External Gamma Irradiation Research Articles

АНАЛИЗ ВЛИЯНИЯ ОБЛУЧЕНИЯ НА МУЛЬТИМОРБИДНОСТЬ УЧАСТНИКОВ ЛИКВИДАЦИИ ПОСЛЕДСТВИЙ АВАРИИ НА ЧЕРНОБЫЛЬСКОЙ АЭС

Purpose: To give a general idea of the most common combinations of diseases in the male population of the Russian Federation and to identify the combinations of diseases, the development of which could be influenced by ionising radiation. Material and methods: Cohort study of the influence of external gamma irradiation on multimorbidity of the Chernobyl accident liquidation participants according to the data of the National Radiation Epidemiological Registry. Multimorbidity was defined as the presence in one participant of the cohort of two or more diseases from the list consisting of ten groups of diagnoses: diseases of lower respiratory tract, diseases of musculoskeletal system, diseases of endocrine system, mental disorders, oncology, neurology, diseases of digestive organs, diseases of cardiovascular system, diseases of genitourinary system, diseases of sense organs. The cohort consisted of men born between 1919 and 1969 who worked in the accident zone from 1986 to 1987 and had a documented whole-body external gamma dose. Cohort follow-up period: 1992–2021. The cohort size at the beginning of the follow-up was 59 290 people. The study participants were divided into two groups according to external gamma dose: up to 150 mGy – 34602 individuals, 150 mGy and more – 24 688 individuals. For all possible combinations of diagnoses, relative radiation risk was calculated as a measure of the association of exposure with diseases. The relative radiation risk was considered statistically significant if the left border of the one-sided 95 % confidence interval was greater than 1. Statistical analyses were performed using the R programming language for statistical computing and the R arules package. Results: During 30 years of follow-up, multimorbidity was noted in 62 % of individuals. The most common combinations of chronic diseases were combinations of cardiovascular diseases with digestive diseases (23 % of the original cohort), with lower respiratory diseases (22 %) and with musculoskeletal diseases (18 %). A combination of all four diagnosis groups was identified in 5 % of individuals. Nineteen multimorbid combinations with statistically significant relative radiation risk in the range (1.07–1.23) were identified. Conclusions: No effect of radiation exposure on the number of individuals with multimorbidity was found, but in the studied cohort there are individuals with cardiovascular diseases, endocrine diseases, oncology and combinations of these groups of diagnoses with diseases of other body systems may be caused by radiation exposure. The statistically significant relative radiation risk for combinations of diagnoses is, in general, greater than for the individual diseases that make up these combinations.

Changes in the structural and functional state of the thyroid gland of small mammals when exposed to low-intensity chronic radiation.

The study gives a morphofunctional assessment of the state of the thyroid gland of tundra voles (Microtus oeconomus Pall.) in conditions of an increased radiation background (the Ukhta district of the Komi Republic (Russia) and the 30-km zone of the Chernobyl NPP), as well as in an experiment with chronic external gamma irradiation in the low dose range. The work summarizes the experience of more than 35 years of field and laboratory research. The authors have noted the high sensitivity of the thyroid gland to chronic radiation against the general irradiation of the organism both in natural conditions and in the experiment. The repeatability of the observed effects in voles from natural populations and the comparability of some effects with the morphological changes occurring in animals after exposure to ionizing radiation in the experiment indicates the radiation nature of these effects. The tundra voles living in conditions of increased radiation background have been identified for a greater variety of morphological rearrangements in the thyroid parenchyma than the experimental animals. The complex and ambiguous nature of the thyroid gland responses to radiation exposure indicates the possibility of a significant increase in the risk of negative effects of ionizing radiation in contrast with the expected results of biological effects' extrapolation from high to low doses.

