Health Canada is advising Canadians that vermiculite insulation may contain asbestos. It can be harmful if disturbed during maintenance, renovation or demolition work. However, there is nothing to indicate that it is harmful if it remains sealed behind wall panels or parquet flooring, in the attic or kept away from the indoor environment.
The best way to reduce the risk of asbestos exposure is to avoid stirring the insulation. If it is sealed and can not get into the air or the environment, the risk is minimal. If you think you have been exposed to asbestos and are worried about it, talk to your doctor or a health professional.
Vermiculite from the Libby mine in Montana (USA) from the 1920s to the 1990s can contain asbestos. This mine supplied most world markets, particularly under the name Zonolite. This insulation has been little used since the mid-1980s and has not been sold in Canada for a decade. Vermiculite insulation produced before 1990 does not necessarily contain asbestos. However, to avoid any danger and until proven otherwise, it is reasonable to assume that vermiculite insulation manufactured before 1990 may contain asbestos.
Asbestos compromises health only when its fibers get into the air you breathe. Breathing asbestos fibers can cause asbestosis (scar tissue that forms in the lungs and impede breathing), mesothelioma (a rare form of cancer of the pleura or abdominal cavity) and lung cancer. Asbestos diseases generally result from frequent and prolonged exposure that can extend over several decades.
Based on current data, there is no evidence that vermiculite for horticultural purposes (potting) is harmful when used as directed.
If vermiculite is present, an analysis of vermiculite is recommended to verify if it contains asbestos.