Causes and risk factors of mesothelioma

Over 9 out of 10 cases of mesothelioma (90%) are caused by exposure to asbestos fibres. Asbestos is a natural mineral found in many countries.

There are three main types of asbestos:

• blue (crocidolite)
• brown (amosite)
• white (chrysotile).

These types of asbestos 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, brown and white asbestos is linked with mesothelioma.

Mesothelioma does not usually develop until many years after exposure to asbestos. It can take 15 to 60 years. But the average time for pleural mesothelioma to develop after exposure to asbestos is about 30 to 50 years. It may be less time for peritoneal mesothelioma.

People most likely to have been exposed to asbestos at work include:

• joiners and construction workers
• plumbers
• electricians
• boilermakers
• painters
• launderers
• dock workers and shipbuilders
• power station workers
• people who served on warships.

Mesothelioma is 5 times more common in men than in women. This is because when asbestos was used in these industries, it was mostly men who did these types of jobs.

People who have not worked directly with asbestos can also sometimes develop mesothelioma. This is called environmental exposure. For example, this might include:

• family members of people who have worked with asbestos and unknowingly might have brought the dust fibres home on their clothes
• people who lived near asbestos factories
• people who worked in buildings containing asbestos materials that were damaged or disturbed.

If you develop an asbestos-related illness, you may be entitled to certain benefits and compensation.

Sometimes, mesothelioma develops in people who do not know, or perhaps cannot remember, that they have been exposed to asbestos.

When asbestos is damaged or disturbed (often by hitting, rubbing or handling it), it releases tiny fibres. These fibres can be breathed into the lungs. Asbestos fibres are very fine and can get into the smallest airways of the lungs. Once the fibres are in the lungs, the body tries to break them down and remove them. This causes inflammation in the lung tissue, which can cause lung disease.

The asbestos fibres can also travel through the lung tissue and settle in the outer lining of the lung (the pleura). Over many years, these fibres can cause pleural mesothelioma or other lung conditions.

Asbestos fibres can also be swallowed, and some can get stuck in the digestive system. They can then move into the outer lining of the tummy (abdomen), called the peritoneum. Here, they cause swelling and thickening of the lining. This can cause peritoneal mesothelioma.