Researchers recently reported new findings regarding potential occupational hazards associated with carbon nanotubes. These nano-scale cylinders have a variety of forms (single-walled and multi-walled, coated and uncoated, and so on.) They are widely available and used in a variety of manufacturing, medical and electronic applications. Previously, much attention was focused on whether when inhaled, nanotubes could produce damage similar to that caused by asbestos. A new study highlights an additional inhalation hazard: immune system suppression. This comes on the heels of a notice from EPA that a test rule for carbon nanotubes under the federal Toxic substances Control Act may be proposed in the indefinite future.