[ RadSafe ] Scientists discover possible radiation and heart disease link
fred-dawson at blueyonder.co.uk
Tue Mar 4 10:53:41 CST 2008
A study of nearly 65,000 nuclear industry workers over more than 60 years
has found a possible link between high radiation exposure and heart disease.
The finding was particularly surprising since there is no established
biological mechanism that would explain how radiation exposure might cause
heart disease. However, the research team stressed that its analysis could
not rule out other factors that could explain the link, such as work-related
stress or irregular shift patterns.
The team studied 64,818 workers at the Sellafield, Springfields, Chapelcross
and Capenhurst nuclear sites. Some of the workers began work in the industry
as far back as 1946, and 42,426 were exposed to radiation as part of their
When the researchers compared workers occupationally exposed to radiation
with those who were not, they did not find any difference in 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.
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. "We see a higher mortality for those workers with the highest level
of operation exposure," said Prof Steve Jones of Westlakes Scientific
Consulting, the private company hired by British Nuclear Fuels and the
Nuclear Decommissioning Authority to carry out the research.
The team stressed that because the analysis was carried out retrospectively,
it could not be sure that the findings ruled out other factors that could be
responsible for the results. "We can't show whether it's a consequence of
that exposure or whether it's due to something else," said Jones.
However, he added that 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 findings will have little relevance for workers joining the industry
today, according to the team. "I don't think it's a big issue for nuclear
workers at present or in the future because the exposure levels are so low,"
said the report's co-author Michael Gillies. In the 1960s, workers were
exposed to up to a radiation dose of 12 millisieverts per year compared with
around one millisievert per year now.
The most highly exposed workers received a radiation dose around five to 10
times less during their entire working lives than survivors of the atomic
bomb dropped on Hiroshima in 1945.
In any case, workers in the nuclear industry are generally much healthier
than the general population, despite the health risks they may face at work.
By comparing their sample with the average for the local population, the
team found that the mortality rate of nuclear workers is 20% lower.
The team reported its findings today in the International Journal of
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