Hign grcieim_ tee nny | 1 June 1950 Alvin C. Graves, d-Division Leader dack Aeby, T. NM. Whit, STUDY OF REC File Cle L aa Group H-] ENI ADGE RECORDS 4 > ar REPERENOK: B-l “Yer some 2 ne tinethere h| as beenstrong reason to» suspect that radiation”Z . 7s e@xposare et Eniwetok, as estizated from file badges, has been over~ ‘ estimated, Jt was suspected that this situation arose on avcount t.: the impossibility of providing valid sontro] blanks, because of the.” variable amount of heat or moisture fogging that eccurred there on film badges wrn in the absence of gemma radistion. To put this suspicion to a statistical test, there is presented below a Table com the badge results for unexposed and possibly exposed men. The co on covers January, February, March 1950, during which period most of the grading wrk on the Shot Islands occurred. The unexposed badges are those worn by a group of about 100 men mown to have spent practically all of this period on Parry Island. Each badge was worn for a period of approximately one month. There is better than a 30% probability that the tabulated numbers, or more discrepant ones, would occur from purely random sampling. From a statistical viewpoint there is therefore no evidence that anyone received measurable gaxma ray exposure during this period. The statistical test is, however, quite weak for the few cases of relatively large apparent exposure, and we are certainly not justified in concluding that no radiation exposure eccurred. It is quite possible that the five highest values represent real radiation exposures. They are, however, well within the monthly permissible level, 1.2 roentgen. We are justified in soncluding that gamma radiation was a negligible factor in the siseable number of apparent exposures in the intermediate region (4.9. those int ed as in the range .06 - .10 reastgen, or ; - possibly somewhat higher). REPOSITORY onleS,y AkSVL COLLECTION sox BEST COPY AVAILABLE 72a] erinwe. ML FOLDER boon HoU u SC C7 wWetetk ye aKa Se ( Ke