Effect of Ultraviolet Radiation on Color, Protein Loss, and Mechanical Properties of Hair

The study investigated the effects of different UV wavelength ranges on various hair types, comparing artificial UV irradiation to sunlight exposure. Hair protein loss was measured using the Lowry method, color changes by diffuse reflectance spectrophotometry, mechanical properties through stress-strain curves, and surface damage via scanning electron microscopy. Results showed that UVA radiation caused about twice as much protein loss in all hair types compared to controls, with UV radiation causing higher protein loss in blond and dark-brown hair. After 91 hours of sunlight exposure, red hair lost more protein than blond and dark-brown hair. All hair types experienced color changes, especially blond hair, with UVA being the main contributor. Mechanical properties did not significantly differ after UV or UVA exposure. UVB radiation primarily caused protein loss, while UVA was responsible for color changes, and melanin type did not affect photo-oxidation resistance.