2002 Progress Report: Subchronic PM2.5 Exposure Study at the NYU PM Center

EPA Grant Number: R827351C012
Subproject: this is subproject number 012 , established and managed by the Center Director under grant R827351
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EPA NYU PM Center: Health Risks of PM Components
Center Director: N/A
Title: Subchronic PM2.5 Exposure Study at the NYU PM Center
Investigators: Lippmann, Morton , Chen, Lung Chi
Institution: New York University School of Medicine
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2004
Project Period Covered by this Report: June 1, 2001 through May 31, 2002
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

The objectives of this research project are to: (1) determine the effects of subchronic concentrated ambient particles (CAPs) exposure on pulmonary histopathology and lavage fluid biomarkers of lung inflammation and lung injury; and (2) determine whether subchronic CAPs exposure accelerates the development of atherosclerotic plaques in a mouse model of human atherosclerotic cardiovascular disease (apoE-/-LDLr-/-mice).

The Harvard Six Cities Study (Dockery, et al., 1993) and the American Cancer Society (ACS) Cohort Study (Pope, et al., 1995) have shown substantially increased mortality in cities with higher average particulate matter (PM2.5) concentrations, not attributable to other risk factors. The validity and robustness of the Six Cities and ACS mortality studies' findings were confirmed by the Health Effects Institute Reanalysis Project (Krewski, et al., 2000). The association between chronic exposure to PM2.5 and increased mortality also was significant when the Six Cities and ACS studies were extended for an additional 9 years (Pope, et al., 2001; Laden, et al., 2001). The PM effect size estimates reported in these studies are much larger than the cumulative effects reported for acute PM exposure and mortality (U.S. Environmental Protection Agency, 2001). This finding indicates that people who live in areas with elevated PM experience cumulative adverse health effects in addition to acute transient effects. Increased mortality is not the only adverse health effect associated with PM exposure; several cross-sectional studies of children (Dockery, et al., 1989, 1996; Raizennne, et al., 1996) have shown that children who live in cities with higher average PM2.5 concentrations have more respiratory symptoms and decreased pulmonary function. Moreover, the Children's Health Study in Southern California has shown that chronic exposure to increased PM pollution also is associated with slower cumulative lung growth (Peters, et al., 1999a,b; Gauderman, et al., 2000; Avol, et al., 2001).

Based on these findings, the New York University PM Center is now conducting the first ever subchronic animal inhalation study using CAPs to provide supplementary and complementary data analogous to those developed in the human cohort studies in cities with varying levels of fine PM. The studies began in 2002, with daily 6-hour exposures to CAPs for 5 days per week over a 6-month period. The main focus of this subchronic inhalation study is on the direct and indirect cardiopulmonary effects of PM. This study tests the hypothesis that subchronic exposure of normal and compromised mice to CAPs will cause cumulative adverse effects on the respiratory and cardiovascular systems.

Progress Summary:

Progress in Year 1 of the Project. We have assembled, tested, and validated the Versatile Aerosol Concentration Enrichment System (VACES) developed by Sioutas, et al., at the Southern California PM Center for a subchronic experiment that involves exposure of mice in vivo and respiratory epithelial cells in vitro to CAPs. Because the labor-intensive nose-only exposure regimen is not an option in a long-term experiment, a whole-body exposure mouse chamber was designed specifically for use with the VACES with design assistance from M. Kleinman (Southern California PM Center). The exposure system consists of a 5-gallon (20 inches x 12 inches x 6 inches) stainless steel tub with 32 cubicles (1 mouse per cubicle) separated by perforated stainless steel sheets. The tops of these cubicles are covered with perforated plastic sheets to allow cardiac telemetry monitoring during the exposure. In each exposure chamber, six stainless steel tubes (each 22 cm in length) with 15 0.25 mm holes, 13.5 mm apart, are used to distribute CAPs evenly throughout the exposure chamber. The exhaust consists of two stainless steel tubes (each 40 cm in length), each with 28 0.5 mm holes, covered with a semicircular urine shield. In addition, a major modification was made to the original design of the VACES to facilitate the operation of the system in a subchronic study: the salt-ice slurry used in the condensation process was replaced by a refrigerated circulator (chiller). Mass flow controllers are used to maintain a constant flow rate through these exposure chambers. For a sham control experiment, the identical system is used, except that a high efficiency particulate air (HEPA) filter at the inlet to the VACES removes ambient particles. The entire system allows for simultaneous exposure of 64 mice to CAPs, with an equal number of sham-exposed mice as controls. Telemetry receivers have been modified so that 16 mice per group with electrocardiogram (ECG) transmitters can be monitored during exposure. Furthermore, a biosampler is used to collect CAPs (one sample per day) for the in vitro exposures. A respiratory epithelial cell line (BEAS- 2B), stably transfected with NF-kB-luciferase reporter plasmid, is used to assess daily biological activity of ambient PM.

