NIOSH Research in Libby, Montana: Job-Related Asbestos Exposures and Health Effects in Mining and Milling of Vermiculite

September 21, 2000

Concerns have been voiced about occupational and potential public health risks from exposure to vermiculite contaminated with asbestos, including potential risks to former miners and to residents of Libby, Montana, and to workers and consumers who come in contact with vermiculite end-products, such as insulation and potting soil. The National Institute for Occupational Safety and Health (NIOSH) has responded to past and current concerns by conducting needed research and disseminating its findings.

Conducting Research and Providing Results to Workers in Libby

In the 1980s, NIOSH conducted research about job-related exposures and health effects among workers employed in mining and milling vermiculite in Libby. As is customary, NIOSH shared its findings with workers, their representatives, and the employer. We also made the results publicly available to the scientific and public health community.

• Our studies identified asbestos contamination in the vermiculite mined and milled in Libby.
• We also determined, from examination of X-rays from Libby miners, that the miners showed evidence of adverse health effects associated with asbestos exposure.
• Further, in a study involving review of death certificates of former Libby vermiculite miners, we identified an excess of deaths from lung cancer and other lung diseases consistent with exposure to asbestos.
• We made our results available in 1985 through meetings in Libby with workers and their representatives, employer representatives, and members of the community. We also published the findings in three articles in the American Journal of Industrial Medicine, a peer-reviewed scientific journal, in 1987, and in articles published in1988 in a supplement to the Annals of Occupational Hygiene, a British scientific journal. NIOSH further disseminated information about health effects related to vermiculite mined and milled in Libby, in a comprehensive 1986 text, Occupational Respiratory Diseases.

Further Occupational Health Research on Vermiculite

Currently, NIOSH is planning new research to help determine the distribution and concentration of asbestos contamination in vermiculite produced by various mines and used in different occupational settings. Through carefully designed sampling, we will be better able to define the extent of potential occupational exposure. We are also assessing other options for possible research. Pending further research, would be prudent to handle vermiculite with caution.

Technical Assistance for Libby Community Response

NIOSH has been providing technical assistance to the U.S. Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry, which are the lead agencies for the Federal government in assessing current concerns about potential community health risks from asbestos exposures in Libby. In addition, we are co-sponsoring the September 21-23, 2000, community conference in Libby on public health and asbestos.