RELATIVE SENSITIVITY OF THE OCULAR TRIGEMINAL, NASAL TRIGEMINAL AND OLFACTORY SYSTEMS TO AIRBORNE CHEMICALS

We measured thresholds for eye irritation and odor in homologous serie s of alcohols (ethanol, 1-butanol, 1-hexanol and l-octanol), ketones ( 2-propanone, 2-pentanone, 2-heptanone and 2-nonanone), and alkylbenzen es (toluene, ethyl benzene and propyl benzene). Eye irritation thresho lds were well above odor thresholds for all series. Both sensory thres holds declined with carbon chain length, a trend that has implicated l ipophilicity in the potency of these and related stimuli. Eye irritati on thresholds were remarkably close to nasal pungency thresholds obtai ned previously in persons lacking olfaction (i.e. anosmics). The agree ment between the two thresholds implies that, despite differences in t he mucus layer at the two sites and in the epithelial tissue itself, t here is remarkable similarity at the site of stimulation. As a practic al matter, the eyes could serve as the sites to assess potency for ind uction of nasal pungency, an assessment previously limited to testing anosmics. Presumably for our brief stimulus presentations (1-3 s), the differences between ocular and nasal mucosae have little relevance to chemical sensitivity. Studies of the ability of homologous chemical s eries to evoke threshold eye irritation, nasal pungency and odor not o nly have practical value, but also can help to define the physicochemi cal properties of the receptor and perireceptor biophases.