Mesothelioma Risk Factors
Risk factors are substances or behaviors that increase the risk of developing a disease or condition. Different diseases and cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for developing a type of skin cancer and smoking is a risk factor for lung cancer. There are several known risk factors that make a person more likely to develop mesothelioma.
Asbestos: The primary risk for developing mesothelioma is through an exposure to asbestos. Asbestos is a naturally occurring substance that is found across the planet. Asbestos has been used in industries throughout history because of its strength and flexibility, and also its amazing ability to insulate and resist heat. As the link between asbestos and mesothelioma became more apparent, the use of this material has decreased. However, unfortunately up to 8 million Americans may already have been exposed to asbestos.
According to the EPA, as many as 750,000 schools and buildings across the country contain asbestos insulation. Many are at risk for occupational asbestos exposure. Especially miners, factory workers, railroad workers, insulation manufacturers, ship builders, gas mask manufacturers, and construction workers. Also, research has shown that family members of those exposed to asbestos at work have an increased risk of developing mesothelioma because of the very tiny asbestos particles are carried home on the clothes of the workers.
There are six different types of asbestos that are found naturally. Chrysotile asbestos, the sole member of the serpentine group, is the most common kind of asbestos. Chrysotile asbestos is still found in many buildings and other commercial products throughout the world today. Chrysotile asbestos is the only form of asbestos that is still mined in the present day, typically throughout Canada, Africa and the Soviet Republic. Unfortunately, because of its extensive use, chrysotile asbestos makes up most of the asbestos-related medical problems today. Chrysotile asbestos is generally white or green in color, and is regarded as being less friable and less likely to be inhaled than other asbestos, making it a less-dangerous form of asbestos.
Amphibole asbestos categorizes nearly all of the different forms of asbestos and is considered by physicians to be the more dangerous category of asbestos. It includes amosite, crocidolite, tremolite, actinolite and anthophyllite asbestos. These forms of asbestos are considered to be extremely dangerous, as their fibers are strong and stiff. Throughout history, amosite, or "brown asbestos" accounted for about 5% of the asbestos used in factories and buildings. Crocidolite is blue in color and is extremely resistant to chemicals. It is considered to be the most lethal form of asbestos, and is not typically used today in any industry.
When asbestos fibers are inhaled, they become embedded in mucus membranes inside the air passages, similar to how a small sliver becomes embedded in the skin. The long, thin, fibers are sharp, and cannot be cleared when they penetrate into the pleural lining of the lung and chest wall. These fibers will eventually cause mesothelioma.
Asbestos fibers can also damage cells of the lung causing asbestosis or lung cancer. The risk of lung cancer among people exposed to asbestos is increased by 7 times, compared with the general population. Indeed, asbestosis, mesothelioma, and lung cancer are the three most frequent causes of death and disease among people with heavy asbestos exposure. Peritoneal mesothelioma, which forms in the abdomen, may result from coughing up and swallowing inhaled asbestos fibers. Cancers of the larynx, pancreas, esophagus, colon, and kidney have also been linked to asbestos exposure, but the increased risk is not as great as with lung cancer.
The risk of developing mesothelioma directly relates to both how often the person is exposed to asbestos and how long these exposures last. People exposed at an early age, for a long period of time, and at higher levels of fiber density are most likely to develop cancer.
Although the risk of developing mesothelioma increases with the amount of asbestos exposure, it is clear that genetic factors also play a role in determining who develops the disease. This explains why not all persons exposed to high levels of asbestos particles develop mesothelioma.
Radiation: There have been a few published reports of pleural and peritoneal mesotheliomas that developed following exposure to Thorotrast (thorium dioxide). Thortotrast was used in the past by doctors for certain x-ray tests. Because Thorotrast was found to cause mesothelioma, it has not been used for many years.
Zeolite: A silicate material chemically related to asbestos, is common in the soil of the Anatoli, a region of Turkey. A few cases of mesothelioma have been described in this region which may have been caused by this mineral.
Tobacco: Although tobacco smoking has not been associated with the development of mesothelioma, the combination of smoking and asbestos exposure increases the chance of developing lung cancer by 50 to 90 percent.