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What is Asbestos?
Asbestos is a name given to a group of minerals which occur naturally as masses of long silky fibers. Asbestos is known for its unique properties of being resistant to abrasion, inert to acid and alkaline solutions, and stable at high temperatures. Because of these attributes, asbestos was widely used in construction and industry. Asbestos fibers are woven together or incorporated within other materials to create many products. There are three main types of asbestos fibers:
- Amosite (Brown Asbestos)
Straight, brittle fibers that are light gray to pale brown (the most commonly used in thermal system insulation).
- Chrysotile (White Asbestos)
Fine, silky, flexible white fibers (the most commonly used asbestos in the United States and Canada). Current evidence suggests that Chrysotile may be less hazardous than Amosite or Crocidolite.
- Crocidolite (Blue Asbestos)
Straight blue fibers.
There are three other types of asbestos fibers: Anthopylite, Tremolite, and Actinolite, which are found as contaminants in Asbestos Containing Materials (ACM).
What is the problem with asbestos?
People who work around or disturb asbestos are at risk for developing asbestos associated diseases. The occupational groups at the greatest risks for developing asbestos associated diseases include: janitors, maintenance personnel, construction workers, insulators, plumbers, mechanics, telephone workers, electrical workers, fire fighters, and asbestos abatement workers. People who work, live, or attend school in buildings containing asbestos products are also considered at risk for developing asbestos associated diseases.
The U.S. Environmental Protection Agency (EPA) considers there is no known safe level of asbestos exposure. In the fall of 1990, the EPA developed a policy, contained in the "Green Book" ("Managing Asbestos in Place—A Building Owner's Guide to Operations and Maintenance for Asbestos Containing Materials"). This document summarized EPA's eleven years of experience with asbestos. EPA recommends that asbestos containing materials (ACM) in good condition, can be maintained in place with very slight health risk to the building occupants.
How is asbestos exposure created?
ACM which can be crumbled, pulverized, or reduced to powder by hand pressure is known as friable asbestos. When friable ACM is damaged or disturbed it releases fibers into the air. Airborne asbestos fibers are small, odorless, and tasteless. They range in size from .1 to 10 microns in length (a human hair is about 50 microns in diameter). Because asbestos fibers are small and light, they can be suspended in the air for long periods. People whose work brings them into contact with asbestos may inhale fibers. A worker's family may inhale asbestos fibers released by clothes which have been in contact with ACM.
People who live or work near asbestos related operations may inhale asbestos fibers that have been released into the air by work activities. The amount of asbestos a worker (anyone disturbing ACM) is exposed to will vary according to several factors:
- the fiber concentration in the air;
- the duration of exposure;
- the worker's breathing rate;
- the weather conditions; and,
- whether or not protective equipment is worn.
Asbestos has been so widely used in the United States that the entire population has been exposed to some degree. Air, beverages, drinking water, food, drugs, dental preparations, and a variety of consumer products all may contain small amounts of asbestos. In addition, asbestos fibers are released into the environment from outcrops of bedrock in the earth. The asbestos containing rocks release fibers as a result of wind, water and chemical erosion.
What are the diseases caused by asbestos exposure?
Once inhaled, the small, inert asbestos fibers can easily penetrate the body's defenses. They are deposited and retained in the airways and tissues of the lungs. In the alveoli, the location of gas exchange, asbestos causes the development of scar tissue. This thickening of the alveoli wall reduces the amount of oxygen available to the body. Because asbestos fibers remain in the body, each exposure increases the likelihood of developing one or more of the following diseases:
A chronic lung ailment caused by the build up of scar tissue inside the lungs. Asbestosis can cause shortness of breath, permanent lung damage, and increases the risk of lung infections.
An asbestos caused cancer of the chest cavity lining or abdominal cavity.
- Other Cancers
Cancer of the lung, esophagus, stomach, colon, and pancreas.
Asbestos causes cancer. This is known from studies of actual groups of asbestos workers, not inferred from animal studies. The time it takes to develop lung cancer is often fifteen years or longer. The time frame for developing asbestosis and mesothelioma is even longer. Many studies have shown the combination of smoking and asbestos exposure to be particularly hazardous. Cigarette smokers exposed to asbestos, on the average are ten times more likely to develop lung cancer than non-smokers.
How has asbestos been used in the U.S.?
Asbestos has been mined and used commercially in North America since 1880, but its use increased greatly during and after World War II. The building and construction industry used asbestos for strengthening cement and plastics. Asbestos was also used for heat insulation, fire proofing, and sound absorption. The ship building industry used asbestos to insulate steam pipes, boilers, hot water pipes, and nuclear reactors in ships. Because of it's good friction and wear characteristics, asbestos is often used in brake shoes and clutch pads in cars, trucks, and airplanes.
In 1979, the United States' consumption of asbestos amounted to 560,000 metric tons. By 1983, the annual total consumption had dropped to 217,000 tons. This reduction was due partially to regulatory actions, which banned the use of asbestos in clothing, wallboard patching compounds, some construction materials, and in gas heaters. Asbestos was voluntarily withdrawn by manufacturers of electric hair dryers in 1979.
Where can asbestos be found?
Asbestos containing materials can be classified into one of three types: sprayed or trowelled-on material, Thermal System Insulation (TSI), or miscellaneous materials.
- Sprayed or trowelled-on materials used on ceilings or walls: This surfacing material is found as a white, popcorn textured decorative, acoustical, and fire proofing cover in homes, buildings, and schools.
- TSI: Here asbestos is often found as plaster cement wrap around boilers, on water and steam pipe elbows, tees, fittings, and pipe runs. Asbestos is also found on duct systems, and as a cardboard type of material (called aircell) found on steam pipe runs.
- Miscellaneous material: This includes all materials containing asbestos which were not included in the above groups. For example: floor tile, sheet rock, ceiling tiles, automotive friction products, rubber tile matting, rubber stair treading and risers, auditorium acoustical panels and sound proofing, gasket material, stage curtains, roofing materials, transite siding, caulking, cement pipe, kiln insulation, electrical panel insulation and wiring, fire brick, tar, and others.
These suspect materials (materials which may contain asbestos) are found in either a friable (can be crushed or crumbled by hand pressure) or a non-friable state.
How many public and commercial (P & C) building are thought to contain asbestos?
Asbestos containing materials have been used extensively in many public and commercial buildings in the United States. In 1988 the EPA published a survey of 3.6 million P&C buildings. The EPA survey gave the following data showing the extent of asbestos use in public and commercial buildings:
- Friable asbestos was found in 733,000 buildings (20%).
- Sprayed or trowelled-on ACM was present in 192,000 buildings (5%).
- Thermal System Insulation (TSI) was found in 563,000 buildings (16%).
- 501,000 buildings (14%) contained damaged ACM.
- 184,000 buildings (5%) contained moderately damaged ACM.
- 317,000 buildings (9%) contained severely damaged ACM.
Of the 733,000 public and commercial buildings containing friable asbestos, the following was found:
- 511,000 buildings (70%) were private, non-residential structures.
- 208,000 buildings (28%) were apartments with ten or more units.
- 14,000 buildings (2%) were Federal Buildings.
The Utah Department of Health also performed a survey to determine the number of state-owned buildings in Utah that contained friable asbestos material. The 1986 report estimates that of 499 buildings surveyed, thirty seven percent contained some form of friable asbestos. The state survey supports the findings of the EPA. This suggests that a significant number of the 32,000 (1990) buildings in Utah contain ACM.