Photo yellowing of human hair

A. C. S. NOGUEIRA, M. RICHENA, L. E. DICELIO AND I. JOEKES

Photochem. Photobiol. B: Biol

Año: 2007 vol. 88 p. 119 - 125

1011-1344

In general, human hair is claimed to turn yellower after sun exposure. This is particularly affirmed for white hair. However, quanti-  tative data relating yellowness to hair type and to the radiation wavelength are missing. This work shows results of the effect of full ortative data relating yellowness to hair type and to the radiation wavelength are missing. This work shows results of the effect of full or UVB-filtered radiation of a mercury vapor or a xenon-arc lamp on the yellowness of virgin white, dark-brown, blond and red hair. AllUVB-filtered radiation of a mercury vapor or a xenon-arc lamp on the yellowness of virgin white, dark-brown, blond and red hair. All hair types showed a substantial change in yellowness after irradiation, which is dependent on the hair type and radiation wavelength.hair types showed a substantial change in yellowness after irradiation, which is dependent on the hair type and radiation wavelength. Surprisingly, white hair turns less yellow after both full and UVB-filtered radiation exposure. This effect is more pronounced whenSurprisingly, white hair turns less yellow after both full and UVB-filtered radiation exposure. This effect is more pronounced when UVB is filtered from the radiation system. The only radiation that shows a photo-yellowing effect on white hair is infrared. As the yel-UVB is filtered from the radiation system. The only radiation that shows a photo-yellowing effect on white hair is infrared. As the yel- lowness of white hair is commonly related to tryptophan degradation, fluorescence experiments with hair solutions were performed tolowness of white hair is commonly related to tryptophan degradation, fluorescence experiments with hair solutions were performed to identify the natural degradation of tryptophan which occurs in hair after light irradiation. Pigmented hairs were also studied, as well asidentify the natural degradation of tryptophan which occurs in hair after light irradiation. Pigmented hairs were also studied, as well as  hair treated with a bleaching solution. Although we observe a decrease in tryptophan content of hair after lamp radiation, a direct cor-hair treated with a bleaching solution. Although we observe a decrease in tryptophan content of hair after lamp radiation, a direct cor-  relation with hair yellowness was not achieved. Results are discussed in terms of hair type, composition and melanin content.relation with hair yellowness was not achieved. Results are discussed in terms of hair type, composition and melanin content. 2007 Published by Elsevier B.V.2007 Published by Elsevier B.V. 22 Keywords: Photo-degradation; White hair; UV-light; Hair color 23 23 Keywords: Photo-degradation; White hair; UV-light; Hair color 23