title: Neptunium-237 inhalation in rats.
abstract: Groups of rats were exposed to aerosols of 237Np nitrate to determine clearance rates, retention and distribution at various intervals after inhalation. Initial lung burdens (ILB) after 237Np inhalation by three treatment groups were 0.12, 0.19 and 0.37 mu Ci/kg, respectively. Radiochemical analyses of animals killed at 4, 8, 14, 28 and 90 d, as well as data for others maintained until they became moribund, showed that their lung clearance followed a three-compartment model, clearance half-times for which were 1, 35, and 10,000 d, respectively. Only 3% of the ILB was retained after 90 d; 12% of that burden had translocated to the skeleton at 750 d; the half-time for skeletal retention was 2500 d. A single tumor was the only malignancy detected in the lungs of the 35 animals allowed to survive the early phase of the study.
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D005260:Female; D009405:Neptunium / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: D000336:Aerosols; D009405:Neptunium