ИЗУЧЕНИЕ ПЕРСПЕКТИВ ПРИМЕНЕНИЯ ИНТРАГАСТРАЛЬНЫХ КОКТЕЙЛЕЙ С ПРЕПАРАТАМИ КОРНЯ СОЛОДКИ РАЗНОГО ГАЗОВОГО СОСТАВА ПРИ COVID-19 НА ЭКСПЕРИМЕНТАЛЬНОЙ МОДЕЛИ ИММУНОПАТОЛОГИИ, ВЫЗВАННОЙ ГАММА ОБЛУЧЕНИЕМ ЖИВОТНЫХ

This article is devoted to the results of an experimental study, the purpose of which was to clarify the mechanisms of action on the immune system of intragastric cocktails of different gas compositions (oxygen, carbon dioxide, and nitrogen), including in combination with licorice root preparations, with the subsequent prospect of use at different stages of rehabilitation of patients after COVID-19. The experimental model was male Wistar rats, whose acute external gamma irradiation causes a state of immunopathology similar to COVID-19. The data obtained indicated the presence of immunological correction effects under the influence of the studied agents. Moreover, it was noted that in cases of violations of the cellular component of immunity, preference should be given to nitrogen as a dispersion medium and carbon dioxide as a humoral medium, while the immunosuppressive effect is caused by cocktails with oxygen. Thus, it has been established that intragastric cocktails of different compositions differ from each other in the characteristics of the reactions that occur to their use, which in the future can be used at different stages of rehabilitation of patients with COVID-19 and for preventive purposes in the interpandemic period as differentiated methods of immunological correction. This requires additional clinical studies in accordance with the principles of evidence-based medicine.

Comparative cytotoxic activity of lutein or cisplatin doped with liposomes against breast cancer cell lines after radiotherapy

Interactions of the anticancer drug cisplatin or the antioxidant drug lutein with liposomes as model membranes were characterized. All liposomes had the almost spherical shape, taking into account that lyposomes without the said drugs were more evenly dispersed and tended to aggregate less. The mean size diameter of empty liposomal samples was 617.90 ± 75.64 nm, while liposomes loaded with cisplatin, lutein and a cisplatin+lutein combination were 425.60 ± 64.74 nm, 877.85 ± 93.90 nm and 189.91 ± 136.84 nm, respectively, in diameter. The incorporation of cisplatin or lutein into liposome membranes resulted in an increase in the zeta potential values. The lowest zeta potential value was achieved in lyposomes containing cisplatin in combination with lutein. The addition of cisplatin to liposomes caused a shift in the melting temperature towards higher values than those of the main peak of empty liposomes indicating a conformational disorder within the phospholipids. Encapsulation of lutein into liposomes resulted in the disappearance of the main characteristic endothermic peak of pure liposomes. FTIR spectroscopy confirmed the interaction of lutein or cisplatin with functional groups in liposomes. In the absence of external gamma-irradiation, the IC50 value for free lutein in the cytotoxic assay with MCF-7 treated cells was 10.62 gg/ml, while free cisplatin showed the IC50 value of 41.02 gg/ml. IC50 was 65.84 gg/ml and 34.29 gg/ml for nanoliposomal lutein and cisplatin, respectively. Using the combined therapy of gamma irradiation at dose rate 5 Gray followed by 10 Gray, the IC50 value for free lutein changed from 17.0 to 9.5 gg/ml. IC50 for free cisplatin changed from 51.00 to 43.09 gg/ml. This study showed that cytotoxic effect of a standard form of lutein is stronger than that of nanoliposomal lutein. The current evidence reveals a new regimen for the treatment during which replacing cisplatin with free lutein increases anticancer activity against the MCF-7 cancer cell line.

Study of radiation-thermal damage in white rats

Currently, despite the improvement of radiation safety measures, there is a risk of increasing frequency of radiation accidents and various disasters accompanied by explosions, fires and emissions of radionuclides. Emergencies (emergencies) of peacetime and wartime, especially accidents at radiation-hazardous facilities, including nuclear power plants, carry the danger not only of irradiation of people, but also at the same time thermal burns, mechanical injuries, chemical poisoning by harmful gorenje products, as well as other lesions. Experimental modeling of acute radiation and burn disease was carried out both separately and in combination. It was found that external total gamma irradiation of white rats at a dose of 7.5 Gy causes severe radiation sickness with characteristic clinical signs and high mortality of irradiated animals. A heat stroke simulation was performed by applying a metal plate heated to 190°C with an exposure time of 5 and 8 seconds. It turned out that the degree of burn depends on the time of contact with the surface of the body: its application within 5 seconds caused a burn of the III-A degree, an 8-second exposure of the IIIB degree, which was confirmed by the timing of formation, rejection of eshar and complete healing of the thermal lesion. The aggravating effect of ionizing radiation on the course and outcome of combined radiation-thermal pathology is demonstrated.

