General Overview of Asbestos

Asbestos Asbestos is a catch-all term for a variety of different minerals which have a wide range of uses. The word "asbestos" is derived from Greek words meaning "not extinguishable"; asbestos is extremely resistant to fire and heat. All forms of asbestos are fibrous, meaning that asbestos strands can be extracted from the rock and woven and spun much like cotton or other conventional fabrics. In addition to being fireproof and weavable into cloth, asbestos is an outstanding insulator, has high tensile strength, and is chemically stable. The combination of these unusual properties led to the use of asbestos in an enormous variety of household and industrial applications from ancient times; asbestos has been in use for more than two thousand years.

There are two primary types of asbestos in widespread use: serpentine asbestos has a snake-like structure with wavy fibers, and amphibole asbestos is characterized by crystalline needle-like fibers. Serpentine asbestos is generally made up of a compound of magnesium, silicon, hydrogen and oxygen, while amphibole asbestos contains iron, silicon, sodium, oxygen and hydrogen. Because of the very wide variety of sources and types of asbestos, it is common for any particular type of asbestos to contain elements such as quartz, beryl, garnet, feldspar, mica, or clay.

In the ancient world, asbestos was considered a nearly magical material – a cloth that would not burn, or a lamp wick which was never entirely consumed. The earliest recorded use of asbestos come to us from the ancient Greeks. Asbestos wicks were used to light the temples, and funereal clothes for departed kings were woven from asbestos fibers, ensuring that when the ruler was cremated, the ashes of his body would not be mingled with the ashes of the wood used for the pyre. The Greeks even wove asbestos fibers into napkins, a practice later adapted by the Romans, who were said to clean the cloths by tossing them into a fire – the food or stains would burn off, leaving the cloth unsullied. For this reason, the Romans called asbestos "amiantus", Latin for "unspoiled" or "unpolluted".

However, as the use of asbestos cloth spread in the classical era, the ancients also began to notice that there were negative health effects associated with this magical substance. Slaves who were forced to extract the fibers from asbestos-bearing rock and weave the asbestos cloths commonly developed diseases of the lungs. Possibly because of this, the use of asbestos declined in later centuries and by the Middle Ages the substance was no longer in widespread use, although there were some exceptions. Some historians report that Charlemagne had an asbestos tablecloth for use at state banquets, and it is known that Marco Polo returned from China with reports of items made from asbestos fiber.

Asbestos enjoyed renewed prosperity with the coming of the Industrial Revolution, which spurred an insatiable demand for insulation for the boilers, turbines, steam pipes and other high-temperature machinery of the factory age. It is not known with certainty whether these innovators were aware of the health risks associated with asbestos, but in an era of child labor, poor sanitation, and brutal conditions on the factory floor, such concerns were likely not taken very seriously in any case. The rise of the railroads and the development of steam-powered ships made asbestos even more widely used, as fire suppression and control was a critical need in those modes of transport.

By the beginning of the twentieth century, the risk of asbestos were becoming obvious to researchers. The inhabitants of asbestos mining towns were riddled with lung problems. During World War One, several studies in the United States found that asbestos workers tended to die young. Finally in 1924, a British physician established that asbestos fibers could enter the lungs and cause a wide variety of very serious ailments, leading to further study of asbestos. By the 1930s, medical science was beginning to explore the connection between asbestos and a particularly deadly strain of cancer now known as "mesothelioma".

Asbestos is primarily dangerous to human health when the substance is damaged, broken, or exposed to extreme heat. Normally the fibers remain large and stable, and cannot become airborne or enter the body. However, a peculiarity in the structure of asbestos fibers means that when stressed or damaged, they have a strong tendency to fracture into many much smaller fibers. These fibers in turn can split, until one large fiber is eventually the source of hundreds or even thousands of tiny fibers. These fibers are so small and so insidious that they can easily become airborne and breathed into the lungs of people nearby. When this occurs, the fibers penetrate the lungs, heart, and membranes of the body and cause a variety of syndromes and diseases, including asbestosis, lung cancer, gastrointestinal cancer, and mesothelioma.

Despite these health risks, asbestos continued in very wide use throughout the 20th century, until growing public awareness of the danger and anger at the asbestos industry for concealing the risks prompted a political outcry and led to regulatory action. Amphibole asbestos, which is considerably more dangerous to human health, has been banned globally since the 1980s, although there are still many buildings which contain it, since it was used for construction pipes, conduits for electrical or communication lines, insulation, and ceiling tiles. Serpentine asbestos, particularly a form known as "chrysotile" is in wider use, and is still permitted for some uses in the United States. Chrysotile is found in floor sheeting, roofing materials, fireproofing, brake pads and shoes, automotive components, fireproof clothing, fire doors, and other uses. There is only limited evidence that chrysotile asbestos poses serious health risks, but most sources of chrysotile asbestos are also contaminated with the far deadlier amphibole varieties. This has lead many public health authorities to take a "better safe than sorry" approach and impose an absolute ban. Chrysotile has been banned outright in the European Union and in Australia, and asbestos in any form is no longer used at all in those regions.

'General Overview of Asbestos' Resources:
  1. U. S. Environmental Protection Agency.  Asbestos and Vermiculite.  "Asbestos Ban and Phase Out."  25 April 2007. 
  2. U. S. Environmental Protection Agency.  Asbestos and Vermiculite. "General Asbestos Information."  25 April 2007.  
  3. Wisconsin Department of Natural Resources.  "Asbestos:  History and Uses."  21 April 2006.
  4. U. S. Geological Survey.  "Asbestos Statistics and Information."  20 March 2007.
  5. U. S. Environmental Protection Agency.  Asbestos and Vermiculite.  "Basic Information."  26 April 2007.