Influence of Oxidative and/or Reductive Treatment on Human Hair (I): Analysis of Hair-Damage after Oxidative and/or Reductive Treatment

Abstract

We devised a damaged hair model to confirm hair-damage was caused not only by chemical stress but also by physical and environmental stress. We observed morphological changes (e.g. decreasing cuticle layers, scale lift, hair swelling) in the hair model and analyzed alterations in the hair composition (e.g. cysteic acid, protein elution, melanin granule). We devised oxidative and reductive treatments (e.g. perming, bleaching) as the chemical stresses. We also devised a system for testing physical and environmental stresses. This consisted of ultraviolet ray (UV) irradiation, brushing, treatment with detergent, drying and heating. These factors are believed to cause hair-damage during normal everyday life. Scale lift was observed and this phenomenon was propagated depending on the amount of physical and environmental stress. The amount of exfoliated cuticles and cysteic acid in the cuticles also tended to increase with the progress of the physical and environmental treatments. The tendency was more remarkable with strong chemical treatments. The swelling of the hair, protein elution and the amount of solubilized melanin granule exhibited similar trends. These trends, though, were not as remarkable as those observed in the cuticle layers. Using the damaged hair model that included physical and environmental stresses, we demonstrated that stresses from everyday life, as well as chemical stresses, effected hair damage. These influences were enhanced depending on the degree of chemical treatment. This tendency was more remarkable in cuticle layers than in the cortex and medulla parts.