Acute and chronic toxicity of nano-scale TiO2particles to freshwater fish, cladocerans, and green algae, and effects of organic and inorganic substrate on TiO2toxicity

This research evaluated the toxicity of TiO2 nanoparticles to freshwater aquatic organisms and the effects of organic and inorganic material on TiO2 toxicity. The fathead minnow was much less acutely sensitive to TiO2 (LC50 500 mg/l and higher) than Ceriodaphnia dubia and Daphnia pulex (mean LC50 values 7.6 and 9.2 mg/l, respectively). Total organic carbon levels of 1.5 mg/l decreased TiO2 acute toxicity to C. dubia (LC50 > 100 mg/l), but kaolinite clay decreased TiO2 toxicity to a lesser extent. In chronic toxicity tests, the green algae Pseudokirchneriella subcapitata was more sensitive to TiO2 (IC25 1–2 mg/l) than C. dubia (IC25 9.4–26.4 mg/l) and the fathead minnow (IC25 values over 340 mg/l). Study results indicate that the specific organisms exposed and the effects of water quality parameters on TiO2 toxicity should be considered in hazard evaluations of this nanoparticle.