ABSTRACT
For nearly 100 years since the discovery of radioactivity, a number of experimental and epidemiologic studies have provided increasing information on the health risks of ionizing radiation. At the end of the nineteenth century and the beginning of the twentieth century, radiation exposure was considered to be a promising therapeutic approach for the treatment of cancer and other diseases. Mild radium therapy, involving the oral or parenteral administration of microgram quantities of radium and its daughter isotopes, was commonly used (Macklis 1990). The death in 1932 of
7.1 Introduction .................................................................................................. 107 7.2 Units of Radiation Dose: Basic Terms and Denitions ................................ 109 7.3 Low-Dose Radiation Effects in Human Studies ........................................... 109
7.3.1 Health Effects in Professionally Exposed Groups ............................ 110 7.3.1.1 Health Status in Medical Professional Groups Exposed
to Radiation in Their Work Environments ........................ 111 7.3.1.2 Nuclear Worker Cohort Studies ......................................... 113 7.3.1.3 Long-Term Follow-Ups in Nuclear Test Participants ......... 116
7.3.2 Diagnostic and Therapeutic Medical Exposures .............................. 116 7.3.2.1 Diagnostic Radiation Procedures....................................... 117 7.3.2.2 Radiotherapy ...................................................................... 118
7.3.3 Environmental Background Radiation ............................................. 120 7.3.4 Residential Radon and Lung Cancer Risk ........................................ 121 7.3.5 Long-Term Health Consequences of Accidents in Nuclear
Power Plants ...................................................................................... 123 7.3.6 Health Status in Atomic Bomb Survivors ........................................ 128
7.4 Mechanisms of Radiation Hormesis ............................................................. 130 7.4.1 Immune System Response ................................................................ 131 7.4.2 Deoxyribonucleic Acid Repair ......................................................... 133 7.4.3 Free Radical Scavenging .................................................................. 134 7.4.4 Heat-Shock Response ....................................................................... 135 7.4.5 Autophagy and Apoptosis ................................................................. 135 7.4.6 Epigenetic Alterations....................................................................... 136
7.5 Concluding Remarks .................................................................................... 139 Acknowledgment ................................................................................................... 140 References .............................................................................................................. 140
the prominent millionaire Eben M. Byers from radium poisoning after consuming a large quantity of Radithor (a popular and expensive mixture of radium-226 and radium-228 in distilled water) helped to bring about an end to the era of mild radium therapy. The event alerted the public and much of the medical profession about the potential harmful effects of internal radium.
