Vermiculite and Asbestos
Continued from: About Asbestos
Vermiculite is a naturally occurring, safe mineral that has been widely used for over 80 years in the insulation, construction, horticulture and agriculture industries. It has an appearance similar to mica and has a unique exfoliation property; that is, it expands to many times its original volume when it is heated. Its most familiar form is the white particles that appear in potting soil. This substance is plentiful worldwide and is mined on almost every continent. The most productive mines are located in the Palabora region of South Africa, the northwestern corner of China and in the eastern Appalachian range of Virginia and South Carolina.
Although asbestos is not intrinsic to vermiculite, some sources of vermiculite do contain a substantial portion of asbestos. Asbestos exposure creates a risk of malignant mesothelioma or asbestosis. Specifically, vermiculite from the mines in Libby, Montana, contains tremolite asbestos. The Libby, Montana, mines were closed in 1990 due to health hazards related to asbestos exposure. Almost all of the vermiculite mined today comes from deposits that are geologically older (1.5 to 3 billion years) than those of Libby, Montana (225 million years).
Vermiculite Media Reports
Although a number of media outlets have cast doubt on the safety of vermiculite including McCall's Magazine, National Public Radio, Newsweek and 20/20 inspections show that current processing and use of this mineral is safe. For example, The Schundler Company, which is the largest processor of vermiculite, was inspected by the United States Environmental Protection Agency in 2000. The vermiculite was found to contain no asbestos during this inspection.
Any vermiculite that was mined and used in construction and insulation prior to the closing of the mines in Libby could conceivably contain asbestos. It is best if these materials are not disturbed, so as not to create any asbestos dust that could be inhaled. In cases where asbestos-containing vermiculite must be removed, standard hazardous material handling protocols should be used. Before removing and destroying any construction materials, it is best to have them tested for asbestos.
Researchers have evaluated the potential exposure to asbestos caused by the use of or exposure to vermiculite. They have not, however, provided any statistical evaluation of the risk of asbestosis, mesothelioma or lung cancer related to vermiculite exposure.
[Page updated May 2006]