The Influence of a Humectant on the Retention by Humans of Solanesol from Cigarette Smoke (Part 2, Glycerin)

Two common humectants are used as additives in the cigarette manufacturing process, propylene glycol (PG) and glycerin. The humectants may influence the deposition of cigarette smoke in the human respiratory tract by affecting the hygroscopic properties and growth of smoke particles. This study examines the influence of glycerin addition on the retention of solanesol by smokers. The influence of PG addition has been previously reported (7). The first cigarette used in the study (control) was a commercially available brand containing no additives in the blend (with a measured level of glycerin of 0.19%). The other cigarette (test) had an identical tobacco blend to the control, but had 2.3% added glycerin. The construction of the cigarette with 2.3% glycerin (test) was selected to match as closely as possible the ‘tar’ (as measured by Federal Trade Commission regimen), pressure drop (open and closed), and nicotine level of the commercial cigarette (control). Twelve smokers evaluated both products. The sample collection was performed using three cigarettes smoked within one hour. Each human subject smoked the control cigarette and then the test cigarette in two separate sessions. The exhaled smoke was collected using a vacuum assisted procedure designed to avoid strain in exhaling, and solanesol was analyzed using an high performance liquid chromatography (HPLC) technique. The cigarette butts from the smokers were collected and also analyzed for solanesol. The results obtained for the cigarette butts from the smokers were used to calculate the level of solanesol in the smoke delivered to the human subject, based on calibration curves. These curves were generated separately by analyzing the solanesol in smoke and in the cigarette butts obtained by machine smoking under different puffing regimes. Knowing the levels of delivered amount of solanesol and that in the exhaled smoke it was possible to calculate the retention of this compound from mainstream smoke for the two cigarette types. The amount of solanesol retained by the smoker (per cigarette) was on average 314.8 µg/cig with 18.9% relative standard deviation for the commercial cigarette, and 302.6 µg/cig with 20.3% relative standard deviation for the cigarette with 2.3% added glycerin. The retention % of solanesol from the commercial cigarette showed an average of 69.5% with 9.4% relative standard deviation, and the cigarette with 2.3% added glycerin showed an average retention of 69.4% with 10.5% relative standard deviation. Applying the paired t-test to the data it was found that there were no significant differences in the retention amount of solanesol, or in the retention % of solanesol for the two cigarettes. No correlation was found between the amount of solanesol delivered to the smoker (in µg/cig) and the solanesol retention % by the smoker.