Human safety review of "nano" titanium dioxide and zinc oxide.

Based on the current weight of evidence of all available data, the risk for humans from the use of nano-structured titanium dioxide (TiO(2)) or zinc oxide (ZnO) currently used in cosmetic preparations or sunscreens is considered negligible. There is a large body of information that when viewed in its entirety is considered as sufficient to demonstrate that these nano-structured ultraviolet (UV) filters, irrespective of various treatments (coatings) or crystalline structure, can be regarded as safe for use at concentrations up to 25% in cosmetic products to protect the skin from harmful effects of solar UV radiation. "Nano" TiO(2) and ZnO formulated in topically applied sunscreen products exist as aggregates of primary particles ranging from 30-150 nm in size.