Formerly valued for its material properties, asbestos is now widely recognized as a human health hazard. Asbestos is the name given to a type of naturally occurring silicate minerals. It is made up of microscopic bundles of fibers. If materials containing asbestos become damaged, the fibers may be released into the air where they may be inhaled. Once present in the lungs, asbestos fibers may cause serious health problems.
Asbestos is a good thermal and sound insulator and was often included in building materials until its dangers were discovered. Its use is now banned in about 60 countries around the world. However, many products containing asbestos still exist. What is more, the lung diseases caused by asbestos fibers may take many years to develop. It can therefore be difficult to prove whether asbestos caused the disease when it comes to claiming compensation for an occupational exposure. And there will probably be many more cases of asbestos-related disease in the future.
Historical Background and Scientific Foundations
Asbestos is not a single material, nor is it used on its own. The term refers to a group of fibrous silicate minerals with good sound and thermal insulation properties, good heat resistance, and high strength. There are several types of asbestos, with the three most significant being chrysotile, crocidolite, and amosite. Chrysotile, often known as white asbestos, is made up of long, thin, flexible fibers that form scroll-like structures. Crocidolite and amosite are known as blue and brown asbestos, respectively, and have a less defined physical structure.
Asbestos is cheap and this, with its combination of attractive physical properties, made it increasingly popular for insulation, fireproofing, roofing, and flooring from the early twentieth century onward. When asbestos is added to a material, it makes it both strong and fireproof. Asbestos is therefore found in more than 3,000 different manufactured products, including roofing felt, ceiling and floor tiles, automobile parts such as disc-brake pads and clutch facings, protective clothing, and various types of cement. The majority of asbestos-containing products are related to building. The use of asbestos peaked in the 1960s and early 1970s, and premises built or refurbished during this time are likely to contain some form of it.
Impacts and Issues
Asbestos fibers consist of bundles of microscopic fibers that may be released whenever the material is handled, during mining, manufacture, construction activities, transport and use, or disposal. These microscopic fibers form an aerosol, which is readily inhaled. Fibers with a diameter of three micrometers, or less, may become embedded in the lung—either in the upper airways or lower down in the alveoli, where gas exchange with the blood takes place. The fibers of chrysotile asbestos are more likely to break down and dissolve, while those of amosite and crocidolite tend to persist. The fibers can be removed by several natural biological processes—for instance, white blood cells from the immune system engulf them and carry them away from the lungs. However, some fibers persist and cause lung disease. White asbestos appears to be less dangerous than the blue or brown forms.
Many studies have shown that there are three different lung diseases that can be linked to asbestos exposure. Asbestosis is a serious, progressive lung disease caused by scarring of the lungs by asbestos fibers. Symptoms include shortness of breath and a characteristic crackling sound on inhaling. There is no treatment for asbestosis.
WORDS TO KNOW
AMOSITE: The brown form of asbestos.
ASBESTOS: An incombustible fibrous mineral once commonly used for fireproofing and electrical insulation.
CHRYSOTILE: The white form of asbestos, which is less deadly than the blue or brown form.
CROCIDOLITE: The blue form of asbestos.
Lung cancer is also more likely among those who have been exposed to asbestos, and it is the most common of the asbestos-related diseases. Finally, most cases of the rare cancer mesothelioma have been linked to asbestos. Mesothelioma is a cancer of the membrane that lines the lungs, chest, and heart; it is responsible for around 0.04% of all deaths in the United States. All asbestos-related diseases are made worse by smoking, because it impairs the body’s defenses against asbestos fibers. Asbestos exposure causes around 10,000 deaths per year in the United States.
The health hazards of asbestos have been known for many years now, with the first case of disease being recorded in 1906, while the first case for compensation for disease caused by exposure was in 1929. Since then there have been thousands of such claims, only some of which have proved successful. Many countries have now intro-
duced a ban on making new products from asbestos and strict guidelines for managing existing asbestos. Whether known asbestos-containing material remains in place or is removed depends upon which is thought to pose the lesser risk to human health. The International Agency for Research on Cancer lists all three kinds of asbestos as a Group 1 carcinogen, which means that there is no safe limit and human exposure should be as low as possible.
EnvironmentalChemistry.com. “A Brief History of Asbestos Use and Associated Health Risks.” October 2004. http://environmentalchemistry.com/yogi/environmental/asbestoshistory2004.html (accessed February 16, 2008)
World Health Organization. “Asbestos.” http://www.euro.who.int/document/aiq/6_2_asbestos.pdf (accessed February 12, 2008).