External Radiation Dose Research Articles

Construction of a realistic voxel phantom of the Japanese red fox (Vulpes vulpes japonica) based on MRI imaging and estimation of its background external radiation dose rate from environmental radionuclides.

In this study, we selected the Japanese red fox (Vulpes vulpes japonica) as a representative mid-size mammal from the forests near the spent nuclear fuel reprocessing plant at Rokkasho. A fox voxel phantom was constructed based on magnetic resonance imaging of a female red fox caught in Rokkasho. This phantom consisted of 264×321×383 voxels (each voxel size: 0.78×0.78×2mm) with internal organs. The external radiation dose rate to the voxel phantom by beta and gamma rays from environmental radionuclides was estimated using a Monte Carlo code (EGS4 and UCPIXEL). We estimated the dose rates to the phantom on the ground and in an average fox burrow in the Rokkasho forest, which were 11 and 27 nGy h-1, respectively. Assuming that the animal on the ground was irradiated by cosmic rays of 27 nGy h-1, the total external dose rate was evaluated to be 38 nGy h-1. Based on the assumption that the fox lives on the ground for 12h and in the burrow for 12h, the dose rate was estimated to be 33 nGy h-1.

Does long-term radiation exposure in Chornobyl impact the reproductive structures of Nuphar lutea (Linné) Smith?

The 1986 Chornobyl Nuclear Power Plant accident caused radioactive contamination of water bodies within the Pripyat River floodplain, resulting in the accumulation of radionuclides by macrophytes, which are fundamental species in water ecosystems. Yellow water lily Nuphar lutea (L.) Smith., a macrophyte playing a significant role in the formation of vegetation cover in aquatic ecosystems, is commonly considered as a bioindicator of water pollution. In this study, we investigate the potential of N. lutea as an indicator of radionuclide contamination in water bodies, particularly through changes in its reproductive structures, such as pollen viability, morphology of pollen grains, seeds, and fruits. Our findings reveal that pollen viability remains stable at total absorbed dose rates below 14.4 μGy/h, with only 1–4% of sterile grains. However, beyond this threshold the percentage of sterile grains increases nearly fivefold, pointing to high internal plant exposure to 90Sr. A similar trend was observed in the allometry and size of pollen grains, where small and flattened grains are formed in the reservoir with the highest external radiation dose rate (≥14.4 μGy/h). On the other hand, while morphometric parameters of fruits are influenced by radiation, their variation appears to be the result of a combination of physicochemical factors and the trophic status of a water body. Our research highlights the adverse impact of long-term radiation exposure on the male reproductive system of N. lutea and shows the potential of using the pollen grains sterility as an indicators of heavily radionuclide-contaminated water bodies. Additionally, we observed gradual changes in a pollen allometric length-to-width coefficient as the radiation dose level increases.

Advancements in Biological Dosimetry Techniques for Surge Response to Radiation Emergencies in Ghana

The awareness of the use of biodosimetry to estimate external radiation doses received by individuals and in radiation oncology, nuclear medicine, diagnostic, and interventional radiology has gained traction in recent years. At present Ghana is poised to integrate about 1GW of nuclear power into its electricity mix by 2034. The increased awareness of biodosimetry is probably due to increased radiological threats and incidents, medical and forensic applications, the quest to strengthen emergency response to unplanned radiation exposures such as radiological accidents, and the malevolent use of radioactive sources. Biodosimetry capabilities would play an effective role during public health management of radiation emergencies for rapid dose estimation and help to medically categorize the exposures for the purpose of prioritizing treatment of the affected persons. Moreover, it will also serve to provide reassurance and psychological support for the “worried-well”. Biodosimetry methods and infrastructure can also be utilized for various applications, including molecular research, medical cytogenetics, and forensics. This write-up assesses the status of biodosimetry methods and infrastructure capabilities available at the Ghana Atomic Energy Commission (GAEC), which could be leveraged during radiological or allied scenarios.

Predictors of Clinical Hematological Toxicities under Radiotherapy in Patients with Cervical Cancer-A Risk Analysis.

