The Belarusian protests are a series of ongoing political demonstrations and protests Demonstrations supporting Lukashenko took place in Mogilev, Gomel, and Prime Minister Roman Golovchenko stated that, "to date, all enterprises in the Students and professors of leading Belarusian universities carried out.
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Gomel State Medical University
The timestamp is only as accurate as the clock in the camera, and it may be completely wrong. From Wikimedia Commons, the free media repository. File information. Structured data. Captions English Add a one-line explanation of what this file represents. Sharapova was born in in Nyagan, Siberia, after her family fled Gomel in the wake of the Chernobyl accident.
In Sharapova left Russia to study tennis in the United States. In she won the U. Open and, in , the Australian Open. You cannot overwrite this file. The following other wikis use this file: Usage on be. In addition, radiation doses to the thyroid for the following minor exposure pathways were calculated: a intake of short-lived I, I and Te via inhalation and ingestion; b external irradiation from radionuclides deposited on the ground and c ingestion intake of Cs and Cs.
This paper describes the methodology, input data and results of reconstruction of individual thyroid doses for all cohort members in the Belarusian-American study. It is recognized that the results of the direct thyroid measurements, the responses given by the respondents during the personal interviews, as well as the parameters of the ecological and biokinetic models include various degrees of uncertainty. The evaluation of uncertainties associated with the thyroid doses reconstructed for the cohort members of the Belarusian-American study is under way.
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The Belarusian cohort initially included 11, individuals who attended screening examinations. The remaining 11, cohort members are considered here. The distribution of these cohort members according to the raion of residence at the time of the accident is shown in Fig. Only Gomel and Mogilev 4 Oblasts as well as the city of Minsk are shown. An additional individuals resided at the time of the accident in other parts of the country or outside Belarus.
Almost half of the cohort 5, of 11, resided at the time of the accident in Bragin, Khoiniki and Narovla raions, which are the closest in proximity to the Chernobyl nuclear power plant. Distribution of the cohort members by raion of residence at the time of the Chernobyl accident. Raions where and more individuals resided are highlighted in gray.
The study was reviewed and approved by the institutional review boards of the participating organizations in Belarus and the U. The following information was used to calculate the absorbed doses to the thyroids of the individuals included in the cohort:. Results of interviews for all cohort members or their relatives for children who were less than 10 years old at the time of the accident. Ecological and biokinetic models used to evaluate the variation with time of the I activity in the thyroid.
Values of thyroid masses of the Belarusian children close to the time of the Chernobyl accident. The scheme of thyroid dose calculation for the Belarusian cohort members is shown in Fig. The thyroid doses were estimated using input data specific to each cohort member direct thyroid measurement and personal interview and ecological data I ground deposition in the settlements. The manner in which the information used in the dose reconstruction was obtained and processed is discussed in the following sections. The direct thyroid measurements were conducted in Belarus during April-June on about 40, individuals aged 18 years or younger at the time of the Chernobyl accident 6.
The direct thyroid measurements were performed using different types of radiation monitoring devices, mainly the DP-5 dose-rate meter, the SRP survey meter and the DRG dosimeter Table 1. The temporal distribution of the direct thyroid measurements, which were all conducted between 30 April and 28 June , are shown in Fig.
The measurements started earlier among residents of the city of Minsk median date of 12 May and Gomel Oblast median date of 16 May than among those of Mogilev Oblast median date of 27 May , which is relatively far from the Chernobyl nuclear power plant. The median date of the direct thyroid measurements for the entire cohort is 16 May Temporal distribution of the direct thyroid measurements performed on the cohort members. The direct thyroid measurements made in Belarus were not performed by professionals, but by people with no experience in radiation measurements.
In general, the persons who conducted measurements were given instructions on how to use the measuring devices and to record the results of the measurements; however, there was no quality control of their measuring practices or of the way in which they recorded the measured values.
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In many instances, the background exposure rate in the presence or absence of the subject in the room where the measurements were performed, was not measured or recorded. Therefore, to estimate the device response due only to the I content in the thyroid of the subject, it was necessary to investigate whether the measurement results took into account the following contributions to the overall signal registered by the device:. The external surface contamination of the body and the clothes as well as the internal contamination due to Cs, Cs and Cs incorporated in the body.
The manner in which the I activities in the thyroids of the subjects were derived from the results of the direct thyroid measurements is described below. When the background radiation in the room was measured during the direct thyroid measurements, the net exposure rate was calculated as:. Often, the background radiation in the room where the measurements were performed was not measured during the measurement campaign in Belarus.
In those instances, the method used to estimate P bg t m depended upon the availability of outdoor exposure rates. If outdoor exposure rate in the settlement of interest: a was measured at the day of thyroid measurement, t m ; or b was estimated by means of interpolation of measurements performed in that settlement before and after the day t m , the background radiation in the room was calculated as:.
Based on the results of 3, measurements performed outdoors and indoors in — in Belarus, the indoor exposure rate due to natural background radiation was taken to be equal to that measured outdoors 8. The shielding factor was estimated from the measurements of outdoor and indoor exposure rates performed between 3 May and 16 May in the same settlement during the same day:. The value of the shielding factor varies from 0. When outdoor exposure rate was not measured in the settlement of interest, the outdoor exposure rate was calculated as:.
