ANNEX J Exposures and effects of the Chernobyl accident CONTENTS Page INTRODUCTION.................................................. 453 I. PHYSICALCONSEQUENCESOFTHEACCIDENT................... 454 A. THEACCIDENT........................................... 454 B. RELEASEOFRADIONUCLIDES ............................. 456 1. Estimation of radionuclide amounts released .................. 456 2. Physical and chemical properties of the radioactivematerialsreleased ............................. 457 C. GROUNDCONTAMINATION................................ 458 1. AreasoftheformerSovietUnion........................... 458 2. Remainderofnorthernandsouthernhemisphere............... 465 D. ENVIRONMENTAL BEHAVIOUR OF DEPOSITEDRADIONUCLIDES .............................. 465 1. Terrestrialenvironment.................................. 465 2. Aquaticenvironment.................................... 466 E. SUMMARY............................................... 466 II. RADIATIONDOSESTOEXPOSEDPOPULATIONGROUPS ........... 467 A. WORKERS INVOLVED IN THE ACCIDENT .................... 468 1. Emergencyworkers..................................... 468 2. Recoveryoperationworkers............................... 469 B. EVACUATEDPERSONS.................................... 472 1. Dosesfromexternalexposure ............................. 473 2. Dosesfrominternalexposure.............................. 474 3. Residualandavertedcollectivedoses........................ 474 C. INHABITANTS OF CONTAMINATED AREAS OFTHEFORMERSOVIETUNION............................ 475 1. Dosesfromexternalexposure ............................. 476 2. Dosesfrominternalexposure.............................. 479 D. INHABITANTSOFDISTANTCOUNTRIES..................... 485 1. Thyroiddoses ......................................... 486 2. Bone-marrowdoses..................................... 486 E. COLLECTIVEDOSES ...................................... 486 1. Collectivedosesfromexternalexposure...................... 486 2. Collectivedosesfrominternalexposure...................... 486 3. Totalcollectivedoses.................................... 486 F. SUMMARY............................................... 487 452 ANNEX J: EXPOSURES AND EFFECTS OF THE CHERNOBYL ACCIDENT Page III. EARLY HEALTH EFFECTS IN REACTOR AND EMERGENCY WORKERS 488 IV. REGISTRATIONANDHEALTHMONITORINGPROGRAMMES........ 490 A. REGISTRATION AND MONITORING OFEXPOSEDPOPULATIONS................................ 490 1. TheChernobylregistries................................. 490 2. Specializedregistries.................................... 491 B. REGISTRATION OF MORTALITY AND DISEASE INTHEGENERALPOPULATION............................. 491 1. Mortality ............................................. 491 2. Cancerincidence....................................... 492 3. Specializedcancerregistries .............................. 492 C. QUALITY AND COMPLETENESS OF REGISTRATION ........... 493 1. Registersofexposedpopulations........................... 493 2. Registersofthegeneralpopulation ......................... 494 D. INTERNATIONAL COLLABORATIVE SCREENING PROJECTS .... 495 1. TheInternationalChernobylProject ........................ 495 2. TheIPHECAproject.................................... 495 3. The Chernobyl Sasakawa Health and Medical Cooperation Project . 495 E. SUMMARY............................................... 496 V. LATEHEALTHEFFECTSOFTHECHERNOBYLACCIDENT .......... 497 A. CANCER................................................. 497 1. Thyroidcancer......................................... 497 2. Leukaemia............................................ 504 3. Othersolidtumours..................................... 507 B. OTHERSOMATICDISORDERS.............................. 508 1. Thyroid abnormalities ................................... 508 2. Somaticdisordersotherthanthyroid........................ 510 3. Immunologicaleffects................................... 511 C. PREGNANCY OUTCOME ................................... 512 D. PSYCHOLOGICAL AND OTHER ACCIDENT-RELATED EFFECTS . 513 E. SUMMARY............................................... 514 CONCLUSIONS.................................................... 515 Tables ............................................................ 518 References ......................................................... 