Health Effects of Suspended Particulate Matter

1
Health Effects of Suspended Particulate Matter

• Judith C. Chow (Judy.Chow_at_dri.edu)
• John G. Watson
• Desert Research InstituteReno, Nevada, USA
• Presented at
• The Workshop on Air Quality Management,
  Measurement, Modeling, and Health Effects
• University of Zagreb, Zagreb, Croatia
• 24 May 2007

2
Objectives

• Report progress for PM and health effects
• Explain ultrafine particles and their
  toxicological/ epidemiological associations
• Identify knowledge gaps and future challenges in
  PM research

3
Air Pollution/Health Issue
http//www.epri.com/
4
Air Quality Decision Making Framework
Emissions (rates, particle size, and composition)
Transport and Transformation
Concentrations in Air (composition, particle
size, health indicator)
Human Exposure (outdoor and indoor)
Human Inhalation
Dose to Target Tissues
Adverse Health Effects

National Research Council, 1998, Research
Priorities for Airborne Particulate Matter I -
Immediate Priorities and a Long-Range Research
Portfolio
5
National Research Council (NRC) Reports (1998,
1999, 2001, 2004)
6
History of Public Policy and PM Science
SCIENCE 1930s-1950s Early Episode
studies 1960s-1980s Ecological mortality and
inhalation tox. studies 1989-mid 1990s New
results from several epidemiologic studies
U.S. PUBLIC POLICY 1955, 1963 Early
national legislation 1967, 1970, 1971 Clean
Air Act, amendments, NAAQS 1987 PM standards
revised, TSP-PM10
Pope and Dockery, 2006, JAWMA, 56(6)
7
History of Public Policy and PM Science
(continued)

• SCIENCE
• 1997
• Vedals Lines that Divide
• Growth in PM and health
• effects research (Vedal, 1997, JAWMA)
• 2006
• Lines that Connect
• Gaps and skepticism (Pope and Dockery, 2006,
  JAWMA)

U.S. PUBLIC POLICY 1997-2002
Promulgation of PM2.5 standards, Legal challenges
argued and largely resolved 2006 New proposed
standards for PM2.5 and PM10-2.5
Pope and Dockery, 2006, JAWMA, 56(6)
8
Particle Size Distribution
Watson, 2002, JAWMA, 52(6)
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Inhalation Properties
Lung deposition peaks at 40-60 for 30 nm
UPTracheal deposition is 20-40 for lt10 nm UP
Chow, 1995, JAWMA 45(5) Phalen et al., 1991,
Radiat. Protect. Dosim. 38(1/3)
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Potential Particulate Matter (PM) Health
Indicators

• Ultrafine, fine, or coarse mass size fractions
• Mass, surface area, or number of particles
• Mass, sulfate, acidity, solubility, or transition
  metals
• Pollens, fungi, molds, or endotoxins
• Synergies with weather or other pollutants

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1997 AWMA Critical Review and Discussion Summary
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What is now no longer true from 1997 Critical
Review?

• weak biological plausibility has been the
  single largest stumbling block to accepting the
  association as causal.
• evidence supporting development of chronic
  illness from long-term particle exposure is
  weak.

Vedal, 1997, JAWMA, 47(5)
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Follow-up on PM and Health Effects

• Bates DV (2000). Lines that connect assessing
  the causality inference in the case of
  particulate pollution. Environ Health Perspect
  10891-2.
• Pope CA III and Dockery DW (2006). Health
  effects of fine particulate air pollution lines
  that connect.

