Differences In Smoking Behavior Research Articles

Cigarette Smoking and Serious Psychological Distress: A Population-Based Study of California Adults

This study examines differences in smoking behaviors between adults with and without serious psychological distress (SPD) in California, which has the longest running comprehensive tobacco control program in the world. Cross-sectional data from the 2007 California Health Interview Survey on 50,880 noninstitutionalized adults were used to analyze smoking prevalence, cigarette consumption, and quit ratio. Persons with SPD were identified using the K6 scale, a clinically validated psychological screening instrument. About 3.8% of California adults screened positive for SPD in the past 30 days (acute SPD) and an additional 4.8% screened positive for SPD in the past 2-12 months (recent SPD). Persons with SPD were more likely to be current smokers than those without SPD (adjusted odds ratios [AOR] = 2.54, 95% CI = 2.02-3.19 for acute SPD and AOR = 2.20, 95% CI = 1.79-2.71 for recent SPD). Current smokers with acute SPD were more likely to smoke ≥20 cigarettes daily than those without SPD (AOR = 1.59, 95% CI = 1.06-2.39). The quit rate was lower among ever-smokers with acute (AOR = 0.46, 95% CI = 0.35-0.62) or recent SPD (AOR = 0.55, 95% CI = 0.42-0.71) than those without SPD. While persons with acute or recent SPD comprised 8.6% of adults, they consumed 19.2% of all cigarettes in California. In California, adults with SPD were more likely to be current smokers and to smoke heavily and less likely to quit than those without SPD. The findings underscore the need for effective smoking cessation strategies targeting this group.

Cigarette smoking as a risk factor for coronary heart disease in women compared with men: a systematic review and meta-analysis of prospective cohort studies

Prevalence of smoking is increasing in women in some populations and is a risk factor for coronary heart disease. Whether smoking confers the same excess risk of coronary heart disease for women as it does for men is unknown. Therefore, we aimed to estimate the effect of smoking on coronary heart disease in women compared with men after accounting for sex differences in other major risk factors. We undertook a systematic review and meta-analysis of prospective cohort studies published between Jan 1, 1966, and Dec 31, 2010, from four online databases. We selected cohort studies that were stratified by sex with measures of relative risk (RR), and associated variability, for coronary heart disease and current smoking compared with not smoking. We pooled data with a random effects model with inverse variance weighting, and estimated RR ratios (RRRs) between men and women. We reviewed 8005 abstracts and included 26 articles with data for 3,912,809 individuals and 67,075 coronary heart disease events from 86 prospective trials. In 75 cohorts (2·4 million participants) that adjusted for cardiovascular risk factors other than coronary heart disease, the pooled adjusted female-to-male RRR of smoking compared with not smoking for coronary heart disease was 1·25 (95% CI 1·12-1·39, p<0·0001). This outcome was unchanged after adjustment for potential publication bias and there was no evidence of important between-study heterogeneity (p=0·21). The RRR increased by 2% for every additional year of study follow-up (p=0·03). In pooled data from 53 studies, there was no evidence of a sex difference in the RR between participants who had previously smoked compared with those who never had (RRR 0·96, 95% CI 0·86-1·08, p=0·53). Whether mechanisms underlying the sex difference in risk of coronary heart disease are biological or related to differences in smoking behaviour between men and women is unclear. Tobacco-control programmes should consider women, particularly in those countries where smoking among young women is increasing in prevalence. None.

Factors affecting exposure to nicotine and carbon monoxide in adult cigarette smokers

Exposure to cigarette smoke among smokers is highly variable. This variability has been attributed to differences in smoking behavior as measured by smoking topography, as well as other behavioral and subjective aspects of smoking. The objective of this study was to determine the factors affecting smoke exposure as estimated by biomarkers of exposure to nicotine and carbon monoxide (CO). In a multi-center cross-sectional study of 3585 adult smokers and 1077 adult nonsmokers, exposure to nicotine and CO was estimated by 24 h urinary excretion of nicotine and five of its metabolites and by blood carboxyhemoglobin, respectively. Number of cigarettes smoked per day (CPD) was determined from cigarette butts returned. Puffing parameters were determined through a CreSS® micro device and a 182-item adult smoker questionnaire (ASQ) was administered. The relationship between exposure and demographic factors, smoking machine measured tar yield and CPD was examined in a statistical model (Model A). Topography parameters were added to this model (Model B) which was further expanded (Model C) by adding selected questions from the ASQ identified by a data reduction process. In all the models, CPD was the most important and highest ranking factor determining daily exposure. Other statistically significant factors were number of years smoked, questions related to morning smoking, topography and tar yield categories. In conclusion, the models investigated in this analysis, explain about 30–40% of variability in exposure to nicotine and CO.

