Spontaneous cigarette brand switching: consequences for nicotine and carbon monoxide exposure.

A group of smokers who had participated in smoking-related studies three to six years earlier were re-studied to assess changes in their smoking practices. Individuals who smoked the same brands of cigarettes showed no change in plasma cotinine (reflecting exposure to nicotine) or expired carbon monoxide (CO) concentration. Those who switched to cigarettes of lower nicotine yield (average decrease 38 per cent) showed reduced plasma cotinine concentrations, due primarily to smoking fewer cigarettes per day. The intake of nicotine per cigarette was not different. Subjects who smoked cigarettes of higher yield (102 per cent increase) had higher cotinine and CO levels, due to greater intake per cigarette.     

Nicotine yield and measures of cigarette smoke exposure in a large population: are lower-yield cigarettes safer?

We examined the relationship of machine-estimated nicotine yield by cigarette brand with the level of cigarette consumption and two biochemical measures of smoke exposure (expired-air carbon monoxide and plasma thiocyanate) in a large, population-based sample of smokers (N = 713). The lower the nicotine yield of the cigarette, the greater the number of cigarettes smoked per day. Prior to adjusting for number of cigarettes smoked per day, nicotine yield was not related to the actual measures of smoke exposure. Smokers of ultralow-yield cigarettes had laboratory tests of smoke exposure which were not significantly different from those of smokers of higher-yield brands. Only after adjustment for number of cigarettes smoked per day did nicotine yield become significantly related to expired-air carbon monoxide and to plasma thiocyanate. In multivariate analysis, the number of cigarettes smoked per day accounted for 28 per cent and 22 per cent of the variance in observed expired-air carbon monoxide and plasma thiocyanate levels, respectively, whereas nicotine yield accounted for only 1 per cent and 2 per cent of the variance, respectively. The relative lack of an effect of nicotine yield on the biochemical measure appears to be due to the fact that smokers of lower nicotine brands smoked more cigarettes per day, thereby compensating for reduced delivery of smoke products. Our data do not support the concept that ultralow-yield cigarettes are less hazardous than others. Machine estimates suggesting low nicotine yield underrepresent actual human consumption of harmful cigarette constituents.     

Smoking cessation program: baseline carbon monoxide and serum thiocyanate levels as predictors of outcome

One hundred and sixty-two smokers who participated in an aggressive smoking cessation program underwent analysis of expired air carbon monoxide (CO) and serum thiocyanate (SCN) at entry and one year later. Persons who failed to quit smoking had higher baseline CO and SCN and smoked more cigarettes per day than did those who succeeded in quitting. The use of CO, SCN, number of cigarettes smoked, age, and blood pressure at baseline permitted accurate classification of over 70 per cent of the subjects into groups which would succeed and fail in their effort to quit smoking. Persons who failed to quit reduced the reported number of cigaretts smoked per day by one-third, but there was no corresponding reduction in CO and SCN, suggesting that self-reporting of a reduction in the number of cigarettes smoked may not lead to a corresponding decline in exposure.     

Smoking habits and blood carbon monoxide levels

The carboxyhemoglobin concentrations (COHb) of 97 meat porters, 77 office workers, and 200 pregnant women have been determined. Individuals were questioned on smoking habits including numbers normally smoked per day, numbers already smoked on day of sampling, and time since last cigarette. The number of cigarettes smoked per day appears to allow the best prediction of COHb concentration. Individuals whose occupation involved them in physical exertion (meat porters) accumulated less carbon monoxide (CO) for numbers of cigarettes smoked per day than individuals smoking whilst sedentary. Pregnant women were seen to accumulate CO in a similar way to the active meat porters. In all groups, smokers had significantly higher COHb concentrations than nonsmokers. The effects of activity on CO uptake and elimination are discussed in relation to cigarette smoking, and it is suggested that the effect of activity on COHb is related more to elimination in the nonsmoking periods rather than uptake in the smoking periods.     

Menthol vs nonmenthol cigarettes: effects on smoking behavior.

