threats to its safe operation. The actions outlined in this chapter are those most appropriate at this time. The framework and methodology to address vulnerabilities presented in the earlier chapters offer an ongoing means by which new actions can be identified and taken over time.


Toxic, flammable, and explosive materials present the greatest risk of catastrophic incident. In the absence of specific threat information, it will be most appropriate to invest in mitigation and preparedness for general classes of vulnerabilities.

Absent any specific intelligence information, among chemicals having toxic, explosive, or flammable properties, analysis indicated little benefit in differentiating one specific chemical from another for the purposes of determining research and development needs for securing the chemical infrastructure. Using the example of highly toxic chemicals, consequences of a release depend on so many event-specific variables that it is possible that a release of one toxic material could actually lead to more casualties than a similar-sized release of another more toxic material under different circumstances. Furthermore, measures can be taken to mitigate the potential for and consequences of any large volume toxic release. During the analysis of the chemical categories listed in Chapter 3, it was determined that by focusing on general classes of vulnerabilities (i.e., chemical properties) within chemical categories, instead of on specific chemicals, more appropriate guidance for science and technology investments could be given.

By analogy with past accidents involving the chemical industry, it is possible that a single terrorist incident involving the chemical infrastructure could result in catastrophic loss of life or injuries.

This report adopts the definition of catastrophic incident outlined in the Department of Homeland Security’s National Response Plan—one that “results in large numbers of casualties and/or displaced persons, possibly in the tens of thousands.” In part due to lack of access to the results of off-site consequence models, this report discusses scenarios based on historical chemical incidents that serve as existence proofs (but not necessarily upper bounds) for the possible consequences. Using this approach it is easy to determine that a single chemical event could cause catastrophic casualties. For example, approximately 4,000 people died in the immediate aftermath

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