summary for Libby Amphibole asbestos are also posted on this site.


U.S. EPA. IRIS Toxicological Review of Libby Amphibole Asbestos (Interagency Science Discussion Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-11/002D, 2014.


Samantha J. Jones,  Ph:  202-564-6794,  Email:

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This draft health assessment of Libby Amphibole asbestos was prepared by staff in both EPA’s Region 8 Office and ORD/NCEA. The assessment is focused on a specific type of asbestos termed “Libby Amphibole asbestos”. Libby Amphibole asbestos (LAA) identifies the mixture of amphibole mineral fibers of varying elemental composition (e.g., winchite, richterite, tremolite, etc.) that have been identified in the Rainy Creek complex near Libby, Montana. LAA is a specific type of asbestos found in the vermiculite ore mined and processed in Libby, MT. Vermiculite is a mineral used as building insulation or as a soil amendment. LAA is made up of very durable fibers that do not typically dissolve or break down. They can remain airborne for a long time, but eventually settle into soil, or other materials (e.g., carpet).

Libby was identified as a Superfund site because of this asbestos contamination. In 2009, EPA announced a public health emergency at the Libby Superfund site because of the serious health impacts from asbestos contamination in the community. This is the first time EPA had made a finding under the Comprehensive Environmental Response, Compensation, and Liability Act (or Superfund) that conditions at a site constituted a public health emergency. The IRIS assessment of LAA addresses the potential cancer and noncancer human health effects resulting from long-term exposure.


Date Description
Aug 2007The Libby Amphibole asbestos assessment was initiated in 2007. It was nominated for assessment by the IRIS Program because it supports OSWER and Region 8 site clean-up and related risk management initiatives at this Superfund site. An assessment for Libby Amphibole asbestos is not currently on IRIS.
May 2011EPA hosted an interagency science consultation on the draft IRIS Toxicological Review of Libby Amphibole asbestos.
Aug 2011EPA released the External Review Draft for public review and comment, and announced the public listening session would be held on October 6, 2011. [Federal Register Notice Aug 25, 2011]
Oct 2011EPA conducted a public listening session on the draft assessment.
Feb 2012EPA’s Science Advisory Board (SAB) held a public peer review meeting on the draft IRIS assessment.
Jan 2013EPA’s SAB released the final peer review report, “Review of EPA’s Draft Assessment Entitled Toxicological Review of Libby Amphibole asbestos (August 2011)."
Aug 2014EPA submitted the draft document for final agency and interagency review prior to releasing the final report.
Dec 2014EPA released the final report on the IRIS web site.


The final assessment has been loaded on the IRIS website and database. This assessment does not replace the existing IRIS listing for asbestos (EPA, 1988).

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This download(s) is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency determination or policy.

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