Population characteristics and cigarette yield as determinants of smoke exposure

Relationships of population characteristics, smoking history, and cigarette yield with smoke exposure as measured by peripheral blood concentrations of thiocyanate, carboxyhemoglobin, nicotine and cotinine were sought in 170 male smokers. This population of smokers had significant elevations of serum thiocyanate, blood carboxyhemoglobin and plasma nicotine and cotinine concentrations as compared with an equal number of age- and sex-matched nonsmokers and these concentrations correlated significantly with past 24-hour cigarette consumption. Although the nicotine yield of the cigarette correlated significantly with plasma cotinine and marginally with plasma nicotine, the reduction in plasma nicotine and cotinine was not proportionate to the reduced yield of the cigarettes, suggesting that smokers partially compensate for the lower yields of their cigarettes. Blood levels of carboxyhemoglobin, nicotine and cotinine were also significantly associated with the weight of the subjects, presumably due to the relationship between weight and the volume of distribution. Univariate and multiple regression analyses provided evidence that coffee and alcohol consumption and years smoked also may be important determinants of smoke exposure.     

Can cigarette size and nicotine content influence smoking and puffing rates?

The stimuli controlling the rate at which people smoke cigarettes have not been clearly defined. On the hypothesis that smoking is basically nicotine-seeking behavior. nicotine available to the subject was experimentally manipulated through controlling cigarette size and nicotine content. In Experiment I, subjects given their own cigarettes in whole, half, quarter, and eighth lengths, increased the number of cigarettes smoked and number of puffs to compensate for reductions in size. Satisfaction was directly related to cigarette length. In Experiment II, subjects given special cigarettes delivering 0.2 or 2.0 mg nicotine/cigarette smoked significantly more of the low than of the high nicotine cigarettes and took significantly more puffs. As in Experiment I, significantly more quarter length than full length cigarettes were smoked, but total number of puffs did not differe. These results support the hypothesis that nicotine controls smoking behavior.     

Effects of smoking abstinence and chain-smoking on puffing topography and diurnal nicotine exposure.

Effects of chain-smoking, a 15-h smoking abstinence, and the nicotine yield of cigarettes on puff indices were studied in eight healthy smokers by using a controlled crossover study design. Puff parameters were measured puff by puff with a portable measuring device when 10 or 20 cigarettes, with nicotine yields of 0.3 and 1.0 mg, were smoked per day. The interval between sessions was 1 h, and the 20 cigarettes per day were chain-smoked 2 at a time. Serum cotinine indicated that smokers compensate completely for the lower nicotine delivery from the 0.3-mg cigarette. Smokers almost doubled total puff volume per cigarette and per day mainly by taking more puffs from the low-nicotine cigarettes and slightly prolonging puff duration. However, nicotine deprivation and chain-smoking had a relatively minor effect on puffing indices with both brands, a fact that agrees poorly with the nicotine titration hypothesis. However, in the course of every single cigarette of the day smokers significantly reduced puff duration and puff volume toward the end of the cigarette, which probably involves satiation of the nicotine crave but may also be due to changes in taste of the smoke.     

Plasma nicotine and cotinine in tobacco smoke exposed beagle dogs

Nicotine and cotinine have been determined in plasma samples from 87 beagle dogs chronically exposed to cigarette smoke with three different levels of nicotine. An additional 18 sham-exposed animals were included in the study as controls. Smoke was administered to the animals through permanent tracheostomas via cuffed tracheostomy tubes and was generated from reference cigarettes under standard puffing parameters by ADL-II smoking machines. The dogs were exposed for an average of 2 years prior to sample collection. The results from blood samples collected at specific intervals in the daily exposure schedules indicate that nicotine may be useful as a relative index of smoke exposure. At elevated exposure levels, average blood concentrations were related to the number of cigarettes smoked as well as the nitocine delivery of the cigarette. Cotinine was found to increase more slowly than nicotine and was also metabolized more rapidly than in humans. Overall, the study affords an examination of the relationship of plasma nicotine and cotinine with estimated nicotine exposure.     

