May 11, 2005
ATSDR was created by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, more commonly known as the Superfund law. The Superfund program is responsible for finding and cleaning up the most dangerous hazardous waste sites in the country. Currently, the U.S. Environmental Protection Agency (EPA) lists for cleanup 1244 National Priority List (NPL) sites. ATSDR leads federal public health efforts at these and other sites with actual or potential toxic exposures. In accomplishing this purpose, ATSDR’s priorities include 1) mitigating the risks of health effects at sites with documented exposures, 2) preventing exposures and resulting health effects, and 3) determining health effects associated with exposures.
I have been leading ATSDR’s work in El Dorado Hills, and have significant responsibility in the Agency’s other asbestos-related work. As you may be aware, asbestos is a name given to a group of six different fibrous minerals that occur in the environment. There are two main families of asbestos fibers: the serpentine form, such as crysotile, and the amphiboles, including crocidolite, amosite, and tremolite. Chrysotile is the most common type of fibrous serpentine, with long, flexible fibers, and it is the type most commonly used in commercial products. Amphibole fibers, on the other hand, are brittle, having a rod or needle shape. Although exposure to both types of asbestos increases the likelihood of developing asbestos-related diseases, amphibole fibers tend to stay in the lungs longer and are thought to increase the likelihood of illness, especially mesothelioma, to a greater extent than chrysotile asbestos. The type of asbestos found at El Dorado Hills is primarily amphibole asbestos.
I will begin my testimony with a brief discussion of ATSDR’s involvement with asbestos issues. Our most recent experiences begin in 1999 in the town of Libby, Montana, where vermiculite ore contaminated with amphibole asbestos was mined and processed from the early 1920s until 1990. I will then discuss our work at El Dorado Hills.
ATSDR’s Work In Libby, Montana
Results of these activities and additional evaluations conducted by ATSDR, EPA, and the State of Montana indicate that people who worked in the Libby mine or processing facilities belonging to W.R. Grace Company and people who lived in the Libby community were exposed to asbestos through contaminated vermiculite, a mineral that was processed into a variety of products, including insulation.
ATSDR undertook medical screening of over 7,300 persons who were potentially exposed to the asbestos in Libby vermiculite. Nearly 18% of medical screening participants had radiographic pleural abnormalities consistent with asbestos exposure. Of the former W.R. Grace employees receiving x-rays, 51% had pleural abnormalities and 3.8% had interstitial lung abnormalities. Mortality due to lung cancer and asbestosis was also found to be elevated in Libby. ATSDR has implemented a Tremolite Asbestos Registry (TAR) of exposed persons (tremolite is one of the amphibole asbestos types found in Libby). The TAR will allow for tracking the health of individuals exposed to tremolite asbestos from the mine in Libby. ATSDR also has funded the State of Montana to conduct additional periodic medical surveillance for eligible persons.
ATSDR’s Work in Addressing Potential Libby Asbestos Exposures Elsewhere in the United States
These exposure pathway investigations are initially being conducted at 28 “Phase One Sites” that have been identified for evaluation on the basis of the nature of processing performed, tonnage received, and current site conditions. The findings for these Phase One sites will guide our future actions with regard to other sites that received and processed vermiculite ore from Libby. Health statistics reviews (to evaluate mortality and/or cancer registry data) are currently under way in 25 states, and pilot mesothelioma surveillance has been initiated in three states (New York, Wisconsin and New Jersey). In addition, ATSDR has funded a comprehensive community exposure assessment project in a community in Minnesota where neighborhoods may have been exposed to particulate air emissions and/or waste dumping from a plant that received asbestos-containing vermiculite ore from Libby, Montana. ATSDR is also funding a study to evaluate the progression of asbestos-related pulmonary abnormalities among a group of workers in Ohio who had past exposure to Libby vermiculite.
Although these methodologies have certain limitations, for the five health statistics reviews completed to-date, ATSDR did not find any significant excess of asbestos related mortality or asbestos related malignancies in communities near the sites. For the twelve health consultations completed to-date, ATSDR has determined that former workers and household contacts were likely to have been exposed to asbestos released during vermiculite processing and that further public health intervention is warranted for these groups.
