Risk factors and causes of mesothelioma
Asbestos is the most common cause of mesothelioma. Up to nine out of ten cases of mesothelioma (90%) are caused by exposure to asbestos fibres.
Asbestos is a natural mineral found in many countries. It acts as an insulator (to keep heat in and cold out) and it protects against fire and corrosion.
There are three main types of asbestos: blue (crocidolite), brown (amosite) and white (chrysotile). These were used in UK industries until the ban on imports of blue and brown asbestos in the 1980s and on all types in 1999. Exposure to blue and brown asbestos is commonly linked with mesothelioma. However, exposure to all types of asbestos is harmful.
Mesothelioma doesn’t usually develop until many years after exposure to asbestos. It can take any time from 10–60 years, although the average is about 30–40 years after exposure.
When asbestos is disturbed or damaged, it releases tiny fibres that can be breathed into the lungs. Asbestos fibres are very fine and can make their way into the smallest airways of the lungs. Once the fibres are in the lungs, the body’s defence mechanisms try to break them down and remove them. This leads to inflammation in the lung tissue.
The asbestos fibres can also travel through the lung tissue to settle in the outer lining of the lung (the pleura). Over many years they can cause mesothelioma or other lung diseases to develop.
Asbestos fibres can also be swallowed, and some of the fibres can stick in the digestive system. They can then move into the outer lining of the abdomen (the peritoneum). Here, they cause swelling and thickening of the lining and can lead to peritoneal mesothelioma.
Exposure to asbestos
People most likely to have been exposed to asbestos at work include:
joiners and construction workers
As these jobs were mostly done by men, mesothelioma is five times more common in men than in women.
People who haven’t worked directly with asbestos can also sometimes develop mesothelioma. These can include:
family members of people who’ve worked with asbestos and brought the dust home on their clothes
people who lived near asbestos factories
people who worked in buildings containing asbestos materials that were disturbed or damaged.
Occasionally, mesothelioma develops in people who have never been exposed to asbestos.
The other causes of the disease are not fully understood, but, in rare cases, mesothelioma has been linked to exposure to radiation. A mineral called erionite, which has been found in Turkey and North America, has also been linked to mesothelioma.
Mesothelioma isn’t infectious and can’t be passed on to other people. It isn’t caused by inherited faulty genes, so family members don’t have an increased risk of developing it, unless they have also been exposed to asbestos.