Gunshot residue - Further studies on particles of environmental and occupational origin

The results of studies on particles of environmental and occupational origin conducted at the Reparto Carabinieri Investigazioni Scientifiche, Parma, Italy, are presented. Data were obtained from 175 samples taken from the hands of subjects employed in relevant occupations. Samples were also obtained from automobile interiors, from the hands of motorists after they had worked on the motor, battery and tyres, and from the hands of individuals after they had fired cartridge-operated industrial tools (stud guns), children's cap guns, and had handled and set off fireworks. Although the study confirms that in the majority of cases, occupational samples cannot be falsely identified as gun shot residue, it also demonstrates that people with automobile-related jobs (i.e. mechanics, automobile electricians, tyre repairmen) can be exposed to particles composed of barium and antimony which, in some cases, may be hard to distinguish from irregular, flattened and flaky-looking gun shot residue. The risk of a "false-positive" result is particularly high when automatic research systems and tape-lift collection are used without further investigation based on particle morphology. We therefore believe that a slight change in the classification would be necessary, as we have tried to demonstrate with the present work. Our research also confirms previous studies indicating that Italian cartridge-operated industrial tools produce barium, lead, and antimony particles that may appear compatible with gunshot residue. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.