Risk Ratio
The ratio of the risk among persons with specific risk factors compared to the risk among persons without risk factors. A risk ratio greater than 1 indicates greater risk of disease in the exposed group compared to the unexposed.

Dose-Response Relationship
The quantitative relationship between the amount of exposure to a toxicant and the incidence of the adverse effects.

Anthophyllite
A type of asbestos in the amphibole group; it is also known as azbolen asbestos.

Parenchymal fibrosis
It is easily conceivable that prolonged retention of some types of minerals in the lung would be a stimulating factor for inflammatory and neoplastic processes, leading in turn to parenchymal fibrosis and peripheral cancer.

Suspect material
Building material suspected of containing asbestos, e.g., surfacing material, floor tile, ceiling tile, thermal system insulation, and miscellaneous other materials.

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.

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.

Permissible Exposure Limit (PEL)
An Occupational Safety and Health Administration (OSHA) allowable exposure level in workplace air averaged over an 8-hour shift of a 40 hour workweek.

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.

Friable asbestos
Any material containing more than one percent asbestos, and that can be crumbled or reduced to powder by hand pressure. (May include previously non-friable material which becomes broken or damaged by mechanical force.)