Asbestos
Public perception is that asbestos is a man-made material,
however this is not the case at all – it is in fact a term used
to describe several naturally occurring minerals.
There are six forms of asbestos - chrysotile, crocidolite, amosite, anthophyllite,
tremolite, and actinolite. All types of asbestos are formed of fibres,
and when asbestos is crushed these fibres separate and can become air
borne, which is where the risk of inhalation becomes possible. All forms
of asbestos exhibit a number of properties that are desirable in a number
of applications, they are excellent chemical and thermal resistance, high
tensile strength, high flexibility and low electrical conductivity.
Asbestos isn’t used in its raw form, it is commonly mixed with other
materials such as concrete to form strong and heat resistant composites.
For some applications it is simply woven into material sheeting, this
approach is commonly taken when the intended use is thermal insulation
where the material needs to remain flexible.
Of the six forms of asbestos, chysotile is the most commonly used in industry,
this is the only one of the asbestos minerals that has a serpentine construction,
i.e. is composed of layered structure of crystals. The other types of
asbestos are all of amphiboles construction and have a chain-like structure
of long fibres. Chrysotile presents the lowest risk of causing asbestos
related illness, as the layered construction is less likely to release
the fibres that can lodge in people’s lungs and lead to asbestosis
or mesothelioma.
Chysotile is still being mined today, and is used in a number of areas,
mainly involved in the construction industry. There are far stricter controls
on the use of asbestos since the discovery of its carcinogenic properties,
and under these controls its use is considered perfectly safe, presenting
no additional risks of developing cancer to the workers who use this material.
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