a A cell whose nucleus is intercepied by the path of such a par- ticle suffers sufficient injury that its capacity for cell division is usually r Jost (Bary eedcen, A.W., 1962 and Blocre, W., 1959). i ween eee One . millionth of a gram injected intradermally in rice has caused cancer a similar amount injected into the blood system ' of dogs has induced a substantial incidence of Bone cancer lays, C.W., et al., 1947), because of plutenium's tendency to seek bone tissue. | Fortu- nately the body, maintains n a relatively effective barrier against the entry | ‘of plutonium into the blood system. | . Also, because of the short range of the emitted helium nuclei, the radiation from plutonium deposited on the surface of human skin does not usually reach any relevant tissue. t f h | Unfor- tunately the lung is more vulnerable. ? Before I describe why this is, I'd like to say something about the TTS Eve Te < prenes An aerosol is physically like cigarette smoke, or fog, or cement dust. "Because of their small size, the particles “comprising an aerosol remain suspended in air for long periods of time. . Se, CSTE TT ae If an aerosol is inhaled, then, depending on its physical characteristics, it: y “may be deposited at different sites in the respiratory tree (Health_Physics, 1966). Larger aerosol sizes are usually removed by turbulence in the nose . Lo f particles deposited in the bronchial tree are cleared upward in hours by the clliated mucus blanket that covers the structure. This clearance system 4 @ucs nat panstrate into the deep respiratory structures, the alveoli, where tie basic exygena-carbon dioxide exchanye of the lung lakes pluce. Srnaller eS ~ es eer ee ee ee ee Se ne rene ee characteristics of an aerosol. Oe we ere eemm te Parr aren we .. . * ee ie ee eee ee eo - Oe eee eee (lises, t7.. et al., 1947); eetraeee eet The cancer inducing potential of plutonium-is well known. ep Oncere Ser ee Me Oe ee 6 emer ee oe ge eee A ont ewee eee ewes ee ee Be a eee eee = me ey sete rr ee ee ememe eee meee toot ae tew tn wees Aw wees vate me ee ee ee eee sale Oe ted ae Bee eea a “Nps tne wpe weer Rees wanes mF te 1/10 of that. &% br dug A os tr oem et rete Ree eet ome ' C. .