卷 69, 编号 5 (2024)

The paper presents the key outcomes of the 71^st Session of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) which took place during 20‒24 May 2024. National delegations from 30 UNSCEAR Member-states as well as the representatives of ten international organizations participated in the work of the Session. Within the framework of the meetings of the working group and subgroups the documents on the following projects were discussed: R.762 “Second primary cancer after radiotherapy”, R.763 “Evaluation of public exposures to ionizing radiation from natural and other sources”, R.764 “Epidemiological studies of radiation and cancer”, R.765 “Evaluation of diseases of the circulatory system from radiation exposure”, and R.766 “Nervous system effects of ionizing radiation”. The following Reports of the Secretariat have also been presented during the work of the Session: UNSCEAR/71/7 “Implementation of the Strategy to improve collection, analysis and dissemination of data on radiation exposure (including consideration of the Committee’s ad hoc working group on sources and exposure)”, UNSCEAR/71/8 “Implementation of the Committee’s Future Programme of Work and proposals for the period 2025-2029 (including consideration of the Committee’s ad hoc working group on effects and mechanisms)”, UNSCEAR/71/9 Implementation of public information and outreach strategy for 2025–2029”. Report to the UN General Assembly has been prepared based on the results of the Session.

Purpose: The operation of nuclear facilities such as NPPs is accompanied by the formation and release of tritium compounds into the environment. Currently available data on the biological effects of tritium, especially its organic compounds, are very scattered and fragmentary. There is still no consensus on the regulation of the content of inorganic and organic tritium compounds in different environments. This leads, for example, to a wide range of permissible levels of tritium in the environment in different countries, which requires additional experimental and calculated data in order to harmonize standards and ensure the safety of the members of the public living near such nuclear facilities. The purpose of this work is a comparative assessment of molecular cellular biological effects (formation of DNA double-strand breaks and micronuclei) upon exposure to individual tritiated compounds in mammals.

Material and methods: An in vivo study was conducted on male rats that received orally drinking water containing tritium oxide (HTO) or ³H-thymidine with a volumetric specific activity of 800 kBq/l for 10, 21 and 31 days. The number of DNA double-strand break (DSB) repair foci in rat splenocytes was assessed by immunocytochemical staining of phosphorylated histone H2AX (γH2AX) foci. An analysis of the frequencies of polychromatophilic erythrocytes (PCE) with micronuclei (MN) in the bone marrow of rats was also carried out.

Results: The genotoxic effect of both forms of tritium was determined by a significant yield of DNA DSBs in splenocytes and micronuclei in bone marrow PCE (a more pronounced effect on the 31st day of ³H-thymidine action). With chronic exposure to ³H-thymidine on days 21 and 31, the number of γH2AX foci significantly increases; in the case of HTO, the level of foci on days 31 does not significantly change. Exposure to HTO and ³H-thymidine caused approximately the same induction of PCE with micronuclei on days 10 and 21, but by day 31 the effect of ³H-thymidine was approximately 40 % greater than that of HTO. The experiment revealed a likely genotoxic effect of inhaled tritium in control rats that were kept in the same room as the rats that received HTO and ³H-thymidine orally. However, additional experiments are needed to confirm this effect.

Conclusion: The result of this work expands the understanding of the mutation process in mammalian cells exposed to internal ionizing radiation when taking compounds containing tritium. Increased genotoxicity is observed when rats ingest drinking water containing tritium with an activity of 800 kBq/l.

One of the requirements of the current Basic Sanitary Rules for Radiation Safety (OSPORB-99/2010) for the organization of work with open sources of radiation (radioactive materials) is the establishment of class of work that determines the zonality of industrial premises, requirements for their decoration, layout of technological equipment, ventilation, using of personal protective equipment, etc. Formalization of such requirements is necessary as in the design of enterprises, as well as for the organization safety working conditions for personnel in existing production facilities. The accumulated long-term experience of the country’s nuclear industry has shown the validity of the requirements imposed by the existing regulatory documents for the organization of work with open nuclides at the initial stage оrganisation of large-scale production. In article presents methodological approaches to the procedure for establishing class of work as at the projected enterprises of the nuclear industry and when adjusting the established classes of work at existing enterprises. Substantiated approaches to determining the value of the minimum significant activity of a radionuclide based on data on its radiotoxicity under internal irradiation (with inhalation intake), as required according to OSPORB-99/2010. In article proposed new values of the minimum significant activity for a number of radionuclides. Unified classes of work are recommended for individual sections of separation and sublimate uranium production. The procedure for determining the actual total activity at the workplaces of uranium production is described, taking into account data on the contamination of work surfaces and the volumetric activity of uranium aerosols in the air of the working area. These methodological approaches were implemented in the Guidelines of MU 2.6.1.02-03 “Establishment of class of work with open radionuclide sources in the handling of uranium and its compounds at the enterprises of JSC “TVEL”, in the Guidelines of MU 2.6.1. 044-08 “Establishment of class of work when dealing with open sources of radiation” as well as in the draft updated Guidelines for establishing the class of work when working with open sources of ionizing radiation, developed in 2024.

