RMI Nuclear Justice Documents

t 424 v4 Ae: WV x FF, a tivity tn larger particles collected on fall-out trays at the same sites. The mean size of particles (mean diameter on a weight basis) from such air samples has averaged approximately 30 p, and few particles have exceeded 50 yu, by optical measurement, Values for radioactivity per cuble meter of air obtained from low- and high-volume air samplers include parti- hye cles of respirable size (0.1 to 5.0 ;:). However, it is apparent that the amount of radioactivity . Any Fi if. re Pe ‘ . |A~» Ned 4 in this small size range is undoubtedly a niinute fraction of the activity in the total alr sample. Furthermore, studies by the Army Chemical Corps"' have shown that only one out of approxt- mately each 10,000 particles found in air samples is radioactive. The report by G. M. Dunning," summarizing the results of all continental atomic tests to date, states that in no instance did air-borne contamination exceed 1.3 yc/nyfor any 24-hr pertod and that under such conditions tne calculated dose to the lungs would be only {30 mrep. In view of these data, there {s an obvious need for establishment of more practical criteria regarding health hazards associated with air-burne contamination. Thus, from physteal considerations alone, it fs apparent that the danger from inhaling radioactive fall-out particles in significant amounts during the first few days postdetonation is impossible without simultaneously being subjected to at least 100 times as much external beta- gammaradiation exposure, Actually, the potential acute inhalation hazard ts further reduced by the physiological-safety factors previously listed, For example, if one were inhaling atrborne particles in the 0.1- to 50.0-» size range, the 5- to 50- size particles would inittally be trapped In the nose and upper respiratory tract. If these particles were insoluble, they would ' La e. be carried rapidly to the throat, swallowed, and eliminated in the feces within a few days, * “4 f ze: ms. ee : eventually removed by phagocytic action but at much slower rates (weeks to months), These fine particles (0.1 to 2.0 j1), however, account for only a minute fraction of the total inhaled radioactivity, Thus it is apparent, from both physical and physiological considerations, that ‘ le Le eos co towing an atomic explosion would constitute a negligible quantity, percentagewise, when compared with the corresponding external gamma-ray and/or beta-ray exposure during this period. These conclusions are further subs(anttated by the tesults of controlled laboratory inhalation studies, plus the field data presented from head exposures of rabbits to radioactive fall- any possible internal hazard from inhalation in nuclear warfare during the first few days fol- PROS SME r al , If . Ns 5 4 “YY . ipod Furthermore, the great majority (85 to 90 per cent) of 0.1- to 5.0-p particles wouldbe distributed initially in the trachea, bronchi, and bronchloler. This material retained in the ciliated air passages is removed upward rapidly by cillary action and likewise swallowed and eliminated in the feces. The 10 to 15 per cent of material deposited in the lung alveoli ts also tA C ; 7. : fe if * wat va . *S : out material at near (7-mile) and distant (106-mile) stations, as follows: 1. Radioassay of lung specimens from animals exposed (head only) to fall-out at both the 7- and 106-mile stations gave entirely negative results when measurements were made 6 to 21 days later. However, the specimens of intestines in the same animals still showed definite, we omer m1 2 although small, amounts of radioactivity. From these field data it Is not possible to quantitate the relative local hazard to pulmonaryvs gastrointestinal tissues; however, the field results showed that the intestinal organs accumulated the bulk of the retained radioactivity, even after inhalation exposures performed in a manner designed to minimize actual ingestion of radio- = ~~ 2. The negative findings in thyroid tissue indicate that 1 in absorbable form from either the lungs or gastrointestinal tract was not present in significant amounts. However, it is pos- vat at. “2 haled materials because urine samples collected during the first 24 hr contained measurable amounts of isotopes having a shorter half life than that of mixed fission products, 3. In contrast to these essentially negative findings for internal radiation exposure, the “+ ously, were 14 to 32 r at the 7-mile-are stations and 1.5 to 4.2 r at the (06-mile-are stations, * as measured by both film and chemical methods of dosimetry, ore ‘¢t 7 ‘ mh os times) of radioactive particles in the intestinal (racts than are retained in the resptratory organs following an acute inhalation exposure, Under fleld conditions, where the greatest amount of radioactivity ts found in the larger particles, the acute radiation damage from inhalation, if any, is far more lkely to invelve the intestinal organs than those of the respiration ”¢ oe 4 : ‘pp Bs i: : sible that 1", or some other soluble and absorbable isotope, may have been present in the in- integrated doses of external gamma radiation, to which the animals were exposed simultane- As in the laboratory studies," animals retain far greater amounts (factors of 10 to 150 21 LaAUer. ” SFA 2. - <~ me ke “se “3 “f, fa f a “ossf e “ A . te ¥ at < i ‘ 4 t active materials, ‘ 4 a Tf ~~ “ e