Radioisotope Brief: Strontium-90

Half-life: 29.1 years

Mode of decay: Beta radiation

Chemical properties: Chemically reactive; can create halide, oxide, and sulfide compounds

What is it used for?

Because Sr-90 generates heat as it decays, it is used as a power source for space vehicles, remote weather stations, and navigational beacons. It also is used in industrial gauges and medically, in a controlled manner, to treat bone tumors.

Where does it come from?

Sr-90 is produced commercially through nuclear fission for use in medicine and industry. It also is found in the environment from nuclear testing that occurred in the 1950s and 1960s and in nuclear reactor waste and can contaminate reactor parts and fluids.

What form is it in?

Sr-90 is a soft metal. It can be present in dust from nuclear fission after detonation of nuclear weapons or a nuclear power plant accident.

What does it look like?

In its pure form, Sr-90 is a soft, shiny silver metal, but it quickly changes to yellow when exposed to air.

How can it hurt me?

Sr-90 can be inhaled, but ingestion in food and water is the greatest health concern. Once in the body, Sr-90 acts like calcium and is readily incorporated into bones and teeth, where it can cause cancers of the bone, bone marrow, and soft tissues around the bone.

Sr-90 decays to yttrium 90 (Y-90), which in turn decays by beta radiation so that wherever Sr-90 is present Y-90 is also present. Because of the beta radiation, Y-90 poses a risk of burns to the eyes and on the skin from external exposure.

For more information on Sr-90, see the Public Health Statement by the Agency for

Toxic Substances and Disease Registry at, or visit the Environmental Protection Agency at

For more information on protecting yourself before or during a radiologic emergency, see CDC’s fact sheet titled “Frequently Asked Questions (FAQs) About a Radiation Emergency” at, and “Sheltering in Place During a Radiation Emergency,” at

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