External dose estimates of laboratory rats and mice during exposure to dispersed neutron-activated 56Mn powder.

Estimates of external absorbed dose in experimental animals exposed to sprayed neutron-activated 56Mn powder are necessary for comparison with internal absorbed doses estimated under the same exposure conditions, which is required for a correct interpretation of the observed biological effects. It has been established that the measured dose of external absorbed dose as a result of gamma irradiation range 1–15 mGy, which is order of magnitude less than the maximal dose of internal gamma and beta irradiation of the whole body of the same experimental animals irradiated under the same conditions: according to the available literature data, the maximal values ​​of absorbed dose of internal gamma-beta irradiation of the whole body are in the range of 330 mGy–1200 mGy for mice and 100 mGy–150 mGy for rats. It is concluded that under the conditions of experiments with dispersed neutron-activated powder 56MnO2, internal gamma-beta irradiation of experimental animals is the main factor of radiation exposure compared to external gamma irradiation.

Radiolytic behaviour of a TODGA based solvent under alpha irradiation

In this work the radiolytic stability of a TODGA based solvent has been investigated in alpha radiolysis measured by solvent extraction distribution ratios. Solutions of TODGA in alkane diluents have been subjected to 244Cm α-irradiation in the presence of nitric acid (0.5 M) and analysed using radiometric techniques to determine their rates of radiolytic degradation. It was shown that alpha radiolysis, similarly to external gamma irradiation, produces an exponential decrease of the free TODGA concentration of the organic solvent as the solvent is degraded with increasing absorbed alpha dose. The degradation constant, obtained from the exponential decrease, indicates that the free TODGA concentration is halved with every 1.0 MGy deposited to the solvent from internal alpha decay. This result could be useful information when dealing with high activity actinide solutions in TODGA based solvent extraction systems.

Behaviour of magnesium phosphate cement-based materials under gamma and alpha irradiation

Stabilization and solidification of low- and intermediate-level radioactive waste using Portland cement, possibly blended with fly ash or blastfurnace slag, is a well-established practice. However, when the waste contains high amounts of alpha emitters, this solution can be restricted by the strong release of radiolytic gases, wherein H2 is the most abundant. This work investigates the interest of using magnesium potassium phosphate cement (MPC), a binder with a high chemical water demand, as a possible substitute to Portland cement (PC). The radiolytic gas production of PC and MPC pastes and mortars is determined under external gamma and internal alpha irradiation. The H2 radiolytic yield of MPC materials is found to be 2 to 3 times smaller than that of PC references, provided that the main part of the mixing water is consumed by K-struvite formation. Moreover, gamma irradiation of a MPC mortar up to an integrated dose of 10 MGy has no significant influence on its mechanical strength (flexural, compressive) nor on its mineralogy. MPC materials are thus potential candidates for the conditioning of high amounts of radioactivity with limited H2 release. The H2 production of MPC materials can be reduced further by adding radical scavengers or H2 getters within the matrix. However, other radiolytic gases such as O2 are often produced, making these solutions potentially less attractive considering the concern of pressure build-up within the cemented waste package.

The structure of leukemia in the personnel employed at the production Association “Mayak” in 1948-1958

The spectrum of leucosis among the workers of the first production facility of Russian atomic industry employed in the period of production development - 1948-1958 is presented. The characteristic of the latent period of malignant neoplasms of hematopoietic tissue and individual accumulated doses of external gamma irradiation of personnel with established outcomes in the form of leukemia is given.

Hto, Tritiated Amino Acid Exposure and External Exposure Induce Differential Effects on Hematopoiesis and Iron Metabolism

