Repeated inhalation exposure of beagle dogs to aerosols of 239PuO2

This experiment was initiated to study the biological behavior and long term effects of repeated inhalation exposures to 239PuO2 particles compared with those seen in Beagle dogs that received a single exposure as young adults. A design study has been carried out to determine levels of exposure and exposure schedules which are desirable for this study. The design study involved the development of a model to use with high-level single-exposure data to predict low level repeated exposure probabilities of lung tumors. A sensitivity analysis on the duration of the exposures, the time between exposures, the relative magnitude of each exposure and the exposure level was carried out. A block type experiment has been designed in which Beagle dogs are being exposed via inhalation to a monodisperse aerosol of 0.75 μm AD 239PuO2 particles at either 0.1 μCi or 0.01 μCi at half-year intervals for ten years. Also included is a group which were exposed only once to 0.1 μCi of 239PuO2 to serve as a basis for comparison. The first exposure has been completed in all of these dogs