Long Carbon Nanotubes: Just as Dangerous as Asbestos

Exposure to long carbon nanotubes can cause mesothelioma — the same form of incurable lung cancer caused by exposure to long-fiber asbestos, according to a new long-term study on mice.

This research is not the first to raise the alarm on long carbon nanotubes, which measure in the range of 15–20 µm and are used in electronics and objects that are designed to be durable, such as helmets and hockey sticks. A line of previous studies found that long carbon nanotubes can aerosolize and enter the lungs and then work their way into the membranous pleural space that surrounds the lungs, resulting in inflammation and a form of scarring called fibrosis.

The new study makes the final step in tracing the connection between carbon nanotubes and cancer. Researchers injected both long and short (less than 15 µm) carbon nanotubes into the pleural space of mice at various doses and exposure durations, from 5 µg for up to 12 weeks to 2.5 µg for one year, as well as doses of 1 µg, 0.5 µg, and 0.2 µg for up to 20 months. In parallel, they tested a comparison group of animals with asbestos fibers, using the same doses and exposure times. They then tracked the animals’ pleural health over...