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.
Yet governments are only beginning to grapple with those dangers. Japan's labor department issued a notice in February requiring measures to protect workers from exposure to nanomaterials: It may be the world's first nano-specific regulation affecting actual practices. Previously, Berkeley, California -- ever ready to stand alone -- had adopted what is apparently the only nano-specific regulation in the United States: a requirement that companies submit toxicology reports about nanomaterials they're using.
At the federal level, the EPA launched a voluntary reporting program in January; industry participation has been anemic. Both the EPA and the Food and Drug Administration have so far declined to regulate nanomaterials as such, saying they're covered under existing regulations. The National Institute for Occupational Safety and Health has issued recommendations for handling nanomaterials, but the agency has no enforcement power.
The European Union, by contrast, is taking a precautionary approach. While U.S. regulators generally presume products to be safe until proven harmful, the EU's new REACH legislation demands that manufacturers demonstrate the safety of their chemicals. Just last week, the EU released a document concluding that nanorisks "can be dealt with under the current legislative framework," with some modifications. For example, the document says that under REACH, when companies introduce nanoforms of existing substances, they must provide additional material about "the specific properties, hazards, and risks" of the nanomaterials.
At this point, however, many of the most basic questions about those nanohazards are unanswered. What materials are harmful, in what particle sizes and shapes, under what conditions? Who is at risk: Workers? People using nano-enabled products? Wildlife and ecosystems? How should we measure exposures?
The U.S. government spends $1.5 billion a year on nano research. Less than 5 percent of that is aimed at addressing these fundamental questions.
What is known about nanohazards counsels caution.
Nanomaterials are so small that they travel easily, both in the body and in the environment. Their tiny size and high surface area give them unusual characteristics: insoluble materials become soluble; nonconductive ones start conducting electricity; harmless substances can become toxic.
Nanoparticles are easily inhaled. They can pass from the lungs into the bloodstream and other organs. They can even slip through the olfactory nerve into the brain, evading the protective blood-brain barrier. It's not clear whether they penetrate the skin. Once they're inside the body, it's not clear how long they remain or what they do. What's more, current science has no way of testing for nano-waste in the air or water, and no way of cleaning up such pollution.
The tiny cylinders known as carbon nanotubes, or CNTs, are among the most widely used nanomaterials. These tubes, which come in different sizes and shapes, lend extraordinary strength and lightness to bicycle frames and tennis rackets; researchers are also investigating uses in medicine, electronics and other fields. The recent UK study found that long, straight CNTs, when injected into lab mice, cause scarring even faster than asbestos. One of the investigators predicts the scarring will lead to cancer; other experts are less sure. The study doesn't prove whether it's possible to inhale enough CNTs to cause the same results as the injections. But which workers want to serve as the test cases?
Another red flag is silver. Manufacturers are lacing ordinary household objects -- from toothpaste to teddy bears -- with nanoparticles of silver, long known for its disinfecting powers. A recent experiment on nanosilver-containing socks, touted as odor-eating, found that silver particles leaked out into the wash water. Once there, the silver could interfere with water-treatment efforts, in part by killing good microbes as well as the nasty ones, and might threaten aquatic life (a fear supported by the zebrafish study).
When Samsung started marketing a washing machine that emits silver ions two years ago, a national association of wastewater treatment authorities asked the U.S. Environmental Protection Agency to regulate such equipment as pesticides. And indeed, EPA has required some manufacturers to register nanosilver-containing products -- like computer keyboards -- as pesticides or drop their germ-killing claims.
A farm-oriented pesticide law dating to 1947 is scarcely the right tool for addressing the 21st-century hazards of nanotechnology. But it's the only tool that EPA enforcers have, since the agency's policymakers have explicitly declined to regulate nanomaterials as such.
What Price Convenience?
Of the hundreds of nano-enhanced products now on the market, many are cosmetics, and many others, such as clothing and computer peripherals, are spiked with silver for unnecessary antibacterial effects. Convenience items, like stain-resistant sofas and static-free fleece, are a third big category.
It would be easy to say, "Who needs this stuff? Just wash your hands (or feet, in the case of the smell-resistant socks), clean up your spills and keep the nano magic on the shelf until we know whether it's safe." Indeed, some environmental groups are calling for a moratorium on nano-containing products.
But nanotech also has a tremendous upside in medicine -- whether for treating cancer or regrowing bones -- and in green applications, from affordable solar cells to super-efficient water filtration. In any case, this technology is not going away. The U.S. House of Representatives voted on June 5 to reauthorize the $1.5 billion-a-year National Nanotechnology Initiative; the Senate is expected to act in the coming weeks.
The House bill mandates "a detailed implementation plan for environmental, health, and safety research." That's an important step forward, but it's not enough. As we hurtle into this very small future, we need to pay much more attention to the potentially large risks.