Introduction: The Bayesian approach has found wide application for the tasks of estimating doses of internal exposure under various intake scenarios. The South Ural Institute of Biophysics has accumulated considerable experience in using the Bayesian approach to estimate the expected effective doses of internal exposure for current individual dosimetry control when radionuclides intake into body by various ways. Attributing the type of compounds Moderate or Slow according to the NRB-99/2009 classification for acute inhalation of industrial Pu-239 compounds bias dose estimates to the lungs, which leads to the need to develop a new methodology.

Purpose: The development of a calculation methodology using the Bayesian approach for the case of acute inhalation of industrial Pu-239 compounds into the human body and its testing in artificial cases.

Material and methods: A technique is presented for interpreting a series of measurement results of Pu-239 activity in daily urine and/or daily feces to assess the distribution of intake, two key parameters of the biokinetic model of ICRP Publication 66 (the proportion of rapid absorption f_r and the rate of slow absorption into the blood s_s), as well as annual weighted equivalent doses to the lungs. The technique allows using a prior information about the estimated parameters and correctly processing measurement results below the detection limit.

Results: A jDose program has been created that implements the technique in ~ 20 minutes on a modern office computer. The program was tested on artificial cases with 10 measurements of Pu-239 activity in daily urine and 10 in daily feces during the first 10 days after acute inhalation intake at AMAD = 1 µm. Testing showed reproducibility of the set «true» parameter values in the range (average ± 2 standard deviations) with an increase in the proportion of unreliable measurement results. The increase in the proportion of unreliable measurement results had the greatest impact on the estimation of the coefficient of variation of the slow absorption rate parameter into the blood s_s.

The efficiency of DNA integrity repair processes after radiation exposure may depend on hereditary variations of repair genes caused by single nucleotide polymorphisms. Disturbances or even failure of repair processes trigger a chain of reactions leading to genome instability and oncogenic transformation of the cell.

Purpose: To investigate the association of single nucleotide polymorphism in genes of nucleotide excision repair (ERCC2 rs13181, XPC rs2228001), AP site repair (APEX rs1130409), homologous recombination (XRCC3 rs861539), single-strand DNA break repair (XRCC1 rs25487), and double-strand DNA break repair (PARP rs1136410, XRCC4 rs2075685) with the risk of malignant neoplasm development of various localisations in chronically exposed persons.

Material and methods: The study was conducted in 861 individuals who were exposed to chronic low dose rate radiation. 274 people of which had malignant neoplasms (MN) of various localisations and 587 people made up the comparison group (exposed persons without MN). The mean accumulated dose to red bone marrow (RBM) in the group of people with MN was 561.65±25.31 mGy, while in the comparison group it was 543.14±36.06 mGy. Genotyping of polymorphic loci rs13181, rs2228001, rs1130409, rs861539, rs25487, rs1136410, and rs2075685 was performed by real-time PCR. The association of polymorphic loci with the risk of MN development was determined by the odds ratio (OR) and 95 % confidence interval (95 % CI). A multifactor dimensionality reduction method was used to assess intergenic interactions.

Results: Single-stranded DNA break repair gene rs25487 (XRCC1) polymorphism in accordance with the dominant model is associated with an increased risk of MN development in the combined group of the examined persons (OR=1.79 (1.12‒2.87), p=0.01). The polymorphism of the gene involved in homologous recombination rs861539 (XRCC3) in accordance with the recessive model is associated with a reduced risk of MN development both in the combined group of exposed persons (OR = 0.25 (0.15‒0.41; p<0.00001), and separately in the group of the Slavs (OR = 0.28 (0.13‒0.60); p<0.0001) and in the group of the Turks (OR = 0.22 (0.11‒0.44; p<0.0001). The model of interfactorial interactions allowed us to establish a protective effect with respect to the risk of MN development in carriers of polymorphic loci rs861539 of XRCC3 gene and rs1130409 of APEX1 gene (p<0.001).

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PDF (RUS) Full-text article (in Russian)

Conflict of interest. The authors declare no conflict of interest.

Financing. This study was carried out within the framework of the state assignment of the FMBA of Russia: “Evaluation of the medical and biological effects of chronic radiation exposure and mechanisms of their development to improve the methods for early detection of exposure effects” (Immunohematopoiesis-24)”.

