Influence of radiation-dose pattern from inhaled beta--gamma-emitting radionuclides on canine peripheral lymphocytes
As part of studies assess the biological hazards associated with inhaled radionuclides, periodic hematologic evaluations were performed on beagle dogs given a single nose-only exposure to aerosols of beta--gamma-emitting isotopes. The physical form and specific radionuclides selected produced radiation-dose patterns representative of those which might be encountered in the event of human accidental exposures. Dogs received graded lung burdens of either $sup 90$Y, $sup 91$Y, $sup 144$Ce, or $sup 90$Sr, each in fused clay. Differences in the effective half-lives of these radionuclides resulted in a spectrum of cumulative radiation doses to lung delivered at a variety of dose rates. Since the form in which the radionuclides were inhaled was relatively insoluble, the lung and intrathoracic tissues represented the primary recipient of the dose. Regardless of the effective half-life of radionuclide retention, a dose-related depression of peripheral lymphocytes was observed at various times after inhalation exposure. The time at which maximum depression and subsequent recovery occurred, however, was most directly related to the effective half-life of the radionuclide. Of special interest was the persistence of lymphopenia through 2$sup 1$$/$$sub 2$ years after exposure to $sup 144$Ce and $sup 90$Sr in fused clay where, other than tracheobronchial lymph nodes, the lymphoid tissue received very little radiation dose. The possible mechanisms responsible for lymphocyte depression from these various radiation-dose patterns are discussed. (auth)
- Research Organization:
- Lovelace Foundation for Medical Education and Research, Albuquerque, NM; Battelle Pacific Northwest Labs., Richland, Wash. (USA); USAEC Division of Biomedical and Environmental Research, Washington, D.C.
- NSA Number:
- NSA-33-023562
- OSTI ID:
- 4052613
- Report Number(s):
- CONF-740930--
- Country of Publication:
- United States
- Language:
- English
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