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Cardiac effects of seasonal ambient particulate matter and ozone co-exposure in rats.

Farraj AK, Walsh L, Haykal-Coates N, Malik F, McGee J, Winsett D, Duvall R, Kovalcik K, Cascio WE, Higuchi M, Hazari MS - Part Fibre Toxicol (2015)

Bottom Line: Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources.These findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses.These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.

View Article: PubMed Central - PubMed

Affiliation: Environmental Public Health Division, US EPA, 109 TW Alexander Drive, Research Triangle Park, Durham, NC, 27711, USA. farraj.aimen@epa.gov.

ABSTRACT

Background: The potential for seasonal differences in the physicochemical characteristics of ambient particulate matter (PM) to modify interactive effects with gaseous pollutants has not been thoroughly examined. The purpose of this study was to compare cardiac responses in conscious hypertensive rats co-exposed to concentrated ambient particulates (CAPs) and ozone (O3) in Durham, NC during the summer and winter, and to analyze responses based on particle mass and chemistry.

Methods: Rats were exposed once for 4 hrs by whole-body inhalation to fine CAPs alone (target concentration: 150 μg/m3), O3 (0.2 ppm) alone, CAPs plus O3, or filtered air during summer 2011 and winter 2012. Telemetered electrocardiographic (ECG) data from implanted biosensors were analyzed for heart rate (HR), ECG parameters, heart rate variability (HRV), and spontaneous arrhythmia. The sensitivity to triggering of arrhythmia was measured in a separate cohort one day after exposure using intravenously administered aconitine. PM elemental composition and organic and elemental carbon fractions were analyzed by high-resolution inductively coupled plasma-mass spectrometry and thermo-optical pyrolytic vaporization, respectively. Particulate sources were inferred from elemental analysis using a chemical mass balance model.

Results: Seasonal differences in CAPs composition were most evident in particle mass concentrations (summer, 171 μg/m3; winter, 85 μg/m3), size (summer, 324 nm; winter, 125 nm), organic:elemental carbon ratios (summer, 16.6; winter, 9.7), and sulfate levels (summer, 49.1 μg/m3; winter, 16.8 μg/m3). Enrichment of metals in winter PM resulted in equivalent summer and winter metal exposure concentrations. Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources. Single pollutant cardiovascular effects with CAPs and O3 were present during both summer and winter exposures, with evidence for unique effects of co-exposures and associated changes in autonomic tone.

Conclusions: These findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses. Although there was inconsistency in biological responses, some cardiovascular responses were evident only in the co-exposure group during both seasons despite variability in PM physicochemical composition. These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.

No MeSH data available.


Related in: MedlinePlus

Schematic of concentrated ambient particulates (CAPs) and ozone (O3) co-exposure system showing concentrator, O3 generator, exposure chambers, and particulate matter (PM) and O3 monitoring systems. Receivers were placed within each chamber to monitor electrocardiogram, heart rate and body temperature. Particle concentration and sizing were tracked in real-time using a scanning mobility particle sizer and an aerodynamic particle sizer. Additional aerosol monitors (DustTrak and P-Trak) were used to track PM levels in real-time.
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Fig9: Schematic of concentrated ambient particulates (CAPs) and ozone (O3) co-exposure system showing concentrator, O3 generator, exposure chambers, and particulate matter (PM) and O3 monitoring systems. Receivers were placed within each chamber to monitor electrocardiogram, heart rate and body temperature. Particle concentration and sizing were tracked in real-time using a scanning mobility particle sizer and an aerodynamic particle sizer. Additional aerosol monitors (DustTrak and P-Trak) were used to track PM levels in real-time.

Mentions: All exposures were conducted in the U. S. EPA’s Research Triangle Park, NC Consolidated Research Facility (CRF), Concentrated Air Particles (CAPs) Laboratory located at 179 T.W. Alexander Dr., RTP, NC. EPA’s CAPs exposure facility accommodated 3 Hinners style, stainless steel and glass, 0.3 m3 whole body chambers (Figure 9). Each chamber was modified to expose animals to ozone and clean air as well as CAPs. The wire mesh animal cages were modified and receivers positioned within each chamber to maximize telemeter signal transmission and minimize effects on chamber PM distribution. Two CAPs chambers were connected to the outlet of a PM2.5 fine particle concentrator (Harvard Fine Particle Concentrator, Harvard University, Boston, MA; HFPC) [49]. Stainless steel tubing (3” diameter) with quick connecting joints was used to transport Air/PM from the concentrator outlet to the designated chamber(s). Transport tubing was configured to deliver all CAPs to a single chamber, split concentrated PM between two chambers, or to totally bypass chambers allowing for gas pollutant or clean air operation. Chamber temperature, relative humidity, air flow, and static pressure and test agent concentrations for PM and O3 were continuously monitored, displayed, and recorded by the lab’s computerized electronic data acquisition system. Clean, charcoal and HEPA filtered, and conditioned dilution air was available from two sources (Core Inhalator System (CIS) supply air, DP = ~55 F, 50% relative humidity (RH), and Medical Grade Air, DP = ~ − 20 F, ~5% RH). The two dilution air streams were blended to regulate chamber RH and peak PM concentrations. Chamber environmental data, PM, and O3 concentrations from multiple exposures within each group were averaged to produce mean values for each exposure group.Figure 9


Cardiac effects of seasonal ambient particulate matter and ozone co-exposure in rats.

