Asbestos is the name given to a group of six different fibrous minerals (amosite, chrysotile, crocidolite, and the fibrous varieties of tremolite, actinolite, and anthophyllite) that occur naturally in the environment. One of these, namely chrysotile, belongs to the serpentine family of minerals, while all of the others belong to the amphibole family. All forms of asbestos are hazardous, and all can cause cancer, but amphibole forms of asbestos are considered to be somewhat more hazardous to health than chrysotile.

Asbestos fibers do not have any detectable odor or taste. They do not dissolve in water or evaporate and are resistant to heat, fire, chemical and biological degradation. Because of these properties, asbestos has been mined for use in a wide range of manufactured products, mostly in building materials, friction products, and heat-resistant fabrics.

Since asbestos fibers may cause harmful health effects in people who are exposed, all new uses of asbestos have been banned in the United States by the EPA.

Mesothelioma is cancer of the mesothelium, which is the lining that protects vital organs of the body. A diagnosis of malignant mesothelioma (often simply called mesothelioma) is very serious. Most cases are fatal within two years, although recent improvements in treatment (both chemotherapy and surgical treatment) have extended the survival times of many mesothelioma patients.

The rarest form of mesothelioma develops in the lining of the heart or pericardium. This type of mesothelioma cancer is known as pericardial mesothelioma.

Pericardial mesothelioma is believed to be caused by exposure to asbestos, a mineral commonly used in fire retardant and insulating materials. Since this form of mesothelioma cancer is rare, however, the links between asbestos exposure and the disease are not as strong as with the other forms of mesothelioma cancer.

Approximately 10 to 20 percent of Mesothelioma tumors develop in the lining of the abdomen. This type of mesothelioma is referred to as peritoneal mesothelioma.

The only known cause of peritoneal Mesothelioma is exposure to asbestos.

Nearly three-quarters of mesothelioma tumors develop in the lining of the lungs, which is known as the "pleura." Consequently, this type of mesothelioma cancer is known as pleural mesothelioma.

The only known cause of pleural mesothelioma is exposure to asbestos fibers, which are inhaled into the lungs and become lodged there.