Asbestos
Asbestos is a generic term for six naturally-occurring fibrous minerals: chrysotile, amosite, crocidolite, anthophyllite, tremolite, and actinolite. Chrysotile, a fibrous form of serpentine, is the most common type of asbestos, followed by amosite and crocidolite. Asbestos has been mined in China, Italy, Russia, South Africa, the United States, and Zimbabwe. The largest known deposit of asbestos is found in Quebec; Canada produces 40 percent of the world's supply of fibrous minerals.
Asbestos has many useful properties. It is highly resistant to chemical corrosives and heat, has high tensile strength, and is a good nonconductor of electricity. Its hollow fibers make asbestos an excellent insulator. It is flexible and inflammable. Some types of asbestos occur in long fibers which may be spun into pure mineral yarns; shorter-fibered grades of asbestos may be blended with such materials as cotton or glass wool, and "nonspinning" asbestos, grades with fibers too short to be spun or blended, are mixed with binding agents and molded into sheets.
Asbestos was first used by the Romans over two thousand years ago to make lamp wicks and fireproof cremation shrouds. Asbestos was first introduced in the United States by Henry Johns in 1858 as the main ingredient in his fireproof roofing material. Asbestos cloth became widely used in fireproof clothing and insulating fabric for such applications as automobile brake linings and clutch facings, where high temperatures would damage other materials. Asbestos cloth has also been used as insulation for electrical cables. Molded asbestos has been used to make a variety of fireproof building materials, including floor tiling, paints, roofing shingles, boiler and pipe insulation, and wallboard. By the 1930s asbestos could be found in everything from draperies to designer coats and modeling clay.
Asbestos fibers are small enough to become airborne and be inhaled or ingested. The fibers are resistant to the body's efforts to remove them; asbestos punctures the air sacs in human lungs and accumulates over time, reducing the tissues' elasticity and decreasing their ability to exchange oxygen. This condition is known as asbestosis. The first recorded case of asbestosis in asbestos workers was reported in the 1890s by Dr. Montague Murray of England. Asbestos has also been associated with lung cancer and a rare cancer of the stomach and abdominal linings called mesothelioma. Because of these potential health hazards, asbestos is being replaced in areas where it is considered to present an imminent danger, such as in public schools. The process of replacing asbestos with safer materials is termed asbestos abatement.
While scientists continue to research the hazards of asbestos exposure, litigation against asbestos manufacturers has increased dramatically. For example, in 1995 alone a series of lawsuits were launched against manufacturers such as Goodyear Tire and Rubber and B.F. Goodrich by a group of merchant marines who claim they suffer medical conditions resulting from exposure to asbestos used on engine casings on ships built between World War Two and 1977. Also in 1995 a UK court ordered an asbestos firm, T and N PLC, to settle with an individual who a contracted mesothelioma while living close to an asbestos processing facility. On the other hand, in the U.S. in 1996, a $1.3 billion dollar class action settlement brought forth by 250,000 people against 20 different asbestos manufacturers was nullified by a federal appeals court.
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