The 20th report from the Committee on Medical Aspects of Radiation in the Environment (COMARE) provides an important review of whether exposure to ionising radiation is associated with cardiovascular disease (CVD), including ischaemic heart disease and stroke.

The report confirms that there is strong evidence of increased cardiovascular risk at higher radiation doses (typically above 0.5–1 Gy), such as those received during some radiotherapy treatments. At these levels, damage to blood vessels and cardiac tissues is well established.

At moderate doses (0.1–0.5 Gy), the evidence is more limited but suggests a possible increase in risk. However, the most relevant question for modern practice, whether low doses (<0.1 Gy) and low dose-rate exposures (such as those from diagnostic imaging or occupational exposure) increase cardiovascular risk, remains uncertain. COMARE concludes that there is no direct evidence of increased risk at these lower levels, but also no clear evidence of a safe threshold below which risk does not occur.

Importantly, the biological mechanisms underlying radiation-induced cardiovascular disease are not yet fully understood and appear more complex than those for cancer. This adds further uncertainty when estimating risks at low doses.

Overall, the report reinforces the importance of optimisation and dose minimisation, particularly in medical exposures, while highlighting the need for further research to better understand potential risks at low doses. Given the high prevalence of cardiovascular disease, even small increases in risk could have significant implications at a population level.

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📚 Reference

Committee on Medical Aspects of Radiation in the Environment (COMARE). Twentieth Report: Risks of Cardiovascular Disease from Exposure to Ionising Radiation. Department of Health and Social Care, UK, 2023.