Asbestos occurs in nature as hydrated silicates of various forms and structures that also contain various metal ions: iron, magnesium, calcium and sodium are typical constituents. There are two major forms of asbestos, known as amphiboles and serpentines. The serpentine form is a double chain structure of magnesium silicate, chrysotile. The amphiboles are what are known as inosilicates and consist of amosite, crocidolite, anthophyllite and actinolite.
The major use for asbestos has been to exploit its refractory properties and its high degree of chemical resistance. As it is extremely resistant to heat it has consequently found use in such applications as insulation materials, fire retardant structures, electrical insulation and brake linings to name just a few. The downside of this material, only discovered in relatively recent times, is its toxicity. The primary route of exposure to this toxicity is from inhaling asbestos fibers and these can cause a number of extremely dangerous and often fatal diseases. These diseases are primarily asbestosis, which arises from inflammation and scarring of the lungs, lung cancer (or bronchial cancer) of a kind also exacerbated by cigarette smoking, and Mesothelioma, a malignant cancer of the mesothelium lining and chest wall of a kind that is highly specific to asbestos exposure.
In addition to inhaling fibers, exposure can also occur from eating and drinking contaminated foodstuffs. The major risk of asbestos related diseases and an asbestos claim is normally associated with exposure to high concentrations of the material over prolonged time scales, and this often occurs with workers in the asbestos, building and related industries, though quite often their family members will also fall victim.
There are also a large number of documented cases where only a brief exposure to the material has resulted in disease. This brief exposure can trigger the equivalent of a time bomb, with no symptoms appearing until forty or so years later.