Long-term effects of switching to cigarettes with lower tar and nicotine yields

On switching to cigarettes with lower tar and nicotine yields, most individuals smoke more intensively, but it is not clear if this effect persists over a long period. Smoking behaviour was monitored in 10 male and 18 female volunteers at five monthly visits, smoking commercially available cigarettes (tar yield>10 mg), then for six more visits at 6-week intervals after switching (mean reduction of 5.9 mg tar and 0.45 mg nicotine). Puffing behaviour was monitored with a flow sensing holder, and measurements were made before and after smoking of plasma cotinine, carboxyhaemglobin and alveolar carbon monoxide. After switching, cotinine levels only fell 40% of that predicted from the fall in nicotine yields, and there were no systematic trends for the rest of the study. Puff volumes rose (reflecting perhaps the reduced draw resistance of the lower yield cigarettes), and remained higher thereafter. The number of puffs per cigarette appeared to rise on switching, but then decreased again. In conclusion, most effects of switching to lower yield cigarettes appeared to persist for at least 36 weeks, suggesting that the strategy of reducing exposure to cigarette smoke by lowering tar and nicotine yields may be of limited value.     

Good relationship between saliva cotinine kinetics and plasma cotinine kinetics after smoking one cigarette

This study investigated the relationship between plasma and saliva cotinine kinetics after smoking one cigarette and the relationship between cotinine kinetics and estimated nicotine intake, which was calculated as mouth level exposure (MLE) of nicotine, from smoking two test cigarettes with different nicotine yields. This study was conducted in 16 healthy adult Japanese smokers, who did not have null nor reduced-activity alleles of CYP2A6, with a quasi-randomized crossover design of smoking a low-tar cigarette or a high-tar cigarette. Saliva cotinine showed similar concentration profiles to plasma cotinine, and all of the calculated pharmacokinetic parameters of cotinine showed the same values in plasma and saliva. The C_max and AUC of cotinine showed almost the same dose-responsiveness to the estimated MLE of nicotine between plasma and saliva, but the t_max and t_1/2 of cotinine were not affected by the estimated MLE of nicotine in either plasma or saliva. The results show that saliva cotinine kinetics reflects plasma cotinine kinetics, and measurement of saliva cotinine concentration gives the same information as plasma cotinine on the nicotine intake. Thus, saliva cotinine would be a good and less-invasive exposure marker of cigarette smoke, reflecting the plasma cotinine concentration and kinetics.     

The effect of menthol containing cigarettes on adult smokers’ exposure to nicotine and carbon monoxide

There is limited information comparing biomarkers of exposure (BOE) to cigarette smoke in menthol (MS) and non-menthol cigarette smokers (NMS). Objective: To compare BOE to nicotine and carbon monoxide in MS and NMS. Methods: Cross-sectional, observational, ambulatory, multi-centre study in 3341 adult cigarette smokers. Nicotine equivalents (NE) in 24 h urine, NE/cigarette, COHb and serum cotinine were measured. Statistical analyses included analysis of variance and Wilcoxon test. Results: Analyses of variance revealed no statistically significant effects of mentholated cigarettes on NE/24 h, COHb, serum cotinine and NE/cigarette. On average MS smoked 15.0 and NMS 16.8 cigarettes/day. The unadjusted mean differences were as follows: MS had lower NE/24 h (5.4%) and COHb (3.2%), higher serum cotinine (3.0%) and NE/cigarette (5.7%) than NMS. African-Americans MS smoked 40% fewer cigarettes, showed lower NE/24 h (24%) and COHb (10%) and higher NE/cig (29%) and serum cotinine (8%) levels than their White counterparts. Conclusions: Smoking mentholated cigarettes does not increase daily exposure to smoke constituents as measured by NE and COHb. These findings are consistent with the majority of epidemiological studies indicating no difference in smoking related risks between MS and NMS.     

