CC BY
5IRSTI 76.29.62 UDC 614.876:577.35
CALCULATION OF THE ACCUMULATED IRRADIATION DOSE OF ANIMAL ORGANS WITH URANIUM ORAL INTAKE IN THE EXPERIMENT
D. Ibrayeva1, E. Saifullina1, M. Aumalikova1, P. Kazymbet1, M. Bakhtin1, M. Hoshi2
1NcJSC "Astana Medical University", Kazakhstan 010000, Nur-Sultan city, Beibitshilik st.,
49А
2Peace Center Professor Emeritus, Hiroshima University, Japan, 731-0153, Hiroshima
1D. Ibrayeva - Researcher, Institute of Radiobiology and Radiation Protection, NcJSC "Astana Medical University", Nur-Sultan, Kazakhstan. E-mail: danaraibrayeva@gmail.com
2E. Saifullina - Senior Lecturer, Department of Pathological Physiology named after V.G. Korpacheva, NcJSC"Astana Medical University", Nur-Sultan, Kazakhstan. E-mail: elena_krupina@mail.ru
1M. Aumalikova - Head of Laboratory, Institute of Radiobiology and Radiation Protection, NJSC "Astana Medical University", Nur-Sultan, Kazakhstan. E-mail: abulmalik.md@gmail.com
1P. Kazymbet - Director, Institute of Radiobiology and Radiation Protection, NJSC "Astana Medical University", Nur-Sultan, Kazakhstan. E-mail: kazimbet.p@mail.ru
1M. Bakhtin - Deputy Director, Institute of Radiobiology and Radiation Protection, NJSC "Astana Medical University", Nur-Sultan, Kazakhstan. E-mail: bakhtin.m@amu.kz
2M. Hoshi - Peace Center Professor Emeritus, Hiroshima University, Hiroshima, Japan. Email: mhoshi@hiroshimau.ac.jp
Objective: the aim of the study is to determine the content of uranium in animal organs and calculate the dose ofinternal irradiation of organs due to its oral intake.
Methods. The experimental study was carried out on laboratory outbred rats. Within one week, uranium ore dust (UOD) was added to their food at a dose of 50 MPC. After the experiment, the concentration of uranium in the internal organs of the animals was determined by mass spectrometry.
Results. It was found that the concentration of uranium in experimental groups of animals is an order of magnitude higher than the level of uranium concentration in all organs of rats in comparison with the control. It hasbeen shown that a low content of uranium is observed in the brain, testes and ovaries. The maximum concentration of uranium is found in the kidneys, intestines and liver. The calculation of the dose of internal irradiation of organs due to the chronic intake of uranium, where this value varies from 0.01 fGy to 5.67 fGy.
Conclusion. In the early stages of oral intake of UOD, the highest concentration of uranium was observed in the organs of rats at a dose of 50 MPC.
1. Measurements of uranium concentration in organs on a mass spectrometer showed the maximum concentration values in organs such as kidneys, intestines and liver.
2. The critical organ (in terms of the absorbed dose) is the kidneys, which subsequently indicates the likelihood of biological effects.
Key words: uranium, radioactivity, low doses, internal exposure, dosimetry, mass-spectrometry, animal organs, biokinetics.
РАСЧЕТ НАКОПЛЕННОЙ ДОЗЫ ОБЛУЧЕНИЯ ОРГАНОВ ЖИВОТНЫХ ПРИ ПЕРОРАЛЬНОМ ПОСТУПЛЕНИИ УРАНА В ЭКСПЕРИМЕНТЕ
Ибраева Д.С.1, Сайфуллина Е.А.1, Аумаликова М.Н.1, Казымбет П.К.1, Бахтин М.М.1, Хоши М.2
хНАО «Медицинский университет Астана», Казахстан 010000, Нур-Султан, ул. Бейбитшилик 49А
2Хиросимский университет, Япония, 731-0153, Хиросима
1Ибраева Д.С. - Научный сотрудник, Институт радиобиологии и радиационной защиты, НАО «Медицинский университет Астана», Нур-Султан, Казахстан. E-mail: danaraibrayeva@gmail.com 1 Сайфуллина Е.А. - Старший преподаватель, Кафедра патологической физиологии имени В.Г. Корпачева, НАО «Медицинский университет Астана», Нур-Султан, Казахстан. E-mail: elena_krupina@mail.ru 1Аумаликова М.Н. - Заведующий лабораторией, Институт радиобиологии и радиационной защиты, НАО «Медицинский университет Астана», Нур-Султан, Казахстан. E-mail: abulmalik.md@gmail.com
казымбет П.К. - Директор, Институт радиобиологии и радиационной защиты, НАО «Медицинскийуниверситет Астана», Нур-Султан, Казахстан. E-mail: kazimbet.p@mail.ru
1 Бахтин М.М. - Заместитель директора, Институт радиобиологии и радиационной защиты, НАО «Медицинский университет Астана», Нур-Султан, Казахстан. E-mail: bakhtin.m@amu.kz
2Хоши М. - Почетный профессор Центра мира, Хиросимский университет, Хиросима, Япония. Email:mhoshi@hiroshimau.ac.jp
Цель: определить содержание урана в органах животных и рассчитать дозу внутреннего облучения органов за счет его перорального поступления.
