BLEACHING OF HAIR 191 red-haired individuals to sun exposure is, in fact, due to the lack of pigment and/or the inability of their skin to produce it in response to sun irradiation. Dispensing with the speculation of the involvement or non-involvement of pheomelanin in terms of solar damage, let us turn to the conclusions of our work in the field of hair. First, pheomelanin in hair is more resistant than eumelanin to oxidative or photo-degra- dation. This is independently corroborated by a series of in vitro experiments with the isolated pigments. Secondly, modification of the physical properties of melanin pigments, such as their solubility, can result in a significant change in their spectral characteristics. REFERENCES (1) T. B. Fitzpatrick, P. Brunet, and A. Kukita, "The Nature of Hair Pigment," in The Biology of Hair Growth, W. Montagna, Ed. (Academic Press, New York, 1958), pp. 255-303. (2) G. Prota, Recent advances in the chemistry of melanogenesis in mammals, J. Invest. Dermatol., 75, 122-127 (1980). (3) M. R. Chedekel, P. W. Post, R. M. Deibel, and M. Kalus, Photo-destruction of pheomelanin, Photochem. Photobiol., 26, 651-653 (1977). (4) M. Osber, D. Patil, and L. J. Wolfram, An overview of physicochemical properties of melanins, VI European Workshop on Melanin Pigmentation, Murcia, Spain, 1985. (5) J. A. Maclaren and B. Milligan, Wool Science, the Chemical Reactivity of Wool Fiber (Science Press, Marrickville, NSW, Australia, 1981), pp. 219-234. (6) L. J. Wolfram, "The Reactivity of Human Hair. A Review," in Hair Research, Orfanos and Mon- tagna, Eds. (Springer Verlag, 1981), pp. 479-500. (7) E. Tolgyesi, Weathering of hair, Cosmetics and Toiletties, 98, 29-33 (1983). (8) L. J. Wolfram, D. Patil, and L. Albrecht, Communication to the XIII International Pigment Cell ConjSrence, Tucson, Arizona, 1986. (9) T. Sarna and R. C. Sealy, Photo-induced oxygen consumption in melanin systems. Action spectra and quantum yields for eumelanin and synthetic melanin, Photochem. Photobid., 39, 69-74 (1984). (10) T. Sarna, I. A. Menon, and R. C. Sealy, Photo-induced oxygen consumption in melanin systems. II. Action spectra and quantum yields for pheomelanins, Photochem. Photobiol., 39, 805-809 (1984). (! 1) L. J. Wolfram and K. Hall, Isolation and identification of the protein component of hair melanin. J. Soc. Cosmet. Chem., 26, 247-254 (1975).