Strontium-90
Strontium is a naturally occurring element found in rocks, soil, dust, coal, and oil. Strontium-90 is a radioactive isotope of strontium (Sr) with a half-life of 28.8 years. Strontium-90 is a product of nuclear fission and is obtained during nuclear reprocessing of spent nuclear fuel and is a beta-emitter. Strontium 90 is extensively used in medicine and industry. Strontium-90 is a radioactivity hazard and is linked to cancers. (L1135, L1839)