Overview of Nanoscience in the Environment - Environmental and Human Health Impacts of Nanotechnology - page 15

Figure 1.4 Some possible exposure routes for nanoparticles and nanotubes based on current
and potential future applications. (Redrawn from Nanoscience and Nanotechnologies:
Opportunities and Uncertainties , 2004, with permission from The Royal Society.)

may be important or different in nanoparticles and are size dependent include
chemical reactivity, adsorbent properties, catalytic surface, functional group content
and nature, surface charge, crystal structure, oxidation state, tendency to aggregate
and dissolve and degree of toxicity. These properties are discussed in more detail
in Chapters 2 and 3, their effects on the fate and behaviour of nanoparticles in the
environment is discussed in Chapters 4 and 5 and their effect on toxicity is discussed
in Chapters 7 and 9 .

1.12 Nanomaterial Structure - Toxicity Relationship

The causes of the toxicity of nanoparticles are still unclear. So far, research results
are more suggestive than defi nitive and no quantitative structure- activity relation-
ship models are available. Physicochemical properties such as size, specifi c surface
area, structure, morphology, chemical composition, solubility, reactivity, aspect ratio,
photochemistry, production of reactive species and surface properties (i.e. charge
and coating) can be of prime importance. For instance, size is the main characteristic