The Unique Terrorism Threats Posed by Liquid Explosives

Home-brew explosives create new risks, but detection systems working to automatically ID these materials


Details are emerging on the alleged plot to detonate explosives aboard UK to U.S.-bound airliners. Early reports have indicated that the terrorists may have plotted to hide the liquid explosives inside a sports drink container not unlike what a Gatorade may have come in.

According to Henri Nolin, CPP, an assistant chairman for ASIS International's Transportation Security Council, there has been a lot of speculation among the security community that the substance may have been a liquid form of TATP or TCAP. The two explosives can be engineered in both liquid and powder forms, and according to Dennis Koehler of explosives detection company Isonics, both TATP and TCAP are commonly known as "bathtub explosives" because they can be made at home using fairly common ingredients. They also can be detonated with or without a classic detonator; the chemicals are volatile enough that explosion can be created simply smashing a container of such materials to the floor.

And while speculation abounds, no official information has been released yet on what the exact explosive was to be. But by banning a variety of liquids, aerosols and gels from airplanes, says Nolin, who operates a K-9 detection company out of Florida known as Sun State Specialty K-9s, they've been able to eliminate a variety of liquid or liquid-like explosives. The inclusion of toothpaste tubes, while seemingly innocuous, is included because many liquid explosives, such as nitromethane, can be converted into a gel or slurry format from a liquid state.

Most reports into the July 7, 2005, London train bombings indicated that the explosives in question were either TATP or TCAP, and though no one can yet known what the exact explosives in question for the airplanes plot were, these explosive chemicals present a likely possibility and are fairly well-known in the world of terrorism. These explosives, says Isonics' Koehler, can be created by anyone with a fairly basic knowledge of chemistry and basic ingredients and they create, "very, very volatile" substances. To put the destructive nature of these substances in perspective, says Nolin, you have to understand that just 24 ounces of TATP could blow a hole in the hull of a heavy ship, let alone the skin of an airliner.

Besides their explosive power, there's another risk to explosives like TATP and TCAP (both are also known as acetone peroxide). The danger of this type of explosive is that the chemical's base ingredients are acetone (paint thinners and fingernail polish removers), hydrogen peroxide (a sterilizing chemical for first aid) and sulfuric acid (common in auto batteries). The problem, says Koehler, is that all can be obtained readily. And even more challenging to the intelligence and security community is that the procedures of making TATP and TCAP are all readily available online.

Fortunately, many of today's explosive detection systems can locate these chemicals even in small amounts or if the substance is "hidden" inside a container like a sports drink bottle.

According to Tom Brigham, who handles media relations for GE Security, GE's current technology offering uses trace detection. That means, he says, that if just a slight amount of chemical residue is left on the hands, or on clothing or on the explosive container itself, the machines will be able to detect that presence. He added that the GE systems being used at airports are designed to be immediately upgraded such that if the government needs to add a new threat substance, it can be done without delay. Koehler, whose company Isonics recently unveiled ultra-portable detection units that could be deployed into the hands of police and first responders, said the Isonics detection systems can identify a variety of chemicals and explosives, including TATP and TCAP.

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