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Purpose: Carry out a comparative analysis of the criteria and practices of conduct Iodine thyroid blocking (ITB) in various countries from the standpoint of WHO publication (2017) “Iodine thyroid blocking. Guidelines for use in planning for and responding to radiological and nuclear emergencies” (WHO Guidelines) and national Rules and requirements 2.6.1.2523-09 (NRB-99/2009) and other documents, including facility and territorial Emergency plans and instructions contained therein. Results: The WHO Guidelines, prepared using the GRADE method, determine the conditional recommendation in favor of conduct ITB in the event of a release of radioactive iodine: “During a radiation or nuclear emergency, the provision of ITB for people who are at risk of exposure to radioactive iodine should be implemented as urgent protective action as part of a justified and optimized protection strategy”. In the WHO Guidelines, such a recommendation is recognized as qualitatively low, and the strength of this recommendation is conditional, due to insufficient data on the use of stable iodine drugs. However, after studying the implementation of this protective measure, it was determined that the benefits of the intervention outweigh the disadvantages and associated costs. The article contains a selective discussion and opinion of the authors on a number of key issues of organization and conduct ITB. Conclusion: A comparative analysis revealed the similarities and differences between foreign and national practices of conduct ITB. The convergence of positions is necessary and aimed at harmonizing national and international criteria and practices. To date, there is no federal level document in the Russian regulatory framework that regulates the planning, organization and conduct of ITB in relation to people who are not associated with work at radiation hazardous facilities and do not live on territories served by the FMBA of Russia. Based on this, a range of priority important issues that need to be addressed has been identified.

Purpose: Development of recommendations on the use in medical practice of institutions under FMBA of Russia of operational values of radioactive skin contamination in the event of radiological accidents. Material and methods: The easily measured radiation parameters were used as operational values: ambient dose equivalent rate (ADER) of γ-radiation, density of skin contamination with γ-, β- and α-emitting radionuclides. Operational values ​​of skin contamination were estimated on the basis of experimental data described in the literature and models on the kinetics of radioactive substances transport in the body, accepted values ​​of dose criteria for deterministic and stochastic effects. The estimation of radioactive material resorption through the skin was based on the results of experimental studies in laboratory animals (mainly piglets) for a limited set of chemical compounds of radionuclides. Results: The values of γ-ADER of the main dose-forming radionuclides measured at a distance of 10 cm from the skin surface in the range of 10–1000 μSv/h and the possible health effects due to the skin exposure and the intake of radioactive substances into the body were presented. In the IAEA recommendations, the level of skin contamination at 1 µSv/h is considered as a significant operational value according to the criterion of radioactive substances intake through the mouth from the contaminated surface of the hands. However, in our opinion, this estimate is excessively conservative; therefore it is not included in the recommended operational values. If the skin is contaminated with γ-β-emitting radionuclide solutions at a surface contamination higher than 106 Bq/cm2 (ADER ≥1000 µSv/h), the out of turn emergency decontamination should be carried out. Obligatory indications for the whole body counter examination after thorough decontamination and conducting biophysical analysis of bioassay are the following operational values: γ-ADER from the skin > 10 µSv/h; surface contamination of intact skin with β-active radionuclides > 20 000 β-part./(cm2·min); surface contamination of intact skin with α-active radionuclides > 200 α-part./ (cm2·min). Conclusion: The recommended operational values allow preliminarily and promptly to assess the health risk not only in the case of external (contact) exposure of the skin and underlying tissues, but also due to the intake of soluble radioactive substances into the body through intact and damaged (injured) skin. Taking into account the high degree of uncertainty of the estimates obtained, the operational values ​​should be considered as strictly conservative. They should be used only to determinate of urgency of decontamination carrying out for the provision of medical care during the prehospital and early hospital periods with the obligatory follow-up dosimetry examination for the final assessment of absorbed dose.

Purpose: To summarize and analyze the results of research and practical recommendations on the decontamination of victims in the event of radiation accidents, including taking into account the authors’ experience gained in the initial period of the Chernobyl accident (April – August 1986) and in other local radiation accidents (incidents), as well as during emergency exercises. Results: The indications for carrying out decontamination and the technique of its implementation were considered, a comparative assessment of the effectiveness of skin decontamination agents was presented. Recommendations were formulated for determining the priority (urgency) of carrying out decontamination, depending on the level of external radioactive contamination of the victims. Criteria, rules and methods for carrying out decontamination were proposed for use in relation to the practice of medical and hygienic measures at the stages of medical evacuation (accident site, enterprise health center, enterprise sanitary inspection department, triage site, hospital admission department). The features of decontamination of victims with combined radiation injuries and contaminated wounds (burns) were considered, issues of ensuring the radiation safety of medical personnel who provide assistance to victims are touched upon. Conclusion: Timely and correctly performed decontamination reduces the exposure of the skin, prevents the entry of radioactive substances into the body and the transfer (spread) of radioactive substances to the subsequent stages of medical evacuation. The main criteria for the urgency (priority) of carrying out decontamination are the levels of radioactive contamination of the skin, contamination nature (radionuclide composition, physicochemical form, etc.) and the presence of victim’s skin lesions (wounds, burns). Decontamination of victims with high levels of radioactive contamination should be considered as a part of the first and subsequent emergency health care and should be carried out as prescribed or with the direct participation of a healthcare professional. At the stages of medical evacuation, decontamination can be carried out if the victim’s condition is stabilized. In the case of a serious condition of the victim, the priority is evacuation to a hospital, while in the prehospital period, as a rule, only partial decontamination of skin areas with high levels of contamination can be carried out. The procedure and rules for decontamination, including the use of skin decontaminating agents, should be reflected in the action plans of the personnel of radiation hazardous enterprises and the plans for medical support of medical units of the FMBA of Russia.

Purpose: To develop approaches to categorizing (ranking) radiological terrorism (RT) threats on the basis of expert assessment of the possibility (likelihood) of the implementation of certain RT scenarios and assessment of their medical and hygienic consequences. Results: Five categories of RT threats are highlighted. The first (most hazardous) threat category includes situations related to the use of radioactivity dispersing devices (RDD), including the “dirty bomb”. It is shown that the creation of a potential threat of radiation exposure to people at the thresholds of deterministic effects may require the activity of radionuclides in RDD in the range of several hundred TBq. The second category of threats includes scenarios of RT related to the placement of high dose rate radionuclide sources in areas of permanent location or mass gathering of people. The third category of threats includes situations when radionuclide sources maliciously place (enclose) into technological equipment and processes, which leads to radioactive contamination of the environment, industrial and socially significant facilities (water treatment plants, warehouses of food and raw materials), manufactured products. It is shown that in the case of the implementation of such RT scenarios, the dose criteria that require protective measures for the public are unlikely to be achieved. The fourth category of threats includes the physical impact on radioactive materials in the nuclear reactors, fuel element storage pools, and radioactive waste storage facilities. The fifth category of threats includes scenarios of RT related to the use of improvised nuclear devices or nuclear weapons by terrorists. Conclusion: Threats of categories I–III, given the combination of the possibility of implementing RT scenarios and the scale of medical and hygienic consequences, are estimated as relatively high. Threats of category IV and V due to the extremely low probability of their implementation have the lowest rating, despite the great and even catastrophic nature of the consequences.