Lipid Peroxidation Processes Photoinduced by Titanium Dioxide in Emulsion Systems, Representative of Sunscreen Formulations

Abstract

This article studies the peroxidation of linoleic acid and of porcine skin lipids on ultraviolet B (UVB) irradiation, in the presence of various TiO₂ specimens used as inorganic sunscreen pigments in different emulsion systems. It was found that different TiO₂ specimens induce quite variable lipid peroxidation in the same emulsion system, which suggests that the different coatings widely differ in their effectiveness to lower the photocatalytic activity of TiO₂. However, it was also found that the extent of lipid peroxidation caused by the same TiO₂ pigment in different emulsions was even more variable than the effects of different pigments in the same system. This finding might imply that the choice of the formulation components different from TiO₂ could be of paramount importance as far as the potential skin damage induced by the photocatalytic activity of TiO₂ is concerned.

Keywords:

• Emulsion systems
• lipoperoxidation
• porcine ear skin
• titania

Acknowledgments

This research has been carried out with the financial support of Regione Piemonte (Project CIPE 2006) project “Nanoparticles: From Their Impact on the Environment and Human Health to Safer Production And Usage (Nanosafe).”