Critical comparison of intravenous injection of TiO_2 nanoparticles with waterborne and dietary exposures concludes minimal environmentally-relevant toxicity in juvenile rainbow trout Oncorhynchus mykiss

摘要

A critical comparison of studies that have investigated tissue accumulation and toxicity of TiO_2-NPs in fish is necessary to resolve inconsistencies. The present study used identical TiO_2-NPs, toxicological endpoints, and fish (juvenile rainbow trout Oncorhynchus mykiss) as previous studies that investigated waterborne and dietary toxicity of TiO_2-NPs, and conducted a critical comparison of results after intravenous caudal-vein injection of 50 μg of TiO_2-NPs and bulk TiO_2. Injected TiO_2-NPs accumulated only in kidney (94% of measured Ti) and to a lesser extent in spleen; and injected bulk TiO_2 was found only in kidney. No toxicity of TiO_2 was observed in kidney, spleen, or other tissues. Critical comparison of these data with previous studies indicates that dietary and waterborne exposures to TiO_2-NPs d not lead to Ti accumulation in internal tissues, and previous reports of minor toxicity are inconsistent or attributable to respiratory distress resulting from gill occlusion during waterborne exposure.