Final Report: Simulated Roadway Exposure Atmospheres for Laboratory Animal and Human Studies

EPA Grant Number: R834796C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant R834796
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: University of Washington Center for Clean Air Research
Center Director: Vedal, Sverre
Title: Simulated Roadway Exposure Atmospheres for Laboratory Animal and Human Studies
Investigators: McDonald, Jacob D.
Institution: Lovelace Respiratory Research Institute
EPA Project Officer: Callan, Richard
Project Period: December 1, 2010 through November 30, 2015 (Extended to November 30, 2017)
RFA: Clean Air Research Centers (2009) RFA Text |  Recipients Lists
Research Category: Health Effects , Air

Objective:

Traffic-related emissions are associated with the incidence and progression of acute and chronic cardiovascular sequelae in human population studies; however, the causal components, subsequent chemical transformation of these components, and their associated toxicity on the cardiovascular system have not yet been determined. Project 2 develops atmospheres with the primary objective of simulating environments containing key components of roadway emissions and the products of environmental factors that transform them. Exposures are designed to determine air contaminants (or components) that cause or potentiate the toxicity of roadway emissions or confound interpretations based on roadway proximity alone. 

Approach: This project will generate and characterize multiple complex roadway mixtures for subsequent animal and human exposure-related toxicology studies. 

In Aim 1, we will develop and characterize laboratory-generated exposure atmospheres simulating the key components of near-roadway exposures, including transformed emissions and coexposures. Aim 1 will modify and optimize existing LRRI exposure systems that have been previously utilized. We will modify the existing Motor Vehicle Emissions (MVE) exposure system to permit studies that compare atmospheres that mimic near roadway exposure to atmospheres that are physically aged or chemically transformed to mimic downwind exposures. The MVE atmospheres will be studied both as near as realistically practical to the point of emission, and after atmospheric aging simulating time-related particle nucleation and agglomeration. Next, the atmospheres will be chemically transformed in an irradiation (smog) chamber. The ability of a representative background pollutant mix to potentiate the toxic effects of roadway emissions will then be determined. The background mix will be simulated by combining inorganic ions, metals, secondary organics volatile hydrocarbons and ozone in realistic proportions.

In Aim 2, we will conduct inhalation exposures of laboratory animals. Aim 2 will integrate with the animal toxicology project (Project 3). Building on previous findings that show synergistic increases in mouse vascular response when gasoline and diesel emissions are combined, we will investigate permutations to assess the effects of the near-roadway scenarios developed in Aim 1 and define the biological potency based on lipid peroxidation in ApoE-/- mice (Ref: Project 3). The first phase of this work is screening potency of motor vehicle emissions under different exposure combinations that may reflect scenarios observed in Project 1.

Summary/Accomplishments (Outputs/Outcomes):

Aim 1: Atmosphere Generation

The aims of these characterizations are to bridge the laboratory atmosphere data to what is observed in the field sampling campaigns. During this work, several sets of experiments were conducted to better define the role of gas/particle partitioning in the laboratory. The measurements in each of the test atmospheres included particle mass, particle number, volatile hydrocarbons, nitrogen oxides, ozone, carbon monoxide, carbon dioxide, and speciated volatile and semi-volatile hydrocarbons by mass spectrometry.  

In addition to the studies defined above, further atmosphere development focused on creating atmospheres that would allow us to investigate test atmospheres that ‘tease’ out the role of gases versus particles in novel ways, and that further evaluate the role of physical aging of motor vehicle exhaust. Specific studies included atmospheres to evaluate:

  • Mixed motor vehicle exhaust
  • Mixed motor vehicle exhaust minus particles
  • Mixed motor vehicle exhaust minus gases (includes particles)
  • Mixed motor vehicle exhaust minus NOx and ultrafines (simulates downwind)
  • Road Dust
  • Road Dust + MVE
  • Road Dust + 0.33 ppm Ozone
  • Woodsmoke

Consideration of Project 1 Data for Test Atmosphere Design

Part of the design of the Center was to integrate projects to help design experiments. We also considered some of the ambient data from Project 1 in the design of test atmospheres.  Data collected by Project 1 illustrated some interesting differences as one transected away from the road. However, it is unclear if these differences would provide enough of a contrast to elucidate biological differences in the magnitude of response. Because of this, we have considered the use of the ambient data for the design of toxicology experiments more as a tool in placing the results/atmospheres in context of what they model as opposed to determining how we approach the test atmospheres. 

Additional details on exposure generation, including our work overcoming technical challenges to evaluate irradiated atmospheres, are included in the annual reports.

Aim 2: Inhalation Exposures in Laboratory Animals

Conclusions Regarding Metabolomic Profiling

Inhalation of motor vehicle exhaust by mice produced significant changes in serum global metabolite profiles, although the results may be somewhat confounded by a time-dependent effect on metabolites that is not MVE-dependent. Global profiling of serum for mice treated with MVE suggests that exposure results in increased oxidative stress and possible inflammatory responses. A set of metabolites with reported cardiovascular activity were altered and may indicate that changes in vascular tone occur with MVE exposure. MVE-dependent changes in energy metabolites were also observed, but a lack of a clear dose response or reproducibility between MVE-100 and MVE-300 groups argues for a cautious appraisal of general significance. 