Cigarette filter vent blocking: effects on smoking topography and carbon monoxide exposure

Two studies were conducted using smokers of unventilated cigarettes to determine the effects of filter vent blocking on smoke exposure (Experiment 1) and smoking topography (Experiment 2). In both studies, subjects were exposed to ultra low yield cigarettes that had 0%, 50%, and 100% of their filter vents blocked with tape. In Experiment 1, carbon monoxide (CO) exposure from eight 60 ml puffs increased in an orderly fashion as a function of filter vent blocking. By blocking filter vents, smoke was no longer diluted with air as it passed through the filter, and hence, exposure to smoke constituents was increased. In Experiment 2, when puff and inhalation parameters were allowed to vary, subjects took significantly more puffs, and larger puffs from unblocked cigarettes than from completely blocked cigarettes, but CO exposure from the completely blocked cigarette was double that from the unblocked cigarette (8.96 ppm vs. 4.32 ppm). The increased number and volume of puffs taken from ultra low yield cigarettes with unblocked filter vents may be due to changes in physical characteristics of the cigarette, and not to smokers actively compensating for reduced smoke constituent yields.     

Inhalation bioassay of cigarette smoke in rats

Groups of 80 female rats were exposed to cigarette smoke from three types (code 13 = high tar, low nicotine; code 27 = low tar, medium nicotine; code 32 = high tar, high nicotine) of cigarettes in Maddox-ORNL smoking machines, eight cigarettes per day, 7 days per week, for up to 24 months. An additional group received sham exposures and a fifth group served as untreated controls. The sham-exposed animals had significantly lower body weights than the untreated controls. The smoke-exposed animals had significantly lower weights than the sham-exposed controls; the weights were lower for the code 27 and code 32 animals than for the code 13 animals during the second year of exposure. The survival of the code 13 animals was similar to that for the sham-exposed and untreated control group; survival times of the code 27 and code 32 animals were shorter. Body weight and survival reflected the high- and low-nicotine dose groups indicated by in vivo dosimetry measurements. Smoke-induced histopathologic lesions consisted primarily of pulmonary smoke granulomas; the smoke granulomas were less severe in the code 27 exposure group than in the groups exposed to smoke from code 13 or code 32 cigarettes. Additional changes included pulmonary alveolar epithelial hyperplasia, and squamous metaplasia and basal cell hyperplasia of laryngeal and tracheal epithelium. One primary epidermoid carcinoma was found in the lung of a code 27 rat. The rats tolerated the chronic exposures relatively well and certain of the smoke-induced lesions allowed differentiation between the different types of cigarettes.     

Clove cigarette smoking: biochemical,physiological, and subjective effects

Alternative tobacco products such as clove (kreteks) and bidi cigarettes have become increasingly popular among US smokers. The nicotine content of a popular clove cigarette (Djarum Special) filler averaged 7.4 mg; conventional cigarettes contained 13.0 mg. However, smoke yields from standardized machine-smoking analysis indicated it delivered more nicotine, carbon monoxide (CO), and tar than conventional cigarettes. In a clinical study, nicotine delivery, physiologic, and subjective effects of the clove cigarette were compared to their own brand of cigarette in 10 adult smokers (7 males). Average time to smoke the clove cigarette (549 s) and number of puffs (15.1) were significantly greater than own brand (314 s and 9.4 puffs). Increases in venous plasma nicotine and exhaled CO after smoking the clove cigarette (17.4 ng/ml; 6 ppm) were similar to those after own brand (17.6 ng/ml; 4.5 ppm). Maximal changes in heart rate (HR), systolic, and diastolic blood pressures (BP) did not differ significantly between the clove and own brand of cigarette. Compared to their own brand of cigarette, the clove cigarette was rated as better tasting and being distinctly different. Our findings indicate that clove cigarettes deliver significant quantities of nicotine, CO, and presumably other toxic components of tobacco smoke. Taste satisfaction, aromatic odor, and novelty may contribute to their appeal to young smokers.     

Effects of a nicotine-enriched cigarette on nicotine titration,daily cigarette consumption,and levels of carbon monoxide,cotinine, and nicotine

