People exposed to low but persistent doses of radiation face an increased risk of cancers of all types, with an even greater risk of developing leukaemia, according to a new report.
While the study looks only at nuclear industry workers, airline flight crews and people exposed to high levels of radon gas in their homes face a similar risk, according to experts.
The study of nuclear industry workers, published today in the British Medical Journal is compiled by the WHO's International Agency for Research on Cancer in Lyon (IARC).
It included more than 407,000 workers in 15 countries.
The research project involved mainly men employed for at least a year in nuclear power plants and included a long follow-up period, averaging 13 years.
The study compared radiation-dose with deaths from all cancers and took into account factors such as age, length of employment and socio-economic status.
The researchers found that exposures at the limits set for nuclear workers, would lead to a 10 per cent increased risk of death from all cancers, excluding leukaemia. The risk of death from leukaemia increased by 19 per cent.
On this basis, the scientists believe that 1 to 2 per cent of deaths from cancer in these workers were attributable to their radiation exposure, even though the exposure did not exceed recommended limits.
Yet airline flight crews typically receive higher radiation doses when on the job than nuclear industry workers, according to Dublin Institute for Advanced Studies emeritus professor, Denis O'Sullivan.
"On average they get 30 per cent more radiation exposure," he said yesterday.
Prof O'Sullivan headed an EU- funded study of radiation exposures to flight crews and has done research in the area for many years.
The risk was not to passengers but to flight crews who spent long periods of time at high altitudes, increasing their exposure to cosmic radiation.
The new IARC study was in keeping with assumptions that risks increased with exposure, even at low levels, he said.
He cited a Scandinavian study of flight crews, published last year, that suggested these staff faced risks similar to workers in the nuclear industry.
Yet similar doses can be received in homes found to have high radon gas levels, according to Radiological Protection Institute of Ireland principal scientific officer, Dr Tony Colgan.
"It brings home to me that the radiation doses involved here are the radiation doses we receive at home from radon," he said.
A person living in a home with high natural levels of radon gas faces radiation doses comparable to nuclear workers.
The study was conducted by a highly reputable group. "It seems to be a reasonably good measure of the risks involved," Dr Colgan added.
The study supports the idea that there is no safe threshold for radiation exposure, according to the head of natural radiation studies at University College Dublin, James McLaughlin.