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

Author： Mitchell-Blackwood Jade Gurian Patrick O'Donnell Cara

ISSN： 1080-7039

Source： Human and Ecological Risk Assessment, Vol.17, Iss.2, 2011-03, pp. : 489-509

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Abstract

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.