RADIATION AND RISK

 

Bulletin of the (Russian) National Radiation

and Epidemiological Registry

ENGLISH TRANSLATION OF RUSSIAN SPECIAL ISSUE 2003

 

Massachusetts                                                                                                                   Moscow

Cambridge                                                                                                                        Obninsk

2003


ISSN 0131-3878

 

 

Thyroid doses, prediction of radiation-induced thyroid cancers and estimation of radiation risks of thyroid cancer among residents of the Oryol oblast

 

English Translation by scientists in Obninsk

Edited by Richard Wilson, Harvard University

 

Obninsk                                                 Harvard University

Nr Moscow, Russia                               Cambridge, MA 02138

                                                               USA


Editor - in - Chief

 

A.F.Tsyb

 

Academician of RAMS; Chairman, All-Russia Scientific Commission on Radiation

Protection; Director, Medical Radiological Research Center of RAMS (Obninsk)

 

 

Deputy Editor

 

V.K.Ivanov

 

Corr. Member of RAMS; Deputy Chairman, All-Russia Scientific Commission on Radiation Protection;
Deputy Director, Medical Radiological Research Center of RAMS (Obninsk)

 

 

Editorial Coordinator

 

V.A.Sokolov

 

Cand. Sc., Biology

 

 

Analytical group of special issue

 

D. Sc., Tech.

O.K. Vlasov

 

Cand. Sc., Phys.-Math.

O.V. Kaidalov

 

Cand. Sc., Phys.-Math.

A.I. Gorski

 

A.M. Godko

 

© Medical Radiological Research Center of RAMS, 2003 in cooperation with SPC "Medinfo".

ISSN 0131-3878

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Address for English Translation:                         "Radiation and Risk",

                                                                     c/o Richard Wilson

                                                                     Department of Physics

                                                                     Harvard University

                                                                     17 Oxford Street

                                                                     Cambridge, MA 02138, USA

                                                                     telephone:                 617-495-3387

                                                                     fax:                          617-495-0416

                                        E-mail:                      WILSON5@FAS.HARVARD.EDU

 

Contents

 

Preface to English Translation by Richard .Wilson....................................           4    Download original MSWORD file

 

1.   Thyroid doses from incorporated 131I for residents of the Oryol oblast...........................5     Download original MSWORD file

 

 

2.   Prediction of radiation-induced thyroid cancers among residents of the Oryol oblast  based on the ICRP models.............................................................................................................................           17     Download original MSWORD file

 

3.   Estimation of radiation risks of thyroid cancer in the population of the Oryol oblast... 32    Download original MSWORD file

 


 

 

Preface to English Translation

 

 

 

The principal radionuclide in the fallout from the accident at  the Chernobyl nuclear power plant that leads to long term radiation exposures is 137Cs.   It is the radiation from this radionuclide, with a half life of 30 years, that is the principal cause of the “whole body” dose.   With its long half life it lasts in the environment and can be measured many years after the accident.  If there is controversy about doses at a particular location, the radiation can be remeasured.  

 

But the principal exposure to the thyroid gland comes from radioactive iodine –  primarily  131I .   Unfortunately measurements of  131I  were not undertaken in many places till a month or more had passed and much of the iodine had decayed.   The dose reconstruction is therefore much more complex.   Nonetheless the general scheme for reconstruction of doses to the thyroid from Chernobyl fall out are now fairly well established.  The basic detailed information is that of the 137Cs deposition.    It is assumed that locally the ratio of Iodine deposition to cesium deposition is constant since both Cs and I were deposited out of the same radioactive cloud,   although there are larger scale variations from oblast to oblast.    Then  iodine deposition and radiation doses to  the thyroid from iodine may be estimated.

 

The papers in this issue are concerned with the iodine doses, and consequent radiation doses in the Oryol (Oriel) oblast.    They are also concerned with thyroid cancer incidence.    The attempt is made to relate the two. 

 

There are several problems with the attempts to relate thyroid cancer to radiation dose.    These are related to the pathological definitions of thyroid disease, especially cancer.  Diagnoses of thyroid cancers and measurements of the incidence of thyroid diseases in general vary with time and are much more complete since the Chernobyl accident than before the accident.    This inevitably leads to a (spurious) increase in measured incidence since the accident (often called the “screening” effect).  In addition, since thyroid cancer is not often fatal, a “harvesting” effect can occur when there is a change in the completeness of diagnosis as tumors and diseases ignored over the preceding years are suddenly included in the data. 

 

But excessive attention to these details can lead to a failure to recognize a problem early enough.  When a large number of childhood thyroid cancers were discovered in Belarus in 1990, they were met with skepticism for the above reasons.  The skeptics were wrong.  The incidence of childhood thyroid cancers is the prominent feature of the consequences of the Chernobyl accident.  What is the situation with adult cancers in 2003?   

 

The papers here may help to address this issue.   The numbers are too small for a statistically significant increase of cancers to be seen in an epidemiological study with the oblast taken as a whole,  but the papers presented show that if only rayons with high estimated doses are included in such a study,  a more sensitive test is possible.