Lewis Wolpert: 'There have been rumours that nanotechnology could create robots that would devour the world'

It comes to me as rather a shock to find that I am on the same side as Greenpeace and Prince Charles on an environmental issue. They suggest, as a recent article in Science reports, that we should be worrying about the environmental dangers of nanotechnology and applying the precautionary principle.

It comes to me as rather a shock to find that I am on the same side as Greenpeace and Prince Charles on an environmental issue. They suggest, as a recent article in Science reports, that we should be worrying about the environmental dangers of nanotechnology and applying the precautionary principle.

Eric Drexler introduced the term nanotechnology in the Eighties to describe the advanced capabilities of assembling molecules with atomic precision. He believes that this technology is akin to pre-Sputnik space flight and that it has enormous possibilities. But there are those who doubt that it will be possible to place one atom at a time in the right place, which some of this technology requires. Nevertheless the nanotechnology community is large, and there have been claims that it will be possible to make tiny devices that seek out and destroy cancer cells or can repair faulty heart valves. There is also the hope that the technology could be used to generate cheap electricity and purify water.

Nanotechnology is essentially a toolkit for manipulating molecules at the finest level. A key feature is that the properties of a material can change dramatically when they are present as just a few atoms. Gold, when in bulk, is rather inert, but it becomes highly reactive when present at the nanoscale. The reason for such changes is that, at such small sizes, most of the atoms are on the surface of the particle and this dominates its properties. Thus, when placed in small spaces, their properties can change. This capability to manipulate materials at the atomic level has been stated by a United States official from the Office of Technology to touch "...every human aspect in the world around us". Worldwide, the government funding of nano science has gone from $500m (£300m) in 1997 to $3.5bn in 2004. In the US alone there are some 800 nanotech companies.

There have been rumours that there could be dangerous unintended consequences, such as self-replicating robots that would devour the world. But, probably, the real problems are of the same class as those assumed to be associated with nuclear energy and genetically modified foods, that as some of the tiny units could damage cells and be an environmental danger.

Such an environmental danger is not that different from our earlier experience with asbestos, a fibre which was useful but which became a killer. Tiny carbon tubes can kill bacteria and cause damage in the lungs since they can agglomerate there. Units made of 60 carbon atoms, and known as buckyballs after their similarity in structure to the geodesic domes of Buckminster Fuller, are very strong. They also have the ability to act as sponges for electrons. They are fine for electronic devices, but they could make oxygen highly reactive and able to tear cells apart.

And this illustrates the problem with nanotechnology and environmental safety. Carbon materials widely available in the environment, such as graphite, plant pigments and soot, are regarded as safe. Regulators, who have to judge the safety of several thousand new chemicals each year, partly base their judgement of new materials on the basis of their chemical composition and what is already known about their safety.

But since nanomaterials change their properties when they get very small this may be unreliable. It is also far from clear as to how to test such nanoparticles for toxicity. Mice exposed to nano particles of iron suffered more damage to their lungs than that caused by inert silicon particles.

There is a real need for the public, including politicians, to be fully informed on these issues - openness by both industry and government is essential. It is recognised how important it is for this exciting field to avoid the sort of consumer backlash suffered by Monsanto in relation to genetically modified crops.

But how can the technology be controlled and the public be informed? This is a crucial and difficult issue that, in spite of past experience with GM foods, is still not solved. How to involve the public, and how to avoid groups with special interests dominating, is still very unclear.

Professor Wolpert is professor of biology as applied to medicine at University College London