2011 Progress Report: A National Study to Assess Susceptibility, Vulnerability, and Effect Modification of Air Pollution Health Risks

EPA Grant Number: R834798C005
Subproject: this is subproject number 005 , established and managed by the Center Director under grant R834798
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Air Pollution Mixtures: Health Effects across Life Stages
Center Director: Koutrakis, Petros
Title: A National Study to Assess Susceptibility, Vulnerability, and Effect Modification of Air Pollution Health Risks
Investigators: Dominici, Francesca , Bell, Michelle L. , Schwartz, Joel , Zanobetti, Antonella
Institution: Harvard University
EPA Project Officer: Ilacqua, Vito
Project Period: January 1, 2011 through December 31, 2015 (Extended to December 31, 2016)
Project Period Covered by this Report: January 1, 2011 through June 30,2011
RFA: Clean Air Research Centers (2009) RFA Text |  Recipients Lists
Research Category: Health Effects , Air

Objective:

This national study is aimed at identifying factors that explain the heterogeneity of health risks associated with air pollution exposure. We hypothesize that such factors include medical and social conditions, conditions that modify exposure, and differences in pollution composition that modify exposure toxicity. Moreover, we hypothesize that the relevant factors vary among different health outcomes. Our research will be fully interactive with the other Center projects. Our previous results (e.g., diabetic susceptibility) have guided their analyses, and their results have generated specific hypotheses that we will test.  We have three objectives. In Aims 1 and 2, we will conduct national studies of short- and long-term exposures to individual pollutants, sources, and mixtures. A main focus of our Center is to study established cohorts (NAS, Framingham, and Viva) in Massachusetts and surrounding states using novel, validated approaches to assess exposure. In Aim 3, we will complement those cohort studies, by establishing a cohort of 2.3 million Medicare enrollees residing in the same region and following its members prospectively for cause-specific hospital admissions and mortality for the period 2000-2014, and also by studying all live births in Eastern Massachusetts, geo-coded to exact address and followed for adverse birth outcomes.

Progress Summary:

Project 5 has three aims, and progress is reported for each aim.

Aim 1. Develop statistical methods and conduct national studies to estimate mortality and hospitalization risks associated with short-term exposures to individual pollutants, source types and air pollution mixtures.

  • We almost have completed a manuscript entitled “Effect modifiers of health effect estimates for short-term exposure to ozone and particulate matter: a review” by Antonella Zanobetti, Michelle L. Bell, and Francesca Dominici. In this manuscript, we review recent literature to summarize the state of scientific evidence on effect modification and identify consistencies across studies. We focus on time series and case-crossover studies of the effects of short-term exposure to PM or ozone on mortality and morbidity.
  • We almost have completed a manuscript entitled “Identifying the most harmful chemical components of fine particulate air pollution in 118 U.S. counties: 2000 to 2008” by Christopher Barr, David Diez, Yun Wang and Francesca Dominici. In this manuscript, we extend state-of-the-art Bayesian statistical models to identify specific combinations of constituent pollutants most harmful to a Medicare population aged 65 and older in each of 118 individual U.S. counties. Our stochastic search variable selection (SSVS) method allows us to accurately and flexibly evaluate many possible regression models in each county. We consider for inclusion the six most common pollution components (sulfate, nitrate, silicon, elemental carbon, organic carbon, and sodium ion) to identify the combination of pollutants most supported by the data. We interpret the full results within the emerging context of multi-pollutant regulation, and highlight the potential for these findings to power regulatory efforts that focus on specific sources within individual counties. Complete results and extensive tools for evaluation of reproducibility are made freely available online.

Aim 2. Develop statistical methods and conduct national studies to estimate mortality and hospitalization risks associated with long-term exposures to individual pollutants, source types and air pollution mixtures. We have submitted a manuscript, entitled “An approach to multipollutant accountability research using principal stratification.” We also will present this work at the September 2011 International Society for Environmental Epidemiology (ISEE) conference in Barcelona (see reference below).  In this manuscript, we introduce a potential-outcomes framework for accountability research that uses a Bayesian Markov chain Monte Carlo (MCMC) computational strategy. The approach stratifies areas based upon the estimated causal effect of an air quality regulation on ambient air pollution and assesses the causal effect of the regulation on health outcomes within these strata. As regulations may affect concentrations of many interrelated pollutants, we extend the use of principal stratification to a multi-pollutant approach that accommodates a multivariate intermediate response vector. Furthermore, we make use of recent advancements in hierarchical modeling for point-referenced spatial data to capitalize on information contained in the geographic locations of the pollution measurement sites. Insofar as these methods rely on unobserved potential outcomes, they rely on assumptions regarding associations not identified based on observed data, indicating the importance of sensitivity analyses. We apply our method to examine whether the 1990 Clean Air Act Amendments causally affected Medicare mortality through affecting ambient concentrations of particulate matter and ozone.

Aim 3. Conduct two cohort studies in Massachusetts and surrounding states to estimate health risks associated with long-term exposures to individual pollutants, sources, and air pollution mixtures. We currently are developing the data set and conducting exploratory analyses to estimate the long-term effects of PM2.5 on lung cancer hospital admissions.

Future Activities:

Aims 1 and 2: Continue analysis of national short- and long-term exposures to individual pollutants, sources, and mixtures. 

Aim 3: Continue development and analysis of a cohort of Medicare enrollees in Massachusetts and surrounding states for cause-specific hospital admissions and mortality; studying all live births in Eastern Massachusetts, geo-coded to exact address and followed for adverse birth outcomes.   

Journal Articles:

No journal articles submitted with this report: View all 60 publications for this subproject

Supplemental Keywords:

national studies, air pollution, heterogeneity, vulnerability, susceptibility, Scientific Discipline, Air, air toxics, Health Risk Assessment, Air Pollution Effects, Biochemistry, Biology, ambient air quality, children's health, complex mixtures, health effects, sensitive populations, air pollutants, biological sensitivities, exposure and effects, lung epithelial cells, susceptible populations, chemical composition, neurotoxicity, toxicity, coronary artery disease, cardiopulmonary, cardiotoxicity, environmental effects, human health, mortality

Progress and Final Reports:

Original Abstract
2010 Progress Report
2012 Progress Report
2013 Progress Report
2014 Progress Report
Final Report


Main Center Abstract and Reports:

R834798    Air Pollution Mixtures: Health Effects across Life Stages

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R834798C001 Relative Toxicity of Air Pollution Mixtures
R834798C002 Cognitive Decline, Cardiovascular Changes, and Biological Aging in Response to Air Pollution
R834798C003 Identifying the Cognitive and Vascular Effects of Air Pollution Sources and Mixtures in the Framingharn Offspring and Third Generation Cohorts
R834798C004 Longitudinal Effects of Multiple Pollutants on Child Growth, Blood Pressure and Cognition
R834798C005 A National Study to Assess Susceptibility, Vulnerability, and Effect Modification of Air Pollution Health Risks