Widespread use of nanoscale silver will challenge regulatory agencies to balance
important potential benefits against the possibility of significant environmental
risk, highlighting the need to identify research priorities concerning this
emerging technology, according to a new report released today by the Project
on Emerging Nanotechnologies (PEN).
But existing information about the impact of silver on the environment offers
a starting point for some assessments of nanosilver, the report argues. See
www.nanotechproject.org/n/silver to obtain a copy of the report.
The issue of assessing the risks posed by nanoscale silver was highlighted
after the Environmental Protection Agency's (EPA) San Francisco office earlier
this year imposed a landmark fine of over $200,000 on a California company selling
computer keyboards and mouses coated with nanosilver. EPA issued the fine on
the grounds that the products should have been registered under federal pesticide
law because of the company's germ-killing claims.
Similar fines have not been imposed since, but the action is increasing attention
on the potential risks posed by nanoscale silver and oversight of nanotechnology
as a whole. There currently are more than 200 manufacturer-identified nanosilver
products on the market and contained in the online nanotechnology consumer products
inventory maintained by PEN —everything from baby carriages and air filters
to athletic socks and coin-operated washing machines. See www.nanotechproject.org/consumer
to search the inventory.
Silver itself is classified as an environmental hazard by EPA because it is
more toxic to aquatic plants and animals than any metal except mercury. Even
if a nanoparticle itself is not especially toxic, silver nanoparticles increase
the effectiveness of delivering toxic silver ions to locations where they can
"We need not assume that because nano is new, we have no scientific basis
for managing risks," says Dr. Samuel N. Luoma, the author of the PEN report
Silver Nanotechnologies and The Environment: Old Problems or New Challenges?,
which also offers a dozen lessons concerning silver in general that can be followed
for managing the potential environmental risks posed by nanosilver. "Our
existing knowledge of silver in the environment provides a starting point for
some assessments, and points toward some of the new questions raised by the
unique properties for nanoparticles that need to be addressed through new research."
The mass of silver dispersed to the environment from new products could be
substantial if one product, or a combination of such products, becomes widespread.
"The silver that went into wastewaters when millions of people had their
photographs developed taught us that small additions of silver to the environment
make a big difference," says Dr. Luoma, a former senior researcher with
the U.S. Geological Survey who now leads science policy coordination for the
John Muir Institute of the Environment at the University of California, Davis.
"Perhaps more significant, we have no means of detecting nanosilver in
the environment once it is released, even if concentrations rise to levels that
are toxic to aquatic ecosystems."
The U.S. federal government has invested only a small percentage of its overall
nanotechnology research funding in understanding the risks posed by nanomaterials,
according to an analysis conducted earlier this year by PEN (http://www.nanotechproject.org/news/archive/ehs-update/),
further highlighting the need for more research on the potential risks posed
by nanomaterials. In addition, laws and institutions shaped in the mid-20th
Century are not likely to succeed in addressing 21st-Century problems.
"Silver is an old problem, and nanosilver is a new challenge. The scope
of the new challenge is not yet clear because it is uncertain how much nanosilver
is now used as an antimicrobial in commercial and consumer products, and because
new uses are likely to be discovered in the future," says J. Clarence Davies,
a PEN senior adviser and a former EPA policy official. "Regardless of the
scope of the nanosilver problem, it underscores the need for more risk research
and new approaches to oversight to deal with new technologies and problems of
the new century."