Altered physiological conditions of the terrestrial isopod Porcellio scaber as a measure of subchronic TiO2 effects.

Titanium dioxide nanoparticles (nano-TiO2) show low toxic potential against a variety of environmental organisms when measured by conventional toxicity endpoints. However, the question is whether the conventional measures of toxicity can define the adverse effects of nanoparticles. The aim of this study was to asses the potential toxic and cytotoxic effects of the ingested nano-TiO2 (anatase, <25 nm) on a terrestrial isopod, Porcellio scaber. In addition to conventional toxicity parameters, the physiological condition of the animals was assessed. Following 28-day feeding exposure to nano-TiO2 at concentrations up to 5,000 μg nano-TiO2/g leaf dry weight, no toxic or cytotoxic effects were demonstrated. However, the physiological condition of the animals was affected in a dose-dependent manner. The physiological state of organisms is an important parameter to assess the potential population implications due to the exposure to nanomaterials. Therefore, we suggest that only if both, the physiological state of the animals exposed to nano-TiO2 and the conventional toxicity markers show no effects, the exposure dose can be interpreted as non-hazardous.