35 A ee Table 3b sa ee Residual Gamma Activity, in counts/min/kg, in Marshallese After Subtraction of K'’, Zn*, and Cs?! amined. In addition, groupsof children at Utirik, Majuro, and Kwajalein Atolls were examined as Age, yr . Rongelap exposed Rongelap unexposed Ailingnae Vurik their accidental exposureto fallout. During the 1959 survey 76 exposed persons, including their children, and 166 unexposed Rongelap people, who served as a comparison population, were ex- 1-13 15 36.1 21.4 172 8.3 37.9 35.0 43.9 11.7 with age or sex. No significant difference was found between the Rongelap exposed and unexposed groups, which implies that no residual Zn** activity remains in the Rongelap people from their original exposure. The 1959 mean body burden of Zn** was 0.44 controls for the growth and development studies on the exposed Rongelap children. The 1960 survey was brief, only the exposed people being examined. As a result of their exposure in 1954, many of the Rongelap people had experienced early symp- toms related to the gastrointestinal] tract and skin. Later they developed a significant depression of their peripheral blood elements commensurate with the calculated dose of gammaradiation (175 r to 64 people and 69 r to 18 people), and beta burns of the skin along with spotty epilation. In addition, radiochemical analyses of urine samples uC as compared to 0.36 pC in 1958. Thus Zn*® showed that they had acquired a low-level body steady-state equilibrium with the environment, as is also the case with Cs'*’. Since the source of Zn*® is ish, which continue to be a dietary staple, the Zn” value can be expected to increasestill further. such as loss in weight of several pounds in most of the people during thefirst several monthsafter body burdens do not seem to have reached a The mean Utirik Zn*® level in 1959 was about one-third the Rongelap mean value. Although Cs'*? and Zn** comprise the major portion of gamma-emitting radionuclides present in the Marshallese (aside from the naturally oc- curring K*°), residual gammaactivity is still present after subtraction of K*°, Zn**, and Cs'*’ con- tributions from the total spectrum in each sub- ject (see Table 36). Analysis of the residual spectra did not indicate any readily identifiable photo- peaks in the short counting time employed (5 or 10 min). This short counting time, along with the difficulties discussed earlier in exact calibration of absolute activities, makes the identification of minor photopeaks very difficult. Most of the difhculties can be circumvented in future field trips by the use of longer counting times, the use of an 8-in. crystal, duplication of the geometry by use ofthe same standard chair, and a moreprecise calihra- ; tion of the phantom. Summary and Conclusions Continuing annual medical surveys of the people of Rongelap Island were carried out in March 1959 and March 1960, 5 and 6 yearsafter burden of radionuclides. Certain other findings~ were possibly related to their radiation exposure, exposure and suggestive evidence ofslight lag in growth and development of the children based on studies of height, weight, and bone development (but inconclusive pending verification of exact ages of some of the children). In spite of the depression of hemopoiesis, no signs of radiation illness developed in the people related to such depression, and no deaths occurred that could be related to their radiation exposure. No specific therapy was given. Recovery of the peripheral blood elements, particularly lymphocytes and platelets, was very slow over the ensuing years. The beta burns, which appeared about 2 weeks after exposure, were, for the most part, superficial in nature and healed in several weeks, with only a fewlesions showing later persisting changes. Specific therapy was not necessary In most cases. The hair regrew normally, beginning at 3 months after exposure. The internally ab- sorbed radionuclides caused no knownacuteeffects and were excreted remarkably fast with barely detectable activity being found a year or twolater. On return of the people to Rongelap Island the very low levels of radioactive contamination remaining there resulted in a rise in their body burdensof cestum-137, zinc-65, and strontium-90. The 5- and 6-year post-exposure surveys were aimedprimarily at evaluating the general medical