| PM Source Apportionment for Short-Term Cardiac Function
Changes
in ApoE-/- Mice Morton Lippmann,1 Jiang-Shiang Hwang,2 Polina Maciejczyk,1 and
Lung-Chi Chen1 1New York University School of Medicine, Tuxedo, New York,
USA; 2Institute of Statistical Science, Academia Sinica, Taipei,
Taiwan Abstract
Daily rates of cardiovascular mortality and morbidity are have been associated with daily variations in fine particulate matter (aerodynamic diameter ≤ 2.5 µm, PM2.5) , but little is known about the influences of the individual source-related PM2.5 categories or the temporal lags for the effects. We investigated heart rate (HR) and HR variability (HRV) data collected during a 5-month study involving 6 hr/day, 5 day/week exposures of normal (C57) mice and a murine model for atherosclerotic disease (ApoE-/-) in Sterling Forest (Tuxedo, New York, USA) . The mice were exposed to concentrated ambient particles (PM2.5 concentrated 10-fold, producing an average of 113 µg/m3) . Daily 6-hr PM2.5 air samples were analyzed by X-ray fluorescence, permitting attribution to major PM source categories [secondary sulfate (SS) , resuspended soil (RS) , residual oil (RO) combustion, and other, largely due to motor vehicle traffic]. We examined associations between these PM2.5 components and both HR and HRV for three different daily time periods: during exposure, the afternoon after exposure, and late at night. For HR there were significant transient associations for RS during exposure, and for SS in the afternoon after exposure. For HRV, there were comparable associations with RO in the afternoon after exposure and for both SS and RS late at night. The biologic bases for these associations and their temporal lags are not known but may be related to the differential solubility of the biologically active PM components at the respiratory epithelia and their access to cells that release mediators that reach the cardiovascular system. Clearly, further research to elucidate the underlying processes is needed. Key words: concentrated ambient particulate matter, heart rate, heart rate variability, motor vehicle pollution, PM2.5, residual oil, resuspended soil, secondary sulfate, source apportionment. Environ Health Perspect 113: 1575-1579 (2005) . doi:10.1289/ehp.8091 available via http://dx.doi.org/ [Online 5 July 2005]
Address correspondence to M. Lippmann, New York University School of Medicine, 57 Old Forge Rd., Tuxedo, NY 10987 USA. Telephone: (845) 731-3558. Fax: (845) 351-5472. E-mail: lippmann@env.med.nyu.edu This research was conducted as part of the New York University Center for Particulate Matter Health Effects Research supported by grant R827351 from the U.S. Environmental Protection Agency and is part of a basic environmental health science center program supported by the National Institute of Environmental Health Sciences (grant ES 00260) . The authors declare they have no competing financial interests. Received 28 February 2005 ; accepted 5 July 2005.
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