551 ANNEX J: EXPOSURES AND EFFECTS OF THE CHERNOBYL ACCIDENT 453 INTRODUCTION 1. The accident of 26 April 1986 at the Chernobyl especially in countries close to the reactor site. For nuclear power plant, located in Ukraine about 20 km south example, in Poland, although the countrywide population- of the border with Belarus, was the most severe ever to weighted average thyroid dose was estimated to be have occurred in the nuclear industry. The Committee approximately 8 mGy, the mean thyroid doses for the considered the initial radiological consequences of that populations of particular districts were in the range from accident in the UNSCEAR 1988 Report [U4]. The short- 0.2 to 64 mGy, and individual values for about 5% of the term effects and treatment of radiation injuries of workers children were about 200 mGy [K32, K33]. It was also and firefighters who were present at the site at the time of estimated in the UNSCEAR 1988 Report [U4] that the accident were reviewed in the Appendix to Annex G, effective doses averaged over large portions of European “Early effects in man of high doses of radiation”, and the countries were 1 mSv or less in the first year after the average individual and collective doses to the population of accident and approximately two to five times the first-year the northern hemisphere were evaluated in Annex D, dose over a lifetime. “Exposures from the Chernobyl accident”, of the 1988 Report [U4]. The objective of this Annex is (a) to review in 4. The doses to population groups in Belarus, the greater detail the exposures of those most closely involved Russian Federation and Ukraine living nearest the accident in the accident and the residents of the local areas most site and to the workers involved in mitigating the accident affected by the residual contamination and (b) to consider are, however, of particular interest, because these people the health consequences that are or could be associated have had the highest exposures and have been monitored with these radiation exposures. for health effects that might be related to the radiation exposures. Research on possible health effects is focussed 2. The impact of the accident on the workers and local on, but not limited to, the investigation of leukaemia residents has indeed been both serious and enormous. The among workers involved in the accident and of thyroid accident caused the deaths within a few days or weeks of cancer among children. Other health effects that are 30 power plant employees and firemen (including 28 considered are non-cancer somatic disorders (e.g. thyroid deaths that were due to radiation exposure), brought about abnormalities and immunological effects), reproductive the evacuation of about 116,000 people from areas sur- effects and psychological effects. Epidemiological studies rounding the reactor during 1986, and the relocation, after have been undertaken among the populations of Belarus, 1986, of about 220,000 people from what were at that time the Russian Federation and Ukraine that were most three constituent republics of the Soviet Union: Belorussia, affected by the accident to investigate whether dose-effect the Russian Soviet Federated Socialist Republic (RSFSR) relationships can be obtained, notably with respect to the and the Ukraine [K23, R11, V2, V3] (these republics will induction of thyroid cancer resulting from internal hereinafter be called by their present-day country names: irradiation by 131I and other radioiodines in young children Belarus, the Russian Federation and Ukraine). Vast and to the induction of leukaemia among workers resulting territories of those three republics were contaminated, and from external irradiation at low dose rates. The dose trace deposition of released radionuclides was measurable estimates that are currently available are of a preliminary in all countries of the northern hemisphere. Stratospheric nature and must be refined by means of difficult and time- interhemispheric transfer may also have led to some consuming dose reconstruction efforts. The accumulation environmental contamination in the southern hemisphere of health statistics will also require some years of effort. [D11]. In addition, about 240,000 workers (“liquidators”) were called upon in 1986 and 1987 to take part in major mitigation activities at the reactor and within the 30-km 5. Because of the questions that have arisen about the zone surrounding the reactor; residual mitigation activities local exposures and effects of the Chernobyl accident, the continued until 1990. All together, about 600,000 persons Committee feels that a review of information at this stage, received the special status of “liquidator”. almost 15 years after the accident, is warranted. Of course, even longer-term studies will be needed to determine the 3. Theradiation exposuresresulting from theChernobyl full consequences of the accident. It is the intention to accident were due initially to 131I and short-lived radio- evaluate in this Annex the data thus far collected on the nuclides and subsequently to radiocaesiums (134Cs and local doses and effects in relation to and as a contribution 137Cs) from both external exposure and the consumption of to the broader knowledge of radiation effects in humans. foods contaminated