Since the classic talk by Richard Feynman (1960) entitled “There Is Plenty of Room at the Bottom,” nanotechnology has grown to a multibillion dollar industry worldwide, with 1300 nanotechnology-enabled products in commercial use by 2010 (Woodrow Wilson Center, 2012). The potential of adverse effects from exposure to “nanophase materials” was already pointed out earlier (Oberdörster and Ferin, 1992; Oberdörster et al., 1992), and concerns about human and environmental health and safety of engineered nanomaterials (ENMs) were initially raised in 2003 (Colvin, 2003). Since then, toxicity of high volume, commercial nanomaterials including nanosilver, fullerenes, quantum dots, carbon nanotubes (CNTs), graphene-based materials, and metal oxide nanoparticles (NPs) has been summarized in several reviews (Donaldson et al., 2004; Borm et al., 2006; Nel et al., 2006; Boczkowski and Hoet, 2009; Krug and Wick, 2011; Kunzmann et al., 2011; Sanchez et al., 2012). New ENMs and composites are continually emerging with potential for significant commercial applications in energy generation, environmental sensing and remediation, aerospace and defense, and medical diagnosis and therapy. Examples of nanoscale materials of different shapes and sizes are depicted in Fig. 29-1. Investigations of the magnitude of release of manufactured nanomaterials and their subsequent fate, transport, transformation, and potential for human and environmental exposure and toxicity (Fig. 29-2) have been areas of active research (Mueller and Nowack, 2008; Krug, 2014).
Length scales for natural and synthetic structures (above) and some examples of engineered nanomaterials of varying size and shape (below).
Research phases for assessing human and environmental safety of engineered nanomaterials.
The United States National Nanotechnology Initiative (NNI, http://www.nano.gov/) defines nanotechnology as the understanding and control of matter at the nanoscale at dimensions between approximately 1 and 100 nm, where unique phenomena enable novel applications. Roco (2005) defined the sizes as ranging from the intermediate length scale between a single atom or molecule and about 100 molecular diameters or about 100 nm, and emphasizes the ability to measure and transform at this nanoscale and to exploit the properties and functions specific for the nanoscale.
Although the NNI defines nanotechnology as a facilitator of unique properties for novel applications, it is noted that nanomaterials are frequently defined by dimensions alone. For instance, the International Organization for Standardization (ISO) Technical Committee on Nanomaterials (TC 229) defines a nanomaterial as a material with any external dimension in the nanoscale or having an internal structure or surface structure in the nanoscale (ISO/TC, 2015). ISO further describes subsets of nanomaterials and properties resulting from nanomaterials that are nanoenabled and nanoenhanced. These terms emphasize that materials at the nanoscale do not always have dramatically different ...