The Collaborative International Dictionary
Strontium-90 \Strontium-90\ A radioactive isotope of strontium produced by certain nuclear reactions, and constituting one of the prominent harmful components of radioactive fallout from nuclear explosions; also called radiostrontium. It has a half-life of 28 years.
Wiktionary
n. (context isotope English) The radioactive isotope of strontium, (nuclide 90 38 Sr), that is present in the fallout from nuclear explosions and, being chemically similar to calcium, is accumulated in the bones
Wikipedia
Strontium-90 () is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.8 years. It undergoes β decay into yttrium-90, with a decay energy of 0.546 MeV. Strontium-90 has applications in medicine and industry and is an isotope of concern in fallout from nuclear weapons and nuclear accidents.
Usage examples of "strontium-90".
Taken in large amounts, strontium-90 can cause leukemia or bone cancer.
This included Strontium-90 and Cesium- 137 and possibly an iodine isotope.