Controlled exposure of healthy young volunteers to ozone causes cardiovascular effects.
BACKGROUND
Recent epidemiology studies have reported associations between short-term ozone exposure and mortality. Such studies have previously reported associations between airborne particulate matter pollution and mortality, and support for a causal relationship has come from controlled-exposure studies that describe pathophysiological mechanisms by which particulate matter could induce acute mortality. In contrast, for ozone, almost no controlled-human-exposure studies have tested whether ozone exposure can modulate the cardiovascular system.


RESULTS
Twenty-three young healthy individuals were exposed in a randomized crossover fashion to clean air and to 0.3-ppm ozone for 2 hours while intermittently exercising. Blood was obtained immediately before exposure, immediately afterward, and the next morning. Continuous Holter monitoring began immediately before exposure and continued for 24 hours. Lung function was performed immediately before and immediately after exposure, and bronchoalveolar lavage was performed 24 hours after exposure. Immediately after ozone exposure, we observed a 98.9% increase in interleukin-8, a 21.4% decrease in plasminogen activator inhibitor-1, a 51.3% decrease in the high-frequency component of heart rate variability, and a 1.2% increase in QT duration. Changes in interleukin-1B and plasminogen activator inhibitor-1 were apparent 24 hours after exposure. In agreement with previous studies, we also observed ozone-induced drops in lung function and an increase in pulmonary inflammation.


CONCLUSIONS
This controlled-human-exposure study shows that ozone can cause an increase in vascular markers of inflammation and changes in markers of fibrinolysis and markers that affect autonomic control of heart rate and repolarization. We believe that these findings provide biological plausibility for the epidemiology studies that associate ozone exposure with mortality.


BACKGROUND
URL: http://www.clinicaltrials.gov. Unique identifier: NCT01492517.
National Health and Environmental Effects, Research Laboratory MD 58D, US EPA, Research Triangle Park, NC 27711, USA. devlin.robert@epa.gov
Robert B
RB
Devlin
Kelly E
KE
Duncan
Melanie
M
Jardim
Michael T
MT
Schmitt
Ana G
AG
Rappold
David
D
Diaz-Sanchez
D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects; D002319:Cardiovascular System / Q000187:drug effects / Q000378:metabolism; D018592:Cross-Over Studies; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D008297:Male; D010126:Ozone / Q000008:administration & dosage* / Q000009:adverse effects*; D055815:Young Adult
D000393:Air Pollutants; D010126:Ozone