NATURALLY OCCURRING ASBESTOS EXPOSURE HAZARDS ASSOCIATED WITH MINING

Asbestos is a commercial term applied to seven regulated minerals that occur in asbestiform habit. Naturally occurring asbestos (NOA) is commonly defined as asbestos that has not been processed in an asbestos mill. Refined asbestos is a known human carcinogen, and NOA can be a human carcinogen. The NOA related exposure hazards associated with mining generally fall into three categories; asbestos in tailings from asbestos mining, asbestos produced as a byproduct of a mining operation, and asbestos present as an associated mineral in an ore deposit. An example of a NOA hazard associated with asbestos mining is that present in the waste rock and tailings dumps at the Atlas Asbestos Mine site in Fresno County, California. The W. R. Grace vermiculite mine in Libby, Montana is an example of the hazards associated with asbestos produced as a byproduct of mining. Examples of exposures to NOA present as an associated mineral in an ore deposit include asbestos present in some iron ore deposits in Minnesota, asbestos veins in serpentine aggregate quarries throughout California, notably, throughout the historic Mother Lode area in the eastern Sierra Nevada, and asbestos veins in aggregate quarries in Sparta, New Jersey. The presence of NOA at mine sites is also problematic in regards to the reclamation of mined lands.