A Radiological Study of Rongelap Atoll, Marshall Islands, During 1954-1955

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Operated by the University of Washington under Contract I?OO Applied Fisheries Laboratory University of Washington

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The detonation of shot one at Bikini Atoll on Narch 1, 1954, produced a fallout of radioactive ash upon Rongelap Atoll, Mars~ll Islands. The distribution of the radioactive ash on the islands and in the plants and antils of the area has been studied and evaluated by the Applied Fisheries Laboratory, During the first expedition to Rongelap Atoll on March 26, 1954, biological samples were collected and measurements made of the radiation contamination. On three additional expeditions extensive collections of material were made for this study, the last on Jauary 25-30, 1955~ The decltie in radioactivity was measured in 1499 samples of fish, invertebrates, land plan~s~ algae, bfidsj pl~kton~ soil and water from the Rongelap area. During this study particular emphasis was placed upon evaluation of the radioactivity h food used by the natives. Coconut milk collected on March 26, 19542 conta~ed 1c03 m~croc~ies Per kilogram of wet tissue while the coconut meat had 1.16 uc/kg. BY Jmuary 25-30, 1955, the level in coconut milk had declined to 0.041 uc/kg and the meat to 0.036 uc/kg. Fish muscle on March 26, 1954, averaged 2.74 uc/kg and fish liver 204. uc/kg. The decl~e to January 25-30 was 0.10 uc/kg for the.muscle and 3.52 uC/@ for the liver of fish. Somewhat similar declines were found for clam muscle, crab muscle, bird muscle and liver, and for squashy

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papaya, arrowroot and pandanus. . The level of radioactivity was highest in the northern portion of the atoll, except for samples of algae and fisheating birdsj collected during January 1955 from the southern part of the atoll, which had higher levels of radioactivity than samples collected from the northern islands on the same date. This may indicate a translocation of radioactive materials within the lagoon.

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Sample processtig procedue and techniques Radioactivity and its rate of decllne in food Evaluation of radioactivity in the biological Land plants and algae Evaluation of the chemical analyses of the Study of the rate of physical decay of radiation in the biological samples

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Radioactivity of foods from Rongelap Atoll, Coeffltiientof variation in percent for values in Table I Radioactlvlty of fish caught at Kabelle Island, Rongelap Atoll Radl~activity of fish caught at Rongelap Atoll, other than at Kabelle Island Radioactivity of Rongelap birds and bird Fission products and radio-calcium in soil from Rongelap Atoll biological samples from Rongelap Atoll Decay rates of Rongelap samples expressed as the slope of the log-log relationship of activity to time after March 1, 1954 Radioactivity of fish from Rongelap Atoll, Scientific names of fishes 53 Radioactivity of Invertebrates other than corals collected at Rongelap Atoll, Radioactivity of coral from Rongelap Atoll, Radioactivity of coconuts from Rongelap

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Radioactivity of edible plants other than coconuts from Rongelap Atoll, 1954-55 plants other than those from Rongelap Atoll, 1954-55 marine algae from Rongelap birds collected at Rongelap tern eggs from Rongelap plankton, soil-sand, and water “ samples from Rongelap Atoll, 1954-55 Data for computing percent activity of flsslon products and calcium in Rongelap soil samples based on 1 milliliter replicates Physical decay rates of Rongelap samples

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Collecttig areas at Rongelap Atoll curies per kilogr~ in fish tissues from curies per kilograM in liver, bone and muscle of carnivorous and omnivorous fishes from Kabelle Island 1954-1955 Radioactivity in microcuries per kilogrm in fish tissues collected in the vicinity of Rongelap Atoll, December 1954 and January Radioactivity in sea cucumber (Holothurla atra) tissues from Kabelle Island 1954-1955 Radioactivity & giant clam tissues: HiPPoPus on March 26> 1954 at ~belle; Tridacna on at Labaredj and on January 30~ Radioactivity in tissues of the land hermit crab, Coenobita on March 26 at Labaredj, January 26, 1955 at Rongelap 21 Rate of decline in land plants, algae and soil samples at Kabelle 1954-1955 24 Dealine of radioactivity in muscle, liver, and kidney samples from north Rongelap expressed as a ratio to the March 26, 1954 Decline of radioactivity in bone and ileu samples from north Rongela! expressed as a ratio to the March 26, 195 collection

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11 Semi-1og plots of decay curves of gastric mill of crab, (lrapsusgrapsus, and musole of sea cucumber, Holothuria atra, colleoted 12 l Log-log plots of Rongelap decay samples of March 26, 1954: plankton from Labaredj; muscle and mantle of giant clam, HIPPopusj from Kabelle; and soil on which decay correction factors were based 44 13l Log-log plots of radioactive decay rate of coconut milk, (Cocos) collected December 8, 1954 at Kabelle, and of liver and muscle of

