Table 13 Residual Beta Burns Subject Subject No. & sex No. & sex 2M Roughening and pigment variation on front of neck Several pigmented macules ACF.* Perianal depigmentation. 39 F 3M Mottled pigmentation both axillae. Pigmented area behindleft ear. 49 F 11M Pigment changesleft ACF, dorsum first right 34M F Scarring and pigmentation left ACF. 39 F M Pigmented patch back of neck. Mottled pigmentation and depigmentation on back of neck. Died 1968. 63 F Slight rugosity and pigmented ridges on back of neck. M toe; pigmented nevi axilla. Pigmented macules left axilla, front of neck and chest. Depigmentedspots shaft penis. 24F Slight pigment variation on front of neck; sev- 25 M Scarring dorsum left foot. Biopsy at 2 years hvalinization of connective tissue and thickening 64 F eral pigmented macules dorsum left foot. of blood vessel walls of cutis. Died 1956. 65 F Slight roughening and pigmentation back of neck; pigment variations and slight hyperpigmentation dorsum right foot. Numerous pigmented macules both sides of neck and a few on arms and ACF. Mottled pigmentation and depigmentation on front of neck. Died 1972. 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. 26M Scarring and depigmentation of dorsum right 67 F Depigmentedscars dorsum left foot. foot. Died 1962. 75 F Slight pigmented area dorsum right first toe. 34 F Slight roughening and pigmentation back of neck. Moles on front of neck. 78F 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 developmentof 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 12 months in all cases except for one man whostill has spotty epilation on the backofhis head. Follow-up skin biopsies of residuallesions, studied at 6 months? and at 3 and 10 years®-1! post ex- posure, histologically showed excellent healing, but in most cases residual evidence of exposure wasnoted, such as epidermal!atrophy andthickening 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 still a distinct possibility, since its latent period may be as long as 48 years and may, on the average, be longer than for some other types of radia- tion-induced malignancy. Manyof the youngerexposed Marshallese still have a longlife expectancy. There are several reasons, however, whyskin cancer maynot occurin 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 development of 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 absenceof chronic radiation dermatitis are factors against the development of skin cancer; nevertheless, persisting cellular changes are seen in their residual skin lesions. If, as Teloh et al.3! believe, skin cancerre- sults from direct irradiation of the epidermis without necessarily severe dermalinjury, its occurrence would be morelikely. The appearanceof nevi in