By Tim Whewell
BBC Radio 4, File On 4
Occupational cancer is a quiet almost invisible epidemic picking off its victims years after they were first exposed to the risk.
The HSE is responsible for workplace safety
It is one of the areas of workplace safety that the Health and Safety Executive (HSE) is responsible for.
Yet according to a new study published on Tuesday its occupational cancer figures are out of date.
The HSE's figures say 6,000 people die annually of work related cancers.
But the study by Prof Andrew Watterson of Stirling University has found that between 18,000 to 24,000 people a year die of occupationally caused cancers.
"We know that the existing figures are wrong because of the basis of the calculation that was done some 25 years ago," he said.
"They looked at small number of - at that time - large industries. There are many more small to medium sized enterprises now where there may be exposures."
The HSE accepts its figures are out of date but the academic charged with reviewing them, believes they will only show a small increase.
Lesley Rushton of Imperial College said: "Because we are adding more cancers the estimates will rise."
But he added that figures for the six cancers in the HSE's original research will not differ greatly.
One of the newer industries Professor Watterson believes the HSE's data does not take into account is microelectronics.
Eleven years after Grace Morrison left the National Semiconductor factory in Greenock, near Glasgow she still has no explanation for what she and many other former workers saw as a cancer cluster in the area.
Grace was diagnosed with cancer and in the same week her sister, who also worked at the plant was found to have leukaemia which eventually claimed her life.
"It was a dreadful time my sister endured two years of hell with the treatment she was having.
"She survived two years and I'm still in remission."
Eventually after a local campaign, the HSE agreed to look into complaints by the firm's employees.
One theory was their cancer stemmed at least partly from exposure to some the chemicals the workers added to tiny silicon discs as part of the microchip production process.
The HSE's 2001 report found two to three times the expected rate of female lung cancer and four to five times the expected rate of female stomach cancers.
It found no immediate proof of a link but said further study was needed urgently yet this work only began this year.
Minutes of meetings of the Microelectronics Working Group, which brings together industry representatives, trade unions, and the HSE, obtained by File On 4 indicate disagreements between the various sides that may help explain the delay in starting the more detailed follow-up study.
One, for example, was over the remit of the new research, with National Semiconductor apparently wanting it limited to lung cancer.
The company declined a request for an interview, but in a statement they said: "There is NO proof that working at National Semiconductor in Greenock has caused an increased risk of employees developing cancer
"Although we have had some concerns regarding the HSE's proposed follow-on study, we have worked closely with the HSE to provide timely comments and information to them.
"National Semiconductor is continuing to work with the HSE on its follow-up study and until this study is completed it would be inappropriate for us to comment further.
"The health and safety of our employees is of paramount importance and we remain committed to providing a safe working environment.
"This is highlighted by the numerous awards secured by the company from organisations such as the Royal Society for the Prevention of Accidents and the British Safety Council and National is one of the top Environmental Health and Safety performers in the UK."
Steve Coldrick, head of the HSE's disease reduction programme, denied that the micro electronics industry was slow to agree to cooperate with in depth studies.
"The key point is the follow up is a further study so it is not an enforcement action," he said.
"It requires the co-operation and collaboration of the people concerned and the follow up study has started.
"You are talking about six years, but it is determining at the rate of other people as well.
"If other people do not think it is urgent and we have no regulatory force behind it, we are dependent on the pace at which they will go."
You can learn more about this story from File On 4, at 2000 BST, Tuesday 9 October 2007, repeated Sunday 14 October 1700 BST.