Contribution. All authors confirm that their authorship meets the international ICMJE criteria. Kodintseva Е. А. ‒ conceived and designed the study, prepared the first draft of the article, read and approved the final version before publication. Akleуev А. А. ‒ conceived and designed the study, scientific editing, read and approved the final version before publication.

Article received: 20.05.2024. Accepted for publication: 25.06.2024.

Despite thousands of studies and about 150 meta-analyses for the effects of second hand smoking (SHS) on the mortality risks from individual diseases for mortality from all causes there are two orders of magnitude less work and only one meta-analysis Lv X. et al, 2015.

Based on a selected sample of works (search in MEDLINE, PubMed, Cochrane Library, Elibrary, Google and reference lists of sources) on all cause mortality due to SHS for exposure to adults (18 publications; 1984–2014), a systematic review, combined analysis and meta-analysis of the appropriate risk (Relative Risk, RR; odds ratio, OR and Hazard Ratio, HR), the value of which was 1.14 (95 % confidence intervals: 1.10, 1.19). This value according to the gradation of risks (R. Monson, 1980, 1990) is ‘indeterminable’, but when compared with the risks of mortality from occupational factors, it is very significant.

By searching through these systems, as well as in the supported database, a selection of meta- and pooled analyzes on the Standardized Mortality Ratio (SMR) for all causes with reference to various kinds of activity, including harmful/dangerous trades was collected. For a number of professions, their own meta-analyses have previously been performed.

Of the 20 employment types considered, only five (25 %) were comparable in risk to or slightly higher than the SHS total mortality index (in increasing magnitude of risk: coal miners, dust exposure, asbestos exposure, beta-naphthylamine, and asbestos cement production). For 70 % of rhazardous/harmful occupations reviewed, the risk of death was statistically significantly lower than from SHS (pilots, nuclear workers, physicians, wood processing, cotton textile production, acrylonitrile exposure, military, rubber production, chemical industry, organic solvent production, drivers, working with plant protection chemicals, exposure to Hg, Cd, Pb, Cu and uranium miners). Only for a few professions was the ‘Healthy Worker Effect’ possible: pilots, the nuclear workers, the military and, less expectedly, drivers and physicians.

Thus, the risk of death from SHS is higher than the risk for most hazardous/harmful occupations, including the nuclear industry and uranium mines. This indicates, on the one hand, the special danger of SHS and the need to strengthen measures to limit smoking, including at enterprises subordinate to the FMBA of Russia. On the other hand, the fact that for most hazardous occupations the mortality risks are now lower or comparable to the risks from SHS may reflect the high level of occupational safety and health and progress in its organization.

The importance and public-social significance of this study, which complements and corrects the earlier meta-analysis of the SHS effect (Lv X. et al, 2015), is that the risk index of overall mortality, all causes, was used, that is, the final index, in contrast from the risks of mortality from individual pathologies or situations.

Purpose: Since currently there are no selective drugs for paramagnetic contrast enhancement (PMC) in MRI in the oncology clinic as such, we tried to obtain a selective oncotropic paramagnetic contrast agent (PMCA) – Mn(II) manganese compound with glucaric acid (used in combination with ^99mTc for breast cancer (breast cancer), and to evaluate on the basis of animal studies the possibility of using Mn(II)-glucarate (Glucaromang) as an oncotropic PMCA in breast cancer.

Material and methods: The synthesis of glucaric acid was carried out by a modified method by oxidation of D-glucose with strong nitric acid. A solution of D-glucaric acid was used to produce manganese glucarate by combining with manganese oxide or carbonate with an excess of glucarate in solution, since one manganese atom forms a complex with two glucaric acid molecules. The injection solution of the obtained Mn(II)-glucarate was adjusted to pH = 6.4–7.2 and sterilized by microfiltration through Millipore filters with a pore size of 0.22 μm. The toxicity indices LD₁₀, LD₅₀, LD₉₀ (ml/kg) were determined in laboratory white mice. An in vivo MRI study of the tumor accumulation of Mn(II)-glucarate was performed in veterinary patients – cats (n = 9) with diagnosed breast cancer, who underwent body MRI to clarify the diagnosis and assess the extent of breast cancer, and 4 cats with malignant tumors of the neck and submandibular region (salivary glands). Scanning was performed using Toshiba Titan Vantage (Canon Medical) and Magnetom Open (Siemens Medical), with subsequent processing by Radiant (https://www.radiantviewer.com ).

