134: Radiation

INTRODUCTION

Although the theory of atomism originated with the Greeks in the fifth century BC, it has been only a little more than a century that scientists could describe and measure atoms and the other particles of radiation. Today we utilize radiation and radionuclides for a vast array of purposes, ranging from mundane household uses such as smoke detection to powering satellites, cancer treatment, and examining the physical properties of individual molecules. Unfortunately, as our knowledge of how to use radiation has expanded so too has our awareness of radiation as a toxin. Indeed, for each of the last three editions of this text, there has been a significant radiation event that captured the world’s attention and demonstrated clearly just how much more we need to know. The particles of radiation, their sources, and the mechanisms by which they pose a health risk are the subjects of the following discussion.

HISTORICAL EXPOSURES

Soon after x-rays were discovered in 1895, a deepening understanding of radiation and radionuclides led to their wider use and their resulting injuries. In the early days of radiation, exposures were small and of low energy, which nevertheless created injuries for a relatively small number of individuals. Clarence Dally was the first known radiation-induced death in 1904 following repeated exposures to Thomas Edison’s early fluoroscopes. By 1927 nearly 100 women employed to create illuminated instrument dials became ill or died after exposure to radium-­containing paint. Efforts to protect workers such as those by the British Roentgen Society were hampered by limitations on measurement of radiation despite the development in 1908 of the Geiger counter that could detect but not quantify radiation. Much later in 1984 and again in 1987, lack of proper remediation of closed radiation treatment centers led to scavengers releasing sources of ⁶⁰ Co and ¹³⁷Cs, respectively. In the cobalt incident beginning in Juarez, Mexico, thousands of tiny metal pellets were spilled in a scrapyard and melted with other metals into table legs later shipped throughout Mexico and the United States. In the cesium incident in Goiânia, Brazil, scavengers were fascinated by the bluish glow of the material. Ultimately, 250 individuals were contaminated, 46 patients were treated with a chelator,and 4 died the month following the initial exposure with another dyingseveral years afterward from radiation-induced injuries.

With the advent of the nuclear age, said to have begun with the first detonation of an atomic bomb in New Mexico in July 1945, suddenly the risks of radiation exposure grew to many thousands at once. Following the use of the two atomic bombs in Japan at the end of World War II, estimates of dead and injured for both cities were well over 200,000. Most of the deaths were from the bomb blast, but many thousands died from acute radiation syndrome (ARS) and others subsequently from radiation-induced cancers. In addition to the people of those cities who were victims of ...