Unethical human experimentation in the United States
In 1953, the AEC ran several studies at the University of Iowa on the health effects of radioactive iodine in newborns and pregnant women. In one study, researchers gave pregnant women from of iodine-131, in order to study the women's aborted embryos in an attempt to discover at what stage, and to what extent, radioactive iodine crosses the placental barrier. In another study, they gave 25 newborn babies (who were under 36 hours old and weighed from ) iodine-131, either by oral administration or through an injection, so that they could measure the amount of iodine in their thyroid glands, as iodine would go to that gland.
Iodine-125
Iodine-125 is commercially available in dilute NaOH solution as I-iodide (or the hypohalite sodium hypoiodite, NaOI) . The radioactive concentration lies at 4 to 11 GBq/ml and the specific radioactivity is >75GBq/µmol. The chemical and radiochemical purity is high. The radionuclidic purity is also high; some I (t=13.1d) is unavoidable due to the neutron capture noted above. The I-126 tolerable content (which is set by the unwanted isotope interfering with dose calculations in brachytherapy) lies at about 0.2% atom fraction of the total iodine (the rest being I-125).