Cervical cancer ranks third in frequency among female cancers globally and causes high mortality worldwide. Concurrent chemoradiotherapy improves the overall survival in cervical cancer patients by 6% but it can cause significant acute and late toxicities affecting patient quality of life. Whole pelvis radiotherapy doses of 10-20 Gy can lead to myelosuppression and to subsequent hematological toxicities since pelvic bones contain half of bone marrow tissue. A total of 69 patients with IB-IVB-staged cervical cancer have been included in this retrospective cohort study. We analyzed clinical adverse events and changes in blood cell counts (hemoglobin, neutrophils, leukocytes, and platelets) during radiation or chemoradiotherapy received at the Oncological Institute of Bucharest from 2018 to 2021. Decreases in hemoglobin levels of over 2.30 g/dL during treatment were associated with BMI > 23.2 kg/m2 (OR = 8.68, 95%CI = [1.01, 75.01]), age over 53 years (OR = 4.60 95%CI = [1.10, 19.22]), with conformational 3D irradiation (OR = 4.78, 95%CI = [1.31, 17.40]) and with total EQD2 of over 66.1 Gy (OR = 3.67, 95%CI = [1.02, 13.14]). The hemoglobin decrease rate of 0.07 g/dL/day was related to 95% isodose volume (OR = 18.00). Neutropenia is associated frequently with gastrointestinal side effects and with the bowel and rectal V45 isodoses (OR = 16.5 and OR = 18.0, respectively). Associations of total external and internal radiation dose with the time durations calculated from the initiation of treatment to the onset of hematological adverse reactions were also obtained. The maximum drop in leukocytes was observed before day 35 from the RT initiation in patients who underwent treatment with 3D conformal radiotherapy (OR = 4.44, 95%CI = [1.25, 15.82]). Neutrophil levels under 2.2 × 103/μL and thrombocyte levels under 131 × 103/μL during the follow-up period were associated with a total planned dose of 54 Gy to the pelvic region volume (OR = 6.82 and OR = 6.67, respectively). This study shows the existence of clinical and blood predictors of hematological adverse reactions in cervical cancer patients. Thus, patients who are in a precarious clinical situation, with low hematological values (but not yet abnormal), should be monitored during days 29-35 after the initiation of RT, especially if they are obese or over 53 years of age.

The External Radiation Dose of the Population Tbilisi, Georgia

The External Radiation Dose of the Population Tbilisi, Georgia

External Radiation Dose to the Shore Crab of Chinnavilai, a High Background Natural Radiation Area

The aim of the study was to determine the activity concentration and radiation dose of radionuclides 226Ra, 228Ra & 40K in shore crab Hemigrapsus Sanguineus, in Chinnavilai, Kayakumari district, Tamil Nadu, India. Gamma spectrometry is used for determine activity concentration and radiation dose of radionuclides (226Ra, 228Ra & 40K.). The total dose values due to both internal and external contributions by all three studied radionuclides fell between 26.51 and 53.19 µGy/day. These values are far below the dose limits (10 mGy/day) prescribed for aquatic animals by the US Department of Energy (2002) and hence the animals are safe, radiologically as far as these radionuclides are concerned. The minimum internal dose for 228Ra in shore crab 0.30 and the external dose 16.42. The total dose for 228Ra in shore crab 16.72. The maximum internal dose for 228Ra in shore crab 0.64 and the external dose 30.03. The total dose for 228Ra in shore crab 30.67.

Measurement of natural radioactivity levels in soil samples of Bidar district, Karnataka, India.

Natural radioactivity measurement, radiation monitoring of the region, dose assessment and interpretation of radiological-related parameters are crucial aspects from the public awareness and environmental safety point of view. The ionising radiations (gamma-rays) emitted from radionuclides such as 226Ra, 232Th and 40K present in environmental materials contributes significantly to the external radiation dose received by the public. High-efficiency gamma spectrometry based on a 4″×4″ NaI (Tl) detector was employed for estimating activity concentrations of the gamma-emitting radioelements. The spectra from the detector were recorded using a PC-based 1k multichannel analyser system (WinTMCA 32). Each sample spectrum was acquired for a counting period of 60000s (16.67hr). Assuming the daughter products of 226Ra and 232Th in equilibrium, the activity concentration of these radionuclides were estimated by using the prominent gamma photo peaks of daughter products. Using the same technique, dose-related radiological parameters were calculated for all the samples. The activity concentrations of the radionuclides and the dose-related parameters for the samples were found to be comparable with the global literature values. The data generated from our study will contribute to the baseline radiological data of the region.