Методы. экспериментальное исследование проводилось на лабораторных беспородных крыс. В течение одной недели в их пищу были добавлены пыль урановой руды (ПУР) в дозе 50 ПДК. После эксперимента методом масс-спектрометрии были определены концентрации урана во внутренних органах животных.
Результаты. Установлено, что концентрация урана у экспериментальных групп животных на порядок превышает уровень концентрации урана во всех органах крыс по сравнению с контролем. Показано, что низкое содержание урана отмечается в головном мозге, семенниках и яичниках. В почках, кишечнике и печени установлена максимальная концентрация урана. Проведен расчет дозы внутреннего облучения органов за счет хронического поступления урана, где данное значение варьирует от 0.01 фГр до 5.67 фГр.
Выводы. В ранние сроки при перорельном поступлении ПУР наблюдалась наиболее высокая концентрация урана в органах крыс, получавших ПУР в дозе 50 ПДК.
1. Измерения концентрации урана в органах на масс-спектрометре показали максимальные значения концентрации в таких органах как почки, кишечник и печень.
2. Критическим органом (по величине поглощенной дозы) являются почки, что свидетельствует в последующем о вероятности биологического воздействия.
Ключевые слова: уран, радиоактивность, малые дозы, внутреннее облучение, дозиметрия, масс-спектрометрия, органы животных, биокинетика.
ТЭЖ1РИБЕ КЕЗ1НДЕГ1 УРАННЬЩ АУА ТАМШЫСЫ АРЦЫЛЫ ТYСУIНДЕГI ЖАНУАРЛАР АГЗАЛАРЫНЫЦ ЖИНАЦТАЛГАН СЭУЛЕЛЕНУ ДОЗАСЫН ЕСЕПТЕУ
Ибраева Д.С.1, Сайфуллина Е.А.1, Аумаликова М.Н.1, Казымбет П.К.1, Бахтин М.М.1, Хоши М.2
1«Астана медициналык университет» КеАК, Казакстан 010000, Нур-Султан к., Бейб1тшшк к-ri, 49А
2Хиросима университет!, 732-0153, Хиросима к;., Жапония
1 Ибраева Д.С. - Радиобиология жэне радиациялык коргау институтыныц гылыми кызметкерi, «Астанамедициналы; университетi» КеАК, Н^р-С^лтан к., Казакстан. E-mail: danaraibrayeva@gmail.com
1 Сайфуллина Е.А. - В. Г. Корпачев атындагы патологиялы; физиология кафедрасынын ага ок^ггушысы,
«Астана медициналык университетi» КеАК, Бейбiтшiлiк, 49/А, Н^р-С^лтан к., Казакстан. E-mail: elena_krupina@mail. ru
1Аумаликова М.Н. - Радиобиология жэне радиациялык коргау институтынын лаборатория менгерушiсi,
«Астана медициналык университетi» КеАК, Н^р-С^лтан к., Казакстан. E-mail: abulmalik.md@gmail.com
1 Казымбет П.К. - Радиобиология жэне радиациялык коргау институтынын директоры, «Астана медициналык университетi» КеАК, Н^р-С^лтан к., Казакстан. E-mail: kazimbet.p@mail.ru
1 Бахтин М.М. - Радиобиология жэне радиациялык коргау институтынын директордын орынбасары,
«Астана медициналык университет» КеАК, Н^р-С^лтан к., Казакстан. E-mail: bakhtin.m@amu.kz 2Хоши М. - Бейбпшшк орталыгынын к¥рметп профессоры, Хиросима университетi, Хиросима к., Жапония. Email: mhoshi@hiroshimau.ac.jp
Максаты: жануарлар агзасындагы ураннын к¥рамын аныктау жэне онын ауызша тYсуiне байланысты органдардын шш сэулелену дозасын есептеу.
