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Understanding Detection Limits within the Current Interim Clearance Goal for Bacillus anthracis Contamination
Citation:
Silvestri, E., A. Murdock, R. James, W. Calfee, J. Archer, AND K. Maxwell. Understanding Detection Limits within the Current Interim Clearance Goal for Bacillus anthracis Contamination. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-21/124, 2021.
Impact/Purpose:
The clearance of a site after a contamination incident involves assessments of the extent of contamination, efficiency of remediation, and the risks that may be present if remediation is not 100% effective or if low levels of contamination are still present at the edges of the contaminated area. Multiple lines of evidence are applied in this determination, among them results from environmental sampling, which can introduce risk due to inefficiencies in sampling and analysis, possible false negative results, and detection limits from the methods themselves. In this report, sampling and analysis method ranges of recovery efficiency (RE), limit of detections (LOD), and false negative rates (FNR) for environmental matrices and analysis methods will be summarized and used to illustrate their effects on the interpretation of sampling results in regard to clearance decisions. A previous literature review by Herzog et al. (2009) investigated how instrument and environmental limits of detection (LOD) for Bacillus anthracis (Ba) analysis methods affected determination of risk to human health . This literature search looked to expand on that search by focusing on journal articles, reports, guidance documents, book chapters, and conference proceedings since the 2009 article, focusing on LOD, RE, and FNR for sampling and analysis methods for Ba and its surrogates. Uncertainties in sampling and measurement results complicate decision making, namely that a zero detection result may not truly be indicative of no contamination. The current detection limits and considerations discussed in this report will help to define the inputs to these risk considerations. In addition, a flow chart is presented i that summarizes the steps involved in the clearance process and links to information in the text that informs these decisions. This report could be used by decision makers and the environmental unit when characterizing and clearing a site.
Description:
In this report, sampling and analysis method ranges of recovery efficiency (RE), limit of detections (LOD), and false negative rates (FNR) for environmental matrices and analysis methods will be summarized and used to illustrate their effects on the interpretation of sampling results in regard to clearance decisions. A previous literature review by Herzog et al. (2009) investigated how instrument and environmental limits of detection (LOD) for Bacillus anthracis (Ba) analysis methods affected determination of risk to human health . This literature search looked to expand on that search by focusing on journal articles, reports, guidance documents, book chapters, and conference proceedings since the 2009 article, focusing on LOD, RE, and FNR for sampling and analysis methods for Ba and its surrogates. Uncertainties in sampling and measurement results complicate decision making, namely that a zero detection result may not truly be indicative of no contamination. The current detection limits and considerations discussed in this report will help to define the inputs to these risk considerations. In addition, a flow chart is presented i that summarizes the steps involved in the clearance process and links to information in the text that informs these decisions.