Conservative assessment of external radiation dose for staff in the event of radionuclide flaw detection

The article proposes a new approach to assessing the effective doses of flaw detectorists performing flaw detection using portable radionuclide flaw detectors (gamma flaw detectors). The existing approach to assessing effective doses, based on the use of one individual dosimeter placed on work clothes in the chest area, is inadequate for the actual working conditions of exposure of flaw detectorists. Gamma flaw detectors contain a closed man-made source of ionizing radiation in their head, therefore, even in the non-working position, such flaw detectors pose a radiation hazard. When transporting and preparing gamma flaw detectors for work, the flaw detector operator is in close proximity to the radiation source. The irradiation geometry changing during the technological cycle when working with portable gamma flaw detectors at certain stages creates a sharply uneven irradiation of the flaw detectorist’s body. Therefore, after assessing the stages of the technological cycle, an option was proposed for a more conservative assessment of effective doses – to change the location of the individual dosimeter on the working clothes of the flaw detectorist, moving the individual dosimeter to the abdominal area. An anonymous study was carried out with the participation of 15 flaw detectorists; three individual dosimeters were displayed on their working clothes: two of them were experimental and were placed in the chest and abdomen; the third (a control dosimeter) was exposed for the quarter on the chest as part of constant individual dosimetric monitoring. In controlled anonymous measurements, the average effective dose, estimated from the readings of dosimeters exposed in the chest area, was equal to 0,95 mSv (median – 0,92 mSv, maximum value – 1,27 mSv). These values were compared with values obtained using dosimeters that were exposed to the abdomen, and the differences were significant (the average effective dose was 1,24 mSv (median – 1,22 mSv, maximum value – 1,78 mSv).

Assessment of Naturally Occurring Radionuclide in Soil Samples from Kutayi Mining Sites in Muya Local Government Area, Niger State, Nigeria

This work examines the Kutayi mining sites with a view of assessing the activity concentration and effective dose rate of NORM (i.e. 40K, 232Th and 226Ra) in these site absorbed in 8 soil samples collected from different areas within the Kutayi mining sites, A γ-ray spectrometry NaI (Tl) at CERT. ABU Zaria, was used to carry out the analysis of the soil samples. The result shows that, activity concentration for 40K ranged from 428.9269 to 93.6236 BqKg-1; for 226Ra it ranged from 50.1738 to 13.7891 BqKg-1 and for 232Th the ranged is from 52.1095 to 18.7457 Bq.Kg-1, the absorbed dose for 40K ranged from 17.8863 to 3.9041 ŋGy.h-1, for 226Ra the range is from 23.1803 to 3.1614 ŋGy.h-1 and for 232Th range from 31.47419 to 11.3224 ŋGy.h-1. The total mean absorbed dose rate is 42.5341 ŋGy.h-1 and the annual effective dose range from 0.0355 mSvy-1 (i.e. 36 – 76 μSv.y-1), with an mean annual effective dose of 0.0522 mSv.y-1 (i.e. 52.2 μSv.y-1, Also the mean Radium Equivalents (Raeq) obtained ranged from 64.0280 BqKg-1 (KT6) to 135.3245 BqKg-1 (KT8). This results show that, the Raeq is 370 BqKg-1 which is the requirement for soil to be used for dwellings; hence the soil from this site is suitable use for buildings. The mean Hext ranged from 0.1730 Bqkg-1 (KT6) to 0.3438 Bqkg-1 (KT8). The maximum allowed value of (Hext = 1) corresponds to the upper limit of Raeq (370 BqKg-1) in order to limit the external gamma radiation dose from the soil to 1.5 mGy y-1, i.e. index should Hext = 1. All these values for Iα are below the maximum permissible value of Iα= 1 which corresponds to 200 Bq.Kg-1. Hence no radiological hazard is envisaged to dwellers of the study areas and the miners working on those sites.

