Biological and health effects of ionising radiation - Knowledge drawn from human exposure to ionising radiation

Human organisms are constantly exposed to ionizing radiation. These exposures can be of natural origin, through radon inhalation for example, medical for diagnostic or therapeutic purposes, or industrial through controlled releases of radionuclides into the environment. These situations generally lead to exposure to low doses of radiation, described by UNSCEAR as not very harmful to human health . In contrast to these situations, accidental events can lead to overexposure of a variable number of people. The monitoring of people exposed to ionizing radiation is highly informative, and has made it possible to increase our knowledge of the health effects of ionizing radiation. The following text describes a number of cases of irradiation and accidental contamination, and attempts to highlight the lessons learned from these exposures. The aim of this article is not to deal with the human or technical malfunctions that led to such events, but to focus on the contribution these accidents have made to general knowledge of the health effects of ionizing radiation and to the development of new therapies. A few significant examples have been selected, representative of situations involving accidental, occupational or environmental exposure. At the end of this document, particular attention is paid to the debate on the effects of exposure to low doses of ionizing radiation, the outcome of which could eventually lead us to question the validity of certain concepts in the radiation protection system.