Urine Cotinine and Environmental Tobacco Exposure in Korean Adolescents

Background: The aim of this study was to elucidate the relationship of environmental tobacco smoke (ETS) exposure and the urine cotinine concentrations in Korean adolescents. Methods: The study population was 1st grade high school adolescents (n = 1467, girls 22.2%) recruited from four high schools, two from Seoul, one from Kangleung and one from Woolsan. We obtained information on active smoking and ETS exposure through self-reported questionnaire and urine cotinine concentrations. Results: The prevalence of active smoking was 6.9% in boys and 0.9% in girls. Median urine cotinine concentrations were 19.5 mu g/L (range, 0-2341 mu g/L) among smokers, and 0 mu g/L (range, 0-1359 mu g/L) among nonsmokers. The positive rate of urine cotinine among nonsmokers exposed to ETS was 2.9%. Boys were exposed to ETS in the order of frequency in PC room (79.6%), home (39.4%), school (11.5%), and public places (5.9%); girls were exposed in the order of frequency in home (40.9%), PC room (33.2%), public places (28.0%), and school (15.2%). The frequency and duration of ETS exposure were significantly larger and longer in boys than in girls. Boys contacted friends who smoked more than girls did (32.6% vs. 17.1%). Parents' smoking status was similar both in boys and girls. Any information on ETS exposure did not differ according to the detectable urine cotinine among nonsmoking adolescents. Conclusion: Low positive rate of urine cotinine and no association of urine cotinine with various ETS exposure history reflect that urine cotinine may not be a good marker for ETS exposure in Korean adolescents.