Morphological Changes in Semi-Permanent Dyed Hair Due to UV-A Radiation

The study examined the effects of UV-A radiation on semi-permanent dyed human hair, revealing significant damage to the hair structure after 600 hours of exposure. The cuticle layer showed degradation, thinning, and cavity formation, while the cortex layer exhibited cavities between cortical cells and melanin granules. The research suggested that UV exposure leads to the generation of free radicals, oxidation of keratin and melanin, cleavage of cystine bonds, and formation of cysteic acid, resulting in hair damage. The findings emphasized the importance of recognizing and managing photo-damage to maintain healthy hair.