Final Report: Health Effects of Concentrated Ambient Particles from the Central Valley of California

EPA Grant Number: R827995
Title: Health Effects of Concentrated Ambient Particles from the Central Valley of California
Investigators: Pinkerton, Kent E. , Sioutas, Constantinos , Smith, Kevin R.
Institution: University of California - Davis , University of Southern California
EPA Project Officer: Chung, Serena
Project Period: February 1, 2000 through January 31, 2003 (Extended to July 31, 2003)
Project Amount: $633,328
RFA: Airborne Particulate Matter Health Effects (1999) RFA Text |  Recipients Lists
Research Category: Particulate Matter , Air , Health Effects

Objective:

The objective of this research project was to examine the mechanisms of particulate toxicity in the lungs of rats following short-term (3-day) exposure to concentrated ambient particles of the California Central Valley during different seasons of the year. Fall and winter were selected for this study, because particle size and composition in the Central Valley of California are markedly different during these seasons. We examined the effects of particles in the fine/ultrafine size mode, as well as the coarse size mode, on the respiratory system of young adult rats. Each exposure condition was characterized by size and chemical composition. Biomarkers of particle-induced effects were measured by bronchoalveolar lavage (BAL) and histological examination of the conducting airways, centriacinar regions, and alveoli of the lungs.

Summary/Accomplishments (Outputs/Outcomes):

Technical Aspects

A particle concentrator system was developed by Dr. Costas Sioutas to facilitate the concentration of ambient particles in real time in the Central Valley, ranging in size from greater than 0.1 to 2.5 µm. Concentrating ultrafine particles (< 0.1 µm) is problematic because of their loss from typical systems as ambient particles are being concentrated. The unique concentrator used in this study was designed to concentrate both fine and ultrafine particulate matter (PM). The particles in this size range were concentrated by a factor of 22 times over ambient levels. The system employed a process of hydration to enlarge particles to super-µm droplets with supersaturation and condensation. The particles subsequently were size separated using a virtual impactor, and returned to their original (ambient) size by passing through a diffusion dryer to remove particle-bound water. For studies with coarse particles (2.5-10 µm), four virtual impactors were used in parallel, each operating at an intake sampling flow of 110 L/minute for a total intake flow of 440 L/minute. The minor flow rate, containing the concentrated coarse-mode particles (2.5-10 mm), could be adjusted to enrich ambient coarse PM concentrations to deliver the desired exposure level and flow rate needed. For coarse particle studies, the concentrated (or minor) flow was set at 11 L/minute to correspond to a concentration enrichment factor of 40. Under these conditions, fine and ultrafine particles were not concentrated, as they were primarily removed in the major exit flow from the system.

For studies with ambient fine/ultrafine particles during the fall and winter seasons, adult Sprague-Dawley rats were exposed in six separate experiments to filtered air or combined fine and ultrafine size modes of PM, enhanced approximately 22-fold over ambient levels in Fresno, CA. The goal of these studies was to determine if concentrated fine/ultrafine fractions of PM2.5 would be cytotoxic and/or proinflammatory in the lungs of healthy adult rats. Exposures were for 4 hours per day for 3 consecutive days. The mean mass concentration of particles ranged from 190 to 847 µg/m3. PM was enriched primarily with ammonium nitrate, organic and elemental carbon, and metals. The viability of cells recovered by BAL from rats exposed to concentrated fine/ultrafine PM was decreased significantly during 4 of 6 weeks, compared to rats exposed to filtered air (p < 0.05). Total BAL cells were increased during 1 week, and neutrophils were increased during 2 weeks.

For studies with ambient coarse particles, we selected the fall season in the Central Valley. The dominant PM fraction in the San Joaquin/Sacramento Valley during this period of the year is coarse particles. Therefore, adult Sprague-Dawley rats were exposed in Fresno or Davis, CA, for 6 hours per day for 3 consecutive days to filtered air or to the coarse fraction of PM enhanced approximately fortyfold over ambient levels with the particle concentrator system. The average mass concentration of concentrated particles ranged from 76 to 460 µg/m3. BAL was performed on each group of rats following exposure. Total cells in BAL from rats exposed to concentrated PM were significantly increased during 1 of 2 weeks in Fresno and 2 of 2 weeks in Davis, compared to rats exposed to filtered air (p < 0.05). BAL macrophages were increased during 1 of 2 weeks in Fresno and 2 of 2 weeks in Davis; neutrophils increased during all 4 weeks and lymphocytes during 2 of 2 weeks in Davis.

Results and Conclusions

For those studies using fine/ultrafine particles, we demonstrated that:  (1) ambient fine and ultrafine particles can be concentrated to study health effects under experimental conditions; (2) concentrated ambient particles in Fresno produce respiratory change in healthy adult rats; (3) respiratory changes can be measured during both the fall and winter seasons in Fresno; and (4) respiratory changes associated with decreased lung cell viability are independent of mean particle mass concentration during these 3-day periods of exposure.

