Vermiculite and Gardening Use
En Español (Spanish): Vermiculita y su uso en jardines (PDF: 46KB/1 page)
Vermiculite is a naturally occurring mineral compound that expands when wet. A member of the phyllosilicate group of minerals, it resembles mica in appearance. In its pure form, vermiculite is clean, odorless, nontoxic and sterile. Recent findings about vermiculite ore contaminated with tremolite asbestos have caused concern over possible health effects for workers who had long-term contact.
For asbestos to cause harmful health effects, it must be present as a tiny fiber that could be inhaled or ingested. When disturbed, asbestos breaks down into fibers 1,200 times thinner than a human hair. If these fibers are inhaled, they become trapped in lung tissue and cause scarring. Asbestos fibers can cause a number of lung diseases, including cancer.
Not all vermiculite products contain asbestos, but some do. An EPA study showed some vermiculite products contain low levels of asbestos. Asbestos is found primarily in the unmixed vermiculite product although some was found in pre-mixed potting soils. For consumers using vermiculite on an infrequent basis the health risk is low. Greenhouse workers in daily contact incur a higher level of risk.
The health risk to home gardeners from infrequent contact with vermiculite is low. Nevertheless, it is prudent to take a few simple precautions.
- Use premixed potting soil. It normally contains more moisture and less vermiculite and reduces the amount of asbestos-laden dust.
- Keep vermiculite moist while using to minimize dust and possible asbestos fibers in the air. As with any dust, breathing in large amounts of particles can cause nose and throat irritation.
- Handle the material outdoors or in a well-ventilated area.
- Avoid bringing dust into the house on clothing or shoes.
- Try alternatives such as peat, sawdust, perlite or bark.
For more information, please contact the Site Assessment and Consultation Unit: Contact Us
This information sheet was prepared in cooperation with the Agency for Toxic Substances and Disease Registry.
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