Prioritizing risks and uncertainties from intentional release of selected Category A pathogens

Area of Science:

• Environmental science
• Public health
• Risk assessment

Background:

• Category A pathogens pose significant indoor environmental health risks.
• Quantitative guidelines are needed to assess exposure and inform response decisions.

Purpose of the Study:

• To develop quantitative guidelines relating indoor environmental pathogen concentrations to human health risk.
• To construct an integrated model for environmental transport and exposure to biological pathogens.

Main Methods:

• Synthesized information on five Category A pathogens (Bacillus anthracis, Yersinia pestis, Francisella tularensis, Variola major, Lassa).
• Developed an integrated model including environmental attenuation, fomite and inhalation exposure, and uncertainty analysis.
• Assumed uniform mixing in environmental compartments for applicability.

Main Results:

• Inhalation is the primary risk when pathogens are airborne; surface contact (ingestion/dermal) is primary when pathogens are on surfaces.
• Proposed sampling locations (floors, walls, HVAC filters) as indicators of past exposure.
• Identified touched surfaces as indicators of future risk for reoccupied buildings.

Conclusions:

• The study provides a framework for developing environmental standards for risk-informed decisions.
• Identified key parameter uncertainties to guide future research priorities.
• Proposed integrating quantitative uncertainty assessments with qualitative considerations for research prioritization.