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A RADIOL~ICAL S- OF RONGELAP ATOLL, MARSHALL The program of study of the Applied Fisheries Laboratory, University of Washington, (Program 19.1 of Operation Castle) was in the Laboratory~s report UWFL-36. This program involved studies of radiological contamination of the fauna and Eniwetok Atoll, with exploratory trips to Bikini Atoll on ~ quarterly basis to ascertain the levels of during the year following the test program. The unexpected pattern and magnitude of radioactive materials from the March 1, 1954 the fallout of the need for new areas of study over and above the planned pro- ~am. One such area was Rongelap Atoll where the fallout resulted .n the evacuation of the native people. On March 21, 1954, the Laboratory recieved a request from k. Paul B. Pearson, AEC Division of Biology and Medicine, to sake a survey of the islands at Rongelap Atoll to determine the }xtent of radiological contamination of the native foods. The expedition to Rongelap, in response to this request, 19.1 Were Lauren R. Donaldson, Charles PI.Barnes, Edward E. Held, talph F. Palumbo and Paul R. Olson. Thomas Shipman, Thomas N. tion to aid the natives In capturing some of their animals on longelaP Island and to make radiation readings on some of the ‘

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Lslmds in the southern part of the atoll. Collections of plants and animals, soil samples and radiation readfigs were made at Labaredj Island on March 26, 1954. serial I?OO89) under a variety of conditions. The shield of the lnstrwent was closed for the first read= ad OPen for the second for each of the locations listed below. Radiation Levels Labaredj Island High tide line Open grass area Open grass area In Pisonia woods Beach rock slabs Beach above high tide llne north side of island East side of island 200 220 above high tide 350 700 A second series of collections were made on the same day at IQbelle Island in the extreme northeastern part of the lagoon’ Radiation read-s were also ~ken at this island as fOl~OWS:

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Radiation Levels Kabelle Island Beach sand at Edge of brush llne on island lagoon Open area in vegeportion of island Coconut grove on lagoon side of Edge of ltrees Lee side of trees Windward side of trees fl 2800 The second expedition to Rongelap Atoll was made on ly 16, 1954. A U.S. Navy Grumman Albatross plane (U.S.P?. R-16, Ho. 902) from the U.S. Naval Station, Kwajaleln, was ed to transport the group to the atoll. Program 19.1 members ktng the trip were Lauren R. Donaldson, Frank Lo~any Arthur Collections were again made at Kabelle Island and radiation Iad@s taken in the same general areas as those recorded on

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Radiation Levels Kabelle Island Low water llne high tide line high tide line ~ On Scaevola brush Me edge of coooMiddle of island Open clearing In middle of island Middle of cooonut During the month of December 1954 three collections of - pies were made at Rongelap Atoll. For the first trip on Decem8, the U.S. Naval Station, Kwajalein, provided a PBM 1.2471) with a fine crew. Landings were made at both Kabelle Rongelap Islands. Dr. Walter D. Claus, AEC Division of Biol- ‘ and Medicine, accompanied Edward Held, Paul Olson, Robert and William Blakeman on this expedition. Film strips were at a number of locations by Claus, Taylor and Blakeman to radiation over an interval of time. On December 18, the Navy again furnished a PBM for the trfP Ron8elQp to pick up the film strips and to collect addition~’

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A successful landing was made at Rongelap ‘ti where the objective V8S accomplished, An accident to the horixlgmeo~nigm of the plane, however, prevented completion the sampl143 at KAbelle Island. Robert Rinehart and Paul groan of u.S.M.R.D.L. accompanied Lauren R. Donaldson, Jared via, Edward Held and paul Olson on this trip. The most extensive survey ad biological collecting trip ,Sconduoted at Rongelap Atoll from January 25 to January 30, ’55* This survey was made in conjunction with U.S.??.R.D.L., ansportation and support facilitfea. Allyn H. Seymour and an.kLowman, Program X9.1, shared the responsibility for the ological sampling. Readings were again made with the survey ter on almost all of the islands visited. The readings were ken at a height of three feet unless otherwise noted. Kabqlle Island 3.0ir II 5.0 at ground level The oolleotions at Rongelap Atoll during this period of ~dy Provided material for 1499 samples which have been proc- ~eds the radiomtive content determined and the results tabu- ‘.

