Comparative evaluation of the hair damage caused by different concentrations of SLS and SLES on detached human hair at different pH and temperatures, an in-vitro study

Abstract

Anionic surfactants, specially Sodium Lauryl Sulfate (SLS) and Sodium Lauryl Ether Sulfate (SLES), are used extensively in hygiene products because of their cleansing and foaming properties. Based on recent studies, anionic surfactants can cause Structured damage on human hair e.g. hair loss, breakage, trichoptilosis, and dry scalp; therefore, different evaluation techniques should be used in safety evaluation of cosmetic ingredients. Purpose: The aim of this study is to define a new technique, with considerable advantage over zein test, for assessment of hair damages caused by anionic surfactants.Materials and methods:hair bundles were immersed in SLS and SLES solutions (5, 10, 20, and 30 % W/V), with different pH values (5, 7 and 30), in different temperatures (37 and 42 °C) and in different time periods (10 minutes and 24 hours). After removing from solution and performing the preparation steps required for lowry test, absorption of sample in 750 nm wavelength was measured by UV-Visible Spectrophotometer. The acquired results were compared with each other and with the results of the zein test.Conclusion:The lowry method is a competent candidate with significant privileges over zein test, which can be used as a direct technique for hair damage assessment in safety evaluation of the hair products.