Asbestos
Asbestos is a name given to a group of six naturally occurring silicate minerals in two categories: serpentine (containing a single mineral: chrysotile) and amphibole (containing all of the other five: amosite, crocidolite, tremolite, anthophyllite, and actinolite). Asbestos was used for thousands of years for various things, such as construction and pottery, although large-scale mining didn't begin until the 19th century. It became desirable as a building material because of its low cost, resistance to fire and acid, and sound absorption. Despite being a cause of lung cancer and various other diseases, and despite thousands of years of people's personal observations, asbestos was not known to be dangerous until scientific studies were done on its health effects. As a result of these advances in science, regulations have phased out asbestos as a construction material in many countries.[1]
Asbestos is actually different than other types of hazardous material in that its toxicity is caused neither by chemistry nor by radiation. Unlike most other harmful substances, asbestos does its damage via direct mechanical action. Its unusually fine-grained crystal structure and long, thin fibers make it particularly susceptible to breaking into microscopic pieces that can be inhaled, and when inhaled, some of those pieces can be so fine as to be only a few atoms thick, making it easy for them to lodge into lung cells.
The mechanism of carcinogenicity for asbestos is frustrated phagocytosis, i.e., the inability of a phagocyte to engulf its target.[2] This mechanism likely also applies to other similarly-shaped, biologically-inert substances such as nanotubes and nanowires that meet the same length threshold for pleural retention of 5 µm as asbestos does.[3]
Some claim that asbestos is actually not harmful at all, and has had its reputation unjustly tarnished. Others further embellish this thought with the claim that asbestos is harmless because it's natural.[citation needed]
Artificial snow commonly contained asbestos fibers before the 1980s phase-out happened.[4]
[edit] Use as medicine
Practitioners of traditional Chinese medicine, while recognizing the risks of asbestos, claim it is effective for treating impotence.[5]
[edit] Footnotes
- ↑ http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-11.pdf IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Asbestos (Chrysotile, Amosite, Crocidolite, Tremolite, Actinolite and Anthophyllite)
- ↑ http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-11.pdf IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Asbestos (Chrysotile, Amosite, Crocidolite, Tremolite, Actinolite and Anthophyllite)
- ↑ http://www.particleandfibretoxicology.com/content/pdf/1743-8977-9-34.pdf Use of back-scatter electron signals to visualise cell/nanowires interactions in vitro and in vivo; frustrated phagocytosis of long fibres in macrophages and compartmentalisation in mesothelial cells in vivo
- ↑ Dorothy in the Wizard of Oz frolicked through it
- ↑ Actinolite, TCMwiki.com.
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