Considered to be the second-most hazardous type of asbestos, amosite – or “brown” – asbestos was mined primarily in South Africa, though commercial production of this variety of asbestos was halted in the last 10 years and the mineral is no longer mined. A member of the amphibole group of asbestos types, amosite is characterized by long, thin fibers that are brittle and break off easily, therefore prompting inhalation.
For much of the 20th century, amosite was the second most prevalent type of asbestos material found in building materials, though it ranked far behind chrysotile asbestos for such uses. Records show that approximately 5 percent of all asbestos used in commercial buildings or factories was, at one time, of the amosite variety.
Amosite asbestos was used mostly in the manufacture of thermal insulation products and was also used in the production of acoustic and anti-condensation material. However, use of this highly friable, easily crumbled form of asbestos is now outlawed in most countries due to its high level of toxicity.
The hazards of brown asbestos cancer have become quite obvious in studies that included the miners who worked with amosite in South Africa. Large percentages of these individuals have developed severe pulmonary problems including both benign and malignant diseases of the pleura (lining of the lungs). Furthermore, Americans who worked with amosite asbestos in factories that used this form of the mineral in the manufacturing process also showed high rates of death due to asbestos-related diseases including mesothelioma cancer.
R. Lemen and E. Bingham, Toxicology and Industrial Health - A Case Study in Avoiding a Deadly Legacy in Developing Countries (Vol. 10, No. 1/2, Princeton Scientific Publishing Co., Inc. 1994);
H. Seidman, et al., Short-term Asbestos Work Exposure and Long-term Observation (Annals of the New York Academy of Sciences, 330:61-89, 1979).