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Public health and components of particulate
matter:The changing assessment of
black carbonComments on the 2014 Critical Review
Dan Greenbaum, PresidentHealth Effects Institute
AWMA MeetingLong Beach California
June 25, 2014
Trusted Science ● Cleaner Air ● Better Health
An Excellent Compendium
• What is Black Carbon?• Discusses pros and cons of different
measurements• An appropriate focus on how to measure
exposure• A wide-ranging review of largely short
term epidemiology and toxicology results
An appropriate focus on diesel, with acknowledgement of the recent improvements
Data from HEI’s Advanced Collaborative Emissions Study (ACES): Evaluating Emissions of 2007 – 2010 Advanced Technology Diesels
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Dramatic Reductions(Khalek, et al JAWMA 2011)
- 98% reduction in mass- 90% - 99% reduction in Ultrafine Particles- Substantial reduction in carbon particles
Important identification of developing country sources
e.g. many sources of BC in Asia
And significant PM effects (GBD 2010)
3.2 million premature deaths (2/3 in Asia)
A Key Challenge: Long Term Effects
• Most public health and cost-benefit assessments rely on long-term studies
• The Critical Review cites a wide range of studies• But only two major cohort long term studies (Lipfert
Veterans cohort; Brunekreef Dutch cohort)• HEI’s Traffic Effects Review (2010) found suggestive
(not causal) evidence of longer term CVD mortality• Cohorts report much larger relative risks
• Likely to be different biological mechanisms
A Key Challenge:Placing BC in the larger PM
Context• BC important, but clearly not the only
component of PM• And BC exists with a number of gases as well
• The authors correctly suggest applying EPA’s “causality” framework
• But do not quote EPA’s own conclusion:
“Overall, the results indicate that many constituents of PM can be linked with differing health effects and the evidence is not yet sufficient to allow differentiation of those constituents or sources that are more closely related to specific health outcomes.” (Emphasis Added; Final EPA PM ISA December 2009)
Critical Review: Some things missing…
• The latest science on Black Carbon• E.g. Bond et al JGR May 2013
• HEI’s NPACT Studies (October 2013)• Lippmann M, Chen L-C, Gordon T, Ito K, Thurston GD.
2013. HEI Research Report 177. National Particle Component Toxicity (NPACT) Initiative: Integrated Epidemiologic and Toxicologic Studies of the Health Effects of Particulate Matter Components
• Vedal S, Campen MJ, McDonald JD, Kaufman JD, Larson TV, Sampson PD, Sheppard L, Simpson CD, Szpiro AA. HEI Research Report 178. National Particle Component Toxicity (NPACT) Initiative Report on Cardiovascular Effects.
Bond et al June 2013- The most comprehensive review to date on sources and transport of BC…- Understanding has changed substantially since 2004
NPACT: A Systematic and Integrated Approach : Toxicology
NYU = 4 (+ 1) sites, 6-month CAPS exposures ApoE -/- mouse LRRI = Albuquerque, 50-day defined exposures ApoE -/-
mouseSeattle: Strong wood smoke signal, little sulfate,
Albuquerque (LRRI):
Lab studies of vehicles, secondary sulfate, nitrate, road dust
Irvine:
Few sulfates, strong traffic (gasoline)
New York City:
Strong traffic (diesel) and sulfates
Tuxedo, NY:
Rural, little traffic, strong sulfate
East Lansing:
Suburban mix of sulfates, vehicles
Lippmann – animal inhalation (Chen)
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Short-term
Long-term
Strongest CVD Effects in East Coast/Midwest Cities (with SO4 and Traffic)
Lippmann – ACS cohort (Thurston)
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without covariates with covariates
Note that only significant and marginal associations are shown
Results for EC and Traffic were sensitive to the inclusion of covariates in the analyses
Vedal toxicology (Campen)(A combination of solid particles and MV
gases?)
EXPOSURE
TBARS (aortic lipid peroxidation)
Oxidized lipo-protein
Plaque area
Plaque inflammation
Vaso-constriction
MVE ++++ +++ + +++ ++
MVE gases +++ + +
Sulfate + + + +++
Sulfate + MVE gases +++ +++ ++
Nitrate +++ +
Nitrate + MVE gases +++ +++ +++
Road dust +
Road dust + MVE gases ++ + 13
Vedal – MESA cohort
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PM2.5, Sulfur, and OC Associated with Carotid Intima Media Thickness (NOT EC or silicon)
No significant associations with Coronary Artery Calcium
Vedal – WHI-OS cohort
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PM2.5, Sulfur, and OC Associated with CVD Events (NOT EC or silicon)
Vedal – WHI cohort
Coherence of NPACT Study Findings
Source or Component
NYU Time Series
NYU Cohort NYU Toxicology UW Cohort UW/Lovelace Toxicology
Motor Vehicle/ ”Traffic”
EC in cold season
EC, Traffic Factor
Motor Vehicle Exhaust
“Coal Combustion” Sulfate in cold season
Coal Factor, Sulfur
Long-term Coal Factor, Sulfur
Sulfur/Sulfate (related?)
Secondary Organic Aerosols
OC in cold season
OC
Sulfate Sulfate in cold season
Sulfur Long-term Sulfur
Sulfur/Sulfate Sulfate and Sulfate + MVE
Transition Metals Cold season Short-term
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NPACT Conclusions• The NPACT studies are the most systematic
effort to combine epidemiologic and toxicologic analyses of the health effects of PM components to date
• The studies found associations between health effects and sulfate particles (primarily from coal combustion) and, to a somewhat lesser extent, traffic sources
… but the HEI NPACT Panel concluded that the studies do not provide compelling evidence that any specific source, component, or size class of PM may be excluded as a possible contributor to PM toxicity.
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Concluding Thoughts on the Review…
• A Very Good Job…• Large number of studies reviewed• Careful attempt to look at how exposure
estimated• Some Challenges as well
• Few Long Term Studies• Not Placed in broader PM context• Key studies missing
• Bond et al June 2013• NPACT October 2013