The increased potential for tritium releases from either nuclear reactors or from new facilities raises questions about the appropriateness of the current ICRP and WHO recommendations for tritium exposures to human populations. To study the potential toxicity of tritium as a function of dose, including at a regulatory level, mice were chronically exposed to tritium in drinking water at one of three concentrations, 10 kBq.l−1, 1 MBq.l−1 or 20 MBq.l−1. Tritium was administered as either HTO or as tritiated non-essential amino acids (TAA). After one month’s exposure, a dose-dependent decrease in red blood cells (RBC) and iron deprivation was seen in all TAA exposed groups, but not in the HTO exposed groups. After eight months of exposure this RBC decrease was compensated by an increase in mean globular volume - suggesting the occurrence of an iron deficit-associated anemia. The analysis of hematopoiesis, of red blood cell retention in the spleen and of iron metabolism in the liver, the kidneys and the intestine suggested that the iron deficit was due to a decrease in iron absorption from the intestine. In contrast, mice exposed to external gamma irradiation at equivalent dose rates did not show any change in red blood cell numbers, white blood cell numbers or in the plasma iron concentration. These results showed that health effects only appeared following chronic exposure to concentrations of tritium above regulatory levels and the effects seen were dependent upon the speciation of tritium.

Adverse effects induced by chronic gamma irradiation in progeny of adult fish not affecting parental reproductive performance

Multigenerational studies have become of great interest in ecotoxicology since the consequence of parental exposure to contaminants on offspring generations was established in situ or in laboratory conditions. The present study mainly examined the chronic effects of external Cs-137 gamma irradiation exposure at 4 dose rates (control, 0.5, 5, and 50 mGy h-1 ) on adult zebrafish (F0) exposed for 10 d and their progeny (F1) exposed or unexposed for 4 to 5 d. The main endpoints investigated included parental reproductive performance, embryo-larval survival, DNA alterations, and reactive oxygen species (ROS) production in F0 and F1. No effects on reproductive success, fecundity, or egg fertilization rate were observed. However, drastic effects were observed on F1 exposed to 50 mGy h-1 , resulting in a mortality rate of 100%. The drastic effects were also observed when the progeny was not irradiated. It was demonstrated that the sensitivity of the embryos was mainly attributable to parental irradiation. Moreover, these drastic effects induced by adult irradiation disappeared over time when 10 d-irradiated adults were placed in a nonirradiated condition. Alterations in larval DNA were observed for the 3 dose rates, and an increase of ROS production was also shown for the 2 lowest dose rates. The present study improves our understanding of the consequences of parental exposure conditions to the progeny. Furthermore, it provides an incentive to take transmitted generational effects into account in ecological risk assessments. Environ Toxicol Chem 2019;38:2556-2567. © 2019 SETAC.

Adıyaman İlinde Dış Mekan Radyoaktivitesi ve Sağlık Risklerinin Değerlendirilmesi

This study was conducted to determine the outdoor absorbed gamma dose levels in and around Adiyaman province in the southeast of Turkey. Measurements were performed using a portable plastic scintillator at 94 different points (Eberline Smart Portable (ESP-2) model). Three readings were made for each measurement and the mean of these three values were determined and the gamma dose values were determined for each measurement region. External gamma irradiation velocities were measured between 63.5 (nGy/h) and 380.2 (nGy/h) levels in Adıyaman and surrounding areas and the mean value was calculated as 144.3 (nGy/h). This value corresponds to the average effective dose equivalent of 177 μSv per year. The lifetime averages of cancer risk values for ICRP 103, BEIR VII and ICRP 60 were found to be 0.071, 0.079 and 0.089, respectively. The results obtained with the results of similar studies in other provinces in Turkey and compared with the world average.

Abstract 3921: Poly(ADP-ribose) polymerase 1 (PARP-1) targeting radionuclides are highly cytotoxic across a panel of 20 neuroblastoma cell lines

