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Accumulation of Explosives in Hair--Part II: Factors Affecting Sorption

NCJ Number
Journal of Forensic Sciences Volume: 52 Issue: 6 Dated: November 2007 Pages: 1291-1307
Jimmie C. Oxley Ph.D.; James L. Smith Ph.D.; Louis J. Kirschenbaum Ph.D.; Suvarna Marimganti Ph.D.
Date Published
November 2007
7 pages
This study examined the sorption to human hair of the following eight explosives: 2,4,6-trinitrotoluene (TNT); pentaerythritol tetranitrate (PETN); hexahydro-1,3,5-trinitro-s-triazine (RDX); diacetone diperoxide (DADP); triacetone triperoxide (TATP); ethylene glycol (EGDN), nitroglycerin (NG); and 2,4-dinitrotoluene (DNT).
The study found that the initial rate at which the explosive is sorbed to hair is relative to the vapor pressure of the explosive. Although initial uptake was rapid, much more gradual uptake continued. For TNT, uptake continued even after 2 years. In a similar experiment performed over a 4-month period, TATP sorption continued to increase with time. Microscopy suggested that hair provided nucleation sites for TATP crystal growth on the surface of the hair. Although there is a general trend for dark hair to sorb explosive more readily than light hair, sorption is a highly individual characteristic, i.e., a person whose hair sorbs TATP well will also sorb TNT well. Once sorbed, the ease with which explosive is removed from the hair depends on the type of explosive. TNT is not lost simply by standing in the open and mild extraction; it requires vigorous washing. TATP, on the other hand, an explosive with high vapor pressure, is readily lost upon standing and mild extraction. This suggests that TNT and TATP are sorbed by hair by different mechanisms. The preferential sorption of explosives by black hair over blond hair and brown hair, the preferential sorption of unbleached hair over bleached, and the preferential sorption of black hair over white hair from the same person suggest melanin is important in explosive sorption; however, wide variation in ability to sorb explosive was observed among black hair from different individuals, which suggests that sorption of explosive to hair is not strictly a matter of binding to melanin. 2 tables, 12 figures, and 18 references