Asbestos: A ubiquitous natural resource
The word asbestos refers to several types of fibrous minerals. In its natural state, asbestos occurs throughout much of the planet: indeed, it is found in two-thirds of the rocks in the earth's crust. The fibres are released by erosion and carried by the wind; thus, depending on where you live, you are most likely inhaling between 10,000 and 15,000 fibres a day.

A study of the European communities shows that natural sources of asbestos release more fibres into the air than industrial sources do (extraction and use). Water also contains asbestos: anywhere from 200,000 to 2,000,000 fibres per litre. In the regions of Québec where the world's largest asbestos mines are located, the drinking water contains up to 170 million fibres per litre! However, this is nothing to be alarmed about: asbestos is harmless in water, as the problem is not ingesting the fibres, but inhaling them.

Researchers have identified three diseases which are associated with the inhalation of the various types of asbestos fibre: asbestosis, which is a form of fibrosis; lung cancer; and mesothelioma of the pleura or the peritoneum, a very rare form of cancer.

Distinguishing between types of asbestos
There is not one but MANY different types of asbestos fibre, divided into two main categories: amphibole and serpentine asbestos.

• The amphibole fibres used commercially (amosite, crocidolite) are extremely hazardous. Because of their chemical structure and straight, needlelike fibres, amphiboles are very dusty, as well as highly biopersistent. Once in the human body, they can remain indefinitely in the lung tissue, and may cause cancer and mesothelioma.
• Chrysotile, the most common serpentine fibre, is considerably less hazardous than ampibole varieties. Silky in texture, with curly fibres, serpentine asbestos is unlikely to remain suspended in the air. Thus, less of it is inhaled, and it does not stay in the lungs very long. The human immune system can eliminate these fibres fairly quickly. The Health & Safety Executive (HSE) of Great Britain recently concluded that, like asbestosis, the appearance of lung cancer linked to chrysotile is a threshold phenomenon, meaning that there is an exposure level below which the health risk, if any, is so low as to be undetectable. Moreover, the HSE confirms that very few cases of mesothelioma are attributable to chrysotile, despite extensive exposure of thousands of workers in the past.

Today, asbestos means chrysotile
What you need to know is that 99% of the world's current asbestos production is chrysotile, a fibre which, when inhaled in small quantities, poses no health threat. Indeed, the controversy surrounding asbestos concerns fibres and products that were used in the past ­ often improperly ­ and which are prohibited today.

What is chrysotile used for today?
Up until the 1970s, some 3,000 products were made with asbestos fibres of all types. These included toasters, dryers, ironing boards and low-density friable insulation products. Today, some sixty countries still use asbestos, but only the chrysotile variety and primarily in cement building materials such as roofing materials, cladding and pipe. These building products account for 90% of the chrysotile used today. Friction products represent another 7% of the chrysotile fibre used, while couplings, a few plastics, and other miscellaneous applications account for the remaining 3%. All of these high-density products, in which the chrysotile fibre is encased in a matrix of either cement or resin, do not present risks of any significance to the general public under normal conditions and use.

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