All types of asbestos fibers are known to cause serious health hazards in humans.[1][2][3] The most common diseases associated with chronic exposure to asbestos are asbestosis and mesothelioma.[4]
Amosite and crocidolite are considered the most hazardous asbestos fiber types;[5] however, chrysotile asbestos has also produced tumors in animals and is a recognized cause of asbestosis and malignant mesothelioma in humans,[6] and mesothelioma has been observed in people who were occupationally exposed to chrysotile, family members of the occupationally exposed, and residents who lived close to asbestos factories and mines.[7]
During the 1980s and again in the 1990s it was suggested at times that the process of making asbestos cement could "neutralize" the asbestos, either via chemical processes or by causing cement to attach to the fibers and changing their physical size; subsequent studies showed that this was untrue, and that decades-old asbestos cement, when broken, releases asbestos fibers identical to those found in nature, with no detectable alteration.[8]