Our Asbestos Main Article provides a comprehensive look at the who, what, when and how of Asbestos

Definition of Asbestos

Asbestos: A natural material made up of tiny fibers which can lodge in the lungs and lead to cancer or scarring of the lungs. The cancer may be lung cancer or (mesothelioma), which is a cancer of the lining of the lungs or other internal organs. The scarring of the lungs is termed asbestosis. Exposure to asbestos usually occurs by breathing contaminated air in workplaces that make or use asbestos or in the air of buildings containing asbestos that are being torn down or renovated.

Asbestos is one of the health hazards of mining. To take a case in point, the small town of Libby, Montana was home through most of the 20th century to one of the world's largest vermiculite mines. Vermiculite, a mineral, is used in everything from insulation to animal feed to potting soil. But Libby's rich vermiculite deposit was laced with asbestos. Hundreds of miners and their families fell sick or died as a result of their exposure to the asbestos.

The following additional information is based on materials from the Agency for Toxic Substances and Disease Registry, a part of the Centers for Disease Control and Prevention (the CDC).

Asbestos is a group of six different fibrous minerals: The six minerals are amosite, chrysotile, crocidolite, and the fibrous varieties of tremolite, actinolite, and anthophyllite. They occur naturally in soil and rocks in some areas. Asbestos fibers vary in length and may be straight or curled. The fibers are resistant to heat and most chemicals.

Asbestos is used for a wide range of manufactured goods, mostly roofing shingles, ceiling and floor tiles, paper products, asbestos cement products, friction products (automobile clutch, brake, and transmission parts), textiles, packaging, gaskets, and coatings.

Asbestos mainly affects the lungs: Changes in the membrane surrounding the lung are common in workers exposed to asbestos. These lung changes are also sometimes found in people living in areas with high levels of asbestos in the air. Breathing very high levels of asbestos may result in a slow buildup of scar-like tissue in the lungs and in the membrane that surrounds the lungs. People with asbestosis have shortness of breath, often along with a cough and sometimes heart enlargement. This is chronic obstructive lung disease (COPD), a serious disease that can lead to disability or death.

Asbestos is a known carcinogen: There are two types of cancer caused by exposure to high levels of asbestos: cancer of the lung tissue itself and mesothelioma, a cancer of the membrane that surrounds the lung and other internal organs. Both of these are usually fatal. These diseases do not develop immediately, but show up only after many years.

Interactions between cigarette smoke and asbestos increase the chances of getting lung cancer. Studies of workers suggest that breathing asbestos can increase the chances of getting cancer in other parts of the body (stomach, intestines, esophagus, pancreas, kidneys), but this is not certain.

People who are exposed to lower levels of asbestos may also have an increased risk of developing cancer, but the risks are usually small and are difficult to measure.

It is not known whether ingesting (swallowing) asbestos causes cancer. Some people who had been exposed to asbestos fibers in their drinking water had higher-than-average death rates from cancer of the esophagus, stomach, and intestines. However, it isn't known whether this was caused by asbestos or by something else.

Medical tests: Chest X-rays cannot detect asbestos fibers, but can detect early signs of lung disease caused by asbestos. Other tests (lung and CAT scans), are also useful in detecting changes in the lungs.

Tests exist to measure asbestos fibers in urine, feces, mucus, or material rinsed out of the lung. However, low levels of asbestos fibers are found in these body fluids in nearly all people, so higher-than-average levels can only show that a person has been exposed to asbestos, not whether the person will experience ill health effects.

Regulations: In 1989, the US Environmental Protection Agency (EPA) banned all new uses of asbestos; uses established before this date are still allowed. The EPA has established regulations that require school systems to inspect for damaged asbestos and to eliminate or reduce the exposure by removing the asbestos or by covering it up. The EPA has set a limit of 7 million fibers per liter (MFL) as the concentration of long asbestos fibers that may be present in drinking water.