Эдiстерi. Зертханалык асыл т^кымды егеук¥йрыктарга эксперименттiк зерттеу жYргiзiлдi. Бiр апта iшiнде олардын тамагына 50 ШРК дозада уран кеш шаны (УКШ) косылды. Масс-спектрометрия эдгамен жYргiзiлген эксперименттен кейiн жануарлардын iшкi мYшелерiндегi ураннын концентрациясы аныкталды. Нэтижесь Жануарлардын эксперименттiк топтарындагы ураннын концентрациясы бакылаумен
салыстырганда егеук^йрьщтардьщ барлык; органдарындагы уран концентрациясыньщ денгейiнен бiршама жогары екендiгi аныщталды. Ураннын тэмен мэлшерi ми, ^рыщ жэне аналык; бездерде бащалады. БYЙректе, iшекте жэне бауырда ураннын ец жогары концентрациясы белгiленген. Уранныц созылмалы тYсуi есебiнен агзалардыц iшкi сэулелену дозасын есептеу жYргiзiлдi, онда осы мэн 0.01 фГр-дан 5.67 фГр-га дейiн ауыщиды.
^орытынды. Ерте мерзiмде уран кенi шацыныц ауыз аркылы тYсуi кезiнде 50 ШРК дозада УКШ алган егеук^йрыщтар органдарында уранныц ец жогары концентрациясы бащалды.
1. Масс-спектрометрдеп органдардагы уран концентрациясын элшеу бYЙрек, iшек жэне бауыр сия^ты органдардагы концентрацияныц максималды мэндерiн кэрсетп.
2. БYЙректер сыни орган (сщршген дозаныц шамасы бойынша) болып табылады, б^л кейiннен биологиялык; эсер ету ы^тималдыгын айга^тайды.
ТYЙiн сездер: уран, радиоактивтшк, тэмен дозалар, iшкi сэулелену, дозимтрия, масс-спектрометрия, жануарлар органдары, биокинетика.
Corresponding author: Ibrayeva Danara, Researcher, Institute of Radiobiology and Radiation Protection, NJSC"Astana Medical University", Nur-Sultan, Kazakhstan.
Postal code: 010000 Address: Beybitshilik 49/APhone: 8 (7172) 539448
E-mail: danaraibrayeva@gmail.com
Recieved: 14.05.2021
Accepted: 20.05.2021
Bibliographic reference: Calculation of the accumulated irradiation dose of animal organs with uranium oral intake in the experiment/D. Ibrayeva, E. Saifullina, M. Aumalikovaet al. // Астана мединалык; журналы. -2021. - № 2 (108). - С. 248-256.
Introduction
Taking into account the goals of the Strategic Plan of the Ministry of Ecology, Geology and Natural Resources of the Republic of Kazakhstan for 2017-2021, aimed at improving the quality of the environment (strategic direction 1), it is necessary to raise the environmental standards of Kazakhstan to the level of developed countries, including changing the process of assessing the impact of industrial radiation risk enterprises on the environment. The republic lacks clearly formulated methodological and regulatory documents on risk assessment for ecosystems in case of chronic radioactive contamination, which in turn justifies the need for comprehensive research for the development of an ecocentric concept of radiation protection.
When standardizing environmental radionuclide contamination, the assessment of environmental risk is relevant [1,2]. Research in the field of assessing chemical environmental risk was first carried out in the 1980s in the United States [3].
In 2 000, in connection with the growing need to study the chronic effects of ionizing radiation on the biota, the ICRP initiated the development of a research program aimed at creating unified methodological approaches to assessing the impact of the radiation factor on the environment. The obtained research results formed the basis of Publication 91 of the ICRP "Framework program for the development of a system for assessing radiation effects in representatives of flora and fauna, with the exception of humans" [4], where a strategy for the protection of representatives of biota is proposed. The development of this program was also received in Publication 108 of the ICRP "Environmental protection: the concept and use of reference animals and plants" [5,6], where the concept is proposed - reference animals and plants, "conditional (reference) animals and plants" (hereinafter - C (R) AP). However, in specific radioecological conditions with the nature of contamination with different (alpha, beta, gamma emitting) radionuclides, developing in different regions, the use of a set of C (R) AP may not always adequately reflect the peculiarities of the functioning of ecosystems. In most studies, environmental risk is assessed for critical components of ecosystems, while methods for assessing radioecological risk at the ecosystem level are in their infancy.
