Finding Risk-Based Switchover Points for Response Decisions for Environmental Exposure to Bacillus anthracis

• Published in: Human and ecological risk assessment Vol. 17; no. 2; pp. 489 - 509
• Main Authors: Mitchell-Blackwood, Jade, Gurian, Patrick L, O’Donnell, Cara
• Format: Journal Article
• Language: English
• Published: Boca Raton Taylor & Francis Group 01.01.2010; Taylor & Francis Ltd
• Subjects: Anthrax; Antibiotics; Bacillus anthracis; Benefit cost analysis; Biological & chemical terrorism; Bioterrorism; Contingency planning; cost benefit analysis; decision model; Decisions; Decontamination; disease control; environmental exposure; fumigation; response strategies; Risk; Risk assessment; risk threshold; Studies; Terrorism; Terrorist attacks; Thresholds; vaccination
• ISSN: 1549-7860; 1080-7039; 1549-7860
• DOI: 10.1080/10807039.2011.552401

In the wake of the 2001 terrorist attacks, the use of Bacillus anthracis (anthrax) in bioterrorism attacks has emerged as a realistic concern. Thus, a contingency plan is needed to inform decision-makers about which response actions are appropriate and justified under which circumstances. This study considers the decisions: (1) to undertake prophylactic antibiotic treatment; (2) to vaccinate individuals; or (3) to decontaminate the building. While these response actions are clearly justified for highly exposed individuals, a very large number of individuals exposed to very small risks in areas outside of the immediate vicinity of the release are also likely. Our results indicate that there are non-negligible risk thresholds below which response actions produce more costs than benefits. For the base case, the thresholds range from a risk of 1 in 33 for decontamination by fumigation to 1 in 6,547 for antibiotic prophylaxis and 1 in 7,108 for vaccination. A one-way sensitivity analysis on uncertain variables indicates less than an order of magnitude change in these thresholds. Benefit–cost analysis is a useful tool for assessing tradeoffs among alternative decisions, but cannot be the sole criterion in responding to incidents because of inherent limitations.