DISTRIBUTIONS OF SERUM COTININE AND URINARY NNAL AMONG DAILY CIGARETTE SMOKERS AND INTER-CORRELATIONS

Background/Objectives: Serum cotinine (SCOT) and urinary 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanol (NNAL) are often used as biomarkers of tobacco smoke. The objective of this study was to investigate factors associated with the variability in the levels of SCOT and NNAL among daily cigarette smokers aged ? 20 years and to evaluate co-rrelational patterns between their observed levels. Methods: Data from National Health and Nutrition Examination Survey for years 2007 - 2012 were used. Statistical methodologies including regression models that incorporated sampling weights and sampling design characteristics were used to assess factors associated with the variability in the observed levels of SCOT and NNAL among daily cigarette smokers aged ? 20 years as well as to study co-rrelational patterns between the observed levels of SCOT and NNAL. Results: Levels of both SCOT and NNAL increased with increase in age (p < 0.01) but, as estimated by the fitted regression parameters, starting at the age of about 55 years for SCOT and at the age of about 60 years for NNAL, increase in observed levels of both of these of chemicals slowed down. Relationship of both SCOT and NNAL with number of cigarettes smoked per day (CPD) was mediated by the self-reported values of CPD. Conclusion: While both SCOT and NNAL are useful biomarkers of tobacco smoke, variability in their observed levels with change in such factors as age as well as co-rrelational patterns between them should be kept in mind before any decision is made to estimate “true” level of smoking associated with their observed levels.