Farraj AK, Walsh L, Haykal-Coates N, Malik F, McGee J, Winsett D, Duvall R, Kovalcik K, Cascio WE, Higuchi M, Hazari MS - Part Fibre Toxicol (2015)

Schematic of concentrated ambient particulates (CAPs) and ozone (O3) co-exposure system showing concentrator, O3 generator, exposure chambers, and particulate matter (PM) and O3 monitoring systems. Receivers were placed within each chamber to monitor electrocardiogram, heart rate and body temperature. Particle concentration and sizing were tracked in real-time using a scanning mobility particle sizer and an aerodynamic particle sizer. Additional aerosol monitors (DustTrak and P-Trak) were used to track PM levels in real-time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4419498&req=5

Fig9: Schematic of concentrated ambient particulates (CAPs) and ozone (O3) co-exposure system showing concentrator, O3 generator, exposure chambers, and particulate matter (PM) and O3 monitoring systems. Receivers were placed within each chamber to monitor electrocardiogram, heart rate and body temperature. Particle concentration and sizing were tracked in real-time using a scanning mobility particle sizer and an aerodynamic particle sizer. Additional aerosol monitors (DustTrak and P-Trak) were used to track PM levels in real-time.
Mentions: All exposures were conducted in the U. S. EPA’s Research Triangle Park, NC Consolidated Research Facility (CRF), Concentrated Air Particles (CAPs) Laboratory located at 179 T.W. Alexander Dr., RTP, NC. EPA’s CAPs exposure facility accommodated 3 Hinners style, stainless steel and glass, 0.3 m3 whole body chambers (Figure 9). Each chamber was modified to expose animals to ozone and clean air as well as CAPs. The wire mesh animal cages were modified and receivers positioned within each chamber to maximize telemeter signal transmission and minimize effects on chamber PM distribution. Two CAPs chambers were connected to the outlet of a PM2.5 fine particle concentrator (Harvard Fine Particle Concentrator, Harvard University, Boston, MA; HFPC) [49]. Stainless steel tubing (3” diameter) with quick connecting joints was used to transport Air/PM from the concentrator outlet to the designated chamber(s). Transport tubing was configured to deliver all CAPs to a single chamber, split concentrated PM between two chambers, or to totally bypass chambers allowing for gas pollutant or clean air operation. Chamber temperature, relative humidity, air flow, and static pressure and test agent concentrations for PM and O3 were continuously monitored, displayed, and recorded by the lab’s computerized electronic data acquisition system. Clean, charcoal and HEPA filtered, and conditioned dilution air was available from two sources (Core Inhalator System (CIS) supply air, DP = ~55 F, 50% relative humidity (RH), and Medical Grade Air, DP = ~ − 20 F, ~5% RH). The two dilution air streams were blended to regulate chamber RH and peak PM concentrations. Chamber environmental data, PM, and O3 concentrations from multiple exposures within each group were averaged to produce mean values for each exposure group.Figure 9

Bottom Line: Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources.These findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses.These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.

View Article: PubMed Central - PubMed

Affiliation: Environmental Public Health Division, US EPA, 109 TW Alexander Drive, Research Triangle Park, Durham, NC, 27711, USA. farraj.aimen@epa.gov.

ABSTRACT

Background: The potential for seasonal differences in the physicochemical characteristics of ambient particulate matter (PM) to modify interactive effects with gaseous pollutants has not been thoroughly examined. The purpose of this study was to compare cardiac responses in conscious hypertensive rats co-exposed to concentrated ambient particulates (CAPs) and ozone (O3) in Durham, NC during the summer and winter, and to analyze responses based on particle mass and chemistry.

Methods: Rats were exposed once for 4 hrs by whole-body inhalation to fine CAPs alone (target concentration: 150 μg/m3), O3 (0.2 ppm) alone, CAPs plus O3, or filtered air during summer 2011 and winter 2012. Telemetered electrocardiographic (ECG) data from implanted biosensors were analyzed for heart rate (HR), ECG parameters, heart rate variability (HRV), and spontaneous arrhythmia. The sensitivity to triggering of arrhythmia was measured in a separate cohort one day after exposure using intravenously administered aconitine. PM elemental composition and organic and elemental carbon fractions were analyzed by high-resolution inductively coupled plasma-mass spectrometry and thermo-optical pyrolytic vaporization, respectively. Particulate sources were inferred from elemental analysis using a chemical mass balance model.

Results: Seasonal differences in CAPs composition were most evident in particle mass concentrations (summer, 171 μg/m3; winter, 85 μg/m3), size (summer, 324 nm; winter, 125 nm), organic:elemental carbon ratios (summer, 16.6; winter, 9.7), and sulfate levels (summer, 49.1 μg/m3; winter, 16.8 μg/m3). Enrichment of metals in winter PM resulted in equivalent summer and winter metal exposure concentrations. Source apportionment analysis showed enrichment for anthropogenic and marine salt sources during winter exposures compared to summer exposures, although only 4% of the total PM mass was attributed to marine salt sources. Single pollutant cardiovascular effects with CAPs and O3 were present during both summer and winter exposures, with evidence for unique effects of co-exposures and associated changes in autonomic tone.

Conclusions: These findings provide evidence for a pronounced effect of season on PM mass, size, composition, and contributing sources, and exposure-induced cardiovascular responses. Although there was inconsistency in biological responses, some cardiovascular responses were evident only in the co-exposure group during both seasons despite variability in PM physicochemical composition. These findings suggest that a single ambient PM metric alone is not sufficient to predict potential for interactive health effects with other air pollutants.

No MeSH data available.


Related in: MedlinePlus