OBJECTIVES. The purpose of this study was to examine intraindividual differences in smoking behavior between smoking regular and mentholated cigarettes. METHODS. Healthy male smokers (n = 29) smoked either a regular or a mentholated cigarette in two separate sessions 1 week apart. Commercial brands with comparable tar, nicotine, and CO content were used. Smoking behavior was constrained by fixed 15-second interpuff intervals, but puff volume and number of puffs were unconstrained. RESULTS. When smoking the non-mentholated brand of cigarettes, participants smoked 22% more puffs and had 13% higher mean volumes per puff than they did when smoking the mentholated brand of cigarettes. The aggregate 39% excess exposure to cigarette smoke in the regular-cigarette condition was not accompanied by commensurate excesses in expired carbon monoxide or in physiological measures normally correlated with nicotine exposure. CONCLUSIONS. These findings parallel differences in physiological correlates of exposure to nicotine found in cross-sectional comparisons of African-American and White smokers and are consistent with the results of emerging laboratory investigations.     

Maintain levels of nicotine but reduce other smoke constituents: A formula for “less-hazardous” cigarettes?

Twenty-two volunteers who smoked more than 20 cigarettes with "high" nicotine yields (0.8 to 1.2 mg) per day participated in an 8-week study designed to test the hypothesis that smoking cigarettes with a constant level of nicotine but reduced deliveries of tar, carbon monoxide, and hydrogen cyanide leads to a decrease in smoke absorption. All subjects smoked their usual high-nicotine brand for the first 3 weeks (P1), and the absorption of smoke constituents was determined from levels of thiocyanate and cotinine in saliva and serum, levels of carbon monoxide in expired air, and levels of carboxyhemoglobin in the blood. During the final 5 weeks (P2), the treatment group (16 subjects) switched to the "light" version of their usual brands (similar yields of nicotine but with reduced yields of tar, carbon monoxide, and hydrogen cyanide); the control group (6 subjects) smoked their usual brands for the duration of the study. Average levels of cotinine for the subjects who switched during P2 were not significantly different from those of the control group as was expected. Slight reductions were noted in average expired-air carbon monoxide levels, blood carboxyhemoglobin, and saliva thiocyanate, but these reductions were smaller than anticipated based on brand characteristics. The results suggest that the ratio of smoke constituents is different when individuals, rather than machines, smoke cigarettes. Yields determined under subject-defined conditions are necessary in order to properly evaluate the role of nicotine in the design of "less-hazardous" cigarettes.     

Cigarette smoking and birthweight: type of cigarette smoked and a possible threshold effect

The effects on birthweight of the number of cigarettes smoked and their tar, nicotine and carbon monoxide yields were investigated prospectively in 1309 pregnant women of whom 414 were smokers. Several approaches to modelling the effect of smoking were tried. These suggested that while both yield and quantity smoked were important, yield had the greatest effect. This led to an empirical approach whereby consistent smokers were divided into four categories according to whether they smoked a low or high quantity of cigarettes per day and whether they smoked low or high yield cigarettes. Using these four groups it emerged that women smoking a low quantity of low yield cigarettes had babies of a similar mean birthweight to those of non-smokers whereas those smoking a low quantity of high yield cigarettes had babies whose birthweight was reduced to the same degree (6% or more) as those of mothers who smoked higher quantities. This apparent threshold was estimated as 13 cigarettes/day and 15 mg/cigarette carbon monoxide. We conclude that brand smoked is at least as important as quantity and that in this population there is evidence for a threshold for tobacco smoke intake below which no discernible effect on birthweight is seen.     

Estimates of maximum or average cigarette tar, nicotine, and carbon monoxide yields can be obtained from yields under standard conditions

Average yields of tar, nicotine, and carbon monoxide per liter of smoke and per cigarette were determined for 10 brands of cigarettes smoked under 27 different conditions (one standard and 26 nonstandard). Per cigarette yields were highly variable across smoking conditions due to differences in the total volume of smoke taken for analysis. The results of a simple linear regression analysis indicated that up to 95% of the variation in tar yield per cigarette could be explained by variations in the total volume of smoke produced per cigarette. Per liter yields for tar, nicotine, and carbon monoxide were almost constant over the conditions investigated. Since most smokers inhale less than this amount, yields per liter provide a rough estimate of the maximum amount to which a smoker might be exposed. Yields per liter, taken over all 26 conditions, are highly correlated with per cigarette yields under standard conditions. Consequently, values on one scale can be converted to the other, at least for the 10 brands investigated. The average conversion factor for tar, nicotine, and carbon monoxide is 2.5 when proceeding from milligrams per king-size cigarette under standard conditions to milligrams per liter. This relationship is true for both vented and nonvented cigarettes when ventilation holes are not blocked.     

