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What causes mesothelioma?
Up to 9 out of 10 cases of mesothelioma are caused by exposure to asbestos. Asbestos is a natural mineral, mined from rock found in many countries. It is made up of tiny fibres that are as strong as steel but can be woven like cotton and are highly resistant to heat and chemicals. When asbestos is disturbed or damaged, it releases tiny fibres that can be breathed into the lungs and cause inflammation, a build-up of scar tissue (fibrosis) and sometimes cancer.
During the 1960s the first definite link between mesothelioma and asbestos was made. Asbestos is now known to be the most common cause of the disease.
Asbestos was very widely used in insulation materials, such as amosite insulation board, and building materials, including asbestos cement. Asbestos fibres are very fine and if they are breathed in they can penetrate to the smallest airways of the lung, so they cannot be breathed or coughed out. Once the fibres are in the lungs the body’s defence mechanism tries to break them down and remove them, which leads to inflammation in the lung tissue. The asbestos fibres can also penetrate through the lung tissue to settle in the pleura (the membrane around the lung).
The asbestos fibres can also be swallowed, and some of the fibres can stick in the digestive tract. They can then move into the membrane that lines the abdomen (the peritoneum), where they cause inflammation.
The people most likely to have been exposed to asbestos include construction workers, plumbers, electricians, boilermakers, shipbuilders and demolition workers. People who lived near to asbestos factories, or worked in buildings where asbestos was present have developed mesothelioma. Family members of people who worked with asbestos and brought the dust home on their clothes have also sometimes been affected.
There are three types of asbestos: blue, brown and white. Blue and brown asbestos, are most commonly linked with mesothelioma. Originally, white asbestos was not thought to be dangerous but recent studies have now shown that it is also harmful.
Mesothelioma does not usually develop until 10-60 years after exposure to asbestos and for this reason it is often difficult to discover the exact cause.
Rarely, mesothelioma develops in people who have never been exposed to asbestos. The other causes of the disease are not fully understood, but exposure to radiation has also in rare cases been linked to mesothelioma.
Research has not found any evidence that smoking increases a person’s risk of developing mesothelioma. It is also thought that exposure to other building materials such as fibreglass does not increase the risk.
Mesothelioma is not contagious and cannot be passed on to other people. It is not caused by inherited faulty genes and so children of people with mesothelioma do not have an increased risk of developing it, unless they have been in contact with asbestos.
source - www.cancerBACUP.org.uk
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