Human Body Odor Research Articles

Advances in chemical sensing technologies for VOCs in breath for security/threat assessment, illicit drug detection, and human trafficking activity

On-site chemical sensing of compounds associated with security and terrorist attacks is of worldwide interest. Other related bio-monitoring topics include identification of individuals posing a threat from illicit drugs, explosive manufacturing, as well as searching for victims of human trafficking and collapsed buildings. The current status of field analytical technologies is directed towards the detection and identification of vapours and volatile organic compounds (VOCs). Some VOCs are associated with exhaled breath, where research is moving from individual breath testing (volatilome) to cell breath (microbiome) and most recently to crowd breath metabolites (exposome). In this paper, an overview of field-deployable chemical screening technologies (both stand-alone and those with portable characteristics) is given with application to early detection and monitoring of human exposome in security operations. On-site systems employed in exhaled breath analysis, i.e. mass spectrometry (MS), optical spectroscopy and chemical sensors are reviewed. Categories of VOCs of interest include (a) VOCs in human breath associated with exposure to threat compounds, and (b) VOCs characteristic of, and associated with, human body odour (e.g. breath, sweat). The latter are relevant to human trafficking scenarios. New technological approaches in miniaturised detection and screening systems are also presented (e.g. non-scanning digital light processing linear ion trap MS (DLP-LIT-MS), nanoparticles, mid-infrared photo-acoustic spectroscopy and hyphenated technologies). Finally, the outlook for rapid and precise, real-time field detection of threat traces in exhaled breath is revealed and discussed.

The human body odor compound androstadienone increases neural conflict coupled to higher behavioral costs during an emotional Stroop task

The androgen derivative androstadienone (AND) is a substance found in human sweat and thus may act as human chemosignal. With the current experiment, we aimed to explore in which way AND affects interference processing during an emotional Stroop task which used human faces as target and emotional words as distractor stimuli. This was complemented by functional magnetic resonance imaging (fMRI) to unravel the neural mechanism of AND-action. Based on previous accounts we expected AND to increase neural activation in areas commonly implicated in evaluation of emotional face processing and to change neural activation in brain regions linked to interference processing.For this aim, a total of 80 healthy individuals (oral contraceptive users, luteal women, men) were tested twice on two consecutive days with an emotional Stroop task using fMRI.Our results suggest that AND increases interference processing in brain areas that are heavily recruited during emotional conflict. At the same time, correlation analyses revealed that this neural interference processing was paralleled by higher behavioral costs (response times) with higher interference related brain activation under AND. Furthermore, AND elicited higher activation in regions implicated in emotional face processing including right fusiform gyrus, inferior frontal gyrus and dorsomedial cortex. In this connection, neural activation was not coupled to behavioral outcome. Furthermore, despite previous accounts of increased hypothalamic activation under AND, we were not able to replicate this finding and discuss possible reasons for this discrepancy.To conclude, AND increased interference processing in regions heavily recruited during emotional conflict which was coupled to higher costs in resolving emotional conflicts with stronger interference-related brain activation under AND. At the moment it remains unclear whether these effects are due to changes in conflict detection or resolution. However, evidence most consistently suggests that AND does not draw attention to the most potent socio-emotional information (human faces) but rather highlights representations of emotional words.

Influence of Body Odors and Gender on Perceived Genital Arousal.

Olfaction is often linked to mating behavior in nonhumans. Additionally, studies in mating behavior have shown that women seem to be more affected by odor cues than men. However, the relationship between odor cues and sexual response-specifically, sexual arousal-has not been studied yet. The aim of this study was to evaluate the impact of the exposure to human body odors (from individuals of the opposite gender) on perceived genital arousal, while these were presented concomitantly to sexually explicit video clips. Eighty university students (40 women) rated their perceived genital arousal (perceived degree of erection/genital lubrication) in response to an audiovisual sexual stimulus, while simultaneously exposed to a body odor from an opposite-gender donor or no odor. Participants also rated each odor sample's (body odor and no odor) perceived pleasantness, intensity, and familiarity. Findings indicated that odor condition had an effect on women's (but not men's) perceived genital arousal, with women showing higher levels of perceived genital arousal in the no odor condition. Also, results showed that women rated body odors as less pleasant than no odor. Notwithstanding, the odor ratings do not seem to explain the association between body odor and perceived genital arousal. The current results support the hypothesis that women, rather than men, are sensitive to odors in the context of sexual response. The findings of this study have relevance for the understanding of human sexuality with respect to chemosensory communication.

