Exposure to low doses of ionising radiation is associated with a modest increased excess risk of heart disease, researchers report today.
The researchers say their findings “have implications for patients who undergo radiation exposure as part of their medical care, as well as policy makers involved in managing radiation risks to radiation workers and the public”.
Although it is known that exposure to high dose radiation can damage the heart, the risks are unclear for individuals exposed to low dose radiation, including those who are exposed to scatter radiation dose from radiotherapy or who work in the nuclear industry.
An international team of researchers, including a team from the National Cancer Institute, Bethesda, MD, USA, and the Southern Urals Biophysics Institute, Ozyorsk, Russia, examined scientific databases for studies that looked at links cardiovascular diseases and exposure to radiation, mostly through radiotherapy and occupational exposures.
They included 93 studies, most of which were published in the past 10 years, that covered a broad range of doses, brief and prolonged exposures, and evaluated frequency and mortality of vascular diseases.
Consistent evidence for a dose dependent increase in cardiovascular risks across a broad range of radiation doses was found: the relative risk per Gy increased for all cardiovascular disease and for specific types of cardiovascular disease, and there was a higher relative risk per dose unit at lower dose ranges (less than 0.1 Gy), and also for lower dose rates.
Their findings show there is a modest but significantly increased excess lifetime risk of 2.3-3.9 cardiovascular deaths per 100 persons exposed to one Gy of radiation.
Although there was significant variation between studies, this was reduced when the authors restricted their analysis to higher quality studies or to those at moderate doses (less than 0.5 Gy) or low dose rates (less than 5 mGy/h).
They say their findings support an association between acute high dose and, to a lesser extent, chronic low dose radiation exposure and most types of cardiovascular disease and suggest that “radiation detriment might have been significantly underestimated, implying that radiation protection and optimisation at low doses should be rethought”.
Little MP, Azizova TV, Richardson DB et al. Ionising radiation and cardiovascular disease: systematic review and meta-analysis. BMJ 9 March 2023
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