Nanotech's tiny revolution raises caution

In a Woodland warehouse cluttered with particle detectors and chambers where mice inhale smoke, UC Davis researchers are trying to learn if a swirl of carbon with tantalizing promise could turn lethal.

Will it lodge in the lungs, causing scars that hinder breathing? Will its cousins climb up nerves in the nose to reach the brain?

Or will some of the weirdest little stuff ever created by humans stream into medicine, electronics, oil refining and food packaging with little or no effect on human health?

Those questions, which have captured global attention, remain largely unanswered as the products of nanotechnology emerge in the marketplace.

"This is a whole new category of substances," said Paul Schulte, who heads a nanotechnology research center for the National Institute for Occupational Safety and Health, or NIOSH.

"There are so many great properties in the nano scale," Schulte said. Yet the same features that could build tomorrow's marvels "may have potential toxic effects, too."

The "nano" scale is small almost beyond imagining -- starting at 1 nanometer, which is one billionth of a meter. A single red blood cell is about 7,000 nanometers wide.

Things that small follow different rules than their bigger counterparts. Aluminum can become more explosive. Gold may glimmer green or red. Carbon can get stronger and conduct electricity better. Sometimes the slightest design change -- make it 4 nanometers instead of 2, create a sphere instead of a tube -- whirls out new possibilities of color, electrical charge, melting temperature or other characteristics.

Each variation could turn into a gold mine or a pest, able to slip through cell membranes and interact with human biology and the environment on the scale of DNA.

"At the moment, nobody has died from engineered nanomaterials. To our knowledge nobody has even gotten sick," said physicist Andrew Maynard. "We have an opportunity to try to mitigate potential risks before they get significant," said Maynard, scientific adviser to the emerging nanotechnologies project at the Woodrow Wilson International Center for Scholars.

The Washington, D.C.-based center, which is tracking consumer products that claim nano ingredients, has called for regulations and risk assessments that better reflect the peculiar twists of the world at nano scale.

It is a world of increasing variety, as researchers and engineers find better ways to tinker at 1 to 100 nanometers, tweaking a few molecules here, a few there.

So far, nanotechnology has produced stain-resistant fabrics, potent sunscreens that go on clear instead of white, antimicrobial storage containers to keep food fresher longer, lightweight yet powerful golf clubs and tennis rackets, and hundreds of other consumer products, from cosmetics to contraceptives.

Some nano-enhanced medications are in use today, including a breast cancer drug with improved solubility. More than 100 other drugs and medical devices are undergoing animal or clinical trials, according to David Rejeski, who heads the Woodrow Wilson nanotech project.

Nanocatalysts have increased efficiency and cut waste in oil refining so significantly that their economic impact in that industry alone dwarfs most consumer applications, said Mike Roco, the National Science Foundation's senior adviser for nanotechnology.

Roco and many others are certain this is only the beginning.

"By 2015 we will have the basic understanding of how cancer works and how to treat cancer," Roco insists. "This is no longer a dream."

Semiconducting nanocrystals called quantum dots, which glow under ultraviolet light, may be able to play a role helping surgeons find and remove every cell of a tumor. Tailored nanoparticles might deliver drugs to certain organs or sites, sparing healthier tissue.

Those looking into nanotechnology's possible downsides are scrambling to catch up.

No one expects to be able to test or analyze the hundreds of unique structures pouring out of labs. There are just too many. So researchers will look for patterns, and they don't need to start from zero.

Human bodies have been under nano-assault for eons. From sea air, mining dust and cooking fires, ultrafine particles have swirled into our lungs. Gas furnaces, diesel engines and welding all emit nano-sized particles linked or suspected in a range of ailments.

Based on what's known about the damage caused by very small airborne particles, NIOSH is recommending against inhaling nanomaterials in the workplace, although no U.S. regulations require respiratory protection.

Meanwhile, uneasy consumer and health groups want the public to be better informed. This spring, eight organizations petitioned the federal Food and Drug Administration to require labels for cosmetics and other goods with nanoparticles, and to do safety testing on nano sunscreens. The agency has not yet responded.

For newly devised nano creations, at least three key questions need investigating, said Nigel Walker, lead scientist for the National Toxicology Program's nanotechnology safety initiative.

Will nanoparticles enter the body in different ways because they're so small? Once breathed, eaten or absorbed through the skin, will they accumulate dangerously in places a larger particle wouldn't? And will the nanoparticles interact with tiny structures in the human body in unexpected, damaging ways?

"There's a lot of science to do to build that framework," Walker said.

That's where Steve Teague and his Woodland warehouse come in. Teague, a retired UC Davis aerosol scientist, has been working for nearly two years to pulverize carbon nanotubes.

He's cobbled together sophisticated particle detectors and Wal-Mart hand tools, tried aluminum and glass and brass parts, and battled the nanotubes' tendencies to clump together in sticky knots.

He's hoping to supply Kent Pinkerton, director of UC Davis' Center for Health and the Environment, with an airborne, contaminant-free suspension that a mouse could inhale.

The UC Davis team may be one of only three in the United States trying to aerosolize single-walled carbon nanotubes -- a material that looks like rolled-up chicken wire fencing, and is expected to become a widely used industrial product.

In earlier studies, when the nanotubes were suspended in a droplet of liquid and inserted into the lungs of mice, some died and others developed lung damage.

The Davis team and another at NIOSH have been trying aggressively to set up mouse inhalation tests that would better mimic potential workplace exposures. "The more people having a go at this one, the better," said Walker of the National Toxicology Program.

He and others acknowledge, though, that the struggle to get the nanotubes suspended in air may mean they won't be a big problem for workers -- at least in this single-walled variety. That's one more reason so many different nanocreations need to be probed, and are interesting researchers.

Laurie Hopkins, a graduate student working with Pinkerton, has been exposing mice tucked into special tubes to quantum dots, trying to learn whether the nanomaterials will stay in nasal chambers or travel up olfactory nerves into the brain.

At UCLA, a new center has just been established to study nanotoxicities. Its director, Dr. Andre Nel, believes the majority of nanostuff will prove harmless.

Yet he stresses that now, with predictions that nanotechnology could become a trillion-dollar industry, is the time to hunt down those dangerous exceptions.

About the writer:

• The Bee's Carrie Peyton Dahlberg can be reached at (916) 321-1086 or cpeytondahlberg@sacbee.com.