Investigation and analysis of explosive traces in public locations with no military context: a critical review

This review examines the prevalence of high explosives and gunshot residue (GSR) in public areas with the primary focus on the likelihood of innocent contamination and its implication for forensic investigations. It is found that most studies acknowledge limitations in sample size and geographical scope, emphasizing the need for broader research encompassing diverse locations and environments. Newly applied technologies like Ambient Mass Spectrometry (AMS) and Raman Spectroscopy hold promise for rapid, sensitive, and selective detection of explosives, potentially revolutionising future research and analysis of real-world environments. Multiple studies demonstrate that the detection of high explosive traces like trinitrotoluene (TNT), Research Department Explosive (RDX), and pentaerythritol tetranitrate (PETN) in public areas is statistically rare, indicating a low probability of innocent contamination. In addition, research on GSR prevalence reveals a similarly low risk of transfer from public surfaces, and while some organic GSR (oGSR) components like 2,6-dinitrotoluene (2,6-DNT) are common in non-shooting environments, others like trinitroglycerine (TNG), particularly in conjunction with markers like ethyl centralite (EC), hold stronger evidentiary value. This highlights the importance of analysing oGSR compounds in combination and considering the specific context of the case. More broadly, the dual-use nature of certain chemicals (e.g. ammonium nitrate in both explosives and fertilizers) necessitates cautious interpretation. Similarly, brake pad dust mimicking GSR and low volatility explosives like High Melting Explosive (HMX) present challenges for detection and underscore the need for expert analysis considering environmental factors.