Introduction - Nanotechnologies for Water Environment Applications - page 10

It is possible that the unique characteristics of NMs result in harmful interactions
to the environment and biological systems. The i n vivo effects of NPs to some
ecological groups [e.g., invertebrates, vertebrates (e.g. fish) and plants] indicate that NPs
can be highly toxic. For example, colloidal C 60 fullerenes are taken up by the
largemouth bass and accumulated into the fish brains. Eukaryotes (e.g., protists and
metazoans) have highly developed processes for the cellular internalization of nanoscale
(100 nm or less) and microscale (100-100,000 nm) particles, namely endocytosis and
phagocytosis, respectively. These processes are integral to key physiological functions
such as intracellular digestion and cellular immunity. However, prokaryotes, like
bacteria, may be largely protected against the uptake of many types of NMs, since they
do not have mechanisms for the transport of NMs across their cell wall. It is worthy of
noting that studies on the antimicrobial properties of NMs and their interactions with
microorganisms are limited. It is not clear how microbial communities respond to NMs
as a function of NM chemical and physical properties (such as composition and stability)
and the environment in which the microbial community exists.
The cytotoxic mechanisms of NMs on living organisms depend on the fate and
transport of NMs upon their physical/chemical/biological interactions with cell
materials. Currently, there are many unknowns concerning the fate and transport of NMs
in the environment, including effects of different interphase transfer and transformation
processes on the form, complexity, and the mechanisms of NM transport and removal in
the environment. At present, fundamental research is focusing on (a) the influence of
particle size, shape and number on basic aspects of ecotoxicology, mechanisms of
action, dose response relationships (at all levels of biological organization) and
toxicokinetic profiles (adsorption/uptake, distribution, metabolism and excretion), and
(b) the extent to which fate, behavior and ecotoxicology of nanoparticles is governed by
specific properties, common to some or all nanoparticles (DEFRA, 2006). Important
research questions to be answered are related to (a) dose response relationships (e.g., are
they affected by particles size, number or shape?), (b) interactions between NPs and
other substances (e.g., do NMs affect the fate, behavior or exotoxicology of other
substances in the environment?), (c) fate and transport of NMs (e.g., are NPs more
persistent, bioaccumulative or toxic than those in bulk or dissolved form? What factors
affect NMs' agglomeration and other fate and behavior? Are any fate and transport
effects of NMs generalizable to certain or all classes of particles?), (d) development of
structure/activity relationships to predict fate and transport of NMs in the environment.
Societal Issues , considerable studies have been conducted on the ethical, legal,
and social implications (ELSI) of nanotechnology. Nanoethicists see nanotechnology as
positively impacting our society in the future. For example, it is estimated that
nanotechnology will create an additional 2 - 10 million jobs across the world by 2014
(ETUC, 2008). Many people believe that this technology has a tremendous long-term
potential to completely revolutionize our society, resulting in better understanding of