The rapid increase of thyroid cancer among children of Belarus and Ukraine who were exposed to substantial fallout from the Chernobyl accident seems to be the major health effect resulting from the accident. A long-term epidemiological study to investigate the incidence of thyroid cancer among a cohort of 15,000 Belarusian children has been undertaken jointly by the Ministry of Health of Belarus and the National Cancer Institute (NCI) of the United States.

Estimation of the thyroid doses could be performed by the following methods:

Direct thyroid measurements were made among Belarusian children within a few weeks after the accident. These results are used to estimate thyroid exposure within the framework of the Scientific Protocol for the Study of Thyroid Cancer and Other Thyroid Disease in Belarus Following the Chernobyl Accident. In order to develop the environmental transfer approach, it is essential to collect and verify all the available radiation information that is reliable and that could be relevant to the estimation of the thyroid doses received by the Belarusian children.

Background: One of the fundamental aspects of the study is the estimation of the thyroid doses received by the 15,000 children of the cohort. (Astakhova, L.N., L.R.Anspaugh, G.W.Beebe, A.Bouville, V.V.Drozdovitch, V.Garber, Yu.I.Gavrilin, V.T.Khrouch, A.V.Kuvshinnikov, Y.N.Kuzmenkov, V.F.Minenko, K.F.Moschik, A.S.Nalivko, J.Robbins, E.V.Shemiakina, S.M.Shinkarev, S.I.Tochitskaya, M.A.Waclawiw. “Chernobyl-related thyroid cancer in children of Belarus: A case-control study.” Radiation Res. 150:349356 (1988); Becker D.V., J.Robbins, G.W.Beebe, A.C.Bouville and B.W.Wachholz. “Childhood thyroid cancer following the Chernobyl accident. – A status report.” Endocrinology and Metabolism Clinics of North America 25(1):197-211 (1996); IAEA – International Atomic Energy Agency. Summary of the Conference Results. Pages 3-17 in: One Decade after the Chernobyl. Summing up the Consequences of the Accident. Proceedings of an International Conference. Vienna, 8-12 April 1996. STI/PUB/1001. Vienna, 1996; Ivanov V.K., A.I.Gorsky, V.A.Pitkevitch, A.F.Tsyb, E.Cardis, H.Storm Risk of radiogenic thyroid cancer in Russia following the Chernobyl accident. Radiation and Thyroid Cancer (eds. G.Thomas, A.Karaoglou and E.D.Williams). Publication No. EUR 18552 EN of the European Commission; pp.89-96. World Scientific Publishing, 1999; Jacob P., G.Goulko, W.F.Heidenreich, I.Likhtarev, I.Kairo, N.Tronko, T.Bogdanova, Ya.Kenigsberg, E.Buglova, V.Drozdovitch, A.Golovneva, E.Demidchik, M.Balonov, I.Zvonova, V.Beral “Thyroid cancer risk to children calculated.” Nature 392:3031 (1998); Kazakov V.S., Demidchik E.P., Astakhova L.N. “Thyroid cancer after Chernobyl.” Nature 359:21 (1992). A long-term epidemiological study to investigate the incidence of thyroid canceramong a cohort of 15,000 Belarusian children has been undertaken jointly by the Ministry of Health of Belarus and the National Cancer Institute (NCI) of the United States (Anspaugh L.R., A.Bouville “United States-Assisted studies on dose reconstruction in the former Soviet Union.” European Commission 16544 EN; pp.1003-1010. Luxembourg, 1996). Measurements of exposure rate against their neck (called “direct thyroid measurements”) that were performed within a few weeks after the accident have been used to estimate the thyroid doses, which are mainly due to the ingestion of milk contaminated with Iodine-131. (Gavrilin Y., V.Khrouch, S.Shinkarev, V.Drozdovitch, V.Minenko, E.Shemyakina, A.Bouville, L.Anspaugh “Estimation of thyroid doses received by the population of Belarus as a result of the Chernobyl accident.” European Commission 16544 EN; pp.1011-1020. Luxembourg, 1996). There are, however, major uncertainties in this dose assessment. (Gavrilin Y., V.T.Khrouch, S.M.Shinkarev, N.A.Krysenko, A.M.Skryabin, A.Bouville, L.R.Anspaugh. “Chernobyl accident: Reconstruction of thyroid dose for inhabitants of the Republic of Belarus.” Health Phys. 67(2):105-119; 1999).

In order to confirm or evaluate the validity of the thyroid dose estimates derived from direct thyroid measurements, it is desirable to use an independent approach, called the “environmental transfer approach”. Within this method the transfer of 131I to man, and, consequently, the thyroid dose, is modeled using as a starting point the measurements of 131I concentration in soil available for various areas of Belarus, and making use also of other radiation measurements, such as exposure rates, 131I concentration in cows’ milk, or 131I concentration in leafy vegetables. (Bouville A. “Thyroid dose assessment: an overview of the problems and solutions.” (eds. G.Thomas, A.Karaoglou and E.D.Williams). Publication No. EUR 18552 EN of the European Commission; pp.297-308. World Scientific Publishing, 1999). Those measurements can be used to calibrate the model or to extrapolate it to regions for which 131I concentrations in soil are not available.

The Republican Center for Environmental Control and Radiation Monitoring of the State Committee for Hydrometeorology of Republic of Belarus, which has experience in that area, will be the organization responsible for preparing that information.

Realization of given Project allows to obtain more reliable thyroid dose estimates that will be further of progress in radiobiology.

Project participants: Specialists who worked in sphere of nuclear power engineering designing, and specialists in sphere radioecology, radiobiology, computer- and GIS-technology. Project participants have big experiences in the investigation of consequences of the Chernobyl accident. The main results of their activities have been reported on the International Conferences and published in more than 60 articles.

Expected results: Collected information will allow to obtain more reliable thyroid dose estimates for Belarusian population following the Chernobyl accident.

Application of Project results:

• The Project results will allow to assess a relationship between contamination of environment by 131I and increase of the number of thyroid diseases;

• With the use of the Project results the consequences of Chernobyl catastrophe in Belarus will assessed more accurately;

• The Project results could be used as a basis for planning of the protective measures in the case of accidents on other nuclear installations.

Meeting ISTC goals:

• The Project gives the possibility to scientists connected with military researches for reorientation of the gains on peace activity;

• The Project allows the scientists from Belarus to be integrated in the international scientific community with the help of the Nation Cancer Institute of the USA;

• The Project supports applied research in the field of environmental protection and in the field of radiation protection of the population in countries suffering from the consequences of the accident at the Chernobyl NPP.

Scope of activities: The given Project provides collection, analysis and reconstruction of radioactive contamination of the environment with 131I for the consequent estimation of thyroid doses for persons lived in Belarus as well as preparation of materials describing of a structure of the information blocks and of their contents. The Project is anticipated to be completed in 18 month. The estimated man-power of Project is 69 menmonth. Two organizations participate in Project: Republican Center for Environmental Control and Radiation Monitoring (RCECRM) of the State Committee on Hydrometeorology of Belarus and Institute of Power Engineering Problems of the National Academy of Sciences of Belarus.

Role of Partner: The Partner will provide 100% of financial support for the Project. The Partner is responsible for:

The Partner organized publications of obtained results in western scientific periodical literature.

Technical approach and methodology: To estimate thyroid doses it is necessary to collect information on 131I contamination. To assess activity of 131I deposited onto the ground for territories where no experimental data exist the correlation-regression analysis will be used. Structure of information block must be account for requirements of the GIS technologies.