Comparison of two stimulus-delivery systems for measurement of nasal pungency thresholds

Using representative members of each of three homologous series of chemical s-ketones, acetates and alcohols-we measured nasal pungency thresholds in a nosmics via two stimulus-delivery systems. The first system consists of the fairly commonly used 270 mi, plastic 'squeeze bottles'. The second system consists of 1900 mi, glass vessels with Teflon tubing and nose-pieces. Alth ough bulkier and more susceptible to mechanical breakage, the glass vessels possess advantages that can allow them to provide 'environmentally realist ic' chemosensory thresholds, i.e. thresholds closer in absolute values to t hose that might be obtained under whole-body exposures. Such advantages inc lude a larger volume of the vapor-source to accommodate whole sniffs, and a tight nose-nose-piece connection to avoid stimulus dilution. The outcome r evealed that, for every chemical, the glass vessels provided nasal pungency thresholds significantly lower than those provided by the squeeze bottles. The difference amounted, on average, to a factor of 4.6, though the relati ve potency of the compounds remained the same under both systems. Additiona lly, when tested with the highest homologues used here, namely, octyl aceta te and l-octanol, anosmics using the glass vessels had little or no difficu lty achieving the criterion for threshold whereas they did have difficulty when using the squeeze bottles.