Je. Comettomuniz et al., TRIGEMINAL AND OLFACTORY CHEMOSENSORY IMPACT OF SELECTED TERPENES, Pharmacology, biochemistry and behavior, 60(3), 1998, pp. 765-770
In Experiment 1, four normosmics and four anosmics (three congenital,
one idiopathic) provided odor and nasal pungency thresholds, respectiv
ely, for the following terpenes: Delta(3)-carene, p-cymene, linalool,
1,8-cineole, and geraniol, plus the structurally related compound cume
ne. Additionally, all subjects provided nasal localization (i.e., righ
t/left) and eye irritation thresholds. Trigeminally mediated threshold
s (i.e., nasal pungency, nasal localization, and eye irritation) lay a
bout three orders of magnitude above odor thresholds, which ranged bet
ween 0.1 and 1.7 ppm. The results implied uniform chemesthetic sensiti
vity across tasks and sites of impact. In Experiment 2, normosmics and
anosmics provided odor and nasal pungency thresholds, respectively, f
or three pairs of isomeric terpenes: alpha- and gamma-terpinene, alpha
- and beta-pinene, and R(+)- and S(-)-limonene. Odor thresholds ranged
between 1.4 and 19 ppm, that is, about an order of magnitude higher t
han those of the previous terpenes, with no substantial differences be
tween odor thresholds of members of a pair. Regarding chemesthetic imp
act, only alpha-terpinene evoked nasal pungency. The overall outcome s
uggests comparable trigeminal chemosensitivity between nose and eyes a
nd between normosmics and anosmics, as shown before for homologous n-a
lcohols. It also lends support to a previously derived solvation model
of the chemesthetic potency of airborne substances, and indicates the
likely importance of certain molecular-size restrictions for effectiv
e trigeminal impact. (C) 1998 Elsevier Science Inc.