Gender Differences in Smoking Behaviour and Cessation

AbstractThis article reviews the literature to compare differential outcomes among men and women after smoking cessation, assess barriers they may face during cessation and provide recommendation to address gender-specific challenges in smoking cessation interventions. There is some evidence that women achieve lower abstinence rates than men after a quit attempt with nicotine replacement therapy, as well as without pharmacotherapy, and several underlying mechanisms were discussed to account for these findings. These include: (a) women have specific genetic variants that affect pharmacokinetics and pharmacodynamics of the medication, (b) hormonal influences increase nicotine metabolism and withdrawal symptoms, (c) women are more responsive to nonpharmacological aspects of smoking than men, (d) women are more vulnerable to depression and negative mood than men, (e) weight concerns are greater barriers for women than for men and (g) women receive less effective social support than men during a quit attempt. Gender-specific counselling that accounts for these factors and addresses the different needs of men and women may be a promising approach to improve long-term abstinence rates. However, more research is required to identify gender-related underlying mechanisms of differential smoking cessation outcomes, develop tailored interventions that account for gender differences and study the implementation and outcomes of gender-responsive treatment approaches.

Chromosome 15q25 (CHRNA3-CHRNA5) Variation Impacts Indirectly on Lung Cancer Risk

Genetic variants at the 15q25 CHRNA5-CHRNA3 locus have been shown to influence lung cancer risk however there is controversy as to whether variants have a direct carcinogenic effect on lung cancer risk or impact indirectly through smoking behavior. We have performed a detailed analysis of the 15q25 risk variants rs12914385 and rs8042374 with smoking behavior and lung cancer risk in 4,343 lung cancer cases and 1,479 controls from the Genetic Lung Cancer Predisposition Study (GELCAPS). A strong association between rs12914385 and rs8042374, and lung cancer risk was shown, odds ratios (OR) were 1.44, (95% confidence interval (CI): 1.29–1.62, P = 3.69×10−10) and 1.35 (95% CI: 1.18–1.55, P = 9.99×10−6) respectively. Each copy of risk alleles at rs12914385 and rs8042374 was associated with increased cigarette consumption of 1.0 and 0.9 cigarettes per day (CPD) (P = 5.18×10−5 and P = 5.65×10−3). These genetically determined modest differences in smoking behavior can be shown to be sufficient to account for the 15q25 association with lung cancer risk. To further verify the indirect effect of 15q25 on the risk, we restricted our analysis of lung cancer risk to never-smokers and conducted a meta-analysis of previously published studies of lung cancer risk in never-smokers. Never-smoker studies published in English were ascertained from PubMed stipulating - lung cancer, risk, genome-wide association, candidate genes. Our study and five previously published studies provided data on 2,405 never-smoker lung cancer cases and 7,622 controls. In the pooled analysis no association has been found between the 15q25 variation and lung cancer risk (OR = 1.09, 95% CI: 0.94–1.28). This study affirms the 15q25 association with smoking and is consistent with an indirect link between genotype and lung cancer risk.

Associations of nicotine intake measures with CHRN genes in Finnish smokers.

Genetic effects contribute to individual differences in smoking behavior. Persistence to smoke despite known harmful health effects is mostly driven by nicotine addiction. As the physiological effects of nicotine are mediated by nicotinic acetylcholine receptors (nAChRs), we aimed at examining whether single nucleotide polymorphisms (SNPs) residing in nAChR subunit (CHRN) genes, other than CHRNA3/CHRNA5/CHRNB4 gene cluster previously showing association in our sample, are associated with smoking quantity or serum cotinine levels. The study sample consisted of 485 Finnish adult daily smokers (age 30-75 years, 59% men) assessed for the number of cigarettes smoked per day (CPD) and serum cotinine level. We first studied SNPs residing on selected nAChR subunit genes (CHRNA2, CHRNA4, CHRNA6/CHRNB3, CHRNA7, CHRNA9, CHRNA10, CHRNB2, CHRNG/CHRND) genotyped within a genome-wide association study for single SNP and multiple SNP associations by ordinal regression. Next, we explored individual haplotype associations using sliding window technique. At one of the 8 loci studied, CHRNG/CHRND (chr2), single SNP (rs1190452), multiple SNP, and 2-SNP haplotype analyses (SNPs rs4973539-rs1190452) all showed statistically significant association with cotinine level. The median cotinine levels varied between the 2-SNP haplotypes from 220 ng/ml (AA haplotype) to 249 ng/ml (AG haplotype). We did not observe significant associations with CPD. These results provide further evidence that the γ-δ nAChR subunit gene region is associated with cotinine levels but not with the number of CPD, illustrating the usefulness of biomarkers in genetic analyses.