To test whether cigarettes with low tar, low carbon monoxide, and medium nicotine yield produce less dangerous effects than cigarettes low in tar and CO but high in nicotine, 12 subjects were recruited to smoke nicotine-enriched cigarettes. The subjects smoked three types of cigarettes in the three experimental conditions: (1) their own brand; (2) cigarettes with 4.8 mg tar, 4.0mg CO, and 0.5 mg nicotine; (3) cigarettes with 5.8 mg tar, 4.1 mg CO, and 1.1 mg nicotine. Subjects monitored their daily consumption for 12 weeks; 4 weeks for each condition. During laboratory visits, the subjects smoked a cigarette while their heart rate and carbon monoxide in expired air were measured pre- and post-smoking. A blood sample was drawn and analyzed for nicotine and cotinine in each experimental condition. No significant differences in daily cigarette consumption were found, although a trend (P<0.07) in the direction of fewer nicotine-enriched cigarettes per day was found. Levels of CO varied significantly among the three conditions: The subjects' own brands yielded the highest level, while the nicotine-enriched cigarette yielded the lowest level. No differences were found for nicotine or cotinine levels. A second purpose of the experiment was to record the degree of nicotine titration displayed by individual smokers, tar and CO levels remained constant in the experimental cigarettes. No general titration effect was observed, although for daily consumption it approached significance. When the subjects' nicotine dependence, measured with a tolerance questionnaire, was taken into acount, a correlation with daily consumption was found (r=77, P<0.005). A cigarette with low tar and CO, but medium to high nicotine yield, would seem to produce less hazardous effects and is worthy of further investigation. The controversial question of whether smokers titrate for nicotine is a function of the individual's nicotine dependence.     

Levels of cigarette availability and exposure in black and white women and efficient smokers

Purposes of this investigation were to examine differences in smoke exposure and smoking topography across three smoking conditions: usual number of cigarettes, restricted (50%) and increased (167%) simulating restricted and unrestricted cigarette availability. A repeated-measures counterbalanced design with a sample of 25 women (13 African Americans; 12 Caucasians) was implemented with a 6-day inpatient protocol conducted in the General Clinical Research Center (GCRC). There were significantly larger percentage increases in carbon monoxide (CO) postcigarette in the restricted condition compared to usual and increased condition. Women with baseline cotinine/cigarette ratios >20 ng/ml/cigarette, considered efficient smokers, had significantly higher CO increases postcigarette at baseline than participants with lower cotinine/cigarette ratios, yet increased this exposure further during the restricted condition. Efficient smokers had significantly higher nicotine boost in the restricted condition compared to less efficient smokers. Differences by ethnicity were also noted with significantly higher CO percentage increases pre- to postcigarette in African Americans across all conditions, compared to Caucasians. Levels of smoke exposure postcigarette in persons who reduce cigarettes per day in response to restricted cigarette availability may be substantial.     

Discriminability of nicotine in tobacco smoke: Implications for titration

Cigarette smokers were presented with puffs from either high (2.5 mg), medium (1.5 mg) or low (.5 mg) nicotine cigarettes in order to determine their ability to discriminate nicotine delivery in tobacco smoke. Puffs were presented in random order during each of two conditions and tar content was controlled by using research cigarettes and a smoke mixing device that varied only nicotine. The first condition allowed olfactory stimuli to be used in discrimination, while the second condition blocked olfaction by occluding subjects' nostrils. In both conditions, subjects discriminated between the nicotine content of different puffs, with higher nicotine puffs rated as significantly stronger (by roughly 50%). Subjective desirability ratings did not vary with nicotine delivery. The implications of the magnitude of change in subjects' ratings for theories of nicotine titration are discussed.     

The effects of a restricted feeding regimen on cigarette smoking in humans.

The effects of 3 days of restricted feeding (800 kcal/day) on cigarette consumption, smoke exposure, and mood were studied in five male research volunteers. A within-subjects design was used in which subjects were exposed in an inpatient research unit to either a nutritionally-balanced diet containing 800 kcal (RESTRICTED DIET) or 3,000 kcal (NORMAL DIET) per day for 3 consecutive days. At least 2 weeks separated diet conditions. Dependent measures included number of cigarettes smoked per day in each diet condition, biological exposure levels (carbon monoxide and plasma cotinine levels), and mood. Number of cigarettes smoked per day did not differ significantly across diet conditions. Biological exposure to carbon monoxide and to cotinine, a metabolite of nicotine indicative of chronic nicotine exposure, also did not differ significantly between conditions. Fatigue scores from the Profile of Mood States were significantly elevated in the RESTRICTED DIET condition. Not surprisingly, subjects in this condition also reported feeling more hungry throughout the day than in the NORMAL DIET condition. From our study results, we conclude that a short period of "dieting," and the resulting hunger elicited from such a diet, do not increase cigarette consumption or smoke exposure in humans.     

