---- Their findings raise possible health concerns for those working in the manufacture of the materials. Carbon nanotubes are rolledup sheets of graphite thousands of times thinner than a human hair. Because they are immensely strong and are good electricity conductors, they are poised for use in a wide range of fields, from engineering to medicine. However, their similarity in shape to asbestos fibres, which are known to damage the lungs, is giving rise to fears of their adverse effects on human health.