Differences in Smoking Behavior and Attitudes among Puerto Rican, Dominican, and Non-Latino White Caregivers of Children with Asthma

No studies have examined the differences in smoking attitudes and behavior between Dominicans (DRs) and Puerto Ricans (PRs). Identification of pretreatment differences is important for cultural adaptation of evidenced-based smoking cessation treatments. Secondary analysis. SETTING/INTERVENTION: Three home visits for asthma education and smoking cessation. Caregivers who smoke and have a child with asthma: DRs (n = 30), PRs (n = 67), and non-Latino whites (n = 128; NLWs). Baseline assessment of psychosocial variables. Controlled for age, education, and acculturation. Compared with DRs, PRs were more acculturated, more nicotine dependent, less motivated and confident to quit, and identified more pros of smoking (all p < .05). Compared with NLWs, PRs were less likely to be employed, smoked fewer cigarettes per day, and had lower education, greater depressed mood, greater pros and cons of smoking, less social support, and higher child asthma morbidity (all p < .05). Compared with NLWs, DRs were less nicotine dependent, more confident to quit, and less likely to live with a smoker; reported greater cons of smoking and greater stress; and were more likely to have a household smoking ban (DRs 60% vs. NLWs 33.6%). Only 3.3% of DRs were precontemplators vs. 16.4% (PRs) and 10.9% (NLWs). PRs appear to have more factors associated with risk of smoking treatment failure; DRs appear to have more protective factors. Examination of the role of these smoking attitudes as potential moderators and mediators of smoking behavior are needed to guide the cultural adaptation of evidenced-based treatments.

Association of a variant in the CHRNA5-A3-B4 gene cluster region to heavy smoking in the Italian population

Large-scale population studies have established that genetic factors contribute to individual differences in smoking behavior. Linkage and genome-wide association studies have shown many chromosomal regions and genes associated with different smoking behaviors. One study was the association of single-nucleotide polymorphisms (SNPs) in the CHRNA5-A3-B4 gene cluster to nicotine addiction. Here, we report a replication of this association in the Italian population represented by three genetically isolated populations. One, the Val Borbera, is a genetic isolate from North-Western Italy; the Cilento population, is located in South-Western Italy; and the Carlantino village is located in South-Eastern Italy. Owing to their position and their isolation, the three populations have a different environment, different history and genetic structure. The variant A of the rs1051730 SNP was significantly associated with smoking quantity in two populations, Val Borbera and Cilento, no association was found in Carlantino population probably because difference in LD pattern in the variant region.

Nicotine dependence and gender differences in smokers accessing community mental health services

Despite evidence of differences in smoking behaviour between women and men, few studies have assessed these differences in individuals with mental illnesses. In this cross-sectional study, we explored gender differences in smoking behaviour among 298 individuals (60% male) accessing community mental health services. Individuals with a psychotic disorder as compared with a non-psychotic disorder, and individuals using a greater number of substances were more likely to be male. Readiness to change, daily cigarette consumption and level of nicotine dependence did not differ between men and women; however, subjective ratings of tobacco addiction were higher in women than in men. Among women, only scores on the subjective tobacco addiction scale were associated with nicotine dependence, while among men, a variety of variables were associated with nicotine dependence. These factors are important for understanding individual differences in tobacco dependence among clients with mental illnesses, and are expected to inform future studies examining tobacco use in mental health treatment populations.

