The causal relationship between asbestos and respiratory illness has long been documented. Even in ancient times, slaves who worked within asbestos mines were devalued because of a curiously early death rate. In a modern sense however, the relationship between asbestos exposure and development of malignant mesothelioma, specifically, led to the federal ban on asbestos products. Unfortunately this did not happen until the late 1970’s and many were wrongfully exposed and still paying the consequences today. While asbestos exposure is the only known cause for all forms of mesothelioma, it does act within the body differently among pleural, pericardial, and peritoneal cases.
Pleural mesothelioma is the most common variety of the disease and is caused by inhaled asbestos fibers. When asbestos materials are disturbed, such as they often are in occupational settings, (chipping, grinding etc.) the fibers will release from their materials and become airborne. Once airborne, the fibers are available for human inhalation. While oftentimes you can see the asbestos "dust," some fibers are very small and are passed directly through the lung’s air sacs. At this point, their final destination is often within the thin layer of cells that covers the lungs in the chest cavity, known as the mesothelium. The shape of the fibers is such that they stick to the cell wall easily. The body may attempt to break down the fibers chemically, as it will do with foreign substances. However, because the fibers are so durable, they are highly resistant to chemical breakdown or expulsion otherwise. The fibers will cause a chronic irritation to the surrounding tissue, which eventually becomes inflamed and scarred. It is from this scar tissue that the cancer’s groundwork is laid.
Pericardial mesothelioma, while it is the rarest form of the disease, is still caused by asbestos exposure. It is how exactly the asbestos acts within the body that is somewhat in question. Cancer specialists believe that microscopic fibers inhaled through the lung are then absorbed into the bloodstream with the blood’s oxygen supply from the lungs. Because all blood will eventually pass through the heart, these fibers often become stuck in the pericardial layer of cells that encompasses the heart. From here the process of inflammation and scar tissue growth is similar to pleural mesothelioma.
Peritoneal mesothelioma is likewise caused by asbestos exposure, although it is not believed that inhaled fibers are solely to blame. It is possible to ingest fibers in food or drink that may have been in the vicinity. The fibers will often pass through the digestive system but ultimately become stuck in the peritoneum, a thin layer of cells that protects the abdominal cavity. The processes by which mesothelioma forms in this area are identical to pleural and pericardial mesothelioma varieties, with inflammation leading to scar tissue and tumor growth.
While it should be said that cases of mesothelioma have been found in patients with no known asbestos exposure history, these are very rare and generally considered to be medical anomalies.