6 December 1967 ADULT HYPERTHYROIDISM is no reason to doubt that what we see in patients whoare allergic to iodides is the action of an iodoprotein formed in these patients. showing functional and neoplastic changes in the thyroid as a late effect of radiation. More recently, there have been a number of both retrospective and prospective make iodinated proteins of this type, and release them into the circulation; and, to some extent, there is a cross relation between a variety of such iodinated proteins. Thus, if patients with Graves’ disease produce a spectrum of antibodies against thyroproteins, some of which are iodinated proteins, it might not be surprising that some patients with this disorder would show allergic reactions to iodine. established that infants who receive neck irradiation later develop a higher incidence of cancer of the thyroid gland (41, 42), There appears to be an increase in cancer of the thyroid in the Japanese people that were exposed to the atomic bomb radiation (43). As for internal exposureof the thyroid gland, the development of thyroid nodules and possibly one case of malignancy have been noted in children, years after receiving radioiodine therapy for hyperthyroid- Wedo knowthat hyperthyroid patients DR. WERNER: We ought to discuss, briefly, “I. Dr. Conard from the Brookhaven National Laboratories has been involved with the Marshallese fallout problem together with Dr. Rall. | wonderif he @ would like to say something about radia“Y. cion effects from this isotope upon the thyroid. DR. ROBERT CONARD, Brookhaven studies in human beings. It has been clearly ism (44). Also, in recent years, an increas- ing numberof cases of hypothyroidism are being reported following such treatment in adults. The recent development of thyroid nodules in the Marshallese has been of particular interest. We carry out annual medical examinations of 86 people who were accidentally exposed to radioactive fallout 12 years ago, in 1954. Most of these National Laboratories, Upton, New York: people received an estimated dose of 175 years it has become apparent that the fore they were evacuated from theirisland, Until relatively recently, the thyroid gland had always been considered a rather radioresistant organ. However, in the past few gland is more radiosensitive, particularly in regard to late effects, than had been thought. This applies both to external and internal radiation of the gland. Radiation may affect the thyroid cells in several possible ways: by directly killing the cells, by injuring the genetic mechanism so that at the time of cell division the cell may die or a mutant form maypersist, or radiation may simply impair the func-_ tion of the cells. Chromosomal aberrations have been demonstrated in irradiated thyroid cells and numerous histological changes in thyroid tissues have been noted following irradiation. These are characterized by cellular necrosis, nuclear changes, « ‘4brosis, blood vessel changes, etc. There have been many animal studies css ar AN ; 1773 Uist 04 rads of whole body y-radiation, 8-burns of the skin, and internal absorption of radioisotopes. During the two days be- they absorbed significant amountsof radioiodine from consumption of contaminated food and water. Estimates of thyroid dose were arrived at by radiochemical analyses of the urine done at 15 days and longer after exposure. It was estimated that the adults received about 160 rads from radioiodines plus the 175 rads of y-radiation to the gland. The children, having smaller glands, naturally received larger doses per unit weight of gland. A three- to four-yearold child was estimated to have received between 700 and 1400 rads from radioiodines plus the external gamma dose. About three years ago, wefirst noticed the development of nodules of the thyroid gland in these people (40, 45, 46). Since that time, the incidence has increased un- |