Nanotechnology – new chances, new risks
The prefix “nano” is derived from the Greek word for dwarf (nánnos). A
nanometre (nm) is one millionth of a millimetre (e.g. a single human
hair is about 80,000 nm wide). The term nanotechnology refers to a range
of technologies performed on a nanometre scale with widespread
applications, encompassing research as well as the processing and
production of systems or structures of up to 100 nm in size.
Application
Nanotechnologies offer a lot of benefits and new possibilities in the
field of medical applications, chemistry, as well as information and
communication technology. Although nanotechnological research is still
at the beginning, a wide variety of nanoscale materials and surfaces are
already in use in cosmetics, textiles, household cleaning products,
filters, paints and coatings as well as in food.
One of the most well-known consumer products is a type of glass for
windows which is coated with titanium oxide nanoparticles that react to
sunlight and break down dirt. When water hits the glass, it spreads
evenly over the surface instead of forming droplets, and runs off
rapidly taking the dirt with it.
Possible risks
Nanotechnology is considered to be a key technology of the 21st century,
but the uncertainty of its effects on man and the environment gives some
cause for concern and remains to be elucidated. Nanomaterials are
defined as substance particles smaller than 100 nm and associated with
very large surface to volume ratios resulting in different physical and
chemical properties as well as higher reactivity. Therefore, it is not
possible to extrapolate from the toxicology of non-nanosized forms of
the same substance to the toxicology of the nanosized materials.
Regulation
These findings have very important regulatory implications: Evaluation
under the current regulation as well as under REACH is based on mass
concentration data, since in toxicology the paradigm exists that health
effects are correlated to the mass of the agent to which the individual
is exposed. In contrast, for nanoparticles the number concentration and
the resulting total surface area determine the interaction with
biological systems. Therefore, the dose expressed as surface area and
the number concentration appear to be more relevant for exposure.
Effects on human health and on the environment
When considering the hazards associated with nanoparticles, the size,
the shape, the surface (including surface charge) and the chemical
composition of the nanoparticle are important. There are many open
questions concerning the absorption, distribution, metabolism and
excretion of nanosized material in the human body. However, some
nanoparticles may translocate through membranes, and neuronal uptake,
translocation in the axon and the potential to cross the blood brain
barrier have also been reported.
One mechanism of the toxicity of nanoparticles is likely to be the
induction of oxidative stress in cells resulting in cytotoxicity and
inflammation. An important aspect of risk assessment that needs to be
clarified as well is the potential for persistence of nanoparticles in
humans and the potential for bioaccumulation in the environment.
Testing methods
Conventional toxicity and ecotoxicity tests have already been shown to
be useful in evaluating hazards of nanoparticles. However, some methods
may require modification and some new testing methods may also be
needed.
For routine characterization of the physico-chemical properties of
nanoparticles appropriate methodologies must be made available.
Furthermore, (to provide a basis for evaluating the risk and the
risk-reducing measures to be implemented,) methodologies and equipment
need to be developed for routine measurements of representative exposure
to free nanoparticles.
Conclusion
In order to ensure the safe use of nanomaterials and the ensuing
benefits, it is necessary to lay the legal and methodological
foundations for evaluating the long-term effects of nanotechnology on
man and the environment.
Source:
Umweltbundesamt Austria
Additional reading:
The
European strategy for nanotechnology and the nanotechnology Action Plan
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