Case study - What is asbestos?
Asbestos is the name for a group of naturally occurring silicate minerals that can be separated into fibers. The fibers are strong, durable, and resistant to heat and fire. They are also long, thin and flexible, so that they can even be woven into cloth.
Because of these qualities, asbestos has been used in thousands of consumer, industrial, maritime, automotive, scientific and building products. During the twentieth century, some 30 million tons of asbestos were used in industrial sites, homes, schools, shipyards and commercial buildings in the United States.
There are several types of asbestos fibers, of which three have been used for commercial applications: (1) Chrysotile, or white asbestos, comes mainly from Canada, and has been very widely used in the US. It is white-gray in color and found in serpentine rock. (2) Amosite, or brown asbestos, comes from southern Africa. (3) Crocidolite, or blue asbestos, comes from southern Africa and Australia. Amosite and crocidolite are called amphiboles. This term refers to the nature of their geologic formation.
Other asbestos fibers that have not been used commercially are tremolite, actinolite and anthophyllite, although they are sometimes contaminants in asbestos-containing products. It should be noted that there are non-fibrous, or non-asbestiform, variants of tremolite, anthophylite and actinolite, which do not have the adverse health consequences that result from exposure to commercial forms of asbestos.
What are asbestos-containing products?
What is common to many asbestos-containing products is that they were (are) used to contain heat (i.e. thermal insulation.) It is impossible to list all of the products that have, at one time or another, contained asbestos. Some of the more common asbestos-containing products are pipe-covering, insulating cement, insulating block, asbestos cloth, gaskets, packing materials, thermal seals, refractory and boiler insulation materials, transite board, asbestos cement pipe, fireproofing spray, joint compound, vinyl floor tile, ceiling tile, mastics, adhesives, coatings, acoustical textures, duct insulation for heating, ventilation and air conditioning (HVAC) systems, roofing products, insulated electrical wire and panels, and brake and clutch assemblies. Some of these products contained a very high proportion of asbestos, while others contained small amounts.
Why is asbestos still a problem?
Asbestos is still a problem because a great deal of it has been used in the United States and elsewhere, because many asbestos-containing products remain in buildings, ships, industrial facilities and other environments where the fibers can become airborne, and because of the serious human health hazards of inhaling asbestos fibers.
Many Americans believe that use of asbestos in products was banned years ago. The fact is that asbestos-containing products are still being imported and sold in this country, continuing to endanger people who may come in contact with such products. A majority of these products are imported from Canada and Mexico, two countries where asbestos is still used; further, not all imported asbestos-containing products are clearly labeled with proper content information. (Sources: U.S. Geological Survey, Mineral Commodity Summaries 2003, and 'Asbestos Strategies')
In an August 2003 report, the EPA's Office of Inspector General reiterates that asbestos is still a product very much around us: a survey in the mid-1980s found that, on average, 20% of all buildings in the United States contain asbestos. Further, this latest report confirms that asbestos containing material is still allowed in pipeline wrap, asbestos-cement corrugated sheet, asbestos-cement flat sheet, roofing felt, millboard, vinyl-asbestos floor tile, asbestos-cement shingle, and roof coatings. (Rept. #2003-P-00012).
A 2004 report by the Environmental Working Group provides a timely evalution of the asbestos-related disease epidemic in America - a 'public health tragedy caused by asbestos.' This report documents the history of asbestos use and provides analysis and statistics to inform the political debate currently being waged to resolve the problem.
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