2009 Progress Report: Comparative Toxicity of Coarse Particles

EPA Grant Number: R833742
Title: Comparative Toxicity of Coarse Particles
Investigators: Gordon, Terry , Chen, Lung Chi , Ito, Kazuhiko , Lippmann, Morton
Institution: New York University
EPA Project Officer: Chung, Serena
Project Period: March 1, 2008 through February 28, 2012
Project Period Covered by this Report: March 1, 2009 through February 28,2010
Project Amount: $1,199,927
RFA: Sources, Composition, and Health Effects of Coarse Particulate Matter (2006) RFA Text |  Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Particulate Matter

Objective:

The objective of this study is to determine the contribution of coarse particles to the adverse health effects associated with exposure to ambient PM.  The aims and objectives have not changed from the original submission.  We hypothesized that differences in the toxicity of coarse PM (PM10-2.5) samples are due to the source contributions to the particles, and in testing this hypothesis, we are: 1) measuring the differential toxicity of coarse particles both in vitro and in vivo; and 2) identifying whether coarse particles from urban and rural sources differ in toxicity.  A number of investigators have clearly demonstrated that PM toxicity in the mammalian lung is governed, in part, by particle size, but little research has been published on whether the physicochemical properties of coarse particles influence their toxicity in mammalian cells.  In the proposed studies, a group of particle toxicologists are collaborating with a source apportionment epidemiologist to explore the toxicity of a variety of urban and rural coarse particles in established models of mammalian cell toxicity.

Progress Summary:

1) Overview of work status and preliminary results: The work on the project aims has proceeded smoothly but at a slower pace than anticipated.  The delays have primarily been due to delays in the digestion of PM samples and the trace element analyses of PM samples.  A microwave digestion system was purchased and a protocol developed to more rapidly address the preparation of hundreds of PM samples for ICP-MS analyses of trace elements.  The in vitro bioassays have been completed for the urban and rural NY samples.  The sampling of San Joaquin Valley, CA PM is complete and the preparation for PM samples for chemical analyses and bioassays is scheduled for Year 3.

 
 (2) Key personnel: No changes in personnel have occurred over the project period.
 
(3) Expenditures: The expenditures and research schedule are on track for completion of all work by 4/11.
 
(4) Quality assurance: No issues regarding data quality assurance have arisen.  Appropriate substrate/filter blanks (field and laboratory) have been collected at all sampling sites and calibration standards have been utilized at all stages of collection of the environmental data, including filter weighing and trace element analysis (e.g., NIST PM standards and water blanks are included in each microwave digestion batch run).
 
(5) Results to date: The proposed in vitro bioassays demonstrated important toxicity differences in the NY samples and that toxicity is dependent on PM size and sampling region (i.e., rural vs. urban).  As expected, greater amounts of ambient PM were collected at the urban collection sites compared to the rural sites (Tables 1 and 2).
 
Table 1. Mass concentration of coarse and fine PM collected at urban and rural sites.  At one urban (Bronx) and one rural (Walkill) site, PM larger than 10 µm was also collected for analyses.
Mass Concentration (µg/m3) of PM Collected
 
 
Super Coarse
(> PM10)
Coarse
(PM10-2.5)
Fine
(PM2.5)
 
 
Bronx
Urban
7.18
7.74
10.69
 
Manhattan
Urban
ND
9.63
10.88
 
Goshen
Rural
ND
5.99
8.30
 
Tuxedo
Rural
ND
4.91
7.06
 
Wallkill
Rural
2.94
4.80
7.15
 
 
 
Table 2. Mass concentration of coarse and fine PM collected at urban and rural sites during the winter and summer seasons.
Mass Concentration (µg/m3) of PM Collected
 
Coarse
Coarse
Fine
Fine
Summer
Winter
Summer
Winter
Bronx
Urban
7.25
8.34
9.21
12.47
Manhattan
Urban
8.02
11.55
9.50
12.53
Goshen
Rural
5.54
7.06
6.35
10.65
Tuxedo
Rural
5.06
4.72
5.85
8.51
Wallkill
Rural
5.23
4.77
5.46
8.99
 
 
The in vitro studies showed that the urban PM samples (50 µg/ml) resulted in greater production of reactive oxygen species (ROS, an index of oxidative stress) in cell lines derived from lung and microvasculature cells (Figure 2).  PM2.5 produced greater amounts of ROS than did PM10-2.5 collected at the urban sites (Manhattan and Bronx), and this size-dependent effect was strongest in the endothelial cells and was not observed with rural PM (Figure 2).  Seasonal effects on ROS were absent in the in vitro studies (Figures 3 and 4).  These findings need to be confirmed in the in vivo bioassays and at additional rural and urban sites before application to the protection of the environment and human health.
 
Figure 2. Relative fluorescence intensity increase over control values for coarse (10-2.5 µm), and fine (<2.5 µm) PM (50 µg/ml) for 2 urban and 3 rural sampling sites. Column and bars represent mean and SEM for the ROS response in vascular endothelial cells.
 
 
Figure 3. Relative fluoresence intensity (ROS) of coarse PM (50 µg/ml) from rural and urban sites collected in summer and winter. Column and bars represent mean and SEM for the ROS response in vascular endothelial cells.
 
 
Figure 4. Relative fluoresence intensity (ROS) of fine PM (50 µg/ml) from rural and urban sites collected in summer and winter. Column and bars represent mean and SEM for the ROS response in vascular endothelial cells.
 
Sampling for coarse and fine PM has been completed at the rural and urban sites in the metropolitan NYC area and the San Joaquin Valley in central California.  Although the California samples are still undergoing bioassay testing and component analyses, important sampling site differences were observed.  As shown in Figure 1, greater amounts of PM (mean) were collected at the urban sites of Bakersfield and Clovis (Fresno), whereas the third urban site, Davis, had much lower amounts of ambient PM.  As expected, the rural Trinidad sampling site (adjacent to the Pacific Ocean) had a relatively low amount of ambient PM collected.  Interestingly, the maximum values of collected PM varied among the sampling sites.  In Tranquility, a farming area of the San Joaquin Valley, the highest level of PM was collected on a windy day during tilling of the fields.  This maximum value for collected mass (combining all 3 size fractions) is equivalent to approximately 250 µg/m3 of ambient PM (PM10 would be approximately 100 µg/m3).  These central California samples are currently being evaluated for toxicity and chemical components for comparison to the rural and urban NY samples.
 
Figure 1. The mean and maximum amounts of PM collected for each size fraction over a 48 hr period using the ChemVol Sampler in urban and rural San Joaquin Valley in CA.  Super Coarse = PM > 10 µm; Coarse = PM10-2.5; Fine = PM2.5.

Future Activities:

The major objective for the remainder of the support period is to complete the bioassays for the California samples and complete the trace element analyses.

Journal Articles:

No journal articles submitted with this report: View all 12 publications for this project

Supplemental Keywords:

RFA, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Biology, atmospheric particulate matter, sensitive populations, atmospheric particles, cardiopulmonary responses, human health effects, bioavailability, cardiovascular vulnerability, sensitive subgroups, cardiotoxicity, exposure assessment

Progress and Final Reports:

Original Abstract
  • 2008 Progress Report
  • 2010 Progress Report
  • Final Report