Passive smoking is associated with lower serum HDL-C levels in school children

Background: In recent years, a number of studies have reported that exposure to environmental tobacco smoke (ETS) reduces high-density lipoprotein cholesterol (HDL-C) levels in children, as well as in adults. Further, a number of countries have indicated that passive smoking increases the risk of early arteriosclerosis onset. Here, to evaluate the effects of ETS exposure, we conducted a cross-sectional epidemiological study on primary school children in Japan using answers from a questionnaire survey, as well as urine cotinine and lipid metabolism-related variable measurements. Methods: A total of 121 sixth-grade primary school children participated in this study by completing a questionnaire about their food intake, lifestyle and family smoking habits. Early in the morning, we also measured height, weight, blood pressure, serum levels of total cholesterol, triglyceride, HDL-C, and blood sugar, as well as urine levels of cotinine and creatinine under unfed conditions. Results: From the questionnaire, 40 and 81 children reported being exposed and not exposed to ETS, respectively. Serum HDL-C levels, which were adjusted for the degree of corpulence and exercise habits, were significantly lower in the passive smoker group than the non-passive-smoker group (65.3 and 72.1 mg/dL, respectively; P = 0.012). In addition, proportional differences in serum HDL-C levels were also observed based on the amount of cigarettes smoked at home by family members of the child. Conclusions: Results suggest that ETS exposure at home is associated in a dose-related manner with lower serum HDL-C levels in primary school children. In addition, our results suggest that smoking in the presence of children who are not usually exposed to ETS increases the risk of arteriosclerosis. Given these findings, we strongly recommend the establishment of anti-passive-smoking measures.