| Diabetes, Obesity, and Hypertension May Enhance Associations between Air Pollution and Markers of Systemic Inflammation Sara D. Dubowsky,1 Helen Suh,1 Joel Schwartz,1,2,3 Brent A. Coull,4 and Diane R. Gold1,3 1Department of Environmental Health, and 2Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA; 3Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA; 4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA
Abstract
Airborne particulate matter (PM) may lead to increased cardiac risk through an inflammatory pathway. Therefore, we investigated associations between ambient PM and markers of systemic inflammation among repeated measures from 44 senior citizens (≥ 60 years of age) and examined susceptibility by conditions linked to chronic inflammation. Mixed models were used to identify associations between concentrations of fine PM [aerodynamic diameter ≤ 2.5 µm (PM2.5) ] averaged over 1–7 days and measures of C-reactive protein (CRP) , interleukin-6 (IL-6) , and white blood cells (WBCs) . Effect modification was investigated for diabetes, obesity, hypertension, and elevated mean inflammatory markers. We found positive associations between longer moving averages of PM2.5 and WBCs across all participants, with a 5.5% [95% confidence interval (CI) , 0.10 to 11%] increase per interquartile increase (5.4 µg/m3) of PM2.5 averaged over the previous week. PM2.5 and CRP also exhibited positive associations among all individuals for averages longer than 1 day, with the largest associations for persons with diabetes, obesity, and hypertension. For example, an interquartile increase in the 5-day mean PM2.5 (6.1 µg/m3) was associated with a 14% increase in CRP (95% CI, –5.4 to 37%) for all individuals and an 81% (95% CI, 21 to 172%) increase for persons with diabetes, obesity, and hypertension. Persons with diabetes, obesity, and hypertension also exhibited positive associations between PM2.5 and IL-6. Individuals with elevated mean inflammatory markers exhibited enhanced associations with CRP, IL-6, and WBCs. We found modest positive associations betweenPM2.5 and indicators of systemic inflammation, with larger associations suggested for individuals with diabetes, obesity, hypertension, and elevated mean inflammatory markers. Key words: air pollution, C-reactive protein, inflammation, metabolic syndrome, particulate matter, susceptibility. Environ Health Perspect 114:992–998 (2006) . doi:10.1289/ehp.8469 available via http://dx.doi.org/ [Online 27 February 2006]
Address correspondence to S.D. Dubowsky, Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 302, Box 354965, Seattle, WA 98105-8123 USA. Telephone: (206) 221-5932. Fax: (206) 685-3875. E-mail: dubowsky@u.washington.edu We are thankful for the input ofD.W. Dockery, P. Koutrakis, F.E. Speizer, N. Rifai, A. Zanobetti, A.A. Litonjua, and E.B. Rimm and vital contributions of J.R. Turner, S. Forrester, C. Peter, M. Rubin, G. Bradwin, our field staff, and participants. This work was funded by the National Institute of Environmental Health Sciences (grants ES09825 and ES00002) , the U.S. Environmental Protection Agency (R827353) , and the Electric Power Research Institute (EPRI ; W09207) . H.S. previously received grant support from EPRI ; however, her freedom to design, conduct, interpret, and publish her research was not compromised. The remaining authors declare they have no competing financial interests. Received 5 July 2005 ; accepted 27 February 2006.
Correction In Table 1 of the manuscript published online, the ranges of CRP for both "Yes" and "No" under "Statin therapy" were incorrect. These values have been corrected here.
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