Asbestos is the name given to a group of minerals that occur naturally in the environment as bundles of fibers that can be separated into thin, durable threads. These fibers are resistant to heat, fire, and chemicals and do not conduct electricity. For these reasons, asbestos has been used widely in many industries.
Chemically, asbestos minerals are silicate compounds, meaning they contain atoms of silicon and oxygen in their molecular structure.
Asbestos minerals are divided into two major groups: Serpentine asbestos and amphibole asbestos. Serpentine asbestos includes the mineral chrysotile, which has long, curly fibers that can be woven. Chrysotile asbestos is the form that has been used most widely in commercial applications. Amphibole asbestos includes the minerals actinolite, tremolite, anthophyllite, crocidolite, and amosite. Amphibole asbestos has straight, needle-like fibers that are more brittle than those of serpentine asbestos and are more limited in their ability to be fabricated.
Even though asbestos is now banned, people working in the construction industries, maintenance or demolition could still come into contact with asbestos dust, putting their health in danger. Exposure to asbestos is a risk, whether tradespeople are working on domestic or industrial premises.
Diseases caused by contact with asbestos include mesothelioma (a type of cancer that affects the membrane around the lung) and asbestos-related lung cancer.
Asbestos lung cancer is a rare type of lung cancer, which is the most common cause of cancer death in the United States. An estimated 4,800 deaths a year are linked to this illness, a number that represents about 4 percent of all U.S. fatalities connected to cancer of the lungs. The overwhelming majority of other deaths — about 90 percent — are linked to smoking.
Medical researchers first made a probable causal relationship between exposure to asbestos and lung cancer in 1935. Seven years later, a member of the National Cancer Institute confirmed asbestos as a cause of lung cancer. Study after study continued to show the cause-effect relationship of asbestos and lung cancer. The Occupational Safety and Health Administration (OSHA) in 1986 proclaimed lung cancer as the greatest risk for Americans who worked with asbestos.
Like mesothelioma, another asbestos-related cancer, lung cancer associated with asbestos is typically diagnosed at a late stage of development because of the long latency period of development and the onset of symptoms.
Both take decades to develop, but only months to spread to distant organs. They have similar diagnostic procedures and treatment techniques; however, the diseases differ in physical characteristics and non-asbestos risk factors.
Companies and manufacturers have mined and used asbestos, a naturally occurring mineral, for commercial purposes in North America since the late 1800s. It is now highly regulated and a number of countries, including U.S. government agencies, classify it as a human carcinogen. When someone disturbs an asbestos-containing product, they release the microscopic fibers into the air. If inhaled, these thin fibers can become trapped in the lungs. Over long periods of time, they can accumulate and cause inflammation, scarring and other critical health problems. In some cases, the fibers can even trigger the development of lung cancer.
Researchers report the duration and concentration of asbestos exposure plays a role in the risk of developing lung cancer. The Helsinki Criteria states the risk for lung cancer increases as much as 4 percent with each year of exposure. OSHA has demonstrated a clear association between the concentration of asbestos exposure and the risk of lung cancer, finding the higher the concentration of asbestos fibers, the higher the risk of lung cancer.
The implications of asbestos exposure are not apparent immediately following exposure. When asbestos fibers are first inhaled, they can become lodged in the lining of the lungs. The size of asbestos fibers affects where they become lodged, having implications on whether lung cancer or mesothelioma develops. Researchers discovered that 3mm fibers are more likely to become lodged in the lining of the lungs, whereas 5mm fibers (1/5 inch) tend to lodge in the lung tissue and increase the risk of developing lung cancer.
After many years, sometimes decades, these fibers cause enough irritation and cellular damage to generate tumor formation. Whether someone develops lung cancer, mesothelioma or asbestosis will depend on a person's health, genetics, habits and the duration and concentration of exposure.
Workers in certain trades and professions, most of them industrial, carry elevated risks of developing asbestos-related lung cancer. Shipyards, which have notoriously poor safety records, exposed workers to widespread asbestos until the mid-1970s. Many employees rarely wore necessary protective gear, and nearly all shipyard workers placed themselves at risk for lung cancer, asbestosis and mesothelioma.
But shipyards workers are hardy the only trade considered high risk for this type of lung cancer. Any occupation in which people are in a confined area where asbestos is present — or where asbestos dust is circulated — is dangerous.
Those occupations include: Auto mechanics, Construction workers, Insulation installer , Roofers , Tilers, Plumbers , Paper mill workers , Textile workers , Sheet metal workers , Toll collectors , Linotype technicians .
Prognosis and Survival Rates
The prognosis and survival rate for someone with lung cancer related to asbestos differs by type and subtype of the disease and also by the stage at which the cancer is found. Overall, the median survival for a limited stage small cell patient, with combination chemotherapy, is 16 to 22 months. For patients with extensive stage cancer, the median survival is nine to 11 months with the same treatment.
A 2008 review of medical literature found that adenocarcinoma is almost always associated with longer survival times. A 2011 study agreed with these findings, reporting that adenocarcinoma patients lived a median of 8.4 months while all other NSCLC patients lived a median of 8.1 months. While the difference is small, researchers believe it to be significant.
Source : www.asbestos.com/