43 The results of institution of thyroid hormone therapy in September 1965 areof interest. The rationale for its possible value in inhibiting the de- velopment of thyroid nodules appears to be ona firm basis. Bielschowsky®® and Astwood and Cassidy*’ have reviewedthe favorable effects of thyroid treatmentof patients with nodules of the thyroid gland. The only experimental evidence founddirectly applicable to the Marshallese situ- ation, however, is in a paper by Nichols et al.*° and unpublished data by Godwin®* demonstrating a reduced incidence of **'I-induced adenomas in rats treated with thyroid hormone. Although the children with thyroid nodules have thus far shown noevidence of thyroid carcinoma, experimental evidence strongly supports the belief that thyroid carcinoma may developin this exposed population. This likelihood led to the performanceof thyroidectomyon all children with thyroid nodules which had failed to disappear on suppressive therapy, even though earlier opeyative wy pe specimens had revealed only adenomatous changes. Since total thyroidectomy was not performed ex- cept in a few cases, even the operated patients will haveto be followed closely for the possible devel- opment of new nodules, and the suppressive effect of thyroid hormone replacement therapy may be important even in them. The results of the treatment of children with thyroid hormonewill also test the thesis of hypothyroid etiology of growth retardation. Early indications 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 presentedin pre- vious publications.’:‘° In this report several new criteria have been added, and furtherstatistical treatment of the 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 numberof peopie involved, lack of vital statistics on the Marshallese people, the language barrier, and uncertainty as to the exact ages in some of the older people. In selecting the criteria to be used, these difficulties limited the ex- tent and usefulness ofthose tests which require moti- vation and cooperation onthe part of the subject." In this report 14 criteria of aging are presented: 4 involving the special sense organs (visual acuity, accommodation, arcussenilis, and hearing loss); 4 involving neurological or neuromuscularfunc- tion (vibratory sense, reaction time, rapidity of movement, and handstrength); 3 involving the integument (skin looseness, skin elasticity, and hair graying); one cardiovascular test (systolic blood pressure); and 2 miscellaneoustests (serum choles- terol and body potassium). Two of the tests re- quired subjective evaluation on the partof the ex- aminer (hair grayness and arcussenilis); 7 required varying degrees of motivation and cooperation on the part of the subject (visual acuity, accommodation, hearing loss, vibratory sense, reaction time, neuromuscular function, and strength); AGING STUDIES During physical examinations, agingeffects are usually referred to in a general qualitative sense. In order to evaluate possible aging effects better, a more quantitative approach wasindicated. A large numberof criteria have at one time or another been regarded as being age dependent. These studies represent an effort to select criteria which could be used underthe conditionsof these ire examinations. The over-all objective has been to combinethe scores of the variouscriteria into one “average age score” for each individual and to compare scores in the exposed and unexposed groupsofsimilar age. An earlier attempt to quan- and 5 tests involved direct measurements (skin looseness, skin elasticity, systolic blood pressure, body potassium, and serum cholesterol). integument. A special caliper with constant spring tension was devised for skin examina- tions..-*°'! (1) Skin Looseness. The skin fold at the junction of the chin and neck was measured in millimeters as described previously. (2) Skin Elas- trcety. This was measured on the back of the hand by allowingthe caliper to pinch a fold of skin for *Several tests were tried and discarded for these reasons, including vital capacity and cardiovascular response to two-step test. Also not included were several tests that were difficult to quantify such as baldness and retinal and peripheralarterioscie- rosis. Other tests, such as serum folic acid and vitamin B,, levels, were eliminated because of poor correlation with aging.