The United States Department of Homeland Security (DHS) published a Final Rule on November 20, 2007, that revised the list of chemicals of interest (COI) that appears in Appendix A to the Chemical Facility Anti-Terrorism Standards (CFATS) (6 C.F.R. §27).1 In accordance with the Final Rule, if a facility possesses any of the approximately 300 COI identified by DHS and those COI are above established screening threshold quantities (STQ), the facility has until January 19, 2008 to prepare and submit a “Top-Screen” consequence assessment survey to DHS. The assessment is designed to permit DHS to make preliminary determinations about whether facilities – including those that are not traditionally considered to be part of the chemical sector – possess potentially dangerous chemicals in quantities that suggest DHS should further inquire as to whether the facility presents a high level of security risk. If a high risk is determined, the facility may be subject to additional regulation under CFATS.2

As part of the Final Rule, DHS: (i) adjusted the STQ for various COI; (ii) defined specific security issues implicated by each COI (and in some cases established different STQs for the same COI based upon the security issues presented); and (iii) instructs facilities on how to calculate the quantities of COI they have in their possession.

DHS examined the following security concerns in selecting the type and quantity of COI that are subject to the Top-Screen evaluation:

1. Release – quantities of toxic, flammable or explosive chemicals that have the potential to create significant adverse consequences for human life or health if intentionally released or detonated;

2. Theft and Diversion – chemicals that have the potential, if stolen or diverted, to be used or converted into weapons; and

3. Sabotage and Contamination – chemicals that, if mixed with other readily available materials, have the potential to create significant adverse consequences for human life or health.3

To review the Final Rule, consult the revised list of COI in Appendix A of the CFATS, or to register to use the Top-Screen consequence assessment tool, facilities should visit

Similarly, to examine the Top-Screen Questions Manual, facilities should visit Some of the more common COI that are subject to Top-Screen assessment are Anhydrous Ammonia, Bromine, Chlorine, Ethylene Oxide, Hydrazine, Hydrochloric Acid and Potassium Chlorate.

Although many facilities will be required to prepare Top-Screen consequence assessments in accordance with the Final Rule, DHS has indicated that many of those facilities may not be subject to further regulation under the CFATS.4