Radionuclide Basics: Technetium-99
Technetium (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.
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.
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.
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 radiationradiationEnergy 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.