Vermiculite is a silver-gold to gray-brown mineral that is flat and shiny in its natural state. When heated to about 1000 degrees C, it appears (or swells) which creates air pockets. This expanded form, and the fact that vermiculite does not burn, makes the material suitable for use as insulation.

Is all vermiculite a health problem?

Vermiculite itself has not been shown to be a health problem. However, some vermiculite insulation contained asbestos fibers, which can cause problems if inhaled. As long as this type of vermiculite-based insulation does not get out of whack behind intact walls or in attics and does not fly away, this should not be a problem.

Zonolite® Attic Insulation is a matter of concern; This insulation was sold in Canada under the name Zonolite® and was extracted from the Libby mine in Montana, USA. This mine had a natural asbestos deposit that resulted in the contamination of vermiculite with asbestos.

The 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 your home may contain vermiculite insulation, it is reasonable to assume that it may be contaminated with asbestos.

What are the health risks of asbestos-containing vermiculite?

  • Asbestos can cause health problems when inhaled into the lungs. Inhalation of very small airborne asbestos fibres has been linked to diseases such as asbestosis, mesothelioma and lung cancer. (See OSH Answers webpage How do particles enter the respiratory system? To find out how small particles should enter the lungs.)
  • Asbestosis – Asbestosis is a lung disease that occurs when asbestos fibers are inhaled. It is a chronic, slow-onset disease that usually requires several years of exposure. The development and progression of asbestosis varies from individual to individual. It is often slow with small changes over five, ten years or more. Many cases do not progress after diagnosis. It may, however, be faster in some people than in others due to different conditions of previous exposure to dust. Asbestosis is characterized by pulmonary fibrosis (formation of scar tissue). Shortness of breath is the most common symptom. In most cases, the first and often the only physical sign is “crackling” – sounds that can be heard through a stethoscope. Also known as “rails”, they are usually detected towards the end of a full inhale. Chest X-rays show small irregular opacities (spots in opaque X-ray films or when X-rays cannot “see” through tissues). These are usually found in the middle and lower lungs. Lung function tests can help determine the severity of the disease.
  • Mesothelioma – Mesothelioma is a cancer of pleural and peritoneal cells (wall of the lung and abdominal cavity). The site of this tumour could be the lung (pleural) or abdomen (peritoneal). Patients with pleural mesothelioma experience chest and shoulder pain and a dry cough is common. As the cancer progresses and the tumor grows, weight loss, weakness and fever may also occur. The time between initial exposure to asbestos and clinical signs of the disease (latency) is difficult to define because for mesothelioma, the scope is quite wide and the disease is rarely observed less than 10 years after the first exposure. even after 40 years.
  • Lung cancer – Asbestos can cause lung cancer. Lung cancer takes many years to develop, but changes in the lungs 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 appear, 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, so to confirm the diagnosis it is necessary to perform laboratory tests, including chest x-ray.

How can we minimize the risk?

The best way to minimize asbestos exposure from vermiculite is NOT to remove or disturb the insulation. If you move the vermiculite, the fibers will be suspended in the air. The following precautions will prevent the release of asbestos fibers into the air:

  • Do not use the attic for storage.
  • No one should go into the attic.
  • If you plan to renovate, hire a professional who is trained and certified to handle asbestos.
  • Never remove the insulation yourself.
  • Seal all cracks and holes in ceilings to prevent insulation from passing through.
  • Caulk light fixtures and attic access to prevent grave insulation
  • It is possible for insulation to fall inside the walls. Caulk window and door frames, along skirting boards and around power outlets.

Where can I get more information?

For more information, visit the Government of Canada’s Health Webpage on Health.