As Uses Grow, Tiny Materials' Safety Is Hard to Pin Down
November 3, 2003
By BARNABY J. FEDER
When researchers fashion nanomaterials so small that their
dimensions can be measured in molecules, the unusual and
potentially valuable characteristics of those materials
tend to show up immediately. But as businesses race to
exploit those benefits, investors and policy makers are
finding that pinpointing the potential environmental and
health impacts of nanotechnology could take years.
In fact, the first stages of environmental impact research
are generating more new questions than answers.
Take the experience of researchers at DuPont, who are
testing microscopic tubes of carbon, known as nanotubes,
valued for their extraordinary strength and electrical
conductivity. When the researchers injected nanotubes into
the lungs of rats in the summer of 2002, the animals
unexpectedly began gasping for breath. Fifteen percent of
them quickly died.
"It was the highest death rate we had ever seen," said
David B. Warheit, the research leader, who began his career
studying asbestos and has been testing the pulmonary
effects of various chemicals for DuPont since 1984.
Yet surprisingly, all the surviving rats seemed completely
normal within 24 hours.
What initially looked like disaster pointed to a possible
safety feature: the nanotubes' tendency to clump rapidly
led to suffocation for some rats exposed to huge doses, but
it also kept most tubes from reaching deep regions of the
lung where they could not be expelled by coughing and could
cause long-term damage. Now researchers see the clumping of
carbon nanotubes and other nanomaterials as a new field for
The DuPont research is among the most sophisticated efforts
to date to examine potential hazards of nanoscale
materials, generally defined as those with at least one
dimension less than 100 nanometers (a nanometer is roughly
the width of 10 hydrogen atoms). Such materials are already
embedded in hundreds of products, including sunscreens and
cosmetics, to make them clear; textiles, to make them
stain-resistant; and power machinery, to add durability.
Early research has raised troubling issues. DuPont and
others, for example, found evidence that the cells that
break down foreign particles in rodent lungs have more
trouble detecting and handling nanoparticles than larger
particles that have long been studied by air pollution
No one has yet created a realistic test for the effects of
inhaled nanoparticles; such a test could easily cost more
than $1 million to design and carry out, toxicologists say.
Lungs are not the only concern. Research shows that
nanoparticles deposited in the nose can make their way
directly into the brain. They can also change shape as they
move from liquid solutions to the air, making it harder to
draw general conclusions about their potential impact on
"It's going to be 10 years before we can answer the 'so
what should I do' question for people," said Eva
rster, an aquatic toxicologist at Southern Methodist
University in Dallas. Last month, she began studying how
the spherical carbon molecules known as buckyballs are
absorbed by water fleas. Eventually, her research could
clarify what effects, if any, release of such nanoparticles
into the air and water to monitor or control pollution
might have on the food chain.
"This field is in its infancy," agreed Joseph B. Hughes, a
professor at the Georgia Institute of Technology who
oversees environmental engineering research at the Center
for Biological and Environmental Nanotechnology, which is
at Rice University in Houston. "The first papers and first
results will have to be cautious. The field is growing so
rapidly in the discovery end that questions about their
environmental consequences are still being generated."
Today's nanotechnology applications and those nearing
commercialization use tiny amounts of the materials, and
for that reason many entrepreneurs say there is no reason
yet for them to investigate potential environmental
impacts. DuPont, which has been sued over the health issues
of chemicals used in products like Teflon, however, has
been more cautious. "It would be unwise to claim that just
because there are tiny amounts, it's harmless,'' said Jim
Romine, director for materials science and engineering at
DuPont's global research campus outside Wilmington, Del.
"We need the data to show that."
At any rate, the amounts being used will not stay tiny for
long, if there is any validity to the federal government's
projection that sales of products based on nanotechnology
will reach $1 trillion by 2015. That pace of industrial
adoption is on a collision course with the measured pace of
toxicology and environmental impact research.
Critics like the ETC Group, a technology policy advocacy
group, say the current regulatory regime is inadequate,
with agencies like the Environmental Protection Agency and
the Food and Drug Administration squeezing oversight of the
new materials into existing categories. They want
development put off until regulators and industry agree on
the best practices for handling nanomaterials. Some propose
international supervision of research on potential risks.
Nanotechnology advocates say they support faster and
broader environmental research, but paying for it has not
been a priority for businesses or the government. The
Environmental Protection Agency, which until this year had
focused on supporting research into how nanotechnology
could help clean or protect the environment, is seeking
grant proposals from researchers looking at potential
risks. But the $4 million it expects to award next year for
risk studies is barely measurable against the $847 million
in federal money that President Bush has proposed for
nanotechnology research and development for the 2004 fiscal
The difficulty and cost of researching risk are influencing
business decisions. L'Oral, the cosmetics giant, for
instance, dropped its research on the characteristics of
buckyballs after outside researchers raised questions about
toxicity, said Francis Quinn, a physicist in the company's
research laboratory in France.
Steven T. Jurvetson, a managing director of Draper Fisher
Jurvetson, a venture capital firm that has stakes in nine
nanotechnology companies, steers clear of any that raise
environmental questions for him. "Until other people's
money and research have proven it safe, we'll assume it
isn't," he said.
Some smaller nanotechnology start-ups say they simply do
not have the resources to push into promising areas that
pose health questions. Argonide Nanomaterials of Sanford,
Fla., has fashioned alumina ceramic material into fibers
just two nanometers thick with superb adhesion
characteristics for use in orthopedic surgery, according to
researchers at Purdue University.
But Argonide said it preferred to focus on filtering
products, which are not implanted in the body and thus
require much less testing. The filters, which can remove
arsenic from water and recycle water from urine on the
International Space Station, will soon be available to
filter viruses out of water lines in dental equipment, the
company's vice president, Cindi Prorok, said. But what
happens to the filters once they are used? Ms. Prorok said
she had no idea.
Don't ask, don't tell is the operating mode for much of the
nanotechnology industry these days when it comes to where
discarded products end up. Many companies assume that
because they are working with compounds that are deemed
safe in larger sizes or because the nanomaterials are
embedded in larger products, the particles will not pose
Even with testing, researchers caution that establishing
toxicity is half the challenge. Determining risk also
requires projecting how likely animals and people are to be
exposed to hazardous materials. Thus, inserting carbon
nanotubes in rats' lungs provides data on how toxic they
might be but does nothing to answer the question of what
level of exposure would be necessary for a rat to breathe
in damaging amounts of such particles.
"Our goal is not to look at every individual nanoparticle
and say, is this good or is it bad?" said Dr. Hughes at
Rice. "There are too many particles, it takes too much time
and money and the results are too open to challenge. We are
interested in understanding whether they will behave along
existing models, and if they differ, what science will help
us predict that. There's a growing awareness that it would
be an advantage to the industry to study this before the
problems manifest themselves."