Relation of Serum Cotinine with Passive Smoking

Abstract

Background: Cotinine is a major metabolite of nicotine and retains for a substantial time in different body fluids. It is considered as a passive smoke exposure marker. Studies on different biochemical markers of tobacco smoke exposure are lacking in Pakistan and serum continine levels in nonsmokers provide a comprehensive measure of passive smoking from all sources in the last two to three days. Objective: To compare the frequency of serum cotinine detection in smokers, passive smokers and never smokers. Methods: Serum cotinine was analyzed on 135 self reported smokers, never smokers and passive smokers by 17-A gas chromatograph with flame ionization detector (FID) equipped with Supelco SPB-5 fused silica capillary column attached with Class GC 10 Software. Association between the qualitative variables (cotinine present/absent) between groups (smoker, never smoker and passive smoker) was taken out using Pearson chi-square test. The mean difference for serum cotinine between the groups (smoker, never smoker and passive smoker) was evaluated by using kruskal wallis test. P-value less than 0.05 was taken as significant. Results: Serum cotinine was detectable in 72.1% of passive smokers which was a significantly higher proportion than smokers and never smokers (p< 0.001). Conclusion: Cotinine was detectable in the serum of smokers and passive smokers. Passive smoking may contribute to increased serum cotinine levels. Large sample size may be required to establish it as a marker for environmental tobacco smoke exposure marker and for validation of smoking status. Key Words: Cotinine, Passive Smoking, Environmental Tobacco Smoke (ETS), Secondhand Smoke (SHS), Gas Chromatography.