J.A.M.A+y Oct. 1, 1955 RESPONSE OF HUMAN BEINGS ACCIDENTALLY EXPOSED TO SIGNIFICANT FALL-OUT RADIATION Commander Eugene P. Cronkite (MC), U. S. N., Victor P. Bond, M.D., San Francisco, Commander Robert A. Conard, Lieut. N. Raphael Shulman, Lieut. Richard S. Farr, (MC), U.S.N., Stanton H. Cohn, Ph.D., San Francisco, Charles L. Dunham, M.D., Washington, D. C. K and Lieut. Col. L. Eugene Browning (MC) U.S. Army After detonation of a nuclear device in the Marshall Islands during the spring of 1954, radioactive material fell upon several neighboring inhabited atolls.: Thefallout material consisted of pulverized and incinerated coral (calcium oxide) coated with radioactive fission products, forced high into the atmosphere by the violence of the explosion. The particulate matter was then distributed over a wide area by the wind structure. The field of radiation resulting from the deposition of this:radioactive material on the islands was sufficiently intense to result in significant whole-body irradiation of the inhabitants. In addition, the skin was contaminated with the material, and someofit was inhaled and ingested. THe calculated whole-body dose of radiation in roentgens as:measured in ‘air and the amountof fall-out observed for each of the island groups is shown below. The exposed American Calculated Whole Body Dose of Radiation Taland Group Rongelap Population 64 Marshallese Roogerik 8 American Allingioae , UOtirik 18 Marshallese Whok-Body Dose in r 175 Fall-Out Observed Heavy (gnow-lke) 7% Moderste (mist-like) servicemen 157 Marshallese oo lu Moderate (mist-itke) Hospital, Honolulu, T. H. The Utirik people were re- turnedto their native atoll after the initial period of observation. The Rongelap and Ailinginae residents were moved to Majuro Atoll for temporary occupation of dwellings built for them. These gammaray doses were calculated from field instrument readings taken at the time of evacuation and decay schemes appropriate for the estimated times of exposure. For the sabe of brevity, details will be presented only on the more’Severely exposed Rongelap group and other groups will be referred to only for comparative purposes. The detonation of the device was observedin the early morning, and hours later the exposed individuals noticed a snow-like material falling from the sky; this continued for several hours. The material was visible on the ground From the Naval Medical Research [ostitute, Bethesda, Md., and ‘J. 5. Radiological Defense Laboratory, San Francisco. Commander Cronkite is now at Brookhaven National Laboratory, Upton, N, Y. Lieut. Parr ts now at the University of Chicago, School of Biological and Medical Sciences. Read before the Section on Military Medicine at the 104th Annual Meeting of the American Medics! Association, Adantic City, June ¢, 1955, Drs. David A. Wood, University of California Hospital, Ses Prascisco, and Edward L. Alpen, U. &. Naval Radiological Defense Laboratory, San Francisco, made the histopathological evaluation of the skin The discussion of this paper was opened by Dr. Lee EB. Farr, Upton, N. Y., and Major Carl Hanson, Washington, D. C. Matement by Lewts L. 1. Effects of High-Yield Nuclear Strauss, chairman, ead report by United States Atomic Eaergy Comee he veloped nausea and 10% vomited and had diarrhea. During this period also, many developed itching and burning of the skin and some reported burning of the eyes with lacrimation. Supervised decontamination and medical care was not possible until the exposed individuals were evacuated to the nearby naval base at Kwaja- lein. By this time, initial symptoms had completely subsided. An emergency medical team, composed largely of naval personnel from the Naval Medical Research Institute and the U. S. Naval Radiological Defense Laboratory, was organized and sent to the area, arriving on the ninth day after exposure. Complete initial histories and physical examinations and frequent follow-up examinations and treatment for medical conditions were carried out on all personnel. In addition, hematological studies to assay the degree of radiation damage and urinary excretion studies for radioactive materials were performed. It was apparent from initial blood studies None servicemen were returned to duty after extensive medical examinations at Kwajalein and at the Tripler General Naval and sifted into the lightly constructed thatched-roof houses. The material whitened the hair and clung to the skin. During the night following the explosion and for the next two days, about two-thirds of the population de- that significant radiation had been received, and by 12 to 14 days further evidence of radiation injury was appatent in the form of skin lesions and epilation. With the exception of the developmentof skin lesions and epila- tion, physical examinations at no time revealed findings in any group that could be attributed with certainty to radiation. CLINICAL OBSERVATIONS, THERAPY, AND HEMATOLOGICAL FINDINGS Since the degree of depression of peripheral blood elements is believed to be the best index of severity of radiation injury, systematic serial determinations were carried out. These determinations consisted of total leukocyte, neutrophil, lymphocyte, and platelet counts and hematocrit determinations. Control groups, as comparable as possible to the exposure groups in respect to age, race, sex, and background, were selected. Findings are expressed in terms of percentage of control values. Significant age and sex difference in blood cell counts were noted in the control groups, and the data are presetited ia accordance with the differences noted. The absolute neutrophil count(fig. 1) of both younger and older age groups fell to a value of approximately 70 to 80% of that of the controls during the second week, followed by a period of fluctuation until the fifth week. At this time the beginning of a second depression was noted for both age groups, and a low value of approxi- matelw 40% of that of the controle ane reached Tha