The low sensitivity, the high level of possible cross-reactivity with environmental bacteria, and the failure to detect dangerous species of Bacillus anthracis and Yersinia pestis limit the usefulness of these hand-held assays. All of the HHAs gave false-positive results with at least one bacterial species that was not the target organism. Further evaluation with environmental samples collected from a wide geographical region is warranted in order to better define the specificity of the HHAs. Further, the number of organisms reported to produce disease in humans was much fewer than the lower limit of consistent detection for both types of assays. Additionally, some HHAs were incapable of detecting infectious agents that cause anthrax and plague. The HHAs are intended for use during the emergency-response phase of a suspected or potential exposure to a biological threat. HHAs are small test strips that contain antibodies to a specific biological agent. A suspect sample is suspended in a liquid supplied with the test assay. The liquid suspension is then applied to the test strip and allowed to develop for approximately 15 minutes. If a biological threat agent is present within the sample, a colored band will appear on the test strip. A quality control test is built into all the strips in order to indicate whether the assay materials are working properly.