From: Rose & Crangle, Ltd. (rcltd@nckcn.com)
Date: Tue Aug 09 2005 - 22:32:54 EEST
Fascinating thread. By the way, Susan Gaidos in the August 1 issue of
The Scientist had an article on a nano issue we do not usually consider.
I reproduce parts of it below.
Bob Crangle
Rose & Crangle, Ltd
117 N. 4th Street, PO Box 285
Lincoln, KS 67455
785 524 5050 (fax 3130)
Volume 19 | Issue 15 | Page 29 | Aug. 1, 2005 The Scientist
Conventional approaches to risk assessment, toxicity screening, and ADME
(absorption, distribution, metabolism, and excretion) modeling don't
necessarily apply to nanoscale materials. Even nomenclature is a
problem: Existing measures for regulating new chemical substances
distinguish materials by name, not size. Thus, the Toxic Substances
Control Act (TSCA) inventory, a listing of the more than 80,000
industrial chemicals currently produced or imported into the United
States, classifies carbon nanotubes as a material chemically identical
to diamond.
Yet nanoparticles (those smaller than 100 nanometers in diameter) often
acquire properties absent from their macroscale counterparts; they may
become stronger, lighter, more heat-resistant, or better electrical
conductors, for instance. But they also can be more toxic, being readily
inhaled into the lungs, absorbed through the skin, or transported across
cell membranes. And nobody knows how long such materials may linger in
or be cleared from the environment.
"While there is concern that the nanostructure-dependent properties of
many engineered nanomaterials may lead to them being hazardous, the
direct risk they present to human health will depend on the probability
of exposures occurring, and the extent to which materials entering the
body exhibit behavior associated with their nanostructure," says Julie
W. Fitzpatrick, a scientist with the International Life Sciences
Institute, who is developing toxicity screening strategies.
Too few studies have been completed, says Kristin Kulinowski, executive
director for education and public policy for the National Science
Foundation-funded Center for Biological and Environmental Nanotechnology
(CBEN) at Rice University. "What we do know is that what may be true for
one particular nanoparticle in one form or one application, may not be
true for another," she says. "There have been some studies that have
pointed out particular effects of nanoparticles on certain systems, such
as cells in culture, fish, and rodents. But they have been pretty
limited, and there are still many gaps in our knowledge about
nanoparticle safety."
In one widely publicized 2004 report, Southern Methodist University
researcher Eva Oberdörster found that nanoparticles called buckyballs
can cause brain damage in fish.1 Later that year, Vicki Colvin and
Christy Sayes at CBEN found that buckyballs are also toxic in vitro,
causing 50% of cultured human cells to die at a concentration of 20
parts per billion.2 "The findings from those [CBEN] experiments were
interesting in that they showed that the toxicity varied dramatically,
according to what was happening at the surface of those particles," says
Kulinowski.
Similarly, Mark Banaszak Holl of the University of Michigan has found
that a particle's surface chemistry can govern whether a particle works
well for biomedical applications.3 And North Carolina State University
toxicologist Nancy Monteiro-Riviere showed that, depending on how
they're made, some nanoscale materials that may otherwise irritate the
skin can be rendered nontoxic.4 Her group is now studying quantum dots,
carbon fullerenes, and iron oxide nanocrystals to see if these
nanomaterials can also penetrate to the dermis.
While participants generally lauded the group's effort, some said its
proposal doesn't go far enough. In a report statement presented at the
meeting, a coalition of 17 environmental and health advocacy groups,
including the Natural Resources Defense Council, the Sierra Club, and
the Breast Cancer Fund, proposed classifying nanomaterials as "new"
chemical substances under TSCA, because they are new organic or
inorganic substances of a particular molecular identity.
The coalition backed recommendations from the Royal Society and the
Royal Academy of Engineering, that nanoparticle release into the
environment be minimized until more is known about how they would affect
ecosystems.
The EPA is now formulating its strategy, and preliminary plans for the
voluntary reporting scheme could arrive later this year. Charles Auer,
director of the EPA's Office of Prevention, Pesticides, and Toxic
Substances, says, "When we will have all these issues resolved, I don't
know. There are a lot of wrinkles here to be sorted through, but there's
a lot of work underway."
-----Original Message-----
From: owner-rp-ml@rapid.lpt.fi [mailto:owner-rp-ml@rapid.lpt.fi] On
Behalf Of Adrian Bowyer
Sent: Tuesday, August 09, 2005 12:52 PM
To: rp-ml@rapid.lpt.fi
Subject: RE: [rp-ml] Nano/fabber politics
Quoting "David K. Leigh" <dkleigh@harvest-tech.com>:
> Now we're talkin' politics - origin of the species. This oughta get
good
> now. :)
Eh?
Oh - One of the things we Europeans can forget completely is that there
are any
politics at all in Darwinian evolution. It feels a bit as if you were
to say,
"Well, if we do the orbital calculations assuming the Earth takes 365.25
days
to go round the Sun..." and an engineer at the back interrupts to say,
"Earth
go round the Sun! That's blasphemy."
You'd blink a bit, wouldn't you...
Yours
Adrian
http://staff.bath.ac.uk/ensab
http://reprap.org
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
This archive was generated by hypermail 2.1.7 : Mon Jan 02 2006 - 08:09:16 EET