Aggregation and toxicity of titanium dioxide nanoparticles in aquatic environment—A Review

Abstract

The use of nanoparticles—particles with size ∼1–100 nm is increasing worldwide. This is particularly the case for applications of titanium dioxide nanoparticles (nano-TiO₂) in consumer products, which have expanded at a fast rate in the last decade. The properties of nano-TiO₂ differ significantly from bulk-TiO₂ of the same composition because of an increase in surface area. A release of nano-TiO₂ from application sources to the aquatic environment may pose possible risks due to their bioavailability and toxicity. The aggregation of nano-TiO₂ plays an important role in the environmental effects of nanoparticles because the size and shape of nanoparticles will determine the magnitude of any potentially toxic effect. Aggregation is affected by pH, ionic strength, and ionic identity (inorganic and organic) of aqueous suspensions and is reviewed in this paper. The current information on the evaluation of ecotoxicological hazards of nano-TiO₂ to bacteria, algae, invertebrates, nematodes, and rainbow trout is also given.

Keywords:

• TiO₂
• aggregation
• ph
• ionic strength
• organic matter
• aquatic toxicity
• reactive oxygen species
• bacteria
• invertebrates
• algae

Acknowledgment

Author wishes to thank Drs. Mary Sohn and Ria Yngard for useful comments on this paper. This paper has also been greatly improved by the comments of the reviewer.

Notes

*Significantly different from the control within each column at P < 0.05 level.

**Significantly different from the control within each column at P < 0.01 level.