Monitoring in the Environment
Exposure Pathway and Exposure Types
Metabolism of Asbestos
Biomarkers of Asbestos
Organs Affected by Asbestos
Molecular Action of Asbestos
Measuring Human Exposure
Comparative Risk Assessment
Fate and Transport
What Everyone Should Know
Asbestos Removal and Sealing
Asbestos, a naturally occurring mineral, is a fibrous hydrated silicate which possesses the unique characteristics of high tensile strength and flexibility. It is also chemical, electrical, and thermal resistant, and yet, is relatively inexpensive. Because of these properties, the commercial use of asbestos has been exceedingly widespread and is found in products ranging from cosmetics to insulation.
There are six asbestos minerals used in over 1,000 commercial applications.
- Chrysotile (Mg6Si4O10(OH)8) is a white or greenish color and is considered to be the softest of the asbestos minerals. It is used in insulation and fireproofing products, as well as spun and woven into asbestos clothes and tapes. Chrysoltile is primarily mined in Canada, Africa and the former USSR. Scientists believe this to be the least toxic of all asbestiform minerals. This curly shaped fiber is the most common (>95%) type of asbestos found.
- Amosite (Fe7Si8O22(OH)2), a brownish-yellow to white asbestos mineral, has excellent properties for use in heat insulation. It has a needle-like morphology and is found in mines in South Africa.
- Crocidolite (Na2Fe2+3Fe3+2Si8O22(OH)2) is a blue sodium iron silicate fiber which may be woven or spun into cloth or tape. Mined in South Africa and Australia, it is believed to be the most toxic of asbestiform minerals. The use of crocidolite is very limited in the United States.
- Anthophyllite, a white magnesium silicate, contains various forms of iron. This fiber has a harsh texture, but has excellent resistance to chemicals and heat. Although limited in the United States, it has been found in decorative and acoustical material.
- Tremolite has a white to yellowish color and is a calcium magnesium silicate. It has been a major ingredient in industrial and commercial talc.
- Actinolite, a calcium iron magnesium silicate, has a greenish to white color. It has poor resistance to chemicals with a harsh texture. These properties limit its commercial use.