[Nano is big! : Facts and myths about nanoparticulate UV filters]

Sunscreen products containing inorganic micronized titanium dioxide (TiO₂) and zinc oxide (ZnO) have been available since the 1950s. Their cosmetic acceptance remained limited as they persist as a white paste on the skin. By reducing the size of the particles into the nano-range below 100 nm, their optical property of reflecting visible light is reduced. After the year 2000, organic filters of this size range were developed. The enthusiasm for nanotechnology that prevailed at the time did not transfer to sunscreen products with nanoparticulate filters. Consumers suspect that the particles permeate the skin, are absorbed by the blood, and spread throughout the body causing illness. Not least due to public pressure, cosmetics-which include sunscreen products-became the first product segment in which accordingly manufactured substances were subjected to strict regulations. Despite advanced regulation and strict approval procedures for nanoparticulate filters, public reservations remained. Possible reasons for this are lack of knowledge or mistrust of the applicable legislation, unclear perception of the behavior of nanoparticles in sunscreen products and as a result unclear perceptions of hazard, risk, and exposure. Against this background, the nature and behavior of nanoparticulate filters in sunscreens on the skin and potentially in the skin, as well as the regulatory framework that ensure that nanoparticulate filters and the products containing them are safe to use are discussed.