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Historical Document

This web site is provided by the Agency for Toxic Substances and Disease Registry (ATSDR) ONLY as an historical reference for the public health community. It is no longer being maintained and the data it contains may no longer be current and/or accurate.

Public Health Response Plan


Exposure to tremolite asbestos in contaminated vermiculite ore has been recognized to be a public health problem. The vermiculite mining and processing facility located in Libby, Montana, operated fromthe 1920s until 1990. Persons who live in the Libby area have come into contact with vermiculite from this facility have been exposed to tremolite asbestos. This includes facility employees, those living in close proximity to the facility, and those who otherwise came into contact with vermiculite from the facility. At present, the Environmental Protection Agency (EPA) is intensively evaluating other facilities that processed vermiculite ore from the Libby mine, and at other vermiculite mining and processing facilities in the United States. The Agency for Toxic Substances and Disease Registry (ATSDR) responded to a petition requesting the agency to provide public health assistance to the community of Libby, and to a request from EPA for assistance to address the public health concerns of persons in other parts of the country who have been exposed to contaminated vermiculite originating in Libby, Montana. Such assistance may be required for additional areas of the country with facilities that mine and process vermiculite ore.

ATSDR is an agency of the U.S. Department of Health and Human Services (HHS) authorized under the Comprehensive Environmental Response, Compensation, and Liability Act (42 U.S.C. 9601) to conduct public health actions to address the uncontrolled release of hazardous substances into the environment. These actions include public health assessments and consultations, health studies, medical testing, medical surveillance, and exposure and disease registries. ATSDR works closely with state and local health departments, EPA, and other HHS agencies in carrying out its mission. Future ATSDR activities will be performed in a similar manner, which is consistent with ATSDR's statutory authorities.


A history of extensive human exposure of residents of the Libby, Montana area to tremolite asbestos in vermiculite ore has resulted in the presence of asbestos-related disease in this population. The potential also exists for exposure and the development of asbestos-related disease in other areas of the country where vermiculite contaminated asbestos was mined and refined. ATSDR has developed this proposed plan to address both immediate (FY 2000) and future (FY 2001 and beyond) public health needs. It is clear that the degree and extent of future work beyond the Libby area depends on the scope and level of asbestos exposure in those areas, and on the results of the initial medical testing in Libby. This document lays out a plan for how this broader investigation could proceed. As with the development of this medical testing program, ATSDR would develop future plans in consultation with other key agencies (for example, EPA, NCI, and NIOSH), which would depend on the availability of resources. The initial medical testing will be conducted in Libby, Montana, but additional testing at other vermiculite mining and processing sites in the United States may be required. The medical testing in Libby is being closely developed with state and local health officials and local physicians, so that referrals for future medical care needs arising from the medical testing program will occur with full coordination. In addition, ATSDR and the National Cancer Institute (NCI) are planning to convene a workshop in May 2000, at the request of local physicians in Libby, to review the most recent information on clinical proposals and potential new approaches for treating asbestos-related disease.


1. Environmental Data Review: Libby residents have been exposed to vermiculite contaminated with tremolite asbestos in the past, and current exposure may be occurring. ATSDR will continue to review environmental testing information to assist EPA and the State of Montana in identifying and eliminating human exposures to asbestos. The findings will guide future environmental sampling efforts and help identify persons at risk of potential adverse health effects who need additional testing and referral for medical treatment.

2. Medical Testing and Referral For Medical Care - FY 2000: To determine the magnitude of the pulmonary health impact of exposure to tremolite asbestos in Libby, a medical testing program will be conducted. This testing will evaluate the current health status of residents in the immediate vicinity of Libby, Montana. Persons who lived, worked, or otherwise contacted vermiculite, as defined by a protocol jointly developed with state and local health authorities, will be offered medical testing, which will consist of an in-depth standardized, face-to-face interview, chest radiographs, and lung function tests. Persons with pulmonary abnormalities, as defined by the project , will be referred to a physician for further evaluation. ATSDR has developed aprotocol to identify those eligible for the medical testing. This involves a short telephone interview of households within a 2.5- mile radius of the center of the Cityof Libby, plus two additional areas near the mine. Individuals residing outside this area who believe they have been exposed will have the opportunity to be screened for eligibility and participation. Once eligibility has been established, an appointment will be made with participants for administration of an in-depth questionnaire, standardized pulmonary function testing, and a chest X-ray. The Libby Medical Testing Project was developed by ATSDR, in cooperation with EPA and state and local health authorities, and with the assistance of external expert consultants. Based on ATSDR's previous experience, the interview will take about an hour for each participant. Chest X-rays (3 views per person to be consistent with the views of the outside expert consultants) and pulmonary function testing (spirometry) will follow the interview. Each X-ray will be read by a local physician and three independent experts, as outlined by the American Thoracic Society. A review of the results of pulmonary function tests will be conducted by respiratory experts. Approximately 3,000 persons are expected to be seen during a 90-day period. The testing office will run 6 or 7 days per week, 10 hours per day on weekdays. The results will serve the persons tested, will help define future health care resource needs of the community, and assist EPA in identifying ways in which persons have been exposed. ATSDR will request patient consent to review the results of physician referrals, which will improve the agency's ability to assess the public health impact of the medical testing program.

