Early patterns of pulmonary cellular response in Syrian hamsters following plutonium inhalation

Syrian hamsters were exposed as young adults (84 days of age) to aerosols of 239PuO2 to obtain graded initial lung burdens (ILB) which ranged from levels calculated to result in early deaths from radiation pneumonitis and pulmonary fibrosis down to a level equivalent on a body weight basis to the currently accepted maximum permissible lung burden for man. The activity median aerodynamic diameter of the aerosol was 2.0 μm with a geometric standard deviation of 1.5. Early patterns of pulmonary cellular response are reported for 37 hamsters in the group that had the highest lung burdens (380 nCi, geometric mean) and survived for 66 to 279 days with a mean survival of 95 days. All of these animals exhibited marked pulmonary inflammatory changes at death