BACKGROUND: Ultraviolet light induces sunburn, ageing of the skin, pigmentation and even promotes skin cancers. As there has been a recent decrease in the ozone layer surrounding the earth, increasing attention has been given to the effects of ultraviolet light on the skin. Through human epidermis, ultraviolet light is reflected, scattered, absorbed or transmitted. In caucacians, the rate of transmitted ultraviolet light A from the epidermis to the dermis is 50% and the rate of transmitted ultraviolet light B is below 10%. OBJECTIVE: The purpose of this study was to evaluate the transmittance of UVA and UVB on Korean normal epidermis. METHODS: Pure epidermis was obtained from normal human epidermis by suction of blisters in 12 patients with vitiligo. All specimens were irradiated respectively with UVA and UVB and the amount of transmitted energy was measured. RESULTS: 1. The transmittance of UVA energy density by normal epidermis was 47.7+11.2% of irradiated UVA energy. 2. The transmittance of UVB energy density by normal epidermis was 32.4+3.4% of irradiated UVB energy. CONCLUSION: UVA energy transmission through normal epidermis of Korean is less than those of Caucacians but UVB energy transmission through nor mal epidermis of Korean is more than those of Caucacians. It is suggested that this could be an important basic data to study for photoaging and photoprotection in Korean population.
Blister ; Dermis ; Epidermis* ; Humans* ; Pigmentation ; Skin ; Skin Neoplasms ; Stratospheric Ozone ; Suction ; Sunburn ; Ultraviolet Rays ; Vitiligo

Recently, exposure to sunlight is increasing due to expanded life time, outdoor leisures, and reduced sun protective ozone layer. Sunlight can produce not only benefit but also various kinds of harmful effect, such as skin carcinogenesis, photoaging and immunologic alterations, These effects can be minimized by sunscreens. This article reviews the methods to measure a suncreens efficacy and factors influencing the measurement. I. Measurement of photoprctective efficacy 1)The sun protective factor(SPF): The SPF is defined as the ratio of the UVB doses required to produce minimal erythema dose(MED) with sunscreen applied to without it. However, the exact procedures are not estabiished and the value is varied by methods. 2)Photoprotective factor A(FFA): In spite of its clinical improtance, evaluation of UVA protection rernains a problem due to its physiologic features. The methods to measure UVA protection are by the use of erythemal, phototoxic and pigmentary rections. 3)Outdoor measurement: It is ideal to measure the photoprotectiveness outdoor but a wide variation in value results from radiance sources and environmental factors. II. Factors influencing the evaluation The radiance sources, individ zal sensitivity to sunlight, product components and various environmental factors can make differences. Conclusion As more sunlight, exposure, he irnportance of photoprotection is increasing. The exact methods to measure the protectiveness of UVA and UVB should be established, especially adjusted to Korean people
Carcinogenesis ; Erythema ; Leisure Activities ; Skin ; Solar System ; Stratospheric Ozone ; Sunlight ; Sunscreening Agents