Urine levels of nicotine and its metabolites in young population exposed to second-hand smoke in nightclubs: a pilot study

The aim of this study was to investigate the extent of second-hand smoke exposure in younger population visiting nightclubs in Croatia by comparing the levels of nicotine and its main metabolites cotinine and trans-3′-hydroxycotinine (3HC) in urine samples taken from 22 participants before and after spending about three hours in a nightclub, stratified by smoking status (smokers and non-smokers). The samples were prepared by liquid-liquid extraction and analysed with gas chromatography-mass spectrometry. The presence of nicotine, cotinine, and 3HC was confirmed in all urine samples. Their median concentrations significantly differed between the two measurements in non-smokers. Our findings show that even a three-hour exposure to second-hand smoke can significantly increase the levels of nicotine and its metabolites in urine, which are indicative of exposure to other, harmful tobacco smoke substances. They also call for raising awareness of the health risks of exposure to second-hand smoke in the general population and among individuals who frequent nightclubs in particular.