Cytotoxicity of Titanium Dioxide Nanopaprticleson A Bacterial Population Isolated from Lakewater Sediments

Abstract

 Studies suggest that approximately 4.6 million ton of pigmentary titanium dioxide (TiO2) is consumed annually worldwide. Owing to the increased industrial and consumer applications, there is growing concern regarding the possible risk associated with their environmental exposure. TiO2 dust, when inhaled, has been classified by the International Agency for Research on Cancer (IARC) as an IARC Group 2B carcinogen, meaning it is possibly carcinogenic to humans. TiO2 nanoparticles (NPs) can enter the aquatic environment either through direct or indirect release as effluents from nano-paints, sunscreen lotions, food additives, medical use, dismantling of batteries, etc. Therefore, the aim of the present study was to explore the difference in toxicity mechanism of TiO2 NPs at low concentrations (1 μg/ml), in a bacterial consortium consisting of Pseudomonas aeruginosa, Bacillus altitudinis and Bacillus tequilensis, isolated from lakewater sediments, under light and dark conditions. The cytotoxicity of the NPs was studied by performing several biochemical assays for the assessment of membrane permeability, cell viability, oxidative stress and secretion of exo-polysaccharides. It was found that there was generation of ROS, which may have resulted in the decrease in cell viability. Also, the cytotoxic effects were found to be more pronounced under dark than under light conditions.

Keywords: titanium dioxide nanoparticles, cytotoxicity, ROS