Nano-titanium dioxide (nano-TiO2) is the nanomaterial produced in the largest amounts and is already contained in numerous products, both in the regular and in nano-scale size. It is therefore also the best investigated nanoparticle. Many in-vivo and in-vitro studies have been conducted to test for potential health hazards, although the epidemiological studies have not demonstrated any TiO2-specific effects. Currently, however, no nano-TiO2-specific epidemiological studies and no data are available on potential exposure. Nonetheless, various international bodies have classified the material as “possibly carcinogenic in humans” based on animal experiments and have pointed to the risks. There is no specific regulation for nano-TiO2 and therefore the regulation for (ultra-)fine particulate emission is applied.