47 8S and Residval Skin Lesions il, The ns some 20 exOn recovery of acute beta bur “Xposed strable ad with w residual d Marshallese continued to sho changes, and scarring, atrophy, and pigment roscopic biopsy studies revealed residual mic the lechanges. However, at no time have any of atitis n sions developed into chronic radiatio derm ologihist or or shown any evidence either grossly ber d num ease cally of malignant change. An incr e hav es mol of benign pigmented maculae and the s of ed area diat been noted in previously irra skin, particularly in the neck region. he sup18 to be se chil- d a pos- "On the culated the ex- LO cases ifferent ses, the x posure Hematological Findings Mean peripheral blood counts in the Marshallese exposed group have tended to remain below those of the unexposed group followingtheinitial that re- 1 of the acute depression. A slight degree of depression of remarkid unex- # / greater corneal oup. itis & any sig- re. Asa ™ Is in the > exposed ifferences sularly in cd group. vere enuv doses of =cks to in1 the basis nexposed ased with vho were consider- ibly aged sed males sed males. houghtto sual func- 1 sex hor- vity of the OP iationsof »Olychro- Koen ap geinthe J white cells and platelets has consistently persisted (Figure 41). This implies a residual radiationeffect on the bone marrow. Other evidence in support of this was thefinding, on bone marrow examination of some of the exposed people, of an alteration in the myeloid-erythroid ratio (increased red cell precursors), presence of cells with abnormal! chromatin material and double nuclei, and aiso increased mitosis. Examination of peripheral blood smears revealed increased numbers of atypical lymphocytes in the exposed group and an unexplained increase in these forms in the children of exposed parents. Also, chromosome studies of lymphocytes in cultured peripheral blood at 10 years post exposure revealed a high incidence of aneuploid cells "and 2-hit aberrations in the blood of the exposed group. Dental Findings Dental examinations showednosignificantdifferences in caries rate between exposed and unexposed groups. However, the incidence andseverity of peridontal disease was slightly greater in the exposed group.It is not known whetherthis finding ts related to radiation exposure. The poor oral hygiene generally observed in the Marshallese resulted in a high caries rate in the teenage children, severe peridontallesions in the adults (heavy calculus and loss of alveolar bone), and edentulous mouths in the aged. Radiation exposure did not appear to have affected developing denti tion in the exposed children, I00b304 Aging Studies Aging studies have been included in several annual surveys to detect the possible influence of radiation on development of premature aging. In the earlier studies various parameters usually associated with aging were measured at the time of physical examination. The values of some of the parameters were estimated and scored on a 0 to 44+ scale (such as graying of the hair, senile changesof theskin, balding,etc.), and the values of others were measured (skin looseness, skin elasticity, accommodationof theeyes, visual acuity, arcus senilis, hearing, blood pressure, neuromuscular function, hand strength, vibratory sense, neuromuscularreaction time, body potassium by spectrographic analysis, etc.). Comparison of these values in exposed and unexposed individuals of the same age showed no apparentdifference. Most of the measurements showed varying degrees of correlation with aging. A biological age score was calculated for individuals and groups by use of an average percentage score. During the 1967 and 1968 surveys the age-related and/or radiationinduced aging effect on immunological competence wastested in 100 unexposed and 50 exposed people (Figures 34 to 37). In the unexposed group decreasing immunological competence with aging was indicated by decreasing percentage transformation of peripheral blood lymphocytes by phytohemagglutinin stimulation, indicating decreasing immunological competence of lymphocytes; and by significantincrease in gamma globulin,reflected also in increases in IgG and IgA immunoglobulins and K light chains. These latter findings were believed to be associated with age-accumulated ef- fects of repeated infections and perhapsalso with increased autoummunereactions. The irradiated population exhibited certain significant differences from the unexposed population which may indicate radiation effects. They had relative depression of platelet and neutrophil levels of the peripheral blood. As pointed out before, some slight degree of depression of peripheral blood elements has, however, been noted since exposure. Compared with the unexposed population the exposed group was also found to havereduced gammaglobulinlevels (including IgG,IgA, and K light chains on immunodiffusion analysis), more pronouncedin older age groups, which may indicate a radiation-induced aging effect. Evidence, however,for relative loss of immunological capac-