Interspecies transmission of emotional information via chemosignals: from humans to dogs (Canis lupus familiaris)

We report a study examining interspecies emotion transfer via body odors (chemosignals). Do human body odors (chemosignals) produced under emotional conditions of happiness and fear provide information that is detectable by pet dogs (Labrador and Golden retrievers)? The odor samples were collected from the axilla of male donors not involved in the main experiment. The experimental setup involved the co-presence of the dog's owner, a stranger and the odor dispenser in a space where the dogs could move freely. There were three odor conditions [fear, happiness, and control (no sweat)] to which the dogs were assigned randomly. The dependent variables were the relevant behaviors of the dogs (e.g., approaching, interacting and gazing) directed to the three targets (owner, stranger, sweat dispenser) aside from the dogs' stress and heart rate indicators. The results indicated with high accuracy that the dogs manifested the predicted behaviors in the three conditions. There were fewer and shorter owner directed behaviors and more stranger directed behaviors when they were in the "happy odor condition" compared to the fear odor and control conditions. In the fear odor condition, they displayed more stressful behaviors. The heart rate data in the control and happy conditions were significantly lower than in the fear condition. Our findings suggest that interspecies emotional communication is facilitated by chemosignals.

Body odor, bacteria, and insect mind melds

Body odor, bacteria, and insect mind melds For anyone who has ever wanted to share a psychic experience with ants, the opportunity for arthropod communion now awaits you at New York City’s Guggenheim Museum until July 5. There, Anicka Yi’s exhibition “Life Is Cheap” features ants, ant aroma, human body odor, armpit bacteria, agar, and other equally delightful, quirky media. First, you should know that this is art you experience with your nose. When visitors enter the exhibition, canisters spritz scents derived from body odor originating from Asian American women and carpenter ants in a work titled “Immigrant Caucus.” To create the fragrance, Yi sampled the women’s sweat and worked with forensic chemist Kenneth Furton to identify the chemical constituents of the human body odors. Furton, a professor at Florida International University, is a pro at scent detection, although he’s arguably better known for his cadaver odor expertise than for

LSPR sensor array based on molecularly imprinted sol-gels for pattern recognition of volatile organic acids

Volatile organic acids are important compounds contained in human body odor. The detection and recognition of volatile organic acids in human body odor are significant in many areas. The present study explored a possibility to use localized surface plasmon resonance (LSPR) of Au nanoparticles (AuNPs) and molecularly imprinted sol-gels (MISGs) as the sensitive layer to recognize typical organic acid odorants, propanoic acid (PA), hexanoic acid (HA), heptanoic acid (HPA) and octanoic acid (OA), from human body. The LSPR layer was prepared by vacuum sputtering of AuNPs on a glass substrate and consequently thermal annealing. The sensitive layer was fabricated by spin-coating molecularly imprinted titanate sol-gel on the AuNPs layer. A homemade optical device was developed to detect the change of transmittance, which was caused by the index changes of organic acid vapors where selecting absorbed by the MISG layers. It was found that compared with MISG coated samples, samples coated with non-imprinted sol gel (NISG) shown no responses to any acid vapors. For the MISG coated sensors, the LSPR sensitivity was affected by the spin coating speed. In addition, a sensor array based on MISGs with different templates (HA, HPA and OA) was constructed to detect the organic acids in single and their binary mixtures. The sensor response was analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). A 100% classification rate was achieved by leave-one-out cross-validation technique for LDA model. This work demonstrated that the MISGs coated LSPR sensor array has a great potential in organic acid odor recognition of human body odor.

The human body odor compound androstadienone leads to anger-dependent effects in an emotional Stroop but not dot-probe task using human faces.