Потужність поглиненої дози зовнішнього опромінення представників іхтіофауни озер у Чорнобильській зоні відчуження

The limits of the average value of the average annual external radiation dose rate of fishes from four lakes (with different degrees of radionuclide pollution of ichthyofauna representatives) of the Chornobyl Exclusion Zone as of 2021 are given, namely: Azbuchyn Lake (4 - 33 μGy/h), Vershyna Lake (3 - 26 μGy/h), Glyboke Lake (2 - 15 μGy/h) and Plyutovyshche Lake (0.02 - 0.16 μGy/h). Bottom-dwelling fish species such as tench and Prussian carp receive the highest external radiation dose, and rudd and surface fish species receive the lowest. It has been proven that the radionuclide 137Cs forms from 62.8 to 98.7 % of the absorbed dose of external irradiation of fishes from the studied water bodies. It is clearly shown that the current levels of the average annual absorbed external dose rate for many of the studied fishes of the lakes exceed the screening dose of 2 μGy/h and in 6 cases out of 22 exceed the safe level of 10 μGy/h recommended by the European Commission project “PROTECT”.

Natural and artificial radioactivity levels and external radiation dose levels of sand samples collected from Lara Beach, Antalya, Türkiye

Natural and artificial radioactivity levels and external radiation dose levels of sand samples collected from Lara Beach, Antalya, Türkiye

ОЦЕНКА РАДИАЦИОННОГО РИСКА СМЕРТИ ОТ СЕРДЕЧНО-СОСУДИСТЫХ ЗАБОЛЕВАНИЙ ЛИКВИДАТОРОВ ПОСЛЕДСТВИЙ АВАРИИ НА ЧАЭС – РАБОТНИКОВ ПРЕДПРИЯТИЙ АТОМНОЙ ПРОМЫШЛЕННОСТИ ПО ДАННЫМ О ДОЗАХ РАЗЛИЧНЫХ ВИДОВ ОБЛУЧЕНИЯ

Background: Assessment of the risk of death from circulatory system diseases due to radiation exposure in liquidators of the Chernobyl accident consequences (hereinafter referred to as liquidators) using data on doses of various types of exposure. Material and methods: The work used the information base of the Industry Register of persons exposed to radiation as a result of the accident at the Chernobyl nuclear power plant (hereinafter referred to as the register), nuclear industry workers. The radiation risk assessment study included men - 12,706 liquidators who had data on external emergency radiation doses when working in the 30 km Chernobyl NPP zone, 1,327 of them had data on occupational radiation doses. Poisson regression was chosen as the statistical model of risk. The study covers the period from 1987 to 2021. During the observation period, the register accumulated 304,023 person/years. The majority of the register in 1986 was made up of men – 84.7 %, women – 15.3 %. Results: When data on doses of different types of radiation are used to calculate doses, different results of excess relative risk are obtained. Only the total radiation dose (occupational, emergency, medical, natural) can provide correct results for calculating the radiation risk of death from radiation-induced diseases. Conclusion: The prospect of research should be considered to be filling the information base of the Industry Register with data on doses of all types of radiation.

Extended analysis of solid cancer incidence among nuclear industry workers in the UK 1955-2011: comparison of workers first hired in earlier and later periods.

To address points arising from the recent study of nuclear workers in the USA and the International Nuclear Workers Study (INWORKS), concerning the difference in solid cancer risk estimates between those first hired in earlier and later calendar years, subsidiary analyses were conducted on a cohort of 172 452 workers in the National Registry for Radiation Workers (NRRW) from the UK. A total of 18 310 incident first primary solid cancer cases were registered in the period from 1955 until 2011 in the NRRW cohort and workers accrued 5.25 million person-years of follow-up. Incidences rates of all solid cancers combined, lung cancer and solid cancer excluding lung cancer were examined in terms of external radiation doses in the full cohort and in a sub-cohort of workers who had no record of internal exposure monitoring and were defined by the periods of first hire before and after the beginning of the years 1960, 1965 and 1970. All analyses were carried out using Poisson Regression. These analyses demonstrated that only for lung cancer between the pre-1965 and post-1964 periods is there strong evidence for a difference in the risks using the NRRW full cohort. In the other calendar period breakdowns and for the other cancer groups, there is no clear evidence of differences in the risks. The NRRW estimation of risks between recent and early workers is not generally consistent with the US workers cohort or the INWORKS evaluations that later hired workers are at much higher solid cancer risk than earlier hired workers, although INWORKS contains a significant part of the latest updated NRRW cohort as well as the US data. The conclusion that the INWORKS and US study data demonstrate a real difference in excess solid cancer risk from external radiation exposure between earlier and later workers is premature. The results presented here should also be treated with caution because of the limited corroborating evidence from other published studies. Information on internal doses, neutron doses as well as non-radiation factors such as smoking and asbestos exposure would be needed to make definitive inferences.

