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Radiation *(Cont'd)*
Background	Definition	Sources	Exposure	Home
Types	Noniodizing	Ionizing	Decay
Units	Risks & Benefits	Jobs	Glossary/Quiz

Noniodizing Radiation
Nonionizing radiation is not capable of knocking electrons out of atoms, creating electrically charged atoms. This type of radiation can damage living tissue by other means, such as by heating it. Nonionizing radiation, such as microwaves, sound waves, and light, may also be a health hazard if not properly controlled. That is why, for example, microwave ovens must pass stringent manufacturing standards. Interlocks are required to ensure that when you open the microwave oven door, the oven turns off.

Penetration Power
of Different Types of Ionizing Radiation
This illustration shows the penetrating power of the three types of ionizing radiation.

Radioactive Decay
Atoms in a radioactive substance decay in random fashion but at a characteristic rate. The half-life is the time taken for half of the atoms of a radioactive substance to decay. Half-lives can range from less than a millionth of a second to millions of years depending on the element concerned.

After one half-life the level of radioactivity of a substance is halved, after two half-lives it is reduced to one quarter, after three half-lives to one-eighth and so on.

Radiation Units
The Curie (Ci) is the basic unit to describe the intensity of radioactivity in a sample of material. It is named for Marie and Pierre Curie. There is also an international unit to describe intensity of radioactivity in a sample. This unit is called the Becquerel and is named after Antoine Henri Becquerel who discovered radioactivity.

The Rem is the unit of dose equivalent. The international unit is sievert.

Risks and Benefits of Radiation

The Risks
Experts are not in complete agreement regarding the precise nature and extent of the risks from exposure to low-level radiation. They do believe that some degree of risk is present even when people are exposed to very small amounts of radiation. Cancer, birth defects, cataracts, and shortening of one's life span are some of the more adverse effects of overexposure to radiation. These effects have been documented when people have been exposed to high levels of radiation. They have not been experimentally documented as results of exposure to radiation at low levels. The possible existence of these adverse health effects as a consequence of exposure to low-level radiation is suggested only by extrapolation from the experimental results of the exposures to high-level radiation.

The Benefits
Radiation does provide numerous benefits: improved medical diagnosis through the use of x-rays or the injection of radioactive isotopes, and improved treatment through the use of radioactive material. These are only two of the numerous beneficial uses of radiation. For example, an accepted treatment for an overactive thyroid (hyperthyroidism) is radioactive iodine; radiation is also used to treat cancer. Nonmedical benefits include energy production and various industrial applications such as in density-moisture gauges used in highway construction and in non-destructive testing by industrial radiography. In New Mexico, over 200 radioactive material licenses are currently active. In addition, about 2,000 x-ray machines are registered by the State. The licensing of radioactive material and the registration of radiation-emitting machines allow the beneficial use of these sources of radiation under proper regulatory control. Under controlled conditions, the benefits of using radiation are likely to outweigh the risks.

Jobs in Radiation Protection

Health Physics
Health physics, or radiological health, is the science that is concerned with the recognition, evaluation, and control of health hazards from radiation. This professional field cuts across various scientific disciplines including basic physical, life, and earth sciences. The health physics profession is devoted to the protection of man and his environment from potential radiation hazards, while at the same time making possible the enjoyment of the numerous benefits resulting from the use of radiation. The wide spectrum of knowledge required of the health physicist makes the profession both challenging and rewarding. Health physicists work in research institutions, medical facilities, governmental regulatory agencies, nuclear power plants, industries designing and producing radiation-detection instruments, and universities.

Rio Grande Chapter of the Health Physics Society
Most members of the Rio Grande Chapter belong to the national Health Physics Society, an organization of over 4,500 professionals dedicated to the development of scientific knowledge and practical means to protect man and his environment from the harmful effects of radiation. The Health Physics Society is committed to ensuring that radiation is used prudently and that radiation exposures are as low as practical. In recent years the national society has engaged in a broad program of attempting to further public understanding of the effects of radiation.

Lesson plan for 5th grade students on radiation--relates to APS Standard 3 properties and changes of matter.

Glossary

ALPHA [Back]	A particulate type of radiation that consists of positive charged particles emitted by atoms of elements. Alpha radiation can just penetrate the surface of the skin but may be hazardous if taken into the body by inhalation or with food or water.
ATOMS [Back]	Smallest unit of of a chemical element. It has a nucleus and one or more orbiting electrons.
BETA [Back]	A particulate type of radiation that consists of electrons. It is more penetrating then alpha radiation.
ELECTRON [Back]	A negatively charged particle that orbits the nucleus of an atom.
ELEMENT [Back]	The simplest form of a chemical. Elements are made of identical atoms. Gold and silver are examples of elements.
GAMMA [Back]	A type of radiation that is pure energy and can be very penetrating. Gamma rays and x rays are similar. However, gamma rays are the products of radioactive atoms while x-rays are produced in man-made machines that are typically used in medical or dental examination.
HALF LIFE [Back]	Radioactive Decay: Spontaneous change in an atom by emission of of charged particles and/or gamma rays; also known as radioactive disintegration and radioactivity.
NEUTRON [Back]	An atomic particle with no electrical charge.
NUCLEAR POWER REACTORS [Back]	An electrical generating facility using a nuclear reactor as its power (heat) source. The main difference between a nuclear power plant and other kinds of power plants (coal, oil, gas) is that at a nuclear power plant, the heat used to make the steam is produced by splitting atoms.
PROTON [Back]	An atomic particle with a positive charge.
RADIATION [Back]	Transmission of energy though space or any medium as waves or particles. Also known as radiant energy.

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