Breath Carbon Monoxide and Cotinine as Biomarkers to Distinguish Smokers From Nonsmokers

Study Summary

Background: * Self-report and biochemical verification are used to determine smoking status in treatment trials and clinical research. Each method has merits and limitations that make it appropriate for particular situations. Participants who feel social pressure to report tobacco abstinence may provide unreliable self-reporting results. Biochemical verification using breath carbon monoxide (CO) is a more reliable indicator, but several biological and environmental factors (including exposure to secondhand smoke) can affect the sensitivity and specificity of breath CO measurement. * An ideal biomarker of smoking status is cotinine, the major metabolite of nicotine. Cotinine levels found in blood, urine, and saliva can be used to distinguish between smokers and nonsmokers, as well as between light and heavy smokers. Researchers are interested in using cotinine assessments to develop suitable breath CO cutoff levels to categorize different types of smokers and nonsmokers for use in future research. Objectives: \- To determine a breath carbon monoxide (CO) cutoff level that optimally discriminates between heavy and light smokers and nonsmokers who are and who are not exposed to environmental tobacco smoke. Eligibility: * Individuals between 18 and 64 years of age who fall into one of the following groups: * current smokers reporting more than 10 cigarettes per day for at least 6 months * current smokers reporting 10 or fewer cigarettes per day for at least 6 months * nonsmokers reporting regular environmental exposure to tobacco smoke * nonsmokers reporting limited or no exposure to tobacco smoke Design: * The study will involve a single outpatient session. * Participants will provide breath CO, urine, and saliva samples, and will complete several smoking-related questionnaires on smoking history, current craving levels, and perceived level of nicotine dependence.