WHAT IS ASBESTOS...

Asbestos is the collective term given to a group of naturally occurring fibrous or "asbestiform" silicate minerals. Asbestos types occur within two groups of minerals: the serpentine and the amphibole. Asbestos containing materials can contain one or more of these types, identifiable only be laboratory analysis. Chrysotile (white asbestos), which accounts for approximately 95% of the world production of asbestos, is the only member of the serpentine group of minerals. Crocidolite (blue asbestos), amosite (brown asbestos), anthophyllite, tremolite and actinolite are all members of the amphibole group. Of the six types of asbestos, only chrysotile, amosite, crocidolite and to a lesser extent anthophyllite are mined for commercial use. Tremolite and actinolite have not been mined commercially although can be found as impurities in other commercially available mineral products.

ASBESTOS PRODUCTS...
For many years, until finally being banned in 1999, asbestos has been used for many and varied applications. Commercially manufactured asbestos containing materials can be broadly divided into the following categories:
  • Thermal insulation (eg. pipe and boiler insulation)
  • Fire-proofing materials (eg. 
  • sprayed insulation, fire door insulation)
    Asbestos cement / fibrocement products (e.g. roof and wall claddings)
  • Decorative and acoustic applications
  • Electrical switchboards, insulators and fittings
  • Vinyl floor coverings
  • Asbestos felts and paper-like products
  • Friction materials (e.g. brake linings)
  • Paints, coatings, sealants and adhesives
  • Packings and gaskets
  • Textiles (eg. woven cloths, blankets)
  • Miscellaneous and unusual products (eg. asbestos socks, phone boxes)
Asbestos has been used in over 3000 commercially manufactured products in as many situations as there are buildings. It is also likely to be found in situations were cost has been the primary reason for use, not its chemical properties. Finding such materials is difficult and requires a well trained eye with knowledge of building construction and use.

ASSESSING THE RISK...
Hazard Any situation with a potential for harm to life, health or property Risk: the probability that a hazard may be realised and an individual may suffer an injury as a result of a hazard. All asbestos containing materials are therefore considered to be a hazard, although the risk presented by the materials can vary significantly.  In general, the more friable asbestos containing materials represent the greatest risk. The type and percentage of asbestos within an asbestos containing material can vary substantially. As such there is also a large variation in the exposure risks associated with the presence of asbestos containing materials within buildings.

PROPERTIES OF ASBESTOS...
The primary useful properties of asbestos fibres are their thermal stability and resistance, chemical resistance, high tensile strength, abrasion resistance, low electrical and thermal conductivity, low biodegradability and good sound absorption qualities. The presence of asbestos in commercial products varies depending upon the product's uses. While all forms of asbestos are fibrous silicates, they differ in their chemical composition and properties, crystalline structure and fibre dimensions and as such their commercially useful properties also vary. All asbestos types are excellent thermal insulators and have been widely used as fire proofing (on steel structural beams and soffits) and insulation materials (on boilers, ovens, kilns, steam pipes and hot water pipes). The amphibole group has considerable resistance to chemical corrosion and as such have been used in environments which are prone to attack by acids. Both chrysotile and crocidolite have high tensile strength, and as such have been widely used in the manufacture of woven asbestos products. All the asbestos types show low electrical and thermal conductivity, low biodegradability and good sound absorption properties

ASBESTOS ANALYSIS...
Confirmation of the asbestos content and type within a suspect material should only be performed through analysis by appropriately trained and qualified personnel. Asbestos analysis is usually performed by polarised light microscopy, which is fast and inexpensive to perform. Confirmation analysis may also be performed by x-ray diffraction, transmission electron microscopy or scanning electron microscopy. An important part of the risk assessment associated with asbestos containing materials is the determination of airborne fibre levels. Airborne asbestos fibre monitoring is performed by a technique known as the Membrane Filter Method.  A sample of air is collected onto a membrane filter, with subsequent analysis by Phase Contrast Microscopy

HEALTH EFFECTS...
Inhalation of asbestos fibre may lead to the following asbestos related diseases: Mesothelioma: cancer of the pleura (lining of the lung cavity) or peritoneum (lining of the abdominal cavity). Asbestosis: scarring of the lung tissue. Lung Cancer: a cancer similar to that associated with tobacco smoking. Other cancers: cancer of the larynx, oesophagus, stomach, bowel, rectum and kidneys has been identified in heavily exposed asbestos workers. Asbestos related diseases do not appear for a long time following exposure to asbestos. The term "latency period" is used to described the period of time which passes between initially being exposed to airborne asbestos fibre and the disease being diagnosed.  Depending upon the asbestos type and magnitude of exposure, the latency period can range from between 10 and 40 years