[nanoPost] NEWS ITEM: Concerns regarding long nanotubes tested on mice

Research led by Ken Donaldson of the University of Edinburgh’s Centre for Inflammation Research, UK, found that in mice, long, straight, multi-walled carbon nanotubes can cause the same kind of damage as that inflicted by asbestos fibres when they are injected into the lung's outer lining, called the mesothelium.

The lung clears out foreign bodies by wrapping them up in immune cells, which can then be flushed out of the body. But straight fibres longer than about 20 micrometres cannot be removed in this way because the cells are too small to engulf them. As a result, the cells become inflamed and form unwanted lumps, called granulomas, that can go on to cause mesothelioma, a cancer of the mesothelium.

The work doesn’t show that people exposed to nanotubes will get cancer, Donaldson and his colleagues stress. There have not yet been any studies on the effects of environmental exposure, or inhalation. “We certainly need more research on the toxicology of these materials,” says Donaldson.

The health effects of asbestos only came to light decades after workers were exposed to the fibres. This needn’t happen with nanotubes, says Anthony Seaton, a chest physician and co-author of the paper, published in Nature Nanotechnology 1. “We are well ahead of the game,” he says.

Size matters
"Up to now there has been considerable uncertainty about the hazards that carbon nanotubes might pose," says Richard Jones, a nanotechnologist at the University of Sheffield, UK. This research begins to clarify things, he says. "Now we know that it is the longest tubes that are most likely to cause problems."

Jones adds that nanotubes aren't normally handled in a state in which they might be inhaled, but nevertheless sees a need to protect the public, and the environment from any chance of exposure to nanotubes.

The research, published online in the British journal Nature Nanotechnology, showed that only so-called long carbon nanotubes, and not short ones, caused the pre-cancerous symptoms.