A new study by researchers at the University of Edinburgh into the health risks posed by nanofibers, used to strengthen objects from tennis rackets to airplane wings, has pinpointed the lengths at which these fibers are harmful to the lungs.

Nanofibers, which can be made from a range of materials including carbon, are about 1,000 times smaller than the width of a human hair and can reach the lung cavity when inhaled.

This may lead to mesothelioma, which is known to be caused by breathing in asbestos fibers, which are similar to nanofibers.

"Concern has been expressed that new kinds of nanofibers being made by nanotechnology industries might pose a risk because they have a similar shape to asbestos," said Ken Donaldson, professor of respiratory toxicology.

The study found that lung cells were not affected by short fibers that were less than five-thousandths of a millimeter long. However, longer fibers can reach the lung cavity, where they become stuck and cause disease.

"We knew that long fibers, compared with shorter fibers, could cause tumors but until now we did not know the cut-off length at which this happened. Knowing the length beyond which the tiny fibers can cause disease is important in ensuring that safe fibers are made in the future as well as helping to understand the current risk from asbestos and other fibers," said Donaldson.

The researchers, whose study is published in the journal Toxicology Sciences, created fibers of different lengths using minute silver casts.

They then looked at the effect of these fibers on mouse cells to reach their findings.

Source: The University of Edinburgh