Next March, Mark Welland's laboratory at the University of Cambridge, UK, will gain an unusual member of staff. Welland's team works on nanometre-dimension wires and tubes that could form the future of electronics, but the new recruit won't be an engineer or a physicist — he or she will be a social scientist.

The appointment — a two-year position that will include running regular meetings with everyone from industry representatives to green activists — acknowledges public fears about the possible effects of nanotechnology on human health and the environment. Although Welland may not subscribe to long-standing scare stories about a 'grey goo' of nanometre-sized robots taking over the planet, he realizes that scientists need to address this and other concerns head on.

Welland's proactive attitude stems in large part from a desire to avoid a rerun of Europe's experience with genetically modified (GM) crops. Over the past decade, vociferous campaigning by environmental groups, combined with an inability of both biotech firms and scientists to understand and respond to public concerns, has created a hostile climate of public opinion. Although the discussion has — in Britain, at least — matured this year into a more detailed scientific consideration of the environmental risks and benefits of individual GM crops, these negative perceptions are now deeply ingrained.

Given this background, Welland and other nanotechnologists are alarmed by signs that their work will be the next target for environmental campaigners. Media attention began to build after the publication in January of The Big Down, a report by the ETC group, a small environmental organization based in Winnipeg, Canada. In its previous guise as the Rural Advancement Foundation International, ETC had a history of influential campaigning against GM agriculture.

The ETC report argued that synthetic nanoparticles could be toxic. The Big Down and other ETC publications went on to envisage a technology out of control, potentially able to create new weapons of mass destruction or novel life forms.

ETC doesn't subscribe to the old 'grey goo' scenario. But it has cleverly married fears about GM with its campaign against nanotech by arguing that the public should be especially concerned about 'nanobiotechnology'. This future industry, ETC claims, could create a 'green goo' of novel organisms and products that will behave in unpredictable and uncontrollable ways

Ask ETC officials to define what, exactly, they mean by nanobiotechnology and they become frustratingly difficult to pin down — when pushed, they mention experiments in which researchers have altered the bases of DNA to create a novel, larger molecule that can still store genetic information (H. Liu et al. Science 302, 868–871; 2003). Such fundamental projects are easy to portray as playing God with the stuff of life. But in reality, they have little to do with creating an industry based on new life forms. And even if such work did eventually find applications, most scientists are confident that they could be regulated effectively.

Despite the currently nebulous nature of the 'green goo' scare, the idea may still have resonance with the public. Nanotechnologists would be unwise to dismiss ETC's campaign — particularly as many toxicologists agree that too little is known about the effect on human health of breathing in nanoparticles.

In Britain, the scientific establishment has been relatively quick to respond. In June, the Royal Society and the Royal Academy of Engineering launched a review of the social and ethical implications of nanotechnology, which should report next spring. In the United States, a bill passed in November recommending some $4 billion in spending on nanotech over the next four years also calls for a federal advisory panel to look into similar issues. But federal officials remain concerned that US nanotechnologists are poorly equipped to engage in a debate on the risks and benefits posed by their work. “Because of the GM debate, the United Kingdom is ahead of us in developing mechanisms for dialogue,” says Julia Moore, an expert on nanotechnology policy at the National Science Foundation in Arlington, Virginia.

It's hard to say whether efforts to address the concerns raised by the ETC group will help to avoid the polarization of views that has afflicted the GM debate in Europe. But if scientists don't get involved, debate about nanotechnology will simply be conducted without them. “I've learnt from the GM debate,” says Welland. “It's easy to condemn a technology, but hard to fight back.”