Most people, hearing the word ‘asbestos’, think of floor or roofing tiles, or the gray stuff wrapped around pipes on older boilers. Few realize that vermiculite, a common soil conditioner used by indoor and outdoor gardeners alike, may contain asbestos as well.
It comes in the form of vermiculite, a soil additive mined from natural basaltic deposits, primarily in South Africa, China and Brazil. These deposits, formed over millions of years and altered by the weathering of water and changing temperatures, convert a mineral called diopside into asbestos. Although not all vermiculite contains asbestos, and both regulators and manufacturers are now testing vermiculite products for asbestos content, some products made before 1995 may still contain dangerous levels of asbestos.
This is what happened at the Libby, Montana mine, currently owned by W.R. Grace Company. The mine, operating since the 1920s, had no way to measure asbestos releases until after purchased by Grace in 1963, when monitoring equipment was installed.
Even then, knowing the presence of asbestos, W.R. Grace continued to operate the mine until 1990, endangering the lives of miners and their families in the process. This intentional cover-up, reported by the Salt Lake Tribune on December 3, 2006, cites the instance of asbestos-containing vermiculite as it relates to a grand jury indictment which cited W.R. Grace’s failure to report asbestos to the Environmental Protection Agency (EPA), The U.S. Dept. of Labor’s Occupational Safety and Health Administration (OSHA), or the miners themselves, who continued to work without proper safety equipment.
The 2005 indictment, by a federal grand jury in Montana, charged W.R. Grace and seven current and former executives for knowingly putting the residents of Libby, Montana in danger by concealing information about the presence of, and health effects from, its mining operations. It also cited W.R. Grace and its executives with intentionally obstructing EPA efforts at remediation.
More than 200 Libby, Montana residents have died as a result of these mining operations. Twelve hundred more are suffering from some form of asbestos-related abnormality, including many who were never directly involved in the mining operations at Zonolite Mountain.
Though asbestos use in manufacturing has declined significantly in recent decades, some still exists in hundreds of older products kept on gardening shelves in garages in and greenhouses. It also crops up in small amounts in newly manufactured products that escape the monitoring parameters of industry and government.
If you are using vermiculite to condition soil, be aware that stored bags will likely contain higher proportions of asbestos. Even newer bags that seem to incorporate large quantities of dust alongside the vermiculite pellets may have residual asbestos and should be used with caution, or discarded. The current EPA standard, of one percent or less of asbestos, is not a guarantee of safety, as even minute portions of asbestos can – with long exposures – lead to asbestosis and malignant mesothelioma, a lethal form of cancer whose incidence is known to be higher among commercial gardeners.
You can avoid the hazards by selecting containers of vermiculite labeled ‘non-dusty’. This form of vermiculite is more expensive in the short term, but may save you the cost of debilitating illness in the long term. You can also wear appropriate equipment (face mask, full body hazmat suit and gloves) if you are employed as a seasonal greenhouse worker. Do not take the garments home for cleaning, as this exposes your family, or those sharing laundry facilities, to similar dangers. If in doubt about your rights, contact OSHA.