Transcript Ultrafine Particles and Health Effects

Health Effects of Suspended
Particulate Matter
Judith C. Chow ([email protected])
John G. Watson
Desert Research Institute
Reno, Nevada, USA
Presented at:
The Workshop on Air Quality Management, Measurement,
Modeling, and Health Effects
University of Zagreb, Zagreb, Croatia
24 May 2007
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
Air Pollution/Health Issue
http://www.epri.com/
Air Quality Decision Making
Framework
Emissions
(rates, particle
size, and
composition)
Human
Exposure
(outdoor
and indoor)
Transport
and
Transformation
Human
Inhalation
Concentrations in
Air (composition,
particle size,
health indicator)
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
National
Research
Council
(NRC)
Reports
(1998, 1999,
2001, 2004)
History of Public Policy and
PM Science
SCIENCE
U.S. PUBLIC POLICY
1930s-1950s
Early Episode studies
1955, 1963
Early national legislation
1960s-1980s
Ecological mortality and
inhalation tox. studies
1967, 1970, 1971
Clean Air Act, amendments,
NAAQS
1989-mid 1990s
New results from several
epidemiologic studies
1987
PM standards revised, TSP-PM10
Pope and Dockery, 2006, JAWMA, 56(6)
History of Public Policy and
PM Science (continued)
SCIENCE
U.S. PUBLIC POLICY
1997
Vedal’s “Lines that Divide”
Growth in PM and health
effects research (Vedal,
1997, JAWMA)
2006
“Lines that Connect”
Gaps and skepticism
(Pope
1997-2002
Promulgation of PM2.5
standards, Legal challenges
argued and largely resolved
2006
New proposed standards for
PM2.5 and PM10-2.5
and Dockery, 2006, JAWMA)
Pope and Dockery, 2006, JAWMA, 56(6)
Particle Size Distribution
10
PM 10
Relative Mass Concentration
PM 2.5
Ultrafine (PM 0.1)
8
Nanoparticles
(PM 0.01)
Condensation
Mode
6
Droplet
Mode
4
2
Condensed
Organic
Carbon or
Sulfuric Acid
Vapors, Clean
Environment
Fresh High
Temperature
Emissions,
Organic
Carbon,
Sulfuric Acid,
Metal Vapors
Nucleation
Aitken
Sulfate, Nitrate,
Ammonium,
Organic Carbon,
Elemental Carbon,
Heavy Metals, Fine
Geological
Geological
Material, Pollen,
Sea Salt
Accumulation
Coarse
0
0.001
0.01
0.1
1
Particle Aerodynamic Diameter (µm)
10
100
Watson, 2002, JAWMA, 52(6)
Inhalation Properties
Lung deposition peaks at 40-60% for 30 nm UP
Tracheal deposition is 20-40% for <10 nm UP
120
Rest
Normal
Exercise
Deposition (Percent)
100
80
Mouth (ISO)
Nose
Lung
60
40
20
Trachea
0
0.01
0.1
1
10
100
Particle Aerodynamic Diameter (microns)
Chow, 1995, JAWMA 45(5); Phalen et al., 1991, Radiat. Protect. Dosim. 38(1/3)
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
1997 A&WMA Critical Review
and Discussion Summary
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)
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 108:91-2.
• Pope CA III and Dockery DW (2006).
“Health effects of fine particulate air
pollution: lines that connect.”
2006 Critical Review and
Discussion Summary
Pope and Dockery, 2006, JAWMA, 56(6); Chow et al., 2006, JAWMA, 56(10)
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)
Recent Advances in PM Health
Effects
• Short term exposure and mortality
– >100 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)
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)
PM10
Air Pollution
Health Effects
O3
(Percent Excess
Mortality)
SO2
CO
NO2
Stieb et al., 2002, JAWMA, 52(4)
Mortality risk in Harvard Six-City
Study (Cohort Follow-up)
Mortality Risk Ratio
1.4
1.3
Kingston
1.2
Steubenville
Topeka
1.1
1.0
Portage
St. Louis
0.9
Watertown
0.8
0.7
0
5
10
15
20
25
30
35
PM2.5 (mg/m3)
Laden et al., 2006. Environ. Sci. Technol., 40(13)
Changes in Mortality Risk* in Exposure
10
9
10 Euro cities, resp
Dublin, resp
8
7
Daily time-series vs.
long-term cohort,
all cause
%
Mortality (%)
6
Dublin, cardio
5
10 US cities,
all cause
4
Utah Valley, all cause
3
Dublin, all cause
2
10 Euro cities,
cardio
1
10 Euro cities,
all cause
0
1
2
5
20 30 40
180
390
(6 mo) (13 mo)
3653
(10 yrs)
of Exposure
Figure 1. Comparison of %Days
change
in risk of mortality associated with
3
3
an
increment
of
10
mg/m
PM
or
20
mg/m
or BS estimated
3 for
2.5
*Associated with increments of 10 µg/m3 PM
PM10
2.5 or 20 µg/m PM10 or
different
time scales
of exposure (approximate numberPope
of and
days,
log scale).
British
Smoke
exposure
Dockery, 2006, JAWMA, 56(6)
RR (95% CI)
1.6
1.5
1.3
1.2
Cardiovascular
(Laden et al. 2006)
1.7
ACS multi-city cohort
Associated with increments of 10 µg/m3 PM2.5
ACS LA cohort
Fatal Cardiovascular (Miller et al. 2004)
1.8
Non Fatal Cardiovascular
(Miller et al. 2004)
Ischemic HD (Jerrett et al. 2005)
Harvard Sixcites cohort
Cardiopulmonary
(Jerrett et al. 2005)
Dysrhythmias, Heart failure,
Cardiac arrest (Pope et al. 2004)
Ischemic HD (Pope et al. 2004)
Cardiovascular (Pope et al. 2004)
Cardiopulmonary (Pope et al. 2002)
Cardiopulmonary (Pope et al. 1995)
1.4
Cardiopulmonary
(Dockery et al. 1993)
1.9
Cardiovascular
Mortality Risks* in long-term exposure
Women's Health
Initiative
1.1
1.0
0.9
Pope and Dockery, 2006, JAWMA, 56(6)
Both fine and coarse PM induce health effects
EPA ORD, 2004, PM Criteria Document
Particle composition changes with size
(Fresno, CA, USA)
UP Decreases Rapidly with Distance
from Roadways
Reponen et al., 2003, J. Environ. Monit.
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))
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)
Conceptual Model of UP/PM and
Health Effects (different pathways)
(Sorensen et al., 2003, Mutation Research 544 (2-3))
Hypothesis on Interactions between
UP and Respiratory System
(Donaldson et al., 2001, Occup. Environ. Med., 58(3))
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
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.
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
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