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     Vermiculite Insulation and Asbestos

Vermiculite is a mineral used in many commercial and consumer products including insulation. Vermiculite itself has not been shown to pose health problems. However, some vermiculite insulation can contain asbestos fibres.

Of concern is Zonolite, a product made from vermiculite which was used in many Canadian homes. The vermiculite insulation sold in Canada under the name of Zonolite was extracted from the Libby Mine in Montana, USA. This mine had a natural deposit of asbestos which resulted in the vermiculite being contaminated with asbestos.

Vermiculite produced by the Libby Mine has not been on the market in Canada for more than 10 years. Not all vermiculite sold in Canada before 1990 contains asbestos fibres. However, if you believe that your home may contain vermiculite insulation, it is reasonable to assume that it may be contaminated with asbestos.

Asbestos can cause health problems when inhaled into the lungs. Exposure to asbestos fibres has been associated with asbestosis, mesothelioma and lung cancer.

Asbestosis - Asbestosis is a disease of the lungs produced by inhalation of asbestos fibres. It is a chronic disease with slow onset that usually requires several years of exposure. The development and progression of asbestosis varies from individual to individual. It is often slow with little changes over five, ten or more years. Many cases do not progress after diagnosis. It may, however, be quicker in some individuals than in others due to different conditions of past dust exposure. Asbestosis is characterized by pulmonary fibrosis. Shortness of breath is the most common presenting symptom. In most cases, the first and often the only physical sign is crackles, also known as rales, usually detected near the end of a full inspiration. Chest x-rays reveal small irregular opacities commonly distributed in the middle and lower lung fields. Lung function tests can help to quantify the level of pulmonary dysfunction.

Mesothelioma - Mesothelioma is a cancer of the pleural and peritoneal cells (lining of the lung and abdominal cavity). The site of this tumor might be the lung (pleural) or the abdomen (peritoneal). Patients with pleural mesothelioma experience chest and shoulder pain; dry cough is frequent. With the progression of the tumor, weight loss, weakness, and fever may occur. The time between the initial exposure to asbestos and the clinical manifestation of the disease(latency) is difficult to define but for mesothelioma is quite wide, rarely less than 10 years from the time of the first exposure and it may occur even after 40 years. As a result, the age at which a person was first exposed to asbestos is very important for determining the risk of contracting mesothelioma. The effect of latency is that any daily observation of asbestos-related disease is the result of past exposures.

Lung Cancer - Asbestos is a well-known substance that can cause lung cancer. Lung cancer takes many years to develop, but changes in the lung can begin almost as soon as a person is exposed to asbestos. Lung cancer usually does not cause symptoms in the early stages. When symptoms occur the cancer is often advanced. Symptoms of lung cancer include chronic cough, weight loss, shortness of breath, fever, and chest pain. These symptoms are also common with other lung disorders, therefore to confirm the diagnosis it is necessary to carry out laboratory tests including chest x-ray.

The best way to minimize asbestos exposure from vermiculite is to avoid removing or disturbing the insulation. The following precautions will prevent releasing asbestos fibres into the air:

  • Do not use the attic for storage.

  • You and your children should not go to the attic.

  • If you plan to renovate, hire a professional trained and certified to handle asbestos.

  • You should never attempt to remove the insulation yourself.

  • Seal all cracks and holes in the ceilings to prevent insulation to sift through.

For further information please see the following links:

Health Canada Information

Other Government of Canada Information

Other Information


April 2004


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