The Association of Particulate Air Metal Concentrations with Heart Rate Variability Shannon R. Magari,1 Joel Schwartz,2 Paige L. Williams,3 Russ Hauser,1 Thomas J. Smith,1,4 and David C. Christiani1,5 1Occupational Health Program, Department of Environmental Health, 2Environmental Epidemiology Program, Department of Environmental Health, 3Department of Biostatistics, and 4Environmental Science and Engineering Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 5Pulmonary and Critical Care Unit, Department of Medicine, Massachusetts General Abstract Numerous studies show an association between particulate air pollution and adverse health effects. Particulate matter is a complex mixture of elemental carbon, ammonium, sulfates, nitrates, organic components, and metals. The mechanisms of action of particulate matter 2.5 µm in mean aerodynamic diameter (PM2.5) , as well as the constituents responsible for the observed cardiopulmonary health effects, have not been identified. In this study we focused on the association between the metallic component of PM2.5 and cardiac autonomic function based on standard heart rate variability (HRV) measures in an epidemiologic study of boilermakers. Thirty-nine male boilermakers were monitored throughout a work shift. Each subject wore an ambulatory electrocardiogram (Holter) monitor and a personal monitor to measure PM2.5. We used mixed-effects models to regress heart rate and SDNN index (standard deviation of the normal-to-normal) on PM2.5 and six metals (vanadium, nickel, chromium, lead, copper, and manganese) . There were statistically significant mean increases in the SDNN index of 11.30 msec and 3.98 msec for every 1 µg/m3 increase in the lead and vanadium concentrations, respectively, after adjusting for mean heart rate, age, and smoking status. Small changes in mean heart rate were seen with all exposure metrics. The results of this study suggest an association between exposure to airborne metals and significant alterations in cardiac autonomic function. These results extend our understanding of the adverse health effects of the metals component of ambient PM2.5. Key words: cardiac autonomic function, heart rate variability, metal exposure, occupational exposures, particulate matter. Environ Health Perspect 110:875-880 (2002) . [Online 22 July 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110p875-880magari/ abstract.html Address correspondence to D.C. Christiani, Occupational Health Program, Harvard School of Public Health, Building 1, Room 1402, 665 Huntington Avenue, Boston, MA 02115 USA. Telephone: (617) 432-3323. Fax: (617) 432-0219. E-mail: dchris@hohp.harvard.edu We acknowledge the invaluable assistance of S. Houk, C. Amarasiriwardena, N. Lupoli, J. Y. Kim, E. Rodrigues, and J. Jackson for their help in data collection and laboratory analyses ; S. Mucci for database management and field data collection ; and D. Miller and L. Pothier for database management and statistical programming. We also thank the staff and members of the International Brotherhood of Boilermakers, Iron Shipbuilders, Blacksmiths, Forgers and Helpers of Lodge No. 29, Quincy, Massachusetts. This work was supported by National Institutes of Health grants ES09860 and ES00002, National Institute of Occupational Safety and Health grant OH00152, and The Mickey Leland Air Toxics Center. S.R. Magari was supported by NIH Training Grant T32 ES07069. Received 2 November 2001 ; accepted 15 February 2002. The full version of this article is available for free in HTML or PDF formats. |