Anthrax Detection. DHS Cannot Ensure That Sampling Activities Will Be Validated
GOVERNMENT ACCOUNTABILITY OFFICE WASHINGTON DC
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Federal agencies responsible for responding to the 2001 anthrax incidents adopted a targeted sampling strategy that they based on their best judgment at the time. They primarily collected samples from specific areas, such as mail-processing areas, using their judgment about where anthrax would most likely be found. Such judgments can be effective in some situations for example, in determining whether a facility is contaminated when information on the source of potential contamination is definitive. However, in the case of a negative finding, when the source of potential contamination is not definitive, the basic question Is this building contaminated will remain unanswered. Therefore, in the case of a negative result, a different strategy, probability sampling, is needed. Probability sampling would have allowed agencies to determine whether the building was contaminated with some defined level of confidence. The federal agencies CDC, EPA, and USPS involved in sampling the postal facilities in 2001 to detect anthrax undertook several activities. These included development of a sampling strategy followed by collection of samples using a variety of methods, transporting and extracting, and analysis of the samples. Neither these activities nor the overall process was validated for anthrax testing. Consequently, the agencies were challenged by the limited information available for reliably choosing one method over another and the lack of information on the detection limit to use when evaluating negative results.
- Medicine and Medical Research
- Statistics and Probability
- Environmental Health and Safety