The androgen derivative androstadienone is a substance found in human sweat and thus is a putative human chemosignal. Androstadienone has been studied with respect to effects on mood states, attractiveness ratings, physiological and neural activation. With the current experiment, we aimed to explore in which way androstadienone affects attention to social cues (human faces). Moreover, we wanted to test whether effects depend on specific emotions, the participants' sex and individual sensitivity to smell androstadienone. To do so, we investigated 56 healthy individuals (thereof 29 females taking oral contraceptives) with two attention tasks on two consecutive days (once under androstadienone, once under placebo exposure in pseudorandomized order). With an emotional dot-probe task we measured visuo-spatial cueing while an emotional Stroop task allowed us to investigate interference control. Our results suggest that androstadienone acts in a sex, task and emotion-specific manner as a reduction in interference processes in the emotional Stroop task was only apparent for angry faces in men under androstadienone exposure. More specifically, men showed a smaller difference in reaction times for congruent compared to incongruent trials. At the same time also women were slightly affected by smelling androstadienone as they classified angry faces more often correctly under androstadienone. For the emotional dot-probe task no modulation by androstadienone was observed. Furthermore, in both attention paradigms individual sensitivity to androstadienone was neither correlated with reaction times nor error rates in men and women. To conclude, exposure to androstadienone seems to potentiate the relevance of angry faces in both men and women in connection with interference control, while processes of visuo-spatial cueing remain unaffected.

Fluorometric Biosniffer Camera "Sniff-Cam" for Direct Imaging of Gaseous Ethanol in Breath and Transdermal Vapor.

Various volatile organic compounds can be found in human transpiration, breath and body odor. In this paper, a novel two-dimensional fluorometric imaging system, known as a "sniffer-cam" for ethanol vapor released from human breath and palm skin was constructed and validated. This imaging system measures ethanol vapor concentrations as intensities of fluorescence through an enzymatic reaction induced by alcohol dehydrogenase (ADH). The imaging system consisted of multiple ultraviolet light emitting diode (UV-LED) excitation sheet, an ADH enzyme immobilized mesh substrate and a high-sensitive CCD camera. This imaging system uses ADH for recognition of ethanol vapor. It measures ethanol vapor by measuring fluorescence of nicotinamide adenine dinucleotide (NADH), which is produced by an enzymatic reaction on the mesh. This NADH fluorometric imaging system achieved the two-dimensional real-time imaging of ethanol vapor distribution (0.5-200 ppm). The system showed rapid and accurate responses and a visible measurement, which could lead to an analysis of metabolism function at real time in the near future.

Body odor classification by selecting optimal peaks of chemical compounds in GC–MS spectra using filtering approaches

Present study deals with the operation of filter based approaches for selection of an optimal subset of peaks of chemical compounds in gas chromatography (GC)-mass spectrometry (MS) spectra with the objective to robust classification modeling of human body odor. Particularly, we have employed four filter based approaches including CFS, Linear-correlation, Rank-correlation, and Relief, in the selection of significant peaks and compared their performance. Selected subsets have been validated for qualitative and quantitative classification of human body odor samples in principal component (PC) space. Filter schemes were validated by analyzing sixteen decisive odor data sets obtained through characterization of body odor samples by GC–MS in four different experiments. Every feature filtering method results in an optimal subset of peaks for each data set. Efficiency of a particular subset of peaks has been evaluated by using them in PC analysis, and thereafter on the basis of visual discrimination as well inter-class separation (b) and intra-class (a) separation in PC space. Few methods result in a common subset of peaks for some data sets, though the maximum value of b and a minimum value of a has been obtained for discrimination amongst body odor samples by using selected subsets of peaks compare to all peaks in spectra. Best human body odor class discrimination outcomes have been achieved by using peaks of chemical compounds selected by Relief and CFS filters.

Molecularly Imprinted Sol-Gel-Based QCM Sensor Arrays for the Detection and Recognition of Volatile Aldehydes.

