PETN harmless without an external trigger, say experts

The PETN, found inside UP assembly, was last used in a bomb that went off outside the Delhi high court in 2011.

Forensic experts say the PETN or Pentaerythritol Trinitrate though an extremely powerful explosive is harmless in the form it was found in the state assembly. The explosive, like the RDX, needs an external trigger or detonator—like mercury fulminate or a timer device to go off.

Developed during the World War II in Germany, the PETN’s use in India has been negligible in terror strikes. But it has remained an explosive of choice for the terror groups such as Lashkar-e-Taiba, Indian Mujahideen, Al-Qaeda, which used it more frequently at different places in the world. Forensic experts said no standard bomb could be made using the PETN alone, but it is a frequently used ingredient of high quality bombs, explosives and detonators. Like in hand grenades, the PETN is used with TNT and pellets. It has never been a common component in an improvised explosive device (IED) in India, said the experts.

The terror groups have been using the PETN with ammonium nitrate to increase the intensity of the blast. Security agencies had traced the use of PETN with ammonium nitrate in Varanasi’s Dashashwamedh Ghat blast.

A two-year-old girl was killed and 38 others were injured in the blast. The bomb was hidden in a milk container at Sheetla Ghat. In 2010, two men who got injured in a blast in Sitapur, had PETN with them. Militants in Jammu and Kashmir too have used it in many of their attacks between 2003 and 2005. The PETN, the experts said, is a stable explosive and usually has been used for military exercises and operations. “It is not easily available India and this is why the examples of its use are few,” said an expert. “Its discovery inside the state assembly calls for a detailed investigation. 100 grams of PETN is enough to blow a midsize car, and 150 grams is a good quantity. We are really surprised,” said an expert.