Exposure to moderate levels of radiation may increase the rates of heart disease and stroke, but the degree of risk at lower doses is unclear, finds a large study of atomic bomb survivors published on bmj.com today.
Although the authors cannot be certain that this is a direct (causal) link, their study provides the strongest evidence available to date of an association between circulatory disease and moderate radiation exposure.
Although the authors cannot be certain that this is a direct (causal) link, their study provides the strongest evidence available to date of an association between circulatory disease and moderate radiation exposure.
Several studies have shown that high doses of radiation to the heart or head and neck from radiotherapy cause an excess of deaths from heart disease or stroke in later years. But it is uncertain whether radiation exposures at relatively low dose levels (under 1 Gy) also increase the risk.
This is an important public health issue because of the increasing use of multiple computed tomography (CT) scans and other relatively high dose diagnostic medical procedures.
Medical use of radiation is typically measured in milligray (mGy). The average radiation dose from an abdominal x-ray is 1.4 mGy (0.0014 Gy), that from an abdominal CT scan is 8.0 mGy (0.008 Gy), and that from a pelvic CT scan is 25 mGy (0.025 Gy).
To investigate this further, Dr Yukiko Shimizu and colleagues from the Radiation Effects Research Foundation in Japan examined the risk of heart disease and stroke in 86,611 atomic bomb survivors from Hiroshima and Nagasaki who have been followed up for 53 years, from 1950 to 2003, as part of the Japanese atomic bomb survivor Life Span Study.
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