4, Critical Health Effects: It is widely recognized that inhaled insolubie alpha emitting particles deposited in the lung are, in part, translocated ve via the phagocytic action of uacropheges co the lymph nodes and to other _— sites in the reticuloendothelial. system, and also via blood leucocytes to ° the liver, spleen and tone marrow. . " Recent experiments with inhaled piutonium meke it evident that the pattern and rate of translocation of plutonium from the lung to other sites is highly dependent on particle size and specific activity, with more rapid transport of the smaller and more active particles. Thus, it is far from obvious whether the lung, - lymph nodes, liver, bone or other organ, or fraction thereof, should be taken as the critical organ or critical tissuesite. It has long been known that those tissues in which there is more . active cell division suffer the earliest and most severe radiation damage effects, and that this includes the blcod forming cells in lymphatic giands and in bone narrow (16,377 5 cheffects include the destruction of rapidly 4 multiplying cells that produce the blood platelets which assist in the me ot control cf blood clotting. Similarly the population of leucocytes is reduced with a corresponding reduction in resistance to disease. These . effects plus tile accompanying chromosome structural changes can give rise - to the earlier incidence not only of cancers, but the whole pattern of wtb diseases of the cardiovascular and renzl systems ‘>/ 938) y Let us review the mounting evidence which suggests that inhaled ae . insoluble alpha emitting particles may be the agent of atherosclerosis and thus give rise to an increased risk of death by early coronaries and a strokes. atherosclerosis is reported to be present in every instance of partial or complete arterial occlusion and every case of coronary thrombosis ITCea TRU RTDAE K ore gay el I is ‘i? (39) ae .