For several years, the Agency for Toxic Substances and Disease Registry (ATSDR) has been actively working on issues related to this evaluation:
- Beginning in 2004, ATSDR evaluated asbestos exposures to students and staff at Oak Ridge High School in El Dorado Hills, California. ATSDR released public comment and final health consultations in 2005 and 2006, respectively. See Past Public Health Activities for more information.
- During 2006, ATSDR responded to an issue raised by the National Stone Sand and Gravel Association (NSSGA) in December 2005. This group questioned whether the asbestos reported in the U.S. Environmental Protection Agency (EPA) sampling was truly asbestos or cleavage fragments. Cleavage fragments form by breaking off from minerals with the same chemical structure as asbestos materials, but with different crystal structure. Although individual cleavage fragments may look like asbestos particles, some postulate that they are not as harmful as asbestos particles. In response to these questions, ATSDR requested in March 2006 that the National Toxicology Program conduct toxicity studies on which particles contribute to asbestos-related health effects (these studies will take several years to complete). Also in response to the NSSGA issue, EPA requested that the U.S. Geologic Survey perform a geologic analysis of the El Dorado Hills area. This study was completed in December 2006. See Past Public Health Activities for more information.
- In 2006, ATSDR held an expert panel on biomarkers of exposure (signs in people’s bodies that they have been exposed to chemicals) in 2006 to discuss the state of the science for assessing community exposure to asbestos. Although research continues, reliable methods are not available for taking measurements in a person’s body to measure their past exposure to asbestos, and these methods cannot currently be used to assess community exposures. Using activity-based air sampling data and applying risk assessment methods remain the best ways to assess community exposures and risk. See Past Public Health Activities for more information.
- In 2006, ATSDR identified additional analyses needed on the air sampling filters to allow the use of the risk assessment method that accounts for differing toxicity of amphibole asbestos. Obtaining funding and completing the lab analyses were time consuming; results were available in 2007.
- During 2007 and 2008, ATSDR developed and tested a life table analysis spreadsheet to account for early life exposures. Although this work was based on that of other researchers, ATSDR updated mortality data, developed an in-house spreadsheet to perform calculations, and wrote an explanation of the theory behind the analysis. We completed these tasks in 2008.
- In 2009, ATSDR sent a draft of the health consultation report on community-wide exposure to naturally occurring asbestos for external peer review and prepared a revised draft responding to peer review comments.
- On March 29, 2010, ATSDR released the public comment draft of the health consultation on community-wide exposure to naturally occurring asbestos. The public comment draft included peer review comments and the responses and changes made to address the comments received. On June 30, 2010, the public comment period for the health consultation closed.
- On August 16, 2011, ATSDR released a final version of the health consultation, including public comments received and the responses and changes made to address the comments received.