Potential effects of TiO nanoparticles and TiCl in saltwater to Phaeodactylum tricornutum and Artemia franciscana.

Nanosized titanium dioxide (nTiO) is widespread in many commercial products and several authors investigated its ecotoxicity effects focusing mainly on freshwater environments. Data on saltwater species are still lacking or present contradicting results. We compared for the first time the toxicity of TiCl and nTiO considering standard toxicity tests with microalgae Phaeodactylum tricornutum (growth inhibition test, 1.8-90mg/L) and crustacean Artemia franciscana (mortality test, 0.5-64mg/L). For A. franciscana, two alternative scenarios were considered beside standard protocol: i) darkness; and ii) starvation. About microalgae, results evidenced that effects of TiCl (EC50=63mg/L) were greater than nTiO (no EC50), but IC10 and IC20 were significantly lower suggesting that nTiO is more harmful than TiCl at lower concentrations. The effects of TiCl to crustaceans larvae in all exposure scenarios were lower compared to nTiO (EC50(96h)=15mg/L - standard protocol). During toxicity testing, the absence of light generally lowered nTiO effects while starvation increased the toxicity of both TiCl and nTiO.