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Health Consequences of Chernobyl Accident: Lessons Learned from Medical Response

This module discusses the health consequences and lessons learned from the medical response to the Chernobyl nuclear accident in 1986. It examines the radiation effects, including the release of radionuclides and their impact on human health, such as thyroid cancer. The module also explores the biological effects of ionizing radiation and the long-term consequences of exposure.

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Health Consequences of Chernobyl Accident: Lessons Learned from Medical Response

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  1. HEALTH CONSEQUENCES OF AND LESSONS LEARNED FROM MEDICAL RESPONSE TO SELECTED RADIATION ACCIDENTS Module XIX Chernobyl

  2. Accident at Chernobyl NPP (26 April 1986) Moscow RUSSIAN FEDERATION Kaluga BELARUS Bryansk Gomel ? Chernobyl Kiev UKRAINE Map of area studied Module Medical XIX-(15)

  3. Chernobyl reactor accident Total contaminated surface (> 1 Ci/km2):1000000 km2 Near zone (<100 km):deposition of heavy particles ( Sr, Pu... Far zone (up to 2000 km) :deposition of volatile elements (I, Cs) Module Medical XIX-(15)

  4. Chernobyl disaster: radionuclides released Module Medical XIX-(15)

  5. Main radionuclides contributing to health effects • iodine - 131 • volatile • T1/2: 8 day • disappears from environment in 2 months • inhalation and ingestion • concentrates in thyroid • caesium-137 • volatile • T1/2: 30 years • stays long in environment • body elimination in about 100 days • homogenous distribution in all organs and soft tissues Module Medical XIX-(15)

  6. Biological effects of exposure to ionizing radiation • Deterministic effects • occur when the dose is above given threshold (characteristic for the given effect) • severityincreases with the dose • many cells die or have function altered • examples: erythema, fibrosis, marrow depletion, cataract • Stochastic (probabilistic) • have no known threshold • probability of occurrence increases with dose • may result from alteration in only one or few cells • examples: carcinogenic - various neoplasms • genetic - various hereditary disorders Module Medical XIX-(15)

  7. Erythema on a Chernobyl fireman on Day 17 (primarily from beta radiation) Module Medical XIX-(15)

  8. Severe multiple necrotic-ulcerative radiation burns in Chernobyl fireman on Day 40 after the accident Module Medical XIX-(15)

  9. Lloyd, D.C.: Chromosome analysis to assess radiation dose, Stem Cells, 15: 195-201, 1997 Module Medical XIX-(15)

  10. Module Medical XIX-(15)

  11. 14 death in 106 confirmed ARS patients, 1987-2000 • In 1987-2000 14 confirmed ARS patients died for different reasons • Cause of death only in three cases (Myelodysplastic syndrome) may be associated with II-III degree of ARS • [Ref.: UNSCEAR Report 2000, Part II, Table 55, p.542, United Nations, New York, 2000] Module Medical XIX-(15)

  12. Module Medical XIX-(15)

  13. Human data on radiation cancerogenesis Module Medical XIX-(15)

  14. Thyroid cancer and ionizing radiation • Chernobyl accident shows that exposure to iodine isotopes may cause increase in prevalence of thyroid carcinoma • In 1990-2000about 1800 thyroid cancers observed in 18 million children and adolescents, i.e. under18 years old, living in the most contaminated areas of Belarus, Ukraine and Russia Module Medical XIX-(15)

  15. Post-Chernobyl thyroid cancer • increase observed mainly in children under 15 • incidence rates increased by 100 in the most affected areas (Gomel, Belarus and North of the Ukraine) in 1990-94 • incidence rate multiplied by 3 in adults (Belarus) Module Medical XIX-(15)

  16. Childhood thyroid cancer around Chernobyl in 1986-1998 (children <15 years old at diagnosis) [UNSCEAR: Exposures and Effects of the Chernobyl Accident, Annex J, New York, 2000] Module Medical XIX-(15)

  17. Incidenceof childhood thyroid cancer (<15 years old at diagnosis) around Chernobyl in 1986-1998 Incidence,number of new cases in 100 000 children per year [UNSCEAR: Exposures and Effects of the Chernobyl Accident, Annex J, New York, 2000] Module Medical XIX-(15)

  18. Thyroid cancer around Chernobyl in 1986-1998 (Annual number of cases among ~18M citizens <18 years old in 1986) [UNSCEAR: Exposures and Effects of the Chernobyl Accident, Annex J, New York, 2000] Total No. of thyroid cc. in 13 years =1791 - Module Medical XIX-(15)

  19. Clinical and epidemiological features of childhood thyroid carcinomas diagnosed in Belarus Chernobyl accident • less influenced by gender • female/male ratio was 1.4:1.0 (spontaneous: 2.5/1) • mean age • At time of first diagnosis: 9.4±2.8 years • At time of the accident: 3.8 ± 2.4 years • More than 90% of the patients were less than 6 years old and 3% were still in utero at time of accident. Module Medical XIX-(15)

  20. Morphological analysis of post-Chernobyl childhood thyroid carcinomas • Large majority are papillary carcinomas, very few follicular histotype. Among papillary type, many (33%) solid and follicular variants • Focal micropapillary hyperplasia frequently found in post-Chernobyl thyroid glands J Clin endocrinol Metab 1997;82:3563 Cancer 1994;74:748 J Clin Endocrinol metab 1996;81:9-14 Module Medical XIX-(15)

  21. Distribution of thyroid doses in children and adolescents in Belarus and the Ukraine % Module Medical XIX-(15)

  22. Thyroid doses in I-131 therapy vs radiation induced thyroid carcinoma -500Gy I-131 therapy of differentiated thyroid carcinoma -250 Gy -100 Gy I-131 therapy of hyperthyroidism -70 Gy radiation induced thyroid carcinoma -0.15-5.7 Gy Module Medical XIX-(15)

  23. Other factors contributing to the increased rate of childhood thyroid cancer around Chernobyl • moderate to severe iodine deficiency • late iodine prophylaxis (or thyroid blocking in many villages and towns not evacuated) • active screening (ultrasound, fine needle biopsy) manifesting also the occult cases • awareness (parents request more thyroid examinations of their children than before) Module Medical XIX-(15)

  24. Leukemia and other cancer • No significant increase in leukemia or cancer other than thyroid; solid tumor observed in Chernobyl cleanup workers* • Tendency for elevated leukemia rates, however, among those who received significant doses while working on site in 1986 and 1987. So far statistically significant leukemia excess reported for Russian cleanup workers only** Module Medical XIX-(15)

  25. Psychological disorders • Significant psychological disorders caused by mental distress, among most frequent consequences of accident • Psychological effects of Chernobyl accident mainly due to lack of reliable public information • Distress caused by misperception of radiation risk extremely harmful Module Medical XIX-(15)

  26. Lifetime mortality in population of all ages from fatal cancer after exposure to low doses * general public (all age groups) only Summary factor of cancer risk for working population taken to be 400x10-4 Sv-1 Reference ICRP, Publ. 60, 1991 Module Medical XIX-(15)

  27. Attributable lifetime risk of fatal cancerdepending on age at exposure Attributable lifetime risk, % per sievert Age at time of exposure Module Medical XIX-(15)

  28. Module Medical XIX-(15)

  29. Module Medical XIX-(15)

  30. Chernobyl conclusions • Radiation burns frequent • Burns over 50% of body surface led to death in 19 of 28 cases • Internal contamination present in most patients but was significant in few • Sepsis was uniform cause of death • BMT –very limited indication • Some radiation burns did not re-epithelialize, required surgery Module Medical XIX-(15)

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