The subchronic study was commenced in February 2003, with all C57 mice being exposed to CAPs for 6 hours per day, 5 days per week. However, the ApoE knockout mice (ApoE-/-) developed skin problems, typical of ApoE mice. The NYU External Scientific Advisory Committee recommended that we terminate all the ApoE-/- mice and replace them with the ApoE-/- LDLr-/- double knockout mice. These ApoE-/- mice are more than 8 months old and probably have developed advanced atherosclerotic plaques in their aorta. Although not suitable for long-term study, it may be valuable to investigate the impact of CAPs on these animals in an acute study which will be performed in June 2003 on high PM concentration days. One batch of the ApoE-/- (10/group) was sacrificed on April 17, 2003, 24 hours after five exposures to CAPs or filtered air. We are investigating the effects of CAPs on blood and lavage parameters as well as the histopathological changes in the lungs and hearts of these animals.

Future Activities:

In the next year of the project, the remaining ApoE-/- will be exposed when the exposure concentration is expected to exceed 200 µg/m3. Once all ApoE-/- mice are sacrificed, exposure of the double knockout mice will begin.

Because it will take several weeks to implant transmitters in the double knockout mice, we will continue exposing the ApoE-/- mice with transmitters to CAPs as long as we can. We anticipate that we will expose the ApoE-/- mice for at least 1 month before they are replaced with the double knockout mice with transmitters.

To accommodate the ApoE-/- LDLr-/- mice with transmitters, some of the ApoE-/- mice will be sacrificed. Table 1 shows the number of animals in each exposure group as of May 5, 2003. Based on the baseline heart rate data of the ApoE-/- mice, Dr. Jing Shiang Hwang estimated that with 5 males and 5 females per exposure group with the transmitters, the power of detecting 1 standard deviation change versus mean in the double knockout mice is slightly over 0.8.

Table 1. Number of Animals in Each Exposure Group, May 2003

Starting 3/10/03
Air (sham) group
PM group
Not-exposed
C57BL/6 (intermediate sac on the week of 6/10/03)
18
18
12
ApoE-/-
29
C57BL/6 + transmitters
6
6
ApoE-/- + transmitters
6
6
Starting 5/5/03
     
ApoE-/- LDLr-/-
12 females/12 males
12 females/12 males
1 females/5 males
Starting 5/19/03
     
ApoE-/- LDLr-/- + transmitters
5 females/5 males
5 females/5 males

Supplemental Keywords:

air pollution, air pollutants, particulate matter, PM, fine particles, PM2.5, ambient PM, pulmonary responses, cardiovascular responses, Harvard Six Cities Study, American Cancer Society Cohort Study, PM exposure and mortality, children, Children's Health Study in Southern California, subchronic animal inhalation study, Versatile Aerosol Concentration Enrichment System, concentrated ambient particles, CAPs, telemetry, electrocardiogram, ECG, heart rate, lung effects, respiratory effects, health effects., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, POLLUTANTS/TOXICS, particulate matter, Chemical Engineering, air toxics, Environmental Chemistry, Health Risk Assessment, Air Pollutants, Epidemiology, Air Pollution Effects, Risk Assessments, Biochemistry, Physical Processes, Biology, Environmental Engineering, ambient air quality, asthma, particulates, criteria air pollutants, health effects, human health effects, exposure and effects, lung, exposure, heart rate variability, pulmonary disease, ambient air, air pollution, human exposure, pulmonary, allergens, aerosol, biological markers, human health, aerosols, dosimetry, respiratory, allergen, airborne urban contaminants

Relevant Websites:

http://charlotte.med.nyu.edu/epa-pm-center/ Exit

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • 2001 Progress Report
  • Final

  • Main Center Abstract and Reports:

    R827351    EPA NYU PM Center: Health Risks of PM Components

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827351C001 Exposure Characterization Error
    R827351C002 X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations
    R827351C003 Asthma Susceptibility to PM2.5
    R827351C004 Health Effects of Ambient Air PM in Controlled Human Exposures
    R827351C005 Physicochemical Parameters of Combustion Generated Atmospheres as Determinants of PM Toxicity
    R827351C006 Effects of Particle-Associated Irritants on the Cardiovascular System
    R827351C007 Role of PM-Associated Transition Metals in Exacerbating Infectious Pneumoniae in Exposed Rats
    R827351C008 Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
    R827351C009 Health Risks of Particulate Matter Components: Center Service Core
    R827351C010 Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects
    R827351C011 Urban PM2.5 Surface Chemistry and Interactions with Bronchoalveolar Lavage Fluid (BALF)
    R827351C012 Subchronic PM2.5 Exposure Study at the NYU PM Center
    R827351C013 Long Term Health Effects of Concentrated Ambient PM2.5
    R827351C014 PM Components and NYC Respiratory and Cardiovascular Morbidity
    R827351C015 Development of a Real-Time Monitoring System for Acidity and Soluble Components in Airborne Particulate Matter
    R827351C016 Automated Real-Time Ambient Fine PM Monitoring System