A TWENTY-YEAR REVIEW OF MEDICAL FINDINGS IN A MARSHALLESE POPULATION ACCIDENTALLY EXPOSED TO RADIOACTIVE FALLOUT 1. Background A. THE ACCIDENT The testing of nuclear devices in the Marshall Islands (see Hines25), beginning with Operation Crossroads at Bikini in 1946 and ending with the moratorium in 1958, did not result in significant radiation exposure to personnelor fallout contamination outside the test area except in onecase. repeated physical examinations including studies _ and photographs of beta burnsof the skin, made numerous hematological tests, and monitored for external and internally absorbed radioisotopes. Complete removal of the radioactive contamination from the skin and hair required manycleansing procedures; the coconutoil used on the hair was particularly retentive. At the end of the ex- amination period, most of the skin burns had healed and,althoughsignificant hematological de- On March 1, 1954, the detonation from a tower of a thermonuclear device, Bravo, in the Castle Se- pression had occurred, no serious illnesses were evident that could be related to radiation injury. siderably greater than expected, and an unpre- campmenton EbeyeIsiand for a stay of several weeks. Since Utirik Atoll was only very slightly contaminated from the fallout, it was considered ries of tests at Bikini resulted in a serious fallout accident. The yield was about 17 megatons, con- dicted shift in winds in the upper atmosphere The Marshallese people were taken to a tent en- caused the radioactive cloud to drift over and deposit failout on several inhabited atolls to the east: Rongelap with 64 people, Ailingnae with 18 people, Rongerik with 28 American servicemen, and Utirik with 157 peopie (see Figure 1). A Jap- safe for habitation, and the Utirik people were recurned there with fresh supplies, clothing, andlivestock. Rongelap Atoil was too contaminated to al- with 23 fishermen aboard was also exposed (see Appendix 3). The fallout is thought to have com- Atoll, where they lived for 3 years until their re- anese fishing vessel in the area, the Lucky Dragon, menced at Rongelap about4 to 6 hr after the detonation, at Rongerik about 7 hr after it, and at Utirik about 22 hr afterit. Its duration on the islands is uncertain but has been estimated as about 12 hr, the greater part of the fallout occurring early in the period.? The estimated dose of gammaradiation to theisland populations is discussed in Sec- don IT. A. The American servicemen on Rongerik noted that the needle on a telemetering instrument suddenly beganrising and wentoff-scale in 30 min, beginning about6 to 7 hr after the detonation. An alarm was radioedto the task force, and a plane flying low confirmed thatsignificant fallout had occurred. The exposed people were evacuated by planes and Navy ships within about two days and taken to Kwajalein, 175 miles to the south. They were first examined by the medical group at the Naval Dispensary there. Eight days after the accident a medical team consisting of 21 doctors and technicians, largely from the Navy, which had been re- quested by the AEC, arrived at Kwajalein. For two months the team took medicalhistories, did LOC E98 low immediate return andits people (along with the 18 from Ailingnae) were taken to a temporary village built for them on Ejet Island in Majuro turn to Rongelap. The American servicemen were taken to Tripler Army Hospital for further examinations and later returned to duty. B. ANNUAL EXAMINATIONS Medical examinations of the Rongelap people were conducted at their temporary home on Majuro in September of 1954 and in March of 1955, 1956, and 1957. In 1954 an unexposed group of Marshallese living at Majuro was chosen as a comparison population for these examinations. This group, however, was composed of people from manyof the Marshall Islands who were not easily located for subsequent examinations. Unexposed Rongelap people gradually moved to Ejet to live with their fellow islanders, and this group increased further on the return to Rongelap. These unexposed Rongelap people were included in the examinations and have served as an excellent comparison population since they are blood relatives of the exposed Rongelap people, match reasonably well for age and sex, and live under the same environmental conditions (see Section III. A.).