title: ECG parameters and exposure to carbon ultrafine particles in young healthy subjects.
abstract: The mechanisms underlying the association between air pollution and cardiovascular morbidity and mortality are unknown. This study aimed to determine whether controlled exposure to elemental carbon ultrafine particles (UFP) affects electrocardiogram (ECG) parameters describing heart rate variability; repolarization duration, morphology, and variability; and changes in the ST segment. Two separate controlled studies (12 subjects each) were performed using a crossover design, in which each subject was exposed to filtered air and carbon UFP for 2 hours. The first protocol involved 2 exposures to air and 10 microg/m(3) (approximately 2 x 10(6) particles/cm(3), count median diameter approximately 25 nm, geometric standard deviation approximately 1.6), at rest. The second protocol included 3 exposures to air, 10, and 25 microg/m(3) UFP (approximately 7 x 10(6) particles/cm(3)), with repeated exercise. Each subject underwent a continuous digital 12-lead ECG Holter recording to analyze the above ECG parameters. Repeated measures analysis of variance (ANOVA) was used to compare tested parameters between exposures. The observed responses to UFP exposure were small and generally not significant, although there were trends indicating an increase in parasympathetic tone, which is most likely also responsible for trends toward ST elevation, blunted QTc shortening, and increased variability of T-wave complexity after exposure to UFP. Recovery from exercise showed a blunted response of the parasympathetic system after exposure to UFP in comparison to air exposure. In conclusion, transient exposure to 10-25 microg/m(3) ultrafine carbon particles does not cause marked changes in ECG-derived parameters in young healthy subjects. However, trends are observed indicating that some subjects might be susceptible to air pollution, with a response involving autonomic modulation of the heart and repolarization of the ventricular myocardium.
authors.affiliation: Department of Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Jean Philippe
authors.initials: JP
authors.lastname: Couderc
authors.forename: Günter
authors.initials: G
authors.lastname: Oberdörster
authors.forename: David
authors.initials: D
authors.lastname: Chalupa
authors.forename: Christopher
authors.initials: C
authors.lastname: Cox
authors.forename: Li-Shan
authors.initials: LS
authors.lastname: Huang
authors.forename: Annette
authors.initials: A
authors.lastname: Peters
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Utell
authors.forename: Mark W
authors.initials: MW
authors.lastname: Frampton
mesh_terms: D000328:Adult; D002244:Carbon / Q000009:adverse effects* / Q000737:chemistry; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory; D004781:Environmental Exposure; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D010316:Particle Size; D052638:Particulate Matter; D012828:Silicones; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D012828:Silicones; D002244:Carbon