Potential effects of TiO2 nanoparticles and TiCl4 in saltwater to Phaeodactylum tricornutum and Artemia franciscana

Nanosized titanium dioxide (nTiO2) 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 TiCl4 and nTiO2 considering standard toxicity tests with microalgae Phaeodactylum tricornutum (growth inhibition test, 1.8–90 mg/L) and crustacean Artemia franciscana (mortality test, 0.5–64 mg/L). For A. franciscana, two alternative scenarios were considered beside standard protocol: i) darkness; and ii) starvation. About microalgae, results evidenced that effects of TiCl4 (EC50 = 63 mg/L) were greater than nTiO2 (no EC50), but IC10 and IC20 were significantly lower suggesting that nTiO2 is more harmful than TiCl4 at lower concentrations. The effects of TiCl4 to crustaceans larvae in all exposure scenarios were lower compared to nTiO2 (EC50(96 h) = 15 mg/L - standard protocol). During toxicity testing, the absence of light generally lowered nTiO2 effects while starvation increased the toxicity of both TiCl4 and nTiO2.