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DAYS AFTER MARCH 1,1934 ‘ 2 RATE OF DECLINE OF RADIOACTIVITY OF RONGELAP FOODS t,1

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, vhlch are considerable and Which are evident in the tables he appeal= where all the individual sample counts are tabud, are not apparent in this generalization. The significance hese differences, however, is discussed on pages 11 to 34. ioactlvity in the prtioipal food items of Rongelap Atoll can The method selected to indicate the error In estimating the ues in Table I is the “coefficient of variation whloh is ratio of the standard deviation to the mean. These values, expressed in percent, are given in Table 11 (page 7 ). The e in values from 10 percent to 178 percent indicates a high ree of variability. These data are closest to being points on a stratght line n plotted on a log-log scale “usingthe time of the blast, ch Is 1954s as time of origin. From this data It appears that mixed fission products the prinoipal source of’radioactivity in the food stuffs. ieptions are bird thnoids, In which the radioactlvit~ was. –“ ,Ctic&llyall 1131, and the gastric mill in a coconut crab, ? which the decay e~ve was nearly a straight line on a semi- ! plot. For the purpose of making an approximation of the )rage rate of decllne, the slope of a least-squares line ~ough the averages of the points in Figure 2 was determined 1 found to be -1.75. It ~st~ces, is related to fallout, Rongelap Atoll was on .

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Southern edge of the fallout from the March Z, 1954 Bikini erlxent and as a consequence there was considerably more inactivity In the northern part of that area. The biological ,plesshow the same pattern except for the bird collections the algae and sand samPles f’romdeep waters of the ~agoon>

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southern edge Of the fallout from the ~r~ent and as a consequence there was loact~vity in the northern part of that area. The biological ple9 show the same pattern except for the bird collections the algae and sand samples from deep waters of the lagoon,

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a~uation of Radioactivity in the Biological Samples Almost all Of the fish specimens, as in former years, were olleated by po~sontig with derris root h shallow waters on or ear the reefs. Some specimens were oaught in the deeper aters of the lagoon with hook and line. TwO flying fish ere obtained outside the atoll when they landed urlng the night. The species seleeted for analysis are those n the atolls and used for food. They include damselfish, rasse, snappers, mullet and tuna. The scientific names of pecies are given in the appendix. The tissues used for analysis of radioactivity were skin, uscle, bone, liver and other viscera. The latter included part f the stomach contents as well as the alimentary canal, in most In m attempt to compare similar species from the same ooality, analysis was limited to the samples from Kabelle sland. Collections of fish were made in waters adjacent to his island on March 26, 1954, July 16, 1954, and January 29? 955. The collecttig area lies near the north end of the sland and consists of a coral-filled channel open to the sea t high tide. The radioactivity of the tissues from the fish Olleoted at Kabelle is summarized in Figure 3. The data are lsted in Table III. ,,,%>:*’”’

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SKIN ‘. ALL FOOD ITEMS DAYS AFTER MARCH I , 1954 FISH TISSUES FROM KABELLE ISLAN13 1954 – 1955

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ore was selective uptake h th 1These data substantiate the general hypothesis, mentioned Flier in this report, tmt the radioactivity in the tissues ~ears to be due principally to mixed fission products. Devllon~ from a straight line in the curves might be due to t-.+{v~ llntake.either by the tissues themselves or because ~eanimals used as food by the shes. ~ general the slope of the curves compares favorably to amounts of at on March 26, ge of time and by January 29, 1955, were negligible deoline curve used for all food items discussed of this report. between the omnivorous and carnivorous fishes radioactivity in comparable tissues were greati issues (Figure 4, Table 111). These same data when analyzed y definite species ofomnivorous fish (damselfish) and carlvorous fish (grouper) show the same trends (Table III). Variation in radioactivity, associated with area and rested to fallout and ~urrent movements withfn and around the toll, tidlcates an Increase in the contamination of the atoll om south to north (Figure 5, Table IV). The lagoon fish ken in the northern part of the lagoon, off Xabelle or Menu ~1~~ are Comparable in levels of radioactivity to reef ftshes ken in this region. The two flytig fish taken outside the atoll Fe remarkably alike In tissue radioactlvtty.

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DAYS AFTER MARCH 1 , 1954 W. 4 AvERAGE AMOUNTS OF RADIOACTIVITY IN MICROCURIES PER KILOGRAM ‘ER t BoNE ANo MUSCLE TISSUE OF CARNIVOROUS ANO OMNIVOROUS FISHES

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1 Rongelap invertebrates showed levels Of activity of from L02 to 104 UC/kg on March 26, 1954. BY late J=uary 1955 the ,evelshad dropped about two orders of magnitude. The almost Iniquitousblack sea cucumber, Holothuria atra, serves best to xemplify the trend (Figure 6). Eext best as indicators were iant clams, HiPROPUS and Tridacna; land hermit crab, Coenobita; oconut crabs Biros; aorals; and spider snail, Pterocera. ..adioactivitywas highest in the digestive and excretory organs, intermediate in the integumentary orgem, and lowe!ktin the muscle, Actual values for the samples are tabulated h the appendix. The kidney of the giant clam (Figure 7) is of special Interest because of’its high level of activity and slow rate of A graph of activity of the tissues of land hermit o~abs collected at the more radioactive northern islands in March and July 1954,em from a less radioactive southern island fn January 1955, shows the effect of geographical differences in radioactivity upon the trend of decline, accentuate the slope ~ the later period (Figure 8), The spider snail was stmilar to the hermit crab in the level of activity of its …