Strontium unit Strontium unit The strontium unit is a unit used to measure the amount of radioactivity from strontium-90, a radionuclide found in nuclear fallout, in a subject's body. Since the human body absorbs strontium as if it were calcium, incorporating it into the skeleton, its presence is very common. One strontium unit is equal to one picocurie from strontium-90 per gram of calcium (37 becquerels per kilogram) in the subject's skeleton. The United States National Academy of Sciences holds that the maximum safe measure of strontium-90 in a person is one hundred strontium units (3700 Bq/kg). The average American is estimated
Radioactivity in the life sciences ). Radioactivity in the life sciences Radioactivity is generally used in life sciences for highly sensitive and direct measurements of biological phenomena, and for visualizing the location of biomolecules radiolabelled with a radioisotope. All atoms exist as stable or unstable isotopes and the latter decay at a given half-life ranging from attoseconds to billions of years; radioisotopes useful to biological and experimental systems have half-lives ranging from minutes to months. In the case of the hydrogen isotope tritium (half-life = 12.3 years) and carbon-14 (half-life = 5,730 years), these isotopes derive their importance from all organic life containing hydrogen and