Genetic variations on chromosomes 5p15 and 15q25 and bladder cancer risk: findings from the Los Angeles–Shanghai bladder case–control study

Genome-wide association studies have associated common variations at chromosomes 5p15 and 15q25 with lung cancer risk. The 5p15 locus has also been associated with increased bladder cancer risk in a recent report. The 15q25 locus has been associated with nicotine dependence and self-reported number of cigarettes smoked per day in some studies and it was proposed that its association with lung cancer may be mediated through differences in smoking behavior. Here, we investigated the roles of variations at 5p15 (rs401681, rs402710, rs2736098 and rs2736100) and 15q25 (rs1051730 and rs8034191) in bladder cancer etiology in two case-control studies conducted separately in Los Angeles County, CA, USA (498 cases and 588 controls) and in Shanghai, China (506 cases and 530 controls). We replicated the association between the 5p15 locus and bladder cancer among non-Hispanic whites (NHW) in Los Angeles [for rs2736100, per C allele odds ratio (OR) = 1.23; 95% confidence interval (CI), 1.02-1.48; P = 0.029] and among Chinese in Shanghai (OR = 1.22; 95% CI, 1.02-1.47; P = 0.033). Both rs1051730 and rs8034191 at 15q25 were rare among Chinese. Among NHW, a significant association was found between rs8034191 and bladder cancer which persisted after adjustment for cigarette smoking status, number of cigarettes smoked per day and number of years of smoking (per C allele OR = 1.26; 95% CI, 1.04-1.54; P = 0.017). Our results support 5p15 and 15q25 as susceptibility regions for bladder cancer risk.

The intersection of gender and race/ethnicity in smoking behaviors among menthol and non‐menthol smokers in the United States

To determine whether menthol is related to initiation, quantity or quitting, we examined differences in smoking behaviors among menthol and non-menthol smokers, stratified by gender and race/ethnicity, and adjusting for age, income and educational attainment. Cross-sectional, using data from the 2005 National Health Interview Survey and Cancer Control Supplement. United States. Black, Hispanic and white women and men aged 25-64 years. For each group, we examined (i) proportion of menthol smokers (comparing current and former smokers); (ii) age of initiation, cigarettes smoked per day and quit attempt in the past year (comparing menthol and non-menthol current smokers); and (iii) time since quitting (comparing menthol and non-menthol former smokers). We calculated predicted values for each demographic group, adjusting for age, income and educational attainment. After adjusting for age, income and education, black (compared with Hispanic and white) and female (compared with male) smokers were more likely to choose menthol cigarettes. There was only one statistically significant difference in age of initiation, cigarettes smoked per day, quit attempts or time since quitting between menthol and non-menthol smokers: white women who smoked menthol cigarettes reported longer cessation compared with those who smoked non-menthol cigarettes. The results do not support the hypothesis that menthol smokers initiate earlier, smoke more or have a harder time quitting compared with non-menthol smokers. A menthol additive and the marketing of it, given the clear demographic preferences demonstrated here, however, may be responsible for enticing the groups least likely to smoke into this addictive behavior.

Use of mentholated cigarettes: what can we learn from national data sets?

Use of mentholated cigarettes: what can we learn from national data sets?

Smoking behavior among Hispanic adults with diabetes on the United States-Mexico border: a public health opportunity

To examine the prevalence of smoking behaviors among adults with diabetes on the United States-Mexico border, to compare these behaviors in U.S. Hispanics and Mexicans with diabetes, and to identify explanations for group differences. Data came from the U.S.-Mexico Border Diabetes Prevention and Control Project survey (2001-2002), a stratified, multistage sample representative of the border population. The analytic sample included adults from all racial and ethnic backgrounds with diabetes (n = 665), including 333 Mexicans and 268 U.S. Hispanics. Smoking behaviors were based on self-reports. Age- and gender-specific prevalence of smoking behavior was estimated and logistic regression was used for mediation analysis of group differences. One in five adults with diabetes (20.1%) in the region was a current smoker. Prevalence was higher among Mexicans (26.2%) than U.S. Hispanics (10.1%, P = 0.003); differences were not explained by sociodemographic or healthcare-related characteristics (odds ratio [OR] 3.86, 95% confidence interval [CI] 1.50-9.91, P = 0.004). Younger Mexicans with diabetes (< 55 years) were four times more likely to smoke than younger U.S. Hispanics (32.1% versus 8.1%, P < 0.001) and Mexican men with diabetes were more than twice as likely to smoke as U.S. Hispanic men (38.9% versus 15.8%, P = 0.003). Among adults with diabetes with a smoking history, 52.5% were former smokers; U.S. Hispanics were more likely to be former smokers than Mexicans with diabetes (62.6% versus 27.5%, P = 0.001). A marginally significant difference remained after adjusting for potential mediators (OR 0.42, 95% CI 0.17-1.08, P = 0.074). Smoking interventions should focus on Mexicans with diabetes in the border region, especially younger adults and men. Identifying sources of differences in smoking behaviors among border groups with diabetes may further inform intervention.

