Plutonium Concentrations in Dietary and Inhalation Pathways at Bikini and New York

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PLUTONIUM CONCENTRATIONS IN DIETARY AND INHALATION PATHWAYS AT BIKINI AND NEW YORK Prepared for U.S. Energy Research & Development Administration under contract No. W-7405-Eng-48

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This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Energy Research &. Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe Reference t o a company or product name does not imply approval or recommendation of the product by the University of California or the U.S. Energy Research & Development Administration to the exclusion of others that may be suitable. Printed in tlic United States of America National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Price: Prmted Copy I *Add 32.50 lor each additional 100 pdgc increment lrorn 601 to 1,000 pager; add 54.50 for each additional 100 page incrcment over 1,000 pages.

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ii Distribution Category PLUTONIUM CONCENTRATIONS IN DIETARY AND INHALATION PATHWAYS AT BIKINI AND NEW YORK

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Plutonium Concentrations in the Inhalation Pathway ...... Plutonium Concentrations in the Ingestion Pathway ...... In take Concentrations Compared with Excreted Concentrations....

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PLUTONIUM CONCENTRATIONS IN DIETARY AND INHALATION PATHWAYS A T BIKINI AND NEW YORK This report assesses the plutonium in take via inhalation and ingestion for residents of New York and residents of Bikini Atoll. Based on inhal ation and ingestion in take,the plutonium transferred to urine would be roughly seven times greater at Bikini than at New York. This ratio compares with data reported to the authors showing urine samples from Bikini residents had about ten times the plutonium of urine samples from New York residents. The comparison of these ratios indicates that d if - ference s in the levels of in take in the New York and Bikini populations can account for the relative differ - ence between the plutonium con cent ra - tions observed in urine samples from the two locations. However, transfer coefficients and models presently accepted for inhaled and ingested plutonium do not account for the absolute magnitude of the This discrepancy suggests inaccuracy in either the plutonium con cent ra - t ions reported for urine samples o r the models and transfer coefficients presently accepted for the metabolism of plutonium in the body. The available urine data consist of results from very few samples, and more data is needed to completely verify the assessments of this paper. It is felt that Bikini Atoll may be the only global sources of data on humans where in take via ingestion is thought to contribute the major frac - tion of the plutonium body burden, and therefore Bikini is possibly the best source of data on transfer of biologically incorporated plutonium across the gut wall. Bikini Atoll was one of the two 1969-70. I n 1970, analyses by the major locations for United States HASL ERDA Laboratory of pooled urine nuclear tests from 1946 through 1958. >k Health and Safety Laboratory, New Re habitation of the atoll began i n York, N.Y.

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samples from Bikini Island showed the average concentration of average concentration of in three urine samples from Bikini was 0.004 pCi / liter. But i n 1974 the average inten samples was a much are attached to these concentrations reported in Ref. 1. The average concentration for any year was obtai ned by multiplying the plutonium concentration of each sample by its volume, summing these products, and dividing by the total volume,)In 1975 the average 239 9240 ~ uc once ntr a - tion in a pooled 9 - liter urine sample liter.This concentration is similar to the value found i n 1974 but is ten times higher than the concentration of 0.001 pCi / liter reported for a 1975 representative population sample from New York. 2 Because of the toxicity of pluto - nium and the belief that urine concent rations directly indicate pluto - nium burdens in the body, the 1970-75 increase of plutonium in Bikini urine samples and the much higher plutonium urine levels in Bikini samples, compared t o New York samples, are cause The purpose of this report is to compare data on Bikini and New York plutonium pathways t o man. Although comparing the in take of plutonium via various pathways does not lead directly to abo lute plutonium concent rations in body tissues or exc ret ions,it does show that a Bikini population is exposed to higher plutonium levels through dietary and inhalation pathways thana New York We acknowledge that the excretion rates of plutonium and the quantities excreted may differ significantly, depending on routes of entry into the body, and that the assessment of these rates and quantities is further comp lica ted by dissimilar physio-chemical forms of plutonium inthe environment. We suggest that different con cent ra - tions of plutonium in corresponding pathways of New York and Bikini can account for the difference between urinary levels presently found inthe two populations, However, the estimated in takes of plutonium at both New York and Bikini should give concent rations in urine very different than those reported to US.^ discrepancy suggests several inter - If the concentrations found i n pathways relate directly to the connium in Bikini an s ' urine will in - crease with time and will differ even more from concurrent New York samples as the Bikini an s rely in - crea singly on dietary components from

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PLUTONIUM CONCENTRATIONS I N THE The contribution from the in hala - tion pathway to plutonium concentration in urine,especially at Bikini, is very hard to quantify.In add i - tion to the different activity levels from fallout in the air at Bikini and New York, re suspension processes that contribute airborne plutonium at New York and Bikini are very difficult t o assess. Nevertheless, it is important t o assess these processes in estimating the cumulative exposure t o plutonium from inhalation. Bennett3 has recently concluded that plutonium from re suspended fallout a t New York presently contributes 0.3% and will ultimately contribute in take equal to 0.5% of the in take that occurs during the original deposition of the fallout debris. Data of one of the authors4 show that the soil plutonium levels on Bikini Island are, on the average,higher than plutonium levels from fallout deposited in the United States.5 Visual observations indicate that the formation of dust clouds or the re suspension of surface materials by people or vehicles at Bikini is slight, even during very long dry spells. However, the available aerosol data show that some locations on Bikini Island have more plutonium in the air than expected from worldwide fallout and more than encountered inNew York City during comparable periods. These data indicate that re suspension does significantly contribute to inhalation of plutonium at Bikini. We will show ina following section that re suspension might also contribute to elevated plutonium levels in the ingestion pathway a t Comparable data on plutonium concent rations in the air exist only for the periods of May 29 to June2, surface air were determined at five locations on Bikini Island and ranged concentration at four sites on the function of latitude are the average plutonium concentrations at ground level at air sampling stations of the HASL sampling network,taken during June 1970. The concentration - latitude profile is simply a contin u o us curve drawn through the available data points. Plotted in Fig.1 as a From this curve,the average fallout - plutonium concentration expected in ground - level air at the

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Island the log normal median, mean of measured concentrations(134 even the lowest concentration found on the entire island are well above mean of concentrations detected on the less contaminated island of Eneu agrees well with this expected concent ration.4y However, on Bikini Fig. 1. Concentrations of 239 ' 240p,in air at various latitudes,taken during June 1 9 7 0 , by t h e HASL sampling network.

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the concentration expected from Fig. 1. Thus, there is little question that the plutonium levels in the air of Bikini Island around the first part of June 1970 were above fallout - plutonium background levels for that latitude. The only mechanisms that could cause such levels are resus - pension processes on the island. The median concentration at Bikini was very nearly equivalent to the mean air concentration at New York during this period in 1970. Remember that during 1970 the urine con cent ra - tions from Bikini and New York were also comparable. Except for water and possibly some fish, no indigenous .material was consumed at Bikini comparison of New York and Bikini, the 1970 data strongly suggest a close correlation between plutonium levels in air and concentrations in I n May, 1972, air samplers were again operated on Bikini Island at four different locations. The 239y240Pu air concentration during this period ranged from less than6 concentration over the island was air concentrations of plutonium during May 1972 are plotted as a function of latitude. ' A smooth continuous curve has again been drawn through the data points. curve, the concentration of plutonium expected in air at the latitude of Bikini during May 1972 is approx i - normal median (21 aCi/m ) of actual concentrations at Bikini is only slightly more than this value,the mean plutonium air concentration detected at Bikini during this period were detected in the air at New York. Again we find a similarity between the levels of plutonium in Bikini and New York air, and the Bikini mean concentration is again higher than expected for this latitude from worldwide fallout concentrations. The 1972 data on air concentration of plutonium at Bikini also showed a strong geographic correlation. The plutonium air concentrations in the samplers increased from northwest to southeast along the length of the island.Therefore, some regions of the island have higher plutonium air concentrations than others. The individual ' s inhalation exposure, then, must also depend on the time spent in specific regions of the I n summary, the data on air concent rations of plutonium at Bikini are rather sketchy, and w e do not know how different the concentrations in large volumes of open air are from

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those in an individual ' s immediate environment, resulting from resus - assume that the plutonium in take via the inhalation pathway on Bikini Island is comparable to that in New York. Also,the available data strongly suggest that over certain regions of the island the aeolian concentrations are significantly higher than in New York. If res us - pension by human activity is also important, as i t seems tobe,there We can a t least safely is a much greater chance of higher exposure at Bikini through the inhal ation pathway. PLUTONIUM CONCENTRATIONS I N THE The primary source of drinking and cooking water for Bikini inhabitants is un processed rain water obtained from cisterns attached to the newly constructed buildings along Lagoon Road. The cisterns collect water May 1 9 7 2 , by t h e HASL sampling network.

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Table 1. Radio nuclide concentrations in the drinking water of Bikini cisterns, Building that the drained from the windward roof of each building. Ground water has also been used for drinking in periods of drought and will be used inthe future whenever cistern water is unavailable. The ground water is presently in high demand for agri cul - ture on Bikini Island. Three of the cisterns were first sampled in June1975 and analyzed for nuclides. The results are abstracted the fallout in rainfall at other Pacific islands over the period 1968 t o 1974, itwas concluded that the From an examination of and, by analogy, 137Cs and 239y240Pu concentrations in the cistern water did not result solely cisterns appear to have contained locally derived levels of radio - tion, two water samples collected by one of the authors(V.N.)in October 1975 from the drinking water tanks on the ERDA-supported Marshall Island research vessel, theR.V.L ikta nur, of 137Cs. This water came from the rain-water supply collected at Kwajalein Atoll and is therefore indicative of fallout concentrations in Marshall Island rainfall. The in Marshall Island rainfall are then approximately 1 / 2 0 of the con cent ra - t ions in the Bikini cisterns. We therefore conclude that the Bikini cistern water contains levels of plutonium radio nuclides that,while small , are nevertheless significantly elevated above the levels expected from worldwide fallout. The higher concentrations could originate from leaching of the concrete cisterns (the concrete used for the cistern construction was locally derived)or, alternatively, from labeled particles being re suspended in air, accumulatin g on the drainage surface of the roofs,then being washed into the cisterns with then extra in.If the latter mechanism is correct, resuspension processes contribute