Smoking Topography in a Nonlaboratory Environment

The relationships between the number of cigarettes smoked/day and the number of puffs/cigarette, puff duration, and total puff time/cigarette were studied. Data were collected on 12 regular smokers for all cigarettes smoked over a 3-day period in a nonlaboratory environment. Between-subject variability was substantial on each of the topographical measures. Neither the number of cigarettes smoked per day nor the classification of Heavy (> 25 cigarettes/day) vs Moderate (< 25 cigarettes/day) smoking levels was related to the intensity with which cigarettes were smoked. Within-subject consistency on the topography measures indicates that smokers may have relatively unique smoking patterns.

Most studies of smoking in the natural environment employ number of cigarettes/day as their estimate of smoke exposure. However, total smoke exposure is determined by an interaction of various topographical features, including frequency (number of cigarettes/day, number of puffs/cigarette), durational (puff duration, interpuff interval, intercigarette interval), and volumetric (puff volume, inhalation volume) components. Employing cigarettes/day to estimate smoke exposure assumes a consistent relationship between cigarettes/day and other topographical features which contribute to total smoke exposure, but it is not clear that such a relationship exists. Laboratory studies of smoking behavior have found that cigarette frequency may vary independently of these other topographic components of smoking, lichtenstein and Antonuccio (1981) examined smoking topography in 24 male smokers while they smoked a cigarette during two 45-minute sessions. They found that cigarette rate was significantly related to intercigarette interval, but not to puff frequency, puff duration, cigarette duration, and amount of tobacco burned.

Results found in laboratory settings, however, have been found not to necessarily generalize to nonlaboratory environments. For example, OssipKlein, Martin, Lomax, Prue, and Davis (1983) examined six subjects smoking adlib in three settings: natural, clinical, and laboratory. They found that cigarette durations were shorter and that subjects took significantly longer and more puffs in a clinical or laboratory setting compared to a naturalistic setting. Thus, examination of the relationship between topographical features in naturalistic smoking would appear to require direct study outside the laboratory.

The present study is to our knowledge the first to examine topographical features of smoking and the relationship between number of cigarettes smoked/ day and other measures of smoking topography while the subject smoked ad-lib in a nonlaboratory environment. This information would potentially be important in examining the extent of individual differences in smoking topography, in assessing the extent to which cigarettes/day is related to other aspects of smoking behavior, and in determining whether categorizing smokers into smoking groups (e.g., moderate and heavy) on the basis of number of cigarettes/day accurately reflects the amount of total smoke exposure/day.     

Effect of cigarette design on biomarkers of exposure,puffing topography and respiratory parameters

Abstract

Despite the lack of evidence, many reports exist which have implied that smokers inhale low-yield cigarette smoke more deeply than that of high-yield cigarettes. The objective of this study was to investigate the effect of short-term switching between smoker’s own brand and test cigarettes with different smoke yields on puffing topography, respiratory parameters and biomarkers of exposure. Participants were randomly assigned to smoke either a Test Cigarette-High Tar (TCH), for two days, and then switched to a Test Cigarette-Low Tar (TCL), for two days or the reverse order (n?=?10 each sequence). Puffing topography (CReSS microdevice), respiratory parameters (inductive plethysmography) and biomarkers of exposure (BOE, urinary nicotine equivalents – NE and blood carboxyhemoglobin – COHb) were measured at baseline and on days 2 and 4. The average puffs per cigarette, puff volume and puff durations were statistically significantly lower, and inter-puff interval was significantly longer for the TCH compared to the TCL groups. Respiratory parameters were not statistically significantly different between the TCH and TCL groups. Post-baseline NE and COHb were statistically significantly lower in the TCL compared to the TCH groups. Under the conditions of this study, we found no indication of changes in respiratory parameters, particularly inhalation time and volume, between study participants smoking lower versus higher yield cigarettes. Likewise, the BOE provides no indication of deeper inhalation when smoking low- versus high-yield cigarettes. These findings are consistent with the published literature indicating smoking low-yield cigarettes does not increase the depth of inhalation.     

