city of vital statistics in the Marshallese and the small numbersof people involved. No diseases, infectious or noninfectious, have developed which could be related directly to radiation effects. The incidence of diseases in the exposed people noted during the +-vear survey, as in previous surveys, remained about the same as found in the unexposed comparison population. A limited survey of immune responses of the exposed groupat 3 years post-exposure’ showedthat the antibody response to tetanus antigenic stimu- lus was not significantlydifferent from the response in the unexposed group. Three deaths have occurred in the exposed people. Thefirst was in a 46-yr-old man whodied of hypertensive heart disease | vear post-exposure. examined by comparing differences between the mean peripheral blood elementlevels of this group and the corresponding group of unexposed women with differences between levels in exposed and unexposed men of the same age group.Nosignificant differences were seen. It might be questioned whether or not the present low body burden of radionuclides might contribute to delayed recovery of hemopoietic function. Admittedlylittle is known of possible effects of such lowlevel exposure on the marrow, particularlyif, as in the case of the Marshallese, a significant dose of penetrating radiation has been previously received. However, it is not believed that the small amount of additional radiation im- posed on the marrowfrom this source would be He had hadthe disease at the timeofirradiation. sufficient to retard hemopoietic recovery. post-exposure. He was a diabetic of long standing and died apparentlyof coronaryheart disease. A third occurred in April 1958, after the present survey, in a 35-yr-old man from the group that received 69 r, due to pneumonia complicating a exposure revealed a drop in the mean leukocyte The second occurred in a 78-yr-old man at 2 years Hematological examination at 3 years post- counts compared with 2-vear levels in both the ex- posed and unexposed people. The possibility was considered that a population trend downward in leukocyte counts was occurring such as has been severe case of chickenpox. In none of these cases was there anydirect evidence that death was due seen in Japan.'* However, this does not seem to be the case, since leukocyte levels this year are not further depressed compared with previouslevels. elements of the exposed people over the 4-year skin subsided rapidlv, and only 12 casesstill show much more rapid recovery seen in animalstudies, but generally conforms to the recovery pattern possible that the acute stage of the beta burns may have caused some of the fluctuation observed in ’ showed earliest recovery (by'1 year post-exposure), epilation, complete regrowth of hair occurred by 6 months post-exposure. No acute effects of the internal absorption of to radiation exposure. Lag in recovery of some of the peripheral blood period since exposure is in sharp contrast to the seen in the Japanese exposed at Hiroshima and Nagasaki. In the Marshallese the myelocyticseries with lymphocytes and platelets exhibiting much slower recovery. The present hematological examinations reveal that the mean leukocyte level has The acuteeffects of the beta irradiation ofthe residual scarring and pigment abberation. It is the white blood cell count. In those showing radionuclides were observed. virtually recovered to the control level, but more LATE EFFECTS posed group. Thrombocyte production still does seen, but certain of the more fundamentalof these individuals had lower counts than in the unex- not appear to have recovered completely asevidenced by the lower mean levels in the exposed people both individually and as a group. As has been pointed out, however, the slightly lower peripheral blood level of these elements has not impaired in anyobservable waytheir resistance to disease. There has been considerable speculation as to whether there is a lowered reserve hemopoietic capacity in the marrowof the exposed people. The effect of the natural stresses of childbearing and menstruation in women 15 to +5 vears of age was 5904253 Late effects of radiation exposure have not been effects that have been observed in animals and to a lesser extent in man will be mentioned in relation to the Marshallese. Shortening of life span'*-*? has not been evident. The 3 deaths that have occurred in the exposed population do not appear to indicate a higher mortality rate than seen in the comparison popu- lations. From these observations it would appear that some of the higher estimates oflife shortening per roentgen maybe too high. Premature aging'~-’”is difficult to assess. From observations over the past 4 years the impression is