Methods for Evaluating the Combined Effects of Chemical and Nonchemical Exposures for Cumulative Environmental Health Risk Assessment.

Cumulative risk assessment (CRA) has been proposed as a means of evaluating possible additive and synergistic effects of multiple chemical, physical and social stressors on human health, with the goal of informing policy and decision-making, and protecting public health. Routine application of CRA to environmental regulatory and policy decision making, however, has been limited due to a perceived lack of appropriate quantitative approaches for assessing combined effects of chemical and nonchemical exposures. Seven research projects, which represented a variety of disciplines, including population health science, laboratory science, social sciences, geography, statistics and mathematics, were funded by the US Environmental Protection Agency (EPA) to help address this knowledge gap. We synthesize key insights from these unique studies to determine the implications for CRA practice and priorities for further research. Our analyses of these seven projects demonstrate that the necessary analytical methods to support CRA are available but are ultimately context-dependent. These projects collectively provided advancements for CRA in the areas of community engagement, characterization of exposures to nonchemical stressors, and assessment of health effects associated with joint exposures to chemical and psychosocial stressors.

Engaging Communities in Research on Cumulative Risk and Social Stress-Environment Interactions: Lessons Learned from EPA's STAR Program.

Studies have documented cumulative health effects of chemical and nonchemical exposures, particularly chronic environmental and social stressors. Environmental justice groups have advocated for community participation in research that assesses how these interactions contribute to health disparities experienced by low-income and communities of color. In 2009, the U.S. Environmental Protection Agency issued a request for research applications (RFA), "Understanding the Role of Nonchemical Stressors and Developing Analytic Methods for Cumulative Risk Assessments." Seven research projects were funded to help address this knowledge gap. Each engaged with communities in different ways. We describe the community engagement approaches of the seven research projects, which ranged from outreach through shared leadership/participatory. We then assess the experiences of these programs with respect to the community engagement goals of the RFA. We present insights from these community engagement efforts, including how the grants helped to build or enhance the capacity of community organizations in addition to contributing to the research projects. Our analysis of project proposals, annual grantee reports, and participant observation of these seven projects suggests guidelines for the development of future funding mechanisms and for conducting community-engaged research on cumulative risk involving environmental and social stressors including: 1) providing for flexibility in the mode of community engagement; 2) addressing conflict between research timing and engagement needs, 3) developing approaches for communicating about the uniquely sensitive issues of nonchemical stressors and social risks; and 4) encouraging the evaluation of community engagement efforts.