FADING OF ARTIFICIAL HAIR COLOR 423 We have also conducted experiments to ascertain the effect of formulations containing other DVB-UVA photofilter systems, such as that composed of 1 % dimethylpabaimi­ dopropyl laurdimonium tosylate (1 %) and benzophenone-3 (1 %) (see formulation in the Experimental section). Natural white hair was dyed with a red dye one group of samples was irradiated under artificial sunlight and shampooed every eight hours, and the second was treated with 0.17 g of formulation per gram of hair, using an oil-based formulation, and irradiated and shampooed similarly to other samples. A reduced treatment amount was employed in order to simulate the practical usage conditions and to minimize the unfavorable tactile modification of the hair. After 24 hours of total irradiation, samples treated with the oil formulation had an average color loss of 4.59 ± 0.54 while samples not treated with the formulation had an average color loss of 4.82 ± 0.83, amounting to 4. 5 % color protection. After 48 hours of irradiation, the average color losses were 7 .22 ± 0.25 and 8.24 ± 0.47 for the treated and untreated samples, respectively, which corresponds to 12% color protection. Finally, color fading could be reduced by including cationic polymers or silicones, in combination with photo-absorbers, in the photoprotection products (24,25 ). Such raw materials are typically included in the commercial formulations of conditioners, fixa­ tives, or shampoos. The mechanism of color-loss prevention could be explained by a "sealing effect" of absorbed layers of polymer or silicone slowing down the diffusing out of hair dyes during shampooing. The use of film-forming polymers and/or oils could also improve the uniformity of distribution of photo-absorbers, resulting in a greater attenu­ ation of incident light. In one experiment, natural white hair, dyed with medium auburn hair color, was treated with 2% benzophenone-4 and 2% benzophenone-4 in the form of a salt of PVP/DMAPA copolymer. After 16 hours of irradiation and two shampooings, the dE was 7 .9 ± 1.0, 7 .1 ± 0.8, and 6.4 ± 0.8 for untreated, benzophenone-4 treated, and benzophenone-4-polymer-treated hair, respectively. Thus, the observed photopro­ tection effect of 19% for benzophenone-4-PVP/DMAPA was greater than that (10%) measured for benzophenone-4 alone. In another experiment, natural white hair dyed with medium auburn hair color was treated with 2% benzophenone-4-PVP/DMAPA copolymer 2% benzophenone-4-PVP/DMAPA copolymer-2% amodimethicone and 2% benzophenone-4-PVP/DMAPA copolymer-2% trimethylsiloxyamodimethicone, which, after 16 hours of irradiation and two shampooings, gave a dE of 5.5 ± 0.6 (14% protection), 4.8 ± 0.9 (25% protection), and 5.6 ± 1.1 (12.5% protection), respectively, versus a dE of 6.4 ± 0.6 (0% protection) for the untreated control. Such result suggests that cross-linkable, aminofunctional silicone can lower color loss when used in combi­ nation with a photo-absorber. CONCLUSIONS The main conclusions from this study can be summarized as follows: • Fading of artificial, permanent hair color is greatest for hair subjected to both irra­ diation and shampooing, and significantly smaller for hair undergoing only irradia­ tion or washing. Color loss has been found to be dependent upon the hair type employed, with hair melanin displaying significant protection of artificial hair dyes. Artificial hair color based on pyrazole intermediates showed the deepest fading as a

424 JOURNAL OF COSMETIC SCIENCE result of shampooing and irradiation/shampooing, probably because of the high water solubility of the coloring products and intermediates. • Photofading of artificial hair color is caused by UV and visible light and can be reduced by 27% to 63%, depending on the irradiation dose, by a complete elimi­ nation of UV radiation by the use of an inorganic glass filter. According to theoretical calculations, the attenuation of UV light (290-400 nm) by organic photofilters depends on the amount deposited on the hair and varies from 10% to 25% for UVB filters and 40% to 60% for UV A filters at the deposition amount of 30 mg/(g hair). • The use of organic photofilters such as benzophenone-3 and benzophenone-4 affords color protection ranging from 15% to 40% for the deposited amounts of photofilters from 5 mg/(g hair) to 25 mg/(g hair). REFERENCES (1) J. Jachowicz, M. Helioff, C. Rocafort, A. Alexander, and R. K. Chaudhuri, Photodegradation of hair and its photoprotection by a substantive photofilter, Drug Cosmet. Ind. (December 1995), and references cited therein. (2) T. Gao and A. Bedell, UV damage to natural gray hair and its photoprotection,j. Cosmet. Sci., 52, 103 (2001). (3) S. B. Ruetsch, Y. Karnath, and H.-D. Weigmann, Photodegradation of human hair: An SEM study, J. Cosmet. Chem., 51, 103 (2000). (4) L. J. Wolfram and L. Albrecht, Chemical and photo-bleaching of brown and red hair,]. Soc. Cosmet. Chem., 82, 179 (1987). (5) E. Hoting, M. Zimmermann, and S. Hilterhaus-Bong, Photochemical alterations in human hair. II. Analysis of melanin,]. Soc. Cosmet. Chem., 46, 181 (1995). (6) E. Hoting and M. Zimmermann, Sunlight-induced modifications in bleached, permed, or dyed human hair,]. Soc. Cosmet. Chem., 48, 79 (1997). (7) Ph. Maillan, UV protection of artificially colored hair using a leave-on formulation, Int.]. Cosmet. Sci., 24, 11 7 (2002). (8) F. W. Marschner and F. Schebece, Composition that protects dyed hair from fading, USP 5,045,307. (9) C. L. Chin and T. C. Ching, A novel silicone color retaining conditioning agent for hair color retention and for clear shampoos, Cosmetics and Toiletries Manufacture Worldwide (Aston Publishing, 2002), p. 167. (10) C. M. Pande, L. Albrecht, B. Yang, Hair photoprotection by dyes,]. Cosmet. Sci., 52, 377 (2001). (11) S. B. Ruetsch, B. Yang, and Y. Karnath, Role of melanin and artificial hair color in preventing photo-oxidative damage to hair, IFSCC Mag., 7, 127 (2004). (12) K. Brown, What's new in hair coloring, SCC Annual Scientific Seminar, Uncasville CT, May 2004, p. 44. (13) M. I. Lim, Y. G. Pan, L. R. Stasaitis, and J. D. Donoghue, USP 5,529,583, 5,672,180, assigned to Clairol. (14) A. Junino and G. Lang, USP 5,279,620, assigned to l'Oreal. (15) M. P. Andousset and J. Cotteret, USP 5,769,903, assigned to l'Oreal A. Bougaut, and Ch. S. Fourcadier, USP 4,094,635, assigned to l'Oreal. (16) J. Jachowicz, B. Lock, and R. McMullen, Spectroscopic analysis of photo and thermal degradation of hair, XIII Congreso Latinoamericano e Iberico de Quimicos Cosmeticos and IFSCC Conference, Acapulco, Mexico, 1997, p. 227. (17) C. Robbins, Weathering in human hair, Text. Res.]., 37, 337 (1967). (18) C. Dubief, Experiments with hair photo-degradation, Cosmet Toiletr., 107, 95 (1992). (19) B. Diffey, A new substrate to measure sunscreen protection factor throughout the ultraviolet spectrum, J. Soc. Cosmet. Chem., 40, 127 (1989). (20) D. Laba, A highly efficient/transparent ultrafine zinc oxide for sun protection, Cosmetics and Toiletries Manufacture Worldwide (Aston Publishing, 2000), p. 299.