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Health and Environmental Effects Research

ORD Scientists’ Study on Immediate Impacts of Air Pollution on Heart Subject of Recent Environmental Health Perspectives Article

Mehdi S. Hazari, a postdoctoral fellow in the Cardiopulmonary and Immunotoxicology Branch of NHEERL’s Environmental Public Health Division (EPHD), is the lead author of a paper published by Environmental Health Perspectives in March 2011. The paper describes a study in which Dr. Hazari and co-workers took a new approach in studying the immediate impacts of air pollution on the heart, one that is based on the hypothesis that, even in the absence of visible symptoms, air pollution conditions individuals with underlying cardiovascular disease and increases their risk of a future triggered adverse response. This study employed the aconitine “challenge” test, which Dr. Hazari developed to trigger cardiac arrhythmia in rats, to examine whether a single inhalation exposure to diesel exhaust (DE), a complex multipollutant, would increase the risk of arrhythmia being triggered in a rat model of hypertension. The results of this study indicate that a single exposure to 150 mg/m3 DE, which is a lower concentration and more relevant to humans, increases the sensitivity to developing arrhythmia, and that much of this response is mediated by the gases present in DE. It also was found that DE stimulated airway irritant nerves bearing the TRPA1 channel, which subsequently caused autonomic nervous system/homeostatic imbalance and, thereby, resulted in this heightened arrhythmogenesis. This is the first study to show such latent effects of air pollution and to demonstrate that acute irritation in the respiratory system can result in increased risk of adverse events in the heart. This has regulatory implications because it demonstrates that a single exposure to a multipollutant can trigger effects in the heart, particularly in susceptible individuals, and, thus, this phenomenon should be taken into account in standard setting.

Citation: Mehdi S. Hazari, Najwa Haykal-Coates, Darrell W. Winsett, Q. Todd Krantz, Charly King, Daniel L. Costa, and Aimen K. Farraj. TRPA1 and Sympathetic Activation Contribute to Increased Risk of Triggered Cardiac Arrhythmias in Hypertensive Rats Exposed to Diesel Exhaust. Environmental Health Perspectives, published electronically ahead of print on March 4, 2011.

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