vA mvelogenous form, since his past: hemograms showed a fairly consistent depression of neutrophil counts compared with these of other exposed boys of the same ave. The inability to demonstrate clear-cut aging ef- fects ia the exposed group in spite of repeated atlempis with a variety of tests is in accord with the generally negative results of similar attempts in the much Jarger expased Japanese populations. The absence of radiation-induced cataractsis nut unex pectedsince the dose tu the lens was prob- ably below threshold and neutrons (knows to have a higher RBE for cataract induction than wanna radiation) were not divolved in the Mar- shallese exposure. to the higher dose to the cluld’s thyroid because of its sutaller size. The rapid growth of the glands during childhood probably increased the chances for neoplastic changes. Vhe growth retardauon in some of these children was thought to be related to reduced thyroid function resulting in lower hoe: sone levels. This deliciency was not recognized during the early years because of falsely high PBI levels resulting from unusually high todopratein levels, which turned out to occur generally in the Marshallese and are now being further studied. Mast of the thyroid glands of the exposed people undergoing surgery contained multiple nodules or arcas of adenomatous change. MLany microscepic areas, although considered benign, were composed of discrete areas of atvpical cells, suggestive in £. THYROID EFFECTS The high incidence of thyroid neoplasms (in 27 of 8b exposed Rongelap peuple, including 3 with carcinomas) and the development in some children of hypothyroidism and growth retardation provide clear evidence for the seriousness ofthyroid some Ges of malignant potential, The cisk of developing benign and malignant neoplasms in the Rongelap people appeared to be about the same as that noted in peaple exposed to x-radiation. Clinical experience with MT sug. gested that the risk would have been less, but the higher energyof the short-lived isotopes ofiodine injury due to radioiodine absorbed fromfallout as- (particularly !!T, PW aod 21), resuliing in medical studies in the population been instituted soon after the exposure and continued to the present date. the extent of thyroid etlects might nut the thyroid, is thought tu have been the important factor in increasing the number of thyroid abnormalities above that expected from similar doses sochated wilh atomic detonations. Had not careful have beea discovered, Vheroid exposure is likely to be greater whea individuals are exposed within 100 to 150 mites of the bomb ifdetonated near the ground. In such higher dose rate and more uniform exposure off from MT alone. fis not unreasonable to speculate that (uanor incidence ia the Marshallese would have been considerably smaller if only "1 had been invelved in the exposure. ‘he lesser amount of short-lived tadine isatopes in the Utirik expo- situadians, if lethal exposure to penetrating radiaVion does not occur, the principal hazard appears sures (because of the later arrival of the fallout) leukemia, Since the latter is ultivvately fatal, it is the dose effeet to their thyroids, but the muniber af to be the late development of thyroid tumors and may have been an important factor in reducing tore serious than Chvroid maligaancies, most of which are well diilticntiated and have an excellent prognosis. Phe relative incidence of thyroid malignancies from cadiauon appears to be about people involved is too small far any firm conclusan lo be drawi. ‘Treatment of the expascd Rongelap people with higher than vhe martalite from it, OF 40) cases Unsroid hormone has been of beneficin enlianci growth and development inthe growth-retarded children aad tnomatntaining a onortial metabele slic The operated cases. Etis notcertaln wheiber 1974, and only ene death had been attributed to noxdules. the same as thatofl ukeriaenatper rad’ bo GF The incidence of thyroid cancer is considerably wong the cxpasca Japanese, $4 were living ina this cause. No evidence of thy roid dysfunction had been noted at the time of diagnosis. bathe Marshallese reduced function was not found in two of the cancer cases exposed as adults, but was an the cast exposed us achild. The high incidence of thyroid clfeets in children exposed at <0 vears of ave was no doubt related Wohas prevented the development of thyroid The documentation of these tivroid effects has inpartaney notenty for she peapte involved but also for the advancement of inedical knowledge aod for planning with reward to Civil Defense and remotely possible future accidents tavealving release of radiotudines (ce. froma nuclear puwer plant). The Marshallese accident represents ex+