19 Psychic effects. The Japanese people exposed to the atomic bombings suffered acute psychic trauma from the horrifying experience they underwent and multiple injuries, burns, loss of homes, lack of food, disease, etc. In contrast, the Ron- gelap people were hardly aware of anything of great significance happening atthe timeof exposure, and it was with relative calm and rapid adjustment that they went to their new homesto living conditions generally superior to those they 3 mC of radiation to the gastro-intestinal tract duringthe first day after radiation, but againthis dose wastoo low for any acuteeffect. Internal concentration of other isotopes was far below any levels necessary to produce acute or subacute effects. LATE EFFECTS turned to their homeisland andareliving in com- Investigations in animals and to a lesser extent in man haverevealed certain late or long-term radiation effects. Some of the more fundamental of these are discussed below in relation to the Marshallese experience. of returning to their home island, the psychic ef- Penetrating Radiation were accustomed to. It is true that they have suffered some nostalgia for their homeisland but always with the knowledge that they would return. (At the time of this writing they havere- pletely rebuilt homes.) If there had been no hope fects might have been serious. There waslittle real concern expressed about their radiation exposure. It would seem, therefore, in the case of the ex- posed Marshallese that there has beenlittle or no apparentpsychic effect of this momentousevent. Superficial Beta Radiation Exposure The acute phase of the beta burnsof the skin was over by several monthsafter exposure with sausfactory healing taking place. No further breakdown or developmentof chronic radiation dermatitis has been noted in anyoftheselesions. It is of interest that about twice the incidence of pingueculae and pterygia had been notedin the exposed Rongelap people as in the unexposed groups during the past two years. Since many of the people received a certain degree of beta radia- tion to the mucous membranes of the eyes (as evidenced by lachrymation and burning during the first day or two), it is possible that this may have influenced the increased incidenceofthese abnormalities. internal Radiation Exposure In an acute fallout situation, iodine-131 is prob- ably the most important absorbedisotope to be considered during the early period. In the Marshallese, the 300 rep estimated to have been delivered to the thyroid glands (100 to 150 from I"! and 175 r from the gammadose) wasfar too low to produce any acute effect. (Possible long-term effects of this dose will be discussed below.) The conglomerate of ingested isotopes delivered about 5001213 Premature aging and shortening of life span have been shown conclusively to occur in animals followingirradiation.'*:'"'* Establishmentofcriteria for quantification of aging is notoriously difficult. Therefore, litthe or no data suitable for precise measurementof agingeffects have been collected in the Marshallese. Accommodationtests ofthe eyes and audiometric analyses were carried out, but no detectable differences in these parameters were found in regard to age between the irradiated and unirradiated groups. As to premature aging, the senior author has observed these people at repeatedintervals since their radiation exposure, and they do not appearto have agedfaster or look older than similarly aged unexposed Marshallese persons. No doubt the subtle changes which occur with aging would bedifficult to detect overthis period of time. Estimates of the shortening oflife span in the humanbeing have varied considerably in different reports.*°-?* In the Marshallese at three years post-exposure, only oneof the 64 heavily exposed group had died. This compares favorably with five deaths among the 157 Utirik people who received the smaller exposure. Even though there are quite a few old people in the irradiated group, it is probably too soon to expect meaningful longevity data. However, it would appear that some of the upper estimatesoflife span shorteningin humanbeings are too high (someinvestigators estimate 30 or more days per r), since it would seem that even in this small population more evidence of aging or life span shortening ofthis magnitude would have been noted. Data on lon-