Cobalt-60 Nuclear Generating Station. The cobalt targets are substituted here for a small number of fuel assemblies. After entering a living mammal (such as a human being), some of the is excreted in feces. The remainder is taken up by tissues, mainly the liver, kidneys, and bones, where the prolonged exposure to gamma radiation can cause cancer. Over time, the absorbed cobalt is eliminated in urine. Cobalt is an element used to make steel. Uncontrolled disposal of in scrap metal is responsible for the radioactivity found in several iron-based products. In August 2012, Petco recalled several models of steel pet food
Chemical element isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82. Of the 80 elements with at least one stable isotope, 26 have only one single stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes that occur for a single element is 10 (for tin, element 50). The mass number of an element, "A", is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes