Report to the Scientific Director, Operation Castle, Project 4.1 - Addendum, Nature and Extent of Internal Raioactive Contamination of Human Beings, Plants, and Animals Exposed to Fallout

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OFFICIAL USE ONLY. Report to the Scientitic Director Nature and Extent of Internal Radioactive Human Beings, Plants, Exposed to Fallout Naval Radiological Defense Laboratory Sac Francisco, Calif. Naval Medical Research Institute

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The first instance of exposure of humanbeings to mixed fission products occurred as a result of the contaminatingdetonation of 1 March 1954. Beta activity in the urine of these exposed humanbeings indicated significant internal contamination from the ingestion and inhalation of fallout material. The body burden of the group of humanbeings with the greatest internal contaminationwas of the order of the maximum permissible concentrations for the Few of the fission products present in the environment were readily absorbed by the bloodstream from the lungs and the gastrointestinal tract. Most of those radioelements that gained entry into the body had short radiological and biological lives, and thus the levels of activity in the tissues of the body were relatively low. The concentration of radioisotopes at 6 months postdetonation was barely detectable in the urine of most of the exposed individuals. The human body burden of individual radionuclides was estimated from radiochemical analysis of the human urine and of the tissues and urine of animals from Rongelap. The mean body burdens of the radionuclides in the Ailinginae group were approximately one-half those of the Rongelap group, and the mean body burdens of the American group were about onefourth those of the Rongelap group. Radioiodine is probably the most hazardous internal radioemitter at early times after exposure. Of the longer lived fission products Srs8is the most abundantand presents the greatest potential hazard in this particular group. Oral administration of calcium EDTA, beginning seven weeks postdetonation, to a representative group of individuals from Rongelap increased the rate of excretion of activity. However, the decrease of the body burden was insignificant since the excretion rate was very low at this late time. High levels of activity were found in water and on the external surfaces of plants. The contamination of the internal portions of fruits and vegetables was small; however, high levels of contaminationwere found in the coconut tree sap. Of the individual radionuclides, Sra8, because of its high solubility and relatively long radioactive half life, was probably the isotope of greatest potential hazard in the environment. Gross beta activity of urine and tissue samples of animals indicates significant internal contamination of all the animals. The level of internally deposited radioisotopes in the pigs from Rongelap was ten times the amount in humanbeings from the same area. Studies of animals provided direct data on the nature and distribution of the contamination in the tissues of the body. Over 90 per cent of the activity in the body of animals was localized in the skeleton. The pattern of deposition of the fission products in the skeleton seen in autoradiographs was similar to that of alkaline earths. The fish and clam had a much lower concentration of the alkaline and rare earths and a body burden considerably higher than that of the land animals. Since fish form a large staple item in the diet of the island populations, this high level of contamination is of considerable importance. Studies made on egg production of contaminated hens gave no evidence of any radiation effect. The production rate for eggs was normal, and the eggs produced were also normal.

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The extraordinary ability of fowl to mobilize calcium in shell formation resulted in the presence of very high activity in the shells of the first few eggs. The activity was associated with the fission products of the alkaline earth group. Fertility of the hens and hatchability of the eggs produced by the mating of contaminated roosters and hens showed no radiation effects. The baby chicks hatched from these eggs are growing normally, and the amount of radioactivity in their tissues is barely detectable. In the 6-month postdetonation period, neither significant gross changes nor pathological changes, which could definitely be ascribed to radiation, were detected in any of the animals Analysis of the internal contamination in human beings indicates that the dose to the tissues of the body was near but did not exceed the maximum permissible dose levels. The activity fixed in the body decreased rapidly as a function of time. The contribution of the effects of internal contamination to the total radiation response observed appears to be small on the basis of the estimated body burden of the radioelements. In view of the short half life of the most abundantfission products in this situation, the possibility that chronic irradiation effects will occur is quite small.

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Although it is impossible to acknowledge all the assistance rendered by the many individuals at the Naval Radiological Defense Laboratory and other laboratories that contributed to this project, the contributions of outstandingnature can be mentioned here. We gratefully acknowledge the assistance of the following people: made available all necessary facilities of the laboratory to pursue the many diversified aspects of this problem. Dr. E. L. Alpen assisted in the administration of early phases of this project and assisted in the pathology studies conducted. H. H. Hechter performed the statistical analyses of the data. Miss C. Jones prepared autoradiographs of animal tissues. Dr. W. P. Norris, Argonne National Laboratory, made autoradiographs of animal tissues. Dr. R. Reed performed the microscopic pathological study of animal tissue. Institute, assisted in the collection of the biological samples. C. A. Sondhausassisted in the mathematical calculations of the external and internal dose to the animals. Dr. E. R. Tompkins made available the facilities of the Chemical Technology Division and provided technical advice on the radiochemical aspects of the project.

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1.2 General Nature of Internal Radiation Toxicity . , . CHAPTER 2 INTERNAL CONTAMINATION IN HUMAN BEINGS . 2.2 Results and Discussion ....... 2.2.1 Beta Activity of the Urine ..... 2.2.2 Radiochemical Analysis of the Urine: Estimate of 2.5 Summary and Conclusions ....,. CHAPTER 3 INTERNAL CONTAMINATION IN ANIMALS . . 3.2 Results and Discussion ....... 3.2.3 Radiochemical Analysis of Tissues and Excreta . 3.5 Egg Production in Chickens ...... 3.6 Fertility and Hatchability Studies in Chickens . . . 3.7 Iuternal Radioactive Decontamination Studies in Chickens 3.8 Summary and Conclusions ....... CHAPTER 4 ENVIRONMENTAL STUDIES ..... Chemical and Physical Characteristics of Fallout Material Radiochemical Analysis of Food, Water, and Soil . .

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4.2.2 Results and Discussion ..... 4.3 Summary and Conclusions ..... CHAPTER 3 INTERNAL CONTAMINATION IN ANIMALS Beta and Gamma Activity in Chicken Excreta . . Autoradiograph of Tibia of Chicken Sacrificed 45 days Autoratliograph of Tibia and Femur of Baby Chick Sacrificed 46 Autoradiograph of Tibia of Pig Sacrificed 45 Days Postdetonation Autoradiograph of Tibia and Femur of Pig 6 Sacrificed 57 Days Autoradiograph of Tibia of Adult Sow Sacrificed 38 Days Autoradiograph of Femur of Boar Sacrificed 26 Days Postdetonation Appearance of Gamma Activity in Egg Shell As a Function of Time . Autoradiograph of Chicken Eggs, Showing Pattern of Deposition of Fission Products in Yolk ........ 1.1 Biologically Hazardous Internally Deposited Fission Products . CHAPTER 2 INTERNAL CONTAMINATION IN HUMAN BEINGS Summary of Human Urine Analysis, Gross Beta Activity . . . Gross Beta Activity in Urine of Ailinginae and American Groups . Radiochemical Analysis of Rongelap Urine ..... Mean Body Burden of Rongelap Group ...... Internal Radioactive Decontamination, Calcium EDTA Treatment of CHAPTER 3 INTERNAL CONTAMINATION IN ANIMALS 3.1 Mortality and External Radiation Dose of Animals from the Living Areas of Rongelap and Utirik .......

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Radiochemical Analysis of Tissues and Urine of Pigs from Beta and Gamma Activity of Chicken from Rongelap . . Beta and Gamma Activity of Fish from Rongelap Lagoon . Radiochemical Analysis of Chicken Eggs .... Survey of Initial Activity of Samples Collected from Rongelap External Contaminationon Representative Rongelap Food Removal of Radioactivity from Rongelap Foodstuffs by Radioactive ContaminationAssociated with Edible Portions of Food Plants of Rongelap and Utirik ...... Radiochemical Analysis of Various Rongelap Samples . . Distribution of Activity Between Particulate and Dissolved Material in Rongelap Well Water ...... Beta-Gamma Data on Water from Rongelap and Utirik . . Distribution of Beta Activity Among Various Size Rongelap Gross Beta and Alpha Activity of Soil, Grass, and Thatch from

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OFFICIAL USE ONLY The objectives of the study of internal radioactive contamination, Project 4.1, are as 1. To determine thi nature and extent of the internal radiation hazard to human beings exposed to the fallout from the 1 March 1954 detonation of Operation CASTLE. 2. To evaluate the contribution of the internal contamination to the acute and long-term 3. To determine the feasibility of an internal decontamination therapy program. 4. To determine the amount and type of contamination sustained by exposed animals, food plants, soil, and water of the contaminated atolls. The nuclear detonation of 1 March was the first instance in which a large group of people received a significant internal contamination from fisiion products with an accompanying external dose of less than lethal magnitude. A detailed study of the internal contamination in the exposed human population and in animals was made to determine the kind and degree of internal deposition. There were three general problems to be investigated: (1) The first was to determine the contribution of the internal contamination to the acute radiation syndrome observed in order to evaluate the importance of internal contamination when combined external and internal irradiation occurs. (2) The second problem concerned the possibility of long-term effects. (3) The third question was directly answered by the study made, that is, what was the qualitative and quantitative nature of the internal contamination produced by exposure of individuals to mixed fission products. There has been no previous situation in which human beings have been exposed to an environment contaminated with mixed fission products. Evaluation of the internal contamination of the human beings was made by a study of the radioelements excreted. Since very little information is presently available concerning the ratio of excreted radioelements to the amount deposited in the body, it was necessary to base the evaluation on data obtained from animals that had been contaminated in the same event. Detailed studies of animal tissues and animal excreta then provided data on which estimates of the human body burden were based. 1.2 GENERAL NATURE OF INTERNAL RADIATION TOXICITY The nature of the radiation hazard from internally deposited fission products can best be understood in terms of the biophysical behavior of the radionuclides. Fission products entering the body through inhalation or ingestion concentrate in various tissues and act as sources of internal radiation. The ability of a radionuclide to enter the OFFICIAL USE ONLY

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blood stream is determined by its solubility, chemical properties, and physical state. The radioelements formed in fission are predominantly oxides which have a limited solubility in body fluids. On this basis only a few of the radioelements can become available to the body. However, the amount that can produce injurious effects when deposited within the body is minute because of the close proximity of the isotope to the tissues it irradiates and because the isotope continues to irradiate these tissues until it is removed by biological turnover or is rendered harmless by radioactive decay. The effects of radiation from internally deposited emitters are the same as those from external radiation. The distinguishing feature of internal radiation, however, is its long continuing nature. TABLE 1.1 -Biologically Hazardous Internally Deposited Fission Products tFrom J. G. Hamilton, Rev. Mod. Phys., 20: 718 (1948). Radioactive isotopes follow the same metabolic processes in the body as the naturally occurring inactive isotopes of the same element and of chemically similar elements. Thus strontium and barium, which are analogous chemically to calcium, are deposited in the calcifying tissue of the bone. Although nearly 200 radioisotopes are produced in the fission process, only a few are potential chronic internal radiation hazards. These fission products, listed in Table 1.1, constitute a high percentage of the fission yield and localize chiefly in bone. The “bone seekers” have, in general, long radiological and biological half lives and produce high-energy beta particles. Thus they cause greater damage to bone and to the radiosensitive bone marrow than to other tissues. The damage to the blood-forming tissue results in a reduction of blood cells and thus affects the entire body. Information on the biological effects of internally deposited isotopes is derived from the limited studies of accidental radioisotopic poisoning in humans or from animal experimentation. The best documented data on the effects of small amounts of internally deposited emitters in human beings are obtained from studies of radium poisoning. As a result of radium deposition, terminal anemia, bone necrosis, and osteogenic sarcoma appeared after a number of years. The residual activity in the body associated with these effects was 1 to 2 IJ~of radium. Radium is a particularly hazardous element when deposited internally because of its very long radiological half life. Very few data are available on the long-term biological effects in human beings of the

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logical effects of a number of fission products have been studied in animals by Hamilton,’ Abrams,l Bloom,’ and others. However, most of these studies do not cover the problem of the long-term effects produced by small amounts of internally deposited isotopes in animals. Few data are available concerning the effects of internal contamination with mixed fission products from nuclear detonations. Contaminationis not produced by every detonation of a nuclear device. For example, no internal contamination was detected in any of the individuals exposed to the airbursts at Nagasaki and Hiroshima. In field tests of the contaminatingtype of atomic detonation, animals that inhaled fission products during short periods of exposure were found to have insignificant amounts of internal The long-term effects (primarily malignant changes) resulting frqm radium deposition have been used to set the limits for maximum permissible body concentrations of various radionuclides.” The maximum permissible level of a radioisotope is the maximum amount which may be deposited in the body withoutthe production of detectable damage. The value for both internal and external irradiation to any&sue is 0.3 rem/week.

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INTERNAL CONTAMINATION IN HUMAN BEINGS The internal contamination study was begun 15 days postdetonation with the collection of pooled 24-hr urine samples from the Marshallese and American groups. Maximum activity in the urine occurred during the first few days after internal contamination. By one week an approximate equilibrium state was reached in which the contaminants remaining in the body were firmly fixed, chiefly in the skeletal tissues. The activity in the urine then was derived from radioelements which were replaced in the natural process of biological turnover. Thus the study made is essentially that of an equilibrium condition. All the urine samples were sent back to laboratories in the United States for analysis since the high background encountered in the field masked the relatively low levels of activity in the aliquot samples used. A field laboratory is most desirable for a rapid survey and was shown to be feasible if adequate facilities are provided for the counting of the samples. The first urine samples, mentioned above, were collected by the Los Alamos Scientific Laboratory (LASL). Similar samples collected 44 days postdetonation were …