What Is Cesium-137?

The EPA says cesium-137 is produced by nuclear fission for use in medical devices and gauges, and is also one of the byproducts of nuclear fission in nuclear reactors and nuclear weapons testing. It says larger amounts are used in medical radiation therapy devices for treating cancer and in industrial gauges that detect the flow of liquid through pipes.

The CDC says people are exposed to some cesium-137 every day because amounts remain in the environment from weapons testing in the 1950s and 1960s, but that it is dangerous in the large, concentrated amounts found in radiation therapy units and industrial gauges. It says external exposure to large amounts can cause burns, acute radiation sickness and even death, and that exposure can increase cancer risk because of high-energy gamma radiation. The CDC says Prussian blue traps radioactive material in the intestines and removes it through bowel movements, and that it can only be obtained through a doctor.

An International Atomic Energy Agency report says that on 13 September 1987, a shielded, strongly radioactive cesium-137 source was removed from its protective housing in a teletherapy machine in an abandoned clinic in Goiania, Brazil, and later ruptured, and that many people received large radiation doses from external and internal exposure. It says the accident resulted in the deaths of four people, radiation injuries to many others and radioactive contamination of parts of the city.