Titanium Dioxide (TiO 2 ) Nanoparticle Toxicity in a Caenorhabditis elegans Model.

Titanium dioxide is a compound that is used in the food, cosmetic, and paint industries; however, it is still toxic to humans and the environment. This study determined the toxicities of titanium dioxide nanoparticles (TiO ₂ NPs) in a Caenorhabditis elegans ( C. elegans ) model. The effects of commercially available (C-TiO ₂ ) and synthetically (S-TiO ₂ ) prepared TiO ₂ NP solutions on lethality, lifespan, growth, reproduction, locomotion, and gene expression were studied in C. elegans . Exposure to TiO ₂ NPs (0.0, 0.01, 0.1, 1.0, and 10 mg/L) did not result in any change to the survival rate or body length of the nematodes, regardless of the concentration. However, there was a decrease in the reproduction (brood size) and locomotion (body bending and head thrashing) of the nematodes as the TiO ₂ NP concentration increased. The longevity of the nematodes was shortened following TiO ₂ NP exposure. The gene expression of sod-1, sod-3, ctl-1, ctl-2, cyp35A2, mlt-1, and mlt-2 in the nematodes showed that there was an overexpression of all genes when the worms were exposed to 1 mg/L C-TiO ₂ or 10 mg/L S-TiO ₂ . It was therefore concluded that compared with S-TiO ₂ , C-TiO ₂ possibly causes more toxicity or genotoxicity in the C. elegans model.