- Environmental Concerns Regarding Nanomaterials, Nanoparticles
and Molecular Machines
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- http://www.azonano.com/details.asp?ArticleID=1074
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- Environmental Concerns Regarding Nanomaterials,
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- Nanoparticles and Molecular Machines
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- Topics Covered
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _Background
- Background
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _Could_Nanomaterials_Infiltrate_Huma
- Could Nanomaterials Infiltrate Humans?
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _What_Effects_might_Nanomaterials%20ha
- What Effects might Nanomaterials have on Living Systems?
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _Nanoparticles_and_the_Human%20Immune
- Nanoparticles and the Human Immune System
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _What_are_the_Effects%20of%20Nanotubes%20o
- What are the Effects of Nanotubes on the Human Body?
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- http://www.azonano.com/details.asp?ArticleID=1074#_
- What_about_the_Dangers%20of%20Self-Repl
- What about the Dangers of Self-Replicating Nanorobots?
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- http://www.azonano.com/details.asp?ArticleID=1074#
- _Are_there_Checks_to%20Ensure%20that%20Mol
- Are there Checks to Ensure that Molecular Machines are
Produced Safely?
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- Background
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- The potential impact of nanostructured particles and
devices on the environment is perhaps the most high profile of contemporary
concerns. Quantum dots, nanoparticles, and other throwaway nanodevices
may constitute whole new classes of non-biodegradable pollutants that scientists
have very little understanding of. Essentially, most nanoparticles produced
today are mini-versions of particles that have been produced for a long
time. Thus, the larger (micro) versions have undergone testing, while their
smaller (nano) counterparts have not.
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- For example, Vicki Colvin, Executive Director of Rice
University's Centre for Biological and Environmental Nanotechnology (CBEN)
has recently postulated that nanomaterials provide a large and active surface
for adsorbing smaller contaminants, such as cadmium and organics. Thus,
like naturally occurring colloids, they could provide an avenue for rapid
and long-range transport of waste in underground water.
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- Could Nanomaterials Infiltrate Humans?
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- The concern that nanomaterials could bind to certain
common but harmful substances in the environment, such as pesticides or
PCBs, leads to the short-term worry of such materials infiltrating humans.
According to the ETC Group, at a recent fact-finding meeting at the US
Environmental Protection Agency (EPA), researchers reported that nanoparticles
can penetrate living cells and accumulate in animal organs. In particular,
the possibility of toxic elements attaching themselves to otherwise benign
nanomaterials inside bacteria and finding a way into the bloodstream was
acknowledged.
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- What Effects might Nanomaterials have on Living Systems?
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- In addition, very little work has been done in order
to ascertain the possible effects of nanomaterials on living systems. One
possibility is that proteins in the bloodstream will attach to the surface
of nanoparticles, thus changing their shape and function, and triggering
dangerous unintended consequences, such as blood clotting.
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- Nanoparticles and the Human Immune System
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- A second possibility relates to the ability of nanoparticles
to slip past the human immune system unnoticed, a property desirable for
drug delivery, but worrying if potentially harmful substances can attach
to otherwise benign nanomaterials and reside in the body in a similar manner.
According to Colvin, 'it is possible to speculate that nanoscale inorganic
matter is generally biologically inert. However, without hard data that
specifically addresses the issue of synthetic nanomaterials, it is impossible
to know what physiological effects will occur, and, more critically, what
exposure levels to recommend.'
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- What are the Effects of Nanotubes on the Human Body?
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- To illustrate, this report shows how nanotubes, should
industry predictions be realised, are set to become relatively ubiquitous
within the coming decades - such materials are already finding their way
into a number of products. But it has not yet been determined what happens
if, for example, large quantities of nanotubes are absorbed by the human
body.
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- One prominent concern relates to the structural similarities
between nanotubes and asbestos fibres: like the latter, nanotube fibres
are long, extremely durable, and have the potential to reside in the lungs
for lengthy periods of time. One recent study, conducted by the National
Aeronautics and Space Administration (NASA), has shown that breathing in
large quantities of nanotubes can cause damage to lungs. However, as nanotubes
are essentially similar to soot, then this is not particularly surprising.
On the whole, far more experiments are required before the issue can be
resolved.
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- What about the Dangers of Self-Replicating Nanorobots?
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- Self-replication is probably the earliest recognized
and best-known long-term danger of molecular nanotechnology (MNT). This
centres upon the idea that self-replicating nanorobots capable of functioning
autonomously in the natural environment could quickly convert that natural
environment (i.e. 'biomass') into replicas of themselves (i.e. 'nanomass')
on a global basis. Such a scenario is usually referred to as the 'grey
goo' problem but perhaps more properly termed 'global ecophagy' (Freitas).
The main feature that distinguishes runaway replication as a long-term
environmental concern is the extreme difficulty involved in constructing
machines with the adaptability of living organisms. As Freitas notes:
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- 'The replicators easiest to build will be inflexible
machines, like automobiles or industrial robots To build a runaway replicator
that could operate in the wild would be like building a car that could
go off-road and fuel itself from tree sap. With enough work, this should
be possible, but it will hardly happen by accident. Without replication,
accidents would be like those of industry today: locally harmful, but not
catastrophic to the biosphere. Catastrophic problems seem more likely to
arise though deliberate misuse, such as the use of nanotechnology for military
aggression.'
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- Are there Checks to Ensure that Molecular Machines are
Produced Safely?
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- This is not to imply, however, that the risk that molecular
machines designed for economic purposes might replicate unchecked and destroy
the world should be written off altogether: while the danger seems slight,
even a slight risk of such a catastrophe is best avoided. To this end,
David Forrest has produced a set of guidelines to assure that molecular
machines and their products are developed in a safe and responsible manner.
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- Note: A complete list of references can be found by referring
to the original text.
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- Primary author: Alexander Huw Arnall.
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- Source: Greenpeace report, 'Future Technologies, Today's
Choices Nanotechnology, Artificial Intelligence and Robotics; A technical,
political and institutional map of emerging technologies', July 2003.
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