Photodamage to the Cuticle Layer of Human Hair

by The Cosmetic Chemist Staff


Over the years, there has been considerable interest in understanding the effects of UV radiation on hair. Interestingly, these studies demonstrate that the hair fiber can suffer notable damage as a result of UV exposure. Much of this damage is manifested in the form of protein degradation, changes in the surface chemistry of the fiber, alteration of the mechanical properties of hair, and changes in hair color associated with degradation of pigments and chromophores in hair.1

Several years back, Sigrid Ruetsch and coworkers, from TRI-Princeton, found that extensive exposure of hair to UV light led to fusion of the lamellar components of hair cuticle cells.2 Building on this foundation, more recent work in this area by Richena and Rezende at the University of Campinas in Brazil reveals even more UV-induced radiation changes to the morphology of hair.3

Hair damage inflicted to hair by UV light was shown to result in the formation of small globular bubbles on the surface ranging in size from 1-5 nm. In addition, cuticle step height increases 65% as a result of extreme exposure and morphological changes are observed in the pre-existing holes on the surface of hair, which become larger with increasing exposure to UV radiation.

1. M.F. Dario, A.R. Baby, and M.V.R. Velasco, Effects of solar radiation on hair and photoprotection, J. Photchem. Photobiol. B, 153, 240-246 (2015).
2. S. Ruetsch, Y. Kamath, and H.-D. Weigmann, Photodegradation of human hair: an SEM study, J. Cosmet. Sci., 51, 103-125 (2000).
3. M. Richena and C.A. Rezende, Effect of photodamage on the outermost cuticle layer of human hair, J. Photochem. Photobiol. B, 153, 296-304 (2015).