Is the UV-protection in nanomaterial-containing sunscreens only effective if the nanomaterials enter the skin and how are they excreted later?

No, to effectively act as inorganic UV-blocker (also called mineral UV-blocker) in sunscreen, the materials either in nanoform or lager just need to form a thin layer on top of the skin. If correctly applied (not on mucous membranes or injured skin) the nanomaterials cannot enter the human body and are washed off the skin surface by sweat or water.

• For further information on this topic “Nanoparticles and the skin“, please refer to our cross-cutting section!!!