A chemical commonly used in the manufacture of rubber products may cause cancer in workers regularly exposed to it, suggests research published ahead of print in Occupational and Environmental Medicine.
The researchers base their findings on higher than expected rates of certain cancers, and deaths from the disease, among men working at a rubber chemicals plant in North Wales.
They looked in particular for exposure to a chemical called 2-mercaptobenzothiazole, or MBT for short, which has been implicated in previous research as a possible cancer causing agent (carcinogen).
They looked at the death rates of employees, who had worked at the plant for at least six months, between 1955 and 1984, and diagnoses of cancer between 1971 and 2005.
Among all 2160 employees, 363 had worked in a job that would have exposed them to MBT.
Many of these workers had first been exposed to the chemical decades earlier, during the 1930s, 40s, and 50s. By the end of 2005, 222 of these employees had died, and 136 were traced who were still alive.
Based on national statistics for expected death rates, workers exposed to MBT were twice as likely to die of gut (large intestine) and bladder cancers.
Based on national statistics for expected new cases of cancer, they were also twice as likely to be diagnosed with bladder cancer, and four times as likely to be diagnosed with multiple myeloma (bone marrow cancer).
When compared with 1797 workers who had not been exposed to MBT during their employment, it emerged that the risks of cancer of the large intestine and multiple myeloma both increased significantly according to the amount of MBT exposure.
The authors say that further research in other groups of people exposed to MBT should be carried out to see if similar patterns emerge. "In the meantime, perhaps MBT should be handled with increased care as it may be a human carcinogen," they conclude.