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VetBooks.ir Chapter 18

Toxicity of Nanomaterials

Deon van der Merwe and John A. Pickrell

INTRODUCTION properties is increasing, and have already found commer-
cial application in sporting goods, tires, sunscreens, sani-
The toxicology of nanomaterials has emerged as a chal-
tary ware coatings, stain resistant textiles and clothing,
lenging field of investigation because the widely applied
food products, and electronics (Hoet et al., 2004; Nel
toxicological paradigm, “the dose makes the poison,”
et al., 2006 Tsuji et al., 2006). The list of products incor-
appears to break down when the toxicological effects of
porating nanotechnology is expected to continue to
materials are investigated at the nanometer scale. At this
expand indefinitely. By some estimates, growth of nano-
scale, the physical chemical characteristics of materials technologies and use of ENMs will far exceed the impact
are highly dependent on unit size and shape, and their
of the industrial revolution; they were predicted to become a
interactions with biological systems may differ markedly
one-trillion-dollar market by 2015 (Neletal.,2006).
from chemicals in solution, and from larger particles. The
However, in spite of the seemingly unstoppable success
mass of nanomaterial to which susceptible tissues are
of this technology, the unique properties of ENMs also
exposed therefore becomes relatively less important as a
present considerable new challenges to understanding,
determinant of the degree of biological impact compared
predicting, and managing potential adverse health effects
to the size and form of the material. Particles, fibers, rods,
following exposure. Technological development and
or tubes with one or more dimensions ,100 nm are gen-
applications are outpacing research for safe use and docu-
erally referred to as nanomaterials, or more specifically as
mentation of health and environmental risk (Hoet et al.,
nanoparticles (also known as ultrafine particles), nanofi-
2004; Tsuji et al., 2006). Although exposure to ENMs is
bers, nanorods, or nanotubes. Nanomaterials are formed
often intentional and controlled, widespread use of
in nature during combustion, geological processes, and
increasing quantities of ENMs increases the likelihood of
biological processes. They are also commonly produced
uncontrolled human and animal exposure to nanomaterials
unintentionally by man in processes such as power gener-
in quantities that may result in biological effects. The
ation from coal, the combustion of fuels in automobiles,
future success of nanotechnology will be influenced by
and by many other industrial, engineering, and domestic
the level of public acceptance of the risks from exposure
activities. Additionally, and at a rate that is rapidly accel-
to ENMs, relative to the benefits. The increased demands
erating, nanomaterials are manufactured intentionally
for development to obtain the promised benefits from
through molecular-level engineering to obtain materials
nanomaterials is balanced by an increasing need for a pro-
with unique mechanical, optical, electrical, magnetic, and
active approach in estimating the environmental and
chemical properties (Tsuji et al., 2006; Richards, 2009).
health costs (Ngo et al., 2008).
These materials can be referred to as engineered nanoma-
Concerns regarding the suitability of traditional toxi-
terials (ENMs). They form the core of a rapidly growing
cological assessment methods for evaluating ENMs gave
industry where ENMs are incorporated into a wide variety
birth to a relatively new discipline, named nanotoxicol-
of manufactured products. The increasing use of ENMs,
ogy. The discipline can be defined as: “the study of the
and the uncertainties associated with their unusual and
adverse effects of ENMs on living organisms and ecosys-
often poorly understood biological effects, creates con-
tems, including the prevention and amelioration of such
cern regarding their potential for causing unanticipated
adverse effects” (Oberdo ¨rster, 2010). As with conven-
adverse health effects (Fig. 18.1).
tional chemicals, risk assessment will be the basis of
Investigators continue to discover unique properties of
assessing and regulating exposure to nanomaterials to pro-
materials at the nanometer scale (Hoet et al., 2004).
tect human, animal, and environmental health. Many
Commercialization of products that exploit these unique
applications will likely have limited, or at least
Veterinary Toxicology. DOI: http://dx.doi.org/10.1016/B978-0-12-811410-0.00018-0
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