Marin, A.B., Acree, T.E. and Barnard, J. 1988.
Variation in odor detection thresholds determined by charm analysis.
Chem. Senses 13(3): 435-44.
Variation in odor detection thresholds for 4 groups of individuals, cross-classified by sex and age, was detd. by using 7 std. aroma compds.; Et butanoate, Et 2-methylbutanoate, Et hexanoate, 1,8-cineole, menthone, l-menthol, and l-carvone. These compds. were selected for study because they are all naturally occurring food constituents, and specific anosmia has been reported for some of them. Odor detection thresholds were detd. by using charm anal. The technique presents a sequence of pure aroma compds. in a stream of humidified air for subjects to smell. During a timed sniffing episode, the subject records the instant each odor is detected and the instant it disappears. Each odor stimulus is identified and characterized by its specific presentation time. Analyses are repeated at several dilns. of the stimulus mixt. until no odors are detected. Response data for each odor are combined over all dilns. to yield odor-activity units called charm. Charm values are proportional to the amt. of stimulus and inversely proportional to the subject's threshold. Results of this expt. show that charm anal. is a reproducible method for detg. gas-phase odor detection thresholds. Differences in thresholds between subjects were not the same for all 7 compds. None of the thresholds were influenced by sex, whereas the threshold of l-carvone was affected by age and significant threshold differences between individuals of the same sex and age were found for menthone, l-menthol, and l-carvone.