Reducing the radiation dose from inhaled americium-241 using continuously administered DTPA therapy

Accelerating the removal of a radionuclide from the body of a contaminated individual is the only available approach to decreasing the radiation dose from such exposures. In this study, continuous infusion of a chelating agent, DTPA, was given to dogs that had inhaled a moderately soluble aerosol, 241 AmO2, not only to accelerate clearance of the radionuclide from the lung but also to prevent its deposition in liver and bone. Treatment was begun with an intravenous injection of CaDTPA 1 h after exposure, and was continued for 64 days after exposure by implanting subcutaneously osmotic pumps containing ZnDTPA at 1 day after exposure. The results showed that the infusion therapy was effective in blocking the translocation of 99.5 per cent of the 241Am that would have been deposited in liver, and 98.3 per cent of the 241Am that would have been deposited in bone. This result was significantly better than the result achieved using repeated intravenous injections of DTPA, the method of treatment in current use for actinide contamination cases.