Abstract Introduction: Neuroblastoma is the most common extracranial solid malignancy in childhood, with only up to 50% 5-year survival in high-risk cases. It overexpresses the nuclear enzyme PARP-1, which can be targeted for specific delivery of radionuclides to DNA. Two such novel radiolabeled small molecule therapeutics are [211At]MM4, containing an alpha particle-emitting astatine-211, and [125I]KX1, containing an Auger electron-emitting iodine-125. Methods: Twenty human neuroblastoma cell lines were screened in vitro for sensitivity to [211At]MM4 and [125I]KX1, with non-targeted radionuclides and non-radioactive PARP-1 inhibitors as controls. Next, one sensitive and one resistant cell line was chosen for dosimetry based on radiopharmacology and cellular geometry properties measured specific to each therapeutic and cell line. Monte Carlo simulation was then performed to calculate the radiation dose to the cell nucleus at 50% cell kill. Relative biological effectiveness (RBE) of alpha and Auger particles against gamma irradiation was determined. Finally, the mechanism responsible for differential radiosensitivity across the twenty cell lines was examined by correlation with PARP-1 mRNA level. Results: [211At]MM4 and [125I]KX1 showed closely correlated (R2=0.93) cytotoxicity across the twenty neuroblastoma cell lines. [211At]MM4 demonstrated 102-103 times and 108-109 times greater cytotoxic potency compared to unbound 211At and its non-radioactive PARP-1 inhibitor analog respectively. More sensitive cell lines demonstrated greater sensitivity to [211At]MM4 even when normalized against their sensitivity to alpha radiation (R2=0.40, p<0.01). [125I]KX1 also showed 104-106 times greater potency than its non-radioactive analog. No cell kill by biochemical inhibition of PARP-1 was seen at therapeutic doses of [211At]MM4 and [125I]KX1.The sensitive and resistant cell lines had similar PARP-1 binding of [211At]MM4 and [125I]KX1, but only the sensitive cell line had significantly higher RBE of alpha (9.2) and Auger (4.2) radiation compared to external gamma irradiation. RBE of alpha against Auger therapy was similar in both sensitive (2.2) and insensitive (1.9) cell lines. Cytotoxic sensitivity to PARP-1 targeted radiopharmaceutical was not correlated with PARP-1 mRNA level (R2=0.10, p=0.17). Conclusion: Delivery of alpha and Auger emitters directly to neuroblastoma nuclear DNA by radiolabeled PARP-1 inhibitors results in enhanced cytotoxicity without requiring enzymatic PARP-1 inhibition. Sensitivity to radiolabeled PARP-1 inhibitors is characterized by increased RBE against gamma irradiation and only partially explained by inherent radiosensitivity, warranting further investigation of underlying biological factors. This promising efficacy in vitro can be examined in vivo and in other cancer types for broader application. Citation Format: Hwan Lee, Adam Mansfield, Minu Samanta, Sean W. Reilly, Kuiying Xu, Sean D. Carlin, John M. Maris, Robert H. Mach, Mehran Makvandi, Daniel A. Pryma. Poly(ADP-ribose) polymerase 1 (PARP-1) targeting radionuclides are highly cytotoxic across a panel of 20 neuroblastoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3921.

THE INDICES OF MORBIDITY OF PANCREAS CANCER IN WORKERS OF RADIATION DANGEROUS ENTERPRISE

In Russia, during last decades increasing of morbidity of pancreas cancer is observed. This disease is among leading causes in the structure of mortality of malignant neoplasms. The data concerning effect of ionizing irradiation on development of pancreas cancer is ambiguous. The analysis was carried out concerning indices of morbidity of pancreas cancer in cohort of workers for the first time hired to enterprise of nuclear industry production association «Mayak» in 1948-1982 exposed to prolonged total external gamma-irradiation and internal alpha-irradiation by incorporated plutonium. It is established that in both considered cohort and total population, indices of morbidity of pancreas cancer depended on such non-radiation factors as attained age, gender, calendar period of observation, smoking and value of smoking index, alcohol abuse. The study established increasing of standardized by age indices of morbidity of pancreas cancer in workers exposed to prolonged external gamma-irradiation in doses 0.5 Gy and higher. The effect of internal alpha-irradiation on indices of morbidity of pancreas cancer was absent in examined cohort.

Kerma conversion factors for modern glass buildings in radioactively contaminated areas

To improve the estimation of external gamma irradiation from deposited radioactivity in urban environments a model of a modern office or residential building with glass facades was set up with eleven different building heights. Kerma conversion factors for the floors inside the building from contamination on different types of surfaces were determined by using the Monte Carlo code MCNP6 for the primary gamma energies 0.3 , 0.662 and 3.0 MeV and for three different environmental scenarios. The kerma conversion factors were expressed as formulas for each possible deposition area for contaminants. The importance of the determined factors was shown by comparing them to previously generally used factors for multistorey house blocks.