Current status of reference location in the basic model for assessment of external radiation doses to the population living in radioactively contaminated areas after the Chernobyl accident

An open plot of virgin land is the reference location in the basic model used to date to estimate the effective dose of external exposure to the population living in a radioactively contaminated area. As our field observations in the Bryansk region of Russia have shown, at present it is very difficult to find truly reference plots of virgin land due to the fact that many virgin meadows were plowed or reclaimed for more than 30 years after the Chernobyl accident. Without special instrumental survey, such disturbed meadow areas can easily be confused with areas of virgin soil. Therefore, the situation with the use of open areas of virgin soil as the reference location has changed dramatically since the first years after the Chernobyl accident. It requires a change in the approach to choosing such a location for the model and/or some revision of the structure of the model itself. Firstly, we propose and justify the use of a permanently cultivated kitchengarden plot as the reference location. The second way to resolve the current difficult situation with the presence of a sufficient number of the virgin soil sites could be excluding the very concept of “reference location” from the model. In this case, when calculating the effective dose of external radiation, it is proposed to directly use the values of the gamma radiation dose rate in the air normalized to the 137Cs contamination density of soil. The values of the normalized dose rate should be experimentally determined in the required time period for each of the locations taken into account in the model.

Shape of radiation dose response relationship for ischaemic heart disease mortality and its interpretation: analysis of the national registry for radiation workers (NRRW) cohort

Statistically significant increases in ischemic heart disease (IHD) mortality with cumulative occupational external radiation dose were observed in the National Registry for Radiation Workers (NRRW) cohort. There were 174 541 subjects in the NRRW cohort. The start of follow up was 1955, and the end of the follow-up for each worker was chosen as the earliest date of death or emigration, their 85th birthday or 31 December 2011. The dose-response relationship showed a downward curvature at a higher dose level >0.4 Sv with the overall shape of the dose-response relationship best described by a linear-quadratic model. The smaller risk at dose >0.4 Sv appears to be primarily associated with workers who started employment at a younger age (<30 years old) and those who were employed for more than 30 years. We modelled the dose response by age-at-first exposure. For the age-at-first exposure of 30+ years old, a linear dose-response was the best fit. For age-at-first exposure <30 years old, there was no evidence of excess risk of IHD mortality for radiation doses below 0.1 Sv or above 0.4 Sv, excess risk was only observed for doses between 0.1–0.4 Sv. For this age-at-first exposure group, it was also found that the doses they received when they were less than 35 years old or greater than 50 years old did not contribute to any increased IHD risk.

Дозовая зависимость смертности от болезней системы кровообращения у работников ядерной индустрии (систематический обзор и pooled-анализ): отсутствие эффекта малых доз и подтверждение порога, установленного НКДАР и МКРЗ при 0,5 Гр

Based on the maintained database (source database) on effects in nuclear workers (NW), a selection of major studies of the relationship between mortality from diseases of the circulatory system (CVD; codes 390–459 according to ICD-9 and I00–I99 according to ICD-10) and external radiation dose. The sample included 30 papers and covered cohorts from 6 countries plus an NW cohort from 15 countries. For the sample, in most cases based on published standardized mortality rates (SMR), the relative risks (RR) of mortality from CVD were calculated for the selected dose groups with subsequent processing of the material for outliers. Initial: n = 207; final sample: n = 199; covers very low (0–10 mSv; 15.8 % of the sample), low (&gt;10–100 mSv; 45.8 %) and moderate (&gt;100–1000 mSv; 36.4 %) doses; data for high doses (&gt;1000 mSv; n = 4; 2 % of the sample), due to dubiousness, were excluded. A systematic review and pooled analysis of the RR for mortality from CVD depending on the dose on an ordinal scale was performed on the final sample. For the entire dose range (0–1000 mSv) and for moderate doses, statistically significant trends in increasing RR were found when expressed in five types of regressions (except for the logarithmic one for the entire range). Although the r values were small (0.230–0.293), the effect was clear. The ERR per 1 Gy (Sv) calculated for moderate doses using linear regression was 0.54. This value is higher than those obtained previously in meta-analyses, but should be considered as the most adequate. No dose relationship was found for the very low + low dose range (0–100 mGy); the r coefficients for the regressions were either negligible or negative at statistical insignificance. For the subthreshold dose range for CVD mortality after exposure (according to UNSCEAR and ICRP: 500 mSv), only a weak trend towards an increase in RR was found, statistically insignificant, despite the large sample size (n = 191), while for the dose range 500–1000 mSv, the highest tendency among the pooled analyzes was revealed to increase the risk depending on the level of exposure (r = 0.297–0.423; statistically insignificant due to the small sample size: n = 8). It is concluded that for mortality from CVD after irradiation, the threshold value of 0.5 Gy established by UNSCEAR and ICRP and confirmed in the present pooled analysis should be strictly adhered to. Due to the lack of effects of low doses, it is inappropriate to raise the issue of low dose effects in the context of these pathologies.

