THE EFFECTS OF FALLOUT RADIATION ON THE SKIN By Ronerr A. Conanrp, M. D. Brookhaven National Laboratory Fallout may be classified as the “worldwide” or the “close-in’’ type Worldwide fallout results from the dissemination of minute particles of radioactive material from nuclear detonations which slowlysettle out from the stratosphere and troposphere over the world. Due to the great dilution of this type of fallout and to the loss of activity with time evolved it does not impose a hazard to the skin but may result in a long-term hazard from internal deposition and possible genetic effects from low level irradiation. Close-in fallout is most likely to result from large atomic detonations in which the fireball comes in contact with the ground, causing large amounts of material to be drawn up into the cloud where the radioactive products adhere to the ground particles. Due to the relatively large size of these particles they may then be deposited within several kundred miles of the detonation. With this type of fallout there is areal hazard not only to the skin, but also from whole body penetrating radiation and from internal absorption of radioactive materials. The nearer the site of detonation that fallout occurs the greater is the hazard. The nearer fallout takes place earlier and is therefore more cases of human exposure to fission products or beta emitting material either accidentally or experimentally have heen reported [3-8]. Skin lesions in cattle and horses have also occurred fromfallout following experimental detonations at Alamogordo and in Nevada (9, 10]. Rather numerous experiments on the effects of beta radiation on the skin of animals have been reported and these data will be referred to, also [1115]. First, some of the physieal and biological factors related to skin damage from fallout will be discussed. The chemical and physical makeup of fallout will vary according to the type of terrain or soil over which the detonation orcurs. All fallout is particulate in nature, butthe size of the particles will depend to some extent on the physical and chemical characteristics of the soil. The fallout associated with the Castle detonation, March 1, 1954, was a white, pow- dery material largely composed of incinerated coral. Aside fram the radioaclive component the calcium oxide of the material was in itself irritating to the skin due (o its caustic nature. Moreover it was probably partly dissolved in the perspiration on the skin thus increasing its irritating action. (Incidentally, this may have active due to having undergone less radioactive decay and it is more concentrated since larger enhanced the radiation to the skin by bringing the radioactive materials in closer contact with The accidental exposure of some 240 Mar- of soil, other than predominantly coral, might vary considerably in chemical and physical makeup andirritation to the skin. Color and amounts (particularly larger particles) tend to fall out first. shallese, 28 Americans and 23 Japanese fishermen during Operation Castle, March 1954, affords our most extensive experience with fallout effects on the human skin and in this talk frequent references will be made to data obtained on these people [1, 2}. Several other the skin.) Fallout produced from other types particle size would also vary. For instance siliceous type soils would probably form much less irritating fallout. It goes without saying that for fallout to resultin gross skin damageit would have to be 135