According to new research published in the British Journal of Cancer, one in 17 British carpenters born in the 1940s will die of mesothelioma, a cancer that forms in the cell membrane lining the lungs and other organs, and most commonly associated with long-term exposure to airborne asbestos.

Malignant mesothelioma is a highly aggressive tumor that has a tendency to grow rapidly and after diagnosis the cancer is difficult to control, and there is no cure.

In the largest global study of its kind, more than 600 patients with mesothelioma and 1,400 healthy people were interviewed to examine rates of the disease linked to different occupations.

The researchers calculated that men born in the 1940s who worked as carpenters for more than 10 years before they reached 30 have a lifetime risk for mesothelioma of about one in 17. For plumbers, electricians and decorators born in the same decade who worked in their trade for more than 10 years before they were 30, the risk is one in 50 and for other construction workers one in 125.

For every case of mesothelioma, asbestos also causes about one case of lung cancer so the overall risk of asbestos related cancer for this particular group of carpenters is about one in 10.

The risk was also increased in other industries and the study showed that two-thirds of all British men and one quarter of women had worked in jobs involving potential asbestos exposure at some time in their lives. There was also a small increased risk in those who had lived with someone who had been exposed to asbestos.

The risk of mesothelioma for the rest of the UK population who have not experienced these occupational exposures is about one in 1,000 and these apparently unexposed cases account for 60 per cent of all mesothelioma in women and 15 per cent in men.

Professor Julian Peto, lead researcher said: "The UK has the highest death rate from mesothelioma in the world. The risk is highest in people who were exposed to asbestos before age 30. By getting information on all the jobs people had ever done we have shown that the risk in some occupations, particularly in the building industry, is higher than we previously thought.”

"New regulations introduced in 1970 reduced exposure to asbestos in factories but heavy exposure to the much larger workforce in construction and various other industries continued."

Steve Coldrick, Head of HSE's Disease Reduction Programme, said: "The Health and Safety Executive and Cancer Research UK commissioned this research to learn more about the impact of asbestos related cancers upon our workforce, but particularly for those born in the 1940s who have potentially been more exposed to asbestos than later born tradesmen.

"We must continue to remember that asbestos maintained in good condition on-site is not a threat unless it's disturbed and the fibers become airborne. Also, other potential 'risk factors' such as residence in certain types of housing, living near industrial sites, or engagement in DIY activity, were not associated with an increased risk."

"In 2010, the second part of this research should provide more information about the role of amosite in causing mesothelioma in the younger generation. This is underway now and will provide valuable information about the extent of recent exposure levels (compared to past exposure levels) on our future tradesmen."

There are three main types of asbestos, white, blue and brown. White asbestos was the type most commonly used in the UK. Blue asbestos was not used in Britain after 1970, but the use of brown asbestos continued into the 1980s, and carpenters often cut and drilled brown asbestos insulation board with power tools. The researchers believe this was a major factor underlying Britain's mesothelioma epidemic.

There are just over 2,100 people diagnosed with mesothelioma in the UK each year with about five times as many cases in men as in women.

Dr Lesley Walker, Cancer Research UK's director of information, said: "This research is important in revealing who is at greatest risk from asbestos exposure. We now need to ensure that accurate information for workers and regulation of the asbestos still in buildings keeps pace with what we’ve learned."
References:
1. Cancer Research UK.
2. Image by Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist.