thyroids was first observed nine years after exposure among these people. By 1967 fourteen of sixty-eight of the most heavily exposed had develcpedf nodules which were of sufficient concern to reguire exploretion. Cne carcinema had fleen found. AS a result of the survey early in 1969, five more individuals in this] populaticn were found to have developed thyroid masses which we felt should be explored. Four were from the more heavily exposed group on Fenselap atoll, l.e. sever§l hundred to Tourteen hundred rads estimated dose to the thyroid; ard one on Utirik|atoll who hed probably received 30 rads. ‘These were brought back to the U.S. for sp@cial study at Brookhaven National Laboratory. Because of our interest in and labgratory studies of radiated thyroids, the patients were brought to our institution in Jeptember, 1363 for surgical exploration. Three of the five proved to have lesions of|the thyroid which were malignant (two Rongelap; one Utirik). One of these had ext@nsive regicnal metastases. A fourth patient possessed several nodules, one of which fas very small and has prempted sericus consideration that this might also be malignagt. Autcradicgr==-. were immediately prepared in additicn to a variety of cbservations componly made on tissues from our animals (not 3y-thymidine). Several of these thyroidg had many minut= sclid cellular hyperplastic lesions, none of which tock up significantfamounts cf radioiodine. Many of the lesions were papillary in structure and sugg lesions of milticentric origin. All of these thyroids (except the woman from Utirik) showed the large bizarre nuclear forms repeatedly observed under this qgontract in animals and humans that had received lly, Mention was made in the past annual report of a preliminary revieq of the Marshalss thyroid tissues for evidence of radiation effect based primarily on thq bizarre nucieaT forms and other subtle changes as observed in rats and human thyroid t§ssue. Study has just been completed in a formal manner. To test the validity of these criteria as evidence of radiation e Robert Conard of Brookhaven National Laboratory assembled multiple sli thyroid of the Marshallese, of some thyroids of Japanese atomic bomb This ect, Dr.. s of each thyroids of the Utah-Nevada children who may have been exposed (mentioyfed elsewhere in this report - fron Dr. Marvin Rallison) and of miscellaneous unexto thyroids collected from elsewhere in Utah. More than 190 individual skh des, completely disguised as to identity, were submitted to this writer for review and ppraisal as to evidence of radiation effect in them. All slides were graded as to poh tive cr negativ= evidence of radiation effect, and where positive, the evidence was fur er graded on 2 basis cf +, ++, or +++; + being the slightest evidence and +++ being pypnounced evidence. After individual slides were graded and reported to Dr. Conard, multiple slides that consideralle weight of evidence for radiation effect upen the presence bf Lymohocytes, had come from the same thyroid were grouped together (still as unkncwng) and ’ reappraised. Although in most cases the ratings on several slides fro individual were similar, it was appropriate to affix a single rating t In no case was the rating changed more than one degree to arrive at a for a given thyroid. The results show that all of the Marshallese exc: identified as having received radiation exposure. Among these was a ‘4 who had been exposed and several years later had died of other causes oF Majuro atoll where a post mortem provided the tissue which was free of gross nodularfity. Several of the unexposed thyroids and a few of the Utah-Nevada group were grade as Ccubtful or +. Because of the correlation of the observaticns, Dr. Conard subs uently obtaine= the individual theoretical records of rad dose delivered to the thyrol (based on body burden determined scme days after the removal of the Marshallese pecpl from Reongelap) ed to correlat= The degree of change attributed to radiation effect in the thyroids leulated. Mos in surprisingly precise fashion with the degree cf exposure previously of the Japanese tissues were graded only + or 0. “here as some observe s have placed