Big questions for tiny particles

The study noted, for example, that the field is too fluid to make any solid assessment of the kinds of technologies it will yield in the next 10 years or their effects. It also notes that calls have arisen over the past few years for a moratorium on making nanomaterials until their interaction with living organisms is better understood. While these calls square with the "precautionary principle" that many people apply to environmental issues, the study also acknowledges that "an externally imposed nanotech moratorium seems both unpractical and probably damaging at present."

Perhaps the area of most immediate concern involves public and workplace health issues as well as environmental issues relating to newly developed nanomaterials - especially particles, which can be inhaled or absorbed through the skin.

Vicki Colvin, director of the Center for Biological and Environmental Nanotechnology at Rice University, notes that at nano-meter scales, particles not only can penetrate barriers such as skin more easily, but their small size and large numbers can provide more surface area on which chemical reactions can take place than a single particle of equal total mass. This feature could in effect accelerate chemical reactions that may or may not have an unpleasant effect on humans.

Another worry - not unique to nanotechnology - is economic. Inspired by the water- and dirt-defying surfaces of lotus flowers, DaimlerChrysler Research is looking at specially designed nanoparticles to make wheel rims and auto-body paint self-cleaning. If cars clean themselves, goodbye Scrub-A-Dub carwashes?

Confronting the long-term concerns over "intelligent" nanobots and tiny self-assembling machines is harder. Dr. Colvin doesn't dismiss them out of hand but says, "To me, as a scientist, the issue is: Can I test these questions? Nano-bots are not a testable concern because they are so far out there."

Nevertheless, researchers still are trying to learn from the early days of recombinant DNA research, when scientists imposed a moratorium on their work until they had agreed on a set of guidelines addressing the safety concerns. Nanotech researchers gathered three years ago in Palo Alto, Calif., to establish guidelines for safe and responsible research, which included provisions governing self-replicating machines and molecular manufacturing.

Meanwhile, in December the federal government is slated to hold its second meeting in three years to explore the implications of nanotech for society. Taking a cue from the Human Genome Project, the National Nanotechnology Initiative is funding research into the implications of nanotech, as well as for nanotech R&D itself. And in two nanotech funding bills before Congress, lawmakers are weighing whether to establish a separate institute to study the social and ethical implications of nanotechnology, or to ensure that such studies are administered as part of the existing research effort.

"Public acceptance is no longer a given," Dr. Colvin says. "The public ... sees risks, which must be quantified. It's the ethical duty of scientists to evaluate those risks."

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