Olfactory detection

It is well known from World War I that men suffering from phosgene poisoning 

The odour detection threshold has been established by NIOSH [1484], Technically 

The odour index vapour pressure (in p.p.m.)/odour threshold (in p.p.m.) for phosgene at 20 C is recorded as 1600000 [2112]. This dimensionless term is based on the expression of the vapour pressure in p.p.m. for which 1 atmosphere is taken as 1000000 p.p.m. 

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AHyl chloride has a disagreeable, pungent odor. The odor threshold has been estimated at approximately 3—6 ppm (51). Olfactory detection of odor is thus not an adequate warning of overexposure. 

This pathway provides several amplification steps between odorant binding and signal generation. Due to the electrically compact structure of the cell, it is possible for the activation of only a few tens of channels to drive the membrane to the threshold for action-potential generation. Thus, it is theoretically possible that the limit of olfactory detection is a single molecule, although this has not yet been conclusively demonstrated. 

Hydrogen cyanide has frequently been associated with the odor of bitter almonds (Ballantyne 1983 Gee 1987). The threshold odor for olfactory detection of atmospheric HCN is 1 mg/L, but the odor may not be detected for various reasons, including the presence of other odors and the fact that only 20 to 40% of those tested could detect a cyanide odor. 

Within Severn Trent a modified version of this procedure is utilised for the analysis of malodorous emissions. The most significant difference in this approach compared to those already discussed is the use of high resolution gas chromatography in combination with olfactory detection. This method also combines physico-chemical and olfactometric or sensory techniques but in an alternative manner. Utilisation of gas chromatography combined with odour detection is not a new concept and has been employed fairly commonly for the analysis of food aromas, essential oils and other fragrances. The technique is equally applicable to environmental problems and is used frequently in this laboratory for the analysis of atmospheric emissions and taste and odours in water. Three important benefits accrue from this approach in the context of odour emission analysis. 

Of secondary importance as judged by gas chromatography with olfactory detection are -... 

A variety of compounds have been identified as key contributes to certain malodorous emissions originating from water reclamation works. The most important are considered to be polymeric sulphides, volatile fatty acids, indole and cresol. The utilisation of high resolution gas chromatography in conjuction with olfactory detection is identified as a valuable aid to the analytical procedure. 

Presently, US explosives detection dogs tend to be German or Belgian Shepherds, Malinois or Labradors, but there is more variation within a breed than between breeds [22]. Selecting a dog or breeding a dog with optimal olfactory capabilities has only recently been emphasized. Yet, for centuries animals have been bred to perform select tasks. Perhaps olfactory detection has lagged behind in this... 

Thresholds can vary between and within individuals, with the estrus cycle, and with the chemical background. Some benchmarks will be given here. In laboratory (Wistar) rats, the olfactory detection threshold for ethyl acetate was measured as 7.3 x 10 vol% in subadults, while adult rats were more sensitive (1.4 X 10 vol%) (Apfelbach etah, 1990). (By comparison, among insects the gypsy moth is 10 times as sensitive. The threshold for bombykol, defined as... 

Mason, J. R., Kamalesh, J. and K., Morton, T. H. (1987b). Generalization in olfactory detection of chemical cues containing carbonyl functions by tiger salamanders (Ambystoma tigrinum). 13,1-18. 

Willis, C. M., Church, S. M., Guest, C. M., etal. (2004). Olfactory detection of human bladder cancer by dogs proof of principle study. British Medical Journal 329,712. 

Amyl acetates may be recognized at concentrations of 7 ppm by the fruitlike odor characteristic of esters the mean olfactory detection threshold is 0.2 ppm. ... 

Identification of volatile potato sesquiterpenoids and their olfactory detection by the two-spotted stinkbug Perillus bioculatus. Journal of Chemical Ecology 26 1433-1445. 

Not all of the volatile components present in oak wood play a decisive role in determining the aroma of aged wines. While concentrations in the oak wood will be a conditioning factor, final aroma is the result of each component s olfactory detection threshold and the synergistic effects between it and the other wine components. 

Toasted wood extracts and standard media heated in the laboratory were analyzed by gas chromatography and olfactory detection. Several toasty aromatic... 

Corbit, T., Engen, T. 1971. "Facilitation of Olfactory Detection." Perception and Psychophysics, 10 433-436. 

It allows for enantioselective interactions. For example, it has been shown that the interaction of L-DPPC 10 (R = R = n-CjjHji) with (-)-carvone or (/ )- at the air-water interface gives more expanded mono layers than the interaction of this compound with (-H)-carvone or (5)-l This may be relevant to the mechanism of olfactory detection of these... 

Table 18-5 lists diagnostic and treatment approaches with the greatest success according to scientific consensus. Individuals with the belief that their symptoms result from chemical exposure have poorer treatment outcomes than those without such beliefs (Black et al. 2000 Gupta and Horne 2001). Evaluations of patients with MCS should include a full medical examination, including exposure history and consultations with occupational and psychiatric specialists (Sparks et al. 1994b). Adrenal insufficiency, seizures, and certain classes of medications can decrease the olfactory detection threshold and must be ruled out in complaints of MCS (Scott 1989). One case report described an individual with MCS found to have an occipital lobe meningioma. Removal of the tumor did not resolve the MCS symptoms (Moorhead and Suruda 2000). 

Wines with an ethyl-phenol content above the olfactory detection threshold. 

Tables 13.5 and 13.6 show the overall average qnantities of oxygen in red wines during vatting and aging. Experiments show that the qnantities of oxygen nsed in microbubbling are highly variable from one brand of equipment to another, especially dnring vatting after fermentation. These valnes are based on the olfactory detection of ethanal (Table 13.7).

Pickel D., Manucy G., Walker D., Hall S., and Walker J., Evidence for canine olfactory detection of melanoma, Appl. Anim. Behav. ScL, 89, 107-116, 2004. 

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