C. SKIN EXPOSURES Background information Radioactive fallout debris emits beta particles some of which emerge from fallout material with sufficient range ‘in air to reach from the ground to the head of an erect man. However, in human tissue the range of these beta particles is limited principally to a very small fraction of an inch so that only the skin is irradiated when fallout debris is outside the body. Further, there has been no observed skin damage except from relatively heavy fallout where the radioactive fallout mate- rial has remained in direct contact with the bare skin. Even a single layer of cotton clothing apparently greatly reduces the radiation dose from beta particles. Approximately a 500 roentgen dose delivered by beta particles from fallout debris to the base of the outer layer of the skin tissue is required to produce erythema (reddening of the \ wv FIGURE 4b.—Same case six months later. Damage healed with normal pigmentation except for small spots marking the areas of more severe damage. skin). A similar result from X-rays would require less radiation dose. At somewhat higher doses from beta particles emitted by fallout debris epilation (loss of hair) may occur. At still higher doses more serious skin damage may be expected with such symptoms as ulceration. The Data Skin damage from beta burns was first observed on some eattle grazing near the Alamogordo, New Mexico Test Site following the first nuclear detonation on July 16, 1945. Epila- tion was observed in patches where the fallout debris had supposedly remained in place. VOL ee A cane ar eae OTS FIGURE 4a.— Highly radioactive fallout material remained in contact with the feet causing severe skin damage —28 daysafter initial contamination. The hair grew back, white in color, and no other adverse effects have been observedin the cattle or their offspring. Other “beta burns” have been observed on a few cattle in 1952, on horses in 1953, and one horse in 1955 in Nevada. All of these, as well as the Alamogordo cattle were grazing within 9