Thyroid Neoplasia*as Late Effect of Exposure to Radioactive Iodine in Fallout | “e Robert A. Conard, MD; Brown M.Dobyns, MD; and Wataru W. Sutow, MD Accidental exposure of people of Rongelap Island to radioactive fallout and particularly to radioactive iodines in the fallout has resulted in the development of thyroid abnormali- ties in 21 of 67 of these people, 3 with malignantlesions, 16 | with benign adenomatous nodules, and 2 with atrophy of the gland with hypothyroidism. The preponderanceoflesions occurred in children exposedat less than 10 years of age who hadreceived a greater thyroid exposure. Growth retardation associated with hypothyroid tendency was noted in some children who appearto be responding favorably to thyroid hormone medication. Thyroidectomy, partial to complete, has been carried out on 18 patients. Risk for thyroid cancer from radioactive iodine exposurein this group does not appear to be very different fram that reported following x-irradiation. Teo neoplasia developed recently in Marshallese people of Rongelap Island who were accidentally exposed to radioactive fallout in 1954 during the testing of thermonuclear devices in the Pacific proving grounds. During the two days before evacuation 64 people From the Medical Department. Brookhaven National Laboratory. Upton, NY (Dr. Conard); Case Western Reserve University School of Medicine at Cleveland Metropolitan General Hospital, Cleveland (Dr. Dobyns); and the M. D. Anderson Hospital & Turgor Institute, Houston (Dr. Sutow). Reprint requests to Brookhaven National Laboratory, Upton, NY 11973 (Dr. Con- ard). 316 on Rongelap Island received a whole-body gamma dose of about 175 rad and 18 other Rongelap people on a nearby island received about 69 rad. In addition they sustained serious skin exposure and significant internal absorption of radionuclides. A third population on the island of Utirik, 150 miles east of Rongelap, received only a slight exposure and this group will only be referred to briefly in this communication. By 1957 the radioactive contamination of Rongelap Island had reduced sufficiently to allow the people to. be returned. At JAMA, Oct 12, 1970 ® Vol 214, No 2 JO1280b that time a new village was con- structed for them. Fortunately more than200 Rongelap people(relatives _ of the exposed group) who had not been exposed to fallout returned also and have served as an excellent comparison population. Annual medical examinations during the past 15 years have documented the acute and late effects of this exposure on these populations."* The people of Rongelap had early acute signs of exposure including anorexia, nausea, and vomiting followed later by the development of significant but transient depression of the formed elements in their blood. However, no infections or bleeding tendencies were noted and no deaths occurred which could be attributed to radiation exposure. No prophylatic or specific therapy was given. Radioactive contamination of the skin resulted in the developmentof lesions (“beta burns”) and spotty epilation of the head in the majority of the people between two and four weeks following exposure. The skin lesions healed within several weeks and the hair regrew by six months. Some of the people had slight residual atrophy, scarring, and pigment changes of the skin. The acute effects appeared to be more severe in Thyroid Neopiasia—Conard et al