20 gevity in the exposed Japanese people are notyet available. Degenerative diseases. An increase in degenerative diseases has been reported to occurin irradiated animals as evidence of premature aging.'”’* No such increase in degenerative diseases has been noted in exposed Marshallese compared with unexposed populations. Again, lack ofvital statistics hampersevaluation. Carcinogenesis and leukemia. Increased incidence of cancer in animals has been noted even with low doses of radiation.'*:?* Increased incidence of leukemia has been reported ‘n the exposed Japanese populations.**'?* In the exposed Marshallese no cancer (or leukemia) has been seen. Base-line studies have been carried out during the past two years for alkaline phosphatase levels of the neutrophils, and no consistent decrease of this enzyme indicative ofearly leukemia has been seen in anyin- dividuals. In addition, no increase in basophils in the peripheral blood (based on counts of 4000 white cells) has been noted. Decrease in alkaline phosphatase activity of neutrophils and increase in basophils were noted in Japanese cases that later developed full-blown leukemia.?*"6 In view of reports of thyroid malignancy and leukemia in individuals who as young children had received moderate doses of irradiation over the thymic region,*” the thyroid andits function are being studied in the Marshallese. Theestimated dose of 300 rep to the thyroid from iodine131 and gammaradiationis in the lower rangesreported to have resulted in malignancy. During the present survey, the exposed and unexposed people were screened for cholesterol levels of the sera. No abnormally highlevels indicative ofthyroid hypofunction were noted. (During the next surveyit is planned to determine protein-bound iodine levels in all children.) The incidence of leukemia and malignancy would be expectedto be relatively low with the dose of radiation received by these people, and a significant numberof cases would be seen only in a large population; therefore, the probabilities are good that such effects will not be observed in the Marshallese. Ophthalmologicaleffects: Visual acuity. In exposed teen-aged Japanese children, slight loss of visual acuity has been noted nine years after exposure.'* No differences were found in visual acuity in the exposed and the unexposed Marshallese children. Opactties ofthe lens. Radiation induced cataracts and polychromatic plaques of the lens have been observed in exposed humanbeings.”*?* Careful slit-lamp observations revealed no such changes in the Marshallese. Even if such changes do develop,it is probably too early to expect them yet. Genetic effects. Radiation induced mutations of the germ plasm in animals produce abnormalities in the offspring.***? However, extensive studies by Neelet al.* in the first generation children of exposed Japanese people have failed to show any significant abnormalities. In the case of the Marshallese, no anomalies have been obse~vedin the 13 babies born since the event. Unfortunately the productof the miscarriage and the two deadinfants were not examined. There are several factors which, offhand, would seem to makegenetic studies in the Marshallese likely to be fruitful: 1) The people live together as a unit and thus are easily available from year to year for study. 2) They appear to be a rather homogenousrace anthropologically, having lived in the Marshall Islands for about 2000 years with little outside intercourse. Intermarriage for such a period of time tends to produce genetic homogeneity. Height, skin color, and featuresare fairly uniform. 3) Consanguinous marriages are prevalent (first-cousin marriages on the maternalside only are indeed in good taste) and have produced a backlog of “bad” genes as evidenced by the high incidence of congenital anomalies. Radiation induced mutations wouldbelikely to be reinforced by such marriages. In spite of these factors, the small numbers of people involved in this study (compared to the large numbers in the Japanese studies) makeit unlikely that these studies will be fruitful. Superficial Irradiation of the Skin Thus far there has been noindication of any premalignant or malignant change grossly or microscopically in any of the residual areas of scarring atrophy and pigmentaberrationsresulting from the beta burns. The complaint in some individuals of further epilation during the past year was not substantiated by physical examination. The residual skin lesions are being kept under close surveillance for possible malignant changes. Exposureto tropical sunlight, trauma, andhigh incidence of skin infections may enhance such changes.