22 Table 13 Residual Beta Burns Subject No. & sex 2M Subject | No. & sex Roughening and pigmentvariation on front 39 F Slight roughening and pigmentation back of 3M Mottled pigmentation both axillae. Pigmented area behind left ear. 49 F Numerous pigmented macules bothsides of neck and a few on arms and ACF. 11M Pigment changes left ACF, dorsum first right toe; pigmented nevi axilla. 54M Mottled pigmentation and depigmentation on front of neck. Died 1972. tv F Scarring and pigmentation left ACF. 59 F Mottled pigmentation and depigmentation 20M 23M. of neck. Several pigmented macules ACF.* Perianal depigmentation. Pigmented patch back of neck. Pigmented macules left axilla, front of neck .9 24F ; . and chest. Depigmented spots shaft penis. . ; ws Slight pigment variation on front of neck;. sev:7 eral pigmented macules dorsurn left foot. 25 M 63 F neck; pigment variations andslight hyperpigmentation dorsum mght toot. on back of neck. Died 1968. Slight rugosiry and pigmented ridges on back of neck. 64 F Mole back of neck; slight pigment variation and afew macules front of neck. Mole back of neck Scarring dorsum left foot. Blopsy at 2 years hyalinization of connective tissue and thickening 65 F Pigment variation and roughening front of neck. Not apparent now . 26M Scarring and depigmentation of dorsum right 67 F 75 F Slight pigmented area dorsum right first toe. 34F Slight roughening and pigmentation back of neck. Moles on front of neck. 78 F Numerous pedunculated moles on sides and front of neck. 79M Pigmented and depigmented scar posterior surface left ear. of blood vessel walls of cutis. Died 1956. foot. Died 1962. PP Depigmented scars dorsum left foot. *ACF = antecubital fossa. mentation, but the scars have faded and repigmen- tation has tended to occur in most cases. No evidencehas been seen for the developmentof chronic radiation dermatitis or premalignant or malignant changes in any case, and most people now show little residual evidenceoflesions. 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 back ofhis head. Follow-up skin biopsies of residual lesions, studied at 6 months* and at 3 and 10 years$-1! post exposure,histologically showed excelient healing, but in most cases residual evidence of exposure was noted, such as epidermalatrophy and 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- velopmentofskin cancer dueto radiation exposure is still a distinct possibility, since its latent period 20Gb 114 maybe as long as 48 years and may,on the aver- age, be longer than for someother types of radiation-induced malignancy. Manyof the youngerex- posed Marshallese still have a longlife 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 many investigators believe, the development of skin cancer requires sufficient damage to the dermis to impair nutrition of the epidermalceils. In the Marshallese the superficial nature of the skin burns, rapid healing, and absenceof chronic radiation dermatitis are factors against the developmentof skin cancer*9; nevertheless, persisting cellular changes are seen in their residual skin lesions. If, as Teloh et al.31 believe, skin cancerresults from direct irradiation of the epidermis with- out necessarily severe dermal injury, its occurrence would be morelikely. The appearance of nevi in