The unusual properties of tiny particles contain huge promise. But nobody knows how safe they are. And too few people are trying to find out

WAVING a packet of carbon nanotubes accusingly at the assembled American politicians during a hearing last month in Congress, Andrew Maynard was determined to make a point. The nanotechnology expert at the Woodrow Wilson International Centre for Scholars in Washington, DC, had bought the tiny tubes on the internet. They had arrived in the post along with a safety sheet describing them as graphite and thus requiring no special precautions beyond those needed for a nuisance dust.

Dr Maynard’s theatrics were designed to draw attention to a growing concern about the safety of nanotechnology. The advice he had received was at best uncertain, and at worst breathtakingly negligent. For a start, describing carbon nanotubes as graphite was rather like describing a lump of coal as a diamond. Graphite is made of carbon, just like the nanotubes, although the tubes themselves are about 1m times smaller than the graphite that makes up the “lead” in a pencil. Carbon nanotubes may be perfectly safe, but then again, they may have asbestos-like properties. Nobody knows. Indeed, industry, regulators and governments know little about the general safety of all manner of materials that are made into fantastically small sizes.

This lack of knowledge is so great that research can paradoxically add to the problem. Vicki Colvin, a professor of chemistry at Rice University in Texas and one of the world’s leading experts in nanotechnology-risk research, told the same hearing: “If you fund five teams to understand nanotube toxicity, and they get five different answers, your research investment hurts you, because it creates uncertainty. The bad news is that we have way over five different opinions about carbon-nanotube toxicity right now.”

In the past few years the number of consumer products claiming to use nanotechnology has dramatically grown-to almost 600 by one count. Patents are rapidly being filed (see chart 1). For a product to count as nanotechnology, it does not need to contain a tiny machine-though some seers imagine that as the field’s ultimate aim. It is enough merely for some of the material to have been tinkered with at a small scale. Often that can involve grinding down a substance into particles that may be only a few nanometres big-a nanometre is a billionth of a metre-about 100,000th of the thickness of a sheet of paper. These particles can also be engineered into shapes that provide some functional property, like rigidity. The variety of shapes includes rings, shells, wires, beads, cages and plates. The particles and shapes can also be incorporated into other materials to bestow useful properties on them.

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