Campaigners have called for new studies on cancer clusters near nuclear plants after a leaked report highlighted new concerns over radiation levels.
Protestors against nuclear plants say more research is needed
A government scientific committee found that the risk of cancer from radiation could be 10 times higher or lower than previously thought.
Opponents of the Sizewell and Sellafield nuclear sites say more research is needed on this.
The report calls for new cancer studies near the former Bradwell nuclear plant.
The leaked draft report of CERRIE - the Committee Examining Radiation Risks from Internal Emitters - says the risk of cancer from exposure inside the human body could be much higher than the international safety limits allow.
The report, due to be published in October, could provoke a rethink of the rules on exposure to radiation in nuclear plants such as Sizewell, Sellafield and Dounreay, said Rob Edwards, a writer on the New Scientist, who has followed the Sellafield story for 20 years.
He told BBC News Online: "If radiation is found to be more dangerous than we assumed, those engaged in cleaning up the radiation legacy of the nuclear industry particularly at Sellafield and Dounreay may be exposed to higher risks than they realised."
It may also lead to the re-examination of claims of possible cancer clusters near Sellafield and Bradwell.
"If it is confirmed that plutonium is 10 times more dangerous than previously thought that must increase the likelihood that radiation is to blame for the cluster of childhood leukaemias," he said.
Charles Barnett, chairman of the Shut Down Sizewell Campaign, said this report coupled with concerns over terrorist attacks on reactors should be a major blow to the nuclear industry.
"There should be an examination of cancer records in the Sizewell area," he said.
The former Bradwell Power Station is on the Essex coast
Janine Allis-Smith, of the anti-Sellafield group Cumbrians Opposed to a Radioactive Environment, said new research to find out whether the cluster of leukaemia cases near Sellafield was connected to the plant.
"I would hope they will look at it again. There should be more research," she said.
Jamie Reed, press officer for British Nuclear Fuels at Sellafield, said he could not comment on a leaked report.
He added: "Our workforce is one of the most heavily investigated workforces in the world.
"If there was any need to address any issues we would not be short of evidence. There are no health effects of working here."