The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor arrays based on molecularly imprinted sol-gel (MISG) materials were developed in this work for highly sensitive detection and highly selective recognition of typical aldehyde vapors including hexanal (HAL); nonanal (NAL) and bezaldehyde (BAL). The MISGs were prepared by a sol-gel procedure using two matrix precursors: tetraethyl orthosilicate (TEOS) and tetrabutoxytitanium (TBOT). Aminopropyltriethoxysilane (APT); diethylaminopropyltrimethoxysilane (EAP) and trimethoxy-phenylsilane (TMP) were added as functional monomers to adjust the imprinting effect of the matrix. Hexanoic acid (HA); nonanoic acid (NA) and benzoic acid (BA) were used as psuedotemplates in view of their analogous structure to the target molecules as well as the strong hydrogen-bonding interaction with the matrix. Totally 13 types of MISGs with different components were prepared and coated on QCM electrodes by spin coating. Their sensing characters towards the three aldehyde vapors with different concentrations were investigated qualitatively. The results demonstrated that the response of individual sensors to each target strongly depended on the matrix precursors; functional monomers and template molecules. An optimization of the 13 MISG materials was carried out based on statistical analysis such as principle component analysis (PCA); multivariate analysis of covariance (MANCOVA) and hierarchical cluster analysis (HCA). The optimized sensor array consisting of five channels showed a high discrimination ability on the aldehyde vapors; which was confirmed by quantitative comparison with a randomly selected array. It was suggested that both the molecularly imprinting (MIP) effect and the matrix effect contributed to the sensitivity and selectivity of the optimized sensor array. The developed MISGs were expected to be promising materials for the detection and recognition of volatile aldehydes contained in exhaled breath or human body odor.

The smell of us – crowdsourcing human body odor evaluation

Human body odor is produced when sweat-secreted compounds are metabolized by bacteria present on the skin. The resulting volatile mixture is often negatively perceived, motivating the use of personal cosmetic deodorants. Yet body odor may also be positively perceived in some contexts, and is proposed to play a role in sexual attraction, kin identification and social bonding. Because only human smellers can report the hedonic qualities of body odor, their persceptions are a valualbe complement to modern GC-MS-based quantitative chemical measurements. Here we present a crowdsourcing framework that engages volunteer smellers to characterize human sweat samples. Our approach seeks to reward both the sweat donor and the smeller with a web-based graphical interface that is informative, interesting, and fun. 300 samples from 87 individual donors were scored by 93 smellers for intensity, pleasantness, and a variety of odor descriptors. Body odor intensity and pleasantness were determined to vary with age, gender, and self-reported deodorant use. Counterintuitively, deodorant use showed no effect on the perceived intensity of body odor, and was associated with a decrease in the perceived pleasantness. From these data, we determine the precision and dynamic range of the volunteer nose as a body odor evaluation instrument and estimate the scale of crowdsourcing effort that would be required to precisely quantify the public perception of body odors.

Characterization of human body odor and identification of aldehydes using chemical sensor

AbstractHuman body odor is a unique identity feature of individual as well as an established composite of numerous volatile organic compounds (VOCs) belonging to significant chemical classes. Several analytical methods have been used in the characterization of human body odor in order to recognize the chemical composition of VOCs in medical, forensic, and biometric applications. Besides, real-time sensing systems (based on the chemical sensors) are being researched and developed for qualitative and quantitative recognition of VOCs in body odor. The present review focuses the state-of-the-art research outcomes related to the characterization of human body odor with the objective to identify the VOCs belonging to aldehyde class. Furthermore, the application of chemical sensors in past studies for the detection of aldehydes besides other chemical compounds in body odor is summarized and the significance of aldehydes detection in different applications is discussed.

Organization of olfactory centres in the malaria mosquito Anopheles gambiae.

Mosquitoes are vectors for multiple infectious human diseases and use a variety of sensory cues (olfactory, temperature, humidity and visual) to locate a human host. A comprehensive understanding of the circuitry underlying sensory signalling in the mosquito brain is lacking. Here we used the Q-system of binary gene expression to develop transgenic lines of Anopheles gambiae in which olfactory receptor neurons expressing the odorant receptor co-receptor (Orco) gene are labelled with GFP. These neurons project from the antennae and maxillary palps to the antennal lobe (AL) and from the labella on the proboscis to the suboesophageal zone (SEZ), suggesting integration of olfactory and gustatory signals occurs in this brain region. We present detailed anatomical maps of olfactory innervations in the AL and the SEZ, identifying glomeruli that may respond to human body odours or carbon dioxide. Our results pave the way for anatomical and functional neurogenetic studies of sensory processing in mosquitoes.

