Radiation: What It Is, What You Need to Know - Softcover

Gale, Robert Peter; Lax, Eric

 
9780307950208: Radiation: What It Is, What You Need to Know
Softcover
ISBN 10: 0307950204 ISBN 13: 9780307950208
Verlag: Vintage, 2013

Inhaltsangabe

The universe was born in a nuclear explosion. We live on a radioactive planet. Without radiation there would be not life. And yet radiation remains deeply misunderstood and often mistakenly feared. Now Dr. Robert Peter Gale—one of the world’s leading experts on the subject—and Eric Lax set the record straight about subjects like uranium, plutonium, iodine-131, X-Rays, CT scans, and the radiation of food, while lucidly debunking myths about radioactivity. In this fascinating book, the authors explore the science, benefits, and risks of radiation exposure, drawing on the most up-to-date research and Gale’s extensive experience treating victims of radiation accidents around the globe. Here is an illuminating and essential guide to our post-Chernobyl, post-Fukushima world.

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Über die Autorin bzw. den Autor

Dr. Robert Peter Gale was on the faculty of the UCLA School of Medicine for twenty years and has served as chairman of the Scientific Advisory Committee of the International Bone Marrow Transplant Registry. He is the author of twenty-two medical books, eight hundred scientific articles, and numerous pieces on medical topics and nuclear energy for The New York Times, Los Angeles Times, and The Wall Street Journal.

Eric Lax is the author of medical/science books Life and Death on Ten West, an account of the UCLA bone marrow transplantation unit, as well as Woody Allen: A Biography, each a New York Times Notable Book of the Year. The Mold in Dr. Florey's Coat, about the development of penicillin, was a Los Angeles Times Best Book of the Year.

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Excerpted from the Hardcover Edition


CHAPTER 1

ASSESSING THE RISKS

How Can I Determine My Risk of Cancer From Radiation, and Why Is There So Much Disagreement Among Experts?

On July 16, 1945, in the Jornada del Muerto (Journey of Death) desert near Alamogordo, New Mexico, the fiery explosion of the Trinity test—the first atomic bomb—generated a light brighter than any ever seen on Earth. As it dimmed, it revealed a mushroom cloud of vaporized water and debris that grew thousands of feet into the air. J. Robert Oppenheimer (1904–1967), who more than anyone else was responsible for building the weapon, wrote afterward that watching the explosion brought to mind two lines from the sacred Hindu scripture the Bhagavad Gita: “If the radiance of a thousand suns were to burst into the sky that would be like the splendor of the Mighty One.” And: “I am become Death, the shatterer of worlds.” (It is perhaps more likely that his first thought was, Wow! Thank God, it worked!)

That shattering burst of energy was also an act of creation: it produced radioactive forms of natural elements that—apart from laboratory work during the bomb’s development—had never before existed on Earth, including ­cesium-­137, iodine-­131, and strontium-­90. During the months that followed these newly created radionuclides circled the globe and silently entered the bodies of everyone alive. And because some of these radionuclides remain radioactive for hundreds or thousands of years, the children of these people, their children, and all humans from that date until our species ceases to exist will have radionuclides created at the Trinity explosion in their bodies. The same is true for the radionuclides released by the more than 450 atmospheric nuclear weapons tests carried out by the United States, the Soviet Union, Britain, France, and China between 1945 and 1980, and from several nuclear power facility accidents. Of course, the amounts of radionuclides released from each of these sources differ vastly. It is inappropriate to consider atomic weapons and nuclear power facility accidents comparable, because the quantity of radionuclides released varies greatly, because they are not uniformly distributed over the Earth, and because different people have different likelihoods of encountering them.

Some of the radionuclides released by nuclear weapons testing and by nuclear power facility accidents can cause cancer. But some of the same radionuclides are used to diagnose and treat cancers and save lives. What is the balance between the potential harm and benefit posed by radionuclides and by all forms of radiation?