Защита сперматогенеза β-каротином при радиационных воздействиях. Сообщение 2: обогащение каротиноидом рациона при однократном остром внешнем γ-облучении

Purpose: Experimental evaluation of the efficiency of β-carotene by single acute γ-irradiation of spermatogenesis correction radiation-induced disorders in males (♂) of Wistar rats during prolonged carotenoid enrichment of a diet. Material and methods: Single external gamma irradiation ♂ was performed at the IGUR facility (137Cs, dose rate 0.029 Gy/s). The carotenoid used up on feeding ♂ in a mixture with cottage cheese for 2 months before irradiation, then – throughout the study period three times a week. During the days that ♂ were in cells with intact ♀ β-carotene was administered ♂ orally by a probe in the form of a suspension in vegetable oil. The damage and effectiveness of protection of spermatogenesis of irradiated ♂ were judged by the state of their reproductive function. Results: β-carotene in intact ♂ rats reduced the overall, pre- and postimplantation embryonic mortality, respectively, from 29 to 14, from 22 to 9, and from 10 to 5 %. At the stage of mature sperm following irradiation ♂ dose of 3 Gy – total and pre-implantation mortality from 45 to 29, and from 23 to 9 %. After irradiation at a dose of 5 Gy – total, an pre- and postimplantation induced embryonic death, respectively, from 67 to 56, from 23 to 13 % and from 56 to 43 %. At the stage of spermatids after irradiation in dose 1 Gy – pre-implantation mortality from 23 to 9 %; in the dose of 3 Gy – the number of dead embryos in pregnant ♀ from 12 to 3; at a dose of 5 Gy total embryonic mortality from 57 to 49 %. Carotenoid enrichment of a diet of ♂ irradiated at doses of 3 and 5 Gy, has not corrective impact on the state indicators of their reproductive function, evaluated at fertilization of ♀ sperm irradiated at the stage of spermatocyte. At the stage of spermatogonia after irradiation at a dose of 3 Gy β-carotene increased fertility of ♂ 7 to 12 living embryos and reduced the overall, before – induced postimplantation mortality, respectively, with 63 and 43, from 42 to 25 and from 35 to 19 %. No statistically significant effect of β-carotene on the weight loss of the gonads irradiated ♂ was revealed. Compared to short-term regimen, long-term enrichment of a diet of irradiated ♂ β-carotene more effectively reduced embryonic mortality of their offspring. Conclusions: Correction effects of β-carotene enrichment of the diet in radiation-induced disturbances by single acute external γ-irradiation at doses of 3 and 5 Gy of spermatogenesis in Wistar rats at stages of mature spermatozoa, spermatids and spermatogonia have been established.

Assessment of radiological safety of abandoned tantalite mining sites in Oke-Ogun, Oyo State, Nigeria

Introduction: Tantalite and other solid mineral deposits in Oke-Ogun occupy a very large landscape, and the possibilities of further exploration in new landscape and abandoning unproductive sites cannot be ruled out. These landscapes when abandoned become hideout for criminals and ritualistic activities which pose a great threat to the wellness of the people in the area and Nigerians at large. Objectives: This study attempts to investigate the radiological safety of these abandoned mines so as to convert them to economical valuable sites that can serve as a means of employment for population of the unemployed youth in the area and Nigeria at large. Materials and Methods: A total of seventeen soil samples were randomly selected. These samples were processed and analyzed for activity concentrations of 226Ra, 232Th, and 40K using Hyper Pure Germanium Gamma Spectrometer. RESidual RADioactivity software version (6.5), a computer program developed by the Environmental Assessment Division of Argonne National Laboratory, was used for dose prediction for 70 years using the activity concentrations of soil samples from all the selected sites as its input parameter for the software. Predicted doses were estimated with respect to the three exposure pathways, namely external gamma irradiation from radionuclides in the soil samples, inhalation of dust particles, and inadvertent ingestion of soil. Results: The measured activity concentrations of radionuclides: 226Ra for all the sites is in the range of (17–177) Bq/kg, 232Th in the range of (2–107) Bq/kg, and 40K in the range of (650–1667) Bq/kg. The predicted dose for all the sites is within the range of 0.05–0.35 mSv/y with Eluku mining site having values greater than the permissible limit of 0.25 mSv/y. The health implication of these values is that three of the sites (Gbedu, Sepenteri, and Komu) are safe for other usages. Conclusion: Any of these three mining sites may be used for re-creational purposes, fishing and building of estates to mention but a few.