GC–MS characterization of body odour for identification using artificial neural network classifiers fusion

The focus of the present study is the human body odour recognition by analysis of information about the chemical compounds identified in their gas chromatography–mass spectrometry (GC–MS) chromatogram. The Artificial neural network (ANN) technique implemented in the current study, has been comprehensively used for classification and regression tasks in numerous applications. The experimental data set includes intensity characteristics (peak height, peak area, ratio of peak area and height) of several chemical compounds detected in GC–MS chromatogram of twenty odour samples (from four persons), and two non-body odour samples. The raw data set is transformed with logarithmic scaling, principal component analysis (PCA), and kernel principal component analysis (KPCA) in search of the better features by extracting. After preprocessing of data, feed forward back-propagation neural network (BPNN) technique is used in discrimination of body and non-body odour samples, as well as recognition of body odour to an individual. Although ANN classifier is optimized for the number of neurons, and training algorithms, the classification result is unstable and unsatisfactory (maximum correct classification rate 78% and minimum correct classification rate 44%). To improve the stability and accuracy of ANN classification results, data fusion approach is attempted. Eight different weighted and unweighted decision schemes of data fusion have been implemented in body odour recognition. Amongst them simple weighted vote (SWV), quadratic best worst weighted vote (QBWWV), and best worst weighted vote (BWWV) outperform with 100% class recognition outcomes, compared with a single ANN classifier.

The impact of artificial fragrances on the assessment of mate quality cues in body odor

Cultural practices may either enhance or interfere with evolved preferences as predicted by culture–gene coevolution theory. Here, we investigated the impact of artificial fragrances on the assessment of biologically relevant information in human body odor. To do this, we examined cross-sensory consistency (across faces and odors) in the perception of masculinity and femininity in men and women, and how consistency is influenced by the use of artificial fragrance. Independent sets of same and opposite-sex participants rated odor samples (with and without a fragrance, n=239 raters), and photographs (n=130) of 20 men and 20 women. In female, but not male raters, judgments of masculinity/femininity of non-fragranced odor and faces were correlated. However, the correlation between female ratings of male facial and odor masculinity was not evident when assessing a fragranced body odor. Further analysis also indicated that differences in ratings of male odor masculinity between men with high and low levels of facial masculinity were not present in fragranced body odor samples. This effect was absent in ratings of female odors by both female and male raters, suggesting sex-specificity in the effects of fragrance on odor perception. Our findings suggest that women may be more attentive to these odor cues, and therefore also to disruption of this information through fragrance use. Our results show that cultural practices might both enhance and interfere with evolved preferences.

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Do pheromones influence human behavior?

Social communication via airborne chemicals is ubiquitous in the animal kingdom. Such active substances were designated as “pheromones” by Karlson and Luscher in 1959. As specified by the original definition, pheromones refer to substances that are secreted to the outside by an individual and received by a second individual of the same species, in which they release a specific reaction, for example, a definite behavior or a developmental process. Over the past fifty years, a number of pheromones with distinct functions have been identified in invertebrates as well as in mammals. In the case of mammalian pheromones, recent findings reveal that some of them are processed in the main olfactory system, contrary to the traditional belief that mammalian pheromones are exclusively encoded by the vomeronasal organ and act through the accessory olfactory system. Humans are thought as the most highly scented ape of all in terms of numbers and sizes of sebaceous and apocrine glands. The search for human pheromones, however, has met with less success. The challenges lie in several aspects: (i) Human behavior is highly complex and multifaceted; (ii) Human secretions contain an enormous number of components with changeable concentrations; and (iii) Unlike most mammals, humans do not have a functional accessory olfactory system and rely solely on the main olfactory system to process airborne chemical compounds. Nonetheless, humans possess at least one functional V1r-like gene, a counterpart of the V1r genes that express pheromone receptors in rodents. Moreover, there has been accumulating evidence indicating that human body odors exert a range of pheromone-like effects on odor recipients. These include triggering innate behavioral responses, modulating endocrine levels, signaling social information, and affecting moods and cognition, in line with the roles of releaser, primer, signaler, and modulator pheromones, respectively. In particular, two human steroids—androsta-4,16,- dien-3-one, the most prominent androstene present in male semen, in axillary hair, and on axillary skin surface, and estra-1,3,5(10),16-tetraen-3-ol, first identified in female urine, are considered “putative human sex pheromones”. They have been shown to convey sexual information, modulate mood state, alter autonomic responses, and activate the hypothalamus in manners contingent on the recipient’s gender and sexual orientation yet below his or her awareness. The findings to date have furthered our understandings of human chemosignaling and interpersonal communication, and have paved the way for future investigations of human pheromones. Identifying the mechanisms underlying the release and detection of human pheromones and molecularly characterizing them represent important directions for future work.

