Big questions for tiny particles

From clear sunscreen to self-cleaning cars, nanotechnology seeps into daily life and starts to raise tough ethical issues.

In the days when the Beach Boys ruled the radio and bikinis were the rave, beaches were populated by noses: big and slathered white with zinc oxide to avoid sunburn.

Today the big white noses are gone. Instead of relying on thick goo, many manufacturers now use titanium-dioxide particles so small the sunscreen looks invisible but still reflects away ultraviolet light. Chalk it up to an early use of nanotechnology, where "big" is defined as 1/1000th the width of a human hair and the possibilities look potentially limitless.

Yet even as nanotech goes commercial, environmental groups worry about its effect on health and safety. Long term, analysts say, society will have to confront a broad set of ethical and social issues as it deals with humanity's growing ability to manipulate atoms, molecules, and biology's genetic code. The real crunch may come if researchers manage to merge nanotechnology and biotechnology.

If they do combine the two - what Nobel Prize-winning chemist Richard Smalley has dubbed the "wet" and "dry" sides of nanotechnology - "then you start talking about some long-range issues," says Clayton Teague, who heads the coordinating office for the federal National Nanotechnology Initiative here. These might include the desirability of restoring or enhancing human capabilities such as sight or strength through hybrid nanotech-biotech devices.

Although not strictly nanotechnology, researchers have tested in humans tiny arrays of light- sensing diodes on a chip, which act as replacement photoreceptors, in a bid to restore human sight. Over the very long term, some researchers speak of tiny nanobots, perhaps with some form of artificial intelligence, injected into humans that repair damaged organs or remove obstructions.

Many researchers and industry insiders reject such speculation as hype. But others are less dismissive.

"Whether something looks loopy or not is a function of your time horizon," says Glenn Rey-nolds, a law professor at the University of Tennessee at Knoxville who specializes in nanotech issues. Some ideas, such as self-replicating nanobots, "are not loopy at all if you look far enough into the future."

Whatever nanotech's future, it's already big business. The federal government is pouring so much money into the field that the National Nanotechnology Initiative "is on track to become the second highest-funded science program after NASA," says Mark Modzelewski, executive director of the NanoBusiness Alliance in New York. Meanwhile, venture capital is flowing into the field at a pace that would make many biotech companies envious. In addition, the alliance is leading the US's first nanotech trade mission to Europe in September.

It's this growing level of commercial activity that is drawing the attention of groups such as Greenpeace, which late last month issued a report on the potential impact of nanotechnology and artificial intelligence on society. The report drew heavy criticism from many in the nanotech field. Others who have disagreed with the organization in the past say this effort was relatively tame and makes some useful points.

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."