Carbon Nanotubes That Look Like Asbestos, Behave Like Asbestos

New study shows inhaling long, thin carbon nanotubes may result in
asbestos-related disease

WASHINGTON, May 20 /PRNewswire-USNewswire/ -- A major study published today in
Nature Nanotechnology suggests some forms of carbon nanotubes -- a poster
child for the "nanotechnology revolution" -- could be as harmful as asbestos
if inhaled in sufficient quantities.

The study used established methods to see if specific types of nanotubes have
the potential to cause mesothelioma -- a cancer of the lung lining that can
take 30-40 years to appear following exposure. The results show that long,
thin multi-walled carbon nanotubes that look like asbestos fibers, behave like
asbestos fibers.

Discovered nearly 20 years ago, carbon nanotubes have been described as the
wonder material of the 21st Century. Light as plastic and stronger that steel,
they are being developed for use in new drugs, energy-efficient batteries and
futuristic electronics. But since their discovery, questions have been raised
about whether some of these nanoscale materials may cause harm and undermine a
nascent market for all types of carbon nanotubes, including multi- and
single-walled carbon nanotubes. Leading forecasting firms say sales of all
nanotubes could reach $2 billion annually within the next four to seven years,
according to an article in the U.S. publication Chemical & Engineering News.

"This study is exactly the kind of strategic, highly focused research needed
to ensure the safe and responsible development of nanotechnology," says Andrew
Maynard, Chief Science Advisor to the Project on Emerging Nanotechnologies and
a co-author on the paper. "It looks at a specific nanoscale material expected
to have widespread commercial applications and asks specific questions about a
specific health hazard. Even though scientists have been raising concerns
about the safety of long, thin carbon nanotubes for over a decade, none of the
research needs in the current U.S. federal nanotechnology environment, health
and safety risk research strategy address this question."

Widespread exposure to asbestos has been described as the worst occupational
health disaster in U.S. history and the cost of asbestos-related disease is
expected to exceed $200 billion, according to major U.S. think tank RAND
Corporation.

Anthony Seaton, MD, a co-author on the paper and a professor emeritus at the
University of Aberdeen in the United Kingdom, says, "The toll of
asbestos-related cancer, first noticed in the 1950s and 1960s, is likely to
continue for several more decades even though usage reduced rapidly some 25
years ago. While there are reasons to suppose that nanotubes can be used
safely, this will depend on appropriate steps being taken to prevent them from
being inhaled in the places they are manufactured, used and ultimately
disposed of. Such steps should be based on research into exposure and risk
prevention, leading to regulation of their use. Following this study, the
results of which were foreseen by the Royal Society in the U.K. in 2004, we
can no longer delay investing in such research."

Researchers, led by Professor Kenneth Donaldson at the University of Edinburgh
in the United Kingdom, examined the potential for long and short carbon
nanotubes, long and short asbestos fibers, and carbon black to cause
pathological responses known to be precursors of mesothelioma. Material was
injected into the abdominal cavity of mice -- a sensitive predictor of long
fiber response in the lung lining.

"The results were clear," says Donaldson. "Long, thin carbon nanotubes showed
the same effects as long, thin asbestos fibers."

Asbestos fibers are harmful because they are thin enough to penetrate deep
into the lungs, but sufficiently long to confound the lungs' built-in
clearance mechanisms for getting rid of particles.

Donaldson stresses there are still pieces of the puzzle to fill in. "We still
don't know whether carbon nanotubes will become airborne and be inhaled, or
whether, if they do reach the lungs, they can work their way to the sensitive
outer lining. But if they do get there in sufficient quantity, there is a
chance that some people will develop cancer -- perhaps decades after breathing
the stuff," states Donaldson.

There is a silver lining to this research. According to Donaldson, "Short or
curly carbon nanotubes did not behave like asbestos, and by knowing the
possible dangers of long, thin carbon nanotubes, we can work to control them.
It's a good news story, not a bad one. It shows that carbon nanotubes and
their products could be made to be safe."

But Donaldson added that the present study only tested for fiber-like behavior
and did not exonerate carbon nanotubes from damaging the lungs in other ways.
"More research is still needed if we are to understand how to use these
materials as safely as possible," he notes.

Carbon nanotubes are atom-thick sheets of graphite formed into cylinders. They
may be formed from a single layer of graphite or they may consist of multiple
concentric layers of graphite, resulting in multi-walled carbon nanotubes.
While the diameter of a nanotube can vary from a few nanometers up to tens of
nanometers, they can be hundreds or even thousands of nanometers long. Carbon
nanotubes come in many forms, with different shapes, different atomic
arrangements, and varying amounts and types of added chemicals -- all of which
affect their properties and might influence their impact on human health and
the environment.

"This is a wakeup call for nanotechnology in general and carbon nanotubes in
particular," says Maynard. "As a society, we cannot afford not to exploit this
incredible material, but neither can we afford to get it wrong -- as we did
with asbestos."

The paper can be found on the journal's website: http://www.nature.com/nnano

About Nanotechnology

Nanotechnology is the ability to measure, see, manipulate and manufacture
things usually between 1 and 100 nanometers. A nanometer is one billionth of a
meter; a human hair is roughly 100,000 nanometers wide. In 2007,
nanotechnology was incorporated into more than $88 billion in manufactured
goods. Lux Research projects that figure will grow to $2.6 trillion by 2014,
or about 15% of total global output.

The Project on Emerging Nanotechnologies (www.nanotechproject.org) is an
initiative launched by the Woodrow Wilson International Center for Scholars
and The Pew Charitable Trusts in 2005. It is dedicated to helping business,
government and the public anticipate and manage possible health and
environmental implications of nanotechnology.

SOURCE The Project on Emerging Nanotechnologies

Colin Finan, +1-202-691-4321, colin.finan@wilsoncenter.org, or Sharon
McCarter, +1-202-691-4016, sharon.mccarter@wilsoncenter.org, both of The
Project on Emerging Nanotechnologies