A study on the behaviour of experimentally inhaled plutonium in rats and fallout plutonium in human organs

The behaviour of plutonium in the body of rats following the inhalation of plutonium nitrate aerosols was investigated. The experiment showed that only a few per cent of the retained plutonium in the lung was transferred to other parts of the body within several days after inhalation. Eighty days after inhalation, the plutonium lung burden had decreased to less than 70% of the total body burden and the skeletal burden had increased to about 20% of the total body burden. The half-time value for the retention of plutonium in rat lungs was about 77 days. It should be noted, however, that amount of plutonium in the liver only reached a few per cent of the total body burden. The activity ratio of 241Am to total α-activity in rat lungs was 11.8% immediately after inhalation, but decreased with time to 11.0% after 14 days, 9.5% after 32 days and 8.4% after 80 days. These results show that americium is removed from the lung more rapidly than plutonium. Plutonium produced by nuclear weapon testing has been taken into the human body via ingesion and inhalation and has accumulated in various organs. The concentrations of sup(239.240)Pu in various organs of Japanese subjects were measured. It was noted that the concentration of sup(239.240)Pu in the gonads, especially the ovaries, was relatively high. Measurements of the plutonium content of daily diet in Japan showed that the plutonium deposition in human organs originated more from inhalation of air than from ingestion of food. (author)