Nano-titanium dioxide (nano-TiO2) is the nanomaterial produced in the greatest amounts and is already a component in many products, both in its regular and nano-scale size. This also makes it the best-investigated nanoparticle. Many in-vivo and in-vitro studies have been conducted to test for potential environmental risks. Nonetheless, the possible long-term effects remain unknown. Short-term exposures to high doses showed damage both in aquatic and in terrestrial ecosystems. No specific regulations for nano-TiO2 are currently in place.