LAEA-SM-1L14/8 329 — et we = eee eee in the people extrapolated back to day 1 based on radiochemical urine analblvses. Lt can be noted thac the Larcent exposure was to the thyroid gland from radiogiodines. Ln addition co the dase imparted by 131,, the shorter-Lived isotopes b32y 1537, and 145 aise contributed substantially to the dose. Absorption of these iodine isotopes was both From inhalation as the radioactive cloud passed over and trom drinking contaminated water and eating contaminated food. Based on radiochemical urine analyses beginning at 15 days after exposure it was estimated chat about il.2 Ci of L3lt was accumulated in the thyroid gland at the time of the fallout. The adult thyroid was estimated to have received abouc 160 rads from the radioiodines in addition to 175 rads from whole body gamma irradiation, The dose to the much smaller glands of children was estimated to be considerably higher; in children less than 4 vears of ape the range was catimaced to be 700-1400 vads. Annual examinations have always included carerul thyroid evaluacion. 1,2]. Until 5 years ago che exposed people were considered to have nomal Numerous serum protein bound iodine determinations had been done and all en Since that time increasing numbers of cases of 19 with nodules and 2 other cases with atrophy of the gland with development of marked hypothyroidism. Only 1 of these cases with a nodular thyroid was in the lesser exposed Ailingnae group. Thirty-eight percent of the more heavily exposed group have displayed thyroid abnormalities. This includes one new case that was discovered in March 1969. A notable fact is that 90% of the children exposed at less than 10 years of age Table III shows the distribution of r in a a al the Of the 19 children in the 175 rad group exposed at less than 10 years of age, only 2 have failed to show clearcut abnormality. [t is noteworthy thac no thyroid abnormalities have been noted in children that received lesser exposure, i.e. che 6 children in the Ailingnae croup, the 54 children in the Utirik group and che 48 unexposed children in the same age range. Only 4 cases of abnormalities have been noted in the adults, 1 of these occurring in the lesser exposed group. It should be noted that a low incidence of thyroid enlargement does appear in older people (greater than 50 years of age) of the Utirik and unexposed population (See Table LIL). The chyroids of 12 children and 2 aduits have been subjected tc surgical exploration and the nodules removed. On surgical exposure, the thyroid gland was seen in most cases to be multinodular as shown in Fig. 2. Note the varied size of the nodules from several miilimeters to several centimeters, some being.cytstic, and some hemorrhagic. cords vid. sent The microscopic diagnosis in all but one case was adenomatous goiter, Fig. 3 shows the microscopic appearance with the wide variation in size of follicles closely resembling adenomatous goiter seen with iodine deficiency. Some pathologists claim to see radiation induced changes in the thyroid glands but others do not, Fig. 4 shows the microscopic appearance of the mixed papillary and follicular carcinoma with localized metastases ina en gee thyroid cases in the populations under study. wie pee have developed such abnormalities. <r ne ee ture ame age. al "ears in Serum cholesterol At the present time chere have been 21 cases of thyroic aanormalicies, in tion Le levels had been normal. nodularity of the thyroid gland have developed in the exposec people. h women urinary iodine excretion were within the normal range. 12 year old exposed giri. s posed ot We later discovered that Marshallese people in general have high levels of iodoprotein which may have masked an earlier hypothyroid tendency.;3] Dietary and Ten years after fallouc exposure nodular changes were noted in a c or wice appeared to be in the normal range for these people. memow: me eee om oe 2n and Lene ee ee thyroid tunction with no obvious evidence of any thyroid abnormality. esulted