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Final Report: Effects on Mice of Exposure to Ozone and Ambient Particle Pollution
EPA Grant Number: R828112C106Subproject: this is subproject number 106 , established and managed by the Center Director under grant R828112
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Health Effects Institute
Center Director: Greenbaum, Daniel S.
Title: Effects on Mice of Exposure to Ozone and Ambient Particle Pollution
Investigators: Kobzik, Lester
Institution: Harvard School of Public Health
EPA Project Officer: Katz, Stacey
Project Period: April 1, 2000 through March 31, 2005
RFA: Health Effects Institute (1996)
Research Category: Particles and Diesel Engine Exhaust , Public/Private Partnership Center
Description:
Objective:Epidemiologic studies have indicated that small shortterm increases in the concentration of particulate matter (PM), the complex and variable mixture of particles in the atmosphere, are associated with short-term increases in human morbidity and mortality. Particularly at risk are elderly people and individuals with compromised cardiac or airway function, such as those with asthma.
Plausible biologic mechanisms that would link lowlevel PM exposure with pathophysiologic effects or would explain why people with asthma may be more sensitive than healthy individuals to PM exposure have not yet been established. Because PM is present with other airborne pollutants, it is also important to evaluate the health effects of simultaneous exposure to multiple pollutants.
Summary/Accomplishments (Outputs/Outcomes):Dr Lester Kobzik and colleagues at Harvard School of Public Health used a mouse model of asthma to evaluate how inhaling pollutants affects the airways. The mice were sensitized to the allergen ovalbumin and later challenged with the same aerosol to induce a lung condition in the mice similar to that found in people with asthma. This mouse model of asthma has some appropriate characteristics of human asthma (most notably, allergeninduced airway inflammation), but lacks others (eg, hypersecretion of mucus).
The investigators studied concentrated ambient particles (CAPs) of respirable size and ozone, a gaseous pollutant known to cause airway inflammation and to compromise respiratory function. Kobzik hypothesized that exposure to CAPs plus ozone would cause a synergistic (or greater-than-additive) response. To maximize possible CAPs effects, he used a new version of the Harvard Ambient Particle Concentrator to deliver particles at concentrations that were many times higher than those in ambient Boston air (varying from 12-fold to 67-fold on different days of the study). He exposed mice to ozone at 0.3 ppm, a concentration similar to levels found in urban ambient air. Kobzik also measured daily levels of elements in the PM and CAPs so that, if he found a change in airway function, he could associate it with the elemental composition of the particles.
Kobzik and colleagues evaluated two endpoints associated with the asthmatic response: airway responsiveness and airway inflammation. They evaluated airway responsiveness by challenging the mice with various aerosol concentrations of methacholine, a bronchoconstrictor or agent that narrows the small airways. Mice were challenged with the methacholine aerosol immediately after a 5-hour exposure to one or both pollutants (CAPs and ozone). In some experiments, airway responsiveness was also measured beginning 24 hours after the exposure.
One valuable aspect of the investigators? approach was that they used whole-body plethysmography to measure airway responsiveness. This technique is noninvasive and allows a large number of animals to be tested repeatedly. They placed a mouse in an exposure chamber that was connected to a reference chamber; as the mouse breathed the methacholine entering the exposure chamber, the difference in pressure between the two chambers was measured. From these pressure readings, they derived a recently defined parameter known as enhanced (enh) pause (P), or Penh.
They also evaluated the effects of the pollutants on airway inflammation 24 or 48 hours after the exposure by assessing cells in bronchoalveolar lavage fluid to determine whether (1) the total number of cells increased, and (2) the numbers of cells associated with an inflammatory response, such as eosinophils, increased.
In addition, Kobzik and colleagues evaluated in vitro how concentrated particles might induce the synthesis of cellular mediators associated with inflammation. They did this by resuspending particles collected on different days of the in vivo exposure study, adding them to lung cells (derived from rats), and measuring 24 hours later the levels of tumor necrosis factor a (TNF-a) and macrophage inflammatory protein?2 (MIP-2) produced by the cells.
Kobzik and colleagues used four statistical approaches to evaluate the effects of pollutants on Penh. One approach indicated that CAPs (without ozone) slightly increased Penh immediately after exposure, but values returned to baseline by 24 hours later. This suggests that the particles? effect on Penh is small and transient, which is consistent with the effects of various air pollutant components on airway function that have been described in other studies. Ozone alone did not increase Penh after exposure. Only one of the four statistical approaches suggested a synergistic effect of CAPs plus ozone, and the investigators were appropriately cautious in interpreting this finding.
Another approach?factor analysis?suggested that different elemental components of the CAPs were associated with different effects on Penh; in particular, that Penh increased on days with high aluminum and silicate levels in the particles. Some particle components also appeared to be associated with decreased Penh. These findings support the idea that the magnitude of a specific health outcome on a particular day is a function of the aggregate elemental composition and concentration of pollutants in ambient air on that day.