Risk of central nervous system tumour incidence in a cohort of workers chronically exposed to ionising radiation.

The aim of the present study was to assess the risk of primary central nervous system (CNS) tumour incidence in a cohort of 22,377 Mayak Production Association workers chronically exposed to ionising radiation. There were 96 primary CNS tumours, including 42 cases of glioma and 44 cases of meningioma, registered during the whole follow-up period (1948-2018). The study demonstrated that the risk of primary CNS tumour incidence was associated with sex, attained age, calendar period, tall body height, age at the beginning of exposure, and facility type. There was no association found between risk of CNS tumour incidence and body mass index, smoking (males) and alcohol consumption status. The study did not find an effect of the total external gamma radiation dose absorbed in the brain on risk of CNS tumour incidence irrespective of whether an adjustment for the total external neutron dose absorbed in the brain was included or not. Excess relative risk per 1Gy of external gamma brain dose was 0.05 (95% confidence interval (CI) -0.30; 0.70) for all CNS tumours, -0.18 (95% CI -; 0.44) for gliomas, and 0.38 (95% CI -0.32; 2.08) for meningiomas without adjustment for total neutron brain dose. There was no effect modification by sex, attained age, age at hire or facility.

Structural Indices of the Communities of Benthic and Phytophilous Invertebrates in Water Bodies Differing in the Dose Rate of Ionizing Radiation

The structural indices of the communities of benthic and phytophilous invertebrates were studied in water bodies differing in the levels of external radiation dose rate within the Chornobyl exclusion zone. The macrofauna of invertebrates of all studied water bodies was characterized by low species richness, numbers, and biomass. The obtained results suggest that the benthic and phytophilous invertebrate fauna of the cooling pond of the Chornobyl Nuclear Power Plant differs in its structure from the fauna of other water bodies of the Chornobyl exclusion zone more significantly than these water bodies differ from each other in terms of dose load levels on the biota. We consider the main reason for these differences to be the succession processes in the ecosystem caused by the transformation of the cooling pond of the Chornobyl Nuclear Power Plant. There is no reason to claim that the influence of external ionizing radiation determines the change in the structural indices of the communities of benthic and phytophilous invertebrates in water bodies of the Chornobyl exclusion zone.

ЗАБОЛЕВАЕМОСТЬ САХАРНЫМ ДИАБЕТОМ 2 ТИПА И РИСК ЕГО ВОЗНИКНОВЕНИЯ У ЛИКВИДАТОРОВ ПОСЛЕДСТВИЙ АВАРИИ НА ЧАЭС, В ТОМ ЧИСЛЕ РАБОТНИКОВ ПРЕДПРИЯТИЙ АТОМНОЙ ПРОМЫШЛЕННОСТИ

