Material 'looks like asbestos, behaves like asbestos'

Carbon nanotubes are tiny molecules that exhibit extraordinary strength and unique electrical properties. Their current and potential uses range from lightweight sports equipment to tear-resistant clothing, but tests have suggested their widespread use could lead to mesothelioma, a cancer of the lining of the lungs.

Scientists from Britain and the United States, led by by Professor Ken Donaldson of the University of Edinburgh, carried out tests on mice using the material.

"The results were clear," said Prof Donaldson. "Long, thin carbon nanotubes showed the same effects as long, thin asbestos fibers."

Writing in the journal Nature Nanotechnology, the researchers said the findings were of "considerable importance", not least because industry was investing heavily in carbon nanotubes for a wide range of products "under the assumption that they are no more hazardous than graphite."

"Our results suggest the need for further research and great caution before introducing such products into the market if long-term harm is to be avoided," they said.

'Appropriate steps'

Forecasters have predicted that sales of all nanotubes could reach £2 billion annually within the next four to seven years.

Dr Anthony Seaton, of the University of Aberdeen, and a co-author of the paper, said: "The toll of asbestos-related cancer, first noticed in the 1950s and 1960s, is likely to continue for several more decades even though usage reduced rapidly some 25 years ago.

"While there are reasons to suppose that nanotubes can be used safely, this will depend on appropriate steps being taken to prevent them from being inhaled in the places they are manufactured, used and ultimately disposed of."

He added: "Such steps should be based on research into exposure and risk prevention, leading to regulation of their use. Following this study, the results of which were foreseen by the Royal Society in the UK in 2004, we can no longer delay investing in such research."

Good news!

Asbestos fibres are harmful because they are thin enough to penetrate deep into the lungs, but sufficiently long to confound the lungs' built-in clearance mechanisms for getting rid of particles.

Prof Donaldson said there was a silver lining to the new research. He explained: "Short or curly carbon nanotubes did not behave like asbestos, and by knowing the possible dangers of long, thin carbon nanotubes, we can work to control them.

"It's a good news story, not a bad one. It shows that carbon nanotubes and their products could be made to be safe."

Andrew Maynard, chief science advisor to the Project on Emerging Nanotechnologies, commented: "This is a wakeup call for nanotechnology in general and carbon nanotubes in particular. As a society, we cannot afford not to exploit this incredible material, but neither can we afford to get it wrong - as we did with asbestos."