PHOTOPROTECTION BY HUMAN MELANIN 353 mented and non-pigmented skin through photoacoustic spectroscopy. We feel confi- dent that the apparent absorption spectrum of epidermal melanin pigmentation is es- sentially correct. In comparing the edge of the absorption spectrum of EMP with that of the erythema action spectrum it was found that the latter is a slower function of wavelength than the EMP apparent absorption spectrum. Therefore, the much higher sensitivity of human skin to UVB than to UVA can only be partially accounted for by the absorbance of EMP. Morison (16) has considered the possible roles of melanin in human skin and concluded that photoprotection from the UV is not its primary function. CONCLUSIONS a. Human epidermal melanin pigmentation, in its natural state, absorbs light differ- ently than does synthetic and extracted melanin. b. Human EMP provides less protection in the wavelength range 305-280 nm of the UVB than previously assumed. At these wavelengths the epidermal proteins are the primary absorbers. c. UVB photoprotection is important to dark- as well as lighter-skinned individuals. ACKNOWLEDGMENTS We express our gratitude to Dr. M. M. Selim, Chairman, Department of Derma- tology, A1-Sabah Hospital, for his constant support and encouragement. We also thank Mr. Iqbal Sadiq for his tireless and inspired assistance. This work was partially sup- ported by the Environmental Protection Council of Kuwait. REFERENCES (1) R. R. Anderson andJ. A. Parrish, The optics of human skin,J. Invest. Dermatol., 77, 13-19 (1981). (2) P. Amblard, J. Beani, R. Gautron, J. Reymond, and B. Doyon, Statistical study of individual variations in sunburn sensitivity in 303 volunteers without photodermatosis, Arch. Dermatol. Res., 274, 195-206 (1982). (3) S. Shono, M. Imura, M. Ota, S. Ono, and K. Toda, The relationship of skin color, UVB-induced erythema, and melanogenesis, J. Invest. Dermatol., 84, 265-267 (1985). (4) K. H. Kaidbey, P. Agin, R. M. Sayre, and A.M. Kligman, Photoprotection by melanin--A com- parison of black and Caucasian skin, J. Am. Acad. Dermatol., 1, 249-260 (1979). (5) W. Westerhof, D. Babelaar, R. H. Cormane, J. Langelaar, and J. Hup Middelkamp, The protective role of epidermal melanin in a patient with porphyria variegata and vitiligo, Acta Dermatovener., 61, 23-31 (1981). (6) J. C. van der Leun, Delayed pigmentation and ultraviolet erythema, Photochem. Photobiol., 4, 459-464 (1965). (7) N. Kollias and A. Baqer, On the assessment of melanin in human skin in vivo, Photochem. Photobid., 43, 49-54 (1986). (8) N. Kollias, A. Baqer, and K. Razi Naqvi, Fiber optic spectrophotometer for noninvasive transmission and diffuse reflection studies, Spec. Lett., 19, 149-165 (1986). (9) N. Kollias and A. Baqer, Spectroscopic characteristics of human melanin in vivo, J. Invest. Dermatol., 85, 38-42 (1985).

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