AS The results of institution of thyroid hormone therapy in September 1965 are of interest. The rationale forits possible value in inhibiting the development of thyroid nodules appears to be ona firm basis. Bielschowsky’*> and Astwood and Cassidy" have reviewed the favorable effects of thyroid treatment of patients with nodules of the thyroid gland. The only experimental evidence found directly applicable to the Marshallese situauon, however, is in a paper by Nichols et al." and unpublished data by Godwin" demonstrating a reduced incidenceof '"'I-induced adenomas in rats treated with thyroid hormone. Although the children with thyroid nodules have thus far shown no evidence of thyroid carcinoma, experimental evidence strongly supports the belief that thyroid carcinoma maydevelop in nis exposed population. Thislikelihood led to the performanceof thyroidectomyonall children with thyroid nodules which had failed to disappear on suppressive therapy, even though earlier operative specimenshad revealed only adenomatous changes. Since total thyroidectomy was not performed except in a fewcases, even the operated patientswill have to be followed closely for tne possible development of new nodules, and the suppressive effect of thyroid hormone replacement therapy maybe Important even in them. The results of the treatment of children with thyroid hormone will also test the thesis of hypothyroid etiology of growth retardation. Early indi- cations are that the treatment is successful, since there has been a spurt in growth in the two most dwarfed boys in the year following institution of the treatment. tify these aging criteria has been presented in previous publications.”“" In this report several new criteria have been added, and further statistical! treatment ofthe data has been undertaken. Methods The aging criteria to be presented were recorded only in adults (20 years of age and older). Data were recorded on 91 adults, 36 in the Rongelap and Ailingnae exposed groups and 55 in the larger comparison population. The ages were reasonably well distributed except for the small number of people >60 years of age. The study was hampered by the small number of people involved, lack of vital statistics on the Marshallese people, the language barrier, and uncertanity as to the exact agesinsome the older people. In selecting the criteria t be used, these difficulties limited the extent and uscfulness of those tests which require moti- vation and cooperation on the part of the subject.* In this report 14 criteria of aging are presented: 4 involving the special sense organs (visual acuity, accommodation, arcus senilis, and hearing loss); 4 involving neurological or neuromuscular function (vibratory sense, reaction time, rapidity of movement, and hand strength); 3 involving the integument (skin looseness, skin elasticity, and hair graying); one cardiovascular test (systolic blood pressure}; and 2 miscellaneous tests (serum choles- terol and body potassium). Two of the tests required subjective evaluation on the partof the examiner (hair grayness and arcus senilis); 7 required varying degrecs of motivation and cooperation on the part of the subject (visual acuity, accommodation, hearing loss, vibratory sense, reac- AGING STUDIES tion ume, neuromuscular function, and strength): and 5 tests involved direct measurements (skin looseness, skin elasticity, systolic blood pressure, During physical examinations, aging effects are body potassium, and serum cholesterol). integument. A special caliper with constant In order to evaluate possible aging effects better, spring tension was devised for skin examina- usually referred to in a general qualitative sense. a more quantitative approach was indicated. A large number of criteria have at one time or in- other been regarded as being age dependent. These studies represent an eflort to select criteria which could be used under the conditions of these examin.tions. The over-all objective has been to combine the scores of the various criteria into one “average age score” for each individual and to colmpare scores in the exposed and unexposed groups of siniilar age. An earlier attempt to quan- tions.’ °"*! (1) Shen Looseness. The skin fold at the juncuion of the chin and neck was measured in millimeters as described previously. (2) Skin Elas- uicily This was measured on the back of the hand by allowing the caliper to pinch a fold of skin for *Several rests were tried and discarded far these reasons, a1 cluding vital capacity and cardiovascular response to two-step test Also nat included were several tesis that were difficult ta quantify such as baldness and retinal and peripheral artenose leross Other tests, such as serum folie acid and vitarnin By were chminated because of poor correlation with aging levels