FP D ON ON __.-1 INTRODUCTION Until recently it has been generally assumed that injury to the skin from ionizing radiation was not a serious hasard associated with the detonation of nuclear devices. However, in 1954 the importance of this hazard be- came apparent when widespread radiation lesions of the skin developed in a large group of people accidentally exposed to fallout radiation in the Marshall Islands following the experimental detonation of a large muclear device. In addition to exposure of some 239 Marshallese people and 28 Americans, there were 23 Japanese fishermen exposed on their fishing boat. The radiation ef- fects and skin lesions in this latter group have been described by Koyama et al. and others, Prior to that time, a limited mmber of skin lesions on the backs of cattle (Bird; Paysinger gt al.) and horses (Atomic Energy Commission Report) has been noted from fallout following experimental detanations. In addition, exposure of the hands of several individuals who had carelessly handled fission product samples from a detonation resulted in the development of severe lesions (Knowlton gt al.). Other cases of beta lesions in human beings ofaccidental or experimental nature have been described by Robbins et al.; Crawford; Low-Beer; Wirth and Raper; Conard and Tessmers; Kepp; Griffith get al. and Kepp, Miller and Reich; Nodles and Witten et al. Some of the rather mumerocus studies on the effects of beta radiation on animal skin are reported by Henshaw; Raper and Barnes; Snider and Raper; Lushbeugh; Moritz and Henriques; Paysinger ot al.3; Bruess Cloudman et al.; Glucksmann; Kharchenko and Venolurov; Koletsky et al.; Minisovs Passonneeu and Hamilton; Smmbik et gl. and Unger et al. The recent accident in the Marshall Islands affords the first example of large mimbers of lesions of the skin in human beings from fallout. Studies of