Determinants of salivary cotinine concentrations in Chinese male smokers

doi:10.1016/S0091-7435(02)00037-3

Preventive Medicine

Volume 36, Issue 3, March 2003, Pages 282-290

https://doi.org/10.1016/S0091-7435(02)00037-3 Get rights and content

Abstract

Background

Identifying factors that affect cotinine levels in smokers may be useful for smoking cessation programs. Our aims were to characterize the distribution of salivary cotinine levels in Chinese smokers and to investigate factors that influence cotinine concentrations.

Methods

In a cross-sectional study, 600 Chinese adult smokers answered a questionnaire on smoking habits and provided a saliva sample for cotinine analysis. Modification of the relation between number of cigarettes smoked and cotinine concentration by individual characteristics, smoking behavior, and type of tobacco was evaluated.

Results

Quadratic model provided the best fit for the relation between number of cigarettes smoked in the previous 24 hours and salivary cotinine concentration. Among those smoking up to 20 cigarettes, the median cotinine concentration was higher among younger subjects, those smoking cigarettes without filter and regular rather than light cigarettes, and those inhaling frequently and deeply. Such trends were not observed among heavier smokers. The increase in cotinine per cigarette tended to be larger in those with lower median cotinine level.

Conclusions

Our findings show that smoking behavior-related factors modify the relation between number of cigarettes smoked and salivary cotinine concentration. This suggests that smokers may regulate their smoking behavior to achieve a certain optimum nicotine level.

Introduction

There are now about 1.1 billion smokers in the world, using diverse tobacco products. Nicotine addiction is central in the maintenance of sustained smoking, but little is known about nicotine delivery and dose in smokers around the world. Measurement of cotinine, the major proximate metabolite of nicotine, in smokers can provide a characterization of nicotine dose received by a population.

Cotinine can be measured in body fluids, such as plasma, saliva, and urine, as a biomarker of inhaled or ingested nicotine [1], [2]. Cotinine is readily detectable in smokers with a distribution of levels quite distinct from that of nonsmokers. Earlier studies have shown different mean salivary and serum concentrations of cotinine among U.S. smokers of different ethnic backgrounds including Hispanics, blacks, and whites [3], [4], [5]. These differences may reflect differences in smoking behavior, types of cigarettes smoked, and/or nicotine metabolism between smokers of different ethnic groups [5], [6], [7], [8], [9]. The roles of smoking behavior and product characteristics in modifying cotinine concentrations are not yet well understood.

Since nicotine is the major addictive substance in cigarette smoke, cotinine levels of body fluids, as an indicator of nicotine dose, may prove to be important predictors of smoking cessation rates. Identification of factors affecting cotinine levels in body fluids may provide useful information for planning of smoking cessation programs, and for determining the appropriate dosage for nicotine replacement therapy. In addition, the intake of nicotine can be taken as a surrogate for exposure to tar and other toxic substances in tobacco smoke and may thus be predictive of the adverse health effects of smoking [9].

In China, the proportion of active smokers is high among men and low among women. In the National Smoking Prevalence Survey conducted in China in 1996, 63% of men and 4% of women were current smokers [10]. The distribution of cotinine levels in the Chinese smoking population has not been studied previously.

The aims of the present study were to characterize the distribution of salivary cotinine levels in Chinese smokers from Beijing and Shanghai, and to investigate factors that influence salivary cotinine levels in smokers. In addition, this study forms the first part of a multicountry study that will compare the relation of the number of cigarettes smoked with salivary cotinine concentration across different national groups, including China, Mexico, and Brazil.

Section snippets

Study design

A cross-sectional study was conducted among adults in Beijing and Shanghai, China, with interviews and saliva specimen collection taking place between January and March 1999. The Human Research Committees of the Johns Hopkins School of Public Health and the Chinese Academy of Preventive Medicine approved the study.

Study population

The study sample included 600 Chinese adult smokers 15 years or older who were residents in the cities of Beijing and Shanghai (300 subjects in each city). Trained interviewers from

Characteristics and salivary cotinine concentrations of the study population

The distribution of individual characteristics, smoking behavior, and tobacco product characteristics are presented in Table 1 for the total population of 600 subjects and for the final study population of 510 subjects, all cigarette-smoking men. The distributions of most of the characteristics were essentially similar in the study population and in the total population. The number of cigarettes smoked daily was slightly higher in the study population. The median number of cigarettes smoked in

Discussion

This study evaluated the relation between the number of cigarettes smoked in the previous 24 hours and salivary cotinine concentration in a sample of Chinese adults from Beijing and Shanghai. Cotinine concentration as a function of the number of cigarettes smoked fitted well a linear model for the purposes of our analyses. However, the best fit to the data was a convex relation with flattening of the change in cotinine at about 20–30 cigarettes. This form of the curve suggests that there is an

Conclusions

In a population of Chinese male smokers, salivary cotinine concentration increased significantly with the number of cigarettes smoked in the previous 24 hours, a quadratic model providing the best fit to the data. Flattening of this relation was observed at 20–30 cigarettes. Among those smoking up to 20 cigarettes, the median cotinine concentration was higher among younger subjects, among those smoking cigarettes without filter and regular cigarettes rather than light cigarettes, among those

Acknowledgements

This study was funded by a grant from SmithKline Beecham Consumer Healthcare to the Institute for Global Tobacco Control at the Johns Hopkins University Bloomberry School of Public Health. The study was initiated and analyzed by the investigators.

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The prevalence of smokers (daily and occasional) was 27.8% (95% CI: 25.2-30.4%). The optimal cut-point to discriminate smoking status was 9.2 ng/ml (sensitivity=88.7% and specificity=89.0%). The area under the ROC curve was 0.952. The optimal cut-point was 12.2 ng/ml in men and 7.6 ng/ml in women. The optimal cut-point was higher at ages with a greater prevalence of smoking. Daily smokers had a higher cut-point than occasional smokers.
The optimal cut-point to discriminate smoking status in the adult population is 9.2 ng/ml, with sensitivities and specificities around 90%. The cut-point was higher in men and in younger people. The cut-point increases with higher prevalence of daily smokers.
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Objective: To assess environmental tobacco smoke (ETS) exposure amongst primary school children.
Methods: A descriptive, community-based, cross-sectional study of self-reported parental smoking patterns and children's salivary cotinine concentrations in 245 children aged 5–11 years attending 10 primary schools in Liverpool.
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Regular articleDeterminants of salivary cotinine concentrations in Chinese male smokers

Abstract

Background

Methods

Results

Conclusions

Introduction

Section snippets

Study design

Study population

Characteristics and salivary cotinine concentrations of the study population

Discussion

Conclusions

Acknowledgements

Pharmacol Biochem Behav

Prev Med

J Chromatogr B Biomed Appl

Regul Toxicol Pharmacol

J Clin Epidemiol

Food Chem Toxicol

Comparison of tests used to distinguish smokers from nonsmokers

Am J Public Health

Cotinine as a biomarker of environmental tobacco smoke exposure

Epidemiol Rev

Racial differences in serum cotinine levels among smokers in the Coronary Artery Risk Development in (Young) Adults Study

Am J Public Health

Cigarette yields of tar and nicotine and markers of exposure to tobacco smoke

Am Rev Respir Dis

Racial and ethnic differences in serum cotinine levels of cigarette smokers. Third National Health and Nutrition Examination Survey, 1988–1991

JAMA

How a cigarette is smoked determines blood nicotine levels

Clin Pharmacol Ther

Regular article
Determinants of salivary cotinine concentrations in Chinese male smokers