Stability of Sunscreens Containing CePO(4): Proposal for a New Inorganic UV Filter

Inorganic UV filters have become attractive because of their role in protecting the skin from the damage caused by continuous exposure to the sun. However, their large refractive index and high photocatalytic activity have led to the development of alternative inorganic materials such as CePO(4) for application as UV filters. This compound leaves a low amount of white residue on the skin and is highly stable. The aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing ordinary organic UV filters combined with 5% CePO(4), and, to compare it with other formulations containing the same vehicle with 5% TiO(2) or ZnO as inorganic materials. The rheological behavior and chemical stability of the formulations containing these different UV filters were investigated. Results showed that the formulation containing CePO(4) is a promising innovative UV filter due to its low interaction with organic filters, which culminates in longer shelf life when compared with traditional formulations containing ZnO or TiO(2) filters. Moreover, the recognized ability of CePO(4) to leave a low amount of white residue on the skin combined with great stability, suggests that CePO(4) can be used as inorganic filter in high concentrations, affording formulations with high SPF values.