Iron Isotopes are mainly used in nutritional studies, with Fe-57 and Fe-58 being the two most commonly used Fe isotopes. Studies have included iron-loss by human adolescents, conditions for effective iron absorption, interventions for anemia and genetic iron control. The Fe-54 isotope is used for the production of radioactive Fe-55 which in turn is used as an electron capture detector and in X-ray fluorescence. Fe-56 can be used for the production of radioactive Co-55 which is used as a tumor seeking agent in bleomycin.