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Radiation Protection

Radionuclide Basics: Technetium-99

TechnetiumTechnetium (chemical symbol Tc) is a silver-gray, radioactive metal. It occurs naturally in very small amounts in the earth's crust, but is primarily man-made. Technetium-99 is produced during nuclear reactor operation, and is a byproduct of nuclear weapons explosions. Technetium-99 can be found as a component of nuclear waste.

Technetium-99m is a short-lived form of Tc-99 that is used as a medical diagnostic tool. It has a short half-life (6 hours) and does not remain in the body or the environment for long.

Type of Radiation Emitted:  Half-lifeHelpHalf-lifeThe time required for half of the radioactive atoms present to decay or transform. Some radionuclides have half-lives of mere seconds, but others have half-lives of hundreds or millions of years.
Beta Half-Life
Beta ParticlesHelpBeta ParticleA form of particulate ionizing radiation made up of small, fast-moving particles. Some beta particles are capable of penetrating the skin and causing damage such as skin burns. Beta-emitters are most hazardous when they are inhaled or swallowed. Technetium-99: 210,000 years
Technetium-99m: 6 hours
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Technetium in the Environment

Air, sea water, soils, plants and animals contain very low concentrations of Tc-99. Because of its long half-life, Tc-99 remains in the environment for an extended period of time.

Organic matter in soils and sediments slow the transport of Tc-99. In the presence of oxygen, plants readily take up technetium compounds from the soils. Some plants such as brown algae in seawater are able to concentrate Tc-99. Sea animals can also concentrate Technetium-99 in their bodies.

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Technetium Sources

Tiny amounts of Tc-99 are part of the environment and are found in food and water. Higher amounts may be found close to contaminated facilities such as federal weapons facilities or nuclear fuel cycle facilities.

Exposure to technetium from the environment is unlikely. Most human exposure to technetium comes from the intentional use of Tc-99m in nuclear medicine.

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Technetium and Health

Technetium-99 can pose a health risk when it enters the body. Once in the human body, Tc-99 concentrates in the thyroid gland and the gastrointestinal tract. However, the body constantly gets rid of Tc-99 in feces. As with any other radioactive material, there is an increased chance that cancer or other adverse health effects can result from exposure to radiationHelpradiationEnergy given off as either particles or rays..

The Tc-99m used in medical diagnostics has a short, six-hour half-life and does not remain in the body.

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