Urinary Cotinine Level in Indonesian Children Exposed to Domestic Cigarette Smoke

BACKGROUND: Cotinine is a major metabolite of nicotine, and its urinary level is an indicator of exposure to cigarette smoke. The present study was aimed at identifying the urinary cotinine level in Indonesian children who were exposed and not exposed to domestic cigarette smoke. METHODS: The study was a cross-sectional study in elementary school-aged children who had not smoked. The subjects were categorized into an exposed group and unexposed group based on their exposure status. Data were obtained from a questionnaire and random urinary samples measured using enzyme-linked immunosorbent assay. RESULTS: There were a total of 128 subjects, including 64 children in the exposed group and 64 children in the unexposed group. The median level of cotinine in all subjects was 17.95 ng/ml (with a range of 0.1–158.3 ng/ml). The urinary cotinine level in the exposed group was higher than the unexposed group (median: 30.1 ng/ml vs. 8.45 ng/ml; P < 0.000). There was a correlation between urinary cotinine levels in children exposed to cigarette smoke and the number of cigarettes smoked by the smokers at home (P < 0.05). The optimal cut-off points of urinary cotinine levels in children, which was utilized to evaluate cigarette smoke exposure, was 17.95 ng/ml (81% sensitivity; 81% specificity; P < 0.000). CONCLUSION: The urinary cotinine level in children exposed to cigarette smoke is higher than children who are not exposed to domestic cigarette smoke. The urinary cotinine level can be used as a noninvasive marker to evaluate cigarette smoke exposure in children.