O o d h e a d p u b L i s h I n g L i m I t e d

particles can behave differently from the bulk material. The very large surface
to bulk ratio of nanoparticles and their enhanced surface chemistry can lead
to increased toxicity. The International Risk Governance Council state in
their White Paper on Nanotechnology Risk Governance (Renn and Roco,
2006):
‘There is only a limited understanding of the potential EHS risks of
nanomaterials and further studies are required for both: (i) hazard
characterisation, in areas such as toxicity, ecotoxicity, carcinogenicity,
volatility, flammability, persistence and accumulation in cells; and (ii)
exposure, including the potential for oral, cutaneous and inhalative uptakes
of nanomaterials during production, transport (in air, water, soil and
biosystems), decomposition and/or waste disposal.
• Human health risks. Several studies have shown that: (i) due to the
high surface-area-to-volume ratio and higher reactivity of
nanostructures, large doses can cause cells and organs to demonstrate
a toxic response (in particular inflammation) even when the material
itself is non-toxic; (ii) some nanosized particles are able to penetrate
the liver and other organs and to pass along nerve axons into the
brain; (iii) nanomaterials may combine with iron or other metals,
thereby increasing the level of toxicity and presenting unknown risks;
(iv) engineered nanomaterials raise particular concerns because of
the unknown characteristics of their new properties and their potential
use in concentrated amounts; and (v) some nanomaterials may have
similar characteristics to known high-risk materials at the microscale.
• Explosion risks. The higher surface reactivity and surface-area-to-
volume ratio of nanopowders increases the risk of dust explosion and
the ease of ignition.
• Ecological risks. The impact of nanostructures on the environment
may be significant because of the potential for: (i) bioaccumulation,