<unk>  is a material, today usually produced by the incomplete combustion of petroleum products.<unk>  is a form of amorphous<unk>  that has an extremely high surface area to volume ratio, and as such it is one of the first nanomaterials to find common use. It is similar to soot but with a much higher surface area to volume ratio.<unk>  is often used as a pigment and reinforcement in rubber and plastic products.
The current International Agency for Research on Cancer (IARC) evaluation is that,<unk>  is possibly carcinogenic to humans  (Group 2B)". Short-term exposure to high concentrations of the<unk>  dust may produce discomfort to the upper respiratory tract, through mechanical irritation.
Carbon black
Silane
Opium
Tantalum carbide
Psyllium
Coal tar
Carbon suboxide
Cadmium oxide