Polonium subjects were chosen because experimenters wanted persons who had not been exposed to polonium either through work or accident. All subjects had incurable diseases. Excretion of polonium was followed, and an autopsy was conducted at that time on the deceased patient to determine which organs absorbed the polonium. Patients' ages ranged from 'early thirties' to 'early forties'. The experiments were described in Chapter 3 of Biological Studies with Polonium, Radium, and Plutonium, National Nuclear Energy Series, Volume VI-3, McGraw-Hill, New York, 1950. Not specified is the isotope under study, but at the time polonium-210 was the most readily available polonium
Isotopes of polonium per second as 5 grams of Ra. A few curies (1 curie equals 37 gigabecquerels) of Po emit a blue glow caused by excitation of surrounding air. A single gram of Po generates 140 watts of power. Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance, a Po heat source was also in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components