The Physical and Chemical Disruption of Human Hair After Bleaching – Studies by Transmission Electron Microscopy and Redox Proteomics

The study investigated the effects of cosmetic peroxide bleaching on human hair, revealing that bleaching caused significant structural and chemical damage. Protein loss increased with bleaching severity, affecting not only the cuticle but also the cortex, including intermediate filaments and keratin-associated proteins. Transmission electron microscopy showed substantial damage to the cuticle and cortex, with extensive melanin degradation even at mild bleaching levels. Protein oxidation, particularly of sulphur-containing amino acids, was prominent, converting cystine disulphide bonds to cysteic acid. The findings concluded that peroxide treatments rapidly penetrate the cortex, causing widespread oxidative damage and protein loss, facilitated by the degradation of the cuticle layers.