Effects of repeated exposure to ozonated water on hair fibre structure and integrity: Part I

Ozone has recently been marketed as a hair-revitalizing treatment claimed to enhance shine, softness and overall fibre quality. However, given its strongly oxidative nature, rigorous evaluation is required to determine its true effects on hair structure. This study investigates the impact of repeated exposure to ozonated water on a variety of hair-fibre properties.

Multiple analytical techniques were used: Fourier transform infrared spectroscopy (FTIR) to detect chemical changes; scanning electron microscopy (SEM) and fluorescence microscopy to assess surface and internal morphological alterations; differential scanning calorimetry (DSC) to analyse keratin and matrix thermal behaviour; tensile testing to determine mechanical responses; and combability, shine and colour measurements to evaluate consumer-relevant attributes.

Ozonated water induced distinct oxidative modifications across structural, chemical and functional domains. FTIR revealed progressive increases in cysteic acid-related bands and carbonyl groups, confirming protein and lipid oxidation. SEM and fluorescence imaging showed cuticle fusion and increased cortical fluorescence, consistent with elevated carbonyl content. Morphological cuticle changes, together with increased cysteic acid content, aligned with the rise in combing force. DSC demonstrated an increased denaturation temperature accompanied by a slight reduction in enthalpy, indicating altered crosslink density and partial disruption of keratin order; these changes were further supported by increased post-yield stiffness in tensile tests and modifications observed in the Amide I and II regions. Changes in shine and colour were minimal.

Prolonged exposure to ozonated water induced cumulative oxidative modifications of hair proteins, lipids and pigments, resulting in alterations to various hair properties. Ozone appears to induce a unique damage signature that extends beyond the cuticle into the cortex. Future studies will explore lipidomic and biochemical changes in greater depth and evaluate how ozone-treated hair responds to subsequent cosmetic and environmental stressors.