Radiation and Risk

Among cultivated crops, wheat along with rye accumulates 137Cs in grain and green biomass to the lowest extent; therefore, its cultivation in radioactively contaminated areas is a radiologically justified measure for reducing the population’s collective dose. Spring crops are of particular interest because of their shorter life cycle and less pronounced root development compared with winter crops. The aim of this study was to investigate the distribution parameters of 137Cs and 40K in soft spring golden wheat (Triticum aestivum L. var. Lutescens) grown on a radioactively contaminated sod-podzolic loam that had not been subjected to intensive ameliorative practices. The hypothesis was tested that the transfer of 137Cs and 40K to wheat organs is related to soil profile depth. Samples were collected from an arable field where the contamination density of 137Cs in the 0-30 cm soil layer was 34244 kBq/m2. Agrochemical analysis indicated slightly acidic pH and moderately high contents of organic matter, available potassium, and phosphorus. Cesium and potassium were found to be distributed among plant organs in similar proportions. Concentration ratios and aggregated transfer factors for the radionuclides were determined from soil to roots, stems, inflorescences, and grain. The concentration ratios were compared with IAEA data for cereal crops in temperate environments and, for cesium, were in close agreement with the published values. The IAEA concentration ratios for potassium in wheat stems and shoots (1.1; n=2) appeared to be substantially underestimated compared with the values obtained in the present study (4.411.37; n=5), whereas good agreement was observed for potassium transfer to grain. It was shown that, with increasing soil profile depth, the aggregated transfer factors for 137Cs and 40K remain stable, reflecting uniform uptake of these radionuclides throughout the root zone. No effect of the texture of the subsoil horizon or the plough pan on the transfer of 137Cs and 40K was observed. Spearman’s rank correlation analysis based on small sample sizes revealed a negative correlation (rs=-0.9) between sample values of the activity concentrations of 137Cs and 40K along the following translocation pathways: 40K in soil – 137Cs in inflorescences; 40K in soil – 137Cs in grain; 40K in inflorescences – 137Cs in grain; and 40K in grain – 137Cs in grain.

One of the ways to increase the effectiveness of high-tech proton therapy, along with combined radiation schemes, is to enhance the damaging effect on the tumor by administering radiosensitizing agents. The use of high Z metal nanoparticles seems promising for these aims. The purpose of this work is to study the cytotoxicity of HfN nanoparticles and to investigate their influence on the effectiveness of combined neutron-proton irradiation of the Chinese hamster normal (V-79) and tumor cells (B14-150). HfN nanoparticles synthesized by laser ablation in acetonitrile ("MEPhI", Moscow) with silane-polyethylene glycol surface modification (Shemyakin-Ovchinnikov Institute of bioorganic chemistry of RAS, Moscow) were used. Doses of neutrons and protons from the NG-14 portable neutron generator and the Prometheus proton therapy complex were 1 Gy and 5 Gy, respectively. The neutron contribution to the total dose was 40% at the combined "neutrons→protons" mode exposure, and the interval between neutrons and protons fractions was 1 hour. HfN nanoparticles had proved to have no cytotoxic effect on normal and tumor cells of the Chinese hamster at the concentration range of 10-800 μg/ml. Pre-incubation of cells with HfN nanoparticles led to no statistically significant changes in the efficiency of combined irradiation with neutrons and protons. The observed absence of the additional damaging effect from HfN nanoparticles in combined irradiation may be due the negligible dose enhancement factor at the macroscopic level and its rapid fall-off in the close vicinities from nanoparticles surface, 3-5 nm, at the microscopic level, further compromised by the effect of protein corona formation.

Microglial cells account for 5% to 13% of the total cell population in the central nervous system (CNS). In the mature CNS, microglia are capable of self-renewal and can rapidly proliferate in response to injury. A primary function of microglial cells is the initiation and maintenance of the immune response, alongside key roles in inducing inflammation, maintaining brain homeostasis, and regulating neuronal networks. The diverse functions of microglia include the control of neurogenesis and synaptic pruning, as well as providing trophic support to neurons. This review systematizes data on the morphological, molecular-biochemical, and physiological changes in microglia following exposure to ionizing radiation, considering the dose and quality of the radiation. It examines the specific morphological, molecular, biochemical, and physiological processes occurring in microglia under exposure to various radiation doses. Additionally, the review presents data on microglial functioning associated with the long-term effects of different radiation doses and the impact of irradiation on cognitive functions.

Medicinal plants and phytopreparations produced from them represent one of the potential channels of radionuclide intake into the human body. As part of the study, an analysis of the accumulation of Sr-90 in wild medicinal plants growing in the Voronezh region was carried out. For the study, 10 types of plant raw materials were selected, including aboveground parts (grass), leaves, inflorescences and root systems. In parallel, soil samples were taken from a depth of 0-20 cm to assess the background content of 90Sr. The specific activity was measured using the RADEK MKGB-01 spectrometer. All analyzed samples of raw materials comply with the standards for the content of 90Sr. Statistical analysis revealed a strong positive correlation between the specific activity of the radionuclide in the soil and in the plant raw materials (r=0.62-0.97), which makes it possible to assert that its absorption from the soil substrate is the main route of the radionuclide entry into the plants. The unevenness of the distribution of the radioisotope in various plant organs has been established. The highest accumulation capacity is characteristic of root systems (accumulation coefficients up to 2.0). The leaves of the studied plants also show a relatively high level of accumulation (accumulation coefficient >1.0). Minimum values of accumulation coefficient are noted for flowers and inflorescences. The data obtained make it possible to predict radiation risks during the procurement of medicinal raw materials in the conditions of chernozem soils of the Voronezh region.

As a result of a comprehensive study of peripheral blood cell populations and hematopoietic organs in mice exposed to 3 Gy dose and kept in contact with non-irradiated mice for 90 days, a "rescue effect" was observed at the interorganism level. In general, the immediate aftermath of the experiment was characterized by a reduction in the severity of radiation-induced disorders in the organism of exposed mice due to their contact with non-irradiated mice. This was manifested by the normalization of the percentage of lymphocytes, neutrophils, and monocytes, as well as a decrease in the severity of the genotoxic effects of radiation, as evidenced by a decrease in the frequency of erythrocytes with micronucleus. The p-value values (differences from the irradiated control) ranged from 1,3*10-5 to 0,03. In the long term after the exposure, the phenomenon of increased severity of radiation-induced changes in the organism of irradiated mice due to their contact with non-irradiated individuals prevailed. This is manifested by a decrease in the absolute number of leukocytes, a decrease in the percentage of lymphocytes and an increase in the relative number of neutrophils. In addition, there was an increase in the level of monocytes (the 30-th day) and eosinophils (the 30-th and the 90-th day). There was an increase in the frequency of normochromatophilic erythrocytes with micronuclei (the 30-th day). The p-value values ranged from 6,0*10-5 to 0,07. At the end of the experiment (the 90-th day), there was a significant increase in the number of nucleated bone marrow cells and a decrease in the number of nucleated thymus cells in irradiated individuals that were in contact with non-irradiated mice (cage with a septum, p=0,03, and without a septum, p=0,01, respectively). The inconsistency of the phenomenon under consideration throughout the experiment highlights the complex nature of the "interaction" between the effects of post-radiation recovery and the influence of signals from unexposed "bystander animals".