-9devised by Rerson. Rates of flow of Lol, among compartments refleck the physiological State of hyperthyroidism and the development of a radiation effect.] in draft form in the hands of Dr. Brill. the results from these analyses. move to Two manuscripts have beem Publication has been delayed. by The results are prepared describir. Ur. Brill's recent Brookhaven National Laboratory. The Development of Neoplasms of the Thyroid Following Irradiation At least two Circumstances may have an important bearing on of development of neoplasms following 131 I. One concerns the damage to the cell whidh results in in- pairment to the synthesis and output of thyroid hormone, resulting]in a secondary stimulus to the gland from the pituitary (TSH). The other concerng the intrinsic nuclear damage that results in the production of abnormalities witlin the cell, or failure of cell division. In referring here to damage to the cellg, it is important to keep in mind that the effects produced are often not rapidly lefhal to the cells; rather the cells survive for long periods with only mild impairmenf of fimction. If the development of benign or malignant neoplasms is dependent on tion then prolonged mild hypothyroidism should be an important pr the other hand, if the cellular damage is so devastating as to caugbe severe hypothyr: ism, then that same damage would be so crippling as to hinder the fevelopment of a n growth which is dependent on cell division. Our studies have shown that neoplasm formation in the rats refuires an interval of 14 to 18 months from the time of the irradiation. The lengthy clearly shown in the Marshallese where, in spite of thorough ann the first palpable nodule was not found for 9 years and neoplasms at 26 years. (See twenty-six year report). physical examina Bre still appeari Many of the experimental ideas for our laboratory have come from our experience in operating the thyroid Marshallese. finterval in man is fneoplasmsof the The maximal estimated dose to the thyroid in the Marshallese was 1,15¢