What Causes Mesothelioma?
Mesothelioma is almost exclusively caused by exposure to asbestos. In fact, to date, almost every patient who has been diagnosed with the malignant form of mesothelioma has been exposed. Exposure is often occupational, but it is also possible that it is environmental, or even through secondhand exposure. It is estimated that 90% of all mesothelioma cases can be traced back to asbestos exposure.
What Is Mesothelioma?
Mesothelioma is a rare but very aggressive form of cancer that usually attacks the lining of the lungs (pleural mesothelioma) or abdomen (peritoneal mesothelioma). It can also occur in the lining of the heart (pericardial mesothelioma) or the testicles (testicular mesothelioma) but these are rarer than instances of pleural and peritoneal mesothelioma. In the past, this cancer was incredibly uncommon. However, after the industrial revolution, asbestos became more widely used, and the incidences of mesothelioma rose with it.
It took quite a number of years of medical research to pinpoint exactly what the cause of mesothelioma was. However, a fact sheet has now been released by the National Cancer Institute that clearly demonstrates the cancer risks associated with asbestos exposure.
This was further explained by the International Agency for Research on Cancer (IARC) at the World Health Organization conference in March 2011. Here, they highlighted what the exact evidence is and, since then, this evidence has strengthened significantly. It is now accepted as fact that all types of asbestos, and all lengths of fibers, can cause cancer in humans. In 2009, the IARC had confirmed this for chrysotile asbestos, but it is now known that it is true across the board.
What Is Asbestos?
For many years, asbestos was considered to be a miracle mineral, but it is now dubbed as the killer mineral. It is found naturally in a lot of countries and was found to be useful because of its insulating properties. Not just that, it protects materials from corrosion and fire. While there are various forms of asbestos, three forms are the most common. These are:
• Crocidolite or blue asbestos
• Amosite or brown asbestos
• Chrysotile or white asbestos
Asbestos was banned in this country in 1989, although federal regulations on asbestos continue to be quite confusing to many. This is mainly due to the fact that the evidence supporting the link between mesothelioma is strongest with blue and brown asbestos, which has led to some manufacturers continuing to use white asbestos.
One of the biggest problems is that the latency period for mesothelioma is incredibly long. Few people develop it within 10 years of having been exposed, and it is more common for it to happen up to 40 years or even more afterwards.
Will Everyone Develop Mesothelioma After Exposure?
Absolutely not. It is not yet quite understood how much exposure to asbestos is required for mesothelioma to develop, particularly since some people don’t develop it despite heavy exposure while others develop it after a relatively short exposure. What is known is that there are some risk factors that increase a person’s chances of developing it. These include:
• Working in an asbestos mine or processing plant
• Working in an occupation classed as high risk, including dry wall insulation, boiler rooms, shipyards, and the construction industry
• Having been in the military, particularly in the U.S. Navy
• Living in areas close to asbestos mines
• Accidentally disturbing asbestos, either in a residential setting or as part of your occupation
Understanding Pleural Mesothelioma
The most common form of mesothelioma is pleural mesothelioma, which affects the lungs. This happens when people inhale the asbestos fibers. These fibers are microscopic and can get into the smallest of the airways. Once they are, the body tries to remove them by breaking them down. This causes the lung tissue to become inflamed. If there is some damage to the lung, it is possible for the fibers to reach the outer lung lining. Both can lead not just to mesothelioma, but also to asbestosis and lung cancer.
Understanding Peritoneal Mesothelioma
The second most common type is peritoneal mesothelioma, which happens on the lining of the stomach. This is caused by ingesting asbestos fibers, sticking anywhere in the digestive system. They will eventually travel to the peritoneum, which is the outer lining of the abdomen, leading to swelling and thickening and, possibly, mesothelioma.
How Risky Is Exposure to Asbestos?
Asbestos exposure was particularly common in shipbuilders, boilermakers, electricians, plumbers, construction workers, and joiners. These were male dominated professions and this is why mesothelioma is five times more likely to occur in men than in women. However, this doesn’t mean women are immune to the condition. In fact, the following people have been known to develop mesothelioma as well:
• Relatives of people who have occupational exposure and carry the fibers home in their hair or clothes
• Residents of areas near asbestos mines or factories
• People who lived or worked in buildings where asbestos was present and it got damaged or disturbed
When Mesothelioma Is Not Caused by Asbestos
As stated, mesothelioma can be traced back to asbestos exposure in 90% of cases. Thus, 10% of cases cannot be linked to asbestos. These cases are often very poorly understood, although some research are currently being conducted regarding such cases. Mesothelioma in itself is not a contagious disease but, as stated, can be developed as a result of secondary exposure to asbestos and, potentially, to other products now believed to be linked to mesothelioma.
Some of the situations that are now believed to be linked to mesothelioma are outlined below.
1. Exposure to Mineral Fibers
It is known that mesothelioma is caused by exposure to asbestos, which is a mineral. As such, it stands to reason that other minerals have the potential to do the same. One such class of minerals is the group of minerals known as zeolites, which have strong chemical similarities to asbestos. In one region of Turkey, there are significantly higher rates of mesothelioma than anywhere else in the world, and it is now suggested that this is because they work with erionite, which is a zeolite and is used as a building material. Further research have to be conducted to confirm this.
2. Radiation Exposure
There is some evidence that radiation exposure may lead to mesothelioma. However, the data on this is inconsistent and rare. What is known is that there are a number of studies that have shown people who have had radiation therapy to treat different forms of cancer are more likely to develop mesothelioma.
3. Simian Virus 40 Contaminated Polio Vaccines
Some research have been completed on the effects of Simian Virus 40 contaminated polio vaccines. This happened between 1955 and 1963, and those who had those vaccines were found to be more likely to develop mesothelioma. There is no clear and determined link to prove correlation, although more studies are being conducted. Some scientists suggest that the disproportionally large number of people in the 1955-1963 age group were also more likely to be employed in some form of asbestos industry, and that this is the real connection.
Mesothelioma is a very rare form of cancer, even in those who have had significant asbestos exposure. As a result, scientists have researched genes as well, trying to determine whether genes have a role to play. What they found was that people with a mutated BAP1 gene were more likely to develop mesothelioma if they had asbestos exposure. Interestingly, they are also more likely to develop eye melanomas.
5. Gender and Age
It is known that mesothelioma is more likely to occur in men. This is mainly due to the fact that the industries in which high levels of asbestos were present were strongly male dominated. Additionally, because of the long latency period, it is unlikely for mesothelioma to develop in someone younger than 45. That being said, gender and age are not likely to be directly linked to mesothelioma. Instead, it is simply more likely to be found in elderly men.
What About Smoking?
There have been significant cases of research that have demonstrated that smoking does not increase the chances of developing mesothelioma. However, a strong link between asbestos, smoking and lung cancer has been observed. If smokers are exposed to asbestos, they are 90% more likely to develop lung cancer later on in life. Furthermore, smoking makes asbestosis worse and makes it more difficult for the lungs to get rid of foreign bodies.
Last but not least, it is vital to understand that causes and risk factors are not the same thing. For instance, men are more likely to develop mesothelioma than women, making it a risk factor. Being a man, however, doesn’t cause mesothelioma. Sometimes, it is difficult to determine what is a risk factor and what is a cause. The most likely cause of mesothelioma is asbestos. The link between asbestos and mesothelioma is so strong that other elements are not likely to be classed as a cause of the condition.