| Prospective Analysis of Traffic Exposure as a Risk Factor for Incident Coronary Heart Disease: The Atherosclerosis Risk in Communities (ARIC) Study Haidong Kan,1,2 Gerardo Heiss,3 Kathryn M. Rose,3 Eric A. Whitsel,3,4 Fred Lurmann,5 and Stephanie J. London1 1Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA; 2Department of Environmental Health, School of Public Health, Fudan University, Shanghai, China; 3Department of Epidemiology, School of Public Health, and 4Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; 5Sonoma Technology Inc., Petaluma, California, USA Abstract
Background: For people living close to busy roads, traffic is a major source of air pollution. Few prospective data have been published on the effects of long-term exposure to traffic on the incidence of coronary heart disease (CHD) . Objectives: In this article, we examined the association between long-term traffic exposure and incidence of fatal and nonfatal CHD in a population-based prospective cohort study. Methods: We studied 13,309 middle-age men and women in the Atherosclerosis Risk in Communities study, without previous CHD at enrollment, from 1987 to 1989 in four U.S. communities. Geographic information system–mapped traffic density and distance to major roads served as measures of traffic exposure. We examined the association between traffic exposure and incident CHD using proportional hazards regression models, with adjustment for background air pollution and a wide range of individual cardiovascular risk factors. Results: Over an average of 13 years of follow-up, 976 subjects developed CHD. Relative to those in the lowest quartile of traffic density, the adjusted hazard ratio (HR) in the highest quartile was 1.32 [95% confidence interval (CI) , 1.06–1.65 ; p-value for trend across quartiles = 0.042]. When we treated traffic density as a continuous variable, the adjusted HR per one unit increase of log-transformed density was 1.03 (95% CI, 1.01–1.05 ; p = 0.006) . For residents living within 300 m of major roads compared with those living farther away, the adjusted HR was 1.12 (95% CI, 0.95–1.32 ; p = 0.189) . We found little evidence of effect modification for sex, smoking status, obesity, low-density lipoprotein cholesterol level, hypertension, age, or education. Conclusion: Higher long-term exposure to traffic is associated with incidence of CHD, independent of other risk factors. These prospective data support an effect of traffic-related air pollution on the development of CHD in middle-age persons. Key words: air pollution, coronary disease, traffic. Environ Health Perspect 116:1463–1468 (2008) . doi:10.1289/ehp.11290 available via http://dx.doi.org/ [Online 8 July 2008]
Address correspondence to S.J. London, Epidemiology Branch, National Institute of Environmental Health Sciences, P.O. Box 12233, Mail Drop A3-05, Research Triangle Park, NC 27709 USA. Telephone: (919) 541-5772. Fax: (919) 541-2511. E-mail: london2@niehs.nih.gov Supplemental Material is available online at http://www.ehponline.org/members/2008/11290/suppl.pdf The Atherosclerosis Risk in Communities study is a collaborative study supported by National Heart, Lung, and Blood Institute contracts N01-HC-55015, N01-HC-55016, N01-HC-55018, N01-HC-55019, N01-HC-55020, N01-HC-55021, and N01-HC-55022. This work was also supported by Z01 ES043012 from the Intramural Research Program, National Institute of Environmental Health Sciences. The authors declare they have no competing financial interests. Received 23 January 2008 ; accepted 8 July 2008.
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