Hydrogen cyanide
Carrier absorbed hydrogen cyanide can find use as a pesticide. Perhaps the most infamous of these is (German: "Cyclone B", with the B standing for – prussic acid; also, to distinguish it from an earlier product later known as Zyklon A), it was used in Nazi German extermination camps during World War II to kill "en masse" as part of their Final Solution genocide program. Hydrogen cyanide was also used in the camps for delousing clothing in attempts to eradicate diseases carried by lice and other parasites. One of the original Czech producers continued making Zyklon B under the trademark "Uragan D2" until recently.