Multiplicity of human scent signature

Petr Doležal,Irena Valterová,Veronika Škeříková,Štěpán Urban,Ludvík Pinc,Jana Lněničková,Kenneth G. Furton,Pavlína Kyjaková

doi:10.1186/s41935-019-0112-z

Abstract

BackgroundIn this paper, the term “human scent signature” refers to a group of chemical compounds in a human scent trace that are in certain relative concentrations that make an unambiguous identification of persons possible. At the present time, the scent identification of persons is performed using specially trained canines. However, the scent identification mechanism as well as the molecular composition of the human scent signature is entirely unrecognized. Delimitations of the group of chemical compounds according to their volatilities that specially trained canines use for the scent identification of persons were initially the main aim of this study.MethodsEleven volunteer scent samples were split into three groups of chemical compounds, i.e., into three disjointed scent fractions with different volatilities of the compounds via preparative gas chromatography. The human scent signatures were searched in these separated scent fractions using six specially trained canines (female German Shepherds).ResultsThe canines were able to identify individual persons successfully using different scent fractions. From this fact, it follows that one scent trace can contain more than only one group of scent compounds that can be used for scent identification by the trained canines. This observed phenomenon was named as “the multiplicity of the human scent signature” in this study. The scent identification line-up procedure provided the following results: The poorly volatile fraction resulted in an 85% success rate in the scent identification procedure. The middle fraction resulted in a 58% success rate, and the highly volatile fraction resulted in a 30% success rate.ConclusionsIn this study, it was found that the human scent sample contains more than one group of scent compounds; according to which the trained canines are able to identify human individuals. It means that the human scent sample contains more than only one scent signature. The authors of this research believe that results of this study will open a broad discussion about the multiplicity of the human scent signature, primary scent molecules, optimal canine training, and in general, the scent identification method in many countries.

Highlights

In this paper, the term “human scent signature” refers to a group of chemical compounds in a human scent trace that are in certain relative concentrations that make an unambiguous identification of persons possible
The same scent samples were analyzed by comprehensive two-dimensional gaschromatography–time of flight mass spectrometry (GCxGC–TOFMS) and the results were discussed in our study (Doležal et al 2017)
During this study, 198 “full” scent samples were collected from volunteers and used in line-up identifications as target (TS) and distracting scent (DS) samples

Summary

Introduction

The term “human scent signature” refers to a group of chemical compounds in a human scent trace that are in certain relative concentrations that make an unambiguous identification of persons possible. Identifying the scents of individual persons using specially trained canines is a well-known forensic method (Settle et al 1994; Schoon 1996; Schoon 2005) frequently used in criminal investigations. The results of these identifications are generally understood to be subjective and are legally accepted as corroborating evidence (Marchal et al 2016; Tomaszewski and Girdwoyn 2006) only in some countries (the USA, Spain, France, Russia, Czechia, Poland, Slovakia, etc.). The primary scent category includes compounds that are assumed to be genetically conditioned Their relative concentrations are approximately stable over time regardless of environmental factors, diet, weather, humidity, visceral state, emotional state, illness, menstrual cycle, medication, etc. Tertiary scents originate from the external environment, e.g., from cosmetics used, scents of the workplace, gasoline, smoking, scents of other people, and domestic animals

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