Hair as Forensic Evidence of Explosive Handling

Hair has the ability to assimilate a variety of chemical compounds. The analysis of hair for determining first‐hand exposure to illegal drugs is a popular forensic technique [1–6]. Molecules such as explosives can also become trapped in hair due to external exposure and detected at trace levels [7–12]. Hair analysis could prove a powerful, non‐invasive method for the detection of individual exposure to illicit explosives. Previous studies showed that in a sealed vessel with adequate headspace, military explosives such as PETN, TNT, and RDX were sorbed to human hair. These organic explosives persisted on hair even after the hair was washed with detergents or solvent [7, 8]. Such sorption was influenced by hair color, and the levels of contamination were on the order of micrograms per gram hair after thousands of hours of exposure. It was assumed that in the “real‐world” explosives would sorb to hair through the condensation of vapors or by the deposition of solid particulates. This study involved the sampling of hair from students and instructors attending field classes for handling explosives at Fort A. P. Hill, Fredericksburg, VA and Redstone Arsenal, AL. Hair was sampled using combs fitted with cheesecloth, and the cheesecloth was extracted and analyzed by GC‐ECD for PETN, TNT, and RDX. On average, 80% of the participants were contaminated with PETN, found in detonating cord, after daily field exercises. Average participant contamination with TNT and RDX in hair ranged from 30 to 50%.