NUCLEAR workers exposed to relatively high levels of radiation over long periods of service before the 1980s may be at increased risk of circulatory disease, according to a new scientific study.

Prepared by Westlakes Scientific Consulting, the research was published online yesterday (Tuesday) in the International Journal of Epidemiology.

It focused on 65,000 individuals employed between 1946 and 2002 at sites operated by British Nuclear Fuels plc and its predecessors, including Capenhurst.

Professor Steve Jones, corresponding author of the study, said: “What we have shown is an association between relatively high levels of occupational exposure to radiation and mortality from circulatory system disease.

“However, we have not been able to take account of all the other possible causes of circulatory system disease. The possible biological mechanisms that might explain a link with radiation are tentative at best, and so the results of our analysis are not consistent with any simple causal interpretation.”

Michael Gillies, a statistician from the study team, said: “Other factors associated, for example, with diet, exercise, socioeconomic status, shift working and stress, may be responsible.

“This is clearly something that requires more detailed investigation.”

A spokesman for Sellafield Ltd, which now runs Capenhurst, said: “We do not believe this study has identified any reason for our employees to be concerned about their radiation dose.

“This study shows no more than a statistical association between cumulative external radiation dose and cardiovascular disease.

“Of great importance is the fact there is currently no plausible biological mechanism for radiation to cause illnesses such as heart disease at occupational doses.”