Sources and Effects of Ionizing Radiation—UNSCEAR 2008
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SOURCES AND EFFECTS OF IONIZING RADIATION United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR 2008 Report to the General Assembly with Scientific Annexes VOLUME II Scientific Annexes C, D and E UNITED NATIONS New York, 2011 NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. UNITED NATIONS PUBLICATION Sales No. E.11.IX.3 ISBN-13: 978-92-1-142280-1 e-ISBN-13: 978-92-1-054482-5 © United Nations, April 2011. All rights reserved. Publishing production: English, Publishing and Library Section, United Nations Office at Vienna. CONTENTS Page VOLUME I: SOURCES Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation VOLUME II: EFFECTS Annex C. Radiation exposures in accidents. 1 Annex D. Health effects due to radiation from the Chernobyl accident. 45 Annex E. Effects of ionizing radiation on non-human biota . 221 iii ANNEX d health EFFECTS DUE TO RADIATION FROM THE CHERNOBYL ACCIDENT CONTENTS Page I. INTRODUCTION. 47 A. past assessments. 47 B. Structure of the present scientific annex .................................................. 49 II. pHYSICAL AND ENVIRONMENTAL CONTExT . ................................................. 49 A. Radionuclide release and deposition. 49 B. Environmental transfer. 51 C. Environmental countermeasures. 53 III. RADIATION DOSES TO ExpOSED pOpULATION GROUpS. 53 A. Doses to workers involved in response and recovery. 54 B. Doses to general population. 54 IV. ATTRIBUTION OF HEALTH EFFECTS TO RADIATION ExpOSURE. 56 A. General discussion. 56 B. Deterministic effects. 56 C. Stochastic effects. 56 D. psychological trauma and other related effects. 57 V. EARLY HEALTH EFFECTS . ................................................................. 58 A. Acute radiation syndrome in emergency workers . 58 B. General public. 59 VI. LATE HEALTH EFFECTS . .................................................................. 59 A. Actual observations .................................................................. 59 1. Late health effects in ARS survivors. 59 2. Thyroid cancer . 60 3. Leukaemia . 61 4. Other solid cancers ............................................................... 62 5. Non-cancer effects ............................................................... 62 B. Theoretical projections ................................................................ 63 1. Review of published projections. 63 2. Scientific limitations. 64 3. UNSCEAR statement. 64 VII. GENERAL CONCLUSIONS. 64 A. Health risks attributable to radiation . 64 B. Comparison of present annex with previous reports . 65 C. Comparison of observed late health effects with projections. 65 D. New knowledge from studies of the accident. 66 45 Page ACKNOWLEDGEMENTS. 66 AppENDIx A. pHYSICAL AND ENVIRONMENTAL CONTExT . 67 AppENDIx B. RADIATION DOSES TO ExpOSED pOpULATION GROUpS .................................. 103 AppENDIx C. EARLY HEALTH EFFECTS . 145 AppENDIx D. LATE HEALTH EFFECTS ............................................................ 151 REFERENCES. 205 46 I. introdUCTION 1. The 1986 accident at the Soviet Union’s Chernobyl populations in Belarus, the Russian Federation and Ukraine5 nuclear power plant (ChNPP) was the most severe ever to (the three republics). Two radionuclides, the short-lived have occurred in the civilian nuclear power industry.1 It trig- iodine-131 (131I with a half-life of 8 days) and the long-lived gered an unprecedented international effort to improve caesium-137 (137Cs with a half-life of 30 years), were par- understanding of the health effects due to radiation from the ticularly significant for the radiation dose they delivered to accident and has become the most extensively studied members of the public. accident involving radiation exposure. 4. In the former Soviet Union, the contamination of fresh 2. Two workers died in the immediate aftermath; and milk with 131I and the lack of prompt countermeasures led to high doses of radiation2 to 134 plant staff and emergency high thyroid doses, particularly among children. In the longer personnel3 resulted in acute radiation syndrome (ARS), term, mainly due to radiocaesium, the general population was which proved fatal for 28 of them. Other than this group also exposed to radiation externally from radio active deposi- of emergency workers, several hundred thousand were tion and internally from consuming contaminated foodstuffs. involved in recovery operations;4 they were exposed However, in part because of the countermeasures taken, the externally and, to a lesser degree, internally to radiation resulting radiation doses were relatively low (the average from the damaged reactor and from radionuclides released additional dose in 1986–2005 in “contaminated areas”6 of the to the environment. three republics was about equivalent to that from a computed tomography (CT) scan in medicine), and should not lead to 3. The accident caused the largest uncontrolled radioactive substantial health effects in the general population that could release into the environment ever recorded for any civilian be attributed to radiation exposure from the accident. Even operation; large quantities of radioactive substances were so, the severe disruption caused by the accident, confounded released into the air for about 10 days. The radioactive cloud with the remarkable political changes that took place in the dispersed over the entire northern hemisphere, and deposited Soviet Union and the new republics, resulted in major social substantial amounts of radioactive material over large areas and economic impact, and great distress for the affected of the former Soviet Union and some other countries in populations. Europe, contaminating land, water and biota, and causing particularly serious social and economic disruption for large A. past assessments 5. There has been an unprecedented effort by the inter- 1 The accident site is located in present-day northern Ukraine, some 20 km national community to assess the magnitude and character- south of the border with Belarus and 140 km west of the border with the istics of the health effects due to the radiation exposure Russian Federation. The accident occurred on the 26 April 1986 during a resulting from the accident. As early as August 1986, a low-power engineering test of the Unit 4 reactor. Improper, unstable opera- tion of the reactor, which had design flaws, allowed an uncontrollable power widely attended international gathering, the “Post- Accident surge to occur, resulting in successive steam explosions, which severely Review Meeting”, was convened in Vienna. The resulting damaged the reactor building and completely destroyed the reactor [I7, I31]. report of the International Nuclear Safety Advisory Group 2 The term dose is used in this scientific annex in a number of ways: in a (INSAG) contained a limited but essentially correct early general sense, to indicate an amount of radiation absorbed from a given account of the accident and its expected radiological conse- exposure, and in two specific senses, to indicate either the physical quantity, absorbed dose, or the protection quantity, effective dose. Absorbed dose is quences [I31]. In May 1988, the International Scientific given in the unit, gray (Gy) (or appropriate submultiples) and effective dose Conference on the Medical Aspects of the Accident at the is given in the unit, sievert (Sv) (or appropriate submultiples). In general, Chernobyl Nuclear Power Plant [I32] held in Kiev sum- absolute values of dose relate to absorbed dose, unless otherwise indicated. marized the available information at the time and confirmed The concepts of collective absorbed dose and collective effective dose are that some children had received high doses to the thyroid. also used. 3 Approximately 600 workers responded on site within the first day to the In May 1989, scientists obtained a more comprehensive immediate emergency, including staff of the plant, firemen, security guards insight into the scale of the consequences of the accident at and staff of the local medical facility. an ad hoc meeting convened at the time of the 38th session 4 In 1986 and 1987 some 440,000 recovery operation workers worked at the Chernobyl site, and more such recovery workers were involved in various activities between 1988 and 1990. The work included, among other things, 5 At the time of the accident, these were three constituent Soviet Socialist construction of the sarcophagus over the damaged reactor and decontamina- Republics of the Soviet Union. tion of the site and roads. Special health registers currently hold records on 6 The “contaminated areas” were defined arbitrarily in the former Soviet more than 500,000 recovery operation workers