Influence of inhaled Ca-DTPA on the long-term effects of inhaled Pu nitrate

Male Wistar rats were exposed, nose-only, to a 239Pu nitrate aerosol generated from 0.27 N nitric acid solution. The initial lung burden was 70 +- 18 nCi 239Pu. Twenty days later, and at five subsequent weekly intervals, the rats were similarly exposed to Ca-DTPA aerosols (3 mg Ca-DTPA/rat/exposure) or to sham Ca-DTPA. Groups of animals were sacrificed at 30, 60, 100 and 150 days after Pu inhalation to determine possible effects of Ca-DTPA therapy, and Pu retention and distribution kinetics for dosimetric purposes. Appropriate control animals exposed to nitric acid aerosols, nitric acid in combination with Ca-DTPA or sham Ca-DTPA, and non-treated controls, completed the study. Delayed inhaled chelation therapy had little effect on Pu clearance from the lung. However, eventual deposition in skeleton and liver was decreased by 20% (significance level = 0.05). Treatment with Ca-DTPA had no significant effect on weight gain or survival or on the incidence of lung and bone tumors induced by plutonium inhalation. Radiation dose-tumor response data are presented which illustrate the wide range in accumulated radiation dose in these animals due to variations in initial lung burden and life-span subsequent to Pu inhalation. (author)