In vivo, CAPs had little or no effect on the numbers of cells in bronchoalveolar lavage fluid 24 or 48 hours after exposure; ozone slightly increased cell numbers in a pattern consistent with inflammation, which as to be expected. In vitro, resuspended CAPs induced the synthesis of high levels (frequently more than 1000-fold increases above background levels) of TNF-a and MIP-2 from rat lung cells. These results confirm previous findings from the investigators that suggest that components present in resuspended particles can induce the release of mediators associated with lung inflammation.
Overall, the results indicate that respirable PM, even when concentrated to levels higher than normally found in ambient air, had little effect on the airway mechanical and inflammatory parameters measured in this small animal model of asthma. In addition, the effects of exposure to CAPs plus ozone did not achieve synergy that could be convincingly demonstrated. Because this mouse model mimics only some characteristics of human asthma, which is a complex illness, we cannot be certain to what extent these results may or may not predict the effects of ambient PM and ozone exposure on people with asthma.
Supplemental Keywords:Air, ambient air quality, air toxics, epidemiology, health effects, particulate matter, biochemistry, motor vehicle emissions, diesel exhaust, animal models, ozone, pathology. , Air, Scientific Discipline, Health, RFA, Toxicology, Risk Assessments, Health Risk Assessment, air toxics, Atmospheric Sciences, Biochemistry, particulate matter, Environmental Chemistry, mobile sources, automotive exhaust, exposure assessment, exposure and effects, Acute health effects, ambient air quality, cardiovascular vulnerability, indoor air quality, mortality, diesel exhaust, ozone, aerosol particles, cardiopulmonary responses, human health risk, lung inflammation, lung injury, genetic susceptibility, air pollutants, chronic health effects, human health effects, particulates, diesel exhaust particles, ambient particle health effects, acute lung injury, air pollution, environmental risks, exposure, ambient particle pollution, human exposure, PM, pulmonary disease
Progress and Final Reports:
Original Abstract
Main Center Abstract and Reports:
R828112 Health Effects Institute
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R828112C042 Does Inhalation of Methanol Vapor Affect Human Neurobehavior?
R828112C043 Human Responses to Nitrogen Dioxide
R828112C044 The Role of Inflammation in Ozone-Induced Lung Injury
R828112C045 How Does Exercise Affect the Dose of Inhaled Air Pollutants?
R828112C046 How Do Chemicals in Diesel Engine Exhaust Damage DNA?
R828112C047 Effect of Nitrogen Dioxide on Bacterial Respiratory infection
in Mice
R828112C048 Effects of Ozone Exposure on Airway Epithelium
R828112C049 Inhalation of Aldehydes and Effects on Breathing
R828112C050 Does Ozone Cause Precancerous Changes in Cells?
R828112C051 Effects of Formaldehyde on Human Airway Epithelial Cells Exposed in a Novel Culture System
R828112C052 Carbon Monoxide and Cardiac Arrhythmias
R828112C053 Effects of Formaldehyde and Particle-Bound Formaldehyde on Lung Macrophage Functions
R828112C054 Mechanisms for Protecting Lung Epithelial Cells Against Oxidant Injury
R828112C055 Relationship of Nitropyrene-Derived DNA Adducts to Carcinogenesis
R828112C056 Particle Trap Effects on Heavy-Duty Diesel Engine Emissions
R828112C057 Carbon Monoxide and Atherosclerosis
R828112C058 Nitrogen Dioxide and Respiratory Illness in Children
R828112C059 Noninvasive Methods for Measuring Ventilation in Mobile Subjects
R828112C060 Oxidant Air Pollutants and Lung Cancer: An Animal Model
R828112C061 Detection of Carcinogen-DNA Adducts: Development of New Methods
R828112C062 Effects of Carbon Monoxide on Heart Muscle Cells
R828112C063 Development of Personal Ozone Samplers: Three Approaches
R828112C064 Development of Biomarkers to Monitor Carcinogen Exposure
R828112C065 Effects of Prolonged Ozone Inhalation on Collagen Structure and Content in Rat Lungs
R828112C065II Prolonged Ozone Exposure and the Contractile Properties of Isolated Rat Airways
R828112C065III Changes in Complex Carbohydrate Content and Structure in Rat Lungs Caused by Prolonged Ozone Inhalation
R828112C065IV Genetic Control of Connective Tissue Protein Synthesis After Prolonged Ozone Inhalation
R828112C065V Pulmonary Function Alterations in Rats After Chronic Ozone Inhalation
R828112C065VII Prolonged Ozone Exposure Leads to Functional and Structural Changes in the Rat Nose
R828112C065VIII - IX Studies of Changes in Lung Structure and Enzyme Activities
in Rats After Prolonged Exposure to Ozone
R828112C065X An Innovative Approach to Analyzing Multiple Experimental Outcomes: A Case Study of Rats Exposed to Ozone
R828112C065XI The Consequences of Prolonged Inhalation of Ozone on Rats:
An Integrative Summary of the Results of Eight Collaborative Studies
R828112C066 Interactive Effects of Nitropyrenes in Diesel Exhaust
R828112C067 Detection of Formaldehyde–DNA Adducts: Development of New Methods
R828112C068I Comparison of the Carcinogenicity of Diesel Exhaust and Carbon Black in Rat Lungs
R828112C068II An Investigation of DNA Damage in the Lungs of Rats Exposed to Diesel Exhaust
R828112C068III No Evidence For Genetic Mutations Found In Lung Tumors From Rats Exposed To Diesel Exhaust or Carbon Black
R828112C069 Noninvasive Determination of Respiratory Ozone Absorption: The Bolus-Response Method
R828112C070 The Effects of Inhaled Oxidants and Acid Aerosols on Pulmonary Function
R828112C071 Biochemical Consequences of Ozone Reacting with Membrane Fatty Acids
R828112C072 DNA Mutations in Rats Treated with a Carcinogen Present in Diesel Exhaust
R828112C073 Developmental Neurotoxicity of Inhaled Methanol in Rats
R828112C074 Methanol Distribution in Non Pregnant and Pregnant Rodents
R828112C075 Is Increased Mortality Associated with Ozone Exposure in Mexico City?
