Health Risks of Ionizing Radiation: An Overview of Epidemiological Studies A Report by the Community-Based Hazard Management Program George Perkins Marsh Institute Clark University March 2006 Health Risks of Ionizing Radiation: An Overview of Epidemiological Studies by Abel Russ, Casey Burns, Seth Tuler, and Octavia Taylor Community-Based Hazard Management The George Perkins Marsh Institute Clark University Worcester, MA 01610-1477 USA March 2006 Contents List of Tables ............................................................................................................................... vi List of Figures ............................................................................................................................. vii Acknowledgments ........................................................................................................................ x 1. INTRODUCTION ................................................................................................................ 1 1.1 Goals ............................................................................................................................. 1 Ionizing radiation ................................................................................................... 1 Low dose ................................................................................................................ 1 1.2 A brief history of radiation ........................................................................................... 1 1.3 Exposure ....................................................................................................................... 2 1.4 Standards ...................................................................................................................... 3 1.5 Radiation basics ............................................................................................................ 3 1.6 Epidemiological methods ............................................................................................. 7 Statistical significance ............................................................................................ 7 Study design ........................................................................................................... 8 1.7 Risk terminology .......................................................................................................... 9 Relative risk ........................................................................................................... 9 Excess relative risk (ERR) ..................................................................................... 9 Odds ratio (OR) ...................................................................................................... 9 Excessive absolute risk (EAR) ............................................................................... 9 Standardized incidence ratio (SIR) ........................................................................ 9 Standardized mortality ratio (SMR) ....................................................................... 9 P value .................................................................................................................. 10 Confidence interval .............................................................................................. 10 1.8 Dose-response curves ................................................................................................. 10 1.9 Overview structure ..................................................................................................... 11 2. BACKGROUND RADIATION ......................................................................................... 13 2.1 Introduction ................................................................................................................ 13 2.2 Summary of studies .................................................................................................... 13 External exposure ................................................................................................. 14 High exposure areas ............................................................................................. 14 Radon ................................................................................................................... 15 2.3 Discussion ................................................................................................................... 17 3. MEDICAL EXPOSURES .................................................................................................. 19 3.1 Introduction ................................................................................................................ 19 3.2 Diagnostic exposures .................................................................................................. 21 Diagnostic x-rays ................................................................................................. 21 Diagnostic iodine-131 .......................................................................................... 23 i ii Contents Thorotrast ............................................................................................................. 24 3.3 Radiotherapy for non-cancer disease .......................................................................... 24 Tuberculosis ......................................................................................................... 25 Ankylosingspondylitis ......................................................................................... 25 Hyperthyroidism .................................................................................................. 26 Radiotherapy for other non-cancer diseases ........................................................ 26 Radiotherapy for non-cancer disease in children ................................................. 26 3.4 Radiotherapy for cancer ............................................................................................. 28 Radiotherapy for childhood cancer ...................................................................... 29 3.5 In utero exposures ....................................................................................................... 29 3.6 Parental exposures ...................................................................................................... 30 3.7 Radiologists’ occupational exposures ......................................................................... 31 3.8 Conclusions ................................................................................................................ 31 4. ATOMIC BOMB SURVIVORS ........................................................................................ 43 4.1 Introduction ................................................................................................................ 43 RERF research ..................................................................................................... 43 Doses .................................................................................................................... 44 Uncertainties ........................................................................................................ 45 4.2 Cancer mortality ......................................................................................................... 45 4.3 Noncancer mortality ................................................................................................... 48 4.4.1 Solid cancer incidence ................................................................................................ 48 4.4.2 Incidence of leukemia and related cancers ................................................................. 49 4.5 Incidence of noncancer disease .................................................................................. 50 4.6 Preconception and prenatal exposures ........................................................................ 51 4.7 Discussion ................................................................................................................... 52 Age, time and gender ........................................................................................... 52 Dose-response curves ........................................................................................... 52 Applicability to other contexts ............................................................................. 53 5. NUCLEAR WEAPONS TESTING .................................................................................. 58 5.1 Military personnel ...................................................................................................... 58 5.2 Semipalatinsk Test Site downwinders ........................................................................ 59 5.3 Nevada Test Site downwinders ................................................................................... 60 Leukemia .............................................................................................................. 60 Thyroid disease .................................................................................................... 61 5.4 South Pacific testing ................................................................................................... 63 5.5 Health effects in Scandinavia ..................................................................................... 63 5.6 Discussion ..................................................................................................................