Asbestos is the generic name for 6 different naturally-occurring fibrous minerals. A "fibre" is defined as a particle that is more than 5 micrometres (μm) in length and having a length to width ratio of at least 3:1. Many Canadian regulations further add that a fibre of asbestos must also be less than 3 μm wide.
Based on their physical and chemical properties, there are two major groups of asbestos: serpentine and amphibole.
Serpentine: Serpentine fibres are long, flexible and curved. These fibres can be woven together. The main type of serpentine asbestos is chrysotile (white asbestos), which is the main type of asbestos used in manufacturing.
Amphiobole: Amphibole fibres are straight and stiff. These fibres are generally brittle and rod- or needle-shaped, which limits their commercial usefulness. There are 5 sub-types of amphiobole asbestos, including:
This document is part of a series of documents on asbestos:
Asbestos occurs in large natural deposits, or as contaminants in other minerals. For example, tremolite asbestos may occur in deposits of chrysotile, vermiculite, and talc.
According to the American Geographical Society's Geographical Review in 1967, almost 40% of the world's asbestos production is concentrated in a narrow area in southern Quebec, known as the "Serpentine Belt".
Because it has heat-resistant and insulating properties, asbestos was used in a wide range of manufactured products.
Asbestos was used for:
All forms of asbestos are resistant to heat, fire, chemical, and biological break-down. Asbestos does not dissolve in water or evaporate. These properties mean that asbestos fibres do not burn, do not undergo significant reactions with most chemicals, and do not break down significantly in the environment. Other properties of asbestos that made it so commercially desirable include its wear and friction characteristics, its tensile strength, its heat, electrical and sound insulation capabilities, and its adsorption capacity. With these properties, asbestos was useful in a wide range of manufactured products such as building materials, friction products, and heat-resistant fabrics.
Asbestos is a friable material which means that when it is dry, it can be crumbled, pulverized or powdered. Small fibres and clumps of fibres may be released into the air as dust. Inhaling asbestos during its manufacturing or use is the main health concern.
The human health effects from long-term asbestos exposure are well documented, including asbestosis and changes in the lining of the lungs (pleural abnormalities). Both chrysotile and the amphibole forms of asbestos have been shown to cause lung cancer and mesothelioma.
Asbestos has been banned entirely in 39 countries since 1983, including the European Union, Argentina, Australia, Chile, Croatia and Saudi Arabia. Other countries are either severely restricting its use or phasing it out it out over a specified period of time. All new uses of asbestos were banned in the US by the Environmental Protection Agency (EPA) in July 1989.
In Canada, the use of asbestos has declined since the mid-1970s and early 1980s. Products containing asbestos are regulated by the Asbestos Products Regulation (SOR 2007/260).
In Canadian workplaces, the WHMIS(Workplace Hazardous Materials Information System) classification for asbestos is "D2A - Poisonous and infectious material - Other effects - Very toxic". This class includes compounds that can cause cancer.
Asbestos is also listed as carcinogenic by:
Document last updated on January 18, 2012