DEPOSITION OF PB-214 AND NUCLEAR ABERRATIONS IN THE RESPIRATORY-TRACTOF RATS AFTER EXPOSURE TO RADON PROGENY UNDER DIFFERENT AEROSOL CONDITIONS

The aim of this work was to relate Pb-214 deposition within the respir atory tract of the rat to aerosol characteristics during exposure to r adon and its progeny. Two different exposure conditions were studied: static, without air recirculation with a low unattached fraction of ra don progeny (fp similar to 10%); and dynamic, with continuous air reci rculation (fp>80%). Deposition was estimated by measuring Pb-214 reten tion in nasopharynx and lungs at the end of a 3-h exposure using gamma spectrometry. The deposition of Pb-214 in the pulmonary region was th e same in the two exposure conditions. By contrast, nasopharynx deposi tion was 5 times higher under dynamic than under static exposure. The dose delivered to the deep lung was estimated by micronuclei scoring i n alveolar macrophages extracted by pulmonary lavage. For a similar cu mulative dose delivered under static or dynamic conditions, a similar micronuclei index was measured, 1.22% +/- 0.26 and 1.47% +/- 0.42, res pectively, 8 d after exposure. These results suggest that the unattach ed fraction did not influence radon progeny deposition and the resulti ng delivered dose in the deep lung of the rat. Copyright (C) 1996 Else vier Science Ltd.