Radiation exposure linked to CVD risk

When we talk about the A-Bomb, what comes to mind is exposure to high doses of radiation and cancer. The event occurred almost 65 years ago but new reports about its after effects continue to appear, highlighting the fact that such an event has some long-term consequences, some of which we’ve seen and some which are still to come.

A teams of Japanese researchers looked at data of 86,611 people who survived the A-bombs dropped on Hiroshima and Nagasaki. Previous reports have shown a disproportionately high incidence of cancer in this population, a finding that was not really surprising. What is surprising is that cardiovascular disorders such as stroke and heart disease also accounted for a significant fraction of excess deaths which are radiation-related. Analysis of the data showed that A-bomb survivors exposed to at least 0.r Gy of radiation have a significantly elevated risk for cardiovascular diseases.

According to the study authors:

“This study provides the strongest evidence available to date that radiation may increase the rates of stroke and heart disease at moderate dose levels (mainly 0.5-2 Gy. Given the widespread use of multiple computed tomography scans and other relatively high-dose diagnostic medical procedures, as well as radiotherapy that exposes the heart, the implications are substantial, insofar as effects occur at doses under 1 Gy.”

The study began 50 years ago which aimed to closely follow up the health outcomes of those who survived the immediate effects of the bombs. The participants of the study were survivors who lived within a 2.5 km radius of the bomb blasts and still resided there at the start of the study. Their outcomes were compared to a group of people of similar age and gender profile but who not or less exposed to the blast. The survivors were followed up till 2003. The results showed:

19,054 survivors died from cardiovascular diseases which included 9,622 mortality cases due to stroke and 8463 cases from heart disease. Of those deaths, 210 were considered “excess” deaths linked to exposure to radiation. The excess relative risk of a circulatory-disease-related death per Gy of radiation exposure was 11% but only exposure doses higher than 0.5 Gy.

According to an editorial by Dr Mark Little of the Imperial College London, UK)

 [The study]…”adds to a growing body of evidence suggesting an association between cardiovascular disease and exposure to [low to moderate] levels of radiation, as well as the well-known (and mechanistically well-understood) association at high doses.”

The radiation-cardiovascular disease risk link is especially relevant nowadays when the issue of radiation for medical purposes is becoming a hot topic, with questions regarding its safety.