Page 413 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

396 Potential Impacts of Nanomaterials

technological innovations, chemicals, or drugs were released prior to a
broad-based risk assessment, information is needed now regarding the
potential toxicological impact of nanomaterials on human health and
the environment.
New nanomaterials should be thoroughly investigated for occupa-
tional safety during manufacture, exposure scenarios likely to be encoun-
tered by the consumer (e.g., commercial products, medicines, cosmetics),
and postuse release and migration in the environment. Also, the bio-
compatibility of nanomaterials should be evaluated before incorporat-
ing these new structures into biomedical devices or implants produced
by tissue engineering. This chapter describes the known toxicity of sev-
eral classes of nanomaterials.

Fullerenes
Fullerenes or buckyballs (short for buckminsterfullerene) are molecular
). These spheres are made of
structures containing 60 carbon atoms (C 60
carbon and each carbon is bonded to three neighboring carbons of about
one nanometer in diameter. Three scientists first discovered fullerenes
in 1985 while studying “clusters-aggregates of atoms” where they vapor-
ized graphite with a laser in an atmosphere of helium gas to form stable
carbon clusters. It was discovered that only a geometric shape could
combine 60 carbon atoms into a spherical structure of hexagons and
pentagons. This combination of structure was the basis of a geodesic
dome designed by Buckminster Fuller for the 1967 Montreal Exhibition.
Since the newly discovered molecule resembled this architectural struc-
ture, they were termed buckminsterfullerene (Kroto et al., 1985). In
1996, the Nobel Prize was awarded to Curl, Kroto, and Smalley for their
discovery.
Although carbon has many beneficial applications, including pros-
thetic materials, dental implants, bone plates, and heart valves, the
impacts of carbon in the form of fullerenes on human health are largely
unknown. These materials possess unique chemical, mechanical, elec-
trical, optical, magnetic, and biological properties that make them can-
didates for a variety of novel commercial and medical applications. One
aspect of fullerenes that makes them particularly attractive for appli-
cations ranging from drug delivery to cosmetics is that they may be
derivatized in an infinite number of variations to tailor the fullerene’s
properties to a given application.
is
Information regarding the biodistribution and metabolism of C 60
lacking and it has been difficult to study due to the low solubility of C 60
in water coupled with a lack of sensitive analytical techniques for detect-
14
ing fullerenes. In one study, water-soluble C-labeled fullerenes were
orally administered to rats. The fullerenes were not absorbed but were