R828112C076 Effects of Fuel Modification and Emission Control Devices on Heavy-Duty Diesel Engine Emissions
R828112C077 Metabolic Studies in Monkeys Exposed to Methanol Vapors
R828112C078 Effects of Ozone on Pulmonary Function and Airway Inflammation in Normal and Potentially Sensitive Human Subjects
R828112C079 Improvement of a Respiratory Ozone Analyzer
R828112C080 Mechanism of Oxidative Stress from Low Levels of Carbon Monoxide
R828112C081 Long-Term Exposure to Ozone: Development of Methods to Estimate Past Exposures and Health Outcomes
R828112C082 Effects of Ambient Ozone on Healthy, Wheezy, and Asthmatic Children
R828112C083 Daily Changes in Oxygen Saturation and Pulse Rate Associated with Particulate Air Pollution and Barometric Pressure
R828112C084 Evaluation of The Potential Health Effects of the Atmospheric Reaction Products of Polycyclic Aromatic Hydrocarbons
R828112C085 Mechanisms of Response to Ozone Exposure: The Role of Mast Cells in Mice
R828112C086 Statistical Methods for Epidemiologic Studies of the Health Effects of Air Pollution
R828112C087 Development of New Methods to Measure Benzene Biomarkers
R828112C088 Alveolar Changes in Rat Lungs After Long-Term Exposure to Nitric Oxide
R828112C089 Effects of Prenatal Exposure to Inhaled Methanol on Nonhuman Primates and Their Infant Offspring
R828112C090 A Pilot Study of Potential Biomarkers of Ozone Exposure
R828112C091 Effects of Concentrated Ambient Particles on the Cardiac and Pulmonary Systems of Dogs
R828112C092 Cancer, Mutations, and Adducts in Rats and Mice Exposed to Butadiene and Its Metabolites
R828112C093 Effects of Concentrated Ambient Particles in Rats and Hamsters: An Exploratory Study
R828112C094I The National Morbidity, Mortality, and Air Pollution Study: Methods and Methodologic Issues
R828112C094II The National Morbidity, Mortality, and Air Pollution Study: Morbidity and Mortality from Air Pollution in the United States
R828112C095 Association of Particulate Matter Components with Daily Mortality and Morbidity in Urban Populations
R828112C096 Acute Pulmonary Effects of Ultrafine Particles in Rats and Mice
R828112C097 Identifying Subgroups of the General Population That May Be Susceptible to Short-Term Increases in Particulate Air Pollution
R828112C098 Daily Mortality and Fine and Ultrafine Particles in Erfurt, Germany
R828112C099 A Case-Crossover Analysis of Fine Particulate Matter Air Pollution and Out-of-Hospital Sudden Cardiac Arrest
R828112C100 Effects of Mexico City Air on Rat Nose
R828112C101 Penetration of Lung Lining and Clearance of Particles Containing Benzo[a]pyrene
R828112C102 Metabolism of Ether Oxygenates Added to Gasoline
R828112C103 Characterization and Mechanisms of Chromosomal Alterations Induced by Benzene in Mice and Humans
R828112C104 Acute Cardiovascular Effects in Rats from Exposure to Urban Ambient Particles
R828112C105 Genetic Differences in Induction of Acute Lung Injury and Inflammation in Mice
R828112C106 Effects on Mice of Exposure to Ozone and Ambient Particle Pollution
R828112C107 Emissions from Diesel and Gasoline Engines Measured in Highway Tunnels