In vivo screening to determine hazards of nanoparticles: nanosized TiO2.

A single-species laboratory test with terrestrial invertebrates was used to identify the hazard of nanosized TiO(2). Feeding parameters, weight change, mortality, and the activities of catalase and glutathione-S-transferase were evaluated after 3 or 14 days of dietary exposure. The effects of nano-TiO(2) were dependent on exposure concentration and duration, total consumed quantity, size and pre-treatment of particles. The intensity of a response was ruled by duration of exposure and not by consumed quantity of nano-TiO(2) or exposure concentration as expected. The response to nano-TiO(2) is described as threshold-like. The exposure concentrations 10-1000 microg TiO(2)/g dry food (1.35-1025 microg of total consumed quantity of TiO(2)/g animal wet wt.) were identified as safe for tested species after tested exposure period. We conclude that the response to nanoparticles is different from that of soluble chemicals therefore these two types of data should be interpreted and processed differently.