2001 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
Current 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, 2000 through May 31, 2001
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

The NYU PM Center is now conducting the first ever subchronic animal inhalation study using concentrated air particles (CAPs) to provide supplementary and complementary data analogous to that 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/week over a 6-month period. 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 system.

The objectives of this research project are to: (1) determine the effects of subchronic 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 carciovascular disease (apoE-/-LdLr-/-mice).

Progress Summary:

The Sioutas virtual impactor ambient concentrator system purchased from the University of Southern California has been installed and modified to serve our exposure needs. The salt-ice cooling system was replaced with a refrigeration-recirculating system that we developed. This modification eliminates almost 1.5 hours of preparation and clean-up time each day. The system also is much more stable in response to changes in ambient temperatures. A schematic diagram of the system is shown below (see Figure 1).

Figure 1. Schematic Diagram of the Refrigeration-Recirculating System

We are fine-tuning the operational parameters of the concentrator in terms of the temperatures of the humidifier and the cooler. Our goal is to obtain the relationship between the ambient temperature and relative humidity (RH) with the operational parameters of the concentrator so that a stable concentrating factor will be maintained throughout the experiment.

We have been collecting concentrated ambient PM using the biosampler. The volume collected using the biosampler varied with RH of ambient air. The PM suspensions were freeze dried and reconstituted to desired concentration for in vitro exposure experiments. The preliminary experiments using BEAS-2B cells have produced promising results. We have observed variations in the cellular response to PM condensate and the response changes with different weather conditions. We are in the process of investigating whether the biological responses change with the composition of PM.

A prototype animal exposure chamber that will be coupled to the concentrator has been constructed. It consists of 32 compartments divided by perforated stainless steel sheet metal to individually house the mice during each 6-hour exposure. The exposure atmosphere is distributed through six 12 inch-tubes (1/4” OD) with 1/32” holes one-half an inch apart (see Figures 2 and 3). The exposure atmosphere is exhausted through two similar tubes at the bottom of the chamber. Urine shields were placed on the top of the exhaust tubes to prevent clogging (see Figure 4). The distribution of particle concentrations within each compartment was measured using a NaCl test aerosol, and the particles were uniformly distributed inside the exposure chamber (see Figure 5).

Figure 2. Mouse Exposure Chamber With 32 Atmosphere Sampling Ports (To Verify Even Distribution)

Figure 3. Inside the Exposure Chamber

Figure 4. Urine Shield of the Exhaust Tube

Figure 5. Uniform Distribution of Testing Aerosols Inside a Fume Hood

An identical concentrator system is being constructed for the sham control exposure. This sham system will be operated under identical conditions, except that a HEPA filter is placed before the humidifier on the air inlet tubing.

Currently, an Aerotec 2 cyclone is being used on the inlet to remove the coarse fraction of PM. Operating at 220 lpm, this cyclone has a cut-off size of approximately 5 µm. An impactor inlet currently is being constructed so that the exposure can be conducted at 350 lpm with either a cut size of 2.5 or 10 µm.

Considerable progress has been made purchasing and breeding the mice needed for the study and finalizing the study design (see Table 1). Types of mice that will be used are:

· C57BL/6: “Normal mice”, no genetic alterations, susceptible to pulmonary injury and atherosclerosis (fatty streaks in the aorta on a high fat diet).

· B6;129 ApoE-/- LDLr -/-: B6;129 mice with targeted mutations of the genes apolipoprotein E and the low density lipoprotein receptor.

· C57BL/6J ApoE-/- LDLr -/-: We purchased 6 breeding pairs from Jackson laboratories. These mice are breeding well and we have 27 first generation mice as of September 25.

· C57BL/6J ApoE-/-: C57BL/6 mice with targeted mutation of the gene for apolipoprotein E. These mice develop atherosclerotic plaques in the aorta after 6 months on a high fat diet and develop coronary artery disease between 7-12 months. We purchased 120 male C57BL/6 ApoE-/- mice from M+B in Denmark and started them on a high fat diet on August 21.

Table 1. Summary of Mouse Types and Their Purposes in This Research Project

Animal
Air (Sham) Group
PM Group
Cage Controls
Total
C57BL/6
For pulmonary endpoints
18
(sacr 9 at 3 months)
18
(sacr 9 at 3 months)
12
(for sentinels)
48
C57BL/6 ApoE-/- (males, high fat diet x ? months). Aortic plaque extent and severity
30
(sacr 15 at 3 months)
30
(sacr 15 at 3 months)
20
80
B6;129 ApoE-/- LDLr -/-(males and females, high fat diet x ? months). Aortic plaque extent and severity)
24 (12 f, 12 m)
(add at 3 months)
24 (12 f, 12 m)
(add at 3 months)
12
60
C57BL/6 + transmitters
(heart rate, heart rate variability)
6
6
12
ApoE-/- males high fat diet x 5 months + transmitters (Ischemia, arrhythmia)
10
10
8
28


Total animals needed:
-C57BL/6 (36 + 12) = 48 minimum for exposure + 12 sentinels (sac 3 at 0, 2, 4, 6 months) = 60 + 5 extra for replacements = 65 (ordered October 1, 2002 from Jackson Laboratories)
-C57BL/6 ApoE-/- (80 + 12) = 92, we have 120 so there are about 28 extra
-B6;129 ApoE-/- LDLr -/- ( 48 + 12 ) = 60 needed by February.

Future Activities:

Future activities are to continue fine-tuning the operational parameters of the concentrator, investigating whether the biological responses change with the composition of PM, constructing an impactor inlet, and purchasing and breeding mice needed for the study.

Supplemental Keywords:

particulate matter, PM, PM components, relative humidity, RH, concentrator, ambient temperatures, exposure, subchronic mouse study, concentrated air particles, CAPs, cardiopulmonary effects., RFA, Scientific Discipline, Health, PHYSICAL ASPECTS, Air, POLLUTANTS/TOXICS, particulate matter, Chemical Engineering, Environmental Chemistry, air toxics, Health Risk Assessment, Air Pollutants, Epidemiology, Air Pollution Effects, Risk Assessments, Biochemistry, Physical Processes, Environmental Engineering, Biology, 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

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • 2002 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