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Asbestos is the common
name for any variety of silicate materials that are fibrous in
structure and are more resistant to acid and fire than other
materials. It has two forms, serpentine and amphibole, and is
made of impure magnesium silicate. Asbestos is used for thermal
insulation, fire proofing, electrical insulation, building
materials, brake linings and has been used in numerous
industries.
Serpentine and amphibole asbestos both exhibit physical and
chemical resistance to high temperatures and applied force. The
raw ore of both forms is made up of fibrous strands. The strands
then continue to split into smaller and thinner fibers as
disturbance continues and increases. Asbestos' ore form will
initially divide into visible strands, fiber bundles, and
individual fibers. But then those visible strands, bundles, and
fibers will continue to split into microscopic fibers, bundles,
and strands. The splitting can continue on to minute levels of
microscopic levels of detection. This process is unique to
asbestos and is why airborne asbestos is such a problem. The
fibers can become so small that they remain airborne longer and
pass undetected by the respiratory dust defenses.
Physical characteristics differentiate the serpentine and
amphibole forms. Serpentines divide into curly, wavy fibers that
show little resistance to being bent or spiraled. Amphibole
fibers are needlelike shards that show great resistance to being
bent or curled. Serpentines are like man-made wool in
appearance, where amphiboles are like man-made fiberglass.
In addition to the two forms, there are three main types of
asbestos: chrysotile, amosite, and crocidolite. Chrysotile
asbestos is serpentine and amosite and crocidolite are
amphibole. Chrysotile is the chief commercial asbestos today.
Amosite is used in insulating materials and crocidolite is used
for making asbestos-cement products.
Canada is a chief producer of asbestos, which has some of the
largest asbestos mine fields in the world. Other producers are
Russia, Zimbabwe, the Republic of South Africa, Cyprus, and the
United States of America.
Asbestos is a potent carcinogen, that is, a cancer-causing
substance, and is a serious health hazard. It is the known cause
of pleural plaques,
asbestosis,
mesothelioma, and causes cancers of the lung, esophagus, and
colon. Diseases caused by asbestos have a long latency period,
usually taking ten to forty years before showing any symptoms of
the disease. This is especially apparent today, when people who
worked with installing asbestos as insulation and other
materials in the 1970s are just now coming to realize that they
are developing cancer at alarming rates.
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