Childhood environmental tobacco smoke exposure: a smoking gun for atherosclerosis in adulthood.

I n the 1960s, the US Surgeon General and American Heart Association issued reports warning of the dangers of smoking on fatal coronary artery disease. Since those early publications , 32 US Surgeon General reports and thousands of studies have been released exposing the harmful effects of cigarette smoking on cardiovascular health. Yet, more than a half a century later, the toxic legacy continues to unravel. Cigarette smoking is now well established as a causal risk factor for cardiovascular disease (CVD). Pooled data from almost 1 million people reveals that the risk of ischemic heart disease for current smokers is 2.6 times (95% confidence interval [CI], 2.4–2.7) higher for men and 3.0 times (95% CI, 2.8–3.2) higher for women compared with nonsmokers. 6 Secondhand smoke (SHS) exposure has emerged as a significant risk factor for CVD among nonsmokers, demonstrating a dose-dependent relationship with higher risk of CVD among those with higher SHS exposure. In epidemiological studies, the risk of coronary heart disease among SHS-exposed nonsmoking adults is 1.25 times (95% CI, 1.17–1.32) higher than unexposed adults. Although the risks of concurrent SHS exposure are clear, the deleterious cardiovascular health effects of remote SHS exposure, especially from SHS exposure during childhood, have been more difficult to demonstrate. Clinicians and public health professionals have unanswered questions about how to reduce exposure to risk factors during childhood that increase the risk of adult CVD. Are adults exposed to SHS in childhood at higher risk of CVD compared with those with a smoke-free childhood? Does the vascular damage observed in healthy nonsmoking young adults exposed to SHS persist decades later? 11,12 Can the residual risk of CVD events in excess of classic risk factors be partly explained by early life SHS exposure? Clearly, the immediate effects of SHS on children are overwhelmingly harmful. Increased respiratory illnesses and infections from childhood SHS exposure result in extra emergency department visits and medical expenditures. The detrimental health outcomes in childhood because of concurrent SHS exposure are sufficient to warrant action; however, the connection between remote SHS exposure in childhood and heart disease in adulthood remains poorly characterized. Previous studies have not been able to detect an association between self-reported cumulative lifetime SHS exposure and risk of myocardial infarc-tion. 15 Childhood may be an especially vulnerable period for lasting and permanent harmful cardiovascular effects of SHS. 16 Incomplete pediatric exposure ascertainment likely limits the ability of previous studies …