In many instances, the handwritten records did not indicate if the background radiation in the room where the measurements were performed was subtracted from the results of measurement of exposure rate near the thyroid. To evaluate if it was subtracted, the exposure rate measured against the neck, P m t m , was compared with the background radiation in the room, P bg t m , either measured or calculated using Eq. Sometimes, the exposure rate measured by the DP-5 device was recorded in the notebook as less than 0.
The values of LLE depend on the type of device and on the magnitude of the exposure rate due to background radiation in the room. LLE values were assigned to 1, cohort members, including of them who were measured with the DP-5 device and persons measured with the SRP device. Direct thyroid measurements were made in Belarus on subjects who were internally contaminated with radionuclides other than I and whose skin, hair and clothes could also be contaminated.
Therefore, when a Belarusian cohort member was measured shortly after fallout, external contamination of his or her body with radionuclides of Chernobyl origin contributed substantially to the response of the radiation device. In June internal contamination with radiocesium isotopes homogeneously distributed in the body was more important than external contamination. A measurement of background exposure rate performed near the thigh of the subject can be used to account for the contribution of the internal contamination with the radiocesiums and for some of the external contamination However, in Belarus, as a rule, the background against another part of the body of the subject was not measured.
To evaluate the contribution to the measured signal from external and internal contamination of the body it was necessary to estimate a the external contamination of every cohort member as well as the activity of cesium isotopes Cs, Cs and Cs in their bodies at the time of their direct thyroid measurements, and b the response of the radiation devices for the radiocesiums in the body as well as for all radionuclides that contributed to the external contamination of the body surfaces.
The problem was exacerbated by the facts that a the cohort members were children from 0 to 18 years old, so that a range of body sizes had to be considered; b the measurements were made using different types of radiation devices; and c many cohort members changed places of residence several times between the date of the accident and the date of the direct thyroid measurement.
Models were developed to estimate the levels of external and internal contamination for all cohort members at the time of their direct thyroid measurement. The model of external contamination was used to estimate the activities of 95 Zr, 95 Nb, 99 Mo, Ru, Ru, Te, I, I, I, Cs, Cs, Cs, Ba, La, Ce, Ce, Np on all surfaces of the body, which was divided into 19 regions, including face, hair, neck, arms, hands, trunk and legs.
The activities were calculated for each day between 26 April and 30 June for individuals of different ages: newborns, children aged 1, 5, 10 and 15 years, and adults. Twelve different scenarios of residence were considered in the study, including permanent residence at the settlement and relocation from the settlement of residence on 26, 27, 28, 29, 30 April, or 2, 5, 10, 15, 20 or 25 May The model accounts for indoor and outdoor air and ground surface contamination, natural and man-made resuspension of radioactive particles and washing habits of the population.
Calculations were also made assuming that the cohort members at the time of their direct thyroid measurements wore contaminated clothes that either had been washed every week or had not been washed since the time of the accident 26 April For the purposes of the dose assessment, it was assumed, because the majority of measurements were done two weeks or later after the accident Fig.
The model of internal contamination was used to estimate the activities of Cs, Cs and Cs in the bodies of the cohort members at the time of their direct thyroid measurements. The assessment of the contribution to the measured signal from radionuclides located in the 19 regions representing the surface of body, as well as from radiocesiums into the body, was made by means of Monte Carlo modeling of the human body at various ages and the use of mathematical models of radiation detectors.
The contribution of the external and internal contamination of the subject to the exposure rate measured near the thyroid was taken into account by means of a correction factor as:. To assign a correction factor to a given study subject, his or her personal information from the questionnaire was taken into account. Thirty-five scenarios of relocation between 16 areas in Belarus were considered in the assignment of the correction factors to the study subjects.
Due to the complexity of the task, the administration of stable iodine for the study subject under consideration was not taken into account. Figure 4 shows, as an example, the variation with time of the relative contributions to the exposure rate measured near the thyroid of the external contamination of the subject, of his or her internal contamination and of the I activity in his or her thyroid. The example that is given is for a measurement made by means of a SRP device on a 5-year-old child who resided in Khoiniki raion, where the majority of the study subjects resided at the time of the accident Fig.
For measurements that took place at the beginning of June and later, I in the thyroid contributed less than half to the device response, the remainder of the signal being caused mainly by the radiocesium isotopes incorporated in the body.
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Similar contributions of cesium activity in the body to the results of the direct thyroid measurements were shown by Ulanovsky et al. Variation with time of the contribution of the external thin line and internal broken line contamination of the subject, and of the I activity in the thyroid thick line to the exposure rate measured near the thyroid by the SRP device for a 5-year-old child who resided in Khoiniki raion of Gomel Oblast. The corrected net exposure rate, P net,corr t m , is only due to the I activity in the thyroid of the subject at the time of the direct thyroid measurement.
The relationship between P net,corr t m and the I activity in thyroid is as follows:. As direct thyroid measurements were performed using devices that were not designed to measure radioactivity in humans, calibration factors for I needed to be estimated for these devices. A Monte Carlo method of numerical simulation of radiation transport was used to calculate the device- and age-specific calibration factors Table 3 that were used in this study to derive the I activities in the thyroids from the results of the direct thyroid measurements.