At present, Kazakhstan has accumulated more than 170 million tons of radioactive waste in the form of tailings from concentration plants, heap leaching piles, tailing dumps of hydrometallurgical plants and waste of poor commodity, unprocessed ore, requiring constant
radiation monitoring of their condition and rehabilitation of the territory [7,8]. In the northern region of the Republic, according to the data of the commission for the study of the state of the radiation situation at the ore administrations of the former Tselinny Mining and Chemical Combine,about 61 million tons of radioactive waste with a total total activity of 168.4 thousand Curie have accumulated [9]. Many of them, associated with the extraction of raw materials enriched with radionuclides from the bowels, lead to an increase in the radiation background and the formation of radioactive anomalies and remain abandoned. The main properties of radioactive anomalies of this type are: practically infinite time of their existence due to long-lived radionuclides; the presence ofa greater number of radionuclides-members of natural decay series; constant release of radon into the environment; the presence of other micro- and macrocomponents that pollute the environment and affect the migration of radionuclides [10].
The assessment of the radiation risk to biological objects is carried out taking into account the radiation safety criteria, which leads to the receipt of erroneous data due to the lack of a single criterion [11,12]. At the same time, a unified criterion for the safety of biological objects under the influence of a chronic radiation factor has not yet been developed and adopted. In this regard, the study of the degree of uranium distribution in the organs of laboratory animals with chronic oral intake of uranium in the experiment and the subsequent assessment of the dose load is an urgent task.
Materials and methods
An experimental study was carried out on laboratory outbred rats (adult males), where uranium ore dust (UOD) in doses of 50 MPC was added to their food for one week. The composition of uranium ore dust is presented in table 1.
Table 1 - Chemical composition of uranium ore dust from SMCC, %.
U O3 Mo O Zn O2 Fe2O3 Si O2 Al2 O A s2O Sulf ur
0,3 98 0,12 3 0,0 27 6,1 40, 6 4,6 1 0 ,008 1,5
M gO CO P2 O5 Na2O +KO Fe O2 M nO C aO Carb on / mois ture
3,5 10,0 2,0 10,0 4,0 0,2 2 7 ,0 2/7,9
From the above data, it can be seen that the bulk of UOD is carbon monoxide( carbonate), a mixture of sodium and potassium oxides, calcium oxide, ferrous and trivalent iron oxide, aluminum,magnesium, phosphorus oxides, uranium oxide, molybdenum oxide, zinc, and arsenic. Thus, the composition of the dust we used is very complex. Radiospectrometric studies of the UOD used in the experiment showed that the total activity of its a-emitting radionuclides was 98.8 Bq/g, and of the P-emitting ones - 30.4 Bq/g.
UOD was added to baby food Nestle, a dairy - free porridge, and mixed to a homogeneous mass. At the same time, UOD was absorbed into the animals ' bodies under conditions of natural food consumption as the only source of nutrition.
To control the portion eaten, the animals of the experimental and control groups were seatedin individual cages, in the corner of which fixed containers with food and water were placed. After feeding, the food eaten and residues were recorded, the volumes of which were insignificant (less than 1% of the total volume of the mixture).
A total of 6 animals were used in the experiment. Determination of uranium concentration was carried out in samples of organs, such as kidneys, liver, intestines, testes and ovaries of outbred rats 24 hours after feeding with porridge with UOD. The period of feeding animals in 7 days is equal to 1 year of human life [13].
To calculate the parameters of the seed, the activity of the isotopes 238U, 235U in the UOD and the values of the activity of uranium supplied to the personnel for 1 year of production activity
were taken into account. To estimate the dose load of animals, the measured uranium concentration was converted. According to the US Department of Energy for 2011, 1 p,g / L is 0.6757 pCi / L, respectively 0.6757 pCi / L is 25 Bq / g.
On the equipment "Multiwave PRO 3000" we carried out microwave decomposition of animal organs, after which the uranium content was determined on the mass spectrometer with inductively coupled plasma "ICP-MS Agilent 7800".
Tables 2 and 3 present the technical parameters of the equipment for measuring uranium in bioassays. Table 2 - Temperature-time range of decomposition of organ samples from outbred rats.
Time, min Power, W Temperature, °C
20 500 210-220
15 1200 210-220
15 1200 70
Table 3 - Technical parameters of ICP-MS.
ICP-MS Set value
RF generator power 1500 W
Number of points per peak 6
Carrier gas 1.05 L / min
Dilution mode On
Dilution gas 0.1 L / min
Argon gas 4.3 L / min
Construction of calibration dependencies. Calibration curves were obtained using aqueous standard uranium solutions. To plot the calibration curves, calibration aqueous solutions with a mass concentration of uranium of 0; 0.5 p,g / L and 5 p,g / L. Analytical signals are measured according to optimized conditions (n = 11). The MassHunter Workstation software of the mass spectrometer automatically approximates and constructs a linear calibration characteristic in coordinates, the value of the signal intensity (imp / s) and the value of the mass concentration of uranium (p,g / L) [14-16].