To determine whether this balance favors harm or benefit, it is necessary to know what radiation dose a person has received. This is not as simple as it might seem (in fact it is exceedingly complex, even for radiation experts), so we ask the reader please to bear with the following several pages of technical information, knowing that in the end all you ­really need to remember is one technical term: millisievert (mSv), named for the Swedish medical physicist Rolf Maximilian Sievert (1896–1966), who did pioneering work on the biological effects of radiation exposure. A sievert (Sv) is a unit of potentially harmful radiation. Each year we generally receive a few thousandths of a sievert, called a millisievert. People in the United States on average receive 6.5 mSv of radiation annually.

Radioactivity is measured by the number of atoms decaying (losing energy by emitting radioactive particles and/or electromagnetic waves) in a certain amount of time. The disappearance of a radionuclide is measured by how long it takes for one-­half of its atoms to decay. That can take a long time, as something can be reduced by one-­half almost forever, until only one atom remains—and then it decays. But most of the starting radioactivity is gone after about 10 half-­lives; only about one-­thousandth of the starting radioactivity remains.

These measurements have many names, depending on what you want to quantify. At first it is easy to mistake which unit to use, so one can end up comparing the radioactive equivalent of eels to elephants. It is also easy to mistake amounts: 1 microsievert (a millionth of a sievert) is a thousand times smaller than 1 millisievert (a thousand mSv make 1 Sv), yet several news reports of the Fukushima-­Daiichi nuclear power facility accident confused these units.

In estimating how a radiation exposure might affect us, scientists need to consider the amount of radiation we are exposed to; what type of radiation it is; how much of it gets into the various cells, tissues, and organs in our body; and how susceptible these tissues and organs are to radiation-­induced damage. Some cells, like bone marrow, skin, and gastrointestinal tract cells, are especially sensitive to damage from radiation. One reason is that they divide frequently—rapidly dividing cells are more sensitive to radiation that damage DNA. For example, a normal person needs to produce about 3 billion red blood cells each day to stay healthy. Other cells, predominantly those that divide infrequently, if ever, like heart, liver, and brain cells, are relatively resistant to radiation-­induced damage.

So to determine the amount of radiation in an exposure, we must calculate the quantity of radiation emitted or released from a source, be it a CT scanner, a radiation therapy machine, a nuclear weapon, a failed nuclear power facility, or a radioisotope injected for a PET scan.

But calculating the quantity of radiation is complex. Some diagnostic radiation machines emit electromagnetic waves such as X‑rays or particles such as protons, neutrons, or electrons. Other radiation-­related activities, like fissioning uranium-­235 or plutonium-­239 in a nuclear weapon, emit gamma rays and neutrons. Most fission products emit electrons and gamma rays. The explosion of the Chernobyl nuclear reactor released into the environment more than 200 radionuclides in diverse physical and chemical forms, including radioactive gases such as xenon-­133 and iodine-­124 and -131, as well as radioactive particles. These gases rapidly disperse into the atmosphere. The radioactive particles also disperse across a very broad area—unless it happens to rain when the radioactive cloud passes over you and particles of cesium-­137 and strontium-­90 fall to the ground with the raindrops.

Unfortunately, when the radioactive plume from the 1986 Chernobyl accident containing particles with iodine-­131 and cesium-­137 passed over Scotland, it was raining. Consequently, substantial amounts of these radionuclides landed on grass. The grass was subsequently eaten by grazing animals, especially sheep, and those radionuclides were incorporated into their bodies and secreted in their milk. The iodine-­131, with an 8-­day half-­life, was gone in about three months. But the cesium-­137 was concentrated in the meat of the sheep, and with its half-­life of 30 years, it stayed around for the lifetime of the sheep. The level of cesium-­137 in many of these animals exceeded government safety standards; consequently many sheep were killed and buried, and their meat was quarantined from the market.

For a radioactive substance or radionuclide, like a gram of radium-­232 or a gram of cesium-­137, we can compute how much radiation it releases by considering the number of spontaneous disintegrations (decays) that occur in the nuclei of the atoms in that gram over a certain time interval, for example, one second. This rate of decay, referred to as the...

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Verlag
Vintage
Erscheinungsdatum
2013
Sprache
Englisch
ISBN 10 
0307950204
ISBN 13 
9780307950208
Einband
Taschenbuch
Anzahl der Seiten
288
Kontakt zum Hersteller
Nicht verfügbar
Verantwortliche Person
Nicht verfügbar

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