Humans odors

Repellents Tested with an Inanimate Attractant. Machines have been constmcted by several groups to measure the intrinsic (initial) repeUency of a compound when it is added to a warm, moist airstream to overcome the attractiveness of the airstream to mosquitoes. Such machines remove the factor of human odor ia attempts to simplify the measurement of repeUency. 

Human Odor, visibility, nasopharyngeal and eye irritation Acute respiratory disease Chronic respiratory disease, lung cancer... 

Figure 6.14 Approximate air supply rate for (human) odor removal (extracted from BS 5925 1980)...

Chen D. and Haviland-Jones J. (1999). Rapid mood change and human odors. Physiol Behav 68, 241-250. 

Hold, B. and Schleidt, M. (1977) The importance of human odor in nonverbal communication. Z. Tierpsychol. 43, 225-238. 

Here is a bit of a complication there is a lot of individual variation in the sense of human olfaction. Not everything smells the same to everyone. This holds both for the intensity of the perceived smeU as well as for its quality pleasant, floral, skunky, sweaty, or no odor at all. Andreas Keller has recently demonstrated that some significant part of this individual variation in the sense of smell derives from genetic variation in human odorant genes. Specifically, two single nucleotide polymorphisms (SNPs), leading to two amino acid substitutions in an odorant receptor, have dramatic affects on the perception of the odor of androstenone, a steroid derived from testosterone. 

As discussed in Ch. 5, dogs are extremely sensitive to odors (Neuhaus, 1953, 1956a,b Neuhaus and Muller, 1954). A dog can identify a human odor against background odors such as bergamot, clove or oregano oil, tobacco smoke. 

Colorless gas pungent suffocating odor human odor perception 0.5 mg/m hquefies by compression at 9.8 atm at 25°C, or without compression at -33.35°C (at 1 atm) sohdifies at -77.7°C critical temperature and pressure, 133°C and 112.5 atm, respectively vapor density 0.59 (air l) density of liquid ammonia 0.677 g/mL at —34°C dielectric constant at —34°C is about 22 extremely soluble in water solution alkaline pKa 9.25 in dilute aqueous solution at 25°C the gas does not support ordinary combustion, but bums with a yellow flame when mixed in air at 16— 27% composition. 

In humans, odor from sweat glands isn t always desirable (though some may argue this point in certain circumstances). But in nature, animal-specific odors produced by evaporation serve as a means of personal identification. Many animals, including humans, can recognize each other by these individualized scents. 

Despite this switching off of the importance of pheromones other types of human odor continue to play an important role in the bonding between individuals between mother and child, between man and woman, and between members of a family. Although our ability to recognize people by their odor is very much less than, say, that of a dog, it is clear that each of us has his or her own unique smell. 

Simple white T-shirt used in human odor discrimination test... 

Wang L, Chen L, Jacob T. Evidence for peripheral plasticity in human odor response. J. Physiol. 2004 554 236-244. 

Acree T, Am H. Flavomet and Human Odor Space. http./Avww. Jlavornet.org. 

Because toluene is fairly volatile, exposure for humans would occur principally by inhalation. It has a human odor threshold of 0.1mgm ( 26ppb). Dermal exposure may also be significant, especially in an industrial setting, where skin may be exposed... 

FLEC measurements of a complaint case of malodorous linoleum showed that wetting of the material increased the emission of, e.g., odorous fatty acids. (Wolkoff et al., 1995). The impact of humidity has also been investigated for other building products (Wolkoff, 1996b). In this article, the impact of temperature, nitrogen instead of air and air velocity in the FLEC have also been investigated for VOCs with low human odor thresholds. 

With a wider range and number of far infrared absorption spectra and more of the requisite expert evaluations, it would doubtless be possible to extend and eventually to clarify our understanding of the complexities of human odor evaluations. The existence of these complexities is at once an obstacle and a challenge and is a consequence of the fact that the messages coming into our consciousness are complex because the molecules in which they are conveyed are themselves complex. What is important is the fact that the sensory inputs can be put in a one-to-one relation with the molecular-vibrational attributes of the stimuli that induce them. 

