Recommended Exposure Limit (REL)
A National Institute for Occupational Safety and Health (NIOSH) time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek.

Amosite
A type of asbestos in the amphibole group; it is also known as brown asbestos.

Chrysotile Asbestos
A fibrous member of the serpentine group of minerals. Chrysotile asbestos fibers are flexible and have a curved morphology. It is the most common form of asbestos used commercially, also referred to as white asbestos.

Bulk Sample
A sample of suspected asbestos-containing material that is obtained from a building to be analyzed microscopically for asbestos content. Bulk sample analysis can be part of a process to assess the hazard from asbestos in a building.

Malignant pleural mesothelioma
Malignant pleural mesothelioma is a type of cancer that affects the inside lining of the chest cavity. It is usually associated with asbestos exposure.

Vermiculite
A chemically inert, lightweight, fire resistant, and odorless magnesium silicate material that is generally used for its thermal and sound insulation in construction and for its absorbent properties in horticultural applications. Vermiculite mined from Libby, Montana has been demonstrated to contain various amounts of asbestiform tremolite-like amphibole minerals.

Alimta (pemetrexed for injection)
Alimta is a new cancer drug used to treat malignant pleural mesothelioma. Alimta is given with cisplatin, another anti-cancer medicine.

Fibrogenic
Causing or contributing to the fibrotic response mechanism in tissues; commonly refers to substances that contribute to fibrosis of the lungs or liver.

RACM
Regulated Asbestos-Containing Material is (a) friable asbestos material, (b) Category I non-friable ACM that has become friable, (c) Category I non-friable ACM that will be or has been subjected to sanding, grinding, cutting or abrading, or (d) Category II non-friable ACM that has a high probability of becoming or has become crumbled, pulverized, or reduced to powder by the forces expected to act on the material in the course of demolition or renovation operations.

Tremolite
Tremolite may occur in fibrous form (an asbestos). It is not used commercially in the United States, but is a common impurity in chrysotile asbestos and vermiculite mined from deposits in Libby, Montana.