compared to none in the unexposed group have occurred, Attempts to quantify aging changes did not indicate any premature aging effects in this exposed population. Studies of chromosomes and peripheral -blood cultures of the Rongelap people at 10 years post exposure indicated that small numbers of chromosome aberrations of the type usually associated with radiation exposure were still present. One of. the more important findings noted within a few years after radiation exposure was slight retardation of growth in some of the exposed children as evidenced by extensive anthropometric measurements and skeletal maturation studies. The retardation of growth was most '. notable in boys who had been exposed when less than 5 years of age, i _ particularly in two boys exposed between 15 and 18 months of age Thyroid lesions. 3. Lo. oon, | " Estimations of radiation dose to the thyroid gland. Unfortunately _ - te the calculations of dose to the thyroid from the absorption of radionuclides in the fallout. had to be based on radiochemical urine analyses that were obtained several weeks after the accident. It was known that there were several isotopes of iodine in abundance in the fallout (131,132,133, 1357), These iodine isotopes gained entry into the body from inhalation and from consumption of contaminated food and water during the two days before the people could be evacuated from the island. It was calculated that the ' thyroid gland on the average accumulated roughly 11.2 mCi of 13ly. on the first day of exposure. The extrapolated dose to the adult thyroid of the people on Rongelap was 160 rads from all the radioiodines plus 175 rads fron. ~ ganma radiation. | ; Due however, to the smaller size of the thyroid gland in | | | | ‘DOE ARCHIVES /83 LQ Pp.