What Has ATSDR Done in El Dorado Hills, California?
As you are aware, Oak Ridge High School is located in El Dorado Hills, California, about 30 miles northeast of Sacramento in El Dorado County. Naturally occurring asbestos (NOA)—as opposed to asbestos encountered through mining or processing—has been identified in rocks and soils on and around school property. ATSDR became involved through our petition process, by which a community member requested that the Agency evaluate the public health implications of current and past asbestos exposures to students and staff at the high school. ATSDR has investigated the asbestos exposures at the school, prepared a public health consultation, and released the findings of the health consultation to the public on May 6, 2005.
Sampling by the school district and the EPA showed that asbestos, of the amphibole variety, is in soil and in air near disturbed soil on the school grounds. ATSDR is concerned with the health implications of breathing in asbestos fibers because exposure can be associated with pleural disease, asbestosis, lung cancer, and mesothelioma. ATSDR is well aware that many issues in asbestos science are currently debated among scientists, including the role of mineralogy and fiber size in toxicity, the best means of assessing exposure, and methods for measuring disease within an exposed population.
To this end, ATSDR has used its experience at numerous sites across the nation, combined with the best science possible, to determine the impact of asbestos exposure on students, faculty, and staff at Oak Ridge High School. To assess the impact of asbestos exposures on the Oak Ridge High School community, ATSDR used information from several agency public health activities. These activities include use of an expert panel on the role of fiber size in asbestos toxicity following the World Trade Center disaster; experience in testing asbestos-exposed populations in Libby Montana; agency work to improve asbestos toxicity assessment; and experiences throughout the agency’s years in educating the public, training health care workers, and mitigating exposures.
To provide the best science possible, ATSDR has participated in and hosted a number of workshops in asbestos exposure and toxicity assessment. To ensure scientific integrity, ATSDR asked three asbestos science experts who have no affiliation with ATSDR to peer-review the public health consultation. The purpose of the peer review was to ensure that the evaluation performed in the document used the best science, given the nature of the available information. ATSDR released the public health consultation (including peer review comments and our responses) to the public for comment on May 6, 2005.
ATSDR has provided an active federal presence in the El Dorado community by participating in a public meeting organized by EPA in February 2004; by distribution of a newsletter to the community on agency activities in June 2004; by a presentation on the agency's experience and knowledge about health effects of amphibole asbestos at a science seminar organized by EPA in August 2004; by responding to numerous phone calls and emails from community members; and by conducting teleconferences with community organizations, among other activities. The agency plans to continue its involvement with the El Dorado community and provide another health consultation that will discuss the broader community-wide data recently collected by EPA.
What Were ATSDR’s Findings?
ATSDR concludes that EPA and the school district personnel have removed the potential for exposure to asbestos on the school campus. Specifically, the classrooms have been cleaned and tested for asbestos, and all bare areas and soils containing asbestos have been either covered with clean fill or landscaped to prevent the release of asbestos fibers. ATSDR determined that current asbestos exposures at the school have been minimized and are not likely to increase the risk of disease.
The available data about past exposures and amphibole toxicity are insufficient to permit an accurate estimation of the risk from past exposures. However, ATSDR used the available data to reach general conclusions about likely exposures and to obtain a general sense of the health effects that could result from exposure. This evaluation of the data indicates that potential exposures to amphibole asbestos in the past were high enough to increase the risk of adverse health effects for highly exposed groups. These potentially highly exposed groups include coaches, outdoor maintenance workers, and student athletes, because they are most likely to have been exposed during the time they spent at the school fields and tracks.
This does not mean that people in these groups who were exposed in the past will develop asbestos-related disease. It means that potential exposures were high enough to increase risk and that it was necessary to take action to prevent further exposure by cleaning classrooms and covering soils or landscaping.
In summary, ATSDR finds:
The recommendations of the health consultation are the following:
What Are the Next Steps for ATSDR in El Dorado Hills?
Madame Chair, this completes my testimony, and I am pleased to answer your questions at this time.
Last Revised: May 17, 2005