Exposure to a low level of radiation is linked to a small increase in a person's cancer risk, a study of nuclear power station workers found.
Power station workers are exposed to less radiation than in the past
An international team studied over 407,000 workers in 15 countries, who were followed up for around 13 years.
The British Medical Journal study estimates up to 2% of cancer deaths were due to radiation exposure.
But they said the increased risk did not apply to people living near to power stations.
Ionising radiation is a well known cancer-causing agent.
Current radiation protection recommendations are to limit occupational doses to 100 millisieverts (mSv) over five years and doses to the public to 1 mSv per year.
These guidelines were based mainly on data from survivors of the atomic bomb in Japan and the extrapolation of risks to the general population and radiation workers is controversial.
Researchers studied the thousands of nuclear industry workers in order to get a better idea of their risk.
Most were men and had been employed for at least one year in nuclear power production facilities, or in related activities such as research, waste management or fuel and weapons production.
Ninety per cent of workers were exposed to a cumulative dose of under 50mSv, and less than 1% over 500mSv.
Factors such as age, duration of employment, and socioeconomic status were taken into account when the researchers looked at the workers.
Just under 200 died from leukaemias, and 6,519 from other cancers.
The researchers say, that from their evidence, 1 to 2% of deaths from cancer among workers in this study may be attributable to radiation.
The risk estimates from the study are consistent with those used for current radiation protection standards, they say.
And they add that many of the workers in this study worked in the early years of the industry when doses tended to be higher than they are today.
Dr Colin Muirhead, of the Radiological Protection Division of the Health Protection Agency, who worked on the study, told the BBC News website: "This is what we expected to see, because even with a low dose of radiation, there would be a cancer risk.
He added: "The levels of exposure we saw in this study are much lower than were seen in Hiroshima and Nagasaki.
"In absolute terms, it is a fairly small increase in risk."
He said workers in the industry should be reassured by the study's findings.
"At an individual level it will make a very small difference."
And he said the results also fitted in with studies which had found no link between cancer risk and living near a nuclear power station.
"It's certain that for the population, exposure would be much lower than what we're talking about here.
"There is no inconsistency."
Professor John Toy, Medical Director at Cancer Research UK, said: "Radiation is a very well known carcinogen.
"This extremely large study shows an increased risk, albeit small, of cancer and most types of leukaemia associated with occupational low-dose radiation exposure."
He added: "The radiation risk estimates are statistically comparable with those used for current radiation protection standards.
"The nuclear industry must remain ever vigilant to ensure these standards are not breached and constantly endeavour to reduce the exposure of its workers to radiation."