Extraction and characterization of sub-micron sized TiO 2 from toothpaste: evaluation of their toxic effects in marine microalgae Chlorella sp.

Objective The increased production of titanium dioxide (TiO 2 ) incorporated consumer products have expressed concerns about their potential threat to the environment. It is warranted to investigate the importance of the release of TiO 2 from consumer products and the resulting environmental repercussions. Thus, the present study evaluated the toxicity of TiO 2 extracted from toothpaste along with the commercially available TiO 2 (nano and bulk). Methods The extracted and commercially available TiO 2 were characterized for their shape, size, crystallinity, and functional groups. Chlorella sp. (0.1 optical density) was interacted with extracted, nano, and bulk TiO 2 particles (0.01, 0.1, and 1 mg/L) for 72 h in a 100 mL sterile beaker. After 72 h, the cellular viability (%) was evaluated by cell count method. Oxidative stress in Chlorella sp. was computed by determining the reactive oxygen species generated. Intracellular concentration of Ti in Chlorella sp. was determined by inductively coupled plasma mass spectrophotometer. Principal component analysis was used to establish the relation between the different TiO 2 particles and assays performed in Chlorella sp. Results The extracted TiO 2 was in the rutile phase and had a particle size in the sub-micron range. Toxicity of TiO 2 was dose- and size-dependent and nano-form of TiO 2 were found to be more toxic to Chlorella sp. followed by extracted and bulk TiO 2 . In addition to toxicity, oxidative stress and intracellular Ti concentration were measured. Our findings emphasize that extracted TiO 2 at environmentally relevant concentrations of TiO 2 were less toxic compared to commercially procured nano TiO 2 . Conclusion This study highlights the need of assessing the environmental risks of nanoparticles used in consumer products by studying their interactions with aquatic organisms.