January 2014 in “한국미용학회지” This study observed that long-term UV-A exposure and semi-permanent dye treatment can cause significant structural damage to human hair, particularly affecting the cuticle and cortex layers.
January 2005 in “Seibutsu Butsuri/Seibutsu butsuri” Chemical treatments damage hair more than UV exposure, making it thinner and less flexible.
40 citations
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February 2002 in “International Journal of Dermatology” In this study, hair damaged by permanent dye showed signs of recovery over time, with near complete restoration to its original state after eight weeks.
January 2008 in “대한미용학회지” This study reports that prolonged UV irradiation causes progressive damage to the hair's keratin structure, leading to increased surface roughness, cuticle destruction, and decreased tensile strength in young women’s hair.
4 citations
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January 2007 in “Sen'i Gakkaishi” This study found that permanent wave treatment accelerates hair degradation after protease exposure, showing significant morphological differences compared to untreated hair and linked to damage from Alpha-helical region denaturation.