A new study that examines how the jobs of British workers affects their risk of cancer, concludes that over 8,000 cancer deaths a year in Britain, that is 5% of all cancer deaths, are linked to occupations, especially those involving shift work or exposure to carcinogens like asbestos and diesel engine fumes.
Over half of the work-related cancer deaths are in male construction workers, say the researchers. Lead author Dr Lesley Rushton, an occupational epidemiologist at Imperial College London, and colleagues, write about their findings in an open paper published online in the British Journal of Cancer on 19 June.
To calculate the impact of work on cancer cases and deaths, Rushton and colleagues use a list of work-related cancer-causing substances compiled by the International Agency for Research on Cancer (IARC).
For different types of cancer they estimate a risk exposure period (REP), and they reference national data sources such as the Labour Force Survey and Census of Employment to estimate the proportion of the population exposed to each cancer-causing agent in each relevant industry or occupation.
They calculate that about 13,600 new cancer cases in 2004 and over 8,000 cancer deaths in 2005 in Britain every year were linked to work-related risk factors.
Rushton told the press:
"The cancer with the greatest number of cases and deaths linked to work is lung – a disease which is hard to detect early and has poor survival. Over 30 occupational exposures have been identified by IARC as definite or probable lung cancer causing substances." She said the best way to beat lung cancer is prevention: smoking is by far the biggest risk factor, but workplace risks are also having an impact. (To put these figures in perspective, about 43,000 cancer deaths in the UK every year are smoking-related).
The biggest impact on these figures is from asbestos, which the researchers link to over 4,200 cancer cases in 2004, and other carcinogens such as diesel engine oil and silica that construction workers are exposed to. Although asbestos is no longer used in the construction industry, working in old buildings can still be a risk today. Also, because asbestos-related cancers take a long time to develop, the numbers are continuing to rise.
Rushton and colleagues estimate that after asbestos, the main work-related risk factors are:
Night shift: tied to around 1,960 cases of breast cancer in female night-shift workers.
Exposure to mineral oil: tied to around 1,730 cases of bladder, lung and non-melanoma skin cancers among workers in the metal and printing industries.
Sun exposure: linked to around 1,540 cases of skin cancer.
Exposure to silica: tied to 910 cancer cases.
Diesel engine exhaust exposure: tied to 800 cases.
The researchers suggest their estimates could be on the low side, as new work-related risk factors are found and our understanding of their effects improves. Plus, their analysis is based on 2004 figures, and there are more cases of cancer today than there were then.
They also note that some of these risks are not just work-related, for instance, asbestos is still present in some homes, and air pollution includes diesel engine exhaust.
Sara Hiom, director of information at Cancer Research UK, said the Health and Safety Executive has commissioned a study to review the evidence on cancer's link to shift work: at the moment it is only classified as a "probable cause of cancer".
"Once the review is complete in 2015, we will have a more definite understanding of the role it may play in influencing cancer risk," she said, adding that:
"At this point, we expect the government and employers to take fast and appropriate action to minimise the risks faced by workers and Cancer Research UK will be watching this closely."
However, she noted that a large proportion of the deaths documented in the study are from exposure to asbestos that occurred decades ago, and "improved safety measures should mean that in the next generation or so we will see this number tail off dramatically".