Reported cigarette smoke values: a closer look.

Effects of mechanical compression of the filter tips and of blocking the air channels of a special filter design on the smoke yields of seven brands of commercial filter cigarettes were investigated. In addition, the influence of these variables on actual uptake of smoke constituents by smokers was studied with four subjects. Compression of filter tips produced major increases in smoke yields for the cigarette which features a filter tip with four longitudinal air channels at its periphery. Blocking of these air channels increased tar yields by 51 per cent, nicotine by 69 per cent, and carbon monoxide by 147 per cent. Subjects who smoked the cigarette with this special filter design tended to smoke fewer cigarettes per day than when they smoked cigarettes with perforated filter tips, yet their plasma cotinine levels were significantly higher. Blood pressure and pulse rate were markedly elevated after first exposure to smoke from the special filter cigarette, as were plasma nicotine levels. These results point out that individuals inhale different quantities of smoke constituents from cigarettes with reportedly similar smoke yields according to Federal Trade Commission methods. A redefinition of "average" smoking parameters readjustment of standard laboratory methodology are suggested.     

Dependency, social factors, and the smoking cessation process: the doctors helping smokers study

We analyzed data obtained from a representative sample of the smoking patients (n = 1,338) of 66 family physicians to determine predictors of attempts to stop smoking, desire to quit smoking, and successful smoking cessation. Compared to subjects who made no attempt to quit smoking, subjects who tried to quit smoking tended to be younger, had tried to quit smoking in the year prior to the study, waited longer before smoking their first cigarette of the day, had more desire to quit smoking, and had more social support for quitting. Education and cigarettes smoked per day were not independently related to the subject making a quit attempt. Desire to quit smoking was associated with an attempt to quit in the year prior to the study and social support for smoking cessation (support of spouse, second most important social contact, and physician). Desire to quit smoking was not independently related to age, education, or dependency on cigarettes (measured by the number of cigarettes smoked per day and the length of time a subject waited before smoking the first cigarette of the day). Compared to subjects who tried to quit and failed, subjects who succeeded were older, smoked fewer cigarettes per day, and waited longer to smoke their first cigarette of the day. Spouse support, support of the second most important social contact, and advice of a doctor to quit smoking were not independently related to whether or not a cessation attempt would be successful. These data suggest that successful smoking cessation requires two components: social support to make an attempt to quit and the ability to overcome dependency on cigarettes to make the attempt successful.     

A comparison of the yields of tar, nicotine, and carbon monoxide of 36 brands of Canadian cigarettes tested under three conditions

A number of countries, including Canada, sponsor routine monitoring of cigarette tar, nicotine, and carbon monoxide yields which are evaluated by cigarette-smoking machines according to a standard protocol. These standardized yields continue to decline as tobacco companies modify their brands to meet consumers' demand for "light" products. This trend toward cigarettes with low average deliveries of toxic substances may reduce health risks for some people. However, switching to low-yield cigarettes may not result in reduced risks for smokers who smoke these cigarettes intensively. Thirty-six brands of Canadian cigarettes, including 28 with ventilated filters, were tested under standard conditions and 2 others in order to determine how yields of tar, nicotine, and carbon monoxide change when cigarettes are manipulated by smokers in order to increase their smoke intake. While the rank order yields of tar, nicotine, and carbon monoxide was preserved, the average yields of all three substances more than doubled when cigarettes were intensively smoked in comparison with standard smoking.     

Pack size, reported cigarette smoking rates, and the heaviness of smoking

Three distinct samples show that pack size is highly associated with individual reports of daily cigarette intake, confirming an earlier report based on aggregate data. Those who report smoking 25 cigarettes per day (or who buy packs of 25) are heavier smokers than those who report smoking 20 cigarettes per day (or who buy packs of 20), as evidenced by greater likelihood of starting smoking earlier in the morning and by higher average levels of alveolar carbon monoxide. Categorizations based on number of cigarettes smoked per day should not assume that "one pack of twenties" is roughly the same as "one pack of twenty-fives." No conclusions can be drawn about whether the availability of larger packs promotes heavier smoking.     