A multilevel-based study of school policy for tobacco control in relation to cigarette smoking among children in elementary schools: gender differences

The aim was to comprehensively examine school-based tobacco policy status, implementation and students' perceived smoking at school in regard to gender-specific differences in smoking behavior. We conducted a multilevel-based study to assess two-level effects for smoking among 2350 grades three to six students in 26 randomly selected elementary schools in southern Taiwan. A series of multilevel models were analyzed separately for male and female students. The school-level variables appear to be related to smoking behavior in male students. Among males, the risk of ever-smoking was significantly associated with those schools without antitobacco health education activities or curricula [adjusted odds ratio (aOR) = 6.23, 95% confidence interval (CI): 2.55-15.24], with a high perceived smoking rate (aOR = 3.08, 95% CI: 1.41-6.72) and located in a mountainous region (aOR = 2.53, 95% CI: 1.15-5.58). The risk of ever-smoking among females was significantly associated with those schools without antitobacco activities or curricula (aOR = 3.10, 95% CI: 1.27-7.55). As compared with female counterparts, the specific school that the male students attended had a positive significant effect on the risk of being ever-smokers. The findings suggest that effective tobacco policy implementation should be considered in elementary schools that are currently putting children at the greatest risk for cigarette smoking, especially in regard to male students.

Smoking behaviour and attitudes in patients undergoing cardiac surgery. The Radboud experience

Changes in smoking behaviour and attitudes of 2642 patients, undergoing cardiac surgery, between January 2000 and July 2008 were studied. All patients completed a preoperative questionnaire concerning smoking behaviour and attitude. Study endpoints are behaviour and attitude in relation to tobacco use in hospitals, cessation smoking before and after the operation. Over the years there have been no notable differences in smoking behaviour, however, significantly less patients accept smoking in the hospital (0.9% vs. 5.3%). Significantly more patients stopped within the two weeks before surgery (9.4% vs. 5.3%). The percentage of patients who did not have the intention to stop smoking after the operation did not decrease significantly. Significantly less older patients smoke (1.6% vs. 13.4%) and are less tolerant towards smoking in the hospital (1.8% vs. 4.1%). A significant higher percentage of older patients have stopped smoking over five years before the operation. Concerning the intention to stop smoking after the operation, there is no significant difference. These results show that over the years, patients undergoing cardiac surgery seem to be more aware about the relation between health and smoking. This is not related to the type of operation, however, apparently with age.

Soziale Determinanten des Tabakkonsums bei Erwachsenen in Deutschland

Findings on social differences in smoking behavior are an essential prerequisite for target-group-specific tobacco prevention. Using the available data on the adult population in Germany, it can be shown that people with little education, low occupational status, and low income are more likely to smoke. Smoking rates are also high among unemployed and single-parent men and women and in certain immigrant groups. A comparison between the federal states points to a strong correlation between smoking rate and poverty. It can be shown that the social differences in smoking behavior grew, especially among women, during the period from 1998 to 2006. Thus, the results suggest that the reduction of social disparities in tobacco consumption should also be a measure of the success of tobacco prevention.

Differences in socioeconomic and gender inequalities in tobacco smoking in Denmark and Sweden; a cross sectional comparison of the equity effect of different public health policies

