Dose Rates for Population Near Semipalatinsk
Complex Examination of Semipalatinsk Test Site Region Population by Advanced Dosimetry Methods
Tech Area / Field
- ENV-EHS/Environmental Health and Safety/Environment
8 Project completed
Senior Project Manager
National Nuclear Center of the Republic of Kazakstan / Institute of Nuclear Physics, Kazakstan, Almaty
- National Nuclear Center of the Republic of Kazakstan / Institute of Radiation Security and Ecology, Kazakstan, Kurchatov\nScienific center of obstetrics, gynecology and perinatology, Kazakstan, Almaty
- SENES Oak Ridge Inc. / Center for Risk Analysis, USA, TN, Oak Ridge\nBaylor College of Medicine, USA, TX, Houston\nForschungszentrum Jülich GmbH, Germany, Jülich
Project summaryRecently, the 53rd session of General Assembly of the United Nations called for urgent action involving a more comprehensive study of lifetime cumulative radiation doses among residents living near the Semipalatinsk nuclear testing site (SNTS). The need for such research, which requires bio-sampling from residents is timely because the survival of the exposed population is rapidly decreasing.
The reliable definition of dose to the population in the settlements neighboring SNTS is one of the main problems in the study of consequences of nuclear weapon testing. An accurate definition of dose requires scientifically justified measurements and is needed for rehabilitation, remediation, and prediction of public health effects. Now more than ever this work is urgently needed since there is a greater likelihood of acts of terrorism using nuclear weapons or radioactive materials.
The information about dose to the population in the region of SNTS now available is very inconsistent. Radiation dose estimates range from tens of mGy to several Gy. The main cause of such large discrepancies is the imperfection of methods used for definition of an integral dose and incompleteness of the data of dosimetric monitoring required for these calculations.
Over the last several years, a new method of retrospective dosimetry based on the analysis of intensity of EPR signal in enamel of teeth was developed which now is considering by IAEA and WHO as the most reliable method for assessing inpidual dose for radiation incidents. However, in Kazakhstan EPR of tooth enamel was not applied previously because of the modern EPR-facilities absence. Taking into consideration the urgency and significance of research involving EPR and dose reconstruction, the Government of Japan granted to the Institute of Nuclear Physics (Almaty INP) EPR instrumentation and software to conduct EPR analyses. After obtaining this equipment, considerable experience in this field has been accumulated at INP, which has been confirmed through successful participation in International experiment "Intercomparison-2", conducted by IAEA in 1998-1999 for improvements in dosimetry based on EPR (just now the lab was invited to take part at the next International experiment “Intercomparison 3” which will be held in April-November 2003). The realization of work on EPR dosimetry of tooth enamel in the magnetic resonance lab of INP has been certificated by the State Standards Organization of Kazakhstan. Thus, we now meet the necessary prerequisites for conducting EPR dosimetry for sampled populations in the region of SNTS and in the other places of Kazakhstan.
While EPR provides sufficiently accurate data concerning the integral dose from external irradiation, it does not completely account of internal dose from ingestion and inhalation of radionuclides. Therefore, to obtain more complete information we propose to supplement EPR data with results from cytogenetic biodosimetry (G-banding and FISH) in peripheral blood lymphocytes of subjects who donate teeth. The combination of results from these methods will more accurately reflect the actual total dose from SNTS for neighboring population. One disadvantage of this method is the existence of chromosome aberrations not related to radiation exposure.
In this connection, the data collected from EPR and cytogenetic dosimetry will be analyzed jointly and compared with results from incorporation monitoring, and radiological monitoring results from soil, food, and water sampling in order to estimate cumulative inpidual dose. The complex application of these three essentially different methods of retrospective dosimetry will allow us to completely take into account the effects of both external and internal irradiation, and on this basis to get valid data about the doses to the representative cohort of residents living near SNTS. It warrants noting that, to date, such a comprehensive approach with simultaneously applied variety dosimetric methods (EPR, cytogenetics, whole-body counting, etc.) for the same subjects has not been pursued in the SNTS region or in Kazakhstan in general.
