As incidents of domestic and international terrorism occur with greater frequency, U.S. first responders have another important problem to contend with – they are encountering certain unfamiliar types of explosives that are now being used by terrorists. The most common of these “new” explosives – which have been in the terrorist inventory since at least the early 1990s, but were not a principal “weapon of choice” until recently – are Triacetone Triperoxide (TATP) and Hexamethylene Triperoxide Diamine (HMTD). Both use peroxide as a key ingredient.

U.S. law-enforcement (LE) and public-safety response agencies have found both during what appears to have been investigations of non-emergency incidents. Typically, such incident investigations start out as an effort to identify an “unified” substance, but then escalate in intensity as additional information becomes available about the product. In some cases, the suspects seem to have been experimenting with chemical-explosive “recipes” found on the internet.

As the incident investigation continues, yet more information may be developed from simple clues such as emails found on computers and/or books or other documents carelessly left at the scene. The problem has grown so dramatically in such a short period of time that both TATP and HMTD have been found during recent investigations carried out in college dorms, home basements, and illicit laboratories.

The dimensions of the problem have resulted in a number of changes in the tactical objectives of U.S. hazardous materials response teams (HMRTs), and have led to revisions in their safety precautions as well. Team members have learned from previous incidents involving peroxide-based explosives, for example, that some very hazardous reactions can occur during the responses to such incidents. Because both TATP and HMTD are extremely sensitive materials, an action as simple as opening the container holding the explosive can set them off immediately.

The “Near Vicinity” May Be Too Close

It is not absolutely necessary, in fact, to actually touch the IED (improvised explosive device) container to cause a violent explosion – the production of shock, friction, or heat near the container could produce the same reaction. Here the lesson to be learned is that HMRT members and other emergency first responders should not handle the IED or pre-cursor chemicals in any way, or walk through chemical residue, until a site-safety plan has been implemented and the IED not only has been fully evaluated but HMRT members and other emergency first responders should not handle the IED or pre-cursor chemicals in any way until a site-safety plan has been implemented also rendered safe. With that precaution in mind, it also should be noted that any response to incidents involving peroxide-based explosives must include participation by law-enforcement and bomb-squad personnel as well as a chemist possessing considerable expertise in the handling of explosives.

Another important prerequisite to be noted, and included in contingency plans, is that, because so many agencies and political jurisdictions are likely to be involved, a Unified Command must be established as soon as possible. Doing so will ensure the investigation will be better organized and that all important priorities are given proper consideration.

When a response has been requested and the HMRT arrives on the scene, the first priorities to be considered must be the saving of lives and the evacuation of the incident area. The evacuation should be carried out in accordance with guidelines set forth in the Emergency Response Guidebook (ERG) – tempered and/or modified by recommendations made by the bomb squad as well as such factors as the topography in the area surrounding the incident and the size of the population most likely to be affected.

The next important task in the HMRT response usually will be to conduct a hazard-risk assessment. This will start in most if not all situations by examination of and research on the product(s) involved. As noted earlier, the two most widely used peroxide family explosives are TATP and HMTD, which use different precursors. TATP is prepared by combining precisely measured amounts of hydrogen peroxide, acetone, and a strong acid. The most common strong acids now used are sulfuric acid, hydrochloric acid, and nitric acid. HMTD is similarly prepared – from such commonly used chemicals as hydrogen peroxide, hexamine, and citric acid.

Of course, in order to know exactly what to research, and in what depth, intelligence found or developed by the LE agencies participating should be provided to the HMRT, the members of which must keep in mind that, when referencing these materials, they must give serious consideration to the potential reactions that may occur. As noted previously, peroxide-based explosives are highly reactive and potentially explosive. If any of these substances are suspected to be present, the bomb squad should take the lead role in the investigation.

The Essential Prerequisites: Plans, Precautions, and Professional Expertise

Once the product(s) have been identified and the initial precautionary actions taken (evacuation, research, and isolation), the HMRT should assist the LE/Bomb Squad with continued reference and by providing its own technical expertise – including, to cite one important example, the development of an Incident Action Plan (IAP). The latter not only should set forth site-safety considerations and tactical objectives but also incorporate product information, the guidelines needed for contacting and working with chemists and other technical professionals, and suggestions on ways to assist the LE/Bomb Squad with presumptive on-scene testing and sampling – as and when needed.

To summarize: The mitigation of incidents involving peroxide-based explosives is a major and increasingly difficult problem for the nation’s hazardous materials response teams. Such incidents must not be handled alone, but in close cooperation with other agencies – which means there is an urgent need for pre-incident interactions and planning with LE agencies. Not just team leaders, but all HMRT members should remember that there are many subject-matter experts who are willing to assist at any time – this is particularly true, of course, if close working relationships have previously been established with those experts.

They are relatively common today in Iraq, Israel, and elsewhere in the Mideast, but still rare in the United States – for the present. But when an IED attack or any similar high-risk/low-frequency incident does occur, those responding must ask themselves if they are as fully prepared as they should and must be to work with the many other agencies that undoubtedly will be involved.

Glen Rudner
Glen Rudner

Glen Rudner retired in 2022 as a manager of environmental operations for the Norfolk Southern (NS) Railway with environmental compliance and operations responsibilities in Tennessee, Alabama, Mississippi, and Louisiana. Previously, he was the hazardous materials compliance officer for NS’s Alabama Division (covering Alabama, Mississippi, Louisiana, and southwestern Tennessee). Prior to NS, he served as one of the general managers at the Security and Emergency Response Training Center in Pueblo, Colorado. He worked as a private consultant and retired as a hazardous materials response officer for the Virginia Department of Emergency Management. He has nearly 42 years of experience in public safety. He spent 12 years as a career firefighter/hazardous materials specialist for the City of Alexandria Fire Department, as well as a former volunteer firefighter, emergency medical technician, and officer. As a subcontractor, he served as a consultant and assisted in developing training programs for local, state, and federal agencies. He serves as secretary for the National Fire Protection Association Technical Committee on Hazardous Materials Response. He is a member of the International Association of Fire Chiefs Hazardous Materials Committee, a member of the American Society of Testing and Materials, and a former co-chairman of the Ethanol Emergency Response Coalition. He served as a member of the FEMA NAC RESPONSE Subcommittee.

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