Vermiculite Insulation

The Issue

Some vermiculite insulation may contain amphibole asbestos fibers. 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.

Background

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. Of concern is vermiculite ore produced by the Libby Mine in Montana from the 1920's to 1990. It was sold as Zonolite® Attic Insulation and possibly other brands in Canada during that time. Vermiculite from the Libby Mine may contain amphibole asbestos. The Libby Mine supplied the majority of the world market in vermiculite-based insulation.

Products made from vermiculite ore produced by the Libby Mine were not widely used after the mid-1980's and have not been on the market in Canada since 1990. Not all vermiculite produced before 1990 contains amphibole asbestos fibers. 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.

Asbestos is the generic name for a variety of fibrous minerals found naturally in rock formations around the world. Because asbestos fibers are strong, durable and non-combustible, they were widely used by industry, mainly in construction and friction materials. Commercial asbestos fibers belong in two broad mineralogical groups: serpentine (chrysotile) and amphibole (tremolite, actinolyte and others).

  • Amphibole asbestos often contains more iron and resists acid and extremely high temperatures. Because of this, it has been heavily used in industrial furnaces and heating systems. However when inhaled, amphibole fibres stay much longer in the lungs than chrysotile fibers and they are more likely to inflict damage and cause disease, including cancer. Accordingly, amphibole asbestos has been drastically controlled and largely replaced.

  • Chrysotile is the only serpentine asbestos that is found in almost all asbestos-based products available today and is the main form of asbestos still mined. Chrysotile is different from the amphiboles both structurally and chemically. It is generally accepted that chrysotile asbestos is less potent and does less damage to the lungs than the amphiboles.

How much asbestos is in a product does not indicate its health risk. If the asbestos fibres are enclosed or tightly bound in a compound, there is no significant health risk. One of the main problems with asbestos came from sprayed or "friable" (easily broken up) amphibole asbestos used in buildings until the 1970s.

The Health Risks Of Vermiculite Containing Amphibole Asbestos

Although the overall percentages of amphibole asbestos in bulk vermiculite are very low, the airborne percentages can increase if the material is disturbed. Asbestos poses health risks only when fibers are present in the air that people breathe. If asbestos fibers are enclosed or tightly bound in a product, for example in asbestos siding or asbestos floor tiles, there are no significant health risks. How exposure to asbestos can affect you depends on:

  • The concentration of asbestos fibers in the air;

    •

  • How long the exposure lasted;

  • How often you were exposed;

  • The size of the asbestos fibers inhaled; and

    •

  • The amount of time since the initial exposure.

When inhaled in significant quantities, asbestos fibers can cause asbestosis (a scarring of the lungs which makes breathing difficult), mesothelioma (a rare cancer of the lining of the chest or abdominal cavity) and lung cancer. The link between exposure to asbestos and other types of cancers is less clear. 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.

Minimizing Your Risk

The best way to minimize your risk of amphibole asbestos exposure is to avoid disturbing vermiculite-based insulation in any way. If vermiculite-based insulation is contained and not exposed to the home or interior environment, it poses very little risk.

If you know you have vermiculite-based insulation in your attic, take these precautionary steps.

  • Do not allow children to play in an attic with open areas of vermiculite-based insulation and make sure anyone working in the attic knows about the possible presence of amphibole asbestos.

  • Do not use the attic for storage if retrieving items from it may disturb the insulation.

  • If you must go into the attic, walk on boards in order to minimize disturbance of the insulation and use an appropriate respirator mask. Do not remain in the attic any longer than is necessary.

  • Common dust masks are not effective against asbestos fibres.

  • If you have vermiculite-based insulation and you decide to have it removed, speak to trained and qualified asbestos removal professionals to handle the insulation removal. They can be found by looking up experts in "asbestos abatement /removal." never attempt to remove the insulation yourself.

  • If you plan to remodel or renovate in a manner that would disturb the vermiculite, speak to professionals who are trained and qualified to handle asbestos removal before proceeding with the work to be done.

    •

  • Seal all cracks and holes in the ceilings of the rooms below the insulation (for example, apply caulking around light fixtures and the attic hatch) to prevent insulation sifting through.

If you suspect you have vermiculite-based insulation in your walls, as a precautionary step, seal all cracks and holes. For example, apply caulking around window and door frames, along baseboards and around electrical outlets.

Buildings And Homes

Because it is a valuable reinforcing, insulating and fire-proofing material, asbestos was used widely in construction materials such as insulation board, asbestos cement, and floor and ceiling tiles. These products are very dense and do not release significant amounts of fibers under normal use. However, fibers may be released if these products are cut or damaged.

Asbestos fiber concentrations in the air in buildings are usually about the same as in the air outside, and are not a significant risk. However, levels may be higher if friable asbestos materials are disturbed. There is also concern about vermiculite insulation which may contain small amounts of amphibole asbestos, principally tremolite or actinolite. These amphibole fibers may cause health risks if disturbed.

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 home or interior environment.

When Can Asbestos Be A Problem In The Home?

Today, far fewer products in the home contain asbestos. Current products that do contain the material are better made to withstand wear and use. However, frequent or prolonged exposure to asbestos fibers may still bring health risks. This can happen with the release of fibers into the air when asbestos-containing products break down, either through deterioration as they age or when they are cut. People can put themselves at risk—often without realizing it—if they do not take proper precautions when repairs or renovations disturb asbestos-containing materials. This can occur in a number of situations:

  • Disturbing loose-fill vermiculite insulation which may contain asbestos.

  • Removing deteriorating roofing shingles and siding containing asbestos, or tampering with roofing felt that contains asbestos.

  • Ripping away old asbestos insulation from around a hot water tank.

  • Sanding or scraping vinyl asbestos floor tiles.

  • Breaking apart acoustical ceilings tiles containing asbestos.

  • Sanding plaster containing asbestos, or sanding or disturbing acoustical plaster that gives ceilings and walls a soft, textured look.

  • Sanding or scraping older water based asbestos coatings such as roofing compounds, spackling, sealants, paint, putty, caulking or drywall.

  • Sawing, drilling or smoothing rough edges of new or old asbestos materials.

 

How To Minimize The Asbestos Risks In The Home

If you do not know if products in your home contain asbestos, have an experienced contractor inspect them. If there is asbestos, the best interim measure (unless the product is peeling or deteriorating) is to seal the surface temporarily so that fibres will not be released into indoor air. If the product is already protected or isolated, simply leave it alone. It is a complex and expensive matter to remove asbestos, and should be done by an experienced contractor.

 

The Health Risks of Asbestos

Asbestos poses health risks only when fibers are present in the air that people breathe. How exposure to asbestos can affect you depends on:

 

  • The concentration of asbestos fibers in the air.

  • How long the exposure lasted.

  • How often you were exposed.

  • The size of the asbestos fibers inhaled.

  • The amount of time since the initial exposure.

When inhaled in significant quantities, asbestos fibers can cause asbestosis (a scarring of the lungs which makes breathing difficult),  mesothelioma (a rare cancer of the lining of the chest or abdominal cavity) and lung cancer. The link between exposure to asbestos and other types of cancers is less clear. Smoking, combined with inhaled asbestos, greatly increases the risk of lung cancer.