Taggant

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A taggant can mean a radio frequency microchip used in automated identification and data capture (see RFID). In such cases, electronic devices use radio waves to track and identify items, such as pharmaceutical products, by assigning individual serial numbers to the containers holding each product. This technology may prevent the diversion or counterfeiting of drugs by allowing wholesalers and pharmacists to determine the identity and dosage of individual products.

A taggant is also a chemical or physical marker added to materials to allow various forms of testing. It is believed that they generally consist of microscopic particles built up in many layers, which are made of different materials. It is a somewhat secretive process, but products that may be affected include ink, paper, perfume, and medication. Taggants allow testing marked items for qualities such as lot number and concentration (to test for dilution, for example). In particular, taggants are known to be widely used in plastic, sheet and flexible explosives.

1 Explosive taggants

[edit] Explosive taggants

There are two types of taggant which can be added, one to help detect the presence of a bomb in, for example, airport screening of luggage; and the other to assist the police in finding the culprits after the detonation of such a bomb.

[edit] Detection taggants

These are volatile chemicals which will slowly evaporate from the explosive and can be detected in the atmosphere by either detection dogs or specialised machines. They are intended to allow the presence of a bomb containing the explosive to be detected. Although various technologies exist to detect untagged explosives, detection taggants help to increase their reliability and their inclusion in explosives is mandatory in many countries, for example in the United States pursuant to the Antiterrorism Act of 1996.

There is a choice between four possible detection taggant chemicals which must be added to plastic explosives under the 1998 International Civil Aviation Organization's Convention on the Marking of Explosives for the Purpose of Identification. In the United States the marker is always 2,3-dimethyl-2,3-dinitrobutane, usually called DMDNB or DMNB. Dogs are very sensitive to it and can detect as little as 0.5 parts per billion in the air, as can specialised ion mobility spectrometers. Other taggants in use are ethylene glycol dinitrate, known as EGDN and used to mark Semtex, ortho-mononitrotoluene (o-MNT), and para-mononitrotoluene (p-MNT).

[edit] Identification (or post detonation) taggants

These are added to the explosive so that the manufacturer and batch number can be determined if it is used illegally. The taggant must survive the explosion and not be contaminated by the environment afterwards. Several different technologies have been tried, but probably the most common are microscopic polymer particles. A popular type is tiny chips called Microtaggantwhich are built up of different coloured plastic layers.

Whilst detection taggants are universally used, this is not the case with identification taggants; in particular there are arguments that there may be minimal benefit in practice to law enforcement agencies compared to the cost to industry of the taggant. One reason cited is that most terrorist attacks use homemade explosives, for instance in the 1993 World Trade Center bombing, and in the Oklahoma City and Omagh bombings. Contamination of the site is also cited as a problem, since countless different taggants might be present at a crime scene from, for example, explosives used to obtain the building materials.

Switzerland passed a law in 1980 requiring taggants in explosives manufactured there, and that the code must be changed every six months. So far it is the only country which requires identification taggants. Imported explosives must be tagged only if competing products are also manufactured in Switzerland.