Environmental Risks of Nanotechnology: Evaluating the Ecotoxicity of Nanomaterials

Abstract

The unique electronic, optical, magnetic, and mechanical properties of materials in the nanoscale open avenues to new technologically relevant alternatives for application in catalysis, advanced materials, medicine, energy, electronics, and even environmental remediation. In that sense, the incorporation of such nanomaterials (NMs) in everyday consumer products, food ingredients, packing materials, cosmetics, and clothes, as well as the increase in the number of waste by-products containing nanosized components, has raised many questions about their potential impact on the environment and their risk for public health. Although most of the NMs have been extensively studied in research labs for decades, it is very probable that the long-term effects have been overlooked or even that the tests performed to evaluate their potential toxicity are not enough to reach a conclusion. Ecotoxicology is a multidisciplinary field of study that aims to evaluate and predict the impact of toxic chemicals on biological organisms. What would be the fate and effects of NMs in an ecosystem is a new-and important-question for this field. To answer it, we should consider not only the chemical composition, but also the concentration, stability, bioavailability, solubility, size, shape, aggregation, and physical properties of the considered NM and its interactions with other substances. As many nanometals and their derivatives (oxides, chalcogenes, and salts), as well as carbon-based NMs, are finding commercial uses or even being considered for polluted water, air, or soil remediation, it is important to assess their potential risks for and effects on the environment and human health. In this chapter, we start by discussing the physical and chemical properties of some technologically important NMs, in order to understand how such properties may have implications on human health and a potential for ecological disruption if dispersed as pollutants in the environment. After that, we present a glimpse of the actual and future markets of consumer products and environmental technologies making use of NMs. In order to understand the impact on ecology and human health, we will discuss how their unique properties enable them to pass through natural barriers, their bioaccumulation in organisms, and the disruption of metabolic processes by oxidative stress, enzyme inhibition, cellular interactions, inflammation, or genotoxicity, creating a health risk for the short and long terms due to their toxicological effects. Finally, we will discuss several in vitro and in vivo techniques and some of the advantages and disadvantages of exposure methods used in ecotoxicology.