For those studies using coarse particles, we demonstrated that: (1) significant respiratory effects in healthy adult rats were produced by exposure to concentrated ambient coarse particles in the Fresno and Davis areas; (2) these respiratory responses following exposure to coarse particles were different compared with exposure to fine/ultrafine particles, suggesting that different mechanisms may be responsible for pulmonary damage for each ambient particle size; and (3) humans are exposed to the full spectrum of particle sizes in the environment, thus, a role for coarse particles in observed health effects because of particle exposure should not be eliminated.

Implications of Research Findings

It remains a challenge to assign specific biological effects to a particular component of particles based on particle size or composition. Studies with concentrated ambient particles in the California Central Valley, however, can provide insights to determine if a consistent pattern of injury to the lung emerges as a result of exposure to fully characterized ambient particles based on particle size (ultrafine and coarse) and composition. Our studies in the California Central Valley have been instrumental in demonstrating that not all particles produce the same effect based on concentration, size, or chemical composition. Certain particles of specific chemical or size distribution produce unique biological responses (i.e., decreased cell viability, total cell number, or alterations in cell differential). This strongly suggests different mechanisms of toxicity. Further inhalation exposure studies with concentrated ambient particles should greatly facilitate answers to these questions.


Journal Articles on this Report : 7 Displayed | Download in RIS Format

Other project views: All 9 publications 7 publications in selected types All 7 journal articles
Type Citation Project Document Sources
Journal Article Dietert RR, Etzel RA, Chen D, Halonen M, Holladay SD, Jarabek AM, Landreth K, Peden DB, Pinkerton K, Smialowicz RJ, Zoetis T. Workshop to identify critical windows of exposure for children's health: immune and respiratory systems work group summary. Environmental Health Perspectives 2000;108(Suppl 3):483-490. R827995 (Final)
R826246 (2000)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article Pinkerton KE, Joad JP. The mammalian respiratory system and critical windows of exposure for children's health. Environmental Health Perspectives 2000;108(Suppl 3):457-462. R827995 (Final)
    R826246 (Final)
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  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article Pinkerton KE, Zhou Y-M, Teague SV, Peake JL, Walther RC, Kennedy IM, Leppert VJ, Aust AE. Reduced lung cell proliferation following short-term exposure to ultrafine soot and iron particles in neonatal rats: key to impaired lung growth? Inhalation Toxicology 2004;16(Suppl 1):73-81. R827995 (Final)
    R829215 (2003)
    R829215 (2004)
    R829215 (Final)
  • Abstract from PubMed
  • Abstract: Taylor and Francis-Abstract
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  • Journal Article Smith KR, Kim S, Recendez JJ, Teague SV, Menache MG, Grubbs DE, Sioutas C, Pinkerton KE. Airborne particles of the California Central Valley alter the lungs of healthy adult rats. Environmental Health Perspectives 2003;111(7):902-908 (discussion A408-409). R827995 (Final)
    R826246 (Final)
    R829215 (Final)
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  • Abstract from PubMed
  • Full-text: EHP-Full Text PDF
  • Abstract: EHP-Abstract
  • Journal Article Yang G, Teague S, Pinkerton K, Kennedy IM. Synthesis of an ultrafine iron and soot aerosol for the evaluation of particle toxicity. Aerosol Science and Technology 2001;35(3):759-766. R827995 (Final)
    R826246 (Final)
  • Full-text: Taylor and Francis-Full Text PDF
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  • Abstract: Taylor and Francis-Abstract
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  • Journal Article Zhou Y-M, Zhong C-Y, Kennedy IM, Pinkerton KE. Pulmonary responses of acute exposure to ultrafine iron particles in healthy adult rats. Environmental Toxicology 2003;18(4):227-235. R827995 (Final)
    R826246 (Final)
    R829215 (2003)
    R829215 (2004)
    R829215 (Final)
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  • Journal Article Zhou Y-M, Zhong C-Y, Kennedy IM, Leppert VJ, Pinkerton KE. Oxidative stress and NFκB activation in the lungs of rats: a synergistic interaction between soot and iron particles. Toxicology and Applied Pharmacology 2003;190(2):157-169. R827995 (Final)
    R829215 (2003)
    R829215 (2004)
    R829215 (Final)
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  • Abstract: Science Direct-Abstract
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  • Supplemental Keywords:

    particulate matter, PM2.5, PM10, particle size and composition, air, geographic area, health, physical aspects, atmospheric sciences, environmental chemistry, epidemiology, health risk assessment, molecular biology, genetics, physical processes, risk assessments, state, air toxics, acute health effects, California, CA, DNA damage, airway epithelial cells, ambient air quality, animal inhalation study, chemical mixtures, cytotoxic events, exposure, human health effects, inhaled, lung inflammation, particle size, particulate exposure, respiratory., RFA, Health, Scientific Discipline, Air, Geographic Area, particulate matter, Toxicology, air toxics, Environmental Chemistry, Health Risk Assessment, State, Risk Assessments, Molecular Biology/Genetics, ambient air quality, particle size, airway epithelial cells, PM 2.5, DNA damage, cytotoxic events, chemical mixtures, lung inflammation, particulate exposure, Acute health effects, inhaled, PM, California (CA), respiratory, ultrafine particles, animal inhalation study

    Progress and Final Reports:

    Original Abstract
  • 2000 Progress Report
  • 2001 Progress Report
  • 2002