In recent years, many steps have been taken to remove asbestos from buildings and commercial products in an effort to reduce human exposure which leads to asbestos related disease, notably asbestosis. Asbestos however, is still a relevant hazard today, found in a number of different forms.
It still exists in hundreds of older products as well as in trace amounts in newly manufactured products. Among new products that may still contain asbestos are soil retention enhancers, particularly vermiculite.
Vermiculite is a mica-like mineral mined around the world and used in a variety of commercial and consumer products because it is fire-resistant and has good insulation qualities.
Today, most vermiculite is safe. However, that is not to say it cannot contain asbestos. Vermiculite which is accompanied by a great deal of dust likely has residual asbestos in its contents and should be used with caution. Current regulations ban products which contain 1% or more asbestos. Unfortunately even products containing less that 1% asbestos are still extremely hazardous, particularly when in loose dust form as vermiculite often is manufactured.
During the 1920s and 1930s, when asbestos awareness was practically nonexistent, the Libby Mine in Montana, Canada, produced Zonolite® Attic Insulation – and possibly other brands which may have contained amphibole asbestos – to supply the majority of the world market in vermiculite-based insulation.
Hundreds of the Libby mine’s employees and residents of the town were diagnosed with mesothelioma, an aggressive cancer that is known only to be caused by asbestos exposure and many of these residents were able to secure financial compensation for their families through litigation.
Mesothelioma incidence is also known to be high in commercial gardeners and other occupations which deal with large amounts of loose vermiculite. Note the appearance of the vermiculite. If it seems to carry a great deal of residual dust, dispose of it outdoors. Read the label as most manufacturers of vermiculite mark their products packaging with “Non Dusty” labels.
Based on current information, there is no evidence that vermiculite currently available for horticultural purposes (e.g. potting plants) is a health risk when used as directed.
Not all vermiculite produced before 1990 contains amphibole asbestos fibres. However, to be safe and in the absence of evidence to the contrary, it is reasonable to assume that if your building has older vermiculite-based insulation, it may contain some amphibole asbestos.
These products can cause health risks if disturbed during maintenance, renovation or demolition. However, there is currently no evidence of risk to your health if the insulation is sealed behind wallboards and floorboards, isolated in an attic, or otherwise kept from exposure to the interior environment.