Inorganic sunscreens

Inorganic sunscreens, based on TiO2 and ZnO, are a rapidly growing segment of the overall UV protection market. They offer the advantages of high SPF, broad-spectrum coverage and reduced potential irritancy to users. Lack of transparency has traditionally been a drawback regarding acceptance of these products. Recent development work has therefore prioritised the achievement of transparency through superior control of particle size, shape and particle size distribution. The properties of TiO2, and ZnO are discussed as sunscreen actives, and the key factors affecting efficacy and cosmetic elegance. The pros and cons of different product forms (powders and dispersions) are discussed. Physical sunscreens can be used either as the sole active in a formulation, or in combination with each other or with organic sunscreens; the relative benefits of these approaches are assessed. The paper concludes with a review of work undertaken to achieve transparency along with developments to improve efficacy (SPF and WA coverage) and photostability.