Working at a nuclear site may be bad for the heart

A study which included almost 65,000 nuclear industry workers over more than 60 years, has found a possible link between high radiation exposure and heart disease.

The researchers studied 64,818 workers at the Sellafield, Springfields, Chapelcross and Capenhurst nuclear sites, some of whom began working in the industry as far back as 1946.

Of that group 42,426 were routinely exposed to radiation as part of their job.

The researchers found when they compared workers occupationally exposed to radiation with those who were not, there was no disparity between the number of cases of heart disease and stroke.

However, when they split the radiation-exposed workers into groups with different levels of exposure (based on readings from radiation-monitoring badges worn by all staff) they did see a disparity.

They found that those workers who were exposed to the highest levels had a slightly lower life expectancy due to an increased probability of heart disease and strokes.

Professor Steve Jones, of Westlakes Scientific Consulting, says a higher mortality was seen for those workers with the highest level of operation exposure.

The team does however emphasise that because the analysis was carried out retrospectively, it could not be sure that the findings ruled out other factors.

Professor Jones says it is unclear whether the results are a consequence of that exposure or whether they are due to something else.

He says if radiation were the cause, then the workers who have experienced the highest levels of exposure have roughly a 73% chance of surviving until they are 70, compared with a 75% chance if they had received no exposure at all.

The researchers say the findings will have little relevance for workers joining the industry today because exposure levels are now so low.

Co-author Michael Gillies says in the 1960s, workers were exposed to a radiation dose of up to 12 millisieverts per year compared with around one millisievert per year now.

Experts say studies of atomic bomb survivors in Japan had also suggested a link with heart disease.

Gillies says the most highly exposed workers received a radiation dose around 5 to 10 times less during their entire working lives than survivors of the atomic bomb dropped on Hiroshima in 1945.

The team say in general workers in the nuclear industry are much healthier than the general population, despite the health risks they may face at work.

The researchers say that further studies are needed to consider factors such as diet, exercise, cholesterol levels and smoking habits that affect the risk of heart disease.

Westlakes Scientific Consulting is a private company hired by British Nuclear Fuels and the Nuclear Decommissioning Authority to carry out the research.

The findings are published in the International Journal of Epidemiology.

(Source: International Journal of Epidemiology: Westlakes Scientific Consulting: March 2008)