Smoking Topography in Response to Denicotinized and High-Yield Nicotine Cigarettes in Adolescent Smokers

PurposeThe objective of this study was to explore the smoking topography of adolescent smokers. It is well established that the majority of adult nicotine-dependent smokers began smoking as adolescents. Whereas recent advances have been made with respect to identification of factors that predispose to nicotine dependence, very little is known about the actual smoking behavior (e.g., topography) of adolescent smokers, or its relationship to nicotine dependence. Correspondingly, the extent to which adolescent smokers smoke to obtain nicotine is also unknown.MethodsIn the present study, we assessed several topographical indices of smoking (e.g., puff volume, puff number) in a sample of 35 light, adolescent smokers. Moreover, we examined whether smoking behavior is different in response to smoking a denicotinized relative to a high-yield, nicotine cigarette.ResultsAll participants evidenced a significant increase in expired air carbon monoxide after the smoking of a cigarette. Results of independent-sample t-tests revealed that adolescents who smoked a low-yield nicotine cigarette took significantly more puffs per cigarette than did those who smoked a high-yield cigarette.ConclusionsThese findings suggest that adolescent smokers do titrate their nicotine intake in response to smoking denicotinized cigarettes, but do so not by taking larger puffs or smoking more quickly, but by simply taking more puffs per cigarette. Implications of the findings and future directions for this type of research with adolescents are discussed.     

Evidence for compensation in smokers of low yield cigarettes

To determine the relation of smoking low yield cigarettes (tar yield less than 15.0 mg and nicotine yield less than 1.0 mg per cigarette) to the number of cigarettes smoked per day, we analysed information provided on self-administered questionnaires by 7706 current, regular cigarette smokers. The mean age at starting to smoke and the mean number of years of smoking were not consistently different in smokers of low yield compared with smokers of high yield cigarettes. In contrast, at all ages in both men and women, smokers of low yield cigarettes smoked significantly more cigarettes per day than smokers of high yield cigarettes. The differences in the number of cigarettes smoked per day between smokers of low and high yield cigarettes were small--about 3 cigarettes per day in men and about 1 1/2 cigarettes per day in women. However, these small differences might translate to the smoking of as many as one billion more packs of cigarettes per year in the United States alone. The potential beneficial effect of the smoking of cigarettes whose yield per cigarette is lower must be weighed against a possible adverse effect of the smoking of more cigarettes if the relation between smoking low yield cigarettes and smoking more cigarettes is causal.     

Does switching from cigarettes to pipes or cigars reduce tobacco smoke exposure?

Cigarette smoking histories, reported depth of inhalation, number of pipe and cigars (PC) smoked, serum thiocyanate (SCN) and expired air carbon monoxide (CO) levels were examined in PC male smokers enrolled in the Multiple Risk Factor Intervention Trial (MRFIT). Serum SCN levels for all PC smokers were higher than for non-smokers and lower than for current cigarette smokers. Levels were related to the amount of product smoke. Prior cigarette smokers had higher SCN levels when compared to PC users who had never smoked cigarettes, smoked a larger number of tobacco products per day, and reported inhaling into the chest more often. Prospective data on baseline cigarette smokers demonstrated that smokers who stopped all tobacco products had a greater drop in SCN and CO than those who switched to PC. The findings strongly suggest that cessation of all tobacco products is the best strategy for decreasing exposure to tobacco smoke.     

Consumption of 'low-yield' cigarettes: its frequency and relationship to serum thiocyanate.

To determine the use and possible health risks of low-yield cigarettes, we ascertained the cigarette brands and serum thiocyanate (SCN) levels of 2,561 adult smokers (age 25-74) in population-based samples of seven upper Midwestern communities during 1980-82. Brands were coded according to December 1981 Federal Trade Commission (FTC) ratings for "tar", nicotine, and carbon monoxide (CO). Compared to 1980 data from the National Center for Health Statistics for the United States as a whole, a greater proportion of smokers in these communities smoked low-yield brands. More people with higher education than lesser and more women than men smoked low-yield cigarettes. Greater proportions of older people (65-75 years) than younger people (less than 65 years) smoked cigarettes in the highest and lowest brand yield categories. SCN, adjusted for number of cigarettes smoked and for sex, was only weakly associated with brand ratings for "tar" (r = +.12), nicotine (R = +.11), and CO (r = +.15). Furthermore, the gradient in SCN between lowest and highest quintiles of brand strength was less than 16 per cent--much lower than the 300-500 per cent gradient in smoke components implied by FTC ratings. These data add to the evidence that smoking low-yield cigarettes may not be significantly less hazardous than smoking high-yield brands.     

