Asbestos is a silicon-based mineral considered hazardous and carcinogenic to people. Asbestos has been used by people throughout history due to its unique characteristics, which include excellent tensile strength and insulating ability, and resistance to fire, heat, electricity and many corrosive chemicals. Exposure to asbestos has been proven to cause debilitating and life-threatening diseases.
History
Asbestos was used at least as far back as the ancient Greeks, who used it in insulation and garments, and supposedly even coined its name. In the modern era, asbestos became popular with builders in the late 1800s and was used in roof shingles, ceiling tiles, mixed cement, automobile brakes and heat-resistant materials until the late 1970s, when it was removed from many products.
Types
Asbestos exists in nature as six different types of fibers, all of which are hazardous in people. The two major groups of asbestos fibers are serpentine, which are generally long and curly, and amphibole, which are all straight and needle-like.
Significance of Exposure
Asbestos exposure usually occurs from breathing in the fibers, which can become caught in the trachea, bronchi, lungs and surrounding internal tissues. The fibers then cause irritation and inflammatory reactions, which can develop into fibrosis, cell death and cancerous processes. Swallowed asbestos fibers are not as hazardous, but they are thought to cause gastrointestinal symptoms and allergic reactions.
Asbestos Causes Lung Cancer
The National Cancer Institute cites that asbestos is considered a carcinogenic material by many agencies, including the U.S. Environmental Protection Agency, the U.S. Department of Health and Human Services and the International Agency for Research on Cancer. According to NCI, studies show that asbestos exposure via inhalation dramatically increases the odds of malignant lung cancers and benign lung tumors. Lung cancers induced from asbestos exposure usually develop in the bronchi, although the trachea, bronchioles and alveoli are also potential sites. Malignant lung cancer, often of the small-cell type, has high mortality rates because it spreads through the body via the bloodstream and lymphatic system.
The Agency for Toxic Substances and Disease Registry notes the odds of lung cancer being induced from asbestos exposure are far more likely when combined with cigarette smoking. The agency cites that asbestos-exposed people who smoke increase their odds of lung cancer between 50 and 84 times.
Asbestos and Mesothelioma
Mesothelioma is cancer of the thin membranous tissues called the mesothelium, which line the chest, abdomen and internal organs. Mesothelioma is the most prevalent cancer associated with asbestos exposure, as cited by Mesothelioma.com. Asbestos is the predominant cause of mesothelioma, although inhalation of fiber glass can cause similar effects. Pleural mesothelioma in the linings of the lungs is the most common type and potentially the most life-threatening. Mesothelioma progresses slowly over years and initially has only minor symptoms, which makes it difficult to diagnose.
Other Potential Cancers
NCI warns that other types of cancer could be related to asbestos exposure, although more studies are needed. The institute mentions that the risks of gastrointestinal and colorectal cancers are most likely increased by asbestos exposure and possibly cancers of the throat, kidney, throat and gallbladder.
Asbestosis
Inhaling asbestos fibers does not always cause lung cancer or mesothelioma, but it will eventually cause asbestosis, according to MayoClinic.com. Asbestosis is fibrosis of the lungs from continuous irritation, inflammation and damage, which leads to scarring and the inability to expand the lungs, as noted by MayoClinic.com. Without proper expansion, breathing and gas exchange becomes inefficient. Asbestosis also takes years to progress, and in some cases, is merely a precursor to malignant lung cancer and mesothelioma.