3. Health Care Provider and Community Health Education: ATSDR, in coordination with local health care providers, will provide community health education on asbestos-related pulmonary abnormalities through fact sheets and public meetings, which will include presentations, posters, and interactive sessions. Before, during, and after the medical testing program, ATSDR will provide local physicians with access to a network of medical specialists in occupational and environmental respiratory diseases. Local health care providers will be given additional training by medical experts in pulmonary disease before the medical testing program. During the medical testing, medical specialists can be available for hands-on or long-distance consultations. After the testing portion of the program is completed, the network of specialists will be available, if necessary, to accept referrals for diagnosis and recommendations regarding long-term care of pulmonary conditions identified during the medical testing. The responsibility for ongoing medical care will rest with local health care providers; however, consultation with the specialists will be facilitated by ATSDR.


Based on ATSDR's current understanding of contamination and resulting disease in the Libby area, the following activities are proposed. Upon completion of the initial environmental sampling and medical screening activities detailed in the "Current Needs" section of this plan, these activities will be expanded and/or revised as needed.

1. Additional Medical Testing: Once asbestos enters the lungs, it remains for a long time, with scarring of lung tissue and the lining of the chest wall (pleura) continuing. Therefore, it is anticipated that future testing will be necessary for all current residents of Libby who have been significantly exposed. The degree and frequency of additional testing will be partially directed by the findings of the first testing and by environmental exposure levels currently being identified by EPA. ATSDR may need to actively notify others who once lived or worked in Libby but have since moved elsewhere. The prevalence of abnormal conditions among persons participating in the initial testing (especially among those who have only community-based exposure to ambient air) will be an indicator of the need for more intensive future testing and will help determine whether other people need to be found and offered testing. Identification of former mine workers will be coordinated with NIOSH. Persons with abnormalities on chest radiographs will need more frequent evaluations, perhaps every 1 to 2 years, and those with no abnormalities on initial testing may need testing at less frequent intervals, depending on exposure history.

2. Health Care Provider and Community Health Education: Education of health care providers and community health education activities are both integral components of any long-term effort. ATSDR is currently, and will continue to, work closely with local health care providers to identify their training needs. An interactive training session on respiratory disease and asbestos-related exposures will be planned by ATSDR for local health care providers. Community health education on these topics will be provided through fact sheets and public meetings, which will include presentations, posters, and interactive sessions. Local health care providers will assist in the community health education effort.

3. Health Research: Health research is needed to better understand the pathogenesis of asbestos-related illnesses in residents of the Libby, Montana, area and to identify the most important environmental exposure pathways.

A. Preliminary Investigation: ATSDR is currently conducting a case-series to examine all nonoccupational cases of asbestos-related disease in residents of the Libby community. These cases are being identified from medical records of referral physicians. The goals of this case-series are to confirm the presence of asbestos-related abnormalities and to identify special exposure pathways. This effort will involve the confirmation of asbestos-related abnormalities on a chest X-ray by a panel of experts and personal interviews for about 40 persons who were previously diagnosed with asbestos-related disease.

B. Clinical and Pathologic Investigation: Little is known about the pathogenesis and natural history of lung disease associated with tremolite asbestos. Information from a clinical and pathologic investigation would be of extreme value in developing clinical case definitions for tremolite-related lung disease and for developing guidelines for the diagnosis and medical management of these illnesses. Understanding whether tremolite asbestos differs from other forms of asbestos will also be helpful to EPA in its ongoing oversight of asbestos exposures.

C. Epidemiologic Study: A protocol is being developed by ATSDR for an epidemiologic study to examine the association between different personal characteristics and various types of environmental exposures in the Libby community and the development of asbestos-related diseases. Many potential pathways of exposure exist and critical questions remain unaddressed regarding which pathways of exposure are most significant. This study will formally test hypotheses that are generated as a result of the case-series investigation being initiated by ATSDR in FY 2000. Persons tested and diagnosed with probable asbestos-related disease (cases) will be identified from the EPA-supported medical testing and compared with those who participated in the medical screening but were not found to have any evidence of asbestos-related disease (controls). It is expected that approximately 150 cases and 300 controls will be interviewed to obtain additional information on opportunities for exposure, personal and family history, and other possible or potential risk factors.

