asbestos

Any of several related minerals of fibrous structure that offer great heat resistance because of their nonflammability and poor conductivity. Commercial asbestos is generally either made from serpentine (‘white’ asbestos) or from sodium iron silicate (‘blue’ asbestos). The fibres are woven together or bound by an inert material. Over time the fibres can work loose and, because they are small enough to float freely in the air or be inhaled, asbestos usage is now strictly controlled; exposure to its dust can cause cancer.

Asbestos has been used for brake linings, suits for fire fighters and astronauts, insulation of electric wires in furnaces, and fireproof materials for the building industry. Exposure to asbestos is a recognized cause of industrial cancer (mesothelioma), especially in the ‘blue’ form (from South Africa), rather than the more common ‘white’. In 2001 there were 30,000 new cases of asbestos-related cancer in industrialized countries. Asbestos dust can also cause asbestosis, a chronic lung inflammation. There are severe restrictions around the world on the production and use of asbestos, and on the methods by which it is removed from existing installations.