Project at a Glance
Title: Mechanisms of particulate toxicology: systemic effects in sensitive animal models and susceptible humans.
Principal Investigator / Author(s): Kleinman, M. T.
Contractor: UC Irvine
Contract Number: 99-316
Research Program Area: Health & Exposure
Topic Areas: Health Effects of Air Pollution, Toxic Air Contaminants
Particle-induced lung injury and heart responses were measured in young adult and geriatric (senescent) rats exposed to laboratory generated particles composed of elemental carbon and ammonium nitrate. The particle compositions and concentrations used were consistent with ambient aerosols collected and characterized in California. This study was part of a coordinated multicampus program. The biological responses studied focused on cardiophysiologic factors (changes in blood pressure, variability in heart rate and abnormal heart rhythms) in the animal studies and macrophage superoxide production in the human studies. Acute (4 hour) single day exposures to particles alone were compared with the effects of a mixture of particles and ozone at approximately the same particle concentrations. Both exposures produced decreases in blood pressure and heart rate. Blood pressure changes (differences between pre-exposure and post-exposure levels) were significantly different from controls. Heart rate was decreased by pollutant exposure but the response was not statistically significant. The changes induced by single day exposure to particles alone were not significantly different from those induced by the single day ozone + particle mixture. Thus, the effects observed may be those of the particles and not due to the presence of ozone in the mixture. Repeated 3-day (4 hour per day) exposures to particles caused changes in heart rate and blood pressure that were statistically significant immediately post-exposure, but there were no changes in baseline levels measured 20 hours after exposure. Heart rate variability was not significantly changed after a single exposure to particles, but showed progressive reduction after 2 and three days of consecutive exposure, compared to clean air exposures.
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