Asbestos is the name given to a natural group of flexible fiber-like minerals that are separated into thin threads and woven. These fibers are fireproof, relatively inexpensive, excellent insulators, and do not conduct electricity. For these reasons, asbestos has been widely used in many industries since the late 1800s. The building and construction industry used it for strengthening cement and plastics as well as for insulation, fireproofing, and sound absorption. The shipbuilding industry has used asbestos to insulate boilers, steampipes, hot water pipes, and nuclear reactors in ships. The automotive industry uses asbestos in vehicle brake-shoes and clutch pads. More than 5,000 products contain or have contained asbestos, some of which are listed below:
- Asbestos cement sheet and pipe products used for water supply and sewage piping, roofing and siding, casings for electrical wires, fire protection material, chemical tanks, electrical switchboards and components, and residential and industrial building materials.
- Friction products, such as clutch facings, brake linings for automobiles, railroad cars, airplanes, and industrial friction materials.
- Products containing asbestos paper, such as table pads and heat-protective mats, heat and electrical wire insulation, industrial filters for beverages, small appliance components, and underlying material for sheet flooring.
- Asbestos textile products, such as packing components, roofing materials, heat- and fire-resistant clothing, and fireproof draperies.
- Other products, including ceiling and floor tile, gaskets and packings, paints, coatings, and sealants, caulking and patching tape, and plastics.
Asbestos was seen as an ideal building material. During the twentieth century, some 30 million tons of asbestos were used in the construction of industrial sites, office buildings, schools, shipyards, homes, and everyday items such as ironing boards, dryers, toasters, and low-density insulation products. By the turn of the 20th century, however, researchers began to see a correlation between the unusually large numbers of deaths and lung problems in asbestos mining towns. Despite the growing link between asbestos and health problems, manufacturers and companies continued its use for many of their projects.
In the late 1970s, the U.S. Consumer Product Safety Commission banned the use of asbestos in wallboard patching compounds and gas fireplaces because these products released excessive amounts of asbestos fibers into the environment. In addition, asbestos was voluntarily withdrawn by manufacturers of electric hair dryers. These and other regulatory actions, coupled with widespread public concern about the hazards of asbestos, have resulted in a significant annual decline in U.S. use of asbestos. Domestic use of asbestos amounted to about 560,000 metric tons in 1979, but it had dropped to about 55,000 metric tons by 1989.
The known dangers of asbestos prompted the U.S. Environmental Protection Agency (EPA) to establish Federal Regulations banning certain uses of asbestos-containing materials. The Clean Air Act (CAA) generally prohibits the use of asbestos-containing spray-applied surfacing material for fireproofing/insulation and “decorative” purposes, if the material contains more than 1% asbestos. In addition, the CAA has banned the installation of wet and molded asbestos pipe insulation as well as molded asbestos block insulations on boilers and hot water tanks since 1975. Under the Toxic Substances Control Act (TSCA), the EPA has banned certain categories of asbestos-containing products. The six categories are: corrugated paper, rollboard, commercial paper, specialty paper, flooring felt, and any new uses of asbestos.
Many individuals today are not aware that they have been exposed to asbestos. Others know they have had asbestos exposure in the past but were never told of the potential danger to their health. Although asbestos use has declined significantly in recent decades, asbestos exposure is still a problem because a great deal of asbestos has been used in construction in the United States.
How Asbestos Causes Harm
Asbestos fibers enter the body in the air we breathe. Most of the asbestos fibers we breathe – like other dust particles – are stopped long before they enter the small airways of the lungs. For example, when we enter a dusty room, we sometimes choke. When we cough, the mucus stops the irritating substance. Because asbestos fibers are so small and thin, however, mucus is unable to stop all of the fibers from passing all the way down to the lungs.
People who breathe asbestos into their lungs may develop a slow buildup of scar-like tissue. Click on A, B and C to see three microscopic slides of asbestos fibers lodged in the lungs. This scar-like tissue does not expand and contract like normal lung tissue and so breathing becomes difficult. Blood flow to the lungs may also decrease and cause the heart to enlarge. This disease is called asbestosis. People with asbestosis have shortness of breath, often accompanied by a cough. This is a serious disease and can eventually lead to disability or death in people exposed to high amounts of asbestos.
People who have worked around asbestos also have an increased chance of getting two types of cancer: (1) cancer of the lung tissue itself and (2) mesothelioma, a cancer of the thin membrane that surrounds the lung and other internal organs. These diseases do not develop immediately, but appear only after a number of years. There is also some evidence from studies of workers that breathing asbestos can increase the chances of getting cancer in other locations (for example, stomach, intestines, esophagus, pancreas, kidneys), but this is less certain. Members of the public who are exposed to lower levels of asbestos may also have increased chances of getting cancer, but the risks are usually small and are difficult to measure directly. Many asbestos-containing products remain in buildings, ships, industrial facilities and other environments where the fibers can become airborne. It is even possible that a family member could expose others, because microscopic asbestos fibers on their clothing can come off at home. To learn more about your level of risk, click on Frequently Asked Questions.