Chemosensory Detectability of 1-Butanol and 2-Heptanone Singly and in Binary Mixtures

Abstract

Using 1-butanol and 2-heptanone as stimuli we measured detectability (i.e., psychometric) functions for the odor, nasal pungency, and eye irritation of these two substances alone and in binary mixtures. Nasal pungency responses were tested in subjects lacking olfaction (i.e., anosmics) for whom odors do not interfere. Eye irritation responses were tested in normosmics and anosmics and found to be similar in both groups so their results were pooled. When all stimuli -single and mixtures -were transformed into concentration units of one (or the other) chemical, a single function could fit all data from the same sensory endpoint with a correlation coefficient of 0.91 or higher. The outcome lends support, as a first approximation, to the notion of chemosensory agonism, in the sense of dose additivity, between the members of binary mixtures presented at perithreshold levels.

Psychometric functions for the olfactory and trigeminal detectability of butyl acetate and toluene

“…Obtaining a psychometric function, particularly for the chemical senses, entails considerable more experimental work than just measuring a threshold based on a performance criterion, but psychometric functions provide more detailed information to help characterize the sensory modality. For example, psychometric functions were the outcome of choice when we probed into the rules of chemosensory agonism between 2-heptanone and 1-butanol 6 . Figure 6 illustrates how the outcome from the two approaches compares.…”

“…The second one is a cyclic, aromatic hydrocarbon with no oxygen-containing chemical groups. Their selection followed the general idea of testing two compounds with substantial structural and physicochemical differences to mark a contrast with a previous study using identical methodology but employing the relatively similar compounds 1-butanol and 2-heptanone 6 .…”

“…In the present study we have applied this very same methodology but, rather than fixing a criterion for threshold, we decided to build complete psychometric functions (also called detectability or stimulus-response functions) covering the overall range from chance detection to virtually perfect detection. Build-up of these functions entails a considerable amount of testing and subject-time but they provide comprehensive information on the characteristics of both the stimulus and the chemosensory system 6,18,19 .…”

An assessment of air quality reflecting the chemosensory irritation impact of mixtures of volatile organic compounds

“…We start with the psychometric plots obtained from the probability of sensory irritation detection, Q, of a given VOC as a function of its gaseous concentration, log P with P in ppm (Cometto-Muñiz et al, 1999;2001a;2002;2004a;2004b;2007b;2008;Cain et al, 2006). As for the determination of thresholds, this involves a panel of human subjects.…”

“…Several studies of sensory irritation thresholds (NPTs and EITs) from mixtures of VOCs have shown various levels of additivity that, to a first approximation, are not-too-far from complete additivity (Nielsen et al, 1988;Cometto-Muñiz et al, 1997;1999;2001a;2004a;2004b). So are results from studies on ODTs 2005b;Wise et al, 2007;Miyazawa et al, 2009).…”