Wednesday, December 23, 2009

Commercial Peroxides

In a blog last month about academic lab alternative security programs I mentioned the IED precursor chemicals that had been bought by the suspected terrorist in Denver earlier this year. I said then that I would probably address the question of why such materials were not chemicals of interest under CFATS. Well this slow season during the holidays seem like a good time to address such issues. Pressure Events The first thing that people have to realize is that there are a wide variety of readily available commercial products that can be used to make an ‘explosion’. Most people consider it an explosion when a chemical reaction produces a gas in a sealed jar and the resulting gas pressure builds up to the point where the jar ‘explodes’ sending pieces of glass flying. While military and security people don’t really consider these ‘pressure events’ to be explosions, they are used to damage property and hurt people. DHS has not attempted to regulate the chemicals that go into these types of ‘explosives’ for two basic reasons. First the potential damage from these devices is so limited that they really are not useable as terrorist weapons. The second reason is that the number of potential chemicals used in such devices is so large that there is no practical way to regulate them. For a really ludicrous example look at the ‘explosion’ resulting from the combination of Mentos® candy and Coke®. Peroxide Explosives Now the alert reader will be quick to point out that the peroxide explosives that could be made with hair care products involved in the Denver case are explosives in the military sense. That is that the chemical reaction is in reality a really fast burning fire that produces a great deal of pressure in a very short period of time. Properly enclosed in a metallic casing these explosions can produce significant damage over a large area. Various peroxides are of particular significance when looking at a large number of improvised explosives. Chemically speaking they contain readily available oxygen that promote a wide variety of chemical reactions. From a security point of view they speed up the rate of combustion for many materials so that the other chemical now explosively burns. These peroxides are available in a wide variety of commercial products, including cleaning products, hair colorings, and hygiene products. The concentration in these products is so low that they would have no appreciable affect on the rate of burning. Unfortunately, a chemist or chemical technician can figure out ways to extract the peroxides from these products to produce a concentrated enough to peroxides to be used in improvised explosives. There is a problem with this however. You really have to know what you are doing when completing the extraction/concentration process. Nearly all of the techniques require the application of heat and that is always a dangerous thing to do to peroxides. They are unstable molecules that readily give up their excess oxygen (which is why they are used in explosives in the first place). If you don’t follow procedures exactly the premature of release of oxygen will result in small explosions in your equipment. Some will be true explosions while others will be pressure events. Dirty equipment or poor temperature control make this result even more likely. While the explosions will be small on a relative scale, they will certainly be large enough to destroy the processing equipment while killing or injuring the operators. Peroxide COI DHS took all of this into account when they set their minimum concentrations for peroxides when they established their list of DHS Chemicals of Interest (Appendix A to 6 CFR 27). Generally speaking the concentration listed in the appendix are those that are readily useable as improvised explosive components. This is why peroxide containing hair products are not covered materials under CFATS. This does not mean that DHS and the FBI are ignoring the potential use of lower concentrations of peroxide in commercial products. As I noted in an earlier blog DHS has established a voluntary program urging retailers and distributors of a variety of peroxide containing materials to watch out for odd purchases of these materials. The lower the concentration the larger the amount of material needed to extract sufficient quantities of peroxide to make terrorist weapons. This means that typical, legitimate users of these materials do not need to be hassled to prevent terrorist use of these chemicals.

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