Summary: Investigation purposes Diabetes mellitus (DM) occupies the largest share in the structure of endocrine system diseases, nutritional disorders and metabolic disorders, which is currently one of the important priorities of national health systems. Research on certain groups of the population with their own harmful occupational risk factors is relevant. Analysis of the incidence of diabetes mellitus of the second type - T2DM (ICD 10: E11-E11.9) of liquidators of the consequences of the Chernobyl accident ‒ workers of nuclear industry enterprises for 30 years of observation and assessment of the radiation risk of its occurrence. Material and methods: The study includes data from the Industry register of persons exposed to radiation as a result of the Chernobyl accident over a thirty-year period, having a verified dose of external radiation received during work in the 30 km zone of the Chernobyl nuclear power plant, men – 12663 people, 1327, of whom have data on the dose of occupational irradiation. The Poisson process with an intensity parameter was chosen as a statistical model of morbidity. Results: The incidence of T2DM in liquidators of the consequences of the Chernobyl accident was estimated by age and sex groups. On the basis of the obtained file of individual unstratified data, an analytical likelihood function for the Poisson process was constructed and the value of the excess relative risk (ERR) of T2DM incidence was calculated and the nature of the dose dependence of RR was investigated. A cohort epidemiological study of a group of liquidators in 1986–1990 was carried out. over a thirty-year period, depending on the dose, both received during the liquidation of the consequences of the Chernobyl accident, and during professional work with radioactive substances (RS) and sources of ionizing radiation (IRS). Direct estimates of the radiogenic risk of diabetes mellitus are given. Different values ​​of risk were noted when using doses from different types of radiation. There was no significant increase in the risk of disease per dose unit (ERR / Sv). Conclusion: With the aging of the cohort of liquidators, an increase in the incidence of T2DM was noted in both men and women. The results obtained on the assessment of the radiation risk of T2DM at this stage are taken as preliminary, since the use of radiation risk in the development of radiation safety regulations requires a total dose from all types of exposure (professional, emergency, medical, natural).

Assessment of the radiation exposure dose in air-water plants of various water body types in Polissia

The study aimed to determine the exposure patterns in air-water plants of Polissia reservoirs located in the territories with different levels of radionuclide contamination of the catchment area, and to assess the risk of radiation damage to air-water plants based on the radionuclides content in the bottom sediments of the reservoirs. To determine the regularities of the air-aquatic plant irradiation dose formation the results of the 2014– 2020 research were used on the specific activity of 90Sr and 137Cs in water, bottom sediments, and a set of data on the radionuclides content in aerial organs, rhizomes, and roots of Phragmites australis (Cav.) Trin as well as Tуpha angustifolia L. in the ecosystems of reservoirs outside the exclusion zone – Kyivskyi (Strakholissia village) and Povchanskyi (Povch village, Korostensky district, Zhytomyr Region) reservoirs, Bile lake (Bile village, Varasky District, Rivne Oblast), and Lake Lisove (village of Nova Markovka, Vyshgorod district, Kyiv region); in the exclusion zone – Lake Glyboke, Yanivsky Zaton and the averaged samples from the two reservoirs formed in the course of draining of the Chernobyl Nuclear Power Plant cooling reservoir. The specific activity of 90Sr in the samples was determined by the oxalate method, and 137Cs was determined by the gamma spectrometric method in the aquatic radioecology department of the Institute of Hydrobiology of the National Academy of Sciences of Ukraine. The heterogeneity of the plants environment, the attenuation of g-radiation by water masses and biomass, and the level of radionuclide contamination of aboveground and underground organs were taken into account while determining plant radiation dose rates. It was established that during the research period the dose rate of external g-irradiation of underwater organs of air-water plants that is formed by 137Cs concentrated in water masses, is 100 or more times lower than that of 137Cs radiation accumulated in bottom sediments, i.e. it can be neglected when determining the total dose. In the studied reservoirs of the exclusion zone, the external irradiation dose rate in air-water plants was 7.5–271 μGy/day, outside the exclusion zone it was 0.1–33 μGy/day. The dose rate of internal irradiation in the exclusion zone reservoirs air-water plants was 1.2–50 μGy/day, outside the exclusion zone it was 0.01–15 μGy/day. The total radiation dose rate in the exclusion zone reservoirs air-water plants was 9–289 μGy/day, in the reservoirs outside the exclusion zone it was 0.65–48 μGy/day. In the reservoirs outside the exclusion zone, the contribution of the external component to the total dose rate ranged from 69 to 81 %, in reservoirs within the exclusion zone it ranged from 69 to 78 %. The study established the levels of radionuclide content in the bottom sediments corresponding to various degrees of radiobiological effects manifestation in air-water plants. It was established that the plants of most reservoirs, in particular the Kyiv Reservoir, develop in the conditions of radiation well-being zones of and physiological masking, in some reservoirs of the exclusion zone they develop under the conditions of ecological masking zones. Key words: air-water plants, dose rate, bottom sediments, radionuclides.