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
2019 redefinition of SI base units values associated with the following constants of nature: The seven definitions above are rewritten below with the derived units (joule, coulomb, hertz, lumen and watt) expressed in terms of the seven base units (second, metre, kilogram, ampere, kelvin, mole and candela), according to the updated 9th edition of the SI Brochure (2018). In the list that follows, the symbol sr stands for the dimensionless unit steradian. As part of the redefinition, the international prototype kilogram was retired and definitions of the kilogram, the ampere, and the kelvin were replaced. The definition of the mole was revised. These changes have the