22 ing on their homeisland wassmall, it was decided to allow the people to return. CONCLUDING REMARKS Theincreasingly widespread uses of radioactive sources in research andindustry increase the possibility of exposure of people to various forms of ionizing radiation. Therefore, greater knowledge of such effects on humanbeingsis badly needed. Considerable research is being carried out on effects of radiation on animals, but there are obvious limitations in extrapolating such data to the human species. Human experimentation, particularly with regard to whole-body radiation effects, is limited to therapeutic use of radiation in diseased people. Thoughsuchdataareuseful, they must be evaluated with caution. The most valuable information about human radiation effects, therefore, has come from people irradiated from atomic bombs such as the Japanese people of Hiroshima and Nagasaki and the Marshallese, from a few isolated laboratory accidents, and from individuals having ingested radium. The group of irradiated Marshallese people offers a most valuable source of data on human beings who have sustained injury from all the possible modesof exposure-penetratingradiation, beta radiation of the skin, and internal absorption of radioactive materials. The acute and subacuteeffects of these different forms of exposure have been well documented and for the most part have subsided. Even though,as pointed out, the radioactive contamination of Rongelap Islandis considered perfectly safe for human habitation, the levels of activity are higher than those found in other inhabited locations in the world. The habitation of these people on the island will afford most valuable ecological radiation data on humanbeings. Since only small amounts of isotopes are necessaryfor tracer studies, the various radioisotopes present can be traced from the soil, through the food chain, and into the humanbeing, where the tissue and organdistribution, biological half-lives, and excretion rates can be studied. Such investigations will be done by the use of whole-body gammaspectroscopy of the people and of sample materials, and by radiochemicalanalysesofsoil, food, and humanexcreta. Several factors favorably influence these studies on the Marshallese. The exposed and unexposed . Rongelap people are interrelated and represent a remarkably homogeneouspopulation. Theylive underthe same environmental, sociological, and economic conditions and are likely to remaintogether as a groupindefinitely. As contrasted with the Japanese, the dose of gammaradiation received is reasonably well established. Also in contrast to the Japanese, these people have been subjected to only minimal psychic and no physical trauma. In view of these facts, continued medical sur- veys of the Marshallese people are anticipated on an annualbasis. Summary Results are reported of a medical survey on the Marshallese people exposed to radioactive fallout three years previously. Examinations werecarried out at Majuro in the Marshall Islands on 82 people from Rongelap who had been exposed to the heaviest fallout and on a comparison population of unexposed Rongelap people matchedfor age and sex. A Navy LST wasused for the second phase of the examinations to examine 144 people of Utirik Island whoreceived the least fallout. The survey showedthatall the irradiated Marshallese people were makingsatisfactory recovery from their radiation exposure. The followingis a summary ofthe findings on the Rongelap people. ACUTE AND SUBACUTE EFFECTS Penetrating radiation Diseases. In general the incidenceofdisease, in- fectious and noninfectious, was about the same in the exposed as in the unexposed group. No symptoms werepresentthat could berelated to radiation effects. Several interesting findings were noted in both the irradiated and unirradiated groups: the incidence of congenital anomalies was high; peptic ulcer and psychic disturbances wererare; the incidence of dental caries was very high; and intestinal parasitism was widespread. Nutrition. Nutrition appeared to be as good in the exposed as in the unexposed groups. Growth and development. In the exposed children from about 4 through 9 years of age there was a slight lag in bone maturation (based on x-ray studies of the left wrist), and these children were