Public health and components of particulate matter: The changing assessment of black carbon

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

3

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• But do not quote EPA’s own conclusion: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

NPACT: Long Term Epidemiology in Over

100 Cities

Lippmann – animal inhalation (Chen)

11

Short-term

Long-term

Strongest CVD Effects in East Coast/Midwest Cities (with SO4 and Traffic)

Lippmann – ACS cohort (Thurston)

12

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

14

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

15

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

16

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.

17

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

Thank You!

[email protected]