SciTech Tuesday: Zyklon B

On June 20, 1922 a German company filed for a patent on a new formulation of a pesticide/insecticide, which it called Zyklon B (zyklon is German for cyclone).

After its first use as a pesticide in California citrus plantations in the late 19^th century, hydrogen cyanide came to be used in all sorts of circumstances as a fumigant. In the US it was used to fumigate train cars, the clothes of immigrants, and in Germany it was used to kill lice and rats. In World War I, a form of hydrogen cyanide, known as Zyklon, used as a chemical weapon by the German military.

After World War I, this form of hydrogen cyanide was banned. The scientists at a German chemical company came up with a new formulation, getting the cyanide from the waste products of sugar-beet production, and packaged the hydrogen cyanide with diatomaceous earth in a canister, along with a chemical irritant to warn of the product’s toxicity. They called it Zyklon B to differentiate it from the earlier, banned, product. From 1922 to the start of the war, most of the sales came from outside of Germany.

Hydrogen cyanide is a very potent toxin. It binds with the iron compound in an enzyme called cytochrome c oxidase in cells. This enzyme is necessary in production of adenosine triphosphate (ATP), which is required by cells in energy transfer. Without ATP cells cannot survive, and without cytochrome c oxidase cells can’t make ATP. Hydrogen cyanide reacts with cytochrome c oxidase and keeps it from making ATP. In aerial forms, such as Zyklon B, it enters the body quickly. In a human of about 150 lbs only 70 milligrams of Zyklon B can be fatal in 2 minutes.

In 1941 the German SS was experimenting with methods of efficiently killing prisoners. A captain tested Zyklon B on a group of Russian POWs at Auschwitz in a building basement. By early 1942 Zyklon B became the SS’s preferred method for killing prisoners and was used to kill at least 1 million prisoners. Many of these were at Auschwitz, where the practice originated.

Two of the scientists who developed managed Zyklon B production were tried and executed in British military court for knowingly delivering the chemical to kill prisoners.  Different forms of hydrogen cyanide are still used today as pesticides.

Posted by Rob Wallace, STEM Education Coordinator at The National WWII Museum.

all images from Wikimedia Commons