[en] Survival is now the norm for children treated with radiotherapy and chemotherapy for childhood cancers. These children are now living to have children of their own. A Danish study of adverse health outcomes in the offspring of childhood cancer survivors and the offspring of the cancer survivor's sibling is ongoing. The cumulative probability of congenital malformation is non significantly higher amongst the offspring of cancer survivors than amongst the offspring of cancer survivor's siblings; and non significantly higher amongst the offspring of cancer survivors who received radiotherapy treatment compared with those who did not. future analyses will incorporate radiation dose to the uterus and gonads of cancer survivors. To date, studies of childhood cancer survivors offspring have not indicated and excess of congenial malformation. (Author) 7 refs

[en] Radiation epidemiology is the study of human disease following radiation exposure to populations. Epidemiologic studies of radiation-exposed populations have been conducted for nearly 100 years, starting with the radium dial painters in the 1920s and most recently with large-scale studies of radiation workers. As radiation epidemiology has become increasingly sophisticated it is used for setting radiation protection standards as well as to guide the compensation programmes in place for nuclear weapons workers, nuclear weapons test participants, and other occupationally exposed workers in the United States and elsewhere. It is known with high assurance that radiation effects at levels above 100–150 mGy can be detected as evidenced in multiple population studies conducted around the world. The challenge for radiation epidemiology is evaluating the effects at low doses, below about 100 mGy of low-linear energy transfer radiation, and assessing the risks following low dose-rate exposures over years. The weakness of radiation epidemiology in directly studying low dose and low dose-rate exposures is that the signal, i.e. the excess numbers of cancers associated with low-level radiation exposure, is so very small that it cannot be seen against the very high background occurrence of cancer in the population, i.e. a lifetime risk of incidence reaching up to about 38% (i.e. 1 in 3 persons will develop a cancer in their lifetime). Thus, extrapolation models are used for the management of risk at low doses and low dose rates, but having adequate information from low dose and low dose-rate studies would be highly desirable. An overview of recently conducted radiation epidemiologic studies which evaluate risk following low-level radiation exposures is presented. Future improvements in risk assessment for radiation protection may come from increasingly informative epidemiologic studies, combined with mechanistic radiobiologic understanding of adverse outcome pathways, with both incorporated into biologically based models. (paper)

[en] NCRP Report No. 180, ‘Management of Exposure to Ionizing Radiation: Radiation Protection Guidance for the United States (2018)’ was developed by Council Committee 1. The report builds and expands upon previous recommendations of NCRP and ICRP, covering exposure to radiation and radioactive materials for five exposure categories: occupational, public, medical, emergency workers, and nonhuman biota. Actions to add, increase, reduce or remove a source of exposure to humans require justification. Optimisation of protection universally applies, taking into account societal, economic, and environmental factors; addressing all hazards, and striving for continuous improvement when it is reasonable to do so. Numeric protection criteria for management of dose to an individual for a given exposure situation are provided, and differ in some respects from ICRP. A specific numeric criterion is suitable to be designated as a regulatory dose limit only when the source of exposure is stable, characterised, and the responsible organisation has established an appropriate radiation control program in advance of source introduction. Medical exposure includes patients, comforters and caregivers of a patient, and voluntary participants in biomedical research. Emergency workers are a new exposure category; their exposure is treated separately from occupational, public or medical exposure, and numeric criteria are provided for deterministic and stochastic effects. For nonhuman biota, the focus is on population maintenance of the affected species, and a guideline is provided for when additional assessment may be necessary. In addition, the recommendations emphasise that: ethical principles support decision-making; stakeholder engagement is necessary in deciding suitable management of their radiation exposure; and a strong safety culture is intrinsic to effective radiation protection programs. (memorandum)

[en] The recently published NCRP Commentary No. 27 evaluated the new information from epidemiologic studies as to their degree of support for applying the linear nonthreshold (LNT) model of carcinogenic effects for radiation protection purposes (NCRP 2018 Implications of Recent Epidemiologic Studies for the Linear Nonthreshold Model and Radiation Protection, Commentary No. 27 (Bethesda, MD: National Council on Radiation Protection and Measurements)). The aim was to determine whether recent epidemiologic studies of low-LET radiation, particularly those at low doses and/or low dose rates (LD/LDR), broadly support the LNT model of carcinogenic risk or, on the contrary, demonstrate sufficient evidence that the LNT model is inappropriate for the purposes of radiation protection. An updated review was needed because a considerable number of reports of radiation epidemiologic studies based on new or updated data have been published since other major reviews were conducted by national and international scientific committees. The Commentary provides a critical review of the LD/LDR studies that are most directly applicable to current occupational, environmental and medical radiation exposure circumstances. This Memorandum summarises several of the more important LD/LDR studies that incorporate radiation dose responses for solid cancer and leukemia that were reviewed in Commentary No. 27. In addition, an overview is provided of radiation studies of breast and thyroid cancers, and cancer after childhood exposures. Non-cancers are briefly touched upon such as ischemic heart disease, cataracts, and heritable genetic effects. To assess the applicability and utility of the LNT model for radiation protection, the Commentary evaluated 29 epidemiologic studies or groups of studies, primarily of total solid cancer, in terms of strengths and weaknesses in their epidemiologic methods, dosimetry approaches, and statistical modelling, and the degree to which they supported a LNT model for continued use in radiation protection. Recommendations for how to make epidemiologic radiation studies more informative are outlined. The NCRP Committee recognises that the risks from LD/LDR exposures are small and uncertain. The Committee judged that the available epidemiologic data were broadly supportive of the LNT model and that at this time no alternative dose-response relationship appears more pragmatic or prudent for radiation protection purposes. (memorandum)