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Machine-read from the scan, so expect some errors. Lines that couldn’t be read are left out.
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Director, Division of Operational and Environmental Department of Energy Mapager, Envi ronment , Health, and Safety Research Program Bat tell e,Pacific Northwest Labora t o ri es The Enewetak Advisory Group met on April 26 a n d 2 7 , 1978 i n Denver, Colorado. t o consider the fol lowing questions: The purpose of the meeting was 1. Isit possible t o develop dose-related cleanup guidance that would asslure that doses t o future residents of Enewetak Atoll would not significantly exceed proposed EPA guidelines for transuranics? What advice can be given t o the Defense Nuclear Agency on May 3, 1978 t o facilitate planning for cleanup of transuranics on Enewetak? What additional information can be obtained that could improve the confidence of the dose estimates and cleanup criteria for transuranics? The Advisory Group reviewed information and data provided by DOE-Division o f Can plowing be used as an effective cleanup measure for transuranics in soils ? Occupati opal a n d Envi ronmental Safety, Lawrence L i vermore Laboratory, DOE-Nevada Operations Office, and Defense Nuclear Agency and offers the following response t o the above questions. (This pertains only to transuranic elements and does not consider radiation doses from other radionuclides which, the Advisory Group understands, will I delay the resettlement o f some of the islands for many years.)I The Enewetak Advisory Group does not find i t possible t o develop reasonEblp cleanup guidance that would assure that radiation doses from transuranics t o future residents would not significantly exceed proposed EPA guidelines. Obviously, the more stringent the cleanup criteria, the greater the degree o f assurance; but uncertainties inherent in our present understanding of the problem preclude absolute assurance. One cannot predict,wi t h certainty the contamination levels that will exist in the islands after cleanup--this must be determined a t a future time. dietary habits of every individual w h o returns t o the islands. most important, many of the factors that are involved in movement o f transuranics in the environment and the deposition a n d retention of transuranics in human beinqs are n o t we1 1 established. One cannot predict the lifestyle and
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The Advisory Group i s of the opinion that the recommended cleanup criteria as discussed in item 2 below will r e s u l t in averaqe transuranic radiation doses t o 'subsequently exposed populations that wi 11 be commensurate with proposed EPA guidelines. The EPA considers its guidance levels t o be equivalent toa lifetime risk of about14 premature cancer deaths per 103,OOC persons exposed andto perhaps an equal number of genetic effects,although these estimates are based on many uncertain assumptions a n d are generally considered t o be quite conservative. An estimate of 14 cancers per 100,000 people would correspond toa 3% chance o f one cancer appearing ina population o f 200 people exposed toEPA guidance levels for their lifetime ; or expressed differently,to a probability of one cancer in every 2100 years (assuming a constant population size). 2 . Considering the physical and ecological 1 imitations t o removal of transuranics from the Enewetak Atoll, the Advisory Group recommends the following. From the information currently avai lable and used for dose assessment, we believe that cleanup of all one-quarter or one-half* hectare areas exceeding (with 70% confidence) 40 pCi/g of surface (0to3 cm.) soils of village islands will provide a reasonable exoectation that doses i n the bone and lung will be commensurate with the EPA guidance. I n terms of radiation dosesparing benefit t o future in habitat ants, cleanup ofa standard area on a village island is worth about4 times as much as cleanup toa given level onan agricultural island and12 times as much as cleanup o f the same area t o the same level on a picnic island. However, i n the light of existing contamination levels and available cleanup resources, it would appear that cleanup of all one-quarter hectare areas on village islands that exceed 40 pCi/g should receive first priority. Because the other islands may have increased use over that currently assumed, a second priority should be the cleanup of agriculture island half-hectare areas exceeding (with 70% confidence) 80 pCi/g. A third priority should be the cleanup o f picnic island resources are exhausted, some islands may notbe cleaned u p ; final dose assessment may indicate that these islands will have t o be anomalous since the concentration of transuranics appears t o be uniform with depth. cleanup for use as a village or agriculture island i s remote. However, the possibility of covering Pearl with the less contaminated soil from the village islands and, perhaps, from the agricultural islands should be considered for lowering the average surface contamination levels and reducing the logistics problems of transporting the soil from the other islands to Runit. We note that the soil profile on Pearl i s ble believe that the possibility of effective * 1 / 4 hectare i f IMP readings are taken on a 25 meter grid ; 1/2 hectare ifa 50 meter grid is used.
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3. I n the next few weeks the following should be accomplished t o improve the capability t o make dose assessments and guide cleanup activities : a. The analysis o f coconut and associated soils now i n progress a t LLL should be expedited. b . The urine bioassay data from Bikini should be obtained and analyzed f o r use by the Advisory Group. t o contpare estimates of the body burdens of transuranics inthe people who have been living on Bikini with the levels of transuranics in the environment a n d in the food harvested from Bikini islands. We believe i t would be informative c. Adata bank that accumulates all data from all organizations participating in Marshall Islands studies should be started and made, available toall persons involved inthe Marshall Islands program. - - I d . The organization and responsibilities of all DOE contractor personnel should be reviewed and clearly defined. Questions raised concerning possible bias i n IMP 241Am readings relative to soil Am andPu levels should be resolved. f . An inventory ofall current Enewetak projects for use by the Advisory Group should be provided. Further sbggestions will be forwarded fo7 lowing the next meeting o f the Advisory Group the week of June 5;1978. We plan t o review the calibration ofthe IMP and the Am-Pu soil data ; review new data Dr. Robison expects to bring from Enewetak; comment on the draft dose assessment report ; consider long-term issues related t o final phases o f the cleanup operations, certification and reassessment of dose based on contamination levels remaining after cleanup; and review orgdnizational responsibilities. 4. Plowing may reduce the surface s o i l concentrations and hence reduce the potential inhalation problem. Plowing i s unlikely t o reduce plant uptake, since i t merely redistributes the transuranics in the plowed area. Decisions on plowing should await the results of the proposed plowing experiment t o be conducted a t Enewetak. participate in the planning o f the experiment and analysis of the soil sampling data. Since DNA has requested advice on this technique, t h e experiment should be conducted as soon as possible. been drawn to our attention that on Enjebi, for instance, the depth to beach rock i s variable and hence consistent plowing t o depth may be We recommend that a statistician I n addition, experience has shown that there are large quantities o f unexploded ordnance and other dangerous hardware i n the subsurface. These pose t o the operators a potential risk that may outweigh the benefits tobe obtained from plowing. Task Group Members