There are different kinds of asbestos. The most common forms are:
- "White" asbestos or Chrysotile which is obtained from serpentine rocks. Chrysotile is the type most often used in industry. It is more flexible than other types of asbestos and can be spun and woven into fabric. This is the kind of asbestos used in theatre curtains and firefighters' suits.
- "Brown" asbestos or Amosite is a trade name for the amphiboles belonging to the Cummingtonite - Grunerite solid solution series, commonly from Africa.
- "Blue" asbestos or Riebeckite is also known under the name of Crocidolite. Blue asbestos is commonly thought of as the most dangerous type of asbestos.
In the United States, chrysotile has been the most commonly used type of asbestos. Chrysotile was often present in a wide variety of materials, including but not limited to:
- sheetrock taping
- mud and texture coats
- vinyl floor tiles, sheeting, adhesives and ceiling tiles
- plasters and stuccos
- roofing tars, felts, siding, and shingles
- "transite" panels, siding, countertops, and pipes
- acoustical ceilings
- brake pads and shoes
- clutch plates
- stage curtains
- fire blankets
- interior fire doors
- fireproof clothing for firefighters
- refractory cements and papers
Asbestos has been classified as a known human carcinogen (a substance that causes cancer) by the U.S. Department of Health and Human Services, the EPA, and the International Agency for Research on Cancer. In 1989 the EPA passed the Asbestos Ban and Phase Out Rule which was subsequently overturned in the case of Corrosion Proof Fittings v. U.S. Environmental Protection Agency, 1991. This ruling leaves many consumer products that can still legally contain trace amounts of asbestos.
Although it is clear that health risks from asbestos exposure increase with heavier exposure and longer exposure time, investigators have found asbestos-related diseases in individuals with only brief exposures. Generally, those who develop asbestos-related diseases show no signs of illness for a long time after their first exposure. It can take from 10 to 40 years or more for symptoms of an asbestos-related condition to appear.