39 These data also maybe useful as a baseline, should genetic changes appearin later generations, pos- sibly related to radiation exposure. IV. Thyroid Findings A. EARLY FINDINGS Examinationsfor possible thyroid abnormalities were an importantpartof the program from the beginning. At the time of the accident it was not considered likely that the thyroid had received a sufficient dose of radioiodine to result in abnormalities. In retrospect this proved to be quite wrong, since thyroid injurv and its sequelae have been the most serious late result of the fallout exposure in the Marshallese people. A chronological reviewof events leading to the development of thyroid abnormalities follows. Beginning several years after exposure it was noted that 5 of 19 children exposed at <10 years of age showedretardation of growth.®-16 This was particularly notable in the boys exposed at <5 years of age (Figure 26). The cause ofthis retardation was not immediately apparent. It was recognized that thyroid hormonedeficiency from thyroid injury could result in such growth retardation. However, examinations during this early period did not reveal any thyroid abnormalities, and the PBI levels in these children as well asin all Marshallese were in the normal to high range. The grows retardation gradually became mere apparent, and at we es Height (cm) Figure 27. Growth-retarded boys exposed at age | year (No.3, left, and No. 5), 6 months after start of treatment at age 11 (1966). Figure 26. Statural growth in Rongelap boys exposed at <5 years of age, 1958-1967. . Figure 28. Bone dysgenesis of heads of humert in subject No.5, typical of hypothyroid disease (1965). PRIVACY ACT MATERIAL REMOVED