Inhaling carbon nanotubes can suppress the immune system, according to scientists. The findings raise possible health concerns for those working in the manufacture of the materials.

Carbon nanotubes are rolled-up sheets of graphite thousands of times thinner than a human hair. Because they are immensely strong and are good electric conductors, they are poised for use in a wide range of fields from engineering to medicine. However, there are concerns over the similar shape of nanotubes and asbestos fibres, which are known to cause damage to the lungs in conditions such as mesothelioma.

Scientists are therefore trying to work out if there are any adverse effects that nanotubes might have on human health.

In the new study on mice, researchers found that inhaling nanotubes affected the function of T cells, a type of white blood cell that organises the immune system to fight infections.

“One of the take-home messages is you have to consider not just effects in the lung if it’s something you inhale but also effects outside of the lung,” said Jacob McDonald of the Lovelace Respiratory Research Institute in Albuquerque, New Mexico, who led the work. “These nanotubes appear to have an interesting, subtle yet significant response, systemically, on different organ systems that warrants careful consideration.”

Writing today in Nature Nanotechnology, the researchers said that although carbon nanotubes were unlikely to pose risks to the general public when incorporated into products, anyone working in their production and processing was more likely to be exposed to larger amounts over a longer period. “Immune dysfunction is a concern for those who work in this industry,” they wrote.

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