Gender differences in predictors for long-term smoking cessation following physician advice and nicotine replacement therapy.

We evaluated gender differences in demographic, smoking history, nicotine dependence, transtheoretical, and perceived stress variables as predictors of smoking cessation. Participants (n = 381) smoked at least 15 cigarettes per day and were motivated to quit. The outcome variable was 7-day abstinence at 1-year follow-up. Predictor variables included: age, education level, number of years smoking, cigarettes per day, quit attempts, nicotine dependence, stage of change, decisional balance, processes of change, self-efficacy, and perceived stress. Logistic regression analysis was used to derive predictive models for women and men. In women, lower scores for pre- and mid-treatment perceived stress significantly increased the likelihood of being abstinent at follow-up. For men, a higher level of education or number of quit attempts lasting > 24 hours in the past year, along with less frequent use of behavioural processes of change at baseline increased the probability of being abstinent at follow-up.     

Cigarette smoking and male lung cancer in an area of very high incidence. I. Report of a case-control study in the West of Scotland.

Altogether 656 male lung cancer cases and 1312 age and sex matched controls were interviewed between 1976 and 1981 in a case-control study of cigarette smoking habits and lung cancer in Glasgow and the West of Scotland, an area with the highest recorded incidence in the world. The relative risk of lung cancer increased significantly for smokers whose consumption was below 20 cigarettes per day but did not rise significantly in those who smoked more than 20 cigarettes per day. Other smoking characteristics such as inhalation and tar yields of brands smoked did not explain this finding. Additionally, the relative risks observed at all levels of cigarette consumption were low in comparison with those in the published literature. By constructing an index of cigarette exposure which included the tar yields of brands smoked, an assessment of the risk of lung cancer in relation to tar exposure independent of amount smoked was derived. Only in smokers of less than 15 cigarettes per day was there a statistically significant reduction in risk of lung cancer associated with lower levels of tar yield.     

The importance of tar and nicotine in determining cigarette smoking habits.

Cigarette consumption and inhaling, assessed using carboxyhaemoglobin levels, were studied in 1786 men to investigate the importance of tar and nicotine as determinants of smoking habits. No prior warning was given that smoking habits would be studied. Neither nicotine nor tar yields materially influenced the number of cigarettes smoked a day. Both nicotine and tar yields were negatively associated with inhaling (p less than 0.001) but after allowing for either of the two yields the effect of the other on inhaling was no longer statistically significant. There was, therefore, no indication as to whether nicotine or tar was the more important determinant of smoking habit.     

Baseline characteristics and recruitment strategies in a randomized clinical trial of African-American light smokers

PURPOSE: This study describes the design, recruitment, and baseline data of the first smoking-cessation clinical trial for African-American light smokers, Kick It at Swope II (KIS-II). DESIGN: KIS-II was a randomized trial testing the efficacy of nicotine gum (vs. placebo gum) in combination with counseling (motivational interviewing or health education). SETTING: This study was conducted at an urban community-based clinic serving predominantly lower-income African-Americans. SUBJECTS: African-Americans who smoked 1 to 10 cigarettes per day were eligible. Of 1933 individuals screened, 1012 (52%) were eligible and 755 (75%) were enrolled in the study. MEASURES: Baseline assessment included smoking history and psychometric measures. ANALYSIS: The majority of participants were women (67%) with a mean age of 45.1 years (SD = 10.7). Participants smoked on average 7.6 cigarettes (SD = 3.21) per day, had a mean exhaled carbon monoxide level of 13.9 ppm (SD = 8.9) and a mean serum cotinine level of 244.2 ng/mL (SD = 154.4), and reported high levels of motivation and confidence to quit smoking. CONCLUSION: African-American light smokers were motivated to stop smoking and to enroll in a smoking-cessation program. Characteristics of our sample suggest African-American light smokers are an appropriate group for inclusion in smoking-cessation interventions.