. . TAD ae a . eae CUAREERa a as of shoes protected against foot lesions and index finger were common apparently to explain were the increased number of compared with the Marshallese. In this in the Japanese, but lesions of the hands between thumb due to handling contaminated fishing lines. Difficult lesions of belt line distribution in the fishermen as connection there were several American sailors on naval vessels who also developed mild pigmented lesions of belt-line distribution from fallout on the ships. From available information, the severity and course of the lesions in the Japanese fishermen appeared to be similar to those seen in the Rongelap Marshallese group. The lesions reported in this paper did not follow precisely the same course as those beta radiation lesions described by Knowlton, Robbins, and others and they presented certain unique features which merit further discussion. The early symptoms of itching and burning of the skin and eyes were probably due mainly to skin irradiation from the fallout material. However, the chemical nature of this material may have contributed to the irritation. It has been noted (12) that irritating chemicals applied during or shortly after irradiation enhance the effects of radiation. The lack of prominence of some of the lesions that dose reaching the papillary the beta radiation the dose of an erythema was notable, particularly in view of the severity developed. Wilhelmy (13). states that erythema only occurs when the layer exceeds a certain level. Perhaps due to the low energy of to the dermis was insufficient to evoke the response. On the other hand, the darkness of the skin and the development of hyperpigmentation may have masked an ery- thema. Microscopically, a superficial hyperemia was not a notable finding. Wirth and Raper (10) point out that they were umpressed in their studies on P** radiation of the human skin with the difficulty of distinguishing between true erythema and tanning, par— ticularly in the skin of brunette individuals. It was unfortunate that color filters were not available to aid in distinguishing an erythema as suggested by Harris et al. (14). In general, the length of the latent period before development of lesions of the skin is considered to be roughly inversely proportional to the dose of radiation (15, 16). In the present series of cases the relatively long latent period is suggestive of a low dose of radiation. Due to the wide spectrum of beta energies and particulate distribution of radioactive material, strict comparisons cannot be made with previous experience. However, the later deve lopment of less severe lesions in the Ailingnae and Rongerik groups as contrasted with earlier development of more serious lesions in the Rongelap group is in keeping with a lower skin dose in the former, and a higher skin dose in the latter. It is of interest, however, that the latent period was dependent to some extent on anatomical location. The foot lesions which were generally the most severe lesions encountered had a longer latent period than did the less severe lesions occurring elsewhere on the body. It seems likely that the greater severity of these lesions was due to a greater radiation dose to the feet since the feet received an appreciably greater contribution from close proximity to the contaminated ground. Perhaps such differences in latent period may be related to thickness of the epidermis, differences in length of mitotic cycles or other inherent characteristics of skin in different areas of the body. The histopathological changes noted, such as destructive and atrophic changes of the epidermis, disturbances in keratinization,and atrophy of hair follicles when taken together are consistent with radiation injury to the skin (9, 12, 17, 18, 19, and 20). Severe injury to the dermis and blood vessels was not observed. The minimal dermal injury with severe epidermal injury is in keeping with the large component of low energy beta material present, resulting in absorption of the greater portion of the energy in the epidermis. ig. Hyperpigmentation of injured areas was a consistent finding in the Marshallese and the American Negroes. Pigmented lesions were also observed to a lesser extent in the white Americans. Such pronounced pignentation is not characteristic of the usual lesions as described fol lowing exposure to beta or penetrating radiation, but may be more typical of the response to ultra soft roentgen or “Grenz rays” (21), | 435