Emerging Trends in Radiation and Cancer

Ionizing radiation is a well-studied physical exposure and a known carcinogen for more than 100 years. Most scientific evidence comes from studies on atomic bomb survivors and patients treated with radiation, and has lately been complemented by studies on populations exposed in environmental or occupational settings to radon, studies of nuclear workers or patients with diagnostic procedures. These studies, together with animal experiments, show that ionizing radiation induces cancer in most tissues, of most species, and at all ages. There is a firm dose-response, and risks at high-dose and high-dose rate are known with reasonable precision and accuracy. Further research is however needed regarding effects of low radiation doses received over long periods at relatively low dose rate, different types of radiation, individual sensitivity (e.g. genetic predisposition), relevant time-windows of exposure, age at exposure, and mechanisms of radiation carcinogenesis. The most predominant source of natural radiation exposure is radon, which is a gas that leaks out of the earth all over the world at different levels. Radon is the second most important lung carcinogen globally. The most important source of man-made radiation exposure is medical diagnostics; in particular the use of computed tomography (CT). Although CT scans are highly beneficial and potentially lifesaving by improving the accuracy of diagnosis and surgical interventions, unnecessary use of these examinations needs to be minimized. Concerning non-ionising radiation, at present, there is no convincing evidence that radiofrequency electromagnetic fields (mobile phones) increase the risk of cancer. The information on long term heavy mobile phone use is limited, why continued research is still needed.