Analysis of the Cross-Contamination of explosive canine training aids during manufacturing and storage

Explosive detecting canines should be trained using real explosive materials that have minimal contamination by other explosive odors to ensure accurate identification of potential threats. Therefore, the potential for cross-contamination between training aids is of importance. There are various storage methods in use by canine handlers, such as plastic and cloth bags, but these can lead to cross-contamination between training aids during storage. Alternatively, odor-permeable membrane devices (OPMD) may store training aides and be used as a delivery device. OPMDs allow for volatile compounds from the training aids to be released during training while helping to prevent contaminants from entering the device. However, the amount of contamination in a training aid upon receipt from a vendor is outside the control of canine handlers. To test the initial cross-contamination levels of training aids, 11 explosive materials were ordered from three different vendors. A 1-gram sample of each was collected and analyzed using gas chromatography – mass spectrometry. In several cases, explosive materials that are commercially available already exhibit elevated levels of contamination. This indicates that training aids must be acquiring contamination during manufacturing and/or storage at the vendor facility. The cross-contamination of explosive canine training aids stored in OPMDs was further evaluated and compared to traditional storage methods by storing various combinations of storage containers with explosives and using activated charcoal strips to collect the volatile compounds. Only one type of storage container, a Velcro bag, showed evidence of contamination.