DHS Issues Revised List of Chemical and Threshold Levels for Chemical Facility Security Regulations

On Nov. 20 DHS released a revised final rule and “Appendix A” list of chemicals. The Appendix A list of chemicals provides Screening Threshold Quantities (STQ) that trigger reporting requirements for facilities that possess chemicals of interest that may pose a potential security threat. In finalizing the Appendix A list of chemicals, DHS made several significant changes to the regulation.

DHS identified three primary security issue categories, including: release, threat/diversion and sabotage/contamination. The release and threat/diversion categories were further subdivided into additional security issues. Some chemicals were also given more than one STQ to reflect different potential risks for the different security issue categories.

DHS also addressed the issue of mixtures contained in the chemicals listed in Appendix A by setting minimum concentration levels of the chemical in a mixture that would trigger the reporting requirements. The Department also provided guidance on how the STQ should be calculated for chemicals and mixtures for each security issue listed in Appendix A. Specialized approaches for propane, chlorine and ammonium nitrate were identified in the final rule.
All facilities that possess chemicals listed in Appendix A at or above the STQ must submit a Chemical Security Assessment Tool (CSAT) Top-Screen by Jan. 18, 2008. To register and submit the CSAT Top-Screen, facilities should visit The CSAT Top-Screen Questions and User Manual are also available online at the DHS website at Facilities determined to be “high-risk” will then be required to conduct vulnerability assessments and submit site security plans that meet the appropriate performance standards.
For more information on the chemical facility security regulatory requirements and the revised Appendix A, please visit the NASF website at

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