Taggant Types and Previous Uses

Two different kinds of taggants are commonly discussed. Detection taggants are materials added to explosives that can be sensed (pre-blast) by an associated detection instrument. Identification taggants are additives designed to survive an explosive blast, to be recoverable at the bomb scene, and to provide pertinent information, such as last legal purchaser, to aid law enforcement personnel in identifying the perpetrator.

Detection Taggants

A number of technologies exist to detect untagged explosive materials, including dual-energy x-ray, x-ray computed tomography, thermal neutron activation, vapor/particle detection, and use of canines.9 Detection taggant schemes may improve the specificity and efficiency of these detection technologies or make new methods possible.

Taggant options include addition of volatile chemicals, radioisotopes, or electromagnetic taggants. In countries ratifying the International Civil Aviation Organization's “Convention on the Marking of Plastic Explosives for the Purpose of Detection,” plastic explosives are currently being tagged, or “marked,” with one of four volatile chemicals. 10

Identification Taggants

Identification taggants can encode information in a variety of ways and can be added at various points in the production and distribution process. Microscopic plastic particles are the most well known form of identification taggant. The color sequence of the colored layers that compose the particles is used for identification. Another approach uses polymeric microbeads of various sizes and colors. Other approaches use rare-earth elements in a synthetic matrix blended with fluorescent pigments and iron powder, isotopic methods, and immunoassay techniques.

9  

National Research Council. 1993. Detection of Explosives for Commercial Aviation Security. Washington, D.C.: National Academy Press.

10  

The United States has chosen to use 2,3-dimethyl-2,3-dinitrobutane (DMNB).



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--> Taggant Types and Previous Uses Two different kinds of taggants are commonly discussed. Detection taggants are materials added to explosives that can be sensed (pre-blast) by an associated detection instrument. Identification taggants are additives designed to survive an explosive blast, to be recoverable at the bomb scene, and to provide pertinent information, such as last legal purchaser, to aid law enforcement personnel in identifying the perpetrator. Detection Taggants A number of technologies exist to detect untagged explosive materials, including dual-energy x-ray, x-ray computed tomography, thermal neutron activation, vapor/particle detection, and use of canines.9 Detection taggant schemes may improve the specificity and efficiency of these detection technologies or make new methods possible. Taggant options include addition of volatile chemicals, radioisotopes, or electromagnetic taggants. In countries ratifying the International Civil Aviation Organization's “Convention on the Marking of Plastic Explosives for the Purpose of Detection,” plastic explosives are currently being tagged, or “marked,” with one of four volatile chemicals. 10 Identification Taggants Identification taggants can encode information in a variety of ways and can be added at various points in the production and distribution process. Microscopic plastic particles are the most well known form of identification taggant. The color sequence of the colored layers that compose the particles is used for identification. Another approach uses polymeric microbeads of various sizes and colors. Other approaches use rare-earth elements in a synthetic matrix blended with fluorescent pigments and iron powder, isotopic methods, and immunoassay techniques. 9   National Research Council. 1993. Detection of Explosives for Commercial Aviation Security. Washington, D.C.: National Academy Press. 10   The United States has chosen to use 2,3-dimethyl-2,3-dinitrobutane (DMNB).

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--> History of Taggant Research and Use During 1977 to 1980, a pilot test was conducted for the ATF by the Aerospace Corporation. This feasibility demonstration program evaluated the addition of identification taggants manufactured by the 3M Corporation to 6.4 million pounds of packaged, cap-sensitive explosives manufactured by four companies (Atlas, DuPont, Hercules, and Independent). Taggant addition during manufacture, recordkeeping, and taggant recovery and analysis procedures were evaluated.11 In 1980, the Swiss government began requiring that all manufactured explosives contain identification taggants to aid in criminal investigations. Some success in resolving bombing cases has been reported,12 although the usefulness of the Swiss experience is controversial, in part because of differences between the U.S. and Swiss explosives industries. 13 Previous Evaluation of Taggants In 1980, the Office of Technology Assessment (OTA) examined the use of identification taggants in commercial explosives.14 While it concluded that taggants could be useful for law enforcement, OTA noted the need for further development and safety/compatibility evaluation testing. Committee's Approach to Evaluation of Taggants Taggant Taxonomy In an effort to categorize the many existing and proposed taggant concepts, the committee developed a draft taggant concepts taxonomy as shown in Box 1. Such a taxonomy should prove useful for stimulating thinking about new taggant approaches and for ensuring a complete consideration of taggant concepts. The reader is cautioned that this taxonomy is only a draft tool being used to stimulate committee thinking at this point. 11   Aerospace Corporation. 1980. Identification Tagging Pilot Test for Packaged, Cap-Sensitive Explosives: Final Report. ATR-80(5860-03)-1ND. Washington, D.C.: Aerospace Corporation. 12   Scharer, J. 1995. “Switzerland's Explosives Identification Program,” in Proceedings of the International Explosives Symposium. Fairfax, Va.: Government Printing Office. 13   Ronay, C. 1997. Testimony to the Committee on Marking, Rendering Inert, and Licensing of Explosive Materials. 14   Office of Technology Assessment. 1980. Taggants in Explosives. Washington, D.C.: Government Printing Office.