The study in mice showed that long carbon nanotubes could cause inflammation of the membrane which surrounds organs (the mesothelium), and this is similar to what is seen with certain types of asbestos. With blue and brown asbestos, inflammation of the mesothelium of the lungs can lead to the development of a rare lung cancer (mesothelioma); however, the mice in this study were not studied for long enough to see if they developed cancer. Carbon nanotubes that are embedded in other materials, like those in tennis rackets, car body panels and bike frames, are thought to be relatively harmless, but the researchers suggest that further studies are needed to confirm this.