38 EFFECTS OF IONIZING RADIATION and the severe, spotty epidermal injury with minimal dermal injury are notable. The particulate nature and uneven distribution of the fallout material was responsible for the spotty nature of the lesions and, the large component of soft energy beta radiation was responsible for the greater epidermal injury. The prominence of pigmentary changes is probably related to race.* It is generally conceded that blondes with light pigment are more sensitive to radiation than brunettes (17). Lastly it is quite evident that sensitivity and response varied with anatomic location, In Table 3.3 are listed the approximate surface skin doses required to produce recognizable epidermal injury from beta radiations in ani- in comparing animal lesions from knowndoses with lesions in the exposed individuals in this study in order to estimate the skin dose, since species differences in response may exist, and certain radiation factors are not. well established, such as accurate knowledge of the beta spectrum of the fallout material and close rate. Comparison with humandatasutfers from wide differences in radiation energy and doses re- ported and methods of determining the rep dose. The lowincidence of infection of the radiation burns is probably due to their superficial nature. Ulceration and partial healing preceded the time of minimal granulocyte counts. It is conceivable, however, that with higher Table 3.3.—Surface Doses Required to Produce Recognizeable Epidermal Injury INVESTIGATOR Henshaw, et al (22)_______.) Raper and Barnes (23)_____Raper and Barnes (23) _____ . Snider and Raper(24)____.Raper and Barnes (23)__..__| Lushbaugh Moritz and Moritz and Moritz and Moritz and Moritz and Moritz and (25)__..____--_ Henriques (26)__; Henriques (26)__| Henriques (26)__| Henriques (26)_.| Henriques (26)__| Henriques (26)..| ANIMAL ISOTOPE Rats_.______-_ Rats___.____Mice________Mice_.______Rabbits.____. Sheep_._____Pigs_-_..-... Pigs. _...._.. Pigs-...___._-| Pigs..._____Pigs. ..____-Pigs-_..-___- mals. It is apparent from the table that beta ray energy is of considerable importance in determining the degree of injury. According to Moritz and Henriques, the difference in dose be- tween that required to produce threshold skin damage and that for permanent damagein pigs is 500 to 1000 rep (26). One is not justified * Reported clinical experience with radiation skin lesions is based predominantly on the response of white-skinned people, whereas the lesions described herein were observed primarily in the Marshallese, a highly pigmented people. Pp2 AVERAGE ENERGY (Mev) 0.5 SuRFACE Dosk (REP) 1, 500-4, 000 ps p32 p32 0. 5 0.5 0.5 4, 000 2, 500 2, 500 p22 0.5 5, 000 Sr’e S35 Co” Cs? Sree ye y" 0.3 0. 05 0. 01 0. 2 0. 3 0.5 0.7 2, 20, 4, 2, 1, 1, 1, 500-5, 000 000-30, 000 000-5, 000 000-3, 000 500-2, 000 500-2, 000 500-2, 000 doses of whole-body radiation, the defenses against infection might have beensufficiently impaired to have resulted in serious complications from skin lesions of the severity encountered. Severe radiation injury is known to predispose to cancer. The probability of the development of malignancies at the site of healed lesions is unknown. Certain factors appear to decrease the probability: (a) The majority of the lesions were superficial. (b) Visible signs of chronic radiation dermatitis are absent in