Radiation has always been part of our natural environment. It comes to us as a result of radioactive mineral deposits, cosmic radiation, and similar natural phenomena. Today, however, our environment also contains humanmade radiation. It comes from medical X-rays and radiation therapy, microwave ovens, color television sets, industrial isotopes and X-rays, radioactive wastes from nuclear power plants, and nuclear fallout from weapons testing.
Natural radiation is responsible for about 58 percent of an average person`s exposure to radiation in the environment. Humanmade radiation accounts for 41 percent, and the remaining 1 percent comes from fallout. (Concerns about nuclear fallout led to the 1963 treaty between the United States and the Soviet Union banning atmospheric testing of atomic weapons).
Radiation may enter the body directly through the skin, but it is usually inhaled ingested as radioactive particles or substances. The effect of radiation exposure depends on the dose, the length of exposure, the type of radiation, and the individual`s degree of sensitivity.
Prolonged or excessive exposure produces radiation sickness in most people. The symptoms of this disease come in stages : first, diarrhea, nausea, vomiting; second, loss of hair, hemorrhaging beneath the skin surface, ulcers in the mouth and digestive system; third, eye cataracts, high susceptibility to infections, and possible leukemia. In general, women tend to be more vulnerable to the effects of radiation than are men.
Vulnerable Parts of The Body
Radiation has its most serious effect on those tissue in which cells normally reproduce rapidly-the lining of the digestive tract, the blood-forming tissues, and so on. Especially vulnerable are sperm and egg cells and developing fetuses. Radiation is thus a major factor in genetic mutations, and significant doses are known to cause infertility, miscarriage, and birth defects. And certain radioactive elements can remain in the body indefinitely, emitting harmful radiation over a long period of time. Strontium-90 accumulates in bones; plutonium collects in the liver, bones, and sex organs.
Radiation and Cancer
The tissues of the body vary widely in their sensitivity to radiation. Some tissues are very sensitive to radiation and will become damaged with minimal does; others are remarkably resistant. Diagnostic radiation-use of radiation as an aid in diagnosing disease-usually presents such a small risk of disease that the benefits are thought to outweigh any risk.
In doses below those that cause radiation sickness but above normal (such as those experienced by people who work with radioactive materials), radiation is thought to be carcinogenic. Because radioactive particles act primarily to alter or destroy individual cells, long-term exposure at normally “nondangerous” levels may promote cancerous growth. Recent studies indicate that there may be no safe level of radiation exposure, no dose of radiation so low that the risk of cancer is zero.
Some researchers believe that humans are exposed to unnecessary doses of radiation through routine dental and diagnostic X-rays. Reflecting this concern, in November 1982 the American College of Radiologists joined a growing list of clinicians in recommending that chest X-rays be used more springly. Other medical professionals have expressed hope that the development of revolutionary techniques for viewing body tissues without X-rays will replace the use of radiationdependent equipment in clinical diagnosis.
References :
A Turk et al., Environmental Science, Philadelphia : Saunders, 1974.
Jeanne Kassler, “Radiologists Urge Fewer Chest X-Rays”, New York Times, November 23, 1982.
Marvin R Levy, Mark Dignan, Janet H Shirreffs, Essentials of Life & Health, Fourth Edition, Random House, New York, 1984.
Jane E. Brody, “Magnetic Device Lifts Hopes for Diagnosis Without X-Ray”, New York Times, November 28, 1982.
