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, focusing on structural and chemical changes. It was found that protein loss increased with the severity of bleaching, affecting not only the cuticle but also the cortex, including intermediate filaments and keratin-associated proteins. Bleaching led to significant damage to the cuticle and cortex, with extensive melanin degradation even at mild bleaching levels. The oxidation primarily targeted sulphur-containing amino acids, converting cystine disulphide bonds to cysteic acid. The study concluded that peroxide treatments rapidly penetrate the cortex, causing widespread oxidative damage and protein loss, facilitated by structural degradation of the cuticle.