4. Development of an ATSDR Asbestos Registry: Creation of an Asbestos Subregistry, as part of ATSDR's National Exposure Registry, would allow researchers to follow the health of asbestos-exposed individuals, and would provide health education materials for current and former residents of the Libby area. An Asbestos Subregistry also would provide valuable environmental and medical information for dose-reconstruction activities and investigation of new or unforeseen health outcomes. This activity could be broadened to include sites in other states with additional funds.

5. Enhancement of Local Medical Care: Upgrading of local hospital and community care resources will facilitate the quality of care being provided close to home for residents of the Libby area with illness. This will require support by federal, state, and local partners working together (including HRSA, other HHS agencies, and state health authorities). The cost of upgrading existing community and hospital facilities needs to be developed with key federal agencies. Additionally, participation in clinical research and clinical trials for treatment of disease related to exposure to tremolite asbestos can be initiated by HHS agencies (such as NCI) and coordinated with ATSDR.

FY 2001 and Beyond

1. Health Statistics Reviews: Health statistics reviews can be undertaken for populations surrounding a subset of sites that have processed vermiculite. Because of the variety of states that would be involved, it appears that mortality data would be the most readily available data for mesotheliomas, lung cancer, and noncancerous respiratory deaths, although cancer registries will be utilized where available and contacts with respiratory disease specialists will be sought. The exact location of these facilities, the industrial hygiene practices employed, and the amount of vermiculite processed will need to be determined. It is recommended that a pilot project be conducted on high-exposure sites thought to pose the greatest public health threat. Mapping of mesothelioma and other rare lung diseases should be considered as part of this pilot project. Depending on the outcome of this pilot project, additional sites could be investigated.

2. Medical Testing at Other Vermiculite Processing Facilities: It is not yet known whether persons who worked at or lived near other vermiculite facilities in the United States need to be tested. However, if significant disease is discovered among those tested in Libby, Montana, then testing for persons exposed at other processing facilities will be considered on the basis of EPA exposure assessments. Several steps would be necessary to complete this activity. First would be an evaluation of each facility that has processed vermiculite and a determination of its potential for exposure. This could be accomplished by working with NIOSH, EPA, and state and local health and environment departments to determine significant levels of exposure. This information could then be used to establish the facilities that pose the greatest health risk. Finally, a pilot medical testing program could be conducted at three sites for employees, family members, and others in ancillary occupations or with other significant exposures.

3. An Expanded Epidemiologic Study: An expanded epidemiologic study in areas located outside the City of Libby, Montana, may be conducted to measure the association between different personal characteristics and community exposures and the development of mesotheliomas and pulmonary disease. This study would formally test hypotheses that occupational or community exposure to vermiculite processing contributed to acquiring pulmonary disease (such as mesothelioma) and identify the most relevant routes of environmental exposure. This work would begin as an evaluation of cases, or a case-series study and could progress to a case-control study if appropriate. Working collaboratively with groups (such as the National Cancer Institute, the National Center for Health Statistics, and state health departments), persons with asbestos-related disease (case group) can be identified, along with an appropriate control group (persons who were not found to have an asbestos-related disease). This work would assist EPA and others in the identification of pathways of environmental exposure and therefore result in a better understanding of the development of these diseases.

4. Mesothelioma Surveillance: According to NCI about 30% of mesothelioma cases are of uncertain etiology and are not occupation related. NCI has performed surveillance activities on mesothelioma utilizing both mortality and cancer registry data and has been studying the prevalence of mesothelioma in selected geographic areas. ATSDR would work collaboratively with NCI and state cancer registries to identify cases of mesothelioma and would then extend the mesothelioma effort to geographic areas where vermiculite contaminated with tremolite asbestos is a potential problem. It is expected that state cancer registries will verify diagnoses using medical records and pathology specimens that could be made available to NCI and ATSDR. ATSDR will expand on this information by investigating environmental exposures to identify cases. This will be done by working collaboratively with NCI and EPA to develop a questionnaire that collects a work history specifically for exposure to vermiculite ore, in addition to known occupational hazards such as shipbuilding; environmental exposure data, including residential history, to look at proximity to vermiculite processing facilities; use of vermiculite insulation; and information on potential confounding factors (such as tobacco use). Currently unidentified sources (i.e., other than vermiculite) of asbestos exposure may be significant in certain geographic areas of the country.

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