Asbestos Fibers

Asbestos is the smallest, naturally occurring fiber in the world (1). There are six minerals that fall under the classification of asbestos. They are grouped under two families of minerals known as the serpentines and amphiboles. The serpentines are singularly known as chrysotile (white asbestos). The larger amphiboles group comprises amosite (brown asbestos), crocidolite (blue asbestos), anthophyllite, tremolite, and actinolite. The two groups are mineralogically distinct and differentiated by the manner in which they are processed in the lungs after inhalation. Chrysotile fibers are easily degraded in the lung and break apart easily, properties inherent to other non-fibrous minerals. However, the lungs' responses to the amphiboles are more detrimental and suggest a more insoluble structure. Currently, chrysotile is the only form of asbestos that is mined in significant quantities.

The ability of an asbestos fiber to damage an organ, for example the lung, is dependent on its diameter (2). Long, thin fibers are able to bypass the lungs natural defenses that serve to filter non-fibrous particles. Shorter fibers have been determined to pose little threat to human health. The chrysotile form of asbestos is unique in that its fiber forms a thin, rolled up sheet. This configuration is due to the component magnesium-silica structure of the mineral. The amphiboles are made up of more robust silicate double chains, which contribute to the minerals' greater toxicity.

A number of studies have indicated that chrysotile asbestos is relatively harmless compared to asbestos fibers from the amphiboles group (3, 4, 5). These studies reported no significant increases in risks of asbestosis, mesothelioma, or lung cancer. However, heavy and prolonged exposure may produce lung cancer. Exposure concentrations and the length of exposure to asbestos are key elements in assessing health outcomes. Even though situations such as low dose exposure over a long period of time or high exposures of short duration both pose low risks of adverse health effects, significant disease has been known to occur.

'Asbestos Fibers' Sources:
  1. O'Reilly, K.A.; et al., "Asbestos-related lung disease". Am Fam Physician; 75:683-8, 690, 2007.
  2. Bernstein, D.M. and Hoskins, J.A., "The health effects of chrysotile: current perspective based upon recent data". Reg Toxicol Pharmacol; 45: 252-64, 2006.
  3. Yarborough, C.M., "Chrysotile asbestos and mesothelioma". Crit. Toxicol. Rev.; 36:165-87, 2006.
  4. Paustenbach, D.J., et al., "Environmental and occupational health hazards associated with the presence of asbestos in brake linings and pads (1900 to present): a "state-of-the-art" review". J. Toxicol. Environ. Health B Crit. Rev.; 7:33-110, 2004.
    1. Camus, M. et al., "Non-occupational exposure to chrysotile asbestos and the risk of lung cancer". N. Engl. J. Med.; 338:1565-71, 1998.

 

 

 

 

 
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