Research Secondhand Smoke Exposure and Coronary Artery Calcification among Nonsmoking Participants of a Population-Based Cohort Frank Peinemann,1,2 Susanne Moebus,1 Nico Dragano,3 Stefan Möhlenkamp,4 Nils Lehmann,1 Hajo Zeeb,2 Raimund Erbel,4 Karl-Heinz Jöckel,1 and Barbara Hoffmann5 on behalf of the Heinz Nixdorf Recall Study Investigative Group 1Institute for Medical Informatics, Biometry, and Epidemiology, University Duisburg-Essen, Essen, Germany; 2Institute for Medical Biometry, Epidemiology, and Informatics, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany; 3Institute of Medical Sociology, Heinrich Heine University, Düsseldorf, Germany; 4West German Heart Center, University Hospital, University of Duisburg-Essen, Essen, Germany; 5Leibniz Research Institute for Environmental Medicine and Medical Faculty, University of Düsseldorf, Düsseldorf, Germany Background : Secondhand smoke (SHS) consists of fine particulate matter, carcinogens, and various toxins that affect large parts of the population. SHS increases the risk for acute cardio­ vascular events and may contribute to the development of atherosclerosis. o Bjectivs : We investigated the association of SHS with coronary artery calcification (CAC). Methods : In this crosss­ectional analysis, we used baseline data (2000 –2003) from 1,766 never­ smokers without clinically manifested coronary heart disease, 45–75 years of age, from the Heinz Nixdorf Recall Study, an ongoing, prospective, population­based cohort study in Germany. Self­ reported frequent SHS at home, at work, and in other places was assessed by questionnaire. CAC scores were derived based on electron­ beam computed tomography. We conducted multiple linear regression analysis using exposure to SHS as the explanatory variable and ln(CAC+1) as the response variable. We conducted logistic regression to estimate the odds ratio (OR) for presence of any CAC. words r esult : Frequent exposure to SHS was reported by 21.5% of participants. After adjustment for age, sex, and socioeconomic status, CAC + 1 was 21.1% [95% confidence interval (CI): –5.5%, 55.2%] higher in exposed than in unexposed participants. After adjusting for other cardiovascular risk factors, the association was attenuated (15.4%; 95% CI: –9.6%, 47.2%). SHS exposure was also associated with a CAC score > 0 (fully adjusted OR = 1.38; 95% CI: 1.03, 1.84). c onclusi : Self­ reported frequent exposure to SHS was associated with subclinical coronary atherosclerosis in our cross­ sectional study population. Considering the widespread exposure and the clinical relevance of coronary atherosclerosis, this result, if confirmed, is of public health importance. k ey : cardiovascular atherosclerosis, comparative risk assessment, environmental epi­ demiology, population health, secondhand smoke. Environ Health Perspect 119:1556–1561 (2011). http://dx.doi.org/10.1289/ehp.1003347 [Online 8 July 2011] Materials and Methods Study population. We investigated baseline data from an ongoing prospective population- based Caucasian cohort study in Germany (Heinz Nixdorf Recall Study). Details about design (Schmermund et al. 2002) and about baseline recruitment and population-based assessment of subclinical atherosclerosis (Schmermund et al. 2006) have been previ- ously reported. In short, baseline data from 4,814 participants 45–75 years of age were collected from 2000 to 2003. The original cohort aims to clarify the predictive value of coronary calcification for future cardiac events in a random population sample. We used baseline data from 1,766 never-smokers (34% men) with available information on exposure and outcome (Figure 1). Data from Address correspondence to B. Hoffmann, IUF Leibniz Research Institute for Environmental Medicine, Department of Epidemiology, Auf’m Hennekamp 50, 40225 Düsseldorf, Germany. Telephone: 49-211-3389313. Fax: 49-211-3389283. E-mail: b.hoffmann@uni-duesseldorf.de We thank the staff of the Heinz Nixdorf Recall Study, in particular U. Roggenbuck and S. Hertel. We thank D. Grönemeyer and R. Seibel for their valuable contribution in electron-beam computed tomography imaging. Advisory board of the Heinz Nixdorf Recall Study: T. Meinertz, Hamburg (chair); M. Blettner, Mainz, Germany; C. Bode, Freiburg, Germany; P.J. de Feyter, Rotterdam, the Netherlands; B. Güntert, Hall i.T., Austria; F. Gutzwiller, Zürich, Switzerland; H. Heinen, Bonn, Germany; O. Hess, Bern, Switzerland; B. Klein, Essen, Germany; H. Löwel, Neuherberg, Germany; M. Reiser, Munich, Germany; G. Schmidt, Essen, Germany; M. Schwaiger, Munich, Germany; C. Steinmüller, Bonn, Germany; T. Theorell, Stockholm, Sweden; and S.N. Willich, Berlin, Germany. This work was supported by the Heinz Nixdorf Foundation, Essen, Germany; the German Ministry of Education and Science, Berlin, Germany; and Imatron Inc., South San Francisco, CA, USA, which produced the electron-beam computed tomogra- phy scanners. Assessment of psychosocial factors and neighborhood level information was funded by the German Research Foundation, Bonn, Germany (projects SI 236/8-1 and SI 236/9-1). Laboratory equipment was provided by Sarstedt AG & Co., Nuembrecht, Germany. The authors declare they have no actual or potential competing financial interests. Received 16 December 2010; accepted 8 July 2011. ovlume 119 | number 11 | November 2011 • Environmental Health Perspectives Secondhand smoke (SHS) is the combination of smoke given off by the burning end of a tobacco product and the smoke exhaled by the smoker. The Germany National Health Survey 1998 estimated a prevalence of 55% for regular exposure to SHS in nonsmokers 18–79 years of age in Germany (Deutsches Krebsforschungszentrum 2005). Exposure to SHS is a relevant health problem; for exam- ple, cardiovascular event rates are 20–50% higher in subjects exposed to SHS than in those not exposed, causing an estimated 40,000–50,000 deaths from coronary heart disease (CHD) in the United States each year (U.S. Department of Health and Human Services 2006). Biological mechanisms pro- posed to explain adverse effects of SHS on the cardiovascular system include the elicitation of oxidative stress, inflammatory responses, activation of platelets, endothelial dysfunc- tion, and changes of the autonomic balance (Barnoya and Glantz 2005). Studies focusing on clinical events can- not distinguish between the triggering of acute events and chronic processes leading to the development and progression of atherosclerosis as the underlying pathology for cardiovascular 1556 events. It is therefore necessary to investigate measures of subclinical atherosclerosis to assess the potential influence on the underlying dis- ease process. Some studies suggest that SHS contributes to the development and progres- sion of atherosclerosis. Recent studies found associations between SHS and carotid artery intimal-medial thickness (Knoflach et al. 2009), aortic plaque (Kiechl et al. 2002), ankle-brachial index (He et al. 2008), arterial stiffness (Mack et al. 2003), and endothelial function (Leone and Balbarini 2008) as indica- tors of subclinical atherosclerosis, but not all studies are consistent with a positive associa- tion (Agarwal 2009). Whether SHS is associ- ated with coronary atherosclerosis has not yet been investigated. Coronary artery calcifica- tion/calcium (CAC) detected by electron-beam computed tomography is a reliable measure of the degree of coronary atherosclerosis and is associated with cardiac events (Erbel et al. 2010; Folsom et al. 2008; Greenland et al. 2007). The aim of the present study was to investigate the association of exposure to SHS and the degree of CAC as a measure of coro- nary atherosclerosis in participants of a popula- tion-based cohort in Germany.