The original Project K-465 was considered at the 25 sessions of ISTC Governing Board (July 9, 2001) and was approved for funding by American Party as Project Development Grant (PDG) on the total 30 K$, with special comments from US.
US party specific remarks:
- Need to find US collaborator with large, dose-reconstruction experience to help guide the study.
- Need to include epidemiologist and biostatistician on the staff. Please relate this proposal to other test site reconstruction in Russia and the USA.
- Explain how the techniques used there can be applied the this study. Please address how patients will be recruited and how samples will be collected.
- Describe how background measurements will be obtained and how they will be compared with samples obtained in the study.
- Explain how environmental measurements will be used and how the dose from short-lived radionuclides (now long decayed) will be assessed.
Taking into account, that the first recommendation was “to find US collaborator with large dose-reconstruction experience to help guide the study”, we addressed to Dr. Owen Hoffman, President and Director SENES Oak Ridge Inc., which is well known for its expertise in dose reconstruction using risk as an endpoint.
Dr. Owen Hoffman has more than 25 years experience on the evaluation of the dose to humans and human risk assessment. He has presented numerous lectures and workshops on quantitative methods for assessment of uncertainty in exposure, dose and risk.
Dr. Owen Hoffman kindly gave his agreement to be a collaborator at this Project.
Including epidemiologist and biostatistician in the staff seems does not seem reasonable, as there are only few epidemiologists and biostatisticians in Almaty, they are not experienced enough, and the majority of them have been already committed to other projects and collaborations in the institutions they work. Besides this, the first collaborator on this Project, Dr. L. Peterson, is the specialist just of this field. Dr. Leif E. Peterson, Director of Epidemiology and Biostatistics Center for Chronic Disease Prevention and Control Research, Baylor College of Medicine, has significant scientific and collaborative experience in studies of radiation exposure in Ukraine, Belarus, Russian Federation, and Kazakhstan. His expertise in genetics, radiation epidemiology, and biostatistics is online at http://myprofile.cos.com/petersoL16. With Dr. Peterson assistance and under his supervision via e-mail and discussions during mutual visits the study design, day-to-day oversight of data collection, and follow-up data analysis will be performed by INP staff, thus, there must not be any doubt that this part of work will be done on a high, quite modern level.
During the PDG stage a lot of literature and special reports data have been studied, so on this base and with collaborators help all world experience on this field will be used.
The certification available in lab NMR the radiation installation with Co-60 on the analogous standard source of Almaty Branch of “National Center of Expertise and Certification” of Republic Kazakhstan was held.
The irradiation installation is indispensable for definition of a dose by EPR method with usage of a series of additional artificial irradiations. It allows to avoid an error because of personal distinctions of a radiation susceptibility of tooth enamel. The Cs-137 radiation is most convenient for these aims.
The activity on organization of the irradiating installation with Cs-137 have been made. The delineations of two versions of the irradiating installations (with activity 0,3 Cu and 4,0 Cu) were designed, the indispensable documentation preformed, which one was transferred to Sanitary- Epidemiological Committee of the Kazakhstan Republic for a coordination and statement.
Some preliminary experiments were held to study of UV irradiation influencing on a radiation EPR-signal on tooth enamel substance. The outcomes have shown, that in general the contribution of UV irradiation in a radiation signal may be rather significant, so during work on forward dens it should be taken into account, as it was noted earlier in a literature.
Besides, the considerable work on definition of influencing of an acid condition on a radiation susceptibility of tooth enamel was held, as the inhabitants of Kazakhstan widely use acidmilk food products. It was determined, that the processing by acids can lower a radiation signal on 20-40 %.
The elaboration of a technique of tooth enamel preliminary treatment permitted to lower possible errors of a dose reconstruction by EPR signal up to a minimum.
