Page 42 - Curriculum Visions Dynamic Book

Irradiation
The word radiation has come to mean the harmful effects that radioactivity can have on the body. However, radiation can be a very useful process. Even despite accidents in the past, its usefulness far outweighs its dangers.
The key to understanding how to make use of radiation, and the precautions to take, is to understand what radiation does to living tissue.
Effects of exposure to radiation
Alpha rays are made of very bulky particles that eventually combine with electrons from other atoms to produce helium gas. They do not travel far inside the body. But the alpha particles cause great damage to body tissues because
they can knock atoms out of molecules and cause them to change or mutate. The effect is especially severe if the DNA inside cells is damaged. The result may be that the wrong signals are sent to build new tissue, and cancers may be formed.
Most body damage from alpha particles is caused to the DNA in skin cells. Beta radiation penetrates tissue more deeply than alpha radiation, reaching 2-3 cm inside the tissues. However, the most powerful form of radiation is gamma radiation, similar to X-rays. These waves of nuclear energy can pass right through the body and so can damage any atoms anywhere. Severe doses of this form of radiation can affect any of the body’s inside organs, causing what is known as “radiation sickness”.
Whichever form of radiation is involved, an overdose causes many cells to die or mutate. A general name for mutated cells is cancer, and natural radiation has been one contributor to many skin cancers.
Atom bomb testing in the atmosphere produced radioactive strontium-90. Strontium behaves chemically very much like calcium and is easily incorporated into
the bones. It is believed that strontium in bone cells
causes damage to blood cells, a form of cancer known as leukaemia. For this reason, there have been no atmospheric nuclear tests for many years.
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 The boxes on this conveyor belt are being irradiated to sterilise the medical equipment they contain.