2 Radioactive gas radon. This comes from the disintegration of
radium. It escapes from soil and rocks into the atmosphere. It enters the body by
people inhaling the substance when they breathe.
3 Carbon-14. This is a substance produced in the atmosphere; all
living material has some Carbon-14.
b. Man-Made Radiation.
(1) Medical radiation. Today, people may be exposed to two types of
radiation: diagnostic radiation (dental x-rays, chest x-rays) or therapeutic radiation
(radiation to treat a disease). X-rays can be taken of any part of the body. By means of
x-ray, the doctor can see problems in the kidney, possible broken bones, congestion in
the lungs, and so forth. When proper precautions are taken, such as the use of protective
devices and reasonable limitations to the use of radiation, there are great benefits to the
physician.
(2) Industrial radiation. A variety of devices using various types of radiation
exist in the world today. Some are as sophisticated and complex as nuclear generators
and reactors, while others are as ordinary as the microwave ovens used to dry potato
chips. Other radiation equipment is used to test new products. These and many more
radiation devices are all potential sources of radiation to people.
(3) Fallout. Most publicized is fallout from nuclear explosions. Particles
from surface explosions, shallow surface reactions, or low air bursts are capable of
producing radioactive contamination over large areas next to the explosion site. The
residue may be so great as to be a biological hazard. Delayed fallout (fallout which
comes after the first day) consists of very fine, invisible particles which settle in low
concentration over a large area of the earth's surface. If the fallout is from a surface
burst, a fireball may interact with surface earth and water. The strong after-winds at the
surface of the earth will cause large amounts of earth or water to be sucked up as the
fireball rises. As this mass cools, the radioactive particles of earth and water fall to
earth contaminating the area in which they drop.
(4) Radiation from other sources. There are other sources of radiation in
addition to the sources just discussed (natural background radiation, environmental
contamination radiation, and medical radiation).
(a) Radium in watches/clocks. For many years, radium was used for
the luminous markings on watch and clock dials. Enough radium was used so that
people who made the watches, sold the watches, or wore the watches were exposed to
radiation from the radium.
MD0587
2-5
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