LEUKEMIA INCIDENCE AND MORTALITY OF RECOVERY OPERATION WORKERS OF THE CHERNOBYL ACCIDENT: ASSESSMENT OF RADIATION RISKS FOR THE FOLLOW-UP PERIOD OF 1986–2014

Leukemia incidence in the cohort of Russian male recovery operation workers (liquidators) was estimated at 78110 people for the follow-up period 1986-2014. The average age of the liquidators at the time of entry into the zone of works for liquidation of the Chernobyl accident was 34 years. Radiation risk of leukemia incidence (with the exception of chronic lymphocytic leukemia) was analyzed for liquidators who had official data on the individual dose of external gamma radiation of the entire body accumulated over the period of work. During the follow-up period, 157 cases of leukemia were detected (with the exception of chronic lymphocytic leukemia). Collection and verification of data of hemoblastoses cases among persons exposed to radiation exposure was carried out according to a specially developed algorithm. The average dose of the liquidators was 108 mGy. During the period 1986–1997 was established a statistically significant (p<0.05) linear dose dependence of the leukemia incidence with an excess relative risk of ERR/Gy=4.17 (90% CI: 0.18, 13.24). From 1998 until the end of the follow-up period, as well as for the entire follow-up period (from 1986 to 2014), no statistically significant estimates of excess relative risk were found. For mortality, no statistically significant estimates of excess relative risk and relative risk were found for any of the observation periods. The obtained estimates of the radiation risk of morbidity indicate that a statistically significant excess leukemia incidence of liquidators, which may be associated with external gamma irradiation, is manifested in the first decade after exposure.

Effect of gamma radiation on the production of bystander signals from three earthworm species irradiated in vivo

The effect of gamma radiation delivered over 24 h on the induction of bystander signals of three earthworm species exposed in vivo was investigated: A. chlorotica, A. caliginosa, and E. tetraedra. Worms were exposed to external gamma irradiation (Co-60 source) for 24 h and samples of head, body, and clitellum were dissected from exposed and control worms and placed in culture medium for 24 h at 19 C. The harvested medium was filtered and assayed for expression of bystander signals using both clonogenic and mitochondrial reporter assays. Different responses were observed in the different species and in the different tissues. A. chlorotica worm-treated reporters show insignificant mitochondrial response for all sections, yet a significant clonogenic reduction in survival for body sections. A. caliginosa worm-treated reporters show a significant mitochondrial response for some sections and insignificant mitochondrial response and insignificant reduction in clonogenic survival for the rest. E. tetraedra worms from a control site show significant evidence of bystander signalling, measured by mitochondrial response in reporter cells, for all sections while those harvested from a contaminated site show insignificant changes in baseline signalling when exposed to the challenge dose. In vivo exposure of earthworm species shows evidence of bystander signalling using two different reporter assays. This effect varied between the different species and tissues. There is also evidence of attenuated bystander signalling in worms harvested from a site contaminated with radiation.

The Effectiveness of Sulfotozifan in the Case of External Gamma Irradiation

No radiation protection agents have been found to date which would not have toxic side effects while having radioprotective action of unlimited duration. Based on the screening of organo-element chemical compounds, a novel radioprotector sulfotozifan was selected to prevent the acute radiation syndrome in animals. Sulfotozifan belongs to compounds of hazard class 3 (National Standard of the Russian Federation (GOST) 12.1:007.76). A single subcutaneous administration of sulfotozifan at a dose of 38.0 mg / kg of body weight 2-4 days prior to the radiation exposure of animals to an absolute lethal dose, protects 80-100% of the animals from the radiation death. The pretreatment of animals with sulfotozifan 2-4 days prior to the irradiation has a positive effect on the animals’ clinical condition, normalizes their hematological parameters, increases the levels of T and B lymphocytes, inhibits peroxidation of lipids (POL), reduces the concentration of malondialdehyde (MDA), the final product of POL, in the erythrocyte hemolysate and blood plasma, and also promotes a reduction in the formation of radiotoxins. By its organoleptic, physicochemical, and bacterioscopic characteristics, the meat from irradiated animals pretreated with sulfotozifan does not differ significantly from those of the meat from the control animals and thus meets GOST requirements.