Nicotine yield as determinant of smoke exposure indicators and puffing behavior.

Relationships between machine smoking nicotine yield and different smoke exposure indicators were investigated in a cross-sectional study. For each of the four yield classes H (1.0-1.2 mg), M (0.7-0.9 mg), L (0.4-0.6 mg) and U (0.1-0.3 mg) 18 male and 18 female subjects were recruited. The experimental design (2 x 2) included smoking with lip contact or with a flowmeter holder, natural smoking of one cigarette or forced smoking (30 puffs). The analysis of presmoking measures revealed for plasma nicotine H greater than L, U; M greater than U, for plasma cotinine H, M greater than U, and no differences for respiratory CO. Pre- to postsmoking boosts of CO and nicotine increased with yield, but the differences were smaller than those in yield. This partial compensation can be attributed to puffing behavior as revealed by the differences between yield classes with respect to flowmeter measures (puff volume, flow parameters, number of puffs). Contact condition hardly influenced the results. Forced puffing revealed down regulation mechanisms in smoke absorption and, less pronounced, in puffing behavior. Cardiovascular and subjective effects were widely independent of yield. Plasma cotinine appeared as the best smoke exposure indicator, due both to its high retest reliability and its relationship to nicotine yield.     

Cigarette smoke inhalation and blood dose markers in beagle dogs

The time course of three tobacco-related blood dose markers was determined in beagle dogs during and after two-, four-, and six-cigarette acute smoke exposures. Venous blood samples were taken from a jugular catheter at selected intervals and analyzed for nicotine, cotinine, and carboxyhemoglobin (COHb). Smoke was generated from reference cigarettes (1.91 mg of nicotine) by a machine and delivered to the trachea of tracheostomized dogs. Cigarettes were chain-smoked in pairs with a 5-min break between pairs when four or six cigarettes were smoked. Blood nicotine, cotinine, and COHb levels all rose during smoke inhalation. Peak values of COHb were dosimetrically related to the number of cigarettes, while peak nicotine and cotinine values were not related consistently. The exposure protocol used in this study produced blood levels of all three measured parameters which were in the range of published values for human smokers, so that it is possible to approximate acute human cigarette smoke inhalation in the beagle dog model.     

Human Smoking Patterns and Smoke Deliveries

This study, based on a sample (N = 517) of adult medical patients at a southeastern medical center who were current users of cigarettes, reports the interrelationships among the puff characteristics of cigarette smoking behavior and smoke deliveries of tar and nicotine. Average puff duration, average puff volume, and the number of puffs were found to be significantly positively correlated with daily tar and nicotine intake. Intervals between puffs and total time smoking were not correlated with nicotine and tar intake. It was concluded that “how” a person smokes affects “how much” this person is exposed to tar and nicotine.     

Effects of smoking abstinence and nicotine abstinence on heart rate,activity and cigarette craving under field conditions

In a field study heart rate, activity, cigarette consumption, craving for cigarettes, saliva cotinine and subjective ratings were assessed in 12 female subjects, smoking medium tar/medium nicotine cigarettes (TN). The habituated cigarettes were compared with a nearly nicotine-free/medium tar (0·08 mg/9·3 mg) cigarette ( Tn ) and with abstinence. Two recording periods of 3 days each were conducted in two consecutive weeks. Heart rate was highest with the Tn cigarettes, 8 bpm lower on abstinence days and in between with the Tn cigarettes. A characteristic increase in heart rate and activity before cigarette lighting appeared with the TN and the Tn cigarettes and with button pressing indicating smoking desire on abstinence days. This response is attributed to an anticipative activation preceding lighting a cigarette. Subjective ratings assessing the craving to smoke differed between abstinence and the smoking condition but not between the two cigarette types, whereas saliva cotinine was significantly higher with the TN than with the Tn cigarettes or abstinence. Cigarette consumption was similar with both cigarette types, but taste and strength were rated better for the TN than the Tn cigarettes. It is concluded that heart rate and saliva cotinine depend on the amount of nicotine absorbed, whereas subjective craving is reduced by smoking independently of the actual nicotine yield of the cigarette.