Asbestos has long been known as a material that does not burn, and has been used by many different cultures over the past several thousand years. During the industrial revolution of the late nineteenth century asbestos began to be used on an enormous scale, and during the twentieth century, the substance was added to an estimated three to five thousand different types of products.
Asbestos was widely used in industry and commerce for several reasons. First and perhaps most importantly, it was cheap and easy to produce and work with. In addition the substance has some valuable physical and chemical properties: it is virtually fire proof, and does not burn. It's highly resistant to acid and chemical degradation, has a high tensile strength, and is an excellent thermal, acoustical, and electrical insulator.
How was Asbestos Used?
During the twentieth century asbestos was added to many different types of products. These included construction materials (such as shingles and siding, cements, caulks, plasters, adhesives, pipes, and many other materials), fire proof fabric and protective clothing, household electrical appliances, brake pads and linings, moldable plastics, and other products. When added to these products it improved fire resistance and insulating qualities, and added strength.
Asbestos was added to many types of building materials, which were used in industrial, commercial, public, and residential buildings alike. Its high fire resistance made it particularly useful in industrial buildings, where it was used around furnaces and boilers as insulation and fire-proofing, and even in heat-resistant protective clothing.
Asbestos was also used in ship-yards and in the construction of ocean-going vessels (including Navy and industrial ships), and in the manufacture of brake pads and brake linings for the automotive industry, and other products such as electrical appliances.
Asbestos is also unintentionally present in some materials, including Zonolite, a vermiculite insulation product that can be found in millions of American homes. Zonolite was made using vermiculite obtained from a mine contaminated with asbestos.
Why is Asbestos No Longer Used?
For the most part, asbestos is no longer used: many of the chemical and physical properties that made it so useful also make the substance hazardous to health. Due to the inert nature of asbestos, the body is unable to break it down when it is inhaled.
Long, thin asbestos fibers that enter the lungs become lodged there, and over time cause chronic irritation and inflammation. Heavy or repeated asbestos exposure causes a condition called asbestosis, in which chronic inflammation leads to the development of scar tissue in the lungs. The scar tissue cannot hold oxygen and is stiff and inflexible, leading to painful breathing and reduced lung capacity.
Asbestos exposure can also cause cancer. These cancers, called mesothelioma, can develop in different parts of the body (most commonly in the lining of the lungs, abdomen, or heart) after relatively small amounts of asbestos exposure. Mesothelioma cancers are difficult to diagnose and are highly treatment-resistant.
Is All Asbestos Dangerous?
There are six types of asbestos: chrysotile, amosite, actinolite, anthoplyllite, crocidolite, and tremolite. Each differs slightly in terms of properties such as acid resistance, strength, and flexibility, and because of this were used in different ways. Chrysotile, for example, was the most flexible, and was the most common type of asbestos used in American construction materials. Chrysotile was once believed to be safe, but long-term health studies on workers exposed to chrysotile have shown that this is not the case.
Asbestos is only dangerous when it is inhaled. If there is asbestos siding on your home, you're not at risk just because the asbestos is there. Intact asbestos that doesn't shed fibers is safe as long as it is left undisturbed, because fibers are a health risk only when airborne. The level of risk depends on the condition of the material–if it's intact and in good condition, the risk is low.
Am I at Risk of Exposure?
Those most at risk of exposure work or have worked with or around asbestos. People in many different industries are affected, either because they worked with asbestos, or because their work–place contained machinery with asbestos–containing parts, asbestos insulation, or other materials. This can include construction workers, ship–yard and ship workers, and many types of industrial workers.