锶-90 (Strontium-90) is a radioactive isotope of the element 锶 (strontium). It is produced during nuclear fission processes, such as those occurring in nuclear reactors and atomic bomb explosions. With a half-life of about 29 years, it decays into 锶-90 (yttrium-90), emitting beta particles that can be harmful to living organisms. Due to its chemical properties, 锶-90 can replace calcium in bones, leading to potential health risks, including bone cancer and leukemia. It is often monitored in environmental studies, especially after nuclear accidents, to assess contamination levels and their impact on human health and ecosystems.