Chemosensory Communication of Gender Information: Masculinity Bias in Body Odor Perception and Femininity Bias Introduced by Chemosignals During Social Perception.

Human body odor is a source of important social information. In this study, we explore whether the sex of an individual can be established based on smelling axillary odor and whether exposure to male and female odors biases chemosensory and social perception. In a double-blind, pseudo-randomized application, 31 healthy normosmic heterosexual male and female raters were exposed to male and female chemosignals (odor samples of 27 heterosexual donors collected during a cardio workout) and a no odor sample. Recipients rated chemosensory samples on a masculinity-femininity scale and provided intensity, familiarity and pleasantness ratings. Additionally, the modulation of social perception (gender-neutral faces and personality attributes) and affective introspection (mood) by male and female chemosignals was assessed. Male and female axillary odors were rated as rather masculine, regardless of the sex of the donor. As opposed to the masculinity bias in the odor perception, a femininity bias modulating social perception appeared. A facilitated femininity detection in gender-neutral faces and personality attributes in male and female chemosignals appeared. No chemosensory effect on mood of the rater was observed. The results are discussed with regards to the use of male and female chemosignals in affective and social communication.

Diversity and evolution of the primate skin microbiome.

Skin microbes play a role in human body odour, health and disease. Compared with gut microbes, we know little about the changes in the composition of skin microbes in response to evolutionary changes in hosts, or more recent behavioural and cultural changes in humans. No studies have used sequence-based approaches to consider the skin microbe communities of gorillas and chimpanzees, for example. Comparison of the microbial associates of non-human primates with those of humans offers unique insights into both the ancient and modern features of our skin-associated microbes. Here we describe the microbes found on the skin of humans, chimpanzees, gorillas, rhesus macaques and baboons. We focus on the bacterial and archaeal residents in the axilla using high-throughput sequencing of the 16S rRNA gene. We find that human skin microbial communities are unique relative to those of other primates, in terms of both their diversity and their composition. These differences appear to reflect both ancient shifts during millions of years of primate evolution and more recent changes due to modern hygiene.

What Makes Us Smell: The Biochemistry of Body Odour and the Design of New Deodorant Ingredients.

Today, axilla odours are socially stigmatized and are targeted with deodorants and antiperspirants representing a multi-billion market. Axilla odours aren't simple byproducts of our metabolism but specifically formed by an intricate interplay between i) specific glands, ii) secreted amino acid conjugates of highly specific odorants and iii) selective enzymes present in microorganisms colonizing our skin, providing a natural 'controlled-release' mechanism. Within a multidisciplinary research project, we were able to elucidate the structure of key body odorants, isolate and characterize secreted amino acid conjugates and identify the enzymes responsible for odour release. These enzymes then served as targets for the development of specific active compounds in an almost medicinal chemistry approach, an approach rarely used in the cosmetic field so far. Here we review the key new insights into the biochemistry of human body odour formation, with some remarks on the experimental steps undertaken and hurdles encountered. The development of deodorant actives and the difficult path to market for such specifically acting cosmetic actives is discussed. The basic insights into the biochemistry also opened the way to address some questions in population genetics: Why have large proportions of Asians lost the 'ability' to form body odours? Do twins smell the same? Are our typical body odours indeed influenced by the immune system as often claimed? After addressing these questions, I'll conclude with the key remaining challenges in this field on an ecological niche that is 'anatomically very close to our heart'.