MEDICAL SURVEY OF RONGELAP PEOPLE, MARCH 1958, FOUR YEARS AFTER EXPOSURE TO FALLOUT Background This report presents the results of a medical surveycarried out in March 1958 on the Marshal- lese people of Rongelap Atoll who were accidentally exposed to radioactive fallout in March 1954. The accident occurred following the detonation of a high vield thermonuclear device during experiments at Bikini in the Pacific Proving Grounds. An unpredicted shift in winds caused a deposition ofsignificant amountsoffallout on four inhabited Marshall Islands nearby and on 23 Japanese fishermen aboard their fishing vessel, the Lucky Dragon (see Figure 1.) Sixty-four inhabit- ants ofthe island of Rongelap, 105 nautical miles awayfrom the detonation, received the largest fallout exposure: an estimated dose of 175 r whole- body gammaradiation, beta burns andepilation from contaminationof the skin, and slight internal absorption of radioactive material. Another 18 Rongelap people away on a nearbyisland (Ailing- nace), where less fallout occurred, received only about half this exposure. Twenty-eight American servicemen on the island of Rongerik further away received about the same amountof radiation as did the 18 people on Ailingnae (about 70 r). Lastly, 157 Marshallese on Utirik, about 200 miles . distant, received only about 14 r whole-body radiation. The fallout was not visible on this island and noskin effects were seen. The exposed people were evacuated from these islands by plane and ship about two daysafter the accident and taken to Kwajalein Naval Base about 200 miles to the south, where they received extensive examinationsfor the following 3 months. In view of the generally negative findings on the American servicemen, they were returned to their duty stations. The Utirik people were repatriated to their home island, where the radioactivity was considered to be low enoughfor safe habitation. Because Rongelap Atoll was considered to be too highly contaminated, a temporary village was constructed for the Rongelap people on Majuro Atoll several hundred miles to the south, where they remained for the following 32 years. In July 1957, after careful evaluation of remaining radio- hh ft 3 Cr ced oo Cs logical hazards, Rongelap Island wasfoundsafe for habitation. A newvillage was constructed, and the Rongelap people were moved there by Navy ship. The present survey was therefore carried out at Rongelap Island. SUMMARY OF PAST FINDINGS Reports have been published on the findings of surveys made at the following times after exposure: initial examinations,’ 6 months,” | year,' 2 years,’ and 3 years.’ The following is a brief summaryof these findings. During the first 24 to 48 hr after exposure, about *% of the Rongelap people experienced anorexia and nausea. A few vomited and had diarrhea. Manyalso experienced itching and burning of the skin and a few complained of lachrymation and burning of the eyes. Following this, these people remained asymptomatic until about 2 weeks after the accident, when cutaneouslesions and loss of hair developed duelargely to beta irradiation of the skin. It was apparent whenthe people werefirst examined, a few days after exposure, that the lymphocytes were considerably depressed and that significant doses of radiation had probably been received. In addition to the whole-body dose of radiation and the betairradiation of the skin, radiochemical analyses of the urine showed that significant amounts ofradio- active material had also been absorbed internally. The effects of the radiation can best be summarized under three headings according to the mode of exposure: penetrating irradiation, skin irradiation, and internalirradiation. Penetrating Irradiation The changesin the peripheral blood of the more heavily exposed Rongelap people who received 175 r will be reviewed below (see Figures 7, 9, 12 and Tables 3, 4,5). The changes in the Ailingnae and Utirik groups weresimilar but less marked. Certain unexplained fluctuations have occured from yearto year in the peripheral bloodlevels of the comparison populations as well as of the exposed groups. Depression of the peripheral blood elements as represented by mean population levels occurred as follows.