In this study, a comparison between the chemical composition of the particulate-phase of exhaled smoke and that of smoke generated with a smoking machine has been performed. For this purpose, eight human subjects smoked a common Lights (10.6 mg ‘tar’/cig) commercial cigarette and the exhaled particulate-phase smoke from three cigarettes was collected on Cambridge pads for each smoker. The smoke collection from the human subjects was vacuum assisted. The cigarette butts from the smokers were collected and analyzed for nicotine. The machine smoking was performed with a Borgwaldt RM20 CSR smoking machine working under conditions recommended by the U.S. Federal Trade Commission (FTC). The nicotine levels for the cigarette butts from the smokers were used to normalize the level of exhaled smoke condensate to that of the FTC smoking conditions. The smoke condensates from exhaled smoke as well as that from the machine smoking were analyzed by a gas chromatographic technique with mass spectral peak identification. The retention efficiency for 160 compounds was calculated from the ratio of the compound peak areas in the exhaled smoke (normalized by the corresponding butt nicotine level) vs. the areas of the corresponding peaks from the chromatogram of the smoke generated by the smoking machine. In the calculation of the results, it was assumed that the composition of mainstream smoke remains practically constant at different smoking regimes. All compounds found in the machine-generated smoke were also present in the exhaled smoke, but at different levels. About one third of the compounds were retained more than 66% by the smoker. Another third of the compounds were retained between 33% and 66%, and the rest of the compounds were retained very little from the mainstream particulate-phase of the cigarette smoke. The compounds retained more than 66% were in general compounds with lower molecular weight and with higher water solubility, which eluted first from a 5% phenyl dimethyl-polysiloxane (DB-5MS) chromatographic column. The compounds retained less than 33% from smoke were those with higher molecular weights and boiling points, which had longer elution times from the chromatographic column. These compounds consisted mainly of long-chain hydrocarbons (saturated or squalene type) and phytosterol-type compounds. The compounds retained between 33% and 66% had intermediate chromatographic retention times. No attempt was made to evaluate or identify new compounds formed in the exhaled smoke. The results were obtained from a limited number of subjects, but among these the retentions for individual compounds did not show large differences, indicating that the retention process is not very different for the subjects evaluated. An attempt was made to verify whether or not the retention of compounds by the smoker is analogous to a distribution process. Only weak correlations were obtained between the human retention and octanol/water partition coefficients or between the human retention and the chromatographic retention times of individual compounds.
When smoked by the Federal Trade Commission (FTC) method, the standard butt length for filtered cigarettes is specified as tipping plus 3 mm. One of the criticisms of this standard is that the tipping overlap hides some of the tobacco column and that consumers actually smoke cigarettes past the tipping.
The objective of this study was to determine how consumers actually smoke their usual brand when smoking in their everyday environment. A portable device was designed to collect and preserve cigarettes from consumers after smoking. In use, the smoldering cigarette is dropped into the device and it is closed. Upon closing, the cigarette is extinguished, the mouth end of the filter is cut and separated for further analysis, and the date and time are recorded.
Fifty adult smokers per brand were recruited across 5 US cities (10 smokers/city). A wide range of brands was studied: menthol and non-menthol, 1 mg to 18 mg FTC ‘tar’ yield, 17 to 25 mm circumference, and both 85 and 100 mm lengths. A total of 10528 cigarettes from 803 subjects covering 17 brands was measured.
The subjects were provided with one pack of their usual brand, as well as a collection device, and were instructed on how to use the device. The devices were collected on subsequent days. The cigarettes were then removed and the distance from the tipping to the char line was measured. The overall median butt length was tipping plus 6.7 mm with an overall average of tipping plus 8.4 mm. There was no significant effect of FTC ‘tar’ yield on either mean (p = 0.72) or median (p = 0.92) butt length.
Methods based on the analyses of cigarette filters have been used to estimate ‘tar’ and nicotine yields to smokers. These methods rely on the measurement of filtration efficiencies (FEs). However FEs may be influenced by both cigarette design features e.g., type of filter and levels of filter ventilation, and human smoking behaviour factors such as puff flow-rates and cigarette butt lengths. Two filter analysis methods are considered in our study. One is based on the analysis of whole filters using average values of FEs obtained from a range of machine smoking regimes. The other, a ‘part filter’ method, analyses a 10 mm section from the mouth end of the filter where the FE remains relatively constant irrespective of puff flow rates and butt lengths. Human puffing behaviour records were obtained from 10 smokers, each smoking six commercial cigarettes ranging from 1 mg to 12 mg ‘tar’ yields [International Standard (ISO) values]. These records were used to drive a human smoke duplicator and the resulting ‘tar’ and nicotine yields obtained from duplication were compared with the estimates obtained from ‘whole’ and ‘part filter’ analysis. The results indicated that whilst both filter methods gave good correlations with nicotine and ‘tar’ yields obtained from smoke duplication, the ‘part filter’ method was less susceptible to the effect of nicotine condensation and changes in FEs and hence gave a more accurate assessment of yields than the ‘whole filter’ method.
FK St. Charles, M Ashley, CJ Shepperd, P Clayton and G Errington
The analysis of spent filters from human-smoked (HS) cigarettes has been used to estimate cigarette yields for over three decades. Until recently, the whole filter was used for estimation; however a part-filter method has been shown to improve the accuracy of estimated HS yields. The part-filter method uses only the mouth-end portion of the filter, downstream of the ventilation holes, for analysis. In this portion, the filtration efficiency is relatively constant irrespective of typical puff flow rates of humans and also minimizes butt length effects (e.g. nicotine condensation) on filtration efficiency. Therefore, the estimations of HS cigarette yields are more robust to human smoking conditions than previous whole-filter methods.
British American Tobacco has adopted this method to obtain better understanding of how smokers actually use their products in their everyday environment. This can give information to help understand approaches to harm reduction. Since adopting this method, modifications and quality control features have been added to improve the accuracy of the estimation. This paper will describe in detail the methodology currently in use, along with sources of error, storage studies, quality control, repeatability and reproducibility.