Abstract: Titanium dioxide nanoparticles (TiO2-NPs) are common components used in sunscreens, cosmetics, industrial applications, and many other products. Concerning their high production and widespread applications, characterization and quantification of TiO2-NPs in various matrixes is a topic of great interest for researchers studying their potential environmental and health impacts. Validated and easily applicable analytical tools are required to develop and implement regulatory frameworks and an appropriate risk assessment for engineered nanoparticles (ENPs). Herein, we provide a critical review of the current knowledge
available on world-wide production and measured environmental concentrations as well as on available techniques to measure and characterize these ENPs in the environment.