Nanotech: Why Something So Small Can Be So Dangerous

"It's green, it's clean, it's never seen -- that's nanotechnology!"

That exuberant motto, used by an executive at a trade group for nanotech entrepreneurs, reflects the buoyant enthusiasm for nanotechnology in some business and scientific circles.

Part of the slogan is indisputably true: nanotechnology -- which involves creating and manipulating common substances at the scale of the nanometer, or one billionth of a meter -- is invisible to the human eye.

But the rest of the motto is open for debate. Nanotech does hold clean and green potential, especially for supplying cheap renewable energy and safe drinking water. But nanomaterials also pose possible serious risks to the environment and human health -- risks that researchers have barely begun to probe, and regulators have barely begun to regulate.

What's more, the potential damage could take years or even decades to surface. So these tiny particles could soon become the next big thing -- only to turn into the next big disaster.

Nano enthusiasts see it as the next "platform technology" -- one that will, like electricity or micro-computing, change the way we do almost everything. While that prediction is still unproven, there's no question that nanotech is booming. Universities, industry, and governments around the globe are pouring billions into creating and developing nanoproducts and applications. A range of nanotechnologies is already used in more than 600 consumer products -- from electronics to toothpaste -- with global sales projected to soar to $2.6 trillion by 2014.

Environmentalists, scientists, and policymakers increasingly worry that nanotech development is outrunning our understanding of how to use it safely. Consider these examples from last month alone:

• An animal study from the United Kingdom found that certain carbon nanotubes can cause the same kind of lung damage as asbestos. Carbon nanotubes are among the most widely used nanomaterials.
• A coalition of consumer groups petitioned the U.S. Environmental Protection Agency to ban the sale of products that contain germ-killing nanosilver particles, from stuffed animals to clothing, arguing that the silver could harm human health, poison aquatic life, and contribute to the rise of antibiotic resistance.
• Researchers in Singapore reported that nanosilver caused severe developmental problems in zebrafish embryos -- bolstering worries about what happens when those antimicrobial products, like soap and clothing, leak silver into the waste stream.
• The U.S. Department of Defense, in an internal memo, acknowledged that nanomaterials may "present... risks that are different than those for comparable material at a larger scale." That's an overarching risk with nanomaterials: Their tiny size and high surface area make them more chemically reactive and cause them to behave in unpredictable ways. So a substance that's safe at a normal size can become toxic at the nanoscale.
• Australian farmers proposed new standards that would exclude nanotechnology from organic products.
• The European Union announced that it will require full health and safety testing for carbon and graphite under its strict new chemicals law, known as REACH (for Registration, Evaluation, and Authorisation of Chemical Substances). Carbon and graphite were previously exempt, because they're considered safe in their normal forms. But the U.K. study comparing carbon nanotubes to asbestos, along with a similar report from Japan, raised new alarms about these seemingly harmless substances.

Old Materials, New Risks

The EU's move is a critical step toward recognizing nanomaterials as a potential new hazard that requires new rules and new information.

The raw materials of nanotechnology are familiar. Carbon, silver, and metals like iron and titanium are among the most common. But at the nanoscale, these well-known substances take on new and unpredictable properties. That's what makes them so versatile and valuable. It also makes them potentially dangerous in ways that their larger-scale counterparts are not.