14
2006 Critical Review and Discussion Summary
Pope and Dockery, 2006, JAWMA, 56(6) Chow et
al., 2006, JAWMA, 56(10)
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Key Aspects of 2006 Critical Review

• Short-term exposure and mortality
• Long-term exposure and mortality
• Time-scales of exposure
• Shape of concentration-response function
• Cardiovascular disease
• Biological plausibility

Pope and Dockery, 2006, JAWMA, 56(6)
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Recent Advances in PM Health Effects

• Short term exposure and mortality
• gt100 time series studies single multiple
  cities
• Long term exposure and mortality
• Built around 6-City ACS growing prospective
  data base
• Time scales of exposure
• Varied time scales distributed lags

Chow et al., 2006, JAWMA, 56(10)
17
Recent Advances in PM Health Effects (continued)

• Shape of the concentration response function
• Lack of apparent threshold near-linearity
  through 0
• Cardiovascular disease
• Cardiac events changes in function progressive
  disease
• Biologic plausibility
• Several prevailing theories evidence for
  coherence with toxicology

Chow et al., 2006, JAWMA, 56(10)
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PM10
O3
Air Pollution Health Effects (Percent Excess
Mortality)
SO2
CO
NO2
Stieb et al., 2002, JAWMA, 52(4)
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Mortality risk in Harvard Six-City Study (Cohort
Follow-up)
Kingston
Steubenville
Topeka
Portage
St. Louis
Watertown
Laden et al., 2006. Environ. Sci. Technol., 40(13)
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Changes in Mortality Risk in Exposure
Mortality ()
Days of Exposure
Associated with increments of 10 µg/m3 PM2.5 or
20 µg/m3 PM10 or British Smoke exposure
Pope and Dockery, 2006, JAWMA, 56(6)
21
Cardiovascular Mortality Risks in long-term
exposure
Associated with increments of 10 µg/m3 PM2.5
Pope and Dockery, 2006, JAWMA, 56(6)
22
Both fine and coarse PM induce health effects
EPA ORD, 2004, PM Criteria Document
23
Particle composition changes with size (Fresno,
CA, USA)
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UP Decreases Rapidly with Distance from Roadways
Reponen et al., 2003, J. Environ. Monit.
25
Health Effects of Ultrafine Particles (UP)
The lag (in days) between concentration and
effect CV cardiovascular disease RE
respiratory disease
(Ibald-Mulli et al., 2002, J. Aerosol Med., 15(2))
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Hypotheses on Toxicological Effects of UP

• Inflammatory (i.e., large surface area, react
  with macrophages and epithelial cells)
• Not efficiently removed by macrophages
• Contain or release more toxic free radicals
• Inhibit phagocytosis (i.e., unable to remove
  foreign substances)
• Translocate from lung to other organs via
  bloodstream or lymphatic system
• Effects enhanced by oxidant gases (e.g., ozone)
• Effects are most severe on the elderly and people
  with compromised respiratory tracts (e.g.,
  chronic obstructive pulmonary disease)

27
Conceptual Model of UP/PM and Health Effects
(different pathways)
(Sorensen et al., 2003, Mutation Research 544
(2-3))
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Hypothesis on Interactions between UP and
Respiratory System
(Donaldson et al., 2001, Occup. Environ. Med.,
58(3))
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Summary

• Much progress has been made regarding PM health
  effects
• Evidence of increasing cardiovascular effects in
  addition to pulmonary effects
• Better understanding of pathophysiological
  pathways to link PM-related mortality and
  morbidity
• Increasing research in the health effects of
  ultrafine particles

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Knowledge Gaps

• Compliance air quality networks need to be
  designed for epidemiology studies. (Measurements
  at central site may not represent general
  population exposure.)
• Particle types and concentrations in
  toxicological studies are much higher and not
  representative of ambient air.
• Toxicological studies need to establish
  associations from animal subjects to humans.

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Challenges Ahead

• Enhance air quality monitoring for research
• Assess toxicity of PM components
• Investigate health effects of long-term exposure
  to air pollutants
• Formulate multi-pollutant research programs

Simmons et al., 2004, NRC
32
Challenges Ahead (continued)

• Integrate across disciplines
• Design collaborative research
• Prioritize funding to multidisciplinary teams
• Encourage fellowships/sabbaticals
• Conduct joint workshop/meeting and publish
  proceedings and peer-reviewed summaries

Simmons et al., 2004, NRC