Questions and Answers About Asbestos
The following answers some basic questions about asbestos and the risks of exposure.
- What is asbestos?
- Why is asbestos dangerous?
- How do people get exposed to asbestos?
- What products contain asbestos?
What is asbestos?
Asbestos is a virtually indestructible fiber, which when inhaled into the lung, tends to persist indefinitely. It is found in rock, and there are three major fiber types: chrysotile, amosite, and crocidilite. It is soft enough to be woven, is as flexible as cotton, and is fire-resistant. Asbestos has been used throughout history, but most extensively from the Industrial Revolution through the mid-1970s. In commercial and industrial settings, asbestos-containing products have been used for insulation for boilers, steam pipes, turbines, ovens, kilns, and other high-temperature equipment. In addition, numerous drywall and cement products contain asbestos.
Why is asbestos dangerous?
The precise mechanism that causes asbestos-related diseases is unknown. Asbestos is extremely dangerous if inhaled because it is indestructible and can result in lung disease. It appears that even low levels of exposure to asbestos can cause the fatal cancer mesothelioma. The inhalation of asbestos fiber has been associated with numerous other types of diseases such as lung, colon and gastrointestinal cancer as well as with fibrotic diseases in the lung such as asbestosis and pleural disease. Asbestos is not dangerous in its inert form as rock. When cut or disturbed, asbestos releases millions of microscopic fibers into the atmosphere. These fibers, when inhaled deep into the lung, can cause irreversible injury.
How do people get exposed to Asbestos?
Asbestos exposure occurs when asbestos fibers are released into the air. This happens when asbestos-containing materials such as pipe covering is cut during installation or repair, or when it deteriorates or is disturbed. Asbestos cements and fireproofing release fibers when mixed, or when the dry mixture is scraped. Joint compound releases fibers when mixed and sanded. Asbestos siding and asbestos cement pipe release fibers when cut with a power saw. Boilers release asbestos fibers during installation and major repair, and gaskets give off fibers when they are scraped from pipe flanges.
Many occupations pose a risk of exposure. Military and civilian ships used asbestos pipe insulation extensively, resulting in exposure to those who worked in the Navy, Merchant Marines, or in shipyards. Asbestos products have been used extensively in power plants, pulp and paper mills, oil refineries, aluminum plants, steel mills, chemical plants, and other industrial facilities. Large, steel-framed buildings used fireproofing on the steel girders, and residential and commercial structures often used asbestos-containing siding and joint compound.
What products contain asbestos?
Asbestos has been used throughout history but most extensively from the Industrial Revolution through the mid-1970s. Most manufacturers did not reveal the asbestos content of their products. Sewer and water systems from the 1940s through the 1970s used asbestos cement or “transite” pipe extensively. In addition, asbestos was used in:
- Pipe covering and block as a thermal insulation.
- Fireproofing that was sprayed on steel girders and other metal surfaces.
- Most joint compounds until the mid-1970s. Joint compound (which fills the gaps between sheets of drywall) used asbestos as a binder.
- Many refractory and high-temperature cements that were trawled or sprayed between bricks or onto metal surfaces.
- Many gaskets.
- Most boilers that were manufactured before 1980.