The relationship between chemical structure and perceived odor has been studied by electrophysiological, chemical-analytical, and psychophysical techniques. Certain odorants in addition to being detected by the olfactory system evoke specific behavioral responses. Recent studies on various mammalian species have attempted to equate specific odor sources with behavioral patterns and to profile the odorants in hopes of Identifying the biologically active components ( ). In addition, studies on human odor suggest similarities in odor sources and types with other mammalian species and also suggest some of these odors may be reflective of internal body processes. 

Table I Diagnostic Potential of Human Odors Odor Source Information Content...

These odors include spermous, musky, fishy, urinous, malty and sweaty, and can be related to some observed human odors (39). 

Thus, Amoore suggests that, if we have a specific olfactory receptor for a given odorant then that odorant might be naturally given off by the body. The sweaty odor of isovaleric acid is probably part of the foot odor and is produced by the action of skin bacteria on apocrine secretion (see below). Pyrolline, the spermous odor, has been shown to be produced by enzymatic breakdown of the polyamines in semen (40). Androst-16-en-3-one, the urinous primary odor, has axillary-like odor the related androstenol, which is found in urine, is perceived as a musky odor to some individuals (41). Both steroids are found in axillary sweat and may be formed as metabolites of apocrine secretion. Chemicals which fit the malty anosmia have not as yet been reported from human odor sources. The natural musks, such as cycloheptadecenone (civet), were first obtained from animal scent glands. 

Since man possess odor sources similar to mammalian species, it is of value to determine both the nature and the biochemical origin of these odorants. Profiling of human odors represents a non-invasive technique which might prove useful in the detection of many metabolic and Infectious disorders and for monitoring normal body processes. Alternatively, we may be unknowingly emitting and perceiving odorants which could effect our interpersonal relationships. Only further research in this area will determine to what extent this occurs. 

Many body odors result from the metabolic processes of bacteria. Consequently, skin-dwelling microorganisms play an important role in the production of human odors. The type and density of bacteria in different body locations are determined by several factors type and density of skin glands moisture levels and the availability oxygen (Leyden,... 

Humans possess rich repositories of odors, one of which, the axillae, has been implicated as the source of semiochemical information. There is, however, no substantial body of evidence to allow one to conclude that releaser-pheromone effects can be ascribed to human odors. While there has been, and undoubtedly will continue to be, a stream of products claiming to use sex attractants and behavior modifiers isolated from humans, the absence of experimental data backing the efficacy of the claims may also be a trademark. Evidence addressing product efficacy may be presented in the form of personal testimonials, magazine/newspaper advertisements or the discoverer s appearance on a T.V. talk-show. Where data on such discoveries has appeared in patents, e.g., the copulin mixture, it can be subjected to an experimental protocol to determine validity. Eventually this will occur with other compounds claimed to be human pheromones and packaged for consumer-purchase caveat emptor). 

Second, almost all of the low-molecular-weight sulfur compounds have objectionable (to humans) odors. Thus, in defense, the skunk sprays offenders with a mixture of thiols (and other compounds) containing the disulfide, (E)-2-buten-l-yl methyl disulfide, and the thiols 1-butane thiol, 3-methylbutane-l-thiol, and ( )-2-butene-l-thiol. Additionally, although the mixture of low-molecular-weight hydrocarbons used as natural gas is essentially odorless (to humans), contamination of that material with only a few parts per billion (ppb) of a mixture of low-molecular-weight (mostly Cs-isomers) thiols is sufficient to allow humans to smell a gas leak. ... 

Almost all of the low-molecular-weight amines have objectionable (to humans) odors. Many of the compounds smell fishy and, indeed, the odor of rotting fish has been attributed to such materials. Some diamines produced by the action of bacteria on decaying organic materials enjoy names refiective of their unpleasant odors, for example, putrescine [H2N(CH2)4NH2] and cadaverine [H2N(CH2)5NH2]. 

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