ASN Report 2022

Studies on nuclear industry workers have given a clearer picture of the risk associated with chronic exposures at low doses established over many years, whether as a result of external exposure or internal contamination. Hereditary and teratogenic effects The occurrence of possible hereditary effects from ionising radiation has not been demonstrated in humans. Such effects have not been observed among the survivors of the Hiroshima and Nagasaki bombings. But hereditary effects have been documented in experimental work on animals; more specifically, the mutations induced by ionising radiation in germ cells (cells that develop into reproductive cells: spermatozoa or ovules) can be transmitted to the progeny. An ICRP working group, TG121, is currently working on the subject of heritable effects and their modes of transmission to future generations. Environmental protection The purpose of radiation protection is to prevent, mitigate and limit the exposure of individuals to ionising radiation, directly or indirectly, including through deleterious effects on the environment. Over and beyond environmental protection aiming at the protection of humans and present or future generations, the protection of non-human species as such forms part of the environmental protection prescribed in the French constitutional Charter for the Environment. Protection of nature in the specific interests of animal and plant species (see point 3.4) has been the subject of several publications since 2008 (ICRP 108, 114, 124 and 148). 1.3.3 Molecular signature in radiation-induced cancers It is currently impossible to distinguish a radiation-induced cancer from a cancer that is not radiation induced. The reason for this is that the molecular lesions caused by ionising radiation seem no different to those resulting from the normal cellular metabolism, with the involvement of free radicals – oxygenated in particular – in both cases. Furthermore, to date, neither anatomopathological examinations nor research for specific mutations have been able to distinguish a radiation-induced tumour from a sporadic tumour. It is known that in the first stages of carcinogenesis (process of cancer formation) a cell develops with a particular combination of DNA lesions that enables it to escape from the usual control of cellular division, and that it takes about ten to one hundred DNA lesions (mutations, breaks, etc.) at critical points to pass through these stages. All the agents capable of damaging cellular DNA (tobacco, alcohol, various chemical substances, ionising radiation, high temperature, other environmental factors, notably nutritional and free radicals of normal cellular metabolism, etc.) contribute to cellular ageing and to carcinogenesis. Consequently, in a multi-risk approach to carcinogenesis, can we still talk about radiation-induced cancers? Yes we can, given the quantity of epidemiological data which indicate that cancer frequency increases when the dose increases, with the other main risk factors taken into account. However, the radiation-induced event can also in certain cases be the only event responsible (radiation-induced cancers in children). Highlighting a radiological signature of cancers, that is to say the discovery of markers that could indicate whether a tumour has a radiation-induced component or not, would be of considerable benefit in the evaluation of the risks associated with exposure to ionising radiation, but has not been demonstrated to date. The multifactorial nature of carcinogenesis calls for a cautious approach with respect to the all the risk factors, since each one of them could contribute to DNA damage. This is particularly important in persons displaying high individual radiosensitivity and for the most sensitive organs such as the breast and the bone marrow, and all the more so if the persons are young. Here, the principles of justification and optimisation are more than ever applicable (see chapter 2). Workers (“radium girls”) painting the pointers of luminous dials with radium in the US Radium plant (United States Radium Corporation) in Orange, New Jersey – 1922 ASN Report on the state of nuclear safety and radiation protection in France in 2022 103 • 01 • Nuclear activities: ionising radiation and health and environmental risks 07 08 13 AP 04 10 06 12 14 03 09 05 11 02 01