2011 Progress Report: Analytical Strategies for Assessing Cumulative Effects of Chemical and Nonchemical Stressors

EPA Grant Number: R834580
Title: Analytical Strategies for Assessing Cumulative Effects of Chemical and Nonchemical Stressors
Investigators: Lai, Dejian , Linder, Stephen H. , Sexton, Ken , Peek, M. Kristin , Cutchin, Malcolm , Stowe, Raymond
Institution: The University of Texas Medical Branch - Galveston , The University of Texas at Austin , Microgen LLC , The University of Texas at Houston , University of Minnesota , University of North Carolina at Chapel Hill
Current Institution: The University of Texas at Houston , Microgen LLC , The University of Texas Medical Branch - Galveston , The University of Texas at Austin , University of Minnesota , University of North Carolina at Chapel Hill
EPA Project Officer: Hahn, Intaek
Project Period: June 1, 2010 through May 31, 2014 (Extended to May 31, 2015)
Project Period Covered by this Report: October 1, 2010 through December 31,2011
Project Amount: $555,923
RFA: Understanding the Role of Nonchemical Stressors and Developing Analytic Methods for Cumulative Risk Assessments (2009) RFA Text |  Recipients Lists
Research Category: Human Health

Objective:

The key research question is: How does the spatial distribution of ambient chemical exposures across neighborhoods interact with nonchemical stressors at both the neighborhood and individual levels to account for observed differences in adverse health effects? These adverse effects are captured through biologic markers of allostatic load, cardiovascular risk, hormonal stress response, inflammation, and organ dysfunction. From the quantification of this complex interaction, we will have a better understanding of the relationship between chemical and non-chemical factors and will be able to construct more reliable measures of cumulative risk for targeted reduction and mitigation.

Progress Summary:

We are midway through a nine-step sequence of tasks and activities. The first four steps have to do with the complex modeling that is the core of our project. This is what we are working on now. Modeling is accomplished in three rounds. In round one, data on chemical exposures are collected and integrated with responses and attributes from our sample survey for Texas City. Fortunately, the National-scale Air Toxics Assessment for 2005 was completed last Spring and gives us a set of modeled exposure estimates that are perfectly timed with our survey responses. We also need to consider monitoring data for ozone and particulate matter. There are three monitors in Texas City, generating daily and weekly estimates for analysis. Finally, we need to gather data from the state’s permitting authority on upset events; these are unplanned releases of air toxics by point sources that contribute to an area’s acute chemical exposures. We also are including daily allergen counts as an important respiratory factor, contributing to stress. Once these data are compiled and checked, we begin to group measures and indicators together into measurement models. This step is in process, since these models are revised throughout our testing. Upon completion of this measurement round, we construct a model that captures the effects, pathways, and relationships that connect these exposure and survey variables to health. We are in the process of testing a series of small-scale models to be sure that we understand how the model works and that our measurement is valid. Once we have a model that fits the data and tells us a consistent story about the relationships (from what we already know from the science), we will move to connecting these results to risk assessment as a strategy for making it more accurate and reliable.

A New Goal: We are examining the relationship between Texas City and four other port/refinery centers on the Gulf Coast of Texas (Brownsville, Corpus Christi, Baytown, Port Arthur) to establish points of reference for comparative risk estimates. It is important to understand where the Texas City riskscape fits relative to other places with similar industrial and demographic characteristics; this becomes especially important for relating our findings on cumulative risk to community assessment procedures that can target mitigation and risk reduction strategies to the areas in greatest need.

A Revised Goal: We had planned to engage community groups once the initial measurement work was finished. Refinements and re-testing are taking longer than anticipated. Consequently, any community interactions must wait until we have some concrete estimates and alternative model pathways to discuss.

Future Activities:

There are three tasks that will occupy the study team over the next year. First, we will continue to apply sensitivity testing to the measurement models for each of our major concepts: social stressors, neighborhood stressors, psychosocial stressors, cumulative environmental stressors and adverse biologic health effects. These models combine variables in complex ways to better summarize their significance for people’s health and enable us to sort out their patterns of influence. Second, we will estimate the formal parameters of our model under different specifications; as variables are added and dropped, and linkages posited and rejected, we get closer to a stable set of relationships and to clarity on how the model’s components behave. Third, once this work is done, attention can turn to why these results matter and how they can best be used to improve risk assessment. This third step will extend to the end of the project and beyond. Eventually, we hope to convert this modeling into procedures useful for identifying risk in other communities and better targeting its reduction and mitigation.


Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other project views: All 17 publications 17 publications in selected types All 17 journal articles
Type Citation Project Document Sources
Journal Article Linder SH, Sexton K. Conceptual models for cumulative risk assessment. American Journal of Public Health 2011;101(Suppl 1):S74-S81. R834580 (2010)
R834580 (2011)
R834580 (2012)
R834580 (2013)
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  • Abstract from PubMed
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  • Journal Article Sexton K, Linder SH. Cumulative risk assessment for combined health effects from chemical and nonchemical stressors. American Journal of Public Health 2011;101(Suppl 1):S81-S88. R834580 (2010)
    R834580 (2011)
    R834580 (2012)
    R834580 (2013)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Full-text: AJPH-Full Text HTML
    Exit
  • Abstract: AJPH-Abstract
    Exit
  • Other: AJPH-Full Text PDF
    Exit
  • Supplemental Keywords:

    cumulative environmental stressors, biologic risk, GLAMM models, laten variable analysis, allostatic load, NATA 2005, upset events

    Progress and Final Reports:

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