Environmental tobacco use and indicators of metabolic syndrome in Chinese adults

Exposure to environmental tobacco smoke (ETS) is a widespread source of nicotine exposure, and an estimated 540 million Chinese are exposed to ETS in mainland China. We aimed to investigate associations of ETS exposure and metabolic syndrome (MetS) as well as its individual components independent of active smoking status in Chinese adults. A cross-sectional data of 304 randomly selected Chinese households with fourth (elementary school) and seventh (middle school) graders in Qingdao city was used. Assessments of fat mass, metabolic biomarkers, personal history of illness, and health behaviors were conducted. Proportions of current smokers were 3% in women and 60.5% in men, and more men reported exposure to ETS 5-7 days per week than women (60.8% vs. 48.1%). Exposure to ETS was significantly associated with enhanced risks of MetS (odds ratio [OR] = 2.8, p = .01), hypertriglyceridemia (OR = 2.1, p = .02), and central obesity (OR = 2.7, p < .001) and reduced levels of high-density lipoprotein cholesterol (OR = 1.9, p = .02) and elevated mean levels of fasting insulin (p < .01). These observed associations were independent of active smoking status and were successfully replicated in female never-smokers. Results of our study support the hypothesis that ETS exposure is independently associated with MetS and its individual components. Further large-scale studies with longitudinal design and objective assessment of ETS exposure are needed to elucidate the underlying mechanisms and the causal effects of passive smoking on MetS. Findings of this work emphasize the importance of developing community intervention to reduce smoking, ETS, and promote healthy lifestyle.