Asbestos and mesothelioma

Asbestos
It is known that asbestos causes most cases of pleural mesothelioma. The risk is greater if a person was exposed to large amounts of it from an early age for a very long period of time. Many people with peritoneal mesothelioma have also been exposed to asbestos. 
A link between asbestos and lung disease has been noted since the beginning of the 18th century. But the link with mesothelioma has only been known since the 1960's. The number of cases of mesothelioma in the UK each year is expected to rise sharply for the next few years, because of the heavy use of asbestos in industry from the end of the second world war up until the mid 1970s.
Asbestos

It is estimated that in the UK, more than 90% of men with mesothelioma, and more than 80% of women, have been in contact with asbestos. But some people say they have no history of any exposure to asbestos.
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. A specialist doctor or nurse may be able to give you some information. Or some of the mesothelioma organisations can help and advise patients.

What is asbestos?
Asbestos is an insulating material which is heat and fire resistant. In the past, asbestos was used widely in the: 
  • Building industry
  • Ship building industry
  • Motor industry
  • Manufacture of household appliances
  • Power stations
  • Telephone exchanges

Therefore, 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 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 men 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 second word war (after 1945). Mesothelioma may not develop until 15 to 60 years after somebody has been exposed to asbestos, which is why there has been an increase in cases in recent years. The number of people dying from mesothelioma each year is expected to peak around 2016, and then start decreasing. 
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.
The 3 different types of asbestos 

How asbestos causes mesothelioma
Asbestos is made up of tiny fibres. Someone can breathe these fibres in when he comes into contact with asbestos. The fibres work their way into the pleura, lining the lung. They irritate the pleura and can cause gene changes (mutations) which 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 someones has been exposed to asbestos, his/her family may also have been exposed. Asbestos fibres can be carried home on people's clothes. Research studies have confirmed that the families of people exposed to asbestos also have a higher risk of developing mesothelioma.
Schematic diagram of how asbestos causes 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. But this is not completely clear.
Some people have been found to be exposed to polio vaccines contaminated with SV40 virus between 1955 and 1963 in some countries, including Britain. 

Radiation
Pleural and peritoneal mesothelioma has been shown to develop after exposure to radiation from a chemical called thorium dioxide (Thorotrast). This chemical 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 erionite (a type of Zeolite fibre) has been shown to cause mesothelioma. 

Working as a painter has been linked with an increased risk of mesothelioma possibly due to chemicals in the paint.

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