domestic use. On 21 December 1988, 340 g (12 ounces) of Semtex brought down a Boeing 747 over Lockerbie, Scotland killing all 259 passengers and crew aboard the aircraft and 11 bystanders on the ground. Also in response to international agreements, Semtex has a detection taggant added to produce a distinctive vapor signature to aid detection. First, ethylene glycol dinitrate was used, but was later switched to 2,3-dimethyl-2,3-dinitrobutane (DMDNB) or p-mononitrotoluene (1-methyl-4-nitrobenzene), which is used currently. According to the manufacturer, the taggant agent was voluntarily being added by 1991, years before the protocol became compulsory. Batches of Semtex made before 1990, however, are untagged, though it is not known whether there are still major stocks of such old batches of Semtex. According to the manufacturer, even this untagged Semtex can now be detected. The shelf life of Semtex was reduced from ten years before the 1990s to five years now. Explosia states that there is no compulsory tagging allowing reliable post-detonation detection of a certain plastic explosive (such as incorporating a unique metallic code into the mass of the explosive), so Semtex is not tagged in this way. On 25 May 1997, Bohumil Šole, a scientist who claimed to have been involved with inventing Semtex, committed suicide at a spa in Jeseník by blowing himself up with explosives. Šole, 63, was being treated there for psychological problems. It was unclear what explosives were used. Twenty other people were hurt in the explosion, while six were seriously injured. According to the manufacturer, Explosia, he was not a member of the team that developed the explosive in the 1960s. According to the producer's 2017 catalog, several variants of Semtex are offered: Semtex 1A, Semtex 1H, Semtex 10, Semtex 10-SE, Semtex S 30, Semtex C-4, Semtex PW 4, and Semtex 90. Notes References External links Website of the manufacturer with a brief history of Semtex Manufacturer's rebuttal of various alleged misapprehensions, including involvement of Bohumil Sole Explosives Products introduced in 1966 Czech inventions