12. Cerium Oxide Nanoparticles: Structure, Applications, Reactivity, and Eco-Toxicology

In this chapter, the physical, chemical, and ecotoxicological features of nanometric cerium oxide will be discussed on the basis of the recent research. In contrast with other oxides such as SiO₂, ZnO, ZrO₂, or TiO₂ with relevant industrial applications, ceria presents a unique redox chemistry that expanded its application to fields that take advantage of its chemical reactivity, as heterogeneous catalysis and detoxification of gaseous exhausts. In the past, several studies were strictly focused on the exploration of its eventual damage to environment and human health. CeO₂, as other rare earths oxides, is basically a low toxicity substance[1] and nowadays there is vast and increasing evidence pointing to its potential role as protective compound in terms of human health. The aim of this chapter is to offer a wide scope of description of the intrinsic physicochemical behavior of this unique compound, with deep emphasis in the inherent challenge that represents a definitive understanding of its surface chemistry. The apparent contradiction between toxicity and health benefits will be discussed according to the present evidence and the intrinsic limitations of these complex studies.