Results: In the injection solution of Mn(II)-glucarate 0.5 M, free manganese was absent in detectable amounts, the excess of glucaric acid (has an antineoproliferative effect) was up to 2–2.5 %. Osmolality 1550±39 mOsmol/(kg H₂O), viscosity 2.85±0.15 MPa·s, at 37 °C. When stored for 6 months, there was no release of manganese from the complex. The thermodynamic stability constant was 17.6–17.9. For the injection drug «Mn(II)-glucarate, 0.5M, aqueous solution”, the mortality rates for single administration in mice were, respectively: LD₁₀ = 6.8 ± 5.0 ml/kg, LD₅₀=15.1 ± 4.7 ml/kg, LD₉₀=37.5 ± 23.8 ml/kg . When administered Mn(II)-glucarate as laboratory mice and cats with breast cancer did not show significant changes in the blood pattern and any side effects. The drug accumulated intensively in the primary tumor and metastases. The index of enhancement for T₁-WI was 1.78 ± 0.082 (p < 0.02) for the primary tumor and 1.49 ± 0.09 (p < 0.05) for lymphogenic metastases.

Conclusion: Mn-glucarate is an original paramagnetic contrast agent, highly stable, non-toxic, providing in vivo intensive MRI imaging of tumor structures, in particular in breast cancer.

Purpose: Analysis of radical radiotherapy efficacy (combination of remote irradiation with simultaneous dose escalation to the tumor focus and subsequent intracavitary component) in a patient diagnosed with stage III endometrial cancer when surgical treatment is impossible. Assessment of the dynamics of the underlying disease and adverse events. The purpose of the study is to analyze the effectiveness of radical radiation therapy in a patient diagnosed with stage III endometrial cancer when surgical treatment is impossible.

Material and methods: We present a clinical case of a patient with inoperable stage III endometrial cancer (histologic variant-highly differentiated adenocarcinoma) with metastasis to the lower third of the vagina. The first stage was a course of remote radiotherapy on a linear gas pedal VarianTrueBeamSTx on the uterus, vagina, paravaginal tissues, pelvic lymph nodes up to a total dose of 50 Gy and simultaneous dose intensification on the area of tumor focus in the lower third of the vagina up to a total dose of 62.5 Gy. The method of dose administration was rotational radiotherapy with intensity modulation of photon radiation (Volume-modulated arc therapy ‒ VMAT).

The second stage was a course of intracavitary (contact, brachytherapy) radiotherapy on MultiSource HDR device with ⁶⁰Co ionizing radiation source. A gynecological two-channel applicator was used during treatment. The plan of each treatment session was developed based on CT images on the SagiPlan planning station. Intracavitary radiation therapy mode – single dose of 6 Gy, 4 fractions were performed.

The effect of radiation therapy was assessed by MRI of pelvic organs with intravenous contrasting immediately after treatment and further at intervals of every 3 months.We present a clinical case of a 71 year old female patient diagnosed with stage III endometrial cancer (well-differentiated adenocarcinoma), with adenocarcinoma metastasis to the lower 1/3 of the vagina. Planning of radiotherapy and radiation therapy in a patient with inoperable endometrial cancer with simultaneous escalation of the dose of ionizing radiation to the area of ​​metastasis in the vagina during the remote component and subsequent intracavitary boost to the uterine area. Study of the results of radiation therapy.

Results: After treatment, MRI data showed complete regression of the tumor nidus in the vagina and reduction of the nidus in the uterine body (more 50 %). Long-term control of the tumor process in the patient, confirmed by clinical and radiological studies (MRI of the pelvic organs), was also achieved.The capabilities of modern radiation therapy make it possible to carry out radical treatment of patients with endometrial cancer in clinical cases when it is necessary to increase the dose of ionizing radiation to a separate tumor focus, without exceeding the tolerable levels of radiation exposure to risk organs. This approach makes it possible to achieve remission in real clinical practice.

Conclusion: The capabilities of modern radiation therapy allow radical treatment of patients with inoperable endometrial cancer in clinical cases when it is necessary to increase the dose of ionizing radiation to a separate tumor focus without exceeding tolerance levels of radiation loads on risk organs. This approach makes it possible to achieve remission in real clinical practice.

Purpose: Testing samples of cotton materials for their use as objects of recovery of accumulated dose by EPR dosimetry.

Material and methods: Samples of cotton fabric and fabrics of mixed composition – lab coats, casual clothing items – shirts and jeans, as well as protective masks and respirators were irradiated using a linear electron accelerator model UELR-10-10C2 in the dose range from several Gy to 16 kGy. EPR spectra were recorded using the Bruker Elexsys-II E580 X-band EPR spectrometer with a SuperHighQ cylindrical resonator.

Results: It was found that ionizing radiation induces free radicals in materials with triplet EPR signal, the most intense line of which has g = 2.019 and a linewidth 6 G. There was no or negligible native signal in uncolored fabrics. The radiation-induced EPR signal decayed exponentially with average half-life time of 62 hours.

Conclusion: Clothing materials based on cotton fabrics, as well as materials of protective medical masks, have shown themselves suitable for use as an object of retrospective EPR dosimetry.