The increasing use of nanoparticulate engineered materials
posses the question on the safety of those materials. A paradigmatic case is their use in cosmetics, in principle because
those materials are in direct contact with the body and because probably cosmetic usage of nanotechnology will anticipate the use of nanoparticles in medicine. Non acute toxic effects have been observed so far and some tones of some
nanoparticles are already used in sunscreens. However the observed effects of interaction between nanoparticles and biological structures calls for a better understanding of that interaction and a prudent development of consumer products
based on nanoparticles. In this paper we summarize the known
facts regarding the use of nanoparticles in cosmetics.