To assess the internal dose of animals, the technique described in publication 108 of the International Commission on Radiological Protection (ICRP) for reference animals was used, based on modeling an organ with a simple geometric figure (in the form of an ellipsoid with dimensionsof 20 x 6 x 5 cm) with a uniform distribution of the radionuclide over volume with chronic intake [4].
To calculate the radiation doses of laboratory animals for each organ, the internal dose of theorgan was calculated, where it was calculated by integrating the dose rate for a given period of time:
T
Di = f D°(t) * dt
0
where:
Di - accumulated radiation dose of organs, Gy, for a period of time T;
D°(t) - dose rate in an organ due to uranium incorporated in the body, Gy / day.
D°(t) = 1,6 * 10-16 * q* t * E
where
t - time after the beginning of uranium intake, days;£' - energy absorbed in the i-th target organ, MeV; q - activity of uranium in the source organ, Bq.
Results and Discussion
The results of the distribution of uranium in the organs of outbred rats at a dose of 50 MPC are shown in
20 18 16 14 12 10 8 6 4 2 0
18,6
0,45
0,003 0,017 0,06 0,
^^ I ^ ■
control 50 MPC
2,3
0,04 IB 0,05 0,08 0,06 0,13
Brain
Liver Kidney Intestines Testis Ovary
Figure 1 - Concentration of uranium in the organs of outbred rats at 50 MPC, ^g /1.
The results showed that in the early periods after the arrival of uranium ore dust, the highest concentration of uranium was observed in the organs of rats receiving UOD at a dose of 50 MPC. The concentration of uranium in experimental groups of animals is an order of magnitude higher than the concentration of uranium in all organs of rats in comparison with control animals. A fairly low content of uranium isotopes is noted in organs, the brain (barrier organ), testis and ovary. However, as can be seen from Figure 1, there are organs in which the maximum concentration of uranium was found. These include the kidneys, intestines, liver, which perform the functions of storage, excretion and are a kind of biogeochemical barriers. The organs are uranium concentrating organs, in contrast to the above organs.
In the works of G.P. Galibina, Yu.V. Novikova, the distribution of uranium was studied after prolonged oral administration of uranyl nitrate to mice at a dose of 0.02-20 mg. After 9-11 months, the kidneys contained 3-10 mcg, the bones 26-77 mcg, and the liver 0-0.5 mcg. These data showthat the main amount of uranium after oral intake is deposited in the bones and kidneys [17].
In studies, the parameters of the elimination of radionuclides from the body are usually characterized by the effective half-life (Teff), that is, the time during which the initial amount of the radionuclide will be halved. For uranium entering the body, the half-life of uranium isotopes from the body of laboratory animals will depend only on the biological half-life Teff = Tbiol, since the half-life of uranium isotopes (234, 235, 238) is 2,46-105, 7.04-108, 4,5-109 years, respectively.
According to ICRP 108, the assessment of internal doses often uses internal dosimetry modelsfor reference animals. In this work, we use a method based on modeling an organ with a simple geometric figure with a uniform distribution of the radionuclide over the volume during chronic intake [4].
The results of calculating the radiation doses of laboratory animals for each organ at 50 MPC are presented in table 4.
Table - Results of calculating radiation doses of laboratory animals for each organ at 50 MPC.
Name Uranium activity in organs, Bq / g Accumulated dose,fGy
Brain 0.494±0.16 0.01
Liver 9.76±3.25 0.2
Kidney 281.58±93.86 5.67
Intestines 32.11±10.7 0.65
Testis 0.98±0.32 0.02
Ovaries 1.6±.53 0.03
As can be seen from the data presented in Table 3, the dose of internal irradiation of organs due to chronic intake of uranium at 50 MPC varies from 0.01 fGy to 5.67 fGy. The highest content of uranium isotopes in the body of animals was found in the kidneys, intestines and liver. The
obtained data on internal irradiation doses for oral administration are consistent with the literature data. It is known that the main organ of uranium compound deposition is the kidney and liver. The maximum value of the absorbed dose was noted in the kidneys, which subsequently indicates the likelihood of biological effects according to the sources [18]. Conclusions
In the early stages of oral intake of UOD, the highest concentration of uranium was observedin the organs of rats at a dose of 50 MPC.
1. Measurements of uranium concentration in organs on a mass spectrometer showed themaximum concentration values in organs such as kidneys, intestines and liver.
2. The critical organ (in terms of the absorbed dose) is the kidneys, which subsequentlyindicates the likelihood of biological effects.
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