The scientific foundation and efficacy of the use of canines as chemical detectors for explosives

This article reviews the use of dogs as chemical detectors, and the scientific foundation and available information on the reliability of explosive detector dogs, including a comparison with analytical instrumental techniques. Compositions of common military and industrial explosives are described, including relative vapor pressures of common explosives and constituent odor signature chemicals. Examples of active volatile odor signature chemicals from parent explosive chemicals are discussed as well as the need for additional studies. The specific example of odor chemicals from the high explosive composition C-4 studied by solid phase microextraction indicates that the volatile odor chemicals 2-ethyl-1-hexanol and cyclohexanone are available in the headspace; whereas, the active chemical cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) is not. A detailed comparison between instrumental detection methods and detector dogs shows aspects for which instrumental methods have advantages, a comparable number of aspects for which detector dogs have advantages, as well as additional aspects where there are no clear advantages. Overall, detector dogs still represent the fastest, most versatile, reliable real-time explosive detection device available. Instrumental methods, while they continue to improve, generally suffer from a lack of efficient sampling systems, selectivity problems in the presence of interfering odor chemicals and limited mobility/tracking ability.