BackgroundDenmark and Sweden are considered to be countries of rather similar socio-political type, but public health policies and smoking habits differ considerably between the two neighbours. A study comparing mechanisms behind socioeconomic inequalities in tobacco smoking, could yield information regarding the impact of health policy and -promotion in the two countries.MethodsCross-sectional comparisons of socioeconomic and gender differences in smoking behaviour among 6 995 Danish and 13 604 Swedish persons aged 18-80 years.ResultsThe prevalence of smoking was higher in Denmark compared to Sweden. The total attributable fraction (TAF) of low education regarding daily smoking was 36% for Danish men and 35% for Danish women, and 32% and 46%, respectively, for Swedish men and women. TAF of low education regarding continued smoking were 16.2% and 15.8% for Danish men and women, and 11.0% and 18.8% for Swedish men and women, respectivelyThe main finding of the study was that the socioeconomic patterning of smoking, based on level of education and expressed as the relative contribution to the total burden of smoking exposure, was rather different in Sweden and Denmark. Moreover, these differences were modified by gender and age. As a general pattern, socioeconomic differences in Sweden tended to contribute more to the total burden of this habit among women, especially in the younger age groups. In men, the patterns were much more similar between the two countries. Regarding continued smoking/unsuccessful quitting, the patterns were similar for women, but somewhat different for men. Here we found that socioeconomic differences contributed more to overall continued smoking in Danish men, especially in the middle-age and older age strata.ConclusionThe results imply that Swedish anti-smoking policy and/or implemented measures have been less effective in a health equity perspective among the younger generation of women, but more effective among men, compared to Danish policy implementation. The results also raises the more general issue regarding the possible need for a trade-off principle between overall population efficacy versus equity efficacy of anti-tobacco, as well as general public health policies and intervention strategies.

Preliminary effects of bupropion and the promoter region (HTTLPR) serotonin transporter (SLC6A4) polymorphism on smoking behavior in schizophrenia

In the current study, we investigated how individual variants in the serotonin promoter gene, previously associated with smoking cessation and linked to anxiety-related personality traits, were associated with individual differences in responsiveness to bupropion and cognitive behavioral therapy (CBT) in a clinical population. We hypothesize that subjects with the long allele may be less responsive to treatment. Altogether 61 schizophrenic patients (46M, 15F) on stable neuroleptic medication were initially enrolled in a smoking reduction program (prospective, double-blind, placebo-controlled) including cognitive behavioral therapy plus placebo or CBT plus bupropion. Additionally, subjects were genotyped for a polymorphism in the serotonin transporter (SLC6A4). Thirty-two subjects (23M, 9F) completed a 14-week course of treatment. While both groups of subjects demonstrated significant reductions in smoking behavior due to CBT, subjects receiving bupropion did not show significant differences in smoking behavior when compared to placebo. In addition, analysis by SPSS repeated measures multivariate showed a significant sex by SLC6A4 genotype interaction on the number of cigarettes smoked. Only male subjects with at least one short promoter region allele (short/short and short/long combined) showed a reduction in cigarette consumption as a result of treatment. This study provides preliminary evidence of how polymorphisms in the serotonin transporter can be informative in predicting individual responses to smoking reduction therapy.

Correlates of heavy smoking among alcohol-using methadone maintenance clients.

This cross-sectional study examines predictors of heavy smoking among 256 male and female methadone maintenance therapy (MMT) clients from five MMT clinics in the Los Angeles area. The authors find that women report lower rates of heavy smoking than men (47% vs. 54%, respectively), in concordance with current literature pointing to gender differences in smoking behaviors. In particular, men who report heavy drinking, fair or poor health, and recent heroin use are more likely to report heavy smoking compared with men not reporting these factors. Women who report recent heroin use, a lifetime history of sex trade, and who have been ill enough to require a blood transfusion also have greater odds of reporting heavy cigarette smoking. Findings from this study may aid not only in designing gender-based smoking cessation programs for MMT clients but also in addressing the gender-based issues related to smoking in such a population.

Smokers with the CHRNA lung cancer-associated variants are exposed to higher levels of nicotine equivalents and a carcinogenic tobacco-specific nitrosamine.

A locus at 15q24/15q25.1, which includes the nicotinic acetylcholine receptor A subunits 3 and 5 (CHRNA3 and CHRNA5) genes, has recently been associated with lung cancer risk, self-reported number of cigarettes smoked per day, and a nicotine dependence scale. It is not clear whether the association with lung cancer is direct or mediated through differences in smoking behavior. We used urinary biomarkers to test whether two linked lung cancer risk variants in CHRNA3 (rs1051730) and CHRNA5 (rs16969968) are associated with intensity of smoking and exposure to a tobacco-specific carcinogenic nitrosamine per cigarette dose. We studied 819 smokers and found that carriers of these variants extract a greater amount of nicotine (P = 0.003) and are exposed to a higher internal dose of 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (P = 0.03) per cigarette than noncarriers. Thus, smokers who carry the CHRNA3 and CHRNA5 variants are expected to be at increased risk for lung cancer compared with smokers who do not carry these alleles even if they smoked the same number of cigarettes. Number of cigarettes per day, even if it could be accurately assessed, is not an adequate measure of smoking dose.