Table 13 Residual Beta Burns Subject No. & sex Subject No. & sex 2M Roughening and pigment variation on fro: of neck. Several pigmented macules ACF.* Perianal depigmentation. 39 F 3M Mottled pigmentation both anillae. Pigmented 49 F area behind left ear. Slight roughening and pigmentation back of neck; pigment variations and slight hyperPigmentation dorsum night foot. Numerous pigmented macules both sides of neck and a few on arms and ACF. HIM) Pigrnent changesleft ACF, dorsum Arst right 54M Mottled pigmentation and depigmentation on front of neck. Died 1972. 17F Scarring and pigmentation left ACF. 59 F 20M ‘Pigmented patch back of neck. Mottled pigmentation and depigmentation on back of neck. Died 1968. 23M Pigmented macules left axilla, front of neck and chest. Depigmentedspots shaft penis. 63 F Slight rugosity and pigmented ridges on back 24F Slight pigment variation on front of neck; several pigmented macules dorsum left foot. 25 M toe; pigmented nevi axilla. Scarring dorsum left foot. Biopsy at 2 years hyalinization of connective tissue and thickening of blood vessel walls of cutis. Died 1956. 26M Scarring and depigmentation of dorsum right foot. Died 1962. 34F Slight roughening and pigmentation back of neck. Moles on front of neck. 64 F 65 F of neck. Mole back of neck; slight pigment variation and afew maculesfront of neck. Mole back of neck. Pigment variation and roughening front of neck. Not apparent now. 67 F Depigmented scars dorsum left foot. 75 F Slight pigmented area dorsum right firsttoe. 78 F Numerous pedunculated moles on sides and front of neck. 79M Pigmented and depigmented scar posterior surface left ear. “ACF = antecubital fossa. mentation, but the scars have faded and repigmentation has tended to occur in most cases. Noevidencehas been seen for the development of chronic radiation dermatitis or premalignant or malignant changesin any case, and most people now show little residual evidence of lesions. Hair of normal color and texture regrew by 6 to [2 months in all cases except for one man whostill has spotty epilation on the backofhis head. Follow-up skin biopsies of residual lesions, studied at 6 months? and at 3 and 10 years®-11 post exposure, histologically showed excellent healing, but in most cases residual evidence of exposure was noted, such as epidermal atrophyand thickening of the corium with collagen bands, although little evidence of significant vascular changes was ‘seen in the corium (see Figure 19). Though no malignant changes in the skin have thus far been noted in the Marshallese, the de- velopmentof skin cancer due to radiation exposure is sull a distinct possibility, since its latent period may be as long as 48 years and may, on the average, be longer than for someothertypes of radiation-induced malignancy. Manyofthe youngerexposed Marshallese still have a long life expectancy. There are several reasons, however, why skin cancer may not occur in the Marshallese. The low average energy of the beta rays resulted in much less damage to the dermis than to the epidermis. This would make the prognosis favorable if, as manyinvestigators believe, the developmentof skin cancer requires sufficient damage to the dermis to impair nutrition of the epidermalcells. In the Marshallese the superficial nature of the skin burns, rapid healing, and absence of chronic radiation dermatitis are factors against the development of skin cancer?°; nevertheless, persisting cellular changes are seen in their residual skin lesions. If, as Telch et al.3! believe, skin cancerre- sults from direct irradiation of the epidermis without necessarily severe dermal injury, its occurrence would be morelikely. The appearance of nevi in