Date, On Exposures The work of Henriques* suggests that at the depth of U.Uu9 mm in iiving porcine skin (maximm thickness of epidermis) that “l4uu_/3uu roentgen-equivalent—beta" (delivered over short periods of time so that they may be assumed to be instantaneous) is required to produce recognizable transepidermal injury. The curve of biological damage rises go on to develop chronic radiation dermatitis persisting for months, The preceding discussion suggests that, using the gamma dose rates listed in these criteria, which are based on an estimated 10 roentgen infinity gamma dose, as high as 2,000 reps might be delivered to the ‘basal layer of the epidermis over a period of time covered by the lifetime of the radioactive material. There have been instances where the calculated infinity gamma dose in areas where personnel were present around the Nevada Test Site have reached 12-15 roentzgens but there have been no Imown cases of beta burns in these areas. The number of persons involved in these areas cf highest contamination was relatively small, perhaps a few dozen, and with an observed duration of fallout of about one hour it is possible that they were not in a positicn to receive the full fallout. Likewise, minute areas of the skin may have been so affected yet not detected or reported. In other areas encompassing some 2,000 people the infinity gamma dose was about eight roentgens and no instances of beta injury appeared. *Op,. cits re the epidermis may be expected to exfoliate and in the majority of cases = rather sharply so that at a dose of just under 2000 rep (at 0.09 m),