The certain activity was held for the selection of a monitoring background settlement for comparison with data of researches in locale of Semipalatinsk polygon. As a monitoring site the settlement “Bayan – Aul” from Pavlodar district has been selected. This settlement has similar natural environments, living level and foodstuff of the population, but there did not passed tracks from clouds of nuclear tests, and the contents of radionuclides in objects of environment is lower than a background of global losses for middle latitudes of northern hemisphere.
The revised version of a questionnaire for studied person was offered, it was discussed with collaborator L. Peterson (USA) by e-mail and the questionnaire final version was adopted. So all the demands of Scandinavian Committee how to work with patients which will be investigated will fulfilled. For the patients recruiting a free of charge stomatological help to population with this specially elaborated questionnaire filling is planned.
Enough complicate appeared the problem about dose load from short-lived radionuclides, which ones now has decayed for a long ago. One may consider that the main input to the dose from the short-lived radionuclides gives I-131. We tender to utilize an indirect route of definition dose load from I-131 on the basis of data about Cs-137 contents.
All these data and approach suggested were attentively discussed with potential collaborator Dr.P. Hill (Germany). He pointed that the method which was good for Chernobyl may be not so good for Semipalatinsk, because of Cs-137 has a rather short period of existence in a living organism, so the data on Cs-137 alone will not allow to reconstruct the whole dose in this case. He suggested to add to data on Cs-137 some data on other incorporated radionuclides, first of all on Sr-90, which have a long period of existence in organism ( in particular, in bones). The account of all these radionuclides should allow more reliable reconstruction of the whole dose. These recommendations were be taken into account and correspondingly included to the Project K-465.2 final text.
A very helpful for work at the Project there were participation in several International Meetings.
All these activities allowed to deliver the new advanced version of K-465.2 Project. All details of this new version were attentively discussed with US collaborator L. Peterson during the Project Manager S. Pivovarov visit to Houston.
Besides this during the PDG stage a lot of work was devoted to elaboration of the list of equipment, which will be needed for fulfilling the Project. For this aim a number of suggestions in Internet and in advertising prospects of various firms have been studied together with a price conjuncture. In result a list of equipment which is supposed to get on the Project was formed.
Also during the PDG stage the metrological testing of all main equipment, which will be used for the Project K-465.2 fulfilling, was made.
So, the PDG fulfilling allow to give full clear answers on US Party comments and was very helpful as a preparation stage for this big Project K-465.2 successful fulfilling.
The specific aims of the present project are:
1) To perform EPR with tooth enamel, cytogenetic biodosimetry, whole-body counting, radiological monitoring of soil, foodstuffs, and water to derive estimates of inpidual cumulative SNTS total doses among villagers living in Dolon, Mostik and Sarzhal (which received the greatest radiation dose from SNTS) and a non-exposed village having the same climatic and social conditions;
2) To estimate total radiation dose to subjects based on the various dosimetric methods used in Aim 1; compare differences in results across methods and compare with archived data; determine uncertainty distributions of parameters for which empirical data were collected;
3) Publish results in peer-reviewed literature, present results at International conferences, and disseminate findings through the World Wide Web.
Preliminary evaluations indicate that approximately 30-50 subjects will consent to provide tooth samples and peripheral blood samples in each of four selected villages. At the completion of the proposed Project, we will have for each subject:
- demographics and residence history of villagers
- personal dose based on EPR spectroscopy
- personal dose based on frequency of observed chromosome aberration of different types (unstable rings and dicentrics, stable reciprocal translocations, etc)
- the level of radionuclides contamination of soil, foodstuffs and water based on radiological monitoring
- personal dose based on results of incorporation monitoring
- archived data on above information
Thus, the planned work includes collection of samples in SNTS region, sample preparation, obtaining the experimental data using advanced dosimetry methods (listed above), developing a database, conducting data analysis with an intercomparison of results from different methods, presenting results and conclusions at International meetings and publishing results in the peer-reviewed literature.
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