Asbestos Overview

What is Asbestos?

The word "asbestos" actually refers to a particular form taken by any one of six naturally occurring minerals. These very fine fibers are separable, are a hundreds of times thinner than hairs, and too small to be seen with the naked eye. They are actually crystals. The Occupational Safety and Health Administration (OSHA) defines fibers of concern as at least five micrometers long and at least three times as long as their diameters. Mineralogists speak of fibers as much as a thousand times as long as their diameters.

Types of Asbestos

The minerals that are considered silicates (the molecules include silicon and oxygen) are:

  • chrysotile (aka serpentine or white asbestos; from Greek meaning "fine, silky hair") appears as curly whitish fibers and constitutes ninety percent of the asbestos in use; it's mined mostly in Canada. Even by 1997 there were only two companies still in the business
  • crocidolite (aka riebeckite or blue asbestos with straight fibers) comes from southern Africa and Australia
  • amosite (cummingtonite-grunerite or brown asbestos; the trade name is an acronym for Asbestos Mines of South Africa) is also straight, but brittle
  • anthophyllite is brittle and white; the "asbestiform" is only one variety
  • tremolite, which in rough form appears white and chalky and also comes in other forms
  • actinolite also comes in other forms than the asbestos fibers.

The last five types are referred to mineralogically as "amphibole" (ambiguous, referring to their geologic formation) and have a slightly more complex crystal structure. Their brittle rods or needles are not used explicitly in commercial products. When they are present they stay in the lungs longer than chrysotile and are more likely to cause illness, and even the worst asbestos illnesses. In fact, it may often be very small contaminations of amphibole minerals within chrysotile that are most to blame for cancer deaths caused by asbestos.

Minerals of this sort are found commonly in certain kinds of rock. These rocks are widely found In California in at least 44 of the state's 58 counties. These rocks, however, do not always contain asbestos. Most of the rocks contain less than 25 percent asbestos and because of the minerals' durability, they could be mined at low cost by simply crushing the other minerals from around them. Other asbestiform minerals have also been found, but have not been commercially exploited, and at least one has been synthesized in the laboratory. Asbestos fibers seem particularly to have formed near fault zones in the rocks where high temperatures, pressures, and water have transformed the molecules into the asbestiform crystals. Sometimes a vein of fibers is clearly visible across a cut in the rock. Often the surrounding rock, which appears to be clear of asbestos, harbors fibers too, just not gathered as well or controlled when the rock is crushed, drilled, or simply quarried.

It is very hard to differentiate rock and other materials that are clear of asbestos from those that are contaminated. Once asbestos is identified in any of the rock and soil within a location -or the construction materials brought to it, or the materials accumulated by demolition - all of those materials must be considered contaminated and fall under federal, state, and local asbestos regulations.

Where is Asbestos Located?

A map compiled from a US Geological Survey database of records and literature on the history of asbestos mining in the US shows a strong band of proven deposits running down the eastern shoulder of the Appalachian Mountains from northern New Jersey to northern Georgia (where it coincides with some of the fastest-growing counties in the nation). Fairfax County, Virginia, has asbestos in eleven square miles and have set up specific procedures in monitoring and reporting requirements for construction in the area. There is another stripe of proven deposits up the middle of Vermont, over into Maine, clusters in Michigan's Upper Peninsula, some in the northern Rockies, across northern and central Washington, and at the tail of the California sweep is a very high concentration north of Tucson, Arizona.

Russia (by far the world leader, supplying nearly half of what is mined worldwide), China, Kazakhstan, Brazil, Zimbabwe, and 15 other countries also have accounts of asbestos. Only China's mining operations are growing, and they mostly serve Chinese uses. Chrysotile asbestos, however, is still mined heavily in Canada. This supplied 89 percent of the asbestos used in the US between 2002 and 2005. Canadian labor authorities estimate that the minerals are present in almost two-thirds of the earth's crust. They also estimate that everyone on earth breathes in an average of between ten and fifteen thousand asbestos fibers a day and drinks between two hundred thousand and two million fibers in each liter of water. In the chrysotile-mining areas of Quebec, people may be drinking as much as 170 million fibers in each liter of water. The authorities cite these statistics to demonstrate that asbestos is not as hazardous as some people think.

The mining of asbestos in the US ended in 2002, but were still exporting two or three thousand metric tons a year (down from seven in 2002), including asbestos-containing materials and re-exports of materials that have come into the US from overseas. The Chrysotile Institute (based in Canada) reports US consumption of 13 thousand metric tons of chrysotile a year, in addition to imports of ACMs such as cement pipe and sheets.

Chrysotile fibers are mostly exported from Canada as raw fibers for mixing into other materials manufactured elsewhere. The fibers are shipped in double pressure-packed plastic bags, labeled with warnings, and stacked on pallets. The Montreal-based Chrysotile Institute, a coalition of mining, manufacturing, labor-union, provincial and Canadian interests makes a great deal of proper methods of caretaking while the fibers are stored. They do this by frequently vacuuming and wet-mopping the warehouse floors. Under a 1987 convention of the International Labor Organization, the bags should be opened only inside sealed containers, operated through glove ports, that feed directly into the manufacturing processes that will mix them with encapsulating materials. At every point in the process, and especially when the mixed product is shaped and cut, the convention calls for vacuum systems to remove any fibers that might escape dry. Though all of these measures are depicted in photos on the Chrysotile Institute's Web site, workers are shown operating even systems that rely only on wetting the product as it is cut without respirators to protect their lungs from errant fibers.

Why Was Asbestos Used?

What has made asbestos most attractive throughout history is that it is burn resistant. Another interesting feature is that it does not conduct electricity. The very word comes from a root that it closely resembles "unquenchable" and may relate to the use of asbestos fibers as lamp wicks. The fibers are fine, flexible and can be spun into thread and woven into cloth that is flameproof, hard to tear, and insulates well. Left loose, the fibers do not pack down as readily as some others do. It is virtually indestructible by heat, salt water, corrosive chemicals (especially alkalies), and any chemical or biological process. The fibers mix well into other materials such as asphalt or cement to make them stronger, more flexible, and fire-retardant. They do not dissolve or evaporate with water that may be used to make the mix. By themselves, the minerals are very light.

What Makes Asbestos So Dangerous?

The fibers of asbestos are what cause it to be dangerous. They fill the air surrounding asbestos products and when breathed or swallowed, embed in the tissues of the linings of your organs, most commonly your lungs and digestive system. Asbestos can also affect your heart. However, before people knew the dangers of asbestos, it was used to make a number of products, many of which could be commonly found in the home. Today, the use of asbestos is highly regulated, which means that less people are getting sick, but many cases of asbestosis, lung cancer and mesothelioma are still reported due to exposure in the past. If you live in an older home or were part of the construction industry in the past, it is a good idea to ask your doctor to check your body for asbestos exposure.

Show Your Support

Get Your Own Asbestos      Awareness Wristband
Attention Veterans
Related News