Endothelial Cell Toxicity/Response

To confirm the phenomenon of serum inflammatory potential related to complex combustion atmosphere exposures, we characterized a number of responses induced by serum from mice exposed to mixed vehicle emissions, wood smoke, road dust, and other mixtures, with serum collected 4 h and 24 h after exposures. Primary mouse brain microvascular endothelial cells (BMVEC; Cell Biologics) and pulmonary artery endothelial cells (PAEC; Cell Biologics) treated with serum from exposed C57BL mice showed modest elevation of inflammatory chemokines, both in terms of relative mRNA and cell surface expression. These findings indicate that some factors in the serum produced from inhalational exposures can in turn produce systemic inflammatory responses.

Additional details on toxicological experiments conducted as part of Project 2 may be found in the annual reports.

We had planned to include as Aim 3, a study of inhalation exposures of human subjects in an effort to compare significant pathophysiological findings from our animal model exposures to responses in humans, but due to human subjects issues related to Project 4, Aim 3 was dropped.

Conclusions:

Project 2 achieved Aims 1 and 2 and provided key support to Projects 1 and especially 3. Project 2 researchers successfully developed a number of complicated test atmospheres with varying composition (e.g., MVE without particles, road dust). In addition, experiments with MVE elucidated a number of biomarkers of exposure.

 


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 14 publications 5 publications in selected types All 5 journal articles
Other center views: All 187 publications 87 publications in selected types All 86 journal articles
Type Citation Sub Project Document Sources
Journal Article Lund AK, Doyle-Eisele M, Lin Y-H, Arashiro M, Surratt JD, Holmes T, Schilling KA, Seinfeld JH, Rohr AC, Knipping EM, McDonald, JD. The effects of α-pinene versus toluene-derived secondary organic aerosol exposure on the expression of markers associated with vascular disease. Inhalation Toxicology 2013;25(6):309-324. R834796 (2013)
R834796 (2014)
R834796 (2015)
R834796 (Final)
R834796C002 (2015)
R834796C002 (Final)
R834796C003 (2013)
R833990 (2011)
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  • Other: UNC at Chapel Hill-Abstract
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  • Journal Article Mauderly JL, Kracko D, Brower J, Doyle-Eisele M, McDonald JD, Lund AK, Seilkop SK. The National Environmental Respiratory Center (NERC) experiment in multi-pollutant air quality health research: IV. Vascular effects of repeated inhalation exposure to a mixture of five inorganic gases. Inhalation Toxicology 2014;26(11):691-696. R834796 (2014)
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  • Journal Article McDonald JD, Chow JC, Peccia J, Liu Y, Chand R, Hidy GM, Mauderly JL. Influence of collection region and site type on the composition of paved road dust. Air Quality, Atmosphere and Health 2013;6(3):615-628. R834796 (2013)
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  • Journal Article Oppenheim HA, Lucero J, Guyot A-C, Herbert LM, McDonald JD, Mabondzo A, Lund AK. Exposure to vehicle emissions results in altered blood brain barrier permeability and expression of matrix metalloproteinases and tight junction proteins in mice. Particle and Fibre Toxicology 2013;10:62. R834796 (2014)
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  • Abstract: BioMed Central-Abstract
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  • Supplemental Keywords:

    Inhalation toxicology, diesel, gasoline engine, Health, Scientific Discipline, Air, ENVIRONMENTAL MANAGEMENT, Air Quality, air toxics, Health Risk Assessment, Risk Assessments, mobile sources, Biochemistry, Environmental Monitoring, Risk Assessment, ambient air quality, atmospheric particulate matter, particulate matter, aerosol particles, air pollutants, motor vehicle emissions, vehicle emissions, air quality models, motor vehicle exhaust, airway disease, bioavailability, air pollution, particle exposure, atmospheric aerosols, ambient particle health effects, vascular dysfunction, cardiotoxicity, atmospheric chemistry, exposure assessment

    Relevant Websites:

    University of Washington Department of Environmental & Occupational Health Sciences Exit

    Progress and Final Reports:

    Original Abstract
  • 2011 Progress Report
  • 2012 Progress Report
  • 2013 Progress Report
  • 2014
  • 2015 Progress Report
  • 2016 Progress Report

  • Main Center Abstract and Reports:

    R834796    University of Washington Center for Clean Air Research

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R834796C001 Exposure Mapping – Characterization of Gases and Particles for ExposureAssessment in Health Effects and Laboratory Studies
    R834796C002 Simulated Roadway Exposure Atmospheres for Laboratory Animal and Human Studies
    R834796C003 Cardiovascular Consequences of Immune Modification by Traffic-Related Emissions
    R834796C004 Vascular Response to Traffic-Derived Inhalation in Humans
    R834796C005 Effects of Long-Term Exposure to Traffic-Derived Particles and Gases on Subclinical Measures of Cardiovascular Disease in a Multi-Ethnic Cohort