Investigation of the stability of coated titanium microparticles used in sunscreens.

Due to its UV-light-absorbing properties, titanium dioxide is used in many sunscreen products. However, concern has been raised about a possible photocatalytic activity of titanium dioxide on living tissues. To reduce potential adverse effects, titanium dioxide used in cosmetic preparations is often coated. The coating should be stable under conditions of use. In order to verify the coating stability, sunscreen-grade-coated titanium microparticles were investigated by laser-induced plasma spectroscopy. No changes in the mechanical stability of the coated microparticles could be detected during the manufacturing and penetration of the sunscreen. Applying strong forces on the microparticles by centrifugation, exceeding by far in use conditions, resulted only in small changes in the coating. Copyright 2000 S. Karger AG, Basel.