British scientists called on Thursday for more research into the safety of nanoparticles, materials so small that their dimensions can be measured in atoms, following evidence that they can lodge in the brain.
Nanotechnology, which could revolutionize the health-care, consumer and construction industries, has been touted by advocates as a potential multibillion-dollar endeavor.
Prophets of doom have painted a nightmare scenario of self-replicating robots turning the Earth into a "gray goo."
But Ken Donaldson, professor of respiratory toxicology at the University of Edinburgh, said the real risk lay in breathing in designer materials so small that they can slip through membranes inside the body.
Research on rats has shown that nanoparticles deposited in the nose can migrate to the brain and move from the lungs into the bloodstream, he told reporters.
So far, it is unclear whether this poses any health threat to humans. But Donaldson, who will address a scientific conference next week on the potential hazards of nanotech at the Daresbury Laboratory research center in northern England, urges caution.
"The big worry would be if a nanotechnology business designs nanoparticles that are fundamentally different from the ones we are already exposed to and seem to cope with reasonably well," he said.
Severe reactions possible
Modern humans breathe in considerable numbers of nanoparticles on a daily basis in traffic fumes and even from cooking. In some individuals they can trigger asthma or even cardiovascular problems, by setting off an inflammatory response from the body's immune system.
The new materials being developed through nanotechnology, which involves manipulating matter on a scale of a billionth of a meter, or about 80,000 times smaller than the thickness of a human hair, might trigger more severe reactions.
Mike Horton, professor of medicine at University College London and co-director of the new London Center for Nanotechnology, said scientists were treating the issue "very seriously" and had learned the lessons of public disquiet over genetic engineering.
He called for more experiments to establish how nanoparticles reached the brain and what the impact might be. But he dismissed the idea of a moratorium on nanotechnology.
"The impact would be exactly the same as the moratorium on genetic modification in Germany, which wiped out a whole area of biological science for 30 years. That would be a disaster," he said.