Mesothelioma is considered a rare cancer affecting the mesothelial covering of certain body cavities and organs. Health experts agree that it will continue to rise because of the continued exposure of millions of individuals to the primary causative agent of mesothelioma – asbestos. Although the incidence of mesothelioma globally is estimated at 1 to 6 per 1 million individuals, the relatively long carcinogenesis or latency period of mesothelioma (often ranging from 20 to 50 years) means that the incidence can actually rise in the future especially in developing countries where asbestos is still used in various sectors of society.
While asbestos is the primary culprit, often cited as the source in more than 80 percent of cases of malignant mesothelioma, there are other possible causes. Additionally, certain factors have been identified which can play a significant role in the development of mesothelioma. These can include the following:
Roggli, Sharma, Butnor, Sporn, and Vollmer described in a 2002 study of the correlation between exposure to asbestos and malignant mesothelioma seen in 1,445 cases that asbestos is indisputably associated with mesothelioma development. In 2015, Gulati and Redlich published in the Current Opinion in Pulmonary Medicine journal that there are more than 125 million people all around the world who have been exposed to asbestos in their respective occupations. These figures all point to asbestos as the major culprit in mesothelioma.
The excellent insulating and sound-absorbing properties of asbestos made it a very important building material at the turn of the 20th century although its mining has been traced to 4,000 years ago. Asbestos also provided excellent fire resistance, electrical insulation, chemical resilience, heat resistance, average tensile strength, and overall affordability – qualities that were put to use especially in the shipbuilding and construction industries. As such, asbestos has been used in roofing ceilings, drywalls, cements, roof shingles, glues, wirings, and adhesives among other things.
It is for this reason that individuals who were directly involved with activities that involved raw asbestos or asbestos-containing materials or products have the highest risk of developing mesothelioma. These individuals include workers in construction sites, shipyards, power plants, chemical plants, boiler production facilities, automotive assembly plants and repair facilities, and insulation-production and manufacturing plants.
Individuals involved in building renovations, remodeling, or demolitions are also at an increased risk of developing mesothelioma. Asbestos fibers can become airborne through agitation or destruction of the asbestos-containing materials and thus inhaled if the proper personal protective equipment as well as other safety measures are not observed.
Aside from occupational exposure to asbestos, individuals can also be exposed to asbestos through other means. For example, family and other household members of individuals who worked with or around asbestos can also be exposed to asbestos.
Workers returning home unfortunately bring with them asbestos particles that may have clung to their work clothes, their hair, and any other material they use at the worksite and which they bring home.
It is important to understand that a dose-response relationship exists between asbestos and mesothelioma. This means that the greater amounts or doses of asbestos, the greater the risk of mesothelioma development. Asbestos is not absorbed nor broken down into smaller particles and as such has the tendency to accumulate. While a single exposure may only lead to a small dose of asbestos, it nevertheless can cause cellular damage. With repeated exposure, the amount of asbestos accumulates and the cellular damage gets worse.
When asbestos is inhaled, the microscopic fibrils of asbestos gets lodged in the mesothelial layer of the covering of the lungs, called the pleura. Here, the asbestos microfibrils can produce any one of four common pathologic processes that lead to mesothelioma. These include:
Whatever is the exact mechanism for the development of mesothelioma, one thing is certain: asbestos microfibrils disrupt normal processes of the cell which leads to the development of an entirely different progeny cell. This initiates the oncogenic cascade of mesothelioma.