An investigation into clusters of cancer cases around Sellafield and Dounreay nuclear sites has found they were very unlikely to have been caused by radiation exposure.
A report from the Committee on Medical Aspects of Radiation in the Environment (Comare) said the clusters had gone.
It also found no evidence of a spike in thyroid cancers following the Windscale reactor fire in 1957.
The committee said rural population mixing may have been a factor.
Comare – an expert Department of Health committee – now wants more research to be carried out into the role that infection plays in the development of leukaemia and non-Hodgkin lymphoma.
It has been suggested that an infectious agent could be introduced into rural communities by an influx of people, triggering a rise in cases of these rare cancers.
Around 500 children under 14 develop leukaemia every year in the UK, making it the most common cancer among children.
Previous reports found an increased incidence of leukaemia and non-Hodgkin lymphoma in children and young adults under 25 years of age living in Seascale, a village near Sellafield on the west coast of Cumbria, and around Dounreay, on the north coast of Scotland.
These clusters of cases occurred between 1963 and 1990 – but the committee’s report concluded that radiation doses from the plants were too small to be the reason behind the excess cases.
No increase in cases and no new cases have been reported in children living close to either site between 1991 and 2006.
However, the cause of the clusters of leukaemia around Sellafield and Dounreay is still not clear.
The report also looked at the incidence of thyroid cancer around Sellafield, after high excess rates were found in Cumbria in those born between 1954 and 1958.
But any link with radioactive releases from the Windscale reactor fire in 1957 has been ruled out after similarly high rates were found for those born after the fire, who would not have been affected by the iodine gases released.
Prof Alex Elliott, past-chairman of Comare, said regulations around routine radiation processes at nuclear installations were very tight.
He said: “People shouldn’t worry about cancer risk from radiation.”
But he was concerned that data on national childhood cancers should be protected and continue to be made available to researchers studying disease rates.