Definition: Pentaerythritol tetranitrate, more commonly known as PETN, is a highly potent explosive that is a major ingredient in weapons from the Semtex plastic explosive to TNT blends and nuclear warheads. Ever since shoe bomber Richard Reid attempted to blow up an airliner in December 2001 by detonating PETN in his shoe, airlines have been on higher alert for nitrate-based explosive chemicals that can be tested for on suspicious passengers.


However, on Christmas Day 2009, Umar Farouk Abdulmutallab, a 23-year-old Nigerian, smuggled a PETN explosive onto an Amsterdam-to-Detroit flight smuggled in his underwear. On Oct. 29, 2010, PETN explosive devices constructed out of printer toner cartridges were found on two flights out of Yemen and bound for the United States. If detonated remotely while the planes were in mid-air, the planes could have easily been taken down.

PETN is not a new choice of terrorists. In fact, it was widely used in the 1970s and 1980s terrorist attacks on airplanes. Introduced after World War I, PETN is less stable than other common explosives but retains its shelf life longer. Just over 100 grams of PETN can destroy a car, and Abdulmutallab's 80 grams -- combined with his window seat -- was likely intended to blow a hole in the side of the plane. The white powder needs a detonator or chemical reaction to explode, but can't be sparked with a lit match. Legally, it is used by the military and in mining operations, but whereas it can be difficult to buy off the shelf in some countries such as the United States the chemicals to mix it up can usually be acquired.

Like its explosive cousin nitroglycerin, PETN is also used as a heart medication.

Alternate Spellings: Pentaerythritol tetranitrate