differences between the healthy and the malignant celis of each organ could shed ecme lignt on this important questicn. _ It alao is observed that the relative significance of chemical agents, viruses and radiation in the incidence of human cancer is not known. Details of the mechanisms of cancer induction by chemical agents and viruses also are poorly understood. And the proposed chemical carcinogens in cigarette smoke and in polluted urban environments have not been demonstrated to be carcinogenic at the low concentrations involved. For all of these reasons it is deemed likely that radiation, and alpha radiation in particular, ; maybe the principal agent of human cancer. In view of such a possibility, it is very disturbing to note that the U.S. National Cancer Institute, now spending about one-half billion dollars per year on cancer research, has completely-neglected the field of radiation induced cancer research. Published evidence (39-45) indicates that atherosclerosis is a tumor of the artery wall and that the alpha activity at the calcified plaque ‘site is likely to be the mutagenic agent. If so the major causes of death in the general population - coronary disease, other cancers, and strokes tay in large part be attributable to internal alpha emitters from natural and pollutant sources. If so, fallout plutonium and alpha emitting . contaminants mustalready be contributing to increased health risks and life shortening to the general public. Cigarette smoking causes increased risks of early coronaries, lung cancer, cancers at other sites, and other health effects (46) » with about 15 years reduction in life expectancy for those who . regularly smoke 2 packs of cigarettes per day or more (attributable to lung burdens of only about five picocuries of 7!°Po in excess of that of nonsmokers). Fallout levels from past atmospheric nuclear tests have given rise to plutonium organ burdens of ~0.5 pCi/kg of lung tissue and ~0.7 pCi/kg of liver tissue in the general public ©) | Although these levels are only Ss i