Mesothelioma Risks And Causes

How common mesothelioma is
Mesothelioma is quite a rare cancer, but it is becoming more common. Around 2,400 people are diagnosed with mesothelioma in the UK each year. There are about 5 times as many cases in men as in women. This is probably because many cases have been caused by exposure to asbestos at work. Mesothelioma in the chest (pleural mesothelioma) is much more common than mesothelioma in the abdomen (peritoneal mesothelioma).


Asbestos
We know what causes most cases of pleural mesothelioma. Around 1 in 10 people exposed to asbestos develop mesothelioma in the pleural membranes. Many people with peritoneal mesothelioma have also been exposed to asbestos. We have known of a link between asbestos and lung disease since the beginning of the 18th century. But the link with mesothelioma has only been known since the 1960's. Unfortunately, the number of cases of mesothelioma in the UK each year is expected to rise sharply over the next 20 years because of the heavy use of asbestos in industry from the end of the second world war up until the mid 1970s.


Between 7 and 8 out of every 10 people (70 to 80%) diagnosed with mesothelioma say they have been in contact with asbestos. Your risk is greater if you were exposed to large amounts of it from an early age for a very long period of time. But some people say they have no history of any exposure to asbestos.

Remember that many people who develop mesothelioma due to asbestos exposure may be able to claim compensation. It is important to talk to a solicitor about this as early as possible. Your specialist doctor or nurse may be able to give you some information. Or some of the mesothelioma organisations can help and advise you.

What asbestos is
Asbestos is an insulating material that is heat and fire resistant. In the past, asbestos was used widely in the

Building industry
Ship building industry
Manufacture of household appliances
Motor industry
Power stations
Telephone exchanges

So most cases of mesothelioma occur in men who have worked in manufacturing using asbestos or who have used asbestos products, particularly in construction or engineering. A recent UK study showed that risks are particularly high for metal plate workers (mainly in shipbuilding) and carpenters, and the risk is higher in people exposed to asbestos before the age of 30. This study estimated that 1 out of 17 British carpenters born in the 1940s and employed in carpentry for more than 10 years before the age of 30 would go on to develop mesothelioma. People who worked as plumbers or mechanics also have an increased risk.

Asbestos was widely used in the years after the war (after 1945). Mesothelioma may not develop until 15 to 40 years after you have been exposed to asbestos, which is why we are now seeing an increase in cases. The number of cases is expected to peak around 2020 and then start to go down.

There are three main types of asbestos - blue, brown and white. Blue and brown asbestos are strongly linked with mesothelioma. They have been banned since the late 1980's and cannot be imported into the UK. White asbestos is now also thought to be harmful. The use of all asbestos was banned in 1999 in the UK.

How asbestos causes mesothelioma
Asbestos is made up of tiny fibres. You can breathe these fibres in when you come into contact with asbestos. The fibres work their way into the pleura, lining the lung. They irritate the pleura and may cause gene changes (mutations) that lead to the growth of cancer. Some of the fibres that have been breathed in can be coughed up and swallowed. This is probably the cause of peritoneal mesothelioma.

If you have been exposed to asbestos, your family may also have been exposed. Asbestos fibres can be carried home on your clothes. Research studies have confirmed that the families of people exposed to asbestos also have a higher risk of developing mesothelioma.

The SV40 virus
Research has looked into a virus called SV40 (the SV stands for 'simian virus'). In people who have been exposed to asbestos, some studies have shown that contact with the SV40 virus makes it more likely that they will develop mesothelioma. So SV40 is thought of as a possible 'co-factor' for mesothelioma development. Some people in certain parts of the former USSR were exposed to SV40 virus by contaminated polio vaccines in the 1970's.

Radiation
Pleural and peritoneal mesothelioma has been known to develop after exposure to radiation from a chemical called thorium dioxide (Thorotrast). This was used until the 1950's in some X-ray tests.

Some studies show an increased risk of mesothelioma in people treated with radiotherapy for a previous cancer. But other studies show no increased risk. If radiotherapy does increase the risk of mesothelioma, this is likely to occur only in a very small number of people.

Other chemicals
A mineral found in Turkey called Zeolite has been shown to cause mesothelioma.