The Department of Homeland Security is charged with securing the nation from the many threats we face. These threats include natural and man-made biological, chemical, radiological, and nuclear threats. As a member of the PHEMCE, DHS is the lead agency responsible for conducting the threat and risk assessments that are leveraged in PHEMCE requirements setting. DHS is also a key partner in PHEMCE response planning, policy, guidance, and communication. Within DHS, the Science and Technology Directorate (S&T) strives to equip decision-makers with tools for better assessing the significant risks that chemical, biological, radiological, and nuclear (CBRN) threats pose to the nation.

The Project BioShield Act of 2004 (P.L. 108-276), requires the Secretary of Homeland Security, in consultation with the Secretary of Health and Human Services (HHS) and the heads of other agencies as appropriate, to make determinations of CBRN agents that are material threats to the U.S. population and authorizes the Secretary of HHS to determine the public health consequences and recommend countermeasures to such threats. If suitable countermeasures do not already exist, this process can culminate in a joint DHS-HHS recommendation to the President or his delegate, the Director of the Office of Management and Budget, to authorize the use of BioShield special reserve funds.

Under Homeland Security Presidential Directives (HSPD) 10, 22, and 18, DHS is mandated to conduct the Biological Terrorism Risk Assessment, the Chemical Terrorism Risk Assessment, the Radiological and Nuclear Terrorism Risk Assessment, and the Integrated CBRN Terrorism Risk Assessment.

The first step in the BioShield process is threat identification and prioritization in order to inform medical countermeasure development and acquisition. DHS has the lead in threat identification and leverages the DHS Integrated Terrorism Risk Assessment findings to determine which CBRN agents present a greater risk based on the relative risk ranking against the U.S. population sufficient to affect national security. Specifically, for the highest ranked agents in the TRA, DHS evaluates the intelligence and threat information and develops and models a highly plausible consequence scenario taking into account acquisition, production, dissemination efficacy, source strength and meteorological conditions. This model is used to derive an estimate of the number of potentially exposed individuals at various levels of exposure, which becomes part of the MTA. The estimates are provided to HHS, which conducts its Public Health Consequence Modeling (PHCM) as the basis for determining public health impacts.

For agents considered to be a material threat, HHS determines whether these agents lack an existing, effective countermeasure and whether a countermeasure should be procured using BioShield reserve funds. If so, then HHS coordinates activities within the interagency Public Health Emergency Medical Countermeasure Enterprise (PHEMCE) to define countermeasure requirements and acquisition options.

• Department of Homeland Security Science and Technology Directorate
• DHS Science and Technology Directorate Strategic Plan
• Department of Homeland Security Office of Health Affairs

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