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.

Lethal Concentration(50) (LC50)
A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

Adenocarcinoma
Adenocarcinoma of the lung is a type of lung cancer. Like other cancers, adenocarcinoma is the growth of abnormal cells. These cancerous cells multiply out of control, and form a tumor. As the tumor grows, it destroys parts of the lung. Eventually, the tumor's abnormal cells can spread (metastasize) to other parts of the body, including the brain.

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.

Actinolite
One of the six types of asbestos.

Actinolite
Actinolite is the intermediate member; when iron is predominant the mineral is ferro-actinolite and when magnesium is predominant, the mineral is tremolite. The iron produces a green color that darkens as the iron content increases. Actinolite may occur in fibrous form (an asbestos). It is not used commercially, but is a common impurity in chrysotile asbestos.

Asbestos Containing Material (ACM).
Any material or product that contains more than one percent 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.

Immunologic Toxicity
The occurrence of adverse effects on the immune system that may result from exposure to environmental agents such as chemicals.

Asbestos
A general term applied to certain polysilicate fibrous minerals displaying similar physical characteristics although differing in composition. The most common asbestos mineral (over 95% of U.S. production) is chrysotile, a variety of serpentine, a metamorphic mineral.