Asbestos is a mixture of magnesium and iron silicates in fibrous form. It appears as dust in the form of fine fibres in the air. Asbestos enters the body by inhalation, and fine dust containing fibres of diameters less than 5 microns and lengths greater than 5 microns may be deposited in the alveoli. The fibres are insoluble. The dust deposited in the lungs causes fibrosis, pleural plaques, mesothelioma and lung cancer. Asbestosis results in impaired lung function after five to ten years. The symptoms are shortness of breath, chest pain, and later bronchitis with increased sputum and clubbing of the fingers. Other specific diseases associated with asbestos are; cancers of the bronchi, pleura and peritoneum and probably other organs; and asbestos corns of the skin. All these, with the exception of corns, are due to the inhalation of asbestos fibres and consequently any process which gives rise to large amounts of asbestos dust may constitute a health hazard.
Asbestos was first used in Finland about 2500 BC to strengthen clay pots. In classical times, the indestructible shrouds in which in the eminent were preserved were woven from asbestos (the word comes from the Greek meaning inextinguishable or indestructible) and it is still use for lamp wicks.
Occupational exposure occurs in asbestos mines and wherever asbestos or asbestos products are in use: for instance, in handling asbestos-cement products used in the building industry (roofing sheets, wallboard and pipes). Exposure may also occur in the textile industry in the manufacture of fireproof materials, such as asbestos clothes or brake linings for motor vehicles. There is increasing concern about water-borne asbestos in communities which have used asbestos-and-cement pipe to transmit water from reservoirs and wells. Asbestos is also used for insulation and fire protection purposes in ship-building, house-building and in the undersealing of cars, and as as a surface coating in acoustical applications.
From 1940 to 1980, some 21 million Americans were exposed to microscopic fibers of asbestos from insulation and other building materials. The fibers entered their lungs and, in a high proportion of cases, caused cancer. From that group, the best estimate was that in each year until the turn of the 20th Century, 8,000 to 10,000 people would die of asbestos disease. American manufactures were aware since the 1930's of the dangers to employees and customers but largely suppressed the knowledge. In the USA, for example, projections indicate that in the second half of this century, about 2 million workers exposed to asbestos will have died of from cancers it has caused. In the UK, it is estimated that as many as 500,000 workers will die from asbestos related disease over the next 30 years. In 1985, Martin Marietta, a major USA corporation, agreed to pay restitution charges to the employees and their families who were injured by asbestos inhalation resulting from their work. In 1994, a $1.5 billion court settlement was awarded to a class action lawsuit against Fibreboard Corporation, Oregon. The settlement established a fund devoted to future asbestos-related personal injury claims against the company.
In 2005, some 730,000 asbestos lawsuits were pending in U.S. courts and as many as 75,000 new cases are filed each year. More than 8,000 companies have defended themselves from asbestos claims, resulting in more than 73 asbestos-related bankruptcies since 1985.
Many in the construction industry believe that the US government has banned the use of asbestos. While certain limitations have been imposed, this by no means has eliminated the use of asbestos. In 1994, more than 800 million tonnes of asbestos were still being used annually in the USA, more than two thirds of its 3,000 uses being in construction, e.g. floor tiles, roofing materials, electrical insulation, corrosion-resistant coatings, heat-resistant materials and asbestos cement pipe and sheet. Even if asbestos were banned in the future, asbestos will be a continuing hazard in maintenance, remodelling and demolition.
Mining and manufacture of vermiculite (Zonolite) in Libby, Montana, USA for many more years escaped asbestos controls. Vermiculite was discovered to contain tremolite, a form of asbestos, in the 1980s, but company and government concealment of the issue meant that Libby ore was still processed and millions of buildings are still insulated with Zonolite. In 1970, the company skirted New York City regulations and supplied asbestos-contaminated vermiculite as fireproofing for the World Trade Center towers. After its destruction (11 September 2001), the EPA measured dangerously high levels of asbestos in lower Manhattan's air. The scandal only came to light in 1999. In total, more than 190 people have died due to mining operations in Libby and hundreds more have contracted terminal illnesses.
In 1991 the EEC/EU was obliged to abandon use of its major building in Brussels, the Berlaymont, in order to permit major work to remove the asbestos used in its construction. The building was declared free of asbestos in 1999, after around 12,000 tonnes of asbestos had been removed at an estimated cost of 5 billion BEF.
While industrialized countries are limiting use of asbestos, Third World nations such as Malaysia, Thailand and China are actually buying more because it is a cheap building material easily mixed with cement. Canada is the largest exporter and is actively promoting its use.
Asbestos water pipes, though banned in many countries of the world, are still used in India very widely.