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
Period 7 element Period 7 element A period 7 element is one of the chemical elements in the seventh row (or "period") of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered.