The research team, which also consisted of colleagues from IQAC-CSIC in Barcelona, the Ohio State University, and the University of Cincinnati College of Medicine, published their findings in the International Journal of Cosmetics Science using the examples of EDDS and histidine as effective chelants for use in shampoos and conditioners, respectively.
Damage to hair from UV exposure is known to be a highly complex process involving initiation via absorption of UV light followed by formation and propagation of reactive oxygen species (ROS).
Therefore the research team set about understanding these mechanisms, to explain the role of copper in accelerating the formation of ROS and identify strategies to reduce the hair damage caused by these reactive species.
Testing
To do this, the location of copper in hair was measured by Transmission electron microscopy–(TEM) X-ray energy dispersive spectroscopy (XEDS) and levels measured by ICP-OES, in virgin Caucasian-source hair, purchased from International Hair Importers & Products.
Protein changes were also measured as total protein loss via the Lowry assay, and MALDI ToF was used to identify the biomarker protein fragments; which originates from the calcium-binding protein S100A3.
Sensory methods and dry combing friction were then used to measure hair damage due to copper and UV exposure and to demonstrate the efficacy of N,N' ethylenediamine disuccinic acid (EDDS) and histidine chelants to reduce this damage.
“Exposure to UV will damage hair as measured by protein loss and this damage will be accelerated in the presence of copper ions from tap water taken up by hair,” says the study. “This structural degradation in combination with physical damage from combing/washing, etc. will over time lead to loss of shine, poor combing and poor hair health.”
“The use of chelants such as EDDS and histidine in shampoos and conditioners, respectively, will reduce copper levels in hair and ultimately lead to improved hair health.”
Reasons
Hair damage from UV exposure has been shown to occur to the keratin proteins, lipids, and melanin, eventually leading to colour changes and also noticeable physical changes such as split ends, loss of shine and manageability.
Maintaining hair health is a key need for women globally, so the research team says it embarked on this study to better understand the mechanisms of UV damage and identify technology to prevent this damage, which is a high priority for the cosmetics industry.